In-Situ Stretched Characterization of Twins and Slip Synergistic Mechanisms in AZ31 Magnesium Alloy Sheets via Hard Plate Accumulative Roll Bonding

The limited ductility of magnesium alloys at ambient temperature is primarily attributed to the restricted activation of slip modes, which leads to a pronounced basal plane texture. To overcome this issue, high-performance AZ31 magnesium sheets were fabricated using a specially designed hard plate accumulative roll bonding (HP-ARB) process. In contrast to conventional Accumulative Roll Bonding (ARB) studies, this work uniquely combines HP-ARB with in-situ electron backscatter diffraction (EBSD), enabling direct tracking of twinning–slip interactions during tensile deformation. Thus, the deformation behavior of AZ31 magnesium alloy sheets treated with HP-ARB under uniaxial stretching at room temperature was studied to clarify the mechanism of enhanced sheet performance. The results demonstrate that the HP-ARB technique effectively reduces the average grain size to 4.23 ± 0.28 μm, achieves an ultimate tensile strength of 312.6 MPa, and results in an elongation of ~ 9.7 pct. These improvements significantly enhance the mechanical properties of the material. During the tensile deformation of the rolled magnesium sheets, at low strain levels, the plastic deformation of the grain c-axis is facilitated by the formation of {10-12} tension twins and secondary twins, which delays plastic fracture and improves ductility. At higher strain levels, the activation of non-basal slip systems increases, thereby diminishing the strong basal plane texture and achieving an optimal combination of strength and ductility. These findings highlight the novelty of integrating in-situ EBSD with HP-ARB and demonstrate a clear pathway to achieve simultaneous grain refinement, twin–slip synergy, and superior strength–ductility balance in magnesium alloys.