Optimisation of process parameters for Directed Energy Deposition (DED) of IN718 nickel-based superalloy

In this Thesis assignment, the goal was to find the optimum process parameters to produce Inconel 718 alloy via Directed Energy Deposition (DED). Therefore, for this purpose, the experimental analysis considered three different steps in which the optimum process parameters are achieved step by step. More in detail, the characterisation regarded: 40 “Single Scan Tracks” (SSTs), 24 “Single Layers” (SLs) and 3 “Cubes”. Indeed, the laser-related parameters like laser power (P), laser scan speed (SS) were selected according to the SSTs analysis, whereas the optimum hatching distance (Hd) was estimated according to the SLs. The best melt pool in terms of residual defect and geometrical regularity was chosen as the best-deposited melt pool, and accordingly, the process parameters associated with that melt pool were selected as the optimum parameters. Thereafter, the best Hd were considered according to the cross-section analysis of SLs in which the densest SLs with the most surface regularity revealed the optimal Hd. The outcomes show that P 600W, F 750 mm/min and Hd 0.3 mm, are the optimum DED process parameters to fabricate In718 parts. All in all, it can be concluded that this method of optimisation of process parameters is very promising to be implemented for optimisation of process parameters. It means, through the SSTs and SLs analyses, it would be possible to develop the process parameter of IN718 in a short and economical way without wasting time and material.