Microstructure characteristics during the multi-pass hot rolling and their effect on the mechanical properties of AM50 magnesium alloy sheet

The multi-pass hot rolling process of AM50 magnesium alloy sheet was investigated in detailed in this paper. The rough rolling with a 10%, 30% or 50% reduction per pass and the subsequent intermediate annealing at 200 °C and 300 °C were adopted to study their effects on the microstructure and mechanical properties of finish-rolled sheet. Dynamically recrystallized grains nucleated inside deformation twins can be found at the beginning of hot rolling. The intermediate annealing process is not recommended for the rough-rolled sheet with a high reduction ratio per pass. The rolled AM50 sheet exhibits a high strength (UTS: 306 MPa, YS: 236 MPa) and a moderate elongation (15.3%). More excellent ductility (∼26%) can also be obtained with keeping a similar tensile strength to AZ31H sheet.