Abstract:

Presetting tensile twins (TTs) can enhance the mechanical properties of magnesium (Mg) alloys. Two as-received (AR) sheets, as-received state-A (AR-A) with fiber texture and nonuniform grains and as-received state-B with basal texture and uniform equiaxial grains are selected to induce TTs via a novel method called corrugated wide limit alignment (CWLA), and the corresponding CWLA-processed sheets are denoted as CWLA-processed state-A (C-A) and CWLA-processed state-B (C-B). The results demonstrate that a larger initial average grain size correlates with a higher fraction of TTs induced in Mg sheets, thereby refining the grains and forming a new rolling direction (RD) tilted texture during CWLA. The ultimate tensile strength increases by 32% from AR-A to C-A, primarily due to refinement strengthening and twinning-induced strain hardening. The recrystallization mechanism of C-A is dominated by twinning-induced dynamic recrystallization (DRX), where DRX grains prefer to inherit the orientation of TTs, resulting in an enhanced RD-tilted texture and the formation of multi-modal texture. The recrystallization mechanism of C-B is mainly discontinuous DRX and continuous DRX, and the DRX grains prefer to inherit the orientation of matrix grains, ultimately forming a basal texture. In summary, the tensile mechanical behavior of pre-twinned Mg sheets significantly depends on the grain size and texture of the AR sheets, so they present similar changing trends during tensile deformation.

Key words: Mg sheet, Texture, Grain size, Corrugated wide limit alignment (CWLA), Tensile twin (TT), Dynamic recrystallization (DRX)