Characteristics of the initiation and propagation of crevice corrosion in stainless steel

The crevice corrosion behavior of 316 L stainless steel in NaCl solution was investigated under constant potential conditions. Once crevice corrosion initiates at a given site, it propagates from the initiation site toward the crevice mouth. Upon reaching the crevice mouth, corrosion spreads circumferentially along the crevice mouth. This behavior occurs because the potential decreases rapidly before reaching the corrosion initiation site due to the IR drop, resulting in higher potential at the crevice mouth than at the bottom. Additionally, the distribution of solution concentration within the crevice does not differ significantly regardless of the location of the corrosion initiation site. This potential gradient leads to an increase in the corrosion current within the crevice, which accelerates crevice corrosion. From an equipment maintenance perspective, this study suggests that crevice corrosion predominantly propagates in the direction of crevice depth near the crevice mouth. When crevice corrosion is detected, even if the crevice length is significant, propagation in the direction of crevice depth is limited near the bottom. Therefore, priority should be given to inspecting and maintaining the area near the crevice mouth.