交变载荷频率对MS X65管线钢在H2S介质中腐蚀电化学行为影响

采用动电位极化、线性极化、电化学阻抗等电化学测试技术,研究了不同应力比(R)下MS X65管线钢在含H2S介质中的腐蚀电化学行为随交变载荷频率变化的规律。结果表明:自腐蚀电流密度Icorr、电荷转移电阻Rct、线性极化电阻Rp等腐蚀电化学动力学参数均随着交变载荷频率的增加,先上升或下降,后趋于稳定,存在一个临界交变频率;且由R=0.4时的0.25 Hz增大到R=0.85时的1 Hz,这与不同应力比和交变频率对电极表面电化学活性反应位点和腐蚀介质中阴极反应物扩散速率的交互影响有关。

Effect of Cyclic Stress Frequency on Corrosion Electrochemical Behavior of MS X65 Pipeline Steel in HS Containing Medium

The electrochemical behavior of MS X65 pipeline steel in H2 S containing medium by different stress ratios(R) was investigated via electrochemical test techniques such as dynamic potential polarization,linear polarization,and electrochemical impedance.The results indicated that electrochemical kinetic parameters such as free-corrosion current density Icorr,electron transfer resistance Rct,and linear polarization resistance Rp all increase or decrease first with the increase of the cyclic stress frequency,and then stabilized by a critical cyclic stress frequency.The critical frequency increased from0.25 Hz for R=0.4 to 1 Hz for R=0.85, which would be related to the interactive influence of different stress ratios and cyclic stress frequencies on the electrochemically active reaction sites on the electrode surface and the diffusion rate of cathode reactants.