通过对X80管线钢进行固体渗碳模拟焊接接头区域的Fe3C和退化珠光体组织,采用扫描Kelvin探针(SKP)、扫描振动参比电极(SVP)和局部电化学交流阻抗谱(LEIS)结合浸泡实验分析了Fe3C和珠光体对铁素体钢表面电化学性能以及在鹰潭土壤模拟溶液中的局部腐蚀发生规律的影响. 结果表明, 退化珠光体组织在空气(湿度为40\%, 温度为22 ℃)中的腐蚀电位低于贝氏体铁素体, 并且随着Fe3C含量的增加, 腐蚀电位降低; 渗碳试样在鹰潭模拟溶液中发生局部腐蚀,中心铁素体区为整个材料电偶腐蚀的阴极, 退化珠光体和退化珠光体/贝氏体铁素体区为阳极, 随着Fe3C含量的增加, 阳极溶解电流密度增大；模拟溶液各离子含量成倍增加后, 退化珠光体的阳极电流密度升高, 电化学交流阻抗值降低, 局部腐蚀效应增大.
The microstructure of X80 pipeline steel welding joint, consisted of Fe3C and degenerated pearlite, was simulated by carburizing treatment. The effects of Fe3C and pearlite on the electrochemical properties of bainitic ferrite steel and localized corrosion occurrence regularity in Yingtan soil simulation solution were investigated by scanning Kelvin probe (SKP), scanning vibrating probe (SVP) and local electrochemical impedance spectroscopy (LEIS), combined with immersion test. It is demonstrated that the corrosion potential of degenerated pearlite is lower than bainitic ferrite, and decreases with increasing Fe3C content. Localized corrosion occurs on the surface of the carburized sample in Yingtan soil simulation solution. The anodic oxidation process is observed to be initiated on the carburized degenerated pearlite, whereas the cathodic reaction involving dissolved H+ is on bainitic ferrite, and the anodic current density increases with increasing Fe3C concentration. As the ion contents of the soil simulation solution doubled, the anodic dissolution of degenerated pearlite increases, and the local impedance of the electrode decreases.
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