Effect of different melting practices on mechanical properties of sand cast Al-Si alloy scraps

Abstract

The effect of different melting practices on the mechanical properties of sand cast aluminum-silicon alloy scraps have been investigated in this study. Samples of aluminum alloy products were cast using automobile pistons scraps as charge materials. The castings were carried out at four different locations in Nigeria of Oyo, Ondo, Kaduna States and Abuja. At Oyo and Abuja, the samples were cast in the local aluminum pots casting shops at Saki and Tungamaje respectively. At Kaduna, the samples were cast in Clement Yaro foundry in Kaduna a private foundry, while the samples from Ondo were cast at the foundry of Federal University of Technology, Akure (FUTA). Green sand casting was used to cast all the samples. Chemical and microstructure analysis carried out shows near uniform distribution of Silicon (Si). The results showed that the cast aluminum alloy is hyper eutectics Al-Si (over 16% Si) alloy. Tensile, hardness and impact tests were carried out to determine the mechanical properties. This produced an average percentage accuracy of the ultimate tensile stress and Brinell hardness number for Saki sample, 80.84%; FUTA sample, 82.5%; Kaduna sample, 93.48% and Tungamaje sample, 75.23%. The study has established that with adequate melting practice indigenous casting shops in Nigeria can produce cast products with 90% quality.