Twinning-induced shear banding and its control in rolling of magnesium

Rolling of magnesium sheets is challenging at temperatures below 200 degrees C due to the strain localization and shear banding associated with the twinning activity. In this study, magnesium sheets with basal, off-basal (90 degrees tilted), and mixed (50% basal + 50% off-basal) textures are rolled between room temperature and 165 degrees C to understand and control the twinning-induced localizations. While the fraction of strain-localized regions increases from 0.1 to 0.6 with strain and temperature, the intensity of them are controlled by the starting textures. The sheet with basal texture develops the most intense localizations at room temperature, and fails by shear banding at 0.16 strain. Off-basal sheet, on the other hand, has similar fraction of twins and localizations but deforms to the strain of 0.36 without shear banding. Maximum uniform strains increase with temperature and reach to 0.60, 0.50, and 0.33 at 165 degrees C for off-basal, mixed, and basal textures, respectively. When the fraction and intensity of localizations are incorporated to a model treating the continuum as a composite, it is possible to capture the shear banding and failure during rolling. The model correctly predicts the maximum strains for a given starting texture and temperature.