The effects of sulfate reducing bacteria on corrosion of carbon steel Q235 under simulated disbonded coating by using electrochemical impedance spectroscopy

The effect of sulfate reducing bacteria (SRB) on the corrosion of the carbon steel Q235 has been investigated in the crevice under the simulated disbonded coating in the soil-extract solutions (SES). The results of electrochemical impedance spectroscopy (EIS) show that the corrosion rate is inhibited in the SES with SRB during the stationary phase of SRB, but enhanced during the death phase. The comparison of the polarization (Rp) and the charge transfer resistances (Rt) has indicated that the biofilm seriously influences the reactive procedure of metal/solution interface. SRB is found in the pits on the surface of the steel.

Research highlights
► Effect of SRB on corrosion of carbon steel was investigated under disbonded coating.
► Protective ability of biofilm was analyzed by comparison of Rp and Rt.
► Sulfate reducing bacteria influenced corrosion was investigated by EIS.
► Corrosion was enhanced during death phase, but inhibited during stationary phase.
► Sulfate reducing bacteria preferred living in pits.