Influence of T6 and T7 Heat Treatments on the Mechanical Properties of Rheocast Secondary AlSi7Cu3Mg Alloy

The effects of T6 and T7 heat treatments on the mechanical properties of a rheocast secondary AlSi7Cu3Mg alloy are investigated. A lower arm automotive suspension was cast as a demonstrator. While the solution treatment was optimized in previous research, the quenching rate and the ageing treatment were here studied. The influence of the quenching process on the component's distortion was analysed by a coordinate-measuring technique. The results indicated a significant effect of the quenching rate on the tensile properties as well as the distortion of the component. Water quenching led to a greater distortion of the component compared to still-air cooling. The elongation to fracture seemed to be less affected by the quenching process. Higher ductility was obtained after the over-ageing T7 treatment, while the yield and tensile strengths were similar to those obtained after a peak ageing T6 treatment.