AZ31 magnesium alloy rolled sheets with alternating distribution of fine and mixed crystal regions were obtained by medium strain rate rolling.The visco-plastic self-consistent(VPSC)models for different microtructure were built.The deformation mechanism,texture evolution and mechanical response of AZ31 magnesium alloy rolled sheets at room temperature were predicted.The contribution of fine and mixed crystal regions on plastic deformation was studied.The results indicate that the fine-grained zone and the mixed-grained zone show the rolling texture characteristics of the rolled plates prepared at 410℃and the average strain rates of 1.9 s-1,4.8 s-1 and 7.8 s-1,while the texture components in the fine grain zone are closer to the ND direction than that in the mixed grain zone.With average strain rate increasing,the difference of the texture components in the fine grain zone and the mixed grain zone gradually decreases.In the early stage of plastic deformation,the main deformation mechanism is basal slip,while the secondary deformation mechanism is prismatic slip and pyramidal slip,and the extension twinning is hardly initiated.The contraction twinning is initiated,causing that some of the grains deflects 56°in the TD direction.This induces the formation a texture component in the TD direction.The activity of prismatic slip decreases,leading that the separation effect of pyramidal slip is enhanced.This finally contributes to the decrease of texture pole density and the formation of bimodal texture in the ND direction.During the tensile deformation process of the rolled plate,the texture components in the fine-crystal regions are closer to the ND direction than those in the mixed-crystal regions,resulting in the fact that the initiation of basal slip decreases and the activation of non-basal slip increases in the fine-grained zone in contrast to the mixed-grained zone.This makes the fine-grained zone strengthen and the mixed-grained zone weaken.The difference of texture components gradually decreases,leading to the deformation mechanism activity of the fine-grained zone and the mixed-grained zone tends to be the same.Finally,the contribution of the fine-grained zone and mixed-grained zone to tensile deformation is gradually similar.
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