Enhancing the recrystallization resistance and strength-ductility trade-off of Al–Mg–Si–Cu–Mn alloys by three-step homogenization

Abstract

This study explores a three-step homogenization regime tailored to optimize the dispersoids precipitation, recrystallization resistance, and consequently, the mechanical performance of an Al–Mg–Si–Cu–Mn alloy. Comparative analyses against conventional one-step homogenization treatment reveal a substantial improvement in the precipitation of α-Al(Mn,Fe)Si dispersoids, with a 77.2% increase in number density and a 9.1% reduction in average size. This enhancement is attributed to the optimized nucleation kinetics achieved at an intermediate temperature during the three-step homogenization process. Samples subjected to one-step homogenization treatment experience complete recrystallization after a 1 h solution treatment at 560 °C, whereas three-step homogenized samples exhibit superior resistance to recrystallization, maintaining a well-preserved recovery structure. Pinning force analysis highlights the enhanced effectiveness of dispersoids obtained with the three-step homogenization treatment in inhibiting recrystallization. In terms of mechanical performance, samples underwent the three-step homogenization treatment demonstrate a synergistic enhancement in strength and ductility compared to the one-step homogenized sample. This enhancement is attributed to the intergranular fracture and low working hardening rate induced by the large recrystallized grains present in the samples treated with one-step homogenization.