Effect of Twins and β‐Mg ₁₇ Al ₁₂ Precipitates on the Mechanical Behavior and Corrosion Resistance of AZ80 Alloy

This study investigated rolling‐assisted aging as a strategy for balancing strength and corrosion resistance in AZ80 alloy. Solution‐treated specimens were pre‐rolled at 8%, 12%, and 16% reductions, then aged at 180 °C for 24 h. Increasing reduction from 8% to 16% raised twin‐boundary density from 0.058 ± 0.009 to 0.121 ± 0.017 μm ⁻¹ and β‐Mg ₁₇ Al ₁₂ area fraction from 11.71% ± 3.25% to 14.64% ± 1.95%. Granular precipitates preferentially observed in twin‐related regions, suggesting twin‑assisted precipitation. Mechanical and corrosion responses showed non‐monotonic dependence on reduction. The 12% rolled‐aged sample achieved the best performance, with tensile/compressive strengths of 388 and 435 MPa, CYS/TYS ratio of 0.775, corrosion current density of 7.69 × 10 ⁻⁷  A·cm ⁻² , and hydrogen evolution of 3.2 mL·cm ⁻² after 300 h in 3.5 wt.% NaCl. Direct aging gave 304 MPa, 368 MPa, 0.495, 6.07 × 10 ⁻⁶  A·cm ⁻² , and 7.7 mL·cm ⁻² , respectively. Increasing the reduction to 16% did not yield further improvement, indicating that the optimal performance is governed by the interplay among grain refinement, precipitate morphology, twin boundaries, and deformation‑induced heterogeneity. The 12% pre‑rolling reduction combined with conventional aging provides a composition‑neutral processing route for enhancing the combined performance of AZ80 alloy.