Prediction of Grain Size Evolution During Hot Rolling of HSLA Steels Considering Precipitation

A physical-based model for predicting grain size evolution during multi-pass hot rolling of HSLA steels has been developed, consisting of two coupled modules. The first is a microstructure module based on modeling the interaction of an ensemble of multiple grains. It considers strain hardening, dynamic recovery, and dynamic recrystallization during plastic deformation, as well as static recovery, static recrystallization, metadynamic recrystallization, and grain growth after straining. In the second module, the KWN multiclass approach was used together with classical nucleation theory for simulations of precipitation kinetics during thermomechanical processing. The parameters of the model were obtained through extensive experiments with the Gleeble-machine, thermodynamic calculations with Thermo-Calc software, and microstructural characterizations of selected HSLA steel grades. A user-friendly application for simulating the hot rolling schedule was developed for industrial use. The results of the simulations show good predictability of the simulation system compared to industrial results for different hot rolling schedules.