December 2015

NASA/TM2015-218797

NESC-RP-13-00884

 

Spin Forming of an Aluminum 2219-T6 

Aft Bulkhead for the Orion Multi-Purpose 

Crew Vehicle

Phase II Supplemental Report

Robert S. Piascik/NESC and Michael D. Squire/NESC

Langley Research Center, Hampton, Virginia

Marcia S. Domack and Eric K. Hoffman

Langley Research Center, Hampton, Virginia
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December 2015

NASA/TM2015-218797

NESC-RP-13-00884

 

Spin Forming of an Aluminum 2219-T6 

Aft Bulkhead for the Orion Multi-Purpose 

Crew Vehicle

Phase II Supplemental Report

Robert S. Piascik/NESC and Michael D. Squire/NESC

Langley Research Center, Hampton, Virginia

Marcia S. Domack and Eric K. Hoffman

Langley Research Center, Hampton, Virginia
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Hampton, VA 23681-2199

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The use of trademarks or names of manufacturers in the report is for accurate reporting and does not 

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NASA Engineering and Safety Center

Technical Assessment Report

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NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

1 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

Phase II Supplemental Report

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion 

Multi-Purpose Crew Vehicle

October 28, 2015
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

2 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

Table of Contents

1.0 Notification and Authorization.....................................................................................................7

2.0 Executive Summary.......................................................................................................................8

3.0 Background ..................................................................................................................................11

3.1 Orion MPCV Aft Bulkhead..............................................................................................11

3.2 Spin Formed Aft-Bulkhead Pathfinder.............................................................................12

4.0 Supplemental Mechanical Test Program...................................................................................13

4.1 Objectives.........................................................................................................................13

5.0 Supplemental Stress Corrosion Tests.........................................................................................13

5.1 Background ......................................................................................................................13

5.2 Test Procedures ................................................................................................................16

5.3 Stress Corrosion Results...................................................................................................23

5.4 Stress Corrosion Summary...............................................................................................59

6.0 Supplemental Tensile Tests.........................................................................................................62

6.1 Background ......................................................................................................................62

6.2 Microstructural Analysis..................................................................................................62

6.3 Heat Treat Practice ...........................................................................................................72

6.4 Tensile Test Procedures....................................................................................................74

6.5 Tensile Test Results..........................................................................................................79

6.5.1 Effect of Through-Thickness Position on Tensile Properties..........................79

6.5.2 Effect of Heat Treat Variant on Tensile Properties.........................................82

6.6 Tensile Summary..............................................................................................................84

7.0 Supplemental Fracture Toughness Tests...................................................................................85

7.1 Fracture Toughness Test Procedures................................................................................85

7.2 Fracture Toughness Test Results......................................................................................88

7.2.1 Aft Bulkhead Fracture Toughness Results......................................................88

7.2.2 Supplemental Fracture Toughness Test Results..............................................91

7.2.3 Effect of Heat Treat Variant on Fracture Toughness ......................................92

7.2.4 Comparison with Other Al 2219-T62 Spin Formed Product ..........................96

7.3 Fracture Toughness Summary..........................................................................................98

8.0 Findings, Observations, and NESC Recommendations..........................................................100

8.1 Findings..........................................................................................................................100

8.2 Observations...................................................................................................................101

8.3 NESC Recommendations...............................................................................................102

9.0 Acronyms List ............................................................................................................................102

10.0 References...................................................................................................................................104

11.0 Appendices..................................................................................................................................106

11.1 Appendix A: Photomicrographs of Specimens from the Phase II Stress Corrosion 

Tests; LT Orientation .....................................................................................................106

11.2 Appendix B: Photomicrographs of Specimens from the Phase II Stress Corrosion 

Tests; ST Orientation......................................................................................................122

11.3 Appendix C: Summary of the Supplemental SCC Test Results following 30-day 

3.5% NaCl Alternate Immersion Exposure ....................................................................148
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NESC Request No.: TI-13-00884_Phase II Supplemental Report

11.4 Appendix D: Summary of the Phase II SCC Test Results Following 30-day 3.5% 

NaCl Alternate Immersion Exposure .............................................................................150

List of Figures

Figure 1. Orion MPCV Configuration.................................................................................................12

Figure 2. Diagram showing Coupon Blank Locations for SCC Tests of the Spin Formed Aft 

Bulkhead ..............................................................................................................................17

Figure 3. Round Sub-Size Tensile Specimen Design used for SCC Testing ......................................19

Figure 4. Stress-Strain Curves for (a) non-exposed specimens and (b) exposed specimens of Al 

2219-T62..............................................................................................................................32

Figure 5. Photomicrographs of SCC Specimens from Aft Bulkhead Coupon Blank M10

following 30-day 3.5% NaCl Alternate Immersion Exposure at Applied Stress 

Levels of (a) 0% YS; (b) 50% YS (measured); (c) 50% YS (MMPDS); (d) 75% YS 

(measured); and (e) 75% YS (MMPDS)..............................................................................37

Figure 6. Photomicrographs of SCC Specimens from Aft Bulkhead Coupon Blank J1 

following 30-day 3.5% NaCl Alternate Immersion Exposure at Applied Stress 

Levels of (a) 0% YS; (b) 50% YS; and (c) 75% YS............................................................40

Figure 7. Photomicrographs of SCC Specimens from Aft Bulkhead Coupon Blank J2 

following 30-day 3.5% NaCl Alternate Immersion Exposure at Applied Stress 

Levels of (a) 0% YS; (b) 50% YS; and (c) 75% YS............................................................43

Figure 8. Photomicrographs of SCC Specimens from Aft Bulkhead Coupon Blank J3 

following 30-day 3.5% NaCl Alternate Immersion Exposure at Applied Stress 

Levels of (a) 0% YS; (b) 50% YS; and (c) 75% YS............................................................46

Figure 9. Photomicrographs of SCC Specimens from Standard Plate following 30-day 3.5% 

NaCl Alternate Immersion exposure at Applied Stress Levels of (a) 0% YS; (b) 50% 

YS; and (c) 75% YS.............................................................................................................49

Figure 10. Photomicrographs of SCC Specimens from Modified Plate following 30-day 3.5% 

NaCl Alternate Immersion Exposure at Applied Stress Levels of (a) 0% YS; (b) 50% 

YS; and (c) 75% YS.............................................................................................................52

Figure 11. Photomicrographs of SCC Specimens from the CPST Dome Pole following 30-day 

3.5% NaCl Alternate Immersion Exposure at Applied Stress Levels of (a) 0% YS; 

(b) 50% YS; and (c) 75% YS...............................................................................................55

Figure 12. Photomicrographs of SCC Specimens from the CPST Dome rim following 30-day 

3.5% NaCl Alternate Immersion Exposure at Applied Stress Levels of (a) 0% YS; 

(b) 50% YS; and (c) 75% YS...............................................................................................58

Figure 13. Aft Bulkhead Cut Plan showing the Location of the Tensile Coupon Blank for 

Supplemental Testing highlighted in Yellow.......................................................................64

Figure 14. Coupon Blank L2 showing the Locations of the Phase II and Supplemental Tensile 

Specimens............................................................................................................................64

Figure 15. Through-thickness Microstructure of Aft Bulkhead Coupon Blank L2 in the (a) L-S 

Plane and (b) LT-S Plane.....................................................................................................66

Figure 16. Inverse Pole Figure Maps at t/8, t/2, and 7t/8 of Aft Bulkhead Coupon Blank L2 for 

the (a) L-S and (b) LT-S Planes...........................................................................................68

Figure 17. Texture Maps at t/8, t/2, and 7t/8 of Aft Bulkhead Coupon Blank L2 for the (a) L-S 

and (b) LT-S Planes.............................................................................................................70

Figure 18. Pole Figures for the t/8, t/2, and 7t/8 Through-Thickness Positions of Aft Bulkhead 

Coupon Blank L2 for the (a) L-S and (b) LT-S Planes........................................................72
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Figure 19. Cooling Rate Curves for Water Quench and Glycol Quench Mediums. .............................73

Figure 20. Round Subsize Tensile Specimen Design used for Testing in the L and LT 

Orientations..........................................................................................................................74

Figure 21. Round Subsize Tensile Specimen Design used for Testing in the ST Orientation ..............75

Figure 22. Tensile Test Load Stand, Specimen, and Instrumentation. ..................................................77

Figure 23. Typical Stress-Strain Curve for the Spin Formed Al 2219-T62 Aft Bulkhead Material 

in the L Orientation; Coupon Blank L2, Specimen T-L2-L-13 ...........................................78

Figure 24. JIC Fracture Toughness Specimen Design; L-T and T-L Orientations.................................86

Figure 25. JIC fracture Toughness Specimen Design; S-T and T-S Orientations ..................................87

Figure 26. JIC fracture Toughness Specimen and Test Apparatus. ........................................................87

Figure 27. Aft Bulkhead Cut Plan showing the Location of the Fracture Toughness Test Coupon 

Blanks highlighted in Yellow ..............................................................................................88

Figure 28. Fracture Toughness Data Summary for Wrought Al-2219-T62 Plate Heat Treated 

using Standard and Modified Heat Treat Variants...............................................................92

Figure 29. J-R Curve and Fracture Surface of Specimen CP-406-27 from Standard Heat Treat 

Al 2219-T62 Wrought Plate; T-L Orientation .....................................................................93

Figure 30. J-R Curve and Fracture Surface of Specimen CP-406A-1 from Modified Heat Treat 

Al 2219-T62 Wrought Plate; T-L Orientation .....................................................................94

Figure 31. Fracture Toughness of Standard and Modified Heat Treat Wrought Plate vs. Spin 

Formed Aft Bulkhead; L-T Orientation...............................................................................95

Figure 32. Fracture Toughness of Standard and Modified Heat Treat Wrought Plate vs. Spin 

Formed Aft Bulkhead; T-L Orientation...............................................................................96

Figure 33. J-R Curve and Fracture Surface of Specimens CP-406A-62 from the Pole Region of 

the Al 2219-T62 Spin Formed CPST Dome; S-T Orientation.............................................97

Figure 34. Fracture Toughness of Spin Formed CPST Dome vs. Aft Bulkhead; S-T Orientation. ......98

Figure A-1. Photomicrographs of SCC Specimens from Aft Bulkhead Coupon Blank M7 

following 30-day 3.5% NaCl Alternate Immersion Exposure at Applied Stress 

Levels of (a) 0% YS; (b) 50% YS; (c) 75% YS; and (d) 90% YS.....................................109

Figure A-2. Photomicrographs of SCC Specimens from Aft Bulkhead Coupon Blank M8 

following 30-day 3.5% NaCl Alternate Immersion Exposure at Applied Stress 

Levels of (a) 0% YS; (b) 50% YS; (c) 75% YS; and (d) 90% YS.....................................113

Figure A-3. Photomicrographs of SCC Specimens from Aft Bulkhead Coupon Blank M9 

following 30-day 3.5% Nacl alternate Immersion Exposure at Applied Stress Levels 

of (a) 0% YS; (b) 50% YS; (c) 75% YS; and (d) 90% YS ................................................117

Figure A-4. Photomicrographs of SCC Specimens from Aft Bulkhead Coupon Blank M10 

following 30-day 3.5% NaCl Alternate Immersion Exposure at applied Stress Levels 

of (a) 0% YS; (b) 50% YS; (c) 75% YS; and (d) 90% YS ................................................121

Figure B-1. Photomicrographs of SCC Specimens from Aft Bulkhead Coupon Blank M7 

following 30-day 3.5% NaCl Alternate Immersion Exposure at Applied Stress 

Levels of (a) 0% YS; (b) 50% YS; (c) 75% YS; and (d) 90% YS.....................................109

Figure B-2. Photomicrographs of SCC Specimens from Aft Bulkhead Coupon Blank M8 

following 30-day 3.5% NaCl Alternate Immersion Exposure at Applied Stress 

Levels of (a) 0% YS; (b) 50% YS; (c) 75% YS; and (d) 90% YS.....................................113

Figure B-3. Photomicrographs of SCC Specimens from Aft Bulkhead Coupon Blank M9 

following 30-day 3.5% NaCl Alternate Immersion Exposure at Applied Stress 

Levels of (a) 0% YS; (b) 50% YS; (c) 75% YS; and (d) 90% YS.....................................117
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NESC Request No.: TI-13-00884_Phase II Supplemental Report

Figure B-4. Photomicrographs of SCC Specimens from aft Bulkhead Coupon Blank M10 

following 30-day 3.5% NaCl Alternate Immersion Exposure at Applied Stress 

Levels of (a) 0% YS; (b) 50% YS; (c) 75% YS; and (d) 90% YS.....................................121

List of Tables

Table 1. Supplemental SCC Test Matrix and Questions being Addressed ........................................15

Table 2. SCC Coupon Blank Locations and Orientations..................................................................18

Table 3. Supplemental SCC Test Matrix ...........................................................................................20

Table 4. Supplemental SCC Test Results for Spin Formed Al 2219-T62 Aft Bulkhead, CPST 

Dome and Wrought Plate Materials following 30-day 3.5% NaCl Alternate 

Immersion Exposure ............................................................................................................26

Table 5. Phase II SCC Test Results for Spin Formed Al 2219-T62 Aft Bulkhead Material 

following 30-day 3.5% NaCl Alternate Immersion Exposure. ............................................27

Table 6. Baseline Tensile Properties of the Al 2219-T62 Supplemental Test Materials...................28

Table 7. Residual Load Carrying Ability Data for Supplemental Al 2219-T62 Spin Formed

and Wrought Plate Materials following 30-day 3.5% NaCl Alternate Immersion 

Exposure with an Applied Stress.........................................................................................29

Table 8. Residual Tensile Strength and Percent Tensile Strength Retained for Supplemental 

Al 2219-T62 Spin Formed and Wrought Plate Materials following 30-day 3.5% 

NaCl Alternate Immersion Exposure with No Applied Stress.............................................30

Table 9. Residual Load Carrying Ability Data from the Phase II SCC Testing of Spin Formed 

Al 2219-T62 Aft Bulkhead Material following 30-day 3.5% NaCl Alternate 

Immersion Exposure ............................................................................................................31

Table 10. Supplemental Tensile Test Matrix and Questions being Addressed....................................62

Table 11. Grain Sizes for the L and LT Planes at t/8, t/2, and 7t/8 of Aft Bulkhead Coupon 

Blank L2...............................................................................................................................68

Table 12. Supplemental Tensile Test Matrix for the Aft Bulkhead and Remnant Plate Material........76

Table 13. Tensile Properties of the Spin Formed Al 2219-T62 Aft Bulkhead Material from 

Coupon blank L2 at Through-Thickness Positions t/8, t/2, and 7t/8 in Longitudinal 

(L) and Long Transverse (LT) Orientations.........................................................................79

Table 14. Average Tensile Properties and Standard Deviation Values for the Spin Formed Al 

2219-T62 Aft Bulkhead Material as a Function of Through-Thickness Position and 

Orientation ...........................................................................................................................80

Table 15. MMPDS Design Allowables and Alcoa Typical Tensile Properties at Room 

Temperature for Al 2219-T62 Plate.....................................................................................81

Table 16. Tensile Properties of Al 2219-T62 Plate Processed using Standard (water quench) 

and Modified (glycol quench) Heat Treatment as per AMS 2770.......................................82

Table 17. Average Tensile Properties and Standard Deviation Values of Al 2219-T62 Plate 

Processed using Standard and Modified Heat Treatment as per AMS 2770. ......................83

Table 18. Average Tensile Properties and Standard Deviation Values for the Spin Formed Al 

2219-T62 aft Bulkhead Material..........................................................................................83

Table 19. Supplemental Fracture Toughness Test Matrix and Questions being Addressed ................85

Table 20. Fracture Toughness Coupon Blank Locations and Orientations..........................................89

Table 21. Summary of Fracture Toughness Data for the Spin Formed Al 2219-T62 Aft 

Bulkhead Material................................................................................................................90
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Table 22. Summary of Fracture Toughness Data for Al 2219-T62 Wrought Plate and Spin 

Form Dome Material............................................................................................................91

Table C-1. Supplemental SCC Test Results for Spin Formed Al 2219-T62 Aft Bulkhead, CPST 

Dome and Wrought Plate Materials following 30-day 3.5% NaCl Alternate 

Immersion Exposure ..........................................................................................................148

Table D-1. Phase II SCC Test Results for Spin Formed Al 2219-T62 Aft Bulkhead Material 

following 30-day 3.5% NaCl Alternate Immersion Exposure; LT Orientation.................150

Table D-2. Phase II SCC Test Results for Spin Formed Al 2219-T62 Aft Bulkhead Material 

following 30-day 3.5% NaCl Alternate Immersion Exposure; ST Orientation .................151
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Supplemental Report

1.0 Notification and Authorization 

The principal focus of this project was to assist the Orion Multi-Purpose Crew Vehicle (MPCV) 

Program in developing a spin forming fabrication process for manufacture of the aft bulkhead of 

the pressure vessel. The spin forming process will enable a single piece aluminum (Al) 2219 aft 

bulkhead which will eliminate the current multiple piece welded construction, simplify 

fabrication, and lead to an enhanced design that will reduce vehicle weight by eliminating welds. 

Phase I (NESC-RP-12-00776/NASA TM-2014-218163, (1)) of this assessment explored spin 

forming the single-piece forward pressure vessel bulkhead from aluminum-lithium (Al-Li) 2195.

The Orion MPCV Program and prime contractor Lockheed Martin (LM) recently made two 

decisions relative to the NASA Engineering and Safety Center (NESC) Phase I work scope: 

(1) LM selected the spin forming process to manufacture a single-piece aft bulkhead for the 

Orion MPCV, and (2) the aft bulkhead will be manufactured from Al 2219 (2).

Based on the Orion MPCV Program’s emphasis related to the spin forming process, the NESC 

was asked to conduct a Phase II assessment to assist in the manufacture of the aft bulkhead and 

to conduct a feasibility study into spin forming the cone section of the Orion MPCV. The Phase 

II assessment (NESC-RP-13-00884/NASA TP-2015-218674), (3)) produced and characterized a 

full scale Al 2219-T62 spin formed aft bulkhead as a pathfinder for the manufacture of the Orion 

MPCV aft bulkhead. During characterization of the aft bulkhead questions arose regarding stress 

corrosion cracking (SCC) results and the lack of comparable data in the literature; uniformity of 

the microstructure; and the impact on properties of the modified heat treatment practice used 

during production. Based on these questions, a supplementary study was initiated and approved 

by the NESC. This supplemental report, which is an addendum to the Phase II Spin Formed Aft 

Bulkhead final report (3), focuses on the results of supplemental mechanical property tests,

which attempted to resolve some of these questions.

The Phase II assessment plan was approved on July 18, 2013. Dr. Robert Piascik, NASA 

Technical Fellow for Materials at the Langley Research Center (LaRC), was selected to lead this 

assessment. The supplemental testing activity was proposed to and approved by the NESC 

Review Board on November 20, 2014, during the report out on the Phase II assessment.

The primary stakeholders for this assessment were the NASA Orion MPCV Program and prime 

contractor Lockheed Martin. Additional benefactors are commercial launch providers 

developing crew module concepts and all users of Al 2219-T6 spin formed products.
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2.0 Executive Summary

The objective of the Phase II Spin Formed Aft Bulkhead study (3) was to assist the Orion MultiPurpose Crew Vehicle (MPCV) Program in developing a spin forming fabrication process for the 

manufacture of the aft bulkhead of the pressure vessel. The spin forming process will enable a 

single piece aluminum (Al) 2219 aft bulkhead resulting in the elimination of the current multiple 

piece welded construction, simplified fabrication, and an enhanced design that will reduce 

vehicle weight by eliminating welds. The Phase II assessment produced and characterized a full 

scale Al 2219-T62 spin formed aft bulkhead as a pathfinder for the manufacture of the Orion 

MPCV aft bulkhead. During characterization of the pathfinder aft bulkhead some questions 

arose regarding stress corrosion cracking (SCC) results, uniformity of the microstructure, and the 

impact on properties of the modified heat treatment practice used by the spin forming vendor, 

Spincraft. It was also noted that limited data was available in handbooks and open literature for 

Al 2219-T6 material. This supplemental report1, which is an addendum to the Phase II Spin 

Formed Aft Bulkhead final report (3), focuses on the results of supplemental mechanical 

property tests, which attempted to resolve some of these questions.

Material from the pathfinder aft bulkhead was provided for additional SCC and tensile testing. 

In addition, plate remnants from the spin forming blank were heat treated using standard and 

modified practices, and material was provided for SCC, tensile, and fracture toughness testing. 

The difference in the heat treatment practices is the post-solutionizing quench media; water is 

used in the standard practice and a water/glycol mixture in the modified practice. The 

water/glycol mixture results in a slower quench rate, which helps control residual stress and

distortion in large parts, but which may alter material properties. Also, material from an Al 

2219-T62 spin formed dome produced by Spincraft for NASA’s Cryogenic Propellant Storage

and Transfer Program (CPST) Program (4), (5) was provided for SCC and fracture toughness 

testing to represent a comparable product.

The Phase II study SCC test results indicated lower stress corrosion resistance than has been 

previously documented for Al 2219-T6 material, raising a question about whether the spin 

forming process compromises SCC resistance. During SCC testing of the aft bulkhead material 

the only failures that occurred were for specimens tested in the short transverse (ST) orientation, 

and in particular, one specimen failed at a low enough exposure stress level that, if substantiated, 

would indicate a need to limit the service stress levels for the aft bulkhead. This result prompted 

a review of the SCC test standard used for the aft bulkhead, MSFC-STD-3029 (6), compared 

with American Society for Testing and Materials (ASTM) test methods and practices for SCC 

evaluation (7) (8) (9), a review of the test procedures, and a review of available literature. 

Supplemental testing was devised to retest the material to determine whether the one low test 

result was repeatable and representative of the material, and to examine SCC resistance at 

additional locations within the aft bulkhead.

No specimen failures occurred during the supplemental SCC tests of the aft bulkhead and postexposure residual strength levels were above minimum required values. However, post-exposure 

 

1 Published as NASA-TM-2015-218797
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metallurgical analysis revealed SCC in several specimens. All specimens exhibited pitting 

corrosion and most exhibited intergranular attack. This finding prompted a review of all 

specimens from the Phase II testing, some of which failed during exposure, to more definitively 

identify corrosion morphology and the occurrence of SCC. SCC was confirmed in all specimens 

that failed during the Phase II testing. SCC was not observed in any specimens that survived 

exposure.

A review of test procedures did not provide an explanation for the difference in results between 

the Phase II and supplemental SCC tests. Numerous factors can affect the outcome of SCC tests, 

such as solution chemistry, relative humidity, and applied stress level. The only documented 

experimental difference was in the condition of the stressing frames. For the Phase II tests the 

frames were anodized for protection of the frames and to prevent galvanic corrosion. In the 

supplemental tests a traditional polymer based coating was applied to the frames. It is uncertain 

whether this created sufficiently different environmental conditions to explain the varied test 

results. The difference may also be a reflection of inherent material variability.

No failures occurred during supplemental testing of the standard or modified plates. However, 

the standard plate exhibited higher post-exposure residual strength ratios. Post-exposure 

metallurgical evaluation showed evidence of SCC only in the modified plate, suggesting that the 

slower quench rate associated with modified heat treatment reduces stress corrosion resistance. 

No specimen failures occurred during supplemental tests of the CPST dome material; however,

residual strength levels were lower than for the aft bulkhead.

The grain size in the aft bulkhead varied with distance from the pole and through the thickness of 

the plate, with larger grain sizes noted in regions of greater deformation, typically biased toward 

the outer mold line (OML) and toward the rim. The variation in grain size stems from the 

complex and non-uniform deformation induced during spin forming as the plate is shaped over 

the mandrel. Phase II tensile property testing sampled only the mid-thickness position, which 

was the most uniform. Supplemental tensile tests were defined to examine the effect of throughthickness variations in grain size on material strength and evaluate the effect of the postsolutionizing quench rate. Supplemental test results confirmed that neither the grain size 

variations nor the quench rate adversely impacted tensile properties. Tensile strengths were 

uniform through the thickness of the aft bulkhead and were comparable to the standard and 

modified plates.

Supplemental fracture toughness testing was performed to determine whether the quench rate 

impacted toughness and how the aft bulkhead compared with the CPST dome. Fracture 

toughness behavior of the standard and modified plates, the CPST dome material, and the aft 

bulkhead were essentially equivalent, with acceptable toughness levels and demonstrated stable 

tearing.

The supplemental test results combined with the Phase II tests results for the Al 2219-T62 aft 

bulkhead build confidence that spin forming has no identified barriers for fabrication of the

Orion aft bulkhead. Tensile and fracture toughness values were uniform with orientation and 

location within the aft bulkhead and were comparable to Al 2219-T6 wrought products. SCC
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resistance was lower than previously documented for Al 2219-T6 wrought products, likely 

related to the slower quench rate associated with modified heat treatment. Evidence of SCC was 

observed in material from the aft bulkhead, CPST dome, and modified plate, based on failure 

during exposure, residual strength reduction, or occurrence of SCC. These materials all received 

the modified heat treatment, indicating that the reduced SCC resistance was likely due to the 

modified heat treatment and not the spin forming process. SCC failures occurred in all three 

products for material exposed at the minimum exposure stress level used in this study, 50% of 

the MMPDS ST YS for plate, indicating that the threshold stress level for SCC may be lower.

Recommendations from this study to the Orion MPCV Program include performing SCC testing

to identify the threshold stress level for SCC to establish maximum allowable service stress 

levels. Testing is recommended on multiple spin formed Al 2219-T6 aft bulkhead articles 

produced during initial serial production and should sample multiple material lots. The SCC test 

results from this study are for one spin formed aft bulkhead, consequently they represent one 

material lot and one fabricated production article. In addition, evidence of SCC was observed 

for all non-zero exposure stress levels indicating that the SCC threshold is below the minimum 

stress level used in this study. Future testing should include stress levels lower than those used 

in this study in order to identify a threshold stress level for SCC for Al 2219-T6 spin formed 

material. It is also recommended that heat treatment studies be performed to determine whether 

a faster quench rate can be achieved that improves SCC resistance without compromising 

residual stress and distortion control. SCC results from this study and any additional 

programmatic testing may be used to develop a Materials Usage Agreement (MUA).
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3.0 Background

3.1 Orion MPCV Aft Bulkhead

The primary structural elements of the Orion MPCV pressure vessel, shown in Figure 1, consist 

of a single piece forged barrel, a multi-piece cone section, a single piece forward bulkhead, a 

single piece forward tunnel, integrated forward gussets, and a multi-piece welded aft bulkhead. 

The aft bulkhead configuration shown is assembled from Al-Li 2195 using one circular and two 

latitudinal welds. The Orion MPCV Program and LM changed to a single-piece aft bulkhead 

design using spin form fabrication and Al 2219 (2). The motivation for the change in fabrication 

method was to reduce structural weight by eliminating welds and associated weld lands. The 

change in material was driven by the single-piece aft bulkhead design, which requires a preform 

thicker than 2 inches (the current thickness limit for Al-Li 2195) to accommodate all design 

features. Figure 1 shows the MPCV design at the start of this study and that was used for 

Exploration Flight Test 1 (EFT-1). In addition to the design changes for the aft bulkhead, the 

cone section was redesigned to reduce the assembly from twelve to three pieces. These design 

changes were implemented for Exploration Mission (EM-1) flight article (2).
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Figure 1. Orion MPCV configuration (Note: dimensions in inches).

3.2 Spin Formed Aft-Bulkhead Pathfinder

The objective of the Phase II project was to spin form an aft bulkhead test article to assess the 

mechanical properties (e.g., tensile, fracture toughness, and SCC). The study used spin forming 

to produce a pathfinder article from a single plate (1.5- to 2.5-inch thick) with a curvature similar 

to the Orion aft bulkhead curvature. For a 100-inch diameter (1.5-inch thick) spin forming 

blank, preliminary calculations show that a 207.5-inch curvature radius adequately simulated

(scaled to) the larger Orion design. Upon completion of spin forming and heat treatment, the 

pathfinder was sectioned to supply spin formed material to support metallurgical analysis and 

mechanical property testing, which included a grain size evaluation, tensile and fracture 

toughness testing, and SCC characterization. Selected pathfinder regions (acreage and thickness 

locations) were tested to assess uniformity. Analysis of the Phase II test results raised questions 

about whether the spin forming process adversely impacts SCC resistance, whether post-spin 

forming heat treatment is detrimental to strength and fracture toughness, and whether observed 

grain size variations affect properties. Supplemental SCC, tensile, and fracture toughness tests 

were defined to address some of these questions.
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4.0 Supplemental Mechanical Test Program

4.1 Objectives

During the execution of the Phase II mechanical property testing and analysis of the aft 

bulkhead, several issues arose, which the NESC team attempted to address to assist the LM

MPCV design team in their first article test program. In addition, several findings were observed 

that the team wished to further analyze to clarify the results. The team proposed a limited 

number of supplemental SCC, tensile, and fracture toughness tests, which were accepted by the 

NESC advisory team. Further details on these supplemental tests are addressed in Sections 5

through 7. Due to project milestones and schedule, the results from these supplemental tests

were not included in the Phase II Spin Formed Aft Bulkhead final report (3), but are presented 

here as an addendum.

5.0 Supplemental Stress Corrosion Tests

5.1 Background

During SCC testing of the aft bulkhead material the only failures that occurred were for 

specimens tested in the ST orientation. Specimen failures occurred in three of the four coupon 

blank locations tested at exposure stress levels of 75% of the material yield strength (YS). One 

specimen from the M10 coupon blank failed at an exposure stress of 50% of the material YS. 

These results raised questions about the SCC resistance of the aft bulkhead material in 

comparison with other wrought products. The failure at 50% YS exposure stress raised concern 

because of the impact on SCC resistance table ratings and threshold stress level, which is used, in 

part, to identify the maximum allowable service stress. A key question guiding the supplemental 

testing was whether this failure was repeatable.

Additional questions arose when making comparisons with handbook and published data in an 

attempt to interpret the SCC results. A complication that impeded interpreting the results was 

that there is limited SCC data available for Al 2219-T6 products. In addition, several questions 

arose regarding the available data for Al 2219-T8 products, both in terms of SCC test practices 

and the available data to substantiate published ratings. In particular, what should be the 

appropriate basis for the applied stress level? There are a number of applicable standards for 

SCC testing that use different applied stress levels, exposure periods, and criterion ratings (7),

(8), (9), (10). Most standards establish exposure stress levels based on the Metallic Materials 

Properties Development and Standardization (MMPDS) Handbook (11) allowable YS, but the 

Marshall Space Flight Center (MSFC) SCC test standard, MSFC-STD-3029 (6), which was used 

for the aft bulkhead testing, uses exposure stress levels based on the measured YS for the product 

being tested. The MMPDS design allowable material properties are generally lower due to the 

statistical analysis, consequently using the actual material properties results in higher exposure 

stress levels and a more severe test than the handbook data being used for comparison. Also, the 

measured YS of the aft bulkhead was higher in the ST orientation than the longitudinal (L) and 

long transverse (LT) orientations so the ST specimens experienced the highest exposure stress 
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levels. No design values exist for spin formed products so testing according to standards that 

base exposure stress levels on MMPDS requires using values for plate. MMPDS provides 

design allowables for plate in the L and LT orientations only so these values are used in testing 

where exposure stress levels are based on MMPDS and for all orientations. Specimens exposed 

at stress levels of 50 and 75% of measured ST YS for the aft bulkhead were equivalent to 

exposures at 60 and 90% of the MMPDS YS values for plate, illustrating the more aggressive 

test conditions experienced in the current study as compared to the literature reference data.

To address the issue of exposure stress level, additional SCC tests were conducted on coupon 

blank M10 using applied stress levels based on MMPDS A-basis design allowables for Al 2219-

T62 plate. To further verify and interpret the SCC results, additional tests were also conducted 

on coupon blanks at other locations within the aft bulkhead, other spin formed products, and 

wrought plate materials. Table 1 lists the SCC test matrix and the questions being addressed. 

These supplemental SCC tests consisted of 30-day alternate immersion in a 3.5% sodium 

chloride (NaCl) environment and only evaluated the ST orientation since this is the grain 

orientation most susceptible to SCC and the orientation of the failures in question. The goal of 

the supplemental SCC test matrix was to ensure confidence in the Phase II data that had been 

generated, and characterize the aft bulkhead component as best as possible.

Additional general questions arose regarding how the SCC ratings in published literature were 

established. What type of SCC data will the Orion MPCV Program use to base their design? 

What is the threshold stress level for SCC for the aft bulkhead? Due to limited funds and 

schedule, not all of these questions can be addressed in the scope of this supplemental SCC test 

program.
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Table 1. Supplemental SCC test matrix and questions being addressed.

Aft bulkhead M10 ST YS = 44.4 ksi

MMPDS LT YS = 36 ksi

The first priority of these supplemental SCC tests was to repeat the tests on coupon blank M10 to 

determine whether the one specimen failure that occurred at 50% YS applied stress level was 

repeatable. The concern was that if this result was repeatable it would indicate a threshold stress 

level for SCC low enough that service stress levels for the aft bulkhead would be lower than 

acceptable for the current design. These first priority tests repeated the tests for material from 

coupon blank M10 with the applied stress levels based on measured YS values established from 

baseline tensile test data for the coupon blank to determine if the results were repeatable. 

Additional tests from this coupon blank were also conducted at applied stress levels based on 

MMPDS design values to determine whether or not the material would pass at the resulting 

lower exposure stress levels.

Material 

Source

Location / 

Heat 

Treatment

Applied Stress 

Level,

% YS

Applied Stress 

Level, 

ksi

Orient.

# of 

Specimens Question Addressed

50 based on M10 avg. ST YS 22.2 ST 3

75 based on M10 avg. ST YS 33.3 ST 3

50 based on MMPDS LT YS 1 8 ST 3

75 based on MMPDS LT YS 2 7 ST 3

0 0 ST 3

50 based on MMPDS LT YS 1 8 ST 3

75 based on MMPDS LT YS 2 7 ST 3

0 0 ST 3

50 based on MMPDS LT YS 1 8 ST 3

75 based on MMPDS LT YS 2 7 ST 3

0 0 ST 3

50 based on MMPDS LT YS 1 8 ST 3

75 based on MMPDS LT YS 2 7 ST 3

0 0 ST 3 4. Does spin forming alter the SCC resistance of plate? 

50 based on MMPDS LT YS 1 8 ST 3

75 based on MMPDS LT YS 2 7 ST 3

0 0 ST 3

50 based on MMPDS LT YS 1 8 ST 3

75 based on MMPDS LT YS 2 7 ST 3

0 0 ST 3

50 based on MMPDS LT YS 1 8 ST 3

75 based on MMPDS LT YS 2 7 ST 3

0 0 ST 3

50 based on MMPDS LT YS 1 8 ST 3

75 based on MMPDS LT YS 2 7 ST 3

Plate

CPST Spin 

Formed 

Dome

Rim

2. Does material pass at exposure stress levels based on 

MMPDS design properties rather than actual material 

yield strength?

Aft 

Bulkhead

J2 3. What is the SCC behavior in other coupon blank 

locations along a different meridian line?

Aft 

Bulkhead

J1

1. Is failure at 50% exposure stress repeatable? Was 

this data point an outlier or it is representative of this 

Aft aft bulkhead location?

Bulkhead M10

6. How does the aft bulkhead compare with other spin 

formed domes?

Aft 

Bulkhead

J3

Modified

Standard

CPST Spin 

Formed 

Dome

Pole

Plate

5. Does the quench rate affect SCC resistance of plate?
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The second priority tests were in response to requests from the Orion MPCV Program to better 

understand the SCC resistance throughout the aft bulkhead. The SCC specimens from coupon 

blanks J1, J2, and J3 designated for seacoast exposure SCC testing were re-directed to alternate 

immersion SCC testing to examine more locations in the aft bulkhead. Seacoast exposure SCC 

testing was proposed in the original test program because of concerns that the alternate 

immersion test results could become obscured because of general corrosion in the form of 

pitting. Seacoast exposure SCC testing, which is performed in a less aggressive outdoor 

environment and requires longer test durations than the standard accelerated corrosion tests 

performed in a laboratory, is used as a complementary test to alternate immersion. Based on the 

Phase II alternate immersion SCC test results, the NESC team decided that obtaining additional 

data through the accelerated laboratory test was a higher priority. These seacoast exposure SCC 

test specimens had been machined and loaded in the stressing frames; the only change required 

was to change the applied stress levels and install them in the alternate immersion test apparatus. 

For these tests, the applied stress level was based upon MMPDS A-basis design properties for 

plate. These specimens offered a ready opportunity to generate the additional data while staying 

within the prescribed budget and schedule.

The third priority tests were in response to the limited SCC data for Al 2219-T6 products and the 

unknown effects of material processing on SCC performance. The SCC resistance of the aft 

bulkhead was lower than that reported for Al 2219-T6 wrought products. These tests attempted 

to determine if this was inherent to this plate lot or due to the spin forming process. It is not 

possible to isolate the effects of spin forming processing alone because these components 

typically receive a post-fabrication heat treatment. However, to evaluate the impact of the 

modified heat treatment used on the aft bulkhead, tests were performed on remnant F temper 

plate from the aft bulkhead spin forming blank (i.e., no spin forming deformation) processed to 

the T62 temper using both standard and modified heat treat procedures as outlined in Section 6.3. 

The primary difference between the two heat treat processes was the post-solution heat treatment 

quench media and the associated cooling rates. The standard heat treatment uses a water quench,

which results in a faster quench rate than the water/glycol quench mixture used for the modified 

heat treatment. Remnant spin formed Al 2219-T62 dome material from the CPST program (5)

was tested to provide data for a comparable product form. For these tests on processed plate and 

the CPST dome material, the applied stress levels were based upon MMPDS A-basis design 

properties for plate since there are no design values for Al 2219-T6 spin formed products. For 

consistency plate values were used in testing of the CPST dome rather than measured values 

from the dome.

5.2 Test Procedures

The location of aft bulkhead coupon blanks tested in the Phase II and supplemental tests are 

shown in the aft bulkhead cut plan (Figure 2) and coupon blank matrix (Table 2). Coupon blanks 

M7, M8, M9, and M10 were evaluated in the Phase II testing while coupon blanks M10, J1, J2, 

and J3 were evaluated in the supplemental testing. The J1 – J3 coupon blanks were originally 

designated for seacoast exposure SCC testing, but were re-directed to the supplemental SCC tests 
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program. As such these specimens had been machined and loaded in the test frames. For each 

coupon blank, MSFC received 9 specimens pre-assembled and loaded in the test fixture and 1 

extra specimen. Since the loads applied did not correspond to the loads in the supplemental test 

plan, these specimens were unloaded and reloaded to the appropriate exposure stress. The 9 

reloaded specimens from each coupon blank were used for the supplemental SCC testing while 

the one extra specimen was used for baseline tensile testing. An additional 18 specimens were 

machined in the ST orientation from coupon blank M10, 9 each for testing at exposure stress 

levels based on MMPDS and the measured YS.

Figure 2. Diagram showing coupon blank locations for SCC tests of the spin formed aft bulkhead.
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Table 2. SCC coupon blank locations and orientations.

M7 14 12 90 12

M8 14 12 90 35-1/8

M9 14 12 90 56-1/4

M10 14 12 190 35-5/8

J1 14 12 180 12

J2 14 12 170 35-5/8

J3 14 12 180 55-5/8

Coupon 

Blank

Coupon Blank Size Coupon Center Point

Longitudinal 

Dimension, 

in

Transverse 

Dimension, 

in

Meridian 

Angle, 

degrees

Arc Length 

from CL, 

in.

Additional test material consisted of remnant Al 2219-F wrought plate from the aft bulkhead spin 

forming blank heat treated to the T62 temper using two heat treat variants as described in Section 

6.3 and remnant material from the pole and rim regions of a spin formed Al 2219-T62 CPST 

dome. For the plate and CPST dome material, 12 ST tension specimens were machined, oriented 

with respect to the original plate rolling direction. Three specimens from each set of 12 were 

used to obtain baseline tensile data to assist in characterizing the effects of stress and exposure 

on SCC; the remaining 9 were used for SCC testing.

All specimens for the supplemental SCC tests were machined in the ST orientation per the 

ASTM E8 (12) small-size round tension test specimen design shown in Figure 3. Baseline 

tensile tests were conducted for each lot of material using the same specimen design to assist in 

characterizing the effects of stress and exposure on SCC.
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NOTES:

1. Tolerances: ± 0.005 inch, except otherwise specified.

2. Surface finish: 16√ for the reduced section, 32√ for the rest.

3. Thread dimensions must be as specified. Measurement by fabricator is mandatory. 

4. No undercutting of radii permitted.

5. Gage section to be concentric with axis within 0.002 inch TIR and parallel.

6. No file marks or nicks permitted within gage section.

7. Center-drilling permissible (both ends). May use a #1 size max. Chamfer diameter not to exceed 0.100 in.

8. Break sharp edges.

9. The reduced section may have a gradual taper from the ends toward the center with the ends not more than 

0.005 inch larger diameter than the center.

Figure 3. Round sub-size tensile specimen design used for SCC testing (12).

The SCC testing and analysis were performed in accordance with MSFC-STD-3029 (6). The 

SCC specimens were tested using the direct tension loading method as described in ASTM G49 

(9). Constant strain stressing frames were used to determine the applied stress levels from 

measurement of the strain where average linear stress () is proportional to the average linear 

strain (), / = E, where the constant E is the modulus of elasticity. As per the test matrix 

shown in Table 3; three replicate SCC specimens from each group were loaded in tension to 

50 and 75% of the MMPDS A-basis LT YS (36 ksi), which correspond to an applied stress of 

18 and 27 ksi, respectively. Additional specimens from coupon blank M10 were stressed to 

50 and 75% of the average YS value (44.41 ksi) obtained from baseline tensile tests of the 

coupon blank M10, which correspond to an applied stress of 22.2 and 33.3 ksi, respectively. 

These stress levels correspond to 62% and 93% of the MMPDS A-basis YS, which illustrates the 

discrepancy between test methods and potential difficulties in comparing results. In the case of 

the aft bulkhead, an exposure stress of 75% of the measured YS equates to more than 90% of the 

MMPDS value. More importantly, the 50% exposure stress based on measured YS is 62% of the 
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MMPDS value. Control specimens with no applied stress were also tested in all groups for 

comparison.

All specimens were subjected to alternate immersion exposure in a 3.5% NaCl solution for a test 

duration of 30 days per ASTM G44 (7). Three replicate specimens were tested for each stress 

level and test group as per the SCC test matrices shown in Table 3.

Table 3. Supplemental SCC test matrix.

(1) Average UTS and YS obtained from baseline tensile tests of unexposed specimens

(2) MMPDS A-basis LT YS = 36 ksi

Specimens were considered to have failed by SCC if the specimens fractured during exposure, 

the residual tensile strength was below the specified threshold, or the specimens exhibited 

cracking during post-exposure visual and metallographic examination.

If no specimens fractured during exposure for a given test condition, then one specimen from the 

set was subjected to metallographic examination while the remaining two specimens were loaded 

to failure in tension to determine residual tensile strength. Two measures were used to evaluate 

Stress Level Stress Level Stress Level Stress Level 

% YS ksi % YS ksi

0 0 0 0

50 18 50 22.2

75 27 75 33.3

0 0 ----- -----

50 18 ----- -----

75 27 ----- -----

0 0 ----- -----

50 18 ----- -----

75 27 ----- -----

0 0 ----- -----

50 18 ----- -----

75 27 ----- -----

0 0 ----- -----

50 18 ----- -----

75 27 ----- -----

0 0 ----- -----

50 18 ----- -----

75 27 ----- -----

0 0 ----- -----

50 18 ----- -----

75 27 ----- -----

0 0 ----- -----

50 18 ----- -----

75 27 ----- -----

MMPDS LT YS(2) Actual ST YS

Material 

Source

Location / 

Heat Treat Orient.

 UTS(1) 

ksi

 YS(1) 

ksi

Aft 

Bulkhead

J2 

Membrane

Aft 

Bulkhead

M10 

Membrane

ST 57.04 43.11

Aft 

Bulkhead

J1 

Pole ST 55.09 41.88

56.30 40.18

Aft 

Bulkhead

J3 

Rim ST 58.05 43.81

Plate Standard ST 62.07 43.50

ST 59.65 44.41

CPST 

Dome Rim ST 57.56 37.33

Plate Modified ST 59.15 37.19

CPST 

Dome Pole ST
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the residual tensile strength of the surviving specimens: the percent tensile strength retained, 

which compares the residual tensile strength of the exposed specimens to the average tensile 

strength of unexposed specimens; and the residual strength ratio, which compares the residual 

tensile strength of specimens exposed with and without an applied stress. These criteria enable 

quantification of the effects of general corrosion thus reducing the experimental interferences 

associated with the more subjective visual examination of specimens (13).

The percent tensile strength retained provides a measure of the residual load carrying ability of 

the exposed specimens compared to unexposed specimens, and is an indication of the reduction 

in specimen cross-sectional area, not a change in strength of the material. Loss in cross-sectional 

area can be due to general corrosion, pitting, and/or stress corrosion. Metallurgical examination 

is required to confirm the type of corrosion. For the specimens tested with an applied stress, the 

reduction in tensile strength is due to the combined effect of stress and the corrosive 

environment. For the specimens tested with no applied stress the reduction in tensile strength is 

due to the effect of the corrosive environment only. The percent tensile strength retained for 

each exposed specimen was calculated as:

Percent Tensile Strength Retained = (UTSf/UTSi) x 100

where:

UTSf = Residual strength of the exposed specimen (failure load / original specimen crosssectional area)

UTSi = Average ultimate tensile strength for the unexposed specimens.

The residual strength ratio for each specimen that was exposed with an applied stress was 

calculated as:

Residual Strength Ratio = UTSs/UTSo

where:

UTSs = Residual strength of stressed and exposed specimen

UTSo = Averaged residual strength of non-stressed and exposed specimens

The residual strength ratio provides a more direct indication of the effect of applied stress during 

exposure and therefore a method to separate the effects of general corrosion and pitting from 

stress corrosion. The UTSs and UTSo are calculated based on original specimen cross-sectional 

area, and provide an indication of the loss in area due to stress corrosion and general corrosion, 

respectively. For this study, specimens with residual strength ratios of less than 0.75 were 

considered failures. This threshold for the residual strength ratio was based on heritage SCC test 

data generated at MSFC.
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Specimens that fractured were sectioned and examined metallographically to verify that SCC 

was the cause of the fracture. If no failures occurred for a set of replicate specimens then one 

was examined to determine whether SCC occurred. Guidelines that were used to identify SCC in 

Al alloys include (1) cracks that follow an intergranular path or mixed intergranular -

transgranular path were considered as SCC; (2) exclusively transgranular cracks that initiated at 

corrosion pits were not considered as SCC; and (3) intergranular cracks that were no deeper than 

the width of localized areas of intergranular corrosion were not considered as SCC (14). In this 

study additional criteria that guided classification of an observed crack to be due to stress 

corrosion were that the crack length extended beyond the depth of pitting or intergranular attack, 

the crack branched, and / or that the crack initiated on the specimen surface.

One goal of MSFC-STD-3029 is to establish ratings for SCC resistance. The table rating 

requirements are shown below for reference. It should be noted that while table ratings are

important, for design purposes a threshold stress level for SCC must be identified to establish 

maximum allowable service stress levels. Also, the collective data from the Phase II and 

supplemental SCC tests are not sufficient to define a threshold value or establish table ratings. 

Both the Phase II and supplemental testing was performed on the same Al 2219-T6 spin formed 

aft bulkhead; consequently, this represents one material lot and one single fabrication article. 

There are no standards or test guides that define the number of tests required to establish a 

threshold stress level for SCC and the requirements will be unique for a specific combination of 

product form, material, and anticipated service conditions.

Table I Requirements

Alloys, tempers, and weldments in Table I are considered highly resistant to SCC in 3.5% NaCl 

alternate immersion or 5% salt spray. An alloy or weldment can be added to this table if no 

stress corrosion failures occur on specimens stressed to 75% of the YS within 30 days of

exposure.

Table II Requirements

Alloys, tempers, and weldments in Table II are considered moderately resistant to SCC in 3.5%

NaCl alternate immersion or 5% salt spray. An alloy or weldment is added to this table if no 

stress corrosion failures occur on specimens stressed to 50% of the YS within 30 days of 

exposure.

Table III Requirements

Alloys, tempers, and weldments in Table III are considered to have low resistance to SCC in 

3.5% NaCl alternate immersion or 5% salt spray. They are placed in this table if stress corrosion 

failures occur on specimens stressed to 50% of the YS within 30 days of exposure.
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5.3 Stress Corrosion Results

The supplemental SCC tests results for the 30-day alternate immersion exposure are presented in 

Table 4. No SCC failures occurred in the ST specimens during the 30-day alternate immersion 

exposure for specimens from the aft bulkhead, standard or modified plates, or the CPST dome. 

Results from the Phase II SCC tests of the aft bulkhead are provided in Table 5 for comparison 

and illustrate that specimen failures occurred in three of the four coupon blank locations at 75% 

YS exposure stress, and in coupon blank M10 at 50% YS exposure stress.

For the supplemental tests, one of the three replicate specimens from each test group was 

metallographically examined. The remaining two replicate specimens from each test group were 

tensile tested to determine residual tensile strength remaining after exposure with the results used 

to determine residual tensile strength retained and the residual strength ratio. The individual and 

average tensile strengths of the supplemental materials obtained from baseline tensile tests are 

shown in Table 6 and were used to determine residual tensile strength for the surviving SCC 

specimens.

Residual tensile strength results for the supplemental tests are shown in Table 7 for specimens 

exposed with an applied stress and in Table 8 for specimens exposed without applied stress. For 

the specimens from the aft bulkhead which were exposed with an applied stress the percent

tensile strength retained ranged from 51 to 73% compared to a range of 40 to 69% for specimens 

exposed without an applied stress. The highest percentages were for the specimens from coupon 

blank J3, obtained from the rim area of the bulkhead while the lowest were for specimens from 

coupon blank J1 near the pole. A graphical representation of the overall reduction in residual 

strength for the exposed specimens is presented in Figure 4. The baseline stress-strain curves for 

specimens from all material lots prior to exposure are shown in Figure 4(a) while Figure 4(b) 

shows the stress-strain curves for the exposed specimens. The curves are not identified and are 

presented to show the reduction in residual strength resulting from the exposure. In comparison, 

as shown in Table 9, for the Phase II tests the percent tensile strength retained for the specimens 

exposed with an applied stress ranged from 4 to 55% compared to the specimens tested without 

an applied stress, which ranged from 32 to 49%. The lowest values were for the 50% YS 

exposure stress specimens from coupon blank M10 (membrane) and the highest from coupon 

blank M9 (rim). For the CPST dome material percent tensile strength retained values ranged 

from 34 to 59 with the highest values from the rim. Based on the percent tensile strength 

retained from the Phase II and supplemental testing of the aft bulkhead combined with the 

limited testing of the CPST dome, there is some variability in SCC resistance throughout the aft 

bulkhead, and potentially in similar spin formed components, with regions near the rim having 

greater resistance.

The percent tensile strength retained for specimens obtained from the standard and modified 

plates were similar, indicating that there was no significant effect of the heat treatments on SCC 

resistance. Percent tensile strength retained values ranged from 52 to 63 for the modified heat 

treat and from 45 to 57 for the standard heat treat.
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The residual strength ratios shown in Table 7 and Table 8 were used in this study as an additional 

failure criteria, with a value of 0.75 defined as the threshold for passing. All of the specimens 

from the supplemental tests of the aft bulkhead passed as did all of the Phase II tests, with the 

exception of the 50% YS exposure stress level (specimens # 153 and 154) from the Phase II tests 

of coupon blank M10. All specimens from the standard and modified plates passed this test. 

Five of the eight specimens from the CPST dome passed. Two of the specimens that failed were 

obtained from the pole, one with a ratio of 0.58 had been exposed at 50% of LT MMPDS YS 

(44.8% of measured ST YS) and one with a ratio of 0.73 had been exposed at 75% of LT 

MMPDS YS (67.2% of measured ST YS). The third specimen that failed the residual strength 

ratio test with a ratio of 0.73 was from the CPST dome rim area and had been exposed at 75% of 

the LT MMPDS YS (72.3% of measured ST YS). The average ratios for all materials evaluated 

in the supplemental tests (from best to worst) were 1.11 for M10, 1.10 for standard plate, 1.04 for 

J2, 0.99 for J3, 0.97 for J1, 0.89 for modified plate, 0.87 for CPST rim, and 0.74 for CPST pole. 

While not a rigorous comparison, the residual strength ratios indicate that the aft bulkhead had 

slightly better SCC resistance that the CPST dome and the standard heat treatment was slightly 

more resistant than the modified heat treatment.

Metallographic examination was used to evaluate whether SCC was the cause of specimen 

failures during exposure and to determine whether SCC occurred in specimens that survived 

exposure. Photomicrographs of one of the three replicate specimens from each supplemental test 

group are shown in Figure 5 through Figure 12. For each sample set, a low magnification view 

of the exposed specimen is shown with low and high magnification photomicrographs of the 

polished cross-section in the etched and unetched conditions. The presence or absence of SCC 

was noted for each specimen and primary SCC features were encircled. Pitting was apparent on 

all specimens, however, the effect was not sufficiently detrimental to cause failures within the 

30-day exposure period. Additionally, intergranular corrosion was present in many samples, 

primarily from the aft bulkhead and modified plate. According to electrochemical theory, Al

alloys that contain appreciable amounts of soluble alloying elements such as Cu, Mg, Si, and Zn

are susceptible to grain boundary corrosion, including both intergranular and stress corrosion

(15). Specimen J1-8, Figure 6(a), shows a typical example of intergranular corrosion observed 

in these samples. SCC was observed in samples from the aft bulkhead, CPST dome, and 

modified plate as noted in the micrographs (encircled in red); however, the extent was not 

sufficiently detrimental to cause failure within the 30 day exposure period. SCC was not 

observed in the standard plate. From aft bulkhead coupon blank M10, specimens M10-6

(Figure 5(b), 50% YS (measured)); M10-15 (Figure 5(c), 50% YS (MMPDS)); M10-9 

(Figure 5(d), 75% YS (measured)); and M10-16 (Figure 5(e), 75% YS (MMPDS)) showed SCC. 

Specimens J1-2 from coupon blank J1 at 75% YS (Figure 6(c)) and specimen J2-5 from coupon 

blank J2 at 50% YS (Figure 7(b)) showed evidence of SCC. For the case of other product forms, 

specimen GQ-4 (Figure 10(b)) from the modified plate, and specimens CP-P9 (Figure 11(c)) and 

CP-R7 (Figure 12(c)) from the CPST dome showed evidence of SCC.

The observation of SCC in the supplemental test specimens that survived exposure prompted a 

review of all specimens from the Phase II testing at stress levels and exposure periods similar to 
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those used in the supplemental testing. Photomicrographs of the LT and ST specimens from the 

Phase II testing are provided in Appendix A (Figure A-1 - Figure A-4; Section 11.1) and 

Appendix B (Figure B-1 - Figure B-4; Section 11.2), respectively. The LT specimens exhibited 

pitting and intergranular attack, but SCC was not observed. The ST specimens exhibited pitting 

and intergranular attack and SCC was confirmed in nearly all samples that failed during 

exposure. SCC was not observed in any specimens that survived exposure.

A summary compilation of the supplemental tests results for each individual specimen is shown 

in Appendix C, Table C-1. This table includes the test conditions, pass/fail, residual strength, 

and metallographic examination results cross-referenced with the location in the report of the 

relevant photomicrograph figure number. A similar summary compilation for the Phase II test 

results is shown in Appendix D, Table D-1, for the LT orientation and Table D-2 for the ST 

orientation.

Also noted in the supplemental test specimens was that the grain size in samples from the aft 

bulkhead coupon blanks (Figures 5-8) and the standard and modified plates (Figures 9 and 10) 

were similar to one another, but smaller than in samples from the CPST dome material

(Figures 11 and 12). The difference in grain size was not quantified, but may have contributed to 

a greater extent of pitting and the lower residual strength ratios in the CPST dome material.

A review of test procedures did not provide an explanation for the difference in the occurrence of 

failures during exposure for the Phase II and supplemental SCC tests. Numerous factors can 

affect the outcome of SCC tests, such as solution chemistry, relative humidity, and applied stress 

level. The only documented experimental difference was in the condition of the stressing 

frames, which were fabricated from Al 6061. For the Phase II tests the frames were anodized for 

protection of the frames and to minimize any galvanic effects on the Al 2219 specimen. Since 

the anodized coating is considered non-conductive and the two alloys (i.e., Al 2219 and Al 6061) 

are considered galvanically-compatible, no galvanic effects were anticipated. In the 

supplemental testing the stressing frames were coated with a plastic compound for extra galvanic 

protection. The extra isolation of the frames may have more fully suppressed galvanic effects;

however, it is uncertain whether this created sufficiently different environmental conditions to 

explain the varied test results. The failure that occurred in the 50% YS exposure stress level 

specimen from coupon blank M10 during the Phase II testing was not repeatable.

The pass/fail results, percent tensile strength retained, residual strength ratio, and results of 

metallurgical examination for all of the materials evaluated in both the Phase II and supplemental 

test phases of this study indicate that the spin forming process and associated modified heat treat 

practice reduces the SCC resistance of Al 2219-T6 material when compared with handbook 

rankings for Al 2219-T6 wrought products. The reduced SCC resistance was likely due to the 

slower quench rate experienced during the modified heat treatment as compared with the 

standard heat treatment. Evidence of SCC was observed in material from the aft bulkhead, 

CPST dome, and modified plate, which all received the modified heat treatment. SCC failures 

occurred in all three products for material exposed at the minimum used in this study, 50% of the 

MMPDS ST YS for plate (18 ksi), based on either failure during exposure, residual strength 

reduction, or occurrence of SCC. It should be noted that the data from this study provides an 
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indication of SCC resistance, but additional data will be needed to confirm trends noted and to 

establish a threshold stress level for SCC. It is recommended that additional testing be 

performed by the Orion MPCV Program or other end users of spin formed Al 2219-T6 products. 

This study sampled one spin formed aft bulkhead and consequently only one material lot.

Additional testing should be performed on multiple articles from initial serial production and 

should sample multiple material lots. It is also recommended that heat treatment studies be 

performed to determine whether a faster quench rate can be achieved that improves SCC 

resistance without compromising residual stress and distortion control.

Table 4. Supplemental SCC test results for spin formed Al 2219-T62 aft bulkhead, CPST 

dome and wrought plate materials following 30-day 3.5% NaCl alternate immersion exposure.

(1) Average UTS and YS values obtained from baseline tensile tests of unexposed specimens.

(2) MMPDS A-basis LT YS = 36 ksi.

(3) Failure ratio = number of failures divided by total number of specimens tested.

0 0 0 0/3 NF in 30 days

18 40.5 50 0/3 NF in 30 days

27 60.8 75 0/3 NF in 30 days

22.2 50 61.7 0/3 NF in 30 days

33.3 75 92.5 0/3 NF in 30 days

0 0 0 0/3 NF in 30 days

18 43.0 50 0/3 NF in 30 days

27 64.5 75 0/3 NF in 30 days

0 0 0 0/3 NF in 30 days

18 41.8 50 0/3 NF in 30 days

27 62.6 75 0/3 NF in 30 days

0 0.0 0 0/3 NF in 30 days

18 41.1 50 0/3 NF in 30 days

27 61.6 75 0/3 NF in 30 days

0 0 0 0/3 NF in 30 days

18 41.4 50 0/3 NF in 30 days

27 62.1 75 0/3 NF in 30 days

0 0 0 0/3 NF in 30 days

18 48.4 50 0/3 NF in 30 days

27 72.6 75 0/3 NF in 30 days

0 0 0 0/3 NF in 30 days

18 44.8 50 0/3 NF in 30 days

27 67.2 75 0/3 NF in 30 days

0 0 0 0/3 NF in 30 days

18 48.2 50 0/3 NF in 30 days

27 72.3 75 0/3 NF in 30 days

Material 

Source

Location / 

Heat Treat Orient.

 UTS(1) 

ksi

 YS(1) 

ksi

Aft 

Bulkhead

M10 

Membrane ST 59.65 44.41

Applied 

Stress Level 

ksi

Applied 

Stress Level 

% Actual 

ST YS

Applied 

Stress Level 

% MMPDS 

LT YS(2)

Failure 

Ratio(3)

Days to 

Failure

Aft 

Bulkhead

J2 

Membrane ST 57.04 43.11

Aft 

Bulkhead

J1 

Pole ST 55.09 41.88

CPST 

Dome Pole ST 56.30 40.18

Plate Modified ST 59.15 37.19

Aft 

Bulkhead

J3 

Rim ST 58.05 43.81

Plate Standard ST 62.07 43.50

CPST 

Dome Rim ST 57.56 37.33
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Table 5. Phase II SCC test results for spin formed Al 2219-T62 aft bulkhead material 

following 30-day 3.5% NaCl alternate immersion exposure.

Coupon 

Blank

Meridian 

Angle Orient.

UTS

ksi

YS

ksi

Stress 

Level

% YS

Stress 

Level

ksi

Failure 

Ratio(3)

Days to 

Failure

M7 90° ST 57.87 43.2

0 0 0/3 No failures

50 21.6 0/3 No failures

75 32.4 3/3 26, 28, 30

M8 90° ST 58.69 43.73

0 0 0/3 No failures

50 21.87 0/3 No failures

75 32.8 3/3 27, 30, 30

M9 90° ST 59.86 44.33

0 0 0/3 No failures

50 22.17 1/3(1) 30(1)

75 33.25 0/3 No failures

M10 190° ST 59.65 44.41

0 0 0/3 No failures

50 22.21 1/3(2) 29

75 33.31 2/3 26, 30

(1) Invalid failure. Failed in the shoulder outside of the gage length.

(2) The two specimens that did not break apart during exposure did not pass the residual tensile strength ratio test and can also 

be considered failures.

(3) Failure ratio = number of failures divided by total number of specimens tested.
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Table 6. Baseline tensile properties of the Al 2219-T62 supplemental test materials.

Material 

Source

Location / 

Heat Treat

Orient. Specimen 

No.

UTS 

ksi

YS 

ksi

E 

Msi

e 

% 

Aft 

Bulkhead

M10 

Membrane ST

M10-19 59.44 44.57 9.98 4.76

M10-20 59.59 44.79 10.04 5.01

M10-21 59.92 43.88 10.34 4.73

Average 59.65 44.41 10.12 4.83

Aft 

Bulkhead

J1 

Pole ST J1-10 55.09 41.88 9.84 4.58

Aft 

Bulkhead

J2 

Membrane ST J2-10 57.04 43.11 10.14 5.13

Aft 

Bulkhead

J3 

Rim ST J3-10 58.05 43.81 10.01 5.68

Plate Standard ST

WQ-10 62.41 42.44 9.85 5.03

WQ-11 61.77 44.42 10.82 4.61

WQ-12 62.02 43.63 11.92 4.21

Average 62.07 43.5 10.86 4.62

Plate Modified ST

GQ-10 60.27 35.75 10.18 4.94

GQ-11 57.95 36.31 9.67 4.75

GQ-12 59.24 39.52 11.31 4.67

Average 59.15 37.19 10.39 4.79

CPST 

Dome Pole ST

CPP-10 55.4 41.74 10.79 3.06

CPP-11 57 40.77 10.1 3.86

CPP-12 56.5 38.02 9.81 4.01

Average 56.3 40.18 10.23 3.64

CPST 

Dome Rim ST

CPR-10 57.42 36.91 9.89 4.31

CPR-11 57.18 35.97 10.33 4.89

CPR-12 58.08 39.11 9.89 3.99

Average 57.56 37.33 10.04 4.40
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Table 7. Residual load carrying ability data for supplemental Al 2219-T62 spin formed and 

wrought plate materials following 30-day 3.5% NaCl alternate immersion exposure with an applied 

stress.

(1) UTSf = Residual strength of exposed specimen (failure load / original specimen cross-sectional area).

(2) Percent tensile strength retained = UTSf / UTSi x 100 where UTSi = average ultimate tensile strength 

obtained from baseline tensile tests of non-exposed specimens.

(3) Residual strength ratio = UTSs/UTSo where: UTSs = residual strength of stressed and exposed specimen and 

UTSo = averaged residual strength of non-stressed and exposed specimens.

(4) Passed if residual strength ratio ≥0.75, failed if ratio <0.75.

M10-4 22.2 50 61.7 35.48 60 1.14 Passed

M10-5 22.2 50 61.7 33.29 56 1.07 Passed

Avg. 34.39 58.0 1.11

M10-7 33.3 75 92.5 31.80 54 1.03 Passed

M10-8 33.3 75 92.5 36.71 62 1.18 Passed

Avg. 34.25 58.0 1.11

M10-13 18 40.5 50 34.34 58 1.11 Passed

M10-14 18 40.5 50 32.32 55 1.04 Passed

Avg. 33.33 56.5 1.08

M10-17 27 60.8 75 33.73 57 1.09 Passed

M10-18 27 60.8 75 38.03 64 1.23 Passed

Avg. 35.88 60.5 1.16

J1-4 18 43.0 50 28.11 51 0.88 Passed

J1-5 18 43.0 50 33.00 60 1.03 Passed

Avg. 30.56 55.5 0.96

J1-1 27 64.5 75 29.58 54 0.92 Passed

J1-3 27 64.5 75 32.92 60 1.03 Passed

Avg. 31.25 57.0 0.98

J2-4 18 41.8 50 37.08 65 1.16 Passed

J2-6 18 41.8 50 30.97 54 0.97 Passed

Avg. 34.02 59.5 1.07

J2-1 27 62.6 75 31.37 55 0.98 Passed

J2-3 27 62.6 75 33.17 58 1.04 Passed

Avg. 32.27 56.5 1.01

J3-4 18 41.1 50 37.65 65 0.97 Passed

J3-6 18 41.1 50 39.93 69 1.03 Passed

Avg. 38.79 67.0 1.00

J3-1 27 61.6 75 32.68 57 0.85 Passed

J3-2 27 61.6 75 41.97 73 1.09 Passed

Avg. 37.32 65.0 0.97

WQ-4 18 41.4 50 34.96 57 1.23 Passed

WQ-5 18 41.4 50 33.99 55 1.19 Passed

Avg. 34.47 56.0 1.21

WQ-7 27 62.1 75 27.84 45 0.98 Passed

WQ-8 27 62.1 75 28.63 46 1.01 Passed

Avg. 28.24 45.5 1.00

GQ-5 18 48.4 50 33.99 57 0.87 Passed

GQ-6 18 48.4 50 30.65 52 0.78 Passed

Avg. 32.32 54.5 0.83

GQ-8 27 72.6 75 36.71 62 0.94 Passed

GQ-9 27 72.6 75 37.15 63 0.95 Passed

Avg. 36.93 62.5 0.95

CP-P4 18 44.8 50 27.93 50 0.85 Passed

CP-P5 18 44.8 50 19.24 34 0.58 Failed

Avg. 23.58 42.0 0.72

CP-P7 27 67.2 75 26.26 47 0.8 Passed

CP-P8 27 67.2 75 24.15 43 0.73 Failed

Avg. 25.21 45.0 0.77

CP-R5 18 48.2 50 29.95 52 0.87 Passed

CP-R6 18 48.2 50 33.64 59 0.98 Passed

Avg. 31.80 55.5 0.93

CP-R8 27 72.3 75 30.65 54 0.89 Passed

CP-R9 27 72.3 75 25.21 44 0.73 Failed

Avg. 27.93 49.0 0.81

Pole ST

Rim ST

Aft 

Bulkhead

M10 

Membrane ST

Aft 

Bulkhead

J1 

Pole ST

Aft 

Bulkhead

Aft 

Bulkhead

Plate

Plate

CPST 

Dome

CPST 

Dome

J2 

Membrane ST

J3 

Rim ST

Standard ST

Modified ST

Residual 

Strength 

Ratio(3) Pass / Fail(4) Material Source

Location / 

Heat Treat Orient.

Specimen 

No.

Applied 

Stress Level 

ksi

Applied 

Stress Level % Actual ST 

YS

Applied 

Stress Level % MMPDS 

LT YS

Residual 

Tensile 

Strength(1) 

ksi

Percent 

Tensile 

Strength 

Retained(2)
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Table 8. Residual tensile strength and percent tensile strength retained for supplemental Al 

2219-T62 spin formed and wrought plate materials following 30-day 3.5% NaCl alternate 

immersion exposure with no applied stress.

(1) UTSf = Residual strength of exposed specimen (failure load / original specimen cross-sectional area).

(2) Percent tensile strength retained = UTSf / UTSi x 100 where UTSi = average ultimate tensile strength 

obtained from baseline tensile tests of non-exposed specimens.

Material Location /

Source Heat Treat

M10-1 0 38.19 64

M10-2 0 23.79 40

Average 0 30.99 5 2

J1-7 0 36.59 66

J1-9 0 27.55 50

Average 0 32.07 5 8

J2-7 0 29.67 52

J2-9 0 34.07 60

Average 0 31.87 5 6

J3-7 0 36.92 64

J3-9 0 40.34 69

Average 0 38.63 6 7

WQ-1 0 28.53 46

WQ-2 0 28.36 46

Average 0 28.45 4 6

GQ-2 0 43.63 74

GQ-3 0 34.5 58

Average 0 39.07 6 6

CP-P1 0 33.36 59

CP-P3 0 32.66 58

Average 0 33.01 5 8

CP-R2 0 35.82 62

CP-R3 0 33.01 57

Average 0 34.42 6 0

CPST 

Dome Rim ST

CPST 

Dome Pole ST

Plate Modified ST

Plate Standard ST

Aft 

Bulkhead J3 ST

Aft 

Bulkhead J2 ST

Residual 

Tensile 

Strength(1) 

ksi

Percent 

Tensile 

Strength 

Retained

Orient. (2)

Aft 

Bulkhead M10 ST

Specimen 

No.

Applied 

Stress Level 

ksi

Aft 

Bulkhead J1 ST
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Table 9. Residual load carrying ability data from the Phase II SCC testing of spin formed Al 

2219-T62 aft bulkhead material following 30-day 3.5% NaCl alternate immersion exposure.

(1) UTSf = Residual strength of exposed specimen (failure load / original specimen cross-sectional area).

(2) Percent tensile strength retained = UTSf / UTSi x 100 where UTSi = average ultimate tensile strength obtained from baseline 

tensile tests of non-exposed specimens.

(3) Residual strength ratio = UTSs/UTSo where: UTSs = residual strength of stressed and exposed specimen and UTSo = 

averaged residual strength of non-stressed and exposed specimens.

(4) Passed if residual strength ratio ≥0.75, failed if ratio <0.75.

Applied Applied Residual (1) Percent (2)

Baseline Baseline Stress Stress Tensile Tensile Residual (3)

Coupon Orient. UTS, YS, Specimen Level, Level, Strength Strength Strength

Blank ksi ksi No. ksi % YS ksi Retained Ratio Pass/Fail (4)

24 0 0 28.40 49.0 NA NA

25 0 0 18.61 32.0 NA NA

Avg. 23.51 40.5

27 21.60 50 22.51 39.0 0.96 passed

28 21.60 50 20.97 36.0 0.89 passed

Avg. 21.74 37.5 0.93

 ------- 32.40 75 ------- ------- ------- -------

 ------- 32.40 75 ------- ------- ------- -------

Avg. NA NA NA

66 0 0 23.25 40.0 NA NA

67 0 0 19.44 33.0 NA NA

Avg. 21.35 36.5

69 21.87 50 16.52 28.0 0.77 passed

70 21.87 50 32.45 55.0 1.52 passed

Avg. 24.49 41.5 1.1

 ------- 32.8 75 ------- ------- ------- -------

 ------- 32.8 75 ------- ------- ------- -------

Avg. NA NA NA

108 0 0 26.95 45.0 NA NA

109 0 0 19.55 33.0 NA NA

Avg. 23.25 39.0

110 22.17 50 28.09 47.0 1.21 passed

112 22.17 50 19.66 33.0 0.85 passed

Avg. 23.88 40.0 1.03

114 33.25 75 24.50 41.0 1.05 passed

115 33.25 75 27.58 46.0 1.19 passed

Avg. 26.04 43.5 1.12

150 0 0 18.88 32.0 NA NA

151 0 0 19.36 32.0 NA NA

Avg. 19.12 32.0

153 22.21 50 5.51 9.0 0.29 failed

154 22.21 50 2.56 4.0 0.13 failed

Avg. 4.04 6.5 0.21

155 33.31 75 20.32 34.0 1.06 passed

 --- --- --- --- --- --- ---

Avg. 20.32 34.0 1.06

M 9

M10 ST

57.87 43.20

58.69 43.73

59.86 44.33

59.65 44.41

M 7 ST

M 8 ST

ST
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

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Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

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NESC Request No.: TI-13-00884_Phase II Supplemental Report

(a) Non-Exposed Specimens

(b) Exposed Specimens

Figure 4. Stress-strain curves for (a) non-exposed specimens and (b) exposed specimens of 

Al 2219-T62.
NASA Engineering and Safety Center

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Document #:

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Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

33 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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m10-3_etched_m03_20x.jpg m10-3_etched_m04_50x.jpg

Coupon blank: M10

Specimen No.: M10-3

Orientation: ST

Applied stress (% YS): 0

Applied stress (ksi): 0

Failed?: No

SCC?: No

(a) 0% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

34 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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m10-6_etched_m03_20x.jpg m10-6_etched_m04_50x.jpg

Coupon blank: M10

Specimen No.: M10-6

Orientation: ST

Applied stress (% YS): 50, based on M10 average ST YS

Applied stress (ksi): 22.2

Failed?: No

SCC?: Yes; circled in red

(b) 50% YS (measured)
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

35 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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m10-15_etched_m03_20x.jpg m10-15_etched_m04_50x.jpg

Coupon blank: M10

Specimen No.: M10-15

Orientation: ST

Applied stress (% YS): 50, based on MMPDS LT YS

Applied stress (ksi): 18

Failed?: No

SCC?: Yes; circled in red

(c) 50% YS (MMPDS)
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

36 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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m10-9_etched_m03_20x.jpg m10-9_etched_m04_50x.jpg

Coupon blank: M10

Specimen No.: M10-9

Orientation: ST

Applied stress (% YS): 75, based on M10 average ST YS

Applied stress (ksi): 33.3

Failed?: No

SCC?: Yes; circled in red

(d) 75% YS (measured)
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

37 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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m10-16_etched_m03_20x.jpg m10-16_etched_m04_50x.jpg

Coupon blank: M10

Specimen No.: M10-16

Orientation: ST

Applied stress (% YS): 75, based on MMPDS LT YS

Applied stress (ksi): 27

Failed?: No

SCC?: Yes; circled in red

(e) 75% YS (MMPDS)

Figure 5. Photomicrographs of SCC specimens from aft bulkhead coupon blank M10 following 

30-day 3.5% NaCl alternate immersion exposure at applied stress levels of (a) 0% YS; 

(b) 50% YS (measured); (c) 50% YS (MMPDS); (d) 75% YS (measured); and (e) 75% 

YS (MMPDS). 
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

38 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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j1-8_etched_m03_20x.jpg j1-8_etched_m04_50x.jpg

Coupon blank: J1

Specimen No.: J1-8

Orientation: ST

Applied stress (% YS): 0

Applied stress (ksi): 0

Failed?: No

SCC?: No

(a) 0% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

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Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

39 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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j1-6_etched_m03_20x.jpg j1-6_etched_m04_50x.jpg

Coupon blank: J1

Specimen No.: J1-6

Orientation: ST

Applied stress (% YS): 50, based on MMPDS LT YS

Applied stress (ksi): 18

Failed?: No

SCC?: No

(b) 50% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

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Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

40 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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j1-2_etched_m03_20x.jpg j1-2_etched_m04_50x.jpg

Coupon blank: J1

Specimen No.: J1-2

Orientation: ST

Applied stress (% YS): 75, based on MMPDS LT YS

Applied stress (ksi): 27

Failed?: No

SCC?: Yes; circled in red

(c) 75% YS

Figure 6. Photomicrographs of SCC specimens from aft bulkhead coupon blank J1 following 

30-day 3.5% NaCl alternate immersion exposure at applied stress levels of (a) 0% YS; 

(b) 50% YS; and (c) 75% YS.
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

41 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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j2-8_etched_m03_20x.jpg j2-8_etched_m04_50x.jpg

Coupon blank: J2

Specimen No.: J2-8

Orientation: ST

Applied stress (% YS): 0

Applied stress (ksi): 0

Failed?: No

SCC?: No

(a) 0% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

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Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

42 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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j2-5_etched_m03_20x.jpg j2-5_etched_m04_50x.jpg

Coupon blank: J2

Specimen No.: J2-5

Orientation: ST

Applied stress (% YS): 50, based on MMPDS LT YS

Applied stress (ksi): 18

Failed?: No

SCC?: Yes; circled in red

(b) 50% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

43 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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j2-2_etched_m03_20x.jpg j2-2_etched_m04_50x.jpg

Coupon blank: J2

Specimen No.: J2-2

Orientation: ST

Applied stress (% YS): 75, based on MMPDS LT YS

Applied stress (ksi): 27

Failed?: No

SCC?: No

(c) 75% YS

Figure 7. Photomicrographs of SCC specimens from aft bulkhead coupon blank J2 following 

30-day 3.5% NaCl alternate immersion exposure at applied stress levels of (a) 0% YS; 

(b) 50% YS; and (c) 75% YS.
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

44 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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j3-8_etched_m03_20x.jpg j3-8_etched_m04_50x.jpg

Coupon blank: J3

Specimen No.: J3-8

Orientation: ST

Applied stress (% YS): 0

Applied stress (ksi): 0

Failed?: No

SCC?: No

(a) 0% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

45 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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j3-5_etched_m03_20x.jpg j3-5_etched_m04_50x.jpg

Coupon blank: J3

Specimen No.: J3-5

Orientation: ST

Applied stress (% YS): 50, based on MMPDS LT YS

Applied stress (ksi): 18

Failed?: No

SCC?: No

(b) 50% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

46 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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j3-3_etched_m03_20x.jpg j3-3_etched_m04_50x.jpg

Coupon blank: J3

Specimen No.: J3-3

Orientation: ST

Applied stress (% YS): 75, based on MMPDS LT YS

Applied stress (ksi): 27

Failed?: No

SCC?: No

(c) 75% YS

Figure 8. Photomicrographs of SCC specimens from aft bulkhead coupon blank J3 following 

30-day 3.5% NaCl alternate immersion exposure at applied stress levels of (a) 0% YS; 

(b) 50% YS; and (c) 75% YS.
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

47 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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wq-3_etched_m03_20x.jpg wq-3_etched_m04_50x.jpg

Coupon blank: Standard plate

Specimen No.: WQ-3

Orientation: ST

Applied stress (% YS): 0

Applied stress (ksi): 0

Failed?: No

SCC?: No

(a) 0% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

48 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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wq-6_etched_m03_20x.jpg wq-6_etched_m04_50x.jpg

Coupon blank: Standard plate

Specimen No.: WQ-6

Orientation: ST

Applied stress (% YS): 50, based on MMPDS LT YS

Applied stress (ksi): 18

Failed?: No

SCC?: No

(b) 50% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

49 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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wq-9_etched_m03_20x.jpg wq-9_etched_m04_50x.jpg

Coupon blank: Standard plate

Specimen No.: WQ-9

Orientation: ST

Applied stress (% YS): 75, based on MMPDS LT YS

Applied stress (ksi): 27

Failed?: No

SCC?: No

(c) 75% YS

Figure 9. Photomicrographs of SCC specimens from standard plate following 30-day 3.5% NaCl 

alternate immersion exposure at applied stress levels of (a) 0% YS; (b) 50% YS; and 

(c) 75% YS.
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

50 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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gq-1_etched_m03_20x.jpg gq-1_etched_m04_50x.jpg

Coupon blank: Modified plate

Specimen No.: GQ-1

Orientation: ST

Applied stress (% YS): 0

Applied stress (ksi): 0

Failed?: No

SCC?: No

(a) 0% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

51 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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gq-4_etched_m03_20x.jpg gq-4_etched_m04_50x.jpg

Coupon blank: Modified plate

Specimen No.: GQ-4

Orientation: ST

Applied stress (% YS): 50, based on MMPDS LT YS

Applied stress (ksi): 18

Failed?: No

SCC?: Yes; encircled in red

(b) 50% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

52 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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gq-7_etched_m03_20x.jpg gq-7_etched_m04_50x.jpg

Coupon blank: Modified plate

Specimen No.: GQ-7

Orientation: ST

Applied stress (% YS): 75, based on MMPDS LT YS

Applied stress (ksi): 27

Failed?: No

SCC?: No

(c) 75% YS

Figure 10. Photomicrographs of SCC specimens from modified plate following 30-day 3.5% NaCl 

alternate immersion exposure at applied stress levels of (a) 0% YS; (b) 50% YS; and 

(c) 75% YS.
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

53 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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cp-p2_etched_m03_20x.jpg cp-p2_etched_m04_50x.jpg

Coupon blank: CPST dome; pole region

Specimen No.: CP-P2

Orientation: ST

Applied stress (% YS): 0

Applied stress (ksi): 0

Failed?: No

SCC?: No

(a) 0% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

54 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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cp-p6_etched_m03_20x.jpg cp-p6_etched_m04_50x.jpg

Coupon blank: CPST dome; pole region

Specimen No.: CP-P6

Orientation: ST

Applied stress (% YS): 50, based on MMPDS LT YS

Applied stress (ksi): 18

Failed?: No

SCC?: No

(b) 50% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

55 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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cp-p9_etched_m03_20x.jpg cp-p9_etched_m04_50x.jpg

Coupon blank: CPST dome; pole region

Specimen No.: CP-P9

Orientation: ST

Applied stress (% YS): 75, based on MMPDS LT YS

Applied stress (ksi): 27

Failed?: No

SCC?: Yes; circled in red

(c) 75% YS

Figure 11. Photomicrographs of SCC specimens from the CPST dome pole following 30-day 3.5% 

NaCl alternate immersion exposure at applied stress levels of (a) 0% YS; (b) 50% YS; 

and (c) 75% YS.
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

56 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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cp-r1_etched_m03_20x.jpg cp-r1_etched_m04_50x.jpg

Coupon blank: CPST dome; rim region

Specimen No.: CP-R1

Orientation: ST

Applied stress (% YS): 0

Applied stress (ksi): 0

Failed?: No

SCC?: No

(a) 0% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

57 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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cp-r4_etched_m03_20x.jpg cp-r4_etched_m04_50x.jpg

Coupon blank: CPST dome; rim region

Specimen No.: CP-R4

Orientation: ST

Applied stress (% YS): 50, based on MMPDS LT YS

Applied stress (ksi): 18

Failed?: No

SCC?: No

(b) 50% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

58 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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cp-r7_etched_m03_20x.jpg cp-r7_etched_m04_50x.jpg

Coupon blank: CPST dome; rim region

Specimen No.: CP-R7

Orientation: ST

Applied stress (% YS): 75, based on MMPDS LT YS

Applied stress (ksi): 27

Failed?: No

SCC?: Yes; circled in red

(c) 75% YS

Figure 12. Photomicrographs of SCC specimens from the CPST dome rim following 30-day 3.5% 

NaCl alternate immersion exposure at applied stress levels of (a) 0% YS; (b) 50% YS; 

and (c) 75% YS.
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

59 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

5.4 Stress Corrosion Summary

Results for all of the materials evaluated during the Phase II and supplemental SCC testing 

indicate that the spin forming process and associated modified heat treat practice reduces the

resistance to SCC based on comparison with handbook rankings for Al 2219-T6 wrought 

products. Evidence of SCC was observed in material from the aft bulkhead, CPST dome, and 

modified plate, based on the criteria of failure during exposure, residual strength reduction, or 

occurrence of SCC. These materials all received the modified heat treatment, indicating that the 

reduced SCC resistance was likely due to the modified heat treatment and not the spin forming 

process. SCC failures occurred in all three products for material exposed at the minimum 

exposure stress level used in this study, 50% of the MMPDS ST YS for plate, indicating that the 

threshold stress level for SCC may be lower.

No specimens failed during the supplemental test exposures of the aft bulkhead and postexposure residual strength ratios were above minimum required values. A retest of coupon blank 

M10 showed that the single specimen failure at 50% YS exposure stress was not repeatable. 

Similarly, tests of adjacent coupon blank J2 showed no specimen failures. A review of test 

procedures and specimen preparation could not identify a cause for this discrepancy with the 

Phase II testing and could indicate material variability. However, post-exposure microstructural 

examination showed SCC in the supplemental test specimens from coupon blanks M10 and J2.

Test results for the aft bulkhead indicated increasing SCC resistance with distance from the pole. 

In the Phase II testing the number of specimen failures during exposure was smallest at the rim 

and increased at the membrane and pole locations. The only specimens in the Phase II test matrix 

that failed the residual strength or exhibited SCC were from the pole and membrane regions. In 

both the Phase II and supplemental tests the percent residual strength retained was greatest at the 

rim, lower in the membrane, and lowest at the pole. The only supplemental test specimens that 

exhibited SCC were from the pole and membrane locations. Results from the CPST dome 

showed less well defined trends with location; however, the lowest residual strength ratio was 

from the pole.

Similar pass/fail results and residual strengths were observed for the standard and modified 

plates. However, metallurgical analysis showed evidence of SCC in the modified plate, 

suggesting that the reduced quench rate associated with the modified heat treatment reduced the 

SCC resistance. Studies to increase the quench rate while not compromising residual stress and 

distortion effects are recommended.

Additional SCC testing is recommended by the Orion MPCV Program and/or other users of spin 

formed Al 2219-T6 products to confirm trends presented by this study, to establish a threshold 

stress level for SCC, and to determine a maximum allowable service stress. Additional testing 

should be performed on multiple articles from initial serial production and should sample 

multiple material lots. In addition, exposure stress levels during additional testing should be 

successively reduced until no evidence of SCC occurs. Results from this study and any 

additional programmatic testing may be used to develop a Materials Usage Agreement (MUA).
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

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NESC Request No.: TI-13-00884_Phase II Supplemental Report

The following findings, observations, and NESC recommendations are provided in response to 

the questions posed in Table 1 for the supplemental stress corrosion tests.

A retest of coupon blank M10 showed that the single specimen failure at 50% YS 

exposure stress was not repeatable.

Material from coupon blank M10 and the adjacent blank, J2, passed the 30-

day 3.5% NaCl alternate immersion exposure at 50%YS exposure stress and 

had acceptable residual strength ratios.

Post-exposure microstructural examination showed SCC in both the Phase II 

tests of coupon blank M10 and the supplemental tests of coupon blank M10 

and J2.

Aft bulkhead material from coupon blank M10 passed the 30-day 3.5% NaCl alternate 

immersion exposure at exposure stress levels based on MMPDS for plate and measured 

ST YS values for the aft bulkhead.

Material from additional locations in the aft bulkhead passed the 30-day 3.5% NaCl 

alternate immersion exposure at exposure stress levels based on MMPDS YS values for 

plate and exhibited residual strengths above minimum required values.

 Residual strength values were higher at the rim as compared with the pole and 

membrane locations.

The combined spin forming process and associated modified heat treat practice reduces

the SCC resistance compared with wrought plate, likely related to the slower quench rate 

associated with the modified heat treatment.

 While no SCC failures occurred during 30-day alternate immersion exposure 

in a 3.5% NaCl environment, post-exposure metallurgical evaluation showed 

SCC in the spin formed aft bulkhead and CPST dome materials subjected to 

the modified heat treatment.

 Remnant plate processed using the modified heat treatment exhibited lower

post-exposure residual strength values than standard plate.

 Post-exposure metallurgical evaluation showed SCC in the modified plate. 

No evidence of SCC was found in the standard plate.

The SCC resistance of the Al 2219-T62 spin formed aft bulkhead and CPST dome were 

similar, indicating that the SCC behavior observed is likely representative of similarly 

processed Al 2219-T62 spin formed products.

The SCC data for the aft bulkhead provides insight about the SCC resistance of the spin 

formed Al 2219-T62 material, but is insufficient to establish a SCC threshold stress level.

 Testing in this study sampled one spin formed aft bulkhead and one material 

lot. Establishing a threshold requires testing of multiple serial production aft 

bulkheads and multiple material lots.
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 Evidence of SCC was observed for all non-zero exposure stress levels

indicating that the SCC threshold is below the minimum stress level used in 

this study.

Grain size in the CPST dome was larger than in the aft bulkhead, which may have 

contributed to a greater extent of pitting and lower percent tensile strength retained and 

residual strength ratios.

R-1. Perform additional SCC testing on spin formed Al 2219-T6 products to establish a 

threshold stress level for SCC and to determine a maximum allowable service stress.

(O-1)

 Additional testing should be performed on multiple articles from initial serial 

production and should sample multiple material lots.

 Exposure stress levels should be successively reduced until there is no 

evidence of stress corrosion.

R-2. Perform heat treatment studies to determine whether a faster quench rate can be achieved 

that improves SCC resistance without compromising residual stress and distortion 

control. (F-4) 
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6.0 Supplemental Tensile Tests

6.1 Background

Based on the results of the tensile tests performed on the aft bulkhead and the limited amount of 

handbook data available for interpretation of the results, a limited quantity of additional tensile 

tests were conducted to address key questions. Table 10 shows the supplemental tensile test 

matrix and questions being addressed.

Table 10. Supplemental tensile test matrix and questions being addressed.

(1) Standard: Solution heat treat @ 995°F ± 10°F / 3 hours; water quench, and age @ 375°F ± 10°F / 36 hours.

(2) Modified: Solution heat treat @ 995°F ± 10°F / 3 hours; glycol quench, and age @ 375°F ± 10°F / 36 hours.

6.2 Microstructural Analysis

Based on microstructural characterization of the aft bulkhead performed during the Phase II 

study, the post-recrystallization grain morphology varies with meridian distance and throughthickness position, with larger grain sizes associated with likely regions of higher deformation

(3), (16). Grain sizes were larger toward the rim and toward the OML surface, which was in 

direct contact with the forming tool. Additional microstructural analysis of the aft bulkhead was 

performed in support or the supplemental tensile test matrix. No metallurgical analysis was 

performed on the standard or modified plate nor on the CPST dome.

For the initial test and evaluation of the aft bulkhead conducted during the Phase II study, tensile, 

fracture toughness, and SCC specimens extracted from the aft bulkhead were located at the t/2 

through-thickness position. Metallurgical analysis performed during the Phase II study revealed 

that the microstructure in the aft bulkhead was most uniform with meridian distance (from pole 

Material 

Source

Location / Heat 

Treatment

Orient.

Throughthickness 

position

# of Specimens Question Addressed

t/8 3

7t/8 3

t/8 3

7t/8 3

L t/2 3

LT t/2 3

ST t/2 3

L t/2 3

LT t/2 3

ST t/2 3

1. What are the tensile properties at other 

through-thickness locations in the aft 

bulkhead?

2. What effect does the inhomogeneous 

microstructure have on the tensile 

properties of the aft bulkhead?

3. How do the tensile properties of the aft 

bulkhead compare to wrought plate?

4. What effect does a slower quench during 

heat treat processing have on the tensile 

properties of the material?

 

5. Are the high ST tensile properties in the aft 

bulkhead inherent to the plate lot or are they 

an artifact of spin form processing?

Plate Standard (1)

L

LT

Aft Bulkhead L2

Plate Modified (2)
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to rim) at t/2 as compared with other through-thickness positions. At t/2 the microstructure 

exhibited the greatest similarity in grain size, morphology, and extent of precipitation on prior 

deformation bands. Additional specimen testing was needed to determine whether there is any 

variation in tensile properties at other through-thickness positions, particularly those biased 

toward the OML.

The through-thickness microstructure at locations from pole to rim were examined in the Phase 

II characterization of the aft bulkhead using meridian arc length coupon blank L7 (Figure 13). 

Coupon blank L2 matched the location on L7 that exhibited the greatest through-thickness 

variation in microstructure so this blank was selected for the supplemental tensile tests. The 

location of specimens machined from coupon blank L2 are shown in Figure 14. Noted are the 

locations of the Phase II and supplemental test specimens. Metallurgical samples were prepared 

from machining remnants adjacent to the L and LT supplemental test specimens. Samples of the 

LT-S and L-S planes were polished through various grades of silicon carbide paper and then 

colloidal diamond paste. Following polishing, the samples were etched with Keller’s reagent 

and were examined using optical microscopy to evaluate variability in grain morphology and 

uniformity through the thickness at each location.

The through-thickness microstructure of the machining remnants of the L and LT supplemental 

test specimens for coupon blank L2 is shown in Figure 15 for the L-S and LT-S planes. The 

grain size was smallest at the inner mold line (IML) where the material was in contact with the 

supporting mandrel and largest towards the OML where deformation was greatest (due to the 

forming tool contacting the material). The larger grain size was due to strain induced 

recrystallization. The t/8 and 7t/8 positions showed significant difference in grain size compared 

to the t/2 position and were selected for the supplemental test specimen position. In addition, the 

membrane region of the finished machined aft bulkhead will likely be located near the OML 

surface so tensile properties from this region will be of most interest to the Orion designers.
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Figure 13. Aft bulkhead cut plan showing the location of the tensile coupon blank for 

supplemental testing highlighted in yellow.

Figure 14. Coupon blank L2 showing the locations of the Phase II and supplemental tensile 

specimens.
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(a) L-S plane

IML

t/8

t/4

3t/8

t/2

5t/8

3t/4

7t/8

OML

S

L

200 m
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(b) LT-S plane

Figure 15. Through-thickness microstructure of aft bulkhead coupon blank L2 in the (a) L-S 

plane and (b) LT-S plane.

Electron backscatter diffraction (EBSD) was used to quantitatively determine grain size and 

texture of coupon blank L2 at the t/8, t/2, and 7t/8 through-thickness positions shown in Figure 

15. Regions approximately 0.06 to 0.08 inch x 0.25 inch were scanned at each thickness position 

for the L-S and LT-S planes. The larger grain size at the t/8 (OML) is evident in the inverse pole 

figure maps shown in Figure 16. The grain size at t/8 and t/2 appear similar. Grain sizes at each 

location were quantified using average intercept lengths in the L / LT and ST orientations in each 

image, ASTM grain size number, and average grain area and the results are summarized in Table 

11. The results confirm that the largest grain size occurs at 7t/8 (near the OML surface), with 

intercept lengths in both dimensions twice that of the t/8 and t/2 positions and grain areas three to 

six times larger.

Through-thickness variations in texture were evaluated from the EBSD data and are shown in 

Figure 17 and Figure 18 as texture maps and pole figures, respectively, for the t/8, t/2, and 7t/8 

IML

t/8

t/4

3t/8

t/2

5t/8

3t/4

7t/8

OML

S

LT 200 m
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positions for the L-S and LT-S planes. In Figure 17 each color represents all variants for a given 

texture components within 20 degrees. The texture analysis reveals a mix of shear, compressive 

deformation (Brass and Copper), and cube components, with the shear and cube being most 

dominant. More brass and copper are observed at t/8 (near the IML), indicative of compression 

of material against the forming mandrel. The pole figures indicate similar texture distributions 

for the L-S and LT-S planes. Stronger textures were observed at t/2 and 7t/8 (near the OML) 

reflecting the higher degree of deformation associated with contact by the forming roller.

(a) L-S plane
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(b) LT-S plane

Figure 16. Inverse pole figure maps at t/8, t/2, and 7t/8 of aft bulkhead coupon blank L2 for the 

(a) L-S and (b) LT-S planes.

Table 11. Grain sizes for the L and LT planes at t/8, t/2, and 7t/8 of aft bulkhead coupon 

blank L2.

Orient.

Throughthickness 

position

Intercept Length 

μm

ASTM #

Grain 

Area 

μm2 ST L or LT

L

t/8 72.3 156 3.8 18,950

t/2 76.7 169.4 3.8 22,031

7t/8 130.1 274.8 2.4 68,502

LT

t/8 74.7 134.3 4 16,296

t/2 76.9 136.2 4 16,682

7t/8 151.7 285.7 1.6 98,270
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(a) L-S plane
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(b) LT-S plane

Figure 17. Texture maps at t/8, t/2, and 7t/8 of aft bulkhead coupon blank L2 for the (a) L-S and 

(b) LT-S planes.
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(a) L-S plane
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(b) LT-S plane

Figure 18. Pole figures for the t/8, t/2, and 7t/8 through-thickness positions of aft bulkhead coupon 

blank L2 for the (a) L-S and (b) LT-S planes.

6.3 Heat Treat Practice

Additional testing was designed to address the heat treat practice used in the processing of the aft 

bulkhead as described in Section 7.8 of Phase II Spin Formed Aft Bulkhead report (3). The 

solution heat treat and quench operation used by Spincraft consisted of a quench in a 

water/glycol mixture, which results in a slower overall cooling rate compared with a water 

quench to reduce part distortion and residual stress in the final product. Although this quench 

operation is permissible per AMS 2770, the slower cooling rate affects the precipitation kinetics 

during subsequent aging and may impact material properties (17).

F-temper plate machining remnants from the aft bulkhead forming blank were laboratory heat 

treat processed to the T62 temper as per AMS 2770 (18). This heat treatment consists of 

solutionizing at 995°F ± 10°F for a soak time of 3 hours, followed by a quench, and artificially 

ageing at 375°F ± 10°F for 36 hours. Two variants of this heat treatment were evaluated: 

standard heat treatment that used a water quench and modified heat treatment, which used a

glycol quench (15-17% polymer solution type 1/water quench medium) similar to that used by 
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Spincraft in the heat treatment of the aft bulkhead. Figure 19 illustrates the difference in cooling 

rates between the quench media based on data collected from embedded thermocouples in the 

plates processed for the supplemental testing. Plate processed using the two heat treatments are 

referred to in this report as standard and modified plate.

Figure 19. Cooling rate curves for water quench and glycol quench mediums.

0

100

200

300

400

500

600

700

800

900

1000

-150 -100 -50 0

Temp,

°F

Cooling Rate, °F/sec

dT/dt - Water quench

dT/dt - Glycol quench
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6.4 Tensile Test Procedures

To characterize the effects of the varying through-thickness microstructure on the tensile 

properties, tensile specimens from coupon blank L2 (arc length = 36.0 in; meridian angle 347°) 

(Figure 13) were tested at the t/8 (near the IML surface) and 7/t8 (near the OML surface) 

through-thickness locations for comparison to Phase II tensile test results acquired at the t/2 

location. To evaluate the effect of the modified heat treatment practice, tensile specimens were 

machined at the t/2 thickness position from the standard and modified plates for comparison with 

results from the aft bulkhead.

Tensile testing of the spin formed aft bulkhead and the standard and modified plate material was 

conducted in accordance with ASTM E8 (12). Room temperature tensile tests were conducted in 

the L and LT orientations for the aft bulkhead and the L, LT, and ST orientations for the plate. 

These grain orientations were with respect to the original plate rolling direction. No ST 

orientation specimens were machined for the supplemental aft bulkhead material since throughthickness locations other than t/2 were not feasible. Two specimen designs were used; one for 

the L and LT orientations (Figure 20) and one for the ST orientation (Figure 21). All specimens 

were machined from the coupon blanks such that the test section was located at either the t/8 

(near the IML surface), t/2 (mid-plane), or 7t/8 (near the OML surface) through-thickness 

position. Three replicate tests were conducted for each grain orientation as per the test matrices 

shown in Table 12.

Figure 20. Round subsize tensile specimen design used for testing in the L and LT orientations

(12). Dimensions are in inches.
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Figure 21. Round subsize tensile specimen design used for testing in the ST orientation (12). 

Dimensions are in inches.
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Table 12. Supplemental tensile test matrix for the aft bulkhead and remnant plate material.

Product Form Location / 

Heat Treatment Orient.

Throughthickness 

Location

Specimen ID

Aft bulkhead L2

L

t/8

T-L2-L-2-t/8-74

T-L2-L-2-t/8-76

T-L2-L-2-t/8-78

7t/8

T-L2-L-2-7t/8-73

T-L2-L-2-7t/8-75

T-L2-L-2-7t/8-77

LT

t/8

T-L2-LT-2-t/8-79

T-L2-LT-2-t/8-81

T-L2-LT-2-t/8-83

7t/8

T-L2-LT-2-7t/8-80

T-L2-LT-2-7t/8-82

T-L2-LT-2-7t/8-84

Plate

Standard (1)

L t/2

T-PL-WQ-L-85

T-PL-WQ-L-86

T-PL-WQ-L-87

LT t/2

T-PL-WQ-LT-88

T-PL-WQ-LT-89

T-PL-WQ-LT-90

ST t/2

T-PL-WQ-ST-91

T-PL-WQ-ST-92

T-PL-WQ-ST-93

Modified (2)

L t/2

T-PL-GLQ-L-94

T-PL-GLQ-L-95

T-PL-GLQ-L-96

LT t/2

T-PL-GLQ-LT-97

T-PL-GLQ-LT-98

T-PL-GLQ-LT-99

ST t/2

T-PL-GLQ-ST-100

T-PL-GLQ-ST-101

T-PL-GLQ-ST-102

(1)

 Standard: Solution heat treat @ 995°F ± 10°F / 3 hours; water quench, and age @ 375°F ± 10°F / 36 hours.

(2)

 Modified: Solution heat treat @ 995°F ± 10°F / 3 hours; glycol quench, and age @ 375°F ± 10°F / 36 hours.

Tensile tests were conducted in a servo-hydraulic test machine at a displacement rate of 

0.01 in/min (ipm) to specimen failure using the test setup shown in Figure 22. Back-to-back 

extensometers with either a 1.000 in (L and LT specimens) or 0.500 in (ST specimens) gauge 

length were used to measure specimen strain response. Ultimate tensile strength (UTS), 0.2% 

YS, and percent elongation (e) were determined for each test condition. The modulus of 

elasticity (E) was calculated from the stress-strain plot and is shown in the results section as a 

reference value. Figure 23 shows a typical stress-strain curve for a tensile test.
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Figure 22. Tensile test load stand, specimen, and instrumentation.
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Figure 23. Typical stress-strain curve for the spin formed Al 2219-T62 aft bulkhead material in 

the L orientation; coupon blank L2, specimen T-L2-L-13.

0

10

20

30

40

50

60

-0.010 0.010 0.030 0.050 0.070 0.090 0.110 0.130

Stress (ksi)

Strain (in/in)
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6.5 Tensile Test Results

6.5.1 Effect of Through-Thickness Position on Tensile Properties

The individual specimen tensile test results for the aft bulkhead coupon blank L2 at the t/8 and 

7t/8 through-thickness positions are shown in Table 13 for the L and LT orientations. Also 

shown for comparison are the tensile properties at the t/2 position from the same coupon blank 

from the Phase II test program. The overall average tensile property values and standard 

deviations for these specimens are shown in for each orientation.

Table 13. Tensile properties of the spin formed Al 2219-T62 aft bulkhead material from 

coupon blank L2 at through-thickness positions t/8, t/2, and 7t/8 in longitudinal (L) and long 

transverse (LT) orientations.

Specimen ID

ThroughCoupon Thickness Orient. UTS 0.2% YS E e(tot) 

Blank Position (ksi) (ksi) (Msi) (%)

L2

T-L2-L-2-t/8-74

t/8 L

59.06 41.64 10.35 11.17

T-L2-L-2-t/8-76 59.02 41.62 10.4 10.44

T-L2-L-2-t/8-78 59.22 41.71 10.45 10.35

T-L2-L-13

t/2 L

56.35 37.66 10.43 12.37

T-L2-L-14 56.56 37.79 10.47 12.68

T-L2-L-15 56.75 37.77 10.4 13.85

T-L2-L-2-7t/8-73*

7t/8 L

--- --- --- ---

T-L2-L-2-7t/8-75 57.24 38.45 10.48 10.82

T-L2-L-2-7t/8-77 57.11 38.52 10.42 10.47

L2

T-L2-LT-2-t/8-79

t/8 LT

58.82 41.05 10.43 9.75

T-L2-LT-2-t/8-81 57.93 40.55 10.3 9.81

T-L2-LT-2-t/8-83 58.04 40.74 10.38 8.56

T-L2-LT-16

t/2 LT

56.33 37.49 10.38 10.73

T-L2-LT-17 56.46 37.56 10.39 10.12

T-L2-LT-18 56.1 37.35 10.44 10.61

T-L2-LT-2-7t/8-80

7t/8 LT

56.6 38.18 10.46 9.01

T-L2-LT-2-7t/8-82 56.81 38.42 10.46 9.25

T-L2-LT-2-7t/8-84 56.16 38.36 10.44 8.75

 Data acquisition system malfunctioned; data set lost.
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Table 14. Average tensile properties and standard deviation values for the spin formed 

Al 2219-T62 aft bulkhead material as a function of through-thickness position and orientation.

Orient.

ThroughCoupon Thickness UTS 0.2% YS E e(tot) 

Blank Position (ksi) (ksi) (Msi) (%)

L2 L t/8

59.1 41.66 10.4 10.65 Average

0.11 0.05 0.05 0.45 Std. Dev.

L2 L t/2

56.55 37.74 10.44 12.97

0.2 0.07 0.03 0.78

L2 L 7t/8

57.17 38.49 10.45 10.65

0.1 0.05 0.04 0.24

Orient.

ThroughCoupon Thickness UTS 0.2% YS E e(tot) 

Blank Position (ksi) (ksi) (Msi) (%)

L2 LT t/8

58.26 40.78 10.37 9.37

0.48 0.25 0.07 0.71

L2 LT t/2

56.3 37.47 10.41 10.49

0.18 0.11 0.03 0.32

L2 LT 7t/8

56.52 38.32 10.45 9.01

0.33 0.13 0.01 0.25

The tensile strengths were uniform for each through-thickness position and orientation. Strength 

values varied by less than 1 ksi for each set of replicate specimens and standard deviations were 

less than 0.5. The t/8 through-thickness position exhibited higher UTS and YS values by 

approximately 2-3 ksi compared to the t/2 and 7t/8 positions for both the L and LT orientations. 

Values for the t/2 and 7t/8 positions were equivalent. Elongations exceeded 9% for all positions. 

The observed variation in material strength through the thickness may be related to the 

differences noted in grain size and texture at these positions, with higher strengths associated 

with finer grain size; however, the difference in strength was relatively small (<5%).

Tensile properties measured for the aft bulkhead were compared with MMPDS Handbook Abasis design allowable values for plate products (11) and with typical properties reported in the 

Alcoa Green Letter for 2219 (19). Tensile properties at all position/orientation combinations 

exceeded MMPDS values for plate products (Table 15) (11). Tensile strength at the t/8 position 

exceeded typical values (Table 15) in both L and LT orientations, but values at t/2 and 7t/8 were 

approximately 2 ksi lower than typical values. Elongations exceeded typical values for the L 

orientation at all through-thickness positions and for the LT orientation at t/2. Elongations for the 

LT orientation at t/8 and 7t/8 were within 1% of typical values. There was no clear trend of 

tensile properties with through-thickness position. The through-thickness tensile properties 
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exhibit the typical trend for aluminum alloys of increasing elongation with decreasing strength, 

although the difference in values is less than 2 ksi in strength and 2% in elongation. 

Based on the uniformity in tensile properties and the favorable comparison with typical and

MMPDS values, there was no detrimental effects of through-thickness grain size and texture 

variations on tensile properties.

Table 15. MMPDS design allowables and Alcoa typical tensile properties at room temperature 

for Al 2219-T62 plate (11), (19).

Alloy: Al 2219

Specification: QQ-A-250/30

Product Form: Sheet and plate

Temper -T62

 Thickness, in. 0.020 - 2.000

UTS YS E e 

Basis Orient. (ksi) (ksi) (Msi) (%)

L 54 36 -----

LT 54 36 d

L 55 37 -----

LT 55 37 -----

d e, % (S-basis): 0.020 - 0.039 in., 6%; 0.040 - 0.249 in., 7 %; 0.250 - 1.000 in., 8%; 1.001 - 2.000 in., 7%

Alloy: Al 2219

Product Form: Sheet and plate

Temper -T62

UTS YS E e 

Orient. (ksi) (ksi) (Msi) (%)

Typicals LT 58 40 10.5 12

Alcoa Green Letter: Alcoa Aluminum Alloys 2219 and 2419

10.5

MMPDS Design Properties

A

B
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6.5.2 Effect of Heat Treat Variant on Tensile Properties

The individual specimen tensile test results for the Al 2219-T62 plate heat treated using the 

standard and modified heat treatments are shown in Table 16 for the L, LT, and ST orientations. 

The average tensile property values and standard deviations for each set of specimens are shown 

in Table 17. Also shown in Table 18 for comparison are the overall average tensile properties 

for all coupon blanks tested from the Phase II testing of the spin formed aft bulkhead, which was 

processed using the modified heat treatment. Comparisons are made to isolate the effects of spin 

form deformation prior to T62 heat treatment (aft bulkhead vs. modified plate) and the effect of 

the quench rate (standard vs. modified plate).

Table 16. Tensile properties of Al 2219-T62 plate processed using standard (water quench) 

and modified (glycol quench) heat treatment as per AMS 2770 (18).

 Heat Specimen UTS YS E e(tot) 

Form Treat Number Orient. ksi ksi Msi %

Plate Standard (1)

T-PL-WQ-L-85

L

61.17 41.83 10.49 11.25

T-PL-WQ-L-86 61.27 42.20 10.48 9.41

T-PL-WQ-L-87 60.63 41.70 10.37 9.24

T-PL-WQ-LT-88

LT

57.17 40.77 10.32 9.26

T-PL-WQ-LT-89 58.45 39.62 10.38 9.87

T-PL-WQ-LT-90 59.80 41.07 10.36 7.76

T-PL-WQ-ST-91

ST

56.07 41.54 10.03 4.35

T-PL-WQ-ST-92 56.56 41.69 10.16 4.60

T-PL-WQ-ST-93 56.76 41.41 10.23 4.88

Plate Modified (2)

T-PL-GLQ-L-94

L

55.63 38.79 10.38 12.34

T-PL-GLQ-L-95 56.67 38.32 10.39 11.36

T-PL-GLQ-L-96 58.56 39.27 10.36 11.80

T-PL-GLQ-LT-97

LT

56.29 38.01 10.37 10.74

T-PL-GLQ-LT-98 58.88 39.50 10.34 8.91

T-PL-GLQ-LT-99 59.02 39.57 10.36 8.67

T-PL-GLQ-ST-100

ST

55.70 42.74 10.25 4.18

T-PL-GLQ-ST-101 55.54 42.96 10.33 4.13

T-PL-GLQ-ST-102 54.70 42.25 10.19 3.88

(1)

 Standard: Solution heat treat @ 995°F ± 10°F / 3 hours; water quench, and age @ 375°F ± 10°F / 36 hours.

(2)

 Modified: Solution heat treat @ 995°F ± 10°F / 3 hours; glycol quench, and age @ 375°F ± 10°F / 36 hours.
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Table 17. Average tensile properties and standard deviation values of Al 2219-T62 plate 

processed using standard and modified heat treatment as per AMS 2770 (18).

Orient.

UTS 

ksi

YS 

ksi

E 

Msi

e(tot) 

%

Std Mod Std Mod Std Mod Std Mod Heat Treat

L

61.03 56.95 41.91 38.79 10.45 10.38 9.97 11.83 Average

0.34 1.49 0.26 0.47 0.07 0.01 1.11 0.49 Std. Dev.

LT

58.47 58.06 40.48 39.03 10.35 10.36 8.96 9.44

1.31 1.54 0.77 0.88 0.03 0.01 1.09 1.13

ST

56.47 55.31 41.55 42.65 10.14 10.25 4.61 4.06

0.35 0.54 0.14 0.36 0.10 0.07 0.27 0.16

Table 18. Average tensile properties and standard deviation values for the spin formed Al 

2219-T62 aft bulkhead material.

Orient. 

UTS 

ksi 

YS 

ksi 

E 

Msi 

e 

1.00" GL 

%

L

57.1 38.2 10.5 12.14 Average

1.64 0.86 0.59 1.23 Std Dev.

LT

56.7 37.9 10.4 10.32

1.67 0.90 0.42 1.02

ST*

58.7 42.2 10.1 4.66

1.54 2.67 0.47 0.56

= 0.50” GL

The mechanical properties of age-hardenable aluminum alloys are dependent upon many factors, 

including the rate at which the material is cooled (quenched) after solution heat treatment. The L 

orientation exhibited the greatest difference in strength between the standard and modified plate

with UTS and YS being 3 to 4 ksi greater for the standard plate. Conversely the LT and ST 

orientations exhibited similar strengths between the two heat treat conditions. The strengths of 

the modified plate were similar to the average values for the aft bulkhead, indicating that

deformation associated with the spin forming process had no detrimental effect on tensile 

properties. This result indicates that the laboratory processed modified plate achieved similar 

quench rates to the full-scale commercially processed aft bulkhead. The YS variations in the 

modified plate were equivalent to those measured in the aft bulkhead, with ST YS being higher 

than L and LT, indicating that the higher ST YS is inherent in the plate and not the result of the 

spin forming process. The standard plate exhibited isotropic YS, with values for all orientations 

within 1 ksi. Both heat treat conditions resulted in tensile properties, which exceeded MMPDS 

A-basis design allowables for plate products. The L and LT YS and UTS of the standard plate 

exceeded typical values for plate. Values for the modified plate values were lower by less than 
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1 ksi. These results indicate that the modified heat treatment used by Spincraft for the aft 

bulkhead had no adverse effects on tensile properties.

6.6 Tensile Summary

Supplemental tensile test results confirmed that neither the grain size variations nor the quench 

rate adversely impacted tensile properties. Tensile strengths were uniform through the aft 

bulkhead thickness, with UTS and YS values within 1-2 ksi for all through-thickness positions 

(t/8 (IML), t/2, 7t/8 (OML) evaluated, and were comparable to the standard and modified plates. 

Tensile strengths were within 4 ksi for each orientation for the standard and modified plates. 

The YS in the standard plate was similar for all orientations. The YS in the ST orientation was 

higher than that for the L and LT orientations in both the aft bulkhead and modified plate 

indicating that this trend with orientation is inherent to this plate and not the result of the spin 

forming process.

The grain size in the aft bulkhead varied with distance from the pole and through the thickness of 

the plate, with larger grain sizes observed in regions of greater deformation, typically biased 

toward the OML and rim. Grain size was largest near the OML (7t/8), by a factor of three 

compared to the IML and t/2 positions based on grain area, likely associated with the combined 

stresses necessary to form the material over the mandrel. Through-thickness variations in 

material texture were observed, reflecting higher compression at the IML due to contact with the 

forming mandrel and greater overall deformation toward the OML. The variation in grain size 

stems from the complex and non-uniform deformation induced during spin forming as the plate 

is formed over the mandrel. The observed variations in grain size and texture did not adversely 

affect material properties.

The following findings and observation are provided in response to the questions posed in 

Table 10 for the supplemental tensile tests:

Tensile properties of the aft bulkhead were uniform with through-thickness position and 

orientation and were not adversely affected by the inhomogeneous microstructure

 Tensile strengths varied less than 5% with through-thickness position and 

specimen orientation, with strengths higher by 2-3 ksi at the t/8 position.

Tensile properties of the aft bulkhead were equivalent to the standard and modified plates 

indicating that there was no adverse effect of the slower quench rate used during 

processing.

Tensile properties in the ST orientation were higher than that for the L and LT 

orientations in both the aft bulkhead and modified plate indicating that this trend is 

inherent to the plate used in fabrication of the aft bulkhead and not a result of the spin 

forming process.

The higher tensile properties noted at the t/8 through-thickness position compared to the 

t/2 and 7t/8 positions may be related to the smaller grain size observed at that location.
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7.0 Supplemental Fracture Toughness Tests

Based on the results of the fracture toughness tests performed on the aft bulkhead (3) and the 

limited fracture toughness data available in the literature for comparison and interpretation of the 

results, supplemental fracture toughness tests were performed as per the test matrix shown in 

Table 19. Also shown in the table are the questions being addressed by these supplemental tests.

To isolate the effects of spin forming deformation on fracture behavior, remnant Al 2219-F plate 

from the spin forming blank was heat treated to the T62 temper using two heat treat variants as 

described in Section 6.3. Due to the lack of fracture toughness data for spin formed products, 

additional fracture toughness data was collected on remnant 2.5 inch thick Al 2219-T62 spin 

formed dome material. This dome was produced to manufacture tanks in support of the CPST 

Program (2), (5). Specific questions being addressed by the supplemental fracture toughness 

testing include whether the spin form processing compromises the fracture toughness of the 

material compared to standard wrought Al 2219-T62 plate and whether the slower quench used 

during heat treatment of the aft bulkhead, (i.e., the modified heat treat variant) has any effect on 

fracture toughness compared to the standard water quench rate.

Table 19. Supplemental fracture toughness test matrix and questions being addressed

(1)

 Standard: Solution heat treat @ 995°F ± 10°F / 3 hours; water quench, and age @ 375°F ± 10°F / 36 hours.

(2)

 Modified: Solution heat treat @ 995°F ± 10°F / 3 hours; glycol quench, and age @ 375°F ± 10°F / 36 hours.

7.1 Fracture Toughness Test Procedures

Fracture toughness testing of the wrought plate and spin formed CPST dome material was 

conducted in accordance with ASTM E1820 (20). Per this test method, the fracture toughness is 

quantified in terms of JIC, which is a measure of the fracture toughness of the material at the 

onset of stable crack extension. Fracture toughness characterization of the plate was conducted 

in three grain orientations, L-T, T-L and T-S

2

. For the spin formed CPST dome, specimens were 

 

2

For the standard and modified plate material, an error was made in the cut plan and specimen layout drawings 

resulting in fracture toughness specimens being machined in the T-S orientation instead of S-T orientation.
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sectioned from the rim and pole regions, and fracture toughness data was collected in the S-T 

orientation only. The test orientation designation first identifies the loading direction and is 

followed by the crack growth orientation as they relate to the grain orientation of the material. 

Fracture toughness was measured using a compact tension (C(T)) specimen configuration. Two 

specimen designs were used; one for the L-T and T-L orientations (Figure 24) and one for the 

S-T and T-S orientations (Figure 25). All specimens were machined from the coupon blanks 

such that the test section was located at the mid-plane thickness (t/2) of the coupon blank. Two 

replicate tests were conducted for each grain orientation as per the test matrix shown in Table 19. 

The test apparatus used for fracture toughness testing is shown in Figure 26.

Figure 24. JIC fracture toughness specimen design; L-T and T-L orientations. All dimensions are in 

inches (20).

 

A

DETAIL A

2.500

2.000

1.000

1.00 u0.01

i 0.002 -Ai 0.002 -A0.800

0.750 u0.005

0.010 +0.000/ -0.004 C/L

0.200 u0.001

0.520

0.200

2x O 0.500 +0.005 / -0.000

0.100

30°

60°

0.800

i 0.002 -A-3 xxx

3 xxx

5

4

6

5

1.195

2.400
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Figure 25. JIC fracture toughness specimen design; S-T and T-S orientations. All dimensions are 

in inches (20).

Figure 26. JIC fracture toughness specimen and test apparatus.

i 0.002 -Ai 0.002 -A- C/L i 0.002 -A3 xxx

3 xxx

5

4

6

1.250

1.000

0.60

0.60 A

DETAIL A

2x O 0.250 +.005 / -0.000

0.010 +0.000 /-0.004

0.200

30° 0.100 0.145

0.500

60°

0.400

-A- 1
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7.2 Fracture Toughness Test Results

7.2.1 Aft Bulkhead Fracture Toughness Results

To assist in the comparison and interpretation of the supplementary fracture toughness results, 

the aft bulkhead data generated during the Phase II test program are presented here for reference. 

The aft bulkhead cut plan with the location of coupon blanks highlighted in yellow from which 

fracture toughness specimens were excised for fracture toughness testing is shown in Figure 27. 

Table 20 shows the size and location of these coupon blanks with respect to the original plate 

rolling direction and distance from the aft bulkhead pole to the coupon blank center point. These 

coupon blank locations were designed to determine uniformity of fracture toughness properties 

throughout the aft bulkhead and were evaluated along selected meridian and circumferential 

lines.

A summary of the fracture toughness test results for the spin formed Al 2219-T62 aft bulkhead 

material is provided in Table 21 (3). All but five specimens were valid per the ASTM E1820 

specification. In each case the invalidity was related to the difference between the estimated 

crack extension and the measured crack extension. In each case the deviation was considered 

minor and inconsequential to the toughness results.

Figure 27. Aft bulkhead cut plan showing the location of the fracture toughness test coupon 

blanks highlighted in yellow.
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Table 20. Fracture toughness coupon blank locations and orientations.

Longitudinal Transverse Meridian Arc Length

Coupon Dimension, Dimension, Angle , from dome CL

Blank in. in. degrees in.

M1 14 12 9° 54-5/8

M2 14 12 13° 36

M3 14 12 30° 16-1/8

M4 14 12 277° 55-1/2

M5 14 12 281° 35-7/8

M6 14 12 225° 35-1/8

Coupon Blank Size Coupon Center Point
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Table 21. Summary of fracture toughness data for the spin formed Al 2219-T62 aft bulkhead 

material (3).

* Not valid JIC value.

Specimen Coupon JIC KJIC 

ID Blank in-lb/in2 ksi√in

CP-406-191 105.6 35.1

CP-406-193 114.8 36.6

CP-406-196 91.5* 32.7

CP-406-198 90.6* 32.5

CP-406-201 62.6 27.0

CP-406-203 62.2 26.9

CP-406-206 115.1 36.6

CP-406-208 112.8 36.3

CP-406-211 86.2* 31.7

CP-406-213 91.0 32.6

CP-406-216 89.9 32.4

CP-406-218 56.0 25.6

CP-406-221 117.2 37.0

CP-406-223 125.7 38.3

CP-406-226 84.9 31.5

CP-406-228 93.1 32.9

CP-406-231 66.0 27.7

CP-406-233 90.7 32.5

CP-406-236 102.5 34.6

CP-406-238 99.1 34.0

CP-406-241 86.0 31.7

CP-406-243 93.4* 33.0

CP-406-246 78.0 30.1

CP-406-248 50.9 24.4

CP-406-251 108.4 35.5

CP-406-253 107.3 35.4

CP-406-256 86.3 31.7

CP-406-258 85.6 31.6

CP-406-261 67.8 28.1

CP-406-263 77.4 30.0

CP-406-266 118.7 37.2

CP-406-268 114.0 36.4

CP-406-271 86.5 31.7

CP-406-273 85.0 31.5

CP-406-276 59.1 26.2

CP-406-278 57.4* 25.9

M6

L-T

T-L

S-T

M3

L-T

T-L

S-T

M4

L-T

T-L

S-T

Orient.

M5

L-T

T-L

S-T

M1

L-T

T-L

S-T

M2

L-T

T-L

S-T
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7.2.2 Supplemental Fracture Toughness Test Results

A summary of the supplemental study fracture toughness test results for the Al 2219-T62 

wrought plate and spin formed CPST dome material is provided in Table 22. For the wrought 

plate material, all but three specimens were valid per the ASTM E1820 specification. In each 

case, the invalidity was related to an inaccurate estimate of the compliance-based predicted crack 

extension versus the specimen crack extension. The deviations were low and inconsequential to 

the toughness results. For the dome material, none of the specimens were valid. These 

invalidities were primarily related to an insufficient number of data points collected during crack 

extension. This made it difficult to determine definitive R-curve behavior, but the tests did 

generate sufficient data to estimate a K-based fracture toughness value.

Table 22. Summary of fracture toughness data for Al 2219-T62 wrought plate and spin form 

dome material.

Material 

Source

Location / 

Heat Treat

Specimen 

ID Orient.

JQ KJQ

Valid JIc

(in-lb/in2) (ksi√in)

Plate Standard (1)

CP-406A-25 T-L 107.4 36.5 Yes

CP-406A-27 T-L 98.5 35 Yes

CP-406A-29 L-T 102.7 35.9 Yes

CP-406A-31 L-T 113.9 37.8 Yes

CP-406A-33 T-S 123.4 38.8 No

CP-406A-35 T-S 144.3 42 Yes

Plate Modified (2)

CP-406A-1 T-L 112.5 35.3 Yes

CP-406A-3 T-L 77.4 30 Yes

CP-406A-5 L-T 109.9 37.6 No

CP-406A-7 L-T 112.3 36.2 Yes

CP-406A-9 T-S 157.1 42.4 Yes

CP-406A-11 T-S 136.5 39.5 No

CPST 

Dome Pole

CP-406A-61 S-T 61.6 26.3 No

CP-406A-62 S-T 47.7 23.1 No

CPST 

Dome Rim

CP-406A-73 S-T 80 29.7 No

CP-406A-74 S-T 100.8 33.3 No

(1) Standard: Solution heat treat @ 995°F ± 10°F / 3 hours; water quench, and age @ 375°F ± 10°F / 36 hours.

(2) Modified: Solution heat treat @ 995°F ± 10°F / 3 hours; glycol quench, and age @ 375°F ± 10°F / 36 hours.
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7.2.3 Effect of Heat Treat Variant on Fracture Toughness

The supplemental study fracture toughness data listed in Table 22 for the standard and modified 

plates is plotted in Figure 28 as a function of heat treat variant and test orientation. Fracture 

toughness comparisons were based on KJQ values listed in Table 22. The fracture toughness of 

the standard and modified plates was exemplary, with fracture toughness values, KJQ, in the T-L, 

L-T, and T-S greater than or equal to 30 ksi√in. Fracture toughness values trended as expected 

with respect to orientation, increasing in toughness from the T-L to L-T to T-S orientation. For a 

given orientation, the fracture behavior did not vary with heat treatment. All of the standard and 

modified plate data exhibited rising R-curve behavior, indicative of stable tearing capability as 

shown in the typical R-curves presented in Figure 29 and Figure 30. This behavior is consistent 

with the R-curve behavior during fracture toughness testing of material from the spin formed aft 

bulkhead, which was heat treated using the modified heat treat variant. 

Figure 28. Fracture toughness data summary for wrought Al-2219-T62 plate heat treated using 

standard and modified heat treat variants.
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Figure 29. J-R curve and fracture surface of specimen CP-406-27 from standard heat treat Al 2219-

T62 wrought plate; T-L orientation.
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Figure 30. J-R curve and fracture surface of specimen CP-406A-1 from modified heat treat Al 2219-

T62 wrought plate; T-L orientation.

Fracture toughness data in the rolling plane (T-L and L-T) from the standard and modified plates

are compared to fracture toughness data from the Phase II study on the spin formed aft bulkhead 

(3) in Figure 31 and Figure 32. The data shown for the aft bulkhead represent all data from the 

various meridian and arc length locations. The L-T fracture toughness of the standard and 

modified plates are equivalent and the aft bulkhead was comparable to the wrought plate 

material. For the T-L orientation, the modified plate exhibited higher variability than was 

observed in the standard plate and the aft bulkhead material. The range of the modified plate and 

aft bulkhead data overlap and can be considered equivalent. Based on average data, the T-L 
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fracture toughness performance of the standard plate may be judged as better than the modified 

plate and spin formed aft bulkhead.

Figure 31. Fracture toughness of standard and modified heat treat wrought plate vs. spin formed aft 

bulkhead; L-T orientation.

15

20

25

30

35

40

KJQ (ksi√in)

L-T Fracture Toughness

Standard HT Plate Modified HT Plate Spin Formed APVBH
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Figure 32. Fracture toughness of standard and modified heat treat wrought plate vs. spin formed aft 

bulkhead; T-L orientation.

7.2.4 Comparison with Other Al 2219-T62 Spin Formed Product

All of the data for the CPST dome exhibited rising R-curve behavior, indicative of stable tearing 

capability as shown in the typical R-curve presented in Figure 33. This behavior is consistent 

with the R-curve behavior exhibited by material from the spin formed aft bulkhead. The aft 

bulkhead and CPST dome were fabricated by Spincraft and received the modified heat treatment.

Fracture toughness data in the S-T orientation from the CPST dome is compared to fracture 

toughness data from the original study on the spin formed aft bulkhead (3) in Figure 34. 

Individual test results from the spin formed aft bulkhead are shown for coupon blanks near the 

rim (M3); membrane (M2, M5, and M6); and pole (M1 and M4). (See aft bulkhead cut plan 

shown in Figure 27 for location of coupon blanks.) The S-T fracture toughness measured at the 

rim location in the CPST dome was higher than that for the pole, based on average and 

individual test results. A similar trend was observed in the aft bulkhead, but the change in 

toughness from pole to rim was less in magnitude than in the CPST dome. Based on average 

15

20

25

30

35

40

KJQ (ksi√in)

T-L Fracture Toughness

Standard HT Plate Modified HT Plate Spin Formed APVHB
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values, toughness at the rim was similar for both products, but the toughness at the pole was 

slightly lower for the CPST dome than the aft bulkhead. Differences in toughness behavior with 

location may be due to variations in spin forming deformation and grain size. Material from the 

CPST dome was not available for a detailed forming or microstructural assessment, so a 

conclusive explanation for the fracture toughness differences would require further study. It 

should be noted that while the aft bulkhead and CPST dome were produced by Spincraft 

differences in size, shape, and thickness will affect the deformation imparted to the material and 

consequently material properties. In addition, during examination of the SCC specimens it was 

noted that the grain size in the CPST dome was visually larger than that for the aft bulkhead,

which may have contributed to the differences in toughness behavior.

Figure 33. J-R curve and fracture surface of specimens CP-406A-62 from the pole region of the Al 

2219-T62 spin formed CPST dome; S-T orientation.
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Figure 34. Fracture toughness of spin formed CPST dome vs. aft bulkhead; S-T orientation.

7.3 Fracture Toughness Summary

Spin form fabrication did not have adverse effects on the fracture behavior of the material. The 

aft bulkhead fracture toughness values and fracture behavior were consistent with the behavior of 

the Al 2219-T62 wrought plate processed using the standard and modified heat treatments. The 

supplementary fracture toughness tests of the wrought plate showed room temperature in-plane 

toughness values ranged from 31 to 38 ksi√in. The material was capable of stable crack 

extension and exhibited rising R-curve behavior. There was little to no difference in fracture 

behavior with heat treat variant. In comparison, the in-plane (L-T and T-L) toughness values for 

the aft bulkhead ranged from 31.5 to 38.3 ksi√in, and the material exhibited rising R-curve 

behavior.

The supplementary fracture toughness tests of the spin formed CPST dome showed that the S-T 

toughness was similar to the aft bulkhead toughness. The trends observed with location were 

similar in both products with toughness higher near the rim than the pole. Toughness values 

were similar for both products near the pole and toughness was slightly lower in the CPST dome 

near the rim. Differences in toughness values between the CPST dome and aft bulkhead may be 
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due to differences in the level of deformation imparted which arise due to differences in size, 

shape, and thickness of the two products. Toughness in the S-T orientation was greater than or 

equal to 23 ksi√in for the CPST dome, and 27 ksi√in for the aft bulkhead. Both products 

exhibited rising R-curve behavior indicative of stable tearing capability. The positive fracture 

toughness attributes from the CPST dome, a comparable product form to the aft bulkhead, give 

further credence to the spin forming process as a viable fabrication process for MPCV aft 

bulkhead.

The following findings are provided in response to the questions posed in Table 19 for the 

supplemental fracture toughness tests.

The fracture toughness of the aft bulkhead was comparable to the standard and modified 

plates.

Fracture toughness of the standard and modified plates was essentially equivalent 

indicating that there was no adverse effect of the slower quench rate used during 

processing.

Fracture toughness of the aft bulkhead and CPST dome were equivalent and exhibited 

overall average toughness values of 25 ksi√in and stable tearing.
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8.0 Findings, Observations, and NESC Recommendations

The following findings, observations, and NESC recommendations are based on the results of a 

supplemental study for which the main objective was to determine whether there are technical 

obstacles relative to the spin forming a single piece aft bulkhead.

The Phase II M&P studies did not identify any potential insurmountable technical issues that 

would preclude spin forming the MPCV aft bulkhead. The potential benefits of spin forming an 

Al 2219 aft bulkhead include reduced weight and production costs, which are associated with 

eliminating welds and weld lands, and improved performance and design margins.

8.1 Findings

The following findings are provided in response to the questions posed in Table 19 for the 

supplemental tests:

A retest of coupon blank M10 showed that the single specimen failure at 50% YS 

exposure stress was not repeatable.

Material from coupon blank M10 and the adjacent blank, J2, passed the 30-

day 3.5% NaCl alternate immersion exposure at 50%YS exposure stress and 

had acceptable residual strength ratios.

Post-exposure microstructural examination showed SCC in both the Phase II 

tests of coupon blank M10 and the supplemental tests of coupon blank M10 

and J2.

Aft bulkhead material from coupon blank M10 passed the 30-day 3.5% NaCl alternate 

immersion exposure at exposure stress levels based on MMPDS for plate and measured 

ST YS values for the aft bulkhead.

Material from additional locations in the aft bulkhead passed the 30-day 3.5% NaCl 

alternate immersion exposure at exposure stress levels based on MMPDS YS values for 

plate and exhibited residual strengths above minimum required values.

 Residual strength values were higher at the rim as compared with the pole and 

membrane locations.

The combined spin forming process and associated modified heat treat practice reduces

the SCC resistance compared with wrought plate, likely related to the slower quench rate 

associated with the modified heat treatment.

 While no SCC failures occurred during 30-day alternate immersion exposure 

in a 3.5% NaCl environment, post-exposure metallurgical evaluation showed 

SCC in the spin formed aft bulkhead and CPST dome materials subjected to 

the modified heat treatment.

 Remnant plate processed using the modified heat treatment exhibited lower 

post-exposure residual strength values than standard plate.
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 Post-exposure metallurgical evaluation showed SCC in the modified plate. 

No evidence of SCC was found in the standard plate.

The SCC resistance of the Al 2219-T62 spin formed aft bulkhead and CPST dome were 

similar indicating that the SCC behavior observed is likely representative of similarly 

processed Al 2219-T62 spin formed products.

Tensile properties of the aft bulkhead were uniform with through-thickness position and 

orientation and were not adversely affected by the inhomogeneous microstructure 

 Tensile strengths varied less than 5% with through-thickness position and 

specimen orientation, with strengths higher by 2 to 3 ksi at the t/8 position.

Tensile properties of the aft bulkhead were equivalent to the standard and modified plates

indicating that there was no adverse effect of the slower quench rate used during 

processing.

Tensile properties in the ST orientation were higher than that for the L and LT 

orientations in both the aft bulkhead and modified plate indicating that this trend is 

inherent to the plate used in fabrication of the aft bulkhead and not a result of the spin 

forming process.

The fracture toughness of the aft bulkhead was comparable to the standard and modified 

plates.

Fracture toughness of the standard and modified plates was essentially equivalent 

indicating that there was no adverse effect of the slower quench rate used during 

processing.

Fracture toughness of the aft bulkhead and CPST dome were equivalent and exhibited 

overall average toughness values of 25 ksi√in and stable tearing.

8.2 Observations

The following observations were identified:

The SCC data for the aft bulkhead provides insight about the SCC resistance of the spin 

formed Al 2219-T62 material, but is insufficient to establish a SCC threshold stress level.

 Testing in this study sampled one spin formed aft bulkhead and one material 

lot. Establishing a threshold requires testing of multiple serial production aft 

bulkheads and multiple material lots. 

 Evidence of SCC was observed for all non-zero exposure stress levels 

indicating that the SCC threshold is below the minimum stress level used in 

this study.

Grain size in the CPST dome was larger than in the aft bulkhead, which may have 

contributed to a greater extent of pitting and lower percent tensile strength retained and 

residual strength ratios.
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The higher tensile properties noted at the t/8 through-thickness position compared to the 

t/2 and 7t/8 positions may be related to the smaller grain size observed at that location.

8.3 NESC Recommendations

The following NESC recommendations were identified and directed towards the MPCV 

Program:

R-1. Perform additional SCC testing on spin formed Al 2219-T6 products to establish a 

threshold stress level for SCC and to determine a maximum allowable service stress.

(O-1)

 Additional testing should be performed on multiple articles from initial serial 

production and should sample multiple material lots.

 Exposure stress levels should be successively reduced until there is no 

evidence of stress corrosion.

R-2. Perform heat treatment studies to determine whether a faster quench rate can be achieved 

that improves SCC resistance without compromising residual stress and distortion 

control. (F-4)

9.0 Acronyms List

a Crack Length

AMA Analytical Mechanics Associates

AMS Aerospace Material Specifications

ASTM American Society for Testing and Materials

C(T) Compact Tension

CPST Cryogenic Propellant Storage and Transfer

e, etotal Elongation, %

E Modulus of Elasticity

EBSD Electron Backscatter Diffraction

EFT-1 Exploration Flight Test

EM-1 Exploration Mission

FPVBH Forward Pressure Vessel Bulkhead

GL Gage Length

IML Inner Mold Line

in Inch

ipm Inches Per Minute

Jq Provisional J Integral

J J Integral

K Crack Tip Stress Intensity, ksi√in

KJQ Provisional Fracture Toughness

ksi Kilopound Per Square Inch, 103
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L Longitudinal (direction parallel to plate rolling direction)

LaRC Langley Research Center

LM Lockheed Martin

LT, T Long Transverse (direction perpendicular to the longitudinal (rolling) direction 

and in the rolling plane)

M&P Materials and Processes

MMPDS Metallic Material Properties Development and Standardization

MPCV Multi-Purpose Crew Vehicle

MSFC Marshall Space Flight Center

Msi Megapound Per Square Inch, 106

MUA Materials Usage Agreement

NaCl Sodium Chloride

NASA National Aeronautics and Space Administration

NESC NASA Engineering and Safety Center

OML Outer Mold Line

psi Pounds Per Square Inch

R-curve Resistance Curve

S, ST Short Transverse (through-thickness direction of the plate perpendicular to both 

longitudinal and long transverse directions)

SCC Stress Corrosion Crack

SLS Space Launch System

t Thickness

UTS Ultimate Tensile Strength

UTSf Residual Strength of the Exposed Specimen

UTSi Average Ultimate Tensile Strength for the Unexposed Specimens

UTSo Averaged Residual Strength of Non-Stressed and Exposed Specimens

UTSs Residual Strength of Stressed and Exposed Specimen

YS Yield Strength

 Average Linear Stress

 Average Linear Strain
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10.0 References

1. M. S. Domack, E. K. Hoffman. I. S. Raju, R. S. Piascik. Spin Forming Aluminum Alloy Crew 

Module (CM) Metallic Forward Pressure Vessel Bulkhead (FPVBH) – Phase 1. February 

2014. NESC-RP-12-00776; NASA/TM-2014-218163.

2. Exploration Mission (EM-1) Integrated Structure SSDR, Crew Module Structures Crew Cabin 

Structure Overview. Middleton, Frank. s.l.: Orion MPCV, September 9, 2015. Integrated 

Structures SSDR; 09/08/15-09/18/15. ITAR- Export Controlled.

3. Hoffman, E.K., Domack, M.S., et al. Spin Forming Aluminum Crew Module (CM) Metallic Aft 

Pressure Vessel Bulkhead (APVBH) – Phase II. Hampton, VA: National Aeronautics and 

Space Administration, Langley Research Center, January, 2015. NESC-RP-13-00884; 

NASA/TP-2015-218674.

4. Cryogenic Propellant Storage and Transfer Project. s.l.: National Aeronautics and Space 

Administration. NASA Fact Sheet PS–01038–06–0713.

5. McGill, P., Talton, M. Materials and Processes Laboratory Flash Report, MPFR-14-019: 

CPST Spun Dome Material Characterization, July, 2014. Huntsville, AL: NASA Marshall 

Space Flight Center, July 2014. MPFR-14-09.

6. MSFC-STD-3029, Rev. A: Guidelines for the Selection of Metallic Materials for Stress 

Corrosion Cracking Resistance in Sodium Chloride Environments. Huntsville, AL: NASA 

MSFC, 2005. MSFC-3029A.

7. ASTM G44 -Standard Practice for Exposure of Metals and Alloys by Alternate Immersion in 

Neutral 3.5 % Sodium Chloride Solution. West Conshohocken, PA: ASTM International, 

2013. G44.

8. ASTM G47 - Standard Test Method for Determining Susceptibility to Stress-Corrosion 

Cracking of 2XXX and 7XXX Aluminum Alloy Products1. West Conshohocken, PA: ASTM 

International, 2011. G47.

9. ASTM G49 - Standard Practice for Preparation and Use of Direct Tension Stress-Corrosion 

Test Specimens. West Conshohocken, PA: ASTM International, 2011. G49.

10. ASTM G64 - Standard Classification of Resistance to Stress-Corrosion Cracking of HeatTreatable Aluminum Alloys. West Conshohocken, PA: ASTM International, 2013. G64.

11. Metallic Materials Properties Development and Standardization (MMPDS) Handbook. 

Columbus, OH: Battelle Memorial Institute, April 2013. MMPDS-08.

12. ASTM E8 - Standard Test Methods for Tension Testing of Metallic Materials. West 

Conshohocken, PA: ASTM International, 2011. E8.

13. Colvin, E.L. and Emptage, M.R. The Breaking Load Method: Results and Statistical 

Modification from the ASTM Interlaboratory Program. New Methods for Corrosion Testing 

of Aluminum Alloys, ASTM STP 1134. West Conshohocken, PA: ASTM International, 1992, 

pp. 82-100.

14. Sprowls, D.O., Summerson, T.J., Ugiansky, G. M., Epstein, S.G., and Craig, H.L., Jr.,. 

“Evaluation of a Proposed Standard Method for Testing for Susceptibilty to Stress-Corrosion 

Cracking of High-Strength 7xxx Series Aluminum Alloy Products,”. [ed.] Jr., editor H.L. 
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Craig. Stress Corrosion – New Approaches, ASTM STP 610. Philadelphia, PA: American 

Society for Testing and Materials, 1976, pp. 3-31.

15. ASM Handbook Volume 13 Corrosion. Metals Park, OH: ASM International, 1987. 

pp. 590-591. Vol. 13, Corrosion of Aluminum and Aluminum Alloys.

16. Runge, Manfred. Spinning and Flow Forming. [trans.] David H. Pollitt. s.l.: verlag modern 

industrie AG, 1993. Original title: Drücken and Drückwalzen.

17. Influence of quench and heating rates on the ageing response of an Al–Zn–Mg–(Zr) alloy. A. 

Deschamps, Y. Bre ́chet. 1998, Materials Science and Engineering , Vol. A251, pp. 200-207.

18. AMS 2770H. Aerospace Materials Specification: Heat treatment of wrought aluminum alloy 

parts. Warrendale, PA: SAE International, 2006. AMS 2770H.

19. Mayer, L. W. Alcoa Green Letter 176 - Alcoa Aluminum Alloy 2219. New Kensington, PA: 

Aluminum Company of America, Applications Engineering Division, June 1957. 176.

20. ASTM E1820 - Standard Test Method for Measurement of Fracture Toughness. West 

Conshohocken, PA: American Society for Testing and Materials, 2013. E1820.
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11.0 Appendices

11.1 Appendix A: Photomicrographs of Specimens from the Phase II Stress 

Corrosion Tests; LT Orientation

#2_unetched_m01_20x.jpg #2_unetched_m02_50x.jpg

#2_etched_m03_20x.jpg #2_etched_m04_50x.jpg

Coupon blank: M7

Specimen No.: 2

Orientation: LT

Applied stress (% YS): 0

Applied stress (ksi): 0

Failed?: No

SCC?: No

(a) 0% YS
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#5_unetched_m01_20x.jpg #5_unetched_m02_50x.jpg

#5_etched_m03_20x.jpg #5_etched_m04_50x.jpg

Coupon blank: M7

Specimen No.: 5

Orientation: LT

Applied stress (% YS): 50, based on M7 average LT YS

Applied stress (ksi): 18.32

Failed?: No

SCC?: No

(b) 50% YS
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#8_unetched_m01_20x.jpg #8_unetched_m02_50x.jpg

#8_etched_m03_20x.jpg #8_etched_m04_50x.jpg

Coupon blank: M7

Specimen No.: 8

Orientation: LT

Applied stress (% YS): 75, based on M7 average LT YS

Applied stress (ksi): 27.48

Failed?: No

SCC?: No

(c) 75% YS
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#12_unetched_m01_20x.jpg #12_unetched_m02_50x.jpg

#12_etched_m03_20x.jpg #12_etched_m04_50x.jpg

Coupon blank: M7

Specimen No.: 12

Orientation: LT

Applied stress (% YS): 90, based on M7 average LT YS

Applied stress (ksi): 32.98

Failed?: No

SCC?: No

(d) 90% YS

Figure A-1. Photomicrographs of SCC specimens from aft bulkhead coupon blank M7 following 

30-day 3.5% NaCl alternate immersion exposure at applied stress levels of (a) 0% YS; 

(b) 50% YS; (c) 75% YS; and (d) 90% YS.
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#44_unetched_m01_20x.jpg #44_unetched_m02_50x.jpg

#44_etched_m03_20x.jpg #44_etched_m04_50x.jpg

Coupon blank: M8

Specimen No.: 44

Orientation: LT

Applied stress (% YS): 0

Applied stress (ksi): 0

Failed?: No

SCC?: No

(a) 0% YS
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#47_unetched_m01_20x.jpg #47_unetched_m02_50x.jpg

#47_etched_m03_20x.jpg #47_etched_m04_50x.jpg

Coupon blank: M8

Specimen No.: 47

Orientation: LT

Applied stress (% YS): 50, based on M8 average LT YS

Applied stress (ksi): 19.39

Failed?: No

SCC?: No

(b) 50% YS
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#50_unetched_m01_20x.jpg #50_unetched_m02_50x.jpg

#50_etched_m03_20x.jpg #50_etched_m04_50x.jpg

Coupon blank: M8

Specimen No.: 50

Orientation: LT

Applied stress (% YS): 75, based on M8 average LT YS

Applied stress (ksi): 29.90

Failed?: No

SCC?: No

(c) 75% YS
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#54_etched_m03_20x.jpg #54_etched_m04_50x.jpg

Coupon blank: M8

Specimen No.: 54

Orientation: LT

Applied stress (% YS): 90, based on M8 average LT YS

Applied stress (ksi): 34.90

Failed?: No

SCC?: No

(d) 90% YS

Figure A-2. Photomicrographs of SCC specimens from aft bulkhead coupon blank M8 following 

30-day 3.5% NaCl alternate immersion exposure at applied stress levels of (a) 0% YS; 

(b) 50% YS; (c) 75% YS; and (d) 90% YS.
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#86_unetched_m01_20x.jpg #86_unetched_m02_50x.jpg

#86_etched_m03_20x.jpg #86_etched_m04_50x.jpg

Coupon blank: M9

Specimen No.: 86

Orientation: LT

Applied stress (% YS): 0

Applied stress (ksi): 0

Failed?: No

SCC?: No

(a) 0% YS
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#89_unetched_m01_20x.jpg #89_unetched_m02_50x.jpg

#89_etched_m03_20x.jpg #89_etched_m04_50x.jpg

Coupon blank: M9

Specimen No.: 89

Orientation: LT

Applied stress (% YS): 50, based on M9 average LT YS

Applied stress (ksi): 19.84

Failed?: No

SCC?: No

(b) 50% YS
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#92_unetched_m01_20x.jpg #92_unetched_m02_50x.jpg

#92_etched_m03_20x.jpg #92_etched_m04_50x.jpg

Coupon blank: M9

Specimen No.: 92

Orientation: LT

Applied stress (% YS): 75, based on M9 average LT YS

Applied stress (ksi): 29.76

Failed?: No

SCC?: No

(c) 75% YS
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Coupon blank: M9

Specimen No.: 96

Orientation: LT

Applied stress (% YS): 90, based on M9 average LT YS

Applied stress (ksi): 35.71

Failed?: No

SCC?: No

(d) 90% YS

Figure A-3. Photomicrographs of SCC specimens from aft bulkhead coupon blank M9 following 

30-day 3.5% NaCl alternate immersion exposure at applied stress levels of (a) 0% YS; 

(b) 50% YS; (c) 75% YS; and (d) 90% YS.
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

118 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#170_etched_m03_20x.jpg #170_etched_m04_50x.jpg

Coupon blank: M10

Specimen No.: 170

Orientation: LT

Applied stress (% YS): 0

Applied stress (ksi): 0

Failed?: No

SCC?: No

(a) 0% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

119 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#173_etched_m03_20x.jpg #173_etched_m04_50x.jpg

Coupon blank: M10

Specimen No.: 173

Orientation: LT

Applied stress (% YS): 50, based on M10 average LT YS

Applied stress (ksi): 18.94

Failed?: No

SCC?: No

(b) 50% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

120 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#176_etched_m03_20x.jpg #176_etched_m04_50x.jpg

Coupon blank: M10

Specimen No.: 176

Orientation: LT

Applied stress (% YS): 75, based on M10 average LT YS

Applied stress (ksi): 28.40

Failed?: No

SCC?: No

(c) 75% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

121 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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Coupon blank: M10

Specimen No.: 180

Orientation: LT

Applied stress (% YS): 90, based on M10 average LT YS

Applied stress (ksi): 34.08

Failed?: No

SCC?: No

(d) 90% YS

Figure A-4. Photomicrographs of SCC specimens from aft bulkhead coupon blank M10 following 

30-day 3.5% NaCl alternate immersion exposure at applied stress levels of (a) 0% YS; 

(b) 50% YS; (c) 75% YS; and (d) 90% YS.
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

122 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

11.2 Appendix B: Photomicrographs of Specimens from the Phase II Stress 

Corrosion Tests; ST Orientation

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#23_etched_m03_20x.jpg #23_etched_m04_50x.jpg

Coupon blank: M7

Specimen No.: 23

Orientation: ST

Applied stress (% YS): 0

Applied stress (ksi): 0

Failed?: No

SCC?: No

(a) 0% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

123 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#26_etched_m03_20x.jpg #26_etched_m04_50x.jpg

Coupon blank: M7

Specimen No.: 26

Orientation: ST

Applied stress (% YS): 50, based on M7 average ST YS

Applied stress (ksi): 21.60

Failed?: No

SCC?: No

(b) 50% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

124 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#29_etched_m03_20x.jpg #29_etched_m04_50x.jpg

Coupon blank: M7

Specimen No.: 29

Orientation: ST

Applied stress (% YS): 75, based on M7 average ST YS

Applied stress (ksi): 32.4

Failed?: Yes, 30 days

SCC?: Yes; circled in red

(c1) 75% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

125 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#30_etched_m03_20x.jpg #30_etched_m04_50x.jpg

Coupon blank: M7

Specimen No.: 30

Orientation: ST

Applied stress (% YS): 75, based on M7 average ST YS

Applied stress (ksi): 32.4

Failed?: Yes, 28 days

SCC?: Yes; circled in red

(c2) 75% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

126 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#31_etched_m03_20x.jpg #31_etched_m04_50x.jpg

Coupon blank: M7

Specimen No.: 31

Orientation: ST

Applied stress (% YS): 75, based on M7 average ST YS

Applied stress (ksi): 32.4

Failed?: Yes, 26 days

SCC?: Yes; circled in red

(c3) 75% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

127 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#33_etched_m03_20x.jpg #33_etched_m04_50x.jpg

Coupon blank: M7

Specimen No.: 33

Orientation: ST

Applied stress (% YS): 90, based on M7 average ST YS

Applied stress (ksi): 38.88

Failed?: Yes, 28 days

SCC?: Yes; circled in red

(d1) 90% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

128 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#34_etched_m03_20x.jpg #34_etched_m04_50x.jpg

Coupon blank: M7

Specimen No.: 34

Orientation: ST

Applied stress (% YS): 90, based on M7 average ST YS

Applied stress (ksi): 38.88

Failed?: Yes, 26 days

SCC?: Yes; circled in red

(d2) 90% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

129 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#35_etched_m03_20x.jpg #35_etched_m04_50x.jpg

Coupon blank: M7

Specimen No.: 35

Orientation: ST

Applied stress (% YS): 90, based on M7 average ST YS

Applied stress (ksi): 38.88

Failed?: Yes, 26 days

SCC?: Yes; circled in red

(d3) 90% YS

Figure B-1. Photomicrographs of SCC specimens from aft bulkhead coupon blank M7 following 

30-day 3.5% NaCl alternate immersion exposure at applied stress levels of (a) 0% YS; 

(b) 50% YS; (c1, c2, c3) 75% YS; and (d1, d2, d3) 90% YS.
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

130 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#65_etched_m03_20x.jpg #65_etched_m04_50x.jpg

Coupon blank: M8

Specimen No.: 65

Orientation: ST

Applied stress (% YS): 0

Applied stress (ksi): 0

Failed?: No

SCC?: No

(a) 0% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

131 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#68_etched_m03_20x.jpg #68_etched_m04_50x.jpg

Coupon blank: M8

Specimen No.: 68

Orientation: ST

Applied stress (% YS): 50, based on M8 average ST YS

Applied stress (ksi): 21.87

Failed?: No

SCC?: No

(b) 50% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

132 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#71_etched_m03_20x.jpg #71_etched_m04_50x.jpg

Coupon blank: M8

Specimen No.: 71

Orientation: ST

Applied stress (% YS): 75, based on M8 average ST YS

Applied stress (ksi): 32.80

Failed?: Yes, 30 days

SCC?: No

(c1) 75% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

133 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#73_etched_m03_20x.jpg #73_etched_m04_50x.jpg

Coupon blank: M8

Specimen No.: 73

Orientation: ST

Applied stress (% YS): 75, based on M8 average ST YS

Applied stress (ksi): 32.80

Failed?: Yes, 27 days

SCC?: Yes; circled in red

(c2) 75% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

134 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#75_etched_m03_20x.jpg #75_etched_m04_50x.jpg

Coupon blank: M8

Specimen No.: 75

Orientation: ST

Applied stress (% YS): 90, based on M8 average ST YS

Applied stress (ksi): 39.36

Failed?: Yes, 26 days

SCC?: Yes; circled in red

(d1) 90% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

135 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#76_etched_m03_20x.jpg #76_etched_m04_50x.jpg

Coupon blank: M8

Specimen No.: 76

Orientation: ST

Applied stress (% YS): 90, based on M8 average ST YS

Applied stress (ksi): 39.36

Failed?: Yes, 30 days

SCC?: No

(d2) 90% YS

Figure B-2. Photomicrographs of SCC specimens from aft bulkhead coupon blank M8 following 

30-day 3.5% NaCl alternate immersion exposure at applied stress levels of (a) 0% YS; 

(b) 50% YS; (c1, c2) 75% YS; and (d1, d2) 90% YS.
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

136 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#107_etched_m03_20x.jpg #107_etched_m04_50x.jpg

Coupon blank: M9

Specimen No.: 107

Orientation: ST

Applied stress (% YS): 0

Applied stress (ksi): 0

Failed?: No

SCC?: No

(a) 0% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

137 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#113_etched_m03_20x.jpg #113_etched_m04_50x.jpg

Coupon blank: M9

Specimen No.: 113

Orientation: ST

Applied stress (% YS): 75, based on M9 average ST YS

Applied stress (ksi): 33.25

Failed?: No

SCC?: No

(b) 75% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

138 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#117_etched_m03_20x.jpg #117_etched_m04_50x.jpg

Coupon blank: M9

Specimen No.: 117

Orientation: ST

Applied stress (% YS): 90, based on M9 average ST YS

Applied stress (ksi): 39.9

Failed?: Yes, 26 days

SCC?: No

(c) 90% YS

Figure B-3. Photomicrographs of SCC specimens from aft bulkhead coupon blank M9 following 

30-day 3.5% NaCl alternate immersion exposure at applied stress levels of (a) 0% YS; 

(b) 75% YS; and (c) 90% YS.
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

139 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#149_etched_m03_20x.jpg #149_etched_m04_50x.jpg

Coupon blank: M10

Specimen No.: 149

Orientation: ST

Applied stress (% YS): 0

Applied stress (ksi): 0

Failed?: No

SCC?: No

(a) 0% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

140 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#152_etched_m03_20x.jpg #152_etched_m04_50x.jpg

Coupon blank: M10

Specimen No.: 152

Orientation: ST

Applied stress (% YS): 50, based on M10 average ST YS

Applied stress (ksi): 22.21

Failed?: Yes, 29 days

SCC?: Yes; circled in red

(b1) 50% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

141 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#153_etched_m03_20x.jpg #153_etched_m04_50x.jpg

Coupon blank: M10

Specimen No.: 153

Orientation: ST

Applied stress (% YS): 50, based on M10 average ST YS

Applied stress (ksi): 22.21

Failed?: No, residual strength test specimen

SCC?: Not rated, tensile test may artificially open cracks

(b2) 50% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

142 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#154_etched_m03_20x.jpg #154_etched_m04_50x.jpg

Coupon blank: M10

Specimen No.: 154

Orientation: ST

Applied stress (% YS): 50, based on M10 average ST YS

Applied stress (ksi): 22.21

Failed?: No, residual strength test specimen

SCC?: Not rated, tensile test may artificially open cracks

(b3) 50% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

143 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#156_etched_m03_20x.jpg #156_etched_m04_50x.jpg

Coupon blank: M10

Specimen No.: 156

Orientation: ST

Applied stress (% YS): 75, based on M10 average ST YS

Applied stress (ksi): 33.31

Failed?: Yes, 30 days

SCC?: No

(c1) 75% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

144 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#157_etched_m03_20x.jpg #157_etched_m04_50x.jpg

Coupon blank: M10

Specimen No.: 157

Orientation: ST

Applied stress (% YS): 75, based on M10 average ST YS

Applied stress (ksi): 33.31

Failed?: Yes, 26 days

SCC?: Yes; circled in red

(c2) 75% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

145 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#159_etched_m03_20x.jpg #159_etched_m04_50x.jpg

Coupon blank: M10

Specimen No.: 159

Orientation: ST

Applied stress (% YS): 90, based on M10 average ST YS

Applied stress (ksi): 39.37

Failed?: Yes, 30 days

SCC?: No

(d1) 90% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

146 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#160_etched_m03_20x.jpg #160_etched_m04_50x.jpg

Coupon blank: M10

Specimen No.: 160

Orientation: ST

Applied stress (% YS): 90, based on M10 average ST YS

Applied stress (ksi): 39.37

Failed?: Yes, 29 days

SCC?: No

(d2) 90% YS
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

147 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

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#161_etched_m03_20x.jpg #161_etched_m04_50x.jpg

Coupon blank: M10

Specimen No.: 161

Orientation: ST

Applied stress (% YS): 90, based on M10 average ST YS

Applied stress (ksi): 39.37

Failed?: Yes, 29 days

SCC?: Yes; circled in red

(d3) 90% YS

Figure B-4. Photomicrographs of SCC specimens from aft bulkhead coupon blank M10 following 

30-day 3.5% NaCl alternate immersion exposure at applied stress levels of (a) 0% YS; 

(b1, b2, b3) 50% YS; (c1, c2) 75% YS; and (d1, d2, d3) 90% YS.
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

148 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

11.3 Appendix C: Summary of the Supplemental SCC Test Results following 30-day 

3.5% NaCl Alternate Immersion Exposure

Table C-1. Supplemental SCC test results for spin formed Al 2219-T62 aft bulkhead, CPST dome and wrought 

plate materials following 30-day 3.5% NaCl alternate immersion exposure.

M10-1 ST 0 0 0 No failure Tensile 38.19 64 ---- ---- ----

M10-2 ST 0 0 0 No failure Tensile 23.79 40 ---- ---- ----

M10-3 ST 0 0 0 No failure Micro ---- ---- ---- No 5 (a)

M10-13 ST 18.00 40.5 50 No failure Tensile 34.34 58 1.11 ---- ----

M10-14 ST 18.00 40.5 50 No failure Tensile 32.32 55 1.04 ---- ----

M10-15 ST 18.00 40.5 50 No failure Micro 32.32 ---- ---- Yes 5 ( c)

M10-4 ST 22.20 50.0 62 No failure Tensile 35.48 60 1.14 ---- ----

M10-5 ST 22.20 50.0 62 No failure Tensile 33.29 56 1.07 ---- ----

M10-6 ST 22.20 50.0 62 No failure Micro ---- ---- ---- Yes 5 (b)

M10-17 ST 27.00 60.8 75 No failure Tensile 33.73 57 1.09 ---- ----

M10-18 ST 27.00 60.8 75 No failure Tensile 38.03 64 1.23 ---- ----

M10-16 ST 27.00 60.8 75 No failure Micro ---- ---- ---- Yes 5 ( e)

M10-7 ST 33.30 75.0 93 No failure Tensile 31.80 54 1.03 ---- ----

M10-8 ST 33.30 75.0 93 No failure Tensile 36.71 62 1.18 ---- ----

M10-9 ST 33.30 75.0 93 No failure Micro ---- ---- ---- Yes 5 (d)

J1-7 ST 0 0 0 No failure Tensile 36.59 66 ---- ---- ----

J1-9 ST 0 0 0 No failure Tensile 27.55 50 ---- ---- ----

J1-8 ST 0 0 0 No failure Micro ---- ---- ---- No 6 (a)

J1-4 ST 18.00 43.0 50 No failure Tensile 28.11 51 0.88 ---- ----

J1-5 ST 18.00 43.0 50 No failure Tensile 33.00 60 1.03 ---- ----

J1-6 ST 18.00 43.0 50 No failure Micro ---- ---- ---- No 6 (b)

J1-1 ST 27.00 64.5 75 No failure Tensile 29.58 54 0.92 ---- ----

J1-3 ST 27.00 64.5 75 No failure Tensile 32.92 60 1.03 ---- ----

J1-2 ST 27.00 64.5 75 No failure Micro ---- ---- ---- Yes 6 ( c)

J2-7 ST 0 0 0 No failure Tensile 29.67 52 ---- ---- ----

J2-9 ST 0 0 0 No failure Tensile 34.07 60 ---- ---- ----

J2-8 ST 0 0 0 No failure Micro ---- ---- ---- No 7 (a)

J2-4 ST 18.00 41.8 50 No failure Tensile 37.08 65 1.16 ---- ----

J2-6 ST 18.00 41.8 50 No failure Tensile 30.97 54 0.97 ---- ----

J2-5 ST 18.00 41.8 50 No failure Micro ---- ---- ---- Yes 7 (b)

J2-1 ST 27.00 62.6 75 No failure Tensile 31.37 55 0.98 ---- ----

J2-3 ST 27.00 62.6 75 No failure Tensile 33.17 58 1.04 ---- ----

J2-2 ST 27.00 62.6 75 No failure Micro ---- ---- ---- No 7 ( c)

J3-7 ST 0 0 0 No failure Tensile 36.92 64 ---- ---- ----

J3-9 ST 0 0 0 No failure Tensile 40.34 69 ---- ---- ----

J3-8 ST 0 0 0 No failure Micro ---- ---- ---- No 8 (a)

J3-4 ST 18.00 41.1 50 No failure Tensile 37.65 65 0.97 ---- ----

J3-6 ST 18.00 41.1 50 No failure Tensile 39.93 69 1.03 ---- ----

J3-5 ST 18.00 41.1 50 No failure Micro ---- ---- ---- No 8 (b)

J3-1 ST 27.00 61.6 75 No failure Tensile 32.68 57 0.85 ---- ----

J3-2 ST 27.00 61.6 75 No failure Tensile 41.97 73 1.09 ---- ----

J3-3 ST 27.00 61.6 75 No failure Micro ---- ---- ---- No 8 ( c)

Photomicrograph

Figure No.

Residual 

Tensile 

Strength 

ksi(1)

Percent

Tensile 

Strength 

Retained(2)

Residual 

Strength 

Ratio(3)

Specimen 

No.

Applied 

Stress Level 

ksi

Applied 

Stress Level

 % Measured 

ST YS

Applied 

Stress Level 

% MMPDS 

Orientation LT YS

Coupon 

Blank 

M10

J1

J2

J3

Days to 

Failure

Post SCC 

Test 

Evaluation

SCC?

Metallographic 

Examination
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

149 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

Table C-1. Supplemental SCC test results for spin formed Al 2219-T62 aft bulkhead, CPST dome and wrought plate 

materials following 30-day 3.5% NaCl alternate immersion exposure (continued).

WQ-1 ST 0 0 0 No failure Tensile 28.53 46 ---- ---- ----

WQ-2 ST 0 0 0 No failure Tensile 28.36 46 ---- ---- ----

WQ-3 ST 0 0 0 No failure Micro ---- ---- ---- No 9 (a)

WQ-4 ST 18.00 41.4 50 No failure Tensile 34.96 57 1.23 ---- ----

WQ-5 ST 18.00 41.4 50 No failure Tensile 33.99 55 1.19 ---- ----

WQ-6 ST 18.00 41.4 50 No failure Micro ---- ---- ---- No 9 (b)

WQ-7 ST 27.00 62.1 75 No failure Tensile 27.84 45 0.98 ---- ----

WQ-8 ST 27.00 62.1 75 No failure Tensile 28.63 46 1.01 ---- ----

WQ-9 ST 27.00 62.1 75 No failure Micro ---- ---- ---- No 9 ( c)

GQ-2 ST 0 0 0 No failure Tensile 43.63 74 ---- ---- ----

GQ-3 ST 0 0 0 No failure Tensile 34.5 58 ---- ---- ----

GQ-1 ST 0 0 0 No failure Micro ---- ---- ---- No 10 (a)

GQ-5 ST 18.00 48.4 50 No failure Tensile 33.99 57 0.87 ---- ----

GQ-6 ST 18.00 48.4 50 No failure Tensile 30.65 52 0.78 ---- ----

GQ-4 ST 18.00 48.4 50 No failure Micro ---- ---- ---- Yes 10 (b)

GQ-8 ST 27.00 72.6 75 No failure Tensile 36.71 62 0.94 ---- ----

GQ-9 ST 27.00 72.6 75 No failure Tensile 37.15 63 0.95 ---- ----

GQ-7 ST 27.00 72.6 75 No failure Micro ---- ---- ---- No 10 ( c)

CP-P1 ST 0 0 0 No failure Tensile 33.36 59 ---- ---- ----

CP-P3 ST 0 0 0 No failure Tensile 32.66 58 ---- ---- ----

CP-P2 ST 0 0 0 No failure Micro ---- ---- ---- No 11 (a)

CP-P4 ST 18.00 44.8 50 No failure Tensile 27.93 50 0.85 ---- ----

CP-P5 ST 18.00 44.8 50 No failure Tensile 19.24 34 0.58 (4) ---- ----

CP-P6 ST 18.00 44.8 50 No failure Micro ---- ---- ---- No 11 (b)

CP-P7 ST 27.00 67.2 75 No failure Tensile 26.26 47 0.8 ---- ----

CP-P8 ST 27.00 67.2 75 No failure Tensile 24.15 43 0.73 (4) ---- ----

CP-P9 ST 27.00 67.2 75 No failure Micro ---- ---- ---- Yes 11 ( c)

CP-R2 ST 0 0 0 No failure Tensile 35.82 62 ---- ---- ----

CP-R3 ST 0 0 0 No failure Tensile 33.01 57 ---- ---- ----

CP-R1 ST 0 0 0 No failure Micro ---- ---- ---- No 12 (a)

CP-R5 ST 18.00 48.2 50 No failure Tensile 29.95 52 0.87 ---- ----

CP-R6 ST 18.00 48.2 50 No failure Tensile 33.64 59 0.98 ---- ----

CP-R4 ST 18.00 48.2 50 No failure Micro ---- ---- ---- No 12 (b)

CP-R8 ST 27.00 72.3 75 No failure Tensile 30.65 54 0.89 ---- ----

CP-R9 ST 27.00 72.3 75 No failure Tensile 25.21 44 0.73 (4) ---- ----

CP-R7 ST 27.00 72.3 75 No failure Micro ---- ---- ---- Yes 12 ( c)

Photomicrograph

Figure No.

Standard 

Plate

Days to 

Failure

Post SCC 

Test 

Evaluation

Residual 

Tensile 

Strength 

ksi(1)

Percent

Tensile 

Strength 

Retained(2)

Residual 

Strength 

Ratio(3)

SCC?

Metallographic 

Examination

Coupon 

Blank 

Specimen 

No. Orientation

Applied 

Stress Level 

ksi

Applied 

Stress Level

 % Measured 

ST YS

Applied 

Stress Level 

% MMPDS 

LT YS

Modified 

Plate

CPST 

Dome 

Pole

CPST 

Dome 

Rim

(1) UTSf = Residual strength of exposed specimen (failure load / original specimen cross sectional area)

(2) Percent tensile strength retained = UTSf / UTSi x 100 where UTSi = average ultimate tensile strength obtained from baseline tensile tests of 

non-exposed specimens.

(3) Residual strength ratio = UTSs/UTSo where: UTSs = residual strength of stressed and exposed specimen and UTSo = averaged residual strength 

of non-stressed and exposed specimens.

(4) Passed if residual strength ratio ≥0.75, failed if ratio <0.75.
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

150 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

11.4 Appendix D: Summary of the Phase II SCC Test Results Following 30-day 3.5% 

NaCl Alternate Immersion Exposure

Table D-1. Phase II SCC test results for spin formed Al 2219-T62 aft bulkhead material following 30-day 3.5% 

NaCl alternate immersion exposure; LT orientation.

M7-3 LT 0 0 0 No failure Tensile 28.23 52 --- --- ---

M7-4 LT 0 0 0 No failure Tensile 30.98 57 --- --- ---

M7-2 LT 0 0 0 No failure Micro --- --- --- No A-1 (a)

M7-6 LT 18.32 50 51 No failure Tensile 22.75 42 0.77 --- ---

M7-7 LT 18.32 50 51 No failure Tensile 29.65 55 1 --- ---

M7-5 LT 18.32 50 51 No failure Micro --- --- --- No A-1 (b)

M7-9 LT 27.48 75 76 No failure Tensile 31.53 58 1.06 --- ---

M7-10 LT 27.48 75 76 No failure Tensile 25.62 47 0.87 --- ---

M7-8 LT 27.48 75 76 No failure Micro --- --- --- No A-1 (c)

M7-13 LT 32.98 90 92 No failure Tensile 28.51 53 0.96 --- ---

M7-14 LT 32.98 90 92 No failure Tensile 25.04 46 0.85 --- ---

M7-12 LT 32.98 90 92 No failure Micro --- --- --- No A-1 (d)

M8-45 LT 0 0 0 No failure Tensile 33.98 59 --- --- ---

M8-46 LT 0 0 0 No failure Tensile 33.23 58 --- --- ---

M8-44 LT 0 0 0 No failure Micro --- --- --- No A-2 (a)

M8-48 LT 19.39 50 54 No failure Tensile 32.54 56 0.97 --- ---

M8-49 LT 19.39 50 54 No failure Tensile 32.68 57 0.97 --- ---

M8-47 LT 19.39 50 54 No failure Micro --- --- --- No A-2 (b)

M8-51 LT 29.09 75 81 No failure Tensile 37.74 65 1.12 --- ---

M8-52 LT 29.09 75 81 No failure Tensile 31.38 54 0.93 --- ---

M8-50 LT 29.09 75 81 No failure Micro --- --- --- No A-2 (c)

M8-55 LT 34.90 90 97 No failure Tensile 32.84 57 0.98 --- ---

M8-56 LT 34.90 90 97 No failure Tensile 37.41 65 1.11 --- ---

M8-54 LT 34.90 90 97 No failure Micro --- --- --- No A-2 (d)

M9-87 LT 0 0 0 No failure Tensile 39.10 66 --- --- ---

M9-88 LT 0 0 0 No failure Tensile 39.16 66 --- --- ---

M9-86 LT 0 0 0 No failure Micro --- --- --- No A-3 (a)

M9-90 LT 19.84 50 55 No failure Tensile 38.96 65 1 --- ---

M9-91 LT 19.84 50 55 No failure Tensile 40.5 68 1.04 --- ---

M9-89 LT 19.84 50 55 No failure Micro --- --- --- No A-3 (b)

M9-93 LT 29.76 75 83 No failure Tensile 39.58 66 1.01 --- ---

M9-94 LT 29.76 75 83 No failure Tensile 42.41 71 1.08 --- ---

M9-92 LT 29.76 75 83 No failure Micro --- --- --- No A-3 (c)

M9-97 LT 35.71 90 99 No failure Tensile 34.08 57 0.87 --- ---

M9-98 LT 35.71 90 99 No failure Tensile 39.06 66 1 --- ---

M9-96 LT 35.71 90 99 No failure Micro --- --- --- No A-3 (d)

M10-171 LT 0 0 0 No failure Tensile 34.10 61 --- --- ---

M10-172 LT 0 0 0 No failure Tensile 29.47 53 --- --- ---

M10-170 LT 0 0 0 No failure Micro --- --- --- No A-4 (a)

M10-174 LT 18.94 50 53 No failure Tensile 31.51 56 0.99 --- ---

M10-175 LT 18.94 50 53 No failure Tensile 29.44 53 0.93 --- ---

M10-173 LT 18.94 50 53 No failure Micro --- --- --- No A-4 (b)

M10-177 LT 28.40 75 79 No failure Tensile 34.70 62 1.09 --- ---

M10-178 LT 28.40 75 79 No failure Tensile 32.52 58 1.02 --- ---

M10-176 LT 28.40 75 79 No failure Micro --- --- --- No A-4 (c)

M10-181 LT 34.08 90 95 No failure Tensile 30.03 54 0.94 --- ---

M10-182 LT 34.08 90 95 No failure Tensile 34.24 61 1.08 --- ---

M10-180 LT 34.08 90 95 No failure Micro --- --- --- No A-4 (d)

SCC?

Metallographic 

Examination

Photomicrograph

Figure No.

Specimen 

No.

Applied 

Stress Level 

ksi

Applied 

Stress Level

 % Measured 

ST YS

Applied 

Stress Level 

% MMPDS 

LT YS

Days to 

Failure

Post SCC 

Test 

Orientation Evaluation

Residual 

Tensile 

Strength 

ksi(1)

Percent

Tensile 

Strength 

Retained(2)

Residual 

Strength 

Ratio(3)

Coupon 

Blank 

M 8

M 9

M10

M 7

(1) UTSf = Residual strength of exposed specimen (failure load / original specimen cross sectional area).

(2) Percent tensile strength retained = UTSf / UTSi x 100 where UTSi = average ultimate tensile strength obtained from baseline tensile 

tests of non-exposed specimens.

(3) Residual strength ratio = UTSs/UTSo where: UTSs = residual strength of stressed and exposed specimen and UTSo = averaged residual 

strength of non-stressed and exposed specimens.

(4) Passed if residual strength ratio ≥0.75, failed if ratio <0.75.
NASA Engineering and Safety Center

Technical Assessment Report

Document #:

NESC-RP13-00884

Version:

1.0

Title:

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion MultiPurpose Crew Vehicle – Phase II Supplemental Report

Page #:

151 of 151

NESC Request No.: TI-13-00884_Phase II Supplemental Report

Table D-2. Phase II SCC test results for spin formed Al 2219-T62 aft bulkhead material following 30-day 3.5% 

NaCl alternate immersion exposure; ST orientation.

M7-24 ST 0 0 0 No failure Tensile 28.40 49 ---- --- ---

M7-25 ST 0 0 0 No failure Tensile 18.61 32 ---- --- ---

M7-23 ST 0 0 0 No failure Micro ---- ---- ---- No B-1 (a)

M7-27 ST 21.60 50 60 No failure Tensile 22.51 39 0.96 --- ---

M7-28 ST 21.60 50 60 No failure Tensile 20.97 36 0.89 --- ---

M7-26 ST 21.60 50 60 No failure Micro --- --- --- No B-1 (b)

M7-29 ST 32.40 75 90 Failed; 30 days Micro ---- ---- ---- Yes B-1 (c1)

M7-30 ST 32.40 75 90 Failed; 28 days Micro ---- ---- ---- Yes B-1 (c2)

M7-31 ST 32.40 75 90 Failed; 26 days Micro ---- ---- ---- Yes B-1 (c3)

M7-33 ST 38.88 90 108 Failed; 28 days Micro --- --- --- Yes B-1 (d1)

M7-34 ST 38.88 90 108 Failed; 26 days Micro --- --- --- Yes B-1 (d2)

M7-35 ST 38.88 90 108 Failed; 26 days Micro --- --- --- Yes B-1 (d3)

M8-66 ST 0 0 0 No failure Tensile 23.25 40 ---- --- ---

M8-67 ST 0 0 0 No failure Tensile 19.44 33 ---- --- ---

M8-65 ST 0 0 0 No failure Micro ---- ---- ---- No B-2 (a)

M8-69 ST 21.87 50 61 No failure Tensile 16.52 28 0.77 --- ---

M8-70 ST 21.87 50 61 No failure Tensile 32.45 55 1.52 --- ---

M8-68 ST 21.87 50 61 No failure Micro --- --- --- No B-2 (b)

M8-72 ST 32.80 75 91 Failed; 30 days Micro --- --- --- --- ---

M8-71 ST 32.80 75 91 Failed; 30 days Micro --- --- --- No B-2 (c1)

M8-73 ST 32.80 75 91 Failed; 27 days Micro --- --- --- Yes B-2 (c2)

M8-77 ST 39.36 90 109 No failure Tensile 22.51 38 1.05 --- ---

M8-75 ST 39.36 90 109 Failed; 26 days Micro --- --- --- Yes B-2 (d1)

M8-76 ST 39.36 90 109 Failed; 30 days Micro --- --- --- No B-2 (d2)

M9-108 ST 0 0 0 No failure Tensile 26.95 45 ---- --- ---

M9-109 ST 0 0 0 No failure Tensile 19.55 33 ---- --- ---

M9-107 ST 0 0 0 No failure Micro ---- ---- ---- No B-3 (a)

M9-110 ST 22.17 50 62 No failure Tensile 28.09 47 1.21 --- ---

M9-112 ST 22.17 50 62 No failure Tensile 19.66 33 0.85 --- ---

M9-111 ST 22.17 50 62 Failed; 30 days(5) Micro --- --- --- --- ---

M9-114 ST 33.25 75 92 No failure Tensile 24.50 41 1.05 --- ---

M9-115 ST 33.25 75 92 No failure Tensile 27.58 46 1.19 --- ---

M9-113 ST 33.25 75 92 No failure Micro --- --- --- No B-3 (b)

M9-118 ST 39.90 90 111 No failure Tensile 24.62 41 1.06 --- ---

M9-119 ST 39.90 90 111 No failure Tensile 25.17 42 1.08 --- ---

M9-117 ST 39.90 90 111 Failed; 26 days Micro --- --- --- No B-3 (c)

M10-150 ST 0 0 0 No failure Tensile 18.88 32 ---- --- ---

M10-151 ST 0 0 0 No failure Tensile 19.36 32 ---- --- ---

M10-149 ST 0 0 0 No failure Micro ---- ---- ---- No B-4 (a)

M10-152 ST 22.21 50 62 Failed; 29 days Micro --- --- --- Yes B-4 (b1)

M10-153 ST 22.21 50 62 No failure Tensile 5.51 9 0.29 (4) Not Rated (6) B-4 (b2)

M10-154 ST 22.21 50 62 No failure Tensile 2.56 4 0.13 (4) Not Rated (6) B-4 (b3)

M10-155 ST 33.31 75 93 No failure Tensile 20.32 34 1.06 --- ---

M10-156 ST 33.31 75 93 Failed; 30 days Micro --- --- --- No B-4 (c1)

M10-157 ST 33.31 75 93 Failed; 26 days Micro --- --- --- Yes B-4 (c2)

M10-159 ST 39.37 90 109 Failed; 30 days Micro --- --- --- No B-4 (d1)

M10-160 ST 39.37 90 109 Failed; 29 days Micro --- --- --- No B-4 (d2)

M10-161 ST 39.37 90 109 Failed; 29 days Micro --- --- --- Yes B-4 (d3)

Post SCC 

Test 

Evaluation

SCC?

Metallographic 

Examination

Photomicrograph

Figure No.

Specimen 

No.

Applied 

Stress Level 

ksi

Applied 

Stress Level

 % Measured 

ST YS

Applied 

Stress Level 

% MMPDS 

LT YS

Residual 

Tensile 

Strength 

ksi(1)

Percent

Tensile 

Strength 

Retained(2) Orientation

Residual 

Strength 

Ratio(3)

Days to 

Failure

M10

Coupon 

Blank 

M 7

M 8

M 9

(1) UTSf = Residual strength of exposed specimen (failure load / original specimen cross-sectional area).

(2) Percent tensile strength retained = UTSf / UTSi x 100 where UTSi = average ultimate tensile strength obtained from baseline tensile tests of 

non-exposed specimens.

(3) Residual strength ratio = UTSs/UTSo where: UTSs = residual strength of stressed and exposed specimen and UTSo = averaged residual strength 

of non-stressed and exposed specimens.

(4) Passed if residual strength ratio ≥0.75, failed if ratio <0.75.

(5)

Invalid failure; failed in shoulder outside of gage length.

(6) Photomicrograph of exposed specimen taken after tensile testing.
REPORT DOCUMENTATION PAGE Form Approved

OMB No. 0704-0188

2. REPORT TYPE

Technical Memorandum

4. TITLE AND SUBTITLE

Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion 

Multi-Purpose Crew Vehicle

Phase II Supplemental Report

5a. CONTRACT NUMBER

6. AUTHOR(S)

Hoffman, Eric K.; Domack, Marcia S.; Torres, Pablo D.;

McGill, Preston B.; Tayon, Wesley A.; Bennett, Jay E.;

Murphy, Joseph T.

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

NASA Langley Research Center

Hampton, VA 23681-2199

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

Washington, DC 20546-0001

8. PERFORMING ORGANIZATION

REPORT NUMBER

L-20606 NESC-RP-13-00884

10. SPONSOR/MONITOR'S ACRONYM(S)

NASA

13. SUPPLEMENTARY NOTES

12. DISTRIBUTION/AVAILABILITY STATEMENT

Unclassified - Unlimited

Subject Category 16 Space Transportation and Safety

Availability: NASA STI Program (757) 864-9658

19a. NAME OF RESPONSIBLE PERSON

STI Help Desk (email: help@sti.nasa.gov)

14. ABSTRACT

The principal focus of this project was to assist the Orion Multi-Purpose Crew Vehicle (MPCV) Program in developing a spin 

forming fabrication process for manufacture of the aft bulkhead of the pressure vessel. The spin forming process will enable a 

single piece aluminum (Al) 2219 aft bulkhead which will eliminate the current multiple piece welded construction, simplify 

fabrication, and lead to an enhanced design that will reduce vehicle weight by eliminating welds. This report is a supplement 

to the original publication (NASA/TM-2015-218674). Phase I (NESC-RP-12-00776/NASA TM-2014-218163, (1)) of this 

assessment explored spin forming the single-piece forward pressure vessel bulkhead from aluminum-lithium (Al-Li) 2195.

15. SUBJECT TERMS

Spin Forming; Crew Module; Aft Pressure Vessel Bulkhead; NASA Engineering and Safety Center; Multi-Purpose Crew 

Vehicle

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OF

PAGES

156

19b. TELEPHONE NUMBER (Include area code)

(443) 757-5802

a. REPORT

U

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U

b. ABSTRACT

U

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ABSTRACT

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Prescribed by ANSI Std. Z39.18

Standard Form 298 (Rev. 8-98)

3. DATES COVERED (From - To)

July 2013 - October 2015

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

5d. PROJECT NUMBER

5e. TASK NUMBER

5f. WORK UNIT NUMBER

869021.05.07.09.43

11. SPONSOR/MONITOR'S REPORT

NUMBER(S)

NASA/TM-2015-218797

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1. REPORT DATE (DD-MM-YYYY)

01- 12 - 2015