Comparative study of the crevice corrosion resistance of UNS S30400 and UNS S31600 stainless steels in the context of Galvele's model

Abstract

Although stainless steels do not rust in unpolluted atmospheres they are prone to localized corrosion in the forms of pitting corrosion crevice corrosion and SCC when exposed to chloride-containing solutions or marine atmospheres. The crevice corrosion repassivation potential of austenitic UNS S30400 and UNS S31600 stainless steels was determined in a wide range of temperature. The repassivation potential of UNS S30400 decreased with increasing chloride concentrations and temperatures at 0°-60°C and it reached a constant value at 60°-90°C regardless of chloride concentration. The repassivation potential of UNS S31600 decreased with increasing chloride concentrations and temperatures in the entire tested temperature range. Crevice-corroded areas on UNS S30400 and UNS S31600 showed crystalline attack plus pitting corrosion.