Embrittlement of welded joints of tram rails in city environments

This paper concerns the issue of cracking of thermite-welded tram rails. The work presents cases of rail cracking revealed directly after welding or after a short period of track operation. The results of static strength tests, resistance to brittle cracking tests, microstructure and chemical composition examinations of a rail that cracked after thermite welding are discussed. It is emphasised that the main cause of occurrence of cracks in the area of rail web is thermal (welding) stresses. Non-metallic inclusions, the presence of hydrogen in the rail and the influence of an active environment were pointed out as factors conducive to the occurrence of brittle cracks.