On the Significance of Thermal Deformation and Dynamic Recrystallization on Flow Behavior of 25Mn2Si2Cr Bainitic Alloy

Abstract

Thermal deformation characteristics, dynamic recrystallization behavior, and processing map of 25Mn2Si2Cr high strength bainitic steels are elucidated during wide temperature range (850–1100 °C) and strain rate (0.1–10 s−1) from flow behavior. Thermomechanical analysis by Thermo‐Calc software indicates that microstructure during thermal deformation is austenite, which is conducive to dynamic recrystallization. Phenomenological constitutive equations of thermal deformation, dynamic recrystallization equation, and processing map are established to predict flow behavior. The experimental results indicate that deformation temperature and strain rate have significant effect on thermal deformation process. Flow stress increases with decrease in deformation temperature and increase in strain rate. Increasing deformation temperature and decreasing strain rate promote dynamic recrystallization occurrence. However, the grain size increases with increase in deformation temperature. Thermal simulations predict that optimum thermal deformation parameters are deformation temperature (950–1000 °C), strain rate (0.25–5 s−1) and deformation temperature (850–950 °C), strain rate (1–5 s−1) for processing of Mn–Si–Cr bainitic steels.