Development of a model for the prediction of mechanical properties for Al-Si-Mg castings

A356 alloy is widely used to produce structural components by means of Low Pressure Die Casting (LPDC) process. Generally, a T6 heat treatment (solution, quenching and aging treatment) is carried out to improve the strength of the casting. Nowadays, software simulation of casting processes and solidification phenomena is a common practice for designing sound components even if mechanical strength values and their correlation with microstructure parameters are not given. However, the possibility to predict material behaviour before producing the castings would represent an additional precious tool for exploiting material properties. In the present study, a model for the estimation of tensile as-cast properties based on casting simulation was validated on a 22'' wheel obtained by LPDC. Microstructural and mechanical properties were investigated on the component both in as-cast and T6 condition. First, areas with different thicknesses and cooling conditions were analysed and secondary dendrite arm spacing (SDAS) measurements were carried out. Subsequently, tensile tests were performed on specimens from rim and spokes. Experimental data were used to verify the reliability of simulation results and to validate the as-cast model. Based on additional information provided by simulation software and experimental data, a mathematical model to predict the mechanical properties after T6 heat treatment was also proposed.