Towards understanding of corrosion behaviors of Q235A pipeline steel subjected to simulated direct stray current interference in different electrolytes

Electrochemical corrosion induced by leakage current from the running rail in DC subway system, the stray current corrosion, is a threat that can't be ignored to the transportation pipeline near the metro line system. In view of the corrosion problem caused by stray current in the subway, this paper discusses the evaluation of simulated direct stray current interference on Q235A metal in two types of electrolytes (solution or soil environments), which is often employed as the pipeline steel. Instrumental methods employed in this study to conduct the electrochemical analysis includes Tafel polarization, electrochemical impedance spectroscopy, SEM scanning and EDS scanning to analyze the main electrochemical parameters for the assessment of corrosion resistance during the stray current corrosion process, which is carried out in electrolyte solution and soil environment, respectively. The EIS of electrolyte solution and soil environment (10 min-30 min) exhibits the same equivalent electronic circuit. The electrochemical results were also compared with two different experimental environments to exhibit a degree of similarity. Results also show that the charge transfer resistance Rct decreases and corrosion current density icorr increases in both electrolyte solution and soil environment, which indicates a reduction of corrosion resistance during the experimental period of this study.