Superplasticity Enhanced by Two-stage Deformation in a Hot-extruded AZ61 Magnesium Alloy

摘要

A two-stage strain rate deformation method is proposed to enhance the superplasticity in a hot extruded AZ61 alloy. In the stage-one of deformation, a relatively high strain rate was applied in order to obtain fine grains through dynamic recrystallization. The optimum strain rate for DRX at 300 deg C was identified as approx 5X10~(-3) s~(-1). Stage-two is conducted at relatively low strain rate in order to utilize the fine grains refined by DRX during stage-one to make the grain boundary sliding operate more smoothly, which resulting in enhanced superplastic elongation from 350 percent to 440 percent