高氮钢在Cl-/HCO3-共存环境中点蚀敏感性研究

摘要

采用循环极化电化学测试方法,在不同浓度的Cl-和HCO3-混合溶液中对高氮钢进行电化学测试,根据循环极化曲线滞回环面积的大小以及点蚀表面形貌特征,分析高氮钢在Cl-/HCO;共存环境中的点蚀敏感性.结果表明:高氮钢在Cl-/HCO3-共存环境中的点蚀行为为钝化膜破裂型点蚀;高氮钢点蚀行为受Cl-和HCO3-两种离子协同作用的影响,点蚀敏感性随Cl-浓度的增加而增大;当Cl-浓度低于0.025mol/L时,高氮钢的点蚀敏感性随HCO3-浓度的增加而增大,当Cl-浓度较高时,点蚀敏感性随HCO3-浓度的增加而降低.%The cyclic polarization electrochemical test method was adopted for the electrochemical test of high nitrogen steels in the Cl-and HCO3--mixed solution with different concentrations.According to the hysteresis loop area of cyclic polarization curves and pitting surface's morphology features,the pitting sensitivity of high nitrogen steels in Cl-/HCO3--coexisted environment was analyzed.The results show that,the synergy of Cl-and HCO3-influences the high nitrogen steel's pitting corrosion;and the pitting corrosion's sensitivity increases with the increase of Cl-concentration;and when the Cl-concentration is lower than 0.025mol/L,the pitting sensitivity of high nitrogen steels increases with the increase of HCO3-concentration;when the Cl-concentration is higher,the pitting sensitivity decreases with the increase of concentration of HCO3-.