Grain Size Evolution during Multipass Hot‐Rolling of C‐Mn Steels: Comparison of Phase Field and Extended JMAK Modeling

Abstract

The design of multipass hot‐rolling schedules is of great importance to steel industry and an effort is made to predict the microstructure evolution. In the present study, a multi‐phase field model is employed for the simulation of the grain size evolution due to static recrystallization and grain growth during multipass hot‐rolling of C‐Mn steels. A variable stored energy per rolling pass, a temperature dependent interface mobility, and nucleation site density are considered. The model is compared with an extended JMAK model and validated with experimental data obtained from two hot‐rolling schedules. The results indicate that both models describe the experimental data well, however the phase field model avoids certain discontinuities between static recrystallization and grain growth. A statistical analysis is conducted to investigate the effect of the microstructure domain size on the phase field results and grain size distributions. The effect of key process parameters on the kinetics of static recrystallization and grain growth are determined by the temporal evolution of equivalent circular grain diameter distributions. Both approaches have the potential to be used for the computational design of multipass hot‐rolling processes in steels.