Mechanical behaviour and microstructural evolution of magnesium alloy AZ31 in tension at different temperatures

The mechanical behaviour and microstructure changes of the magnesium alloy AZ31 have been studied in tension at various temperatures, from RT to 250 °C. Continuous dynamic recrystallization (DRX) under tension was observed for temperatures higher than 150 °C. Texture components corresponding to a high activation of 〈c + a〉 slip systems were observed from 200 °C. DRX occurs by rotation recrystallisation. At 200 °C a strong texture is conserved despite the occurrence of DRX, which is typical for rotation recrystallisation and concurrent grain deformation by slip. At 250 °C, where superplastic behaviour is observed, the texture of small grains weakens due to grain boundary sliding as an additional deformation mechanism. The dramatic changes in the mechanical behaviour at elevated temperature can thus be explained by the occurrence of DRX, the high activities of non-basal slip systems and the occurrence of grain boundary sliding.