The effect of injection velocity on liquid segregation and mechanical properties in arm part fabricated by semi-solid die casting process

Semi-solid die casting of Al alloy is suitable for complicated large parts of near net shape without defect and excellent mechanical properties in comparison with conventional casting process. Die design for the product with high quality in semi-solid die casting is required to prevent micro porosity, inflow of oxidized substances, and liquid segregation. Therefore, shape and size of runner, position and size of overflow and air vent, and arrangement of heating line are very important. Micro porosity, unfilled phenomena, turbulent flow, and liquid segregation occurs during semi-solid die casting. To prevent these phenomena, defect analysis of product according to the change of injection velocity is carried out and optimal injection velocity for high quality product is proposed and simulated. Also, the measurement of mechanical properties according to various injection velocity and heat treatment condition is performed.