Study on the corrosion mechanism of X65 steel by manganese-oxidizing bacteria in marine environment

The impact of MOB isolated from marine sediments on the corrosion process of X65 steel and the underlying corrosion mechanism are investigated in this work. Results indicate that MOB produces a pH-neutral environment that contributes to Mn 2 + biological oxidation . The manganese oxide produced by MOB can be employed as effective substitute cathode, augmenting both the surface film instability and the electrochemical reactivity of metal. MOB interacts with the steel matrix by rapidly oxidizing the dissolved Fe 2+ of X65 steel to iron oxide when Mn 2+ concentrations are inadequate. There may be multiple factors that contribute to the corrosion of X65 steel. • Manganese oxides produced by MOB could be the main factor inducing corrosion in carbon steel. • Generation of Fe 2+ further exacerbates the MIC process in the absence of Mn 2+ . • Complete schematic corrosion process diagram is presented to explain the mechanism of MOB occurrence in MIC.