Additive manufacturing or 3D printing offers the chance to create complex 3D geometries for specific goals in aerospace, energy, automotive, and medical applications. This type of printing enables the manufacturing of elements that are either economically unfeasible or difficult to manufacture through the usual processes, along with low material waste and decreased tooling requirements. Despite these advantages, the mechanical characteristics of fabricated components remain challenging due to the anisotropic behavior of AM specific microstructure.

The objectives of this thesis were to investigate the microstructure of Alloy 718 manufactured through electron beam melting (EBM), under both as-built and post-treated conditions. In this study, samples were subjected to hot isostatic pressing (HIP) and HIP + solution treatment aging (STA) post-treatments. All samples were produced in the vertical direction in rectangular solid geometry. The studies involved grain width measurements, phases, and defects present, and their respective distribution, also microhardness tests.

The result demonstrates that microstructures were affected by the thermal history, especially concerning temperature and cooling rates. The HIP treatment results in a considerable decrease in the defects amount and dissolution of γ" phase. Consequently, a reduction in hardness for the HIP condition was observed. Furthermore, post-treatments did not affect the inclusions and NbC because of their high solvus temperature. For HIP+STA treatment, a slight rise in hardness value was recorded compared with the as-built condition, which is attributed to re-precipitation of γ" during the two-step aging process whereas grain width remains steady for all conditions in the hatch region.