TEST AND FATIGUE OF THE RAIL

Abstract

The rail as the most signficant element of the railway track has been developed even in recent decade both in relation with its mechanical and chemical parameters. The evolution in testing the different steel materials permits to establish results in behaviour which are not specified by norms and their detailed calculation. Such is, e.g., the impact work as well as the determination of the transition temperature ,which in relation with the continuously welded rails (c.w.r.) might become a necessary requirement. The transition temperature of the rail steels in dependence on their mechanical and chemical properties is also dealt with by the paper. It has been established that the transition temperature of the rails currently used is very high and, consequently, the process of recrystallization does not take place at all in the case of the rails lying in the railway track. The steels of rail are to be classified in the brittle or in the transition zone of fracture. This circumstance ought to be changed in order to be able to reduce the rail failures and weld ruptures in winter time. The fatigue cracks in the rail, their propagation and the classification of these cracks under the safety limit is of importance from the point of view of a safety railway operation. The author investigates the occurrance of such deficiencies under the safety limit as well as the time-dependent propagation of them and gives answers to the questions relating to the classification aud development of the kidney-formed cracks caused by the fatigue of the rail steel, further he points out the position, form, extension and the fracture surface. In justifying the supersonic test of fatigue cracks presents its mathematical formuIa in dependence on the load.