Variabilità di proprietà meccaniche in relazione alle condizioni locali di solidificazione in componenti motore colati in sabbia in lega Al-Si-Cu-Mg

The design trend in the automotive industry towards engine downsizing, driven by stringent European emission regulations, necessitates the use of aluminium alloys with high thermal stability, such as Al-Si-Cu-Mg alloys. The mechanical properties of castings are strongly dependent on the microstructure, which is influenced by casting process and local solidification conditions, geometric complexity, and heat treatment. These factors are challenging to assess using samples cast apart. This study aims to elucidate the dependence of tensile properties on local solidification conditions in a complex Al-Si-Cu-Mg alloy casting produced via sand casting and then subjected to HIP+T6 treatment. Tensile specimens, extracted from the most significant regions of the casting, underwent microstructural and fractographic analysis. The results demonstrate that the mechanical properties of the alloy improve as the secondary dendrite arm spacing (SDAS) decreases, and that the morphology and size of eutectic silicon and intermetallics, both dependent on cooling rate, influence ductility.