Electrochemical corrosion behaviors and mechanism of carbon steel in the presence of acid-producing bacterium Citrobacter farmeri in artificial seawater

Acid-producing bacteria, which can induce variation in pH, play a key role in microbiologically influenced corrosion (MIC). In this study, the corrosion behavior of Q235 carbon steel was investigated in the presence of acid-producing bacterium Citrobacter farmeri. During the initial stage of bacterial adhesion, formation of inhomogeneous biofilm of C. farmeri produced differential aeration cells, resulting in the formation of tiny crevices on the carbon steel. After 168 h incubation, a thick biofilm of C. farmeri formed on the carbon steel, which accelerated the corrosion process and produced an inner layer of Fe3O4. The results suggested that the corrosion behavior of carbon steel in the presence of C. farmeri was determined by the formation of thick biofilm and conductive Fe3O4 film.