Optimization of process parameters and microstructure evolution of FGH4096 PM superalloy

In this study, the optimization of process parameters and the microstructure evolution of hot isostatically pressed (HIPed) FGH4096 powder metallurgy (PM) superalloy were systematically investigated. For parameter optimization, on the basis of the traditional constitutive equation and thermal working diagram, double-cone compression + heat treatment and inclusion simulation were innovatively added to further optimize the processing parameters. For the evolution of the tissue, the influence of thermal deformation parameters and the recrystallization mechanism were comprehensively studied. In addition, the evolution of PPBs and the γ′ phase, as well as the role of γ′ relative recrystallization, have also been clarified. The optimized parameters are a temperature range of 1070–1100 ℃, a strain rate of 1–10 s⁻¹, and a strain below 1.8. The PPB networks can be effectively broken through high temperature and high strain rate. γ′ phase exhibited dual functionality during thermomechanical processing:Coarse γ′ (~1 μm) promoted DRX and fine γ' (100–300 nm) suppressed DRX. During the hot deformation process of HIPed FGH4096, DDRX is the dominant DRX mechanism, CDRX serves as an auxiliary DRX mechanism, and twins also promote DRX. The findings of this study provide valuable guidance for optimizing the thermal processing of FGH4096, thereby enhancing microstructural uniformity and mechanical performance.