X80钢焊接接头在不同pH值土壤中的腐蚀电化学特征  

Electrochemical Corrosion Characteristics of X80 Steel Welded Joints in Soil with Different pH Values

作　　者：谢飞[1] 王丹[1] 吴明[1] 王宸 任胜华 

机构地区：[1]辽宁石油化工大学石油天然气工程学院,辽宁抚顺113001 [2]辽河油田金马油田开发公司,辽宁盘锦124000 [3]中石化天津分公司,天津300270

出　　处：《材料保护》2015年第11期31-33,47,共4页Materials Protection

基　　金：国家自然科学基金(50771053);辽宁省教育厅科学研究基金资助项目(L2014156)资助

摘　　要：高强度管线钢在油气管道长距离输送应用中埋地管道焊接接头处的腐蚀现象越发明显。为了探究高强度钢焊接接头在不同pH值土壤中的腐蚀行为,利用动电位极化及交流阻抗技术对X80钢焊接接头在库尔勒土壤模拟溶液中的电化学特征进行测定,并结合金相显微镜对其腐蚀形貌进行了观察。结果表明:随着土壤pH值的增大,X80钢焊接接头的腐蚀速率呈现逐渐减小的趋势;当模拟溶液为弱酸性环境时,腐蚀产物膜遭到破坏,加剧了Cl_-等腐蚀性离子对金属的腐蚀,试样电极表面腐蚀坑明显;当溶液为碱性环境时,腐蚀产物膜对材料起到一定的保护作用,金属腐蚀受到抑制;当溶液pH值为10.5时,电极表面出现了钝化膜,试样表面腐蚀现象不明显,只有几个微小的腐蚀坑存在。High strength pipeline steel is widely used in the field of long-distance transfer of oil and gas pipelines,and the related corrosion phenomenon of the buried pipe welded joint is more obvious.In this work,the effects of pH value on corrosion behavior of X80 pipeline steel welded joints in simulated Ku' erle soil solution were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy(EIS).The corrosion morphologies were observed by metallographic microscope.Results showed that the corrosion rate of X80 steel welded joints was decreased slightly with the increase of pH value.When the simulated solution was acidic,the corrosion product films were destroyed on the surface of the metal electrode and the corrosion phenomenon of metal was accelerated by corrosive Cl^-,so that there were many corrosion pits on the metal surface.When the solution was alkaline,the metal was protected by the corrosion product films in a certain degree,and the corrosion of welded joints was restrained.When pH value was10.5,the passive films were formed on the surface of the sample and the corrosion phenomenon was not obvious.At the same time,there were only a few small corrosion pits on the surface of the metal.

关 键 词：土壤腐蚀 X80钢焊接接头 土壤PH值 腐蚀电化学 

分 类 号：TG407[金属学及工艺—焊接]