Bacillus widely exists in wet natural environment such as soil, water and air, and is often studied as one of representative microorganisms for microbiologically influenced corrosion(MIC) research. In this paper, the growth curve of Bacillus subtilis isolated from marine environment was determined by turbidimetry and its effect on corrosion behavior of 10MnNiCrCu steel was studied by open circuit potential, AC impedance, polarization curve and scanning electron microscopy(SEM). The results showed that with the change of the growth curve of Bacillus subtilis(BS), the open circuit potential(E ocp ) shifted positively and then negatively, and the charge transfer resistance shown by AC impedance was much lower than that of the sterile system, increasing first and then decreasing. The polarization curves showed that the corrosion current density in BS medium was obviously higher than that in sterile system. The corrosion morphology observation showed that although a biofilm by BS developed on the steel surface, the localized corrosion of 10MnNiCrCu steel was aggravated due to the acidness of the metabolite itself and the biofilm with access for electrolyte ions.

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Corrosion is a common problem of storage tanks, and different storage media and impurities have different effects on the corrosion behavior of steel used for tanks. In this paper, electrochemical impedance spectroscopy (EIS) and polarization curves were used to study the corrosion behavior of 16Mn steel in 3.5% sodium chloride solution after immersion in heavy oil, diesel oil and gasoline, considering the influence of the main impurities, S 2À , on the corrosion process. The results showed that the selfcorrosion current density of 16Mn steel in the solution after the immersion in gasoline was higher than that in heavy oil and diesel oil, due to the higher dissolved oxygen concentration promoting the cathodic reaction. The comparison of blank sample in 3.5% sodium chloride solution and the immersed samples showed that the corrosion rate of the 16Mn steel decreased in the presence of an oil film on the surface of the steel. With the increase of S 2À concentration in the oil, the corrosion rate of 16Mn steel tended to be stable after it gradually increased. This was mainly related to the composition of FeS and FeS 1Àx in the sulfide film formed on the surface of the steel as well as the change of the lattice structure.

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