On the railways of Ukraine since 2012 the laying of high-strength rails of steel grade K76F of company «MK Azovstal» production, as well as rails produced in Russia, in tracks began. For this purpose at PWI the technology for flash-butt welding of high-strength rails of different production was developed, providing the values of strength and ductility of welded joints required according to the Technical Specifications. In the process of industrial implementation of technology for welding the high-strength rails by the rail welding enterprises of Ukraine a large amount of information was gained on the results of complex application of in-process control with non-destructive and destructive testing methods. It was established that the formation of metal structure in the joint zone alongside with energy input has a significant influence on the composition and distribution of non-metallic inclusions in the base metal of welded rails. The type and the structure of defects are largely determined by the composition of non-metallic inclusions. This effect is manifested in different degrees during changes in energy input in the process of welding. 5 Ref., 3 Tables, 8 Figures.
K e y w o r d s : flash-butt welding, flashing, rails, high-strength rails, pulsed flashing, defects in rails, non-metallic inclusions, dull spots, quality control, continuous trackAt PWI the technology of flash-butt welding of highstrength rails of different production was developed, providing the values of strength and ductility of welded joints required according to TS. It is based on the method with pulsed flashing (PF) [1], allowing joining the high-strength rails with their minimal softening and preservation of the required ductile properties. As compared to the known technologies for welding rails, the developed technology requires 1.5-2 times lower energy input.A stable reproduction of technological process requires precise control of energy input, that is provided by the system of automatic control of flashing process using the system for in-process control the welding parameters. At the same time, the maximum admissible deviations from the preset temperature field were established, that provide the optimal conditions for joint formation [2].In the process of industrial implementation of the technology for welding the high-strength rails by rail welding enterprises (RWE) of Ukraine a large volume of information was gained on the results of complex application of in-process control with non-destructive and destructive testing methods. It was established that the formation of metal structure in the joining area alongside with energy input has a significant influence on the composition and distribution of non-metallic inclusions (NMI) in the base rails metal. This effect is manifested in different degrees during changes in energy input in the process of welding.The aim of the investigations was to study the effect of NMI in the rail steel on formation of the structure of welds of high-strength rails.To carry out investigations at the RWE the s...