Unveiling the ductility improvement mechanisms of AZ31 Mg alloy with weakened basal texture at relatively low temperatures

In this work, an efficient and innovative texture weakening and grain refinement method, shear strain induced twin orientation regulation (SITOR), was used to improve the ductility of AZ31 at relatively low temperatures below 200 °C and the corresponding ductility increasing mechanism was explored. In this way, the grains of the SITORed sample were fine and uniform, the strong basal texture was weakened significantly, and a new SITORed texture was formed about 43° away from the parent basal plane. The results showed that the ductility of SITORed AZ31 was significantly improved at relatively low temperatures compared with initial AZ31 alloy. The basal slip dominated the deformation at room temperature which made the fracture elongation increasing from 15.3% to 32.6%. At 100 °C and 150 °C, the basal slip was more active than prismatic slip and pyramidal slip at the initial stage of plastic deformation, and the activity of prismatic slip increased and gradually dominated the deformation with the increase of strain. The fracture elongation increased nearly by 30% at 100 °C. At 150 °C, the fracture elongation of SITORed sample was as high as 63.9%. The fracture elongation increased to 81.7% at 200 °C, which was nearly 35% higher than the original sample. This was due to the occurrence of continuous dynamic recrystallization behavior and multiple slip modes co-actuation.