Effect of sulfate-reducing bacteria on crevice corrosion of 316L stainless steel

The growth characteristics of sulfate-reducing bacteria (SRB) in crevices and their influence on corrosion behavior were systematically investigated. The study revealed that SRB growth within crevices progresses through three distinct stages: exponential growth, stability, and decline. The crevice environment significantly impedes nutrient diffusion, creating a nutrient gradient that drives SRB to adapt by directly extracting electrons from the stainless steel matrix to sustain their metabolic activity. In this process, SRB themselves function as a bio-cathode, facilitating cathodic reactions and accelerating localized corrosion. As a result, the corrosion morphology is dominated by the preferential vertical propagation of pits. These findings highlight the critical role of SRB as a bio-cathode in promoting crevice corrosion.