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be considered if fatigue loading is a con- cern in other applications. Testing of three non-HIP’d tensile specimens suggests that HIPing may not be necessary to achieve desired strength levels. ASTMF3055 requires the sameme- chanical properties for Class D (stress re- lieved, HIP’d, solution treated, and aged) and Class F (same as Class D, except no HIPing) parts. Results described here support this, but there were not enough specimens to make a complete compari- son on the effect of HIPing. Finally, now that industry standard ASTM F3055 is available for use, it may be easier to standardize manufacturing processes from different vendors. All of the parts in this application were made consecutively by one vendor, but this may not be possible in a large produc- tion environment. ~AM&P For more information: Andrew Clifton is an associate manager in Structur- al Materials and Processes, Lockheed Martin Space Systems Co., 1111 Lock- heed Martin Way, Sunnyvale, CA 94089, 408.742.1502, andrew.c.clifton@lmco. com, www.lockheedmartin.com. References 1. J.J. Schirra, R.H. Caless, and R.W. Hatala, The Effect of Laves Phase on the Mechanical Properties of Wrought and Cast + HIP Inconel 718, 1991 Superalloys Conference Proceedings, tms.org/superalloys/10.7449/1991/ Superalloys_1991_375_388.pdf. 2. G.F. Vander Voort, G.M. Lucas, and E.P. Manilova, Metallography and Mi- crostructures of Heat-Resistant Alloys, in ASM Handbook, Volume 9: Metallog- raphy and Microstructures, p 837, ISBN 0-87170-706-3.

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Fig. 7 — Build pause on vertical tensile specimen. Build direction is left to right.

Fig. 8 — Orion Exploration Flight Test 1 vehicle in the Pacific Ocean after landing. Courtesy of NASA.

it may be beneficial to perform these comparisons before making additively manufactured structural parts. In addition, tensile specimens could have been manufactured to near- net size to reduce specimen preparation time and cost. The z orientation (vertical) specimens could have been manufac- tured to net size, allowing for a compar- ison between as-manufactured surfaces and smooth machined surfaces. This

comparison may be important for parts with significant fatigue loading. Fatigue curves were not generat- ed. Instead, parts were subjected to a vi- bration acceptance test, which showed that the parts would be sufficient for the specific mission, but did not lead to a standard stress-versus-cycles (S-N) curve that could be used for other parts and applications. Vibration acceptance and/or fatigue curve generation should