The growth and development of Additive Manufacturing (AM) technologies enable the opportunity for producing lightweight structural components, very appealing for application in the automotive field. In this field, the combination of complex geometries that can be obtained by AM, characterized by inner cavities and lattice structures, with aluminum alloys might promote further weight reduction. Among the AM technologies for metals, the Laser-based Powder Bed Fusion (LPBF) one is currently the most industrially-developed. LPBF results in a peculiar very fine and metastable microstructure, that strongly diverges from the one obtained with conventional processes. Therefore, a comprehensive mechanical and microstructural characterization is needed, especially if post-process heat treatments and fatigue behavior are concerned.

In the present work, the AlSi7Mg0.6 (A357) alloy, widely used in the transportation field, was processed by LPBF. Experimental activities were firstly addressed to the optimization of LPBF process, aimed to minimize the defects content (in terms of lack of fusion and gas porosity), that negatively affects mechanical properties, in particular fatigue strength. A special focus was then devoted to tailored heat treatments, specifically designed on the peculiar microstructure induced by LPBF and to enhance the trade-off between strength and ductility. Tensile and fatigue tests were performed to assess mechanical behavior of as-built and heat-treated alloy, followed by microstructural and fractographic analyses. The main purpose of the experimental campaign was the investigation of the relationships between process, microstructural features and mechanical properties. In particular, since most of the mechanical components are subjected to cycling loading, the fatigue behavior of the LPBF AlSi7Mg0.6 alloy is relevant but currently not widely investigated in the literature. Results of the experimental campaign showed that a proper control of the process parameters, including the heat treatment stage, is mandatory to fully exploit the potential of Al based components produced by LPBF.