Enhanced microbiologically influenced corrosion resistance of 5Cr pipeline steel in the presence of Shewanella oneidensis MR-1

Novel Cr-alloyed pipeline steels were developed, demonstrating exceptional resistance to microbiologically influenced corrosion (MIC). Particularly, the 5.0Cr steel exhibited remarkable mechanical properties with ultimate tensile strength reaching 878 MPa (1.25-fold higher than conventional X80 steel) while maintaining the elongation. In Shewanella oneidensis MR-1-containing environments, 5.0Cr steel displayed significantly lower corrosion metrics: weight loss (0.8 ± 0.3 mg cm⁻² vs. 18.1 ± 2.9 mg cm⁻² for X80 steel) and maximum pit depth (4.9 μm vs. 18.8 μm). This enhanced MIC resistance stems from a Cr-rich oxide layer that simultaneously inhibits bacterial adhesion (50 % biofilm thickness reduction) and restricts extracellular electron transfer (EET), as evidenced by 14-fold higher charge transfer resistance (30 kΩ cm² vs. 2 kΩ cm² for X80 steel). The findings establish a dual-protection mechanism through interfacial engineering of pipeline steel surfaces.