Recrystallisation kinetics of TWIP steel: interface velocity and stored energy

Abstract

In the present article, a modular phase transformation kinetics model has been employed to describe the static recrystallisation behaviour of a high Mn (25 wt-%) twinning induced plasticity steel just after hot deformation. The modular recrystallisation model is based on site saturation with preferential distribution of nuclei, interface controlled growth and impingement of growing particles. The model prediction has been validated with the experimental recrystallisation data of twinning induced plasticity steel. The experimental data were also modelled using Johnson–Mehl–Avrami kinetics based on random distribution of nuclei, which showed worse prediction as compared to the modular transformation kinetic model, thereby indicating the possibility of preferential nucleation around the defect sites. The rate of recrystallisation estimated from the measured fraction recrystallisation decreases sharply within a small recrystallised fraction. The interface migration velocity (interface between the recrystallised grains and the deformed matrix) was estimated from the analytical model. The interface velocity decreases sharply within initial small recrystallised fraction. The calculated stored energy of deformation, from the estimated interface velocity and mobility of the interface, suggests an inhomogeneous distribution within the deformed matrix.