Effects of Sulphate-reducing Bacteria on Corrosion Behaviour of 2205 Duplex Stainless Steel

The effects of sulphate-reducing bacteria (SRB) on the 2205 duplex stainless steel in the sea water and oil industry environments were studied by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and microorganism analysis. The results showed that the detected SRB was the non-spore bacillus of about 0. 8 μm × (1.8 — 2.2) μm in size and the content of S was about 7.59% in the corrosion products. SRB contributed to the corrosion evolution which caused the corrosion failure of 2205 duplex stainless steel pipe in the liquid hydrocarbon cooler. During the corrosion process, the produced H2S could significantly influence the anodic process and finally accelerate the corrosion. SEM observation indicated that the distribution of SRB on the surface of 2205 duplex stainless steel was nonuniform. X-ray photoelectron spectroscopy analysis revealed that the surface film was composed of Cr2O3, MoO3, FeS, FeS2, Fe(OH)2 and FeO after immersing the sample in the SRB medium for 14 d.