AFML-TR-68-251

- .1

-- •SOME PROPERTIES OF IRON, COPPER, AND

SELECTED ALUMINUM ALLOYS INCLUDING

CZTRUE STRESS-TRUE STRAIN AT REDUCED TEMPERATURES

Q,q

James M. Carson, l/Lt., USAF

Air Force Materials Laboiratury

John M. Hawn

University of Dayton

TECHNICAL REPORT AFML-TR.60¶-251

September 1968

This document has been approved for 1'ublic release

and sale; its distribution is uqlimite?.

Air Force Materials Laboratory

Air Force Systems Command '3

Wright-Patterson Air Force Base, Ohio

NOTICES

When Government drawings, specifications, or other data are

used for any purpose other than in connection with a definitely related

Government procurement operation, the United States Government

thereby incurs no responsibility nor any obligation whatsoever; and the

fact that the Government may have formulated, furnished, or in any

way supplied the said drawings, specifications, or other data, is not to

be regarded by implication or otherwise as in any manner licensing the

holder or any other person or coporation, or conveying any rights or

permission to manufacture, use, or sell any patented invention that may

in any way be related thereto.

V

-I

AT I L. 9 1 ,'M AL1

This document has been approved for public releaseand sale; its distribution is unlimited.

Copies of this report should not be returned unless return is

required by security considerations, contractual obligations, or, noticeon a specific document.

AFML-TR-68-251

SOME PROPERTIES OF IRON, COPPER, AND SELECTED

ALUMINUM ALLOYS INCLUDING TRUE STRESS-TRUE STRAIN

AT REDUCED TEMPERATURES

James M. Carson, l/Lt, USAFAir Force Materials Laboratory

John M. HawnUniversity of Dayton

This document has been approved for public releaseand sale; its distribution is unlimited.

____ i____ ____ __- -'. --- .-- ~-- --.. --.

- -k

FOREWORD

Some of the individual tasks covered in this report were carriedout by AFML personnel while the remainder was pursued by theUniversity of Dayton Research Institute, Dayton, Ohio, initiated underAir Force Contract F33615-67-C-1087, and completed underF33615-68-C-1l38, Project 7360, "Chemistry and Physics of Materials",Task 736006, "Hypervelocity Impact Studies". The work was administeredby the Air Force Materials Laboratory, Air Force Systems Command,Wright-Patterson AFB, Ohio with Mr. Alhn K. Hopkins (MAYH) asProject Engineer.

The authors gratefully acknowledge the assistance of Mr. H. F.Swift for his helpful discussion, Mr. P. Graf for his aid in having theoscillographic test records read, and Mr. K. Story for his timelyproduction of liquid helium.

This report was submitted by the authors in August 1968. TheUniversity of Dayton report number is UDRI-TR-68-38.

This technical report has been reviewed and is approved.

HERBERT M. ROSENBERGChief, Exploratory Studies BranchMaterials Physics DivisionAir Force Materials Laboratory

Hi

ABSTRACT

The metallurgical and mechanical properties of several facecentered cubic materials (1100 Al, 7075-0 Al, 7075-T6 Al, OFHC Cu)and a body centered cubic material (Armco iron) were examined.Prior to undergoing tensile testing the materials were insured tohave a nonoriented equiaxed grain structure and underwent chemicalanalysis and hardness tests. The materials were then tensile testedat 296 0 K in the atmosphere, at 77 0 K in a liquid nitrogen bath, and at40K in liquid helium. A continuous record of the axial load and of twoperpendicular specimen profile traces produced a measurement ofspecimen true stress-true strain. Engineering stress-strain,elongation, and reduction in area were also calculated.

IWIU 4

TABLE OF CONTENTS

Page

I. INTRODUCTION ........................................ 1

II. BACKGROUND ........... ............................

I III. TEST MATERIALS ........... ..................... . ...

Ii 100- 0 Aluminum .............. .................. Z

7075-0 Aluminum ............... .................. 2

7075-T6 Aluminum ............... ................. 3

OFHC Copper ................ .................... 3

Armco Iron ................ ..................... 3

IV. MECHANICAL PROPERTIES ............. ................ 6

Results ............. ....................... ... 10

Tensile Strength ...... .................... 11

Percent Elongation ......... ................. . .. 11

Percent Area Reduction ........... ............... 11

True Fracture Stress ......... ................ .. 17

Energy Per Unit Volume to Fracture ... ......... ... 17

REFERENCES ................ ......................... ... 18

APPENDIX I ................. ......................... ... 19

APPENDIX I. .................... ......................... 20

I v

Preceding Page Blank

LIST OF ILLUSTRATIONS

FigureNo Page

I Threaded True Stress-True Strain Tensile Specimen . . 7

z Tensile Properties of 1100-0 Al. . . . . . 12

3 Tensile Properties of 7075-0 Al. . . . . . . . . . . . 13

4 Tensile Properties of 7075-T6 Al . . . . . . . . . . . 14

5 Tensile Properties of OFHC Cu. . . ..... ........... 15

6 Tensile Properties of Armco Iron. . . . . . . . . . . 16

7 Grain Structure of 1100-0 A. . . . . . . . . . . . . 20

8 Grain Structure of 7075-0 Al ........ ............. 20

9 Grain Structure of 707-T6 A ............. . 21

10 Grain Structure of OFHC Cu . . . . . . . . . . . . . 21

11 Grain Structure of Armco Iron .... ............... 22

12 True Stress-Strain 1100-o0 A. . . . . . . . . . . . 24

13 Engineering Stress-Strain 1100-0 Al. . . . . . . . . . 25

14 True Stress-Strain 707S-0 Al. . . . . . . . .. . . 26

15 Engineering Stress-Strain 7075-0 Al. . . . . . . . . . 27

16 Tru Stress-Strain 7075-T6 A . . . . . . . . . . . . 28

17 Engineering Stress-Strain 7075-T6 Al . . . . . . . . . 29

18 True Stress-Strain OFHC Cu. . . . . . . . . . . . . 30

19 Engineering Stress-Strain OFHC Cu ......... 31

vi

' - .. . .. . . . ......W

List of Illustrations (Continued)

FigureNo. Page

20 True Stress-Strain Armco Iron .......... .......... 32

21 Engineering Stress-Strain Armco Iron . . . . . . . . . 33

LIST OF TABLES

TableNo. __e

I Test Materials Metallurgical Data ........... . . 4-5

IU Tensile Test Data Sunmnary ....... ............. 8_-9

vii

~- -- t-

SOME PROPERTIES OF IRON, COPPER, AND SELECTED

ALUMINUM ALLOYS INCLUDING TRUE STRESS-TRUE STRAIN

AT REDUCED TEMPERATURES

I. INTRODUCTION

The investigation of the response of materials to hypervelocityimpact, being conducted by the Air Force Materials Laboratory (AFML)light-gas gun facility, deals with several types of materials impactedunder various conditions. A concurrent program of materials character-ization was initiated for two basic reasons. First, it was necessary tomake certain that the materials under study were homogeneous andpossessed both uniform and well known properties. In those casen wherea material was found to be nonhomogeneous steps were taken to make ituniform. Secondly, since material properties play an important role inimpact effects, such as cratering in a semi-infinite target or holeproduction in a thin plate impact, it was necessary to measure variousmechanical properties before these relationships could be established.

This materials characterization is broken into the followinggeneral categories: chemical analysis, metallurgical analysis, andmechanical properties including hardness and true stress-true straintensile relationships. The tensile tests in this phase of the programwere conducted at three temperatures (296 0 K, 77 0 K, 40 K) and involvedfive materials (1100 Al, 7075-0 Al, 7075-T6 Al, OFHC Cu, Armco iron).All the materials tested were of the same stock as that used in the AFMLhypervelocity impact studies. This report is a listing of the results ofthis materials characterization and should be considered with two previousreports (Reference 1 and 2) which outlined the project and presentedinitial data. In some cases data from these reports is repeated here forcompleteness.

I1. BACKGROUND

The effect of low temperatures upon various materials issurveyed in Reference 3. Briefly, materials with a body centeredcubic structure (Armco iron) may be expected to become brittle atlow temperatures. As the ductility approaches zero fracture naturallyoccurs suddenly and without warning. Materials with a face centered

Preceding Page Blank

_1W

cubic structure (OFHC Cu, 1100 Al, 7075-C Al, 7075-T6 Al) may beexpected to retain their ductility at low temperatures and show anincrease in tensile strength. As a material is alloyed however, these,&sic trends may be modified to account for the influence of theailoying additions.

III. TEST MATERIALS

The materials selected for this particular study were subjectedto the following ieries of operations to determine their chemical andstructural properties:

1 Heat treatment (manufacturers).

2. Metallographi. examination (to insure nonorientede .ýiiaxed grain structure).

3. Upset forging and further heat treatment (if oriented grainstructure was initially present).

4. Additional metallographic examination (to check results of

upset forging and for grain size determination,.

5. Chemical Lnalysis.

6. Hardness measurements.

1100-0 Aluminum

The material war taken from a die cast ingot with originaldimensions of 16-1/2 inch diameter x 24 inch length. The ingot was inan as cast condition and metallographic examination revealed anonoriented equiaxed grain structure.

7075-0 Aluminum

The materi,4 was taken from die cast ingots with originaldimensions of 3-1/2 inch diameter x 24 inch length. The ingots wereannealed in air for two hours at 775°F and air .ooled. Metallographicexamination indicated the grain structure to be nonoriented equiaxed.

2-•.

* -!

4

7075-T6 Aluminum

The material was taken from die cast ingots with originaldimensions of 3-1/2 inch diameter x 24 inch length. The ingots weresolution heat-treated in air for eight hours at 870°F and quenched inwater at 150 0 F. At the conclusion of aging for 26 hours at 250 0 F,metallographic examination showed a nonoriented equiaxed grainstructure.

OFHC Copper

The material which was taken from ingots, formed by anelectrolytic process, with original dimensions of 4 inch diameter x36 inch length, was found to have some grain orientation. The ingotswere cut into sec-tions 6 inches long and each section was upset forgedat 1425°F along its three principle axes to final dimensions of 3-1/4inch x 3-1/4 inch x 7-1/4 inch length and then air cooled, Aftervacuum annealing for 3-1/2 hours at 300OF and furnace cooling,additional metallographic examination revealed the presence of anonoriented equiaxed grain structure as a result of the forgingoperations.

Armco Iron

The material, taken from very highly refined, as cast ingotswith original dimnensicns of 4 inch diameter x 36 inch length, wasfound to have some grain orientation after initial metallographicexamination. The ingots were cut i~no sections of 12 inch length. Eachsection was upset forged along its three principle axes to finaldimensions of 5-1/2 inch diameter x 6-1/2 inch length then air cooled.After normalization the sections were air cooled and shot blasted.Additional metallographic examination revealed that a nonorientedequi.R•ed grain structure had been achieved as a result of the forgingoperations.

Table I (page 4-5) lists for each material:

1. Chemical analysis (parts per million_).

2. Hardness measurements taken over a cross sectional area(Brinell Hardness Number; 500 kg load applied for 30 sec;10 mm dia,. ball).

3. Grain size (ASTM Number).

4. Average grain diameter (mm).

-3-

,.,e4P4..~ * "

#.

aI

n l... .. ..

TABLET

TEST MATERIALS METALLURGICAL DATA

1100-0 Aluminum 7075-0 Aluminum

Chemical Chemical Manufacturing Chemical Manufacturingaslmonto Analysis Analysis Limits (PPM) Analysis Limits (PPM)

(PM) (PPM) (PPM)

Be 30C

WO 10 10 23800 21000-29000AlSi 1900 1100 10000 1600 5000PSCaTi 200 40 300 2000vCr 10 20 2000 1800-4000HD 50 60 500 70 3000Fe 4100 4800 10000 1500 7000CcNiCu 1000 800 2000 16000 12000-20000Zn 200 50 '900 5330I 51000-61000ZrNO

CdSn

PbSiCe _ _ __ _ _

MSE (500 kg load, 23.5-25.5 56.0-59.530 see, 10 am dia.ball)

Grain Size 0 3.5(AM No.)

Avg. grain dia. 0.0500 0.0149

[] 4

7075-T6 Aluminum Armco Iron OFHC Copper

Chemical Manufacturing Chemical Chemical ChemicalSlements Analysis Limits (PPM) Analysis Analysis Analysis

(PPM) (PPM) (PPM) (PPM)

Be 30

C 170 8.50 1 1.3

23300 21000-29000 <10Al <10 < 5Si 1400 5000 140 40 1P 40S 200Ca <10Ti 400 2000 <10

V <10Cr 2000 1800-4000Mn 60 3000 140 400 <1Fe 1500 7000 Mfg. Limits 99.9% <10Co <10Ni 140 1Cu 15700 12000-20000 140 1120 Mfg. Limits

99.995 (UZn 54000 51000-61000 <10Zr <10Mo 140Ag <10Cd <10Sn 10 50 2Sb <10w <1000Pb <10 3Bi <SCe 140

BHN (500 kg load 150.0-159.0 70.0-72.0 48.5-50.530 sec, 10 ma dia.ball)

Grain Size 3.5 2.5 4.5(CAST No.)

Avg. grain dia. 0.0149 0.0211 0.0106(--)

5

Photomicrographs of each material, showing grain structure,are included in Appendix I.

Blanks of each material with original dimensions of approx-imately 1/2 inch x 1/2 inch x 2-1/2 inch length were cut in both thelongitudinal and transverse directions from each ingot. The tensilespectimens were machined in accordance with the dimensioned drawing(Figure 1).

IV. MECHANICAL PROPERTIES

All materials used in this study underwent tensile tests onequipment designed to produce a record of true stress-true strain andoperate at reduced temperatures. The design and capabilities of thisequipment are discuhsed in Reference 4. Briefly, the tests wereconducted at room temperature in the atmosphere, at 77 0 K in a liquidnitrogen bath using one cryostat, and at 40 K in liquid helium using asecond cryostat. The first cryostat is capable of operation at a numberof specific temperatures as low as 77 0 K; the second cryostat iscapable of operation from 40 to 770 K.

A diameter sensing gage which constantly traversed the specimenproduced a continuous record of the specimen profile. This measurecoupled with a continuous record of the axial load allowed the computa-tion of true stress and true strain which is a more meaningful measureof a materials mechanical and metallurgical characteristics than theconventional engineering stress-strain relationship. The engineeringrelationship was also computed on the basis of the load record and thecrosshead motion. All tests were conducted at an initial strain rate of.01 in/in/min. Since the crosshead speed was constant this strainrate decreased as the specimen elongated. Upon the formation of aReck in the specimen (nonuniform plastic deformation) the strain rateincreased drastically.

The true stress of a specimen was found within ±2 to 4%(Reference 4). This figure represents a combination of the errors inmeasuring the load and the specimen diameter and is based upon thestandard deviations of the load and diameter calibrations from leastsquares lines.

The severe necking encountered with the OFHC copper specimensexceeded the range of the diameter gage. At 2960 K and 77 0 K the rangewas approximately . 250 to . 100 Inch. At 40 K, due to a restrictioncaused by the bellows of the tensile dewar, the range limits wereapproximately 0. 250 to 0. 160 inch. Only the copper specimens werelimited by these ranges. Calculations for the copper specimens

"6-

I

PEFT REF.

-- _--_ _--j-.24 NC Z Ti-I•EAPj TYP.'

BLEND IN SMOOTHFACED CURVE

-. 252 DIA.t.O01

Figure 1. Threaded True Stress-True Strain Tensile Specimen

involving the use of the final diameter are based on post fracturemeasurements. The true stress-true strain curves for copper areextrapolated to this post fracture measurement.

The tensile data presented in Table II is a summary obtainedfrom all the tests conducted. All available data, including tests notproducing true stress-strain records, is given to demonstrate theuniformity of the data. The data marked by the asterisk was containedin the preliminary report (Reference 2) and represents tests conductedat the Army Materials Research Agency, Watertown Arsenal by JohnNunes at a similar test speed using material from the same stock.In addition to the specimen orientation with respect to the billet fromwhich it was cut and the test temperature the following information isgiven for the consecutively numbered tests of each material:

1. Percent Elongation was primarily determined by measuringthe total crosshead motion and then correcting thismeasure for the elongation of the specimen grips and pullrods, thus resulting in the deformation of the tensilespecimen. Post fracture measurements of the gage andtotal specimen lengths provided a check of the percentelongation measured by the primary means. In all casesTable H gives the result of the crosshead measure, except

"-7-

0-k

* a * • i o . . • • .N .. N 1 N I N .4 O N - -. -0 O €. N -* -• 0 -• O ID

If a C O a V- N V- C SAN N q .. C" .-* N - -O V N.2 . * O .a.N.-. - *N • . • • • .. * * V N

f

4.

. . . . . . . . .

- I• - o 0 N- in

4 a- S N- e N C On V C SA . C. -

he~ ~ V ~ mS '1C -9- .- 0.0 (• o C0

"0-A- V n N4 on inf C. 49' 0.a Vv @ft @~N NP.

-i- V C9 N t P' A t-C. -.i~A - N 4S V ~ . O V @ 0 0 Ij ~' N N V ff V~ SW 'C C t- t-t a 0. .0

• N N.-N

N1a a, ' N N i a' 4

Mi ~ ~ ~ ' - 0 ýI41 0- N A- NN

Nn N N IN - I- - ý - --

f'1~~~r ai0

O0NM C

where noted, in which case it was not available and the totallength measure is presented. This secondary measure wasfound to be comparable, although often I-Z% higher than, theprimary measure.

2. Percent Area Reduction was computed from both the finalreading of the diameter gage and the post fracture diameter.The computation based on the final diameter gage readingis presented in the Table except for those noted cases wherethe specimen necking exceeded the range of the gage or thediameter gage reading was unavailable or unreliable.

3. Tensile Strength was computed using the maximum load seenby the specimen divided by its original cross sectional areaat the temperature at which the test was conducted.

4. True Fracture Stress is .ne fracture load divided by theminimum cross sectional area at fracture. In those caseswhere the material was very ductile and no distinct fracturewas evident the true fracture stress is the result ofextrapolating the plastic deformation portion of the truestress-true strain curve to the true strain at fracture. Acheck of this extrapolation technique with materials showinga distinct fracture verified its accuracy.

S. True Strain is derived from the measure of the minimumspecimen diameter, and is based on the definition of truef i LdL Listrain, Lz lnrI where an initial increment of

length Lo has been plastically deformed to a length Li.

This further reduces to s x 2 ln-i (where Do is the originalDi

diameter and Di is the instanteous diameter) since volumeis conserved during plastic deformation.

6. Energy to Fracture Per Unit Volume was computed using aplanimeter to measure the area under the true stress-truestrain graph. In some cases the area was to the extrapolatedtrue fracture stress points mentioned earlier.

Results

True stress-strain and engineering stress-strain graphs for eachmaterial are presented in Appendix 11. The graphs starting on page 12(Figures 2-6) depict the changes in tensile strength, percent elongation,percent area reduction, true fracture stress, and energy per unit volume

-10.

I.

i

to fracture as a function of temperature for each material. The pointsin these graphs are averages of the values in Table IU.

They show that although a general trend may exist that thechange is not linear with respect to temperature. Rather, the graphsare non-linear and marked by plateaus and even reversals in direction.Even two similar materials such as 7075-0 and T6 Al do not show thesame trends. Generally, however, a distinction can be made betweenthe two different crystal structures tested.

Tensile Strength

The tensile strengths of the face centered cubic aluminumsincreased in a very similar manner as temperature decreased. Thestrength values maintained the same relation to each other at reducedtemperatures as they do at room temperature. OFHC copper showedan approximately linear increase in tensile strength. The body centeredArmco iron, however, increased in strength to about 77 0 K thenremained essentially constant forming a plateau. This plateau seemedto be the mark of the severe embrittlement of the iron.

Percent Elongation

The softer aluminums (1100-0, 7075-0) behaved similarly asthe temperature drops as they both showed an initial increase inelongation followed by a decrease. The softer 1100-0 Al did not dropbelow its room temperature level as the 7075-0 did, however. Thehard 7075-T6 Al and the Armco iron behaved in a similar way as bothshowed a severe decrease in elongation the iron becoming almosttotally brittle while th- Al maintained a few percent elongation evenat 40 K. The copper was not adversely affected by the decreasedtemperature and showed a general increase in elongation.

Percent Area Reduction

A trend similar to elongation is seen for area reduction in thatthe two softer aluminums and the 7075-T6 and Armco iron behavesimilarly. All four materials show a decrease in percent areareduction; the hard aluminum and irm showing the fastest decrease.The copper again is changed little by decreases in temperatures as thecorresponding decrease in area reduction is only a couple of percent.Although the trend& for elongation and reduction in area are similar,they are two distinct measures and should be considered as such.

-11-

35

23o Xa x3U25X

S40

~3o

170 X

6sO

40

30

70-so

50 X

4 - -

hi

30

.30

0 100 too .300TEMPERA? URE *K

Figure Z. Tensile Properties of 1100-0 Aljb 4Z-

25> 020I •x! 0- X

1I51 .3 0 ---

zzI"I

•= so x70w") 60

40 o

'a."IX

40 OI-

-30

xx10

~25

w

1t0

:70

40

300 100 a*050

TEMPERATURE *K

F iguare 3. Tenoile Propertiem of 7075-0 Al

-13-

*12020

""0 1

10

I50-

102.5

~-100

9T.

95

S 20

'5 xS 10

$ 0

22 15z 190

5 10

90J x

"90To

0 100 200 300TEMPERATURE *K

Figure 4. Tensile Properties of 7075-T6 Al

-14-

> h 220

!:

00140wI-

"": 100 -

S240-

wW,200

x16 X

Ii.w 120

z 900

w xo

go-

-40

130-

70

z

- 80J 60w

0 0 04 60

Fiur 5.0niePoeriso FCC

it -40

20

0 ~ 30 200

TEMPERATURE OKFigure 5. Tensile Properties of OFHC Cu

so

900.°X

"Z 40

to -x

so 1

K ~IL 770-

60o

40

~20

0 K I

40z2 30"

I o X1-w I0

40

I-

0 100 200 300TEMPERATURE OK

Figure 6. Tensile Properties of Armco Iron

-16-

In the elastic region the two measures may be related by Poisson'sratio and during uniform plastic deformation they may be related byrealizing that volume is conserved, however, upon the formation of aneck these simple relationships no longer apply. Reference 5 containsa detailed study of this relationship.

True Fracture Stress

True fracture stress is a combination of the load supported atfracture and of the area reduction. When the extrapolated values areused for the true fracture stress, the voids which form in the area ofa neck prior to fracture and thus reduce the effective area are beingtaken into account. Generally, a net increase in true fracture stresswas seen, however, due to the relative effects of area and load the1100 Al, 7075-0 Al, and OFHC Cu showed continuing increaseswhile the 7075-T6 Al unexpectedly decreased to 77 0 K then increasedgreatly between 77 0 K and 40 K. The Armco iron remained relativelyconstant throughout the temperature range.

Energy Per Unit Volume to Fracture

The energy to fracture is a function of the true stress at fracture,the area reduction, and the slope of the elastic and plastic portions ofthe true stress-true strain relationship. The 1100 Al and 7075-0 Alwere similar as they increased then decreased as the temperature waslowered. However, the decrease in the 1100 started much later thanit did in the 7075-0 Al. The 7075-T6 Al and iron were again similaras both decreased to 77 0 K then remained constant to 40 K. The coppershowed a linear increase to 40 K.

As a result of some of the trends noted above and particularlythe great ductility of some of the materials at low temperatures aproject is underway to determine the mode of failure and explain thisductility. Fractographs which are photographs of a carbon replica ofthe specimen's fracture surface as viewed under an electron microscopehave been made of all the body centered cubic materials tested. Also,additional tensile tests are planned at each tcmperature with a smallgrained 1100 Aluminum.

Further, all of the materials mentioned in this report have beenimpacted in a semi-infinite form (thick block) on the AFML light-gas gunrange at room temperature (297 0 K), in a dry ice-acetone bath (193 0 K),and in a liquid nitrogen bath (77 0 K). Further impacts are planned foreach material in liquid helium (40 K).

-17-

REFERENCES

1. Rolsten, R. F., "Hypervelocity Impact Studies", AFML-TR-66-40,Air Force Materials Laboratory, Wright-Patterson Air ForceBase, Ohio, March 1966.

2. Rolsten, R. F. and Dean, W. A. "Metallurgy of Aluminum Ingots

for Hypervelocity Impact Targets", AFML-TR-66-109, Air ForceMaterials Laboratory, Wright-Patterson Air Force Base, Ohio,April 1966.

3. "Effects of Low Temperature on Structural Metals", NationalAeronautics and Space Administration, Technology UtilizationReport No. NASA-SP-5012, December 1964.

4. Fiscus, I. B. and Carson, J. M., "A Diameter Gage for TrueStress-True Strain Measurements of Tensile Specimens at ReducedTemperatures", AFML-TR-68-27, Air Force Materials Laboratory,Wright-Patterson Air Force Base, Ohio, February 1968.

5. Kula, Eric B. and Parson, Frank R., "Ductility Relationships inTensile Testing", Watertown Arsenal Laboratories, TechnicalReport No. WAL 111/25, October 1967.

-18-

I!

I; __ __ __ ___ __ __ __

APPENDIX I

Each material underwent a rnetalEographic examination toinsure a nonoriented equiaxed grain structure. Material specimensrepresenting the principal axes of the billet were mounted, polishedand etched for examination. Photomicrographs of an etched surface ofeach material appear in this appendix.

-19-

U.,. .

40p,

Figure 7. Grain Structure of 1100-0 Al (100x)

Figure 8. Grain Structure of 7075-0 Al (lO~x)

-20o-

4b4

A. p

:.' . £* : , - * • 1• • . 3,•

Figure 9. Grain Structure of 7075-T6 Al (100x)

Figure 10. Grain Structure of OFHC Cu (lOOx)

-K1

~~.4(

1 '.1.. .•

' e

Figure 11. Grain Structure of Armco Iron ( lOOx)

.Z

I!I ' l I i a . . . •

APPENDIX H

This appendix presents true stress-true strain and engineeringstress-strain graphs for each material at all of the test temperatures.Data points are included on the graphs. The dotted lines show thepoints to which various tests were extrapolated. Serrated yieldingoccurred at 40 K in some of the materials. This is shown on theengineering stress-strain graphs while the true stress-true straingraphs trace the upper load limit of these serrations.

-23-

Kso1100 ALUMINUMTRUE STRESS-STRAIN

~070 7 LIQ. He

S

/

So

50

/1/0 & 4

4

i " • 02

S•4506

1400 7

30

TEMP.

1 -4 .-. ! _

Figure 12. True Stress-Strain I I00-_0 Al

50 -

1100 ALUMINUM

ENQINEERING STRESS- STRAIN

45 LOQ. He

40 *

35-

2 5-

30

I-

20-4

U• U

"p p

.. 03 A.M TE..

F igur 13. Eaihcetig Stross-Strain 1100.0 A.,

S-25-

10 7 LO. He

a 7075-0 ALUMI"TRUE STRESS - STRAIN

70-

I ¢

*40-

g 02

03

304 507

10s

00 .1 .2 .3 .4 .8 .6

TRUE STRAIN (IN/INs

Figure 14. True Stress-Strain 7075-0 Al

-26-

...........

3

so I

7075-0 ALUMINUMENGINEERING STRESS-STRAIN

7C

8 LIQ He

60

50/-

5 L IO. N g

/4

30 2 ROOM TEMP.

20

10 ,

0i ILIII,0 .04 .08 .12 .16 .2 .24

STRAIN (IN/IN)

Figure 15. Engineering Stress-Strain 7075-0 Al

-27-

110

7 0 LIO. He

902ROOM TEMP.

5 4•• LIO. N2

90

7075-T6TRUE STRESS-STRAIN

0203

-0 0 O

0 7

20

~ I110

.I .2 .3

TRUE STRAIN (IN/IN)

Figure 16. True Stress-Strain 7075-T6 Al

-28-

100100 44Y7 LIQ Hl

/ 7075-T6 ALUMINUMENGINEERING STRESS- STRAIN

90 5 4 LIQ. N2

80

2

ROOM TEMP.

70

60

hi50

I-

40

30

20

p I I ,, II0.02 .04 .06 .08 0.1 .12 .14

STRAIN (IN/IN)

Figure 17. Engineering Stress-Strain 7075-T6 Al

-Z9-

' 5 5 5 , 5 " 5 * w U I 5 w

OFHC COPPERTRUE STRESS-STRAIN

8.9 L 1. He/

200 /,oo /

/ /,5

V / , " °/ / 1/ 7* ISO/LIQ. N2

00U/ /I,'

Ad /

01)- /

l ROOM TEMP.

01

02

0 06

X7

0 0 1 - I 1

2 4 6 S 1.0 1.2 1.4 1.6 I. 2.0 2.2 2.4 2.6 24 3.0

TRUE STRAIN (IN/IN)

Figure 18. True Stress-Strain OFHC Cu

-30-

60 *

OFHC COPPERENGINEERING STRESS-STRAIN

55

50

45 -

40 X

Zon 35- L LIQ. He-

30 X 2

25-

x

I

10

_ROOM TEMP

o6 20 .I.2 .3 . 1 1

STRAIN (IN/IN)

Figure 19. Engineering Stress-Strain GFHC Cu

-31-

10 _

ARMO IRONLIOs6LIO H TRUW STRESS-STAIN 5

3/o" 0'

so .01loool ROOM TEMP.

03

so-o

0SO

i i i • I I A I I i i I0 a 4 5 6 ? I S I0O 1.1 1.2 1.3 L4

TRUE ITR (INIWIN

Figure 20. True Stress-Strain Armco Iron

-32-

100

LIQ. N2 ARMCO IRON

LIo . He ENGINEERING STRESS STRAIN90 10

80

70

~60

U)In

w1- 50

40

30

ROOM TEMP

10 "

O 05 .1 .15 .25 .3 3A

STRAIN (IN/IN)

Figure 2 1. Engineering Stress-Strain Armco Iron

-33-

S... . .. . "- I • I I -- . . .

__ _ _ _ _ _ _ _ _ _ _ __ _ _ __r_ _ _ _ _ __ __ _ _ _ _ _ _ _ _

Unclassifiedunity laissiftcetioe

DOCUMNT CONTROL DATA- R&DS5eeuuftp .bOsEI/e ftII.. he* of aftfe.ct aw ig enMd mwoo"" mim•s bm•gd• omAtend. #X a .mwoI mO..vt cIsefSthie)

I. OINWATSWO ACTgVIn'PY(Coope-me aubO.) as RE9PEN'TSECURITY C LAOS.IVCAr0ON

Air Force Materials Laboratory Unclassified

Wright-Patterson AFB, Ohio 45433 lab GOup

3 NIPAT TITLE SOME PROPERTIES OF IRON, COPPER, AND SELECTED

ALUMINUM ALLOYS INCLUDING TRUE STRESS-TRUE STRAIN ATREDUCED TEMPERATURES

. sIcmpv0avUe MOTO (7*9 ao oe mWd maeo,, ds•e)

Technical Report6. avMAUOm8 m - Not amp. 01n01

Carson, Lt. James M. and Hawn, John M.

6 , "Po w GATE N

September 1968 33 5G&. CNTRACT O AT NO~w, we. 0. o@omATOR'o UEPORT NuMOwIK(S)

F33615-68-C- 11381PRMT . UDRI-TR-68- 38

7360* Sb. ,Wton l• m ee,,,eR,,. inb.m ., mp-b..,e

Task No. 736006S V LAFML- TR-O68-251

This document has been approved for public release and sale; itsdistribution is unlimited.

It. wLSUSmArSV "0T10 It. SPSeSoee, 1eTLITAR ACTITYAir Force Materials LaboratoryAir Force Systems Command

. Wri'ht-Patterson AFB. Ohio 45433

The mnetallurgical and mechanical properties of several face

entered cubic materials ,100 Al. 7075-0 Al. 7075-T6 Al. OFHC Cu)w a body centered cubic material (Armco iron) were examined. Priorto undergoing tensile testing the materials were insured to have a

nonoriented equiaxed grain structure and underween chemical analysisA hardness tests. The materials were then tensile tested at Z96eC in

the atmosphere, at 770K in a liquid nitrogen bath, and at 44oK in liquidhelium. A continuous record of the axial load and of two perpendicularspecimen profile traces produced a measurement of specimen truestress-true strain. Engineering stress-strain, elongation, andreduction in area were also calculated.

11i D D 473 .... " "' ' .. ....

!If-

Unclasp~i~edSecurity CaSsification___________

14 LINK A LINK S LINK C

POLE WT AOLB WT POLE I WT

Stress

StrainTensile TestsCryogenic Mechanical PropertiesIronCopperAluminum

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