The Effect of Hold Melt Time against Al-Cu Alloy Hardness and Impact Strength on Recycled Piston and Copper Casting

Abstract

The product quality and estimation of chemical elements in cast products are determined by the melting of raw materials and the alloying of materials. Copper, silicon, magnesium, zinc, and manganese are alloying elements, which are often added either separately or together to aluminum. The alloy element, when found in aluminum castings, can found of different types of hardenings: solution, age, and work hardenings. In this study, copper was added to the piston recycle casting to obtain a hardening of the dissolution. However, the melting point of copper reaches 1200°C, which is two times higher than the melting point of the piston, reaching 600°C. If casting is done at the melting point of copper, then some elements will be lost, and the solubility of hydrogen gas will be greater as a result of the as-cast recycled piston and the reduced quality of copper like this mechanical properties is decreased. In this study, the former piston was re-melted, and copper pieces were inserted into the melted piston at 600°C and held at 800°C for 60, 75, 90, 105, and 120 minutes. The copper solubility phenomenon in recycling a liquid piston due to diffusion events can be demonstrated by the characteristics and mechanical properties of the as-cast recycled piston and copper added. Hardness, impact, and metallographic test specimens from from recycled as-cast product made with permanent molds. The results of specimen testing show that the longer the holding time, the increase in the hardness value and impact resistance of the specimen, and the formation of the Al2Cu phase increases with increasing holding time. The maximum hardness and durability of 86.3 BHN and 9.6 joules/cm2, respectively, were obtained at a hold melt of 120 minutes. In addition, at a holding time of 90 minutes, the formed Al2Cu phase formation is increase so that the Al phase is decrease