重载铁路钢轨损伤行为分析

利用电感耦合等离子体光谱仪、硬度仪、光学显微镜和扫描电子显微镜等对现场重载铁路损伤钢轨进行各种微观测试分析,分析了重载钢轨的损伤机理。结果表明:重载钢轨中碳、硅、锰含量较高,这有利于提高钢轨强度、硬度和耐磨性;现场服役损伤钢轨的表面硬度明显高于新钢轨的表面硬度,其轨距角处和轨顶区硬度高于非接触区的硬度;现场服役钢轨和新钢轨试样均表现为残余压应力;疲劳裂纹主要在轨顶区表面萌生，扩展较深且扩展角度明显不同，疲劳裂纹扩展方式主要表现为穿晶和沿晶扩展，钢轨侧磨区几乎无疲劳裂纹存在;轨顶区域塑性变形严重，塑性区组织明显被拉长细化呈流线型，塑性层厚度与裂纹扩展深度大致相同。

Analysis of Damage Behavior of Heavy-haul Railway Rails

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.