不同钝化工艺对S22053不锈钢腐蚀行为的影响

Effects of Different Passivation Processes on Corrosion Behavior of S22053 Stainless Steel

针对同一种材料经不同钝化工艺处理后钝化膜的形成、耐蚀性的优劣、钝化后腐蚀行为的比较鲜有报道,为此,通过极化曲线、电化学阻抗谱、临界点蚀温度、再钝化温度测试等方法考察了自然钝化、阳极钝化和酸洗钝化3种钝化工艺对S22053不锈钢耐腐蚀性能的影响,并通过扫描电镜观察了腐蚀前后试样表面的表面形貌。结果表明:阳极钝化和酸洗钝化都可以提高S22053不锈钢的耐腐蚀性能,采用20%(质量分数)硝酸酸洗钝化后不锈钢的耐腐蚀性能最好;不同钝化工艺对S22053不锈钢的点蚀电位影响并不显著,但会显著改变不锈钢的阻抗和临界点蚀温度;点腐蚀发生后腐蚀前沿有明显的沿晶腐蚀倾向,同时伴随有奥氏体晶粒的优先溶解。

The effects of three passivation processes including natural passivation,anode passivation and acid pickling passivation,on the corrosion resistance of S22053 stainless steel were investigated by electrochemical polarization curve,electrochemical impedance spectroscopy,critical pitting temperature and repassivation temperature tests.The surface morphologies of the samples before and after corrosion were observed by SEM.Results showed that both anode passivation and pickling passivation could improve the corrosion resistance of S22053 stainless steel,and 20%(mass fraction)nitric acid passivation process had the best corrosion resistance.Different passivation processes had no significant effects on the pitting potential of S22053 stainless steel,but they would significantly change the resistance of stainless steel and the critical pitting temperature.There was an obvious tendency of intergranular corrosion at the corrosion front after pitting corrosion.At the same time,the phenomenon of preferential dissolution of austenite grains was accompanied.