低温对EA4T车轴钢疲劳性能的影响

为解决现行高铁车轴设计标准未考虑低温环境给高铁车轴的使用带来一定安全隐患的问题,运用旋转弯曲疲劳试验方法测试不同温度下试验钢疲劳性能,采用扫描电子显微镜观察疲劳断口,借助透射电子显微镜观察不同温度断口附近位错组态.结果表明:EA4T车轴材料应力敏感性与温度成反比,高于-80℃条件下EA4T车轴材料低温服役的疲劳性能优良...

Effect of Low Temperature on Fatigue Properties of EA4T Axle Steel

The current design standard of high-speed railway axle does not incorporate the hazardous situation of low temperature,which brings certain hidden danger to the use of high-speed railway axle.In this paper,the fatigue properties of the tested steel at low temperature were studied by means of rotating bending fatigue tests.The fatigue fracture was observed by scanning electron microscope.The dislocation configurations near the fracture surface at different temperatures were observed by transmission electron microscope.Results show that the stress sensitivity of EA4T axle material is inversely proportional to the temperature.It has excellent fatigue performance when the temperature is higher than?80℃,without fatigue ductility-brittle transition temperature.Accordingly,it is safe and reliable.With the decrease of temperature,the number of free dislocations decreases,and the generation and expansion of dislocations are confined to the direction of dense arrangement of Body Centered Cubic(BCC)lattice.As a result,the threshold of driving force required for dislocation initiation is increased,and the fatigue crack is initiated and propagated at the surface crystal boundary.The crack grows by dislocation sliding.