The Influence of Powder Size and Packing Density on the Temperature Distribution in Selective Laser Melting

Metal powder properties in Selective Laser Melting (SLM) is among one of the most important factors when implementing new alloy developments for the equipment. In fact, not all commercially available metal powder alloys are ready to be implemented without a comprehensive set of tests. Besides the powder properties, we have a large number of building and environmental parameters that demands extensively research prior implementation. Although selected alloys are commercially available and documented to be used in SLM, including Ti6Al4V, SS316L and In718, the majority of it still not ready to be utilized in this system. The focus of this study is to use a thermal model in order to predict the thermal distribution of the process regarding different aspects of the powder properties, especially the thermal conductivity, when different powder packing densities and diameters are used. A Stainless Steel 304L will be utilized in this work, since it is not yet available to be commercially used. The main goal is to show the capabilities of the Finite Element Method in the pre-definition of optimal parameters for the process using a new alloy development. Our findings can be used as a pre-evaluation guideline when printing SS304L, since the comparison with similar experimental work in the field showed significant resemblance and outcomes. The temperature distributions show that the packing density has greater sensibility on the final temperature distributions, compared to the powder diameter variance. Two different power inputs are compiled and the temperature outcomes demonstrate that a power input of 100 Watts is recommended to use when printing SS304L, rather than 400 Watts that brings high temperature into the powder bed.