Optimizing the design of the selective melt dispersion (SMD) process based on metallographic investigations of additively manufactured 316L steel samples

Abstract In this paper, an author-developed experimental setup will be used to investigate the novel additive process of selective melt dispersion (SMD), a directed energy deposition (DED) process. For this purpose, 316L samples and 316L powder were additively processed by laser treatment. The parameters laser power, pulse repetition rate and feed rate were varied throughout the experiments. The samples, i.e., the welds, produced in this way were then examined for the roughness parameters Ra and Rz, weld width, weld geometry (and also height) and their microstructure. It was found that there is a correlation between the energy input and the resulting width of the weld. In addition, low roughness values in the range of those achieved by investment casting were observed. The weld geometries (cross section) of randomly selected samples were not consistent and therefore, did not yield evaluable results. Upon closer inspection, it was found that in contrast to what had been assumed, no additive material build-up could be achieved with the experimental setup. After analyzing the overall system, it became evident that the positioning of the subsystems in the experimental setup needed to be modified to enable material build-up. The successful modification of the setup was then verified by experiment.