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MATERIALS DATA HANDBOOK __ _ t.c_

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June 197Z _ _"i

Prepared for _ "_.,.&-4

\National Aerona_ic_ and Space Administration

:: George C. Marshall Space Flight Center _ _ z

Mar_hall Space Flight Center, Alabama 3581Z o_°_ _,

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Contract NAS8-26644 tu

: WESTERN APPLIED RESEARCH & DEVELOPMENT, INC.DIL

_:-, 1403-07 Industrial Road San Carlos, California 94070

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https://ntrs.nasa.gov/search.jsp?R=19720022813 2018-05-20T10:42:50+00:00Z

PREFACE

This Materials Data Handbook on stainless steel alloy A_Z86 was, prepared by Western Applied Research _ Development, Inc. under contract

_'ith the National Aeronautics and Space Administration, George C. Mar-shall Space Flight Center, Marshall Space Flight Center, Alabama.

It is intended that this Handbook present, in the form of a singledocument, a summary of the materials property information presentlyavailable on alloy A-286.

The Handbook is divided into twelve (12) chapters. The scope ofthe information presented includes physical and mechanical property dataat cryogenic, ambient, and elevated temperatures, supplemented withuseful information in such areas as material procurement, metallurgyof the alloy, corrosion, environmental effects, fabrication and joiningtechniques. Design data are presented, as available, and these data arecomplemented with information on the typical behavior of the alloy. The

• major source used for the design data is the Department of Defense doc-ument, Military Handbook-5A.

Information on the alloy is given in the form of tables and figures,_ supplemented with descriptive text as appropriate. Source references

for the information presented are listed at the end of each chapter.

Throughout the text, tables, and figures, common engineering units(with which measurements were made) are accompanied by conversions to

International (SI) Units, except in the instances where double units would

over-complicate data presentation, or "vhere SI units are impractical (e. g.,machine tools and machining). In these instances, conversion factors arenoted. A primary exception to the use of SI units is the conversion of 1000pounds per square inch to kilograms per square millimeter rather thannewtons, in agreement with the ASTM that this unit is of a more practicalnature for worldwide use.

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ACNOWLEDGMENTS

This "Materials Data Handbook: Stainless Steel A]_loyA-286 I_wasprepared by Western Applied Research & Development, Inc. under Con-tract No. NAS8-26644 for the George C. Marshall Space Flight Center ofthe National Aeronautics and Space Administration. The work was admin-istered under the technicaldirection of the Astronautics Laboratory,Materials Division of the George C. Marshall Space Flight Center withMr. Wayne R. Morgan acting as Project Manager.

Sincere appreciation istendered to the many commercial organ-izationsand Government agencies who have assisted in the preparationof this document.

IL

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TABLE OF CONTENTS

Preface .......................................... i

Acknowledgments ......... ii

Table of Contents ........................................... iiir

Tabular Abstract ....................... iv

Symbols - - v

Conversion Factor s viii

Chapter 1 General Information .................. 1

Chapter Z Procurement Informat_.on ....... 3

Chapter 3 Metallurgy ............. 7

Chapter 4 Production Practices ........... Z3

_ Chapter 5 Manu.'acturing Practices ....................... Z95.

_ Chapter 6 Space Environment Effects ................ 354- "''''

Chapter 7 Static Mechanical Properties ................... 41

_ Chapter 8 Dynamic and Time Dependent Properties ........ 61

Chapter 9 Physical Properties ................ 75

Chapter 10 Corrosion l%esistance and Protection ............ 79

Chapter II Surface Treatments ........................... 83

Chapter IZ Joining Technique_ - .......................--- - 87

• ,,. llt

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TABULAR ABSTRACT

Stainless Steel Alloy A-286

TYPE:

Precipitation hardenS, g, heat treatable, austenitic _tainless steel

NOMINAL COMPOSITION:

Fe-15Cr-Z5Ni-Z. ITi-I. ZMo-0. ZA/

AVAILABILITY:

Sheet, plate, bar, tubing, forgings, cast, .gs, wire, rivets, bolts,and screws

TYPICAL PH_/SICAL PROPERTIES:

Density 7.94 g/cm s at room temperatureThermal Conductivity 0. 057 cal/cm _/sec/cm/° C at 6000 CAv. Coeff. of Thermal Exapnsion -- 17.0 _cm/cm/°C at 600°CSpecific Heat 0.II callcm _ °C (Z0--700°C)Electrical Resistivity 91.0 microhm-cm at 30.6°C

?

TYPICAL MECHANICAL PROPERTIES: _"

JFtu, 1800°F (98Z°C) plus ages .... 145 ksi (10Z ks/turn _)1650°F (899vC) plus age ..... 157 ksi (110 kg/mm _)

Ft,,, 1800°F plus age 95 ksi (67 kg/rnn_ z)

1650°F plus a_e ............ 10Z ksi (7Z kg/mm s)• e(Z in or 4D), 1800 F plus age .... Z4 percent

1650°F plus age .... 25 percent_ E (tension) --- Z9.1 x l0 s ksi (ZO. 5 x I0 s kglmrn a)

_ FABRICATION CHARACTERISTICS:

f Weldability ............. More difficult than austenitic et_Inles ssteels; easiest of PH stainless steels

_, (fusion and resistance methods)•, Formability .................... Similar to austenltic steels, but

slightly more resistantMachlnabLlity .................. Same as for 300 series of stalniess @steels, but at slower rates

_ COMMENTS:

_/ A superaL1oy, with high strength, good resistance to corrosion and oxld-_: ation, and low relaxation, for service at temperatm'es as high as 1300i OF (704 o C); also excellent properties mt cryogenic temperatures.

,1,1325°F (718°C)

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L

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SYMBOLS

a One-half notch section dimensionA Area of cross section; "A" basis for mechanical

property values (MIL-HDBK-5A)Angstrom unit

AC Air coolAIVIS Aerospace M_terial SpecificationsAnn Annealed

ASTM American Society for Testing MethodsA_, or Avg Average

B "B" basis for mechanical property values (MIL-HDBK-SA)

' b Subscript "bending"bcc Body centered cubicBHN Br inell hardne s s numberbr Subscript "bearing"

Btu British thermal unit(s)

_,._: °C Degree(s) Celsius:_' c Subscript "compression"ll CD Cold drawn

i CF Cold finished: cm Centimeter

Specific heatCold rolledCW Cold workedCVM Consumable vacuum melted

D or Dis DiameterDPH Diamond pyramid hardnes s

• Elongation in percentE Modulus of elasticity, tension

_" E c Modulus of elasticity, compressione/D Ratio of edge distance tc hole diameterE s Sccant modulus

• Et Tangent moduluseV Electron volt(s)

0 F _egree(s) Fahrenheit

_ru Subscript "ffatigue"Bearing ultimate strength

Fb_y Bearing yield strength

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1

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fcc Face centered cubicFC Furnace cool

FFcy Compressive yield strengthsu Shear stress; shear strength

Ftu Ultimate tensile strengthFty O. 2% tensile yield strength (unless otherwise indicated)

g Gram tG Modulus of rigidity

HAZ Heat affectedzone in weldments

hcp Hexagonal close packhr Hour(s)HT Heat treat

IACS International annealed copper standardin Inch

iprn Inches per minute

o K Degree(s) KelvinK Stress intensity factor; thermal conductivityKc Measure of fracture toughness (plane stress) at point of

crack growth instabilitykg KilogramKlc Plane strain fracture toughness valueksi Thousand pounds per square inch

Kt Theoretical elastic stress concentration factor

L Longitudinallb PoundLT Long transverse (same as transverse)

M Bending momentm MeterM Subscript "mean"

Maximumml MilliliterMIL MilitaryMin Minimummm Millimeter

@

N Cycles to _ailureNSR Notch strength ratioNTS Notch tensile strength

OG Oil quench

ppm Parts per million

pt Point; part vtI

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r RadiusRA Reduction in area; Rockwell hardness A scaleRB Rockwell hardness B scaleRC Rockwell hardiless C scale

rpm Revolutions per minuteRT Room temperature

SA Solution annealsec Second

S-N S = stress; N = number of cyclesSpec Specifications;specimenST Solution treat;short trans .'erseSTA Solution treated and aged

T Transverset Thickness; timeTemp Temperaturetyp Typical

Var VariableVHN Vickers hardness number

W Width

'_; WG Water quench¢,

_p

b F

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CONVERSION FACTORS

To Convert To Multiply By

angstrom units millimeters I x 10-7l

Btu/lb/° F cal/g/o C 1

Btu/ftZ /sec/°F-inch cal/g/cm_ /sec/°C-cm 1.2404

circular rail square centimeters 5.0_,7 075 x I0 -s

cubic feet cubic meters 0. 028 317

cubic feet/minute liters/second 0. 4720

cubic inches cubic centimeters 16. 387 162

feet meters 0. 304 800 609 :

foot-pounds kilogram-meters 0.138 255

gallons (U.S.) liters _. 785 411 784

inches millimeters 25.4

ksi (thousand pounds kilograms/square millimeter 0. 70307per square inch

microns millimeters 0. 001

mils millimeter s 0. 0254

ounces (avoir.) grams 28. 349 527

' ounces (U.S. fluid) rnLUiliters 29. 5729

pounds (avoir.) kilograms 0. 453 592 37

' pounds/foot kilograms/meter I. 488 16

pounds/cubic foot grams/cubic centimeter 0. 016 018 463 i

Isquare feet (U. S. ) square met ers 0. 092 903 41

square inches (U. S. ) square centimeters 6.451 625 8

_ Temperature in °C = (o F- 32) (5/9) @Temperature in OK - °C + 273.15

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Chapter 1

GENERAL INFORMATION

1.1 Alloy A-Z86 is a precipitation-hardening, heat-treatable, austeniticstainless steel developed as an improvement on the German alloy

"Tinidur." As a "superalloy" or "heat-resistant alloy," it has beendesigned for service at temperatures as high as 1300 F (704°C) forapplications requiring high strength and good resistance tc corrosionat operating temperatures, and for service at higher temperatureswhere applications are at lower stresses.

l.Z Hot-working characte_iotics resemble those of other stainless steelsrather than other superalloys. Machinability of .A-286 is similar tothat of other austeniticsteels, including"gumrning," in the soft solution-tre-_tedcondition. The alloy is welded readily by shielded-arc andinert-gas-arc techniques; however, itis recommended that the mat-erial be in an essentiallystress-free solution-treatedconditionpriorto welding.

1.3 Good resistance has been shown against all atmospheres encountered

in jet engines and turbo supercharger service up to at least 1300°F(104°C). Excellent performance is shown in Z0-percent salt spraycorrosion tests. The high nickel content affords more resistance to

dilute, cool sulfuric acid solutions than 18-8 stainless steels.

I. 4 Typical areas of application include structures for jet engines andq

_ superchargers, turbine wheels and blades, frames, castings, and_ afterburner parts. Alloy A-286 is particularly attractive for applic-

ations as fasteners and springs for elevated-temperature servicebecause of relatively low stress-relaxation or loss of load inoperations

1.5 Precautions. Intergranular corrosion may occur in the aged condition,

and c_tre must be used in pickling with HNO3--HF solutions afteraging. Resistance to corrosion is _ot good in strong, selective en-vironments such as in HNOs--HF mixtures and boiling 65 percentsulfuric acid.

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.P. "ll

Chapter 1 - References

1.1 American Iron and Steel Institute,"High-Temperature High-StrengthAlloys," AISI, February 1963.

I.Z Alloy Digest, "Allegheny A-Z8_." (FilingCode SS-4), EngineeringA/loys Digest, Inc., New Jersey, D_cember 1952.

1.3 ASTMSTP-160, "A-286 Alloy," A_gusL 1954, p. 70.

I.4 Allegheny Ludlum Steel Corporation, t_A-Z86,'vProd-tctBulletin.

I.5 Carpenter Tl_chnology Corporation, B_Carpenter A-286," TechnicalData, June 1970.

I.6 Univera1-Cyclops/Speciadty Steel Division, "Unitemp A-286, 'tHT-3020, 1971.

1 7 Superior Tube, "Super Alloy Tubing," Bulletin71, Jtme I%8.

I. 8 J.G. Sessler and H.G. Weiss, Eds., "Aerospace Structural MetalsHandbook," AFML TR 68-115, 1971 Edition, Vol. I.

I. 9 DMIC Memorandum Z45, "Current and Future Usage of Niaterialsin Aircraft Gas Tu._bine Engines," Febcuary I, 1970.

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o ._ib

Chapter g

PROCUREMENT INFORMATION

2. i General

Alloy A°Z86 is available as billets, bars, forgings, sheet, plate,strip, shapes, and tubing (refs. _.. 1 through 2.5).

2.11 Alternate designation. American Iron and Steel Institute, AISI 660.

2.2 Procurement Specifications

AMS specifications that apply specifically to A-286 are listed intable 2.2. There are no specific Military or ASTM specifications.

Z.3 Ma_or Producers of the Alloy (United States only) include:

A- _.Su Allegheny Ludlum Steel CorporationAltemp _ cOliver BuildingPittsburgh, Pennsylvania

_ Carpenter A-280 Carpenter Technology Corporation.... 150 W. Bern Street

_ Reading, Pennsylvania

A° Z86 Republic Steel Corpor ation ,Special Metals DivisionMas silon, Ohio

A-286 Superior Tube1938 Germantown Avenue

Norristown, Pennsylvania

Uniternp A-286 Universa_Z.yclops Specialty Steel Division650 Washington RoadPittsburgh, Pennsylvania

Z.4 Available Forms, Sizes_ and Conditions

See table Z. 2 for information on available forms and conditions.Consult producers for details on available size8 and purchaseinformation.

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-._

TABLE 2.2. --AhiS Specifications for Various Forms of Alloy

Source Ref. 2.6

Alloy A-Z86

Spec. No. Item Condition

5525C Sheet, strip, and plate Sol HT

5731D Bars,forgings, tubing, Cons elec melted, 1800°F(982°C)and rings sol treated

573ZC Bars,forgings, tubing Cons elec melted, 1800°F(982°C)and rings sol and prec treated

5734C Bars, forgings,and Cons elec melted, 1650° F(899°C)tubing sol HT

5735G Bars,forgings, tubing, 1800°F(98Z°C) sol and prec HTand rings

5736F Bars, forgings,tubing, 1800°F(982°C) sol treatedand rings

5737E Bars, forgings,and Cons elec melted, 1650° F(899°C)tubing sol HT and prec HT

5804B Welding wire Cold drawn, as drawn

5805B Welding wire Vac melted, cold drawn, as drawn

7235A Rivets 1650°F(899°C) sol and partialprec HT

7477B Bolts and screws Upset headed, HT, roll-threaded,; sol and prec HT

_ 7478G Bolts and screws HT, roll-threaded, sol and prec HT

: 7479C Bolts and screws HT, roll-threaded, 1650 °F(899 °C) HT

7481A Studs HT, roll-threaded

74903 Rings, flash-welded --=l

Note: Specifications as of May 1971.

4

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Chapter 2 - References

Z. I Alloy Diges___t,"Allegheny A-Z86," (Filing Code SS-4), EngineeringAlloys Digest, Inc., New Jersey, December 1952.

2.2 Allegheny Ludlum Steel Corp., "A-Z86," Product Bulletin.

2.3 Superior Tube, "Super Alloy Tubing," Bulletin 71, June 1968.

2.4 Carpenter Technology Corp., "Unitemp A-Z86," Technical Data,June 1970.

2.5 Universal-Cyclops Specialty Steel Div., "Unitemp A-286," HT-

3020, 1971.

2.6 Aerospace Material Specifications, Society Automotive Engineers,Inc., New York; late=L Index, May 1971.

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Chapter 3

CMETALLURGY ,,R_C_[;!NG PA,E BI,ANK NOT FU,MYV_'

3. I Chemical Composition

3.11 Nominal chemical composition. Published values for "ty%_cal chem-ical composition" (refs. 3. Z-3.13) have been averaged and rQundedto province the nominal chemical composition in percent listed below:

C 0.05 Mo 1. ?.0IVm I.33 Ti 2.14S_. 0.55 B 0.0005Cr 15.0 V 0.26Ni 25.4 A1 0.21 -,

Fe Balance .....-__\

3.12 Chemicai composition range. The ranges of element concentration _,_in peruent listed below have been d_ rived from the highest and lowest _.values reported as typical chemical compositions or ranges (refs.3. ?.-3.16):

C 0.05 - 0.08 Ni 24.0 - 27.0Mn 1 00 - 2.00 Mo 1.0 - 1.75Si 0.40 - 1.00 Ti 1.75 - 2.60P 0.02 - 0.04 B 0.00Z- 0.015

• S 0.01 - 0.02 V 0.I0- 0.50Cr 13.5 - 16.0 A1 0.16 - 0.36

Fe Balance

3.13 Chemical composition limits. A/viS specified composition limitsfor A-286 are given in table 3.13 according to the requirementsfor various forms.

3.14 Alloying elements. The principal alloying elements are nickel andchromium. Phase diagrams for the iron-chromium-nickel system

. at room and elevated temperatures are given in figure 3.14.

The nickel provides strenghtening, stabilizes the fcc matrix, formsy' and inhibits formation of deleterious phases; it is present in suf-

_" flcient quantity to favor the austenitic structure and to reduce thetemperature at which austenite transforms to martensite so that theaustenite is re_ained on cooling to room temperature and even to

' cryogenic temperat'ares. Chromium provides resistance to oxidationas we]/as solid-_ulution strengthening (refs. 3.8, 3.17).

Aluminum and titanium are the primary hardener elements. Bysuitable heat treatment, they precipitate lntermetallic phases suchas ordered fcc y' _is(Ti, A1)] from the matrix to provide high proof-stress at elevated temperatures (refs. 3.4, 3.8, 3.18).

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2 Stren_thenin$ Mechanisms

3.21 General. Optimum properties of A-286 are obtained by heat treatingand aging (precipitation hardening). Thus, it is not necessary to workit in the temperature range of 10O0 ° to 1500°F (538 ° to 816°C) toproduce high yield strengths as is required for other high-temperaturealloys. (However, cold working affects some properties after agingso that modified heat treatments may be required. ) Solution treat-ment at 1800°F (98Z°C)provides optimum stress-rupture propertiesafter aging; solution treatment at 1650°F (899°C) provides maximumroom temperature yield strength or short-time properties. Aftersolution treating, A-Z86 is soft (about 150--160 BHN) and is in itsmost ductile condition. Aging at 1300°--1400°F (704°--760°C) resultsin an increase of hardness to 260--340 BHN. The high strength of thealloy is developed during the aging treatment by the random form-ation of a fine precipitate of [Ni 3 (Ti, A.I)] in the austenitic matrix(Refs. 3.3, 3.5, 3.6, 3.9, 3.15, 3.19).

3.22 Precipitation Hardenin$. A great number of investigations have beenmade on the strengthening mechanisms and microstructure of iron-base superalloys such as A-286. In one of these _tudies (ref. 3.20),it was shown that (a)A small A1 content (up to 1 percent) increasesthe amount of age hardening of a Ti-bearing steel, but further addi-tions decrease the amount; (b) Increase of Ti content at any A1 con-tent increases age hardening; (c) The amount of aging in a Ni-A1-Tisteel is greater thin can be obtained with the single addition of sim-ilar amounts of A1 and Ti; (d) The optimum composition for a 25Ni-15Cr steel would contain 1 percent A1 and 2.5 percent Ti. The

:_ precipitating phase for this cc._. position was identified as Niq(A1, Ti).

In a study of the mechanical properties of austenitic steels contain-s" ing y' precipitate [Ni3(Ti , A1)] , it was determined that a large in-

crease in proof-stress occurs during aging as a result of particlegrowth at almost constant volume fraction of precipitate. Up to thepeak proof-stress, dislocations are paired because of the high anti-phase-domain boundary energy, and this accounts satisfactorilyfor the increasing proof-stress. The value of the antiphase domainboundary energy is higher at higher Ti/AI ratios. Misfits between0 and 0.4 percent have no effect on yield strength. During an Ors-wan looping process, which bypasses large particle,% a transitionoccurs from paired to single dislocations that reduces the fall instress with increasing particle size. A back stress detectable atlow strains arises from stable Orowan loops and causes work-hardening..t/.ore marked work-hardening associated with debrisin the slip planes is shown by alloys with high TI/AI ratios (e. g.,A-286), apparently a result of bypassing of particles by cross-slipwhich gives rise to con_plex slip interactions (ref. 3.4).

Aging at about 700°C causes the formation of the desirable strength-enlng _' phase _fqla (Ti, A1)]. However, aging at higher temperatures,for example. 800uC., or overaging, can cause the formation of a

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cellular precipitate, hexagonal 1] Ni3 Ti. A large amount of the 1]phase is considered undesirable because it leads to low ductility,particularly creep ductility (refs. 3.8, 3.20). In overaged alloys,deformation has caused the loss of coherency between the y' andthe austenite; slip was observed primarily in the _,'-austenite regions,but fracture of the cellular colonies was observed at large deform-ations (ref. 3.21). On the other hand, cellular precipitation can beconsidered a fairly stable form of dispersion hardening and thus showresistance to overaging, which can be useful _n maintaining high-strength levels after aging or during testing at elevated temperatures(ref. 3.20). It has been suggested that the _ Ni 3Tiphase be used toadvantage to control the microstructure and properties of super-alloys (ref. B. 11).

3.23 Solid- Solut ..on Stren_then_.n_. It has been shown that solid-solutionhardening is slight with respect to room-temperature properties ofA-286. However, the presence of certain elements in the alloy canpromote the strengthening of properties at elevated temperatures.These elements, generally interstitial in nature, also alter the latticeparameter of the fcc matrix, and thus the degree of hardening pro-duced by a precipitate can be affected by means of the magnitude ofdeveloped coherency strains. For example, boron retards formationof _) and markedly improves stress-rupture properties. Molybdenumand chromium are also solid-solution strengtheners (refs. 3.8, 3.18,3.zo).

3. Z4 Heat Treatment. The strength of alloy A-286 is obtained by a solutionheat treatment (annealing) followed by an aging (precipitation harden-ing) treatment. Recor_nended treatments are given in the following

" subsections (refs. 3.1, 3.6, 3.15, 3.19).

3. 241 Solution treatment for optimum stress-rupture properties.Bars and forgings: heat to 1800°F (982°C), hold 1 hr at heat,

" cool rapidly.t_ Sheet and strip: heat to 1800°F (98Z°C), hold for 1 hr per inch:: (25.4 ram) of thickness, cool rapidly.

Large sections are oil- or water-quenched from the solutiontemperature. Sheet and strip may be water quenched or fan cooledif distortion must be held to a minimum.

3. 242 Solution treatment for optimum short-time tensile properties.Heat to 1650°F (899°C), hold I to 2 hours at heat, cc_ol rapidly.

3. Z43 Aging treatment.' Heat to 13000 to 1400°F (7040 to 760°C), hold 12 to 16 hours at heat

and cool rapidly. A temperature of 1325°F (718°C) is generally used.

3. Z44 The effect of age-hardening on the properties of A-286 sheet at cryo-genic temper;_tures is illustrated in figure 3. 244.

m 9f,

i ....

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3.25 Cold _Norking. Alloy A-286 may also be strengthened by cold workingprior to aglng; for example, tensile strengths of 150 to about 220 ksi{105 to 155 kg/mm _) are developed by cold reducing in amounts up to60 percent and then aging in the range lZ00° to1300°F (6470to704°C).As a general rule, as the amount of cold work is increased, the agingtemperature should be lowered for ma_.imum hardness and short-timetensile strength. Cold working affectsmechanical properties becauseof its influence on grain-size growth and the reaction kinetics of aging.The critical amount of cold work must exceed 1 to 6 percent to avoidthe growth of abnormally large grains. As far as the rate of harden-ing is concerned, A-286 may be redt_ced as much as 90 percent be-fore a _oftening treatment is required (refs. 3.6, 3.19). The effectof cold working on room-ten.perature tensile strength of A-286 com-pared with stainless steel Type 302 is shown in figure 3.25.

3. 251 The effect of aging temperatare and cold-reduction on the hardness ofA-286 i_ illustrated in figure 3. 251. The effect of cold reduction andaging temperature on the tensile properties of A-286 is presented intable 3.Z51.

3. 252 A double-aging treatment, that is, aging temperatures higher thannormal followed by a second aging cycle at temperatures lower thannormal, is somtimes used to obtain uniformity of properties in partsthat have been cold-worked nonuniformly. In these instances, forA-286 parts with varying amounts of cold work, double-aging at1400 ° F (760 ° C) and 1300 oF (704 ° C), respectively, provides more iuniform short-time tensile properties, hardness, and creep ruptureproperties than the usual single aging treatment at 1325uF (718°C);structural stability of the part in service is also improved (ref. 3.19).An ex_.mple of the effect of double aging is given in table 3. 252.

3.26 Stress Relief. Heat-resistant alloys, such as A-286, cannot be stress-relieved because the intermediate temperatures result in aging. Hence,in order to restore ductility and reduce stresses in cold-formed partsand weldments, the alloy is heated rapidly to the annealing (solution-treating) temperate. In forgings, finishing temperat_tre is usuallyabove 1700_F (926uC) so that stress-relieving is not required for as-

i forged parts (ref. 3.19).

i 3.3 Critical Tempers.tures

i Melting range, 1371°--1426°C (2500°-q.bO0°F) (refs. 3.6. 3.9). •Intermetallic precipitation reaction, 750 _ to 800°C (1382°--1472°F)(ref. 3.20).

3.4 Crystal Str .uc.ture/,_ Alloy A-286 has a face-centered-cubic (fcc) matrix (austenite) strength-

ened by gamma prime precipitation, with a tendency to form topolog-ically close packed phases such as sigma, mu, Laves, and chl (refs.

:_ 3.8, 3.13). .The properties of precipitated tntermetallic phases are>_ given in talfle 3.4.

f

10

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3.5 Microstructure

General. The structure of the austenitic solid solution in A-Z86 ismodified by most of the elements added for precipitation hardening,and there is some correlation of lattice parameter with atomic sizeof the substitutional element. The size effect is _mportant to solidsolution strengthening and affords control by d_iiberate mismatchof alloying _lements over the coherency strains resulting irom pre-cipitation hardening. Aluminum and titanium are potent substitutionalelements. There is a propensity for stacking faults in A-Z86, althoughdislocation content is low. Stacking fault energy is lowered by chrom-ium, molybdenum, and titanium, and increased by nicI_el. The effectsof stacking fault changes will be seen in the nucleation and growth ofprecipitates as well as in the resistance t_ deform_ttion by the aus-tenite (ref. 3.13).

3.51 Gamma Prime I_(') Phase. The importance of the 7' phase is uniquebecause it is only a titanium transition phase, based on ordered fcc[Nis(Ti, A1)];the equilibrium phase is _ (Ni3Ti). The 7t is the majorhardening phase in A-286, and is the most important intermetalliccompound because of its natural morphology with small interparticledistance, preference for general precipitatzon and large volume per-

cent. Other favorable factors include the high ductility of the phasecompared with minor precipitates and the coherency with the austen-itlc matrix because of close lattice matching. It forms as sphericalprecipitates (see figure 3.51) that have a low surface energy (refs.3.8, 3.13, 3.ZO, 3.21).

3.52 Eta (_I Phase. In the approach to equilibrium, the y' transitionphase is replaced by _ phase, hexagonal Ni s Ti (see figure 3.5Z).As a cellular precipitate, forming in the range of 750°--1800°F(399°--982°C), it is nucleated at grain boundaries and can be detri-mental to notched stress-rupture strength. Precipitation may alsooccur as Windmanstatten intergranular 1] which reduces hardness,strength, and physical properties, but not ductility. The presenceof boron and aluminum retards both modes of formation (refs. 3.8,3.13, 3.18, 3.21).

3.53 Beta (B1 Phase. For best mechanical properties, B phase [Ni(AI,Ti)] should be avoided. It precipitates in a few hours at 1100 °-1500°F (593°--816°C), but rapid17 overages to massive plates (seefigure 3.53) with large spacing values because of lattice disregistry.

!_ 3.54 Laves Phase. Austenitic steels are embrittled by the Laves phase_ at room temperature, but there is little effect at elevated temper-

atures; for example, Laves phase was found in the grain boundariesof A-286 with no influence on properties at ll00°F (593°C). The

_ phase is precipitated from IZ000-_000OF (649°--10950C} in a morph-ology that varies from general intergranular precipitation to grainboundary forms. It has been shown that nlckel-containing plmses

II

XXXXX-O 19

(V', 17,G) in A-286 can deplete the matrix composition in nickel andpave the way for Laves phase precipitation(ref. B.I3).

3.55 _) Phase. The Y phase appears in the temperature region of_il i750_ (6490 _ 954OC) with aging times longer than I0 hours;the unit cell structure is (Fe_TNieCr13)(Mos._Ti4._). The massive,blocky morphology of the X phase at grain boundaries is not expectedto contribute to hardening (refs. 3.13, 3.23).

I

3.56 Sigma (a) Phase. The _ phase is a most well-known phase in iron-based austenites. Pormation of a, after prolonged times at 9000 --1700°F (482° --9g6°C), is minimized by nickel, promoted by chro-mium, and stabilizedby silicon.The a phase can cause embrittlementat room or elevated temperatures to an extent influenced by theamount and distributionof the phase. A continuous grain boundary acan be detrimental, but blocky morphology in fine-grained austenitecan increase creep ductility(ref, 3.13).

3.57 G Phase. A common elemental composition for the G-phase, basedon work with A-286, involves nickel, titanium, and silicon. G phasemay be found after solutiontreatment; ifnot, aging more than I00hours at 1200o --1550°F (649° --843°C) is required for formation.The morphology is generally globular at grain boundaries (see figure3.57). This phase has littleeffecton room-temperature impactw 0energy or short-time tensileproperties at 1200 F (649 C); however,microcracking has been found in A-286 at the G phase--grain boundaryinterfaces in stress-rupture at 1200°F (refs. 3.8_ 3.13).

3.6 Metallo_raphic Procedures

3.61 General. The techniques for preparing A-286 specimens for cxam-ination of structura by optical microscopy are essentially those usedfor other austenitic stainless steels. For example, specimens may

_- be polished mechanically by grinding to an 80- or 120-grlt finish onf

a grinding belt or wheel _nd then polishing with succe••ively finer

_: en_iery papers (ref. 3.24). Alternatively, specimens may be electro-polished, which elim;nates difficulties of distortion and the collection

_ of chips or particles o_ the metal surface that might arise from mech-anical polishing, but m&y lead to unsatisfactory relief effect• whenlarge particles are preseut (ref. 3.25). Etching of specimens may

_. also be performed as for stainless steels, by framer•ion or by elec-_ trolytic techniques. Detail• of etchant solutions are provided in ref-

_ erence 3 26 and the Marshall Space Flight Center "Materials DataHandbook: Stainles• Steel Type 301." The techniques and agentsde-scribed in the following subsections are those that have been usedfor recent, specific examination• of A-286.

3.6Z O tical Micro•co . In a study of cyclic-strain-induced oxldation of- an • ar alloys, s macroetch of concentrated aqua regia

was used first to reveal grain boundaries. For subsequent micro-

_. scopic _n_flon to reveal localized oxidation, a mlcroetchant w_sused that corisisted of I0 l_rts nitric acid, 10 parts acetic acid, and

5 parts hydrochloric acid (ref, 3.27).

XXXXX-020

3.63 Electron Microscopy. Intergranular precipitation of intermetalliccompounds was studied by electron microscopy and x-ray diffrac=tion (ref. 3.23). Specimens for electron microscopy were mech-anically polished and then etched in a freshly=mixed solution of92 percent hydrochloric acid, 5 percent sulfuric acid, and 3 per=cent nU.ric acid. Parlodion replicas were chromium-shadowed inhigh vacuum at a glancing angle of 20 degrees.

For a study of the interaction betweew dislocations and intermetallicprecipitates, tensile strip specimens were electropolished and thenetched electrolytically in a 10 percent oxalic acid solution to revealthe structure of the steel (ref. 3.21). (The procedure for electro=1ytic etching with oxalic acid is given in reference 3.24. ) A two=stage replication procedure was used for electron microscopicexamination of slip markings at different stages during deform=ation, the procedure involved a formvar replica of the specimenshadovCed by a gold-palladium alloy and _-ubsequent preparation ofa carbon replica _ronn the shaOowed formvar replica. For trans-mission e!cctron microscopy, specimen strips were chemicallythinned to about 0. 005 inch (0. 127 ram) thickness and then electro-polished with a standard acetic acid--perchloric acid solution.

Tensile strip specimens and aged sheet were examined in a studyof the strengthening mechanisms in y'=precipitating alloys (ref. 3.4).The tensile specimens were chemically thinned to 0.5=mm slices.Foils were prepared by dishing in 20 percent sulfuric acid at 50Vand finally polishing in 10 percent perchloric acid in methanol at12V.

z

XXXXX-021

TABLE 3.1 3. --Variation in AMS Specifications for Composition L_.mits

Source Ref. 3.1

_lov A-2865525C 5731C, 5734D ]

Spec. No.(a) 5736F 57_SG. 5737E ] 5804B . ..5805BElement (b) rain max rain max rain" max rain max

Carbon - 0.08 - 0.08 - 0.08 - 0.08Manganese - Z.O0 - X.O0 - Z.00 - Z.00Silicon - I.00 - i.00 - I.00 - I.00Phosphorus* - 0.0Z5 - 0.0Z5 - 0.0Z0 - 0.010Sulfur* - 0.025 - 0.025 - 0.015 - 0.010Chromium 13.50 Z7.00 13.50 16.00 13.50 16.00 13.50 16.00Nickel 24.00 27.00 Z4.00 Z7.00 24.00 27.00 24.00 27.00

Molybdenum I.00 I.50 I.00 I.50 I.00 1.50 I.00 I.50Titanium* I.90 Z.30 I.90 Z.35 Z.00 2.45 Z.00 Z.45Boron 0.0030 0.010 0.0030 0.010 0.0030 0.010 0.0030 0.010Vanadium 0.10 0.50 0.10 0.50 0. I0 0.50 0.I0 0.50Aluminum - 0.35 - 0.35 - 0.35 - 0.35

Oxygen* ....... 0.005Hydrogen* ....... 0.0005

* Indicates element variations

(a)See table Z. I for description of specifications.

(b) Specifications that apply to chemical analysis are:

AMS 2248, Chemic-../ Check Analysis Limits, Wrought Heatand Corrosion R sistant Steels and Alloys.

ASTM E353, Chemical Analysis of Stainless, Heac Resisting,/v[araging, and Other S_mi/ar Chromium Nickel-Iron Alloys.

14

XXXXX-022

IS

XXXXX-023

A

,,,....

,.-, <30 i i

< o o

16?

XXXXX-024

17

XXXXX-025

-250 -200 -150 -I00 -50 0 °C

zoo- _'_ ! - 15o

O Aged 1350°F(732°C). - 5016 hrs. AC

• Annealed : !0 z

200 i ....... L I .., ....

, ,__8">. 100- -----_

0" "" - 50

0 i I '"13 , , * ,,,i ,, , , ,2.0

T_.o L

o ,_ Kt= 10

1.o.

1

80 ,_,k . i ._.! _ ; "

"_ wL -':':_ ; '" "_N

• . _ , _ _ . ._.

0 , i i '. i , ,' ,, ,I ,i,.I t , , ,-400 -300 -200 -100 0 I00 OF

Test Temperature

FIGURE 3. Z44. -- Effect of age-hardenin_ on properties of A-286_, sheet at cryogenic temperatures" 0. 095-inch (2.41-ram) thick.

_ii (Ref. 7.12)

(_ is

XXXXX-026

160Typ _ ----'_- 100

/

, 120 "" _-__-i "_ _-286 - 75

.-_ 8o ...../ _- - 50 "_

/ o/

... >, 40 254_

/ 0 0./

0 ZO 40 60Amount of Cold Work, percent

/

" _ FIGURE 3. Z5. --Effect of cold-working on room/" temperature tensile strength of A-286 com-

pared with stainless steel Type 302.(Ref. 3.19)

0 200 400 600 800 °C500 " ' I' _ ' ' 't

/-\450 Amount of _ ,,_

® Cold Work _ /

S, .,S •

_ 350

o o 50% _.I-_ _:_0 ..,_ _'_

, "_ _ \

, _o 250 .... / _

_/150 ------------

0 400 800 1200 1600 °F

Aging Temperature (16 hrs at temperature)

FIGURE 3. 251. -- Effect of cold reduction and agingtemperature on hardness of A-Z86.

(Ref. 3.19;

19

d

XXXXX-027

XXXXX-028

Chapter 3 - References

3.1 Aerospace Material Specifications, Society Automotive Engineers,Inc., ;qew York; latest Index, May 1971.

3.Z ASTMSTP-187, page 80.

3.3 ASTMSTP-160, August 1954, p. 70.

3.4 D. Raynor and J.M, Silcock, "Strengthening Mechanisms in y'-PrecipitatingAlloys," Metal Scl. J., 4, 121 (1970).

3.5 Allegheny Ludlum Steel Corp., "A-286," Product Literature.

3.6 Universal-Cyclops Specialty Steel Division, "Unitemp-A-286,"HT3020, 1971.

3.7 1971 SAE Handbook, Society Automotive Engineers, Inc., New York.

3. Q C.P. Sullivanand M.J. Donachie, Jr., "Microstructures and Mech-anical Properties of Iron- Base (-Containing} Superalloys," MetalsEn_. Qtr., 1._11(4}, 1 (1971}.

3.9 American Iron and Steel Institute, "High Temperature High StrengthAlloys," February 1963.

3.10 R.H. Raring, et a!., "Progress Report of NASA Special Committeei on Material Research for Supersonic Transports," NASA TN D-1798,

May 1963.

3.11 D.R. Muzyka, "Controlling Microstructures and Properties ofSuperallvys via Use of Precipitated Phases," Metals Eng. Qtr.,11 (4), 12 {1971}.

', 3.12 G.P. Sabol and R. Stickler, "Microstructure of Nickel-Ba_ed Super-

alloys," phys. star. solid., 35, 11 {1969).

3.13 R.F. Decker and S. Floreen, "Precipitation from SubstitutionalIron-Base Austenitic and Martensitic Solid Solutions," in Precipit-

_ * ation from Iron-Base Alloys, Metallurg. Soc. Conf., Cleveland,• 1963, Gordon & B1-each, N'ew York, 1965

3.14 Carpenter Technology Corp., "Carpenter A-286," Technical Data,June 1970.

3.15 Superior Tube, "Super Alloy Tubing," Bulletin 71, June 1968.

3.16 J.H.G. Monypenny, Stainless Iron and Steel, Vol. 2, "Microstructures,"Chapman & Hall, Ltd.",London, 1954.

21

XXXXX-029

3.17 C.J. Slunder, A.F. Hoenie, and A.M. Hall, "Thermal and MechanicalTreatment for Precipitation-Hardening Stainless Steels," NASA SP-5O89, 1968.

3.18 C.P. Sullivan and M.J. Donachie, Jr., "Some Effects of Microstruc-ture on the Mechanical Properties of Nickel-Base Superalloys," Metal

En_. Qtr., 7 (I), 36 (1967).

3.19 Metals Handbook, 8th Ed., Vol. 2, "Heat Treating, Cleaning, and

Finishing," American Society for Metals, Metals Park, Ohio, 1964.

3.20 K.J. Irvine, D.T. Llewellyn, and F.B. Pickering, "High-strength

austenitic stainless steels," J.I.S.I., 199, 153 (1961).

3.21. F.G. Wil._on and F.B. Picketing, "Some Aspects of the Deformationof an Age-Hardened Austenitic Stee. ," J.I.S.I., 207, 490 (1969).

3.22 Marshall Space Flight Center, "Effects of Low Temperatures onStructural Metals," NASA SP-501Z, December 1964.

3._3 H.J. Beattie, Jr., and W.C. Hagel, "Intergranular Precipitation of

Intermetallic Compounds in Complex Austenitic Alloys," Trans.

Metall. Soc. AIME, ZZ..__I,28 (1961).

3.Z4 ASTM Standards, AZ62-64T, Part 3, American Society for Testingand Ma6"erials, 1968.

3.Z5 J.M. Camp and C.B. Francis, "The Making, Shaping, and Treatingof Steel," 6th Edition, United States Steel Co., 1951.

3. Z6 J.P. Vidosic, "Study of Phase Identifications in Steel and Aluminum

Alloys," Georgia Institute of Technology, Final Project Report A641

for NASA., September 1963.

3.Z7 L.F. Coffin, Jr., Trans. ASM, 56, 339 (1963).

ZZ

XXXXX-030

Chapter 4

PRODUCTION PRACTICES

4.1 General. The production of superalloy steels such as A-286 involvesa two-stage refining process. The steel is first melted and refinedin an electric arc furnace to produce an ingot for remelting. Thisingot is made the consumable electrode in a remelt process conductsin vacuum to ensure a high-purity alloy that will have the uesii'ed._u-_ltles of high strength, resistance to temperature, and resistanceto corrosion (ref. 4.1).

Production of mill products is similar to practices for other stain-less steels.

4.2 Manufacture of Wrought Products

4.21 Air Melting. Alloy A-Z86 is first produced by the double-slag pro-cess (as for other stainless steels) that ensures a fully deoxidizedor "killed" ingot for additional processing. Production of this airmelt must be carefully controlled to ensure the highest possiblequality in the final vacuum-melted product (refs. 4.1, 4.2).

4. ZZ Remeltin_. The demands of advancing aerospace technology for supestrong and super-re_istant materials have been highly instrumentalin encouraging the development of remelting processes that at leastmini_nize the concentration of elements in alloy compositions thathave deleterious effects on physical and mechanical properties (refs.4._, 4.3). For example, purity of the steel is one of many factorswhich determines the notch strength of a steel in a given alloy systenAlso, the tolerance for embrittling factors is affected by changes inthe alloying content, l_Iore specifically, it has been shown that thegas content of the consumable-electrode vacuum melt is far less tha:that of the air melt, for example, Z9 percent less hydrogen, 6Z per-cent less oxygen, and 93 percent less nitrogen. Additionally, impro,

" ment in workability has resulted from improved microstructure andminimization of segregation (ref. 4.4).

It. the remclt process, the ingot from the air melt is placed as the, electrode in a vacuum-melting furnace. After the furnace is sealed

I off, it is evacuated and then current is al:plied to the electrode. Asthe electrode melts, oxygen, nitrogen, and hydrogen are removed

. from the melt because of the high vacuum (ref. 4. I). By 1956, con-sumable electrode - vacuum melted ingots were produced up to Z6-

r inch (66-cm) diameter (ref. 4.4), and by 1969, up to 45-inch (144-cm) diameter (ref. 4.3).

A comparison of the transverse ductility of A-_86 from an air-melteand a vacuum-melted heat is given in figure 4. _-21. A comparison ofthe fatigue strength of air-melted vs consumable electrode-vacuumrr,elted A-286 is given in figure 4. _.

23

XXXXX-031

4.23 Rolled Products (ref.4.5). Except for coils of thin strips or rods forsubsequent wire fabrication, rolled preducts are usually produced instraightor flatsections. After solidification,cast ingots weighingur to I0,000 pounds (4,350 kg) are removed from the mold and heatedin a furnace in a sulfur-free atmosphere. {Even small amounts ofsulfur wi]l cause the material to be hot short and, possibly, to crackduring rollingat elevated temperatures. ) Ingots may be forged be-fore rolling, or may go directly to the blooming mill for rollingintcrectangular slabs; the hot-working range is n_rrow, which necessi-tates frequent reheating during the operations of ingot breakdown.If the finalproduct is to be bar stock, ingots are forged to squares.(Round shapes may also be forged in diameters of 3-I/Z inches to 6inches (8.9 to 15.Z cm). After rollingor forging in the blooming mill,billetsare surface-conditioned and the hot top end is removed. Usually,ultrasonic inspection is made at this time, particularly since it isdifficultto heal defects in stainless steels during hot rolling.

The billetsare hot rolled on 3-high mills down to 3/8 inch {9.5 rnm)plate. Billetsmay be cross rolled to minimize directionalvariatimas.Frequent heating may be required as well as surface conditioning.At this time, the alloy is pickled and ma 7 be shot-blasted before fur-ther rolling. Rolling is generally performed on a Z-high mill forthicknesses of 0. 045 to 3/8 inch (1.14 to 9.5 mm). The sheet may befinished hot or cold. Rolling to thinner sheet is usually done cold ona cluster mill. Typical fabrication schedules for bar involve hot roll-ing of the forged bars down to 2-1/4 inches (63.5 ram)on a _4-inch(61-cm) mill, followed by surface conditioning and reheating for roll-ing on a 10-in:h (Z5.4-crn) mill down to 5/16 inch (0.79 cm) diameterrod. For wire production, rod is coiled at this stage by cold drawinginto wire as small as 0. 001 inch (C. 0Z5 ram) in diameter.

Hot rolled sheet and plate are generally annealed after rolling, anddescaled by acid pickling or vapor blasting. Then, the alloy may berolled, leveled, and sheared to length; sheet products rnay be stretchstraightened and cut to size. Cold rolled products may be given atemper treatment for deliver 7 in the cold-reduced and tempered con-dition (CRT). Mechanical properties depend on the amount of coldreduction and the tempering temperature. Bar products over Z-l/4inches (63.5 ram) diameter generally are straightened, annealedor tempered, and ground to finished size. Bars of smaller diameter

i are straightened, ground, heat treated, descaled, and pickled prior •to cooling. Most rolled products are shipped from the mill in thesolution treated (annealed) condition.

4.24 Extrusions (refs. 4.9, 4.6). Tubing and structural shapes have beenp'roduced by the hot extrusion process. Extruded shapes such as teesand angles can be cold drawn to improve tolerances and achievethinner gages. For example, tee sections with 0.06Z-inch (1.57 ram)webs have been extruded from A-286. Techniques for extrusion aresimilar to practices for stainless steel. By use of the Ugine-Sejournetglass-lubrication process, extrusions have been made at rat_.4 up

24

Y

×××××-032

97:1 for A-286. in this process, billets are transferred from theheating farnace to the charging table of the extrusion press. Asa billet rolls _nto position before the container, it passes overa sheet of glass fiber or a layer of glass powder that fuses to thesurface of the bille_. Also, a glass-fiber pad is placed in front ofthe die face during extrusion. Billets are heated in either gas- oroil-fired furnaces by induction or by salt-bath heatirg; long inductiontimes are required. Successful extruding of A-286 requires accurateteml_erature control, working within a narrow temperature range,minimized transfer time from furnace to extrusion press, and con-trolled speed of extrusion so that overheating does not result fromthe heat of deformation.

Products, where possible, are quenched after extrusion to removeany adhering glass. In some instances, air cooling is required ifthe extrusion cross-sectional area is large or if the alloy is sens-itive to quench cracking. Detwisting on hydraulic torsional stretchersor straightening on roll straighteners is usually required for ex-trusion products.

4.3 Forging (refs. 4.5, 4.6)

4.31 Billets, ingots, and bars for forging generally are produced by prac-tices used for conventional stainless steels. Requirements for forg-ing billets are relatively small; thus, suppliers stock a few standardsizes and either cog or roll them to the sizes specified by the cus-tomer. Forging billets are usually supplied in the overaged condition,

0 Odeveloped by holding solution-treated material at 1150 F (621 C) forseveral hours. Overaged material must be solu_.ion-treated prior toprecipitation hardening. If billets are supplied in the solution-treatedcondition, they may be precipitation hardened directly after forging.

4.32 Wire, Rod, and Tube. Alloy A-286 is readily drawn into tube, rod,and wire. The tubing is used extensively for both hydraulic and deicingsystems in aircraft. Rod and wire are us,ed for f_.steners and springswhere resistance to corrosion is ._mportant.

_ 4.4 Castings (ref. 4.8)

4.41 Alloy A-286 is cast in investment molds. For consistent properties_ • at a higher level, particularly ductility, it muBt be cast under vacuum_ from certified vacuum-melted master heats. Alumina, magnesia, or

zirconia crucibles are satisfactory after they have been cured by

i several wash heats. Alumina or zirconia facing material is prefer-able to a silica facing in investment molds, poured at a preheat of

o 0up to 1900 F (1038 C), because silica may react to form surfacedefects in the casting. The production cycle for casting a I P-pound(5.2-kg) charge is 6 minutes.

25

XXXXX-033

Alloy A-Z86 castings are solution annealed at 2000°F (1094°C) for1-1/Z hours per inch {per 7-5.4 ram} of section thickness, followedby rapid cooling in air to room temperature.

XXXXX-034

4O

VacuumMelted

o•" 30 -U

_ Vacuum'rj

Melted

= 20 ......

Melted

_< Air /

_ Melted _/iI

"'_ 10o

Plt

0 ,,Elongation Reduction

in Area

FIGURE 7.4221. --Transverse ductilityof air-meltedvs. consumable-electrode vacuum melted A-28_.

(Re r 4.4)

_5

60 I_ _-- Vacuum Melted

•

_ 40Air Melted

i - 25

_ 30• ___ l I I

. 1 10 100 ,' Cycle,_ to Faiiure x l0 s

i: FIGURE 7.4222. --Fatigue strength at 1200OF (649°C)of air-meltedand consumable-electrdoe vacuum-melted A-286.

(Ref. 4.4)

27

XXXXX-035

Chapter 4 - References

4.1 Republic Steel Corp./Special Metals Div., "Now and Tomorrow withHigh Performance Alloys," ,Tune 1969.

4.Z S.J. Matas, "Influence of Impurities and Related Effects on Strengthand Toughness cf High Strel.gth Steels," paper presented at AmericanSociety for Metals, Golden Gate Metals Conference, February 13,1964, San Francisco, California.

4.3 R. Schlatter, "Vacuum Melting of Specialty Steels," J. Metals, 2.Z_(4),33 (1970).

4.4 R.K. Pitier, E.E.B.eynolds, and W.W. Dyrkacz, "ConsumableElectrode Vacuum Remelting of High-Temperature Alloys," Conf.of Metall. Soc. of AIME on High Temperature Materials, Cleveland,Ohio, April 16-17, 1957, Ch. 25.

4.5 D.E. Strohecker, A.F. Gerds, and F.W. Boulger, "DeformationProcessing of Precipitation-Hardening Stainless Steels," NASA SP-5088, 1968.

4.6 L.M. Christensen, "Development of Improved Methods, Processes,and Techniques for Producing Steel Extrusions," ML-TDR 64-231, JJuly 1964.

4.7 A.M. Sabrof', et al., "A Manual on the Fundamentals of Forging _Practice, AFML TDR 64-95 Suppl., December 1964.

4.8 J.G. Kura, V.D. Barth, and H.D. McIntire, "Shaping of Precip-itation-Hardening Stainless Steels by Casting and Powder Metallurgy,"NASA SP-5086, 1968.

I

i •!:, Z8

&

XXXXX-036

Chapter 5

MANUFACTURING PRACTICES

5. i General. Techniques for fabricating precipitation-hardenable (PH)sta._,-2ess steels are not very much different _.... those1_or,, used for

other stainless steels. Alloy A-Z86 is slightly more resistant todeformation than the austenitic stainless steels during hot working.It is t,.. most forgeable of heat-resisting alloys In the solution-treated condition, it is somewhat stiffer than stainless steels suchas Types 316 ahd 310; however, it can be sat_.sfactorily cold drawnand formed. Machining can be performed with the same techniquesand equipment as used for the 300 series of stainless steels, but atslower rates (refs. 5.1 through 5.5).

5.11 Blanks for secondary deformation processes may be produced bythe cutting, preforming, or welding of material in the annealed orsolution-treated condition to the desired shapes and sizes. Shearingis the most economical and most widely used method. Blanking,normally performed on a punch press to produce the desired shapein one operation, may be used for materials of less than 0.1ZS-inch(3. 175-ram) thickness; dies should be rigid and guide pins must beused. Low- or high-speed bands may be used for sawing. Slitting,hand-shearing, routing, and nibbling are also used. Thermal cuttingis often more efficient for PH steel material thicker than 1/4 inch(6.35 mm). PH steel blanks must be deburred to minimize damageto forming tools and assure safety in handling. Deburring may beaccomplished by draw filing or grinding on materials of less than0. 040 inch (1. 016 mm) thick; for greater thicknesses, grinding wheelsor machining operations (milling) are suggested {ref. 5.6). Surfacesshould be free of imperfections, soluble substances (oil, grease), andcontaminants, such as iron, thatwill reduce resistance to corrosion.

5.2 Formin_

.: 5.21 Alloy A-286 is normally cold worked in the annealed (solution-treated)condition. As annealed, Rockwell B hardness is 75--85 and formabilityis good. It is one of the most po'_ular high-temperature alloys forcold heading applications. For this purpose, dead softannealed wireis sometimes used, but more often the wire is given a slight colddraw to provide better shearability and resistance to flattening (ref.5.1). Forming processes include:

Brake bending Tube formingDeep drawing Roli formingSpinning Roll bendingShear forming DimplingDrop hammer forming JogglingTrapped-rubber forming SizingStretch forming Explosive forming.

29

XXXXX-037

5.22 in brake forming, A-Z86 is more easily bent at room temperaturethan other IDI-Isteels such as 17-7 PH, IDH 15-7 Mo, AM 350, and

AM 355 (ref. 5.7); lowest springback among the aged alloys is shown

by A-Z86 (ref. 5.8). in deep-drawing processes, A-286 can probablybe formed at a higher speed than most PH steels (ref. 5.6), that is,greater than I0--20 feet per minute (3--6 m/min). Shear forming,

generally used to reduce machining time on parts with shapes that

cannot be made by conventional forming methods, has been used

successfully for A-Z86 jet-engine shafts (ref. 5.9). The derivationof limits for drop-hammer-forming of A-Z86 are discussed in ref-

erence 5.7. From the standpoint of buckling in compression-flange

forn-ing (by trapped-rl,bber forn_ing), A-286 has the best formabilityco_ipared with other PH steels (ref. 5.10). Alloy A-286 can be

stretched (stretch forming) more without splitting than other PH

steels !ref. 5.7), but can withstand less stretching strain in tubeforming (ref. 5. II). It is more easily formed by linear roll binding

and joggling than other PH steels (ref. 5.1Z).

5.3 Forging

5.31 The narrow range of temperature permissible for forgin_ A-286 is

generally limited on the low side by a drop in forgeability due tocarbide precipitation. For most PH alloys, this reaction starts at

about 1750°F (954°C) (ref. 5.6). Alloy A-Z86 forged at a temper-

ature of ZI50°F (i177°C) displays low decarburization, low scale,

fair grain size control, fair forgeability, and no thermal cracking

(ref. 5.13). Temperatures recommended for A-Z86 forgings re-ceiving given nominal amounts of reduction are as follows:

Maximun% forging temperature 2150 °F (I177 ° C)

Light reduction, up to 15 percent 1800 °F (98Z°C)

Moderate reduction, 15--50 percent ZI00°F (I149°C)

Severe reduction, >50 percent ZI50°F (I177°C)Variable reduction Z100 °F (I177 °C).

Heating in a reduced atmosphere should be avoided t,,prevent pick

, up of nitrogen or carbon; neutral or slightly oxidizing atmospheresare recommended for forging A-Z86 (refs. 5. I, 5.6). Subsequent

scale can be removed by pickling in HF--HNOs mixture or by grit

blasting (see Chapter II). Lubrication practices are the same as for

austenitic steels. Specific cooling procedures are rarely needed

after forging for heat-resisting alloys; ifforging temperatures are

correctly maintained, the forgings can be cooled in stillair andw_11 be in suitable condition for heat treating (ref. 5.5).

5.4 Machinin_

5.41 Alloy A=286 is slower to n.achine than the 300 series of stainless/ steels, and exhibits the s_xne gumminess and work-hardening char-_ acteristics so that rigid :nachlne setups and sharp tools are required.

i_ To overcome the gumming condition, the alloy is often partially aged

(_ hour at 13Z5°F, 718°C) or fully aged (16 hours at 13ZSUF), oroveraged (several hours at 15000 F, 816°C)prior to machining. After

×××××-038

overaging and machining, re-solution treating and aging are requiredto develop optimum propertles (ref. 5.1).

Other suggestions for successful machining include the use ofrelatively low cutting speeds with recommended cutting fluids toreduce buildup, friction, and tool-chip temperatures. By usingsharp tools of recommended geometries, work hardening is min-imized. Also, tools should cut, not push, metal and they shouldnever rub or dwell in the cut (ref. 5.14).

Machine tools for cutting A-286 need the following characteristicsinsure rigid, vibration-free operation (ref. 5.14): (a) Dynamic

ba;.a,_ce of rotating elements; (b) True runi.ing spindle; (c) Snugbearings; (d) Rigid frames; (e) Wide speed/feed ranges; (f) Amplepower to n_aintain speed; (g) Easy accessibility for maintenance.Milling machines and lathes also shou!d have backlash eliminationdevices as well as snug, clean, correctly-lubricated gibs and slides.Typical parameters for machining A-286 are given in table 5.41.Extensive detail on machining practice is given in reference 5.14.

5.5 Electrochemical Machining

5.51 Most of the r pecific data and information on electrolyte compositionand operating conditions for electrochemical machining (ECM) ofA-286 are proprietary {ref. 5.14). However, some available data onrepresentative operating conditions are summarized in table 5.51.As indicate3 in the table, good surface smoothne _ was obtained forcavity-sinking with a sodium nitrate _lectrolyte (ref. 5.16), andgood cutting results with a sodium chloride--boric acid electrolyte(ref. 5.17). When the electrolytes for cutting contained either sul-furic or tartaric acid, or hydrochloric acid and tartaric acid, poorercutting performance {maximum feed rate of 0.27 in/rain (6.86 ram)was observed.

Data published on the effects of ECM on the properties c ¢ A-Z86 in-

dicate thatno intergranular corrrosion occurs, and fatiguestrengthis essentiallyidenticalto that of the parent metal (ref. 5.18). In astudy of the susceptibilityof various steels to hydrogen embrittle-ment as a result of ECM, an aqueous etchant was used that included

_: IS volume-percent HCf, 17 volume-percent HNO s and 31 volume-/_ percent H s PO 4 . No evidence of hydrogen embrittlement was observed, in subsequent constant-strain-rate bend tests (ref. 5.ZO}.

31

! I I

XXXXX-039

TABLE 5.41. --Typical Machining Parameters

Source Refs. 5.14, 5.15i|

Alloy A-286

Cond. Tool (b) Depth of Speed,Operation (a) Grade Fluid Cut, in (c) fpm (c) Feed

Turning ST C-Z none 0. 025 150 0. 008 iprT-5 none 0. Z5 40 0. 010

STA C-Z none 0. 187 80 0.01 3

T-_5 non e 0. _5 45 0.01Face ST C-2 i 0.25 120 0. 004 iptmilling T-15 I 0.25 55 0. 003

STA C-Z I 0. Z5 IZ0 0. 004

T-_5 I 0, Z5 55 0. 003

End ST C-2 I 0. 050 I00 0. 0035 iptmilling T-15 I 0. 050 40 !0.0035

STA C-Z I 0. Z5 150 0. 005

T-15 I 0. Z5 40 0.00Z5Slab ST C-Z il 0. Z5 140 i0.006 ipt

milling T-5 il 0. Z5 50 0. 005STA C-Z II 0.Z5 II0 0.006

T-15 n 0._ 50 0.005Drilling ST T-15 - - 10-Z0 0. 0005 ipr, I/8-in drill

0. 007 ipr, l-in drill

STA - - - 10-Z0 0.001 ipr, I/8-in drill;

0. 010 iprf 1-in drill ._Tapping S TA M- 10 - ] - 3 0 -

Broaching ST, T-15 - [ - 9 chip load, 0. 002 iptSTA [ :_

Burface ST downfeed, rough, 0. 001 ipp; table speed, Z0 fpm; 5:grinding wheel speed, 6000 fpm

downfeed, finish, 0. 0005 ipp; table speed, Z0 fpm;wheel speed, 3000 fpm ..

(a) ST, 180-220 Bhn hardness; STA, 280-320 Bhn hardness. .:

(b) C-2, carbide tool; M- and T-, high speed steel; see reference 5.14for tool geometries and alternatives

(c) I inch = Z5.4 ram; I ft = 30.5 cm.

I, sullurized oil _

=,_ If, chlorinated oil

, 3Z

4

XXXXX-040

TABLE 5.51.--Representative Chemical Machin.in_ Conditions

Source Refs. 5.14, 5.16, 5.17, 5.19

Alloy A- 286

Parameter OperationCavity Sinking Cutting Gr inding

Electrolyte NaNOa, 5.0 lb/gal NaC1, 200-227 g/1 "Anocut #90"(600 g/l) H3BO3, 25 g/1 (a)

Temperature 100°F (38°C) 70°F (Zl°C) .

Inlet pressure range 240/240 psi(0.17/0.17 kg/mm _)

Flow rate 3.9 gal/min - _(14.8 I/rain)

Current 741 A - 80-130 A

Applied voltage 1Z. 0 10- lZ 5

Feed rate 0. 040 in/min 0. 071 in/min 3.7 in/min(i. 0Z mm/min) {I.80 mm/min) (94 mm/min)

Depth (or length 0. 510 inch 0.0 to 1. Z in 0. 005 inch

of cut) (13.0 ram) O. 0 to 30.5 mm) (0. lZ7 mm)

Cathode wheel speed - 7200 surf ft/min -(Z196 surf rn/n_in)

Surface roughness lZ- 20 _in (av) - Satisfactory(0.3--0.5 _m)

(a) Anocut Engineering Company, Chicago, Illinois

?

33

XXXXX-04 i

Chapter 5 - References

5.1 Carpenter Technology Corporation, "Carpenter A-286," TechnicalData, June 1970.

5.2 Univeral-Cyclops/Specialt7 Steel Div., "Unitemp A-286," HT3020, 1971.

5.3 Metals Handbook, Vc1.3, "Machining," American Society for Metals,Metals Park, Ohio, 8th Edition, 1967.

5.4 Metals Handbook, Vol.4, "Forming," American Society for Metals,Metals Park, Ohio, 8th Edition, 1969.

5.5 Metals Handbook, Vol. 5, "Forging and Ca3ting," American Society forMetals, l_'etals Park, Ohio, 8th Edition, 1970.

5.6 D.E. Strohecker, A.F. Gerds, arid F.W. Boulger, "Deformation Pro-cessing of Precipitation-Hardening Stainless Steels, " NASA SP-5088,1968.

5.7 W.W. Wood, et al., "Final Re::. t on Sheet Forming Technology,"Vols. I and I.I, Report No. ASD DR. 6?-7-871, July 1963.

5.8 Allegheny Ludlum Steel Corp., "Tensile _ ;,_rties of AM-350 Cold-Drawn Wire," Tech. Data Sheet 126-71659-3_0.

5.9 F. Jacobs, "Effects of Shear Forming Upon the Properties of Materials,"Temco Aircraft Corp., ASD TR 62-380, August 1962.

5.10 J.M. Raymer et al., "Metastable Austenitic Forming of High StrengthPressure Vessels," AVCO Corp., ML TDR64-174, July 1964.

5.11 W.W. Wood, et al., "Final Report on Advanced Theoretical Manufac-turing Technology," Vols. I and I1, AFML TR 64-411, June 1965.

5.12 W.W. Wood, et al., "Theoretical Formability," Vol_,. I and II, ASDTR 61-191, August 1961.

5.13 A.M. Sabroff, et al., "A Manual of the Fundamentals of Forging Prac-tice," AFML TDR 64-95, Suppl., December 1964.

5.14 C.T. Olofson, J.A. Gurklis, and F.W. Boulger, "Machining and Grind-ing of Ultrahigh-Strength Steels and Stainless Steel All( lCs," NASA SP-5084, 1968.

5.15 Metal Progress Databook: 1968, pp. 111-113.

_ 5.16 J. Bayer, M.A. Cummings, and A.U. Jollis, "Final Report on Elec-trolytic Machining Development," AFML TDR 64-313, September 1964.

5.17 3.E. C1ilford, D.E. Semons, and J. McCallum, "High-TemperatureA/toy Cutting Program," AMC TR 59-7-617, January 18, 1959.

5.18 R. 3. Favor and H.G. PoplJ, "Materials Property Data Compi/ation.Part I. Hastello7 X," 5th Qtr. Rept., Cont. AF 33(657)-8017, ,N_ay 1961.

5.19 H.W. Jacobus, 'Surface Effects of Electrolytic MAchining," Report No.AZ43, Cont. AF 33(657)-IIZ15, December II, 1963.

i 5. Z0 R.L. Jones, "Suscept_,dity of MAterials to Hydrogen Embrittlement

from Chemical Milling Operations," Cnovalr/General Dynamics, Re-

i port No. MRG-219, March 16, 1961.: 34

XXXXX-042

Chapter 6

SPACE ENVIRONMENT EFFECTS

6.1 General. Stainless steels are used successfully in both structural andnonstructural applications for aerospace vehicles. In general, thesealloys are relatively insensitive to degradation under typical spaceenvironment conditions.

6.7. The low pressure encountered in space is conducive to the loss of mat-erials of construction by sublimation (or evaporation) because moleculeswhich leave the surface of materials are not returned by collisions withambient gas molecules. Thus, above altitudes of about 160 kin, themean free path of a molecule at ambient temperatures is so long in com-parison with the size of the spacecraft that any molecule which leavesthe surface will not return. Loss of material by sublimation in thevacuum of space is intuitively obvious, but the effect of very highvacuum on the rupture ._nd fatigue properties of materials is unexpected;however, experiments have indicated that the density of the gas sur-rounding a material is an important parameter defining its bel _ .riotunder stress. Apparently, the character of the gas layer adsorbed onmaterials influences certain m_chanical properties. Thus, prolongedexposure of materials to a space environment will alter or removeadsorbed gas layers and some of the physical properties of the mat-erials in space will be different than on ear_n.

The removal of material from a spacecraft structure will obviously leadto an overall weakening of members. The weakening of a member canbe simply computed by knowledge of the mass-strength relationship.Where gross sublimation of a matelial is involved, tests made beforeand after exposure of specimens to a vacuum will furnish experimentalvalues. Ideally, the tests should be performed in an atmosphere closelyresembling the space environn_ent; however, for practical evaluationof the effects of sublimation, the most important condition to be met isthat a molecule leaving the surface of the test piece has a negligible

" _ chance of returning.

_ The rate of evaporation of an ideal, pure substance is given by Lang-muir ws equation:

E- P17.14

_ • where E is the rate in g-sec'l-cm =a of exposed surface, Ivl is the mol-i ecular weight of the material. P is the equilibrium vapor pressure in

tort, and T is the absolute temperature, WK.

Comparison of predictions from the above equation with experimentaldata indicate that the Langmuir equation is conservative; thus, theequation must be employed cautiously. Further, it is necessary torecognize that its use to predict vacuum volatility is limited by:

35

XXXXX-043

a. The vapor pressure, P, in the equation is the equilibrium pressure.h_ the space environment, molecules which leave the surface of theliquic! or solid phase do not return, and thus equilibrium is notestabl'_,hc d.

b. The molecular weight of the evaporating molecules must beknown; for most materials, this molecular weight is frequentlydifferent than assumed (association).

c. Oxide films or thin coatings may act as barriers to the escapeof molecules.

d. In practice, most materials are complex mixtures (alloys orpolymers) which defy simple treatment. The average assumedmolecular weight of a system can not be used in the equation.

e. The process of ev_-poration for systems of practical interest isvery different from the purely random process assigned to idealsystems. For example, evaporation from loc_.lized planes ofhigh surface energy is much greater than from planes of lowenergy; this leads to uneven evaporation, and etching of the sur-face becomes evident.

As is evident from the above discussion, the Langmuir equation is lim-ited to approximations of evaporation rates in a space environment; itis useful in that it assists in the selection of appropriate materials ofconstruction for spacecraft. For example, the equation indicates thatevery substance has a rate of evaporation in free space as long as theabsolute temperature is not zero. Thus, at a given temperature, say,ZS°C, one should select materials which exhibit very low vapor press-ures; obviously, the usual metals of construction (iron, copper, etc. )can qualify, but there is some question about the lighter metals suchas cadmium, magnesium, aluminum, etc. Table 6.1 illustrates theestimated sublimation losses suffered by metals in a space environ-ment over a moderate range of temperatures; it is anticipated that atlower temperatures, the rate of evaporation will be infinitesimal. Itis evident that zinc does not appear to be a uee£ul rre tal for the con-s_.ruction of spacecrafts or components which are exposed to the highvacuum of space. Pure magnesium metal barely qualHies for the con-struction of spacecrafts; however, the alloys of magnesium which arecurrently used show conslderably lower losses because the surfacepresented to the space environment acts as a barrier for sublimation

ix (oxide-chromate c_nversion coatings, etc.). Thin film0 of lead (asin soldered joints) may be weakened by prolonged exposure to thespace environment. On the other hand, a thin coating of pure tin willact as an efficient barrier for sublimation of other rnaterials. (l_ef. 6.5).

6.3 The effects of nuclear and indigenous space radiation on the rr.ech-anical properties of A-286 are not expected to be very elgnl/Icant. Theresults of some studies of irradiation of the alloy are dlsculeed inChapter 9.

36

XXXXX-044

Sputtering of the surface by atomic or molecular particles can de-teriorate surface finishes in a relatively short period. The sputteringprocess is associated with a minimum threshold energy value foratomic or molecular particles striking a material surface. Typicalvalues which have been obtained for this threshold energy are 6, 11,and 12 eV for O, N_, and Om particles, respectively, to remove oneor more atoms from the materials' surface upon which they impinge(re£. 6,1). Loss of metal by this mechanism can vary over a ,,viderange and the greatest loss may be expected during solar storms(rcf. 6.1). However, loss of metal by sputtering has litt_.e structuralsignificance, although it may seriously affect optical and emissiveproperties of the material surface.

The surface erosion of metals and alloys due to corpuscu_'a_ radiationis probably insignificant, amotmtir,g to something of the order o _.254nanometers per year. Indigenous space radiation, howew;r, ,.vA1 tendco accelerate the removal of surfa.=e films on A-286 which might resultin _he loss of lubricity and an incre,_sed prr, pensity to ",ohl weld. "The interaction of indigenous radiation with 0esorption gases naightcause some spurious, transient el3ctrical _u_ d_ions if the alloy isused for electrical applications.

6.4 Micrometeoroids can produce surface erosion sim{lar to sputteringbut on a more macroscopic scale, and may also produce punctures.They vary widely in mass, composition, velocity, and flux; gen-eralizations about rates of erosion and penetration, therefore, mustbe used with care. The predicted frequency of impact as a functionof meteoroid mass is given in figure 6.1. Calculat;ons of armorthickness required for meteoroid protection are given in reference6.11.

0

|

I

XXXXX-045

TABLE 6.1. --Evaporation Rates in Vacuum of Typical Elements

Used in Aerospace Alloys (a, b)J.

Source Ref. 6.14,. m .m •, |,

Evaporation Rate, g/crn _/secElement

--100 °C 0°C 100 °C 250 °C 500°C

Aluminum 1.2x10 "el 1.1 xl0 "4e 2.0x 10"as 1.7x10 "_1 6.5x10 "la

Titanium <10 "°g 2.5x lf} -s° 4.1 x 10 -4a 7.4x10 -_s 2.0x10 "le

Iron <10 .99 6.SxlG "_ ,4x10 -44 4.3xI0 -_g 9.1x10 "Iv

Nickel <I0 "9° 5.7 x I0-v° 1.3 x I0-4a 6.7x I0-as 1.7x I0-Is

Copper 1,2 x 10-94 1 -_x 10-66 6._ x I0-s9 4.0x I0=ss 4.7 x 10=14

Chromium 9,5 x I0"ga 1.0x 10=54 1.4x I0-3v 3.8x I0-a" Z.2x I0-Is

Vanadium <.I0 "99 l.gx10 -sv 2.1x10 "dl 5.0x10 -4z 1.2x10 "_4

Manganese 2._ x I0 "v_ 1.1 x I0 -e= 6.5 x I0 "as 3.8x I0 "Is 1.6 x I0 -g

Silicon ,:10 "s9 1.9xI0 "ea 3.6xI0 "4a 4.3xl0"ae 5.5xI0 -Is

Magnesilu_n 2.9 x 10 -as 5.3 x 10 -a° 1.8 x I0 -Is 1.3 x 10 -6 6.6 x I0 .8

Zinc 3.5 x I0"a° 5.I x I0"Is 1.8x I0"9 2.3x I0"" 2.80l

(a) The actual evapor&tion rate of each element in combination withothers wi!l be lower.

(b) The values may be in error by Jeveral orderB of rr_gnitude asthey have been extrapolated from btgh-ternperature datlt. The

•, rates at low tempeatures will be consider&bly less than thevalueb given in the table.

_ 38t

b

XXXXX-046

4

\

3 \ e._McCRACKEN , ALEXANDER, DUBIN 1961

2 \\

s \

o..---W HI PPLE 1963_-, EXPLORER-

-2 maz_ \

i "3 PEGASUS "_\_VAN DE HULST 1948---4 ELIrORO (RAOAR)---"/ _ ,--.t_AUMANN 1966

Z _ NTATIVE NASA

-6 \ \"7 WATSON 1941 _ _

\"8 %

"9

-IO 0 MAGNITUDE

-II

L i I I I I • I I, X I I _..

-II -:b -9 -O -7 -6 -S -4 -3 -2 -I 0 I °

LOBM (Ore)

i FIGURE 6.1. -- Various estirru_tes of meteoroid mass influx.

(Ref. 6.3) _

_ 39

l

XXXXX-047

i

i

Chapter 6 - References

6.1 C.G. Goetzel, J.B. R[ttenhousc and J.B. Singletary, Eds.,

Space Materials Handbook, Addison-Wesley Press, Palo Alto,California, 1965.

6.Z J.R. Redus, "Sputtering of a Vehicle Surface in a Space Environ-ment," NASA TN D-Ill3, June 1962.

6.3 SAMPE, The Effects of the Space Environment on Materials_,Western Periodicals Co., North Hollywood, California, 1967.

6.4 L.E. Kaechele and A.E. Olshaker, "Meteoroids - Implications

for the Design of Space Structures," Aerospace Engineering, I__9,May 1960.

6.5 R.F. Muraca, et al., "Design Data for Pressurized Gas Systems,"NASA Contract NAS7-105, November !963.

6.6 F.L. Whipple, "On Meteoroids and Penetration," I. Geophys.Res., 68, 49Z9 (1963).

6.7 H.C. van de Hulst, "Zodiacal Light in the Solar Corona," Astro-

phy__: J., 105, 471 (1947).

6.8 F.G. Watson, Between the Planets, The Blakiston Co., Philadelphia;

revised, Harvard University Press, Cambridge, Mass., 1956.

6.9 C.W. McCracken et al. "Direct Measurements of InterplanetaryDust Particles in the Vicinity of the Earth," Nature, 192, 441 (1961).

6. I0 R. J Naumann, "The Near-Earth Meteoroid Environment," NASA

TN D-3717, November 1966.

_. II C.D.._4iller, "Meteoroid Hazard Evaluation for Simple Struc.ureswith Various Orientationp," NASA TN D-6056, October 1970.

6. IZ K.S. Clifton and P.J. Natwnann, "Pegasus Satellite Measurementsof Meteoroid Penetration," NASA TM X-1316, 1966.

6.13 W.M. Alexander eta]., "Zodia_.al Dust: Measurement by Mariner

IV," Science, 106, 1240 (1965).

6.14 S. Dushma_,, Vacuum Techniques, John Wiley & So_ J, New York,1949.

6, 15 M. Kangil_skl, "Radiation Effects Design Handbook: Sec. 7, Struc-

tural Alloys," NASA C11-1873, October 1971.

4O

?

XXXXX-048

Chapter 7

STATIC MECHANICAL PROPERTIES

7.1 Specified Properties

7.11 NASA Specified Properties7.12 AM$ Specified Properties7.12! AMS specific_properties for various products, table 7. 121.7.13 Military Specified Properties7.14 Federal Specified Properties7.15 ASTM Specified Properties

7.2 Ela.stic Properties and Moduli

7.21 Poisson _s ratio at various temperatures, figure 7.21.7.22 Young's modulus of elasticity, E7.221 Design value of E, 29.1 xl0 a ksi (20.5x10 s kg/mm 2) (ref. 7.4).7.222 Values of E at room and elevated temperatures, see figure 7.21.7.23 Compression modulus, E c7.231 Design value of E c, 29.1 x 103ksi (20.5 x 103 kg/mm s) (ref. 7.4).7. Z4 Modulus of rigidity (shear modulus), G7.241 Design value of G, 10.4x10 a ksi(7.31 xl0 s kg/mm 2) (ref. 7.4).7.242 Values of G at room and elevated temFeratures, see figure 7.Zl.7.25 Tangent m.'.dulus --7.251 Tangent modulus in compression at various temperatures, figure 7.251.

7.3 Hardness (see also Chapter 3)

7.31 AMS specified hardness for various products, see table 7. 121.7.32 Typical hardness values (refs. 7.2, 7.5, 7.6):

ST 1800°F (982°C) + aging - Rc = 26--32 :_"ST 1800°F (982°C) + aging - Rb = 9Z--95ST 1650°F (899UC) + aging - Bhn = 302

7.4 Strength properties (see also Ghapters 3 and 12)

7.41 Tension7.411 Design mechanical properties for STA sheet, strip, plate, bars,

forgings, and mechanical tubing, table 7.4111.7.412 Typical tensile properties of various products7.4121 Tensile test data for vacuum-melt heats from two different parent

melt heats, table 7. 4121.7.4122 Typical tensile properties at room temperature of various mill

products, table 7.4122.! 7. 4123 Effect of cold reduction on tensile properties of aged bar and wi, e,,_ figure 7.4123.

7.413 Stress-strain diagrams7.4131 Stress-_train curves in tension for sheet at room and elevated

temperatures, figure 7.4131.7.4132 Stress-strain curves to failure for sheet at room and elevated

i temperatures, figure 7.4132.7.4133 Typical stress-strain curves for sheet at room and cryogenic

t temperatures, figure 7.4133.

41

XXXXX-049

7.414 Effect of temperature on tensile properties

7.4141 Effect of temperature on ultimate tensile strength, figure 7.4141.

7.4142 Effect of temperature on tensile yield strength, figure 7.4142.7.4143 Effect of elevated temperatures on tensile properties of bar stock,

figure 7.4143.

7.4144 Effect of elevated temperatures on tensile properties of STA tubing,figure 7.4144.

7. "145 Effect of elevated temperatures on tensil properties of 15-percent

cold drawn and aged wire, figure 7. 4145.7.4146 Effect of elevated temperatures on tensile properties of 40-percent

cold drawn and aged wire, figure 7.4146.

7.4147 Effect of cryogenic temperatures on tensile properties of bar stock

and cold-worked-and-aged bar, figure 7.4147.

7. 4148 Effect of cryogenic temperatures on tensile properties of STA sheet,

figure 7.4148.

7.42 Compression (see also table 7.411)

7.4ZI Stress-strain curves in compression for sheet at various temper-atures, figure 7.421.

7.4ZZ Effect of ten_perature on compressive yield strength, figure 7.42Z.

7 43 Bending

7.431 Annealed (1800°F, 982°C) sheet shall withstand, without cracking,bending at room temperature through the angle indicated below,around

a diameter equal to the nominal thickness of the nuaterial with axis

of bend parallel to the direction of rolling (ref. 7.15):

Nominal thickne ss Angle,

inch rnrn de_, min

to 0. 249 6.32 1800.249 - 0.'149 6.32 - 19.0 90

7.44 Shear and torsion (see also table 7. 411 )

7. 441 Effect of temperature on the ultimate shear strength, figure 7. 441. :}7.442 Effects of cryogenic temperature on double-shear strength of cold-

drawn and aged bar, figure 7. 442. _7.45 Bearing (see also table 7. 411)7.46 Fracture

7. 461 Notch properties: 7.4611 Effect of temperature on notch strength of cold-reduced and aged

; sheet, figure 7. 4611.7.462 Fracture toughness

7.4621 KIC = 181 ksi-bF_o_,(641 kg/[_m al') for forging, cold worked and agedat 1250--1300 F (687 --704 C); specimen 3.0 in (76.2 ram) thick by

3.4 in (_,6.4 ram) wide, with crack length of 0.65 in (16.5 turn);_i (ref. 7.16).

J

XXXXX-050

TABLE 7. 121. -- AMS Specified Properties for Various Products

Source Ref. 7.1

Alloy A- 28 6--, , , m,

Ft., min F t , rain e(4D), Redn.Productksi g/m ksi kg/mm . in, Area, Hardness

'-' ,......... |

Sheet, strip, and plate(air melt);1800°F (982°C) ST

0.001-0.0015 in (a) 105 73.8 - - 10 - ->0.0015-0.002 105 73.8 - - 12 - ->0,002-0. 004 105 73.8 - - 20 - ->0.004 105 73.8 - - 25 - -

1800°F (982°C) STplus aging {b)0.001-0. 0015 in !25 87.9 95 66.8 4 - Rc,24-35>0.0015-0.002 130 91.4 95 66.8 8 - Z4- 35>0.002-0.004 135 94.9 95 66.8 [0 - 24- 35>0.004 140 98.4 95 66.8 [5 - 24- 35

Bars, forgings, tubing,and rings (air melt);1800°F (982°C) ST BHN,plus aging (b) 130 91.4 85 59.8 15 18 248 - 351 _

Bars, forgings, and _%

tubing (cons elec melt)l1650°-F (899°C) ST BHN,plus aging (b) 140 88.4 95 66.8 IZ 15 Z77 - 363

Bars, forgings, tubing,and rings (cons elec);1800°F (98Z°C) ST BHN,plas aging (b) 130 91.4 85 59.8 15 20 Z48 - 341

(a) 1 inch = Z5.4 mm

(b) 1325°F (718°C)for 16 hr, AC.b

43

XXXXX-051

TABLE 7.411. -- D_esi_n Mechanical Properties for STA Material

Source Ref. 7.4

Alloy A- Z86

Form Sheet, strip, Bars, forgings, andand plate mechanical Lubing

Thickness >0.004 in Cu_Asumable elec-

(>0.102 ram) trode melted

Basis S S S

Ftu, ksi (kg/mm _) 140 (98.4) 130 (91.4) 140 (98.4)

Fry , ksi 95 (66.8) 85 (59.8) 95 (66.8)

Fcy, ksi 95 (66.8) 85 (59.8) 95 (66.8)

Fsu, ksi 91 (64.0) 85 (59.8) 91 (64.0)

Fbru, ksi(e/D = 1.5) Zl0 (147) 195 (137) ZI0 (148)

(e/D = 2.0) Z66 (187) 247 (173) 266 (187)

Fbry, ksi(e/D = 1.5) 14Z (99.8) IZ7 (89.3) 14Z (99.8)

(e/D = Z.0) 171 (IZ0) 153 (107) 171 (IZ0)

e, percent ! 15 (a) 15 (b) IZ (b)

(a) Elongation in 2 inches (50.8 n'Ln%) ._

(b) Elongation in 4D. :,

o:

;' 2

?

44

XXXXX-052

TABLE 7.4121. --A__verages for Tensile Test Data for Vacuum Melt

Heats from Two Different Parent Melt Heats (a)

Source P.ef. 7.7

Alloy A-Z86, i-3/4x 3-i/2 in (4.4x 8.9 cm) bar

Parent Air Melt "A," 1.9-2.3 Ti "B," 1.9-Z.3 Ti

ComDosition, 70 Vacuum melts Vacuum melts

Carbon 0.03 0.04Manganese i.19 i.29Sulfur 0.005 0.007Phosphorus 0.019 0.013Silicon 0.78 0.59Nickel Z5.48 Z4.77Cb romium 14.28 15.02Molybdenum I. 20 I. 21i'anadium 0. Z7 0. Z9Titanium 2.23 Z.22Aluminum 0.Z2 0.Z2Boron 0.009 0.008

Mechanical Prope rties

1800°F (982°C), I hr, C_,1325°F (718UC), It, hr, AC -"0.01% Ftv, ksi (kg/rnm 2) 90.7 (63.8) 97.5 (68.5)0.1%0 Fry ;ksi 168.Z (76.1) I13.Z (79.6)Ftu, ksf 153.9 (108.2) 16Z. I (114.0) ._Redn of Area, %0 45 45 :Elongation, %0 2Z Z4

1800°F (98Z°C), 1 hr, OQ,

1650°F (899°C), Z hr, OQ, i13Z5OF (718°C), 16 hr, AC0.02%o Ftv, ksi 89.7 (63.I) 99.Z (69.7)

0.2.% Fty_ ksi 106.0 (74.5) 114.6 (80.6) _:Ftu, ks[ 153.7 (108.0) 161.4 (113.5)Redn of Area, % 44 46 l

; Elongation, % ZZ 13 .... , |_ . 1800°F (981°C), 1 hr, OQ,

1650°F 1899vC), Z hr, OQ,1300°F i704°C), 16 hr, AC

; . 0.02% Ft_, ksi 87.7 161.7) 97.0 (68.2) "0. Z%Ftv . ksi 103.0 (71.4) 111 0 (78 0)Ftu, ksr 154.5 (108.6) 16Z.5 (I14.Z)

i" Redn of Area, % 43 48 °

Elonsation, %0 ......Z3. 7-4

(a) Chemica/analyses and tensile properties were reported for each

of 3 vacuum melt heats from each parent l:eat; additionally, resultswere given for top and bottom of bar. Because of the excellent agree-ment of values, averages are pr-.sented.

45 _

XXXXX-053

TABLE 7.4122. --Typical Tensile properties at Room Temperatureof Various Mill Products

Source Refs. 7.2, 7.8, 7.9, 7.13

Alloy A- Z86t'ty., 0.2% offset _ Ftu Elong, Redn in

Product/Treatment _Sl [kg/mm _ [ ksi [kg/mm _ % Area, %

Extrusions

1800°F (982°C), WQ -L 119.5 84.0 162.0 113.9 Z9.0 45.Z+ 13250F (718Oc), AC -T 105.0 73.8 130.7 91.9 27.3 51.0

1650_F (899°C), WQ -L 85.6 60.2 148.5 104.4 25.4 4Z.4+ 1325 o (718°C), AC -T 88.8 6Z.4 147.4 103.6 24.0 33.7

1750°F (954Oc), WQ -L 85.0 59.8 150.0 105.4 Z6.0 37.0+ 1300UF (704UG), AC -T 8Z.9 58.3 131.0 9Z.1 15.0 2-0.0

.m

Bar Stock

1800OF (98ZUC), OQ 96.0 67.5 146. 102.6 24.5 41.+ 13Z5°F (718°C), AC

Vacuum Casting_

X000°F (1093°C, _ OQ+ 1650°F (8990C) 85.4 60.0 106.0 74.5 10.5 17.+ 13Z5°F (718Oc), AC

.m

Tubing

Annealed 35-60 _-5-42 110. 77. 50-25

,!

462

m

XXXXX-054

2.40 - [..... "

I220 _ _

-_ - 150

_ ._.._ __

,.oo .¢._t ._/

,g 18o -- "" _ "_ r" , E_b,O

fm J 7 J160 ..............

J CR + aging 8 to 16 hours -- 110

_ at IZ00°--1250°F

. t// (6490 --676 ° C)140 --

120

60 _._

40 - -- ----I-_._e_i

_ 20 ._ __ _ -- i'

..L.._ m_mm_ m

- 0 I

; 0 ZO 30 40 50 60 70

Percent Cold Reduction .

i! FIGURE 7.4123. --Effect of cold reduction on tensilepropertiee of aged A-Z86 bar and wire.

t (Xef. 7.z)

i -

×××××-056

1800°F(_82°C), 1 hr (argon),_ Tension

4. 1325°F(?18°C), 16 h.rs, AC

100 ! 70

60

80

50

_z

• 60" 40

3O40

2O

20

I0

0 0

Strain, length/length

FIGURE 7.4131. --Stress-strain curves in tension for A-286 sheetat room and elevated temperatures; 0. 062 in (I. 57 ms).

(Refs. 8.10, 7.11)

200

t600 ° F(98Z°C|, 1 hr {argon), C_+ 1325°F_ 718°C), 16 hrs, &C

120

16o

_ ----- -'_6oo _o-'ci "I

120 _ .100°F(_93 'C) _ __

'; .... _ _ ' ; I _ ' ' _ ""

• _;r o / 1000OF1538 I L _ _ :

_, +lioo°! .... 60, 80 ..

i

Tension : .... 30

0 0.15 0.30

Strain, lensth/lemlth

FIGURE 7.413Z. -- Stress strsin ¢r ryes to fs_dm'e to• A- Z_ sheetat room _ elevat_ temperMures.

(t_fs. 7.10, 7.11)

49

XXXXX-057

160 ...........i.........I

-423 _ F (-253 '°c,) 1O0J

I

lZ0320OF (.196°C) 80

-_ 70OF (Zi°C)

¢ 60 _80 ....................... "--

.... . 40

40 _ 1

20

Tension

O 0

0 2 6 8 I0

Strain, O. 001 length/length

FIGURE 7.4133. -- Typical stress-strain curves for A-236 shee_.at r,_,orn and cryogenic ternpe:atures; 0.050 in (1.27 rnm).

[180005 ` (98Z°-C), AC, 1325°F (718°C}, 16 hrs](Ref. 7.17)

A 50 I'i

XXXXX-058

0 tO0 200 300 400 500 600 700 EO0 °C

90

u 40 __, <, '_ ....... '"I ' ' " 'o_ ,-- xi_.,: .U_ ._ijmL_ :L::... _4--:-

o : '. Strength at temperatuce _:'_! ; :t;!:" 'i_l I_'::, Exposure up to 1000 . s .,. _ It ...... _

l 1 '1,, _TI, ,I, _.. li.,i ...... I+ ,.I ..,

0 200 400 000 800 I000 1200 1400 1600 °F

Temperature

FIGURE 7.4141. -- Effect of temperature on the ultimatetensile strength of A-Z86.

(Ref. 7.4)

o loo zoo ._00 4oo 5o0 C_o 7oo 8oo °c

+I.+L+.._.LL_._ ,{X!$1_ :'i'f. "r.:,i;I,;l[: ,,!!h_ ti'l,lir,,

_,!'.!l!fitlill!lt,_:i_L';ft-',:IlIHIIU _' I _ .lrI r_lfr i' il_ :;,_",

- _ , ,tr. !t! t.lf fl _ t ;.;, t_" I__i !_,_1_!,_f ,,it !i_t Str_'ngth at temperature i_"¢f ....

40 I{[-Hi_',xposureup to 1000 hrs 11:11_i 7ii{HT!IifT!ltffll_Hi..... i 1-!I, _ ,i20 _h+, t,,, :::..:,!_t!,,.I,t!iI!t_l!; •

0 ZOO 400 600 800 1000 17.00 1400 o_

Temperstur •

FIG rile 7. 414Z. -- Effect of temperature on the tensile. yield strength of A-Z86.

(Ref 7.4)

}

i

" i

i

×××××-059

_1 i_:>I _ "_<x>_Nr,," 0 o o

•-_ 0_ _ _ 0 _ _0 ,..4

'lile '°":.,.'_'__L__' '_'" i', _,' : :Z_L.=':'' : _-0;_._

-, -: _r'q

.,, ;. ! o ;

• i'1 t' .t i %t _ ,_o " :' -, 1:'-i': i...... t I :1 o lI.<...0 _ O

u ° ° o o a.-i CO ,,0 _I' II0

_0 i IP--,E -_

' 7!. !- -_.... !! .7__ _ !/_ "°-:" '

, ,, -tt--::: - 1-I-.' t , /_ t , .I i I _ ,.,= ",° , "_

., .'. i..i .. _ _i--I .................. ®_ -'-<><, I......... _ II ;.,'U il..... , "

_" "! " -'" "' '-N ----- I _ @ ,..I lit

..... " '......ill-:---!_:! ..... i, , - .......... " _, i_.....T_ II _ ".el:IN I

":''_.'---_'j" tt44-4-; I: ==:_ =' ::3::";t i .....F......i..................... +

• :. r_1._, _ i_i,, ! [i : i._i .:.:.<+ =o ;il i I , I i .... o

<; ,_ _I _ II ®° ,,,° 0 O0 0 0 0 0 0 0NU'I eel ,,.i ,,,O _ N

_ lml l=,,i

,, 18_ 'qlllluo,ilti luolllod 'uol_l|UOl_

k

{_ 5Z_ g

×××××-065

_ ! . _ _ :,, :,-_--_-_--!---l-_.,_'-i--.-_--_--._- _ ,.,,,., . _ .I ! _ !_-"_-_._ _i ,.,'-'_, , , , _ "0 ......,

, ,-< "--.- ]-...I,I_[.._,.... _ _,_-, ,,or,- , , _ I;) >)'(- I - • _ --, --- _ _.,,cI

: : Ioo I i I

_.I-!-_=')--+I-;....!_. ,:-..-_I! _._---I'_I! '.= .,

,j).,- _ [ : :.,..,_V-! _'_ II Ii i I ' I-!I :.... _ 0.3,_

-)'_: I i i " i _ I I i , i Bg]0 0 C_ 0 0 0 0 0 0 C_ C, 0 0

_.e_ 'q_3uo_IS 'uoF_3uol_I

e'r..u',.u/ 8_I0 0 0 O _s_ ._

(,_ _ 0_ _,- m _ 0 •

°J_"_'_ ,,'_-- _ ' ' ' ' ", _ " l _!--

I 0 _ "

--I--I-44-i_ i..L...,.,_" ' i o_-_-_ _i-__ ......- -_._ 1 " _- . _..

...._-_ I ' ' / _

-.._-5--:__....I-.-':?-:-:-,-_..M__i_.i__'_i _ , I''_"_ ; ' ) ! i

. Ii I )I; ,--I i !._+_.___,_li_..__.Ir,

i', ,:: 'I ': /.. / ! 1 ' I ' oo o o o o o o = o o o o o

0 _0 _ m '_ _ N

Tsq 'q31_oz_S 'uoII1UluoII]

XXXXX-066

-250 -200 -150 -100 -50 0 °C

o _ I ....... 7- ......... u ' ' "

260 - _Ftu - 180

' - 160220 -

-_ - 1.40

_' 180 - _-'_

_'"_- - lZO _-- 0.250-in (6.35-ram) bar; "_

1800°F(982°G}, 2 hr, CW40%, Ftu ,_+ 1200°F(649°C}, 16 hrs, AG

----5/8..in(15.9-ram) bar stock; _%140 - 1800°F(982°G}, ] hr, OQ, - 100

+ 13Z5°F(718°G}, i6 hrs, AC

Fry - 80100 "-- --" --..- .,,..,. _

T - I l I I I [ II i i

50-i i i i._I,

- "_ 30- ,

# (,l , o , n , I I t I ! , _-_. , , ) ,, ,,,,

_4 30 ..... _ ....

zo-

10

-400 -300 -200 -100 0 100 OF

Test Temperature

FIGURE 7.4147. -- Effect of cryogenic temperature ontenmile properties o£ A-286 bar stock and cold-worked-and-aged bar.

(Refs. 7.Z, 7.14)

;: 54

XXXXX-067

it

55

XXXXX-068

°,a_r[

100 ZOO 300 400 500 600 700 °C

_ 100 ::'" ,:": r:::':: ":'": ........ :'':::'": ::::": ....... :" .... ;wmg • • • mmm am mmliem • • mmw mR • mmwwew • ww_w

u ._ i:..":".:':.:::.::'::":::-:'..".:,'__!_H_ _!__!_ !_•r _ IIlll lllll Illll IIIll Ill._ • ="III I fill II I!_ IIIII IIIllll Ill Illllll I_

f] _ :::::::::::::::::::::::::::::::::::::::::::::::::.....,:::::,:-::::::;"_ _ so :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::! Strenb:h at temperature :iii:ii_.::_ii"iii:.".'!:||!m eewew m.w.,.wwmw _m_

f_ : Exooeure up to _,000 hre ::::::::::::::::::::::::::

0 ZOO 400 600 800 I000 1_-00 °F

Tempe r_ture

FIGUI_E 7.4_2. -. Effect of temperature on compressiveyield strensth of A-_86. (.Ref. 7.4)

56

XXXXX-069

100 Z00 i00 400 500 600 700 °CI-_

,_ 14fll" f_ | l

......... /,_ t,l,. _! !-It! ...T

_ 60 Strength at temperature T_,,,,_;_:,_: ,:_

o° LExposure up to 1000 hrs ":11:-+.i_'i 7ii!Trl ,i t ril i i _'" _' filTi_

0 200 400 600 800 I000 iZ00 °F

Temperature

FIGURE 7.441. --Effect of temperature on theultimate shear strength of A-Z86.

(Ref. 7.,I)

-Z00 -I00 0 °C

i150 iI__ --_- .- --

•$ - _ -__ 100

Fsu130 \ - 90 H ,

4.i .............

t.., ] _---" - 80" t 'o..... F_y.i::

--4-- ............ "_ -- 70

_ _' "_ ,,It'3' 90 I

{ -400 -200 0 200 _FTemperature

, FIGURE 7.44Z. --Results of double-shear tests on0.312-in (7.92--mm) bar; cold drawn m_d agedat 1200_F (649_C), 16 hrs.

(Ref. 7.14)

57

XXXXX-070

58

XXXXX-O71

Chapter 7 - References

7.1 AMS Material Specifications, Society Automotive Engineers,Inc., New York; latest Index, May 1971.

7.Z Universal Cyclops-Specialty Steel Division, "Uni_emp A-Z86,"}IT 3020, 1971.

7.3 American Iron and Steel Institute, '_Iigh Ten, perature High-. Strength Alloys," New York, February 1963.

7.4 Military Handbook 5-A, Dept. of Defense, FSC 1500, "MetallicMaterials and Elements for Aerospace Vehicle Structures,"February .]966; latest change order January 1970.

7.5 1971 SAE Handbook, Society Automotive Engineers, Inc., New York.

7.6 Superior Tube, "Super Alloy Tubing," Bulletin 71, Jm:e 1968.

7.7 Republic Steel/Special Metals Division, "Data on Some RepublicSteel Consumable Electrode Vacuum Arc Remelt Steels," June1969.

7.8 R.J. Fiorentino and A.M. Sabroff, "Availability and MechanicalProperties of High-Strength Steel Extrusions," DMIC Report 138,October Z6, 1960.

7.9 Precision Metal Molding, ZZ, 57 (September 1964), "Vacuum-, TVlelte_ investment Casting-'_lloy_."

7.10 J.R. Kattus, J.B. Preston, and H.L. Lessley, "Determinationof Tensile, Compressive, Bearing, and Shear Properties atElev_ted Temperatures," WADC TR 58-365, November 1958.

! 7.11 J.G. Sessler and V. Weiss, Eds., "Aerospace Structural MetalsHandbook," AF,_L TR 68-115, 1971 Edition.

: 7. lZ R.H. Raring, et al., "Progress Report of the NASA SpecialCommittee on Materials Research for Supersonic Transports,"NASA TN D-1798, May 1963.

7.13 Carpenter Technology Corporation, "Carpen_-Jr A-286," Technical' Data, June 1970.

7.14 J.W. Montano, "An Evaluation of the Mechanical and Stress Cor-rosion Properties of Cold Worked A-Z86 Alloy," NASA TM X-&4569,February 12, 1971.

59

XXXXX-072

7. !5 AMS Specification 5525C, as revised II-I-68.

7.16 K.E. Fritz and D.R. deforest, "High Strength Turbo Generator

Retalning Ring Forgings of an Age-Hardenable Austenitic Alloy,"

J. Materials, 3 i_), 629 (1968).

7.17 E.H. Schmidt, "Fatigue Properties of Sheet, Bar, and Cast

Metallic Materials for Cryogenic Applications," Rocketdyne Eng-

ineering Report R-7564 under Contract NASS-18734, 30 August1968; see also NASA Tech Brief 70-10199.

6O

XXXXX-073

. TL_,'¥

Chapter 8

DYNAMIC AND TIME DEPENDENT PROPERTIES

8.1 General. Alloy A-286 has excellent dynamic and time-dependentpropOSes at elevated temperatures; for example, the relativelylow stress-relaxation makes it particularly attractive for high-temperature bolt and spring applications (ref. 8.1). Additionally,experience has shown that for good design, A-286 has sufferedpractically no failures at cryogenic temperatures. On the basis ofsimilar strength level and grain size, i_. has better fatigue strengththan K-Monel (ref. 8.Z).

8. Z Specified Properties

8. Zl AMS spe ified stress-rupture requirements, table 8.21.

8.3 Impact Strength

8.31 V-Notch Charpy impact data for bar stock at cryogenic temperatures,figure 8.31.

8.32 V-Notch Charpy impact data for bar stock at elevated temperatures,figure 8.32.

8.48.41 Creep and creep rupture data8.411 Creep strength of A-Z86 bar at elevated temperatures, figure 8.411.8.41Z Stress to rupture at elevated temperatures of tubing, figure 4.1Z.8.413 Stress rupture properties for annealed and aged A-Z86 at elevated

tempera**ures, figure 8.413.8.42 Linear parameter master curves8.4ZI Parameter plot of ,_y,pical stress-rupture life for bar, figure 8.4ZI.8,43 Stress relaxation data8,431 Relaxation of A-Z86 helical compression springs at constant deflection.

figure 8. 431."i 8.432 Relaxation of springs with various stresses at 1000°F (538°C),

table 8.43Z.i 8.433 Producers' design data for boits at elevated temperatures, table 8.433.

• 8.5 Stability (see also Chapter 7)

8.51 Effect of exposure on tensile properties of ¢old rolled and agedsheet, table 8.51.

' 8.52 Effect of exposure on notch strength of cold rolled and aged sheet,tab13 8.5Z.

8.53 Effect of exposure and test temperabare on shear strength of sheetand bar, flsure 8. S3.

8.54 Effect of exposure and test temperature ¢m bearing properties ofsheet, figure 8.54.

61

t

XXXXX-074

8.6 Fati[_ue

8.61 Reversed-bending flexura/ fatigue data for A-Z86 sheet at roomand cryogenic temperatures, figure 8.61.

XXXXX-075

.. gq,'¥

TAB,,E b '_2. --Relaxation of Sprin_s with Various Stre.oses

at 1000°F (538°C) (a)

Source Ref. 8.11

Alloy A-286 .....

Temper 15% RA

Stress Relaxation t ,_oLoad Lossksi kg/mm _- 5 hr 10 hr 20 hr 50 hr 100 hr 140 }lr_

I0 7 5.0 5.0 5.0 5.0 5.0 5.0ZO 14 5.0 5.1 5.5 5.5 6.0 6.0i40 28 5.8 6.3 6.4 6.8 7.5 7.560 42 4.7 5.5 6.0 6.4 7.2 7.580 56 6.0 6.8 8.Z 9.0 I0.0 I0.0

TABLE 8. 433. - Producers' Design Data for Bolts

at Elevated Temperatures

Source Ref. 8. lZ

Alloy A-286

Temperature InitialTensile Stress Min Relaxed Stress Design Life,

OF °C ksi I kg/rnm= (a), ksi Ikg/mm_ hours.i

700 371 40 Z8 40 Z8 -850 455 90 63 - - 35,000

tI000 538 70 49 - - I0,0001000 538 30 21 - - 10,000lZO0 649 40 Z8 Z6 18 -1350 732 20 14 - - 10,0001400 760 40 28 10 7 -

_, .....

(a) Minimum relaxed stress after 1000 hours.

64

XXXXX-077

•"_ 6S

XXXXX-078

XXXXX-079

-200 -150 -100 -50 0 °C

i :_- :;',l ;,'._I_,',' _", :: ,; ',, ', ;_ ., ;',i _ ."7"I79-,.*-,,.;.,,.L'_.L,;I _,±__ _t-+ ":._ I 'I'1'_! '*!' t ,'',''_,' f" ,., ,;,. _**.t ..'r ,! _ _'*"_[!] ,,

50 ".'," .LL._ "_, '!.l':'.*.l]'l !!'.::',I _]'_L!:.::I ;':l!:itt.]if _' _ I ':!:!!'.l i P'I_f! '

'_ ..!_--;:----?/8-_.n (22.2 mm)_r: _ ;_:',iI_ k 6

:,._ --.-- GW 40% {from 3 _:: :--tL' !-::._ --]i-:'. :_ /' "_to ":.t diff. suppliers) ti:'/:' ';:';:t:i:;t'" ::"_li'_ '_u 4

i:;I;:I:;I!: :iI" L' .I _.__:I:_'

i

-300 -200 -100 0 100 OF

Test Temperature

FIGURE 8.31. -- V-Notch Charpy impact data at cryogenictemperatures for A-286 bar stock.

[518-in and 7/8-in: ST 1800°F¢98Z°C), I hr, OO +1325°I;(718uC),16 hrs, AC.

CW 40%: aged IZ00°F(649'C , 16 hrs, AC_(Refs.8.1, 8.4, 8.6 8.7)

0 150 300 450 600 750 °C

.,, _:,1_', :1,,_T_., ._ '.-1.''_ 9v v :.v.,-r'r,.,._'n,,"v'Plltl+l , I!!i:I]I i: ,i ', _.;; ;"

60 " ..t.:_' : , ._ ',_ ,; _ '.: _:' :..

""o 40 _': t'_:'.H,;!'_.,_L2_Uk!d _ • ,;

ii--7/8-in (Z2.Z-mm)bar ,, __T[-- -- 5/8-in (15.9-ram) bar_ i I: 5_ " 30 '"!1-t:.. _........;l'l'";:::l"_J.'-:' ....... I":'1 ' :1 ."1":' .,::'1'.,.,]_,i.1.,..:1; q' ,:I;_

0 400 800 IZ00 1600 °F

Test TemperatureI

FIGUR_ 8.3Z. --V-Notch Charpy impact data atelevated temperatures for A-Z86 bar stock.

(Refs. 8.1, 8.4)

67

XXXXX-080

g50 600 650 700 °C70

9060

._ I00 hrsm

70 _ 50

lO00 hrs \ 40

50 \\

\ 30

---,-1% creep----0.5% creep \ \ \

30

1000 1100 1Z00 1300 OF

Test TemperatureFIGURE 8. 411. -- Creep strength of A-Z86 bar at

elevated temperatures. (Refs. 8.1, 8.3)

600 650 700 750 800 °C80

50

60 40.,'4

- ?,; 3O® 40e_4

! 4a

t u_ 20

! zo10 ,

0 0

1100 1200 1300 1400 1500 OF

_. F.acpoour • Temperature

FIGURE 8. 412. --Stress to rupture at elevated temperaturesof A-286 tubing; 0. 250 in (6.35 ram) O.D. by0. 028 in (0.711 nun) wall. (Ref. 8.8)

68

XXXXX-08i

550 600 650 700 750 800 OC

:!'_i tT,!l', _ t;'i, :Jl!|_::'. i :, l,lt til!,,

80 El 1:'! I'.T'. ::It :!l! t_i_ :!!: :_:l "ll ' ' '1 "

z. i::I iI_..... :i:__,._,, ,.::I, I_:..:,:!_:I.::I,..I_:I I.:.I._I I. - so............................ Ii,,t, ,

_.2:; '_;; '"_':' 'i:t :.ii :.: _: 100 hrs ". /:':: '. ": ': ":.:" "60 "'"! ....... ;_ 40 _•"4 ':l:l: 1 !-;'%, "l :,,

_:i._,:; _i " ,x '

• ,:, '::: ', ': '.' 3040 ....... ::'" .... I4ll

....... .',' ' l:. l'.. ' '_ .'_ .,: '" : : ' '

.... :IN !I : io,) Z0 -::.......................',_ : : '-. . . ' . : .......... ' '................. : i i:, _',. il ; 1000 hrs " t :i_,..l :

............ /, I, .H, ,,,_

60 1• _'- _';:'_ ....... _' ' " ' I .....

:_;'i+, :_ ....... ,I I ., ,+,. _+; • i. ,' .,_., ,: . .. H:' '_i,'_":l :l,:I_ 40 "";'_'_±' ' ':4: ' !' ,, I , I ,'l !_ ' ;.._ .'ll ! l l'

o ,!_, . ...... , ..................... .,_,,, _"....... _ I.. IIH.,,I .... I .... I , .I,I:II!;I_ ,. _ , I00 hrs ,',I; _,!"' : t_,'l'_' ' ' l :'' .l,vvv II.LO _)I,I" ,' ,'_ , , I _I

ZO

0 !_!.... lt'"l""l .... I" I

1000 1100 lZ00 1300 1400 1500 OF

Temperature

i FIGURE 8. 413. --Stress rupture properties of annealed and' aged A-Z86 at elevated temperatures.

(Refs. 8. I, 8.9)

69

XXXXX-082

. ._,r¥

_cucu/ _

c_

. 8 _ o_2._

• _O N "0

,_ oo ,

M_-'Vo

o

!s_ 'ss_18

o 0 0 o Q _ I

_.._,,_,.,;._..................._,__.,,__ ._ _ o ®t,_llllllh_llll._llllllllllllh_ll,_llllllUlll-'.1 _,, , , ' ' _ _ O0"llllllIllllllllllllllllllll IIIIIt11111111111_1 I I I I I i £ I z I

H+H-I-_ _bFt-Ft+)-Prl.-H-t--_, ;IIII IIIIIiiiii _o0 Ii'_r_-t_l',lllll',;',l',ll .......... • .,='_'_' "IIIIIIIIIIIIIIII/ II[lilllllll 11 rll [I ] Ill. Ill[" Ill I II1 I I l I f I I l •

•_,-, N_.

::"""""""'==':::":='::==== amlIT'IITT_IlTT,Ii l_l: I TTI I T r alllelmiiimi_lmllimllllllmlmli_mmmmml

'_I .,_I,_III IIIII I.=III _ -'I II._1113111111==IIIII! Ill IIIII" ,1111 IIIII IIIII IIIII IIIII I • II IIII IIII I1_111 IIIII IIII IIIII

r'............. ' ............ HI ''''I '''I ''=== *==== =i_l i .... _ _

::::::::::::::::::::::::::::::::::::::::::::::::::::::: en_ _'_ _ 'I|ai Inll anus am ml • • Illml *Ilia |llllllm Ilmllmll enroll II HI III n

............. ,.I.I_ ........ ...,.... ............ l--._ _ .. _i Ilillllllllil line • t lie lie • IIIOllinlmllOllli lilli/m

,I............ I .... I [i_ _==_'.,,l,,.l._l...u, ........ [__:--_ _ h ,.__III Iiiii lllllllll I NIIII lill_lllglill

,_11_ h_ll ll;;l ._'"_ .'IIII lllll!lllllll I_II IIII==I _ ! _

lille Ill' _il_ IlUl lili II0 | m011im lmmll nine *

] ,0mati,_ a mill, .eRrata limll nmmllll ll0el elmira IIl_ .imP. _ iN-

) "illl"llllllll_ll_l'_llllllh_llllllllllll_Ilu ,.w-_._=_m ¢'_+ I k":i t ilalolooelllllollmmmwlmu_mmllllllllllllllllmlimi_a_i mlmmllml

_', ,me , els|m cmoil Olln ll_W llilll mmmwi ¢1111011llll l II sinai mmmm_ Ill ai_m • 0 _

: ,.+;llllllll:_ll._lll=llllllll._lllll:llllllllll:_=_l _ _ _ v,Iml|mill*iml,limammmloilmHl mmummm hill IN marealllmmimmaoommmlm mmmm INnm II mmlelHlina| el oil ,all mlmnlmllmimi _m *...._.._..........._n.n=...,..._........... EqI_I_IE-_- ,,i _,

-. ,,.51,_lll ;llll _ _!_ / m_h_l._ll _I III.*IIIIII_1111111. _ _ IIii.0_loll Hill *HI II _111 I Ill mlllliOllllll IIII II Ill IIII I / i I

Illlle I n l| |ell • mm

_ o o o o _ _o

, lm_ 'mme_r_ls

?0

XXXXX-083

0 100 200 300 400 500 600 °C

120'1 I v i i I I

- 80

_m 7 / 8- ;.n .(22-ram) b_r;

e._ 100 - - 70

60 _o_

80-0.06Z-in (I.57-rnnl)sheet;

O 30 rain 50' 0 1000 hrs

60 | I I I I0 200 400 600 800 i000 1200°F

Test Temperature

FIGURE 8.53. --Effec_ of exposure and test temperat_ure on shearstrength of A-Z86 sheet and bar. [1800°F (98Z°C), I hr, OQ,13ZS°F (718°C), AC] (Refs. 8.14, 8.15)

0 I00 Z00 300 400 500 600 °C

i I i l I I_,. • 30 min, e/E - 1.5 - 2Z0

300 _ O 1000 hrs, e/D= 1,5qD 30rain, e/D= 2.0

__ _ I000 hrs, e/D= Z.0 Z00

Z60 180

160 ...&J

zzo

140r_

180 _ 0

Fbry Q )20

. .o , ,0 ZOO 400 600 800 1000 lZO0 0 F

Test Temperature

FIGURE 8.54. -- Effect of exposure and test temperature on bearingproperties of A-286 sheet, 0.062 in (1.57 turn). [1800°F (982°C),1 hr, OQ, 13ZS°F (718°C), 16 h_s] (B.efs. 8.14, 8.15)

71

XXXXX-084

. fJ,_¥

XXXXX-085

Chapter 8 - References

8.1 Universal-Cyclops Specialty Steel Division, "Uniterup A-Zg6,"I-IT 30?-0, 1971.

8. Z E.H. Schlr_dt, "Fatigue Properties of Sheet, Bar, and CastMo-tallic Materials for Cryogenic Applications," KocketdyneReport K-7564 under Contrvct NAS8-18734, 30 August 1968;see also NASA Tech Brief 70-10199.

8.3 Carpenter Tecimology Corporation, "Carpenter A-286," TechnicalData, June 1970.

8.4 American Iron and Steel Institute, "High Temperature High-Strength A11o7s," New York, February 1963.

8,5 AI_ Material Specifications, Scciety of Automotive Engineer_,Inc., New York; latest Index, May 1971.

8.6 ALlegheny Ludlum Steel Corporation, 'tA-Z86," Product Data.

8.7 J.W. Moncano, "An Evaluation of the Mechanical and StressCorrosion Properties of Cold Worked A-Z86 Alloy," NASATMX-64569, February 12, 1971.

8.8 Superior Tube, "Super Alloy Tubing," June 1968.

8.9 ASTM STP-160_ "A-286," August 1934, p. 70.

8.10 I_.G. Matters and R.E. Lochen, "Materials for Helical Com-pression Springs for Use at Constant Deflection from 600 to1400 F," ASTM Proc., _ 672 (1956).

8.11 J.W. Besemer and V.A. Stanton, "Springs for Use at HighTemperature," Metal Progress, April 1965, p. 84.

8.12 Metals Handbook, 8th Edition, Vol 1, "Properties and Selection• o_'Materials," Amerciau Society for Metals, MetLls Park, Ohio,

1961.

. 8.13 R.H. Raring, et al., "Progress Report of the NASA SpecialCommittee on Material Research for Supersonic Transports."

i NASA TN D-1798, May 1963.

i

73

XXXXX-086

8.14 J.B. Eattus, J.B. Preston, and H.L. Lessley, "Determinationof Tensile, Corapressive, Bearing, and Shear Properties atF.levated Te'._peratures," WADC TR 58-?_63, November 1_58.

8.15 J.S. Sessler andV. Weiss, _d_., '_Aerospace S'_ructur_,l MetalsHandbook," AFML TR 68-115, 1971 Edition.

74

XXXXX-087

Chapter 9

PHYSICAL PROPEP.TIES

9.1 Density, p(at room temperature)

0.Z86 lb/in 3 (7.94 g/cm s) (refs. 9.1 through 9.5)

9. Z Thermal Properties

9.21 Thermal conductivity, K, figure 9.21.9.2Z Thermal coefficient of expansion, a, see figure 9.21.9.23 Specific heat,

0.11 Btu/in 2 OF (70 °-1300°F)0.11 cal/cm°C (Z0--700°C) (refs. 9.1, 9.2)

9.24 Thermal diffusivity

9.3 Electrical Properties

9.3i Electrical resistivity, table 9.31.

9.4 Magnetic Properties

9.41 The alloy rerne.ins essentially nonmagnetic, even after coldworking (ref. c. 1).

9.4Z Permeability (H=200 oersteds):Solution treated, 1.010 (ref. 9.Z)Solution treated and aged, 1. 007/1. 003 (refs. 9.2, 9.1)Cold worked and aged to Rc 40 min, 1.015/1.020 (ref. 9.1).

9, 5 Nuclear Properties

9.51 The maximum hardening of austenitic steels by irradiation occursat about 300°C, and causes increases in room temperature yield andultimate strength, accompanied by reductions in ductility. Annealingat 5000 to 600°-C can remove these changes in tensile properties. A

, _ drastic reduc*.ion of ductility takes place at elevated temperatures and! cannot be removed by annealing to 1350°C. The effect of irradiation

on creep has not been firmly established, but there is general agree-'_• ment that elongation _t failure is reduced (ref. 9.8).

9.52 Effect of irradiation and testing at -257°C on tensile properties of" A-286, table 9.5Z.

9.6 Other Physical PropertiesI

9.61 Emissivity9.62 Damping capacity

XXXXX-088

TABLE 9.3i. -- Electrical Resistivit)r

iSource ' R.efs. 9.1, 9.2Alloy A-286

Temperature Microhms-in [

L OF [ °C i Micr°hms'cm

87 30.5 35.8 91.01000 538 45.5 115.61200 649 46.8 118.81350 732 47.3 120.11500 816 48.2 122.4

TABLE 9.52. -- Effect of Irradiation at -257°C on Tensile Properties of

Allo_r Tested at -257°C

Source Refs. 9.6, 9.7

Alloy A-286

Fh,, ksi Ftu , ksi Notched F t. ,ksi Elong, Redn inSpecimen (k_/mm=) (kg/ram z ) (kg/n_ _ ) % Area, %

l,

Unirrad. 135.9 (95.5) 223.6 (157.2) 185.8 (130.5) 37.5 31.0Irrad.(a) 137.0 (96.3) 219.7 (154.5) 188.6 (132.6) 30.4 32.2

= Unirrad. L149.6 (105 2) 235. (165 Z) 216.4 (152 1) 34.5 46.5(b) " • •Irrad.(c) 152. (106.9) 229. (245.7) 245.7 (172.7) 33.5 16.i i

Unirrad. 156 8 (110.2) 238.2 (167.4) 255. (179.3) 31.8 42.2(b) •Irrad.(c) 165.7 (116.5) 238. (167.3) 239. (168.0) 31.0 39.7

i' -(a) 5.0 x 10 is n/cm a

, (b) Two different heats(c) 1.0 x I0xv n/cm a/

¢

i"

t

._

•_i- 76

XXXXX-089

100 200 300 400 500 600 °C

: : : ; :

l : : "'" i" "" :• . ; :.....i • . . ._. . :-. : ...................:..............

. ' '. i i : . : |• " !' • . i : - ,' • .: : J

• • I " . _ " : : _, , 72014.... , - .. ,. . . , . /..I:/'; ..... : • i : '. '0• : ! " i " I , I I / i l o

• " • . : ' • i • '/ .' • l _.g_.... "......................................................... • -: s--- -- 19"-= i _°"'" I ....." " " I ...... : " " " : il " "'" .' "",,_ (,,)

0.05 12 ....... }.... i........... " ...... "...... -..i ..... -.._.$." "_ ""•" "i............. : • _ ; ,_ c:

, I : _ • I... ; . .__) .,-, u•. _ . , . , ., , • ; : . .'-"" •....... I _1.7 I: ;" :• , • : • : i , _

0 "; . _. 0

o10 ".'"l.....r....i'" i _ "--_" ....: ":"....90.04.... - - 16 6"--.('; _ .: ,I" : 1.... ' .. .i_. m_,.. • :' ....' .. i : • .i'... : '. )."

' i " / l_ "_" i I : ! " : .... I"

ifaglliigllgg.|mV'- ........."4.........u_ _.._ "ira .re!l, . I" : I .! : i • i ',.lliltlgfillfiiglgiiP"

I .... i . "..." ..." ..." .: I , • : .. ! • o_ , , _ .....; .. , ; ---

, • I _ • L". L: L .td _ 8 l|ln|JlUJn|JlI'-l" "" "'_""_-- "";'" "". --', .......... , ...... 1- ...... _" ; . :

llhiHl.lll.llJ_ m • , • .. l ., , I i0.03 - mmmmmmp,.'! .... I I ..... t "; • " i...... .--: : .... .. !. :. :i

_ Ifliiil_ • ", • "i • • I"' i ! "" =" )"l . I • i , i:'.T..... :.......i..... ! T-I-.--:.T:--.'-I-- :........t........t. .....: t::-- ";

.................. I I i

...:: ,,1:. ": | • • | , : . • ,• . i .. u • I ". . . •..... t'" • -6 i ..... : ......, I ... I. , i _ • i I I

0 200 400 600 800 1000 1200 oF :3;Tempe ratur e

FIGURE 9.21. -- Effect of temperature on the physical ,_, properties of A-286.

(Re_.9.5) "

77

XXXXX-090

Chapter 9 - Kefereuces

9.1 Universal-Cyclops/Specialty Steel Div., "Unitemp A-Z86," HT 30Z0,1971.

9. Z Allegheny Ludlum Steel Corp., "A-Z86," Product Literature.

9.3 Americau Iron and Steel Institute, "High Temperature High StrengthAlloys, 'r February 1963.

9.4 1971 SAE Handbook, Society Automotive Engineers, New York.

9.5 _litary Handbook-5A, Dept. of Defense, FSC 1500, "MetallicMaterials and Elements for Aerospace Vehicle Structures,"February 1966; l_-test change order, January 1970.

9.6 J.J. Lombardo, C.E. Dixon, and J.A. Bagley, _'Cryogenic RadiationEffects on NERVA Structural Materials," paper presented at 69thAnn. Mtg. ASTM, Atlantic City, New Jersey, June Z7-July 1, 1966.

9.7 C.A. Schwanbeck, "Effect of Nuclear Radiation on Materials atCryogenic Temperatures," NASA CR-54881, January 1965.

9.8 M. Kangilaski, 'Radiation Effects Design Handbook: Section 7.Structural Alloys," NASA CR-1873, October 1971 "<'

78

XXXXX-O91

Chapter 10

CORROSION RESISTANCE AND PROTECTION

10.1 General. In common with other stainless steels, A-286 tends to be

pass'ire by virtue of an oxygen-containing surface film. It shows goodresistance to all atmospheres encountered in jet engine and turbosupercharger service up to at least 1300°F (704°C), and has shownexcellent performance in 20-percent salt spray tests. Because ofthe high nickel content, A-286 is more resistant than 18-8 stainlesssteels to cool, dilute sulfuric acid solutions (ref. 10.1).

10.2 Corrosion in Water. The resistance of stainless steels to corrosionin water at hig'h ter:nperatures is generally excellent. However, casehardening of the steels by nitriding or malcomizing (see Chapter 11)can decrease initial corrosion resistance to the extent that usefulnessis limited in water at 500°C. The rate of corrosion in supercriticalwater varies with test temperature. As shown in figure 10.2, A-Z86

is resistant to attack at 800°F (427°C) and 5000 psi (3.5 k_/mm2);appreciably higher rates of corrosion are observed at 1000 and1350°F (538 ° and 732°C) (ref. 10.2).

t

10.3 Oxidizing Environments. The resistance of A-286 to attack is notgood in strong, selective oxidizing environments such as nitric-- _hydrofluoric acid and boiling 65-percent nitric acid. Intergranularcorrosion may occur in the aged condition, and care must be used _when pickling with nitric--hydrofluoric acid mixtures after aging _(ref. 10.1).

Alloy A-286 is adequately resistant to oxidation without special coat-ings for service to temperatures up to about 1300°F (704°C). It doesnot compare favorably with stainless steel Types 309 and 310 aboveabout 1500°F (8160C) (ref. 10.1).

Highly localimed regions of surface oxidation have been observed inA-Z86 that is subjected to cyclic plastic strain at elevated temper-atures of 9500 to ll50°F (5100 to 6Zl°C). Apparently, there islocalized and reversed grain boundary deformation thatleads torepeated rupture of the protective oxide film, and also accelerated

• oxidation in the region of deformation. These regions become thenuclei for initiatingfatiguecracks (ref. 10.3)•

10.4 Propellant Environments. Alloy A-286 has been found compatible• _-ith the following propeTlants for long-term applications (ref. 10.4):

Condition Propellant , Test Temperature

Rust-free Aerozine-50, 55°-60°F (I0°-16°C)- Hydrazine , _100°F (<38°C)- Unsymmetrical dimethylhydrazlne, < 140 u F (< 60 ° C)_

Annealed Nitrogen tetroxide (,_0.SS/0 HsO) _ 55u-60°F (I0°-16vC)

79

XXXXX-092

10.5 H)rdrosen Embrittlement. The austenitic stainless steels are notgreatly affected' _y atomic hydrogen absorbed during descaling orelectroplating processes (ref. 10.5). To investigate the mechanicalaspects of hydrogen-induced failure in solution-treated and agedA-286, fracture toughness tests were conducted on precracked beadspecimens loaded in 3-point bending. Hydrogen test environmentswere molecular hydrogen at a pressure o_ 680 tort and an atomic-molecular hydrogen mixture at a molecular hydrogen pressure of8 x 10 -3 tort; comparative runs were made in a vacuum environ-ment. The fatigue cracks in A-286 would not propagate under thebending mode of loading in any of the environments; there were nofailures (ref. 10.6).

10.6 Protective Measures• As pointed out earlier, surface treatment ofA-286 for resistance to corrosion is rarely required. However,surface treatments used for improvement of other characteristicsare discussed in chapter 11, along with available information on theeffect that such treatments may have on resistance to corrosion.

i 8o

f

|

XXXXX-093

1000800

600

400

_ 200

°_

• I00

8060 J40 '_

2O

0

0 40 80 120 160

Exposure Time, dayse

FIGURE 10.2. -- Corrosion of A-286 in degassedsupercritical water.

(Ref. lO.Z)

i 8,

XXXXX-094

Chapter 10 - References

10.1 Universal-Cyclops/Specialty Steel Division, "Unitemp A-286,"HT 3020, 1971.

10.2 Karl F. Smith, "Stainless Steels," in C.1%. Tipton, Jr., Ed.,I%_actor Handbook, Vol 1, Interscience Publishers, New York, 1960.

10.3 L.F. Coffin, Jr., "Cyclic-Strain-Induced Oxic'_tion of High-Temp-

erature Alloys," Trans. ASM, 5__6, 339 (1963).

10.4 K.D. May, "Advanced Valve Technology," NASA SP-5019, February1965.

10.5 Battelle Memorial Institute, "Surface Treatments for PrecipitationHardening Stainless Steels," NASA SP-5090, 1968.

10.6 H.G. Nelson, "The Kinetic and Mechanical Aspects of Hydrogen-Induced Failure in Metals," NASA TN D-6691, April 1972.

XXXXX-095

Chapter I1

SURFACE TREATMENTS

11.1 General. The surface of alloy A-286 may be treated chemically,mechanically, or electrochemically to remove scale developed duringheat treatment or to improve resistance to wear, resistance to stress-corrosion cracking, fatigue life, etc. In general, the end-use of heat-resisting alloys does not require that they have a polished finish.

11. Z Scale Removal. Scale formed during heat treatment may be removedn:echanically by shot or grit blasting, tumbling, vapor honing, etc.,or may be removed chemically by acid pickling solutions. The mech-anical methods are generally employed as a supplement to chemicalmethods. In this instance, a final sand blasting will produce an attrac-tive finish; however, it is mandatory that sand be used rather thansteel grit to avoid surface contamination by metallic particles. Onthe other hand, mechanical methods are often preferred because ofthe possibility of intergranular corrosion resulting from strong pick-ling acids or prolo,,ged pickling times (refs. 11.1, ll.Z). The mostwidely used chemical procedures consist essentially of scale-condi-tioning in an oxidizing caustic bath followed by immersion in a pick-ling bath. Several examples of chemical procedures are summarizedin table ll.Z. .

]1.3 Mechanical Treatments. Mechanical treatments such as burnishing,

explosive hardening, planiahing, or peening are not generally usedfor componcnts made of A-286. However, such treatments mayoccasionally be used to advantage (ref. 1I.5). For example, ithas ]been shown that shock loading does increase the hardness of A-Z86and may effecteconomic savings by reducing aging time (refs. II.5,II.7). The peening of welds in A-Z86 sheet has produced a marked _increase in fatiguestrength compared with as-welded joints(ref.11.8).A compendium of information on shot peening for improved fatigueproperties and resistance to corrosion of high-strength a11cys hasrecently become available (ref. I1.6).

11.4 Coatings. Precipitation-hardening stainless steels are not carburizedintentionallybecause the process is detrimental to corrosion resist-

. ance and other properties. In order to avoid the effects of carburizing(i. e., carbon absorption), A-286, for example, is usually heat treatedin an air atmosphere rather than in so-called neutral atmospheres

• which contain the products of fuel combustion (ref. 1 I. 5).

All stainless steels, because of their chromium content, can be case-hardened by nitriding. Diffusion of nitrogen into the m&terial is aidedby the chromium content which facilitates the formation of a stablecase with high hardness. Thls hardness increases wear resistance,develops antigalling properties, and improves fatigue resistance (ref.II. 5). On the other hand, nitrlding detracts from resistance to

XXXXX-096

corrosion because nitrogen, introduced by ni_riding, combines with

available chromium in the surface layers to form chromium nitride,which is not as protective as chromium oxide.

A proprietary nitriding process known as "_Aalcon:izing" hab been

used for case-hardening of A-286 . The process requires tempera-tures of 920 ° to 1050°F (493° to 565°C) and times of 6 to 8 hours.

It is recommended that A-286 be solution annealed and refrigerated

prior to Malc:omizing. Case depth after Malcomizing is 0.00335-0.005 in {0.0089-0.013 cm)and surface hardness is DPH 650--850

(ref. II.9).

Torch-fu_ieu techniques for hard-surfacing of A-286 have been used

successfully for aircraft arresting-gear hookpoints (ref. II.5).

11.5 F_,lectroplatedCoatings. It.general, it is not necessary to electro-plate A-286 for the usual reasons of improving corrosion resistance

or other properties (ref. II.5). However, in order to prevent tear-ing and scoring of extruded shapes, A-Z86 has been electroplated

with an 0.04-inch (I.02 ram) layer of nickel prior to hot extx-usion

with standard glass lubricants (ref. II. I0).

Although the alloy is difficultto braze, it can be brazed readily if

coated with nickel or iron (ref. II.II). Additionally, stress-corro-

sion cracking may be pre_,ented by electrodeposited N_-Cd (ref.II.I_)

on parts which cannot be stress relieved adequately.

After descaling or other surface preparations such as wiring, jigging,machining, and final cleaning, A-286 can be activated for electro- _

plating by immersion, cathodic, or anodic treatments {ref. I I. 5).After activation, the work is transferred to the plating bath as quickly _"as pos siblc. _

!.

!

i .

XXXXX-097

- tt _

TABLE II.Z. --Examples of Chemical Descalln_ Procedures

Source Refs. II.I, ll.Z, 11.3, 11.4

A-286

Operatiou Bath Composition I Temperature Time,I _F I °C min

' (Ref. ll.Z)Descale NaOH with oxidizing additives 950 510 Z5-30Quench Ware r Ambient Z- 1 /Z

Neutralization 18% H_SO 4 + 5% HC1 170-18t 76-82 5Ki_ s e Water Ambient ZAcid treatmert 25% HNO:, F J% HF Ambient 5-10R inse Water Ambient 1

{Ref; 11.1)Desca!e Molten caustic - - -Quench Water - - -

Neutralization lZ--15% HeSO 4 140-160 b0-71 15Rinse Water - - -

Acid treatment 1Z--15% HNO_ + 1--2% HF 110 43 10,,.rose Hot water - -

1.3)Descale Oxidizing salt 900 482 -Quench Water - - -

Neutralization Z0% H_SO 4 - - ] 5Rinse Water - - -

Acid treatment 35--40% HNO s + 470 HF - - Z0Rinse Water - - -

(Rof._ll.4)De,tale i.5--Z% Nail '700-730 371-388 5-Z0Quench Water Antbien_ l/4-1/ZNeutralization Z--10%HaSO 4 70-140 ZI-60 1-3Acid treatment Z-4% HF+Z0%HNO s ;130-1_,0 55-60 5-15Rinse Water Arvbient l/4-I/2

' High-pressure Water, I00 psi (0.07 kg/mm s) Ambient (_.)spray wash .... _ ......

• (a) Governed by part configuration; I min for parts with accessiblesurfaces.

!

85

XXXXX-098

Chapter 11 - References

II.I Universal Cyclops /Specialty Steel Division, "Unitemp A-Z86,"HT 3020, 1971.

ll.Z Metals Handbook, 8th Ed., Vol. 5, "Forging and Cast;.ng," A,_ericsn

Society for Metlas, Metals Park, Ohio, 1970.

II.3 L.:[. Hull, "Techniques for Welding and Fabrication of the A-Z86

High Tempe: _ture Alloy," Weld!v_ DesiGn and Fabricat:on, 34 (I0),58 (1961).

11.4 Metals Handbook, 8th Ed., Vol. Z, "Heat Treating, Gleanin_, and

Finishing," American Society for Metals, Metals Park, Ohio, 1964.

1]. 5 Battelle Memorial Institute, "Surface Treatments of PrecipitationHardening Stainless Steels," NASA SP-5090, 1968.

11.6 Metals and Ceramics Informatior Center, ':Shot Peening for Im-

proved Fatigue Properties and Stress-Corrosion Resistance,"December 1971 (AD 735-409).

11.7 B.G. Koepke, R.P. Jewett, and W.T. Chandler, "Strengtheni,gIron-Base Alloys by Shock Wanes," ML TDR 64-Z8Z, 1964.

11.8 C. 1%.. Srniti: and D.H. Love, "Developn: ,t of Elevated TemperatureSheet Spot-Welded and Seam-Weided Joints," ASD TR 61-67, 1961.

II q Lindberg Steel Treating Co., "Malcomi_ing £or Improved Propertiesin Stainless Steels."

11. I0 L.M. Christensen, "Development of Methods, Processes, and Tech-niques for Producing Steel Extrusions," ML TDR 64-Z31, July 1964.

II.II E.D. Huschke and G.S. Hopkin, HI, "High-Temperature Vacuum

" Brazing of Jet Engine Materials," _Welding J'r Res. _uppl., 34 (5),ZZ3S(19S8).

II. IZ L.E. Gatzek, "Corrosion Control of Missiles in Long-Term SiloEnvironments," paper 916A, SAE Aeron. and Space Eng. and MJg.Mtg., Los Angeles, Cahf., Oct. 5-9° 1964.

86

XXXXX-099

Chapter 12

JOINING TECHNIQUES

12.1 General. Alloy A-286 is the most weldable steel in the group ofprecipitation-hardening austenitic stainless steels (ref. 12.1 ).It can be joined satisfactorily by fusion welding, r_,sistance weld-

. ing, and brazing (ref.12.3). Welding processes are similar tothose used for welding austeniticstainless steels (e.g., ref. 12.1).Specificationsfor A-Z86 welding wlre, flash welded rings, boltsand screws, and rivets are listedin Chapter 2, table Z.I.

1Z. 2 Welding. It is important that welding conditions be carefully con-trolled to avoid cracking in the weld or adjacent to the weld in theheat affected zone. This is especially true when large sections arebeing welded under restraint. Alloy A-286 passes through an areaof low ductility upon cooling; if restraint conditions are severe, thecooling stresses may be relieved by cracking rather than deforming.It is good practice to solution treat after weldin5 and then age harden.Heating to the solution temperature of 1650°F or 1800°F (899 ° or982°C) should be accomplished as rapidly as possible (ref. 12.3).

The production of satisfactoryjointsis also dependent upon theproper selectionof joiningmethods, proper jointdesign, and propercleaning of material prior to making the joint(ref. 12.4). Details ofweldment evaluationmethods are given in reference 12.5

Contaminatio -_during joiningor treating processes of either baseor weld metal by dirt, grease, crayon marks, etc. can seriouslyaffectresistance to corrosion. Carbon pickup can also affectheat-treatment response, and sulfur pickup can affectmechanical prop-erties. Dirt and films of oil and grease can be removed by washingor degreasing operationr; soaps can be removed with hot water. Ahot alkalinewash followed by a hot water rinse is required for solubleoils, tallows, and fats (ref. 12.4). Removal of scale is discussed

" in chapter 11.

12.21 Fusion Welding. Fusion welding of A-286 is generally performedby the gas tungsten-arc process (TIG), but shielded metal arc and

, gas metal-arc (MIG) processes have also been used satisfactorily(refs. 12.1, 1Z.3, 12.4). Welding precautions are similar to thoserequired for nickel-base alloys, such as careful control of gascurrent, arc length, speed of welding, filler metals, backing mat-

' erials, and cond'tion of equipment (ref. 12.6), with additional pre-cautions inherent iv the welding of superalloys: Stress-relief priorto welding is required for parts that have been worked or deformed;welded parts must be rapidly heated and cooled through the agingrange to avoid embrittling carbide precipitations in the grain bound-aries (see also section 12.2); as far as possible, fusion welds aredesignea in low stress areas because a matrix-strengthened filler

" i £4

XXXXX- 100

metal is generally used, yielding between 80- to 90-percent jointefficiency (ref. 17.. 7). Tooling components for welding must benonmetallic or nonmagnetic, and the tooling should not contaminatethe base metal (ref. 12.4).

12. 211 Tungsten Inert-Gas (TI, _-) Process. In thin sections under conditionso_']ow restraint, hot-cracking tendencies are minimized with theTIG process. The weldability of A-286 is improved by keeping heatinput tca minimum and using small, light stringer beads. When-ever multiple passes are required, it is usually necessary to useon_ of the dissimilar filler metals (ref. 12.1).

Alloy A-286 filler metal is usually used for TIG welding of light-gage material. In the instances where weld joint geometry is com-plex, a dissimilar filler metal is used, such as Inconel 92 whichwill also respond to the age-hardening treatment. Hastelloy W mayalso be used, but it does not age-harden. Other austenitic stainlesssteels may be used, _uch as Type 310, where resistance to corro-sion is more desirable than high strength (ref. 12.1 ).

12. 212 Electron Beam Welding. Electron beam welding has been used suc-cessfully to join A-286 to dissimilar metals, for example, a turbinewheel consisting of an A-286 turbine disc and a ring of Udimet-500blades (ref. 12.4).

12. 213 Mechanical Properties of Fusion Welds

12. 2131 Tensile properties of TIG welds at room and elevated temperature,_,table 12.2131.

12.2132 Tensile properties of MIG welds at room temperature, table 12.2132.12.2133 Tensile properties of TIG welds in A-286 sheet at cryogenic temp-

eratures, figure 12.2133.

12.22 l_esistance Welding. Sheet products and bar of small cross sectionca--'_'_e welded satisfactorily by spot, overlap spot, or seam weld-ing. Flash, upset, or projection welding are used to a lesser degree.

,, Alloy A-286 is generally resistance welded in the solution-treatedcondition, then aged or re-solution treated and aged after welding

i (refs. 12.3, 12.4, 12.7).r

12.221 Spot and Seam Welding. Precipitation-hardening stainless steelshave been welded successfully with conve,_tional resistance spot-welding equipment. Because of the higher currents and electrodeforces required -_or thicker sheet and the harder alloys, such as

_ A-286, the larger press-type machines are more suitable. Factors

to be considered are the same as for other steels- Joint overlap

must be sufficient tt, contain the weld; weld loc&tions must be

accessible to the equipment to be used; forging pressure will beinadequate to provide proper contact of part of it is used to formthe parts; sufficient spot spacing must be used so that current isnot reduced _t the desired location because of shunting through

previously made welds (ref. 12.4). "Coring" or incipient melting

88

b

XXXXX-'I 01

is a feature that has been observed in spot welding A-286, whichmay resemble small cracks in the plane of the sheet extendingfrom the edge of the weld nugget toward the unaffected base metal.Central cracking has also been observed. It is suggested that in-creases in electrode force and in weld time will reduce the like-lihood of internal cracking (refs. 12.4, )2.12).

Little informatior, is av_.ilable directly on sean_ welding of A-286.However, st_:dies have shown that the most common cause ofporosity and internal cracks is incorrect weld spacing; successiveweld nuggets must not be too close. Cracking can be reduced alsoby slower welding speeds and longer weld and cool times. Continuousseam welding eliminates cracking (refs. 12.4, 12.12).

12. 222 Flash W'eldin_. Flash welding is better adaptable to the high-strengthh'eat'-treat_.ble alloys than arc, spot, or seam welding in two respects:(1) Molten metal is not retained in the joint; thus, cast structuresthat might be preferentially corroded are not present. (2) The hotmetal in the joint is upset; this upsetting operation may improvethe ductility of the heat affected zone. Other advantages includeweight saving because there is no need for overlapping weldir_,flanges, bolting, or riveting. With suitable design, machining costscan be reduced. Machine capacity (especially transformer capacity)for welding A-286 does not differ greatly from that required for othersteels; however, the upset-pressure capacity must be higher.

Flash welding conditions of greatest importance are flashing current, •time and speed, and upset pressure and distance. In general, highflashing speeds and short flashing times are used when it is desir- :iable to minimize weld contamination. Flash welds that have mech-anical properties approaching those of the base metal are regularlyproduced in conventional machines, with joint efficiencies commonlybetter than 95 percent (ref. 12.4).

12. 223 Mechanical Properties of Resistance Welds

• 12.2231 Operating conditions and resnlting shear strengths for spot welds, -*table 12.2231.

12.2232 Effect of shot-peening on fatigue resistance of 4-spot weldedjointsin STA sheet, figure 12.2232.

12.2233 Tensile properties of flash butt-welds at room temperature,' table 12.2233.

12.3 Brazing. Alloy A-286 can be brazed in vacuum or in atmospheres :. of pure dry hydrogen or argon. Mechanical properties of brazed

joints are somewhat impaired because of the brazing time-temper-ature cycle, but may be improved by oolution treating and agingafter brazing Lref. 12.3).

As with any other welding procedure, aurfacee muat be clean andfree of contaminants. Because of the aluminum and titanium content

in A-286, brazing in controlled atmosphereJ ia necemeary to prevent

89

i

×××××- 102

the formation of refractory oxides of these metals on the alloy surface.Formation of the oxides ma} also be circumvented by copper or nickelplating of the alloy surface prior to brazing (ref. 12.4).

12.31 Comparison of the stress ..rupture life at lZ00 °F (649 °C) of A-286base alloy and nickel-plated alloy with that of brazed welds is shownm figure 1Z. 31.

12.32 Tensile properties of butt-brazed welds at room and elevated temp-eratures are plotted in figure 12.32.

1Z. 33 It has "-; 'n shown that the tensile strengths of braze-coated A-286,tested _ I239°F (649°C), are reduced more than 25 percent when

a braze cont-_h_ing boron (e.g., AMS 4775) is used (ref. 12.14).

(See also figure 12.32. ) Additionally_ ductility, as measured by

elongation, may be reduced to zero. Consequently, brazing oper-ations for the production of cooled turbine blades were examined

carefully (ref. 17-.18). It was found that even in an atmosphere ofhydrogen with a dewpoint of -ll0°F (-79°C) and at temperatures to

23000 F (I260 °C), deleterious oxide formation could not be prevente(..

Hence, electroplating of the base metal was used to promote weLLing

of the base metal by the braze alloys. A minimum thickness of0. 000Z inch (0.00508 turn) nickel plate was found to be satisfactory

for successful brazing. The effect of nickel plate thickness on the

stress-rupture life of A-286 brazed welds tested at I200°F (649°C)

is indicated in figure 12.33. It was also observed that a brazing "-

alloy of Ni-Cr-Si was less harmful to the stress-rupture life ofA-286 than one of NI-Cr-Si-B.

12.4 Fastening. Successful fastening of the high-strength heat-resistingA-286 requires, of course, fasteners of at least equivalent prop-

erties, generally A-286 itself. The excellent tensile and stress :iproperties of A-286 wire and bolts have been illustrated in Chapters _7 and 8. The tensile properties of A-286 rivets are generously re-corded in MIL-HDBK-5A (ref. 12.16) for use with other high-strengthcorrosion-resistant alloys. _

%

_ 12.41 The shear strength of A-286 rivets compared with those of high- _strength aluminum and nickel alloys is illustrated in figure 12.41. _

12.42 The tensile strengths of A-286 rivets in A-286 sheet are summar-ized in table 12.42.

90

XXXXX-'103

91

XXXXX- 104

9Z

XXXXX-'105

. _..,,rlb

93

XXXXX- 106

94

\

+

.+.

XXXXX- 107

95

XXXXX- 108

70_ _mp__-y+_

44.._ 60 --,- t

t..ll - 40

50 ++........... |

._ _z.............. ' 30 -..

® i .7 ',?,_:::z::aB I ,O -r'_. ..........

0 30

zo ---.. +Z ........ 10

104 10 e ,0 eCycles to Failure

FIGURE 12.2232. --Effect of shot-peening on fatigue resistanceof a 4-suot weld lap joint; 0.05-in (1.Z7-mm) sheet; 1800°F

(98Z°C), 10rain, OO+ 1325°F (718°C), 16hrs. (Ref. IZ,l)

80 ! llII

_ed t .--"III ;_- .... i i,-

_ ,_lI 1 I ; I FI -

@ _=_='b -'--: llmlIll h.--_mInInllll Ii_mlnill I ;M '.'ramli_':_qlIlll nlll-_'lll _-

40 mnnmmnunn

mmmmmunun mmmnmnnnu nmmmmmnnn/mmmmmnnun _ _-0nmmml|l!l mmmnuunll mmnmmuull munmnunnl m

+ IIIIlSqlIIIIIllU ImmImlmmlInIIIlIIlInnniillil IiimniIIl nininnill InInIIlll I :_

, R 0 IIIIIIlll lllllllll nnllnllll inlllnlll i ._7

O. 1 1 10 100 1000Rupture Life, hours _-_

FIGURE 12.31. -- Comparison of stress-rupture life of A-_86 _lealloy and nickel-plated alloy with that of brazed welds.

;-*, (Ref. 12.13 )

_ ,6

XXXXX- 109

0 ZOO 400 600 800 LO00 °CI00 - 70

' iI

6O

80

XXXXX-'I "1"1

_._¥

1.59 3.18 4.76 6.35 7.94 9.5 rnna

l zooo __ '_ ii , i ,1 I t_ 1 _

10 000 --r Alloy,, ksi ,{kg/mm __ i ,..... J ! ! --i---_ 1_-

: Monel 49 134.5} I .I--L---f---K-L--4/-_--L_ 4000

--TZOZ4-T31 41 {Z8 8} t ' I ---- /; It 1/--I_

n i_ - 3000 _,

m _

ZOO0

4 000 - ! [ 1 /

--V-- i/ f

.... ;or ;c zoz -T 1

/" ./"At" _ 1 - lOOO .zooo -'_-_ /

F_ .... li o0 I J

1116 2116 3116 4/16 5116 6116 in" Rivet Di ,meter

FIGURE 12,41. --Comparison of shear strengths of rivets.

• v._ef. 12.16)

99

XXXXX-112

Chapter 12 - B.eferences

12.1 R. Kaltenhauser, 'rWeldability of Precipitation-Hardening StainlessSteels," Metals En_. Qtr., 9 (1), 44 (1969).

lZ. 2 Republic Steel Corporation, "Arc Welding Stainless Steel. Part I,Basics of Arc Welding," Adv. 1948a-15M-370A.

12.3 Universal Cyclops/Specialty Steel Division, "Unitemp A-286," HT3020, 1971.

12.4 5.5. Vagi, R.M. Evans, and D.C. Martin, "Welding of PrecipitationHardening Stainless Steels," NASA SP-5087, 1968.

l Z.5 5.J. Vagi, R.P. Meister, and M.D. Randall, "Weldment EvaluationMethods," DMIC Report 244, August 1968.

12.6 International Nickel Co./Huntington Alloys Division, "Joining theHuntington Alloys," Technical Bulletin T-2.

12.7 Weldin_ Handbook, Sec. 5, American Welding Society, New York,1967, Ch. 91.

12.8 ASTM STP-226, "The Elevated Temperature Properties of Weld-Deposited Metal and Weldments," 1958, _. 195.

l Z. 9 I.F. Squires, "Determination of Kesistance Spot. Welding Character-

istics for Some Heat-Resisting Stainless Steels," British Welding J., _

2 (3), 149(196z).12.10 Marshall Space Flight Center, "Effects of Low Temperatures on _

Structural Metals," NASA SP-5012, December 1964. _,

12.11 C.P. Smith and D.H. Love, "Development of Elevated Temperature :_"Sheet Spot-Welded and Seam-Welded Joints," ASD TR 61-67. :_

12.12 P.M. Knowlson, "An Explanation of Factors Affecting the Fornlationof Internal Cracks .n Spot Welds in Nimonic Alloys and Some Stainlel3 s

Steels," British Welding J., 9 (3), 168 (1962).

12.13 Metals Handbook_ 8th Ed., Vol. I, "Selection and Properties of Methyls," )_American Society for Metals, Metals Park, Ohio, 1961.

/,

_ 12.14 W.E. Russell and J.P. Wisner, "An Investigation of High-Temper- _

i_i ature Vacuum and Hydrogen Furnace Brazing," NASA TN-3932, 1957.

12.15 J.H. Sinclair and C.A. Gyorgak, "Effect of Two Braze Coatings,Processing Varlablee, and Heat Treatments on 1200°F Stress-RuptureStrength of L-605, A-286, and Inconel 700 Sheet," NASA TN D-1880,November 196_.

1_.16 Military" Handbook 5-A, Dept. of Defense, FSC I500,"Metallic Materials

i and Elements for Aerospace Vehicle S_ructurel," February 1966;latest change order; January I Q70.

100

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