Laser metal deposition with wire of Inconel 718 on pre-heated substrates

Laser metal deposition with wire (LMD-w) is an additive manufacturing technology with high deposition rates for large parts. During the LMD-w process, a metallic wire is fed into a laser-induced melt pool. A weld bead is created since the melt pool and the substrate move relative to each other. Several beads next and/or on top of each other create layers, coatings, or 3D elements. The process, however, generates high temperatures in a very short time resulting in high temperature gradients, leading to distortion, or cracking. This study investigates how lowering the temperature gradients with pre-heated substrates affects deposition results and how it influences microstructure, hardness and surface roughness using Inconel 718 material. By focusing on beads’ appearance and temperature of the melt pool, the resulting microstructure, porosity, and cracks were analyzed.