Mechanical properties and microstructure of as-extruded AZ31 Mg alloy at high temperatures

The mechanical properties of deformed AZ31 Mg alloy at high temperature of 450–600 °C with a strain rate of 3 s−1 were investigated by tensile tests. The zero strength of AZ31 Mg alloy was emerged at a mushy state (600 °C), while the zero ductility was appeared at 575 °C, just below the solidus temperature. The abnormal coarsening of the grains happened at the temperature of 525–575 °C and some molten grain boundaries were observed at 600 °C. Finally the morphology and crack propagation of fracture surface were also discussed.

► Mechanical properties and microstructure of AZ31 were investigated at 450–600 °C.
► The zero ductility and zero strength were emerged at 575 and 600 °C, respectively.
► Morphology of sugar-like was observed clearly in the fracture surface at 575 and 600 °C.
► Molten grain boundaries were observed in the fracture surface at 600 °C.