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

Abstract

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 21 MPa 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.