Microstructure evolution and mechanical properties of twinned AZ31 alloy plates at lower elevated temperature

•Twinned AZ31 alloy plates exhibited higher strength at low elevated temperature.•Grain refinement induced by pre-existing twin boundaries improved the strength.•Twinned AZ31 alloy plates exhibited more pronounced flow softening at 200°C.•DRX softening induced by pre-existing twins led to the flow softening at 200°C. The AZ31 alloy plates were pre-rolled at room temperature along the transverse direction to introduce extension twinning. The effect of pre-existing twins on the mechanical properties of AZ31 alloy plates at lower elevated temperature was investigated in the current paper. The results revealed that the twinned AZ31 alloy plates exhibited higher strength at lower elevated temperature than the as-received plates without a large reduction in elongation, especially the yield strength increased by 36, 30 and 21MPa at room temperature, 100°C and 200°C, respectively. The improved strength is attributed to the grain refinement by pre-existing {10–12} twin boundaries. Compared with the as-received AZ31 alloy plates, the twinned plates exhibited more pronounced flow softening at 200°C, which can be interpreted by the dynamic recrystallization softening effect induced by pre-existing twins.