An experimental characterization of powder/substrate interaction during direct metal deposition for additive manufacturing

The physical behavior of metal powders during laser-based additive manufacturing processes has been investigated. In particular, an experimental campaign of direct metal deposition has been carried out to evaluate the effect of the laser power and spot size on the powder/substrate interaction and on the surface morphology of the final piece. A fast-camera has been used to evaluate the interaction phenomena during the printing process, while confocal microscopy has been carried out to measure the surface morphology of the samples. Results highlighted that increasing the laser power and laser spot size, the particle impact velocity is about constant, while the powder/laser/substrate interaction zone increases. As a consequence, the mean thickness increases, as confirmed by surface characterization.