不同钢材在储罐沉积水中的电化学腐蚀行为

目前,鲜有多种钢材在储罐沉积水中腐蚀机制的研究报道。采用电化学阻抗谱(EIS)和动电位极化曲线测试技术研究碳钢Q235,管线钢X65、X80,不锈钢316L等4种钢材在原油储罐沉积水中的电化学腐蚀行为,并结合扫描电镜(SEM)、电子能谱(EDS)和X射线衍射谱(XRD)对钢材腐蚀形貌和腐蚀产物成分进行分析。结果表明:Q235钢、X65钢和X80钢浸泡24 d后表面生成疏松腐蚀产物,316L钢表面没有明显腐蚀现象发生;Q235(3.462μA/cm~2)、X65钢(4.122μA/cm~2)和X80钢(5.848μA/cm~2)在原油沉积水中极化曲线自腐蚀电流密度远大于316L(0.118μA/cm~2),316L钢极化曲线有明显的钝化区;随着浸泡时间延长,Q235钢、X65钢、X80钢的EIS谱阻抗模值缓慢增加,随后阻抗模值降低,而316L钢的阻抗模值没有明显变化。

Electrochemical Corrosion Behavior of Different Steels in Sediment Water of Storage Tanks

Electrochemical corrosion behaviors of Q235,X65,X80 and 316L steels in oil tank sediment water were studied using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves.By use of scanning electron microscope (SEM),electron dispersive spectrometer (EDS) and X-ray diffractometer (XRD),the morphologies of steel and corrosion products were analyzed.Results showed that some loose corrosion products were generated on the surface of Q235,X65 and X80 steels after immersion for 24 days.However,little corrosion was occurred on the surface of 316L.Polarization curves indicated that corrosion current densities of Q235 steel (3.462 pA/cm2),X65 steel (4.122 μA/cm2) and X80 steel (5.848 μA/cm2) were much higher than that of 316L steel (0.118 μA/cm2) in sediment water,and passive zone could be observed obviously on the polarization curves of 316L steel.Moreover,the electrochemical impedance spectroscopy presented that impedance modulus of Q235,X65 and X80 steels increased slowly with immersion time,and then decreased.However,there was no significant change in the impedance modulus of 316L steel.