Effects of cathodic protection potential on microbiologically induced corrosion behavior of X70 steel in a near-neutral pH solution

Abstract Sulfate reducing bacteria (SRB) are considered as one of the main causes for failures buried metal pipes. Although many researchers reported that more negative cathodic protection potential was required in environments containing SRB, SRB would increase concentration hydrogen adsorbed on steel surface and thus lead to embrittlement. In study, optimum (CP) potentials X70 bacterial sterile media were evaluated with electrochemical impedance spectroscopy. The morphology composition corrosion products characterized by a scanning electron microscope (SEM), an energy dispersion x-ray spectrometer (EDS), photoelectron (XPS). NS4 medium pits serious than medium. FeOOH Fe 2 O 3 medium, whereas its FeS. When CP −775 mV, growth promoted optimal effect achieved Pits still observed under biofilm corresponding mechanism extracellular transfer (EET). −875 realized solution. However, CO hydrolysis metabolism resulted hydrogen-induced pits. −1025 inhibited severe evolution occurred media. pipeline may when H + high.