Cl^-和应力对X80管线钢电化学腐蚀行为的影响

Influences of Chloride Ions and Stress on Electrochemical Corrosion Behavior of X80 Pipeline Steel

目前,对于Cl^-和应力同时作用时钢铁腐蚀行为及机理的研究不多。采用动电位极化和交流阻抗谱,研究了Cl^-和应力对X80管线钢在高pH值溶液中腐蚀行为的影响。结果表明:Cl^-对X80管线钢的钝化行为有显著影响,当Cl^-浓度小于0.10 mol/L时,X80管线钢表面会形成稳定的钝化膜,当Cl^-浓度大于0.10 mol/L时,则不会形成稳定的钝化膜。在自腐蚀电位下,少量的Cl^-可增加X80管线钢的腐蚀倾向,但大量Cl^-可降低其腐蚀倾向。外加应力使交流阻抗谱低频区出现第二段容抗弧,并且提高自腐蚀电位下X80管线钢的溶解速率。

The influences of chloride ions and stress on the electrochemical corrosion behavior of X80 pipeline steel in solution with high pH value were discussed by potentiodynamic polarization and electrochemical impedance spectroscopy.Results showed that the passivation of X80 pipeline steel was influenced by Cl^-concentration.When the Cl^-concentration was less than 0.10 mol/L,a stable passive film was formed on X80 pipeline steel.When the Cl^-concentration was more than 0.10 mol/L,no stable passive film was generated.Under the free-corrosion potential,a small amount of Cl^-could increase the corrosion tendency of X80 pipeline steel,but a large amount of Cl^-would reduce the corrosion tendency.Besides,the second capacitive arcs appeared in the low-frequency area of alternating current impedance because of applied stress,and the applied stress could accelerate the dissolution rate of X80 pipeline steel under free-corrosion potential.