Effect of argon and nitrogen atmospheres on the properties of stainless steel 316 L parts produced by laser-powder bed fusion

Abstract

The role of the inert gas during laser powder bed fusion (L-PBF) is to remove the process by-products and the air that is initially present in the process chamber. On this purpose, different gas supply options are available. The effect of the process gas and its purity, using argon and nitrogen, on the properties of the 316 L stainless steel produced by L-PBF was studied. The results obtained showed that utilization of argon and nitrogen result in residual oxygen levels that vary over the course of the process sequence in the process chamber. It can be concluded that 316 L stainless steel is a robust alloy to process by L-PBF. A limited effect of the residual oxygen or the gas type (argon or nitrogen) on the tensile properties of the 316 L stainless steel parts was registered. The oxygen and nitrogen pick-up within the produced parts are limited. However, when processing 316 L stainless steel with lower purity gas supply such as a nitrogen generator, risks related to powder degradation arise. Out of the available gas options, the findings highlighted that processing with high purity argon ensures limited powder degradation and high toughness of the produced parts.