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0C Report No. 8926-170

C-1 Material - Titanium - Commercially Pure, Ti 6Al-4V, Ti 5A1-2* Sn

i Static and Fatigue Strength of Dissimilar Alloy Spotwelds

E. K. Winslow, G.D. Lindeneau, W. E. Wise

18 April 1957

Published and Distributed

underContract AF33 (657)-8926

Post Office Box 1960, San Diego 12, California 296-6611

Material Post Office Box 2071 273-8000 1 Accounting Post Office Box 510

GIIIIIIIIDGENERAL. DYNAMICS I CONVAIMMiOREL PAGE

Report No. 8926-170

Material - Titanium - Commercial],, Pure, Ti 6A1-4v, Ti 5Al-2½ Sn

Static and Fatigue Strength of Dissimilar Alloy Spotwelds

Abstract:

Three spotwelded, lap seam combinations comprised of (1) 0.025" thickTi 6A1-4V and 0.025" thick commercially pure titanium; (2) 0.025" thickTi 5A1-2½ Sn and 0.025" thick commercially pure titanium; and, (3) 0.025"thick Ti 6A1-4V and 0.025" thick Ti 5A1-2-ý Sn titanium were tension-shear,cross-tension and fatigue tested. The average tension - shear strengthsof combinations (1), (2) and (3) were 90W, 955 and 959 pounds per spot,respectively, and the average cross-tension strengths were 302, 236 and275 pounds per spot, respectively. The respective tension-shear cross-tension ratios were 0.33, 0.25, and 0.29. The fatigue strengths for107 cycles life were 53, 86 and 97 pounds per spot, respectively.

Reference: Winslow, E. K., Haney, R. J., Wise, W. E., "Spot-welded Titanium - Alpha and Alpha-Beta Alloy .025"Gage Sheet Combination - Shear, Tension and FatigueProperties," General Dynamics/Convair Report SL56-287, San Diego, California, 18 April 1957.(Reference attached).

0141 Islas IliNVI,/ll

ENGINEERING TEST LAORATORIES

C O N V A I R REPORT 56-827A DIVISION OF G•NERAL OYNAMICS CORPORATION DATE 18 April 1957

SAN DIEGO MODEL 7-102A

TITLE

REPORT NO, 564827SPOTWEDED TITANIM

ALPH AND ALHABETA AUIy.025N GALGE SHE COMBINATION

SHBI. TENSION. AND FATIGUE PROPETIES

CONTRACT NO. AF 33(600)-31174

PREPARED BY___________ GROUP STRUCTURES LABORATORIESE. K. Winslow

"REFERENCE0G.vD. Utndem~u

CHECKED BY 4 f- A 4 L. APPROVED B6V. E. Wies E. F. Strong

WITNESSt Chief, EngineeringNO. OF PAGES 17 Test Laboratories

S. R. Carpenter NO. OF DIAGRAMS 13

! d REVISIONS

NO. DATE SY CHANGE PAGES AFFECTED

M 1

WORM il A.

ANALYSIS C 0 N V A I R PAGE 1PREPARED BY E. K. Winslow amlSIMONaOFesawn" MAIM CoeO.Ua"no REPORT NO. 56-827CHECKED BY W. E. Wise SAN Dim"3 MODEL F-102AREVISED BY DATE 18 April L957

REPORT 3D. 56-827NPOTffL"A TITANIUM

ALPHA AND ALPHA-BETA ALLOY.0250 GAGE SHEET COMBINATION

SHEAR. TENSION. AND FATIGUE PROPERTIES

RZFERENCES:

(a) Convair Specification 0-05003. "Welding - Spot and Seam.Commercially Pure and All Alpha Titanium Alloy."

(b) THL Report No. 31. *Welding of Titanium and Titanium Alloys."Battelle Memorial Institute, Titanium Metallurgical Laboratory.7 Fetbnuary 1956.

(c) Convair Report No. 9748. "Spotwelding of 6AL4V Titanium Alloy".Shear, Tension, and Fatigue Characteristics. 6 October 1955.

To determine and evaluate the tension, shear, and fatigue propertiesof alpha and alpha-beta titanium alloys, spotwelded in the following .025'gage sheet material combinations:

a. Conmercially Pure (alpha) to 6AL4V (alpha-beta).

b. Commercially Pure (alpha) to 5 Al 2j SN (alpha).

c. 5 Al 2j SN (alpha) to 6 A14V (alpha-beta).

COXCLUSIONS,

1. Shear strength and weld nugget quality for each required sheet combinationmet Convair Specification 0-05003.

2. Tension-shear rattio, an indicator of weld ductility, was .25 or abovefor all sheet combinations and comparable to commercially pure and allalpha* titanium.

3. Fatigue strengths (pounds/spot) of 5 AL 2* SN - Commercially Pure and6AL4V - Comnerically Pure lap Joints were 88% and 55%, respectively, thefatigue strength .of 5 AL 2j SN - 6AL4V lap joints at the endurance limit.(Based oan SK - Curve Comparison),

RDCOYtOEDATIONS s

It is recommended that spotwelded .025" - .025" commercially puretitanium lap joints be tested in fatigue for the purpose of comparison withf-tlgae test results reported here.

MrONN 1818-A

AL.Y• C O N V A I R PAGE 2PREPARED MY E. K, Winslow A oWvuoR Ofe GInAL avuANA "OSPHeOlI•o REPORT NO. 56-827CHECKED BY W. *E. Wise SAN Dll MODEL F-102AREVISED mY DATE 18 April 1957

TEST SPECIMENS AND PROCFDUREs

The following titanium sheet materials, .025w gage, were used for testspecimen manufacture.

1. Commercially Pure (alpha) - MST III from Mallary Sharon. Heatnumber HT-25268 (AM34901).

2. 6AL4V (alpha-beta) - titanium alloy sheet from Titanium Metals Corp.Heat number X-.4274.

3. 5 AL 2* SN (alpha) - titanium alloy sheet from Titanium Metals Corp.Heat number 1-4384.

The chemical composition and physical properties of 6AL4V, accordingto the manufactureg, were as follows:

Aluminum 6.07%Vanadium 4.05%Carbon .019%Iron .i18%Nitrogen .oil%Hydrogen .012%Titanium Balance

Tensile yield strength Longitudinal grain 128,330 psiTensile yield strength Transverse grain 130,000 psiUltimate Tensile strength Longitudinal grain 142,900 psiUltimate Tensile strength Transverse grain 147,730 psiElongation Longitudinal grain 7%Elongation Transverse grain 9.0%

The chemical composition and physical properties of MST III (AMS 4901)

and 5 AL 2* SN were not available.

Specimen material was prepared for spotwelding as follows&

1. Vapor degrease2. Alkaline cleaner3. Hot H20 rinse4. Titanium etch5. Cold H20 rinse6. 0skite #34 etch7. Hot H20 rinse8. Vapor degreese

PSM no"

ANALYSI C 0 N V A I R PAGE 3PREPARED BY E., K. Winslow A DmON Of ,oMm mAi.S coRPORAnIO REPORT NO. 56-7CHECKED BY W. E. Wise SA DiemO MODEL F-102AREVISED BY DATE 18 April 1957

Hydrogen analysis of test materials was made in the as received andas etched conditions by Process Control IAboratory, Dept 27, Plant 2.

Shear and tension specimen drawings and specificat-ons are shown inFigure 1 and fatigue specimen drawings are shown in Figure 2.

Specimens were spotwelded to give the following&

1. 60% to 80% penetration.2. Sound nuggets.3. .003 inches or less electrode indentation.4. Free of surface burns and electrode pick up.5. Sheet separation less than .005 inches.

Spotwelding machine settings are shown in Table I.

Tension ani shear specimens were tested in a 12,000 pound Tinius OlsenElectromatic testing machine.

Fatigue specimens were tested in a Sonntag SF-lU fatigue machine atload levels (pounds/spot) and load ratios shown in Tables III, IV, and V.The fatigue test set-up is shown in Figure 3.

RFSULS-01 DISCUSSION

The results of tension and shear tests are given in Table II togetherwith tension-shear ratio values.

Fatigue test results are shown in Tables III, IV and V. S-N curvesof the three specimen types tested are shown in Figures 4, 5, and 6.

The results of the hydrogen analysis of specimen material was as

follows:

Material Hy n Condition

MST III .0063 As receivedMST III .oo61 As etched

5A1 a SN .0081 As received5A12 SN .0089 As etched

6 AL 4V .0091 As received6 AL 4V .0085 As etched

POWa ION*.A

ANALSM C 0 N V A I R PAGE

PREPARED EY E.* K. Winslow A MVUUo OFe m, &"Amu Ce"o" REPORT NO. 56-W7

CHECKED BY W. E. Wise GAN DIý MODEL F-102A

REVISED mY DATE 18 April 1957

The shear loads and weld nuggot quality of test specimens in allcases mot Convair Specification 0-05003. This specification requires aainizaa allowable single spot shear strength of 595 pounds and lowestaverage single spot shear of 745 pounds.

The tension-shear ratio, an indicator of weld ductility, was .25or better for all specimen types based on average values. Reference (b)indicates tension-shear ratios of .25 to .40 to be satisfactory for com-mercially pure titanium in most service applications. Reference (c)indicates tension-shear ratios of .25 or better to be satisfactory forcommercially pure and all alpha titanium alloys.

Figure 7 shows comparative S-N curves of specimen groups.

The fatigue strength (pounds/spot) of 6*L4V - commercially pureand 5 Al 21 SN - comercially pure lap Joints were 55% and 88%, respectively,the fatigue strength (pounds/spot) of 5 Al 2* SN - 6AL4V lap joints atthe endurance limit.

Fatigue failures of all specimen groups tested were of typesfound in previous tests. Description of these failures are given in theremarks section of Tables III, IV and V. Photographs, representative ofspot-weld failure usually encountered in fatigue work, may be found inReference (c) Figure 8. This figure is shown in Figure 8 for convenientreference.

NOTE:

The data from which this report vas prepared are recorded inEngineering Test laboratories Data Book Nos. 874, page 2 , and 4025page 5.

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