摘要
采用不同温度对AISI 420马氏体不锈钢进行离子渗氮处理。借助光学显微镜和X射线衍射(XRD)技术分析了渗氮层的微观组织结构,利用显微硬度计测试了渗氮层的硬度分布,通过电化学极化曲线测试和盐雾腐蚀试验研究了离子渗氮AISI 420不锈钢在模拟工业环境中的腐蚀行为。结果表明:AISI 420不锈钢350℃低温离子渗氮层由ε-Fe3N和N过饱和固溶体αN相组成,其化学稳定性高,加之固溶Cr元素的联合作用,明显提高了AISI 420不锈钢基材的腐蚀抗力。AISI 420钢经450℃和550℃渗氮处理,渗氮层中的αN分解成了α相和CrN,造成基体贫Cr,降低了基材的耐蚀性能。马氏体不锈钢低温离子渗氮处理不仅可以提高表面硬度,而且可以获得良好的耐蚀性能。
The effects of plasma nitriding temperature on corrosion behavior of nitrided AISI 420 stainless steel were investigated. The microstructure, phase composition and microhardness of the nitrided layer were examined by means of optical microscope, X-ray diffraction technique and microhardness tester. The corrosion behavior of plasma nitrided AISI 420 stainless steel was evaluated by potential dynamic polarization and salt spray corrosion tests in a simulated industrial environment. The results show that the microstructure of nitrided layer obtained at 350℃ consists of ε-Fe3 N and αN, both of which are supersaturated nitrogen solid solution phase. The corrosion resistance of AISI 420 martensitic stainless steel is considerably improved by plasma nitriding at 350℃ due to the synergistic effect of dissolved Cr and high chemical stabilities phase of ε-Fe3 N and αN . When plasma nitriding is carried out at 450℃ or 550℃, the αN phase is decomposed into αand CrN phases which results in the depletion of Cr in matrix. Therefore, the corrosion resistance of the nitrided steel is reduced. Plasma nitriding at low temperature not only increases the surface hardness, but also improve the corrosion resistance of the martensitic stainless steel.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2007年第5期109-114,共6页
Transactions of Materials and Heat Treatment
基金
国家自然科学基金项目(50171054
50671085)
