Influences of pouring temperature and cooling rate on microstructure and mechanical properties of casting Al-Si-Cu aluminum alloy

Xiaowu HU,Fanrong AI and Hong YAN School of Mechanical Electrical Engineering,Nanchang University,Nanchang 330031,China

摘 要：This paper investigated the influences of pouring temperature and cooling rate on the microstructure development and mechanical properties for casting Al-Si-Cu aluminum alloy.The microstructure of the as-cast samples was characterized by an optical microscope.The results showed that the dendrite arm spacing（DAS,λ） is well refined by pouring at a higher temperature.The λ decreases with increasing pouring temperature due to the multiplication of the nucleation sites in the superheating liquid melt,and the mechanical properties,such as microhardness and ultimate tensile strength increase correspondingly,while the elongation decreases.The relationships between microhardness and λ for the samples cooled in metal mould and sand mould,are given as HV=118.9 1.246λ and HV=115.2 1.029λ,respectively.The effects of the cooling rate controlled by using permanent mould casting and sand mould casing processes（the cooling medium is air and sand,respectively） on the dendrite arm spacing and mechanical properties are similar to the effect of the pouring temperature.

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