Influence of MnS inclusions on dynamic recrystallization and annealing twins formation during thermal deformation

Abstract

The existence of MnS inclusions during thermal deformation affects the dynamic recrystallization (DRX) behavior and twinning evolution of FCC matrix. In this study, we conducted thermal compression experiments on two sets of materials which are MnS-containing and non MnS-containing specimens, respectively. The mechanism of the influence of MnS inclusions on the dynamic recrystallization behavior of the matrix is revealed. The effect of MnS inclusions on the formation of annealed twins during dynamic recrystallization is clarified from the perspective of plastic deformation of MnS inclusions. The results show that the recrystallization behavior of MnS-containing materials are dominated by DDRX, but assisted by PSN and CDRX. Due to the severe plastic deformation and inhomogeneous deformation of MnS inclusions, the uncoordinated deformation between MnS inclusions and matrix cause the unevenly distributed stress and strain at the interface which provides a higher energy storage for the formation of the twin boundaries during DRX process. According to the growth accident model, the PSN mechanism induced by MnS inclusions produces new grains containing twin boundaries in the DRX nucleation stage, leading to the increase of nucleation rate of the twin boundaries. The faster grain boundary migration velocity promotes the nucleation and progression of twins adjacent to MnS inclusions in the DRX growth stage, thereby increasing the density of twin boundaries. Finally, the evolution of annealed twinning near the MnS inclusions during dynamic recrystallization is elucidated in detail.