The existence of narrow and brittle white etching layers (WELs) on the rail surface is often linked with the formation of rail defects such as squats and studs, which play the key roles in rail surface degradation and tribological performance. In the present study, a systematic investigation on stress/strain distribution and fatigue life of the WEL during wheel-rail rolling contact was conducted based on a numerical model considering the realistic wheel geometry. This is the first study considering the influence of rail materials, loading pressure, frictional condition, WEL geometry (a/b), and slip ratio (Sr) in the practical service conditions at the same time. The results revealed much higher residual stress in WEL than in rail matrix. Stress changes along the rail depth matched with the previously reported microstructure evolutions. The current work revealed that the maximum difference in contact stress between the wheel passages of rail matrix and the WEL region (noted as stress variation) rises with the increase of loading pressure, the value of a/b, and Sr; but drops with the friction coefficient (μ). In addition, a critical length-depth ratio of 5 for a/b has been found. The fatigue parameter, FP, of the WEL decreased quickly with the length-depth ratio when it was less than 5 and then increased slightly when it was larger than 5. This study also revealed that the fatigue life of the WEL was reduced for high strength head hardened (HH) rail compared with standard carbon (SC) rail.

中文翻译：

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白色蚀刻层对轮-轨界面滚动接触行为的影响

轨道表面上存在狭窄且易碎的白色蚀刻层（WEL），通常与轨道缺陷（如下蹲和双头螺栓）的形成有关，而缺陷在轨道表面的退化和摩擦学性能中起着关键作用。在本研究中，基于考虑实际车轮几何形状的数值模型，对轮轨滚动接触期间WEL的应力/应变分布和疲劳寿命进行了系统研究。这是第一个考虑轨道材料，负载压力，摩擦条件，WEL几何形状（a / b）和滑移率（Sr）在实际使用条件下同时进行。结果表明，WEL中的残余应力远高于轨道矩阵中的残余应力。沿钢轨深度的应力变化与先前报道的微观结构演变相符。目前的工作表明，随着负载压力，a / b值和Sr值的增加，轨道矩阵的车轮通道与WEL区域之间的最大接触应力差（称为应力变化）会增大。但是随着摩擦系数（μ）下降。此外，a / b的临界长深比为5已找到。当小于5时，WEL的疲劳参数FP随长度-深度比而迅速减小，而当其大于5时，疲劳参数FP随长度-深度比而略有增加。该研究还表明，WEL的疲劳寿命会随着高强度而降低。头部硬化（HH）导轨与标准碳（SC）导轨相比。