March 28, 2013

Economics of Advanced Welding Techniques

Stephen LevesqueDirector, EWI Nuclear Fabrication CenterEmail: slevesque@ewi.org Office: 614-688-5183Mobile: 614-284-5426

Nuclear Fabrication Consortium Some information in this presentation was based

upon research funded by the US Department of Energy through the Nuclear Fabrication Consortium (operated by EWI)

The Nuclear Fabrication Consortium (NFC) was established to independently develop fabrication approaches and data that support the re-establishment of a vibrant US nuclear industry

Overview Laser Welding

─ Process description (Laser and Hybrid Laser Technologies)─ Potential applications─ Cost benefit

Friction Stir Welding─ Process description─ Potential applications─ Cost benefit

Cladding Technologies─ Comparison of various technologies

Tandem GMAW (bonus)

Laser Welding

Laser Background Solid-state laser technology is rapidly

advancing ─ Output powers are continuously increasing─ Price per kilowatt is dropping

(~$750K for 20-kW)─ Improved portability and electrical efficiency─ Improved beam quality – fiber deliverable

Two laser technologies primarily responsible─ Fiber Laser (IPG Photonics)─ Disk Laser (Trumpf)

ROI for laser processing is becoming more attractive─ Cost/watt, cycle time, penetration, distortion

Advantages and Challenges The main advantages of laser

processing include:─ High productivity─ Low heat input─ Minimal distortion

Some challenges include:─ Critical joint preparation due to

limited gap bridging─ Increased capital cost compared to

traditional arc-welding equipment

0.005-in. gap 0.010-in. gap 0.015-in. gap

General Terminology Autogenous Laser Welding

Shielding gas

Laser Beam

Laser-Induced Vapor Plume

Laser Keyhole

or Vapor Cavity

Liquid Weld Pool

Solidified Weld Metal

General Terminology Hybrid Laser-Arc Welding (Hybrid Welding)

─ The combination of two welding processes in the same weld pool

─ Most often GMAW and Laser Welding

Laser Beam

GMAW Torch

“Arc-Leading” HLAW“Laser-Leading” HLAW

Hybrid Terminology The HLAW process can be used in two orientations:

High-level cost model built by EWI Assumes 1 min. of arc time for GTAW and 2 sec. of laser

time per tube Varied process efficiency to evaluate the ROI

0 20000 40000 60000 80000 100000$0

$50,000

$100,000

$150,000

$200,000

$250,000

$300,000

$350,000

$400,000

$450,000

$500,000

$550,000

2kW Laser @ 50%

Manual GTAW @ 50%

Orbital GTAW @ 75%

Robotic GTAW @ 80%

Number of Tubes

Estim

ated

Cos

t

Laser Tube Sheet Welding

Laser Tube Sheet Welding

Containment Welding Hybrid Laser-GMAW welding vs. Tandem GMAW vs.

Submerged Arc Welding

Productivity For one weldment X long

"10" 50-in Parts

"10" 200-in Parts

Hours

SAW 11 27

Tandem 8 18

HLAW 15 16

Includes setup time and weld time

Cost Comparison

"10" 60-in Parts

"10" 200-in Parts

Dollars

SAW $48k $124k

Tandem $38k $84k

HLAW $69k $72k

For one weldment X long

Equipment Cost

SAW $55k

Tandem $150k

HLAW $950k

Includes setup time/weld time

(@$75/hr) and filler metal cost

Combined Comparison Data

200-in

Other Benefits Peak Temperature Models showing reduction in heat

input

SAW

GMAW-T

HLAW

Distortion and Residual StressSAW Tandem HLAW

Friction Stir Welding

Friction Stir Welding Invented by TWI in 1991

─ Wayne Thomas Solid-state joining process

─ No bulk melting of the substrate Capable of joining

─ Aluminum, Magnesium, Copper, Steel, Titanium, Nickel, many more

Non-consumable tool rotates and traverses along a joint

─ Combination of frictional heating and strain causes dynamic recrystallization

─ Adiabatic heating Creates a very fine grain microstructure

─ Low distortion─ Excellent weld properties

Friction Stir Welding Variables Essential FSW variables

─ Vertical (Forge) force, Fz

─ RPM, ─ Travel (Traverse) speed, Vf

Process forces─ Travel (Traverse) force, Fx

─ Cross (Transverse) force, Fy

─ Vertical (Forge) force, Fz

Fx Fy

FzVf

Fx Fy

FzVf

Fx Fy

FzVf

Fx Fy

FzVf

Fx Fy

FzVf

Fx Fy

FzVf

Fx Fy

FzVf

Fx Fy

FzVf

Fx Fy

FzVf

Fx Fy

FzVf

FxFy

FzVf

Fx

Fy

FzVf

Ref: Arbegast, William J., "Week 2 Friction Stir Joining: Process Optimization." (2003).

Friction Stir Welding

Local Clamp

FSW Tool

Main Spindle

Fixturing

FSW Economics FSW of Aluminum

─ 15% reduction in man-hour per ton rate in aluminum panel fabrication – Hydro Aluminum

─ Total fabrication savings of 10% in shipbuilding - Fjellstrand─ 60% cost savings on Delta II and IV rockets – Boeing─ 400% improvement in cycle time for fabricating 25mm thick

plates – General Dynamics Land Systems FSW of Steel Pipeline

─ Estimated cost savings ─ Onshore construction, 7%─ Offshore construction (J-Lay), 25%

- Kallee, S. W. (2010). Industrial Applications of Friction Stir Welding. In D. Lohwasser, & Z. Chen, Friction Stir Welding From Basics to Applications (pp. 118-163). Boca Raton: CRC Press.- Kumar, A., Fairchild, D. P., Macia, M., Anderson, T. D., Jin, H. W., Ayer, R., . . . Mueller, R. R. (2011). Evaluation of Economic Incentives and Weld Properties for Welding Steel Pipelines Using Friction Stir Welding.Proceedings of the Twenty-first (2011) INternational Offshore and Polar Engineering Conference (pp. 460-467). Maui: ISOPE.

FSW of Steel Cost Model Assumptions

─ Plain carbon steel─ Simple butt joint configuration─ Use of EWI DuraStir™ tools─ Machine and fixturing purpose built for assumed application─ Range of thicknesses

─ 3, 6, 9, 12, 16, 19 mm─ Broken down in terms of cost/meter based upon weld length

achievable each month

FSW Cost SummaryCost Summary

                 Thickness   3.00 (mm) 6.00 (mm) 9.00 (mm) 12.00 (mm) 16.00 (mm) 19.00 (mm)

                 

Production Costs:   $246.31/m $307.24/m $373.45/m $444.94/m $531.46/m $613.51/mFixed Costs:   $18.12/m $21.44/m $27.94/m $28.31/m $40.52/m $53.20/mVariable Costs:   $36.46/m $41.32/m $62.65/m $83.29/m $127.46/m $306.23/m                 Total Cost Per Meter: $300.88/m $370.00/m $464.05/m $556.55/m $699.44/m $972.94/m

Cladding

Introduction Many process options exist for weld cladding

and hardfacing A number of factors should be considered when

selecting a process: ─ Desired deposition rate─ Required dilution level─ Welding position─ Component size/geometry─ Method of application

─ Manual/semi-automatic─ Mechanized─ Automated

─ Welder/operator skill─ Alloy/material to be

deposited─ Equipment cost

Available Processes for Surfacing Include Thermal spray Resistance cladding Laser cladding Gas tungsten arc welding (GTAW) Plasma arc welding (PAW) Gas metal arc welding (GMAW) Submerged arc welding (SAW)

─ Single and multi-wire SAW─ Submerged arc strip cladding─ Electroslag strip cladding

Explosion welding

Resistance Cladding Uses Simple off the shelf sheet material and may use

interlayers to make a fusion type weld between CRA and Pipe

Can make the clad weld in one pass Uses sheet metal consumables which are much

lower cost than wire consumables Post weld surface finish should meet customer

requirements No dilution of base metal into CRA surface

Resistance Cladding

Current Cladding Techiques Explosive Welding $$$$

─ Requires post cladding longitudinal seam weld which impacts fatigue

Roll Bonding ─ Requires post clad longitudinal seam weld

GMAW / GTAW / SAW welding─ Processing time intensive with inspectability issues

Liner Expansion (lowest cost)─ Risk of liner buckling is concerning to customers during

installation or dynamic lines

Resistance Cladding Cost comparison

CRA Piping

Expanded Liner Pipe

Roll Bonded Pipe

RSEW Pipe

0 20 40 60 80 100 120

Normalized Price Per Unit

Tandem GMAW Bonus Material

Why Use Tandem GMAW? Improve Productivity and

Quality─ Increased deposition rates─ Faster travel speeds─ Maintain or improve overall

weld quality, gap filling capability

Deposition rate (lbs/hr)

Image courtesy of Lincoln Electric

Example 5.25-in.-thick test joint 0.5-in.wide groove 2° included angle Travel speed: 15 ipm Heat input: 46 kJ/in. Single bead per layer 27 passes required to fill

4.5 in. Fill height per pass ≈ 0.17 in. Clean UT results