Analysis of mechanical strength and corrosion resistance in AA6061-T6 aluminum alloy through optimized heat treatment

This work examines how heat-treatment parameters affect the mechanical properties, corrosion resistance, and fracture behavior of commercial AA6061 aluminum alloy. We used a Taguchi L ₉ (3 ⁴ ) orthogonal experimental design to evaluate the effects of solutionizing temperature (520–540 °C), solutionizing duration (3–5 h), aging temperature (150–170 °C), and aging duration (12–24 h). This research challenges the conventional assumption that maximizing strength in AA6061 inherently degrades electrochemical stability. By modifying thermal parameters that influence the alloy's microstructure, tensile properties, and fracture mechanisms, we determined that the optimal combination of process parameters was solutionizing at 540 °C for 3 h followed by aging at 170 °C for 18 h, which produced the highest ultimate tensile strength of 293 MPa and a hardness of 91 HV due to a refined precipitate distribution. Microstructural evaluation confirmed Mg ₂ Si (β) precipitates and Al-Fe-Si intermetallics. Electrochemical tests in 3.5 wt.% NaCl showed a corrosion rate of 0.0092 mm/year, better than the as-received alloy's rate of 0.0639 mm/year. Fractographic analysis confirmed ductile failure via microvoid coalescence with finer dimples, indicating uniform deformation. Our results show that thermal processing can improve the mechanical properties of AA6061 while preserving its corrosion resistance.