The influence of particle size on the long‐term electrochemical corrosion behavior of pipeline steel in a corrosive soil environment

In this work, the effect of particle size (0.25, 1.0, 1.5 mm) on the electrochemical corrosion behavior of X70 pipeline steel in a 1.5 wt% NaCl sandy soil corrosion system was investigated by electrochemical techniques including linear polarization resistance, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) in combination with SEM‐EDS surface analysis, and X‐ray diffraction characterization. The laboratory experiments indicated that the corrosion rate of X70 pipeline steel increased with decreasing soil particle size to less than 1.0 mm and was mainly determined by a cathodic reaction. Whereas when the soil particle size increased beyond 1.0 mm, the corrosion rate of X70 steel decreased as the soil particle size decreased and the dominant reaction was metal dissolution in the bulk zone, and the corrosion rate was determined by anodic reaction. Additionally, the results of analysis of the metal surface morphologies agreed with the electrochemical measurements results. Corrosion of X70 pipe steel is affected by particle‐sizes in a corrosive soil environment.