Hot deformation behavior and dynamic recrystallization mechanisms of GH4975 alloy prepared by electron beam smelting layered solidification

In this work, the hot deformation behavior and dynamic recrystallization mechanisms of GH4975 prepared by electron beam smelting layered solidification were studied. The friction and temperature correction were applied to the stress-strain curves, and the constitutive equation were established and the hot deformation activation energy was calculated to be 1449.748 kJ/mol. Thermomechanical processing map of GH4975 alloy was build and verified by deformation microstructures. Additional, the microstructure evolution and dynamic recrystallization (DRX) mechanisms were analyzed in detail by electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM). The evolution of dislocation and the dislocation density are characterized in detail during deformation. The results show that high temperature and low strain rate were conducive the occurrence of DRX. Three DRX mechanisms can be discovered during deformation. The recrystallization mechanism of GH4975 alloy is dominated by discontinuous dynamic recrystallization(DDRX) characterized with grain boundary bulging, and assisted by continuous dynamic recrystallization(CDRX) characterized with subgrain rotation. Additional, twin boundaries-induced nucleation (TDRX) can be as supplementary nucleation mechanism.