Effects of stress, strain rate and sulfate-reducing bacteria on corrosion behavior of X70 pipeline steel

Purpose The purpose of this study is to find the multi-factor influence law of stress, strain rate and sulfate-reducing bacteria (SRB) on X70 pipeline steel in a simulated solution of sea mud and the order of influence of the three factors on X70 steel to develop a scientific basis for pipeline corrosion protection. Design/methodology/approach This paper studied the effects of stress, strain rate and SRB on the X70 pipeline steel corrosion behavior in simulated sea mud solution through orthogonal testing, electrochemical experiments and morphological observations. Findings The results of this study showed that stress proved to be the most relevant element for corrosion behavior, followed by SRB and strain rate. At high stresses (301 MPa and 576 MPa), stress dominated the corrosion behavior of X70 pipeline steel. However, at low stress (82 MPa), SRB played the most important role. Originality/value Subsea pipelines are in a very complex environmental regime that includes stress, strain rates and SRB, which often cause pipeline pitting and perforation. However, most scholars have only looked into the influence of single factors on metal corrosion. So, the single-factor experimental results of previous studies could hardly be applied to actual working conditions. There is an urgent need to understand the multi-factor influence law of stress, strain and SRB acting together on the pipeline corrosion behavior, especially to determine the dominant factor.