Research On Impact Of Rail Materials To The Wear And The Microscopic Structure Of The Wheel/Rail

As railway takes up a significant role in modern economic development,high-speed and heavy-duty become the objective of global railway development,which require a higher standard for the wheel system. At the same time, the new service environment also has put the compatibility of current wheel material to a more crucial position. Therefore, it is significant and practical to investigate the compatibility of widely used steel-rail and wheel material. The endeavor of modeling railway movement and researching on the compatibility of railway materials yields guiding significance in reducing railway damage and promoting better development.Due to Hertz contact theory, the compatibility between wheel material (CL60) and four commonly used steel rail material of U71Mn after hot-rolled、U71Mn after hardened and PD3(hot rolled) and PD3steel (hardened)was studied under the load of15、21t and25t in dry condition. Surface analysis testing equipments such as optical microscope(OM)、Vickers hardness tester (MVK-H21)、scanning electron microscope (SEM) and XRD are used to analyze the abrasion of friction pair, variation of the abrasion, abrasive surface variation, top layer structural variation and the shape and the phase of debris. Such conclusions can be seen as follows:1) With the increase of the applied load, the abrasion of each specimen increases.While the effect on wheel is much more apparent than that on steel rail. It can be seen that wheel ends up in enhancement of abrasion and steel rail results in increase of fatigue ratio. The increase of the applied load makes the increase ratio of abrasion larger,and it also makes the plastic deformation layer of steel wheel thicker.However,it has little effect on wheels except making the crack position more close to the surface.2) Under the condition of the same load, when the hardness of steel rail material increases, its abrasion and the surface damage decreases correspondently, but the fatigue ratio increases, the abrasion and surface damage of wheel with mainly abrasive damage would increase with the increase of the hardness of steel rail. Meanwhile, the increase ratio of the abrasion of steel rail specimen decreases with the increase of the hardness of steel rail material, but for the wheel, it appears on the opposite situation. The larger hardness a steel rail has, the thinner its plastic deformation layer it has, the shallower the cracking position and hole position are. The hardness of steel rail hardly affects the plastic deformation layer of the wheel and the position of the crack. However, the increase of the hardness of steel rail results in the larger crack sizes of the wheel specimens.3) The shape of debris is subject to material. The debris of hot-rolled steel friction pair generally appears in flake shape with comparatively even sizes. While the debris of hardened steel friction pair appears in uneven sizes with a mix of powder and flake shaped debris. The XRD curves of four types of debris of friction fair almost have complete coincidence. Main components of debris are Fe2O3and martensite,and larger applied load and higher peak strength indicate larger amount of Fe2O3and martensite.