采用室内埋片法、电化学阻抗谱(EIS)和扫描电镜(SEM)等方法研究了X80钢在西气东输二线沿线典型土壤环境中的腐蚀行为。结果表明, 60天测试期内, X80钢在三种土壤介质中的阻抗谱都呈现为具有两个时间常数的双容抗弧特征:在玉门和伊川两种碱性土壤中的腐蚀速率随时间呈逐渐降低趋势; 在樟树酸性土壤中的腐蚀速率呈逐渐增大趋势。三种情况下腐蚀形态都为点蚀; 低含水量土壤介质中, 钢表面因电解质液相非连续分布导致微观浓差腐蚀电池的形成是促进点蚀发生的主要原因。

The corrosion behaviors of X80 steel in typical soil environments along the Second West-East Gas Pipeline were investigated using the methods of indoor testing of buryed specimens, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The results show that all the impedance spectra present a characteristic of two capacitance loops with two time constants of the X80 steel exposed to three types of soil for 60 d and the corrosion rate decreased with the time of X80 steel exposed to alkaline soil of Yumen and Yichuan, however, the corrosion rate of X80 steel in acid soil of Zhangshu showed the reverse trend. The corrosion mode is pitting corrosion for X80 steel exposed to three types of soil for 60 d. In the soil environment with relative low moisture, the reason for pitting corrosion is the formation of concentration cell on the X80 steel surface caused by the discontinuous distribution of the liquid phase electrolyte.