Microbiologically influenced corrosion behavior of 10CrNi5MoV high-strength steel in marine environments.

10CrNi5MoV high-strength steel may suffer from microbiologically influenced corrosion (MIC) caused by sulfate-reducing bacteria (SRB), posing a severe threat to structural integrity and service safety. Herein, we report the application of immersion corrosion tests, electrochemical measurements, and X-ray photoelectron spectroscopy to investigate the MIC behavior of 10CrNi5MoV in simulated SRB-inoculated seawater. This class of medium-alloy steel is susceptible to MIC, with its corrosion rate reaching ∼0.03 mm y-1 after 21 days of immersion, which is nearly threefold of that under sterile conditions. Electrochemical measurements reveal that SRB notably elevate the corrosion current density and simultaneously reduce the charge transfer resistance, indicating greatly accelerated interfacial corrosion kinetics. Meanwhile, the corrosion morphology transformed from uniform corrosion to severe pitting corrosion, with the average pit depth reaching ∼20 μm after 21 days of immersion. This study supports that SRB-induced MIC follows the cathodic depolarization mechanism, and Ni enrichment in the inner rust layer may mitigate MIC. These findings provide theoretical and experimental references for MIC risk evaluation and management of this steel in marine environments.