Twining evolution and dynamic recrystallization mechanism in GH4706 alloy during hot deformation

Abstract

The dynamic recrystallization (DRX) mechanisms and microstructural evolution of the GH4706 alloy are investigated through isothermal constant strain rate hot compression experiments. The experiments are conducted under different deformation parameters. The effects of different deformation parameters on the substructure, grain boundary (GB), misorientation and twinning are systematically studied. The results indicate that T (Temperature), $\dot{\epsilon }$ (strain rate), and ε (strain) significantly influence the DRX mechanism and microstructural evolution of GH4706 alloy. As ε increases, Σ3 twin boundaries deviate from their specific orientation. However, new twin structures are formed during the recrystallized grain growth process, with high T and low $\dot{\epsilon }$ being more conducive to twin formation. Additionally, discontinuous dynamic recrystallization (DDRX) behavior is identified across all deformation parameters, establishing DDRX as the prime process of DRX in the GH4706 alloy. Continuous dynamic recrystallization (CDRX) typically occurs within grains as an auxiliary nucleation mechanism, particularly active at lower T, higher ε and higher $\dot{\epsilon }$. Meanwhile, twin boundaries provide ideal nucleation sites for DDRX and CDRX grains, thereby accelerating the recrystallization process via twin-induced dynamic recrystallization (TDRX).