Mechanistic investigations of corrosion and localized corrosion of X80 steel in seawater comprising sulfate-reducing bacteria under continuous carbon starvation

Abstract

Sulfate-reducing bacteria (SRB) corrosion is one of the main reasons leading to the service failure of engineering materials in the marine environment. An understanding of SRB corrosion especially under continuous organic carbon starvation is required. In this work, SRB corrosion of X80 pipeline steel under continuous organic carbon starvation was studied using mass loss, electrochemical measurements, and surface analysis. The effects of initial SRB concentrations on steel corrosion were also studied and discussed. The results indicated that more than 99% population of SRB die after 21 d of testing in various conditions, but there are still amounts of SRB survivors. SRB survivors with continued organic carbon starvation have a better adaptive ability and accelerated steel corrosion. Both the uniform and localized corrosion rates are also proportional to the initial SRB concentration as well as SRB survivors. The localized corrosion rate and density of corrosion pits of specimen corresponding to an initial SRB count of 10⁸ cells/mL reach bigger values of (0.693 ± 0.114) mm/y and (1.94 ± 0.39)×10⁴ pits/cm², respectively, which are induced by the combination of the sessile and planktonic SRB.