Abstract: Corrosion of long-distance water pipelines not only affects normal operation of the project but also poses a direct threat to structural safety. Taking a certain water pipeline material as the research subject, specimens with different theoretical corrosion rates were prepared by the electrochemically accelerated corrosion method. The electrochemical behaviors of specimens in freshwater and 3% NaCl solution were comparatively analyzed by open circuit potential (OCP), potentiodynamic polarization (PDP) curve, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). The research results indicate that the relationship between corrosion current density and corrosion degree in freshwater environment is nonlinear. In the NaCl environment, the strong erosive effect of Cl- ions weakens the protective capacity of the corrosion products, leading to an approximately linear variation between both the total impedance and the corrosion current density changing with the corrosion degree. At the same corrosion rate, the corrosion rate of the steel sheet specimen in the saline solution is significantly higher than that in freshwater. SEM observation further confirms that the microstructural changes of corrosion products correspond well with electrochemical characteristics such as corrosion current density and total impedance value.

Key words: corrosion and protection engineering; steel pipeline corrosion; electrochemically accelerated corrosion; electrochemical impedance spectroscopy (EIS); corrosion behavior; Cl- erosion

摘要： 长距离输水管道腐蚀不仅影响工程正常运行，更直接威胁结构安全。以某输水管材为研究对象，采用电加速腐蚀方法制备不同理论腐蚀率的试件，并通过开路电位(OCP)、动电位极化曲线(PDP)、电化学阻抗谱(EIS)及扫描电镜(SEM)，对比分析了试件在淡水与3%NaCl溶液中的电化学行为。研究结果表明：淡水环境中腐蚀电流密度与腐蚀程度呈非线性关系，在NaCl环境中，Cl-的强侵蚀性削弱了腐蚀产物的保护作用，使总阻抗与腐蚀电流密度随腐蚀程度呈近似线性变化；在相同腐蚀率下，钢片试件在盐水中的腐蚀速率明显高于淡水；SEM观察进一步表明：腐蚀产物的微观结构变化与腐蚀电流密度、总阻抗值等电化学特征具有良好一致性。

关键词: 腐蚀与防护工程；钢质管道腐蚀；电加速腐蚀；电化学阻抗谱；腐蚀行为；Cl-侵蚀