Selective laser melting processing of 316L stainless steel: effect of microstructural differences along building direction on corrosion behavior

SLM-processed 316L stainless steel exhibits promoted mechanical and corrosion performances, compared with the conventionally manufactured counterparts, and has been successfully applied in many fields. The anisotropic microstructure of SLM-processed materials, caused by the layer-wise fashion of SLM processing, not only results in the anisotropy of mechanical properties but also leads to the anisotropic corrosion behavior. In this study, the influence of microstructural differences of SLM-processed 316L stainless steel along the building direction on corrosion behavior was investigated. Firstly, the influence of laser scan speed on the microstructure, hardness, and corrosion behavior of SLM-processed 316L stainless steel samples was evaluated. Then, the sample with the highest relative density and the best hardness and corrosion resistance was selected to further investigate the influence of microstructural differences along the building direction on the corrosion behavior. Results showed that the corrosion resistance improved with the increase of distance from bottom plane along the building direction. Microstructure and phase analysis revealed that the microstructural differences in crystallographic orientation and grain size along the building direction of SLM-processed 316L stainless steel led to the different corrosion behavior.