Investigation into spatter behavior during selective laser melting of AISI 316L stainless steel powder

During the process of selective laser melting (SLM), spatter is generated with a negative impact on the performance of parts. Two types of spatter have been identified: droplet spatter, produced by the tearing of molten metal and powder spatter, formed when non-molten metallic powder particles around the molten pool are blown away, both arising as a result of the impact of metallic vapor. Single-track experiments were performed in order to observe spatter behaviors by using a high-speed camera. The influence of energy input on the spatter behavior was investigated by employing 316L stainless steel powder. Results indicate that energy input affects the size, scattering state and jetting height of spatter. Energy dispersive spectroscope analyses show that oxygen contents increase in spatter and SLM parts. X-ray diffraction analyses show that diffraction peaks of austenite and ferrite are considerably lower than those in 316L powder owing to the generation of iron oxides (Fe + 2Fe2 + 304). Comparative tensile testing results show that although both groups of specimens manufactured with fresh and contaminated powders are mainly characterized by ductile fracture, the tensile properties of the latter are far inferior to those of the former, owing to a greater quantity of inclusions. (C) 2015 Published by Elsevier Ltd.