СТРУКТУРА І ВЛАСТИВОСТІ ЗВАРНИХ ЗʼЄДНАНЬ СТАЛІ 20, МОДИФІКОВАНОЇ НАНОЧАСТИНКАМИ НА ОСНОВІ КАРБІДУ ВОЛЬФРАМУ.

The work is devoted to study of the influence of process parameters of welding steel 20 on the structure and properties of low carbon steel welded joints. Experimental steel was modified by nanosized carbide modifier of the system of «thermally split graphite (TRG)–wolframite». The aim of the study was to establish the details of formation of the structure and complex of mechanical properties in the material, containing dispersed reinforcing particles of the carbide phase under the thermal influence of welding processes. The steel was obtained by the method of electron beam remelting (EBR) of the charge billet, which included a nanoscale carbide modifier. Welding of experimental steel samples was performed using electron beam welding (EBW) and argon-arc welding (AAW) technologies. The obtained samples were used to study the macro- and microstructure of the base metal and welded joints by optical microscopy, as well as to determine the mechanical characteristics of metal of welded joints. It was found that the base metal, produced by EBR and following hot rolling of the obtained ingot has a homogeneous ferritic-pearlitic structure, but the morphology of the carbide phase in eutectoid colonies differs from plate pearlitic morphology due to the presence of spheroidized carbide phase particles. In welding by AAW technology, structures with the morphology of the same type as in the base metal are formed in the HAZ, the main difference is the increase in the degree of carbide phase spheroidization and some increase in grain size. EBW technology leads to formation of narrow layers with the structure of lath martensite in the weld fusion zone. It has been established that both the welding technologies provide joints with mechanical characteristics on the level of the base metal, but the EBW technology ensures higher ductility characteristics of the metal. Ref. 13, Table. 4, Fig. 7. [ABSTRACT FROM AUTHOR]