Effects of zinc addition on microstructure and properties of aluminum based alloys fabricated by sand casting process

Abstract

Al-Zn alloys were prepared by using sand casting method. The casting process was carried out by several stages that are the preparation of pattern, making of core box, sand mold, melting of raw materials and pouring. The samples were prepared with different weight percentage of Zn which are 15%, 30% and 45%. By using aluminum and zinc ingot as raw materials, all samples were successfully prepared in form of dumb-bell shape. The result obtained from this study was the grain size of microstructure of as-cast product decreased with increasing of Zn content. 100%Al has the largest grain size (0.1940 mm) and Al-45% Zn has the smallest grain size (0.0414 mm). The addition of Zn into Al-Zn alloy increases mechanical properties of as-cast product. As the Zn content increases, the ultimate tensile strength of samples and hardness values also increased. Highest UTS value for this study was 41.49 MPa (Al- 45%Zn) and the lowest value was 33.61 MPa (100%Al). Highest HV value for this study was 125.86 HV (Al-45%Zn) and the lowest value was 64.10 HV (100%Al). From this study also explained that, increasing the Zn content increases % porosity of as-cast samples but decreases in density. Highest value of density for this study was 2.74 g/cm³ (Al-45%Zn) and the lowest value was 2.56 g/cm³ (Al). However, highest percentage of porosity for this study was 0.92% (Al) and the lowest value was 0.65% (Al-45%Zn). In addition, defects also detected from this research. The defects were appeared on as-cast products were misruns, swell and porosity. This problems occur due to improper controlling parameter used.