Effect of annealing time on bimodal microstructures and tensile properties of Mg-6Sn-3Al-1Zn alloy

Although the Mg-6Sn-3Al-1Zn alloy with bimodal grain size distribution has excellent mechanical properties, its mechanical properties can further be improved by adjusting or controlling its microstructures through annealing. In this study, the effect of annealing time on microstructures and mechanical properties of the Mg-6Sn-3Al-1Zn alloy was systematically studied. The Mg-6Sn-3Al-1Zn alloy with bimodal microstructures was prepared through pack-rolling with two passes at 450 °C (55 % thickness reduction per pass, and the total rolling deformation is 80 %). Then the alloy was annealed for 10 min, 20 min, 30 min and 40 min at 350 °C, respectively. The results showed that volume fractions of Mg2Sn phase and recrystallization grains increased with increasing of the annealing time. The multi-modal microstructures were formed in alloys after annealing. When the annealing time ≤30 min, the average grain size of the alloy increased with increasing of the annealing time, while it decreased after annealed for 40 min. The intensity of {0001} texture decreased with increasing of annealing time (