气体渗氮对中碳车轴钢超长寿命疲劳性能的影响

Effect of gas nitriding on the fatigue properties of medium carbon railway axle steel in a very high cycle regime

研究了气体渗氮在材料表面层由表及里逐次形成的氧化物层、氮化物层及N固溶层对中碳车轴钢超长寿命旋转弯曲疲劳性能的影响.与未处理试样相比,带有氧化物层、去除氧化物层及去除氮化物层的渗氮试样的疲劳强度逐级提高.去除氧化物层和去除氮化物层的试样在超长寿命区分别发生次表面和内部破坏.通过断口观察和断裂分析,阐明了渗氮处理材料的表面层对超长寿命疲劳性能的影响.

After gas nitriding three layers are formed on the surface of medium carbon railway axle steel from the exterior to interior,they are oxide layer,nitride layer and N-diffusion layer respectively.The effect of the three surface layers on the rotary bending fatigue properties of the steel was investigated in a very high cycle regime.Compared with the fatigue strength of untreated specimens,the strengths of nitrided specimens with the oxide layer,the specimens from which the oxide layer was removed and the specimens from which the nitride layer was removed greatly increased step by step.Nitrided specimens without the oxide layer fractured from the position between the compound layer and diffusion layer at the subsurface;while the ones without both the oxide and nitride layers fractured from the matrix.Through fractography and fracture analysis,the effect of the three surface layers on the fatigue properties was clarified in a very high cycle regime.