Patterns of the Formation of Reduced Hardness Zones in a Welded Joint of Railway Rails

The research investigates the structure of a welded joint of a railway rail after local heat treatment and without it. Macro- and microstructural analyses of rail samples were performed using optical microscopy methods. The hardness of the rail running surface in the heat-affected zone of butt welds was measured. It has been found that the formation of zones with reduced hardness is inevitable due to the temperature gradient created during the welding process. Moreover, using local induction heat treatment results in the formation of new, more extended zones with reduced hardness. It has been determined that the only solution to this problem is to reduce the extent of heat-affected zones to sizes that do not lead to increased wear and local crushing.