TY - GEN
T1 - Impact of Coarse γ′ Phase on Recrystallization Modeling in New Ni-Based Superalloy M647
AU - Nishimoto, Takashi
AU - Okajima, Takuma
AU - Yamashita, Kenta
AU - Zhang, Qiaofu
AU - Gong, Jiadong
AU - Olson, Greg
N1 - Publisher Copyright:
© 2020, The Minerals, Metals & Materials Society.
PY - 2020
Y1 - 2020
N2 - M647, a Ni-based superalloy with excellent mechanical properties and good hot deformability, was recently developed for application in airplane engine disks. In airplane engines, fine-grained superalloys are required to improve high-temperature fatigue properties. Methods to control fine grains have been extensively studied, including a refined method of applying the pinning effect of a coarse γ′ phase. However, previous reports focused on the mechanism of nucleation and abnormal grain growth, and reports on modeling to predict grain size are rare, making it difficult to optimize the forging process. The present study proposes a modeling method of M647 recrystallization with a coarse γ’ phase and compares modeling and experimental results. Recrystallization was experimentally observed in M647 with a coarse γ′ phase originating from the grain boundaries of the prior γ phase. Moreover, recrystallization is promoted by heating at a high temperature, applying a high strain, and maintaining the heat for a long duration. Grain growth is restricted by the pinning effect of the coarse γ′ phase. The area fraction of the coarse γ′ phase changed with the heating temperature, and the γ′ grain size increased with heating. Electron backscatter diffraction analysis shows that the kernel average misorientation increased with increasing forging temperature. These trends indicate that the pinning and driving forces of recrystallization fluctuate continuously during forging and reheating. The microstructure is predicted by applying Avrami-type equations, but the accuracy is insufficient because the fluctuation effects are not considered.
AB - M647, a Ni-based superalloy with excellent mechanical properties and good hot deformability, was recently developed for application in airplane engine disks. In airplane engines, fine-grained superalloys are required to improve high-temperature fatigue properties. Methods to control fine grains have been extensively studied, including a refined method of applying the pinning effect of a coarse γ′ phase. However, previous reports focused on the mechanism of nucleation and abnormal grain growth, and reports on modeling to predict grain size are rare, making it difficult to optimize the forging process. The present study proposes a modeling method of M647 recrystallization with a coarse γ’ phase and compares modeling and experimental results. Recrystallization was experimentally observed in M647 with a coarse γ′ phase originating from the grain boundaries of the prior γ phase. Moreover, recrystallization is promoted by heating at a high temperature, applying a high strain, and maintaining the heat for a long duration. Grain growth is restricted by the pinning effect of the coarse γ′ phase. The area fraction of the coarse γ′ phase changed with the heating temperature, and the γ′ grain size increased with heating. Electron backscatter diffraction analysis shows that the kernel average misorientation increased with increasing forging temperature. These trends indicate that the pinning and driving forces of recrystallization fluctuate continuously during forging and reheating. The microstructure is predicted by applying Avrami-type equations, but the accuracy is insufficient because the fluctuation effects are not considered.
KW - Coarse γ′ precipitation
KW - Recrystallization modeling
KW - Static recrystallization
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U2 - 10.1007/978-3-030-51834-9_47
DO - 10.1007/978-3-030-51834-9_47
M3 - Conference contribution
AN - SCOPUS:85091313893
SN - 9783030518332
T3 - Minerals, Metals and Materials Series
SP - 482
EP - 490
BT - Superalloys 2020 - Proceedings of the 14th International Symposium on Superalloys
A2 - Tin, Sammy
A2 - Hardy, Mark
A2 - Clews, Justin
A2 - Cormier, Jonathan
A2 - Feng, Qiang
A2 - Marcin, John
A2 - O'Brien, Chris
A2 - Suzuki, Akane
PB - Springer Science and Business Media Deutschland GmbH
T2 - 14th International Symposium on Superalloys, Superalloys 2021
Y2 - 12 September 2021 through 16 September 2021
ER -