Passivity Breakdown of Mild Steel in Sea Water in the Presence of Sulfate Reducing Bacteria

The electrochemical behavior of 1020 SAE carbon steel in sea water or 0.5M sodium chloride solutions is studied in the presence of sulfate reducing bacteria (isolated from ship fuel storage tanks) and different concentrations of sulfides. Potentiostatic polarization techniques are used to follow the evolution of corrosion and pitting potentials in these media. A change of pitting potential of 1020 SAE steel towards more active values was observed for low concentration of sulfides or in the presence of sulfate reducers suggesting that the role of the latter in the corrosion process might be indirect. The influence of oxygen level on the metal attack is also analyzed.