N含量对13Cr超级马氏体不锈钢耐蚀性的影响

对13Cr超级马氏体不锈钢进行氮合金化,采用淬火-配分热处理工艺,研究了不同N含量对13Cr钢的微观组织及电化学腐蚀行为的影响。结果表明:随N含量增加,板条马氏体组织表现出明显的细化行为,奥氏体含量增加,且有VN生成,从而防止N与Cr结合生成Cr₂N,促使Cr在材料表面形成以Cr₂O₃为主的致密腐蚀产物膜,提高材料耐蚀性;试验钢表面以局部腐蚀为主,试样表面有点蚀发生。随着N含量的增加,形成腐蚀产物膜的孔隙度减小;表面钝化膜为双电层结构,增加了钝化膜的稳定性,点蚀坑数量明显减少且变小;提高N含量有利于试样耐点蚀性能的改善,0.35%N试验钢表面腐蚀产物附着牢固,平整且致密,晶粒大小均匀,可起到良好的保护作用。

Effect of N content on corrosion resistance of 13Cr super-martensitic stainless steel

Nitrogen alloying of 13Cr super-martensitic stainless steel was carried out, quenching and partitioning process was adopted to study the influence of different N content on microstructure and electrochemical corrosion behavior, the results show that with the increase of N content, the lath martensite shows an obvious fining behavior. The austenite content is increased through the formation of VN, which prevents the combination of N and Cr to form Cr₂N, and the Cr forms a corrosion product film dominated by Cr₂O₃ on the surface of the steel, thus improving the corrosion resistance of the steel. The surface of the tested steel is dominated by local corrosion, and pitting corrosion occurs in the specimens. With the increase of N content, the porosity of the corrosion product film decreases, and the surface passivation film is of an electric double layer structure, which increases the stability of the passivation film, and the number of pitting pits is significantly reduced and the pits are smaller. The increase of N content results in the improvement of pitting resistance of the specimens, the corrosion products on surface of the tested steel containing 0.35%N are firmly attached, smooth and compact, and the grain size is uniform, playing a good protective role.