高氮奥氏体的等温分解

The Isothermal Decomposition of High nitrogen Residual Austenite

采用纯铁片 640℃渗氮后油淬制得含有化合物层、高氮奥氏体层以及含氮马氏体层的 Fe- N合金薄片。利用光学显微镜、扫描电镜、显微硬度计及 X射线衍射仪分析了高氮奥氏体的等温分解过程。实验发现 ,渗层内高氮奥氏体的分解始于奥氏体层与化合物层的界面附近 ;分解产物的核心数目很多而核心的长大相当缓慢 ;分解产物高度弥散 ,硬度值高达 80 0 HV以上 ;分解产物的形貌既不同于回火马氏体 ,也不同于一般的贝氏体。

Fe N thin piece containing compound layer,Fe N martensite layer and high nitrogen austenite layer was obtained by nitriding at 640℃ using pure iron.Employed by optical microscope,scanning electron microscope,microhardness tester and X ray diffraction instrument,the isothermal decomposition process of high nitrogen austenite was investigated.The following was observed in the experiment.The decomposition of high nitrogen austenite in the nitriding layer started at the interface between austenite layer and compound layer.The number of decomposition products were large,while the size of them was very small,and the decomposition products was highly disperse,whose microhardness was up to HV800.The pattern of decomposition products was different from both the tempered martensite and normal bainite.