塑性变形条件下16MnR钢的CO_2腐蚀电化学行为

Electrochemical Corrosion Behavior of 16MnR Steel with Plastic Strain in CO_2 Environment

油气田管材常常在各种应力和变形状态下服役,为了研究应力和变形对钢CO2腐蚀电化学行为的影响,利用电化学技术分别测量了16MnR钢在不同弯曲塑性变形状态下的CO2腐蚀电化学阻抗谱、线性极化电阻和自然腐蚀电位。结果表明:随着应变的增大,自然腐蚀电位负移,线性极化电阻逐渐减小,腐蚀速率增大。在拉伸和压缩塑性变形状态下16MnR钢CO2腐蚀的电化学阻抗谱均由高频容抗弧和低频感抗弧组成。随着应变的增大,容抗弧和感抗弧逐渐收缩,反应的总阻抗减小。冷加工变形增大了16MnR钢的电化学活性,使阳极溶解加快,腐蚀速率增大。

Oil country tubular goods often service under stress and strain conditions. In order to investigate the effect of stress and strain on CO2 corrosion behavior of 16MnR steel, electrochemical measurement techniques were employed to determine the electrochemical impedance spectra（EIS）, linear polarization resistance（LPR） and corrosion potential（Ecorr） after different plastic deformation. The results show that the corrosion potential shifts in negative direction, linear polarization resistance decreases, ahd corrosion rate increases with increasing strain. The Nyquist plots of EIS spectra under tensile and compressive strain exhibit two semicircles： a first capacitance loop at high frequency and a second inductance loop at low frequency. The distance along the real axis where the two loops appears decreases with increasing strain, which indicates the total impedance resistance decreases with strain. Cold working deformation improves the electrochemical activity of 16MnR steel, which increases the anodic dissolution and corrosion rate.