Modulating biofilm distribution to control microbiologically influenced corrosion and mechanical degradation of X80 steel

Microbiologically influenced corrosion (MIC) associated with sulfate‑reducing bacteria (SRB) is a leading cause of pipeline failure in the oil and gas industry. Biofilm structure and distribution strongly influence MIC, but controllable modulation remains challenging. Here, we report a novel method to regulate biofilm distribution of Desulfovibrio vulgaris on X80 pipeline steel using epoxy resin and spherical glass beads to define three standardized areas (100, 390, 640 cm 2 ). Combined characterization, including cell counting, H 2 S and H 2 measurement, weight loss, electron microscopy, electrochemistry, and tensile testing, was applied to evaluate MIC behavior and mechanical degradation. Larger biofilm distribution reduced sessile cell density and biofilm thickness but enhanced biogenic H 2 S and H 2 release. MIC was dominated by the extracellular electron transfer (EET) mechanism throughout 7 days, with synergistic hydrogen embrittlement from biogenic gases. Increased distribution area significantly lowered corrosion rate, pit depth, weight loss, and mechanical property degradation. This work provides a robust biofilm modulation platform and clarifies the coupled EET‑MIC and hydrogen embrittlement mechanism, offering a new strategy for mitigating MIC‑induced degradation in pipeline engineering.