Effect of Process and Post-Process Conditions on the Mechanical Properties of an A357 Alloy Produced via Laser Powder Bed Fusion

A357 samples were realized by laser powder bed fusion (LPBF) on building platforms heated up to different temperatures. The effect of the preheating temperature and of the post processing heat treatment on the microstructure and the mechanical properties of the samples was studied. It was demonstrated that building platform heating can act as an in situ ageing heat treatment following the fast cooling that arises during laser scanning. A 17% higher ultimate tensile strength was achieved by the selection of the optimum building platform temperature. Moreover, the possibility to further increase the mechanical properties by means of a direct ageing heat treatment was investigated.