A study on bacteria-assisted cracking of X80 pipeline steel in soil environment

In the paper, bacteria-assisted cracking by sulphate-reducing bacteria (SRB) of X80 pipeline steel in a meadow soil solution was studied under different applied stresses by electrochemical impedance spectroscopy, linear polarisation resistance and scanning electron microscope. The obtained results indicated that the physiological activity of SRB and the applied stresses not only play individual roles in corrosion of the steel, but also had intense synergistic effects in promoting the corrosion process. In the SRB-inoculated soil solution, the number, average length and width of micro-cracks increase to a certain extent. Under the combined actions of SRB and plastic stress, localised corrosion may not only extend to steel matrix but also to lateral direction. The generation processes of bacteria-assisted cracking were discussed in the paper.