Electrical flash-butt welding of rails in situ

Up until the end of 1974 the only method used on the entire track network of Italian State Railways (FS) for welding rails in situ was the thermit welding method. However, considerations concerning the quality of the welded joints have caused FS to employ the method of electrical flash-butt welding to an ever greater extent, both to produce new rails and to recondition used rails with lengths of 36 m. The greater strength of the welded joints achieved by electrical flash-butt welding gives them a better fatigue behavior. Moreover, the thermal influence of the basic material is limited to a smaller area which is accompanied by a more regular distribution of hardness values. All this prevents the formation of irregularities on the rail running surface in the vicinity of the welded joints which can cause hammering on the rail ends when trains pass over the joints. In addition to these advantages, there is the consistency of the results achieved by welding machines that are not influenced by the operator. This means a distinct reduction, if not almost complete elimination, of defective welds.