Improved mechanical properties of AZ31 magnesium alloy sheets by repeated cold rolling and annealing using a small pass reduction

Much less attention has been paid to improve the mechanical properties of magnesium alloy by cold rolling due to its poor room temperature workability. So the present work attempts to improve the mechanical properties of AZ31 magnesium alloy sheets processed by repeated cold rolling and annealing using a small pass reduction in correlation with the concurrent microstructure evolution. The obtained results indicated that after 87% total repeated cold rolling reduction and annealing, the grain microstructure of AZ31 alloy sheet was successfully refined from 22.3 μm to 7.4 μm. The alternating change induced by repeated cold rolling and annealing between deformed microstructure and recrystallized microstructure resulted in the continued refinement of grains. After repeated cold rolling and annealing, the mechanical properties of AZ31 alloy sheets were improved, especially the Erichsen value (IE) of the 87% total rolled sample in annealed condition was significantly increased by more than 36% compared to that of the as-received sample under the same thickness. Improving mechanical properties of AZ31 alloy sheets processed by repeated cold rolling and annealing are ascribed to the grain refinement and weakened basal texture. Finally, 0.40 mm thick thin sheets with good comprehensive mechanical properties were obtained by repeated cold rolling and annealing using a small pass reduction.