摘要
采用Ｘ射线衍射仪及光学显微镜分析了Ｗ１８Ｃｒ４Ｖ高速钢离子氮碳共渗层的相结构，采用连续加载压入法研究了共渗层脆性。研究结果表明：在渗氮气氛中引入ＣＨ４进行离子氮碳共渗时，碳的渗入可抑制渗层中γ′Ｆｅ４Ｎ相的形成；渗层中γ′Ｆｅ４Ｎ相的减少，降低了ε与γ′相混合时的脆性。另一方面ＣＨ４的引入增加了碳化物相，会使脆性增加，综合效果取决于Ｖ（Ｎ２）／Ｖ（Ｈ２）值及ＣＨ４加入量。选择比例适当的Ｎ２、Ｈ２、ＣＨ４气氛，可使共渗层脆性较单纯渗氮小；当Ｖ（Ｎ２）∶Ｖ（Ｈ２）为３∶１时，随ＣＨ４量的增加，渗层深度增加至一定峰值之后下降。
With the help of X ray diffraction and optical microscopy,the phase structure of the plasma nitrocarburized layer of W18Cr4V high speed steel has been investigated.The brittleness of the layer is studied by continuous indent loading.It has been found that during nitrocarburizing,with the addition of CH 4 to the treatment atmosphere,the carbon which diffuses into the layer can suppress the formation of γ′ Fe 4N. When the amount of γ′ decreases,the brittleness which results from the mixture of γ′ and ε decreases.The diffused carbon promotes the formation of carbides at the same time,which results in the increase of brittleness.The combined effect depends on the ratio of N 2 to H 2 and the amount of CH 4.When appropriate volume ratio of N 2,H 2 and CH 4 is chosen for the atmosphere,the brittleness of the plasma nitrocarburized layer can be lower than that of the plasma nitrided only.When V (N 2)∶ V (H 2) is 3∶1,with increasing of CH 4 amount,the thickness of nitrocarburized layer increases first and then decreases.
基金
国家自然科学基金
关键词
离子氮碳共渗
高速钢
相结构
脆性
渗层
plasma nitrocarburizing,\ high speed steel,\ phase structure,\ brittleness
