The effect of the heat treatments on the tool wear of hybrid Additive Manufacturing of IN718

The application of the Direct Energy Deposition (DED) in the aerospace field offers the potential to manufacture and repair critical components. Nevertheless, the parts produced by DED require finishing operations such as machining. Consequently, the tool wear analysis is usually required to better understand the quality of the manufacturing process, especially when difficult-to-machine materials are involved. In this study, the tool wear analysis was carried out after performing machining operations on DED IN718, considering the material as “as-deposited” and “heat-treated” conditions. The microstructural investigation by electron microscopy analysis was performed to study tool wear depending on the variation of the process parameters. The study highlights the presence of different tool wear mechanisms during the machining of the DED IN718. The results demonstrate a correlation between cutting speed, feed rate, material conditions and tool wear. Indeed, although high values of the process parameters (high cutting speed, high feed rate) caused high wear rate, the material conditions affected the tool wear mechanisms involved. It was also found that the main wear mechanisms during the processing of IN718 were adhesive and abrasive. The tools used to machine the heat-treated materials were characterised by extreme wear as suggested by the crater formation, due to the superior mechanical properties exhibited by the material.