Effects of Deformation Processing Parameters on the Microstructure Evolution and Microhardness of GH4169 Superalloy during Annealing Treatment

Abstract

Effects of deformation processing parameters on the microstructural evolution and microhardness of deformed samples during annealing treatment were analyzed. The results show that the initial aging time has the greatest influence on the refinement of annealed grain compared with other processing parameters. This attributes to more δ phases precipitating with the improving initial aging time. The high content of δ phase hinders the quick dynamic recrystallization (DRX) grain growth during annealing. Thus, the high strain rate helps to refine deformed grain by annealing treatment due to a high content of δ phase retained after deformation. Additionally, the massive appearance of recrystallized nuclei/grains also hinders adjacent grain growth. The appearance of many DRX nuclei at high deformation temperature or true strain will cause the fine annealed grain, although the dissolution of δ phase is enhanced. Thus, the grain deformed at 950–1010 °C can be refined to 11–14 μm during annealing. Furthermore, the high true strain is beneficial to obtain fine and homogeneous microstructure during annealing because the high deformation energy promotes static recrystallization (SRX) nucleation. Besides, the microhardness of GH4169 superalloy depends on the grain size and retained content of δ phase due to the fine‐grain and γ″ phase strengthening.