Effects of copper on the localised corrosion and repassivation kinetics of Fe-20Cr- x Cu( x  = 0,1,2 wt%)

Abstract

This study investigates the influence of copper (Cu) content on the localised corrosion behaviour and repassivation kinetics of Fe-20Cr-xCu (x = 0, 1, 2 wt.%) stainless steels (SSs). The effects of Cu on film breakdown, re-passivation kinetics, and crack propagation in these alloys are systematically analyzed. Electrochemical noise analysis is employed to examine the film breakdown frequency of SSs, revealing a notable increase in current peaks with higher Cu content, indicative of enhanced film breakdown. Additionally, the rapid scratching electrode technique is utilised to assess the repassivation kinetics, where it is observed that the repassivation rate decreases with increasing Cu content, indicating that the recovery of passivation in Cu-containing SS is inhibited. Furthermore, simulation of crack growth at the crack tip via an occluded corrosion cell test highlights an accelerated anodic dissolution rate of the small anode with increasing Cu content, signifying Cu's role in promoting crack propagation in SSs.