Effect of Heating Temperature, Heating Time and Initial Microstructure on Recrystallization of Waspaloy during Heating for Forging

Since this project is a result of a class assignment, it has been graded and accepted as fulfillment of the course requirements. Acceptance does not imply technical accuracy or reliability. Any use of the information in this report, including numerical data, is done at the risk of the user. These risks may include catastrophic failure of the device or infringement of patent or copyright laws. The students, faculty, and staff of Cal Poly State University, San Luis Obispo cannot be held liable for any misuse of the project. Abstract 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.