Influence of warm rolling and aging on the microstructural evolution and mechanical behavior of AZ31 magnesium alloy

Abstract

The microstructural evolution and tensile properties of AZ31 after warm rolling and different aging methods and conditions were investigated. The warm rolling was conducted on the as-received AZ31 after homogenization at 400°C for 3h. The rolled slabs were artificially aged at different temperature of 120°C, 180°C and for various durations. As an alternative approach, stress aging was applied on the samples. The results of tensile tests illustrated that the ultimate tensile strength of the as- received AZ31 after 24h aging at 120°C increased up to 300 MPa with the expense of 5% reduction in elongation. While the ductility of the sample aged at 180°C and 48h increased to 14% with the UTS of 285MPa. Also, the stress aging at 120 °C for only 1h increased the yield strength of as-received sample to over 240 MPa. This points to almost 50% increase in strength thermo-mechanical processing. Microstructural observations revealed that the grain growth firstly decreased the strength of rolled samples while improving the ductility. This is followed by the nucleation of recrystallized grains during ageing enhanced the strength with decent ductility as compared to the rolled samples.