宽温域下高速轮轨界面粘着与车轮表面损伤行为

搭建了高低温服役环境轮轨滚动试验台，在实验室条件下成功再现了哈大线等高寒铁路冬季车轮表面剥落和麻点严重、夏季异常光滑的季节性损伤特征；研究了宽温域(-50 ℃~60 ℃)下高速列车轮轨界面粘着和车轮损伤行为，系统探讨了不同服役温度下轮轨滚动接触界面的粘着系数演变规律，分析了车轮表面磨损形貌和表层材料塑变行为等重要特性。研究结果表明：随着服役温度的提高，轮轨界面粘着系数总体呈下降趋势，同时，车轮表面的凹坑尺寸减小，在高温60 ℃时，凹坑特征消失，磨损表面变得较为平整；在低温-40 ℃时，车轮表面最为粗糙，算术平均粗糙度为3.74，而随着服役温度的上升，磨损表面粗糙度显著下降，在高温60 ℃时，车轮表面算术平均粗糙度较小，为0.97；随着服役温度的升高，轮轨接触界面的磨损区域内Fe元素含量与O元素含量之比逐渐减小；低温低湿环境抑制了轮轨界面的摩擦氧化作用，增强了摩擦剪切作用，加剧了车轮表面的剥落、严重的塑性变形和表面疲劳裂纹的萌生与扩展，因此，磨损表面较为粗糙；而高温环境加速了轮轨界面的摩擦氧化作用，氧化磨屑的形成一定程度上起到了固体润滑作用，从而降低了轮轨界面间的粘着，车轮表面相对光滑；磨损机制由低温(-50 ℃~-20 ℃)服役工况下的疲劳磨损逐渐转变为常温(20 ℃)工况下的磨粒磨损和氧化磨损与高温(40 ℃~60 ℃)工况下的粘着磨损。

High-speed wheel-rail interfacial adhesion and surface damage behavior of wheel in wide temperature range

The wheel-rail rolling tester in a high/low temperature environment was built, and the seasonal damage characteristics of wheel surfaces with delamination and pits appearing in winter, and unusually smooth characteristics presenting in summer in the Harbin-Dalian Railway and other alpine railways, were successfully reproduced under laboratory conditions. The wheel-rail interface adhesion and wheel damage behavior of high-speed trains in a wide temperature range (-50 ℃-60 ℃) were studied. The evolution laws of the adhesion coefficient of wheel-rail rolling contact interface were systematically discussed under different service temperatures, and the important characteristics of wheel surface worn morphology and plastic behavior of surface materials were analyzed. Research results show that the adhesion coefficient of wheel-rail interface decreases with an increase of the service temperature. At the same time, the sizes of the pits on the wheel surface decrease, and the pits disappear and the worn surface becomes smoother at 60 ℃. At a low temperature of -40 ℃, the wheel surface is the roughest with the arithmetic mean roughness of 3.74. As the service temperature increases, the roughness of the wheel surface decreases significantly. At a high temperature of 60 ℃, the roughness of the wheel surface is small, and arithmetic mean roughness is 0.97. As the service temperature increases, the element content ratios of the Fe to O in the wear area of the wheel-rail contact interface decrease gradually. A low-temperature and low-humidity environment inhibits the frictional oxidation of the wheel-rail interface, enhances the frictional shear, aggravates the delamination on the wheel surface and serious plastic deformation, and promotes the initiation and propagation of surface fatigue cracks. Therefore, the wear surface is relatively rough. However, the high-temperature environment accelerates the frictional oxidation of the wheel-rail interface, and the formation of oxidized debris plays a solid lubrication role. Therefore, the adhesion of wheel-rail interface reduces, and the wheel surface is relatively smooth. The wear mechanism gradually changes from the fatigue wear at low temperature (-50 ℃~-20 ℃) to the abrasive wear and oxidation wear at room temperature (20 ℃), and adhesive wear at high temperature (40 ℃~60 ℃). 2 tabs, 12 figs, 32 refs.