Hot-Working Characteristics and Dynamic Recrystallization Behavior of Hot Isostatically Pressed FGH4096 Superalloy

Hot-working characteristics, microstructure evolution, and dynamic recrystallization (DRX) of hot isostatically pressed (HIPed) FGH4096 superalloy compressed at the temperature range of 1040 °C to 1130 °C and strain rate range of 0.01 to 10 s −1 were studied. Based on the flow stress curves obtained by friction–temperature correction, a new constitutive equation has been established to predict the flow stresses under different deformation conditions accurately. Also, the hot working maps under different strains were established to optimize the hot working parameters. Different recrystallization behaviors dominate in different hot working regions, and the DRX behavior is sensitive to deformation temperature rather than strain rate. Both continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) are activated for HIPed FGH4096 superalloy under low deformation temperature, while the DDRX dominates under high deformation temperature. The adiabatic shear bands, voids, and cracks along grain boundaries are the main factors of flow instability in the instability regions. The optimized hot working window of T = 1080 °C to 1107 °C and ε̇ = 10 −0.2 to 10 −1.3 s −1 was obtained by combining the hot working map and microstructure evolution.