. . . . - . . , I - , . , . . ,.

*I

. . . NASA TECHNICAL

M E M O R A N D U M

eo r;

. . NASA TM X-53178

DECEMBER 11, 1964

LOW TEMPERATURE MECHANICAL PROPERTIES OF 8AI-IMo-IV TITANIUM ALLOYS AND COMPOSITE WELDMENTS by C. R. DENABURG

Propulsion and Vehicle Engineering Laboratory

NASA

George C. Mdrshull S’uce Flight Center, Hantsville, Alubdmd

TECHNICAL MEMORANDUM X- 53178

LOW TEMPERATURE MECHANICAL PROPERTIES OF 8A1-1M0 - l V TITANIUM ALLOYS AND COMPOSITE WELDMENTS

C. R. Denaburg

George C. Marshall Space F l i g h t Center

Huntsv i l le , Alabama

ABSTRACT

The mechanical p r o p e r t i e s of annealed 8A1-1Mo-1V t i t an ium a l l o y s h e e t , 0.063-inch t h i c k , were determined a t temperatures from ambient t o -253°C (-423°F). The a l l o y had h igh s t r e n g t h through the e n t i r e test temperature range. The t e n s i l e s t r e n g t h a t -253°C (-423°F) was approximately 75 percent g r e a t e r than the ambient temperature t e n s i l e s t r e n g t h . The e longat ion decreased from approximately 16 pe rcen t a t ambient temperature t o approximately 8 pe rcen t a t -196°C (-320°F) and t o less than 3 percent a t -253OC (-423°F).

Weldments of 8A1-1Mo-1V t i tan ium t o 6Al-4V t i tan ium were made by u t i l i z i n g t h e TIG process with 6A1-4V t i tan ium a l l o y f i l l e r . weldments were made wi th the e l e c t r o n beam process without f i l l e r wire. Based upon t y p i c a l s t r e n g t h values of 6Al-4V t i t an ium a l l o y , t h e as- welded j o i n t e f f i c i e n c i e s of both types of weldments exceeded 95 pe rcen t over the e n t i r e range of t es t temperatures from ambient t o -253°C (-423°F). over t he t es t temperature range except a t room temperature, where s t r e n g t h s were approximately equal.

S imi la r

The TIG weldments r e s u l t e d i n s l i g h t l y h igher s t r e n g t h s

NASA - GEORGE C . MARSHALL SPACE FLIGHT CENTER

TECHNICAL MEMORANDUM X-53178

LOW TEMPERATURE MECHANICAL PROPERTIES OF 8Al-lM0-1V TITANIUM ALLOYS AND COMPOSITE WELDMENTS

C . R . Denaburg

MATERIALS DIVISION PROPULSION AND VEHICLE ENGINEERING LABORATORY

TABLE OF CONTENTS

SUMMARY .................................................... INTRODUCTION ............................................... EQUIPMENT AND SPECIMEN CONFIGURATION ....................... RESULTS AND D I S C U S S I O N ..................................... CONCLUSIONS ................................................ APPENDIX ................................................... ReFERENCES .................................................

Page

1

1

2

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iii

LIST OF ILLUSTRATIONS

F igure

1

2

3

4

5

6

Table

I

I1

I11

T i t l e

Low Temperature Mechanical P r o p e r t i e s of 8A1-1Mo-1V Titanium Alloy Sheet (0.063-inch th ick) ............................................. Low Temperature NotchedhJnnotched Tens i l e S t rength Rat io of 8Al-lMo-lV Titanium Alloy Sheet (0.063-inch t h i c k ) . . . . . . . . . . . . . . . . . . . . . . . . . . . Low Temperature Tens i l e S t r eng ths of 8A1-1Mo-1V Titanium Alloy Sheet Welded t o 6A1-4V Titanium Alloy Sheet (0.063-inch th i ck ) ............ Low Temperature Tens i l e S t r eng th of Titanium Alloy 8Al-lMo-lV TIG Weldments, No F i l l e r .......... St ruc tu re of TIG Weldment .......................... St ruc tu re of E lec t ron Beam Weldment ................

LIST OF TABLES

Composition of Titanium Alloys 8A1-1Mo-1V and 6A1-4V ......................................... Low Temperature Mechanical P r o p e r t i e s of 8A1-1Mo-1V Titanium Alloy .......................... Low Temperature Tens i l e S t r eng th of 8 A1-IMo-1V Titanium t o 6A1-4V Titanium Welded J o i n t s .........

iV

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11

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TECHNICAL MEMORANDUM X-53178

LOW TEMPERATURE MECKANICAL PROPERTIES OF 8A1-1M0 - l V TITANIUM ALLOYS AND COMPOSITE WELDMENTS

SUMMARY

The mechanical p r o p e r t i e s of t i t an ium a l l o y 8Al-lMo-lV s h e e t , 0.063-inch t h i c k , were determined a t temperatures from ambient t o -253°C (-423°F). The u l t ima te t e n s i l e s t r e n g t h increased from 158.1 k s i a t ambient temperature t o 279.1 k s i a t -253°C (-423°F). The notched t o unnotched t e n s i l e s t r eng th r a t i o dropped from 0.90 a t ambient temperature t o 0 .81 a t -129°C (-200°F) and decreased sharp ly t o 0 .51 a t -253OC (-423°F). Composite weldments of t i t an ium a l l o y 8Al-lMo-lV t o t i t an ium a l l o y 6A1-4V were made by us ing bo th t h e TIG and e l e c t r o n beam welding processes . 6A1-4V f i l l e r wire; no f i l l e r wire was used wi th the e l e c t r o n beam welding process . J o i n t e f f i c i e n c i e s produced by the TIG process were g r e a t e r than those produced by the e l e c t r o n beam process . I n both cases, however, the j o i n t e f f i c i e n c i e s were above 95 pe rcen t from ambient temperature t o -253°C (-423OF).

The TIG weldments were made w i t h

INTRODUCTION

Titanium a l l o y 8Al-lMo-lV, having an a lpha r i c h - l e a n b e t a s t r u c t u r e , has good f o r g e a b i l i t y and h e a t t reatment q u a l i t i e s and a l s o high s t r e n g t h and r e s i s t a n c e t o c reep a t ambient and h igh temperatures . This a l l o y was developed o r i g i n a l l y f o r j e t engine compressor p a r t s , i . e . , d i s c s , space r s , and b l ades , where high t e n s i l e p rope r t i e s and r e s i s t a n c e t o c reep were of t he utmost importance (Ref. 1).

This i n v e s t i g a t i o n was prompted by the need f o r a d d i t i o n a l low temperature data t o f u l l y eva lua te the performance of t h i s a l l o y over a wide v a r i e t y of environments f o r p o t e n t i a l use i n advanced space v e h i c l e duc t ing , s t r u c t u r a l members, and tank sk ins . The study was l i m i t e d t o t h e low temperature p r o p e r t i e s of the a l l o y i n s h e e t s of 0.063 inch i n th ickness , furnished by the Titanium Metals Corporat ion of America from Heat No. (210) D-3457. I n a d d i t i o n , s i n c e the p r o p e r t i e s of t h i s a l l o y are r epor t ed ly comparable t o the 6A1-4V t i t a n i u m a t room temperature and supe r io r a t e l eva ted temperatures , weldments of 8Al-lMo-lV t o 6A1-4V were prepared f o r eva lua t ion a t low temperatures . TIG ( tungs ten a r c i n e r t gas) weldments u t i l i z i n g 6A1-4V t i t an ium a l l o y f i l l e r and e l e c t r o n beam weldments wi thout a f i l l e r were eva lua ted . welding and t h e welding schedules used are descr ibed i n the Appendix.

Preparat ion of the s h e e t material before

EQUIPMENT AND SPECIMEN CONFIGURATION

The desc r ip t ions of the t e s t i n g equipment and specimen conf igu ra t ion a re repor ted i n r e fe rence 2.

RESULTS AND DISCUSSION

The compositions of t he two t i t an ium a l l o y s inves t iga t ed a re shown i n Table I. The 0.063-inch t h i c k commercial grade shee t was t e s t e d i n the as - rece ivedy s i n g l e 'annealed condi t ion .

The mechanical p r o p e r t i e s of the 8A1-1Mo-1V a l l o y l i s t e d i n Table I1 show the ambient temperature t e n s i l e and y i e l d s t r e n g t h s i n the long i tud ina l d i r e c t i o n t o be 158.1 k s i and 150.0 k s i , r e s p e c t i v e l y , and 279.1 k s i and 258.9 k s i , r e s p e c t i v e l y , a t -253OC (-423%'), which is an inc rease of approximately 75 percent . A comparison of the p r o p e r t i e s i n both the long i tud ina l and t r ansve r se d i r e c t i o n s i s shown i n FIG 1. The percent e longat ion drops gradual ly from 14 pe rcen t a t ambient temper- a t u r e t o 8 .3 percent a t -196OC (-320°F) and decreases sharp ly t o 2 . 7 pe rcen t a t -253°C (-423°F) i n the l o n g i t u d i n a l d i r e c t i o n . The notched t o unnotched t e n s i l e r a t i o s i n d i c a t e a decrease i n toughness wi th a decrease i n temperature (FIG 2 ) . Notch s e n s i t i v i t y i n the long i tud ina l d i r e c t i o n i s n o t q u i t e as severe as t h a t i n the t r ansve r se d i r e c t i o n . However, t he notch s e n s i t i v i t y i n the two d i r e c t i o n s e x h i b i t s a sharp inc rease a t temperatures below -129°C (-200°F).

The 8A1-1Mo-1V shee t , 0.063-inch t h i c k , was TIG welded t o 6A1-4V shee t of the same th ickness us ing 6A1-4V f i l l e r m a t e r i a l . The low temperature t e n s i l e s t r e n g t h s of the composite weldments are shown i n Table 111. The T I G welds, t r ansve r se t o the loading d i r e c t i o n , increased i n t e n s i l e s t r e n g t h from 137.8 k s i a t ambient temperature t o 257.6 k s i a t -253°C (-423°F). (See FIG 3 . ) The average i n c r e a s e i n s t r e n g t h was 29 k s i per 100°F decrease i n temperature w i t h j o i n t e f f i c i e n c i e s i n excess of 95 percent f o r the t e s t ' t e m p e r a t u r e spectrum. The e l e c t r o n beam weldments increased i n t e n s i l e s t r e n g t h from 138.7 k s i a t ambient temperature t o 256.9 k s i a t -253°C (-423°F). J o i n t e f f i - c i e n c i e s of the e l e c t r o n beam weldments were 95 pe rcen t o r above f o r a l l t es t temperatures. Only th ree specimens of t he t o t a l number of weldments t e s t ed f a i l e d i n the fus ion zone; the remainder f a i l e d i n the 6A1-4V a l l o y base m a t e r i a l . Low temperature t e n s i l e s t r e n g t h s of the 8A1-1Mo-1V TIG weldments w i th no f i l l e r added a r e shown i n FIG 4 (Ref. 3) . The s t r e n g t h va lues of composite weldments a r e lower than those from TIG weldments of 8Al-lMo-lV, as would be expected cons ider ing the lower s t r eng th of the 6A1-4V a l l o y .

2

'd'

Macrostructures and micros t ruc tures of bo th types of weldments are shown i n FIG 5 and 6. The h e a t a f f e c t e d zones common t o t h e TIG weld- ments are shown a t lOOX magnif icat ion i n FIG 5. The two upper micro- s t r u c t u r e s i n FIG 6 show the a lpha r i ch - l ean be ta 8Al-lMo-lV t i t an ium and t h e a lpha be ta 6A1-4V t i t an ium a l l o y shee t materials. The lower mic ros t ruc tu re of t he e l e c t r o n beamweld j o i n t shows t h e same type of t r a n s i t i o n from the h e a t a f f e c t e d zone t o the fus ion zone as i l l u s t r a t e d i n FIG 5; however, t r a n s i t i o n from the base metal through t h e h e a t a f f e c t e d zones t o the fus ion zone occurs i n a much narrower area. P repa ra t ion of the macrostructure and mic ros t ruc tu res shown i n FIG 5 and 6 i s descr ibed i n re ference 4.

CONCLUSIONS

It was determined t h a t t i t an ium a l l o y 8Al-lMo-lV has good mechanical p r o p e r t i e s i n the temperature range of 27°C (80'F) through -129°C (-200'F). The composite TIG weldments u t i l i z i n g 6A1-4V f i l l e r metal and the e l e c t r o n beam weldments r e s u l t e d i n weld e f f i c i e n c i e s g r e a t e r than 95 percen t over t he t e s t temperature range from ambient t o -253°C (-423°F). As determined from the eva lua t ion of t he one h e a t of 8Al-lMo-lV t i t an ium a l l o y , t h i s a l l o y i s no t recommended f o r dynamic load a p p l i c a t i o n s a t l i q u i d n i t rogen and l i q u i d hydrogen temperatures because of t h e low d u c t i l i t y and increased notched s e n s i t i v i t y as measured by pe rcen t e longa t ion and notched t o unnotched t e n s i l e r a t i o , r e s p e c t i v e l y .

3

APPENDIX

PREPARATION OF TITANIUM ALLOYS 8A1-1M0 - l V AND 6A1-4V SHEET PRIOR TO WELDING

Degrease by wiping wi th so lven t (a lcohol) Soak i n a l k a l i n e c l eane r f o r 5 minutes (180°F) Immerse i n a water s o l u t i o n of 5 percent "03 and 0.5

Rinse and dry by wiping wi th l i n t - f r e e c l o t h o r t i s s u e percent HF f o r 20 minutes

WELDING SCHEDULE FOR TIG WELDMENTS

Backing p l a t e - S t a i n l e s s s tee l F i l l e r - 1/16-inch diameter 6A1-4V t i tan ium a l l o y Electrode - 3/32-inch diameter t h o r i a t e d tungsten No. 8 metal cup Copper hold down b a r s Volts - 8 Amps - 170 F i l l e r wi re speed - 30 inches/minute Carr iage speed - 18 inches/minute Argon cover flow r a t e - 30 c f h Helium flow r a t e on t r a i l i n g s h i e l d - 6 c f h Helium flow r a t e on backing p l a t e - 50 c fh

WELDING SCHEDULE FOR ELECTRON BEAM WELDMENTS

Machine - Hamilton Zeiss W1-2 E lec t ron Beam Welder

Welding Pass

Beam diameter - 0.005 inch t o 0.008 inch Ki lovo l t s - 110 Milliamps - 3.25 Travel speed - 30 inches/minute Beam d e f l e c t i o n ( t r ansve r se t o weld seam) -

0.020 inch , each s i d e

Wash Pass

Beam diameter (defocused) - 0.040 inch t o 0.050 inch Travel speed - 30 inches/minute

4

280

2 60

240

220

.- v) Y

vi E 200 - v,

180

160

140

120

Temperature, deg Fahr

-400 -300 -200 -100 0 +IO0 I I I I I I I I I I I I

f

,-:I Long i t ud in a I

.. ...... 0 ....... Transverse

I I I I I I I I I I I I -240 -184 -129 -73 - 17.8 t37.8

Temperature, deg Centigrade

v)

20.0 r" V c -

15.0 o N

c .- 10.0 +

2 5.0 2

0 'L

c 0)

c 0

(D w t 0 w -

FIGURE 1 LOW TEMPERATURE MECHANICAL PROPERTIES OF 8AL-1MO-1V

TITANIUM ALLOY SHEET (0.063-INCH THICK)

L 5 m LL

M a, U - z 3

m a, Q

a, I-

c,

L

E

O 0

+ 4

0

0 0 4

I

0 0 cv I

0 0 m I

0 0 e

I

I

- m c -a 3

M c 0 -.I

.-

c, .-

e 0

I I

Y

4

c

Y,

a, > Y, c m I-

L

L

. . . . . .

.

00 r\ m +

00 r\ 4

I

M r\

1

m cv M

I

e 00 4

I

0 e cv I

a, U m M

c a, 0

M a, -0

L

.- c,

- ? 3

m a, Q

a, t-

u

L

€

I I- c3 z W E I- cn W J

v, Z W I-

W I 0 I- O Z Z 3 \

W I 0 I- O Z W E 3 I- Q CT W L1

W I-

0

-

n

n

2

3 1

cv W CT 3 c3 - LL

Temperature, deg Fahr

I -400 -300 -200 -100 0 + l o o

I I I I I I I I I I I I 260

240

220

200

180

160

140

- I

- I

- I

- I

- - - D

-

260

240

220

200

180

160

140

120

-400 -300 -200 -100 0 + l o o I I I I I I I I I I I I

- - TIG, 6AL-4V Fi l ler

I ........o....,.. Electron Beam

- I

- I

- I

- -

- D

- I

I I I I I I I I I I I I -240 -184 -129 -73 -17.8 +37.8

FIGURE 3 LOW TEMPERATURE TENSILE STRENGTHS O F 8AL-1MO-1V TITANIUM

ALLOY SHEET WELDED T O 6AL-4V TITANIUM ALLOY SHEET

(0.063 INCH THICK)

r

7

120 I I I I I I I I I I I I I -240 -184 -129 -73 -17.8 +37.8

8

Temperature, deg Fahr I

-400 -300 -200 -100 0 t 1 0 0 280

2 60

240

220 .- m Y

m m 2 c

200 v,

180

3 60

140

-240 -184 -129 -73 -17.8 t 3 7 . 8

Temperature, deg Centigrade

Figure 4 LOW TEMPERATURE TENSILE STRENGTH OF TITANIUM ALLOY

8AL-1MO-1V TIG WELDMENTS, NO FILLER

Extracted From Reference 3

TIG Weldment Mag. 1OX

8 A I - 1 M o - 1 V T i Heat Affected Zone 6AL-4V T i Heat Affected Zone

Mag. loox

FIGURE 5 STRUCTURE OF TIG WELDMENT

9

Electron Beam Weldment \ Mag. 1OX

/ \

8AI-1Mo-1V Ti Heat Affected Zone 6AI-4V T i Heat Affected Zone

Mag. 100X.

FIGURE 6 STRUCTURE OF ELECTRON BEAM WELDMENT

10

J

TABLE I ,

COMPOSITION OF TITANIUM ALLOYS 8Al-lMo-lV AND 6A1-4V

T i Alloy C - Fe - A 1 - V - I v b H2 02 N2

8-1-11 0.025 0 .08 7 .9 1.0 1 .o 0.004 0.0902 0.010

0.020 0.13 6 . 1 4 . 0 0.006 0 . 0872 0.019 - 1 6 -4

Note 1 - Vendor's Analys is Note 2 - MSFC Analys is

TABLE I1

LOW TEMPERATURE MECHANICAL PROPERTIES OF 8Al- lM0-1V TITANIUM ALLOY

E l . Notched Notched/ U 1 t imate Y.S. 2-Inch Tens i l e Unnotched

Temperature Di rec t ion T.S . 0.2% O f f s e t Gage S t r eng th T e n s i l e O C ks i k s i % k s i ( K t = l O ) Ra t io

+2 7 Long i tud ina 1 158.1 150.0 14.0 141.6 0.90 Transverse 159.2 149.7 16.2 140.4 0 .88

-73 Longi tudinal 188.4 176.8 10.0 141.0 0.79 Tr an sver s e 185.6 1 7 7 . 1 10.5 146.4 0.79

-129 Long i tud ina 1 196.4 194.4 8.0 160.4 0 .81 Transverse 199.0 193.8 9.2 156.7 0.79

-1 96 Longi tud ina 1 243.1 229.3 8 .3 159.9 0.66 Transverse 243.6 226.2 10 .3 137.3 0.56

-253 Longitudinal 279.1 258.9 2 . 7 142.4 0 .51 Transverse 266.4 256.8 1 . 7 136.4 0 .51

Note - Each s t r e n g t h va lue i s an average of t h r e e o r more specimens.

11

TABLE 111 I

LOW TEMPERATURE TENSILE STRENGTH OF TO 6A1-4V TITANIUM WELDED

Temp e r a t u r e O C

+2 7

-73

-129

-196

-253

TIG Weldments” U1 t i m a t e

T.S. k s i

137. a

168.4

187.1

223.4

8A1- 1Mo - 1V TITANIUM JOINTS

E l e c t r o n Beam U1 timate

T.S. k s i

138.7

164.8

181.0

207.6

257.6 256.9

7k 6A1-4V Titanium F i l l e r

Note - Each s t r e n g t h v a l u e i s a n average of t h r e e o r more specimens.

12

REFERENCES

1. Titanium Metals Corporation of America, P r o p e r t i e s of Ti-8Al-lMo-lV.

2 . Miller , P. C., "Low Temperature Mechanical P r o p e r t i e s of Severa l Aluminum Al loys and Thei r Weldments , I 1 MTP-S&M-M-64-16 , October 1961.

3. Schwartzberg, F. R . , Osgood, S. H . , and Keys, R . D . , Cryogenic Material Data Handbook, F.4.6-3, Prepared under Cont rac t N o . 0 3 3 (657-916) by the Martin Company , Denver , Colorado.

4 . Titanium Meta l lu rg ica l Laboratory, Battelle Memorial I n s t i t u t e , "Metallography of Titanium Alloys," "MI, Report No. 103, May 29, 1956.

13

December 11, 1964 APPROVAL TM X-53178

LOW TEMPERATURE MECHANICAL PROPERTIES OF 8Al- lM0-1V TITANIUM ALLOYS AND COMPOSITE WELDMENTS

The information i n t h i s r e p o r t has been reviewed f o r s e c u r i t y c l a s s i f i c a t i o n . Defense o r Atomic Energy Commission programs has been made by the MSFC Secur i ty C l a s s i f i c a t i o n Of f i ce r . has been determined t o be u n c l a s s i f i e d .

Review of any information concerning Department of

This r e p o r t , i n i t s e n t i r e t y ,

This document has a l s o been reviewed and approved f o r t echn ica l accuracy.

C . E . Cataldo Chief , Metallic Materials Branch

ad? W . R . Lucas L Chief , Materials Div is ion

i d ' . ' Acting Di rec to r , Propuls ion and Vehicle Engineer ing Laboratory

14

-

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Mr. C l ine M r . Kuers M r . Kroll Mr. S t e r r e t t Mr. Blumrich M r . Loy M r . Crawford M r . Verb le M r . Wuencher M r . O r r D r . Lucas ( 5 ) M r . Ca ta ldo (15) M r . Shannon M r . Kingsbury M r . R ieh l Mr. Remer Mr . War den Mr. Akens M r . Wiggins Miss Robertson (8) M r . Hofues

S c i e n t i f i c and Technical Informat ion F a c i l i t y (25) At tn : NASA Represen ta t ive (S-AK/RKT) P. 0. Box 5700 Bethesda, Maryland 20014

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