交流杂散电流对涂覆3PE涂层的X70钢腐蚀及涂层剥离行为影响规律研究

Effects of Stray AC on Corrosion of 3-layer Polyethylene Coated X70 Steel And Cathodic Delamination of Coating with Defects

基于电化学测试及金相显微镜等先进技术手段,研究了交流杂散电流对X70钢在3PE涂层缺陷处腐蚀及涂层剥离行为的影响。研究结果表明:随着电流密度的增大,X70钢遭受腐蚀的程度逐渐加剧。不同涂层缺陷面积的试样呈现出不同的电化学阻抗谱变化规律。小尺寸缺陷涂层试样的涂层阻抗与交流电流密度呈反比关系,大尺寸缺陷涂层试样的阻抗与交流电流密度呈正比关系。同等电流密度条件下,在小尺寸缺陷涂层试样上,缺陷处涂层剥离面积较大。涂层缺陷较小时,杂散电流导致的涂层剥离更加严重,对油气管道造成的危害更大,影响油气管道涂层缺陷和剥离检测结果和安全评估。

The effects of stray alternating current(AC)on the corrosion of coated X70pipelinesteel and the delamination of3PE coatings with defects were investigated using electrochemicalmeasurements and metallographic microscope techniques.The results showed that as an increasingAC density,the corrosion was more severe.With an increasing AC density,a different electrochemicalbehavior was observed at samples with two size of defects.The impedance of samples with small defectsdecreased,while that of samples with large defects increased.Under the same level of AC interference,the delamination area on samples with small defects was larger.On samples with small defects,ACinterference resulted in a more severe corrosion damage.Small defects in stray AC environment misledsecurity assessment.