氢对X80钢焊接接头在近中性pH值溶液中腐蚀行为的影响

采用动电位极化和电化学阻抗技术研究了电化学充氢后X80钢母材和焊缝在近中性pH值溶液中的电化学行为,并结合光学显微镜对试样充氢前后的形貌进行了观察,测量了母材和焊缝的放氢量。结果表明,电化学充氢并没有改变钢的组织结构;相同电化学充氢条件下,焊缝比母材吸收更多的氢。在近中性pH值溶液中,未充氢时母材比焊缝有更好的耐蚀性能。充氢促进母材和焊缝在近中性pH值溶液中的阳极溶解。随充氢时间增加,母材和焊缝的自腐蚀电位负移,腐蚀电流增大,腐蚀产物膜电阻和极化电阻减小,母材与焊缝电化学腐蚀行为均加剧。充氢后焊缝中位错缺陷浓度高,对氢起钉扎作用的,使焊缝的耐蚀性大于母材。

Effect of Charged-hydrogen on Corrosion Behavior of Welded Joint of X80 Pipeline Steel in a Near-neutral pH Solution

The electrochemical corrosion behavior of hydrogen-charged base metal and welded joint of X80 pipeline steel in a near-neutral solution was studied by means of potentiodynamic polarization and electrochemical impedance spectroscopy. The morphologies of the base metal and the welded joint of X80 pipeline steel were observed by optical microscopy and the content of released-hydrogen were measured, respectively. It was found that charged-hydrogen had little effect on the microstructure of X80 pipeline steel. The hydrogen content of the welded joint is higher than that of the base metal under the same hydrogen charging condition. The base metal demonstrated higher corrosion resistance than the welded joint when they were not hydrogen charged. However, the charged hydrogen facilitated the anodic dissolution of the base metal and the welded joint of X80 pipeline steel, and the corrosion were accelerated in the near-neutral solution with the increase of charging time. Due to pinning effect on the hydrogen induced by the higher concentration of dislocations defects, the welded joint showed better corrosion resistance than that of the base metal.