SO2-4对含Cl-溶液中316 L奥氏体不锈钢钝化行为及点蚀行为的影响

利用动电位极化、电化学阻抗、恒电位极化以及恒电流极化等电化学测试手段,并结合扫描电镜进行点蚀形态观察,探究了含Cl-溶液中SO2-4浓度对316L奥氏体不锈钢的钝化行为及点蚀行为的影响.结果表明,含Cl-溶液中SO2-4的加入能够使316L不锈钢钝化区变宽,使点蚀电位变正,维钝电流密度降低,进而提高316L的耐点蚀能力.但是在点蚀发生后,随着SO2-4浓度的升高,点蚀内部和边缘形态表现出更为复杂的趋势,蚀坑的周长面积比明显增大.

Effect of SO2-4 on the passive and pitting behavior of 316 L austenite stainless steel in a Cl-containing solution

The effect of SO2-4 on the passive and pitting behavior of 316L austenite stainless steel was investigated in a Cl--contai-ning solution using potentiodynamic polarization tests, electrochemical impedance spectroscopy tests, potentiostatic polarization tests, and galvanostatic polarization tests. In addition, scanning electron microscopy was used to observe the pitting morphology. The results show that the increased SO2-4 concentration increases the passive region of 316L, makes the pitting potential more positive, and decreases the current density, indicating an improved pitting resistance. However, the pitting morphology shows a more complicated trend, and the roughness of the pits increases with the increased SO2-4 concentration after pitting occurred.