CO2环境下油酸咪唑啉对X65钢异种金属焊缝电偶腐蚀的抑制作用研究

研究了X65管线钢与316L不锈钢、Inconel 625双金属复合管的异种金属焊缝在CO2环境下的电偶腐蚀行为,以及油酸咪唑啉的缓蚀作用。结果表明,随着电偶电位差的增大,异种金属焊缝的腐蚀速率明显升高,并且都显著高于母材。添加油酸基咪唑啉缓蚀剂能降低异种金属焊缝在CO2环境下的均匀腐蚀速率。但是,当缓蚀剂浓度添加较低时,异种金属焊接试样的碳钢一侧出现了严重的沟槽腐蚀或密集的点蚀坑;进一步增加缓蚀剂浓度才能消除沟槽腐蚀现象。讨论了缓蚀剂对异种金属焊缝电偶腐蚀的抑制机理,该项研究可为异金属焊接接头处的腐蚀防护提供借鉴。

Corrosion Behavior and Corrosion Inhibition of Dissimilar Metal Welds for X65 Steel in CO2-containing Environment

The corrosion behavior of X65 pipeline steel,and the galvanic corrosion behavior of dissimilar metal welds of X65/316L stainless steel and X65/Inconel 625 in CO2-containing environments,as well as the inhibition effect of imidazoline oleic acid corrosion inhibitor on the corrosion were assessed.The results show that with the increase of the potential difference of the galvanic couples,the corrosion rate of the weld seams for X65 steel with different metals increases obviously,and which is significantly higher than that of the base metal.The addition of oleic acid imidazoline corrosion inhibitor can reduce the uniform corrosion rate of the weld seams for X65 steel with different metals in CO2-containing environment,but when the corrosion inhibitor concentration is low,serious groove corrosion or dense pitting pits appear on the X65 steel side of the welds for X65 steel with different metals.Further increase of corrosion inhibitor concentration can eliminate the phenomenon of groove corrosion.The electrochemical polarization curves and electrochemical impedance spectroscopy were used to analyze the inhibition mechanism of corrosion inhibitors on galvanic corrosion of dissimilar metal welds.This study can provide a reference for the corrosion protection of welding joints of dissimilar metals.