Dynamic Recrystallization Behavior of a Novel Ni-based Superalloy

The dynamic recrystallization behavior of a novel Ni-based superalloy was investigated by means of isothermal compression tests in the temperature range of 1040-1120 degrees C, and the strain range of 0.35-1.2 with a strain rate of 0.1 s(-1). The microstructure evolution and nucleation mechanism of dynamic recrystallization (DRX) were investigated by optical microscope (OM), scanning electrical microscope (SEM), and electron backscattered diffraction (EBSD). Results show that the critical stress and strain for the initiation of DRX are determined from the work hardening rate curves. The volume fraction of DRX grains increases with increasing the temperature and strain. Both discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX) coexist at low deformation temperature and low strain. The effect of CDRX becomes weaker with increasing the deformation temperature, and DDRX is the dominant nucleation mechanisms of DRX at higher temperatures. With increasing strain, the effect of DDRX becomes stronger, and CDRX can only be considered as an assistant nucleation mechanism of DRX at the latter stage of deformation for the studied superalloy. Additionally, Sigma 3 twin boundary contributes to the nucleation of DRX grains.