Influence of process parameters on the final 316L stainless steel properties manufactured by selective laser melting (SLM)

International audienceIn the framework of the fabrication of 316L stainless steel (SS) components by laser additive manufacturing (LAM), the influence of process parameters on microstructure and mechanical properties was studied. Test-specimens, such as cubes and cylindrical samples, were processed by Selective Laser Melting using SLM Solutions GmbH 280HL device. The raw 316L SS powder provided by SLM Solutions GmbH was firstly characterized. Physico-chemical properties such as composition, density, particles size distribution, powder flowability and morphology were investigated and compared with ten commercial 316L SS powders. The impact of process parameters on the microstructure of the manufactured specimens was studied, taking the physico-chemical properties of the powder into account. For this purpose, several observation techniques (SEM, EBSD measurements and TEM) were coupled in order to characterize the microstructure of the specimens' cross-sections. The results showed that the microstructure of the specimens is composed by columnar grains, oriented in the Z-direction and divided into fine intragranular cells. Nano-sized oxide precipitates were observed inside the austenitic matrix. For each specimen, texture, grain size and precipitates were examined with the aim of correlating the process parameters to the microstructure. The impact of process parameters on the mechanical behaviour of the manufactured specimens was finally studied. Mechanical tests were performed on machined samples yield strength, tensile strength, elongation, absorbed energy and hardness were measured and then compared. In this framework, last results regarding the influence of process parameters of AM on microstructure and mechanical properties of 316L SS will be presented and new insight for an optimization of these parameters will be given