Study On The Effect Of Changing Axleload On Wear Properties Of Heavy-Haul Wheel/Rail

The wheel/rail is the most basic component of railway, so the wheel/rail contact has attracted general concern all the time. Especially in the new development period, it has being researched deeply that whether existing rail line will continue to play the important role efficiently when the axle load has changed。 In this article, the wheel/rail contact has been simulated by MMS-2A friction and wear tester under different loads as a reference, then adding the simulation load to research the impact of increased axle load on wheel/rail contact, reducing the simulation load to research the impact of decreased load on wheel/rail contact. The difference between samples is analyzed in several aspects:wear mass loss、 hardness、wear track、plastic deformation and micro-cracks.Based on the analysis, this thesis gets the following conclusions:1、The hardness of surface material in the contact area increase rapidly under both heavy and light load conditions, and wave at a high level at the later stage of the test. In light-load condition, the main damage pattern form of wheel/rail is fatigue crack, and the wear loss is very low, cracks are longer, some of them propagate into the inside of wheel/rail. In heavy condition, the main damage pattern form of wheel/rail is wear, the wear loss is very high, cracks are shorter, most of them are at or near the surface of wheel/rail.2、It is found that there is a sharp rise in the wear loss of wheel/rail,when the experiment simulate in light-load condition in the beginning and then increase the simulated axle load, and the increase rate of wear loss is much higher than that of simulated axle load. With the increase of simulated axle load,the hardness of surface material in the contact area increase slowly, but the increase is not significant. The crack length and depth decrease gradually. The main damage pattern form turns from fatigue crack to wear gradually. So, heavy haul train can run on heavy rail that has light-load experience and needing no maintain.3、After the simulation of heavy-load condition, The hardness of surface material in the contact area will stay in a relative high level. Then decrease the simulated axle load gradually, it is found that the rate of growth in wear loss reduces significantly because of the higher values of hardness in contact area of wheel/rail. With the decrease of simulated axle load, the fatigue cracks have a sustained growth and the wear loss decreases gradually. The cracks grow deeper Into the inside of wheel/rail, the number and length of crack increase significantly, train safety is under the serious hidden danger brought by the fatigue crack in the surface of wheel/rail. So wheel/rail have heavy-load operating experience need grinding and repairing before reducing the operating axle load to reduce the hidden danger brought by the damage of wheel/rail.