Hot deformation behavior and microstructural evolution of a Ni-based wrought superalloy based on 3D hot processing maps

Uniaxial compression tests and microstructural analyses were performed on a Ni-based wrought superalloy across a temperature range spanning the γ+γ’ duplex-phase region (below the γ’ solvus) and the γ single-phase region (above the γ’ solvus). Analysis of the fiow stress curves using an Arrhenius constitutive equation revealed that the activation energy for dynamic recrystallization (DRX) is significantly higher in the duplex-phase region than in the single-phase region. A three-dimensional hot processing map was developed to delineate the infiuence of temperature, strain rate, and strain on the alloy’s workability. The results also indicated that rapid fiow softening at low temperatures (950-980 ℃) and a high strain rate (1 s^-1) is attributable to processing instability. During deformation in the γ+γ’ duplex region, both discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX) mechanisms were active, with DDRX becoming the dominant mechanism at higher temperatures. Initially, the dispersed γ’ precipitates retard DRX. However, these precipitates subsequently dissolve and re-precipitate along DRX grain boundaries as nano- to micro-scale particles, which effectively pin the boundaries and inhibit grain growth.