氮含量对高纯奥氏体不锈钢耐蚀性能的影响及机理的研究

Influence of N Content on Corrosion Resistance of High-Purity Austenitic Stainless Steel and Its Mechanism Research

采用电化学、化学浸渍、ＸＰＳ、ＡＥＳ、物理化学相分析等方法研究了氮对高纯奥氏体不锈钢０００Ｃｒ１９Ｎｉ１４耐点蚀、晶间腐蚀和应力腐蚀开裂性能的影响并对其作用机理进行了探讨。结果表明，氮的加入可以显著改善钢的耐点蚀性能；高纯奥氏体不锈钢加氮（≤０．２０％）合金化敏化热处理不会引起晶界贫铬，在沸腾６５％ＨＮＯ３中主要是均匀腐蚀；在含有Ｃｒ６＋的硝酸溶液中，当氮含量不超过０．０８６８％时对晶间腐蚀影响很小，而氮含量超过０．０８６８％时氮含量增加则晶间腐蚀加剧。因此认为氮元素在晶界偏聚以及高氮钢中氮化铬在晶界的析出是晶间腐蚀加剧的原因；在沸腾４２％ＭｇＣｌ２溶液中的慢应变速率实验（ＳＳＲＴ）结果显示，适当量的加入氮，可以降低固溶态钢的应力腐蚀敏感性，而对敏化态钢没有影响。

This paper presents a study of the effects of nitrogen on the pitting corrosion,intergranular corrosion and stress corrosion cracking behaviour of high-purity austenitic stainless steel 000Crl9Nil4.The results show that nitrogen enhances the pitting resistance significantly.Nitrogen alloying high-purity steels reveal no chromium- depletion at grain boundaries after sensitized heat treatment, and are mainly general corrosion in boiling 65% HNO3 tests.Up to 0.0868%nitrogen additions have very small effects on intergranular corrosion in boiling HNO3 tests with Cr 6+, but above 0.0868%,have detrimental effects as a result of nitrogen segregation and precipitation of chromium nitrides at grain boundaries.Slow strain rate tests(SSRT)conducted on the steels of various nitrogen content in boiling 42%MgCl2 solution indicate that additions of nitrogen lower the susceptibility of the steels upon solution heat treatment to stress corrosion cracking(SCC),and have no effects on the steels upon sensitized heat treatment.