高压干法X65管线钢GMAW焊接接头在模拟海水中的腐蚀行为  

Corrosion behavior of X65 pipeline steel welded joints by hyperbaric GMAW in simulated seawater

作　　者：张忠明[1,2] 薛龙[2] 李齐龙 黄继强[2] 徐春杰[1] ZHANG Zhongming;XUE Long;LI Qilong;HUANG Jiqiang;XU Chunjie(Xi’an University of Technology,Xi’an,710048,China;Opto-mechatronic Equipment Technology Beijing Area Major Laboratory,Beijing Institute of Petrochemical Technology,Beijing,102617,China)

机构地区：[1]西安理工大学,西安710048 [2]北京石油化工学院,光机电装备技术北京市重点实验室,北京102617

出　　处：《焊接学报》2021年第5期45-50,I0004,I0005,共8页Transactions of The China Welding Institution

基　　金：国家自然科学基金资助项目(51275051);北京市自然科学基金—北京市教委联合资助项目(KZ20180017022);光机电装备技术北京市重点实验室开放课题(KF2013-01).

摘　　要：高压干法熔化极气体保护焊(简称GMAW)在海底油气管道等水下构件的组装和维修中有着非常广泛的应用,焊接接头在海水中的腐蚀行为对于海底输油管道的安全运行至关重要.通过模拟浸泡试验和极化曲线法研究不同环境压力下(常压,0.3 MPa,0.5 MPa)X65管线钢干法GMAW焊接接头在人工海水中的腐蚀行为及机理.结果表明,与焊缝和母材相比,热影响区的耐蚀性最差,且环境压力对焊接接头的腐蚀性能影响不明显.X65管线钢干法GMAW焊接接头在人工海水中的腐蚀形式以点蚀为主,在浸泡后期出现严重的局部腐蚀;腐蚀产物由FeOOH,Fe_(2)O_(3),Fe_(3)O_(4)组成,腐蚀产物层在浸泡初期起到减缓金属腐蚀的作用,但随着浸泡时间延长,腐蚀产物层的致密性降低,其下的金属接头容易遭受到Cl^(−)的破坏,使局部腐蚀过程加剧.Hyperbaric dry GMAW is widely employed commercially in the fabrication and maintenance of submarine oil and gas pipelines.The corrosion behaviors of welded joint in seawater are therefore of utmost importance in security operation of the pipelines.The corrosion performance and mechanism of X65 pipeline steel welded joints by hyperbaric GMAW under different ambient pressures(0.1,0.3,0.5 MPa)were studied by polarization curves and immersion simulation experiments in artificial seawater.It was found that compared with the welding base metal and welded zone,the corrosion resistance of heat affected zone is the worst,and the ambient pressure has little effect on the corrosion resistance of the welded joint.Corrosion morphology and corrosion product shows that pitting corrosion is the main corrosion form for the welded joints,and serious local pitting corrosion occurs at the late immersion stage.The corrosion product is composed of FeOOH,Fe_(2)O_(3) and Fe_(3)O_(4).The corrosion product on the surface of the welded joints can mitigate the corrosion at the initial immersion stage.With prolonged immersion durations,the compactness of the corrosion products layer reduces,the metal under the layer is vulnerable to the corrosion by Cl^(−),and thus the local pitting corrosion process is promoted.

关 键 词：X65管线钢 高压焊接 熔化极气体保护焊 腐蚀性能 

分 类 号：TG444.72[金属学及工艺—焊接]