Integrated polycrystalline plasticity–cellular automaton model for microstructure evolution driven by discontinuous dynamic recrystallization during thermo-mechanical processing of magnesium alloys

In this study, an integrated polycrystalline plasticity model, referred to as the VPSC-dDRX(CA) approach, was developed for the first time by combining the viscoplastic self-consistent (VPSC) framework, discontinuous dynamic recrystallization (dDRX) mechanism, and a cellular automaton (CA), to predict the microstructure evolution of magnesium alloys during hot deformation. The model was calibrated using isothermal uniaxial compression tests on as-extruded AZ31B magnesium alloy. Temperature- and strain rate-dependent constitutive relationships were established to describe dislocation density (DD) hardening and dDRX behavior over the range of 523–673 K and 0.001–0.1 s⁻¹. Simulation and experimental results under uniaxial compression showed that higher temperatures and lower strain rates enhanced prismatic slip activity, promoted dDRX, and weakened the <0002>//CD texture. The high accuracy of the proposed multiscale framework is evidenced by grain size errors of less than 5% and texture intensity deviations under 10%. The engineering applicability of the proposed model was illustrated through simulations of multi-directional forging (MDF) and conical-die forward extrusion (CDE), which respectively revealed the path sensitivity and regional heterogeneity of microstructural evolution. The proposed model provides accurate predictions of microstructure and texture evolution under complex deformation conditions, offering a robust framework for assessing region-specific mechanical responses and guiding the design of magnesium alloy forming processes.