Electrochemical Corrosion Behavior of X52 Steel in Simulated Jingxi First Line Soil Environment

Abstract

For analyzing the corrosion mechanism of X52 pipeline steel in the soil enviroment of western China, based on the real soil environment in Ansai area, the potentiodynamic polarization technique, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) were used to reveal the influence law of soil water content and ion concentration on the corrosion process of X52 steel. Results showed that the charge-transfer resistance of X52 steel in 20% water content soil medium was far greater than that in high water content soil medium. The corrosion rate increased firstly and then decreased with the increase of soil water content. In addition, few corrosion pits were found on the surface of X52 steel in the soil medium with 20% water content. With the increase of water content, the number of corrosion pits increased greatly, and the bottom of corrosion product particles showed ulcerative corrosion morphology. Moreover, the anion concentration in NS4 soil simulation solution was higher than that of Ansai soil simulation solution, resulting in worse corrosion resistance of X52 steel in NS4 simulation solution. EIS results showed that increasing the concentration of anion reduced the solution resistance and charge transfer resistance, which promoted the transition of the electrode reaction from activation-controlled reaction to the concentration diffusion-controlled reaction.

Keywords

• x52 pipeline steel|soil corrosion|electrochemical corrosion|water content|ion concentration