Experimental Investigation Of Rail Damnification Mechanism

The railway transportation in China has been developed rapidly during the first decade of the 21st century. With the increase of train speed and axle load, wheel-rail is bearing ever heavier tribological load and its rolling contact fatigue (RCF) and wear become more and more serious. Various damages of wheel-rail have occurred in some railway lines in China.Laboratory research has been carried out to study the occurrence of wear and rolling contact fatigue damage of rail material using JD-1 wheel/rail simulation facility. The interrelationship between fatigue and wearing during the rolling contact of wheel/rail is discussed and the damage mechanism of the rail is analyzed to provide theoretical basis for the selection of rail materials used in high-speed and heavy-load railway. The main achievements and conclusions are as follows:1. The analysis of testing for the rails on Guangzhou-Shenzhen Railway shows that U75V rail has higher intensity and hardness, but the energy consumption of its crack propagation is low. The rate of crack propagation for U75V rail is higher than that of U71Mn rail. Therefore, the performance of antifatigue crack propagation of U71Mn rail is better than that of U75V rail and U71Mn rail is more applicable to the high-speed railway.2. Laboratory research results indicate that with speed increasing, the wear volume of rail is reduced, as well as many oblique cracks initiate and contact fatigue becomes severer.With axle load increasing, the plastic deformation becomes severer, increasing of wear volume and fatigue failure become slight due to removing of micro-cracks partly. The wear volume of rail roller increases rapidly and fatigue failure become severer with the curve radius decreasing. Furthermore, the rail rollers appear the obvious plastic flow.3. For the rail material with a higher hardness, the wear volume is less and plastic deformation layer is thinner after the rolling test. However, its crack propagation is more significant and the fatigue damage is severer with better wear resistance. Meanwhile, for the rail material with a lower hardness, the wear volume is larger and the plastic deformation layer is thicker. In addition, high wear rate reduces the rolling contact fatigue damage by constantly removing surface cracks. The analysis shows that U75V quenched rail with better wear resistance is suitable for heavy haul railway and U71Mn hot rolled rail with better fatigue resistance is more suitable for the high-speed railway.