小半径曲线钢轨纵向条状剥离掉块原因分析及防治措施

Causes Analysis and Related Prevention Measures of Longitudinal Strip Peeling and Falling of Curve Rail with Small Radius

针对一普速铁路半径600 m曲线上股钢轨剥离掉块现象,通过检测分析钢轨表面掉块形貌、不同位置廓形变化、磨耗量、硬度、裂纹扩展行为等,研究其病害原因,并提出防治措施。结果表明:U71MnH钢轨基体组织、硬度、脱碳层、非金属夹杂物等均符合标准要求;钢轨硬度从非工作边到轨距角方向显著增大,产生明显塑性变形层;在过大接触应力反复作用下,钢轨表面容易出现疲劳裂纹,裂纹扩展至一定程度后发生分叉和偏转,进而形成剥离掉块伤损,该缺陷主要出现在轨距角的鱼鳞纹和轨顶面的纵向裂纹交界处。建议对该路段钢轨进行打磨,以消除表面缺陷,改善轮轨匹配关系。由于轮轨接触时同时发生磨损与疲劳伤损,两者之间存在竞争关系,润滑虽然可以减少磨损,但可能加剧疲劳伤损,因此选择适当的润滑时机是十分重要的。

In response to the phenomenon of steel rail peeling and falling on a curve with a radius of 600 m on a conventional railway,the surface morphology of the rail peeling and falling,changes in profile at different positions,wear,hardness,crack propagation behavior,etc.were detected and analyzed to study the causes of the disease and prevention and control measures were proposed.The results show that the matrix structure,hardness,decarburization layer,and non-metallic inclusions of U71MnH rail could meet the standard requirements.The hardness of the steel rail significantly increases from the non working edge to the track gauge angle direction,resulting in a noticeable plastic deformation layer.Under the repeated action of excessive contact stress,fatigue cracks are prone to appear on the surface of the rail.After the cracks propagate to a certain extent,they bifurcate and deflect,resulting in peeling,falling and damage.This defect mainly occurs at the junction of the fish scale pattern at the gauge angle and the longitudinal crack on the top surface of the rail.It is recommended to polish the steel rails in this section to eliminate surface defects and improve the wheel rail matching relationship.Due to the simultaneous occurrence of wear and fatigue damage during wheel rail contact,there is a competitive relationship between these two.Although lubrication can reduce wear,it may exacerbate fatigue damage.Therefore,choosing the appropriate lubrication timing is crucial.