The corrosion resistance, discharge performance and mechanical properties of 1200 mm AZ31 Mg wide sheets produced by coupled continuous casting–rolling and warm rolling

This study produced wide (900–1200 mm) AZ31 alloy sheets with varying thicknesses via continuous casting direct rolling (7 mm, 6 mm) combined with stepwise warm rolling (4.5 mm, 2 mm), examining the effects of this process on microstructure, corrosion durability, mechanical properties, and discharge properties. Results showed that the reduced thickness significantly refined the grain size from 131.20 µm to 7.90 µm with the basal texture intensity reached 52%. Synergistic grain refinement, dislocation, and texture strengthening improved the yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) of the 2 mm-thick sheet by 59.11%, 39.75%, and 83.52%, respectively, compared to those of the 7 mm-thick sheet. Corrosion durability was also improved, with a corrosion rate of 2.19 mm·y⁻¹ for the 2 mm sheet, which was 41% lower than that of the 7 mm sheet (3.72 mm·y⁻¹), due to the formation of a dense Al(OH)₃ and layered double hydroxide corrosion film with mitigated micro-galvanic corrosion. As an Mg-air battery anode, the 2 mm sheet performed the best at 10 mA/cm², achieving an anode efficiency of 61.18%, specific energy of 1660.50 mWh·g⁻¹, easy discharge product detachment, and reduced self-corrosion. In summary, this study demonstrates a cost-effective and industrially viable approach that combines continuous casting direct rolling with stepwise warm rolling to produce ultra-wide AZ31 sheets with simultaneously improved overall properties, offering a novel strategy to expand the opportunity for commercial Mg alloys in both structural and functional applications.