Thermal Deformation Behavior and Microstructure Evolution of GH4151 Alloy

Herein, an as‐cast GH4151 alloy is subjected to thermal compression at different temperatures and strain rates by a thermal simulation testing machine. The constitutive equation, dynamic recrystallization (DRX) model, and hot processing map are obtained from the stress–strain curves. The results show that the optimal heat processing conditions are 1100–1120 °C, 0.001–0.01 s−1 and 1100–1135 °C, 0.001–0.1 s−1. Electron backscatter diffraction (EBSD) and scanning electron microscopy (SEM) show that the recrystallization mechanism of GH4151 alloy is mainly discontinuous DRX (DDRX) and is supplemented by continuous DRX (CDRX). Deformation dislocations are eliminated by the phagocytosis mechanism of dislocations during recrystallization, and the subgrains and low‐angle grain boundaries are transformed into high‐angle grain boundaries, which finally form equiaxed grains. In addition, due to the pinning effect of γ′ phase on grain boundaries, the redissolution of γ′ phase during DRX greatly affects grain growth. The optimum deformation range of GH4151 alloy is 1100–1120 °C, 0.001–0.01 s−1, and 1100–1135 °C, 0.001–0.1 s−1. Deformation dislocations are eliminated during recrytallization, and the subgrains and low‐angle grain boundaries are transformed into high‐angle grain boundaries, which finally form equiaxed grains. In addition, the redissolution of γ′ phase during dynamic recrystallization greatly affects grain growth.