Effect of Solid Fraction and Pressure on Microstructure and Mechanical Properties and Reduction in Liquid Segregation in the Thixo-Die-Casting Process with Al-7 Pct Si Alloy

Abstract

In the thixo-die-casting process, the effect of solid fraction and the applied pressure on filling behavior and mechanical properties of the thixo-die-cast product were investigated. By controlling the behavior of solid particles in thixo materials, reduction in liquid segregation during thixo-die-casting was achieved by varying gating systems and solid fractions. Therefore, a gating system with a specially designed runner and gate that controls microstructure to reduce liquid segregation was proposed. As a result, the filling behavior of the semisolid material was dominantly influenced by a solid fraction and a gating system. In addition, mechanical properties were analyzed as a function of solid fraction and applied pressure. The quality index, which assesses ultimate tensile strength (UTS) and elongation, showed that as the initial solid fraction and applied pressure increased, the quality index increased by about 100 MPa.