采用微观组织观察、失重、动电位扫描、四点弯曲试验、恒电位阴极极化等方法研究了TMCP X80管线钢焊接件在酸性海水中的应力腐蚀及阴极保护规律。结果表明, X80管线钢焊接件母材和热影响区的微观组织及电化学性能相似, 焊材的缺陷导致焊接件成为耐应力腐蚀的薄弱区; 四点弯曲条件会促进焊接件的腐蚀, 但在不含S2-等极易与铁结合的离子的酸性海水中, 焊接件的应力腐蚀并不严重; -900 mV(vs.SCE)更适用于抑制X80管线钢焊接件在该环境下的应力腐蚀。

The stress corrosion cracking of TMCP X80 pipeline steel weldment and its inhibition by potentiostatic cathodic protection in acidic seawater were studied by microstructure observation, polarization curves, four-point bending test, potentiostatic cathodic polarization and weight loss method. The results show that the base metal and heat affected zone of X80 pipeline steel weldment have similar microstructure and electrochemical properties, the weldment is the weak area against stress corrosion cracking because of the defect of weld. Four-point bending conditions can promote the corrosion of weldment, but this kind of corrosion is not serious in such acidic seawater without the ions such as S2- etc which are easy to combine with iron; -900 mV (vs. SCE) is more suitable to inhibit the stress corrosion of X80 pipeline steel weldment in such a medium.