A new insight into pitting initiation in selective laser melted 316L stainless steel

In this work, the effect of process parameters on pitting corrosion behavior and a detailed study on the pits formed in selective laser melted (SLM) 316L stainless steels in 3.5 wt% NaCl solution were studied. Cyclic po-larization (CP) was carried out on the surfaces along the build direction and the pits were characterized using a scanning electron microscope (SEM). Increasing the laser power improved the corrosion resistance while increasing the scan speed was detrimental to it. It was identified that small pits initiated at melt pool boundaries and through dissolution of cell interiors which then possibly coalesced to form bigger pits with a lacy cover formation. The work hence identifies new possible pit initiation sites in SLM SS316L while performing an in-depth analysis of the morphology to understand possible propagation mechanisms.

Automated summary

This study investigated the influence of process parameters on the pitting corrosion behavior of selective laser melted (SLM) 316L stainless steels in 3.5 wt% NaCl solution, and conducted a detailed analysis of the formed pits. Cyclic polarization tests were performed on the surfaces in the build direction, and the pits were characterized using scanning electron microscopy (SEM). The results showed that increasing the laser power improved corrosion resistance, while increasing the scan speed had a detrimental effect. Small pits were found to initiate at the melt pool boundaries and through dissolution of cell interiors, which possibly coalesced to form larger pits with a lacy cover formation.