Simulations On Microstructure Evolution Of Dynamic Recrystallization During Hot-working Process By Multi-phase-field Model

It is difficult to real-time observe the dynamic recrystallization microstructure evolution in metal thermal processing experimentally. In order to understand the evolution of recrystallization microstructure in thermal processing and determine processing parameters for thermal processing.The multi-phase-field method based on the Ginzburg-Landau kinetic equation coupled with the dislocation density model were used to simulate the dynamic recrystallization phenomenon. The effects of different temperatures and strain rates on dynamic recrystallization were investigated, and the reason for the variant of the stress-strain curve from a single peak form to a multi-modal form was illustrated. The multi-phase-field method was adopted to simulate the multi-stage deformation process, including the effects of static recovery and different thermal processing parameters on the dynamic recrystallization kinetics. The results show that the grain size increases in the ceasing of continuous deformation, and higher temperature and lower strain rate can accelerate the process of dynamic recrystallization. Considering the uneven storage energy caused by the uneven compressive deformation, the effects of the initial stored energy on the dynamic recrystallization were investigated. In addition, the second phase were firstly introduced into the multi-phase-field simulation, and the smooth change of phase-field variables between the second phase and the matrix was realized. The model was used to simulate the pinning effect of the second phase particle on the grain boundary migration, and the effects of the different shapes and content of the second phase particles on the dynamic recrystallization process. These results are in aggreement with the experimental and simulation results in the literature, indicating that the model has great practical applicability.