Impact of Intensification Pressure and Grain Refiner on the Hot Tearing Susceptibility of a Semi-Solid Cast Al-Zn-Mg-Cu Alloy

Abstract

The commercial application of wrought aluminum alloys to semi-solid casting would be extremely beneficial, as wrought alloys often exhibit better strength-ductility combinations than cast aluminum alloys. Semi-solid casting typically reduces the hot tearing tendency, as it requires a globular microstructure and produces grain refinement, but hot tearing often still occurs during the semi-solid die casting of complex-shaped components produced from wrought alloys. This study examined the impact of intensification pressure and grain refinement on the hot tearing tendency of an Al-Zn-Mg-Cu alloy. Semi-solid slurries were produced using the SEED (Swirled Equilibrium Enthalpy Device) process. A specially designed constrained rod mold was used to evaluate hot tearing. Results showed the tendency for hot tearing decreased with increasing of intensification pressure. Grain refinement (with 0.06Ti) was also found to be beneficial to the elimination of hot tearing.