AND · 2015. 12. 9. · Partially Melted Zone in Aluminum Welds m Planar and Cellular Solidification C. Huang and S. Kou Solidification theories for metal casting and crystal growth

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PUBLISHED BY THE AMERICAN WELDING SOCIETY TO ADVANCE THE SCIENCE, TECHNOLOGY AND APPLICATION OF WELDING

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T H E F I L L E R M E T A L E X P E R T S

Hobart, McKay, Tri-Mark, and Corex are registered trademarks of Hobart Brothers Company, Troy, Ohio © 1999 ITW Hobart Brothers Company.

FLUX CORED

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T h r e e n e w s o l u t i o n s

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• I)W 329A1' provides smooth bead appearance, minimum spatter and easy slag removal.

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• Spatter-free welding in all-position with 75% A r + 25% C O 2.

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Circle No. 18 on Reader Info-Card

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• MXA-70C6 is metal cored wire for mild steel using Ar + CO 2.

• Provide.,, higher deposition rat(' than ER70~6 solid wire.

• Slag generation is same as a ER70S-6 solid wire.

• With 90% Ar + 10% CO 2, spatter- free welding can be achieved.

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The EPOCH 4 provides the ultimate combination of unsurpassed ultrasonic performance, simplicity of operation, and scope of documentation capabilities. New key features include customizable narrowband filtering, a tunable square wave pulser, and a high PRF rate up to lkHz. Its lightweight of 5.4 Ibs (2.4 Kg) including a high-power NiMH battery, new large high resolution Liquid Crystal Display (LCD) or Electroluminescent Display (ELD), and ease of transducer calibration are unmatched by any other portable flaw detector.

• Customizable narrowband filtering

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• SPECIAL EMPHASIS: SAFETY AND HEALTH

Feature Ar t ic les AWS Website: http://www.aws.org

Monthly Columns

• Positive-Pressure Respirators Increase Productivity and Comfort K. Scheel Respiratory protection programs are evaluated from the viewpoint of increasing employee productivity, comfort and morale/28

• Confined Space Monitors: Tough Choices for Tight Spats D. D. Wagner Choosing an air-quality monitor with the right features is a must for anyone working in confined spaces/31

Design Analysis for Welding of Heavy W Shapes C. Tsai, et al. An investigation into weld splicing of thick plates and rolled shapes comes up with recommendations for avoiding cracking problems/35

• Heads Up on Safety: Use Proper Head and Eye Protection I. H. 01ss0n Know the protective eye and head equipment available and when it is required on the job/43

Welding Research S u p p l e m e n t A Fuzzy Logic System for Process Monitoring and Quality Evaluation in GMAW C. S. Wu, T. Polte and D. Rehfeldt A fuzzy logic system was developed to recognize common disturbances in automatic gas metal arc welding/33-s

Effects of Surface Depression on Pool Convection and Geometry in Stationary GTAW S. H. Ko, S. K. Choi and C. D. You Greater control of bead width and weld penetration will come from a better understanding of weld pool convection/39-s

Partially Melted Zone in Aluminum Welds m Planar and Cellular Solidification C. Huang and S. Kou Solidification theories for metal casting and crystal growth were applied to the study of solidification in the partially melted zone/46-s

Modified Active Control of Metal Transfer and Pulsed GMAW of Titanium Y. M. Zhang and P.J. Li Active control technology is proposed to ensure a repeatable and stable one-drop-per-pulse transfer mode/54-s

Press -Thne News . . . . . . . . . . . . . . 9

Washington Watchword . . . . . . . . 11

Editorial . . . . . . . . . . . . . . . . . . . . 12

Conunen ta ry . . . . . . . . . . . . . . . . . 14

CyberNotes . . . . . . . . . . . . . . . . . . 17

News of the Indus t ry . . . . . . . . . . . 20

New Products . . . . . . . . . . . . . . . . 24

Welding Workbook . . . . . . . . . . . 47

Coming Events . . . . . . . . . . . . . . . 50

Society News . . . . . . . . . . . . . . . . . 55

Guide to AWS Services . . . . . . . . . 73

New Literature . . . . . . . . . . . . . . . 78

Navy Jo in ing Center . . . . . . . . . . . 80

Brazing Q&A . . . . . . . . . . . . . . . . . 81

Stainless Steel Q&A . . . . . . . . . . . . 82

Pe r sonne l . . . . . . . . . . . . . . . . . . . 84

Conferences . . . . . . . . . . . . . . . . . 86

Classifieds . . . . . . . . . . . . . . . . . . 89

Advertiser Index . . . . . . . . . . . . . . 91

Welding Journal (ISSN 0043-2296) is published monthly by the American Welding Society for $90.00 per year in the United States and possessions, $130 per year in foreign countries: $6.00 per single issue for AWS members and $8.00 per single issue for nonmemebers. American Welding Society is located at 550 N.W. LeJeune Rd., Miami, FL 33126-5671; telephone (305) 443-9353. Periodicals postage paid in Miami, FL, and additional mailing offices. POSTMASTER: Send address changes to Welding Journal, 550 N.W. LeJeune Rd., Miami, FL 33126-5671.

Printed by R. R. Donnelley & Sons Co., Senatobia, Miss. Readers of Welding Journal may make copies of articles for personal, archival, educational or research purpose, and which are not for sales or resale. Permission is granted to quote from articles, provided customary acknowledgment of authors and sources is made. Starred (*) items excluded from copyright. WELDING JOURNAL I 7

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W e b s i t e : w w w . g e n s t a r t e c h . c o m

Sumitomo Wins $336 Million Rail Car Order Sumitomo Corp. of America (SCOA), New York, N.Y., re-

cently received a $336 million order for commuter rail cars for use in Illinois. The company, along with Nippon Sharyo, Ltd., will supply 250 new commuter rail cars to Metra, the northeast Illinois commuter rail system based in Chicago.

The order is the largest in Illinois history and one of the largest ever in the commuter railroad industry. Plans call for SCOA to deliver 250 new stainless steel Gallery Type bi-level commuter cars. The car shells will be designed and built by Nip- pon Sharyo with final assembly by Super Steel of Milwaukee, Wis. Metra is expected to exercise its option for 50 additional cars that would raise the contract total to approximately $398 million. Completion date for delivery is 2005. The order is part of a $2 billion improvement plan Metra's board of directors approved last November. Under Metra's "Build Illinois" provi- sion, SCOA will provide a portion of the total contract value to manufacturers and suppliers from Illinois.

Nippon Sharyo, which has annual sales of more than $800 million, has manufactured railroad vehicles for more than 100

years. Since 1980, SCOA and Nippon Sharyo have supplied more than 450 rail passenger cars in the United States.

Sumitomo Corp. of America, in association with Nippon Sharyo, Ltd., will deliver 250 Gallery Type bi-level rail cars similar to the one shown here to Metra, the northeast Illinois commuter rail system.

Campaign Launched to Recruit and Retain Union Pipefitters

The Mechanical Contractors Association of Chicago (MCA), which represents the pipefitting industry in Chicago, recently launched two new programs to recruit new members and keep union pipefitters at the leading edge of industry.

The efforts are part of MC.Ns new campaign "Union Pipe Fit- ters - - Taking on Tomorrow." The two new programs are the MSCA Service Bureau, a recruitment program designed to attract top-quality service technicians to the organization, and the Certified Safety Bureau, which will provide cutting-edge safety training and tracking.

To combat labor shortages found throughout the industry, the MSCA Service Bureau is planning a strong marketing program aimed at qualified technicians. The program will include a series of billboard and cable television ads designed to attract technicians to MCA's program. The organization serves about 400 union mechanical contracting firms through the Piping Educa-

tion Council, whose members employ nearly 8000 Local Union 597 pipefitters.

"We want technicians to ask themselves if they are earning what they are worth in terms of pay and benefits," said MCA executive vice president Stephen Lamb. "MCA is taking the lead in an initiative to ensure that our members are staffed with the best and brightest employees available today." The Service Bureau will provide skills training, serve as a clearinghouse for service- related information and as a labor resource for MCA/s service contractors.

The Certified Safety Bureau will increase the quality, availability and tracking of safety training to union mechanical contractors and their employees. Its backbone will be a computerized database of all approved industry safety training. The training will be provided through interactive computer instruction, classroom training and on the job site through contractor request.

Copper Development Association Names Kireta President and CEO

The board of directors of the Copper Development Associa- tion recently named Andrew G. Kireta, Sr., as the association's president and chief executive officer. He succeeds Robert M. Payne, who retired after ten years of service in that position.

The Copper Development Association is the information, technical and market development arm of the copper and brass industry in the United States. Kireta has been with the organization for 21 years, serving as vice president for tube, pipe and fittings since 1997.

Payne culminates a 40-year career in nonferrous metals that began with Revere Copper and Brass, Inc., at its Baltimore Div.

Michigan Avenue Partners to Acquire Alcoa's Longview Aluminum Smelter

Alcoa Inc., Pittsburgh, Pa., and Michigan Avenue Partners (MAP), Chicago, Ill., recently announced an agreement in which MAP will acquire the 204,000-metric-ton-per-year aluminum smelter in Longview, Wash.

Alcoa was required to sell a 25% interest in Longview as a condition for European Union approval of Alcoa's acquisition of Reynolds Metals Co; instead it will give up 100% of Longview to MAE

The purchase is contingent on financing, is subject to regulatory approvals and is expected to close by the end of the first quarter of this year.

WELDING JOURNAL J 9

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The World Leader!

BY HUGH K. WEBSTER AWS Washington Government Affairs Office

Midnight Regulations Issued at Record Pace

Regulatory activity, primarily in the form of final rules, during the period between the presidential election and the Inau- guration has increased almost 20% since 1948. Regulations issued during this t ime per iod are referred to as "midnight regulations" because agency heads and other officials who are political appointees are like "Cinderellas" who turn back into ordinary citizens upon Inauguration. Once they return to private life, those officials will be without power and unable to effect regulation changes, so they work to push through as many rules as they can before the transition takes place.

President Carter used to hold the record, releasing more than 25,000 pages of midnight regulations between the election and Inauguration, but this was surpassed last month by the Clin- ton Administrat ion, which almost reached the 30,000 page mark.

By far, the leading agency in releasing last-minute regulations in 2000 was the Environmental Protection Agency, which had hoped to issue as many as 88 new rules prior to the change in administrations.

Federal Contractor Rules Finalized The federal government has issued the final version of its

controversial contractor qualification rules. These rules (65 Fed. Reg. 80255) mandate that all federal contractors must have a "satisfactory record of integrity and business ethics" in order to become, or remain, eligible to receive a federal contract. Contractors without a satisfactory record are those who have not complied with labor, employment, environmental, antitrust and consumer protection laws.

The regulations have long been a top priority of organized labor, but are opposed by the business community. Undoubt- edly, a legal challenge will be initiated to question the validity of these regulations.

Record Education Budget Approved Congress passed a record $42 billion education budget as it

adjourned in December of last year. This appropriation is an 18% increase over the previous fiscal year, the largest one-year increase in education funding in the history of the U.S. Depart- ment of Education.

Worker Injury, Illness Rates Decrease Again

Workplace injury and illness rates declined in 1999 for the seventh straight year, according to the U.S. Depar tment of Labor. They have dropped almost 30% since 1992. Further, the

decrease in injuries and illnesses, approximately 4%, is even more impressive in light of the fact that employment overall rose by 2%. Data for 2000 is not yet available.

Congress Fixes Tax Error The Installment Tax Correction Act, passed late last year,

fixed an unintended consequence of an earlier tax bill that restricted the use of the installment of accounting for small businesses. This restriction placed a burden on the sale and purchase of companies, particularly small businesses, by compelling the payment of taxes up front in many instances, rather than over a period of time.

Federal Research Misconduct Defined The Office of Science and Technology Policy has issued a

final policy on misconduct in connection with federal research. The policy is primarily aimed at private companies or universities that perform work pursuant to government contracts. It be- came effective immediately upon release.

"Research misconduct" is generally defined under the policy as "fabrication, falsification or plagiarism in proposing, per- forming or reviewing research or in reporting research results." It does not include, however, "honest error or differences of opinion."

O S H A Celebrates 30 Years The U.S. Occupational Health and Safety Administration

(OSHA) celebrated its 30th anniversary at the end of Decem- ber 2000. Since its creation on December 29, 1970, OSHA has contributed toward the 50% decline in work-related fatalities and 40% decline in occupational injuries. Among its accom- plishments, OSHA cites the establishment of hazard communication, bloodborne pathogen and cotton dust standards, as well as its efforts to reduce brown lung disease.

Significant Government Actions Ranked The Washington, D.C., think tank, The Brookings Institu-

tion, has issued its ranking of the federal government's top 50 greatest achievements since 1944 based on the opinions of more than 400 historians. Number one on the list is rebuilding Europe after World War II, followed by strengthening the nations' highway system and reducing workplace discrimination.

Contact the A WS Washington Government Affairs Office at 1747 Pennsylvania Ave. N. W., Washington, DC 20006; telephone (202) 466-2976; FAX (202) 835-0243.

WELDING JOURNAL I I I

Making Good S.E.N.S.E. In an effort to improve U.S. worker's skills in a variety of fields, including

welding, the U.S. Department of Education awarded a grant to the American Welding Society on July 2, 1993, to develop, organize and operate a business- labor committee that would prepare a skills standard and curriculum leading to an individual becoming an "entry level welder." To accomplish those goals, AWS formed the Education Grant Committee, a broad-based group of AWS members from the business community that included representatives from the welding equipment manufacturing, shipbuilding, aerospace, automotive and general fabrication industries; trade unions; and educators.

The total cost of the project was $1,072,466.85, with the Department of Education funding 49% and AWS the other 51%. In January 1995, AWS was awarded an extension of the grant to develop and prepare additional national skill standards and curriculum guidelines for more advanced training for welders.

Hence, the AWS S.E.N.S.E. - - Schools Excelling through National Skill Standards Educat ion - - program was born. It consists of three voluntary national skill standards for training and qualification of welding personnel (Level I - Entry Level, Level II - Advanced Welder and Level III - Expert Welder) and their associated curriculum guides. The program emphasizes education that produces students who can demonstrate a level of competency in certain identified skills and who are, therefore, more employable.

Following are just a few of the developments pertaining to this widely accepted and popular program:

• As of December 2000, 458 schools participate in S.E.N.S.E. • Kentucky, New Jersey and Ohio have adopted the standards on a

statewide basis. • Companies in the welding industry have contributed to the AWS stan-

dards and have adapted the curriculum for their own use. • The AWS Educat ion Depar tment has produced a S.E.N.S.E. newsletter

for the purpose of exchanging information between AWS and participating organizations.

• The AWS Education Depar tment has also updated its list of all the S.E.N.S.E. schools. The list includes the most current contact information, including e-mail addresses. It will be available for download from the AWS Web site.

When S.E.N.S.E. was first developed, it was decided that each section would be revised and revamped every five years. So, it is now time to take the program to the next level.

A 20-member S.E.N.S.E. Ad Hoc Subcommittee from all facets of the welding industry has been appointed to review and update the current materials. When the committee members have completed the draft copy, they will post it on the AWS Web site (www.aws.org) so you can review it and give your input on the new version at that time. You can send any comments or suggestions you have about the program to the AWS Education Department at (800) 443-9353 ext. 229.

After the committee develops a draft copy, AWS will submit the updated version to the American National Standards Institute for its approval. ANSI approval will lend additional validity to this already highly regarded program.

Your input is important. Af ter all, we want to restore welding as a premier vocation that is financially and personal- ly rewarding.

Robert J. Teuscher. A WS Past President (1999-2000) and Chairman,

A WS Education Committee

2 1 FEBRUARY 2001

A M E R I C A N W E L D I N G S O C I E T Y

Officers

President - - L. W. Myers Consultant

Vice President - - R. L. Arn Teletherm Technologies, Inc.

Vice President - - E. D. Levert Lockheed Martin Missiles and Fire Control

Vice President - - T. M. Mustaleski BWXT-Y 12 LLC

Treasurer - - N. A. Hamers DaimlerChrysler

Executive Director - - E G. DeLaurier, CAE

Directors

O. Al-Erhayem (At Large), JOM Institute

J. M. Appledorn (Dist. 18), The Lincoln Electric Co.

B. J. Bastian (At Large), Benmar Associates

H. J. Bax (Dist. 14), cee Kay Supply

M. D. Bell (Dist. 22), Preventive Metallurgy

H. E. Bennett (Dist. 8), Bennett Sales Co.

B. A. Bernstein (Dist. 5), TechniWeld Lab

S. W. Bollinger (Past President), Consultant.

C. B. Bottenfield (Dist. 3), Dressel Welding Supply

J. C. Bruskotter (Dist. 9), Project Specialists, Inc.

C. E Burg (Dist. 16), Ames Laboratory

S. C. Chapple (Dist. 11), Midway Products Group

G. R. Crawmer (Dist. 6), GE Power Generation Engineering

A. E Fleury (Dist. 2), A. E Vleury & Associates

J. R. Franklin (At Large), Sellstrom Mfg. Co.

J. D. Heikkinen (Dist. 15), Spartan Sauna Heaters, Inc.

J. L. Hunter (Dist. 13), Mitsubishi Motor Mfg. of America, Inc.

M. D. Kersey (Dist. 12), The Lincoln Electric Co.

N. R. Kirsch (Dist. 20), Northeastern Junior College

D. J. Kotecki (At Large), The Lincoln Electric Co.

R. C. Lanier (Dist. 4), Pitt Community College

G. E. Lawson (At Large), ESAB Welding & Cutting Products

V. Y. Matthews (Dist. 10), The Lincoln Electric Co.

G. H. Putnam (Dist. 1), Thermal Dynamics

O. E Reich (Dist. 17), Texas State Technical College at Waco

E R. Schneider (Dist. 21), Bob Schneider Consulting Services

T. A. Siewert (At Large), NtST

R. J. "Pabernik (Dist. 7), The Lincoln Electric Co.

R. J. Zeuscher (Past President), High Plains Fabrication

P. E Zammit (Dist. 19), Brooklyn Iron Works, Inc.

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Com The Benefits of American

National Standards More than any other nation, the U.S. industrial and commercial system is

based on voluntary consensus standards developed by volunteer committees of Standards Developer Organizations (SDOs) such as AWS, ASME and ASTM. In the American system, individuals with a real interest in the subject produce standards from the ground up. In the United States, federal, state or local municipalities may adopt all or parts of a voluntary standard in regulations such as building codes and transit systems. In fact, under the National Technology Transfer and Advancement Act of 1995, federal agencies are directed to use American National Standards (ANS) to satisfy their regulatory requirements. Federal agencies develop their own standards only when suitable ANS don't exist. Outside the United States, governments are involved in standards development to greater degrees.

To accomplish their goal, SDOs must attract consumers, academics and employees of manufacturers and government agencies who are stakeholders in a particular product or process. Stakeholders represent suppliers, consumers and general-interest groups. For example, in structural welding the supplier group includes structural fabricators and erectors and others providing tools or products to them. Consumers consist of owners of structural assemblies, engineering contractors, designers and consultants. General-interest people are academics, government employees (including those who may be regulators) and consultants who are neither suppliers nor consumers.

Standards developed by these groups reflect the goals of all stakeholders, and are scientifically and experience based, safe and affordable. Remember, all standards are safety standards.

The SDO serves as facilitator and policeman. The SDO consists of volunteers and staff members who provide the forum and the rules for the technical committees that actually develop the standard. The rules and procedures must meet those of the American National Standards Institute (ANSI). ANSI Procedures for the Development and Coordination of American National Standards can be found on the ANSI Web page at www.ansi.org.

You may be asking yourself, "So what?" Well, like it or not, your professional life is affected by these committee-developed standards that decide the requirements for industrial products you produce or use. And, furthermore, they affect your personal life, too, such as whenever you purchase consumer products that conform to standards developed by Underwriters Laboratories, Inc.

So maybe you should be more active in the AWS Standards Development Program. AWS publishes more than 170 American National Standards, and these standards are also used internationally.

What are the benefits? You will meet and work with leaders of the welding industry. You will be able to advise your employer of changes that will be occur- ring in the industry. You will develop a network of technically competent people who can help you through problems on your job. You will learn to respect others with a contrary view and to compromise to produce a true consensus.

To apply for committee membership, call (800) 443-9353 ext. 325, or e-mail to [email protected]. You can also sign up on the AWS Web page at www.aws.org by clicking on Technical. Once there, you can comment on published standards or draft standards, learn about upcoming committee meetings and apply for membership on any Technical Committee.

We look forward to hearing from you.

Leonard P. Connor Managing Director, A WS Technical Services

14 I FEBRUARY 2001

WELDING JOURNAL Editorial Staff Publisher

Jeff Weber Editor

Andrew Cullison Features Editor

Mary Ruth Johnsen Managing Editor

Christine Tarafa Associate Editor

Susan Campbell Assistant Editor

Doreen Yamamoto Production Coordinator

Zaida Chavez Peer Review Coordinator

Doreen Kubish Contributing Editor

Bob Irving

Publications, Expositions, Marketing Committee G. D. Uttrachi G.M. Nally Committee Chairman Consultant ESAB Welding & Cutting

R. G. Pali G. O. Wilcox J.P. Nissen Co. Vice Chairman Thermadyne Industries S. Roberts

Whitney Punch Press J. Weber Secretary J. E Saenger, Jr. American Welding Society Edison Welding Institute

P. Albert R.D. Smith Krautkramer Branson The Lincoln Electric Co.

R. L. Arn E D. Winslow, Ex Off. Teletherm Technologies, Inc. Hypertherm

T. A. Barry E.D. Levert, Ex Off. Miller Electric Mfg. Co. Lockheed Martin

Missiles and Fire Control C. E. Boyer ABB Robotics L.G. Kvidahl, Ex Off.

lngalls Shipbuilding T. C. Conard ABICOR Binzel N. Hamers, Ex Off.

DaimlerChrysler D. L. Doench Hobart Brothers Co. S.W. Bollinger, Ex Off.

Consultant J. R. Franklin Sellstrom Mfg. Co. J.C. Lippold, Ex Off.

The Ohio State University N. R. Helton Pandjiris, Inc. W. Gaskin, Ex Off.

Precision Metalforming Association V. Y. Matthews The Lincoln Electric Co. L.W. Myers, Ex Off.

Consultant T. C. Myers DovaTech Ltd. E G. DeLaurier, CAE, Ex Off.

American Welding Society

Advertising Director of Sales

Rob Saltzstein Advertising Sales Representatives

Blake and Michelle Holton 1-800-644-5563

Advertising Production Manager Colleen Beem

Subscriptions Nancy Batista

American Welding Society 550 N.W. LeJeune Rd., Miami, FL 33126 (800) 443-9353 Copyright © 2001 by American Welding Society in both printed and electronic formats. The Society is not responsible for any statement made or opinion expressed herein. Data and information developed by the authors of specific articles are for informational purposes only and are not intended for use without independent, substantiating investigation on the part of potential users.

No flakes! Copper coating on weld wire

can flake and clog gun liners and

tips. Flakes cause reduced arc time due to feedability problems that increase cleaning and repairs,

elevate consumables costs and reduce tip and liner life.

N-S CopperFree" wire r u n s b e t t e r - no f lakes.

N-S CopperFree" carbon steel wire has no copper coating (and no

flakes) so you get more productive

welding time. A unique lubricant

coating reduces N-S CopperFree"

wire's feed force by up to 75% compared to copper-coated wire.

That superior feedability increases arc time and operator control. You

get more welds, and more consistent welds. And no flakes.

N-S CopperFree" wire resists rust and oxidation as well as copper-coated wires, but having no copper coating it minimizes toxic copper fumes.

_QS-9OOO. Circle No. 24 on Reader Info-Card

See for yourself. Get a F R E E spool o f N-S CopperFree wire.

Try N-S CopperFree" carbon steel wire to see its great feedability, without copper flaking. Call your

National Standard Distributor to arrange a free, no obligation

demonstration on your own

equipment. You have nothing to lose but your flakes.

Welding wire to robotic standards

© National-Standard W e l d i n g P r o d u c t s D i v i s i o n

Niles, Michigan Ph: 800-777-1618 Fax: 616-683-9276

www.nationalstandard.com

M A N U F A C T U R I N G A P P L I C A T I O N S E X P O

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May 6-10, 2001 I-X Center Cleveland, OH

FREE EXPO ADMISSION REGISTER BY APRIL 20, 2001. After April 20, bring this registration form to the Expo to receive

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57 [3 Stamping 30 [3 Primary metal products 31 [3 Fabricated metal products 32 [3 Machinery except elect. (inc. gas welding) 33 0 Electrical & electronic equip., supplies, electrodes 34 [3 Petroleum & coal industries 35 [3 Transportation equip.--air, aerospace 36 [3 Transportation equip.--automotive 37 [3 Transportation equip.--boats, ships 38 [3 Transportation equip.--railroad 39 Q Instrument & related equipment 40 [3 Contract construction 41 [3 Chemicals & allied products 420 Utilities 43 [3 Welding distributors & retail trade 44 [3 Misc. repair services (inc. welding shops) 45 Q Educational Services (univ., libraries, schools) 46 [3 Engineering & architectural services (inc. assns.) 47 ~ Misc. business services (inc. commercial labs) 48 [3 Government (federal, state, local) 49 ~1 Other (specify)

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58 [3 Sheet metal fabricating 59~ Spinning 60[3 Finishing 61 [3 Tool & die 62[3 Welding 63Q Slide forming 64 0 Rollforming 65 [3 Coil processing 66 Q Perforating 67 [3 Assembly 68[3 Machining 69 0 Deep drawing 70 [3 Tube/Pipe 71 [3 Advanced materials, intermetallics 72 [3 Aluminum 73 [3 Arc welding 74 [3 Automation 75~ Bending and shearing 76 [3 Brazing and soldering 77 [3 Ceramics 78 0 Computerization 79 [3 Cutting 80 Q Ferrous metals 81 [3 High energy beam processes 82 [3 NDE 83 [3 Nonferrous metals except aluminum 84 [3 Pressure vessels and tanks 85 [3 Punching 86 [3 Resistance welding 87 0 Robotics 88 [3 Safety and health 89 Q Sheet metal 90 [3 Structures 91 [3 Thermal spray 92 [3 Laser Welding 93 [.3 Software/systems 94 [3 Other (specify) 95 [3 None of the above

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this show, please check here and append a statement regarding your disability-related needs. You will be contacted prior to the event. Advance notification is required to ensure availability of appropriate accommodations.

Site Is Doorway to Four Engineering Councils

Information from four New York, N.Y., based engineering councils - - the Materials properties Council, the Welding Research Council, the Pressure Vessel Research Council and the Bolting Technology Council - - can be reached from the same Web site. From the home page, a mouse click links you to pages for each organization.

The Materials Properties Council, Inc. Although some of the material on the site is accessible to council members only, other information is for the general public. The site gives background on the organization, including its goals, history and a list of officers and supporting companies. A user's manual for OmegaPipe'", a software package that performs life assessments on steam piping systems, which can be downloaded as a PDF file, is also on the site.

Synopses of research projects, for example, Repair Welding of Nickel Superalloy Combustion Turbine Blades and Service Exposed Dissimilar Weld Evaluation, are also available.

Welding Research Council. You can read abstracts and purchase WRC bulletins on-line. The Web site also has information on upcoming conferences and committee meetings.

Pressure Vessel Research Council. Besides meeting schedules, workshop details and background about the organization, this area includes a description of council projects and participants, with contact information. A photo gallery of pressure vessel failures is also featured.

Bolting Technology Council. This site emphasizes the benefits of joining the

organization, a list of the industries it serves and its areas of interest. It also includes a history of the council and contact information.

http://www.forengineers.org

Help for Successfully Applying Robotics

Robotics Online is sponsored by the Robotic Industries Association (RIA), a trade group representing approximately 230 robotics suppliers, users, system integrators, research firms and consultants. This site offers page after page of information. In the Tips for Successfully Applying Robotics section, you first click on an application such as arc welding, material handling or dispensing. You are then presented with a wide selection of case studies, articles and technical papers. For instance, in a paper titled Why Automate Your Welding Operation?, Genesis Systems Group offers a checklist that includes the following questions that need to be answered before you purchase a system: "What is the number of units per unit of time? This will help determine how many arcs are required and what the utilization of equipment will be. Number of different assemblies you want to automate on a single cell? As more part numbers are added to a workcell, the tooling and control system may become more complex. Can the operators keep everything straight? What level of foolproof details are required? How often do you change over to run different parts? This can greatly affect the tooling design and cost. Some applications may have many dedicated fixtures, while others may have one

AflYect b ~ e Internet BY MARY RUTH JOHNSEN, Features Editor

fixture with details that are moved." The site features a Buyers' Guide with

product listings, company profiles (often with links to company sites) and an on- line request for bids form. You can also request a free copy of the Robotics Industry Directory. The Educational Resources section offers more technical papers, an on-line bookstore from which you can purchase books and links to organizations that do research on robotics. The site includes details on events, a map to help you navigate, opinion pieces and some information for RIA ]~embers only.

lf~you click onto the Community F o r u ~ section, you can post jobs or a r6sum6 and read tips on how to interview successfully for a job. Its careqr area also includes an article titled Hov~ to Get the Best Jobs in Robotics and Factory Automation, by Jeff H. Chapman. You can also ask and get answers from an automation expert via e-mail, post messages and participate in a live chat or access transcripts of previous chats.

http : / /roboticsonline.org

Site Highlights Welding Wire

National Standard Co. The Web site for this wire manufacturer based in Niles, Mich., offers information on its welding products, bead wire, specialty wire and engineered products segments. The welding wire pages include product descriptions and capabilities. Material safety data sheets are available in PDF format for each wire listed. The pages for the engineered products division, which makes components and materials for the automotive airbag market, has links to related industry associations, publications and other industry sites.

The Web site includes the company's financial statements, both quarterly and annual reports. The News and Events section posts press releases about the company, its products and its involvement with the Save the Children® foundation.

The site offers answers to frequently asked questions, a company history and an on-line literature request form.

http : / /www.nationalstandard.com

WELDING JOURNAL I 17

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Miami, FL 33126 $cholarshi~ are provided by fu~ling from the endowment Scholarship applications available by mail or website.

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News I Industry

USS Cole Returns to the United States for Repairs Two months after the terrorist attack that killed 17 U.S. Navy

sailors and injured 39 others, the USS Cole returned to Litton Ingalls Shipyard in Pascagoula, Miss., to undergo repairs.

The badly damaged Aegis-class destroyer arrived aboard the Blue Marlin, a Norwegian heavy-lift ship. A shroud covered the gaping hole left by the explosion that occurred when suicide bombers ran into the ship as it was being refueled in Aden, Yemen, October 12, 2000.

The USS Cole was built at Ingalls and the ship was christened at the yard before delivery to the Navy in 1996. Many of the same workers who originally constructed the ship will make the repairs. "Ingalls and all of its employees who built USS Cole regret the tragic circumstances that brought the ship back to our shipyard," said Jerry St. Pe', chief operating officer of Litton Ship Systems and executive vice president of Litton Industries, "but we are committed to working with the Navy to return the ship to the fleet in the shortest time possible."

Mike Chapman, general ship superintendent at Ingalls, man- aged the construction team that built the Cole and will perform the same function for the repair team. In an interview December 16, 2000, on National Public Radio's Weekend Edition, Chapman described the Cole's arrival in Pascagoula.

"I was standing on the dock. I watched her come around the corner," Chapman said. "We had looked at a lot of photographs and read a lot of reports on her damage, what she had gone

through, but to see it in person really hit. We were glad to s e e

her, but we wished it had been under different circumstances. We wished she had been coming home sailing proud."

Chapman said repairs are expected to take about a year, approximately one-third the original construction time. "What we're going to do is we'll take out all the damaged decks and bulkheads and equipment, and we will replace all the equipment with newer, updated equipment," he said. "We'll build her back and make her a better ship than she was the first time we put her together."

The first steps in the repair process are to place a watertight patch over the hole, float the destroyer off of the Blue Marlin and move it to dry land. The capability of placing the ship back on land was one reason why the Navy selected Ingalls to make the repairs. "Some aspects of the damage remain unknown and will present challenging engineering problems during the repair," the Navy said when announcing its selection of a repair facility. "The land-level facility at Ingalls provides greater flexibility to deal with major structural damage."

Once the ship is back on land, Ingalls' workers will remove the damaged sections, fabricate huge new ship sections in other areas of the shipyard, then install the new sections aboard ship. Ingalls performed similar repair work on the battle-damaged USS Stark in 1988 - - Mary Ruth Johnsen, Features Editor.

Students Unveil Versatile Vehicle Designs

Three students from the Center for Creative Studies-College of Art and Design in Detroit, Mich., recently unveiled their concepts for the next generation of General Motors' Hummer brand. The designs were developed as part of the 12th annual scholarship program sponsored by the American Iron and Steel Institute (AISI).

The students, Rudolf Gonzalez, East Elmhurst, N.Y.; Marc Senger, Leesburg, Va.; and David Tang, Tenafly, N.J., were required to explore the design possibilities of an expanded Hummer range with the potential for higher manufacturing volume. The students designed with steel in mind, incorporating advancements in high-strength steel, hydroforming and tailor- welded blanks to reduce weight, while maintaining the visual cues that define the Hummer brand. They designed concepts for an expanded product range that included entry-level, mid-level and luxury vehicles, then executed the designs in 3/10 scale clay models.

Tang's entry-level concept implies performance, functionality and industrial strength, and interior room and spacing as unique elements of the design. The design offers lean mass efficiency by incorporating steel technology such as a roll bar made of hydro- formed tubing.

' ~ well-proportioned body with robust detailing is definitely the selling point of this concept," Gonzalez said of his mid-level vehicle design. "Through the use of tailor-welded blanks in the doors and roof, I 'm able to lightweight the vehicle without sacri- ficing structural rigidity."

Senger's concept for a luxury vehicle includes a turbine electric hybrid engine and aircraft-inspired circular styling cues. "My concept symbolizes a move to make driving hybrid vehicles fun


dANUFACTURERS OF CORED WELDING WIRE AND STICK ELECTRODES

We have been told that we are the best-kept secret in the welding industry. In an effort to correct this situation we advise that:

WE MAKE Stainless Cast Iron Cobalt AISI Nickel

410NiMo FC 3 3 % Ni 1 4130 ENiCrFe-2 502 FC 5 5 % Ni 6 4140 ENiCrFe-3 505 FC 9 9 % Ni 12 4340 EniCrCoMo-1 E2553 FC 21 ERNiCrMo-3 E2209 FC 2101 ERNiCr-3 E630 FC 904L FC

THE ABOVE ARE JUST A FEW OF THE CORED WIRES THAT WE MAKE. FOR MORE I N F O R M A T I O N C A L L :


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6 Nozzles ' : , All Stainless Steel 316L ,,

1.00" X 1.25" Bottom feed ~i~,i 1.25" X 1.25" Top feed .... ~ 9' ~

1.00" X 2.50" Top Feed ~ -'~, ~ 1.00" X 4.00" Side Bottom Feed 2.75" X 2.75" Bottom Feed | .... 0.250" Tube Manifold [ ~ I Complete Snake Hugger Spare Screws & Seals L, w"=qW .,d Gas Delivery Kit Plus: Magnetic Base with I ~ ~ J ~ BendablehG~°s~neck I ~ . ~ I " Advanced cover gas-nozzle

WJ'H v V / .~ I ~ ~: : ~ + I system acts like a miniature " ~ --. vL~, [ ' ~ ~ ~ I "Air Hockey" tabe to surround

~,~'~ (7 k¢ t I the weld m argon/,nert gas > ~ ' ~ ' ~ . , ~ 1 ~ " ,MkeHugge, are,ndable • Designed f o r . variety of '-7 "~.~d~=~'~--~ welding cover gas applications,

z~/,,'~, Or deryourSNAKEHUGGERfrom:

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Visit our websile at: wm~ we/dhug~e~ cam

Circle No. 32 on Reader Into-Card

Now Koike Aronson has made automated fillet welding simpler and easier with the new WeI-Handy carriage. It tackles any T-joint over 3 ft. that would benefit from automation. Like I-beams, bridge beams, large tanks and trailer and RV frames,TheWeI-Handy is light - only 18 Ibs. - but it performs like a heavyweight, it self-aligns to the joint and floats along the plate for high accuracy with high automation. So your operator can focus on the arc and not the machine, Your Koike Aronson distributor has all the details,

I ~ KOIKE ARONSON 635 West Main Street Arcade, NY 14009

Circle No. 19 on Reader Into-Card

22 I FEBRUARY 2001

through function," he said. Senger's luxury-level vehicle utilizes hydroforming and rigid, galvanized sheet steel sections to reduce weight; exposed mechanical components for aesthetics and unpainted components that suggest ruggedness.

"The imagination of these students is not only promising, but also very refreshing," said Darryl Martin, senior director, automotive applications, AISI.

Center for Creative Studies students (from lcJ't) RudolJ" Gonzalez, Marc Senger and David Tang exhibit their concepts for Hummer brand vehicles of the future developed as part of the American Iron and Steel Institute intern program.

TWI Uses Laser Welding to 'Sew' Clothing TWI recently conducted a feasibility study for Nigel

Cabourn, a clothing manufacturer in Newcastle, England, to assess the potential for using a laser welding process to manu- facture garments.

In the project, TWI was asked to weld together a shirt, which included putting in buttonholes, pleats in the seams and a collar. The shirt was produced using a low-power diode laser welding process called ClearWeld TM, which uses an almost colorless infrared absorbing medium developed by GENTEX Corp.

"The results of the study were very encouraging and we now plan further research to test this new concept," Nick Sellars of Nigel Cabourn told Connect, a TWI publication. "It opens up a whole range of possibilities in garment design."

The study produced the following results: • Seams were made with little marking of the fabric. • Joints can be made through an upper layer, without visibly

affecting that layer. • Often, seam designs similar to those for stitched seams

may be used. • Only subtle differences exist between the appearance of

welded and stitched seams.

Industry Notes • The Alliance Pipeline commenced commercial service on

December 1, 2000, two months behind schedule. The $2.9 billion pipeline system will transport approximately 1.325 billion ft 3 of natural gas per day from northeastern British Columbia to Chicago. The Alliance Pipeline was the first to use mechanized gas metal arc welding as a primary mainline construction technique in the United States as reported in the November 1999 issue of the Welding Journal. The 2300-mile-long line was originally scheduled to begin service October 2, but construction delays at the Aux Sable fractionalization plant and other problems caused the delay.

3M Has MORE Solutions for Respiratory Protection!

These are some of the many factors to consider when selecting respirators for welding, brazing, soldering and metal pouring. Workers who perform in difficult welding environments have to be comfortable and properly protected. 3M respirators provide better performance in welding environments and address a wide variety of welding requirements. Product offering includes: • Filtering Facepiece Respirators. 3M has a selection

of low-cost filtering facepiece respirators that provide great comfort and protection from metal fumes.

N e w ! 3 M 8515 Welding Respirator

Half and Full Facepiece Respirators. These respirators offer lightweight, easy-breathing comfort. Positive Pressure Respirators. Control your climate. Cool or heat incoming air by 50 degrees! Comfort can lead to increased productivity and worker acceptance.

Look to 3M for the correct respirator solution for your workplace application. For more information on 3M solutions, request our free guide for welding safety by calling the toll-free number below. *Featuring 3M Flame-Resistant Welding Web

I Occupational Health and Environmental Safety Division

3M Center, Building 235-2W-70 P.O. 33275 St. Paul, MN 55133-3275 www.mmm.com/occsafiey

1 800 934-4859

Circle No. 1 on Reader Info-Card Innovation

For more information, circle number on Reader Information Card.

Laser System Cuts and Welds Large Components

The PEDILAS laser system's modular design allows it to be configured to cut and weld. The equipment involves a gantry, or portal system, with 5-axis laser beam movement for integrated cutting or welding of large workpieces. The large work area can be used for processing only or be divided into two sections, one for processing and one for fixturing the next workpiece. The laser resonator travels alongside the system with its own carriage and drive system. This allows the PEDILAS system to have the

and-groove crane rail in the X-axis provides support for the cutting stations. Up to 12 cutting stations are provided, including two plasma stations for oxyfuel and plasma arc cutting, beveling, plate marking, drilling or routing. It incorpo- rates Yaskawa AC brushless motors with digital drive amplifiers, coupled directly to planetary gearboxes. The selected gearbox limits maximum backlash to five arc minutes for improved posit ioning and repeatability. The resolver used for posit ioning feedback is integral to the drive motor, eliminating drive errors or inaccuracies associated with mechanical couplings. A new helical rack travels up to 1500 in./min. The machine offers a choice of seven cutting widths ranging from 8 to 20 ft.

ESAB Cutting Systems 411 S. Ebenezer Rd., Florence, SC 29501-0545

101

high acceleration and deceleration common in laser processing without imposing the high G forces generated by this movement on the laser resonator itself. The working area beneath the Y-axis bridge is open and accessible from both ends.

Schuler Inc. 15300 Commerce Dr. N., S-104, Dearborn, MI 48120

100

Cutting Gantry Has Host of Features

The Avenger 1 gantry shape-cutting machine is equipped with a plasma bevel cutting head, a 200-A precision plasma station and four oxyfuel stations with

flame control. The plasma bevel head combines process automation technology and control software capabilities. The machine features all-welded, stress- relieved, reinforced components with machined contact surfaces, wheels and roller bearings. A large, heavy tongue-

Three-Scale Flowmeter Regulator Has Multiple Features

The H2051 triple-scale f lowmeter regulator for gas metal arc and gas tungsten arc welding has an output of 0-50 standard ft3/h and features a shatter- resistant polycarbonate flow tube. De- signed for at tachment to welding gas cylinders or manifold systems, the H2051 flowmeter regulator provides measure-

24 I FEBRUARY 2001

ment of inlet pressure and shielding gas flow. The flow tube has measuring scales for argon/CO 2, helium or argon and utilizes a high-visibility red flow ball. The adjustment flow control valve ensures gas savings because it locks flow at de- sired settings. Maintenance is reduced with the O-ring valve, which eliminates gas leakage. The rubber ring is used around the threads of the flowmeter instead of soft packing material, which wears out.

Smith Equipment 261) 1 la)ckheed Ave., Watertown, SD 57201-5636

102

U s e r - F r i e n d l y C o n t r o l l e r Des igned for F lex ib i l i ty

The EZ-Link '~' series of controllers are easy-to-use, microprocessor-based controllers that provide flexibility for the operator. Welding and motion functions are coordinated in one package. The front panel layout includes an easy-to- read backlit LCD display. Custom- designed software permits a wide range of programmed sequence configurations. Applications include a controller for longitudinal welding with speed control that has travel start and stop delays that can be preset. Travel carriage, initiation of the weld sequence and weld length can be controlled, and an automatic home sequence can be programmed with the longitudinal controller. The controller for circumferential welding includes preci-

sion lathes, positioner and head-and-tail- stock systems. This controller has features similar to the longitudinal version and automatically adjusts surface travel speed based on the part diameter input by the operator. A pass counter permits multipass welding with an optional limit switch arrangement.

Pandjiris 5151 Nor lhrup A~e., St. Louis, MO 63110

103

B o o m s and Car ts C o m e in A R a i n b o w of C o l o r s

The company's line of heavy-duty booms and carts now come in 12 color options, including Organic Orange, Red

Baron, Blue Streak II, Purple Wave and Yellow Submarine.The new colors are also available on wall and floor mount

accessories. Standard colors - - gray and yellow - - are available at no charge. Booms provide horizontal and vertical

reach and are manufactured from heavy- gauge steel that holds up to 200 lb. There

is a locking device for added safety and 360 deg of rotation with proper ballast. The mounts improve wire feed and or-

ganize a safe work area. The carts make workstations more accessible by organiz-

ing and storing power sources, feeders, gas cylinders and water coolers. Integral to the carts is a 41-gal neoprene-lined

T a k e t h e r o a d to t e c h n o l o g y w i t h t h e ADVENT C o m p u t e r C o n t r o l l e r

The ADVENT Computer Control ler br ings the u l t ima te in technology to the control of hard automation

applications. The system not only controls all the welding parameters but also provides coordinated

control of the various axes of motion.

Eight we ld i ng parameter control - s imul taneously . Coordinated control of s ix axes of mot ion.

Current pu ls ing w i th wave shaping capab i l i t ies . Closed loop control and ful l data acqu is i t i on fac i l i t i es .

Fully in tegra ted f i x t u r i n g for all app l ica t ions . User- f r iendly operator in ter face w i t h high level graphics.

ADVENT Computer Control led hard au tomat ion we ld i ng systems are a product of the Technological Al l iance

between Jet l ine Engineer ing and AMET.

jso Jion,s I 5 GOODYEAR STREET, IRVINE, P-A 9 2 6 I Pl

TEL: ( 9 4 9 ) 9 5 1 - I 5 1 5 • FAX: ( 9 4 9 ) 9 5 1 - 9 2 3 ' 7 EMAIL: SALES@J ETLIN E. P-rt M

WWW.,.IETLI NE.CO M • I I E T L I N E " A U T O M A T I C A L L Y T H E B E B T



tank for ballast or coolant with an optional water circulator pump, a capacity of up to 3000 lb and swivel-front steer- ing and durable rubber tires with cast

iron wheels.

Bernard 104 449 W. Coming Rd., Beecher, IL 60401

Bucket Makes Remote Welding Easier

The company's construction bucket was designed for gas tungsten arc welding operators who work long distances

from the power source. The construction bucket includes a 12.5-ft torch package (choice of 125-, 150- or 220-A air-cooled torch or flex torch, plus work clamp), a 38-ft extension (2-gauge wire) or 88-ft extension (#1/0 wire), PCA-2 power cable connector with rubber boot, Smith flowmeter regulator, welding accessory kit (back cap, collets, collet bodies, nozzles for ~ - or N-in. electrodes) and 10 tungsten electrodes (g2- or ~-in., 2% tho- riated). Packaged in a 6.5-gal bucket, the equipment allows operators to weld up to a 200-ft radius around the power source.It connects a 12.5-ft torch to either a 38- or 88-ft extension of heavy- gauge welding cable and gas hose. For safety, a rubber boot protects all connec-

tions.

Welding Nozzle International 1560 121h St. E., Palmetto, FL 34221

105

W i r e Offers Superior Beads and Pool Control

The Outershield ® 71 Elite gas- shielded, flux cored wire produces a bead in any position and has excellent out-of position pool control. Its fast-freeze slag characteristics make this electrode suitable for applications requiring high deposition rates in the fiat, uphill and overhead positions. Addi t ional features include easy slag removal, low spatter/ fume levels and smooth arc. The wire is available in 0.045-, 0.052- and ¼a-in. di- ameters in packaging that includes 10- and 30-1b spools, a 60-1b coil and a 600-

Vibratory Stress Rel ie f Reduces Res idual Stresses

Due to Welding " F o r m u l a 6 2 " m e t h o d u t i l izes h igh amp l i - t u d e v i b r a t i o n s to r e d u c e p e a k r e s idua l s t resses c l o s e to y i e l d s t ress levels nea r t he w e l d cen te r line. Vibrat ions r emove high tensi le

res idual stresses due to w e l d i n g in fer rous and non- fe r rous metals. S e n d for

f ree b r o c h u r e .

STRESS RELIEF ENGINEERING COmPAnY

1725 M o n r o v i a A v e . , A-1 • Cos t a Mesa, CA 9 2 6 2 7 (949) 642-7820 • FAX (949) 642-0430


lb drum. Typical applications include ships, bridges, barges and offshore plat- forms, as well as general and structural fabrication. It can be used for fillet, lap- joint and butt-joint welds on single- and multiple-pass applications. The elec- t rode was developed for all-position, semiautomatic welding of mild steel and

low-alloy steels.

Lincoln Electric Co. 22801 St. Clair Ave., Cleveland, OH 44117-1199

106

Orbital Welding System Is State of the A r t

The company's orbital welding system provides weld data management features and labor-saving innovations in programming, fixturing and weld documentation. The system is powered by a 486 microprocessor, which enhances programming capabili t ies and can be easily upgraded with new software. Hun- dreds of welding programs can be stored, eliminating the need to re-enter information and improving the opera tor ' s ability to control diameter, root opening and other variables. New programs are easy to create using either a computerized programming interface or a feature that automatically generates programs based on user responses to system prompts. Data can be transferred to

7.6 I FEBRUARY 2001

other computers, improving the ability to analyze and customize reports for doc- umenting quality, cost of welds and more. The portable M100 power supply weighs 37 lb. Other features include Series 20 weld fixtures, which enable one-step fitup of short sanitary fittings for welding, a tube facing tool, for preparing the ends of tubing, fittings and ferrules without damage or contamination to the internal diameter of each component, and a root opening gauge, for maintaining the quality and precision of welds.

Swagelok Co. 107 31400 Aurora Rd . Solon, OH 44139-2764

E r g o n o m i c a l l y D e s i g n e d T o r c h Of fe rs Prec is ion

The Diamond Back torch was designed by the company's engineers and operators for precision and hand comfort. The head of the torch features scal- loped indentations on the right, left and top sides for finger-grip placement. For

precision operators who hold the torch like a pencil, this shape increases control over torch movements while reducing hand fatigue. The back of the handle features a recess where operators can rest their thumb. The torch naturally pivots around this recess, making it easier to walk the cup around the pipe's circum- ference. The handle also features tighter knurling to keep it from slipping out of the operator 's grip. The series includes air-cooled torches rated at 125, 150 and 200 A and water-cooled torches rated at 250 and 350 A, all at 100% duty cycle.

Miller Electric Mfg. Co. 1635 W. Spencer St., Appleton, WI 54912-1079

108

Clarification

The article "A Wise Method for Assessing Arc Welding Performance and Quality," by Dennis Harwig, published December 2000, page 35, contains a Fig. 6 that is a duplicate of Fig. 5. The correct Fig. 6 is printed below.

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Brad| m l m ~a, p I i | ~

m m ~ IMO m I I l lO m Inn I m m

~ t l i ~ tma~ l l e l l t J M i l w i

m

] t: L - I / "-,- i " 1 7 1 - 1 - h i - - t - W 1 I / - , . , . I IIJ it 1 rl 41

. / . . . . . . . I ~ i i ~ l l • l o l I gl

111 so N o ~no an• a m m • ~ , m 4 t 14 ~ • ~ m

Fig. 5 - - Parametric graphs for 1/4-in. fillet welds using a FCA W process.

a ~ r ~

! - "i77" a ~ ~ ' M ~ ~m Im a ~

. . . . ~ i is. ~ ,r, i

lo. le- * / ~

I$. lll-

C u n ~ m, elr,~ ~ ~

f r i l l l i l l l

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. ~-~ i ...... ... ____ ~ ~ ../....~

2D0 W 0 4~0 W 0 M 0 ~ 0 m 0 6 10 115 a0

Fig. 6 - - Parametric graphs for 1~4-in. fillet welds using a GMA W process.


These days, respiratory

protection systems are

a valuable workplace

productivity tool, not just

an expense to ensure

OSHA compliance

BY KEN $ C H E E L

28 I FEBRUARY 2001

F or years, the aim of respiratory protection programs was simply to meet OSHA requirements for workers engaged in welding and other metal finishing applications. Today, however, welding supervisors look

to such programs with a new eye, engaging plant managers and production foremen in discussions about how respiratory protection systems can increase worker productivity, comfort and morale, and actually lower manufacturing costs.

This new focus is particularly important for workers in metal-finishing operations who may be exposed to multiple airborne contaminants. Weld- ing fumes that contain cadmium oxide, manganese, zinc oxide or lead can seriously affect a worker's health, causing metal fume fever, lung and kid- ney damage, pulmonary edema and other conditions. Gases encountered during welding operations, such as ozone, can also damage workers' health.

KEN SCHEEL is in the technical services department of the 3M Occupational Health and Environmental Safety Division (651) 733-1110. He is responsible for positive-pressure respirator systems.

Protection and Productivity Improve

Positive-pressure respirator (PPR) systems, or supplied air respirators with loose-fitting facepieces, hoods or helmets and powered air-purifying respirators, are increasingly being regarded as valuable workplace productivity tools, not just an expense incurred to assure OSHA compliance. In addition to protecting workers' eyes, head and face from airborne contaminants, this equipment can also guard against heat stress when combined with a cooling system. An improvement in employee comfort and, hence, morale can have the added benefit of improving product quality, too. As a result, many industries are reconsidering how best to implement their own respiratory protection programs.

"A well-designed respirator program and the appropriate PPR system enables workers to do more grinding, cutting and welding, and be more efficient in maintenance and repair operations," said Tom Nelson, CIH, former corporate health and safety manager for DuPont and now an industrial hygiene consultant.

Wes Norton, a CIH, CSP with more than 20 years of industrial experience, agreed. "There are numerous industrial operations where positive-pressure respirators are beneficial. When you offer workers a choice between a half-facepiece, negative- pressure respirator and a positive-pressure system with a loose- fitting hood or helmet, they choose the supplied-air system because of the comfort benefits."

Respirator programs that use positive-pressure systems with loose-fitting helmets and hoods are easier to administer, too, according to Jerry Guilliams, a Boeing Co. senior industrial hy- gienist and safety specialist, because the respirators do not require fit testing and users need not be clean-shaven. "Right there, you have eliminated two significant aspects of worker resistance," he said.

While ease of administration is a plus, reducing workers' eye and face injuries-- and sustaining productivity-- is paramount. For example, U.S. Pipe and Foundry in Chattanooga, Tenn., reduced eye injuries by 75% after switching to positive-pressure respirator systems. U.S. Pipe has about 750 employees produc- ing ductile iron fittings, hydrants and valves. Until a few years ago, the foundry's most frequently reported safety problem was foreign matter in the eyes of workers in the grinding department.

Based on the plant's record of worker visits to its first aid room, injuries were significantly reduced after the switch was made. In January 1980, for example, there were 294 visits recorded. In January 2000, the number of visits dropped to 57.

U.S. Pipe's success in reducing eye injuries started several years ago when workers switched from air purifying, half-facepiece respirators to powered air-purifying respirators (PAPR) with a general-purpose helmet and liftable faceshield. In 1999, the Chattanooga plant switched to L-901 PAPR systems with full hardhat protection, a liftable, wide-view lens, and a flame- retardant shroud to help protect workers' shoulders and chests from sparks and other particles. The lightweight headgear is popular with grinders because it can be worn by employees with beards, and because the PAPR unit directs a constant flow of filtered air over the worker's head and face. Because workers feel more comfortable, they take fewer breaks.

Eye Injuries Reduced at Ward Manufacturing

Ward Manufacturing, Blossburg, Pa., employs 1050 workers who produce malleable iron pipe fittings and pipe unions, cast- iron pipe fittings, grooved pipe couplings and a flexible corru-

gated stainless steel tubing for distributing natural and propane gas. Ward's chief respiratory challenge is silica dust as a by-product of its pipe fabrication operations.

'~An engineering control system designed to capture silica dust didn't meet our expectations," Craig Johnson, health and safety manager at Ward said. "The dust problem would occur after the fitting was poured. As the pipe fitting cooled, sand broke free, fell to the vibrating table and then rose into the air."

Employees wore filtering facepiece respirators to protect them from dust because concentrations were below OSHA's permissible exposure limit. Although employees also wore safety glasses, there was still a rash of eye injuries due to circu- lating airborne silica dust. The dust also settled on employees' hair and eyebrows, so when they showered at the end of the day, silica dust would wash into their eyes.

To help reduce eye injuries and increase worker comfort, Ward switched to a supplied air system with loose-fitting headgear. "Since we switched to these respirator systems in April 1997, we've had no eye injuries. None. We're able to provide our workers with Grade D breathing air and at the same time provide a cooling effect. This system has a unit to cool the filtered air before it flows over the head and face. In summer, if it's 90°F outside with high humidity, it is easily more than 100°F in the

Def in i t ions to K n o w

Atmosphere-supplying respirator: A respirator that supplies the user with breathing air from a source independent of the ambient atmosphere, including supplied-air respirators (SARs) and self-contained breathing apparatus (SCBA) units.

Helmet: A rigid respiratory inlet covering that also provides head protection against impact and penetration.

Hood: A respiratory inlet covering that covers the head and neck, and may also cover portions of the shoulders and torso.

Loose-fitting facepiece: A respiratory inlet covering designed to form a partial seal with the face.

Negative-pressure respirator (tight-fitting): A respirator in which the air pressure inside the facepiece is negative during in- halation, compared with the ambient air outside the respirator.

Positive-pressure respirator:. A respirator in which the pressure inside the respiratory inlet covering normally exceeds the ambient air pressure outside the respirator. This includes continuous flow and pressure demand SARs and powered air-purifying respirators.

Powered air-purifying respirator (PAPR): An air-purifying respirator that uses a blower to force ambient air through air-purifying elements to the respiratory inlet covering.

Supplied-air respirator:. An atmosphere-supplying respirator for which the independent source of breathing air is not designed to be carried by the user. This includes continuous flow and pressure demand systems. Also known as airline respirators.

Tight-fitting facepiece: A respiratory inlet covering that forms a complete seal with the face.

Source: OSHA Respirator Standard (29 CFR 1910.134) and ANSI Z88.2-1992.


sort area. By switching to a supplied air system, we've given our workers the benefit of cool filtered air flowing down their faces and across their breathing zone."

Safety and Health Benefits

Positive-pressure respirator systems can have a broad impact on worker protection because they address a variety of workplace issues.

Respiratory protection: Positive- pressure respirators protect workers against particulates, welding sparks, fumes, gas and vapors. These systems are especially useful in welding and grinding work, general maintenance, the utility industry and in industrial paint shops. Health benefits also include the assigned protection factors (APFs) for these systems, which define how much protection a respirator offers against airborne contaminants. The typical negative-pressure, half facepiece has an APF of 10 (i.e., protective against concentrations up to 10 times a substance's permissible exposure limit). Positive-pressure APFs generally range from 25 to 1000.

Eye, head and face protection: Most positive-pressure respirator systems can be equipped with helmets, hoods or loose-fitting facepieces to protect, eyes, head and face. For example, one employer's 10-year study found eye injuries in grinding and chipping operations were reduced 90% when employees wore helmets that covered the whole head and eliminated the need for separate goggles and faceshields.

OSHA compliance: Selecting the appropriate PPR system and accessories can significantly reduce the compliance burden. For example, supplied-air, loose-fitting hoods and helmets do not require fit testing. Furthermore, employees don't have to shave beards and mustaches because PPR systems employing helmets or hoods don't require a tight face seal, as do respirators with either half, or full, facepieces.

Productivity Benefits Positive-pressure systems cost employers about $700 per

worker to outfit an employee in a belt-mounted powered air system with a bumpcap and welding lens. While that initial outlay may seem high, the costs of productivity downtime, poor finished quality, absenteeism and employee turnover can be even more costly.

Workers in foundries or workers exposed to industrial ovens often take a 10-min break for every 30 min of work because of the intense heat. However, a cooling unit that is part of the respirator system can cool the breathing air by as much as 50°E en- abling workers to stay on the job longer. This provides obvious productivity benefits for employers and gives employees on piecework a reason to embrace respiratory protection. A cooling system, which workers regulate individually, can also be used to provide warm air for cold-weather work.

"The ability to individually control the climate is an important benefit," Norton said. "When employees can control the temperature to their own comfort zone, they are more likely to view their working conditions favorably."

Employee Involvement The key to Boeing's successful respiratory protection pro-

gram was having employees test the supplied-air systems and then compare them with negative-pressure, full-face and half- mask respirators, Guilliams said. Even in work areas with ventilation systems that reduce contaminant concentrations below the permissible exposure limit (PEL), employees in the paint shop, chemical processing and maintenance departments chose the supplied-air respirator systems with eye and head protection accessories and an air-cooling unit.

"Involving employees in the selection and providing them with flexible, comfortable equipment has been a huge boost to morale and job satisfaction," Guilliams said. "We have made a strong business case for respirators based on protection, productivity, comfort and morale benefits. With the tight labor market and the need for highly skilled workers, it is more important than ever for our people to be comfortable and happy." •

30 I FEBRUARY 2001

CONFINED SPAC MONITORS: Tough Choices for Tight Spots

Reliable operation and

proper features in a gas

monitor are a must if

you're working

in a confined space

BY D A V I D D. W A G N E R

C onfined space - - j u s t the sound of it appears challenging to those of

us who are even slightly claustrophobic.

Read the Occupational Safety and Health Administration's (OSHA) definition in 29 CFR 1910.146 of a permit- required confined space, "...an area with limited or restricted means of entry and exit; not designed for continuous human occupancy; potential to contain a hazardous atmosphere," and it becomes apparent these areas are somewhat less- than- desirable places to spend the work- day. Unfortunately for many, entry and work in confined spaces is a fact of ev- eryday work life.

Confined spaces exist in almost every

industry and in every workplace. In oil refineries and chemical plants, in power stations and paper mills, in water treat- ment plants and sewer systems, in telecommunications and electric vaults, in hospitals and on farms, on ships, in aircraft and railroad cars confined spaces are too numerous to count. If you are an electrician, plumber, pipe fitter, welder, boiler maker, carpenter, farmer, astro- naut or emergency service worker,

chances are that at some point your daily duties will require you to enter a con-

Working in conJined .spaces poses potential hazards that require special precautions.

fined space and be challenged by the hazards that await there.

Know the Hazards

Some of the hazards in confined spaces are easily recognized. It can be relatively easy to see the potential for falls or entrapment from cave-ins or falling equipment. However, it is the unseen atmospheric hazards that present the greatest danger in a confined space. The lack of breathable oxygen, the potential for explosion due to dangerous levels of combustible gases or the pres- ence of deadly poisonous gas vapors such as carbon monoxide cannot be seen. Therefore, you must rely on the readings

of a portable gas-monitoring instrument to alert you of potential danger.

So, before you drop down that man- hole or crawl into that tank car, here are

some considerations concerning the gas monitor you choose and the procedures you follow to ensure your safety.

Choosing the Right Sensor

Make sure the sensors in the instrument you are using are appropriate for the confined space. Many people consider a confined space monitor to be syn- onymous with a four-gas instrument containing oxygen, combustible gas, carbon monoxide and hydrogen sulfide sensors. While it is true most confined spaces do

DAVID D. WAGNER, Industrial Scientific, Oakdale, Pa., is responsible for all phases of technical support and product management, including driving new product development for portable and fixed system product lines (800) 338-3287.


potentially contain some hazard related to one of these gases, it is not true for all. If you are entering a space that may potentially contain chlorine, an instrument with carbon monoxide and hydrogen sulfide sensors installed will be of little use. Many instruments offer you the ability to change the sensors to match the particular hazard you will encounter. These instruments will provide greater flexibility and value in a wide variety of appli-

cations. The gas-monitoring instrument must

be durable and able to withstand harsh conditions. Although a portable gas detector is certainly a sophisticated piece of electronic equipment, it is still a tool. As such, it is subjected to the rigors of the environment it is used in, just like any other tool. It is dropped, dunked or

caught up in other equipment, and all the while it must still provide a potentially life-saving service. Be certain the instrument you choose is constructed in a manner that will not let its, or your, sur- vival in a tough environment be left to

chance. Confined space pre-entry tests re-

quire remote sampling of the atmosphere from outside the space. There- fore, the instrument you choose must have the capability of using a remote sample pump. Whether the sampling pump is integral to the instrument, or is detachable, is strictly left to your prefer- ence. In either case the pump must have the capabili ty of drawing an adequate sample flow over the distance required to cover the entire space. The pump also should be able to detect and clearly in-

form you if the sample line is blocked, thereby preventing gas flow to the instrument and its sensors.

Be certain that the sample tube material you are using with the pump is of high quality and is compatible with the vapors that you might expect to encounter. Some highly reactive gases like chlorine, nitrogen dioxide or hydrogen chloride may be absorbed into the walls of the tubing and scrubbed from the sample stream. Never use sample tubing made of materials containing silicone rubber compounds. The silicone vapors may off-gas from the tubing and poison catalytic bead type combustible gas sensors, leaving the instrument unable to detect explosive gases. Sample tubing made of urethane or FEP (Teflon ®) is generally suitable for most applications.

Precautions When Welding in Confined Spaces While confined space operations are inherently hazardous,

extra precautions are required whenever welding or cutting is performed in such spaces. Welders can come into contact with any number of different atmospheric hazards, including fluo- rides, zinc, lead, mercury, beryllium, cadmium and toxic cleaning compounds, whose dangers can become exacerbated inside confined spaces. OSHA welding work guidelines describe a confined space as a relatively small or restricted space, such as a tank, boiler, pressure vessel or small compartment of a ship.

OSHA standard 1910.252, outlines general requirements for welding, cutting and brazing, and also directly addresses operat ions in confined spaces. Another OSHA standard, 1915.51, deals with ventilation and protection for welding, cutting and heating, primarily for shipboard work.

Before cutting or welding, spaces must be checked for atmospheric hazards using gas detect ion instruments. Cutting and welding are prohibi ted in confined spaces with explosive atmospheres (mixture of f lammable gases, vapors, liquids or dusts with air), or in spaces that previously contained those materials and that have not been cleaned or properly prepared.

After taking gas detect ion instrument readings, the space must be adequately ventilated with mechanical ventilators to prevent accumulation of toxic materials or possible oxygen de-

ficiency. NEVER use oxygen to ventilate a space. The minimum ventilation rate is 2000 ft 3 (57 m 3) per minute

per welder, except where local exhaust hoods and booths are present, or when airline respirators are used. Vent all hollow spaces, cavities or containers, and take care to observe parti- tions or other barriers that might obstruct cross ventilation.

After ventilation, again take atmospheric readings with gas detection instruments. When the space is ready for entry, the welder must be fitted with any respiratory protection required

(National Insti tute for Occupat ional Safety and Heal th (NIOSH) standard 42 CFR Part 84), safety belts and lifeline; along with other required personal protect ive equipment. A standby at tendant, t rained in preplanned rescue procedures, must be posted outside of the space. The standby a t tendant must maintain visual and verbal communication with the welder

at all times. Some operat ions require work in confined spaces that are

immediately hazardous to life. In such instances, workers must wear a full-facepiece, pressure-demand, self-contained breathing apparatus or a combinat ion full-facepiece, pressure-demand supplied-air respirator with an auxiliary, self-contained

air supply. Other precautions include the following: • Accidental contact. When arc welding is to be suspended

for any substantial per iod of time, such as during lunch, shift change or overnight, all electrodes must be removed from the holders and the holders carefully located so that accidental contact cannot occur. Machines also must be disconnected from

their power sources. • Torch valve. Whenever the torch is not used for a substan-

tial period of time, such as lunchtime, shift change or overnight, . the torch valves must be closed and the gas supply positively shut off at some point outside of the confined space. This action eliminates the possibility of gas escaping through leaks or improperly closed valves. Also, where practical, the torch and hose also should be removed from the confined space.

• Secure cylinders and machinery. Gas cylinders and welding equipment must be left outside of the confined space. Be- fore operat ions are s tar ted, heavy por table equipment mounted on wheels must be securely blocked to prevent acci-

dental movement.

32 ] FEBRUARY 2001

Fig. 1 - - Monitoring should be performed before entering the confined space and during the work operation.

Check the Power

The gas monitor should be able to operate from a variety of power sources. Rechargeable batteries are generally most suitable for portable monitoring instruments because the combustible gas sensors used in the detectors consume large amounts of battery power. Ex- tended confined space operations often

require instrument run times beyond the capacity of the rechargeable batteries. The ability to replace the rechargeable battery pack with disposable alkaline or

lithium battery cells will certainly come in handy in these situations. In addition, make sure that the instrument is capable of running the required amount of time when the sample pump is being used. Some sample pumps use the instrument's battery for power and will reduce the run time of the instrument much more than you might expect.

Know the detection limits of the instrument. There are clear differences in the measuring ranges of sensors in various instruments. As a rule of thumb, the monitor should be capable of measuring

concentrations approaching the immediately dangerous to life and health (IDLH) level of the target gas. All catalytic combustible gas sensors require a minimum background oxygen concen- tration present to respond accurately. Be aware of what that level is and make sure the instrument you choose can be used with a dilution apparatus. By doing so, you will ensure the accuracy of the combustible detector when sampling from inert or oxygen-deficient atmospheres.

Calibrate Often

Beware of claims that instruments do not need to be tested or calibrated on a regular basis. Know one thing for sure: the only way to ensure a gas monitor will respond to gas is to test and verify its operation with known concentrations of the

target gases prior to each use. For example, someone using the instrument before you might have damaged one of the sensors resulting in no difference in the response of a catalytic or electrochemi- cal gas sensor used in a clean atmosphere

Knowing and understanding the

hazards of confined space operations can

save your life.

from one that has failed catastrophically. Regular calibration and functional testing will guarantee the instrument and its sensors are working properly. Whether or not it is done is up to you. If calibration and testing are too difficult and cum- bersome for you to do on your own, dock- ing systems or service programs are available to automatically perform these tasks on your instruments and document the results.

Keep Monitoring

Whether to monitor continuously or not is an often asked question. Usually,

confined space atmospheres are tested before entry to complete the required permits, and then the gas monitor is put back on the truck until the next test. Un- fortunately, the work done while in the confined space may create an unseen hazard. Chemical reactions with solvents during cleaning processes in tanks or vapors produced during maintenance operations such as welding can buildup dangerous gases in a confined space while you work. Continuous monitoring (Fig. 1) of the space's atmosphere dur-

ing the entire entry will ensure there is no potential danger. An instrument capable of activating a remote alarm will

also alert your partner watching from outside of hazardous conditions.

So many choices, so little room for error. Do yourself a favor. Make sure you take time to know and understand the hazards of confined space operations and assure yourself you have the right equipment. It could save your life. •


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Design Analysis for Welding of Heavy W Shapes An investigation evaluated the effects o f weldingparameters and joint geometry on the magnitude and distribution of residual stresses on thick-section butt joints.

BY C. TSAI, D. KIM, J. JAEGER, Y. SHIM, Z. FENG AND J. PAPRITAN

C racking and fracture problems have been associated with groove weld splicing of thick plates and rolled shapes (Ref.

1). Problems were reported in 1981 at the Orange County Con- vention Center in Orlando, Fla. (Ref. 2), and at the American Airlines hangar constructed at Dallas/Fort Worth International Airport in 1988 (Ref. 3). Segregation and slow cooling at the midthickness region of the flange and web intersection causes a reduction in base metal toughness. In addition to reduced toughness, high residual stress (Ref. 4) from nonlinear thermal cycles created by the welding process and geometric irregulari- ties at the weld access holes increase the potential for cracking.

Field experience has shown the welding sequence can have a controlling effect on cracking of heavy, wide flange butt joint connections. When the sequence is such that flanges are welded prior to the web, cracks can initiate from web access holes and propagate through the web material. If the weld sequence is such that the web is welded first, followed by the flanges, cracks again initiate at the web access holes; however, the cracks then tend to propagate through the flange material.

As a recent field case, W36 x 359 rolled shapes from A572 Grade 50 steel were built up into heavy sections to reinforce the guide wall structural system in the Bonneville Navigation Lock (Ref. 5). Because these thick members would be subjected to tensile loads, there was concern for cracking. To provide design guidelines for welding these heavy W shapes, this study performed a finite element model (FEM) analysis to calculate the thermo-mechanicai responses of the weldment to various welding processes and procedures. These thermomechanical responses included transient temperature and strain (or stress) variations of the weldment during heating and cooling periods, and residual stress distribution in the weldment after cooling down to room temperature. Experimental measurements of transient temperature and strain changes during welding and residual stresses in the joint members were conducted to check the validity of the numerical results. These studies resulted in recommendations for improved design and fabrication of thick- shape welded connections.

The finite element studies modeled a W36 x 359 shape, however the experimental investigations utilized W36 x 300 shapes. Although the experimental and test results were based on the W36 x 300 shapes, the structural dimensions of these two materials are similar, as shown in Fig. 1. The thermomechanical responses of these shapes to the welding heat source are also similar. Therefore, comparisons between the finite element analysis

p 4~.s -I

__ m 4¢

949.3 7g0o8

I ~ 2B.6

I I

Fig. 1 - - Dimensions of W-shape jumbo sections (FEM W36 x 359; Experiment W36 x 300).

and the experimental investigations were based on the proxim- ity of these two shapes.

Invest igat ion Var iables and W e l d i n g Processes and P a r a m e t e r s

The variables in this investigation included welding process and parameters, welding sequence, weld access hole geometry and weld joint geometry.

Several welding processes were studied for welding the flanges. They included flux cored arc welding (FCAW), submerged arc welding (SAW) and electrogas welding (EGW). T h e webs were modeled with the FCAW process only. The associated welding parameters included welding current, voltage and travel speed. Typical values of those parameters were assumed for the FEM analysis, as shown in Table 1.

Flanges. The current, voltage and travel speed for the FCAW process for the root pass and second pass were 190 A, 27 V with a travel speed of 6.7 in./min (170.2 mm/min). The remaining

C. TSAI, Y SHIM and J. PAPRITAN are with The Ohio State University, Columbus, Ohio. D. KIM is with Shell Oil Company. J. JAEGER is with the U.S. Army Corps of Engineers. Z. FENG is with Engineering Mechanics of Columbus, Ohio.


Table 1 - - Welding Parameters Used in FEM Analysis

Flange Web

Welding Process FCAW SAW EGW FCAW Current (amps) 190% 250~b, 350 850 200 Voltage (V) 27% 30~b, 30 43 27 Travel speed (in.lmin 6.7% 11 .&b, 20 I 6.7 Number of passes 37% 26,~, 23 I 8 Filler metal dia. (in.) 0.05 6164 0.12 0.05

(a) Root and second pass, (b) remaining passes (c) single-V groove, (d) double-V groove.

passes were deposited with welding parameters of 250 A, 30 V and 11.8 in./min (300 mm/min). The current, voltage and travel speed for the SAW process were 350 A, 30 V and 20 in./min (508 mm/min). The welding parameters for the EGW process were 850 A, 43 V and 1 in./min. Water-cooled copper shoes were used to keep the molten metal in the groove during welding.

Webs. The webs were welded by the FCAW process with welding parameters of 200 A, 27 V and 6.7 in./min.

W e l d Jo in t G e o m e t r y

In this study, the wide flange shapes were joined by a complete penetration groove weld butt joint. Trade Arbed (Ref. 6) and American Institute of Steel Construction (AISC) (Ref. 7) recommend using single-V-groove welds to join the flanges and a double-V-groove weld for the web. Oregon Iron Works (OIW), a fabricator for the Bonneville Navigation Lock project, proposed this recommended joint design (Ref. 5).

The weld joint edge preparation and fit-up details for the flange are presented in Fig. 2. Figure 2D illustrates an alternate double-V-groove weld that was also investigated in this study for possible use in welding the flanges with FCAW. The weld joint edge preparation and fit-up for the web are shown in Fig. 3.

Assuming E71T-1, 0.05-in.-diameter (1.2-mm) electrodes for the FCAW process, it was estimated the double-V-groove web weld required 8 passes to complete. The double-V-groove flange weld required 26 passes while the single-V-groove flange weld required 37 passes for FCAW. For the SAW process with %,-in.- diameter electrodes, a total of 23 passes were used for the single-V flange groove. The other side of the joint was backgouged and rewelded with 6 passes. The EGW process used square butt

2 "

(a) Single-V groove edge for FCAW process

t (b) Single-V groove edge for SAW process

(c) Square-butt groove for EGW process

(d) Alternate double-V groove edge for FCAW process

Fig. 2 - - Flange weld edge preparation and fit-up used in FEM analysis.

9 1 1 6 v ~

Fig. 3 - - Web weld edge preparation and fit-up used in FEM analysis.

~ F C A W WEB :FCAW

a- 1-1/8" 1.2-15116"

a- 1-1/2" 1=4-314"

Ft.,INQE ~

,~ml-tatoulw ~ H a ~ E l o a ~ t o d / m a u a Hole

R.NdGF_: SAW WEB :FCAW

~ ~ ~ ~ave lgufe.

Fig. 4 - -Access hole details used in FEM analysis.

36 I FEBRUARY 2001

Table 2 - - FEM Modeling Case

Case Flange Access hole Joint Welding No. Welding type geometry sequence

1 FCAW 1 '/8 in. dia Single V A 2 FCAW 1 '/8 in. dia. Single V B 3 FCAW 1% in. dia. Single V C 4 FCAW 1 '/2 in. dia. Single V A 5 FCAW 1 '/2 in. dia. Single V B 6 FCAW 1 '/2 in. dia. Single V C 7 FCAW 1 '/8 in. dia. Double V D 8 SAW Elongated Single V A 9 SAW Elongated Single V B 0 EGW Elongated Square butt A 11 EGW Elongated Square butt B 12 EGW Semi-circle Square butt A 13 EGW Semi-circle Square butt B

joints without any joint preparation. The flange was welded uphill by a single pass with a 0.12-in. (3.2-mm) diameter flux-cored electrode.

W e l d A c c e s s H o l e a n d W e l d i n g S e q u e n c e

The weld access hole diameter is an important parameter because it can act as a stress concentrator that promotes cracking. The geometry for the web access holes is shown in Fig. 4 as recommended by Trade Arbed (Ref. 6), AISC (ReL 7) and OIW (Ref. 5) for the respective welding processes.

Because welding sequence can have a significant effect on welding stresses, three different welding sequences were analyzed with FEM.

Finite Element Analysis Temperature-dependent mater ia l propert ies o f . ~ 7 2 Grade

50 were used in the thermal-mechanical f in i te e lement analysis, including thermal conductivity, specific heat, thermal expansion coefficient, Young's modulus, yield stress and strain hardening (Ref. 8).

A total of 13 cases were analyzed (Table 2). The thermal and stress analyses were both modeled as a two-dimensional problem in the plane of the web. Eight-mode quadratic interpolation elements were used for both thermal and stress analyses. The web was treated as unit thickness and the flange treated as unit width in the heat transfer analysis. On the other hand, the flange elements were given a width of 16.75 in. (425.5 mm) with a thickness of 1.125 in. (28.6 mm) used for the web elements for the stress analysis.

Since one of the parameters of interest pertained to effects from varying the diameter of the weld access hole, two finite element mesh designs were used for those cases in which the flanges were welded with the FCAW or EGW processes, while only one mesh was used for the SAW process.

Assuming a condition of symmetry, a quarter of the joint was modeled. The finite element mesh for the P/.-in. (38-mm) diameter weld access hole contained 374 elements (Cases 4--6) while the l~-in. (28.6-mm) diameter weld access hole contained 368 elements (Cases 1-3, 7) for the FCAW process. Only the elongated weld access hole was modeled for the SAW process, which contained 234 elements (Cases 8-9). Two models - - the semicircle and elongated weld access holes - - were considered for the EGW process. They contained 207 elements and 234 elements, respectively (Cases 10-13).

Aclual Welding PMm Lump~ Pasta

7

T 5 Z

7

Fig. 5 - - Actual welding passes vs. lumped passes for single-V- groove weld, FCA W process.

L u m p e d H e a t I n p u t

The heat inputs from welding passes were lumped for cases in which the flanges were modeled with the FCAW or SAW process to make efficient use of CPU time. The background for lumped heat input modeling is discussed in detail elsewhere (Ref. 9).

The flange weld geometry was modeled as a series of stair- stepped elements. The 37 passes required to complete the full penetrat ion single-V-groove flange weld using FCAW were lumped into 8 passes - - Fig. 5. The root and first passes were combined as the first lumped pass. The heat input was then followed sequentially by lumping the remaining passes. Similarly, the 26 passes required to complete the double-V-groove flange weld with FCAW process was modeled as 8 lumped passes being deposited. As the stepping was being performed, only those elements associated with the passes currently being deposited and those that had been previously deposited were considered active at the weld joint. Ten minutes were allowed between each pass. The actual stair step modeling of these lumped passes in the finite element analysis is discussed in detail elsewhere (Ref. 5).

For the SAW process, 23 passes of the single-V-groove flange weld were lumped into a total of 10 heat input passes. The outer groove weld passes were lumped into 6 passes. Backgouging on the other side of the joint was considered as 1 lumped heat pass, but constraints from the root pass previously deposited on the joint were removed from the finite element model to simulate the gauging condition. Weld passes in the gouged groove on the other side of the joint was lumped into 3 heat inputs.

With the EGW process, the flange was welded as a single, up-

Table 3 - - Ramp Heat Input and Heat Flux

Flange Location Lumped tl(s) t2 (s) t3 (s) Heat input/ welding pass weld

length (Btu/in./s)

Flange 1 2.0 7.0 2.0 2.1 2-8 1.0 4.1 1.0 3.0

FCAW Web 1 3.0 12.0 3.0 1.4 2-4 2.0 7.0 2.0 1.9

5 2.0 9.7 2.0 1.7 6-8 2.0 7.0 2.0 1.9

SAW

Flange

Web

1 2 0.8 3.2 0.8 4.0 3-7 0.6 2.4 0.6 4.7

8 0.8 3.2 0.8 4.0 9-10 0.6 2.4 0.6 4.7

1 0.6 2.5 0.6 3.1 2-4 0.7 2.8 0.7 3.5

5 0.6 2.5 0.6 3.1 6-8 0.7 2.8 0.7 3.5

EGW Flange Web

1 5.0 55.0 5.0 8.2 1-8 1.0 4.6 1.0 3.3

W E L D I N G J O U R N A L 137

hill weld pass. Thus, lumping of the welding heat input was not required in the finite element analysis. In addition, no lumped heat input was used in modeling the web weld since it just needed 8 passes to complete.

Sequences A through D were modeled for the FCAW process, whereas only Sequences A and B were used in the EGW and SAW processes.

Ramp Heat Input Function

To represent the transient condition of the welding process the thermal energy was input as a trapezoidal ramp function (Fig. 6) for each lumped pass. The ramp heat input and flux used for each process is given in Table 3. Details of the ramp heat input are discussed elsewhere (Ref. 9).

An are efficiency of 0.85 was assumed for the FCAW process, with 0.95 for the SAW and EGW processes. Preheat and interpass temperature were chosen as 300°F (149°C) for both FCAW and EGW processes, and the ambient temperature was 70°F (21°C). No preheating was modeled for the SAW process, while a 300°F interpass temperature was assumed.

Welding Sequence

Since welding sequence can have a significant effect on welding stresses, three different welding sequences were modeled. The first sequence assumed the flanges were completely welded prior to welding the web. Since the flanges were welded first in this sequence, an edge constraint is developed at the flanges, which restricts shrinkage of the subsequent web weld. Conse- quently, for this welding sequence, denoted as Sequence A, the web weld was modeled with boundary conditions fixing the translation of the edges of the flange along its thickness in the global X direction.

The second fabrication sequence modeled applies to a condition where the web is completely welded first followed by flange welding. This assembly sequence develops a translational constraint in the global X direction along the spliced edge of the web during the flange welding. This second welding sequence is referred to as Sequence B.

Sequence B models a single-V-groove full penetration flange weld with the root opening located at the inside face of the flange. Sequence C is the same single-V-groove weld; however, the root opening is located at the outside face of the flange.

The third procedure modeled is a staggered flange and web welding sequence. In this model, one face of one flange is welded followed by welding one side of the web and then one face of the other flange. This sequence is then repeated to complete the full penetration butt joint. This sequence is referred to as Sequence D.

Heat flux, q

qmax

,, ,,

t I t2 t3

"lime

Fig. 6 - - Ramp heat input.

Stress Analysis

The temperature history obtained from thermal analyses of the various welding processes, sequences and joint geometries were used as thermal loading input for the stress analysis.

Since cracking has been seen initiating at the web and flange access hole interface, which then propagates through either the flange or web plate, residual stresses in the direction of member axis (Sx) along the access hole periphery are of interest.

Figure 7 shows the residual stress plots along the access hole for the FCAW process (Cases 1-3, 7). Tensile stress is plotted as a positive stress value. The access hole diameter is I'A in. For Se- quence A, the maximum tensile residual stress approaches yield stress (50 ksi) near the lower tangent point of the access hole (point C). This result agrees well with cracking problems experienced in the field during fabrication. The tendency in the field for the "flange, then web" welding sequence has been for cracks to initiate from the weld access hole and propagate through the web base metal.

For Sequence B, maximum residual tensile stress is 33 ksi and located at the upper transition tangent of the weld access hole (point B). This also is the area where cracking has been prone to occur in the field when the web is welded prior to the flange. For this welding sequence, the crack tends to initiate near point B and propagate through the flange base material. In addition to high tensile residual stress, the transient thermal stress also reaches yield point in tension at the top of the access hole near the weld (point A) and at the upper tangent point (point B) of the access hole 5. This high transient thermal stress occurs after the initial lumped weld pass (actual weld passes 1 and 2). How- ever, this high tensile transient stress reduces from its initial values by the time the final cap passes are completed. The additional passes deposited to complete the joint tend to produce a more uniform temperature distribution with time near point A and, consequently, lower the final residual stress.

The maximum tensile residual stress of 50 ksi occurs near point B for Sequence C. For the alternating flange and web welding sequence (Sequence D), the maximum residual stress also occurs along the outer edge of the access hole along edge A to B but with a smaller stress value (40 ksi).

To investigate the effect of weld access hole diameter on residual stress, the finite element model was revised from altA - in.-diameter hole to I~A in. No other modifications were made to the thermal or stress analysis. Thermal and residual stress plots were developed along the 1½-in.-diameter weld access hole similar to the l~-in.-diameter model. The residual stress plots for the l~A-in.-diameter weld access holes for Sequences A and B are shown on Fig. 8. Similar results, but with much smaller maximum tensile stress values, can be seen as compared with the ltA - in. access hole case.

Blodgett (Ref. 10) suggested large weld access holes could be beneficial in lowering residual stress. The numerical results indicate that lower maximum tensile residual stress does exist for the larger l~A-in.-diameter access hole geometry.

The SAW and EGW processes were simulated for Cases A and B. Figures 9-11 show the residual stress distributions along the access hole periphery of each simulated joint.

Two types of access hole geometry were simulated for the EGW process. This was to study the effect of interface angle between the flange and web plates. Figures 10 and 11 show the residual stress distribution along the access hole periphery of each simulated case. The elongated hole geometry with a tangent interface resulted in lower residual stress than the normal interface access holes in both Sequences A and B.

38 I FEBRUARY 2001

A B Flange

0 C

I • 3 4 s 6

B C D

D = l m x fm)

I A Flange

__) D C Y

Web W x

m

A

2 4 O ¢ tO

B C D

Di~=¢¢ (in)

Fig. 7 - - Residual stress distribution for FCA W process, 1 V~-in. access hole (Cases 1-3, 7).

Fig. 8 - - Residual stress distribution for FCA W process, 1½-in. access hole (Cases 4, 5).

~D~webCA B Flange

i a 3 4

A B C D

Dimace (~,,)

I A B Flange

ti__ i i i i 4 s

B C D

D i s t a n c e ( i n )

Fig. 9 - - Residual stress distribution for SA W process (Cases8, 9). Fig. 10 - - Residual stress distribution for E G W process, elongated access hole (Cases 10, 11).

Experimental Investigation The actual testing was performed on W36 x 300 shapes,

whereas the finite element analysis utilized W36 x 359 shapes. Five W36 x 300, A52, Grade 50 welded joint coupons were experimentally tested. The difference is the larger W36 x 359 shapes required more welding passes being modeled in the numerical model. However, all other variations, such as joint and access hole geometry and welding parameters, were minimal. Therefore, the thermomechanical responses of the numerical results for the W36 x 359 shape will be similar to those experimentally obtained for the W36 x 300 shape.

The effects on final residual stress and transient thermal strains from the various welding processes, welding sequences, and access hole geometry were evaluated by using blind hole drilling technique and high-temperature strain gauges, respectively. A specially designed data acquisition system was used to monitor the temperature and strain variations at specific locations during testing. The strain gauge locations were predeter- mined from the finite element analysis results where stresses and strains were predicted to be high. These locations were close to the access hole. Since the temperature around the access hole during welding was relatively high (up to 300°F), the effects of temperature change during welding on the strain gauge readings were considered and compensated.

All strain gauges were 3A in. (9.5 mm) from the edges of the access holes for thermal strain measurements. Transient thermal strain data for the first web pass of Case 11 is shown in Fig. 12.

After the weldments re turned to ambient temperature , residual stress measurements were made on the surface. A ~6- in.-diameter, high-speed drill bit was used to drill the hole. The residual stresses were calculated according to ASTM Standard E837-85 (Ref. 11). Two locations were selected on 4 of 5 speci- mens. All strain gauges were ~A-in. from the edges of the access

IC~weA B Flange

b I __x 4

i = 1 i i

A B C

D ~ a r ~ (m)

Fig. 11 - - Residual stress distribution for the E G W process, semicircle access hole (Cases 12, 13).

holes or weld interface, as shown in Fig. 13. The local surface residual strain was gradually relieved by drilling, and reached a steady state at a depth that was about three quarters of the final hole depth. Representative experimental surface residual stress values obtained are tabulated in Table 4.

Numerical and Experimental Data Comparison

Transient thermal strains calculated by finite element analysis for various cases are presented elsewhere (Ref. 5). As a comparison between the numerical results and experimental measurements, Fig. 14 shows the transient strain components plotted correspond to the point as shown for Case 10.

The initial variance between numerical and experimental strain data (t <350 s) shows a tendency for numerical results to overpredict experimental data. This is associated with the two- dimensional modeling of the moving electrode. However, the

WELDING JOURNAL J 39

Table 4 - - Residual Stress Measurement Results

Case No. Case 10 Case 11

Location C

Case 8

S, (ksi) 30.8 -33.5 27.4 Sy (ksi) 44.9 -76.0 57.4

Location E S,(ksi) 46.0 -20.3 36.6 S, (ksi) 32.7 -47.7 72.3

"Of the three processes

investigated, the FCA W

process is recommended

for splicing thick

rolled shapes."

. l m m . • • •

Fig. 1 2 - - Thermal strain measurement during the first pass of web.

Fig. 13 - - Typical positions of residual stress measurements.

numerical results and experimental data do converge with time (t >350 s). This phenomenon has been observed for all investigated cases.

The numerical and experimental results for EGW and SAW are summarized in Table 5. The general trend is for experimental residual stress data to be higher than numerical values. Since base metal is not stress-relieved before welding, initial stress, if

Table 5 - - Comparison of Numerical and Experimental Residual Stresses for Elongated Holes

Sx (ksi) Sy (ksi) I' Process Location Experiment FEM Experiment FEM I

EGW A 29.9 17.8 24.1 18.6 sequence A B 34.3 23.4 24.4 7.8 o o A

I : EGW A -15.8 -24.6 -36.3 -22.4 sequence B B -24.4 -39.0 -42.9 -10.6 SAW A 42.2 4.3 29.3 14.3 sequence A B 39.5 -4.7 20.9 6.8

any, may be a source of deviation between calculated values and experimental data.

Conclusions Residual stress normal to the weld joint near the access hole

interface was calculated by the use of a thermal-mechanical finite element model for several conditions. Table 6 summarizes the numerical results.

The numerical model results in Table 6 indicate that for the FCAW process, the tensile residual stress at the crack initiation location (point B) is minimized by using a flange-web welding sequence (Sequence A) when a 1 ~-in.-deep access hole is used. In addition, the residual tensile stress can be further reduced by increasing the depth of the access hole to a l~A-in, depth. The EGW process with the same "flange, then web" welding sequence also produces lower residual stress at the access hole interface (point B). In addition, the tensile residual stress at point B was reduced by elongating the weld access hole from the semicircle to the elongated type access hole geometry. The SAW process appears to be the least desirable welding process for joining thick rolled shapes from a tensile residual stress consideration at point B.

Numerical results indicate a single-V-groove joint with the root opening at the outer surface of the flange (Sequence C) and a l 'g-in.-diameter access hole produces high tensile residual stress at point B due to weld shrinkage. However, as the hole is elongated and made deeper to 1½ in., tensile residual stress is reduced to a compressive residual stress.

Weld access holes that provide longer openings and larger widths in the web are more desirable from a residual stress van- tage point. The longer opening reduces the joint constraint. In addition, by elongating the access hole, the termination point is pushed further away from the tensile residual stress field near the weld into a compressive residual stress region of the flange. This compressive residual stress is transverse to the tensile residual stress in the web. Their combination results in larger shear stress, and hence, a greater apparent ductility of the flange at the termination of the hole.

The angle of termination of the access hole from the web into the flange also has some effect on residual stress. Holes that ter- minate at a right angle with the flange have higher residual stress than a tangent transition termination.

The alternating welding sequence (Sequence D) with double-V-groove joints on the flanges did not show desirable results in terms of tensile residual stress at point B.

The cooling rate in the H A Z and its size were determined for the FCAW and EGW processes

L from experimental measure- × ments. The FCAW process has a

cooling rate of 372°F/s (207°C/s) while EGW is 19.4°F/s (10.7°C)

4 0 [ FEBRUARY 2001

Table 6 - - Residual Stress (Sx) from Numerical Analysis Near the Weld Access Hole

Process Sequence A Sequence B

Hole 1 ,/8 1 '/2 1 ,/8 1 ,/2 FCAW B -5.9 0 26.1 15.7

C 55.0 22.9 -44.2 2.0 Hole Elongated Elongated

SAW B 30.3 37.9 C 25.1 -49.1

Hole Circle Elongated Circle Elongated EGW B 16.7 12.2 30.3 27.9

C 46.1 23.4 -20.0 -32.3

Sequence C

1% 1 '/2 48.4 -21.3

-13.4 25.O

plicity associated with a single, uphill weld pass. This process uses a square-butt joint and requires almost no joint preparation. Sequence D Modera te tensile residual stress magni-

1 ,/8 tudes also resulted from the study. 31.0 However, the greatest concern for an -7.0 EGW weldment is low toughness. This dis-

advantage currently outweighs the advantages of higher production rates and mod- erate tensile residual stress levels.

Fracture toughness of EGW weldments could be improved substantially by normal- izing and stress relieving (Ref. 12). To take full advantage of the EGW process, further

studies to improve weldment toughness are needed. •

! - _

o i

" m ' E Y l [ M r m

.~L o 1 ~ 2o0 3o0 *~oo

Fig. 14 - - Thermal strains during flange welding with the E G W process (Case 10, G1 location in Fig. 12).

at 1500°F (816°C). Their respective H A Z size is approximately 0.13 in. (3.3 mm) from the weld interface for FCAW and 0.45 in. (11.4 mm) for EGW. This comparison indicates significant difference in the heat input characteristics of these two welding processes. Low fracture toughness is anticipated for EGW weldments.

Recommendat ions

Of the three processes investigated, the FCAW process is recommended for splicing thick rolled shapes. This process tended to produce weldments with lower tensile residual stress. The use of single-V-groove joints, with the root opening at the inner face of the flange, and a double-V-groove weld for the web is desirable. This joint design results in minimal tensile residual stress at the flange-web interface of the access hole.

A "flange, then web" welding sequence (Sequence A) produces a minimal amount of tensile residual stress at the flange- web interface of the access hole and is the most desirable sequence.

The longer access hole opening produces less tensile residual stress at the flange web interface of the access hole. The interface with a tangent transition between web and flange is also desirable.

Future W o r k

The EGW process is a very promising method for splicing thick rolled shapes because of its high deposition rate and sim-

Acknowledgments

The authors wish to acknowledge the support of the U.S. Army Corps of Engineers, both the Portland District Office and the Waterways Experiment Station Information Technology Laboratory. This project was performed under the Corps' contract DACW39-89-L-0006.

The authors also wish to acknowledge the contributions of Thomas J. Black, Harold A. Sadler and Omer Blodgett of the Lincoln Electric Co., whose excellent welding experiments supplied much of the data used and provided guidance for this investigation.

The authors wish to thank Jim Snyder of Bethlehem Steel Corp., who provided the rolled shapes used in these experiments, and Tom Campbell of J. T. Edwards for cutting and de- livering the material. Our thanks also extend to Ken Runyon, John Bosworth and Bruce Hornlourger of Beasley Co. for their support in preparing the FCAW joints.

The authors wish to acknowledge Cort Reiser for welding test coupons and many coworkers and associates in the Depart- ment of Welding Engineering at The Ohio State University who made contributions throughout the course of this investigation.

References 1. Fisher, J. W., and Pense, A. W. 1987. Experience with use of heavy

W-shapes in Tension. Engr. J., AISC, 2nd quarter, pp. 63-72. 2. Barsom, J. M. 1988. Noncolumn application of wide-flange

shapes. Proc. National Steel Construction Conference, Paper No. 7, AISC, Miami, Fla.

3. Giant truss for Dallas hangar found cracked before erection. April 14, 1988. ENR, Construction weekly, pp. 8-9.

4. Alpsten, G. A. and Tall L. 1970. Residual stress in heavy welded shapes. Welding Journal 49(3):93-s to 105-s.

5. Finite element modeling of welded thick plates for Bonneville Navigation Lock. 1990. Project report, Department of Welding Engi- neering, The Ohio State University, Columbus, Ohio.

6. Geometry for finite element mesh and welding lab test. 1989. Ac- tivity report, Trade Arbed.

7. AISC, Supplement No. 2 (Section 1.15.14). 1989. 8. Metals Handbook. 1984 and 1948. ASM International, Materials

Park, Ohio. 9. Determination of residual stress and effects in thick section weld-

ments for hydraulic structures. 1990. Project report, Department of Welding Engineering, The Ohio State University, Columbus, Ohio.

10. Blodgett, O. W. 1989. Private communication with Tsai, Septem- ber 26.

11. Determinating residual stresses by the hole drilling strain gage method. ASTM Standard E837-85.

12. Masubuchi, K. 1970. Materials for Ocean Engineering, The MIT Press, p. 489.

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0 Fill out card below. Be sure to include your All~S Member number. (Please note: i f you sent in your book request last month, do not send in a duplicate caM).

@ Cut out card on dotted lines.

Design and Planning Manual f o r Cost-Effective Welding- This manual is a practical guide for engineers, planners, and hands-on professionals to improve scheduling and lessen rework. Includes sections on cost analysis, concepts of welding design and more.

Jefferson's welding Encyclopedia - No matter your involvement in the industry, Jefferson's puts the world of welding right at your fingertips. A useful tool for any level in the industry- from student to the experienced veteran. Includes a historical look at the welding industry, a handy Buyer's Guide, and an exhaustive listing of key industry suppliers.

• Yes! I'm an AWS Individual Member*. Please send my free book!

(Please check ONE only from the following five book options. One card per AWS Individual Member). • Design and Planning Manual for Cost-Effective Welding • Jefferson' s Welding Encyclopedia • Soldering Handbook • Welding Met~dlur~" • Welding Handbook, 9th Ed., Vol. 1 is,,( available until March 2001. Delivet~ will be in April 2001. )

~ofik, r applies to ~\¥S Individual Members only.: '1~1 ul~grade your tllenthership, c;zll (800) q43+t)353, exL ~80.

AWS Member #

Name

Address

City. State Country

Zip. Phone ( )

E-mail Fax ( ) IMPORTANT: Please allow 6-8 weeks for book delivery (ff Welding Handbook selected, delivery will be in April '01). Books will be delivered to the same address as your Welding Journal.

Soldering Handbook - Written for individuals from a variety of backgrounds, this handy reference is geared toward allowing soldering technology to be more fully utilized in advanced structural joining applications. Topics include fundamentals, materials, fluxes, assembly processes, inspection techniques, safety and health.

Welding Metallurgy - The premier publication on the welding metallurgy of steels. Builders, manufacturers, welding shops, colleges and universities will benefit from this valuable reference book, which places a lifetime of welding research and experience at their fingertips.

Welding Handbook, 9 th Ed., Vol. 1 - Written in descriptive, reader-friendly language, the Handbook offers ample detail to satisfy the welding professional, while simultaneously serving as a thorough introduction to students and others who are new to the field.

*Free book is a benefit of AWS Individual Members only. All other members, including A WS Student Members, may upgrade their memberships (and select a free book) by calling the AWS Membership Department at (800) 443-9353, ext. 480. Individual Member dues are $75.

American Welding Society 550 N.W. LeJeune Rd. Miami, FL 33126

Visit our website http://www.aws.org

Because the potential

exists for head and eye

injuries at nearly every job

site, proper use of personal

protective equipment such

as safety spectacles and

hard hats is a must

rtually every worker required to wear a hard hat - - the most familiar symbol of ersonal protective equipment (PPE) - - now wears one, yet studies indicate bout 30% of those users aren't in compliance with OSHA standards.

The news isn't as good for eye protection. According to the Industrial Safety Equip- ment Association (ISEA) and Compliance magazine, 68% of all employees who should use protective eyewear, don't. That's why an estimated 400,000 eye injuries occur on the job every year, according to the National Society to Prevent Blindness.

We all know the Occupational Safety and Health Administration (OSHA) has very strict rules regarding head and eye protection. For instance, 29 CFR 1910.133 man- dates we use eye protection whenever we're exposed to flying objects, infrared (IR) and ultraviolet (UV) radiation, glare, liquids, molten metals and other dangers. Have I covered your job site? It's hard to think of any project where we don't face a danger from head and eye injuries.

Of course, we can't simply assume OSHA regulations will solve all our problems; we have to assume responsibility for protecting ourselves. That means wearing hard hats, welding helmets and safety spectacles on the job.

Hard hats and protective eyewear are readily available. The cost varies depending on style, use, requirement and quantity. Traditional safety spectacles used on a job site to protect against the sun's glare and any flying objects can be purchased for only $5 or $10. A basic all-around hard hat costs about $10.

BY I N G E M A R H. O L S S O N INGEMAR H. OLSSON is National Sales Manager, Professional Trades, Construction and Welding Channels, Dalloz Safety, Reading, Pa., (610) 371-6161.


Let's review some important basics for proper head and eye protection.

Head Protection

• Always wear appropriate head protection. The latest revision to the ANSI Z89 regulation groups hard hats into Type 1, which protects against falling objects, and Type 2, which protects against both falling objects and side impact. Hard hats are further defined as classes G, E and C. Class G head protectors reduce the danger of contact exposure to low-voltage conductors, as well as to the impact and penetration requirements of either a Type 1 or Type 2. Class E hard hats reduce the danger of contact exposure to high-voltage conductors. Class C hard hats provide no protection against contact with electrical conductors.

• Make sure it fits well. Hard hats should not fall off when the head is bent down or the person wearing it looks at his or her feet. If falling is a potential hazard in your work environment, your biggest danger is that your hard hat will not stay on when you fall. Wear one with increased side impact protection and a chinstrap to secure it.

• Obey "Hard HatArea" signs. These are posted to protect you wherever there is danger from falling and flying objects and possible side impacts.

• Never wear a hard hat backward. When wearing a welding helmet with a safety cap, many welders often turn the suspension around and wear the shell backward. While regulations do not specifically address this issue, if a hard hat was not tested in this "as worn" position, it does not meet the ANSI Z89 standard. Contact the hard hat manufacturer to determine which uses are acceptable for a part icular hard hat or head protector.

• Don't drill holes in the shell o f a hard hat. Doing so may nullify its Class E or G rating, and/or lessen its impact resistance.

• Don't use adhesives orpaint on a hard hat. They could attack or damage the shell, reducing the level of protection.

• Hard hats generally do not have a service life. That's because hard hats are used in and subjected to a variety of conditions. Obviously, a hard hat used every day will need to be replaced far more quickly than a cap used by a manager on a once-a-week trip to a hard hat area.

• Take advantage o f appropriate accessories. In addition to welding equipment, some manufacturers offer various at tachments for hard hats including hearing protection, i.e., earmuffs, as well as visors and faceshields. Liners are available for cold weather wear.

Headgear for visors need to be adjusted for a personalized fit. Ratchet- type headgear suspensions are available and can be easily adjusted simply by turning the ratchet knob. Other types use a pin-lock design style, which can also be easily adjusted to accommodate different head sizes. Visors should be securely attached to headgear following the manufacturer's instructions. Do not guess or have a "looks okay" attitude. For any faceshield to work and protect as it was intended, the visor must be attached correctly.

• Maintain head protection. Clean hard hats with mild soap or detergent and warm water. Never use solvents. In- spect the suspension frequently and dis- card it at the first sign of deterioration or fraying.

Eye Protection • Don't use regular prescription

glasses as safety spectacles. If you wear prescription glasses, you should obtain safety spectacles that incorporate your prescription, or use protective eyewear that comfortably fits over prescription eyewear. Always wear safety spectacles underneath welding helmets, visors and faceshields, which are considered sec-

ondary, not primary, protection. • Go for the best. Safety spectacles of

inferior optical quality can distort or blur vision and depth perception, causing headaches, nausea and fatigue, as well as accidents. Make certain any protective eyewear with plastic lenses meets high- mass and high-velocity impact and penetration criteria in accordance with the ANSI Z87.1 standard. Eyewear meeting these criteria are marked with "Z87."

• Always use a shaded lens when welding, brazing, cutting with a torch, etc. Welding lenses and visors are manufactured in shades to protect against radiation hazards and are ra ted from 1 through 14 - - the higher the shade 's number, the darker the lens and the greater its ability to absorb IR radiation. Welding, cutting and brazing operations produce three types of radiation. Visu- ally, one can see the brightness, while IR is felt as heat. Invisible UV radiation is also present. A shade 3 lens will transmit about 14% of visible light and 9% of IR. By contrast, a shade 10 lens transmits only 0.01% of visible light and 0.001% of IR.

For example, if you do light cutting or brazing, use a shade 3 or 5 lens. Arc welding requires a minimum of shade 10. The identification marking for any shade is stamped on the lens.

With electrical contracting, electrical arcs and flash are among the hazards that may be encountered, often without warning. Special UV- and IR-absorbing lenses are available to protect against this, as well as intermittent electrical arc. Again, match the eye protection with the severity of the radiation.

• Do not use nonabsorptive, tinted lenses for welding. Many lenses offered by Dalloz Safety and other manufacturers are not absorptive lenses dedicated for welding. For example, Willson® T C G " dark gray lenses absorb 86% of IR radiat ion, but are not absorptive welding lenses. They are mainly used outdoors for electrical work where color recognition of wiring is essential.

44 I FEBRUARY 2001

• Consult the standards. Both ANSI Z87.1-1989 and OSHA 29 CFR 1910.133 contain selection charts on shaded lenses for welding, cutting and related applications. Consult these standards for specifics. The CSA Z94.3-92, Industrial Eye and Face Protectors, standard lists shaded numbers and their maximum transmittance values for UV, IR and visible light transmission. The Canadian standard also requires that sideshields used to protect against UV, IR and visible radiation have a shade number equal to, or greater than, the front lens filters, but not greater than a shade 5 rating.

• Lasers require special lenses. Shaded lenses for welding cannot be used when working with lasers because of their monochro- matic light, which requires specialized protective eyewear. Take all proper precautions with protective eyewear for lasers since nearly 70% of accidents in- volve eye injuries.

• Take advantage of special lens options to make your job eas&r and safer Consider a fog-resistant lens coating for workplaces with high humidity, or an indoor-outdoor lens if you frequently move from a ware- house to an outside stocking area and vice versa. An indoor-outdoor lens is designed to protect against both sun- light and harsh overhead lights. Make sure safety spectacles provide sufficient protect ion against ultraviolet and infrared radiation.

• Be certain tinted lenses do not affect color This is especially important if you are working with electrical wiring or en- countering traffic signals.

• Use secondary protection as needed. When a job involves severe impact or

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other hazards, for example from grinding or sanding, use a faceshield or visor as a secondary safety device. OSHA requires that when welding helmets are used, safety spectacles must still be worn as the primary eye protection. The same is true for visors and faceshields. That's because a welding helmet could acci- dentally flip up, thus exposing unpro- tected eyes to high glare, high UV and high IR radiation.

• Keep safety spectacles and otherpro- tective eyewear clean and in good condition. Use only mild soap or detergent. Do not use any solvents. To avoid scratching, do not use paper towels or nontreated paper to dry plastic lenses.

Use a diluted household bleach (one part 5% household bleach to ten parts water) to disinfect protective eyewear.

Most safety spectacles and goggles have replaceable lenses, so change them whenever they are scratched or pit- ted. Frames should be discarded when cut, broken, faded or visibly worn. If goggles or faceshields are

subjected to a chemical splash, they should be discarded. Unseen stress cracks can be a real threat if the visor or lenses are later used for impact protection.

There's no reason why 68% of workers who should be wearing protective eyewear don't when adequate personal protective equipment is so readily available. Your coworkers or employees won't become part of on-the-job injury statistics if you consult with your manufacturer or local supplier for help in selecting the proper head and eye personal protective equipment for the job. •

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EWI offers Professional Workshops in all areas of materials joining technology, providing the knowledge required to produce higher quality products with increased productivity. Workshops are taught by recognized experts who relate course material to real world applications.

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EWI also offers Hands-On Skills Training for welders and welding technicians. Our instructors have industry experience in all major welding processes and can provide certification to any code or standard.

EWI Professional Workshops and Hand-On Skills Training:

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Brazing, Soldering

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Training

Datasheet 249a Wel f Workbook

Practical information for welders and others involved in welding and its allied processes.

Welding Safety and Health

Effective training is the key to any safety program. Welders (this includes brazers and solderers) and cutters must be trained in the proper use of equipment and processes, and they must know all the safety rules pertaining to their jobs and the consequences of not following them.

For any training program to be effective, management must support it and give direction in its implementation. Only with this commitment to safety and health will the results be positive.

Understand the Hazards

Users of equipment must read and understand the manufacturer's instructions on safe operation. Material safety data sheets (MSDS) are provided by manufacturers of consumables, and they must be made available to employees by the employer. They must be read because the MSDS identify hazardous materials that may be present in the product and permissible exposure limits. Certain specifications require precautionary labels, and these should be read and followed.

Employers are required to train their employees with respect to hazardous materials used in the workplace. Individuals must also be trained to recognize hazards to safe operation. For instance, defective or worn electrical insulation must be recognized and not tolerated in welding and cutting. The same can be said for worn or defective hoses in oxyfuel operations.

Persons who must perform their job in potentially hazardous locations, such as a confined space or poorly ventilated area, must be thoroughly informed of the hazards involved and be given the proper equipment and assistance to perform under those conditions.

Radiant Energy Protection

Individuals in areas adjacent to welding and cutting must be protected from radiant energy, sparks and spatter by flame-resistant screens and shields, suitable eye and face protection and protective clothing. Protective screens should provide for air circulation both above and below them. If arc welding or cutting is performed constantly next to painted walls, the walls should have a covering that has low reflectivity to ultraviolet radiation. Paints with titanium dioxide or zinc oxide have low reflectivity, but pigments with a base of powdered or flaked metals are not recommended. Color pigments can be present if they do not increase reflectivity.

Public demonstrators of welding and cutting are responsible for the safety of the observers. Appropriate eye protection must be available, as well as proper ventilation of fumes. Cables and hoses must be directed away from the public area, and fire extin- guishers must be readily available.

Excerpted from the Welding Handbook, VoL 1, Eighth edition.

Fire Concerns

Open flames, electric arcs, sparks, hot metal and spatter all present a potential fire hazard. Sparks can travel great distances from their source and lodge in cracks or other small openings.

Combustibles in the work area present a particular hazard. Perform work away from combustibles or shield it with appropriate noncombustible barriers. Common combustible materials encountered are wood, paper, plastics, cloth materials, chemicals, flammable liquids and gases, dry grass and brush. It is recommended that floors be free of combustible materials at least for a 35-ft radius around the work area.

The best protection would be to have specially designated areas free of fire hazards for welding and cutting. If that is not possible, cover cracks, windows, doorways and other openings with flame-resistant material. Enclosing the work area with flame-resistant screens is a desirable option.

Carefully store fuel for engine-driven equipment, and follow manufacturers' instructions, since vapors can be explosive under certain conditions. Take particular care to prevent gas leakage from acetylene, propane and other fuel gas cylinders and apparatus. Check them on a regular basis.

If a metal wall, ceiling or partition is adjacent to a welding or cutting operation, any combustibles on the other side must be removed since metal readily conducts heat. If removal is not possible, a fire watcher should be stationed with the combustibles, and a fire extinguisher available. A thorough inspection for signs of fire should be conducted up to 30 minutes after completion of the operation.

Burns can be serious. Always take precautions to protect your eyes, face and body from ultraviolet and infrared radiation, sparks and spatter. Those in the work area other than the operator should also be protected.

Explosion Precautions

When flammable gases, vapors and dust mix with oxygen in certain proportions, the danger of explosion exists. Heat and sparks from welding and cutting can be the source of ignition; therefore, these operations should not be performed in atmospheres that contain a combustible mix.

Hollow containers must be vented before applying heat, and never apply heat to containers that have held an unknown material, a combustible substance or a substance that may form flammable vapors. Never apply heat to a container that is covered by an unknown, toxic or flammable substance.

Before starting the operation, clean the container thoroughly or fill it with an inert gas. Always wear appropriate eye protection when the risk of explosion is present.

WELDING JOURNAL [ 4"/

Datasheet 249b

Welding Safety and Health

Eye and Face Protection

Anyone viewing the arc must have a welding helmet or face shield with the appropriate filter plates for the process being viewed. Safety spectacles, goggles or other suitable eye protection must also be worn during welding and cutting. These devices must have side shields when there is danger of injurious rays or flying particles such as from grinding or chipping. Since the arc is covered by flux in the submerged arc welding process, an arc welding helmet is not necessary, but tinted safety glasses should be worn since occasional flashes of the arc might show through the flux.

Safety goggles with the appropriate filter plates and side shields must also be worn with oxyfuel gas welding and cutting. Torch brazing and soldering requires safety spectacles with the appropriate filter. Resistance, induction and infrared welding require operators to wear safety spectacles, goggles and face shields to protect themselves from spatter.

if released into the atmosphere as fumes during welding, brazing or cutting operations. The table below shows some of those compounds and the base or filler metals that may release them.

The Occupational Health and Safety Administration has established permissible exposure limits (PEL) of airborne contaminants. To ensure levels are within allowable limits, air samples must be taken at the breathing zones of the personnel involved. Information on how to obtain an accurate sample in the breathing zone is contained in ANSI/AWS FI.1, Methods for Sampling Airborne Particulates Generated by Welding and Allied Processes. The amount and composition of welding fume can be determined with the testing outlined in this document.

Employers must make available and ensure the employee understands the information contained in material safety data sheets provided by manufacturers of welding consumables. These sheets provide information on materials in electrodes, rods and fluxes that are hazardous or harmful to health.

Fumes and Gases

Factors that influence fume generation are welding current, arc voltage, transfer mode, welding process and shielding gas.

Generally, fumes increase with an increase in welding current, although there are some covered, flux cored and solid electrodes in which the fume increase is nonproportional. Also, an increase in voltage generally increases fume generation. Arc voltage is directly related to arc length.

Arc turbulence encountered with gas metal arc welding in the short circuiting mode contributes to a relatively high fume generation during this transfer. The higher current needed with spray transfer has an affect on fume generation.

The use of CO 2 as a shielding gas will generate more fumes than argon-rich mixtures. When using an inert gas such as helium, more fumes are generated when compared to argon.

In studies that considered the ratio of weight of fumes generated to weight of weld metal deposited, covered electrodes and self-shielded flux cored electrodes produced the most fumes. Gas-shielded flux cored electrodes generated somewhat less fumes and solid wires, the least. Fumes from the submerged arc process are captured in the flux and slag coverage and are not released to the atmosphere.

Minimize Fume Exposure

Keep your head to one side of the fume plume and not directly in it. If possible, position the work so the fume rises to one side. Use a helmet that curves under the chin and toward the chest. Close-fitting helmets and respirators are beneficial.

A proper ventilation system is necessary. The ventilation can be localized at the point of welding or it can be a general filtering of the shop air through natural convection or by mechanical means. The system must ensure that concentrations of hazardous airborne contaminants are below levels allowed by the Occupational Safety and Health Administration (OHSA) or other pertinent authorities.

There are materials sometimes present in consumables, base metals or coatings that have very low permissible exposure limits

Possible Toxic Materials Evolved during Welding or Thermal Cutting

Base or Filler Metal

Carbon and low-al loy steels Stainless steels Manganese steels and

hardfacing materials High-copper alloys

Coated or plated steel or copper

Evolved Metals or Compounds

Chromium, manganese, vanadium Chromium, manganese, nickel Chromium, cobalt, manganese,

nickel, vanadium Beryllium, chromium, copper,

lead, nickel Cadmium*, chromium, copper,

lead nickel, silver

*When cadmium is a constituent in a filler metal, a warning label must be affixed to the container or coil.

Electrical Safety

Bare or poorly insulated conductors are a main source of electrical shock in welding. Precautions must be taken against con- tacting bare elements in the welding or primary circuit, especially when the welder is required to be in a cramped kneeling, lying or sitting position. Welding in damp conditions is an electrical hazard. Welders should not stand in water when welding, and dry gloves and clothing should be worn at all times.

At a minimum, rubber-soled shoes should be worn for protection while standing on potentially conductive surfaces. It is better if the surface is insulated with a rubber mat. Remove rings and jewelry before welding as a precaution against electric shock.

Equipment should be installed, operated and maintained according to the manufacturer's recommendations and electrical codes. The workpiece welded and the frame of electrically powered machines must be connected to a good electrical ground. Chains, wire ropes, cranes, hoists and elevators must not be used as grounding connections or to carry welding current. Do not allow the metal parts of electrodes, electrode holders or torches to touch bare skin or wet clothing. Electrode holders should not be cooled by immersion in water, and do not drape or coil welding cables around the body.

481FEBRUARY2001

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C o n f e r e n c e s and E x h i b i t i o n s

NACE Northern Area Western Conference. February 26-28, Hilton Hotel, Anchorage, Alaska. Sponsored by NACE International, the Corrosion Society. Contact: Dan Powell, Co- chairman, (403) 235-6400, e-mail: [email protected].

International Laser Safety Conference. March 5-8, Catamaran Resort Hotel, San Diego, Calif. Sponsored by the Laser Institute of America. Contact: LIA, 13501 Ingenuity Dr., Ste. 128, Orlando, FL 32826.

NACE International - - Corrosion 2001, Conference and Exhibition. March 11-16, George R. Brown Convention Center, Houston, Tex. Sponsored by NACE International, the Corrosion Society. Contact: NACE Membership Services, (281) 228-6223, FAX: (281) 228-6329, www.nace.org.

WESTEC 2001: Advanced Productivity Exposition. March 26-29, Los Angeles Convention Center, Los Angeles, Calif. Sponsored by the Society of Manufacturing Engineers. Contact: SME Customer Service, One SME Dr., Dearborn, MI 48121, (800) 733-4763, (313) 271-1500, FAX: (313) 271-2861.

• Max International. May 6-10, IX Center, Cleveland, Ohio. Cohosted by the American Welding Society and The Precision Metalforming Association, this collocated event is comprised of

Comf v nts the AWS International Welding and Fabricating Exposition and Annual Conference and METALFORM ExpoSium. Contact: AWS Convention and Exhibitions Dept., 550 NW LeJeune Rd., Miami, FL 33126, (800) 443-9353 ext. 256 or (305) 443-9353 ext. 256, FAX: (305) 442-7451.

• Tenth International JOM-Jubilee-Conference on the Joining of Materials, JOM-10. May 11-14, Helsing0r, Denmark. Cosponsored by the Institute for the Joining of Materials and AWS. Contact: Institute for the Joining of Materials, Klintoh0j V~enge 21, DK-3460 Birkerod, Denmark, 45 45 82 80 85, FAX: 45 45 94 08 55 or e-mail: [email protected].

Twin Cities 2001 Advanced Productivity Exposition. May 15-17, Minneapolis Convention Center, Minneapolis, Minn. Sponsored by the Society of Manufacturing Engineers (SME), America Machine Tool Distributors' Association (AMTDA) and the Association for Manufacturing Technology (AMT). Contact: SME Customer Service, (800) 733-4763 or (313) 271- 1500 ext. 1600 or visit the SME Web site at www.sme.org.

International Robots and Vision Show. June 5-7, Rosemont Convention Center, Chicago. Sponsored by the Robotic Industries Association (RIA) and Automated Imaging Association (AIA). Contact: RIA/AIA, 900 Victors Way, P.O.

Note: A diamond (0) denotes an A WS-sponsored event.

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Weld Cracking: Causes and Cures Conference. June 7-8, Houston Tex. Sponsored by the American Welding Society. Contact: AWS Conference Dept., 550 NW LeJeune Rd., Miami, FL 33126, (800) 443-9353 ext. 223, FAX: (305) 443-1552.

e, The Cutting of Plates Conference. July 17-18, Chicago, Ill. Sponsored by the American Welding Society. Contact: AWS Conference Dept., 550 NW LeJeune Rd., Miami, FL 33126, (800) 443-9353 ext. 223, FAX: (305) 443-1552.

15th International Joining, Cutting and Surfacing Fair "Schweissen & Schneiden." Sept. 12-18, Essen, Germany. Contact: Claus-Peter Regiani or Christina Kursawe, 49(0)201-7224-227 or -529, FAX: 49(0)201-7244-435, e-mail [email protected] or kursawe~ messe-essen.de, www.messe-essen.de.

First Middle East Nondestructive Testing Conference and Exhibition. September 24-26, Gulf International Convention Centre, Bahrain. Cosponsored by the Saudi Arabian Section of the American Society for Nondestructive Testing and the Bahrain Society of Engineers. Contact: The Conference Secretariat, Bahrain Society of Engineers, P.O. Box 835, Maama, Bahrain, 973-727 100, FAX: 973-729 819, e-mail: Mohandis@batelco. com. bh.

International Conference on Advances in Materials and Processing Technologies. September 18-21, Legan~s, Madrid, Spain. Contact: AMPT '01 Congress Secretariat, Fundaci6n Universidad Carlos III, Congrega, Avda. de la Universidad, 30, 28911 Legan6s, Madrid, Spain, 34 91 624 91 42, FAX: 34 91 624 91 47, e-mail: [email protected].

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Las Vegas Machine Tool Exposition. September 24-26, 2001, Las Vegas Convention Center, Las Vegas, Nev. Contact: William Yeates, Show Manager, (702) 566-7300, FAX: (702) 566-7300.

Fourth Pacific Rim International Conference on Advanced Materials and Processing. December 11-15, Hilton Hawaiian Village, Honolulu, Hawaii. Organized by the Chinese Society for Metals, the Korean Institute of Metals and Materials, the Minerals, Metals and Materials Society and the Japan Institute of Metals. Contact: The Japan Institute of Metals, ATTN: PRICM 4 Secretariat, Aoba, Aramaki, Aoba-Ku, Sendal, 980- 0845.

Educational Opportunities Innovative Engineering and Inventive Problem Solving Course. February 26-27, Orlando, Fla. Conducted by the American Society of Mechanical Engineers. Contact: Shari Romar, Senior Education Specialist, ASME International, Three Park Ave., New York, NY 10016, (212) 591-7902, FAX: (212) 591-7143, [email protected].

Respiratory Protection and Fit Testing. February 27-28, Salt Lake City, Utah. Sponsored by the Rocky Mountain Center for Occupational and Environmental Health, University of Utah. Contact: Registration Coordinator, the Rocky Mountain Center for Occupational and Environmental Health, University of Utah, 75 South 2000 E., Salt Lake City, UT 84112, (801) 581- 5710, FAX: (901) 585-5275.

Rocky Mountain Comprehensive Review of Industrial Hygiene. March 5-9, Salt Lake City, Utah. Sponsored by the Rocky

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Mountain Center for Occupational and Environmental Health, University of Utah. Contact: Registration Coordinator, the Rocky Mountain Center for Occupational and Environmental Health, University of Utah, 75 South 2000 E., Salt Lake City, UT 84112, (801) 581-5710, FAX: (901) 585-5275.

Automotive Laser Application Workshop (ALAW) 2001. March 13-14, Dearborn Inn, Dearborn, Mich. Organized by the University of Michigan, College of Engineering, Center for Professional Studies. Contact: Beth Hillis, (734) 647-7194, FAX: (734) 647-7182, e-mail: [email protected], http://cpd.engin. umich.edu.

Blueprint Reading and Graphic Symbols Course. March 28-30, New York, N.Y. Conducted by the American Society of Mechanical Engineers. Contact: Shari Romar, Senior Education Specialist, ASME International, Three Park Ave., New York, NY 10016, (212) 591-7902, FAX: (212) 591-7143, c- mail: [email protected].

• DI.I: 2000 Structural Welding Code - - Steel. A five-day seminar. Sponsored by AWS. For more information and complete schedule, contact: AWS Conferences, 550 NW LeJeune Rd., Miami, FL 33126, (800) 443-9353 ext. 223, FAX: (305) 443-1552.

Boiler and Pressure Vessel Inspectors Training Courses and Seminars. 2001 schedule, National Board of Boiler and Pressure Vessel Inspectors Training and Conference Center, Columbus, Ohio. Conducted by The National Board of Boiler and Pressure Vessel Inspectors. For courses and times, contact: Richard McGuire, Manager of Training, (614) 888-8320, e-mail: rmcquire@nationalboard, org; www.nationalboard.org.

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i WELDING JOURNAL I 53

Educational Opportunit ies

AWS Schedule m CWI/CWE Prep Courses and Exams

Exam applicat ion must be submit ted six weeks before exam date. For exam informat ion and application, contact the AWS Certification Dept. , (800) 443-9353 ext. 273. For exam prep course information, contact the AWS Educat ion Dept. , (800) 443-9353 ext. 229. Dates are subject to change.

Cities Exam Prep CWI/CWE Cities Exam Prep CWI/CWE Courses Exams Courses Exams

Anchorage, Alaska EXAM ONLY March 24 Miami, Fla. EXAM ONLY March 15 Atlanta, Ga. Feb. 26-March 2 March 3 Miami, Fla. EXAM ONLY May 17

(API 1104 Clinic also offered) Minneapolis, Minn. March 5-9 March 10 Bangor, Maine April 2-6 April 7 Mobile, Ala. EXAM ONLY Feb. 17

Nashville, Tenn. May 21-25 May 26 Birmingham, Ala. EXAM ONLY May 26 /API 1104 Clinic also offered) Buffalo, N.Y. EXAM ONLY Feb. 17 New Orleans, La. April 30-May 4 May 5 Charlotte, N.C. Feb. 12-16 Feb. 17 (API 1104 Clinic also offered) Cincinnati, Ohio May 14-18 Ma), 19 Newark, N.J. March 12-16 March 17 Chica~o, I11. April 30-May 4 May 5 Cleveland, Ohio May 11 VIW ONLY May 12 Oklahoma City, Okla. Feb. 5-9 Feb. 10 Columbus, Ohio EXAM ONLY March 3 Perrysbur~, Ohio EXAM ONLY March 24

Portland, Maine April 2-6 April 7 Corpus Christi, Tex . EXAM ONLY May 5 Phoenix, Ariz. March 19-23 March 24 Denver, Colo. Feb. 26-March 2 March 3 Detroit, Mich. EXAM ONLY April 21 May 14-18 May 19

(API 1104 Code Clinic also offered) Gulfport, Miss. Feb. 19-23 Feb. 24 Houston, Tex. March 5-9 March 10 San Francisco, Calif. May 14-18 May 19

(API 1104 Clinic & SCWl also offered) Spokane, Wash. May 14-18 May 19 Indianapolis, Ind. Au~. 6-10 Au~. 11 Jacksonville, Fla. EXAM ONLY April 28 Springfield, Mo. March 19-23 March 24

St. Louis, Mo. May 21-25 May 26 Tulsa, Okla. EXAM ONLY March 10 Knoxville, Tenn. March 12-16 March 17

(API 1104 Clinic also offered) Las Vegas, Nev. April 23-27 April 28 Long Beach, Calif. May 21-25 May 26

Pittsburgh, Pa.

Seattle, Wash. EXAM ONLY April 28

York, Pa. EXAM ONLY April 28

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/ E N E W S

By Susan Campbell

¢ A W S and Trinity Industries Join to Provide Web Learning Applications

T he A m e r i c a n Weld ing Socie ty (AWS) ilnd Tr in i ty In- d u s t r i e s , Inc . , a n n o u n c e d t h e y h a v e f i n a l i z e d an exc lu s ive r e l a t i o n s h i p to c o n v e r t AWS b r a n d e d ed-

u c a t i o n a l m a t e r i a l s i n to i n t e r a c t i v e W e b - b a s e d l e a r n i n g a p p l i c a t i o n s . T h e c h o s e n t e c h n o l o g y p r o v i d e r for t h i s c o l l a b o r a t i o n is Vellis K n o w l e d g e , Inc. , .'l l eade r in industrial e - l ea rn ing .

Vell is b r i n g s i n d u s t r i a l m a n u f a c t u r i n g c o m p a n i e s c o s t - s a v i n g a n s w e r s for a b r o a d r ange of b u s i n e s s p rob - l e m s . T h r o u g h t e c h n o l o g y i n t e g r a t i o n , Vellis o f fe r s a so- l u t i o n to a s t r a t e g i c p r o b l e m of all i n d u s t r i a l m a n u f a c - t u r i n g c l i e n t s : t h e w i d e n i n g ski l l s g a p b e t w e e n w h a t c o m p a n i e s n e e d in t e c h n i c a l sk i l l s a n d t h e c u r r e n t k n o w l e d g e base of the w o r k force.

T i m o t h y R. W a l l a c e , T r i n i t y ' s c h a i r m a n + p r e s i d e n t a n d c h i e f e x e c u t i v e of f icer , said, " H a v i n g a t r a i n e d a n d c e r t i f i e d m a n u f a c t t t r i n g w o r k f o r c e c o n t i n u e s to b e at h i g h p r i o r i t y for i n d u s t r i a l c o m p a n i e s . 1 am e n t h u s i a s - t ic a b o u t t a k i n g t h e b e s t o f T r i n i t y ' s m a n u f a c t u r i n g ex- p e r t i s e , p a r t n e r i n g w i t h t h e A m e r i c a n W e l d i n g Soc i e ty a n d m e r g i n g t h e i r b r a n d e d e d u c a t i o n a l p r o d u c t s w i t h t he be s t of t he I n t e r n e t t h r o u g h t h e V e l l i s L e a r n i n g Man- a g e m e n t System."

A c c o r d i n g to Dr. F r a n k G. l ) eL au r i e r , e x e c u t i v e di- r e c t o r of AWS,"We are e x c i t e d a b o u t t h e p o s s i b i l i t y of a c c o m p l i s h i n g pa r t of o u r e d u c a t i o n a l m i s s i o n t h r o u g h o u r c o l l a b o r a t i o n w i t h T r i n i t y I n d u s t r i e s a n d Vel l i s ' s l e a r n i n g s y s t e m s . T h e d e l i v e r y o f o u r m a n y e d u c a t i o n a l p r o d u c t s in it W e b - b a s e d l e a r n i n g e n v i r o n m e n t wil l ensure t ha t i n d u s t r y c a n take a d v a n t a g e of t he la tes t t ech- nical i n f o r m a t i o n AWS hits to offer."

l ) o u g l a s B r e n n e r , c h i e f e x e c u t i v e o f f i c e r for Vell is K n o w l e d g e , Inc. , said, "This r e l a t i o n s h i p w i t h Tr in i ty and t h e A m e r i c a n W e l d i n g S o c i e t y is t h e p e r f e c t fi t for Vel- lis, as we focus on i n t e g r a t i o n of t e chno l ogy , c o u r s e w a r e - c o n t e n t and s e r v i c e s to i m p r o v e l e a r n i n g o u t c o m e s for i n d u s t r i a l w o r k e r s . T h i s is m u c h m o r e t h a n jus t a l o w e r cos t t r a in ing so lu t ion ."

T h e f i rs t of t en m o d u l e s , "Weld and Base Metal Dis- c o n t i n u i t i e s , " wil l b c a v a i l a b l e ear ly t h i s y e a r . T h e com- p l e t i o n of the se r ies is e x p e c t e d in the late sp r ing .

About Trinity Industries

Trini ty Indus t r i e s , Inc. , h e a d q u a r t e r e d in l)al las,Tcx., is o n e of the n a t i o n ' s l ead ing d ive r s i f i ed i ndus t r i a l com- p a n i e s . T r i n i t y o p e r a t e s t h r o u g h six p r i n c i p a l b u s i n e s s s e g m e n t s : t h e Ra i l ca r G r o u p , t h e I n l a n d Barge G r o u p , t he Parts and Serv ices G r o u p , the H ighway C o n s t r u c t i o n P r o d u c t s ( ; r oup , the C o n c r e t e and Aggrega t e G r o u p and t he Indus t r i a l G r o u p . T r i n i t y ' s Web s i te may he a c c e s s e d at t t ' w u ' . t r i n . l t e t or, for spec i f i c g r o w t h i n f o r m a t i o n , visit w w w . TFDI i tyG'rowt l .~ , c o Ill.

About Vellis Vellis K n o w l e d g e , Inc . , p r o v i d e s c o m p l e t e ski l ls ,

k n o w l e d g e and t r a i n i n g s o h i t i o n s to c o r p o r a t i o n s a r o u n d t h e w o r l d . Vcll is s p e c i a l i z e s in i n d u s t r i a l a p p l i c a t i o n s and is c o n s i d e r e d a w o r l d l eade r in t he c r e a t i o n of learning r e s o u r c e m a t e r i a l s for sk i l l ed w o r k e r s in m a n u f a c - t u r i n g and r e l a t ed i n d u s t r i e s . T h r o u g h an a w a r d - w i n n i n g t e a m a p p r o a c h , V e l l i s c r e a t e s h i g h - l e v e l s t r a t e g i c soltl- t i o n s t h a t are c u s t o m i z e d to t he s p e c i f i c b u s i n e s s chal- l enges of i nd iv idua l c o r p o r a t i o n s . T h e s e u n i q u e t u r n k e y s o l u t i o n s c o m b i n e so f tware , c o n t e n t and spec i a l i z ed ser- v ices . H e a d q u a r t e r e d in Ch icago , II1., Vellis also o p e r a t e s n e t w o r k o f f i c e s in M i c h i g a n , T e x a s a n d B r i s b a n e , A u s - tralia. Visit t h e c o m p a n y ' s \Veb s i te at wwu,. V e l l i s . c o m .

About AWS T h e A m e r i c a n W e l d i n g Society , f o u n d e d ill 1919, is

t h e l a r g e s t o r g a n i z a t i o n ill t h e w o r l d d e d i c a t e d to ad- v a n c i n g t he s c i e n c e , t e c h n o l o g y a n d a p p l i c a t i o n of mate r ia l s jo in ing . H e a d q u a r t e r e d in Miami, Fla.,AWS s e r v e s a p p r o x i m a t e l y 50 ,000 m e m b e r s in t he l l n i t ed States and a r o t m d the wor ld . AWS is d e d i c a t e d to p r o v i d i n g leader- s h i p a n d s e r v i c e s , a n d w o r k s to s e r v e a n d c o o r d i n a t e t h e j o i n i n g i n d u s t r y in m a t t e r s of c o d e s , s t a n d a r d s , ma- t e r i a l s , e d u c a t i o n , c e r t i f i c a t i o n a n d r e s e a r c h . AWS c a n be found at II'll'll'.glll'S. o r g o n t he Web. •

WELDING JOURNAL I ss

• Pittsburgh Students Visit Sheet Metal Workers' Apprentice Training Facility

Students f rom the South Vo-Ik, ch High School, Pittsburgh, Pa., welding program visited the Local ¢~12 Sheet Metal Workers Apprenticeship Training School facility to learn about the various welding techniques they utilize. Instructor George Kirk accompanied the students on the field trip.

• C A N W E TALK? The Welding Journal staff encourages an exchange of ideas with you, our

readers. If you'd like to ask a question, share an idea or voice an opinion, you can call, write, e-mail or fax. Staff e-mail addresses are listed below, along with a guide to help you interact with the right person.

Pub l i she r J e f f Weber [email protected] General Management, Reprint Permission, Copyright Issues

Editor Andrew Cull ison [email protected] Article Submissions

Adver t i s ing Sales Director Rob Saltzstein

[email protected] Advertising Sales

Adver t i s ing P roduc t ion Manager Col leen Beem

[email protected] Advertising Production

Features Editor Mary Ruth J o h n s e n

[email protected] Feature Articles

Adver t i s ing Coordinator Lea Garr igan

[email protected] Production and Promotion

Associate Editor Susan Campbe l l [email protected] Society News

Assistant Editor Doreen Yamamoto [email protected] New Products

Managing Edi tor Chr is t ine Tarafa [email protected] Design and Production

Product ion Assistant Zaida Chavez [email protected] Design and Production

Peer Review Coordinator D o r e e n Kubish

[email protected] Peer Review of Research Papers

Department Secre tary Paola Chac6n

[email protected] General Information

Welding J o u r n a l Dept. 550 N.W. LeJeune Rd. Miami, FL 33126 (800) 443-9353 ext. 348 FAX (305) 443-7404

• Volunteers Sought for the D9 Commit tee on Welding, Brazing and Soldering of Sheet Metal

T he Amer ican Welding Soci- ety (AWS) D9 Commit tee on Welding, Brazing and Solder-

ing of Sheet Metal is looking to add members to the Committee.

The Commit tee recent ly pub- l i shed AWS D9.1:2000, Sheet Metal Welding Code.The Commit- tee is set to beg in the nex t revi- s ion of the code . Ind iv idua ls k n o w l e d g e a b l e in the w e l d i n g and braze weld ing of sheet metal in nons t ruc tu ra l appl ica t ions are encouraged to apply. Contractors , we ld ing ins t ruc to r s and w e lde r s invo lved in hea t ing , ven t i l a t i ng and air c o n d i t i o n i n g , food process ing e q u i p m e n t , cabine t ry , e l e c t r i c a l pane l s or o t h e r non- structural appl icat ions are particularly sought.

If you are i n t e r e s t e d in par- t i c i pa t i ng in this work, p l ease submi t your a p p l i c a t i o n on the AWS Web site at www.aws .org or con tac t the D9 Commi t t ee Secre- tary, J o h n Gayler, at (800) 443- 9353 ext . 472 or via e-mail at [email protected]. •

• O r d e r i n g A W S

P u b l i c a t i o n s

AWS publ ica t ions are n o w be ing d is t r ibuted by Global Engi- neer ing Documents .To order publications, call Global at (800) 854- 7179. Publicat ions can also be ordered from the e-store on the AWS Web site at www.aws.org. •

56 I FEBRUARY 2001

S A F E T Y A N D H E A L T H T O P I C S

• Thermal Spraying Fact S h e e t N o . 20

I n t r o d u c t i o n

Thermal spraying p roces ses use modif ica t ion of arc, plasma and oxyfuel energy sources to p r o d u c e the resulting heat, a t m o s p h e r e and part icle velocity needed to properly coa t an ob j ec t (a subs t r a t c ) w i t h the des i r ed thick- ncss and p rope r t i e s of a surfacing mater ial .The high tem- pe ra tu re s , ve loc i ty and p ro j ec t i l e d i s t ance of the spraying p roces ses create a unique set of safety hazards for the opera to r and those nearby.

D e f i n i t i o n s / P r o c e s s D e s c r i p t i o n s

A c c o r d i n g to ANSI/AWS A3.0, Standard Welding Terms and Defini t ions, t h e r m a l sp ray ing (THSP) is a g roup of p r o c e s s e s that depos i t mo l t en metal l ic or non- meta l l ic su r fac ing mate r ia l s o n t o a p r e p a r e d subs t r a t e . All thermal spraying p roces ses introdt lcc a feeds tock (usl_l- ally a p o w d e r or wire) into a heat ing device ( combus t ion or e l e c t r i c a l ) . T h e r e , the mater ia l is hea t ed , b l e n d e d to t he hea t p l u m e and sp rayed o n t o a p r e p a r e d subs t ra te . The mol ten par t ic les str ike the surfftce, f la t ten and form th in p la t e l e t s that c o n f o r m and a d h e r e to the subs t r a t e and to one another.As they cool, part icles build up a lamel- htr s t r u c t u r e to fo rm the de s i r ed coa t ing . C o m b u s t i o n p r o c e s s e s inc lude low-vek)city nxyfuel (LVOF) and high- velocity oxyfuel (HVOF) systems. Electrical p rocesses are arc ( two-wi re ) , p lasma arc ( p o w d e r ) and p lasma induc- t ion ( p o w d e r ) sys tems.Typica l ope ra t i ng c o n d i t i o n s for the various p roces ses are s h o w n in Table 1 below.

c a r b o n s o l v e n t v a p o r in t h e area of t h e arc or p l a s m a sp ray ing . Haza rdous p h o s g e n e gas can be p r o d u c e d w h e n h y d r o c a r b o n vapors are e x p o s e d to ul traviolet radiat ion f rom these p roces ses .

• N o i s e - The loud noise (high dBA ranges) of these p r o c e s s e s mus t be a d d r e s s e d . Ear muffs and no i se control p r o c e d u r e s s h o u l d be p r o v i d e d to c o n f o r m to t he s tandard limits of OSHA 29 CFR 1910.95.

• R a d i a t i o n - In tense ul traviolet (UV) and infrared (IR) radia t ion o c c u r w i th t hese p r o c e s s e s . T h e y requ i re total p ro tec t ion of the eyes and all e x p o s e d skin to avoid eye damage and burns. Eye shades of No. 3 -6 for combus- t ion and 9- 12 for e lectr ical p r o c e s s e s are r e c o m m e n d e d (see AWS Safetv and Health Fact Sheet No. 2).

• E l e c t r i c S h o c k -The h igher p rocess w)ltagcs used in arc, plasma arc and plasma induc t ion spraying increase the risk of e l ec t r i c shock .Take p r e c a u t i o n a r y m e a s u r e s according to ANSI Z49.1 and AWS Safety and Health Fact Sheet ?v~. 5.

• F i r e - Use care w h e n opera t ing spray guns to aw)id injury to pe r sonne l or causing a fire (see AX~'S Safe O, and Health Fact Sheet No. 6).

¢ M e c h a n i c a l H a z a r d s - T h e s u b s t r a t e su r face prepara t ion , spraying, f inishing and pos t - t r ea tmen t oper- a t ions involved wi th thermal spraying p r o c e s s e s p r e sen t a variety of mechanica l hazards specif ic to thermal spraying. Consul t the e q u i p m e n t manufac tu re r ' s manuals and mater ia l s u p p l i e r ' s MSDSs for t he i r r e c o m m e n d e d safe pract ices .

• C o m p r e s s e d G a s e s - C o m p r e s s e d gases requi re safe handl ing and use as specif ied in ANSI-Z49.1.

I n f o r m a t i o n S o u r c e s

P o t e n t i a l H a z a r d s and H a z a r d o u s Effects

¢ D u s t - Finely d iv ided a i r b o r n e sol id pa r t i cu l a t e shou ld be t rea ted as an explos ive and inhalat ion hazard. A d e q u a t e ven t i l a t i on and w e t c o l l e c t i o n of ove r sp ray should be p rov ided to minimize these hazards.

¢ F u m e s , V a p o r s a n d G a s e s - V e n t i l a t e and use safe p r a c t i c e s a c c o r d i n g to ANSI Z49.1, ti le MSDSs and AWS Safety and Heal th Fact Sheet No. 1. In add i t i on , most spray and abrasive blas t ing o p e r a t i o n s requi re the use of an a p p r o v e d r e s p i r a t o r tha t c o m p l i e s w i t h re- q u i r e m e n t s of ANSI Z88.2 .Also , p r e c a u t i o n s shou l d be e x e r c i s e d to aw)id the p r e s e n c e of c h l o r i n a t e d hydro-

American National Standards Inst i tute (ANSI). Safety in Welding, Cutting and Allied Processes, Z49.1 .American Welding Society, 550, N.W. LeJeune Rd., Miami, FL 33126.

American National Standards Inst i tute (ANSI). Safi, O, Practices f o r Occupat ional and Educat ional Lye and l~lce Protection, Z87.1 .Amer ican National Standards In- stitute, 11 West 42nd St., New York, NY 10036.

Amer i can National S tandards Ins t i tu te (ANSI). Safe Practices f o r Respiratory Protection, Z88.2. A m e r i c a n National Standards Inst i tute, 11 West 42nd St., New York, NY 10036.

---continued on page 58

Table I --Typical Operating Conditions for the Various Processes

LVOF HVOF Arc Plasma Arc Plasma Induction (Atmosphere)

Temperature to 5000°F to 6000°F 4000-15,000°F 4000-15,000°F to 30,000°F Velocity 200-700 PUs 2500-4000 PUs 800-1100 PUs 800-1800 PUs 800-1800 PUs

(<Mach I) (to Mach 5) (<Mach 2) (to Mach 2) (to Mach 2) dBA (Sound Level) I I 0 150 I 15 132 132 Spray Distance 4-10 in. 6-18 in. 2/2-6 in. 2½~ in. 3-8 in.

W E L D I N G J O U R N A L I s 7

• AWS Expo Named Top-Ranking Show

T ' hc A m e r i c a n We l d i ng Soc ie ty (AWS) I n t e r n a t i o n a l W e l d i n g a n d Fabri- ca t ing Expos i t ion has b e e n n a m e d o n e of the top t rade s h o w s by Expo M a g a z i n e . Based o n i n f o r m a t i o n f rom e x h i b i t surveys , t he S e p t e m b e r

i s sue of E x p o f o u n d t he AWS Expo a t t r a c t s t h e h i g h e s t p e r c e n t a g e of first- t ime a t t e n d e e s . T h e AWS Expo was c o m p a r e d w i t h a n u m b e r of na t i ona l and i n t e r n a t i o n a l t r ade s h o w s , i n c l u d i n g C o m d e x and FABTECH, m a k i n g t he In- t e r n a t i o n a l W e l d i n g a n d F a b r i c a t i n g E x p o s i t i o n o n e of t h e t o p - r a n k i n g annual shows .

B e g i n n i n g in 2001, e v e r y t h i n g t he AWS Expo has to o f fe r will c o m b i n e w i t h t h e t e c h n o l o g y a n d p r o g r a m s of t h e P r e c i s i o n M e t a l f o r m i n g Associa- t i on ' s (PMA) METALFORM s h o w to c r ea t e MAX I n t e r n a t i o n a l M a n u f a c t u r i n g App l i ca t ions Exhib i t ion .

The first MAX In t e rna t i ona l will r un May 6 - 1 0 at the I-X C e n t e r in Cleve- land, Ohio. More t h a n 800 ,000 sq ft of exh ib i t space , h o u s i n g more t han 1200 e x h i b i t o r s wi l l b r i n g t o g e t h e r t h e l a t e s t t e c h n o l o g y in w e l d i n g , s t a m p i n g , cu t t i ng and fabr ica t ing e q u i p m e n t . T h e c o m b i n a t i o n of t he se w o r l d - r e n o w n e d s h o w s will give t ens of t h o u s a n d s of a t t e n d e e s the grea tes t s e l ec t ion of equip- m e n t and mater ia l s eve r of fered in one place.

Exh ib i t i on space and e v e n t r eg i s t r a t ion are still available. C o m p a n i e s in- t e r e s t e d in e x h i b i t i n g t h e i r p r o d u c t s and s e r v i c e s s h o u l d c o n t a c t t h e AWS C o n v e n t i o n and E x p o s i t i o n D e p a r t m e n t at ( 8 0 0 ) 4 4 3 - 9 3 5 3 ext . 221. Up-to- da te -even t in fo rmat ion , inc lud ing specia l c o n f e r e n c e sess ions and r ecep t ions , is avai lable on the AWS Web site at w w w . a w s . o ~ g . •

• Santa ClaritaValley College Responds to Demands of High-Tech Industries

T h e Co l l ege o f t h e C a n y o n s , l o c a t e d in Va lenc ia , Calif. , h a s b e e n sup- p l y i n g s o u t h e r n C a l i f o r n i a i n d u s t r y w i t h s k i l l e d c e r t i f i e d w e l d e r s s i nce 1 9 7 6 . W i t h t he r ap id e x p a n s i o n of h i g h - t e c h n o l o g y b u s i n e s s in

t h e San ta Cla r i t a va l ley a n d vic ini ty , t h e r e has b e e n a g r o w i n g d e m a n d for w e l d e r s w i t h a u t o m a t i o n s k i l l s . T h e s e p o s i t i o n s o f f e r g r e a t e r pay a n d requ i re c o m p u t e r skills.

J ack C o m p t o n , d i r e c t o r of t h e c o l l e g e ' s w e l d i n g p r o g r a m , b e g a n offering an o rb i t a l w e l d i n g class in J a n u a r y 1 9 9 9 . W i t h s u p p o r t f r om s u c h corn- p a n i c s as Arc M a c h i n e s , PCI E n e r g y S e r v i c e s a n d D i m e t r i c s , t h e o r b i t a l w e l d i n g p r o g r a m has b e e n s ucce s s f u l l y t r a i n i n g s t u d e n t s for p l a c e m e n t in h i g h - t e c h n o l o g y m a n u f a c t u r i n g a n d c o n s t r u c t i o n f ie lds . W i t h t h e r e c e n t g e n e r o u s d o n a t i o n of s ta te -of - the-ar t o rb i t a l w e l d i n g e q u i p m e n t by Arc Ma- c h i n e s , Inc . , P a c o i m a Calif., t h e w e l d i n g t e c h n o l o g y p r o g r a m has b e e n sig- n i f i c a n t l y e n h a n c e d . In a d d i t i o n , U n i t e k Miyach i Laser Sys t ems Div., Mon- rovia, Calif., has p r o v i d e d the la tes t in l o w - p o w e r YAG laser w e l d i n g equ ip - m e n t , as wel l as a va r ie ty of smal l -sca le f ine spo t r e s i s t a n c e w e l d i n g equ ip - m e n t . " W i t h t h e n e w i n f l u x of laser, o r b i t a l a n d r e s i s t a n c e w e l d i n g e q u i p - m e n t , w e h a v e e x p a n d e d o u r c u r r i c u l u m to i n c l u d e f u n d a m e n t a l s of resis- t ance , laser b e a m a n d o rb i t a l gas t u n g s t e n arc we ld ing , " said C o m p t o n .

S t u d e n t s are c u r r e n t l y b e i n g t r a i n e d o n an AMI Mode l 227 p o w e r supply, M o d e l s 15 a n d 79 w e l d i n g h e a d s for o r b i t a l w e l d i n g . Laser w e l d i n g t r a i n i n g is b e i n g s u p p o r t e d w i t h a U n i t e k Miyachi Mode l LW-250 l o w - p o w e r YAG sys t em. For r e s i s t a n c e w e l d i n g , t r a i n i n g is a c c o m p l i s h e d o n Miyach i M o d e l s IP-217A, IP-215 A p o w e r s u p p l i e s a n d M o d e l s MH-80 a n d MH-88 w e l d h e a d s . T h i s b r o a d s p e c t r u m of w e l d i n g p r o c e s s a p p l i c a t i o n s , a l o n g w i t h h a n d s - o n w e l d i n g e x p e r i e n c e e n a b l e s s t u d e n t s to seek c a r e e r s in t he a e r o s p a c e , s e m i c o n d u c t o r , p e t r o c h e m i c a l , p o w e r g e n e r a t i o n , food and med- ical i ndus t r i e s .

The Co l l ege of t h e C a n y o n s is t h e on ly c o m m u n i t y c o l l e g e in Cal ifor- n ia e q u i p p e d w i t h t h i s r a n g e of a u t o m a t e d w e l d i n g e q u i p m e n t . T h e pa r t - n e r s h i p of loca l i n d u s t r y a n d t h e Co l l ege of t h e C a n y o n s p r e s e n t s a g r ea t o p p o r t u n i t y for s t u d e n t s w h o are s e e k i n g h i g h - t e c h n o l o g y c a r e e r s in au- t o m a t e d w e l d i n g . •

S A F E T Y A N D H E A L T H

T O P I C S - - continued from page 57

A m e r i c a n N a t i o n a l S t a n d a r d s I n s t i t u t e (ANSI). SaJ'i.,tF R e q u i r e - m e n t s f o r I n d u s t r i a l H e a d Protec- t ion, Z89 .1 .Amer ican National Stan- d a r d s I n s t i t u t e , l 1 West 4 2 n d St., New York, NY 10036.

O c c u p a t i o n a l Safety and Heal th A d m i n i s t r a t i o n (OSHA). Code q [ Federal Regu la t i ons ,T i t l e 29 Labor, C h a p t e r XVII, Par ts 1901.1 to 1910 .1450 , O r d e r No. 869-O19- OOll 1-5. S u p e r i n t e n d e n t of l )ocu- merits, U.S. G o v e r n m e n t Pr in t ing Of- r ice ,Washington , DC 02402.

Na t iona l Fire P r o t e c t i o n Asso- c i a t i on (NFPA). S t a n d a r d f o r Fire P r e v e n t i o n in Use o [ C u t t i n g a n d W e l d i n g Processes , NFPA S t a n d a r d 5 lB. Na t iona l Fire P r o t e c t i o n Asso- c i a t ion , O n e B a t t e r y m a r c h Park, Quincy, MA 02269.

Na t iona l Fire P r o t e c t i o n Asso- c ia t ion (NFPA). N a t i o n a l E lec t r ica l Code, NFPA S tanda rd 70. N a t i o n a l Fire P ro t ec t i on Associat ion, One Bat- t e r y m a r c h Park, Quincy, MA 02269.

Na t iona l Fire P r o t e c t i o n Asso- c ia t ion (NFPA). S t a n d a r d fi~r the De- s i gn o f O x g g e n - F u e l Gas 3~1~stems .fi~r Weld ing a n d Cu t t i ng a n d A l l i ed Process, NFPA Standard 51. Nat ional Fire P ro tec t ion Associat ion, One Bat- t e r y m a r c h Park, Quincy, MA 02269.

C o m p r e s s e d (;;is A s s o c i a t i o n (CGA). Safe, H a n d l i n g o f Com- p r e s s e d Gas C y l i n d e r s , CGA P-I. C o m p r e s s e d Gas Assoc ia t ion , 1725 Je f f e r son Davis Highway, Ste. 1004, Arl ington, VA 22202

Robo t i c Indus t r i e s Assoc ia t ion (RIA). S a f e t y R e q u i r e m e n t s f o r In- d u s t r i a l R o b o t s a t t d R o b o t 5~},s- terns, RIA R 15.O6. Robot ic Indus t r i e s Associa t ion , P.O. Box 3724, 900 Vic- tors Way, Ann Arbor, MI 48106.

A m e r i c a n We ld ing Soc ie ty (AWS). T h e r m a l Spr toqng: Practice, T h e o r y a n d A p p l i c a t i o n . A m e r i c a n W e l d i n g Society, 550 N.W. LeJeune Rd., Miami, FL 3 3 1 2 6 . 4

The Safety and Health Fact Sheets, 2nd ed., cover all aspects o f safe O, and health applicable to welding and cutting. The Fact Sheets include 20 pages on suhjects such as f umes and gases, radiation, noise and electrical hazards. Compiled in 199@ Price forAWS members is $27; nonmembeJw, $36. Copies of Safety and Health Fact Sheets can be ordered by calling Global Engineering Documents at (800) 854-7179 or through the AWS P~Teb site at www.aws.org.

58 I FEBRUARY 2001

, Nomina t ions for Distr ict D i rec tor The t e rm of office lbr District l ) i rec tors in the folh)wing Districts will t e rmina te on May 31,2002. As District Nominat-

ing Commi t t ee s will be a p p o i n t e d this spring, it is t ime to th ink of pos i t ion nomina t ions . For fu r the r in lormat ion , use your cu r ren t District 1)irector's contac t informat ion given below.

• Distr ict 3 Claudia B. Bottenfield Manager Dressel Welding Supply, Inc. 20 Prestige Lane Lancaster, PA 17603 (717) 397-1312 FAX: (717) 394-6845 E-mail: cbottenfield@dressel I .corn

• Distr ict 15 *lack I). Heikkinen President Spartan Sauna t lcaters , Inc. 7484 Malta Rd. Evcleth, MN 55734 (218) 741-8433 E-mail: spar tans@cpin te rne t . com

• Distr ict 6 Gerald R. C rawmer General Electric Power Genera t ion Engineer ing 11 Whee le r Drive Clifton Park, NY 12065-1819 (518) 385-0570 FAX: (518) 385-9717 E-mail: [email protected] .com

• Distr ict 9 *John C. Brnskot ter Project Manager Project Specialists, Inc. 405 Gretna Blvd., Ste. 208 (;retna, LA 70053 (504) 367-0603 FAX: (504) 367-0559 E-mail: jbruskot ter@projectspecial is ts .com

• Distr ict 12 *Michael 1). Kersey Technical Sales Representa t ive The Lincoln Electric Co. W223 N798 Saratoga l)r. #H Waukesha, WI 53186 (262) 650-9364 FAX: (262) 650-9370 E-mail: Michael D Kersey@lincolnelectr ic .com

• Distr ict 18 '~lim M. Appledorn Regional Sales Manager The l,incoln Electric Co. 123 N. Berryline Circle Woodlands,TX 77381 (888) 321-9353 FAX: (281) 847-9494 E-mail: j im_apt~ledorn@lincolnelcct rio.corn

• Distr ict 21 *Bob Schneider, Jr. Chief Consul tant Bob Schneider Consul t ing Services 7235 Canyon Breeze Rd. San Diego, CA 92126 (858) 693-1657 FAX (858) 693-4352 E-mail: bscs@pacbel l .net

* l )enotes eligibility for e lec t ion for a n o t h e r three-year term. •

, A W S Publ icat ions • Standard Methods for MechanicaITesting of Welds

T h e A m e r i c a n W e l d i n g S o c i e t y h a s c o m p l e t e d t h e n e w e d i t i o n of Standard Metbods Jbr Mechanical 70st- ing o f Welds (AWS B 4 . 0 M : 2 0 0 0 ) . l ) e v e l o p e d u n d e r t h e g u i d a n c e of i n d u s t r y e x p e r t s , t h i s s t a n d a r d c o v e r s t h e c o m m o n m e t h o d s for t h e m e c h a n i c a l t e s t i n g of w e l d s , i n c l u d i n g b e n d , t e n s i o n , f r a c t u r e and o t h e r tes ts .

Standard Metbods.for Mechanical TestDtg o f Welds c o n t a i n s d e t a i l e d f i g u r e s to a s s i s t u s e r s in a c c u r a t e l y t e s t i n g w e l d s . For e a c h t e s t i n g m e t h o d , i n f o r m a t i o n is p r o v i d e d o n o t h e r a p p l i c a b l e s t a n d a r d s , s u c h as ANSI a n d ASTM, t e s t i n g r e q u i r e m e n t s a n d s a m p l e p r c p a r a -

t ion , as wel l as all t h e n e c e s s a r y t e s t r e p o r t i n g r equ i r e - m e n t s .

T h e n e w e d i t i o n of Standard Metboclsfi)r Met'ban- ical Testing ofl~t, lds is 104 pages and lists for $68, $51 for AWS m e m b e r s .

Ordering Information

Slam/a rd Metbods fi)r,lh, cbanical Test#(q of WeMs, as well as all o ther AWS publications, can bc ordered hy calling Global Engineering Documents at (800) 854-7179, or by visiting the e- store on theAWSWeh site at wtvzl:aws.o~. •


• Sustaining Member Company

T E A M Industries, Inc. T eam Indus t r i e s , Inc. , is a na- t i o n a l l y r e c o g n i z e d sup- o l i e r o f s h o o f a b r i c a t e d 1200 Maloney Road [ P

P. O. Box 350 p i p i n g , A S M E C o d e p r e s s u r e ves- K a u k a u n a , W I 54130 sels , n o n c o d e t a n k s a n d m o d u l a r (920) 766-7977 p i p i n g e q u i p m e n t sk ids . Es tab- www.teamind.com l i s h e d in 1987 b y a s m a l l g r o u p

o f p r i v a t e i n v e s t o r s a n d 17 em- p l o y e e s , t h e c o m p a n y has g r o w n

to m o r e t h a n 200 e m p l o y e e s s e r v i n g an i n t e r n a t i o n a l c u s t o m e r base . T h e c o m p a n y ' s f a b r i c a t i o n s e r v i c e s are u s e d in m a n y m a r k e t s , i n c l u d - ing p r o c e s s i n g , p e t r o c h e m i c a l a n d re f in ing , w a s t e wa te r , fer t i l izer , min- ing, i n d u s t r i a l p r o c e s s , h a z a r d o u s was te , p o w e r a n d c o g e n c r a t i o n .

T h e c o m p a n y ' s g r o w t h c a n b e a t t r i b u t e d to i t s f o c u s o n m e e t i n g c u s t o m e r n e e d s t h r o u g h o n - t i m e d e l i v e r y of h i g h - q u a l i t y p r o d u c t s . In a d d i t i o n to TEAM's i n t e g r a t e d e n g i n e e r i n g , c o m p a t i b l e w i t h t o d a y ' s 3-D d e s i g n p r o g r a m s , a n d dai ly t r a c k i n g of t h e p r o g r e s s of e a c h p i p i n g a s s e m b l y t h r o u g h t h e c o m p a n y ' s s h o p , T E A M ' s c u s t o m c o m p u t e r sys- t e m c a n p r o v i d e t i m e l y c o s t a c c u m u l a t i o n a n d c o s t p r o j e c t i o n s to i ts c u s t o m e r s .

T h e c o m p a n y ' s 100 ,000 - sq - f t p r o d u c t i o n f a c i l i t i e s a rc e q u i p p e d w i t h b o t h c u s t o m a n d s t a t e - o f - t h e - a r t e q u i p m e n t . M u l t i p l e w o r k bays p e r m i t s e g r e g a t i o n o f c a r b o n a n d s t a i n l e s s s t e e l p i p i n g f a b r i c a t i o n ( s p o o l s ) w i t h a d d i t i o n a l a reas ava i l ab l e for p l a t e a n d t a n k f a b r i c a t i o n , m o d u l a r a s s e m b l y , s u r f a c e p r e p a r a t i o n a n d p a i n t i n g , h y d r o s t a t i c tes t - ing , n o n d e s t r u c t i v e e x a m i n a t i o n a n d a p p l i c a t i o n s r e q u i r i n g s p e c i a l c l e a n i n g a n d t e s t ing .TEAM has an a n n u a l ave rage o u t p u t of 25 ,000 piping s p o o l s a n d t he c a p a b i l i t y of f a b r i c a t i n g t anks and vesse l s r a n g i n g in s ize f r o m 2- to 18-ft d i a m e t e r s . T h e c o m p a n y ' s u p l i f t i n g c a p a c i t y is 40 t o n s a n d it has f a b r i c a t e d vesse l s up to 60 ft in l eng th .

TEAM's h i g h l y s k i l l e d u n i o n c r a f t s m e n ( U n i t e d A s s o c i a t i o n o f P l u m b e r s a n d S t e a m f i t t e r s , Local # 4 0 0 ) p r o v i d e c o n f i d e n c e in t h e ac- c u r a c y a n d i n t e g r i t y of t h e c o m p a n y ' s w e l d e d c o m p o n e n t s . T h e c o m - p a n y ' s h i g h l y sk i l l ed w e l d e r s are e x p e r i e n c e d in a v a r i e t y o f a l loys in- c l u d i n g l o w t e m p e r a t u r e , s t a in le s s , c h r o m e moly, n i cke l , Hastal loy, tita- n i u m and dup l ex .

The c o m p a n y ' s qual i ty c o n t r o l sys t em car r ies two ASME Code s t a m p s ("PP" and "U"). Most QC p e r s o n n e l are Ce r t i f i ed We ld ing I n s p e c t o r s (o r CAWIs) .The c o m p a n y has 14 e m p l o y e e s c u r r e n t l y h o l d i n g c e r t i f i c a t i o n as AWS CWI (o r CAWI) in e x e c u t i v e m a n a g e m e n t , e n g i n e e r i n g , p r o j e c t m a n a g e m e n t , qua l i ty c o n t r o l and w e l d i n g and f i t t ing p o s i t i o n s . T h e com- p a n y also has o n e ASNT Cer t i f ied NDT Level III p e r s o n on staff.

TEAM is a s t r o n g s u p p o r t e r of t h e w e l d i n g i n d u s t r y a n d r e g u l a r l y p a r t i c i p a t e s in t he c o d e d e v e l o p m e n t ac t iv i t i e s of AWS,ASME and PFI. •

• Submi tYourTechn ica l C o m m i t t e e Reports

C o m m i t t e e C h a i r m e n - - We w a n t to r ecogn ize the effor ts of your c o m m i t t e e and in form ou r readers of its a c c o m p l i s h m e n t s . Send a b r i e f profile of its activit ies and recen t accompl i shmen t s , a long w i th a m e m b e r ros ter and con tac t numbers , and we will publ i sh it in the Welding Journal's Society News section.

Send your submiss ions to

Susan Campbel l ,Associa te Editor Amer i can Welding Society

550 N.W. LeJeune Rd. Miami, FL 33126

Te lephone , (305) 443-9353 ext. 244, FAX: (305) 443-7404 e-mail: campbell@ aws. org •

60 J FEBRUARY 2001

A W S W E L C O M E S

N E W S U P P O R T I N G C O M P A N I E S

N e w S u p p o r t i n g C o m p a n i e s

Cives Acero 4619 San Dario Ave., Ste. 427 Laredo,TX 78041

Factory Abdulla Khalifa & Partners Co. PO. Box 767 Jubail 31951 Saudi Arabia

Moody Cons t ruc t ion Services, Inc. 12450 County Rd. 39 Duette, FL 33834

N e w Educat iona l I n s t i t u t i o n s

Cecil Communi ty College 107 Railroad Ave. Elkton, MD 21921

Greater LawrenceTechnica l School 57 River Rd. Andover, MA 01810

Quen t in Burdick Job Corps 1500 Universi ty Ave.West Minor, ND 58703

National Pipeline Welding School 4845 S. 83rd E. Ave. Tulsa, OK 74147-0950

Waltham Public Schools-Vocational 617 Lexington St. Waltham, MA 02452-3098

• A W S MEMBERSHIP

M e m b e r As o f Grades J a n u a r y 1, 2001

Sustaining Companies .................... 327 Suppor t ing Companies .................. 153 Educational Inst i tut ions ................. 164 Tota l Corporate Members .......... 644

Individual Members .................. 43,545

Student Members ........................ 4,876

T o t a l M e m b e r s ..... 4 8 , 4 2 1

• Tenth International JOM Jubilee Conference

T ile I n s t i t u t e for t i le J o i n i n g o f M a t e r i a l s ( JOM) ha s an- n o t m c e d t i le T e n t h I n t e r n a -

t i ona l JOM J n b i l e e ( ; o n f e r e n c c o n t h e J o i n i n g o f M a t e r i a l s , J O M - 1 0 , May 11-14 , in Hels ingor , D e n m a r k .

Ti le f o l l o w i n g are t h e m a i n t h e m e s of JOM-IO:

• I n f o r m a t i o n t e c h n o l o g y , cases in its e x p l o i t a t i o n , as wel l as p r e d i c t i o n o f i ts w d n e , for f u t u r e and p r e s e n t w e l d i n g f ab r i ca t i on .

• R o b o t i z a t i o n a n d a u t o m a - t i on in w e l d i n g a n d a s s o c i a t e d p r o c e s s e s .

• Brazing, s o l d e r i n g and asso- c i a t e d p r o c e s s e s in , l o n m e l t jo ining.

JOM w e l c o m e s ti le ac t ive sup- po r t (flAWS to t he .IOM-10 throt , gh s p e a k e r s a n d p a r t i c i p a n t s . AWS c o s p o n s o r e d p r e v i o u s J O M confer - e n c e s 7 t h r o u g h 9.

For fur ther informat ion on JOM- 10, con tac t the Ins t i tu te for the Join- ing of Materials, Klintchoj Vaenge 21, DK-3460 Birkerod, Denmark ; e-mail to join a w s @ p o s t l 0 . t e l e . d k ; tele- p h o n e 45 45 82 80 9 5 ; o r FAX 45 45 94 08 55. •

• V i s i t A W S o n t h e W e b

The wor ld of AWS is as c lose as a click of your mouse .Whi l e visit ing the Amer ican Welding Society 's Web site, you can r e n e w your m e m b e r - ship , buy b o o k s and s t anda rds and even h )ok /b r a new job.To see what ' s on the Web site for you, just visit b t t p . / / wu,u' , aws .o rg . •

• AWS F o u n d a t i o n o n t h e W e b

For f u r t h e r i n f o r m a t i o n on the AWS F o u n d a t i o n s c b o l a r s h i p a n d s t u d e n t l oan p r o g r a m s , v is i t the AWS F o u n d a t i o n o n t h e W e b at w w w . a w s . o r g / f o u n d a t i o n / . •

• Sustaining Member Companies

Wolfe Engineering, Inc. w o l fe E n g i n e e r i n g is a n es- t a b l i s h e d l e a d e r ill t h e de-

a n d f a b r i c a t i o n o f 546 Div i s ion S t r e e t s ign C a m p b e l l , C A 9 5 0 0 8 h i g h - q u a l i t y p r e c i s i o n p a r t s a n d (408) 379-8580 s u b a s s e m b l i e s fo r t h e m i c r o e l e c - www.wolfe-engr.com t r o n i c s a n d a e r o s p a c e i n d u s t r i e s .

S i n c e 1992 , t i le c o m p a n y h a s suc- c e s s fu l l y p a r t n e r e d w i t h m a j o r c o l

p o r a t i o n s by p r o v i d i n g i ts o w n b r a n d o f c u s t o n l i z e d m a n u f a c t u r i n g , en- g i n e e r i n g SUl)port a n d l e a d i n g - e d g e t e c h n o l o g i e s .

Wolfe o f f e r s a b r o a d r ange of s e r v i c e s , i n c l u d i n g t h e fo l l owing : ¢ T u r n k e y p a r t s n l a n u f a c t u r i n g in a c c o r d a n c e w i t h c l i e n t s p e c i f i c a -

t ions . • C u s t o m i z e d e n g i n e e r i n g a n d f a b r i c a t i o n for s u b a s s e m b l i e s a n d

re t ro f i t s . • Rush a s s e m b l y ;lnd o v e r n i g h t s e r v i c e . • Core c o m p e t e n c i e s in h i g h - p u r i t y c l e a n r o o m m a n u f a c t n r i n g . • Tes t ing , i n s p e c t i o n and qua l i t y a s s u r a n c e . Wolfe E n g i n e e r i n g w a s e s t a b l i s h e d in d i r e c t r e s p o n s e to s u p p l i e r ' s

n e e d s for p r e m i u m q u a l i t y t u r n k e y m a n u f a c t u r i n g w h i l e m e e t i n g d e a d - l ines . T e c h n o l o g y c o m p a n i e s s o o n r e c o g n i z e d t h e c o s t b e n e f i t s a s soc i - a t e d w i t h o u t s o u r c i n g s p e c i a l i z e d f a b r i c a t i o n p r o j e c t s , a n d Wol fe Engi- n e e r i n g a n s w e r e d t h e cal l . T h e c o m p a n y ' s u n i q u e p o r t f o l i o o f s e r v i c e s a l l ows c u s t o m e r s to a c h i e v e s i g n i f i c a n t r e d u c t i o n s in o v e r h e a d and l o w e r o p e r a t i o n c o s t s . T h e c o m p a n y has m o r e t b a n 40,00I) sq ft of m a n u f a c t u r - ing area and t w o c l e a n r o o m s fl)r h i g h - p u r i t y assembly . •

Merriam-Graves Corporation M e r r i a m - G r a v e s C o r p . is o n e

o f t i le l a r g e s t i n d e p e n d e n t 933 R o u t e I B y p a s s i n d u s t r i a l g a s a n d w e l d i n g Portsmouth, NH 03801-3553 s n p p l y d i s t r i b n t o r s in t i le n o r t h e a s t - (603) 433-0855 ern USA. www.merriam-graves.com T h e c o m p a n y h a s 20 s t r a t e g i -

ca l ly l o c a t e d b r a n c h e s in s ix s t a t e s , w i t h m o r e t h a n 75 t r u c k s d e l i v e r i n g

p r o d u c t s to i ts c l i en t s . S u p p o r t i n g t h e s e l o c a t i o n s is a 33 ,000-sq- f t p u m p - ing p l a n t , e q u i p p e d w i t h c o m p u t e r - d r i v e n f i l l ing and m i x i n g e q u i p m e n t , w h i c h e n s u r e s t h e a c c u r a c y of m i x t u r e s , p u r i t y o f t h e p r o d u c t a n d guar- a n t e e s c u s t o m e r s t h e h i g h e s t qt, a l i ty p r o d u c t s . In a d d i t i o n , a 20,O00-sq-f t m a t e r i a l s d i s t r i b u t i o n c e n t e r p r o v i d e s n e x t - d a y s e r v i c e to c u s t o m e r s in t i le n o r t h e a s t .

M e r r i a m - G r a v e s a lso has a w e l d i n g m a c h i n e r e p a i r f:lcili ty s t a f f ed by t r a i n e d , a u t h o r i z e d r e p a i r t e c h n i c i a n s . T h e c o m p a n y ' s qua l i t y r e p a i r w o r k a n d q u i c k t t t r n a r o t m d t i m e k e e p d o w n t i m e to a m i n i m u m . T h e c o m p a n y c a n a lso r e n t c u s t o m e r s a u n i t u n t i l t h e i r w e l d i n g m a c h i n e ' s r e p a i r s a re c o m p l e t e .

T h e c o m p a n y ' s p e r s o n n e l a re t r a i n e d in all o f t h e l a t e s t i m p r o v e - m e n t s in t h e w e l d i n g a n d c u t t i n g i n d u s t r y . F r e q u e n t l y , M e r r i a m - G r a v e s h o l d s p r o c e s s a n d p r o d u c t t r a i n i n g s e m i n a r s for c u s t o n l e r s . T h e s e t ra ining s e m i n a r s f o c u s o n a p a r t i c u l a r a p p l i c a t i o n a n d u t i l i z e t h e e x p e r t i s e of t h e c ( ) m p a n y ' s p r e m i u m s u p p l i e r s to p r o v i d e a t t e n d e e s w i t h t h e t oo l s to i m p r o v e t h e i r k n o w l e d g e of w e l d i n g a n d c u t t i n g . •


E N E

I W S

New Jersey Section m e m b e r Bob Bartley, right, p resen t ing a speaker 's g i f t to gues t speaker Garth Stapon.

D I S T R I C T I Di rec to r : Geof f rey H. P u t n a m

P h o n e : ( 8 0 2 ) 4 3 9 - 5 9 1 6

D I S T R I C T 2 D i r e c t o r : A l f r e d F. F l e u r y

P h o n e : ( 7 3 2 ) 8 6 8 - 0 7 6 8

• LONG ISLAND NOVEMBER 9 Speaker: Skip Swift , distr ict representative. Af f i l ia t ion : Thermal Arc, Stoody Hardfacing and Welding Alloys. Topic: Plasma arc welding: defining process appl ica t ions for automation and low-amperage welding.

• NEW JERSEY NOVEMBER 1 Speaker: G a r t h S tapon , marketing manager, metal fabrication. Af f i l i a t ion : Praxair, Danbury, Conn. Topic: Welding wi th metal-cored wires. Act iv i t y : Bob Von d e r O s t e n , a first-year welding student, was recognized by the Section for be ing Somerset County Vo-Tech Student of the Month and winn ing second

Lehigh Vallc 9, Section Chairman Rich Gallagher, &ft, am/Sec l ion Technical Representat ive JeffWiswesser, right, present ing appreciation gifts to Alstom Power Inc. managers Edward W. Rowlands, second f r o m left, Mark Welkey, center and David H. Cooley, second f r o m right, f o r the detailed p l a n t tour they provided the Section.

D I S T R I C T 3 Direc tor : C l a u d i a B o t t e n f i e l d

P h o n e : ( 7 1 7 ) 3 9 7 - 1 3 1 2

Long Island Section guest speaker Skip Swi f t m a k i n g a p o i n t dur ing his November presentation.

place in the AWS New Jersey Sec- t ion's Welding Competit ion.

• LEHIGH VALLEY NOVEMBER 7 Speaker: E d w a r d W. R o w l a n d s , Jr . , general foreman; D a v i d H. Cooley , vice president; and Mark Welkey. Af f i l i a t ion : Alstom Power Inc., Heat Exchange Division, Easton, Pa. Act iv i t y :The Section received a detailed plant tour with thorough ex- p lana t ions of c o n d e n s e r technology and fabrication.

• NEW YORK NOVEMBER 20 Speaker: D a n i e l T. C a m p b e l l , attorney-at-law. Af f i l ia t ion: Belson, Campbel l and Szuflita. Topic: Employment and labor laws.

D I S T R I C T 4 D i r e c t o r : R o y C. L a n i e r P h o n e : ( 9 1 9 ) 3 2 1 - 4 2 8 5

• SOUTHWEST VIRGINIA NOVEMBER 15 Act iv i ty : Section members met to

62 J FEBRUARY 2001

At the Sotllh Carolina Section's social meeting in November are, f rom &ft, Howard and Nellie Jones with their son, Howard Jones, Jr.

Ed RhodesJorming chain links f o r Dayton Section members at the No- vember meeting.

Southwest [7rgin&t Past Chairman Claude Hol- comb, left, with hostess Michelle Provost, center, and Chairman Ed Wyatt.

Act iv i ty: Sect ion m e m b e r s received live demonstrat ions of forge welding and the making of Damas- cus steel. Sect ion m e m b e r s Hans Peot and Ed Rhoades provided live demons t r a t ions for forging chain links and the making of Demascus (al loyed) steel. Members were shown samples of forged crafts.

Holston Vallt 5, ,~etlioll members pose.fin" a p/)olograplJ a / t /w i t Not,ember nleeling.

plan the year 's remain ing events Section to help him in his trials for and activities, the World Skills Competi t ion.

• TRIANGLE DECEMBER 27 Act iv i ty: The Sect ion had AWS Night Out at the Raleigh Sports Arena to see the Carolina Hurri- canes play the New York Rangers.

D I S T R I C T 5 D i r e c t o r : B o r i s A. B e r n s t e i n

P h o n e : ( 7 8 7 ) 8 8 3 - 8 3 8 3

• FLORIDA WEST COAST NOVEMBER 8

Speaker: C u r t W i l s o n c r o f t , specialist. Af f i l ia t ion: Tweco Arcair, Lan- caster, Ohio. Topic:Arc gouging. A c t i v i t y : J a m e s F a s t i n g was presented with the District Educator of the Year Award. Welding student D i e n T r a n accepted the second of five sponsorsh ip checks from the

• SOUTH CAROLINA NOVEMBER 16 Act iv i ty: Sect ion m e m b e r s and guests enjoy a social mee t ing featuring a frogmore stew dinner prepared by O d e l H a s e l d e n and J o n Guer ry .

D I S T R I C T 6 D i r e c t o r : G e r a l d R. C r a w m e r

P h o n e : ( 5 1 8 ) 3 8 5 - 0 5 7 0

D I S T R I C T 7 Director : Robe r t J . Tabe rn ik

Phone : (614) 4 8 8 - 7 9 1 3

• DAYTON NOVEMBER 14 Speaker: Steve Roth , president. Af f i l ia t ion: Southern Ohio Forge and Anvil (SOFA).

D I S T R I C T 8 D i r e c t o r : H a r r e l l E. B e n n e t t

P h o n e : ( 4 2 3 ) 4 7 8 - 3 6 2 4

• HOLSTON VALLEY NOVEMBER 14 Ac t i v i t y :A planning mee t ing was held to discuss positive ways to increase in teres t and a t t endance at Section meetings.

• NORTHEAST MISSISSIPPI DECEMBER 8 A c t i v i t y : T h e Sect ion held its An- nual Ladies' Night and Holiday Party at Ruben 's Catfish House in Columbus, Miss. Enter tainment for the event was provided by ventril- oquist M i c h a e l G r a y and his side- kick, Scotty.

D I S T R I C T 9 D i r e c t o r : J o h n B r u s k o t t e r

P h o n e : ( 5 0 4 ) 3 6 7 - 0 6 0 3

• MOBILE NOVEMBER 16 Speaker: D i a n e I rby. Affi l iat ion:Irby Specialty Services.


Florida West Coast District Educator of the Year Award winner James Fasting, left, with Section Chairman Darryl Jar- dine.

Attending the New OHeans 'Sections November meeting are, f rom lelt, First Vice Chairman John Pajak, Greg St. Cyr and his son, David, guest speaker Bill St. Cyr, Chairman Marie Lygate and Membership Chairman Shelton Ritter

Northwestern Pennsylvania Sec- tion Chairman Isreal Shabtai thanking guest speakerJeff Kehs for his presentation.

Topic: New industry in the Mobile area, Chamber of Commerce agen- das and plans for indus t ry in the future. Act iv i ty:This was a joint mee t ing with ASME.

• NEW ORLEANS NOVEMBER 21 Speaker: Bil l St. Cyr, branch chief, NASA. Aff i l ia t ion: John Stennis Space Center. Topic: Rocket engine test activities at the John Stennis Space Center. Activi ty: J o h n P a j a k was the 50/50 raffle w i n n e r for the evening.

Cleveland Section Chairman Bob Farasey, center, presenting a speaker's gift to Richard Avery, left, while Section member Bob Sott looks on.

D I S T R I C T I 0 D i r e c t o r : V i c t o r Y. M a t t h e w s

Phone: ( 2 1 6 ) 3 8 3 - 2 6 3 8

• NORaltWF~TERN PENNSYLVANIA OCTOBER 10 Speaker: J e f f Kehs . Affiliation: Hypertherm. Topic: Simple solutions to complex problems in plasma arc cutting.

• CLEVELAND OCTOBER 17 Speaker: R i c h a r d E. A v e r y , consultant. Aff i l ia t ion: Nickel D e v e l o p m e n t Institute. Topic: Fabricat ing high-nickel alloys for corrosive environments .

District 10 Director Vic Matthews, right, with Mahoning Valley Section First Vice Chairman Chuck Moore after presenting him with both Dis- trict and Section Meritorious Awards.

• MAHONING VALLEY NOVEMBER 16 Speakers: R i c h a r d Kra l , p roduc- t ion manager, and B r u c e S i k o r a , sales engineer. Aff i l ia t ion: The Holland, Co., Chicago, Ill. Topic: Electr ic-f lash crane rail welding. Activity: Section Chairman K e n n y J o n e s was presented with the Dis- t r ict Meri tor ious Award, First Vice Chairman C h u c k M o o r e received Dist r ic t and Sect ion Mer i to r ious Awards. Dis t r ic t 10 Di rec to r Vic M a t t h e w s presented the awards.

D I S T R I C T I I D i r e c t o r : S c o t t C. C h a p p l e

P h o n e : ( 9 1 3 ) 2 4 1 - 7 2 4 2

64 I FEBRUARY 2001

Northern Phtins Section memberpose fi." a photograpl~ during their November maintenance meeting.

Indiana Section members e,lflo,ing their annual holidayparOz

Aff i l iat ion: MG Systems. Topic: A t e c h n i c a l c o m p a r i s o n o f t h e f e a t u r e s a n d b e n e f i t s o f oxy- fue l , p l a s m a arc a n d l a s e r t h e r m a l c u t t i n g t e c h n o l o g i e s .

Lexington Section Chairman Fmmk McKinley, left, presenting Educator o f the Year Award to Tim Pinson, an instructor at Harrison Vo Tech.

D I S T R I C T 1 2 D i r e c t o r : M i c h a e l D . K e r s e y

P h o n e : ( 2 6 2 ) 6 5 0 - 9 3 6 4

• UPPER PENINSULA OCTOBER 1 7 - 2 0 Act i v i t y : T h e S e c t i o n t o u r e d t h e G i d d i n g s & Lewis F o u n d r y in M e n o m i n e e , Mich . T h e t o u r in- c l u d e d m a n u a l a n d a u t o m a t e d s a n d m o l d m a k i n g , p o u r i n g o f d u c t i l e a n d g rey i ron , s h a k e d o w n a n d met - a l lu rg ica l t e s t ing .

OCTOBER 10 Act i v i t y : A t o u r o f t h e M a r i n e t t e M a r i n e Corp . fac i l i ty in M a r i n e t t e , Wis . , w a s c o n d u c t e d f o r t h e Sec- t i o n . T h e focus of t h e t o u r w as t he c u r r e n t f a b r i c a t i o n o f U.S. C o a s t G u a r d sea -go ing b u o y t e n d e r s .

• F O X VALLEY NOVEMBER 9 Speaker: B o b C h r i s t i a n s e n , sa les r e p r e s e n t a t i v e .

D I S T R I C T 1 3 D i r e c t o r : J . L . H u n t e r

( 3 0 9 ) 8 8 8 - 8 9 5 6

• C H I C A G O SEPTEMBER 30 Act iv i ty :The Sec t i on h a d an e x o t i c a n i m a l sa fa r i a d v e n t u r e at t h e B r o o k f i e l d Z o o . T h e s p e c i a l a f t e r - h o u r s e v e n t i n c l u d e d a d o l p h i n p r e s e n t a t i o n , an e x o t i c a n i m a l t o u r by m o t o r safari , a r e c e p t i o n in t h e H a b i t a t Af r ica E x h i b i t a n d a con t i - n e n t a l b u f f e t d i n n e r in t h e Z o o ' s r e s t a u r a n t at t h e Living Coast .

DECEMBER 12 Speaker: T r a c y H o w a r d , o w n e r a n d ope ra to r . Affi l iat ion: Mihal is Mar ine , Inc. Topic: H o w a r d p e r f o r m e d u n d e r - w a t e r w e l d i n g d e m o n s t r a t i o n s for t h e S e c t i o n . T h e m e e t i n g w a s h o s t e d b y P r o f e s s o r J i m G r e e r of Mor a i ne Valley C o m m u n i t y Col lege at t h e Mor a ine We ld ing Lab.

D I S T R I C T 14 D i r e c t o r : Hi l B a x

P h o n e : ( 3 1 4 ) 6 4 4 - 3 5 0 0 , ext . 1 0 5

• LEXINGTON NOVEMBER 16 Speaker: F r a n k M c K i n l e y , AWS

L e x i n g t o n Sec t i on c h a i r m a n . Aff i l iat ion: KY Serv ice Co. Topic: Hardfac ing . Act i v i t y : M c K i n l e y p r e s e n t e d a w a r d s to m e m b e r s . T h e CWI o f t h e Year A w a r d w a s p r e s e n t e d to B i l l y W i l s o n , an i n s t r u c t o r at Ken- t u c k y T e c h at S o m e r s e t . T i m P i n - s o n , an i n s t r u c t o r at H a r r i s o n Vo Tech, r e c e i v e d t h e E d u c a t o r of t h e Year Award.

• INDIANA DECEMBER 12 Act i v i t y : T h e S e c t i o n h e l d i t s an- nua l h o l i d a y p a r t y at t h e B e e f a n d Boards D i n n e r T h e a t r e .

D I S T R I C T 1 5 D i r e c t o r : J . D . H e i k k i n e n

P h o n e : ( 2 1 8 ) 7 4 1 - 9 6 9 3

• NORTHERN PLAINS NOVEMBER 30 Speakers: R o r y K n u d s o n a n d Matt Mischke . Affi l iat ion: Praxair , Fargo, N.D. Topic: G e n e r a l d i s c u s s i o n o n main- t e n a n c e of w e l d i n g p o w e r sou rce s , f e e d e r s a n d e n g i n e - d r i v e n w e l d i n g m a c h i n e s . Act i v i t y : S e c t i o n S e c r e t a r y / T r e a - s u r e r Lee L a r s o n p r e s e n t e d M i k e L i p i n of S t a n d a r d I n d i a n a t h e Sec- t i o n ' s S p o n s o r s h i p Awards . Sec t ion C h a i r m a n D a v e L y n n e s m e t w i t h t h e n o n m e m b e r s a t t e n d i n g t h e m e e t i n g a n d d i s c u s s e d t h e b e n e - fits of AWS m e m b e r s h i p .

• ARROWHEAD NOVEMBER 16 Speaker: R a n d y K a r p i k , o w n e r .

WELDING JOURNAL I 6T

Central Arkansas CDairman De,t- nis Pickering, left, presenting David Fulbright with 100 A WS dollars for winning the drawing.

Affiliation: Fast Inc., Eveleth, Minn. Topic: Theo ry , o p e r a t i o n a n d man- u f a c t u r e o f s n o w m o b i l e s a n d s n o w m o b i l e s u s p e n s i o n s . Activity:The Sec t ion t o u r e d t he as- s e m b l y p l a n t of Fast Inc . , t h e mak- e rs of t h e "Blade" s n o w m o b i l e .

D I S T R I C T 16 Direc tor : C. F. B u r g

P h o n e : ( 5 1 5 ) 2 9 4 - 5 4 2 8

• SOUTHEAST NEBRASKA OCTOBER 17 Speaker: E r v W o o d a r d . Affiliation: DBI, Inc. Topic: N o n d e s t r u c t i v e e x a m i n a - t ion . Activi ty: T h e S e c t i o n t o u r e d t h e L i n c o l n Stee l C o m p a n y p l a n t . Lin- c o l n Stee l is a s t r u c t u r a l s t e e l fab- r i c a t i o n s h o p .

NOVEMBER 21 Act iv i ty : E x m a r k Mfg. Co. h e l d a t o u r for S e c t i o n M e m b e r s . E x m a r k is a m a n u f a c t u r e r o f c o m m e r c i a l w a l k b e h i n d a n d r i d i n g l a w n m o w e r s .

• MID-PLAINS NOVEMBER 16 Speaker: H e l i o C o u t o . Affiliation: A s p e n Dairy, Miller, Ne- braska . Activi ty: T h e S e c t i o n t o u r e d t h e A s p e n Dairy, w h i c h is a 4 5 0 0 - a n i - m a l h e r d d a i r y o p e r a t i o n . A l l ani- ma l s are i n s i d e a n d 3500 c o w s are m i l k e d t h r e e t i m e s a d a y . A v e r a g e m i l k p r o d u c t i o n p e r c o w is 80 lb p e r day. Ca lv ing is an e v e r y d a y oc- c u r r e n c e at t h e dai ry . T h e r e a re 1500 c o w s t ha t are p r e g n a n t at any g i v e n t i m e . O n a v e r a g e , 25 c a l v e s are b o r n e a c h day.

Central Arkansas Section members at the November meeting hosted by the Sheet Metal Workers Local Union #36L. Gary Jones, f a r left, is business manager for the Union, and Doug Smith, second f rom right, is an apprentice. Sec- tion Chairman Dennis Pickering is at far right.

Arrowhead Section members at the Fast Inc. assembly plant in November

D I S T R I C T 1 7 D i r e c t o r : O r e n P. R e i c h P h o n e : ( 2 5 4 ) 8 6 7 - 2 2 0 3

• CENTRAL ARKANSAS SEPTEMBER 20 Speaker: D e n n i s P i c k e r i n g , A W S C e n t r a l A r k a n s a s S e c t i o n c h a i r - man . Aff i l ia t ion: Hot S p r i n g s R e h a b Center . Topic: S h i e l d e d m e t a l arc w e l d i n g . Act iv i t y :The m e e t i n g w a s h o s t e d b y t h e S h e e t Me ta l W o r k e r s Loca l U n i o n #36L at i ts a p p r e n t i c e t ra ining schoo l .

D I S T R I C T 18 D i r e c t o r : J . M . A p p l e d o r n P h o n e : ( 2 8 1 ) 8 4 7 - 9 4 4 4

• HOUSTON NOVEMBER 15 Speaker: J o e H a l e , m e t a l l u r g y manager . Affiliation: S e r m a t e c h Gas Path. Topic: S u p e r a l l o y r e p a i r s o n gas- t u r b i n e b l a d e s a n d o t h e r c o m p o - n e n t s . Activity: G e o r g e K a m p s c h a e f e r was p r e s e n t e d w i t h t h e Dis t r i c t 18 D i r e c t o r ' s Award by Dis t r i c t 18 Di- r e c t o r J i m A p p l e d o r n .

68 I FEBRUARY 2001

Houston Section guest speaker Joe Hale during his presentation to the members.

ilil

Saudi Arabia Section First Vice Chairman A. N.Al-Awwami presenting a speaker's p laque to guest speaker Ted Valentini.

DISTRICT 19 D i r e c t o r : P h i l Z a m m i t

Phone : (509) 4 6 8 - 2 3 1 0 ext. 1 2 0

• S P O K A N E OCTOBER 11 Speaker: G e n e M o n a c o . Aff i l ia t ion: Monaco Enterpr ises Racing. Topic: NASCAR operat ion and race car fabrication safety specs on roll cages. Activity: District 19 Director P h i l Z a m m i t a t tended the meeting.

DISTRICT 20 D i r e c t o r : N e i l R. K i r s c h

P h o n e : ( 9 7 0 ) 8 4 2 - 5 6 9 5

District 21 D/rector Bob Sc/,teideJ: secoml f rom ItJ?, and his wife, Evelyn, center, enjoying the San Diego Section's November meeting.

DISTRICT 21 D i r e c t o r : F. R. S c h n e i d e r P h o n e : ( 6 1 9 ) 6 9 3 - 1 6 5 7

• SAN D I E G O NOVEMBER 8 Activity:The Section toured the Hi- Tech Welding Services plant. Hi- Tech President Wya t t S w a i m gave an o v e r v i e w of the h i s tory of Hi- Tech Welding and shared his knowledge of e lectron beam welding. General Manager J o h n Mort- s e e s exp la ined h o w to weld tita- n ium and t i tan ium metallurgy. S jon D e l m o r e , director of marketing, shared Hi-Tech's products with members . District 21 Director Bob S c h n e i d e r and his wife, E v e l y n , at tended the meeting.

DISTRICT 22 D i r e c t o r : M a r k B e l l

P h o n e : ( 2 0 9 ) 3 6 7 - 1 3 9 8

I N T E R N A T I O N A L

S E C T I O N

• S A U D I A R A B I A OCTOBER 11 Speakers: K h a l e d M. All, Sect ion

chairman, and Ted Valen t in i , marketing manager. Af f i l ia t ion:AWS and ITW Group, respectively. Topic: O v e r c o m i n g issues wi th welding high strength pipes. •

• A n n o u n c e Y o u r Sec t ion ' s Activi t ies

Stimulate attendance at your Section's meetings and training programs with free listings in the Section Meeting Calendar column of Society News.

Useful information includes your Section name; activity date, time and location; speaker's name, title, affiliation and subject; and notices of golf outings, seminars, contests and other special Sec- tion activities.

If some of your meeting plans are sketchy, send the name and phone number of a person to contact for more information.

Send your new calendar to Susan Campbell,Associate Editor, Welding Journal Dept.,AWS, 550 N.W. LeJeune Rd., Miami, FL 33126; FAX: (305) 443-7404. •


S E C T I O N E V E N T S C A L E N D A R

• N E W JERSEY FEBRUARY 20 Thermal Dynamics. Topic: Simple automation for plasma arc cut t ing machines.

• MILWAUKEE FEBRUARY 15 Topic: Welding and jo in ing failure analysis.

MARCH 15 Topic: Latest Advancements in Stud Welding and Scholarship Night.

APRIL 19 Activity: ABB Flexible Automat ion plant tour.

MAY 17 Activity: Past Spouse's Night.

Cha i rmen ' s and

• LAKESHORE FEBRUARY 8 Activity: Maritime Museum tour and Spouse's Night.

MARCH 14 Activity: Student Day Event.

APRIL 12 Activity: MG Industr ies plant tour.

MAY 18 Activity: District Conference.

MAY 3 Speaker: C h a r l e s C o l b u r n , sculp- tor. Topic: Welded Art. Activity: Students ' Night.

• ALASKA For further information on meetings, e-mail [email protected].

FEBRUARY 16 Topic:To be announced. Location: Anchorage.

MARCH 16 Topic:To be announced . Location: Fairbanks.

APRIL 20 Topic:To be announced . Location." Anchorage.

MAY 19 Activity:AWS Alaska Section Picnic. Location: Palmer, Alaska.

• C O L O R A D O For meet ing updates, call the

Colorado Section's update line at (303) 313-9645. Visit the Section's Web site at www.awsO39.tripod.com

MARCH 8 Speaker: T e r r y McCle l l and . Topic: How to write a WPA.

APRIL 12 Speaker: C h u c k H o w a r d . Topic: How to write a PQR.

MAY 10 Speaker: J a c k H a r k n e s s . Topic: How to write a WQTR. Activity: Student Recogni t ion and Award Night.

JUNE 14 Activity: Executive Board Meeting.

AUGUST 9 Activity: Executive Board Meeting.

• Student Chapters, Send UsYour News

Student Chapters are encour - aged to send reports of their meetings, act ivi t ies a nd even ts , a long wi th photographs , for pub l i ca t ion in the Welding Journal ' s Studen t Activities depar tment .

Send y o u r m e e t i n g / e v e n t repor ts to Susan Campbell ,Assoc. Ed- itor, We ld ing Journa l , 550 N.W. LeJeune Rd., Miami, FL 33126.

Repor t s can also be faxed to (305) 443-4704 or e-mai led to campbell@aws, org. •

• YORK-CENTRAL PENNSYLVANIA

FEBRUARY 1 Speaker: J e r r y M a t h i s o n . Affiliation: ESAB. Activity: Past Chairmen's Night.

MARCH Activity: Ladies' Night and evening on the d inne r t r a in . Date:To be announced .

a n

APRIL 5 Activity: Joint meet ing with ASNT. Speaker:William DeFel ice . Topic: Cryogenics.

S T U D E N T A C T I V I T I E S

D I S T R I C T 3 D i r e c t o r : C l a u d i a B o t t e n f i e l d

P h o n e : ( 7 1 7 ) 3 9 7 - 1 3 1 2

Student Chapter members Rody Schaffer, left, and Ryan Bohn examining fabr icat ion details at Alstom Power Inc. in Easton, Pa.

• LEHIGH CAREER AND TECHNICAL SCHOOL NOVEMBER 7 Activity: The Student Chapter toured the Alstom Power Inc. plant in Easton, Pa. •

70 I FEBRUARY 2001

• 2 0 0 0 - 2 0 0 1 M e m b e r - G e t - A - M e m b e r Campaign L i s t e d b e l o u , a r e t h e p e o p h ' p a r t i c i p a t i n g i n t h e 2 0 0 0 - 2 0 0 1 M e m b e r - G e t - A - M e m b e r C a m p a i g n . F o r c a m p a i g n r u l e s

a n d a p r . i z e list, p l e a s e s e e p a g e 6 5 o f t h i s Welding Journal. I f y o n h a v e a n l ' q u e s t i o n s r e g a r d i n g y o u r m e m b e r , p r o p o s e r p o i n t s , p l e a s e c a l l t h e M e m b e r s h i p D e p a r t m e n t a t

( 8 0 0 ) 4 4 3 - 9 3 5 3 ext . 4 8 0 .

W i n n e r ' s C i r c l e ( A W S M e m b e r s s p o n s o r i t t g 2 0 or m o r e

l ieu ' D ld i l , i d t t a l M e m b e r s , p e r .l'ear,

siHce ]tHle I, 1999)

J. Con]pton, S a n E£,lTlando Vallcy*

E. H. Ezell, M o b i l e *

B.A. Mikeska, H o u s t o n *

J. Merzthal, P e r u *

W+ L. Shreve, l :ox Val ley*

R. Wray, N e b r a s k a *

G. Woomer, J o h n s t o t t ' n / A l t o o n a *

* D e n o t e s t h e n u m b e r o f t i m e s a n

I n d i v i d u a l M e n t b e r h a s a c h i e v e d

W i n n e r ' s C D ' c l e s t a t u s . S t a t u s w i l l

b e a w a r d e d a t t h e c l o s e o f e a c h

m e m b e t v ~ h i p c a m l ) a ~ g n y e a r .

P r e s i d e n t ' s G u i l d (AWS M e m b e r s s p o n s o r i n g 2 0 or m o r e

IICll' Dtdll'ldlla131tqlll)~'rs I)Clll'CCII ]lllIC

I, 2000 , arid M~(I, 31, 2 0 0 1 . )

.1. Conapton,San E e r . n a n d o V a l l e y - 45

J. Merzthal, P e r u - - 21

( ;. W o o m e t , . l o h n s t o w n / A l t o o n a - - 20

P r e s i d e n t ' s R o u n d t a b l e ( A W S M e m b e r s spoHsorDtg 1 1 - 1 9 Jtew

1Hdiv id l la l M e m b e r s be t t t , e e n J u n e 1,

2000 , a t t d Mgoe 3 1 , 2 0 0 1 . )

P. Baldwin, P e o r i a - - l 5

G.Taylor, P a s c a g o u l a - - 14 A.A.AI-Abdulffabb;tr, S a t u l i A r a b i a - 13 A. O. Smith III, T a l s a - - 1 3

E. H. Ezell, M o b i l e - - 12

L.J. Smith, H o t t s t o n - - 1 2

P r e s i d e n t ' s C l u b (AI~\S" m e m b e r s spo~tsorDlg 6 - 1 0 n e w

l t t d i t ' i d u a l M e m b e r s b e t w e e n J u n e 1,

2 0 0 0 , al ld Mal ' 3 l, 2 0 0 I.)

W. R. Beck, R o c h e s t e r - - 9

C.Alonzo,Jr. , S a n A n t o n i o - - 7

R. Buse, M o b i l e - - 6

P r e s i d e n t ' s H o n o r R o l l (AWS m e m b e r s spo~tsorDlg 1 -5 Jtew In-

d i v i d l t a l M e m b e r s b e t w e e n J u n e I,

2 0 0 0 , a n d M a y 31, 2 0 0 1 . Ot t ly t h o s e

s p o n s o r i n g 2 o r m o r e A WS I n d i v i d u a l

B lembe tw are l isted.)

J.T. Blank, N o r t h e r n M i c h i g a n - - 5

C. M. Murray, C l e v e l a n d - - 5

(;. E Neal, F o r t S m i t h - - 5

l).J. Nelson, P u g e t S o u n d - - 5

R. L. Peaslee, D e t r o i t B & S - - 5

W. L. Shrcve, E o x V a l l e y - - 5

C.-l,.Tsai, ~ H w a n - - 5

H. E. (;able, Sr., P i t t s b u t ~ g h - - 4

J. C. Cooley, B i r m i n g h a m - - 4

W ( ~,dver~;Jr., Ix ntg l ~ ' h . / O m n g e C~t 0, - - 4 I). L. Hatfiekl, 7~tlsa - - 4

J. 1). Sanders, H o u s t o n - - 4

L. Schweinegruber , P i t t s b u r g h - - 4

.1. H. Smith, Jr., M o b i l e - - ,l M. R.Tyron, U t a h - - 4

J. N. Carney, W e s t e r n M i c h i g a n - - 3

R. Grays, h~,rn - - 3 C. R. Hein, C e n t r a l A r k a n s a s - - 3

S. I). Keskar, I n d i a - - 3

J. Koster, W e s t e r n M i c h i g a n - - 3

B. L Marini, D e t r o i t - - 3

J.A. Rosado, P u g e t S o u n d - - 3

R. D. Rux, ~ l , o m i n g - - 3 M.A. Sandvig, N o r t h w e s t - - 3

B. Saraswat, I n d i a - - 3

M.Tait, L . A . / I n l a n d E m p i r e - - 3

P. G.Walker, O z a r k - - 3

R.Wright, S o u t h e r n C o l o r a d o - - 3

J. E. Campbell , M i l w a u k e e - - 2

D. S. l)odds, P i t t s b u r g h - - 2

q:A. Flynn, A t l a n t a - - 2

M. Gartman, N o r t h e a s t Mi s s i s s ipp i - - 2

R. Ghamsari, C a n a d a - - 2

S. E Hoff, S a n g a m o n Va l l t 9 , - - 2

J. W. Jaeger, S o u t h e r . n C o l o r a d o - - 2

R. S.Judy, P o r t l a n d - - 2

.1. Knapp, T a l s a - - 2

M.A. Latif, H o u s t o n - - 2

J. R. Leavitt, S o u t h w e s t I d a h o - - 2

J.A. Livesay, ?v2tshv i l le - - 2

D. G. Luna, L . A . / h l l a n d E m p i r e - - 2

S. M. McCasland, 3 ) , r a c u s e - - 2

H.V. McRae, N e w Y o r k - - 2

M. E Mott, F l o r i d a W e s t C o a s t - - 2

C. N. Porto, C l e v e l a n d - - 2

S. M. Qureshi, I n t e r n a t i o n a l - - 2

A. Reyna, N o r t h 7~xas - - 2 K. L. Rigsby, N e w Y o r k - - 2

H.A. Rodriguez, P u e r t o R i c o - - 2

Vd S h i e l d s , N o r t h e a s t M i s s i s s i p p i - - 2

E Soto, N e w . l e r s e l , - - 2

J. Stewart, S a n g a m o n V a l l £ v - - 2

G. S.Tcague, E a s t e r n C a r o l i n a s - - 2

J.Thompson, G r e a t e r H u n t s t , i l l e - - 2

M. G.Weeks, S a b i n e - - 2

R. B.Wiser, R i c h m o n d - - 2

D.A.Wright, K a n s a s O t y - - 2

R. Zabel, S o u t h e a s t N e b r a s k a - - 2

S t u d e n t S p o n s o r s ( A W S m e m b e r s s p o n s o r i n g 3 or m o r e

n e w A W S S l u d e t l l M e m b e r s b e t w e e n

J u n e I, 2 0 0 0 a n d Me O, 3 l. 2 0 0 1 . )

T. M. B u c h a n a n , M i d - O h i o V a l l e y - - 29 PJ. Betts, M o b i l e - - 24 T. C. Murrow, A r i z o n a - - 22 J. Jones, N o r t h T e x a s - - 21

D. Scrrano, P u e r t o R i c o - - 21

J.J. D:mghcrty, Lot t i s t , i l l e - - 20 G . W o o n m r J o h n s t o w n / A l t o o n a - - 20 M. R. Anderson, I n d i a n a - - 18 R.J. l)ePue, O l e a n - B r a d f i ~ r d - - 18

K. R. Moore, C o r p u s C h r i s t i - - 18

H.Jackson, L . A . / l n l a n d E m p D z , - - 16 K.A. Ellis, M a o e l a n d - - 1 5

K.A. Dietrich, W h e e l i n g - - 1 4

S. P. Siviski, M a i n e - - 14 R. Zabel, S o u t h e a s t N e b r a s k a - - 14

J. H. Smith,Jr., M o b i l e - - 13 T. Strickland, A r i z o n a - - 13

H. R. Madron, M a r v l a n d - - 12

E G. Childcrs, O k l a h o m a C i t y - - 10 D. L. [t,'ltficld, T u l s a - - 10 L.J. Heath, M a r F l a n d - - 10 W. H. Kielhorn, E a s t T e x a s - - 9

A. K. Mattox, L e x i n g t o n - - 9

C.Alonzo,.lr., S a n A n t o n i o - - 8

S. D. Gore, C h a r l o t t e - - 8

H.W. Pelster, S E N e b r a s k a - - 7

M. E.qait, L . A . / l n l a n d E m p i r e - - 7

J .T Blank, N o r t h e r n M i c h i g a n - - 6

W.Ccabeoklr.,lz)*~ B e a c b / O m n g e (,'*tO: - - 6

R. Schneider, W y o m i n g - - 6

J.J. Swoyer, L e h i g h V a l l e y - - 6

P. Baldwin, P e o r i a - - 5

J. N. Carney, W e s t e r n M i c h i g a n - - 5

A. E. Classens, C h a r l o t t e - - 5

E. L. Harris, P a s c a g o u l a - - 5

D.J. Nelson, P u g e t S o u n d - - 5

J. Ptmlmer, L o n g B o b . / O r a n g e CnW. - - 5

T. Shirk, T i d e w a t e r - - 5

R G.Walker, O z a r k - - 5

S. R. Zwilling, L o u i s v i l l e - - 5

M.J. Bannester, M o b i l e - - 4

J. R. Carter, Sr., C a r o l i n a - - 4

R. S. Judy, P o r t l a n d - - 4

C.J. Ray, I n d i a n a - - 4

K. L. Rigsby, N e w Y o r k - - 4

J. D. Sanders, H o u s t o n - - 4

T. R.Alberts, S W V i r g i n i a - - 3

G. C',dlender, S a n F e r n a n d o Vall O, - - 3

R. Grays, K e r n - - 3

T. E McClelland, C o l o r a d o - - 3

P. O'Leary, E a s t e r n I d a h o / M o n t a n a - - 3

R. D. Rux, W y o m i n g - - 3

K. E. Samuclson, A l b u q u e r q u e - - 3

E.J.Warren, C o l o r a d o - - 3

C. B.Wesley, N o r t h w e s t e r n Pa. - - 3 ¢

WELDING JOURNAL J 71

S T A N D A R D N O T I C E S

Standards for Public Review

AWS w a s a p p r o v e d as a n a c c r e d - i t e d s t a n d a r d s - p r e p a r i n g o r g a n i z a - t i o n b y t h e A m e r i c a n N a t i o n a l Stan- d a r d s I n s t i t u t e ( A N S I ) in 1 9 7 9 . AWS r u l e s , as a p p r o v e d by ANSI, r e q u i r e al l s t a n d a r d s be o p e n to p u b l i c rev iew f o r c o s n m e n t d u r i n g t h e a p p r o v a l p r o c e s s . T h i s c o l u m n a l s o a d v i s e s o f ANSI a p p r o v a l o f d o c u m e n t s . T h e fol- l o w i n g s t a n d a r d s a r e s u b m i t t e d f o r p u b l i c r e v i e w . A c o p y m a y b e ob - t a i n e d b y s e n d i n g t h e a m o u n t s h o w n to AWS T e c h n i c a l Dept . , 550 N.W. LeJe- u n e Rd. , M i a m i , FL 3 3 1 2 6 , o r b y ca l l - i n g ( 3 0 5 ) 4 4 3 - 9 3 5 3 , ext. 451.

A4.4M:200X, S t a n d a r d P r o c e d u r e s f o r D e t e r m i n a t i o n o f Moi s tu re Con- t e n t o f Weld ing F luxes a n d Weld ing Electrode F lux Coverings. New standard. $10. [ANSI Publ ic R e v i e w ex- pires February 27, 2001 .]

A5.21:200X, S p e c i f i c a t i o n f o r Bare E lec t rodes a n d Rods f o r Sur fac ing . Rev i sed s tandard . $14. [ANSI Publ ic Review expi res February 27, 2001 .]

ISO Draft Standards for Public Review

C o p i e s o f t h e f o l l o w i n g Draf t In- t e r n a t i o n a l S t a n d a r d s a r e a v a i l a b l e f o r r e v i e w a n d c o m m e n t t h r o u g h y o u r n a t i o n a l s t a n d a r d s b o d y , w h i c h in t h e U n i t e d S t a t e s i s ANSI, 11 W e s t 4 2 n d S t r e e t , N e w Y o r k , NY 1 0 0 3 6 ; t e l e p h o n e ( 2 1 2 ) 6 4 2 - 4 9 0 0 . A n y c o m - m e n t s r e g a r d i n g ISO d o c u m e n t s s h o u l d be s e n t to y o u r n a t i o n a l s tan- d a r d s b o d y .

In t h e U n i t e d S t a t e s , i f y o u w i s h to p a r t i c i p a t e in t h e d e v e l o p m e n t o f I n t e r n a t i o n a l S t a n d a r d s for w e l d i n g , c o n t a c t A n d r e w D a v i s at AWS, 5 5 0 N.W. L e J e u n e Rd. , M i a m i , FL 3 3 1 2 6 ; t e l e p h o n e ( 3 0 5 ) 4 4 3 - 9 3 5 3 ex t . 4 6 6 , e- mai l : a d a v i s @ a w s . o r g . O t h e r w i s e c o n - tact y o u r n a t i o n a l s t a n d a r d s b o d y .

ISO/DIS 9606-1, A p p r o v a l Test ing o f Welders - - Fusion Welding - - Part 1: Steels.

ISO/DIS 14327, R e s i s t a n c e We ld ing

- - P r o c e d u r e s f o r D e t e r m i n i n g the Weldabi l i ty Lobe f o r Res is tance Spot, Projec t ion a t td Seam Welding.

ISO/DIS 15614-2, 5J~ecification a n d A p p r o v a l o f Welding Procedures f o r Metal l ic Mater ia l s - - Welding Proce- d u r e Test - - Par t 2 : A r c We ld ing o f A l u m i n i u m a n d Its Allqvs.

ISO/DIS 15614-5, S p ec i f i ca t i o n a n d A p p r o v a l o f Weld ing Procedures Jbr Metal l ic Mater ia l s - - Welding Proce- dure Test - - Part 5:Arc Welding o f Ti- t a n i u m , Z i r c o n i u m a n d TheirAlloys.

ISO/DIS 17642-1, Destruct ive Tests on Welds in Meta l l i c M a t e r i a l s - - Cold Cracking Tests f o r Weldments - - Part 1." General.

ISO/I)IS 17642-2, Destruc t ive Tests on Welds in Meta l l i c M a t e r i a l s - - (,'old Cracking Tests f i , r We ldmen t s - - Part 2: S e l f Res t ra in t Tests.

ISO/DIS 17642-3, Destruc t ive Tests on Welds in Meta l l i c M a t e r i a l s - - Cold Cracking Tests f o r We ldmen t s - - Par t 3: Ex terna l l y Loaded Tests.

ISO/DIS 17652-1, Welding - - Test f o r Shop Pr imer s in Re la t ion to Welding a n d A l l i ed Processes - - Par t 1: Gen- eral Requ i remen t s .

ISO/DIS 17652-2, Welding - - Test f o r Shop Pr imer s in Re la t ion to Welding a n d Al l i ed Processes - - Par t 2: Weld- ing Propert ies o f Shop Pr imers .

ISO/DIS 17652-3, Welding - - Test f o r Shop Pr imer s in Re la t ion to Welding a n d A l l i ed Processes - - Par t 3: Ther- m a l Cutting.

ISO/DIS 17652-3, Welding - - Test f o r Shop Pr imer s in Rela t ion to Welding a n d A l l i e d Processes - - Par t 4: Emis- s ion o f F u m e s a n d Gases.

Revised Standards Approved byANSl :

B2.1:2000, Spec i f i ca t ion ]or Welding

P r o c e d u r e a n d P e r f o r m a n c e Qual i - f i c a t i o n . Approwt l date: N o v e m b e r 14, 2000.

C5.3:2000, R e c o m m e n d e d Pract ices f o r A ir Carbon Arc Goug ing a n d Cut- t ing . A p p r o v a l date: N o v e m b e r 21, 2000.0

T E C H N I C A L C O M M I T T E E

M E E T I N G S

All AWS technical committee meetings are open to the public. Persons wishing to attend a meeting should con- tacl the staff secrela~:l~ ~f the committee as listed below at A WS, 550 N. Vd LeJeune Rd., Miami, FL 33 126; telephone (305) 443-9353.

February 6-7, 2001, G IB Subcommit - t ee on Vibra t ion Welding. Fort Laud- erdale , Fla. S tandards p r e p a r a t i o n meet ing. Staff Contact : J. L. (}:tyler.

February 7, 2001 ,A9B S u b c o m m i t t e e on the Exchange of Welding Informa- t ion. Orlando, Fla. Standards prepara- t ion mee t ing . Staff con tac t : C. B. Pol- lock.

February 7, 2001, D16 C o m m i t t e e on Robo t i c and Automat ic Welding. Or- land(), Fla. S tandards p r e p a r a t i o n meet ing. Staff contact:T. R. Potter.

March 1-2, 2001, C3 C o m m i t t e e on Brazing and Solder ing . 1)aytona, Fla. Standards p r e p a r a t i o n mee t ing . Staff contact : C. B. Pollock.

March 13, 2001, G1A S u b c o m m i t t e e on Hot Gas Weld ing and Ex t rus ion Welding . Hous ton , Tex. Standards p repa ra t ion mee t ing . Staff contac t : J. L. Gayler.

March 20 -21 ,2001 , B4 C o m m i t t e e on M e c h a n i c a l Tes t ing of Welds. Stan- dards p repara t ion meet ing . Staff contact: C. B. Pollock.

March 20-23, 2001, D1 Commi t t ee on S t ruc tu ra l We ld ing .Tampa , Fla. Stan- dards p repara t ion meet ing . Staff contact: H. H. Campbel l . •

72 J FEBRUARY 2001

G U I D E T O A W S S E R V I C E S 5 5 0 N . W . L c . l c u n c R d . , M i a m i , F L 3 3 1 2 6

P h o n e ( 8 0 0 ) 4 4 3 - 9 3 5 3 ; T e l e x 5 1 - 9 2 4 5 ; ( 8 8 8 ) W E L D I N G

F A X ( 3 0 5 ) 4 4 3 - 7 5 5 9 ; I n t e r n e t : t t , w w , a w s . o r g P h o n e e x t e n s i o n s a p p e a r i n p a r e n t h e s e s .

AWS PRESIDENT

L. William Myers , t82 Wolf Run Road

Cul)a, NY 1 4 7 2 7

ADMINISTRATION

Corpont te l ) i rector of Adnlinistl~ltive Services Jim Lankford ( 2 1 4 )

Coq)onl te l ) i rcctor of Marketing Technical Services Division

l )ebnth C.Weir ( 2 7 9 )

P r o m o t e s S o c i e t y p r o g r a n l s a n d a c t i v i t i e s t o AXVS I l l en l l ) e r s , t i l e w e l d i n g cOFIlnlu- n i t y a n d t i le g e n e r a l p u b l i c .

Executive l ) i rector Frank (;. l)eLaurier, ('AE ( 2 1 0 )

Deputy F.xecutive Directors Richard 1). French ( 2 1 8 ) Jeffi'ey R. l tufsey ( 2 6 4 )

.Iohn J. Mcl.aughlin ( 2 3 5 )

Assist;In( Executive Director l )cbbie A. Cadavid ( 2 2 2 )

I)irector of Quality Management Systems Lind: K. Williams ( 2 9 8 )

Corpora te l ) i rector of Finance/Comptrol ler Frank R.'farata ( 2 5 2 )

INFORMATION SERVICES

Corpora te Director Joe Cilli ( 258)

H U M A N RESOURCES

l ) i rcc tor I.uisa Hernandez ( 2 6 6 )

INTERNATIONAL INSTITUTE OF ~ ' E L D I N G

Inl2)rmation (294)

P r o v i d e s l i a i son a c t i v i t i e s i n v o l v i n g o t h e r p r o f e s s i o n a l s o c i e t i e s a n d s t a n d a r d s o r g a - n i z a t i o n s , f l a t iona l ly :llld i l l ternat iOl la l ly ,

GOVERNMENT LIAISON SERVICES

l lugh K Webster Webster. Chamberla in & Bean

Washington, I).C. (202) .166-2976

FAX (202) 835-0243

Ident if ies sou rce s o f fund ing J-kit" w e l d i n g ed- t lca t ion and r e s e a r c h & d e v e l o p n l e n t . Moni- to r s legis la t ive and r e g u l a t o r y issues hl lpor- (ant to the industry.

W E L D I N G EQUIPMENT MANUFACTURERS COMMITTEE

Associate F.xccutive Director Richard I..Alley (217)

INDUSTRY ACTION COMMITTEE

Associate Executive Director Charles R. Fassinger ( 2 9 7 )

COMMUNICATIONS

(k)rporate l)irector, Comlnuniea t ions Nannet tc M. Zapata (308)

CONVENTION & EXPOSITIONS I!xhibiting lnfi)rmation ( 2 2 1 , 2 5 6 )

Managing Director "Ibm L. l)avis (231)

National Sales Matlager ( ;ene Pesant (458)

O r g a n i z e s t i le w e e k - l o n g a n n u a l AWS In- t e r n a t i o n a l W e l d i n g a n d F a b r i c a t i n g F.x- p o s i t i o n a n d ( : o n v e n t i o n . R e g u l a t e s s p a c e a s s i g n n l e n t s , r e g i s t r a t i o n n l a t e r i - : I s a n d o t h e r E x p o a c t i v i t i e s .

PUBLICATION SERVICES l)ivision hlfi)rmation (348)

Managing Director Jeff Weber ( 2 4 6 )

WELDING JOURNAL

Publisllcr .Jeff Weber (246)

F, di tor Andrew Cullison (249)

National Sales 1)irector Rob Saltzstein (243)

WELDING HANDBOOK

Welding t t andbook Editor Annet te O'Brien (303)

P u b l i s h e s A W S ' s n l o n t l l l y n l a g a z i n e , t i le Weld ing . lo t t r t ta l , w h i c h p r o v i d e s itl/~)r- n i l ( tO l l 011 tilt" s t a t e o f t h e w e l d i t l g ill- d u s t r y , i ts t e c h n o l o g y a n d S o c i e t y ac t iv i - t i e s . P u b l i s h e s t h e W e l d i n g H a n d b o o k a n d b o o k s o n g e n e r a l w e l d i n g s u b j e c t s .

MEMBER SERVICES

I)epartnlent Inl()rnlation ( 2 6 1 )

Managing l ) i rcctor Cassie R. Burrell ( 2 5 3 )

l ) i rector Rhcnda A. Mayo (260)

Serves as a liaison b e t w e e n Sectioll nlelllbers andAWS headquar ters , ln lorms nlenfl)ers al)out AWS benefits and o ther activities of interest.

CERTIFICATION PROGRAMS/ BUSINESS DEVELOPMENT

Director of hlt'l Business Developnlent Walter Herfcnt (475)

For cus tomized ce r t i f i ca t ion and educa t i ona l p rograms to industry and governnlent .

EDUCATION

Director .James R. ( ' u n n i n g h a m ( 2 1 9 )

Inl()rnlat ion on edt lcat iot l p r o d u c t s , p r o j e c t s a n d p r o g r a n l s . CW1, SCWI a n d ()ti ler seminars des igned to t ass i s tance ill Cer t i f ica t ion . R e s p o n s i b l e for file S.E.N.S.E. b e g i n n i n g w e l d e r p r o g r a m a n d d i s s e m i n a t i o n o f educa t ion i n fo rma t ion on the w e n .

CONFERENCES

I)irector (,iselle 1, Rodriguez (278)

R e s p o n s i b l e fl)r n a t i o n a l a n d loca l c o n f e r - e n c e s / e x h i b i t i o n s and sen l inars OIl i n d u s t r y t o p i c s r a n g i n g f rom the b a s i c s to the leading edge of t echno logy .

CERTIFICATION OPERATIONS h l f o r n l a t i o n a n d a p p l i c a t i o n n la t e r i a l s Oil c e r t i f y i n g w e l d e r s , w e l d i n g i n s l l e c t o r s a n d e d u c a t o r s . ( 2 7 3 )

Managing l) i rector Wendy S. Reeve (215)

A w a r d s & F e l l o w s

Managillg l)irt_-ctor \Vendy S. Reeve ( 215)

(kx)rdii~ttcs awards and AWS Ftqlow nolllillt't>.

TELEWELD

FAX: (305) 443-5951

For i n f o r m a t i o n a b o u t AWS t e c h n i c a l publ i - c a t i o n s , c o n t a c t tile T e c h n i c a l Se rv ices per- sonne l listed below.

TECHNICAL SERVICES

l )epar tment Infiwnmtion ( 3 4 0 )

Managing Director l.comnxl P Connor ( 2 9 9 )

Qualification. hlspect ion, Food Processing Equipment

Andrew R. l)avis ( 4 6 6 ) hl tcrnat ional Standards Program Manager, W~qding in Marine

(:onst ruct ion

Stephen P. t tedrick ( 3 0 5 ) Safi:ty and I lealth Manager, Symlxds and Definitions

E n g i n e e r s

Hardy II. (;anlpbell IIl ( 3 0 0 ) Structural

Rakesll Gupta ( 3 0 1 ) Filler Metals

Christopher B. P(flkx'k (304) Bntzil~g,~ )Meting, qi_~ting, I~dln )ads, (k)nlputerization,

hlsll'Unlentation

Tim Potter (309) Robotics,Joining of Metals and Alloys, Piping and Tubing,

Friction Welding

J(dln L ( ;ayler (472) Metric IhT, tcXict% Shcx:t Met:d. Plastk,'s and ( k nlll~ ~itt.'s, l~ersonnel (.)u:difit~ld(m

Ed E Mitchell ( 2 5 4 ) T h e r m a l Spray, t l igh-En- e rgy Beam Welding and Cut t ing , Res i s tance

Welding, Aut onlot ive, A e r o s p a c e


P U B L I C A T I O N SALES

Call Global Engineering Documents (80O) 854-7179

Pub l i c a t i on o rde r s .

Senior Publications Coordinator

Rosalinda O'Neill (451)

AWS publishes more than 160 w)lumes of material, including standards that are used throughout the industry.

With regard to technical inquiries, oral opinions on AWS standards may be rendered. However, such opinions represent only the personal opinions of the particular individuals giving them.These individuals do not speak on behalf of AWS, nor do these oral opinions constitute official or unofficial opinions or interpretations of AWS. In addition, oral opinions are informal and should not be used as a substitute for an official interpretation.

I t is the i n t en t o f the A m e r i c a n Weld- ing Socie ty to b u i l d the Socie ty to the h ighes t q u a l i t y s t a n d a r d s poss ible . We we lcome a n y sug~gestions y o u m a y have.

Please contac t a n y o f the s t a f f l i s ted on the p r e v i o u s p a g e or AWS Pres iden t L. Wi l l iam Myers, 482 Wol f R u n Road, Cuba, N Y 14727.

A W S F O U N D A T I O N , I N C .

550 N.W. LeJeune Rd. Miami , FL 3 3 1 2 6 (305) 445-6628

(800) 443-9353 , ext . 293 O r e-mail: b o b w @ a w s . o r g

C h a i r m a n , Board o f T r u s t e e s Rona ld C. P ie rce

E x e c u t i v e D i r e c t o r Frank G. DeLaur ier , CAE

D i r e c t o r o f D e v e l o p m e n t R o b e r t B .Wi the re l l

T h e A W S F o u n d a t i o n is a n o t - f o r - p r o f i t c o r p o r a t i o n e s t a b - l i s h e d t o p r o v i d e s u p p o r t f o r e d u c a t i o n a l a n d s c i e n t i f i c e n d e a v o r s o f t h e A m e r i c a n W e l d i n g Soc ie ty . I n f o r m a t i o n o n g i f t - g i v i n g p r o g r a m s i s a v a i l a b l e u p o n r e q u e s t .

• Nominees for National Office Onl y S u s t a i n i n g M e m b e r s , M e m b e r s , H o n o r a r y M e m b e r s , Life M e m b e r s o r Re-

t i red M e m b e r s w h o have b e e n m e m b e r s for a pe r i od o f at least t h r ee years shall be eligible for e lec t ion as a Di rec tor o r Nat ional Officer.

It is the duty of the National Nomina t ing Commi t t ee to nomina t e candidates for national off ice.The commi t t ee shall hold an open meet ing, preferably at the Annual Meet- ing, at w h i c h m e m b e r s may appea r to p r e s e n t and d i scuss the eligibility o f all candidates.

To be cons idered a candidate for pos i t ions of President ,Vice Pres ident ,Treasurer or Director-at-Large, the following qualifications and condi t ions apply:

P res iden t :To be el igible to ho ld t h e off ice o f Pres iden t , an ind iv idua l m u s t hav e se rved as a Vice Pres iden t for at least o n e year.

Vice P re s iden t :To be el igible to ho ld t h e off ice o f Vice P res iden t , an ind iv idua l m u s t have s e rved at least o n e yea r as a Director , o t h e r t h a n Execu t ive Di rec to r an d Secretary.

T reasu re r :To be el igible to ho ld t h e off ice o f Treasurer , an ind iv idua l m u s t b e a m e m b e r o f t he Society, o t h e r t h a n a S t u d e n t Member , m u s t be f r e q u e n t l y avai lable to t h e Na t i ona l Of f i ce a n d s h o u l d be o f e x e c u t i v e s t a t u s in b u s i n e s s o r i n d u s t r y w i t h e x p e r i e n c e in f inancial affairs.

Director-at -Large:To be el igible for e l e c t i on as a Director-at-Large, an ind iv idua l sha l l p r e v i o u s l y h a v e h e l d of f ice as C h a i r m a n o f a Sec t ion ; as C h a i r m a n o r Vice C h a i r m a n of a s tanding , t e chn ica l or specia l c o m m i t t e e o f t he Society; or as Distr ict Director.

I n t e r e s t e d p a r t i e s a re to s e n d a l e t t e r s t a t i n g w h i c h p a r t i c u l a r o f f ice t h e y are seeking , i nc lud ing a s t a t e m e n t o f qual i f icat ions, the i r w i l l i ngness and ability to se rve if n o m i n a t e d and e l ec t ed and 20 cop ie s o f the i r b iographica l ske tch .

Th i s ma te r i a l s h o u l d be s en t to Rober t J .Teuscher , C h a i r m a n , Nat ional Nomina t - ing C o m m i t t e e , A m e r i c a n Weld ing Society, 550 N.W. LeJeune Rd., Miami, FL 33126.

T h e n e x t m e e t i n g o f t h e Na t i ona l N o m i n a t i n g C o m m i t t e e is c u r r e n t l y s c h e d - u l e d for May 6, 2001, in C leve l and , O h i o . T h e t e r m s o f of f ice for c a n d i d a t e s no m i - na t ed at this m e e t i n g will c o m m e n c e J u n e 1 ,2002. •

¢ Honorary-Meritorious Awards The Honorary-Meritorious Awards Commit tee has the duty to make recommendat ions

regarding nominees presented for Honorary Membership, National Meritorious Certificate, William Irrgang Memorial and the George E. Willis Awards. These awards are presented in conjunct ion with the AWS Exposition and Convention held each spring.The descriptions of these awards follow, and the submission deadline for consideration is July 1 prior to the year of presentation. All candidate material should be sent to the attention of John J. McLaughlin, Secretary, Honorary-Meritorious Awards Committee, 550 N.W LeJeune Road, Miami, FL 33126.

National Meritorious Certificate Award: This award is g iven in r e cogn i t i on o f t he cand ida te ' s counse l , loyalty and devo t ion to t he affairs o f the Society, a s s i s t ance in p r o m o t i n g cordial relat ions wi th indus t ry and o t h e r o rganiza t ions , and for the con- t r ibu t ion o f t ime and effor t on beha l f o f the Society.

W i l l i a m I r r g a n g M e m o r i a l A w a r d : This award is administered by the AmericanWeld- ing Society and sponsored by The Lincoln Electric Company to hono r the late William Irrgang. It is awarded each year to the individual w h o has done the mos t to e n h a n c e the Amer ican Welding Society's goal o f ad- vanc i ng the sc i ence and t e c h n o l o g y of welding over the past five-year period.

George E. W i l l i s A w a r d : This award is adminis te red by the Amer ican Welding So- ciety and s p o n s o r e d b y T h e Lincoln Elec- tric C o m p a n y to h o n o r George E.Willis. It is awarded each year to an individual for p r o m o t i n g t he a d v a n c e m e n t o f w e l d i n g in t e rna t iona l ly by fo s t e r i ng c o o p e r a t i v e par t ic ipa t ion in areas such as t e c h n o l o g y transfer, s tandards rationalization and pro- mo t ion of industr ial goodwill .

I n t e r n a t i o n a l M e r i t o r i o u s Cert i f i - c a t e A w a r d : T h i s a w a r d is g i v e n in r e c o g n i t i o n o f t h e c a n d i d a t e ' s s igni f i - c a n t c o n t r i b u t i o n s to t h e w o r l d w i d e w e l d i n g i n d u s t r y . T h i s a w a r d s h o u l d re- f l e c t " S e r v i c e to t h e I n t e r n a t i o n a l Weld- ing C o m m u n i t y " in t h e b r o a d e s t t e r m s . T h e a w a r d e e is n o t r e q u i r e d to b e a m e m b e r o f t h e A m e r i c a n W e l d i n g So- ciety. Mul t ip le a w a r d s c a n be g i v e n p e r y e a r as t h e s i t u a t i o n d i c t a t e s . T h e a w a r d c o n s i s t s o f a c e r t i f i c a t e to b e p r e s e n t e d at t h e a w a r d ' s l u n c h e o n o r at a n o t h e r t i m e as a p p r o p r i a t e in con- j u n c t i o n w i t h t h e AWS P r e s i d e n t ' s t r ave l i t i n e r a r y , a n d , i f a p p r o p r i a t e , a o n e - y e a r m e m b e r s h i p to AWS.

H o n o r a r y M e m b e r s h i p A w a r d : An H o n o r a r y M e m b e r shal l be a p e r s o n o f a c k n o w l e d g e d e m i n e n c e in t h e w e ld - i n g p r o f e s s i o n , o r w h o is a c c r e d i t e d w i t h e x c e p t i o n a l a c c o m p l i s h m e n t s in t h e d e v e l o p m e n t o f t h e w e l d i n g ar t , u p o n w h o m t h e A m e r i c a n W e l d i n g So- c ie ty s ee s fit to c o n f e r an h o n o r a r y dis- t i n c t i o n . An H o n o r a r y M e m b e r sh a l l have full r i g h t s o f m e m b e r s h i p . •

74 I FEBRUARY 2001

CALL FOR PAPERS

Eleventh International Conference on Computer Technology in Welding

September 19 and 20, 2001 - - Columbus, Ohio

This is the eleventh in a series of computer conferences designed to provide the welding industry with the latest information regarding the use of computers for welding. This conference, jointly sponsored by the American Welding Society, The Welding Institute and the National Institute of Standards and Technology, will be held September 19 and 20, 2001, in Columbus, Ohio. Authors from around the world are strongly encouraged to submit an abstract, as attendance from an international audience will be encouraged.

Authors should submit the Author Form (on reverse side), together with an abstract of no more than 500, words to American Welding Society, Conference Department, 550 NW LeJeune Road, Miami, FL 33126, by January 31, 2001. The abstract should be sufficiently descriptive to give a clear idea of the content of the proposed paper. Authors will be notified of acceptance by March 5, 2001. Complete manuscripts will be required from selected speakers by May 1, 2001.

Authors are not limited to any specific topics, except that papers should be appropriate for the conference subject. Contributions are encouraged in the following areas:

• Modefing of Welds" and WeMing Processes • Off-Line Planning/WeM Simulation~Visualization • Computerized Data Acquisition and Sensing Systems • Real-Time Welding Information and Control Systems • WeM Process' Automation • Network and Web-Based Implementations • Case Histories~Experiences with Commercial Software (by users) • WeMing Documentation (e.g., PQR) • Databases, Database Applications and Knowledge Bases • Standards

To ensure your paper's consideration for the conference, your abstract must be postmarked no later than January 31, 2001.

Author Application Form

Eleventh International Conference on Computer Technology in Welding September 19-20, 2001 - - Columbus , Ohio

Date Mai led

Author's Name: Please check how you are addressed: Mr. Title or Position:

Ms. Dr. Other

Organization: Mailing Address: City: State: Zip Code: Country: Telephone: Fax:

For joint authorship, give names. (If more than two coauthors, please use separate sheet.)

Name: Name: Organization: Organization: Address: Address:

P R O P O S E D TITLE (10 words or less):

ABSTRACT: • Typed, double-spaced, 250-500 words, attached to this form. • Be sure to give information to provide a clear idea of content of the proposed paper. • If completed manuscript is available now, in addition to abstract, attach copy to this

form. • Application form and abstract must be postmarked no later than January 31, 2001.

M A N U S C R I P T DEADLINE: • All manuscripts must be submitted no later than May 1, 2001. • Guidelines for submission of manuscripts will be provided to authors

selected for the program.

P R E S E N T A T I O N AND PUBLICATION OF PAPERS: Has material in this paper been previously published or presented at any meeting?

Yes No When? Where?

Return to AWS postmarked no later than January 31, 2001, to the following address:

Conferences American Welding Society 550 N.W. LeJeune Road Miami, Florida 33126 Phone: (800) 443-9353, Ext. 223, or (305) 443-9353, Ext. 223 Fax: (305) 443-1552

MAX INTERNATIONAL Right For Your Business

~r the next 12 months, you will have to know how to compete more intensely than ever before to keep your plant running or your shop open and to make a decent profit. What new equipment and technologies should you buy to increase your productivity? How do you better utilize your existing plant and equipment to be more productive and cost competitive? How will you find out what is going on in your industry? Where will you learn how other people are solving challenges similar to yours, and how can you make your own plans for the future?

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Every MAX INTERNATIONAL exhibitor wants you to bring them your tough questions. Whether you are looking for new equipment, or want to get more productivity out of your existing equipment, exhibitors are there to help you get answers. Bring your problems, equipment needs and questions to MAX INTERNATIONAL. Let world-class experts help you get the right answers, the right equipment, and the targeted solutions you can take back and put to work. Let them help you make the right decisions.

I N T E R N A T I O N A L M a y 6-10, 2001

I-X Cen te r Cleveland, OH

Literature For more information, circle number on Reader Information Card.

Boiler and Pressure Vessel Safety Video Released

Case For Safety II, a video from the National Board of Boiler and Pressure Vessel Inspectors, makes the case for vigilance anywhere boilers and pressure

plant that resulted in six dead and fourteen injured, and a boiler explosion at a South Carolina high school. The video cautions against indifference to equipment that can be found in nearly every building and home in North America today. The tape is available for $15 plus shipping and handling.

The National Board of Boi ler and Pressure Vessel Inspectors 1055 Crupper Ave., Columbus, OH 43229-1183

White Paper Explains Advantages of Stud Welding

Solutions in Metal Fastening: The Advantages o f Stud Welding presents the steps of drawn arc and capacitor discharge (CD) stud welding methods and provides comparative information against other metal fastening processes. It demonstrates how stud welding helps companies increase metal fastening productivity and save costs, while maintaining high product quality. The paper describes the techniques of drawn arc stud welding, short arc stud welding, gas arc stud welding, contact CD stud

welding and gap CD stud welding. Comparison charts show how stud welding performs against brazing/ soldering, boring/ drilling/tapping, clinch fastening and resistance welding, conventional bolting and manual welding.

Image Industries 115 382 Balm Ct., Wood Dale, IL 60191

Magnet Catalog Introduced

The 28-page MAG-MATE TM 101-H catalog on holding, lifting and fixturing magnets has been released. Containing more than 21 products, the catalog offers hundreds of standard magnets designed with ceramic, Alnico TM, rare earth or electromagnetic materials. With applications in metalworking, fabricating, appliance, automotive,

vessels can be found. Featuring actual television footage of recent incidents, the video focuses on the personal and economic consequences of boiler and pressure vessel accidents. Included are reports on a pressure tank explosion at an Indiana steel mill that killed three people and injured nine, a catastrophic boiler explosion at a Michigan auto

COR-MET ®

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78 J FEBRUARY 2001

automation and robotics industries, the catalog offers a wide variety of magnetic solutions including raw materials, magnetic hand tools, holding, lifting, fixturing, transferring and sweeping magnets. Most magnets are available in stock for same-day shipment. Modified standards or custom designs are available upon request.

Industrial Magnets 116 1240 M-75 S., Boyne City, MI 49712-0080

Brochure Features Pneumatic Tools

The company is offering a 60-page brochure on its complete line of pneumatic tools. The range of products include vertical, horizontal and right- angle grinders, die grinders, chipping hammers, rammers, air saws, air drills, air routers, scalers, power supply

potential inadvertent hazards. Various control measures, the development of laser safety p rograms , po ten t ia l nonbeam hazards, criteria for exposure to eyes and skin, and measurements, as well as i n s t rumen ta t i on re la ted to outdoor laser use, are also detailed. The list pr ice is $90, $70 for L IA members.

Laser Inst i tute of America 13501 Ingenuity Dr., Suite 128, Orlando, FL 32826

Robotic Guide Available in Pocket Size

A pocket-sized guide with complete descriptions, specifications and photos for robots, positioners, cells, flexible manufac tur ing systems and robot traveling columns and tracks is available. Process equipment , torch products , sensors and off-line p rogramming information is also provided. The guide

- - con t inued on page 87

motors, wheel guards, collets, pads, butts and pins, bushings, adapters and special accessories. Quick reference charts for selecting and ordering are included. I n fo rma t ion on p roduc t features, applications and accessories, product specifications and dimensions are also available in the b rochure . Information about the safe operation of air tools is also included.

T. C. Service 117 633 W. Bagley Rd., Berea, OH 44017

Aerospace Welding Leaflet Released

The company has issued a leaflet on aircraf t , jet engine and ae rospace resistance welding. It details the range of equ ipmen t available f rom the company and includes information on medium-frequency inverter welding, which can satisfy the demand for reduced power consumpt ion and operating costs.

British Federal Ltd. 118 Castle Mill Works, Dudley, West Midlands DYI 4DA, U.K.

ANSI Laser Standard Published

The Laser Ins t i tu te of Am e r i c a (LIA) has released ANSI Z136.6 (2000) American National Standard for Safe Use of Lasers Outdoors. Providing gu idance for safely using lasers outdoors , including those that have been granted a variance or exemption from the provisions of the U.S. Federal Laser Product Performance Standard (21 CFT 1040), this s t anda rd is designed to be a supplement to the revised ANSI Z136.1 (2000) for Safe Use of Lasers. The s tandard covers classification and potential hazards associated with light shows, military lasers, lasers used in outdoor scientific research and wireless opt ical c o m m u n i c a t i o n systems dep loyed ou tdoors . In addi t ion , it discusses

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confFP.html ( 8 0 0 ) 4 4 3 - 9 3 5 3 , e x t . 2 2 3

e - m a i l c o n f @ a w s . o r g .

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Na e A MANTECH Center of Excellence r Operated by S ~

D M C 2000 m Foundat ion for Global Secur i ty

NJC presents Knowledge-Based Inspection System (KBIS), Friction Stir Welding for Assault Vehicle, and Thermal Tensioning for Reduced Distortion

T he Defense Manufacturing Con- ference (DMC), hosted by the Joint Defense Manufacturing

Technology Panel, was held in Tampa, Fla., November 27-30. The conference served as a forum to present and discuss initiatives directed at Department of De- fense (DoD) manufacturing technology and sustainment needs. Based on the theme "Foundation for Global Secu- rity," attendees were given an overview of government and industry programs as well as a vision for the future of defense manufacturing and sustainment needs.

The Navy Joining Center (NJC) and more than 60 organizations exhibited to more than 700 attendees at the conference. NJC personnel gave several presentations during the technical sessions. Tim Trapp, NJC project manager, presented an "Overview of the Knowledge- Based Inspection Systems (KBIS)" and "Friction Stir Welding of Aluminum Armor for the Advanced Amphibious Assault Vehicle." Dr. James Dydo, business development manager, presented work on "Transient Thermal-Tensioning

Methods to Reduce Distortion in Thin Ship Panels."

The KBIS project is directed toward the development and validation of a knowledge-based ultrasonic inspection system for steel ship structures. KBIS will lower weld reject rates and repair costs by providing more information about weld discontinuities. The intent of KBIS is to enhance manual ultrasonic inspection by using a computer-based neural network system to classify flaw type and determine discontinuity size. KBIS will provide both hard copy and electronic records of inspection results for independent review and audit.

Friction stir weld development is being done to join aluminum Alloy 2519 for armor on the Advanced Amphibious Assault Vehicle (AAAV). The project supports the AAAV program by devel- oping procedures to improve productivity, reduce acquisition costs, reduce distortion and maximize ballistic performance. NJC activities are centered on the development of optimal welding procedures for a range of material thick-

Navy Joining Center Fellowships A s part of its commitment to further technical education and the advancement of materials joining technology, the Navy Joining Center supports two graduate fellowships each year. These fellowships are awarded through the American Welding Soci- ety Foundation to support graduate students whose research topics address materials joining.

The NJC Fellowships for the 2000-2001 academic year have been awarded to Chad S. Kusko of Lehigh University and Jason E. Mitchell of Vanderbilt University. Kusko has been a previous recipient of an NJC fellowship and is pursuing a doctorate degree in material science and engineering with a dissertation titledA Fundamental Study of Fatigue Crack Propagation along the Fusion Line in Dissimilar Weld Metals. Mitchell is pursuing a master's degree in mechanical engineering with studies in "an investigation of the forces produced during friction stir welding with an objective of improved control."

Please contact the AWS Foundation at (800) 443-9353 ext. 689 for more information on NJC Fellowships.

nesses in the form of groove weld and corner- and T-joint configurations. Upon completion of the development activities, the project will provide friction stir welding tooling concepts, determine machine requirements and develop robust procedures and production methods to support efficient vehicle production.

The presentation on transient thermal-tensioning methods to reduce distortion in thin ship panels described an ongoing development effort aimed at reducing weld distortion in "thin" ship panels. Typical ship panels are fabricated from plate structure that is reinforced with welded T stiffeners. During welding, plastic deformation is induced in the plate creating out-of-plane distortion after cooling. This process involves the application of dynamic local auxiliary heating away from the welded area that causes the panel to "tension" in the weld area. The thermal tensioning effect greatly reduced distortion in the finished welded panel.

For more information regarding the NJC presentations at DMC 2000, please call Tim Trapp at (614) 688-5231, e-mail [email protected], or James Dydo at (614) 688-5116, e-mail [email protected]. •

The Navy Joining Center 1250 Arthur E. Adams Dr.

~ ~ Columbus, OH 43221 Phone: (614) 688-5010

Operated by FAX: (614) 688-5001 E ~ i e-mail: [email protected]

www: http://www.ewiorg Contact: Harvey Castner

80 I FEBRUARY 2001

A B Y R . L. P E A S L E E

Q: We are using a stored-energy resistance spot welding machine to tack hon- eycomb cells to the inside of seal rings before vacuum brazing. The spot welds are not reliable when welding on nickel- plated gamma-prime material surfaces. The nickel plating is applied to prevent oxidation of aluminum and titanium in the base metal during the vacuum brazing cycle, facil itating a good quality braze. Why are the welds weak, and what can be done to eliminate this problem?

A : Nickel plating is a lamellar structure made up of molecule-sized nickel particles, progressively laid on top of the sub-

strate, and presents a different structure than the crystalline base metal. If spot welding is done within days of the plating, bond strength to the base metal will be more of a cohesive force than if the plating is held for long periods of time before spot welding. Also, spot welding may not take to the lamellar-type structure presented by the plated surface, resulting in unreliable welds. Another point to consider is that the plating on gamma-prime materials is difficult. Cleaning base metal prior to going into the nickel-plating bath is very important because it affects bond strength. When the base-metal surface is not adequately cleaned, blisters will be visible in the plating after the plated parts have been processed through the furnace.

Testing the plating bond can be easily accomplished by putting the parts in a vacuum furnace and heating them to 1800°F (980°C), holding the parts at

temperature for five to ten minutes followed by cooling. This cycle allows you to see if there are any blisters. If there are, the bond between the base metal and the plating has been broken and the plating should be removed and the part recleaned and replated. If recleaning and replating are not done, spot welding or brazing would definitely yield poor results. Also, the cycle changes the lamellar structure to a crystalline structure and creates a diffusion weld between the plating and the base metal. Because titanium and aluminum will diffuse up through the plating, this cycle should not be run at a high temperature or for a long period of time. If the plating is thin, you will have titanium and/or aluminum oxide on the surface of the nickel, thus inhibiting the brazing wet-

- - continued on page 87

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WELDING JOURNAL 1 81

A B Y D A M I A N J. K O T E C K I

Q: I am trying to qualify welding procedures for 304L and 316L equipment for cryogenic service in liquid nitrogen or liquid hydrogen. The December 2000 Stainless Q&A column proposed 3 FN minimum for 308L and 316L weld metals for freedom from hot cracking. But when I test welding procedures using covered electrodes or submerged arc with 5 to 10 FN, I fail toughness requirements of 15-mils lateral expansion at -320°F (-196°C, or 77 K). I have no trou- ble with the base metal tests. How can I meet this toughness requirement in the welds without hot cracking?

A: Austenitic stainless steels, including their weld metals, do not undergo the rather abrupt transition from ductile fracture to brittle fracture with falling temperature that is experienced by common mild steel and low-alloy steels. Rather, they experience a gradual decline in toughness, measured as either absorbed energy or lateral expansion in the Charpy V-notch impact test, with falling temperature. At cryogenic temperatures, the fracture mode in austen- ite is still normally ductile tearing, not brittle cleavage. However, the ferrite in a nominally austenitic stainless steel weld metal can experience cleavage fracture, so it is often essential to limit the amount of ferrite to increase the fracture energy at cryogenic temperatures.

Also, keep in mind that the Charpy V- notch impact test becomes invalid at temperatures much below -320°F. It is valid for liquid nitrogen testing but not for liquid hydrogen testing since liquid hydrogen temperature at atmospheric pressure is about--423°F (-253°C, or 20 K). Colder still is liquid helium, at -452°F (-269°C, or 4 K). The problem with Charpy impact testing at these very low temperatures is that the thermal capacitance of the metal approaches zero, so as plastic deformation begins in the root of the notch during the impact test, adiabatic heating occurs, which raises the temperature of the metal. The only valid tests at these very low temperatures are slow strain rate fracture toughness tests, where liquid hydrogen or liquid helium can extract heat fast enough to overcome

adiabatic heating. But fracture toughness tests are highly specialized and expensive, so the average, or even above average, fabrication shop can't afford them. The ASME Code Committee, after examining correlations between fracture toughness tests at liquid helium temperature and Charpy V-notch results at liquid nitrogen temperature, proposes to require 21-mils (0.53-mm) lateral expansion, not 15-mils (0.38-mm) lateral expansion, at liquid nitrogen temperature to qualify a welding procedure for service at liquid helium temperature. As a result, your problem could become even more difficult in the future than it is now.

Coming back to the topic of toughness of nominally austenitic stainless steel weld metals, there have been a number of studies on cryogenic toughness. One of the best known is that of Szuma- chowski and Reid (Welding Journal, November 1978 and February 1979). This work showed ferrite and nitrogen are detrimental to Charpy V-notch impact toughness at liquid nitrogen temperature. It also showed the lime-fluoride slag system (e.g., AWS A5.4 E316L-15 electrodes) produced better toughness at a given ferrite and nitrogen level than did a rutile slag system (e.g., AWS A5.4 E316L- 16 electrodes). The difference between a -15 coating and a -16 coating is due to the oxygen (inclusion) content of the weld metal. The -15 coating produces lower oxygen (about 400 ppm) vs. the -16 coating (about 600 ppm) or -17 coating (about 900 ppm). Therefore, to improve your chances of meeting cryogenic impact requirements, choose low-ferrite, low-nitrogen filler metal with a lime-fluoride (-15) coating. Or, in submerged arc welding, choose a high-basicity flux with a low-ferrite, low-nitrogen filler metal.

But you can do better. The effect of oxygen continues below 400 ppm. A slag- free-inert-gas-shielded process (GTAW or GMAW) can produce on the order of 150 ppm or less of oxygen in the weld metal. I've routinely found low-nitrogen (0.04% or 400 ppm) AWS A5.9 ER308LSi and ER316LSi wires with about 10 FN, welded GMAW, spray transfer, with 98% argon-2% oxygen shielding gas, that produce Charpy V-notch toughness of about 30-mils (0.76-mm) lateral expansion at liquid nitrogen temperature. This is not specially melted material, just commercial quality. At this ferrite level, there are no fears of hot cracking.

On the other hand, if you want to use

a flux-shielded process, you will have to look at filler metals below 5 FN, with highly basic slag systems. As a result of the Szumachowski and Reid work, AWS A5.4 E316L-15 covered electrodes and AWS A5.22 E316LT-3 self-shielded flux cored wires with a highly basic slag system were produced to 2 FN maximum. These were used for fabrication of 304L stainless steel magnet cases for super- conducting magnets for the fusion energy program at Lawrence Livermore National Laboratory. Note that, today, the E316LT-3 filler metal would be classified as E316LT0-3 because the AWS A5.22 standard, as revised in 1995, now includes a welding position indicator ("0" for downhand and horizontal positions only), which it did not when the filler metal for Livermore was manufactured. The steel ranged up to 4 in. (100 mm) thick. Welds were qualified by testing both for 15-mils lateral expansion at liquid nitrogen temperature and for fracture toughness at liquid helium temperature. The welds met the toughness requirements and did not hot crack. The 316L filler metals were chosen because 316L seems to be more resistant to hot cracking than 308L when the ferrite is very low. Low phosphorus, low sulfur and high manganese are also important to the hot cracking resistance of such weld metals.

Nickel-based-alloy filler metals (e.g., AWS A5.11 classes ENiCrFe-2, ENi- CrFe-3 and ENiCrMo-3) can also meet the cryogenic toughness requirements. These have no ferrite, but are crack resistant. They cost considerably more than stainless steel electrodes.

To sum up, your choices for meeting cryogenic toughness requirements are GMAW or GTAW with filler metals of normal FN or slag-shielded filler metals with below 2 FN.

DAMIAN J. KOTECK1 is Technical Director for Stainless and High-Alloy Product Development for The Lincoln Electric Co., Cleveland, Ohio. He is a member of the AWS A5D Subcommittee on Stainless Steel Filler Metals; A W S D1 Structural Welding Committee, Subcommittee on Stainless Steel Welding; and a member and past chair of the Welding Research Council Subcommittee on Welding Stainless Steels and Nickel Base Alloys. Questions may be sent to Mr. Kotecki c/o Welding Journal, 550 N.W. LeJeune Rd., Miami, FL 33126.

82 I FEBRUARY 2001

Safety In Welding, Cutting, and Allied Pmcesxs

Z49... The "finest publication on welding safety in the world" has been thoroughly updated! Unions, societies, trade groups, U.S. military and U.S. enforcement agencies all contributed to the latest edition of Safely in WeMing, Cutting, and Allied Processes -- including AWS, Sheet Metal Workers, OSHA, and NIOSH. 52 pages cover oxyfuel gas welding and cutting safety, arc welding and cutting equipment safety, resistance welding safety, electron beam processes, and laser beam cutting and welding safety. Four appendices. Published in 1999;ANSI-Approved.

Z40.1:1999 ........................ 88.00 AWS members .................... 66.00

Order Now! AWS has secured Global Engineering Documents for sales and order

fulfillment to ensure Member and customer satisfaction. Call (800) 854-7179. Credit cards are secure on www.global.ihs.com

Don't miss this free session at the AWS Expo in Cleveland!

"What You Need to Know About Safety & Health Issues in the Welding Environment" Monday, May 7, 2001

• Proposed ~uidelines for manganese and chromium exposure that can affect all welding operations update on OSHA activity in the welding area K. Brown, project research manager, The Lincoln Electric Co., Cleveland

• How to select the fume removal system that is best for your workspace introduction to a new AWS ventilation document T. Pumphrey, The Lincoln Electric Co., Cleveland

• What type of welding curtain is best for your application? introduction to a new A ~ document on welding cumins B. Tucker, director, Technical and R&D, Dalloz Safety, Lakeland, FL

• Are you still worried about issues like these: contact lenses, pacemakers, or electro-magnetic fields (EMF)? AWS "Safety and Health Fact Sheets" are your quick guide to safety in the welding environment R. Jennings, manager, Technical Publications, Miller Electric Mfg. Co., Appleton, Wl

• Fire Safety in Metal Fabrication See this new NFPA video along with expert commentary A. E Manz, A. E Manz Associates, Union, NJ

Chair: K. Lyttle, senior development associate, Praxair, Inc., Tarrytown, NY

CoChair: S.R. Fiore, senior engineer, Edison Welding Institute, Columbus, OH

To learn more about the AWS WELDING SHOW 2001, go to aws.org or watch your mail for the 2001 Advance Program featuring the AWS WELDING SHOW 2001 and PMA's METALFORM 2001.

C W E L D I N G S H O W 2 O O 1 I N T E R N A T I O N A L E X P O S I T I O N A N D A N N U A L C O N V E N T I O N

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Visit our website http:/Avww.aws.org

Air Products Elects Chairman/CEO

Air Products and Chemicals, Inc., Al- lentown, Pa., announced the election of John P. Jones I I I as chairman of the board, president and chief executive of- ricer. He succeeds Harold A. "Hap" Wagner, who was the company's chairman and chief executive officer since May 1992. Jones previously served as the company's president and chief operating officer. Jones joined the company in 1972 as a participant in its Career and Devel- opment Program and subsequently worked in various management positions in the process gas international division; the International Coal Refining Com- pany; and the Stearns Catalytic World Corporation. He also held executive as- signments as vice president and general manager of environmental and energy systems, group vice president for the Pro- cess Systems Group and president of Air Products Europe. In 1996, Jones was named executive vice president, Gases and Equipment Group, and, two years later, assumed the position of president and chief operating officer. Since 1998, he has served on the company's board of directors. Jones holds a B.S. in chemical engineering from Villanova University, is on the board of directors of the Amer-

ican Chemistry Council and is a member of the board of trustees of the Rider-Pool Foundation.

Motoman Appoints Vice President and Director

Motoman, Inc., Dayton, Ohio, has named Steve Barhorst [AWS] as vice president of finance/chief financial officer. In this position, he is responsible for the Information Systems and Finance Departments. Barhorst earned a B.S. degree from Miami University. After receiving his Certified Public Accountant certification, Barhorst was employed for nearly nine years at Ernst & Young, where he advanced to senior manager status. His experience also includes serving as chief financial officer at Fidelity Health and vice president of finance and chief financial officer at Dolly, Inc.

Carl Traynor was named director of marketing. His background includes a B.A. in economics from the University of Michigan and a J.D. from the Univer- sity of Minnesota Law School. Traynor was an attorney for Lincoln National Corp. and a technology business consultant at the Michigan Center for High Technology. Most recently, Traynor was vice president of business development at Dynalog, Inc.

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All-Fab Corporation welding positioners from 200 to 1250 pound capacity. Compare our price, quality and features.

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Wal l Colmonoy Names Vice President

Daniel C. Fulgham was appointed group vice president for the Process Business Units at Wall Colmonoy Corp., Madison Heights, Mich. In this position,

Fulgham

he oversees the four processing facili- ties in Dayton, Philadelphia, Oklahoma City and San Antonio. Fulgham was previously vice president/general manager at Bristol Aviation Services in Okla- homa. He has more than 22 years of experience in the aviation industry and obtained a B.S. degree in aviation science and management from Oklahoma State University.

Panasonic Factory Automation Appoints Sales Engineer

Panasonic Factory Automation Co. (PFA), Franklin Park, I11., announced Pat Clark [AWS] has joined the corn-

Clark

84 I FEBRUARY 2001

pany as a senior sales engineer. His responsibilities are to support the sales of robotics, welding equipment and welding robotic systems. Prior to joining the company, Clark began his career with a major gas and equipment manufacturer. He was previously plant manager, director of purchasing, distributor manager and has worked both inside and outside sales.

DE-STA-CO Names Manager

DE-STA-CO, Madison Heights, Mich., announced the promotion of Brent Conn to the position of quality manager for its Industrial Products Group. He is responsible for the quality of all products purchased and produced at the company's Birmingham, Mich., plant. Conn joined the company in 1997 as a quality engineer. He holds both a bachelor's degree in journalism and a master's degree in written communications from Eastern Michigan University.

ESAB Announces Appointments

ESAB Cutting Systems, Florence, S.C., announced the following appointments:

Robert Seripnick was named director, machine tool sales. He will be responsible for sales of ESAB's specialty machines including the Alpharex laser and Hydrocut waterjet product lines. Scripnick was previously marketing manager and product manager for the company's gantry cutting systems.

Scripnick Lawrence

Hal Lawrence was named product manager, cutting tables and environmental equipment. He will oversee the

development and production of cutting tables and environmental equipment used with the company's gantry cutting systems. An ESAB employee since 1977, Lawrence's previous duties included senior project manager, large gantry machines project manager and project ad- ministrator and small gantry machines production planner.

Jim Johnson was appointed manager of the company's standard products line. Johnson rejoins the company, where he worked as a software engineer from 1993 to 1999. In this position, Johnson oversees the marketing of small- to medium- sized mechanized cutting systems.

Johnson Defalco

Jeff Defalco [AWS] was named product manager for machine tools. His responsibilities include overseeing all aspects of the company's laser, waterjet and Precision Plasma cutting systems. Defalco was previously the company's senior design engineer and regional sales manager for Asia.

Joe Blackmon I I I was promoted to the position of marketing manager. He assumes responsibility for overseeing all facets of marketing and advertising for the company's product lines. Employed with the company since 1988, Blackmon previously worked as business manager, senior product manager and senior buyer.

Blackmon HI Kearns

Laura Kearns was appointed to the position of manager, machine tool sales. She is responsible for sales west of the Mississippi, with special focus on the company's Alpharex laser and Hydrocut waterjet product lines. Kearns has been with the company for 16 years, with experience in purchasing, production control, project management, software sales and cutting machine sales.

Tempil* Announces Staff Additions

Pramathesh Desai [AWS] has joined the sales and marketing team of Tem- pil °, Inc., South Plainfield, N.J. He joins the company after serving 13 years as welding services manager for the Kanoo Group, Dubai, United Arab Emirates. Desai holds a master's degree in materials engineering from the Cranfield Insti- tute of Technology, United Kingdom, a B.E. in metallurgical engineering from M.S. University, Baroda, India, and a business management diploma from In- dian Merchant's Chamber, Bombay, India.

Nainesh "Nate" Mehta [AWS] has joined the R&D staff of the company. His prime responsibilities include managing the R&D staff. Before joining the company, Mehta was with the R&D department of Dunmore Corp., Newton, Pa. He holds B.S. and M.S. degrees in chemistry.

Obituary

Bob White

Bob White, vice president of sales and marketing for Norris Cylinder Co., died on Friday, December 8, 2000.

White joined Norris in 1985 as south- eastern regional sales manager and served in that capacity until February 1995, at which time he was promoted to vice president, sales and marketing. Prior to joining Norris, he spent 15 years with M&A Welding Supply in Atlanta, Ga. He was president of M&A from 1981 to 1985.

White is survived by his wife, Stephanie, three children and two grand- children.


rences I & Seminars

AWS D I. I CODE WEEK The #1 selling welding code now comes alive in a five-day seminar that begins with a roadmap of D1.1:2000, Structural Welding

Code - - Steel. This is your opportunity to learn from an expert AWS instructor and ask your toughest questions about DI.1. Code week continues with corresponding subjects geared toward engineers, supervisors, planners, welding inspectors and welding technicians. Since your

work is based on a reputation for reliability and safety, you want the latest industry consensus on prequalification. If you want to improve your competitive position by referencing the latest workmanship standards, inspection procedures and acceptance criteria, you won't want to miss this seminar! Each day will be in-depth and intense.

(Day 1, Monday) D I. I Road Map San Francisco, Calif. - - March 5, 2001 St. Louis, Mo. - - April 9, 2001 Chicago, Ill. - - July 16, 2001 Las Vegas, Nev. - - September 17, 2001 Atlanta, Ga. - - November 5, 2001

(Day 2, Tuesday) Design of Welded Connections

San Francisco, Calif. - - March 6, 2001 St. Louis, Mo. - - April 10, 2001 Chicago, Ill. - - July 17, 2001 Las Vegas, Nev. - - September 18, 2001 Atlanta, Ga. - - November 6, 2001

(Day 3, Wednesday) Qualifications San Francisco, Calif. - - March 7, 2001 St. Louis, Mo. - - April 11, 2001 Chicago, I11. - - July 18, 2001 Las Vegas, Nev. - - September 19, 2001 Atlanta, Ga. - - November 7, 2001

(Day 4,Thursday) Fabrication San Francisco, Calif. - - March 8, 2001 St. Louis, Mo. - - April 12, 2001 Chicago, I11. - - July 19, 2001 Las Vegas, Nev. - - September 20, 2001 Atlanta, Ga. - - November 8, 2001

(Day 5, Friday) Inspection San Francisco, Calif. - - March 9, 2001 St. Louis, Mo. - - April 13, 2001 Chicago, Ill. - - July 20, 2001 Las Vegas, Nev. - - September 21, 2001 Atlanta, Ga. - - November 9, 2001

Prices Member Nonmember

(One-day seminar) $345 $420 (Entire week) $795 $870

U P C O M I N G C O N F E R E N C E S

W E L D CRACKING: CAUSES A N D CURES CONFERENCE

June 7-8, 2001 1 Houston, Tex. Hydrogen-induced cracking isn't the only culprit that engineers and QC professionals need to be on the alert against. AWS experts will identify other, often unknown or overlooked cracking scenarios, along with the best use of counteroffensives, including preheat and peening. Other areas covered include the best use of ultrasonics and Charpy tests, plus the lowdown on new test options. This intense day-and-a-half program covers cracking in steels, aluminum, stainless steels and titanium.

THE C U T T I N G OF PLATES CONFERENCE July 17-18, 2001 1 Chicago, III.

For decades, the only plate cutting method was oxyfuel cutting. It is still used, but recently, methods like plasma cutting, high- definition plasma cutting, water jet cutting and both CO 2 and YAG laser cutting are more frequently used. Many companies are in turmoil deciding which method is best. This conference will provide engineers with greater understanding of the issue, knowledge about the cost of equipment, payback, cutting performance and valuable information that can be implemented profitably into their company's production lines. This conference will cover mostly steel, with some mention of stainless and aluminum. Topics include laser cutting, plasma

cutting, high-definition plasma cutting, water jet cutting and innovations in oxygen cutting.

ELEVENTH I N T E R N A T I O N A L CONFERENCE O N COMPUTER T E C H N O L O G Y IN W E L D I N G

September 19-20, 2001 m Columbus, Ohio.

The eleventh in a series of computer conferences will provide the welding industry with the latest information regarding the use of computers for welding. The conference brings together experts on sensors, equipment control, process modeling and data acquisition. Engineers, managers and system integrators will benefit from discussions of hardware and software installations and user experiences with these systems. Integration of welding systems with network and Web applications will be emphasized. Topics to be discussed include modeling of welds and welding processes; off-line planning/weld simulation/visualization; computerized data acquisition and sensing systems; real-time welding information and control systems; weld process automation; network and Web-based implementations; case histories/experiences with commercial software (by users); welding documentation (e.g., WPS, PQR); databases, database applications and knowledge bases; standards.

For further information contact: Conferences, American Welding Society, 550 N.W LeJeune Road, Miami, FL 33126. Telephone: (800) 443-9353 ext. 223 or (305) 443-9353 ext. 223, FAX: (305) 443-1552. Visit the Conference Department homepage http://www.aws.org for upcoming conferences and registration information.

86l FEBRUARY 2001

New Literature - - c o n t i n u e d f r o m / ) a g e 79

ting and flow you wish to obtain. A nickel-plating thickness of 0.0001 in. (0.0025 ram) is too thin, and since the aluminum and titanium will probably diffuse up to the surface, a thickness of at least 0.0005 in. (0.013 mm) is recommended.

Spot welding on a nickel surface with crystalline structure with a diffusion- welded bond to the base metal should improve the quality of the stored energy spot welds.

A blasting procedure using a nickel- chromium-silicon grit has been developed that eliminates the need for nickel plating. The process has been successfully applied to base metals containing lower amounts of aluminum plus titanium. Presently, it works on up to 2% of titanium plus aluminum. The process is not suitable for a 6% base metal containing aluminum, but, at this time, the cut-off point is uncertain, somewhere between 3 and 4%. Blasting is usually accomplished by using a pressure-pot- type blast unit with a 100-lb plant air supply and special blasting grit. Caution must be observed when attempting to blast thinner materials. There is no problem blasting a 0.250-in. (6.350-mm) thick base metal, but when the thickness decreases to 0.032 in. (0.813 mm), and specifically 0.020 in. (0.508 mm) or lower, heavy distortion can be experienced. Remember that blasting puts compressive stress into the surface, so if a surface of 0.032-in. strip is being blasted, the strip will bow toward the blasted surface. This is caused by the compressive stress in the surface, which tends to make the blasted surface longer than the unblasted surface. This is similar to a bimetal strip that has two different coefficient-of-expansion materials joined together. When the temperature changes, the bimetal bows because one side increases in length over the oppo- site side.

Furnace cycle testing of the plating ensures the plating process is in control and that the strength of the plating bond is very strong, resulting from the diffusion welding. Use of the special blasting procedure, within limits, has been very successful, and should be of help. •

R. L. P E A S L E E is Vice President, Wall Colmonoy Corp., Madison Heights, Mich. This article is based on a column prepared for the A WS Detroit Brazing and Soldering Division's newsletter. Reader questions may be sent to Mr. Peaslee c/o Welding Journal, 550 N. W. LeJeune Rd., Miami, FL 33126.

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120

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Structural Welding Code - - Reinforcing Steel This fifth edition of the ANSl-approved/DoD-adopted standard covers welding reinforcing steel In most reinforced concrete applications. Includes allowable stresses, inspection, qua~cation, structural detai~ joint details and workmanship requirements. Figmx~ dearly illustrate important welding considerations: unacceptable weld profiles, effectiv, weld sizes, details of joints of anchorages, base plates and inserts, e~. 9 tables, 5 annexes support 7 chapters. 45 pages, softbotmd, 3-hole punched. Published in 1998. 31.4-98 .................................. 76.00 AWS Members ........................ 57.00

Structural Welding Code - - Sheet Steel "One of the primary objectives of this code is to define the allowable capacities used in sheet steel applications in which the transfer of calculated load occurs." If you're responsible for the welding In steel decks, panels, storage racks, and stud and joist flaming members, to name a few applications, this code helps you to effect consistently sound welding of joints. Includes allowable load capacities, doails of welded connections, prequalification of WPSs, qualification, inspection, stud welding. 7 tables, 44 figures, 5 annexes, and Commentary. 76 pages, softbound, 3-hole punched. ANSI-approved and published In 1998. 31.3-98 .................................. 96.00 AWS Members ........................ 69.00

Bridge Welding Code All metric edition was developed with cooperation from/k~HTO and reflects its requirements Including those for NOT. Details requirements for Inspection, qualification, structural details, stud welding, welded joint details, and workmanship. Includes "Fraction Control Plan for Nonredundant Bridge Members." 250 pages, with 35 tables, 77 figures and several annexes. 8-1/2" x 11", softbound, 3-hole punched. ANSI-approved and published in 1996. OI.5-96 ................................ 156.00 AWS Members ...................... 117.00

Structural Welding Code - Aluminum This code set the rules and regulations necessary for welding su'uctural aluminum using the gas metal arc, gas tungsten arc, and plasma arc welding processes, as well as stud welding and plasma arc gouging, In dynamically loaded or cyclically- loaded nontubular structures as well as tubular structures. Developed under strict ANSI rides, Structural Welding Code -Aluminum Includes sections on Fabrication, Qualification of WPSs and Personnel and Inspection. ANSI-approved, Dept. of I)dense adopted, 224 pages. Published In 1997, 25 tables, 53 figures, 10 annexes as well as commenta~ organized by subject. 31.2-97 ................................ 124.00 AWS Members ........................ 93.00

Structural Welding Code - Stainless Steel This new code establishes the requirements for welding stainless steel using the gas metal, shielded metal, flux cored, and submerged arc welding processes, including stud welding. The code covers design, fabrication, qualification and pm]ualillcation of procedures, welding personnel qualification, and inspection. Includes 79 figures, 26 tables, and 12 annexes in 224 softbound pages. 31.6:1998 .............................. 124.00 AWS Members ............................ 93.00

< • American Welding Society 550 NW LeJeune Rd., Miami, FL 33126 http:/&ww.aws.org

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ABICOR Binzel .................................................................. 10 All Fab Corp ...................................................................... 84 AWS .............................................. 16,18&19,42,77,79,83,88

Cor-Met ........................................................................ 21,78

DCT ................................................................................... 20 Diamond Ground ............................................................... 87 Divers Academy ................................................................ 51

Edison Welding Institute .................................................... 46 Enerpro ............................................................................. 53 ESAB Welding & Cutting ......................................... 34,OBC

F&M Mafco .......................................................................... 3

GAL Gage ......................................................................... 49 Generico .............................................................................. 8

Hobart Brothers ................................................................... 1

J.P. Nissen ........................................................................ 51 Jetline Engineering ............................................................ 25

Kobelco ............................................................................... 2 Koike Aronson ................................................................... 22

La-Co Markal ..................................................................... 52 Lincoln Electric .................................................................. 13 Metorex ............................................................................. 50 Miller Electric .................................................................. 4&5

National Standard ............................................................. 15

Panametrics ........................................................................ 6

Select Arc ........................................................................ IBC Stress Relief ..................................................................... 26

T.J. Clark ........................................................................... 53 Tecnar ............................................................................... 54 Thermco ............................................................................ 52 3M ..................................................................................... 23

Wall Colmonoy .................................................................. 81 Weldcraft Products .......................................................... IFC Weld Hugger ..................................................................... 22 Weldsale ........................................................................... 51

I F C = Inside F r o n t C o v e r I B C = Inside Back C o v e r O B C -- O u t s i d e Back C o v e r

Call for Papers The Tenth International JOM Jubilee Conference on Joining of Materials, JOM-10, is accepting papers for presentation May

11-14, 2001, in Helsingor, Denmark. Organized by the JOM Institute and held biennally since 1981, the conference encourages the presentation of the latest in welding research and development with an emphasis on relevance to industrial applications. It attracts engineers, scientists and educators from all over the world.

Papers are invited on, but are not limited to, the fol lowing topics: • Welding processes and systems • Weldabil i ty of materials • Welding robotization and automation in manufacturing • Welding instruction • Artificial intelligence and computer technology in welding • Weld sensor systems • Arc stability and metal transfer • Brazing, soldering and associated nonarc joining processes

Individuals interested in making a presentation should prepare a short abstract and include the name and address of the author(s), and title of paper. Send it by mail or FAX, no later than February 15, 2001, to JOM Institute Secretariat, Klintehoj Vaenge 21, DK-3460 Birkerod, Denmark; FAX 45 45 94 08 55; e-mail [email protected]


A W S Peer Review Panel All papers published in the Welding Journal's Welding Research Supplement undergo Peer Review before publication for: 1) originality of the contribution; 2) technical value to the welding community; 3) prior publication of the material being reviewed; 4) proper credit to others working in the same area; and 5) justification of the conclusions, based on the work performed. The following individuals serve on the AWS Peer Review Panel and are experts in specific technical areas. All are volunteers in the program.

D. Abson D.L. Hallum D. K. Aidun I.D. Harris D. G. Atteridge D.A. Hartman R. E. Avery R.T. Hemzacek S. S. Babu M.J. Higgins D. J. Ball T. Hikido W. L. Ballis J .E. Hinkel R Banerjee J. E Hinrichs T. S. Bannos T. R Hirthe R. E. Beal E Hochanadel F. R. Beckman D.G. Howden S. S. Bhargava E Howe B. Bjorneklett C. Hsu O. Blodgett J. R Hurley R. J. Bowers D.L. Isenhour J. E. M. Braid J .R. Jachna K. L. Brown J. Jaeger S. B. Brown B.A. Jones J. Bundy J .E. Jones S. N. Burchett W. Kanne M. L. Callabresi B. Kapadia D. A. Canonico A. Kar K. W. Carlson D.D. Kautz N. M. Carlson H.W. Kerr C. L. Chan D.S. Kim Y. J. Chao J. E King C. C. Chen S. Kolli J. C. Chennat P.J. Konkol B. A. Chin S. Kou G. E. Cook J.J. Kozelski R. E. Cook H.G. Kraus R. A. Daemen K.W. Kramer S. Daniewicz J.J. Kwiatkowski J. C. Danko E Lake J. DeLoach J .D. Landes G. den Ouden J.W. Lee X. Deng A. Lesnewich E J. Ditzel G.K. Lewis R. J. Dybas M.V. Li H. W. Ebert T.J. Lienert G. M. Evans M.J. Lucas R. G. Fairbanks R.O. Lund D. A. Fink K.A. Lyttle D. W. Fitting B. Madigan W. R. Frick M.C. Maguire E. Friedman A.K. Majumdar Y. R Gao M. Manohar J. A. Gianetto A. E Manz E E. Gibbs K. Masubuchi E Hall S.L. Mayers

Principal Reviewers

Y. Adonyi W. E Gale K.W. Mitchiner C. E. Albright J.M. Gerken E E. Murray J. A. Brooks D.D. Harwig T.M. Mustaleski H. R. Castner D. Hauser D.L. Olson M. J. Cieslak G.K. Hicken B.M. Patchett M. J. Cola J.E. Indacochea M.A. Quintana C. E. Cross J.L. Jellison T.P. Quinn C. B. Dallam M.Q. Johnson A. Rabinkin B. Damkroger R.R. Kapoor B. Radhakrishnan V. R. Dav~ T.J. Kelly W.G. Reuter S. A. David G.A. Knorovsky R.W. Richardson T. DebRoy D.J. Kotecki J. E Saenger J. H. Devletian R. Kovacevic M.L. Santella R. D. Dixon E V. Lawrence, Jr. S.D. Sheppard P. Dong W. Lin H.B. Smartt J. N. DuPont J.C. Lippoid B.R. Somers T. W. Eagar S. Liu D.J. Tillack G. R. Edwards H.W. Ludewig C.L. Tsai J. W. Elmer R.P. Martukanitz G.D. Uttrachi D. E Farson R. Menon D.R. White Z. Feng S.J. Merrick T. Zacharia S. R. Fiore R.W. Messier, Jr. Y. Zhou L. H. Flasche D.W. Meyer P. W. Fuerschbach J.O. Milewski

J. Mazumder N. Potluri D.W. Trees V. E. Merchant M. Prager A.J. Turner M. T. Merlo D.D. Rager J.J. Vagi W. C. Mohr K. E Rao T.L. VanderWert A. J. Moorhead W. Ridgway I. Varol T. Morrissett A. Ritter R T. Vianco L. W. Mott M.N. Ruoff K.K. Wang C. G. Mukira D.J. Rybicki D.K. Watney K. Mundra E. E Rybicki M.M. Weir O. Myhr K. Sampath C.E. Wirsing K. Nagarathnam J.M. Sawhill, Jr. C.E. Witherell R Nagy A. R Seidler W.E. Wood S. Nasla L.R. Shockley J. Xie T. W. Nelson L.E. Shoemaker Y. E Yang J. L. Novak M. Sierdzinski H. Zhang A. Ortega T.A. Siewert J. Zhang M. Parekh S.D. Smith S. Zhang R. A. Patterson T.M. Sparschu Y.M. Zhang R. L. Peaslee W.J. Sperko D. D. Peter D.E. Spindler E. Pfender J .E. Stallmeyer M. Piltch R.J. Steele L. E. Pope R L. Sturgill

92 I FEBRUARY 2001

W E L D I N G R E S E A R C H

SUPPLEMENT TO THE WELDING JOURNAL, February 2001 Sponsored by the American Welding Society and the Welding Research Council

A Fuzzy Logic System for Process Monitoring and Quality Evaluation in GMAW

Monitoring weld quality in real time is proposed using voltage and current for raw data to develop graphic histograms

BY C. S. WU, T. POLTE A N D D. REHFELDT

ABSTRACT. This paper introduces a fuzzy logic system that is able to recognize common disturbances during automatic gas metal arc welding (GMAW) using measured welding voltage and current signals. A statistical method was employed to process the captured transient raw data, and the probability density distributions (PDDs) and the class frequency distributions (CFDs) were obtained. Based on the processed data (PDD values of welding voltage and current and CFD values of the short-circuiting time), the system automatically generates fuzzy rules and membership functions of linguistic variables, conducts inference and defuzzification, and completes the evaluation process without further expert knowledge.

Introduction

Gas metal arc welding (GMAW) is widely used in industry. The process's high metal deposition rate makes it well suited to automatic and robotic welding. Monitoring weld quality in real time is increasingly important since great financial savings are possible, especially in manufacturing where defective welds lead to losses in production and necessitate time-consuming and expensive repair (Ref.1). The task of a weld monitoring system is to use captured signals to classify a weld into defective or nondefective groups. The internal signals of the welding process such as welding voltage and

C. 5. w u is with 5handong University of Technology, Jinan, China. T. POLTE and D. REHFELDT are with the University of Han- hover, Hannover, Germany.

current, as well as external signals such as CCD camera output, can be used as variables. However, external sensors are expensive and restrict the mobility and flexibility of automated GMAW systems. By comparison, welding voltage and current are inherent process parameters and are easy to measure. Moreover, their curves reflect many peculiarities of the welding process in their shape. Each kind of arc welding process is characterized by certain shapes of the welding voltage and current typical for the process (Refs. 2, 3). Any disturbances or occurrences of faults during welding inevitably result in variation of these curves to some extent. Therefore, quality assurance in GMAW may be achieved through examining welding voltage and current.

To predict the quality of a weld joint, it is essential to process and evaluate the captured raw data. The raw voltage and current signals are not enough for weld process monitoring (Ref. 4). A method should be found to process and evaluate precisely the stochastic and nonlinear arc welding process. Statistical methods are effective in dealing with stochastic processes. The commonly used parame-

KEY WORDS

Fuzzy Logic Weld Process Monitoring Weld Quality Monitoring GMAW Weld Process Control

ters for process monitoring are the mean values and the standard deviations of welding voltage and current (Ref. 4). But these values are not sufficient to the tasks of process monitoring and quality evaluation because they are just some numbers, not fully representing or depicting the actual dynamic behavior of the process. The description of a stochastic process is possible by means of the probability density distributions (PDDs) and class frequency distributions (CFDs). The principle is to distribute the frequency of the sampled values, e.g., different welding voltage values, into discrete classes. A graphical representation of such distributions are histograms (see Appendix). This approach involves a massive data reduction, but the essential process information is retained.

The commercially available Analysator Hannover XV (AH XV) was used to measure and calculate the PDDs of the transient welding voltage and current signals during a welding process (Ref. 5). Further- more, CFDs of the process time signals are derived from the transient voltage. Each welding process has its own characteristic ("fingerprint") PDDs and CFDs. However, comprehensive expert knowledge is required to recognize and distinguish process disturbances and faults through evaluating the PDDs and CFDs of the welding process. If the evaluation is automatically carried out based on the PDDs and CFDs, it will be of great significance for industry applications. To this end, artificial intelligence methods, such as fuzzy logic and neural networks, should be applied. This paper introduces a fuzzy logic system for GMAW process monitoring and quality evaluation.

WELDING RESEARCH SUPPLEMENT J 33-s

Pot~er E $ OU fOlt

Shun t or

Ha l l Sensor

Fig. 1 - Experimental setup•

0.01

0.001

0.0001

l o o .................. T .................................... T .......................................................... t ~ [ i ~ - - Undisturbed : - ' r + +

10 ............... ~ ............. + ' ';. ............... ¢ ................... "f .................. t ................... i . . . . D i s t u r ~ ' - # 1 i i : . , . i i i

1 ~ Disturbance-#2

0.1 ~i • :i i i

........... .............. i ................... + . . . . . . . . . . . i

................ + ................... j ............. %+ ......................... + ...................

+ [ • v ' ~+ , . ~ +

I 0 2 0 3 0 4 0 3 0 6 0

u ( v )

Fig. 2 - - PDD of weld ing voltage.

l

o.1

0.01

0.001

0 . 0 0 0 1

too [ ................ ; ................... ; ................... i ................. T .................. i I I I I I

0 [ + , l i ,

: I I I I I . . . . . : . . . . . . . . . . . . . . . . + .................. 4 .................. 4 .................. l

: I I I : ~ - , - . 4 l I

.... : . . . . . +." ' t~ ............... I .............. I • : " ' . I ~ I I : , " -J ! I I "~- . . . . . . . . . f.~,.Ir ............ '+ .................. 4

+ i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

• i

~ J . 1 1 . , I . . . . l . . . I l l . . i l l . ! . . . . 1

0 lO0 200 300 400 500

I (A)

-- Undi~rb~l

-- . Disturbance-# 1

• . . Disturbance-#2

100.0 [ - - -

r

• ) .0 - -

0

i/ . - - , - - - , - - - , - - - , - - - , - - - ,

I I I I I f

• I I I i I • %t I I I I I

• ~ I I I [ I I I I I I _ . , , . . . - - - . - - - . - - - . - - - .

F "~ 11 I I I I

; ~1 I I I I . t f . : i I I I

# ~ : I I I I

; t I I I / , ~ ~ ~ , , ] I f l ",1 I I I # I l~ Y. I I I

l' t I I I

3 4 5 6 7 8

T1 [ms]

- - Undisturbed

..... Disturbance-# 1

• . . Disturbance-#2

Fig. 3 - - PDD o f weld ing current. Fig. 4 - - CFD o f short-circuit ing time.

M e a s u r e m e n t a n d E x p e r i m e n t a l

M e t h o d

Constant-voltage GMAW experiments were performed with a fully mechanized and computer-controlled welding system• The base metal was 1-mm-thick steel• Shielding gas was 18% CO 2 and 82% Ar with a flow rate of 12 L/min. The wire electrode was 1-mm-diameter SG 3 (equivalent to AWS A5.18-79: ER70S-G). Wire feed rate was set to 4.0 m/min. Welding speed was 76 cm/min, mean welding current was approximately 130 A, and welding voltage was set at the power source to 18 V. Welding was done on a lap joint, which is commonly used in the automotive industry•

Figure 1 shows the experimental setup. The AH XV was used to measure the transient data of the welding voltage and current and to process them into PDDs of welding voltage u and current i and CFDs of short-circuiting time T 1 and arc-burning time T 2.

The AH XV consists of an industrial PC (Intel ® Pentium CPU) with a high performance ADC board and the processing software. A Hall sensor was used to monitor the welding current. The voltage drop between the torch contact tip and the

workpiece was processed by a low pass filter (LPF) and a voltage divider. Each channel was sampled at 100 kHz with a resolution of 12 bits. The software ran under the Microsoft Windows ® 95/NT 4.0 operating system.

In this experimental investigation, 48 welding tests were carried out. Undis- turbed and intentionally disturbed welding experiments were evaluated• The disturbances were as follows:

1 ) Increasing the wire feed rate 2) Decreasing the wire feed rate 3) Increasing the gas nozzle diameter 4) Welding over two sheets 5) Welding over a lap joint with a

clearance between the upper and lower sheets

6) Workpiece surface with some oil 7) Welding over a lap joint with the

upper sheet having a cut in the middle. Figures 2 and 3 show the PDDs of

welding voltage and current. Figure 4 shows the CFDs of short-circuiting time.

A u t o m a t i c E v a l u a t i o n

Figures 2-4 show the differences between the disturbed and the undisturbed experiments, but there are obvious differences between both types of experiments.

Expert knowledge and skill are required to reliably recognize and distinguish the PDDs and CFDs of the GMAW experiments. For a quality prediction without an expert, especially for quality prediction in production lines, automatic evaluation methods have to be developed• A possible solution for this is the implementation of neural networks, fuzzy logic or combi- nations of both. This paper concentrates on a fuzzy logic system. Figure 5 shows the principle of the system•

Basic D e s i g n o f F u z z y Logic Sys tems

To solve a problem based on uncertain or fuzzy observations or correlations, it is necessary to describe, map and process the influencing factors in fuzzy terms and to provide the result of this processing in a usable form. These requirements result in the basic elements of a knowledge-based fuzzy system - - Fig. 5. The numeric values of the input variables are transformed into memberships of fuzzy sets by fuzzifying. This information, together with the declared rules, is given to the inference engine, the results again being a set of memberships of fuzzy sets (terms for the output variables). The last step is to transform these mem-

34-s I FEBRUARY 2001

bership values into the required scalar variables by defuzzifying.

Linguistic Variables As shown in Fig. 5, the developed

fuzzy logic system works mainly with the PDDs and CFDs, which can be repre- sented as n-dimensional vectors on discrete working computers. For the PDD of welding voltage, the whole range of voltage (0.125-60.125 V) is discreted into 121 classes, and the class width is 0.5 V. For the PDD of welding current, the whole range of current (0-451.172 A) is classified as 232 classes, and the class width is 1.95 A. For the CFD of short- circuiting time T 1 and arc-burning time T2, the whole range of 0-19.75 ms is divided into 40 classes and the class width is 0.5 ms. If all values are used, the total number of input variables will be 433. Because each variable has 5-7 terms and a membership function, too many input variables would be prohibitively time- consuming and cause great difficulty in rule-generation and inference, making the problem unsolvable. Thus, additional data processing is necessary to reduce the values of PDDs and CFDs further.

After careful examination of the PDD and CFD curves, it was found that process disturbances affect the PDD curves of both welding voltage and current more markedly in some ranges. For the PDD of welding voltage, there are four sections with this characteristic, and two sections for the PDD of welding current. Thus, the voltage PDD values of every class are added together for the following four ranges of welding voltage: 0.125-4.625 V, 12.125-20.125 V, 20.625-35.125 V and 35.625-60.125 V, respectively. Then four sums SU1, SU2, SU3 and SU4 are obtained. Similarly, the current PDD values of every class are summarized within the following two ranges of welding current, 21.484-99.609 A and 234.375-351.563 A, respectively, and two sums SI1 and SI2 are obtained. For the CFD of short- circuiting time, all CFD values of every class are added together within the range 0-19.75 ms to produce a sum ST1. There- fore, seven values, i.e., SU1, SU2, SU3, SU4, SI1, SI2 and ST1, are available. These values contain the essential information on the PDDs and CFDs in a definite integral way. Each specific welding process should be characterized by seven values of its own. They are the input variables for further processing.

In this research, seven disturbances were made intentionally during GMAW processes. The developed fuzzy logic system should be capable of recognizing and distinguishing them. The output vari-

L[ Welding - ~ Process Welding l voltage & current

Data Processing

Input Variable Vector (SUI, SU2, SU3, SU4, SUS, SI1, SI2, ST1)

Evaluation Result

Fig. 5 - - Block diagram o f the fuzzy logic system.

Table I - - The Linguistic Variables and Their Terms

Linguistic Input/ variables output

SU1 input SU2 input SU3 input SU4 input SI1 input SI2 input ST1 input ER output

T e r m s

(E_Low, V_Low, Low, Mid, High, V_High, E_High) (E_Low, V_Low, Low, Mid, High, V_High, E_High) (E_Low, V_Low, Low, Mid, High, V_High, E_High) (E_Low, V_Low, Low, Mid, High, V_High, E_High) (E_Low, V_Low, Low, Mid, High, V_High, E_High) (E_Low, V_Low, Low, Mid, High, V_High, E_High) (E_Low, V_Low, Low, Mid, High, V_High, E_High)

(Norm, DT_I, DT_2, DT_3, DT_4, DT_5, DT_6, DT_7)

Notes: 1 ) E_Low = extremely low, V_Low = very low, Low = low, M id = medium, High = high, V_High = very high, E_High = extremely high. 2) Norm = normal weld ing condi t ion wi thout any disturbance, DT_I = disturbance No. 1, and so on.

able is the evaluation result that is abbre- viated to ER. Table 1 gives the terms of input and output linguistic variables.

Rule Base

The rule base includes "If-Then" rules, where the premise is a function of the input variables, and in the conclusion there are only terms referring to the output variable. Generalizing rules were used here, which means that not all input variables are necessarily combined in one premise. In this research, the software package WlNROSA (Ref. 6) was applied for automatic generation of relevant fuzzy rules on the basis of measured and processed data. This method needs to define the linguistic values for the "If" clause, as well as for the "Then" clause. For input variables, a data file can be es-

tablished after a series of GMAW experiments. Since this is a diagnosis problem, the evaluation result is whether a GMAW process is normal or disturbed. More- over, it also indicates the type of disturbance in the case of the disturbed condition. The output variable has no definite values, so different digits are attributed to the output variable ER. For example, a value 1 of ER is related with the normal welding condition without any disturbance. If the evaluation result ER is 2, it means the process is disturbed and the disturbance type is No.l, and so on. Now both the input variables and output variable have values so that a data file is set up. Table 2 is such a data file used for automatic determination of membership functions for input and output variables and rule generation.

Figure 6 illustrates the rule-generation

W E L D I N G RESEARCH SUPPLEMENT I 35-s

[

0.6 0.2 0.7

.8

Fuzzy learning data ] r Fuzzy 1

~, hypotheses / ~ Significant fuzzy "~ 0.9 0.0...[0.5 0.3... , J ,l Rules with rating J

1

0.1 0 . 3 . . . 1 0 . 2 0 . 1 . . . / ~ Lindice~ J ( 1 0.8 0.1 .-[0.3 0.2 . . . [ F...ThEN... / " J Finalrule 0.1 0.3...10., 0.6...1~...~... ( ' ~ o,, ~ kb~ 03 01 106 05 /IF..THEN / . . . . . . . ~

. . . . . . . . . . 1 l IF . . .THEN. . . 0.77 ( 1 IF...THEN... / I IF...THEN...0.91

J / IIF...THEN... 0.56 l / IF...THEN... / I IF...THEN...0.89

~ W . . . T ~ N . . . o.51 ~ m .,~ - '~ I w.--~aE~...°.86

Fig. 6 - - Principle of rule generation.

~ 0 . 5 II

, ~- - -~ . - -3- - -~-

t l :.i ~: i . . . . . . . . - I - - - ~ . . . . . t---~ • I r : i~ : .:t ' - t ! l ,

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~ i

i - - ~ . . . . . . . . . .

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- - E L o w

. . . . V L o w

- . - Low

- - Mid

- , . H i g h

- . . V_H/gh

- , . E _ H i g h

Fig. 7 - - Membership function of the input variable 5UI.

Table 2 - - The Data File for Automatic Rule Generation

Test No. SU1 SU2 SU3 SU4 SI1 SI2 ST1 ER

1-1 14.893 59.565 24.330 0.018 59.596 0.767 70.8 1 1-2 15.194 60.282 23.164 0.022 58.610 0.638 74.1 1 1-3 15.076 59.889 23.842 0.019 58.792 0.948 72.4 1 2-1 14.859 63.186 21.003 0.022 54.166 0.282 82.4 2 2-2 14.932 63.340 20.888 0.019 55.632 0.154 82.6 2 2-3 14.461 63.289 21.324 0.022 56.833 0.185 79.4 2 3-1 8.591 7 7 . 7 0 1 11.670 0.008 72.117 5.330 33.7 3 3-2 10.600 73.495 14.365 0.010 68.196 4.307 43.2 3 3-3 9.963 75.685 12.790 0.008 69.989 5.418 37.9 3 4-1 17.902 36.225 44.717 0.008 61.499 0.988 80.4 4 4-2 17.589 37.418 43.611 0.005 64.147 2.091 72.6 4 4-3 17.484 35.469 45.750 0.006 64.074 1.099 77.0 4 5-1 15.203 57.728 25.825 0.025 59.295 0.670 74.2 5 5-2 15.120 58.999 24.728 0.023 59.474 0.637 72.8 5 5-3 15.138 58.987 24.585 0.021 59.941 0.333 75.6 5 6-1 16.921 55.653 26.065 0.018 50.859 1.159 84.3 6 6-2 16.216 58.280 24.068 0.017 52.286 0.946 80.2 6 6-3 16.980 56.376 25.412 0.019 49.794 0.875 85.8 6 7-1 11.705 64.920 21.835 0.026 70.517 0.115 58.2 7 7-2 13.091 61.390 23.753 0.025 66.459 0.122 65.7 7 7-3 14.000 62.208 22.593 0.025 63.516 0.546 66.8 7 8-1 16.169 60.940 21.741 0.020 58.692 0.710 75.1 8 8-2 16.335 60.076 22.470 0.016 58.813 0.576 75.7 8 8-3 15.740 62.827 20.496 0.017 58.773 0.282 76.4 8

pr inc ip le of WlNROSA (Ref. 6). The recorded data of the process are the learning data, which are the basis for action. First of all, hypotheses in the form of "If-Then" rules are generated. They describe possible dependencies between the input and output variables of the GMAW processes. For the case of a small search space, all possible hypotheses are considered, wh i le for cases of larger search space, only certain preferred promising hypotheses are generated with the help of the search method. Every single hypothesis is checked for relevance and evaluated with a rating index between zero and one, which shows how good the rule is confirmed by the learning data. Only those rules that pass the relevance test are taken into the rule set. The result of the rule generation is a set of relevant rules. As this set mainly consists of generalizing rules, a multitude of coverings and confl icts can occur. Though this would be solved by inference and defuzzification in a fuzzy system, it is more useful to reduce these rules in advance to obtain a rule base that is as small as possible. This leads to more transparency and to shorter computing time. The way of solving conflicts can be adapted to the problem by choice of reduction methods and their parameters.

The membership functions of all l in- guistic variables are generated automatically. Triangle membership functions with vertices of a membership degree of 0 and 1 are selected. Figure 7 shows a membership function of the input variable SU1.

After the whole process of rule generation is completed, the rule base consists of 399 rules in all. A few examples of rules are listed below.

If SU2 is V_High and SI1 is V_High and ST1 is V_High, then ER is DT_7 (certainty factor 1.0).

IfSU1 is Low and SI1 is High and ST1 is Mid, then ER is DT_3 (certainty factor O.99).

If SI1 is V_High and SI2 is V_Low and ST1 is V_High, then ER is DT_4 (certainty factor 0.95).

The rules and membership functions are automat ical ly generated by WIN- ROSA. For further processing they are imported to the DataEngine ® (Ref. 7), a software tool for intell igent data analysis, which includes a fuzzy module. After selecting the inference and defuzzification methods, the evaluation results wi l l be obtained.

Inference Engine

Forward chaining is used in the inference process of the knowledge-based fuzzy system. The given facts (i.e., the membership values of the input variable terms) are analyzed and new statements

3 6 - s J FEBRUARY 2001

derived (i.e., the rule conclusion terms). An inference step (the evaluation of a rule) consists of three steps. Experiment

1 ) Aggregation. Aggregation is the cal- Run No. culation of the fulfillment of the whole rule, based on the fulfillments of the in- 1-4 dividual premises. This process generally 1-5 corresponds to the logic and operator of 1-6 the individual premise expressions. This 2-4 connection can, in principal, be carried 2-5 out using any of the following operators: 2-6 Minimum, Maximum, Algebraic prod- 3-4 uct, Algebraic sum, and Gamma-opera- 3-5 tor. In this research, the test results 3-6 demonstrate that the evaluation result is 4-4 of higher accuracy if the algebraic prod- 4-5 uct pA(x) • laB(X) is employed as the ag- 4-6 gregation operator. 5-4

2) Implicat ion. Implication based on 5-5 the certainty factors calculates the corre- 5-6 sponding degree of certainty for the conclusion. This is called the degree of ful- 6-4 fillment. This step represents the 6-5 conclusion of the logic statement, "If A, 6-6 then B." Implication is the connection 7-4 between the certainty factor and the de- 7-5 gree of fulfillment, the results being the 7-6 degree of fulfillment of each of the con- 8-4 clusions. The algebraic product is used 8-5 here as the implication operator. 8-6

3) Accumu la t ion . In knowledge- based systems, often more than one rule leads to the same conclusion. If the conclusion of a rule has a degree of fulfillment of 0.7, but 0.3 with another rule, then the different degrees of fulfillment need to be summarized in just the one. This is achieved by a process of accumulation, which corresponds to unifying individual results with the logical "Or" operator. In the developed fuzzy logic system, the algebraic sum pA(x) + laB(x) - pA(x) • pB(x) is used as the accumulation operator.

Defuzzifying

The results of the inference process must be translated from fuzzy logic (membership of terms of the linguistic variables) into (crisp) values, in other words, a concrete evaluation result. This is done by defuzzifying. Seen mathematically, the result of the inference process is a fuzzy set for the output variable. This set of fuzzy output has a membership function calculated from membership functions and the degree of membership of the different terms. The task of the actual defuzzifier is to transform the membership function of the fuzzy output set into a crisp result. In this work, the mean of maxima is used as the defuzzifying method.

Results and Discussion

GMAW experiments were conducted under eight conditions, i.e., one normal

Table 3 - - Evaluation Results

Welding Conditions

Normal welding

Welding over two sheets

Welding over two sheets with a gap between two sheets

Workpiece surface with some oil

Welding over an overlapped joint with the upper sheet having a cut

Increasing wire feed rate

Decreasing wire feed rate

Increasing gas nozzle diameter

condition without any disturbance and seven conditions with intentional disturbances. For each condition, six welding experiments were carried out. The first three experiments were used to generate fuzzy rules, and three additional experiments were used to test the system. As shown in Table 3, for all 24 experiments tested, the developed fuzzy logic system can automatically recognize 22 cases. The correct recognition rate is 92%.

It should be pointed out that this work is only the initial step for weld process monitoring using the welding voltage and current signals. The so-called 92% correct recognition rate only corre- sponded to the available 48 GMAW experiments (24 for training, 24 for testing). Greater efforts are being made for further research and improvement of the fuzzy system. For one thing, the system will be modified to improve the fuzzy system. Also, the system will be modified to distinguish the process signal's variation caused by disturbances from that caused by an intentional weld schedule. For example, as a robot welds around a corner, the travel speed and the wire feed rate are often intentionally decreased. This changing of process signals is usually known in advance during the welding robot's programming phase so relevant information can be provided to the fuzzy system. Moreover, a large amount of GMA welding trials will be carried out to

Attributed The System Is the Evaluation Code Output Results Correct?

1 0.98 Yes 1 6.00 No 1 0.98 Yes

2 2.00 Yes 2 2.00 Yes 2 2.00 Yes

3 3.01 Yes 3 3.01 Yes 3 3.01 Yes

4 3.97 Yes 4 3.97 Yes 4 3.97 Yes 5 4.99 Yes 5 7.02 No 5 4.99 Yes

6 6.00 Yes 6 6.00 Yes 6 6.00 Yes

7 7.02 Yes 7 7.02 Yes 7 7.02 Yes 8 7.98 Yes 8 7.98 Yes 8 7.98 Yes

obtain more data for sufficiently training the fuzzy system.

Conclusions

The AH XV, fuzzy logic system for process monitoring and quality evaluation in GMAW has been developed. It is used to measure transient welding voltage and current and to process them into PDDs and CFDs during GMAW experiments. The PDDs of welding voltage and current, as well as the CFD of short- circuiting time, are decomposed into several ranges within which the corresponding PDD values or CFD value of every class are summarized in a way that seven input variables are obtained. The measured data are further reduced, but the essential process characteristics remain. The WlNROSA method is applied for automatic generation of linguistic terms, membership functions and relevant fuzzy rules on the basis of the processed experiment data. The rule base containing 399 "If-Then" rules with certainty factors are imported to an intelli- gent data analysis tool named DataEngine, which conducts inference and defuzzification processes so the evaluation results can be obtained.

The system is able to recognize and classify disturbed and undisturbed GMAW experiments. The entire evaluation process can be carried out automat-

W E L D I N G RESEARCH SUPPLEMENT I 37-s

Class Frequency DistribuSon N [11s]

1 O0 : ~ la t i d ' i o s

Mean Vdue

~tandard Deviation

"v'a'i ation CoMfioignt

Number of Events

Signal Evaluation

R'obability ginsity Transient 9gnal Di~ribution

. . . . . .,,-~ @ u vJ i i i i

i i i i o

f - ~ ~ . . . . . _ n__ , l . . l _ o

,, , ,-

i0 2Q qn 40 ~0 QO ?.0 QO Q 0 - - " - m n~,~ ~ ~.~.

la ~ o" - . tiros]

Oat,= Reduction

Fig. 8 - - Principle of determining voltage PDD.

10-

1 "

0 , 1 -

0,01

i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

I . . . . . . . . . . . r . . . . . . . . . . i i i i

I I i i

_ ! . . . . . . . i .

2 4 6 Short-Circuiting Time T1 [ms]

[] undisturbed • disturbed

Fig. 9 - - An example of short-circuiting time CFD.

ically by examining only measured welding voltage and current.

Acknowledgment

The authors gratefully acknowledge support for this project from the DAAD Re- search Fellowship program of Germany.

References

1. Rehfeldt, D., and Schmitz, T. 1994. A system for process quality evaluation in GMAW. Proc. the Int. Conference Advanced Techniques and Low Cost Automation, pp. 227-234, Inter- national Institute of Welding, Beijing, China, International Academic Publishers.

2. Rehfeldt, D., and Polte, T. 1999. Moni- toring systems: algorithms and systems presented at recent welding conferences. IIW- Doc. XIl-1598-99.

3. Adolfsson, S., Bahrami, A., Bolmsj6, G., and Claesson, I. 1998. Quality monitoring in robotized spray GMA welding. Int. J. for Join- ing of Materials 10(1 ): 3-23.

4. Quinn, T. P., Smith, C., McCowan, C. N., Blachowiak, E., and Madigan, R. B. 1999. Arc sensing for defects in constant-voltage gas metal arc welding. Welding Journal 78(9): 322-s to 328-s.

5. Rehfeldt D., and Polte, T. 1999. Three systems for process monitoring, process analysis and quality determination in arc welding. Proc. Int. Conference on Joining of Materials, pp. 277-283, JOM-9, Denmark.

6. MIT GmbH. 1998. WlNROSA user manual. Aachen, Germany.

7. MIT GmbH. 1997. DataEngine overview and user manual. Aachen, Germany.

A p p e n d i x

Probability Density Distribution (PDD) and Class Frequency Distribution (CFD)

The principle of determining the PDD is to distribute the frequency of the sam-

pied values, e.g., different welding voltage values, into discrete classes. Figure 8 shows the PDD of welding voltage from a welding trial under short-circuit ing GMAW conditions. During the welding process, the transient signal of welding voltage is captured and digit ized. For these large masses of raw data, it is useful to distribute them into classes and to determine the number of measured values of the voltage belonging to each class, called the class frequency. The whole range of welding voltage is divided into many classes, such as 0-0.5, 0.5-1.0, 1.0-1.5 ... . . 60-60.5 V. A symbol defining class such as 0.5-1.0 V is called class interval. The difference between the lower and upper class limits is called class width. Regarding the above example the class width is equal to 0.5 V. A tabular arrangement of data by classes with the corresponding class frequencies is called a frequency distribution, or frequency table. Table 4 is an example of frequency distribution. The relative class frequency is the frequency of the class divided by the total frequency of all classes and is generally expressed as a percent- age - - Table 4. A general representation of a frequency distribution is the histogram - - Fig. 8. A histogram consists of a set of rectangles with centers at the class marks (the midpoint of the class interval) and widths equal to the class interval size and areas proportional to class frequencies. If all the rectangles have the same width, then their heights are proportional to the corresponding class frequencies, and it is then customary to take the heights numerically equal to the class frequencies. The frequency scale can be relative frequency or logarithmic frequency in histograms. Figure 8 is the scale in logarithmic frequency.

In addition to the amplitude, a time analysis in short-circuiting welding is also valuable. There are two important

Table 4 - - Example of the Welding Voltage Frequency Table

Voltage Frequency Relative Classes (Number Class (V) of events) Frequency

(%)

0.5-1.0 0 0.0 1.0-1.5 1 1.2 1.5-2.0 3 3.6 2.0-2.5 11 13.2 2.5-3.0 22 26.4 3.0-3.5 15 18.0 3.5-4.0 7 8.4 18.0-18.5 31 37.2 18.5-19.0 21 25.2 19.0-19.5 9 10.8 25.0-25.5 0 0.0 25.5-26.0 0 0.0 60.0-60.5 0 0.0

time signals, i.e., the short-circuiting time T 1 and the arc burning time T 2. The CFD of these times are derived from the transient voltage. To determine T 1, count the time or number of samples where the voltage is below a threshold voltage. A counter is running between the transition from arc burning to short-circuiting up to the transgression of the threshold voltage. Different counts (different duration of T 1) determine the distinct classes of the T 1- CFD. For example, a test lasts 5 seconds. If the counted number of short-circuiting time 100-150 microseconds is 88, then the CFD value corresponding to the class 100-150 microseconds is 88/5 = 17.6 (l/s). After determining all CFD values for all short-circuiting time classes, a histogram can be obtained. Figure 9 shows an example for the differences between the undisturbed and disturbed CFD of short-circuiting time.


Effects of Surface Depression on Pool Convection and Geometry in Stationary GTAW

Arc pressure at peak duration produces deep penetration in pulsed current gas tungsten arc welding

BY S. H. KO, S. K. CHOI AND C. D. YOO

ABSTRACT. The effects of surface depression on pool convection and geometry in stationary GTAW are simulated numerically under DC and pulsed- current conditions. Welding current and Marangoni flow affect surface depression and velocity such that inward flow by the current and positive surface-tension gradient acts to decrease surface depression. Arc pressure is found to be a major factor in surface depression and in fluctuations of free surface and flow velocity. While arc pressure at the low current range has negligible effects on surface depression and pool geometry, it should be considered in the high current range. Under the pulsed current condition, deep penetration is produced mainly by arc pressure at peak duration. The solid- liquid interface profile at the pool center and periphery becomes similar to that of peak and base current, respectively, and penetration is closely correlated to surface depression.

Introduction

Because weld pool convection was found to have significant effects on the bead width and penetration in arc welding (Ref. 1), extensive research has been undertaken to reveal the relationship between pool convection and geometry (Refs. 2-10). Among the various factors affecting pool convection, electromagnetic force and surface-tension gradient are the most important. Because the electromagnetic force generates circulation within the molten pool in a downward direction, penetration increases by pool convection. The rotating direction of Marangoni flow depends on the surface- tension gradient, which is affected by minor elements such as sulfur composition in the base metal. These convection patterns with heat input from the arc determine pool geometry.

S. H. KO and C. D. YO0 are with the Depart- ment of Mechanical Engineering, KAIST, Tae- ion, Korea. S. K. CHOI is with the School of Mechanical Engineering, Kyungpook National Univ., Taegu, Korea.

Numerical methods have been employed to predict pool convection, and the calculated pool geometry was in agreement with the experimental result (Refs. 2, 5). One of the general assumptions made to simplify numerical computation is the molten pool surface is flat (Refs. 2-4). Another assumption of a de- formed surface depression was employed (Refs. 6-8) using the surface profile in an equilibrium state by minimizing the potential energy (Ref. 9). Several attempts were made to include the free surface under the direct current (DC) condition (Refs. 10, 11). While three-dimensional pool geometry was calculated for nonautogenous welding using surface elevation, the effect of arc pressure was not considered (Ref. 10). A numerical model for a full penetration weld with two free surfaces was presented (Ref. 11). Because the focus was the Marangoni effect on a free surface, the effect of the electromagnetic force was ignored and the pool had a cylin- drical shape. Therefore, dynamic effects of surface depression on pool convection and its geometry have not been fully understood under DC and pulsed- current conditions.

In this work, dynamic variations of surface depression and pool convection in DC and pulsed-current gas tungsten arc welding (GTAW) are calculated numerically by employing the Volume of Fluid (VOF) method (Ref. 12). The solid- liquid interface of a molten pool is com- puted by solving the energy equation,

KEY WORDS

Surface Depression Pool Convection GTAW Direct Current Pulsed Current Marangoni Flow Volume of Fluid Method

and the effects of arc pressure, current and surface-tension gradient on surface depression and convection are analyzed based on the calculated results. Causes of deep penetration by the pulsed current are also simulated.

Formulation

Since the effects of a free surface are emphasized in this work, the following assumptions are made in the formulation: 1) fluid flow in the axisymmetric molten pool is incompressible and lami- nar, 2) the effect of the drag force from the plasma jet is neglected, and 3) material properties are constant. The principle of the VOF method for calculating fluid flow with a free surface is described briefly because it was explained in detail in other works (Refs. 8, 12, 13). The solution domain is divided by the staggered grid and the function F is defined to describe the fluid volume ratio within the cell. The governing equations consist of the continuity, momentum equations and an additional equation relating to the function F as follows:

V. V = 0 (I)

=-lvp+vV2 ~ P

(2) P

(3)

where ~ represents the velocity vector, P the pressure, p the mass density, vthe viscosity, Tthe current density, 8 the magnetic flux, [[3 the thermal expansion and Tli q the melting temperature. The electromagnetic and buoyancy forces in Equa- tion 2 are included as the body force.

The energy equation is solved in an implicit manner to calculate the temperature and solid-liquid interface as follows:

WELDING RESEARCH SUPPLEMENT I 39-S

18000 =

16000 Pz=°°

1,00o I I E1~o001 ", \ " \ \ ~1o000-.%.

00oo- ""--.'L \

0 i i i i

1 2 3 4

Radial distance (mm)

Fig. 1 - - Arc pressure distributions on the pool surface.

2 msec 8 msec 16 mse¢

( o ) A r c p r e s s u r e :

110 m s e c 120 mse¢

2 msec 8 msec 16 msec 110 msec 120 m s e c

( b ) A r c p r e s s u r e : P3oo

Fig. 2 - - Surface depression and flow patterns for P1oo and PJoo. (I = OA, y = 1200 dyne/cm).

Table 1 - - Material Properties of Mild Steel Used for Calculation

Mass Density, p Kinematic Viscosity, v Surface Tension Coefficient, y Surface Tension Gradient, dy/dT Electrical Conductivity, ae Permeability, I.to Thermal Conductivity, k Specific Heat, Cp Latent Heat of Fusion, AH Liquidus Temperature, T,q Solidus Temperature, Tso~ Distribution Parameter of Current Density, (~i Distribution Parameter of Heat Flux, aq

7860 (kg/m3) 5.6 x 10-7 (m2/s) 1200 (dyne/cm)

+4.9 x 104 (N/mK) 8.54 x 105 (mho/m)

4g x 10-7 (H/m) 30 (W/mK) 795 (J/kgK) 272 (kJ/kg)

18O9 (K) 1 789 (K) 3 (ram) 3 (mm)

p C p t - ~ + v . VT =kV2T +~tj (4)

where Cp represents the specific heat, k the thermal conductivity and qj the joule heating per unit volume. The latent heat, AH, is considered by increasing the specific heat in the temperature range of phase change as follows:

L~H

C p * - (Tliq_Tsol) ~-Cp,

Tso I < T < Tli q (5)

As for the boundary conditions, the free-slip and no-slip conditions are imposed along the z-axis and on the solid- liquid interface, respectively. The arc pressure of a Gaussian distribution is exerted on the pool surface as shown in Fig. 1,


where P]00, P200 and P300 represent arc pressure at welding current 100, 200 and 300 A (Ref. 11 ). To compare the effect of arc pressure distribution, modified pressures of P100* and P200* are introduced that have the same total arc forces of P100 and P200, respectively. The heat flux and current density from the arc are also described using the Gaussian distribution on the free surface as follows:

/ r2 / q(r) = 2rcc.Texp

q k z~q )

andJ ( r )= ~_/-~_2 exp/- r2 /

where C~q and c~ i denote distribution parameters of heat flux and current density, respectively. Although the distributions of heat flux and current density may vary

with surface depression, they are assumed to be constant because these distributions are not known. Marangoni flow due to the surface-tension gradient, (c~y//3T), is considered by imposing shear stress on the free surface as follows:

o3y o~T

where yand ~ denote the surface-tension coefficient and tangential direction of the free surface, respectively. The SOLA-VOF code written in FORTRAN is modified to include the effects of electromagnetic force and surface-tension gradient.

Results and Discussions

Effects of Welding Parameters under the DC Condition

In order to investigate the effects of the process parameters on surface depression and pool convection, the molten pool is assumed to be a hemispherical shape having a radius of 5 mm without solving the energy equation. Physical properties corresponding to those of mild steel are listed in Table 1 (Refs. 14,15). Initial flow velocity within the molten pool is set to zero. When the pressures of P100 and P300 are exerted on the surface without the current and surface-tension gradient, the calculated free surface profile and flow pattern are like that illustrated in Fig. 2. Small surface depressions and flow velocity are developed at P10o, and they continue to fluctuate until the steady state is reached, which represents

A 1 . 2

'.°lt !! !i • , ! i 0.8 ',li ] , ~i~.

O n ~ . ' ! • I , ~ " 1 ! ~.~ " ~ u . u I I I I*1

!I " i !, i~ .

~ ' 0 4 " ' i h V -o I " l

I ! ' . "t: : : ' I I / " ~ C # J i l l I 1 ~ I ~

0 ,0 - [ -

)

k'~ t,!b'~ ~.,'z':~. , . ' . ' ~ C".-;~-'-"- -'~'.~" ,r,~ ~ ~ , ~ls t' ¢. ~ , ,~ ~ 1 I • I I i f i • ~ I I I 1 I I I I i I

I I I I I I I I I l I i 1 I i I I ! I 1 ~ I i 1 1 I i ! I I I I I I 1

, , . . . . • , j , , , ,

-0.2 I , ,

0.0 0.1 0.2

T i m e ( s e c )

B

8 "

~ o -

-8

0.0

t, :,,1:, : , ! i ', ,. . .

] P ! ' ! i I Il l: | h ~. t ~" I~ ~t~1"~1:. "1 I ! l , ~ ' ! ~ ! , ! , ~ ~c s ~ , ~ J t ' , . i v , ' . ' . , , ' i~ , '

'~ i i ) I! : ' i i ~i i " ~ i i Y " i~ ~ ,

A i

011 0.2

Time (sec)

Fig. 3 - - Effects o f arc pressure on surface depression and axial velocity (I = OA, y = 1200 dyne/cm). A - - Surface depression; B - average axial velocity.

g 1.0

15

hi L : i [ =) ~ =, .. :~ : ~i ! d ! i

r./ 0.0 4 ~ " ......... 100A

/ . . . . . 2 0 0 A ] - - 3 0 0 A

o % o:, o:, o, oo o, °c> e , o, T i m e ( s e c )

Fig. 4 - - Effects o f current on surface depression and axial velocity (P = P2oo, ? = 1200 dyne/cm). A - - Surface depression; B - - average axial velocity.

weld pool oscillation (Ref. 16). With a higher arc pressure of P300, surface depression increases and faster flow velocity is induced.

Variations of surface depression at the surface center and average axial velocity along the z-axis are shown in Fig. 3. As expected, surface depression increases for higher arc pressure. While free surface and flow velocity vibrate periodically for Plo0 and P2o0, the amplitude of P300 decays rapidly with the lapse of time because high arc pressure acts as a re- straint force on surface fluctuation. Since the free surface and axial velocity vibrate at the same frequency, velocity fluctuation is induced by arc pressure.

With the arc pressure fixed to P200, the effect of current on surface depression

and axial velocity is shown in Fig. 4. For the low current of 100 A, surface depression is not affected and is almost similar to the case of 0A in Fig. 3A. When the current increases, surface depression and the amplitude of surface fluctuation decrease. The reason is explained using axial velocity in Fig. 4B. As the electromagnetic force increases with higher current, fast inward flow on the pool surface fills the depressed pool center, which reduces the surface depression and its fluctuation.

To identify the causes of free surface and flow velocity fluctuation, comparisons are made for the cases with P200 and without arc pressure (i.e., P = 0) as shown in Fig. 5. Without arc pressure, the free surface at the pool center rises slightly to

0.1 mm because of the inward flow and the amplitude of surface fluctuation is quite small. When arc pressure of P200 is imposed, surface depression and its amplitude increase significantly. Flow velocity also fluctuates with large amplitude as shown in Fig. 5B, but its magnitude becomes smaller than that of P = 0. It clearly indicates arc pressure is responsible for surface depression and fluctuations of free surface and flow velocity, while current affects flow velocity and decaying of fluctuation.

The effects of surface tension are illustrated in Fig. 6 where the surface- tension coefficients of 1200 and 1800 dyne/cm, fixed arc pressure and current of P20o and 200 A are used for calculation. In this case, the effect of surface-

WELDING RESEARCH SUPPLEMENT ] 41-s

1.0 B 15

"i1° J

b6 i ':"

0.4

0.2

0.0 i ";i "J ; ' ¢ ' - " , : " . " ' , " ' , " ' - " ' " " ' " ' " " " ...................................

- 0 . 2 ' ~ I - ~ ' J ' ' '

O.O 0.1 0.2 0.3 0.4 / . . . . . Time ( s e c ~ J

ig. 5 - - Comparison with and wi thout effects o f arc pressure ( / = 200 A, 7 = 1

i l i i i i il ii ii ii !i " . i

o. i ' : ~ ~ ~ i ',. ".

2 0.0 0.1 0.2 0.2

T i m e ( s e c l T=me ( s e c )

Fig. 6 - - Effects o f surface tension on surface depression and axial velocity (P = P2~ I = 200 A. A - - Surface depression; B - - average axial velocity.

A

- - : lOcm/s

106 msec 112 msec

B

- - : I O c m / s

106 msec 112 msec

Fig. 7 - - Surface profi les and convect ion patterns due to surface-tension gradient (P = P2oo, I = 200 A). A - - dy/dT = -0 .49 dyne/cmK; B - - cty/dT = 0.49 dyne/cmK.

tension gradient is ignored. Surface depression decreases with higher surface tension coefficient as in Fig. 6A because higher pressure is required to deform the pool surface of higher surface tension. However, the axial velocity is not affected by the surface tension coefficient as in Fig. 6B.

When the surface-tension gradients of + .49 dyne/cmK are used with fixed pressure of P200 and current of 200 A, the surface profile and flow pattern are illustrated in Fig. 7. In the case of the negative surface-tension gradient, a double loop circulation is calculated as in Fig. 7A. When the surface-tension gradient is changed to the positive value, Marangoni and electromagnetic flow rotate in the same inward direction, which results in faster axial velocity. These flow patterns are similar to those of previous works


1.0 - - dT/dT---0.4~l~qe/c~K . . . . . . dT/dT= 0.49dyr~/o71K

0.8

0 .4

0 .2

7 t.," ................................................... 0 . 0 ' ' . ,~

0.2 v 0.00 0.05 0.10 0.15 0.20

Time (sec)

B 40 . I - - dT/dT = -0.49 dvne/cmK

. . . . . . . dT/dT = 0.49 dvne/cmK

30" , - -° . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . " ~ , ° ° , % ° , . ° ° ° "

._~ 20" " i ,.

> /

! , o - / /,

° q v

- 1 0 I , • , ,

o.oo o os O.lO o15 Time (secl

0.20

Fig. 8 - - Effects o f sur face-tension g rad ien t on surface depression a n d convec t ion (P = P.,oo, = 2 0 0 A). A - - Surface depression; B - - average ax ia l

velocity.

(Refs. 1-10). Variations of surface depression and axial velocity are shown in Fig. 8. With the negative surface-tension gradient, the pool surface continues to oscillate periodically as in Fig. 8A. Aver- age axial velocity is small because the double loop circulation cancels the axial velocity components along the z-axis. With the positive surface-tension gradient, surface fluctuation decays rapidly and surface depression becomes almost negligible after 0.1 s. This phenomenon by the surface-tension gradient is more pronounced than that by the current in Fig. 5A because the inward flow velocity on the surface becomes much faster than that by the current in Fig. 5B. Therefore, the depressed pool center is filled by the inward flow at a much faster rate.

The calculated results of the flow pattern and solid-liquid interface in the steady state are illustrated in Fig. 9 where the surface-tension gradient o f - 0 . 4 9 dyne/cmK and current of 100 A are used. Comparing the results with P100 and without arc pressure (i.e., P = 0), there is almost no difference in pool geometry because surface depression due to arc pressure is very small. When current and arc pressure are increased to 200 A and P200, surface depression and the resultant penetration increase substantially, as shown in Fig. 10A. Without arc pressure as in Fig. 10B, the effects of surface depression become negligible, and penetration becomes shal- low. Therefore, assumptions of the flat surface and surface depression in a steady state may not be valid in the high current range where the arc pressure and resultant surface depression have significant effects on pool geometry.

The effects of arc pressure distribution are illustrated in Fig. 1 1 where P,00* and P200* in Fig. 1 are used for computation.

A 0 .0 - ( ,

~ 1 .0-

£ ._m 2 . 0 - g N

3.0--

4.0--

5.0

0.0

/ L / / / ' / ~ ' f " % - ' - - "%f T/

B

0.0-

~ " 1.0-

£ .~ 2.0 -

N 3.0--

4.O--

5.0

- - : 10 C m / S

I'O 2'0 3'0 4'o 3'o 1'o 2'0 3'o r ox is ( r a m ) r gx is ( m m )

4'.0 3'.0

Fig. 9 - - F low pat tern a n d so l i d - l i qu id inter face a t l o w cur ren t o f 1 O0 A (dy/dT = -0 . 4 9 dyne/cmK) .

A - - P = P~oo; B - - P = 0.

A 0 . 0 -

"• 1.0-

v

._m 2.O-

N 3 . 0 -

4 . 0 -

5.0 0.0

B 0.0-

1 . 0 -

v .~ 2.0- o N

2.0-

4 . 0 -

l / / / / 4 , -

1 0 #

- - : c m / s

1'o 2'0 2'o 4o' 3'o 3o /o 2'0 ;o 4o' 5to r ox ls ( r n m ) r axTs ( r a m )

Fig. 10 - - F low pat tern a n d so l i d - l i qu id interface at 2 0 0 A (dy/dT = - 0 . 4 9 dyne/cmK). A - - P =

P2oo; B - - P = O.

In the case of P,00*, surface depression and penetration are similar to those of P~00 in Fig. 9A because of low arc pressure. When arc pressure is increased to P200*, deep penetration and narrow pool

radius are calculated. Therefore, if the arc pressure distribution changes in the high current range due to arc length variation or other disturbances, the pool geometry is also influenced.

W E L D I N G R E S E A R C H S U P P L E M E N T I 4 3 - s

A 0.0

1,0-

& 2.0- "~

o

N 3.0-

4.0-

5.0

I / I t , . 0.0-

i 1 .0 -

n 2 . 0 -

3.0--

4.0--

5 .0 -

-- : 10 c m / s

,'.o 2'.0 ;.o 4'.o ~'.o ,.o ,.a ~ . . . . o ,.o r ax is ( r a m ) r ax i s ( r a m )

Fig. 11 - - Flow pattern and sol id- l iqu id interface for mod i f ied arc pressure distr ibutions (dy/dT

= -0 .49 dyne/cmK). A - - P = Pmo*; B - - P = Pz00*.

A

o

b'-r

~- ,0-C Z E

2 .0 - x o N

3.0--

4 . 0 -

-- : 10 c m / s

5.0 0.0 /.o ;.0 ;.0 4'.o ~'.o

r ax i s ( m m )

A

0.C

"~ 1.C

E .~ 2.c o

N 31C

4.C

5.C

-- : 10 c m / s

,'.o ;.o #o 4'.o s'.o r axis ( m m )

S /,/

.~ 2.0- x o

N 3.0-

4.0-

5 . 0 ~ 0.0 1.0 2.0 3.0 4.0 5.0

r ax i s ( m m )

C

o.c

" 1.o-

& .~ 2.0 - u

N 3.0--

5.0 1!0 2t0 3!0 4!0 ' 5.0

r ax i s ( m m )

Fig. 12 - - F low pattern and sol id- l iqu id interface for pulse current (Ip= 200 A, Ib = 100 A, cly/dT = -0 .49 dyne/cmK). A - - fp = 5 Hz, Tp = lO ms; B - - fp = lO Hz, Tp = 20 ms; C - - f p = 2 0 H z , Tp = 10ms.

B l , . . . .

" ~ 1.o-

.~ 2.o- o N

3.°-

I ,o 2!o 3!o 4!o #0 r axis ( m m )

Fig. 13 - - Effects o f arc pressure and heat f lux pulsing on sol id- l iqu id interface (Ip = 200 A, I b = 100 A, f~ = 10 Hz, Tp = 20 ms, dy/dT = - 0 . 4 9 dyne/cmK). A - - On ly arc pressure pulsing; B - - on ly heat flux pulsing.

Effects of Pulsed Current

The effects of pulsed current on pool geometry are illustrated in Fig. 12 where the surface-tension gradient of -0.49 dyne/cmK, the base and peak currents of 100 and 200 A, and corresponding arc pressure of Pro0 and P200 are used for calculation. When the pulsing frequency is 5 Hz and peak duration is 10 ms (average current of 105 A), the penetration in Fig. 12A becomes deeper than that of DC 100 A in Fig. 9A. When the pulsing frequency

and peak duration increase to 10 Hz and 20 ms (average current of 120 A), penetration in Fig. 12B becomes more pronounced and is almost equal to that of DC 200 A in Fig. 10A. The pool radius and penetration at the outer radius are almost the same as that of DC 100 A so the pool geometry becomes similar to a finger shape. When the peak duration of 10 ms and pulsing frequency of 20 Hz are used (Fig. 12C), penetration does not increase to that in Fig. 12B though the average current of 120 A is the same for both cases. It implies that the peak duration is an important factor in determining penetration, and sufficiently long peak duration is needed to provide enough momentum within the molten pool.

To find out the causes of deep penetration under the current pulsing condition of Fig.12B, two cases of pulsing of arc pressure and heat flux are simulated as shown in Fig. 13. The condition of pulsing arc pressure and constant heat flux generates deep penetration similar to a finger shape as shown in Fig. 13A. However, another condition of pulsing heat flux and constant arc pressure becomes similar to that of DC 100 A as in Fig. 13B. These results clearly show deep penetration is produced mainly by pulsing of arc pressure at peak duration rather than by pulsing of heat flux.

The relationship between surface depression and penetration is illustrated in Fig. 14 where pulsing frequency and peak time are 10 Hz and 20 ms, respectively. In this case, arc pressures of P100* and P200* are used for calculation. A close correlation between surface depression and penetration is observed such that the free surface is depressed just after current pulsing and penetration increases rapidly. After peak current, penetration decreases gradually. Peaks of surface depression and penetration coincide up to 0.5 s, because axial momentum by surface depression is delivered immediately in the small weld pool. When the pool size becomes larger after 0.5 s, there is a time delay between the maximum surface depression and penetration because it takes time to deliver axial momentum and heat by convection in the larger molten pool. The experimental verification and effects of temperature-dependent material properties need to be considered in future work.

Conclusions

Surface depression and pool geometry of DC and pulsed-current arc welding are calculated numerically, and the results lead to the following conclusions:

1 ) The free surface of a molten pool is depressed mainly by arc pressure, and in-


0.0 0.2 0.4 0.6 0.8

Time (sec)

Acknowledgments

Fig. 14 - - Relation between surface depression and penetration using P,~* and P2oo* (Ip = 200 A, Ib = 100 A, fp = I0 Hz, Tp = 20 ms, dy/dT = -0.49 dyne/cmK).

ward c i rcu la t ion by the current and Marangon i f l ow decreases surface depression and its f luctuation.

2) Whi le arc pressure in the low current range has negl igible effects on surface depression and pool geometry, the effects of arc pressure and surface depression should be cons idered in the high current range above 200 A.

3) Deep penetration in pulsed current welding is produced mainly by arc pressure at peak duration, and sufficiently long peak durat ion is needed for deep penetration.

The authors ap- prec iate the f inan- c ial support of the POSCO Research In- st i tute and BK-21 project.

References

1. Heiple, C. R., and Roper, J. R. 1982. Mechanism for minor element effect on GTA fusion zone geometry.

1.o Welding Journal 61 (4): 97-s to 102-s.

2. Kou, S., and Wang, Y. H. 1986. Weld pool convection and its effect. Welding Journal 65(3): 63-s to 70-s.

3. Oreper, G. M., Eagar, T. W., and Szekely, J. 1983. Con-

vection in arc weld pools. Welding Journal 62(11): 307-s to 312-s.

4. Zacharia, 1"., David, S. A., Vitek, J. M., and Debroy, T. 1989. Weld pool development during GTA and laser beam welding of type 304 stainless steel, part I - - theoretical analysis. Welding Journal 68(12): 499-s to 509-s.

5. Zacharia, T., David, S. A., Vitek, J. M., and Debroy, T. 1989. Weld pool development during GTA and laser beam welding of type 304 stainless steel, part II - - experimental correlation. Welding Journal 68(12): 510-s to 519-s.

6. Tsai, M. C., and Kou, S. 1990. Electro- magnetic-force-induced convection in weld

pools with a free surface. Welding Journal 69(6): 241-s to 246-s.

7. Kim, S. D., and Na, S.-J. 1992. Effect of weld pool deformation on weld penetration in stationary gas tungsten arc welding. Welding Journal 71 (5): 179-s to 193-s.

8. Choo, R. T. C., Szekely, J., and Westhoff, R. C. 1990. Modeling of high-current arcs with emphasis on free surface phenomena in the weld pool. Welding Jouma169(9): 346-s to 361-s.

9. Lin, M. L., and Eagar, T. W. 1985. Influ- ence of arc pressure on weld pool geometry. Welding Journal 64(6): 163-s to 169-s.

10. Zacharia, T., Eraslan, A. H., and Aidun, D. K. 1988. Modeling of nonautogenous welding. Welding Journal 67(1 ): 18-s to 27-s.

11. Chen, Y., David, S. A., Zacharia, T., and Cremers, C. J. 1998. Marangoni convection with two free surfaces. Numerical Heat Trans- fer, Part A 33: 599-620.

12. Hirt, C. W., and Nichols, B. D. 1981. Volume of fluid (VOE) method for the dynamics of free boundaries. Journal of Computa- tional Physics 39: 201-225.

13. Choi, S. K., Ko, S. H., Yoo, C. D., and Kim, Y. S. 1998. Dynamic simulation of metal transfer in GMAW - - part 2: short-circuit transfer modes. Welding Journal 77(1 ): 45-s to 51 -s.

14. Choo, R. T. C., and Szekely, J. 1991. The effect of gas shear stress on Marangoni flows in arc welding. Welding Journal 70(9): 223-s to 233-s.

15. Brandes, E. A., and Brook, G. B. 1992. Smithells Metals Reference Book, 7th Ed., But- terworth-Heinemann Ltd.

16. Renwick, R. J., and Richardson R. W. 1983. Experimental investigation of GTA weld pool oscillations. Welding Journal 62(2): 29-s to 35-s.

C o r r e c t i o n

Figure 8 as it appears on page 353-s in "A Martensite Boundary on the WRC-1992 Diagram - - Part 2: The Effect of Manganese," by D. J. Kotecki, publ ished December 2000, is a dupl icate of Fig. 7. The correct Fig. 8 appears below. The editors regret this error.

Bend/break results at 10% Mn on the WRC- 1992 Diagram. Compositions that passed the 2T bend test are shown in solid circles. Compositions that cracked during bending are shown as open squares. Between the two parallel heavy lines, some compositions bent and some cracked. Above and to the right of the heavy lines, all compositions bent. Below and to the left of the heavy lines, all compositions cracked in bending

18

16

14

12

10

8

6

4

2

0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Cr Equiv. = %Cr + %Mo + 0.7(%Nb)


Partially Melted Zone in Aluminum Welds Planar and Cellular Solidification

Liquated grain boundaries mostly resolidify with the planar mode but the cellular mode has also been observed

BY C. HUANG AND S. KOU

ABSTRACT. Aluminum Alloy 2219 was gas metal arc welded to study the solidification modes of liquid in the partially melted zone (PMZ), including grain boundary (GB) liquid and liquid spots in the grain interior. GB liquid mostly solidified with the planar solidification mode. The average temperature gradient G across the PMZ was taken as (TL--TE)/Wp, where T, is the liquidus temperature, TE the eutectic temperature and Wp the PMZ width, which was measured with a microscope. The average solidification rate R of the GB liquid was taken as WJts, where WL is the thickness of the GB liquid and ts the solidification time of the GB liquid, which was determined from the measured thermal cycle. The G/R ratio was estimated to be on the order of 10s°C s/cm2, which is close to the minimum G/R required for planar solidification of the alloy. Most GB liquid was too thin to allow enough space for a planar growth front to gradually evolve into a cellular one before solidification was over. Cellular solidification, however, was observed in the PMZ at the bottom of the weld, where G was lowest. It occurred in thicker (15 p,m) GB liquid that had to solidify at a higher R and, hence, lower G/R and more room for cellular solidification to develop. Liquid spots away from the weld were smaller and solidified with the planar mode. Near the weld, however, they grew much larger and had to solidify at a much higher R. Both the lower G/R and the larger space for cellular solidification to develop helped break down planar solidification.

Introduction

Extensive liquation can occur in aluminum alloys during welding in a very

C. HUANG and S. KOU are, respectively, Graduate Student and Professor in the Depart- ment of Materials Science and Engineering, University of Wisconsin, Madison, Wis.

46-S J FEBRUARY 2001

narrow region immediately outside the fusion zone called the partially melted zone (PMZ) (Ref. 1 ). Liquation can result in hot cracking during welding (Refs. 1-7) or loss of ductility after welding (Refs. 8-10).

Huang, et al. (Refs. 11, 12), recently studied the PMZ in gas metal arc welds of 2219 aluminum alloy, which is essentially a binary AI-Cu alloy with a Cu content between 6 and 7 wt-% Cu. It was observed that extensive liquation occurs both along grain boundaries (GBs) and at large 9 (AI2Cu) particles, which are present in the grain interior and sometimes at GBs as well. The most significant find- ings are as follows. First, liquation is initiated at the eutectic temperature TE by the eutectic reaction between the 9 phase and the cz (AI-rich) matrix to form the liquid eutectic, and is intensified by further melting of the 0c matrix above TE. Second, solidification of the GB liquid is directional - - upward and toward the weld re- gardless of the position of the GB relative to the weld. Third, severe Cu segregation occurs both at the GB and in the grain interior, resulting in a Cu-depleted c~ phase next to a Cu-rich eutectic. The Cu- depleted ~ either forms a strip along the GB eutectic or surrounds the eutectic particle in the grain interior. Fourth, the PMZ is rather weak and it fractures pre- maturely under tensile loading; the brittle eutectic fractures badly, while the

KEY WORDS

Aluminum Alloy 2219 Partially Melted Zone Grain Boundary Gas Metal Arc Welding Planar Solidification Cellular Solidification

weak, ductile, Cu-depleted c~ elongates. The solidification modes of the li-

quated material in the PMZ have not been investigated so far. In the present report, the solidification theories for metal casting and crystal growth are applied on a microscopic scale to study solidification in the PMZ. One interesting question to ponder is how a partially melted grain can resolidify with a planar growth front just like a very slowly growing semicon- ductor crystal (Refs. 13, 14), even though the welding speed is obviously orders of magnitude higher than the crystal growing speed.

Experimental Procedure

Aluminum Alloy 2219 is a commercial, high-strength aluminum alloy, selected because it is a binary AI-Cu alloy with an easy-to-understand solidification. The actual composition of the workpiece is AI-6.79% Cu-0.27% Mn-0.13% Fe-0.12% Zr-0.08% V-0.05% Ti-0.04% Zn-0.01% Si by weight. The dimensions of the workpiece were 20 cm x 10 cm x 7.94 ram. This Cu content, 6.79%, is slightly higher than the 6.33% in the 6.35-mm-thick workpiece used in recent studies (Refs. 11, 12). The workpiece was welded in the as-received condition of T851 in the 20-cm direction. T8 stands for solution heat treating and cold working, followed by artificial aging; T51 stands for stress relieving by stretching (Ref. 15).

Two gas metal arc welds, weld 1 and weld 2, were made perpendicular to the rolling direction under the same welding condition. The welding parameters were 7.20 mm/s (17 in./min) welding speed, 26.5-V arc voltage, 195-A average current and Ar shielding. The welding wire was a 1.2-mm-diameter wire of alloy 2319; the actual composition was AI- 6.3% Cu-0.3% Mn-0.18% Zr-0.15% Ti- 0.15% Fe-0.10% V-0.10% Si. The wire

o 0

E

AI Weight Percent Copper

Fig. I - - AI-Cu phase diagram (Ref. 16).

(A)

boundary ~ ~ , liquid

{B} before liquation (C) fully liquated

direction .~ ~, /a~c'N~ mushy zone

o;e, o 0oo, i ,u,,oo ,u,,oo metal 'L- \ \ " ~ zone boundary

~ . . ~ ~ 2 ~ . ~ ~,~ J f /~ . . , ~ " x - 1 liq~ ation

j,~magnmea ~ zone

new grain boundary

WL[i_33L_~/ 31 / i i ~ . • ~ I / 'Cu-depleted Or,

eutectic (D) solidified

Fig. 2 - - Melt ing and solidif ication in the partially melted zone: A - - Overview; B through D - - magnified.

FZ

Fig. 3 - - ?Tp o f thermocouple sheath in weld 1 at the boundary between the fusion zone (FZ) and the partial ly melted zone (PMZ). Transverse cross section o f weld.

feeding speed was 13.5 cm/s (320 in./min).

An earlier weld, called weld 3 hereafter, was made in the same workpiece and with the same welding wire but under a different set of welding parameters. The welding speed was 12.7 mm/s, the welding voltage was 30 V, the average welding current was 250 A and the wire feeding speed was 18.6 cm/s.

Temperature measurements were ini- tially conducted by inserting thermocou- pies into holes drilled from the workpiece bottom. However, it was difficult making thermocouples to position at the targeted positions in the PMZ and the heat-affected zone.

Subsequently, temperature measurements were conducted during welding by plunging a thermocouple into the weld pool from behind the arc, at about 45 deg from the vertical plane along the welding direction. This was done with the help of

a mechanical device on which the thermocouple was mounted. Only one thermocouple was used in each weld because it was difficult for the device to hold more than one thermocouple at a time and push them to the targeted positions, given the rather l im ited space between the arc and the trailing pool edge.

The thermocou- pie was K-type with 0.025-ram-diameter wires and the re-

sponse time was 0.05 s in air and 0.002 s in water. To protect it from the arc, the thermocouple was inserted in an alumina sheath with a 0.5-mm ID and a 0.15-mm wall. The tip of the sheath was ground thinner to reduce the wall thickness at the tip to less than 0.15 mm. The thermal cycle was recorded with a computer- based data acquisition system.

The resultant welds were etched with a solution of 0.5 vol-% HF in water for optical microscopy.

Results and Discussion

Melting and Solidification in the PMZ

For convenience of discussion, the aluminum-rich portion of the AI-Cu phase diagram is shown in Fig. 1 (Ref. 16). The workpiece is considered here as a binary AI-6.79% Cu alloy as an approximation.

The melting and solidification in the PMZ are shown schematically in Fig. 2. Figure 2A is a vertical cross section of the weld pool and its surroundings that is parallel to the welding direction. Points 1, 2 and 3 are, respectively, located ahead of, inside and behind the region in which liquation is happening. Their corresponding microstructures are shown in Figs. 2B-D.

Large e particles are present in the grain interior and sometimes at the GB, as shown in Fig. 2B. The liquated material at the GB and in the grain interior is shown in Fig. 2C. Liquation is initiated at the large e particles at the eutectic temperature T E by the eutectic reaction between O and the surrounding (x matrix. Liquation is intensified by further melting of the surrounding (x at temperatures above TE.

Point 2 reaches its peak temperature TL and the width of the GB liquid w L reaches its maximum when the bottom of the weld pool touches point 2. Solidifi- cation of the GB liquid at point 2 begins when the bottom of the weld pool begins to pass point 2 and ends when the eutectic isotherm TE just passes point 2. The solidification time, ts, is the same as the res- idence time of point 2 in the freezing temperature range of T, to TE, which can be measured with a thermocouple positioned at the bottom of the weld pool.

The solidification mode of the GB liquid at point 2 depends on the temperature gradient, G, and the solidification rate, R. If the G/R ratio is high enough for planar solidification to occur, the GB liquid will solidify with the planar mode, that is, with a planar solidification front. Solidification occurs from the cooler side of the GB liquid to the warmer. As such, the GB actually shifts toward the weld, as can be seen by comparing the GBs in

W E L D I N G RESEARCH SUPPLEMENT J 47-s

solut ion zone

dark -e tch ing precipi tat ion zone

(B)

Fig. 4 - - Transverse cross sections o f part ial ly mel ted zones: A - - Weld I ; B - - weld 2. Points A, B and C are locations o f the micrographs shown in Figs. 7, 6 and 9, respectively.

Figs. 2B and D. This, in fact, is like Bridg- man crystal growth on a microscopic scale. Growth occurs epitaxially from upon the unmelted portion of the grain below the GB liquid, an interesting oc- curence because the GB liquid in between two neighboring grains is usually thought to solidify from both grains, not just one.

The GB liquid solidifies first as a solute-depleted, eutectic-free material, then as a solute-rich eutectic at the GB. Grain boundary segregation of Cu has been measured and reported in a previous study (Ref. 12).

Width of the P M Z

Figure 3 is a micrograph taken from the transverse cross section of weld 1. It shows the tip of the alumina sheath of the thermocouple plunged into the pool of weld 1. As shown, the thermocouple sheath lands at the fusion boundary. The

8 0 0

oo (D L..

t~

E

700

T, 6oo

5oo

4oo

Weld 1

..................... ~ 8 2 _ c . . . . . . . .

[

. . . . . . . . . . . . . . . . . . . . . . . . i 0 . 7 3 4 s e c

3 0 0 ............................. ! . . . . . . . . . . . . . . . . . . .

i (A) 200 . . . . ~ . . . . . . . ' . . . .

1.0 1 '.5 2 . 0 2 . 5 3 .0

Time, sec

800 ,

? =

L . .

Q. E

Weld 2 7 0 0 ........................................................................................................ ..__.~4~.~c._._~ ....................

6 0 0 ......................... ; . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

500 ....................................... i ..................................................... t

4 0 0 . . . . . i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

0.749 sec

,oo ! i, 2 0 0 . . . . . . . . .

1 .0 1.5 2 . 5 ' 210 ' " '

Time, sec

(B) 3.0

Fig. 5 - - Measured thermal cycles showing the sol idif icat ion times: A - - Weld 1; B - - weld 2.

situation is similar in weld 2.

Figure 4 shows the transverse cross sections of welds 1 and 2 and their PMZs. The upper boundary of

the PMZ is the fusion boundary of the weld, that is, T, = 643°C from the phase diagram - - Fig. 1. The lower boundary of the PMZ, that is, TE = 548°C, needs be determined with the help of a microscope. As shown in previous studies (Refs. 11, 12), the first sign of liquation is observed at the lower boundary of the PMZ, where large 0 particles begin to react eutectically with the surrounding (z matrix and form solid eutectic upon cooling. The workpiece microstructure is examined under the microscope upward from the bottom surface of the workpiece until these particles are found. This is repeated across the entire weld and its vicinity. The accuracy of the measurements of the distance between TL and TE is ___0.04 mm. It should be pointed out that at the location of these particles, GB liquation is usually not yet pronounced enough to be readily recognized because GBs are often free of O particles (Refs. 11, 12). Therefore, the size of the PMZ can be seriously under-

estimated if it is measured based on GB liquation.

As shown in Fig. 4, the PMZ is wider at the bottom and narrower on the top. In the vertical direction, the widths of the PMZ in weld 1 are Wp = 2.41 mm at point A, 1.98 mm at point B and 1.76 mm at point C. During welding, the workpiece was free from contact with any materials except at its four corners. As such, the workpiece's bottom surface acts as a thermal barrier to heat flow from the top. This reduces temperature gradients below the weld significantly. The isotherm corresponding to the edge of the dark-etching precipitation zone cuts the workpiece bottom at two separate locations. This is another indication of reduced temperature gradients below the weld. The reduced temperature gradients below a partially penetrating weld have been demonstrated by computer simulation of heat flow during welding (Ref. 17).

Thermal Cycles

Figure 5 shows the thermal cycles measured in welds 1 and 2. The locations of the thermocouples in the welds have been shown previously in Fig. 4. The res- idence time in the freezing temperature range, that is, from the liquidus tempera-


Fig. 6 - - Transverse cross section o f the microstructure in the part ial ly melted zone at po in t B in we ld I (Fig. 4A): A - - Lower magnif icat ion; B - - higher magnif ication.

Fig. 7 - Transverse cross section o f the microstructure in the part ial ly melted zone at po in t A o f weld 1 (Fig. 4A): A - - Lower magnif icat ion; B - - higher magnif ication.

ture TL (643°C) to the eutectic temperature TE (548°C), will be called the solidification time ts hereafter. From Fig. 5, ts = 0.734 s for weld 1 and t s = 0.749 s for weld 2. These results are close to each other, thus suggesting the validity of the temperature measurement technique.

Solidification Modes of GB Liquid

As already mentioned, the workpiece was welded perpendicular to the rolling direction. In a micrograph on the transverse cross section of the weld, the grains in the PMZ appear elongated in the horizontal direction. As observed in previous studies (Refs. 11, 12), GB liquid tends to solidify upward and toward the weld under the influence of the high-temperature gradient in the PMZ. Since GB liquid is hypoeutectic in composition, it solidifies first as a Cu-depleted c~ strip and last as the eutectic.

The PMZ microstructure at point B of Fig. 4A is shown in Fig. 6A. The top left corner is in the fusion zone and the rest is in the PMZ. The light-etching strips along the top of the grains in the PMZ are the Cu-depleted c~, and the dark-etching GBs at the top of the strips are the eutectic. Some ~ strips are shown in Fig. 6B at

a higher magnification. As shown, the c~ strips appear to be planar, that is, without cells or dendrites. The PMZ microstructure next to the thermocouple in weld 2 is similar.

The PMZ microstructure at point A of Fig. 4A is shown in Fig. 7A. The fine grain structure at the top is in the fusion zone. The ~ strip appears to be thicker in some grains and thinner in others. In general, thinner ~ strips are planar in structure while thicker ones are more likely to be cellular. Some c~ strips with a cellular structure are shown in Fig. 7B at a higher magnification. The c~ strips are, on average, significantly thicker than those at point B - - Fig. 6B.

The PMZ microstructure near the bottom of weld 3 is shown in Fig. 8A. The 590 J/mm heat input of weld 3 is lower than the 718 J/mm heat input of weld 1. The lower heat input of this weld results in less liquation, and the 0c strips are on average thinner than those at point A of weld 1 - - Fig. 7A. GB solidification is planar everywhere in the PMZ, including at the bottom of the weld (not shown). This is consistent with the lower heat input of weld 3. However, near the sharp turn in the fusion boundary (indi- cated by the arrow in Fig. 8A), cellular

solidification is observed. Some of the cellular c~ strips are shown in Fig. 8B at a higher magnification. The reason cellular solidification occurs here will be discussed later.

Figure 9A shows the PMZ microstructure near the top of the fusion boundary in weld 1 (point C in Fig. 4A). The upper left corner is part of the weld. The ~ strips are on average significantly thinner than those in the PMZ at the bottom of the weld (point A in Fig. 4A) shown previously in Fig. 7A. Furthermore, the 0c strips appear to be planar; no cellular c~ strips are visible. Some of the planar c~ strips are shown in Fig. 9B at a higher magnification. It is clear the ~ strips are either at the top of the grains or along the side of the grains that face the weld. This directional solidification behavior of the GB liquid, i.e., upward and toward the weld, has been previously discussed (Refs. 11, 12).

In order to understand the solidification modes of the GB liquid, the temperature gradient and the growth rate of the GB liquid will be discussed as follows.

G/R Ratio at GB

It is well known in both metal casting and crystal growth (Refs. 13, 14) that

W E L D I N G RESEARCH SUPPLEMENT I 49-S

Fig. 8 - - Transverse cross section o f the microstructure in the part ia l ly melted zone at the bot tom o f weld 3: A - - Lower magnif icat ion; B - - higher magnif ication. The arrow in A indicates a sharp turn in the fusion boundary.

I(B

Fig. 9 - - Transverse cross section o f the microstructure in the part ial ly melted zone at po in t C o f weld I (Fig. 4A): A - - Lower magnif icat ion; B - - higher magnif ication.

temperature gradient G and growth rate R, both in the direction perpendicular to the growth front (the solid/liquid interface), are the two most fundamental parameters of solidification. They determine the solidification mode, which in turn determines the resultant solidification microstructure.

The temperature gradient and the growth rate of GB liquid in the PMZ will be estimated as follows. Consider point 2 in Fig. 2A. As an approximation, the temperature gradient is

G = TL - TE (1) Wp

where Wp is the width of the PMZ. This G is the average temperature gradient across the width of the PMZ.

Let wL be the thickness of the GB liquid, as shown in Fig. 2C. As an approximation, the growth rate of the GB liquid is

R -- wL (2) ts

where t s is the solidification time of the GB liquid. This R is the average growth rate of the GB liquid. From Equations 1 and 2

G _ = ( T L - T E )ts (3) R WpW L

According to the constitutional super- cooling theory (Refs. 1, 13), for a planar solidification front to be stable, the following criterion must be met:

G > - m L C L (1 - k) (4) R D L

where m L is the slope of the liquidus line in the phase diagram, CL the solute con- centration of liquid at the growth front, k the segregation coefficient and DL the diffusion coefficient of solute in the liquid. If G/R is less than the right-hand side (RHS) of Equation 4, the planar solidification front will break down into a cellular or dendritic one.

Equations 3 and 4 can be further combined to give the following criterion for plane front solidification of the GB liquid

(TL-TE)ts >- mLCL(1-k) (5) WpW L D L

The RHS of Equation 4 can be determined with the help of the phase dia-

gram. As an approximation, the liquidus line and the solidus line of the phase diagram are both assumed to be a straight line. From Fig. 1, the slope of the liquidus line is mL = (548-660°C)/(33.2-0% Cu) -- -3.37°C/% Cu. The equilibrium partition ratio, k = 5.65% Cu/33.2% Cu = 0.17. At the fusion boundary of weld 1, i.e., at the liquidus temperature 643°C, CL is 6.79% Cu. The diffusion coefficient of Cu in liquid AI-5% Cu is about 5 x 10 -s cm2/s (Ref. 18). From these data, the RHS of Equation 4 becomes the following:

m L C L (1 - k)

DL (3.37°C / %Cu) x 6.79%Cu x (1 - 0.17

5 x 10-5cm 2 /s

= 3.80x105 °Cs cm 2

(6

The left-hand side (LHS) of Equation 4, i.e., the G/R ratio, has to be greater than this threshold value if the GB liquid is to have a stable planar solidification front.

To find the G/R ratio, the temperature gradient G and the growth rate R will both have to be determined first. To de-

SO-s I FEBRUARY 2001

@1

E

660r

640~

620~

600~

580~

560~

5401 0 .0 0'.2 0'.4 016 0'.8 1.0

Fraction of liquid, fL

TL

Fig. 7 0 - Relationship between fraction o f l iqu id and temperature in AI- 6.79% Cu.

termine the temperature gradient G from Equation 1, the width of the PMZ is needed. Since the GBs are essentially horizontal because of rolling, the GB liquid is essentially horizontal, too. As such, the relevant temperature gradient G should be the one in the vertical direction, i.e., perpendicular to the GB liquid. Therefore, the PMZ width, wp, is taken as the vertical distance from the fusion boundary (the liquidus temperature TL) to the location where 0 begins to react with the surrounding c£ matrix eutectically (the eutectic temperature TE).

Consider point B in Fig. 4A. As already mentioned, at point B in weld 1, wp = 1.98 ram. From Equation 1 and with TL = 643°C and TE= 548°C, the average temperature gradient G perpendicular to the GB liquid at point B is the following:

c _~ TL - T~

Wp

643oc - 548oc °C - - 4 8 0 - - (7)

0.198cm cm

The average growth rate R perpendicular to the GB liquid can be determined from Equation 2. As already shown, ts = 0.734 s at point B in weld 1. For an (z strip of about 5 p,m thick, Equation 2 becomes the following:

(8)

t2 ` _ W L _ 5X10 -4 c m

t s 0.734 s

= 6.81 x 10 -4 cm 5

N

"O O

t - ~ z

From Equations 7 and 8,

T A

TB

I--

Q .

E

AI - 6.79 % Cu

Temperature, T

T B TA T L

higher temperature gradient

temperature gradient

(A)

TL

T E : ~ / (B)

0 fLB fLA 1

Fraction of liquid, fL

Fig. 11 - - Comparison between two points, A and B, located at a very short but equal distance be low the fusion boundary: A - - Temperature; B - - fraction o f l iquid.

G 480°C / cm

R 6.81x 10-4cm / s

= 7.05 x 105 °C s (9) cm 2

This G/R is above the threshold value of 3.80 x 10s°C s/cm2 in Equation 6 for planar solidification. This appears to be consistent with the micrograph in Fig. 6A. The (z strips have an average thickness of about 5 p.m and they appear planar.

It is worth mentioning, however, that C, in Equation 6 (the Cu content at the growth front of solidifying GB liquid) is not constant but increases during solidification. Therefore, at some point during solidification, --m,CL(1 -- k)/DL can become greater than G/R and planar solidification can break down. From the micrograph in Fig. 6, however, it does not look like this has happened. Discussion of this question follows.

According to the classic theory of interface stability of Mullins and Sekerka (Refs. 19-21), when instability occurs at the planar growth front, it initiates as a perturbation at a certain wavelength. The amplitude of the perturbation can gradually grow and eventually result in a cellular growth front. From Figs. 7B and 8B, the cellular spacing appears to be signif-

icantly greater than the width of GB liquid shown in Fig. 6B. This implies that for the GB liquid shown in Fig. 6B, a planar growth front would not seem to have enough space to evolve into a cellular one before solidification is over. This may explain why planar solidification did not break down before GB solidification was over. In fact, this also implies that even with a G/R ratio below the threshold value, cel lular sol idif ication may not necessarily occur if the GB liquid is too thin to allow enough room for a planar growth front to gradually evolve into a cellular one before solidification is over.

Consider point C in Fig. 4A, where the width of the PMZ in the vertical direction is 1.76 mm. The temperature gradient perpendicular to the GB liquid is, therefore, G = (643-548°C)/0.176 cm = 540°C/cm, which is higher than the 480°C/cm shown previously in Equation 7. From its micrograph shown in Fig. 9, the average thickness of the ~ strips is about 5 ~m. The solidification time, ts, is not available. If it is assumed to be close to that at point B (ts = 0.734 s) as an approximation, the growth rate R = 6.81 x 10 -4 cm/s and the G/R ratio = 7.93 x 105°Cs/cm 2, which is above the threshold value of 3.80 x 10s°C s/cm2 for planar solidification. This appears to be consistent

WELDING RESEARCH SUPPLEMENT I 51-s

with the planar (x strips shown in Fig. 9B. Now consider point A in Fig. 4A,

where the width of the PMZ in the vertical direction is 2.41 mm. The temperature gradient perpendicular to the GB liquid is G = (643-548°C)/0.241 cm = 394°C/cm. From its micrograph shown in Fig. 7B, the average thickness of the strips is almost 15 ~m thick. The solidification time, ts, is not available. Again, if it is assumed to be close to that at point B (ts = 0.734 s) as an approximation, the growth rate R = 2.04 x 10-3 cm/s and the G/R ratio = 1.93 x 10s°C s/cm2, which is below the threshold value of 3.80 x 10s°C s/cm2 for planar solidification. This appears to be consistent with the cellular GB 0~ strips shown in Fig. 7.

It should be pointed out that consid- ering the uncertainties in D, and other values in the calculations, the G/R ratios of 1.93 x 10s°C s/cm2 for point A, 7.05 x 10s°C s/cm2 for point B and 7.93 x 10s°C s/cm 2 for point C are not really much different from the threshold value of 3.80 x 10s°C s/cm2. What is of primary impor- tance, however, is that at points A, B and C of weld 1, the differences in G/R are consistent with the change in the solidification mode of the GB liquid.

Fraction of Liquid and Width of GB Liquid

As previously mentioned, in weld 1 the grain boundary liquid is thicker at point A than at point B, which are about the same distance below the fusion boundary. This can be explained as follows:

Figure 10 shows the relationship between temperature and the fraction of liquid for the AI-6.79% Cu base metal, based on the Scheil equation (Refs. 1, 13). As shown, the fraction of liquid increases rapidly with increasing temperature as the liquidus temperature, T u is approached. As already mentioned, the temperature gradient G is significantly (22%) higher at point B than at point A. Therefore, as shown in Fig. 11A, the temperature at point A is higher than that at point B, even though they are at the same distance, z~, below the fusion boundary. As shown in Fig. 11 B, the fraction of liquid at point A can be significantly greater than that at point B because the fraction increases sharply as the liquidus temperature is approached. Since the local average fraction of liquid is higher at point A than at point B, the GB liquid is thicker at point A than at point B.

Since the temperature is higher at point A than at point B, from the phase diagram (Fig. 1) the composition of the GB liquid can be expected to be lower at A than at B. This suggests that, based on Equation 4, the threshold G/R ratio for planar solidification can be lower for

point A than for point B, and not exactly fixed at a constant value as suggested by Equation 6. Although this is in favor of planar solidification at point A, cellular solidification can still occur at point A in view of its significantly lower G and higher R.

Figure 11 can also help explain the cellular solidification in weld 3 shown in Fig. 8. As mentioned previously, the 590 J/mm heat input of this weld is lower than the 718 J/mm heat input of weld 1, and GB solidification is planar everywhere in the PMZ except near the arrow shown in Fig. 8A. The temperature gradient G is lower in the area because the material here has to absorb heat coming from two sides, rather than one, and because it has less mass to act as an effective heat sink. According to Fig. 11, the local temperature here is higher and the local fraction of liquid is also higher. Consequently, the width of GB liquid WL is greater here and, from Equation 2, growth rate R is higher. As such, the lower local G/R ratio here fa- vors cellular solidification. The wider GB liquid also provides more room for cellular solidification to evolve.

Solidification Modes within Grains

In the PMZ, large 0 particles present in the grain interior react eutectically with the surrounding ~ matrix and form liquid spots during welding. One such liquid spot has been shown schematically in Fig. 2C. As the fusion boundary is approached, the size of the liquid spot increases rapidly, i.e., the local average fraction of liquid increases sharply. Ac- cording to Fig. 10, as the liquidus temperature (fusion boundary) is approached, the fraction of liquid increases sharply.

Particle X in Fig. 6B results from the solidification of a large liquid spot near the weld. In fact, as shown in Fig. 6A, several similar particles are present in the area to the left and above this one. Ap- parently, the solidification mode is not planar because the morphology of the eutectic in particle X appears complex. With a liquid spot, essentially one half of its perimeter faces the weld, along which directional solidification toward the weld can occur. Since the growth front is con- cave toward the liquid rather than flat, solute rejected by the growth front can accumulate more rapidly. Perhaps this has helped trigger early breakdown of planar solidification. The liquid spot is much thicker than the GB liquid nearby, i.e., its diameter is several times the width of the GB liquid. This can suggest two things. First, the liquid spot has to solidify with a much greater solidification rate R and, hence, a smaller G/R ratio than the

GB liquid. Second, the greater thickness of the liquid spot gives more room for nonplanar solidification to evolve.

Particle Y, which is farther away from the weld, is much smaller than particle X and it shows planar c~. According to the phase diagram (Fig. 1), the lower the local temperature, the higher the solute content of the liquid. From Equation 4, the threshold G/R is greater at particle Y than at particle X, and thus planar solidification can break down more easily at particle Y than at particle X. However, the liquid appears to be too thin for cellular solidification to evolve before solidification is over at particle Y. Similar particles are also shown in Fig. 9B.

Conclusions

In the present study on the PMZ in welds of aluminum Alloy 2219, planar and cellular solidification have been observed in the PMZ, both at the GB and in the grain interior. GB liquid tends to solidify with the planar solidification mode. This is because the G/R ratio is high and because the GB liquid is too thin for a planar growth front to evolve into a cellular one before solidification is over. The average temperature gradient G can be estimated from the width and temperature range of the PMZ. From the thickness of GB liquid and thermal cycle measured during welding, the average R can also be estimated. The G/R for the GB liquid in the PMZ near the weld is estimated to be on the order of 10s°C s/cm2, which is close to that required for planar solidification of the GB liquid. However, in the PMZ at the bottom of the weld, cellular solidification can occur, especially where the GB liquid is thicker (15 14m) because of lower G and higher R. For a partially penetrating weld like those in the present study, the lowest G in the PMZ appeared to be at the bottom of the weld. The average growth rate R is higher for a thicker GB liquid because it has to solidify faster. As such, the GIR ratio is low for a thicker GB liquid at the bottom of the weld, where cellular solidification is observed. Large prior 0 particles in the grain interior liquate and form liquid spots that solidify with a planar mode. However, near the weld, liquid spots become much larger and so does R. The much lower GIR and greater spot size allow planar solidification to break down.

Acknowledgments

This work was supported by the Na- tional Science Foundation under Grant No. DMR-9803589. The authors are grateful to Bruce Albrecht and Todd

52-S I FEBRUARY 2001

Holverson of M i l le r Electric Mfg. Co., Appleton, Wis., for donat ing the weld ing equipment and for their technical assistance during the study. They also thank the reviewers for their helpful comments.

References

1. Kou, S. 1987. Welding Metallurgy. New York, N.Y.: John Wiley and Sons. pp. 29-59, 137-139 and 239-262.

2. Robinson, I. B. 1978. The Metallurgy of Aluminum Welding. Pleasanton, Calif.: Kaiser Aluminum Corp.

3. Gittos, N. F., and Scott, M. H. 1981. Heat-affected zone cracking of AI-Mg-Si alloys. Welding Journal 60(6): 95-s to 103-s.

4. Dudas, J. H., and Collins, F. R. 1966. Preventing weld cracks in high-strength aluminum alloys. Welding Journal 45:3-11.

5. Lippold, J. C., Nippes, E. F., and Savage, W. F. 1977. An investigation of hot cracking in 5083-0 aluminum alloy weldments. Welding Journal 56(6): 171 -s to 178-s.

6. Metzger, G. E. 1967. Some mechanical properties of welds in 6061 aluminum alloy sheet. Welding Journal 46(10): 457-s to 469-s.

7. Steenbergen, J. E., and Thornton, H. R.

1970. Quantitative determination of the conditions for hot cracking during welding for aluminum alloys. Welding Journal 49(2): 61-s to 68-s.

8. Gibbs, F. E. 1966. Development of filler metals for welding AI-Zn-Mg Alloy 7039. Welding Journal 45(10): 445-s to 453-s.

9. Young, J. G. 1968. BWRA experience in the welding of aluminum-zinc-magnesium alloys. Welding Journal 47(10): 451 -s to 461 -s.

10. Arthur, J. B. 1955. Fusion welding of 24S-T3 aluminum alloy. Welding Journal 34: 558-s to 569-s.

11. Huang, C., and Kou, S. 2000. Partially melted zone in aluminum welds - - Liquation mechanism and directional solidification. Welding Journal 79(5): 113-s to 120-s.

12. Huang, C., and Kou, S. 2001. Partially melted zone in aluminum welds-- Solute segregation and mechanical behavior. Welding Journal 80(1 ): 9-s to 17-s.

13. Flemings, M. C. 1974. Solidification Processing. New York, N.Y.: McGraw-Hill. pp. 31-92, 95.

14. Kou, S. 1996. Transport Phenomena and Materials Processing. New York, N.Y.: John Wiley and Sons. pp. 526-585.

15. The Aluminum Association. 1982.

Aluminum Standards and Data. Washington, D. C.: The Aluminum Association. p. 15.

16. American Society for Metals. 1986. Bi- nary Alloy Phase Diagrams. Vol. 1. Metals Park, Ohio: American Society for Metals. p. 106.

17. Kou, S., and Le, Y. 1983. Three-dimensional heat flow and solidification during au- togenous GTA welding of aluminum plates. Metallurgical Transactions 14A: 2245-2253.

18. Ejima, T., et al. 1980. Impurity diffusion of fourth period solutes (iron, cobalt, nickel, copper and gallium) and homovalent solutes (indium and thallium) into molten aluminum. J. Jan. Inst. Met. 44(3): 316-323.

19. Mullins, W. W., and Sekerka, R. F. 1963. Morphological stability of a particle growing by diffusion or heat flow. Journal of Applied Physics 34(2): 323-329.

20. Mullins, W. W., and Sekerka, R. F. 1964. Stability of a planar interface during solidification of a dilute binary alloy. Journal of Applied Physics 35(2): 444-451.

21. Sekerka, R. F. 1965. A stability function for explicit evaluation of the Mullins-Sekerka interface stability criterion. Journal of Applied Physics 36(1 ): 264-268.

Call for Papers

The Laser Institute of America (LIA) is seeking abstract submissions for the 20th International Congress on Applications of Lasers and Electro-Optics (ICALEO ® 2001), to be held October 15-18, 2001, in Jacksonville, Fla.

ICALEO 2001 will consist of two conferences, the Laser Materials Processing Conference and the Laser Microfabrication Conference. Papers sought in the Laser Materials Processing Conference include innovative applications, aerospace and automotive applications and laser safety; topics on cutting, drilling, welding, rapid prototyping and surface modification; lasers and laser systems including diode, diode-pumped, gas, advanced laser sources and laser beam shaping.

The Laser Microfabrication Conference will emphasize papers on biomedical applications including catheters, stents, drug delivery, implantable devices and microsurgical components; photonics including diffractive optics, microlenses and microsculpting; electronics involving display devices, silicon machining, surface texturing and thin film patterning; and processes such as cutting, drilling, welding, marking and ultrafast laser processing.

Abstracts should relate original, recent and unpublished results on any of the above topics. Submission deadline is March 30, 2001. For further information visit www.icaleo.org or contact Beth Cohen at (800) 34-LASER or (407) 380-1553.


Modified Active Control of Pulsed GMAW of

Metal Transfer and Titanium

A control method that delivers one drop per pulse transfer in a robust and repeatable manner is proposed

BY Y. M. Z H A N G A N D P. J. LI

ABSTRACT. Conventional pulsed gas metal arc welding (GMAW-P) achieves stable and repeatable spray transfer by using correct pulse parameters. Because the optimal pulse parameters depend on welding parameters, technology is needed to improve the robustness of the transfer process respective to the variations in welding parameters. To resolve this problem, active control technology is proposed to ensure a desirable and repeatable metal transfer mode, i.e., one drop per pulse (ODPP) mode. It uses a peak current lower than the transition current to prevent accidental detachment and takes advantage of the downward momentum of the oscillating droplet to enhance the detachment. When the droplet moves toward the weld pool, the current is switched to peak level and the combination of increased electromagnetic detaching force and downward momentum ensures detachment. Hence, the metal transfer process becomes controllable and robust against variations in welding parameters. However, in order to ensure the combination of increased electromagnetic force and downward momentum, the oscillation process must be monitored. In this study, a modified method is proposed in which the droplet starts to oscillate by first moving toward the weld pool. As a result, the detaching pulse can be applied after a very short period of time and the combination of increased electromagnetic force and downward momentum is guaranteed. Thus, the control system is simplified and the metal transfer's robustness is further improved. This modified active control technology has been used to weld titanium.

Y. M. ZHANG and P J. LI are with the Weld- ing Research and Development Laboratory, Center for Robotics and Manufacturing Sys- tems and Department of Electrical Engineer- ing, College of Engineering, University of Ken- tucky, Lexington, Ky.

Introduction

Titanium is characterized by its high strength and light weight. Such attributes make titanium a primary choice for more and more components and structures in aircraft, tanks and naval vessels (Refs. 1, 2), as well as in certain commercial applications (Ref. 3). In general, titanium alloys have good weldability and can be welded with most arc welding processes. However, a strict atmospheric shield is required to ensure weld quality. Gas tungsten arc welding (GTAW) uses a non- consumable tungsten electrode and generates a stable arc. It is an ideal process for titanium welding. However, its low productivity is not desirable for thick section structures and components. The use of a process such as gas metal arc welding (GMAW) would significantly improve productivity and reduce manufacturing costs if adequate shielding could be achieved.

GMAW of titanium has been investigated for decades. The mode of metal transfer plays a critical role in ensuring the shield. In particular, globular and un- controlled short-circuiting transfers generate significant amounts of spatter, which cause turbulence. Also, the strong cathode jet in globular transfer, a unique phenomenon to the GMAW process with titanium, tends to project the droplets outward when they break up upon entering the weld pool (Ref. 4), making the

KEY WORDS

Titanium Welding GMAW-P Pulsed Current Welding Peak Current Metal Transfer Electromagnetic Force

shielding additionally difficult. On the other hand, spray transfer generates a low level of spatter and has a relatively stable arc. It provides a better shield. Unfortu- nately, however, when a constant current is used, spray transfer is only achieved at high currents in an argon shield. Low currents will produce globular and short-circuiting transfer, and thus, an unstable arc and severe spatter (Refs. 4-8).

Pulsed GMAW uses a low base current to maintain the arc and a high peak current to melt the electrode and detach the droplet. It is capable of achieving spray transfer at low mean currents (Refs. 9, 10). Also, GMAW-P tends to detach the droplet during the base current period. According to an earlier study by Eager, et al. (Ref. 4), droplets are subject to a rejecting force due to the plasma jet issuing from the weld pool, resulting in a condition that may eject coarse spatter. Because the rejecting force is proportional to the amplitude of the welding current, it is very low in the base current period of pulsed GMAW and the plasma- jet-related spatter is minimized. Hence, pulsed GMAW has been used to avoid globular transfer, reduce spatter and improve arcing stability in titanium welding (Refs. 11, 12).

Although GMAW-P is capable of reducing spatter and improving arc stability through spray transfer, such capability is conditional. To ensure a stable arc and an adequate shield, the transfer process must be repeatable and controllable. That is, the transfer rate, number of droplets detached in a unit of time, and the droplet size must be consistent and in an appropriate range. For GMAW-P, an applicable method to ensure the repeatability and controllability has been to detach one, and only one, droplet per pulse (ODPP) with a droplet diameter close to that of the electrode (Refs. 10, 13, 14). In conventional pulsed GMAW, this is achieved by selecting an appropriate duration and amplitude for the peak current. However, in order to ensure the detachment or

54-s [ FEBRUARY 2001

F

i

qF----~

-.---g.---

i A

• ~ i~i ~

T

¥ T

Fig. 1 - - Cur rent wave fo rm used for act ive d rop le t transfer contro l .

avoid one-droplet multiple pulses (ODMP), a peak current higher than the transition current (Ref. 14) must be used.

The use of high current narrows the range of peak current duration for gener- ating stable ODPP. If the duration of the peak current period is longer than required, multiple droplets may be detached in a single pulse (Ref. 15), resulting in a streaming spray transfer. If the duration is shorter, multiple pulses may be needed to develop and detach one droplet (Ref. 13). In addition, such peak current duration depends on, and varies with, welding parameters and conditions. In fact, to determine the peak current duration, studies have been conducted to experimentally correlate wire feed speed, peak current level, peak current duration, base current level and base current duration for a given electrode material, electrode wire diameter and composition of shielding gas (Refs. 10, 13, 14). However, because of the narrow range and its dependence on welding conditions, such an open-loop selection of duration is often not robust with respect to welding parameters and conditions. Repeatable and controllable metal transfer and adequate shielding are not guaranteed.

Modified Active Control

Active Control To achieve a robust control technol-

ogy for repeatable and controllable metal transfer, the authors have proposed oscillating the droplet, utilizing the down-

I I

ward momentum of the oscillating droplet to enhance detachment controllability (Refs. 17-19). As seen in Fig. 1, during period T 1 , the droplet grows gradually and is dragged in the weld pool direction by a downward electromagnetic force generated by the exciting pulse. During period T2, the current is switched to a low level and, therefore, the electromagnetic force is decreased significantly. As a result, the droplet moves towards the electrode and then springs back toward the weld pool due to the surface tension of the melted droplet. DuringT 3 period, the current is switched to a higher level (detaching pulse). With the assistance of downward momentum, the increased electromagnetic force ensures the droplet is detached with a current lower than the peak current needed in conventional pulsed current GMAW. This method has been referred to as active control of metal transfer (Refs. 1 7-19).

Analysis Although satisfactory droplet transfer

can be achieved with active metal transfer control technology, further improve- ments will be beneficial for production of high-quality GMAW, especially for titanium welding. Specifically, analysis shows that the free oscillation period T 2 is critical in ensuring detachment. Droplet mass, electrode material prop- erty and excitation level (the difference between the exciting pulse and the base current) all influence the selection of T 2 and the efficiency in using the downward

I B Electr°magnetic i

I 1 Electromagnetic Force

Fig. 2 - - A rc d is t r ibut ion a n d arc force. A - - L o w current ;

B - - h igh current.

momentum. To take advantage of the downward momentum, the phase match condition must be satisfied, i.e., the detaching pulse must be applied when the droplet moves toward the weld pool. To take maximal advantage of the downward momentum, the detaching pulse was applied when downward motion of the droplet was first detected [based on analysis of vertical coordinates of the electrode tip after oscillation was excited in our previous work (Ref. 1 7)].

This study reveals the active control method may be modified to further improve robustness of metal transfer repeatability and controllability. Such im- provements could be particularly beneficial for titanium welding. As can be seen, in the previous method (Ref. 1 7), the droplet is dragged toward the weld pool by the electromagnetic force in the exciting pulse period. The droplet starts to oscillate toward the electrode when the current is switched from the exciting level to the base current level. When the droplet starts moving toward the weld pool, the detaching pulse is applied to detach the droplet. Because of the damping force, the oscillation energy decreases gradually. The downward momentum, which can be used to enhance the detachment, also decays. Because the droplet first moves toward the electrode after the current is switched to the base level, the detaching pulse can only be applied after the oscillation energy decays for a half oscillation period. As a result, the effective downward momentum for detachment decreases, and the required amplitude of the detaching pulse increases. If the droplet begins the oscillation by first moving toward the weld pool, such decrease in the effective downward momentum and increase in the amplitude of the detaching pulse will be eliminated. In this paper, such a scheme is referred to as modified oscillation. The resultant control is referred to as modified active control.

In addition to the increase in effective downward momentum and the decrease in the detaching current, the modified os-


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i [ Ba,c i

y V

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i

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Fig. 3 - - Comparison of current waveforms for active control and its modification.

¼

High Speed ( ;l~llera

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Fig. 4 - - Experimental apparatus diagram.

Fig. 5 - - Droplet detachment with pulsed current 200/35 A, 50 Hz, 22 V and electrode positive. The electrode is 0.9-ram (0. 035-in.) ER-fi- 1, 800 frames per second.

cillation scheme also generates two additional and important advantages. First, in active control, the droplet is not detached until half an oscillation period has gone. Such a mandatory waiting period lowers the upper limits of the transfer rate and achievable welding current. For example, when 0.9-mm (0.035-in.) wire is used, the upper limit of the metal transfer rate is 80 Hz, lower than it is in conventional GMAW where the typical range of transfer is from 40 to 120 HZ. If a greater diameter wire is used, the frequency limit will be further lowered. Second, the frequency of oscillation depends on the mass of the droplet (Ref. 17). In active control, the detaching current is applied after half an oscillation cycle. To ensure the phase match, the oscillation must be monitored. If the phase match condition is not satisfied when the detaching pulse is applied, the droplet cannot be detached. In that case, the performance of the active control would be even worse than conventional-pulsed GMAW. In previous studies, the oscillation was monitored by high-frame camera (Ref. 17) or the arc voltage signal (Ref. 19). If the modified oscillation scheme is used, the detaching pulse can be applied shortly after oscillation. The phase match is guaranteed. The monitoring system becomes unnecessary, the control system becomes simpler and the process becomes more robust.

Depending on the amplitude of the exciting pulse, the droplet can either be lifted towards the electrode or dragged downwards to the weld pool, as shown in the previous studies (Refs. 20, 21). In fact, when the welding current is low, the arc force pushes the droplet back to the electrode, as shown in Fig. 2A. The electromagnetic force directs to the electrode. As the welding current increases, the arc root covers more and more of the surface of the droplet. When approximately half the droplet is covered by the arc root, the arc force changes its direction, pointing to the weld pool, as illustrated in Fig. 2B. For a given diameter of electrode, the welding current can be selected to fully control the direction of the electromagnetic force, either toward or away from the electrode. For example, for the titanium electrode used in this study, a 100-A or lower current always produces an electromagnetic force pointing toward the electrode, despite the size of the droplet and other welding conditions. A 140-A or higher current always generates an electromagnetic force away from the electrode. That is, the direction of the electromagnetic force is controllable. Hence, the authors propose a method, as illustrated in Fig. 3, to realize the modified oscillation scheme. As


shown in Fig. 3, the modified active control uses a relatively low exciting current to lift the droplet toward the electrode. After the current is switched from the exciting level to the base level, the droplet moves toward the weld pool because of the reduction in the lifting electromagnetic force. After a short period, the detaching pulse current is applied. The detaching current has been designed to ensure the electromagnetic force is away from the electrode. The combination of the detaching electromagnetic force and the downward momentum of the droplet ensures detachment. Hence, the modified oscillation scheme and modified active control are realized.

Experiments revealed the time interval for "free" oscillation (the base current level is very low), i.e., T 2 in Fig. 3, determines the efficiency of the detaching pulse. A correct time interval maximizes the efficiency of the downward momentum, which offers the advantage of reducing the amplitude of the detaching pulse to guarantee the detachment. The relationship between the downward momentum and exciting pulse current value and period was investigated as well. The current waveform was modified based on all these results, as shown in Fig. 3. The details will be discussed later in this paper.

Experimental Procedure

All experiments were performed with bead-on-plate welding. Titanium alloy (ERTi-1) workpiece and 0.9 mm (0.035 in.) titanium wire (ERTi-1) were used. The shielding gas was pure argon (99.999% purity) with a flow rate of 20 L/min. The power supply was an inverter welding power source with current output range from 5 to 450 A (pulse current). This power supply can be used for either constant current (CC) or constant voltage (CV) mode. In this study, the welding current was produced by CC mode. The welding equipment was computer controlled to produce a specific pulsed current waveform and constant arc length. The workpiece was clamped on a trans- versing weld table, allowing the welding torch to remain stationary. The experimental set-up is shown in Fig. 4.

Observation of the droplet was facil- itated by a laser backlighting system. A high-speed camera, 800 frames per second, was positioned to record the transfer of the droplet. The camera's resolution is 128 x 128. For monitoring the droplet transfer process, a 15 x 15 mm field of view surrounding the end of the wire was selected. The corresponding resolution of the camera is about 0.12 mm (0.0048 in.). It can be seen from the images given in this work that the reso-

Fig. 6 - - Droplet detachment with pulsed current 200/35 A, 50 Hz, 22 V and electrode positive. The electrode is 0.9-ram (0.035-in.) ER77-1, 800 frames per second.

Fig. 7 - - Droplet detachment with active detachment control method, detaching current 165 A, base current 35 A, 50 Hz, 20 V and electrode positive. The electrode is 0.9-mm (0.035- in.) ERTi-1, 800 frames per second.

Fig. 8 - - Droplet detachment with pulsed current 230/35, 40 Hz, 22 V and electrode positive. The electrode is 0.9-ram (0.035-in.) ERTi-1, 800 frames per second.

WELDING RESEARCH SUPPLEMENT [ 57-s

1200

15 60o .Z, 8 4oo

Unstable for pulsed Stable for pulsed current GM~W current GM~W

• P u l s e d current , i , i , i , i , i , i , i

4 0 1 6 0 1 8 0 2 0 0 2 2 0 2 4 0 2 @ ) 2 8 0

Current used to detach the droplet, A

Fig. 9 - - Average velocity of droplet transfer in active detachment process and conventional pulsed current process.

¢.

Fig. 10 - - Droplet detachment with modified active control, detaching current 160 A, base current 35 A, 50 Hz, 22 V and electrode positive. The electrode is 0.9-ram (0.035-in.) ERTi- I, 800 frames per second.

lution of the camera is sufficient to extract the geometrical parameters of the droplet. Thus, the droplet can be monitored at least 6 times per cycle during oscillation. Under this monitoring rate, the oscillation phase of the droplet can be monitored reliably. During experiments, the computer output the specific current form and grabbed the images. The images were processed later to investigate the effect of modified active control on droplet detachment.

Resul ts a n d D i s c u s s i o n

Stability plays a critical role in reducing spatter and improving the shielding of the weld area in GMAW of titanium. In the conventional-pulsed GMAW process, if a constant ODPP transfer is obtained, the process is stable because the variation of arc length caused by droplet transfer is small. Furthermore, the droplet is detached in the base current period, resulting in a low rejecting force (Ref. 4). Figure

5 shows images taken during a constant ODPP transfer. The droplet was detached after the peak current period. The rejec- tion effect is not observed.

However, the range of pulsed current parameters for achieving ODPP mode under a certain condition is narrow. Al- though parameters were tuned carefully, random interruption always impairs the stable droplet transfer process, such as the variation of arc length or contact tube wear. As shown in Fig. 6, with the same parameters for the process shown in Fig. 5, after the droplet detached from the wire tip, it returned to the wire due to relatively insufficient pulse energy. It appears the energy required by each pulse to detach the droplet reliably may vary according to the welding conditions. If pulse energy is relatively low, the droplet cannot transfer until its gravity is larger than the surface tension after several pulses. The process becomes unstable, especially for thin wire, because the variation of arc length is larger due to the rel-

atively large surface tension. In order to ensure detachment, high peak current value and long peak current period may be used. However, in addition to high droplet impact speed, the corresponding detachment process tends to proceed asymmetrically. Also, due to the violence of the detachment, the droplet sometimes breaks apart, resulting in coarse spatter.

Stable droplet transfer has been en- sured by using the active droplet transfer control technique. As shown in Fig. 7, during the exciting pulse, the droplet moves downwards to the weld pool due to electromagnetic force. The droplet moves symmetrically or asymmetrically about the electrode's axis, depending on the distribution of arc root on the droplet surface. Equilibrium is established between the electromagnetic force, gravity and the retaining force due to surface tension. When exciting pulse current is switched to the base current level, the droplet begins to oscillate because of the decrease of electromagnetic force, which is proportional to the welding current's power. The spring force derived from surface tension and the damping force from viscous stresses dominate the movement of the droplet. Because they are symmetrical, the motion of the droplet tends to be symmetrical about the electrode's axis. When the droplet starts to move downward, the current is switched to the detaching level and the droplet is detached reliably and axially. The oscillation of the droplet is beneficial for achieving a stable transfer process from two points of view. The oscillation re- trieves the droplet's symmetric shape, and the downward momentum decreases the peak current needed for constant ODPP process. In Fig. 7, the droplet's form was asymmetrical when the exciting pulse was applied. After the oscillation, the motion of the droplet tends to be symmetrical and then it is detached axially. The detaching current needed is only 165 A. However, in the conventional-pulsed current GMAW process of titanium, the droplet is sometimes asymmetrical and when pulsed current is applied, the droplet does not move axially. The droplet may be detached away from the wire to produce coarse spatter, as shown in Fig. 8. The peak current needed is about 230 A for constant ODPP transfer mode.

Besides constancy, another characteristic of the transfer process with active control is the speed of the droplet decreases significantly, to only half of that in conventional pulsed current welding. As shown in Fig. 9, the average speed of the droplet in GMAW-P is 816mm/s for 0.9-mm (0.35-in.) wire with ODPP mode using 230-A pulsed current. The average


speed of the droplet with the active control technique is 423 mm/s, with the same detaching current value. Further- more, the active control uses a much lower detaching current than the peak current in conventional-pulsed GMAW, resulting in a droplet transfer speed decrease to 345mm/s.

The modified active control inherits all of the advantages of the active control method. In addition, the modified control technique further eliminates remaining problems in its origin. As seen in Fig. 10, the droplet is first lifted toward the electrode by the exciting pulse current. Then it springs downwards to the weld pool after the exciting pulse current switches to base current level. After a short period, the detaching pulse current is applied to detach the droplet.

The modified method results in several advantages. First, because the detaching current is applied after less than half the period of droplet oscillation, the time needed for each droplet detachment cycle is decreased significantly. The upper limit of the frequency is increased to 120 Hz, reaching the same range as conventional-pulsed GMAW process. Thus, the welding current range is enlarged, especially for thicker wire, which has a longer oscillation period (Ref. 17). Second, the exciting current decreases to 100 A, which is much smaller than that used by the previous method (140 A). The duration of the exciting pulse is not correspondingly increased. Therefore, the energy used for exciting the oscillation of the droplet decreases significantly and less heat input is produced by the exciting pulse. This characteristic is useful for many applications that need low input energy. Third, the controllability of the droplet detachment is improved. As shown in Fig. 11, in conventional-pulsed GMAW, the droplet is detached only by the electromagnetic force. There is a trade-off between the robustness and the high pulse current. In the previous active control method, the droplet is detached by electromagnetic force and downward momentum. With the assistance of the downward momentum, the requirement for the detaching current is decreased and the allowance of the detaching current is increased. Thus, the controllability is improved. However, because in the exciting pulse current, the droplet is dragged down by electromagnetic force, the energy difference that assists the droplet detachment is not large. In the modified active control method, the electromagnetic force caused by the exciting pulse lifts the droplet. Hence, the energy difference caused by the detaching action and the exciting action is

i i

I

i ~ • ~ L~nvclltlonal pulse

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Fig. 11 - - Comparison of controllability in different control methods.

0.8

0"7 I 0.6

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Fig. 12 - - Relationship between exciting pulse duration and oscillation amplitude of droplet. Exciting current is 100 A, electrode diameter is 0.9-mm "0. 035-in.) ERTi- 1.

250 •

a

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• " . . ]l • Detaching current needed for

stable droplet detachment

; ; ; ' ; ' ; 9 ~ ,

Fig. 13 - - Influence of time to apply detaching pulse on the required detaching current value in active detachment process.


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Fig. 14 - - Droplet transfer with 25-ram (l-in.) contact-tube-to-workpiece distance with modified active control, 400 frames per second.

Fig. 15 - - Droplet transfer with 12-mm (0.5- in.) contact-tube-to-workpiece distance with modified active control, 400 frames per second.

l 4

Fig. 16 - - Droplet transfer with 9-mm (0.36- in.) arc length with modified active control, 400 frames per second.

larger. This difference eases the preven- tion of accidental detachment. As a result, the controllability is increased further, and both the size and transfer instant of the droplet become more controllable. Fourth, the robustness of the

detachment process is improved because after the exciting pulse current switches to base current, the droplet must spring back due to surface tension. The detaching current is applied after a short period. The downward momentum

must be in phase with the detaching arc force. Therefore, this method eliminates the necessity for real-time monitoring and analysis of the oscillation process.

Experiments have also been conducted to investigate the influence of the exciting pulse period on oscillation amplitude. It was found that the exciting pulse current value determines the maximum amplitude of the droplet movement. As can be seen in Fig. 12, for a certain exciting current value and electrode diameter, there is an optimal exciting pulse period. If the exciting period is set at this optimal period, the droplet can be lifted to maximum amplitude. The exciting pulse current period has been set slightly higher than the optimal period to ensure robustness of the process in this study.

This study has also investigated the optimal time to apply the detaching current. It was found the time used in the previous active method is not optimal. As shown in Fig. 13, the needed detaching pulsed current for reliable detachment varies with the instant to apply it during the droplet's downward motion. At a certain instant, the needed detaching pulse current reaches minimum value. The phenomenon is complicated. Oscillation of the droplet is like as a vibration system with viscous damping. If the detaching pulse current is applied as soon as the droplet moves downwards, the velocity of the droplet is additionally accelerated, resulting in an excessive increase of the dump- ing force, which is proportional to velocity. Thus, excessive energy provided by the detaching current is consumed during downward movement of the droplet. In order to detach the droplet reliably, either higher detaching current or longer detaching period should be used. If the detaching force is applied too late, phase mismatch may occur. In the modified method, the detaching current is applied shortly after the current is switched to the base level, so the phase match is guaranteed. Also, the efficiency of the detaching pulse is improved and the need for detaching pulsed current is decreased.

Robustness

In order to demonstrate the stability of the modified active control method, experiments were conducted to investigate droplet transfer under varied conditions. Welding parameters selected as variables include arc length and contact-tube-to- workpiece distance because they have significant influence on the droplet transfer process. Additionally, they are prone to variations during production welding, especially in semiautomatic welding. Variation in contact-tube-to-workpiece distance and arc length changes the heat

60-s J FEBRUARY 2001

generation and arc efficiency. If the allowance of the controllability of a droplet is small, the process cannot withstand change of conditions. Multidroplet per pulse or multipulse per droplet mode wil l occur. However, with improved controllabil ity, the modif ied active control method does not have these problems. As shown in Figs. 14 and 15, with quite different contact-tube-to-workpiece distance, the droplet transfer process remains constant even though the heat generation conditions change. As seen in Figs. 1 6 and 17, the arc length changed from 9 mm (0.36 in.) to 3 mm (0.12 in.), but the active control method still detached the droplet constantly and reliably. The modified active control does withstand variation in the welding condition within a reasonable range.

Conclusions

By util izing active control technology, the robustness of the metal transfer process in GMAW of titanium is significantly improved in comparison with the conventional-pulsed GMAW process. The use of downward momentum decreases the peak current needed for constant ODPP process. The process is stable and free from spatter, which is highly desirable in GMAW welding of titanium.

The major difference between active control and modified active control lies in the method for oscillation generation. In active control, both the exciting and detaching pulses are selected to be at peak level. Hence, oscillation is generated by switching current from the peak level to the background level. The electromagnetic force corresponding to peak current is a detaching force. After the current is switched from peak level to background level, the droplet init ially moves toward the electrode. The detaching action can be taken only after half of the oscil lation cycle. Because oscillation depends on welding parameters such as material and diameter of the electrode, the oscillation process must be monitored. The system is complicated and robustness of the metal transfer depends on the reliability of the monitoring system. In the modified active control, the oscillation is generated by switching the current from the exciting pulse level to background level. Because the exciting pulse in this case is much lower than the detaching pulse, it can be so selected that the resultant electromagnetic force is a retaining force or support force. As a result, before the current is switched to the background level, the electromagnetic force pushes the droplet toward the electrode. After the current is switched, the droplet oscillates by immediately moving

Fig. 17 - - Droplet transfer with 3-mm (0.12- in.) arc length with modified active control, 400 frames per second.

toward the weld pool. Hence, the detaching pulse can be applied after a short period of time, and the phase match between oscillation a nd the detaching force is guaranteed. Consequently, the need to monitor oscil lation is eliminated. The control system is simplified and robustness is improved. Of course, because of the elimination of a half cycle of waiting time, the modified active control also im- proves the range of the metal transfer rate. Because modified active control inherits all other advantages of active control, modified active control is a better solution for applications where highly repeatable metal transfer is desirable.

Acknowledgment

The authors thank Thermal Arc, Inc., Troy, Ohio, for its technical and equipment support.

References

1. Pagnotta, G., and Hume, G. W. 1963. Welding thin-walled titanium pressure vessels. Welding Journal 42(9): 709-714.

2. Rolston, P. W., Chandley, G. D., and Adams, C. M., Jr. 1962. Fabrication of a titanium tank cupola. Welding Journal 41 (2): 128-134.

3. Johnson, M. M., and Roseman, P. 1964. Titanium joins the family of commonly used metals. Welding Journal 43(4): 267-274.

4. Eickhoff, S. T., and Eagar, T. W. 1990. Characterization of spatter in low-current GMAW of titanium alloy plate. Welding Jour- nal 69(10): 382-s to 388-s.

5. Stark, L. E., Bartolo, L. J., and Porter, H. G. 1962. Welding on one-inch-thick Ti-6AI- 4V plate. Welding Journal 41 (9): 805-814.

6. Wolf, R. J., Nagler, H., Crisci, J. R., and Frank, A. L. 1965. Out-of-chamber welding of Ti-7AI-2Cb-ITa alloy titanium plate. Welding Journal 49(10): 443-s to 457-s.

7. Stark, L. E. 1966. Weldability of Ti-7AI- 2Cb-1Ta plate. Welding Journal 50(2): 70-s to 81 -s.

8. Mitchell, D. R., and Feige, N. G. 1967. Welding of alpha-beta titanium alloys in one- inch plate. Welding Journal 46(5): 193-s to 202-s.

9. Ueguri, S., Hara, K., and Komura, H. 1985. Study of metal transfer in pulsed GMA welding. Welding Journal64(8): 242-s to 250-s.

10. Allum, C. J., 1985. Welding technology data: pulsed MIG welding. Welding and Metal Fabrication 53: 24-30.

11. Salter, G. R., and Scott, M. H. 1967. The pulsed inert gas metal arc welding of 1- in.-thick titanium 721 alloy. Welding Journal 46(4): 154-s to 167-s.

12. Ries, D. E. 1983. Gas metal arc welding in titanium. Master's thesis. MIT, Depart- ment of Materials Science and Engineering, Cambridge, Mass.

13. Kim, Y. S., 1989. Metal transfer in gas metal arc welding. Ph.D thesis. MIT, Cam- bridge, Mass.

14. Amin, M., 1983. Pulse current parameters for arc stability and controlled metal transfer in arc welding. Metal Construction 15: 272-278.

15. Ma, J. and Apps, R. L., 1983. Analyz- ing metal transfer during MIG welding. Weld- ing and Metal Fabrication 51 : 119-128.

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21. Amson, J. C. 1965. Lorentz force in the molten tip of an arc electrode. British J. Appl. Phys. 16:1169-1179.


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