Synchronously enhancing the creep performance along two different loading directions in hot-rolled Mg-2wt%Sn alloy plate

Abstract

To save rare-earth (RE) resource and develop creep-resistant Mg alloys in a low-cost way, RE-free Mg alloys are strongly recommended recently. However, serious creep anisotropy and poor creep resistance are still the main problems of safely using RE-free Mg alloys. In the present research, one binary Mg-2wt%Sn hot-rolled plate was employed for studying the compressive creep performance at 393 K. It was found that different activities of basal slip, twinning and pyramidal slip weakened the creep performance along the rolling direction and caused the inevitable creep anisotropy. To weaken the creep anisotropy between the rolling direction and normal direction, multi-directional forging (MDF) with three passes was performed at 393 K. Through inducing high-density twins before creep loading, detwinning was frequently activated during creep loading instead of inducing new twins. As a result, the creep anisotropy was successfully weakened in the MDF processed alloy. Moreover, the creep performance was synchronously enhanced along both loading directions rather than deteriorating the creep performance along the normal direction. It is thus expected that this RE-free way of preparing creep-resistant Mg alloys can be widely accepted in the relative application fields.