Biologically competitive effect of Desulfovibrio desulfurican and Pseudomonas stutzeri on corrosion of X80 pipeline steel in the Shenyang soil solution.

In this paper, we have investigated the corrosion mechanism of X80 carbon steel in the presence of nitrate reducing bacteria (NRB), sulfate reducing bacteria (SRB) or both in the Shenyang soil solution. The results show that both SRB and NRB increase the corrosion rate of steel specimens and cause pitting corrosion of steel. Electrochemical tests and weight-loss data show that the addition of NRB in the SRB-containing environment leads to the reduction of corrosion. The thermodynamic analyses confirm the competitive advantage of NRB for the nutrients (organic carbon sources and irons) and the chemical oxidation of ferrous sulfide by nitrite, which results in a mitigation in the microbiologically influence corrosion (MIC) of SRB.

Synergistic effect of alternating current and sulfate-reducing bacteria on corrosion behavior of X80 steel in coastal saline soil.

With the development of electrified railways and high-voltage transmission lines, it is often inevitable that buried metal structures are subjected to interference from the alternating current (AC) induced by the neighboring power facilities. Commonly found in soil, sulfate-reducing bacteria (SRB) have the capability to accelerate metal corrosion. In this paper, with electrochemical methods, surface analysis techniques, and weight-loss test, the influence of AC and SRB on the X80 steel corrosion behavior was explored in coastal saline soil. The results revealed that the 100 A m-2 AC inhibited the growth of the sessile and planktonic SRB cell. Under the action of 100 A m-2 AC, the metabolic activity of viable bacteria was enhanced, and the process of extracellular electron transfer was accelerated. When both AC and SRB were introduced, the maximum pit depth (76.2 µm) increased significantly to be 15 times higher than in the control condition (4.9 µm). Both SRB and AC played a role in enhancing corrosion. The corrosion rate of the AC-influenced specimen was far higher than that of the SRB-influenced specimen, while SRB and AC produced a synergistic effect on the enhanced corrosion of the specimen.