Investigating the influence of Si on dynamic recrystallization during hot deformation behavior of ultra-high-strength lightweight steel

Abstract

In this work, we systematically evaluated the effect of Si on the dynamic recrystallization (DRX) during hot deformation behavior of a novel high-strength rolled Medium Mn steel. To this end, the novel steel was subjected to compression test in the temperatures of range temperature of 950–1150 °C and the strain rate of range of 0.01–10 s−1. Numerical simulation, constitutive analysis, different models and processing maps were also developed to predict the volume fraction of DRX, which was further confirmed through electron backscatter diffraction (EBSD). The results show that some disparities are existed between the model predictions and the results. The EBSD micrographs of samples displayed prominent discontinuous DRX peak in the true stress-strain curves exhibit conventional equiaxed DRX particles. Most specifically, in initial stages the addition of Si increased the DRX and grain boundary migration, and the later stages of deformation the DRX was triggered after achieving the steady state. Therefore, the final microstructure appears as elongated austenite or localized DRX. Furthermore, the work hardening stage before the new round of DRX nucleation caused the stress to continue to increase after the steady state. These findings provide valuable insights into the complex behavior of materials under the influence of Si addition and enhancing our understanding of microstructural evolution during hot deformation.