Únavové charakteristiky ocelí pro kolejová vozidla v závislosti na tepelném zpracování

Abstract

Throughout its long history of railway rolling stock vehicles showed, in some cases, as an optimal solution in terms of the mode of transport across a range of products, raw materials but also people around the world. Rail transport and associated services are very often reflects the state of the economy and can establish a link between the maturity of the company and the density of its rail network. This area of transport is very demanding on the actual quality of the materials that are involved in the implementation of the settlement and development of railway transport routes, but also in the construction of vehicles. Challenging the selection and ongoing monitoring and verification of the quality of production is one of the prerequisites for maintaining a high service life, but also the security of these solutions. Its use has found, for example rail transport, public transport, public transport, material transport, transport mining or smelting. Nevertheless rail transport must constantly fight very hard for their place in the market with its competition, which consists mainly of automobile and air transportation. One of the fundamental parts of railway vehicles is called wheelsets, which as an independent structural and functional element consists in most cases from the axle and two wheels on it are pressed. From the viewpoint of mechanical action of the environment is one of the most stressed parts and also from the viewpoint of safety it is one of the most critical points of rail vehicles. While the very beginnings of resistance testing machine units against fatigue are associated just with railway axles. During operation, forces act on the wheel set, related to the weight-bearing vehicle itself eventually loads and forces associated with the management of vehicles in the transverse and longitudinal direction, as well as with exhaust heat energy generated during braking of the vehicle. With that it is necessarily associated force transmission between the vehicle and the rails in a direction radial, axial and tangential. These forces are often dynamic nature of variable amplitude and frequency. Individual parts of the railway wheel (wheels, axles) are in the course of its operation subjected to cyclic loading and the resultant effect of time-varying components of the stress may lead, ultimately, to initiate microscopic damage in the surface layers of the material. In the event that the voltage is less than the yield strength of the material damage accumulates with increasing number of cycles, unless the development of cracks or other damage, which results in refraction component.