Among various additive manufacturing (AM) technologies, wire-and-arc additive manufacturing (WAAM) is one of the most suitable for the production of large-scale metallic components, also suggesting possible applications in the construction field. Several research activities have been devoted to the WAAM of steels and titanium alloys and, recently, the application of WAAM to aluminum alloys has also been explored. This paper presents the microstructural and mechanical characterization of WAAM plates produced using a commercial ER 5183 aluminum welding wire. The aim is to evaluate the possible anisotropic behavior under tensile stress of planar elements, considering three different extraction directions in relation to the deposition layer: longitudinal (L), transversal (T) and diagonal (D). Compositional, morphological, microstructural and fractographic analyses were carried out to relate the specific microstructural features induced by WAAM to the tensile properties. An anisotropic behavior was found in regard to the specimen orientation, with the lowest strength and ductility found on T specimens. Reasoning to this was found in the presence of microstructural discontinuities unfavorably oriented with regard to the tensile direction. The results of tensile tests also highlighted an overall good mechanical behavior, comparable to that of conventional AA5083-O sheets, suggesting future use in the realization of very complex geometries and optimized shapes for lightweight structural applications.

Applying additive manufacturing (AM) technologies to the fabrication of aluminum automotive components, with an optimized design, may result in improved vehicle light weighting. However, the post-process heat treatment of such alloys has to be customized for the particular AM microstructure. The present study is aimed at investigating the effect of different heat treatments on the microstructure, hardness and residual stress of the A357 (AlSi7Mg0.6) heat-treatable alloy produced by laser-based powder bed fusion (LPBF, also known as selective laser melting). There are two major issues to be addressed: (1) relieving the internal residual stress resulting from the process and (2) strengthening the alloy with a customized heat treatment. Therefore, stress-relief annealing treatment, direct aging of the as-built alloy and a redesigned T6 treatment (consisting of a shortened high-temperature solution treatment followed by artificial aging) were examined. Comparable hardness values were reached in the LPBF alloy with optimized direct aging and T6 treatments, but complete relief of the residual stress was obtained only with T6. Microstructural analyses also suggested that, because of the supersaturated solid solution, different phenomena were involved in direct aging and T6 treatment.