U71Mn干线钢轨开裂原因及热处理工艺分析

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。

Analysis of Quenching Techniques an d Cracking of the End of U71Mn Rail

Based on to the cracking phenomenon of U71Mn 60Kg /m trunk -line rail during its operation,macro -analysis an d microscopic ex-amination were adopted to analyze th e cause for cracking at the end of the r ail.Some new quenching techniques w ere discussed for the heat -treatment of the end of the rail using by high -speed circulating railway.The results show that the quenching t echniques of surface of the rail was not suitable for the end of the U71Mn r ail.The quenching layer is too thin t o be used,and the thickness is not hom ogeneous,the hardness is too high or too low to meet the demand for mechanical property.The reasonable technique is to use the multi -muzzle profile modeling sprayer to heat,and the cooling and temper tech nology after heating must be controlled correctly,too.Better microstr ucture and performance will be gained if50HZ induction heating technique be adopted.