Corrosion behavior of different building planes of selective laser melting 316L stainless steel in 0.1 M HCl solution

Abstract

This study aimed to investigate the impact of building planes on the microstructure and corrosion behaviors of 316L stainless steel (SS) manufactured using selective laser melting (SLM) when subjected to a 0.1 M HCl solution. The investigation of material corrosion behavior involved the utilization of a wide array of surface characterization techniques, as well as various electrochemical measurements. The findings were subjected to a comparison with those obtained from a commercially rolled 316L SS (R 316L SS). The analysis revealed that the XZ and YZ planes displayed a distinctive fish scale melt pool structure, while the XY plane exhibited a columnar melt pool structure. The densities of the low-angle grain boundaries for different building planes were observed as YZ < XY < XZ. SLM 316L SS showing a broader passivation region and a higher breakdown potential compared to the commercially available R 316L SS, especially the XZ and XY planes. Meanwhile, the passive film on the XZ plane was the more compact and had a lower carrier density. The observed factors contributing to these findings could be attributed to the SLM sample containing an increased proportion of O2−/OH− and Cr2O3 in the passive film. This resulted in the formation of a thick and dense passive film, which is particularly evident on the XY and XZ planes. In addition, it was observed that the nucleation mechanism of the passive films remained unchanged following the SLM process.