Influence of chemical composition and dendritic structure of continuous casting on the heterogeneous effects in rolled steel
Background. Cast metal structure hereditary influence on the properties of finished products is an important issue. To improve the quality of rolled wire it is necessary to obtain continuous casting specimen with the maximum possible length of the zone of equiaxial crystals, dispersed centerline segregation, centerline porosity being welded in the process of hot plastic deformation. Objective. To investigate the continuous casting specimen dendritic structure influence on structure formation in rolled wire associated with the segregation phenomena. Methods. The research was carried out on the industrial continuous casting lots with the initial cross section of 125125 mm from C82D and C86D steels and 11,0 mm in the ready-made diameter. The optical light microscope «Axiovert 200 M MAT» and the binocular microscope «MBI-2» were used. Results. The formation of dendritic structures is most favorable if electromagnetic mixing (EMM) technology is used. In the rolled steel products, made at continuous casting with EMM, there is a tendency to spreading segregation and structural banding, as well as a decrease in the width of martensitic areas. Conclusions. The positive effect of electromagnetic mixing on the reduction in the width of martensitic areas in rolled wire, as well as on the change in the length of the various zones of the dendritic structure in cross-section continuous casting specimen has been established. Segregation increases when the steel is alloyed