采用热处理炉对X80管线钢进行200 ℃回火30 min, 通过动电位极化, 电化学阻抗谱等技术研究了回火前后X80钢在NaHCO3溶液中的腐蚀电化学行为。结果表明, 回火前后X80在NaHCO3溶液中的腐蚀都是阴极控制腐蚀类型, 但低温回火后X80钢的自腐蚀电位从回火前的-0.739 V降低为-0.877 V(SCE), 并且维钝电流也从回火前的5.48 μA·cm-2升高到17.82 μA·cm-2; 电化学阻抗谱测试表明, 低温回火后的钝化膜比回火前X80钢钝化膜疏松, 这与金相显微镜观察结果相吻合。

X80 pipeline steel was tempered for 30min at 200 ℃ with a heat treatment furnace, and then the electrochemical behavior of X80 steel before and after tempering in the solution of NaHCO3 was studied by the method of potentiodynamic polarization , electrochemical impedance spectroscopy and so on. The results showed that the corrosion was the type of cathodiz control. The corrosion potential of the X80 steel was reduced from -0.75 V before tempering to -0.80 V (SCE) after tempereing, and the passive current increased from 5.48 μA·cm-2 before tempering to 17.82 μA·cm-2 after tempered; AC impedance measurements show that the passive film of tempered X80 steel was loose, which is consistent with the observations of atomic force microscopy.