X80管线钢管在5%NaCl+0.5%醋酸溶液中的腐蚀行为研究

应用动电位极化、电化学阻抗谱和浸泡试验方法研究了X80管线钢管母材和焊缝试样在5%NaCl+0.5%醋酸溶液中的腐蚀行为。结果表明，焊缝试样的开路电位较母材负移，在电化学腐蚀过程中，母材和焊缝区的腐蚀过程受活化极化控制，焊缝区具有较高的腐蚀速率。母材和焊缝的电化学阻抗谱均具有两个时间常数，母材极化电阻值大于焊缝区。在浸泡试样中，随着浸泡时间的延长平均腐蚀速率逐渐下降，但焊缝区产生严重的选择性腐蚀现象。

Study on Corrosion Behavior of X80 Pipeline Steel in 5%NaCl+0.5% Acetum

The corrosion behavior of X80 pipeline steel base metal and weld specimens were studied by potentiodynamic polarization，electrochemical impendence spectroscopy and immersion test in 5%NaCl+0.5% acetum. The result showed that the open circuit potential of the weld sample is more positive than the base metal sample. The process of electrochemical corrosion is activation-controlled and the weld sample is with a high corrosion rate. The electrochemical impendence spectroscopy presents two time constants，the polarization resistance of base metal is higher than that of weld joint. The average corrosion rate from the immersion test decreases gradually with the immersion time increasing, but serious selective corrosion appear on the weld zone.