NASA Scientific and Technical Aerospace Reports
NASA Scientific and Technical Aerospace Reports
NASA Scientific and Technical Aerospace Reports
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This report details efforts to enhance the fabrication process for the production of transparent magnesium aluminate spinel<br />
domes. TA&T has evaluated a variety of spinel powders for pressureless sintering. The effects of powder blending <strong>and</strong> milling,<br />
cold isostatic pressing conditions, binder removal, sintering, <strong>and</strong> hot isostatic pressing on the final transparency of pressureless<br />
sintered parts have been determined. A working knowledge of the processing window has been established, allowing<br />
transparent spinel domes to be produced on a repetitive basis. This report details these investigations of the processing<br />
variables, <strong>and</strong> documents the successes of the Phase I effort.<br />
DTIC<br />
Aerothermodynamics; Infrared Windows<br />
20040112030 <strong>NASA</strong> Glenn Research Center, Clevel<strong>and</strong>, OH, USA<br />
Stress Relaxation in Powder Metallurgy Superalloy Disks<br />
Gabb, T. P.; Telesman, J.; Kantzos, P. T.; Bonacuse, P. J.; Barrie, R. L.; Hornbach, D.; [2004]; 2 pp.; In English; Powder<br />
Metallurgy Symposium 2004, 14-18 Mar. 2004, Charlotte, NC, USA<br />
Contract(s)/Grant(s): 728-30-09; Copyright; Avail: CASI; A01, Hardcopy<br />
The objective of this study was to assess the relaxation of stresses at increasing temperatures in several PM superalloy<br />
disks. The effects of temperature, time, <strong>and</strong> plasticity were examined.<br />
Author<br />
Powder Metallurgy; Heat Resistant Alloys<br />
20040112034 <strong>NASA</strong> Glenn Research Center, Clevel<strong>and</strong>, OH, USA<br />
Effects of High Temperature Exposures on Fatigue Life of Disk Superalloys<br />
Gabb, Tim P.; Telesman, Jack; Kantzos, Pete T.; Smith, James W.; Browning, Paul F.; [2004]; 5 pp.; In English; International<br />
Symposium on Superalloys, 19-23 Sep. 2004, Seven Springs, PA, USA<br />
Contract(s)/Grant(s): 728-30-09; No Copyright; Avail: CASI; A01, Hardcopy<br />
The effects on fatigue life of high temperature exposures simulating service conditions were considered for two disk<br />
superalloys. Powder metallurgy processed, supersolvus heat treated Udimet (trademark) 720 <strong>and</strong> ME3 fatigue specimens were<br />
exposed in air at temperatures of 650 to 704 C, for times of 100 h to over 1000 h. They were then tested using conventional<br />
fatigue tests at 650 <strong>and</strong> 704 C, to determine the effects of exposure on fatigue resistance. Cyclic dwell verification tests were<br />
also performed to contrast the effects of intermixed exposures <strong>and</strong> fatigue cycles. The prior exposures reduced life by up to<br />
70% <strong>and</strong> increased the scatter in life, compared to unexposed levels. Cyclic dwell tests reduced lives even more. Fractographic<br />
evaluations indicated the failure mode was shifted by the exposures <strong>and</strong> cyclic dwells from predominantly internal to often<br />
surface crack initiations. The increased scatter in life was related to the competition between internal crack initiations at<br />
inclusions or large grains producing longer lives, <strong>and</strong> surface crack initiations at an environmentally affected surface layer<br />
producing shorter lives.<br />
Author<br />
High Temperature Tests; Temperature Effects; Fatigue Life; Heat Resistant Alloys<br />
20040112035 <strong>NASA</strong> Glenn Research Center, Clevel<strong>and</strong>, OH, USA<br />
The Effect of Solution Heat Treatment on an Advanced Nickel-Base Disk Alloy<br />
Gayda, J.; Gabb, T. P.; Kantzos, P. T.; [2004]; 6 pp.; In English; Tenth International Symposium on Superalloys, 9-23 Sep.<br />
2004, Seven Springs, PA, USA<br />
Contract(s)/Grant(s): WBS 728-30-09; No Copyright; Avail: CASI; A02, Hardcopy<br />
Five heat treat options for an advanced nickel-base disk alloy, LSHR, have been investigated. These included two<br />
conventional solution heat treat cycles, subsolvus/oil quench <strong>and</strong> supersolvus/fan cool, which yield fine grain <strong>and</strong> coarse grain<br />
microstructure disks respectively, as well as three advanced dual microstructure heat treat (DMHT) options. The DMHT<br />
options produce disks with a fine grain bore <strong>and</strong> a coarse grain rim. Based on an overall evaluation of the mechanical property<br />
data, it was evident that the three DMHT options achieved a desirable balance of properties in comparison to the conventional<br />
solution heat treatments for the LSHR alloy. However, one of the DMHT options, SUB/DMHT, produced the best set of<br />
properties, largely based on dwell crack growth data. Further evaluation of the SUB/DMHT option in spin pit experiments on<br />
a generic disk shape demonstrated the advantages <strong>and</strong> reliability of a dual grain structure at the component level.<br />
Author<br />
Heat Resistant Alloys; Nickel Alloys; Disks (Shapes); Heat Treatment; Crack Propagation; Temperature Effects;<br />
Microstructure<br />
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