Development of mechanical properties in AZ31 magnesium alloy processed by cold dynamic extrusion

In this study, AZ31 magnesium alloy plates with fine grained microstructure were processed by cold dynamic extrusion followed by low temperature annealing. The corresponding microstructure evolution and mechanical properties were systematically investigated, with a great emphasis on the effect of high {10−12} extension twin density. Profuse {10–12} extension twin and nanograined structure was generated in various regions after 20% cold dynamic extrusion. Thus, pre-twinning greatly improved the strength and ductility in magnesium alloy. In addition, the introduction of high twin density can be an effective way to improve mechanical properties of magnesium alloy via twin-dislocation interaction during plastic deformation. With mechanical behavior properly described, high twin density increases the uniformity of localized dislocation plasticity, thereby improving the strain hardening property. Also, we conclude that high strain rate in cold dynamic extrusion can be considered as an effective method for preparation of pre-twinning magnesium alloy, which exhibits good mechanical properties.