Analysis of Heat Treatment and Its Effects on the Machinability of Inconel 718 Products Manufactured with Wire and Arc Additive Manufacturing Technique

This work analyzes the effects of different heat treatments on Inconel 718 samples produced with the Wire and Arc additive manufacturing (WAAM) technique and their impact on the machining process of the WAAM products. Since this alloy is a material known for its complex machining procedure, heat treatment is a possibility to improve this manufacturing step. This research was divided into two different parts. First, two distinct heat treatments (solution and homogenization) were performed, and the samples after treatment were compared regarding their microstructure and Vickers hardness. These heat treatments were performed with varying timings to assess possible changes in the original microstructure with those changes. Solution (980 degrees C) and homogenization (1080 degrees C), two commonly applied heat treatment steps with known temperature ranges were performed for 1, 4, 8, and 12 h. In the second step of the research, the machinability of the side milling process was assessed regarding the cutting forces, surface roughness, and tool wear, and by comparing the results for those parameters, it was possible to observe and conclude that even though there were significant changes in the microstructure of the samples that the improvement of the machinability of the Inconel 718 samples with the heat treatments was not achieved, since the objectives of reducing cutting forces, improving surface roughness and reducing tool wear was not possible with predictability and for the same parameter.