含氮奥氏体不锈钢的敏化行为

Sensitization Behavior of Nitrogen Containing Austenitic Stainless Steel

通过65%硝酸浸泡法和电化学动电位再活化法定量评价188奥氏体不锈钢的晶间腐蚀倾向,并利用分析电子显微镜确定晶界的贫铬区,利用透射电子显微镜及电子衍射技术确定晶界析出物的结构。试验结果表明:适量增加氮含量可提高188奥氏体不锈钢的耐晶间腐蚀性能。敏化状态下再活化率Ra在氮的质量分数为0.16%时最低;当氮的质量分数大于0.16%时,贫铬区最低铬含量随氮含量的增加而降低;贫铬区宽度在氮的质量分数为0.16%时最窄,氮含量继续提高则贫铬区宽度扩大。

The intergranular corrosion susceptivity of 18-8 austenitic stainless steel was estimated through dipping the sample in 65% HNO3 and electrochemical potentiokinetic reactivation (EPR) technique. The chromium-depletion profile and the structure of precipitates at grain boundary were determined using scanning transmission electron microscopy (STEM) and X-ray diffraction (XRD). The results showed that by adding nitrogen, the intergranular corrosion resistance of 18-8 austenitic stainless steel can be enhanced. The sensitized sample with 016%N has the minimum rate of reactivation (Ra) and the narrowest chromium-depleted zone. While the content of nitrogen in steel is above 016%, the minimum chromium content of chromium-depleted zone is decreased and the width of chromium-depleted zone is increased with nitrogen content.