Development of ultrafine-grained magnesium alloy AZ31 by multi-pass warm rolling

High-strength bulk ultrafine-grained magnesium alloy AZ31 bars were successfully developed in this study using multi-pass warm rolling. AZ31 bars of 12 mm diameter and several meters length were produced by multi-pass warm rolling of 45 ×45 mm forged blocks at 250°C and 300°C. The yield strength of warm-rolled rods doubled without any apparent loss of elongation. X-ray diffraction analysis revealed that the fractions of the basal planes oriented along and perpendicular to the rolling directions are nearly similar in intensity levels, indicating no strong texture along the rolling direction. The drastic improvement in mechanical properties is attributed to the ultrafine-grained microstructure in the warm-rolled specimens, whereas the absence of the loss of elongation is attributed to the fewer number of twins.