Investigation on microstructural and hardness evaluation in heat-treated and as-cast state of secondary AlSiMg cast alloys

Abstract The purpose of this study is examining the effects of heat treatment on microstructure and hardness of different secondary Al-Si-Mg cast alloys. In this study, the age-hardening (T6) was applied to AlSi7Mg0.3 and AlSi7Mg0.6 samples casted into the sand mould. The microstructure of cast samples was characterized by optical and scanning electron microscopy. Also, hardness and microhardness tests were carried out. The results indicate that age-hardened samples have better mechanical properties thanks morphology changes of microstructural features and precipitation of Mg phases.