基于化学热处理低碳CrNiMoV轴承钢疲劳性能的研究

Fatigue Properties of Low-Carbon CrNiMoV Bearing Steel Modified by Carburizing and Nitriding

为了探究化学热处理工艺对轴承钢旋转弯曲疲劳性能的影响,本文利用旋转弯曲疲劳试验研究了低碳CrNiMoV轴承钢渗碳处理和复合硬化处理后的疲劳性能,分析了表面化学热处理后的组织、硬度分布、表面粗糙度和表面应力分布对旋转弯曲疲劳性能的影响。结果表明：复合硬化的表层存在厚度为4~6μm氮化物层和厚度为0.3 mm的碳氮化物层,表面的显微硬度为885 HV,比渗碳的要高93 HV;与单一渗碳相比,复合硬化后材料表面的残余压应力提高了102.59 MPa。复合硬化后的低碳CrNiMoV试验钢旋转弯曲疲劳性能明显优于单一渗碳。

We addressed therotating-bending fatigue properties of the surfaces of low-carbon CrNiMoV bearing steel,modified by a combination of carburizing and nitriding. The influence of the properties of the surface-modified bearing steel,including the depth profile of hardness,residual stress distribution,surface roughness and texture,on the rotating-bending fatigue behavior was investigated with scanning electron microscopy,white light scanninginterferometry and conventional mechanical probes. The results show that the duplex hardening outperforms carburizing,because of the significantly improved mechanical and fatigue properties. For example,the resistance against rotatingbending fatigue increased considerably; layers of 4 ~ 6 μm nitride and 0. 24 mm carbide / nitride were observed; the micro-hardness（ 885 HV） and residual compressive stress of the duplex hardened bearing-steel,were 93 HV and102. 59 MPa higher than that of the carburized one,respectively. Possible mechanisms responsible for the improved mechanical and rotating-bending fatigue properties were also tentatively discussed in a though-provoking way.