X80管线钢在东南酸性土壤环境中的电化学腐蚀特征研究

Study on Electrochemical Corrosion Characteristics of X80 Pipeline Steel in Simulated Medium of Southeastern Acid Soil

采用电化学测试、扫描电镜观察、表面能谱分析及X射线衍射等方法,研究了原始态与退火处理态的X80管线钢在东南酸性土壤模拟溶液中的电化学腐蚀特征与机理,分析了热处理工艺和腐蚀时间等因素对X80钢极化曲线的影响。结果表明,退火态X80钢耐蚀性低于原始态,这主要与X80钢组织因热处理发生改变有关;随着浸泡时间的延长,原始态与退火态的X80钢在东南酸性土壤模拟溶液中腐蚀趋势均减小,而腐蚀速率先增大后减小;其阴极过程受析氢腐蚀和吸氧腐蚀联合控制;腐蚀产生的锈层主要由FeOOH(表层)和Fe3O4(内层)组成,而腐蚀产物膜的完整性和致密性影响了X80钢表面的腐蚀过程,使管线钢表面的腐蚀破坏程度增加。研究还发现,氯离子含量是影响腐蚀的主导因素。

The corrosion behavior of X80 pipeline steel in simulated solution of southeastern acid soil was investigated using electrochemical measurement, scanning electron microscopy （SEM）, energy dispersive spectrum （EDS） and X-ray diffraction （XRD）. The effects of heat treatment process and corrosion time on the polarization curves were analyzed. The results show that the change of microstructure by annealing treatment accelerates the corrosion of X80 steel, which is worse than that of original state, the corrosion rate increases first and then reduces. The cathodic reactions are dominated by oxygen reduction and hydrogen evolution reaction. The corrosion products consist of FeOOH （surface layer） and Fe3O4 （inner layer）. The integrality and compactness of corrosion product films influence the corrosion process, and increase the corrosion damage of X80 steel surface. The content of C1- dominates the corrosion severity.