Influence of pre-strain and heat treatment on subsequent deformation behavior of extruded AZ31 Mg alloy

Pre-compression and heat treatment were performed on an extruded AZ31 Mg alloy, and their effects on subsequent deformation behavior were investigated. The results show that at low temperature annealing (170 °C for 4 h), the extruded samples with and without annealing exhibit a nearly equivalent yield stress (∼148 MPa) because their microstructures are nearly unchanged. However, under the same annealing condition, the yield stress of sample with pre-twinning and subsequent annealing (∼225 MPa) is higher than that of the pre-twinned one (∼200 MPa). The former sample presents a hardening effect because the solute atoms segregated on twin boundaries lead to a strengthening effect. The pre-twinned sample annealed at 400 °C for 1 h shows a higher ultimate elongation (∼28%) than the pre-twinned one (∼15%), but its yield stress (∼125 MPa) is much lower than that of the pre-twinned one (∼200 MPa).