20CrMnTi钢碳氮复合强化层的制备与性能

Preparation and properties of CN composite strengthening layer of 20CrMnTi steel

采用真空脉冲先渗碳后渗氮、真空脉冲感应渗氮、等离子渗氮等方法在20CrMnTi钢表面制备碳氮复合强化层,利用X射线衍射仪、光学显微镜、扫描电镜、能谱仪和显微硬度计等分析了改性层的物相、组织结构、截面元素分布、致密性和显微硬度梯度。结果表明:真空脉冲先渗碳后渗氮能够获得平缓的硬度梯度;真空脉冲感应渗氮1 h就能够制备出35μm左右的渗氮层,大大的缩短了渗氮时间;先渗碳再离子渗氮工艺能获得50μm左右硬度值高和致密性好的渗氮层,次表层为回火马氏体组织,其渗层深度和氮元素相对含量几乎是单一离子渗氮的两倍。

The CN composite strengthening layer was prepared on the surface of 20 CrMnTi steel by vacuum impulse nitriding,vacuum pulse induction nitriding and plasma nitriding. The phase,microstructure,cross section element distribution,density and microhardness gradient of the modified layer were analyzed by means of X-ray diffractometer,optical microscope,scanning electron microscopy,energy dispersive spectrometer and microhardness test. The results show that the gentle hardness gradient can be obtained by vacuum pulse carburizing first then nitriding,and the nitriding layer of 35 μm or so can be prepared by vacuum pulse induction nitriding for 1 h,which greatly shortens the nitriding time. The nitrided layer with a high hardness and good compactness of about 50 μm can be obtained by first carburizing and then plasma nitriding,and the sub-surface layer is martensite,and the depth of the layer and the relative content of nitrogen are almost two times of that of the single ion nitriding.