Localized corrosion: Passive film breakdown vs. Pit growth stability, Part VI: Pit dissolution kinetics of different alloys and a model for pitting and repassivation potentials

Abstract

The pitting resistance of SS316L, SS304, SS430, and pure Fe was studied in chloride-containing solution. Among these alloys, SS316L exhibits the highest pit initiation rate, but also the highest pitting potential. To explain this phenomenon, the maximum pit dissolution current density (idiss,max) of the alloys in saturated pit solution was measured using one-dimensional artificial pit electrodes. A lower idiss,max was found to correlate with higher pitting and repassivation potentials. Based on a recently proposed pitting framework, a conceptual model for pitting and repassivation potentials was established, based on which the effect of idiss,max on pitting resistance was discussed.