Microstructural evolution and mechanical behavior of twin roll cast AZ31 magnesium alloy sheets: An insightful analysis based on the RC–Sachs model

Twin roll cast (TRC) AZ31 magnesium alloy sheets combine high processing efficiency with microstructural homogeneity, offering significant potential for advanced forming processes and high-end structural applications. However, the evolution of texture-induced anisotropy during hot rolling and the underlying mechanisms enabling simultaneous high strength and ductility remain insufficiently understood. In this study, the microstructural evolution and anisotropic mechanical response of TRC AZ31 sheets during hot rolling are systematically investigated through integrated experiments and mechanism-based modeling. Detailed characterization reveals that dynamic recrystallization (DRX)-induced grain refinement and the strengthening of the basal < 0002 > //TD texture dominate the mechanical response and anisotropy of the rolled sheets. Hot rolling substantially increases both yield strength and ultimate tensile strength, whereas the intensified basal texture limits ductility, leading to a characteristic strength-ductility trade-off with strong directional dependence. To elucidate the interaction between slip and twinning, a relaxed-constraint Sachs (RC-Sachs) constitutive model is developed, incorporating texture statistics, slip-twin activation, and grain-size effects. The model accurately reproduces orientation-dependent stress-strain responses across distinct texture states, with a mean error below 5%, and quantitatively captures the texture-controlled transition of operative deformation mechanisms. The analysis further identifies that moderate weakening of the basal texture, combined with enhanced grain refinement, provides an effective pathway for achieving concurrent high strength and ductility. This work establishes a mechanistic foundation and a predictive modeling framework for the integrated optimization and performance-oriented design of magnesium alloy sheets.