Microbiological corrosion of pipeline steel under yield stress in soil environment

• The yield stress and activities of SRB have synergistic effects on corrosion.
• SRB increase the width and length of micro-cracks with the help of yield stress.
• The tips of cracks trends to become smooth and flowing in the presence of SRB.
• SRB induced secondary pitting is initiated from the bottom of wide shallow pits.

Microbiological corrosion induced by sulfate-reducing bacteria (SRB) of X80 steel under yield stress was studied by EIS, SEM and XPS in a soil environment. The activities of SRB stimulate the generation of secondary pitting on the bottom of wide shallow pits and near micro-crack tips on the specimen with yield stress. Yield stress enhances the stress concentration, promoting the growth of micro-cracks in the inoculated environment. With the assistance of synergistic effect of SRB and yield stress, corrosion of the steel can process easily during the repetition of SRB induced secondary pitting, anodic dissolution and formation of the passive layer.

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