Influence of hot isostatic pressing temperature on the hot deformation and dynamic recrystallization of a typical Ni-based powder metallurgy superalloy

Ni-based powder metallurgy (PM) superalloys are crucial for aerospace applications, yet their hot working processes require precise optimization. This study systematically investigates the hot deformation behavior and microstructural evolution of a typical Ni-based PM superalloy prepared under two distinct hot isostatic pressing (HIP) conditions (1190 °C and 1230 °C). Isothermal compression tests were conducted over deformation temperatures of 1095-1155 °C and strain rates of 0.001-0.1 s -1 , with comprehensive microstructural characterization using electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) techniques. The results demonstrate that HIP temperature significantly influences the alloy’s flow behavior and dynamic recrystallization (DRX) mechanisms. The established Arrhenius-type constitutive models reveal substantially higher deformation activation energy for the 1230 °C-HIP processed alloy compared to the 1190 °C-HIP counterpart. Processing maps constructed at different strains show expanding instability regions with increasing deformation. Microstructural analysis reveals that both discontinuous (DDRX) and continuous (CDRX) dynamic recrystallization mechanisms operate simultaneously, with DDRX predominating. For both alloys, DRX under various deformation conditions was predominantly governed by grain boundary bulging nucleation. These findings provide critical guidance for optimizing thermomechanical processing of Ni-based PM superalloys, enhancing manufacturing quality for aerospace components.