Investigation of the laser-related parameters in Laser-Powder Bed Fusion of Inconel 718-Cu blends at fixed Volumetric Energy Density

The role of the fundamental laser parameters under the same Volumetric Energy Density (VED) in Laser-Powder Bed Fusion (L-PBF) of IN718 – Cu mixtures was investigated. Two IN718-Cu mixtures were obtained by pre-mixing IN718 and Cu powders, subsequently in-situ alloyed through L-PBF. For each blend, two values of the layer thickness were investigated, and for each level, a different value of the VED was chosen on the basis of previous works of the authors and kept constant. Five different combinations of laser power and scan speed were investigated, at fixed VED, for each layer thickness. Cubic samples with 10 mm side were printed under the selected conditions and density, microstructure, microhardness and thermal conductivity were investigated as the output quality indicators. The results showed that some properties of the samples change, even under the same energy input, suggesting that the actual thermal history experienced by the material does not depend only from the VED, but also from the combinations of laser power and scan speed. However, the results suggest also the feasibility and stability of the process within the investigated processing window. Finally, the resulting thermal conductivity was not significantly affected by the investigated process variables.