Tuning Process Parameters to Control the Porosity of Parts Produced with Directed Energy Deposition

Laser powder directed energy deposition (LP-DED) is an exponentially growing additive manufacturing process. The process is mainly used for repairing/remanufacturing operations, for the production of large components, or for the production of components with tailored characteristics. Despite the many benefits in the adoption of the LP-DED process, the applications are nowadays still limited. The reasons lie partly in a limited knowledge of the relationship between process parameters and the properties achieved in the final product. Specifically, one of the critical factors influencing the mechanical properties is the porosity of the part. The purpose of the present work is to investigate the effect of the main process parameters, such as laser power, travel speed and powder feed rate, on the porosity of AISI 316L samples produced by the LP-DED process. Results showed that by tuning process parameters, it is possible to produce samples with a density up to 99.9%. In the range of process parameters investigated in this work, porosities are mainly reduced by increasing the laser power; moreover, at lower power values, the increase in powder feed rate significantly improves the part density.