BS in Materials Engineering
Materials Engineering Department
A fine, uniform grain size is required for creep limited Waspaloy in aircraft engine applications. Upon heating, Waspaloy does not always recrystallize in a uniform manner resulting in occasional large grains with a majority of the grains meeting the grain size requirements. Waspaloy’s microstructure was analyzed with different heat treatments and in the as-forged condition. The strengthening mechanism is the gamma prime phase. The gamma prime solvus temperature is 1908°F so the different heat treatments were determined around that temperature, as well as the forging temperature range of 1800-2150°F. At the 1850°F heat treatment, the microstructure recrystallized with small grains, slightly larger than the as-forged samples. The samples heat treated at 1900°F had microstructures showing the sample recrystallized with larger grains surrounding the smaller grains with an ASTM grain size 5. The samples heat treated at 1925°F appeared similar to the samples that were heat treated at 1900°F, but had an ASTM grain size number slightly larger with an ASTM grain size number of 4.76. The samples heat treated at 1950°F showed larger grains than the previous heat treatments with an ASTM grain size 3.92. The samples heat treated at 2000°F showed much larger grains than the other heat treatments. The average grain size for the samples at 2000°F were about 2.4. The samples fell into the ASTM grain size number requirement for Schlosser at an ASTM grain size of 3 or finer, except for the heat treatments at 2000°F. The as-forged sample was approximately ASTM grain size 6. The recommended heat treatment temperature is 1925°F because it has the gamma prime strengthening mechanism and complies with Schlosser’s ASTM grain size number specification requirements.