X80管线钢焊接接头重构及其在NACE溶液中的腐蚀行为

借助模块化的阵列电极制备技术对X80管线钢焊接接头进行模拟重构,并采用经典电化学测试技术与微电极阵列测试技术研究X80钢模拟焊接接头在CO2饱和的NACE溶液中的腐蚀行为。结果表明,孤立的母材区开路电位最正,热影响区次之,焊缝金属的开路电位最负;腐蚀电流密度表现为焊缝>母材>热影响区;在NACE溶液的浸泡过程中,焊缝区始终作为腐蚀电偶对的的主阳极,腐蚀加速;热影响区始终作为主阴极,腐蚀减缓,母材微电极随着与焊缝区距离不同,其电流极性不一、交替出现。在本文实验条件下,焊缝区是X80钢模拟焊接接头的薄弱环节。
A welded joint was reconstructed by the wire beam electrode (WBE) techniques, and the electrochemical corrosion behavior of X80 pipeline steel welded joint in NACE solution saturated with CO2 was investigated by the microelectrode array (MEA) techniques and classical electrochemical technique.The results show that the open circuit potential values of isolated electrode decrease in the three sectors as below:the base metal, the heat affected zone and the weld metal. By contrast, the corrosion current densities show a different tendency, the biggest value exists in the weld metal zone, and the smallest value exists in the heat affected zone. In this process, the weld metal acts as the main anode, while the heat affected zone acts as the main cathode, and the current polarity of base metal electrode changes alternatively with the distance between the micro-electrode and the weld metal zone during the immersion test. Under these experimental conditions, the weld metal is the weak link in the simulated X80 pipeline steel welded joints