Inter-melt pool corrosion and repassivation of SS316L stainless steel processed by laser powder bed fusion

Pit stability and repassivation of SS316L stainless steel processed by laser powder bed fusion (L-PBF) were examined through polarization experiments on one-dimensional (1D) pit electrodes. The L-PBF-SS316L pit was observed to grow along the Cr and Mo-depleted melt pool boundaries (MPBs) well below the nominal repassivation potential (Erp) due to partial repassivation. MPBs promote pit stability in L-PBF-SS316L by offering an easy path for pit propagation. The implications on the reliability of the nominal Erp of L-PBF-SS316L as a metric for localized corrosion resistance are discussed.