X80管线钢在力电化学耦合作用下CO2腐蚀行为的研究

Study on CO2 Corrosion Behavior of X80 Pipeline Steels under the Coupling of Tensile Stress and Electrochemical Reaction

以典型的管线钢材料X80钢为对象,采用动电位极化和电化学阻抗谱技术,研究了在弹性拉伸应力(60%σys)和塑性拉伸应力(108%σys)状态下,不同CO2分压和Cl-质量分数对材料腐蚀的影响规律。结果表明:受拉伸应力作用的X80钢腐蚀速率随CO2分压的增大而增大,但并非单纯正相关关系;随Cl^-质量分数的增大,呈现先升高后降低的规律,当Cl^-质量分数为3.5%时,X80钢的腐蚀速率达到最大值。此外,塑性应力状态下X80钢的腐蚀速率明显高于弹性应力状态下的值,原因是塑性应力提高了金属表面的电化学反应活性。

Through taking X80 pipeline steel as the object of study,having potentiodynamic polarization(PDS)and electrochemical impedance spectroscopy(EIS)adopted to investigate corrosion behavior of stressed X80 pipeline steel(60%σys and 108%σys)under different CO2 partial pressures and Cl-concentrations was implemented to show that,with the increase of CO2 partial pressures,the corrosion rate of tensile-stressed X80 steel increases,but it’s not just a positive correlation;with the increase of Cl^- concentration,the corrosion rate of tensile-stressed X80 pipeline steel initially increases and then gradually decreases,and at the Cl^- concentration of 3.5%,the X80 pipeline steel’s corrosion rate has the maximum value.Furthermore,the corrosion rate of plastic-stressed X80 steel is higher than that of elastic-stressed X80 steel because plastic stress can improve activity of electrochemical reaction of metal surface.