Ambient extrusion induced working hardening and their effect on mechanical properties in AZ31 hot-extrusion bar

Varying degrees of strain was imposed to AZ31 hot-extrusion bars by ambient extrusion. Mechanical properties were tested along different loading direction to reveal the effect of working hardening on deformation mechanisms and strain hardening behavior. The results showed that, with the increase of extrusion strain, yield strength increased gradually with a sacrifice in ductility. The working hardening from ambient extrusion, on the other hand, showed varying effects for different loading direction due to respective dominating deformation mechanism. Due to the complex crystal orientation, an evident elastic-plastic transition (EPT) stage was found in the 0° and 45° samples. Working hardening could enlarge the EPT stage since it had different effect on basal slip, {101‾2} twinning and prismatic slip.