Research On Wear And Damage Behaviors Between Four Kinds Of Wheel Materials And U75V Rail

High-speed and heavy-haul railways encounter a great development of session, due to its efficiency、transport capacity、free from the effect of nature conditions like climate、low cost、safety、reliability and so on. Nowadays the railway has formed the world railway planning network. New development trend of railway leads to the more difficult problem of wheel/rail contact. The plastic deformation of surface material is closely related to wheel/rail damage, such as wear、rolling contact fatigue. This paper studies the wear、deformation and damage under different wheel materials and different axle loads using MMS-2A wheel/rail rolling wear testing apparatus. The electronic balance, the hardness tester, the profile meter, the optical microscope and the scanning electron microscope, et al.The formation of plastic deformation of surface material over time and its impact on initiation and propagation of crack。 The main conclusion are as follows:1.With the increasing of the hardness ratio of rail steels to wheel steels, the plastic deformation thickness of wheel samples decreases significantly, however, for the rail samples, the thickness increases firstly and then decreases. Furthermore, the increases of hardness of wheel samples to be some degree shorten the length of fatigue crack. The angle of the end of crack propagation of rails increases, thus leading to the fatigue cracks propagating to the heart of rail steels.2. The increasing of axle load will aggravate the wear of wheel/rail samples, and the rolling friction coefficient will increase at the same time.The larger the axle load is, the smaller the fluctuation of friction coefficient after it tended to be stabilized. The increasing of wheel-rail contact stress led to the crystal slip line slipping more deeply from the surface, therefore the plastic deformation thickness increased. With the increasing of axle loads, the surface damage of wheel samples transformed from adhesion damage to fatigue cracks. However, the rail surface damage is dominated by fatigue wear, it transformed from short fatigue cracks to long fatigue cracks and deep delamination.3. Due to the repeated cycles of contact stresses on surface layer materials, pearlite and proeutectoid ferrite structure transform into lamellar structure, and crystal structure of surface materials slips along the rolling direction. At last the plastic deformation is formed on the surface layer materials. With the contact of wheel-rail tends to be stable, the work hardening of plastic deformation layer strength the properties resistance to plastic deformation of surface materials. Thus there has no variation on the thickness of plastic deformation layer as the surface reach plastic shakedown state.4.While the accumulated plastic flow of surface exceeds limits and the differences generated in the slip amplitude of deformed lamellar structure, crack initiation may arise on the surface or sub-surface of wheel/rail. The surface damage of wheels mainly show as fatigue cracks and adhesion wear. Wheel materials with good wear resistance should be chose in case of excessive wear of wheel materials by cracks. Rail materials should have excellent resistance of fatigue and damage tolerance with a high yield strength. Consequently, fatigue crack damage on the surface of rail can be reduced to some degree.Then it will prevented the rail fracture caused by fatigue crack which propagate to the heart of rail steels.