Mechanical Behaviour of 319 Heat Treated Thixo Cast Bars

Abstract

Among cast aluminum alloys, 319 ranks as one of the commercially important alloys used in automotive applications, on account of its excellent casting characteristics and good mechanical properties. It has become one of the candidates for shaping the aluminum alloys in the semisolid state or thixocasting. Semisolid bars have been heat treated in T4, T5 and T6 conditions and the microstructural evolution followed by optical and scanning electron microscopy. Hardness measurements have been performed on aged samples to follow the precipitation process. After aging, samples were prepared for tensile test at room temperature and the effect of thermal treatment on mechanical properties has been studied. Hardness measurements revealed a delay in precipitation starting in T5 with respect to T6 due to the lack of supersaturation. T5 aging treatment gives satisfactory results for elongation because the ductility values are comparable with the results from T6, while the UTS values are slightly lower. The thixocast 319 alloy has definitively good mechanical properties compared to the 319 alloy produces by other casting techniques.