关键词: 重载钢轨, 硬度, 残余应力, 疲劳裂纹, 塑性变形

Abstract:

The damage behavior and mechanism of heavy-haul rails were investigated in detail using various examinations by means of inductively coupled plasma spectrometer, hardness tester,optical microscope and scanning electron microscope. The results indicate that high content of carbon, silicon and manganese elements result in excellent strength, hardness and wear-resistance of heavy-haul rails. The surface hardness of damaged rail in the field is higher than that of new rail. Furthermore, the hardness of rail corner and head zone is higher than that of no-wear regions. The residual stresses of damage and new rails presented compressive stress state. Fatigue cracks always initiated from the rail head surface and then the propagation of cracks appears different crack angles. The intergranular and transgranular growth are dominating propagation modes for the heavy-haul rail cracks. There is almost no fatigue crack on side wear area. In addition, there is severe plastic deformation on the rail head zone and the microstructure is crushed and exhibits obvious streamline. The thickness of deformation layer is roughly the same with crack's growth depth.

Key words: heavy-haul rail, hardness, residual stress, fatigue crack, plastic deformation