Achieving High Strength in Micro-alloyed Mg-Al-Ca-Zn-Mn-Ce Alloy Sheet Processed by Single-Pass Large-Strain Rolling

A low-cost and high-strength Mg-Al-Ca-Zn-Mn-Ce-based alloy sheet has been developed and fabricated by single-pass large-strain rolling process. Effects of rolling temperatures on the microstructure and mechanical properties of the Mg sheets have been investigated. The results show that the grain sizes of the Mg sheets are remarkably refined to be ~ 1.5 and ~ 0.8 µm after rolling at 350 and 250 °C (denoted as X-350 and X-250), respectively. The fine nano-precipitates are found to distribute both within the grain interiors and along the grain boundaries. co-segregations of Ca and Zn atoms also readily occur in present Mg sample, and the solute concentration increases with the decrease in rolling temperature. Nano-precipitates and solute segregations can effectively impede the grain growth and contribute to the grain refinement in as-rolled Mg samples. Optimal mechanical properties have been obtained in X-250 sheet rolled at 250 °C, exhibiting the YS, UTS and EL of ~ 290 MPa, ~ 304 MPa and 11.6%, respectively. The ultra-fine grains, solute segregations and the intensified basal texture play the critical roles together.