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NASA TM -86539 

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A TORQUE, TENSION, AND STRESS CORROSION €40 

EVALUATION OF HIGH STRENGTH A286 BOLTS 

By J. W. Montan0 

Materials and Processes Laboratory 

Science and Engineering Directorate 

February 1986 

National Aeronautics and 

Space,Admintstration 

George C. Marshall Space Flight Center 

MSFC ~ Form 3190 (Rev. May 1983) 

J t 
TECHNICAL REPORT STANDARD TITLE PAGE 

i. REFORT NO. ii. GOVERNMZNT ACCESSION NO. 13. RECIPIENT'S CATALOG NO. 

NASA TM-86539 I 

4. TITLE AND SUBTITLE 

A Torque, Tension, and Stress Corrosion Evaluation 

of High Strength A286 Bolts 

7. AUTHOR(S) 

J. W. Montan0 

9. PERFORMING ORGANIZATION NAME AND ADDRESS 

George C. Marshall Space Flight Center 

Marshall Space Flight Center, Alabama 35812 

12. SPONSORING AGENCY NAME AND ADDRESS 

National Aeronautics and Space Administration 

Washington, D .C . 20546 

15. SUPPLEMENTARY NOTES 

_. 

5. REPORT DATE 

February 1986 

6. PERFORMING ORGANIZATION CODE 

8. PERFORMING ORGANIZATION REP OR^ # 

10. WORK UNIT NO. 

11. CONTRACT OR GRANT NO. 

13. TYPE OF REPOR; & PERIOD COVERED 

Technical Memorandum 

1.1. SPONSORING AGENCY CODE 

Prepared by Materials and Processes Laboratory, Science and Engineering Directorate. 

16. ABSTRACT 

17. KEY WORDS 

Torque 

Torque Induced Load 

Stress Corrosion 

This report addresses the problems associated with overtorque applied to the 

Booster Separation Motor (BSM) Igniter Adapter high strength [200 KSI (1379 Mpa)] 

A286 CRES bolts and the threaded holes of the 7075-T73 aluminum alloy BSM cases. 

Our evaluation included torque, tensile, and stress corrosion tests incorporating the 

A286 CRES bolts and the 7075-T73 aluminum alloy BSM cases. 

18. DISTRIBUTION STATEMENT 

Unclassified - Unlimited 

The tensile test data includes ultimate tensile load (UTL), Johnson's 2/3 yield 

load (J2/3YL), proportional limit load (PLL) , and total bolt stretch. Torque tension 

data includes torque, torque induced load, and positive and negative break-away 

torque. 

19. SECURITY CLASSIF. (Or thli repar\) 20. SECURITY CLASSIF. (or tu. pgm) 21. NO. OF PAGES 

Unclassified U ncla s sified 22 

Stress corrosion test data reflect the overtorque and the resulting torque 

induced loads sustained by the A286 CRES bolts torqued into a 7075-T73 aluminum 

alloy forged dome with threaded holes. After 60 days of salt fog exposure, the 

positive and the negative break-away torques, the subsequent mechanical property 

tensile test results, and the BSM dome threaded hole axial tensile pullout loads are 

reported. 

22. PRICE 

NTIS 

MFc - Form 3292 (h(.Y 1969) ~~ 

For sale by National Technical Information Service. Springfield. Virginia 

22161 
ACKNOWLEDGMENTS 

Mr . Michael Mason, United Space Boosters Incorporated - Mechanical Testing. 

Mr. Carl Wood, MSFC, Materials and Processes Laboratory - Torque Testing. 
c 

TABLE OF CONTENTS 

Page 

SUMMARY ..................................................................... 1 

INTRODUCTION ............................................................... 1 

EQUIPMENT AND STRESS CORROSION PROCEDURE.. .......................... 2 

RESULTS AND DISCUSSION ................................................... 2 

CONCLUSIONS ................................................................ 6 

iii 
LIST OF ILLUSTRATIONS 

Figure 

1. 

2. 

3. 

4. 

.& 5. 

Title 

End views of recovered STS-7 BSMs (forward ends) showing 

lockwire patterns produced by rotation of BSM igniter 

retention bolt heads ................................................. 

Microstructure and hardness of STS-6 BSM Martin Case 0196 

threaded hole area No. 3 showing shear deformation produced 

by 199 in.-lb (22.49 Nm) torque [Reference Table VI] ............... 

A286 CRES bolts torqued to 90 deg beyond 50 in.-lb (5.65 Nm) 

into a Martin BSM Case 0491 dome, subjected to 60 days of 

salt fog exposure [Reference Tables VIIA and B] .................... 

A286 CRES bolts and 7075-T73 aluminum alloy BSM case dome, 

west grit blast cleaned after 60 days of salt fog exposure 

[Reference Tables VIIA and B] ...................................... 

Microstructure and hardness of Martin BSM Case 0451 

threaded hole area No. 5 after 184 in.-lb (20.79 Nm) torque 

and 60 days of salt fog exposure [Reference Tables VIIA and BI .... 

Page 

17 

18 

19 d 

20 

21 

iv 
LIST OF TABLES 

Table Title 

I. Tensile Tests of EWB 0420-4H-4 (200 KSI) A286 Bolts 

(1/4-28 UNJF) ...................................................... 

11. Overtorque and Tensile Test of New EWB 0420-4H-4 (200 KSI) 

A286 Bolts Torqued into Recovered STS-6 BSM Martin Case 1096 

(Lubricant MIL-T- 5544). ............................................ 

111. Overtorque Tests of EWB 0420-4H-4 (200 KSI) A286 Bolts 

Torqued into Kaiser Plate Material, Recovered STS-6 BSM 

1 Case, and New BSM Case (Lubricant MIL-T-5544) ................... 

IV . Tensile Tests of EWB 0420-4H-4 (200 KSI) 1/4-28 A286 Bolts 

Removed from STS-7 BSM (1000014/A52-5-6/X33C13) ................ 

V. Overtorque (With and Without Lubricant) and Tensile Tests of 

EWB 0420-48-4 (200 KSI) A286 Bolts Torqued into Recovered 

STS-6 BSM Martin Case 0226 ....................................... 

VI. Threaded Hole Axial Tensile Pullout on STS-6 Aluminum 

Alloy 7075-T73 BSM Martin Case 0196 ............................... 

VIIA. EWB 0420-4H-4 (200 KSI) A286 Bolts Torqued to 90 deg 

Beyond 50 in.-lb into a Martin BSM Case 0451 Dome with 

USBI Drilled and Tapped Holes, Subjected to 60 Days 

of Salt Fog Exposure. .............................................. 

VIIB. EWB 0420-4H-4 (200 KSI) A286 Bolts Torqued to 90 deg 

Beyond 50 in.-lb into a Martin BSM Case 0451 Dome with 

USBI Drilled and Tapped Holes, Subjected to 60 Days 

of Salt Fog Exposure ............................................... 

VIII. Summary of Tensile Tests. 

A. Bolts Joining the Igniter Adapter Plates to BSM Cases ......... 

B. Overtorqued BSM Case Threaded Hole Pullout Tests ............ 

Page 

7 

8 

9 

10 

11 - 

12 

13 

14 

15 

16 

V 
TECHNICAL MEMORANDUM 

A TORQUE, TENSION, AND STRESS CORROSION EVALUATION 

OF HIGH STRENGTH A286 BOLTS 

SUMMARY 

The mechanical properties, including tensile and torque data, of high strength 

w [200 KSI (1379 MPa)] A286 CRES bolts were determined at ambient temperature for 

unstressed and for highly overtorqued bolts as related to the overtorquing problem 

associated with the Booster Separation Motor (BSM) Igniter Adapter and the 7075-T73 

aluminum alloy BSM cases. Test results indicate that overtorquing did not reduce 

the bolt load carrying capability but did reduce the total stretch as determined in 

subsequent tensile tests. 

i 

The mechanical properties of the A286 CRES bolts were not adversely affected 

after being highly overtorqued into the threaded holes of a 7075-T73 aluminum alloy 

dome and exposed to 60 days of salt fog. 

INTRODUCTION 

On Thursday, May 12, 1983, Metallic Materials Division personnel participated 

in a United Space Boosters Incorporated (USBI) flight readiness review of Space 

Transportation System (STS) 9 at the Marshall Space Flight Center (MSFC). 

purpose of the review was to determine what action must be taken in regard to 

possible damage sustained by overtorquing A286 CRES bolts during the attachment of 

the Igniter Adapter to the 7075-T73 Aluminum Alloy Booster Separation (BSM) Cases. 

The 

A 50 in.-lb (5.65 Nm) torque is specified for the 1/4-28 EWB 0420 [200 KSI 

(1379 MPa)] A286 CRES bolts used to attach the Igniter Adapter (B12016) to the 

7075-T 73 Aluminum Alloy Booster Separation Motor Case (B 12001- 01- 01) . technician following a lockwire diagram illustration had established a technique for 

bolt installation which duplicated the illustration shown in Figure 1 for STS-7 bolts. 

During his installation procedure, he was careful to use a torque wrench and 

the bolt heads to the lockwire. 

wrench to align the bolt heads after he had installed the fasteners to a 50 in.-lb 

torque. The possibility exists that the bolt heads were turned as much as 90 deg 

from the 50 in.-lb (5.65 Nm) installed position, producing an overload of unknown 

magnitude. 

However, a 

I supposedly never exceeded the 50 in.-lb (5.65 Nm) of torque when he was aligning 

One day the technician inadvertently used a socket 

The review and discussion with USBI led to an agreement to perform torque 

tension tests on new bolts and on bolts recovered from STS 7, using an electronic 

torque wrench and a load-indicating washer. Particular emphasis was placed on a 

90 deg advancement of the bolt head beyond the 50 in.-lb (5.65 Nm) torque. The 

tests were performed in used motor cases with threaded holes lubricated with MIL-T5544 and with MIL-T-83483 lubricants. Additional tests were made to determine the 

pull-out strength of the threaded holes in the BSM cases. 
When the torque tension data was plotted it revealed that bolts torqued 90 deg 

beyond the recommended 50 in .-lb (5.65 Nm) installation torque showed a yielding of 

either the bolts or the BSM aluminum alloy threaded holes. 

prompted us to perform a stress corrosion test in a salt fog cabinet using the same 

loading technique. 

This yield indication 

I 

I 6.5 to 7.2 and a temperature of 95OF (35OC). 

The salt fog test followed the procedures of ASTM-B-117-64, "Standard Method 

of Salt Spray (Fog) Testing," which specifies a 5 percent salt solution at a pH of 

EQUIPMENT 

1. Tensile and Torque Tests i 

The tensile test and torque test results are tabulated in Tables I through VI1 8 

and summarized in Table VIII. 

The equipment used in the torque tension evaluation included a GSE Torque 

Indicator and a Lebow Load Cell. - 

L 

The tensile tests were performed on a Satec Baldwin M120/HVL Machine with a 

testing speed of 0.050 in. /min (0.127 cm/min). The A286 CRES bolts were tested i 

with approximately 7 bolt threads engaged in a test fixture and 3 bolt threads 

exposed. 

STRESS CORROSION TEST PROCEDURE 

A 60-day salt fog exposure test was performed on EWB 0420-4H-4 A286 CRES 

bolts, which were torqued to 90 deg beyond 50 in.-lb (5.65 Nm) into a 7075-T73 

aluminum alloy Martin BSM case dome with USBI drilled and tapped holes. Actual 

installation conditions were simulated by using MS 20002- 4C countersunk washers , MIL-T-83483 lubricant and 303 stainless steel spacers, which provided bolt thread 

engagement similar to the 303 S.S. igniter housing flange. 

RESULTS AND DISCUSSION 

a. Tensile Tests - New A286 Bolts 

Ten tensile tests were performed on new EWB 0420-48-4 A286 bolts to 

determine the ultimate tensile load (UTL) , Johnson's approximate 2/3 yield load 

(J2/3YL) (as described in the HIAD AFSCM Vol. 1, Part By Chapter 4), proportional 

load limit (PLL) and the total bolt stretch taken from the load-strain curve. These 

results are shown in Table I. The average UTL of 8402 lb (3819 kg) is well within 

the 7270 lb (3304 kg) minimum load requirement for the EWB 0420-48-4 bolt load as 

stated in SPS-B-640, Appendix 4.5. 
b. Overtorque Tests - STS-6 BSM Case 

Table I1 contains torque and tension test data for new bolts which were 

torqued to approximately 180 deg past 50 in .-lb (5.65 Nm) into a recovered STS-6 

BSM motor case. In three of the four threaded holes the overtorque produced shear 

yielding in the aluminum alloy case threads. 

overtorqued bolts showed mechanical properties comparable to those shown in Table I 

for bolts which had not been overtorqued. 

The subsequent tensile tests on the 

C. Overtorque Tests - Aluminum Alloy Plate, STS-6 BSM Cases, and New 

BSM Case 

Overtorque tests data for the high strength A286 bolts torqued into a 7075- 

T73 aluminum alloy plate, recovered STS-6 BSM aluminum alloy cases, and a new BSM 

aluminum alloy case, are reported in Table 111. The torque, torque induced loads, 

and negative break-away torques are tabulated for bolts which were torqued to 

approximately 90 deg passed 50 in.-lb (5.65 Nm) . . 

d. STS-7 Bolts 

The positive break-away torque values recorded when bolts were removed 

from a STS-7 BSM case are reported in Table IV. These values are extremely high 

when compared to the correct installation torque of 50 in.-lb (5.65 Nm) . six A286 CRES bolts removed from STS-7 were subjected to various overtorque loads 

prior to tensile testing. 

torque values [165 and 185 in-lb (18.64 and 20.90 Nm)] were not subjected to additional torque induced loads. When tensile tested they showed the highest UT loads 

of the STS-7 bolts tested. 

Four of the 

The two bolts which exhibited high positive break-away 

All of the STS-7 bolts tested, regardless of installation torque or additional 

torque, showed excellent mechanical properties which were well within specification 

values for new EWB 0420-4H-4 bolts. 

notched tensile properties of cold worked A286 CRES under conditions which might 

easily produce failure in other alloys of the same strength level. 

This data illustrates the excellent ductility and 

e. Torque Tests With and Without MIL-T-83483 Lubricant 

Table V shows the increase in the torque induced load with the MIL-T-83483 

lubricant as opposed to torquing without a lubricant. 

reported in Table I; however, these high values are not higher than those from bolts 

removed from STS-7, reported in Table IV. 

Note that bolt No. 46 had a r significantly higher UTL and J2/3 YL than any of the ten new bolts which are 

f. Threaded Hole Pullout Test - STS-6 BSM Case 

Table VI lists the results of the threaded hole axial tensile pullout tests on 

the STS-6 Aluminum Alloy BSM Martin Case 0196. Four of the seven threaded holes 

were subjected to various torque induced loads, which actually produced shear yielding in two of the threaded holes, prior to the tensile pullout tests. 

area No. 3, shown in Figure 2, is indicative of the mode of deformation. 

Threaded hole 

3 
2. Salt Fog - Stress Corrosion Tests 

Table VIIA lists the torques obtained at 90 deg past 50 in.-lb (5.65 Nm) for the 

six bolts that were torqued into a drilled and tapped Martin BSM 7075-T73 aluminum 

alloy forged case dome and subjected to a stress corrosion test. Note that each of 

the threaded holes was exercised three times to 50 in-lb (5.65 Nm) of torque prior 

to the installation of the identified test bolts. 

the MIL-T-83483 lubricant and an A286 CRES bolt which was not used in the stress 

corrosion test. 

These exercises were performed using 

3. Summary of Test Results 

A 60-day salt fog exposure test was conducted on EWB 0420-4H-4 A286 CRES 

bolts which were torqued to 90 deg beyond 50 in.-lb (5.65 Nm) into a 7075-T73 

aluminum alloy Martin BSM case dome with USBI drilled and tapped holes. 

installation conditions were simulated by using MS 20002- 4C countersunk washers, MILT-83483 lubricant and 303 stainless steel spacers, which provided bolt thread engagement similar to the 303 S.S. igniter housing flange. Figure 3 shows these components 

prior to salt fog exposure and after 14 days, 30 days, and 60 days exposure. 

Actual 

4 

Table VIIB is a continuation of the stress corrosion test as described in Table 

VIIA. The installation torque and the positive and negative break-away torque values 

are reported after 60 days of salt fog exposure. 

There were no bolt failures or dome threaded hole pullouts. Positive breakaway torques, measured after 60 days, indicated good load retention values. Tensile 

tests performed on the six test volts showed excellent mechanical properties. 

hole axial tensile pullout tests produced high loads, indicating good load carrying 

capability in the aluminum forging threads. 

Threaded 

The MS20002-4C cadmium plated steel washers began rusting in less than 18 hr 

and the 7075-T73 aluminum forging began corroding after two to five days exposure. 

The A286 CRES fasteners and the 303 S .S. spacers showed no signs of corrosive attack. 

The case dome experienced some pitting corrosion as shown in Figure 4, 

especially where the rust from the alloy steel washer contacted the aluminum. The 

areas under the 303 S .S . spacers and the threads showed no evidence of corrosion. 

One of the threaded hole areas which was cross-sectioned and examined metallographically was found to be in good condition inasmuch as there were no corroded, 

cracked, or badly distorted threads (Fig. 5). 

4 

1 
RESULTS AND DISCUSSION 

In considering what, if any, detrimental effects were produced in the 1/4-28 

A286 CRES EWB 0420-48-4 bolts by the 90 deg beyond 50 in-lb (5.65 Nm) torque, 

the following must be evaluated: 

1) Torque induced loads 

2) Comparison of the torque induced loads to the loads obtained in the tensile 

tests. 

3) Determination of the stress produced by the torque induced loads. 

The torque induced loads reported in Table VIIA were obtained by using MIL-T83483 lubricant and new A286 CRES bolts torqued into drilled and tapped 7075-T73 

aluminum alloy dome holes. 

(5.65 Nm) torque using the MIL-T-83483 lubricant prior to installation of the new 

bolts. 

(20.34 Nm) and a torque induced load of approximately 6800 lb (3084.48 kg) . 

These holes were exercised three times to 50 in.-lb 

The 90 deg beyond 50 in-lb (5.65 Nm) torque produced a torque of 180 in-lb 

2 Using the bolt manufacturer's recommended cross sectional area of 0.03637 in. 

(0.2346 cm ) found in SPS-2-1510 for a diameter of 1/4-28 threads/in. the resulting 

stress in this bolt would be 186.97 KSI (1289.12 MPa). 

2 

For comparison purposes, the average J 2/3 Y load for the new EWB 0420 bolts 

(Table I) used in this evaluation was 7745 lb (3513.13 kg) which converts to 212.95 

KSI (1468.25 MPa) . 

For bolts tensile tested after the stress corrosion test, the lowest J 2/3 Y load 

was 7800 lb (3538.08 kg) which converts to 214.46 KSI (1478.67 MPa). 

Certainly the values obtained in this investigation of overtorqued A286 CRES 

bolts exceeds our conservative requirements found in MSFC STD 486-(4) General 

Requirements which specifies that the torque (torque induced load) will not exceed 

65 percent of the J 2/3 tensile yield strength (load). 

What has been determined in this investigation is that torque induced loads have 

1 not been produced in any of the 90 deg passed 50 in-lb (5.65 Nm) torque which 

exceeded or equalled the J 2/4 Y load for new or previously torqued EWB-0420-4H-4 

A 2 8 6 b ol t s . 

Extreme overtorque of 180 deg past 50 in-lb (5.65 Nm) produced shear yielding 

in the 7075-T73 aluminum alloy case threads; however, subsequent tensile tests of 

the overtorqued bolts (Table 11) indicated mechanical properties comparable to those 

obtained with new bolts (Table I). Repeated reuse of the bolts in an overtorqued 

condition will eventually deplete all of the elongation potential in the threads and 

will produce failure. 

li 

5 
CONCLUSIONS 

6 

c 

The results of the torque, tensile, and stress corrosion tests indicate the 

following : 

1) The high strength A286 CRES fasteners used in this application were not 

adversely affected by torquing the bolts to 90 deg beyond the recommended 50 in-lb 

(5.65 Nm) installation torque. This overtorque equalled approximately 180 in-lb 

(20.34 Nm) and produced a torque induced load of approximately 6800 lb (3084.48 kg) . Using the bolt manufacturer recommended stress area, this load translates to 186.97 

KSI (1289.12 MPa) . 

2) The 90 deg beyond 50 in.-lb (5.65 Nm) torque did not produce torque 

induced loads which exceeded or equalled the Johnson's 2/3 yield load for new or 

previously torqued EWB-0420-4H-4 A286 bolts. 

3) The load carrying capability of the threaded holes in the BSM cases, which 

were loaded to 90 deg beyond 50 in-lb (5.65 Nm) torque, was good. However, shear 

yielding of the threads is possible depending on the lubricant used and the number 

of reuse cycles. 

4) Overtorque to 90 deg beyond 50 in.-lb (5.65 Nm) and exposure to salt fog 

did not adversely affect the EWB 0420-48-4 A286 bolts. 

pullout tests produced high loads illustrating the good load carrying capability of the 

7075-T 73 aluminum alloy forging threads. 

Threaded hole axial tensile 

5) 

reuse cycles) and the resulting torque induced loads, especially in the aluminum alloy 

forging threads, caution is recommended when applying the results obtained from this 

investigation to any similar flight hardware torque anomaly. 

bolts in an overtorqued condition will eventually use up all of the elongation potential 

in the threads and will result in failure. 

Due to the variables associated with torque (lubricants and the number of 

Repeated reuse of the 

. 
TABLE I 

TENSILE TESTS OF EWB 0420-4H-4 (200 KSI) A286 BOLTS (1/4-28 UNJF) 

Bo1 t 

Ident. 

# 

13 

15 

22 

23 

24 

35 

37 

40 

41 

43 

Ultimate Tensile 

Load 

Lbs. 

8388 

8386 

8335 

8430 

q359 

8358 

8488 

8451 

8381 

8447 

Johnson's 2/3 

Yield Load* 

Lbs. 

7700 

7675 

7625 

7850 

7625 

7650 

7900 

7800 

7825 

7800 

Proportional 

Limit 

Lbs. 

6820 

6850 

6800 

6820 

6800 

6750 

6750 

6800 

6850 

6850 

Bolt 

Stretch 

Inches 

.0440 

.0425 

.0440 

.0430 

,0440 

.0430 

.0415 

.0430 

.0440 

.0440 

AVG . -- 8402 7745 6809 .0433 

Testing Machine: Satec Baldwin M120/HvL 

Testing speed: .05 Inches/Minute ( .27 an/Minute) 

Bolt Thread Fhgagement: -7 Threads Engaged h Test Fixture and 

3 Threads Exposed 

*Johnson's 2/3 Approx. Method: HIAD UW AFSCM Vol. l-Part B-Chapter 4 

or 

MIL-S"D-1312-Test 8-Tensile Strength 

2 

KSI = 6.8948 Mega Newtons/m2 = 6.8948 Mega Pascdls/m 

Pound = 453.6 Grams = .4536 Kilograms 

Inch = 2.54 an 

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TABLE I11 

OVERTORQUE TESTS OF EWB 0420-4H-4 (200 KSI) A286 BOLTS 

TORQUED INTO KAISER PLATE MATERIAL, RECOVERED STS-6 BSM CASES, 

AND NEW BSM CASE 

(LUBRICANT MIL T 5544) 

Bolt 

Ident . # 

16 

17* 

18 

19 

20 

21 

25 

30 

31 

32 

NOTES : 

Case Angle Torque 

or Torque Degrees Induced Load 

Plate In-Lbs. >50 In-Lbs. Lbs. 

Kaiser Plate 

Kaiser Plate 

0244 

0244 

0279 

0279 

0196 

0196 

0196 

0196 

180 

181 

142 

155 

195 

171 

145 

170 

190 

144 

90' 

107' 

91' 

92' 

90' 

90' 

102' 

102O 

99 O 

91° 

6062 

6039 

6964 

6644 

5851 

6152 

6118 

6904 

6889 

6670 

Bolts 16 & 17: Torqued into Kaiser 7075-T73 Aluminum Alloy Plate - 3.0 Inch 

Thick with USBI Drilled & Tapped Holes (1/4-28 UT?). 

Torqued into Recavered STS-6 Martin Case 0244. 

Torqued into New Martin Case 0279 Dane with USBI Drilled & 

Tapped Holes Y1/4-28 UNF) . 

Bolts 18 & 19: 

Bolts 20 & 21: 

Bolts 25, 30, 31 & 32: Torqued into Recovered STS-6 Martin Case 0196. 

*Bolt #17: Previously Torqued to 44 Degrees Beyond 50 Inch-Lbs Producing 

140 Inch-Lbs of Torque and 4393 Lbs. 

1 KSI = 6.8948 Mega Newtons/m2 = 6.8948 Mega Pascals/m 2 

1 Pound = 453.6 Grams = -4536 Kilograms 

1 Inch Lb = .113 Newton Peter 

Negative 

Break-Away 

Torque 

In-Lbs. 

92 

102 

52 

72 

110 

90 

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11 
TABLE VI 

THREADED HOLE AXIAL TENSILE PULLOUT TESTS ON STS-6 

ALUMINUM ALLOY 7075-T73 BSM MARTIN CASE 0196 

Hole Proportional Pullout 

Ident. Limit Load 

# Lbs. Lbs. Lubrication 

8 7100 7664 MIL T 83483 

7 7050 7470 II 

6 7200 7814 None 

5* 7100 7657 NIL T 83483 

2" 6220 6702 MIL T 83483 

1* 6450 7050 I1 

*ms : 

Bolt Hole #5: Previously Torqued to 186 Inch-Lbs/6994 Lbs/185O Passed 50 Inch-Lbs 

Bolt Hole #3: Previously Torqued to 175 Inch-Lbs/7050 Lbs/127O Passed 50 Inch-Lbs 

Torque Continued to 199 Inch-Lbs/6438 Lbs/185O Passed 50 Inch-Lbs 

(lptallographic Sanple) 

Torque Continued to 220 Inch-Lbs/6588 Lbs/16So Passed 50 Inch-Lbs 

Torque Continued to 188 Inch-Lbs/6731 Lbs/188O Passed 50 Inch-Lbs 

Bolt Hole #2: Previously Torqued to 196 Inch-Lbs/6896 Lbs/llSo Passed 50 Inch-Lbs 

Bolt Hole #1: Previously Torqued to 171 Inch-Lbs/6904 Lbs/135O Passed 50 Inch-Lbs 

mwmr: 

The reduction of torque induced load with increasing torque indicates shear yielding 

of Holes #1 & 2. 

1 Pound = 453.6 Grm = .4536 Kilograms 

12 
TABLE viiA 

EWB 0420-4H-4 (200 KSI) A286 BOLTS TORQUED TO 90° BEYOND 50 INCH-LBS. 

INTO A MARTIN BSM CASE 0451 DOME WITH USBI DRILLED AND TAPPED HOLES 

SUBJECTED TO 60 DAYS OF SALT FOG* EXPOSURE 

Torque Negative 

Bo1 t Dome Angle Induced Break-Away 

Ident. Hole Torque Degrees Load Torque 

# Number In-Lbs. >50 In-Lbs. Lbs. In-Lbs. 

None 1 51 

51 

50 

51 

180 

-- 627 40 

-- 1037 32 

-- 1634 29 

00 2228 -- 

900 6832 99 

27 1 196 

None 2 50 

50 

50 

29 2 176 

40 

30 

24 

-- 

None 3 50 

50 

50 

28 3 180 

-- 

goo 

-- 

21 

19 

-- 

None 4 50 37 

50 29 

50 21 

33 4 191 900 -- 

None 5 50 

50 

50 

39 184 

-- 

goo 

32 

28 

23 

None 6 50 

50 

50 

38 6 185 

29 

21 

20 

-- 

NOTES: 1 Inch Lb = .113 Newton Neter 

Each Dorrre Threaded Hole Lubricated and Exercised 3 Times to 50 Inch-Lbs. of 

Torque Prior to Installation of Identified Bolt. 

BSM Cas 0451 Dane: 

Bolts: A-286 CRES per EM3 0420 (1/4-28) 

Washers: 

Spacers: 

Lubricant: MIL T 83483 

5% NaCl Solution at a F€I of 6.5-7.2 and a Taperatwe of 95OF (35OC). 

7075 T73 Alumh'UKi Alloy Forsing. 

Cadmium Plated Alloy Steel per MS20002-4C. 

303 Stainless Steel (0.273 Inch Thick). 

* SdLt Fog per ASIM-B-117-64 

13 
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TABLE VI11 

SUMMARY OF TENSILE TESTS 

A. BOLTS JOINING THE IGNITER ADAPTER PLATES TO BSM CASES 

TABLG I - TENSILE TEST - (10) NEXJ A286 CRES BOLTS 

Ultimate Tensile Lmd Johnson's 2/3 Yield Imd Bolt Stretch 

Average 8402 Lbs. 7745 Lbs. .0433 Inch 

Range (8335 to 8488) (7625 to 7900) (.0415 to .0440) 

Resuirmt 7270 Lbs. Minimum per W-0420-4 (SPS-B-640 Appendix 4.5) 

TABU I1 - TENSILE TEST - (4) A286 CRES BOLTS TOTD -180' BEYOM) 50 IN.-LBS. (5.65 Ean) 

Ultimate Tensile Load Jahnson's 2/3 Yield Mad Bolt Stretch 

Average 8428 Lbs. 8050 Lbs. .0386 Inch 

Range (8341 to 8480) (7900 to 8150) (.0375 to .0400) 

TABLE IV - TENSILE TEST - (2) A286 CRES BOLTS RECOVERED FfEaM SI'S-7 

Ultimate Tensile Lmd Johnson's 2/3 Yield Load Bolt Stretch 

Average 8848 Lbs. 8375 Lbs. .0420 Inch 

Rarrge (8821 to 8874) (8350 to 8400) ( .0415 to ,0425) 

TABU V - TENSILE TEST - (2) A286 CRES BOLTS TOWITH AND WITHaTT MIL-"-83483 LUBRICANT 

Ultimate Tensile Load Johnson's 2/3 Yield Load Bolt Stretch 

With Lube 8397 Lbs. 7950 Lbs. .0455 Inch 

Without Lube 8733 Lbs. 8250 Lbs. .0430 Inch 

TABIE VIIB - TENSILE TEST - (6) A286 CRES BOLTS - AFTER SALT FOG ExposuRE 

Average 

Range 

Ultimate Tensile Load Jahnson's 2/3 Yield Mad Bolt Stretch 

8425 Lbs. 8012 Lbs. .0422 Inch 

(8293 to 8608) (7800 to 8325) (.0390 to .0460) 

15 
TABLE VI11 . (Concluded) 

B. OVERTORQUED BSM CASE THREADED HOLE PULLOUT TESTS 

TABLE VI - TENSILE TEST - FUJBUl? SWE3GTH OF SI'S-6 BSH CASE 0196 THREADED HOLES (6) 

Ultimate Tensile Icad Proportional Limit Load 

Average 7649 Lbs. 7117 Lbs. 

3 Tests-& Rec. Holes 

Range (7470 to 7814) (7050 to 7200) 

Average 7140 I$S. 

3 Tests-overtorqued Holes 

Range (6702 to 7657) 

6590 Us. 

(6220 to 7100) 

Average 

Range 

Ultimate Tensile Inad Praportional Limit Icad 

7692 Ibs. 7380 Us. 

(7312 to 7898) (7250 to 7550) 
ORIGINAL PAGE IS 

Of POOR QUALm 

. 

Figure 1. End Views of Recovered STS-7 BSMS (Forward Ends) Showing Lockwire 

Patterns Produced by Rotation of BSM Igniter Retention Bolt Heads. 

17 
18 
ORIGINAL PAGE IS 

OF POOR QUALITY 

19 
Figure 4. A286 CRES Bolts and 7075-T73 Aluminum Alloy BSM Case Dome 

Wet Grit Blast Cleaned After 60 Days of Salt Fog Exposure 

[Reference: Tables VI1 A and Bl 

20 
. 

m 

=u 

cd 

a, 

k 

4 

Ll OF POOR QUAun 
APPROVAL 

A TORQUE, TENSION, AND STRESS CORROSION EVALUATION 

OF HIGH STRENGTH A286 BOLTS 

By J. W. Montan0 

The information in this report has been reviewed for technical content. 

of any information concerning Department of Defense or nuclear energy activities or 

programs has been made by the MSFC Security Classification Officer. 

in its entirety, has been determined to be unclassified. 

Review 

This report, b 

R. J. SCHWINGHAMER 11 

Director, Materials and Processes Laboratory 

QUS. GOVERNMENT PRINTING OFFICE 1986-631-068/20101 

22