Effects of twin-twin interactions and deformation bands on the nucleation of recrystallization in AZ31 magnesium alloy

Abstract

Investigating recrystallization is essential to optimize the microstructure including texture weakening and grain refinement in the rolling of magnesium alloys, thus to improve the mechanical properties of magnesium sheets for industrial applications. This research has gained an in-depth understanding of the effects of deformation bands and twin-twin interactions on recrystallization, which will potentially lead to improved manufacturing processes and mechanical properties of magnesium alloys. To study their individual effects, the recrystallization mechanisms of the room-temperature (RT)-rolled and liquid-nitrogen-temperature (LNT)-rolled samples during the annealing process were analysed with the quasi-in-situ electron backscatter diffraction method, respectively. It is found that recrystallization mainly occurred in deformation bands in the RT-rolled sample, which enhanced the initially formed texture, due to oriented and inhomogeneous grain growth. However, it is of great interest to see that the recrystallized sites were mainly located around the (101¯2)-(011¯2) twin-twin interactions with high kernel average misorientation (KAM) values in the LNT-rolled samples, resulting in rather weaker texture, finer grain size and more homogeneous microstructure, because of the randomized orientations of recrystallized grains and uniform grain growth, while almost no recrystallization was observed around the single tension twin variant.

Keywords

• Magnesium alloys
• Recrystallization
• Twin-twin interactions
• Texture evolution
• Cryogenic rolling