Additive manufacturing (AM), a technology from Industry 4.0, has emerged in the early 1980s. This innovation offers benefits such as creating complex geometries, reducing mate-rial waste and allowing more customization of parts. Among all the processes, Electron Beam Melting (EBM) is the one studied in this paper. Using EBM for alloy 718, a nickel-iron based superalloy, is particularly interesting as it can withstand high temperature and has good mechanical properties which is promising for industries such as aerospace. However, some defects are present when producing an EBM part. Post-treatments exist to correct it, and the general steps are hot isostatic pressing (HIP), followed by solution treatment (ST) and double aging. Previous works created a knowledge foundation on the understanding of the effect of post treatments, but some gaps are remaining. Our study focuses on broader range of post treatments and its effect on porosity, grain size, delta phase and carbides.

The objective is to study the effects of post-treatments on the material’s microstructure to achieve an optimized protocol.

To do so, samples were prepared, with polishing and etching. Optical microscope was used to observe grain structures and porosity. The electronic microscope helped to have a deeper view on particles morphology. After these practical experiments, an open-source soft-ware, ImageJ, was employed to performed quantitative analysis.

By studying the microstructures, interesting results came out. The first step of post-treat-ment, hot isostatic pressing (HIP) influences porosity content, more than the other post-treatment steps.

The cooling step that comes after HIPing influences the grain size growth; a faster rate renders smaller grains. Solution treatment temperature is a factor in grain size growth and delta-phase content. Depending on the temperature range, delta particles can precipitate which contribute to inhibiting grain growth. Regarding carbides, it seemed that their amount was linked to delta particles amount. When one was low, the other was high, it can be understandable as these two types of particles need niobium to form.

These results are interesting for further studies and applications. The parameters applied can be reused to confirm what was found or changed to find new results that could result in different mechanical properties, that could be interesting for practical applications.