3O4不锈钢在Cl^-+NO_3^-介质中孔蚀引发特性的研究

Study on Pitting Initiation Characteristic of 304 Stainless Steel In Cl^- +NO_3^- Solutions

测量了304不锈钢在0.5mol／LHCl＋0．5mol／LNaCl＋Xmol／LNaNO3（X=0001，0．01，0．05，0.2）溶液中的极化曲线，得到腐蚀电位Ec和击破电位Eb和NO-3浓度之间关系。结果表明，Ec和Eb都随NO-3浓度增加而正移。同时，将不锈钢记片在各试验溶液中作定时浸泡腐蚀试验，比较不锈钢孔蚀引发及早期发展之特性；低浓度NO-3介质中比高浓度NO-3介质中的孔蚀更为严重；蚀孔的扫描电镜观察表明，孔蚀易于在晶界，夹杂物等高能区引发。

By measuring the polarization curves of 304 stainless steel in the solutions of 0. 5 mol/LHCl+0. 5 mol/L NaCl+X mol/L N03 (X= 0. 001, 0.01, 0.05, 0.2), the relationships ofthe NO3 concentration and the corrosion Potential Ee and the breakdown potential Eb are tabu-lated. It is shown that R and Eb become more Positive with the increase of NO3 concentration.A immersion test of 304 stainless steel plates in the tested solution was made The results showthat pitting develops more rapidly in the dilute solutions of NO3 than in the relatively concen-trate solutions. Scanning electron micrographs of the initiated pits show that pitting generallyorigins at the higher energy region of the materisal, such as grainboundary, inclusions.