Effect of Deformation Temperature on Microstructure and Mechanical Properties of AZ31 Mg Alloy Processed by Differential-Speed Rolling

A differential-speed rolling (DSR) was applied to AZ31 magnesium alloy sample at different rolling temperatures of 473, 523, 573, and 623K with 1-pass and 2-pass operations. The microstructural evolution and mechanical properties of the deformed samples were investigated. The rolling temperature was found to be an important parameter affecting the microstructural development. After DSR at 473K, the microstructure was more homogeneous than that obtained after deformation by equal-speed rolling (ESR). The fully recrystallized microstructures were generated after DSR at 573 and 623K. As to mechanical properties, the yield strength (YS) and ultimate tensile strength (UTS) decreased monotonously with increasing rolling temperature. In contrast, the elongation of the DSR-deformed samples was improved as the rolling temperature increased. The strain hardening exponent (n) calculated by Hollomon equation increased with increasing the rolling temperature, which would explain an increase in the uniform elongation.