Trapezoidal compression induces texture-dislocation heterogeneity for enhanced formability in AZ31 magnesium alloy sheets

Strain path plays a critical role in governing the deformation behavior and formability of Mg alloy sheets. Here, trapezoidal compression was applied to AZ31 Mg alloy sheets to introduce nonuniform contact and constraint conditions, thereby generating spatially differentiated stress-strain states during deformation. The imposed strain path partitioned plastic deformation into distinct micromechanical domains. High-strain regions accommodated deformation primarily through dislocation accumulation and lattice rotation, whereas shear-dominated regions preferentially activated {10−12} tensile twinning. This mechanistic partitioning produced spatial variations in stored energy, the organization of which, rather than its absolute magnitude, governed the recrystallization pathway during annealing. The resulting microstructure consisted of fully recrystallized domains with weakened texture and partially recrystallized domains retaining dense dislocation substructures and sharpened basal texture. This inherited texture-dislocation heterogeneity enabled an exceptional combination of strength retention and ductility enhancement. The tensile elongation increased from 19.6% to ~30% while preserving tensile strength, and the Erichsen cupping value increased from 2.52 mm to 8.54 mm, corresponding to 340% of the as-received condition. Semi-quantitative estimation based on kernel average misorientation confirms that the retained geometrically necessary dislocations contribute measurably to the domain-level mechanical contrast. This contrast generates persistent back stresses that promote pyramidal <c + a> slip activation in hard-oriented grains, sustaining work hardening and delaying strain localization. These findings demonstrate that strain-path-controlled spatial organization of defects provides an effective pathway for achieving high formability in magnesium alloy sheets.