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针对U71Mn60Kg/m干线钢轨使用过程中轨端发生开裂损伤现象,采用硬度检测分析及金相显微技术等手段对所取试样进行了宏观和微观的组织分析。探讨了一些新的淬火技术在高速铁路用钢轨轨端表面淬火中的应用。结果表明:原钢轨轨端表面淬火工艺不当,淬硬层厚度不够,层深不均且表层硬度相差较大,使钢轨轨端机械性能尤其是疲劳强度无法满足干线铁路高速运行列车对钢轨的使用要求,造成开裂损伤。较合理的工艺应采用多喷嘴式仿形喷头加热,并控制好加热后的冷却及回火工艺。采用工频感应热处理工艺也能得到较好的显微组织和性能。
In view of the phenomenon of cracking at the rail ends during the use of U71Mn60Kg / m rail, the microstructure and microstructure of the samples taken were analyzed by means of hardness testing and metallographic microscopy. The application of some new quenching technology to the surface quenching of rail ends in high-speed railway is discussed. The results show that the surface quenching of the original rail is not proper, the thickness of the hardened layer is not enough, the layer depth is not uniform and the hardness of the surface layer is quite different, which makes the mechanical properties of the rail ends, especially the fatigue strength, Requirements, resulting in cracking damage. A more reasonable process should be multi-nozzle profiling nozzle heating, and control the heating after the cooling and tempering process. Using frequency induction heat treatment process can get better microstructure and properties.