Influence of post-weld hot rolling on the microstructure and mechanical properties of AZ31 magnesium alloy sheet

The as-rolled AZ31 Mg alloy sheet was welded by double-sided tungsten inert gas (TIG) welding, followed by annealing and hot rolling with different reduction. The influence of the rolling reduction on the microstructure, tensile properties and microhardness of the specimens was examined. Results showed that the microstructure of the weld fusion zone (FZ) and heat affected zone (HAZ) became more and more consistent with that of the base metal (BM) as the hot rolling reduction increased. The β-Mg17Al12 phases in the FZ dissolved gradually during hot rolling. Both the weld joint and BM were strengthened by hot rolling; the tensile strength of weld joint and BM were closest when the rolling reduction was 27%. The microhardness of the welded sheet increased with rolling reduction.