Directed energy deposition of Inconel 718 powder, cold and hot wire using a six-beam direct diode laser set-up

Abstract

This study puts forward a new set-up for directed energy deposition (DED) with a six-beam direct diode laser head. The set-up implements three process variants, i.e. cold and hot wire as well as powder DED. The differences in the material behavior of INCONEL® alloy 718 (IN718) during additive manufacturing using the three processes is analyzed with respect to dilution, penetration into the base material, as well as solidification microstructure, second phase particles and texture. The results confirm that all three processes allow for defect-free DED of IN718, and that the hot wire process facilitates high-deposition rates with low dilution, whereas the cold wire and powder processes yield different dilution and penetration. The differences of the three process variants motivate to apply these processes interchangeably on the same part depending on the desired local microstructures, textures and thus, properties. The fundamental correlation between the processing conditions of the novel set-up used and the material behavior during DED is discussed.