Electrochemical insight into corrosion degradation of autoclaved Type 304 stainless steel in NaCl solution

Abstract

: This study investigates the effect of autoclave process on the corrosion behavior of Type 304 stainless steel in 100 mM NaCl via potentiodynamic anodic polarization. The autoclave process produced no significant changes in the surface morphology of either the steel-matrix or S-containing inclusions form optical and SEM observation with corresponding EDS maps. Electrochemical measurements conducted in 100 mM NaCl showed that, compared to as-polished stainless steel, autoclaved stainless steel has a lower passive current density by approximately one order of magnitude and reduced pitting potential by approximately 200 mV, indicating increased susceptibility to pitting corrosion. XPS analysis revealed that [Fe]/[Cr] ratio in oxide film on stainless steel coupon became drastically lower due to the autoclaved process. This difference in passive current densities is attributed to Cr-enrichment in the oxide film owing to the autoclave process. Pretreatment, which mainly included electrochemical techniques and smooth polishing to promote sulfur removal from the inclusions, improved the pitting corrosion resistance of the autoclaved stainless steel nevertheless there was a little difference of passive current densities, thus it was assumed that the inclusions affected to the lower pitting corrosion resistance of autoclaved stainless steel from this research.

The authors' abstract, as published at the source. Journal of Materials Research and Technology, 2026 · DOI ↗