A good balance between ductility and stretch formability of dilute Mg-Sn-Y sheet at room temperature

Abstract

In order to develop new magnesium alloy sheets with a good balance between ductility and stretch formability at room temperature, here we designed an Mg alloy with dilute Sn and Y and investigated the microstructure, texture, mechanical properties and stretch formability of Mg-0.4Sn-0.7Y in wt% (TW00) alloy compared with AZ31 alloy under extrusion and hot rolling-annealing conditions. We found that, after extrusion, the extruded TW00 (TW00-E) sheet exhibited a more homogeneous complete dynamic recrystallized microstructure and a splitting texture character with ~±20° tilted to the extrusion direction, compared with the extruded AZ31 (AZ31-E) sheet. After hot rolling-annealing at 400 °C, both the hot rolled annealed TW00 (TW00-RA-400) and AZ31 (AZ31-RA-400) sheets presented similar complete static recrystallized microstructures. However, significant texture weakening occurred in the TW00-RA-400 sheet rather than the AZ31-RA-400 sheet, due to static recrystallization induced by twins and grain boundaries. Tensile tests revealed that the TW00-E and TW00-RA-400 sheets with high Schmid factor (SF) for basal slip exhibited high ductility (~ 33% and ~ 32%). Simultaneously, prismatic <a> slip and texture weakening played a significant role on decreasing r-values for the TW00-E and TW00-RA-400 sheets, respectively, which contributed to the improvement in stretch formability (~ 6.2 mm and ~ 5.4 mm) at room temperature. Therefore, we concluded that the TW00 alloy provided a bright prospect to achieve a good balance between the ductility and stretch formability at room temperature via extrusion or hot rolling-annealing.