Сhair “Metallurgical teсhnologies”, St. Petersburg State Polytechnical University (St. Petersburg, Russia):

Kazakov A. A., Head of the chair, Dr. Eng., Prof., E-mail: kazakov@thixomet.ru
Pakhomova O. V., Leading engineer
Kazakova E. I., Leading engineer

The paper presents study of evolution of cast structure of ferrite-pearlite steel during its thermomechanical processing. Imitation of controlled rolling of specimens cut from different structural areas of industrial continuously cast slab has been conducted using "Gleeble 3800" multi-functional research complex. Investigations have been conducted on the specimens of steel 15, taken fron continuously cast slab with cross section 2501,200 mm. Regularities of evolution of different structural areas of cast billet are established in the process of deformation simulating controlled rolling. It is shown that structural heterogeneity along thickness of sheet metal is connected with metallurgical inheritance, i.e. features of segregation distribution in cast slab. Relationship between different components of deformed structure has been examined from the point of view of inheritance of typical elements of cast structure, using metallographic methods and micro-X-ray spectral analysis. Obtained data testified that Mn content in the massive ferrite areas with sulfide inclusions is less by 1.5 times than in average for the batch, because part of manganese has been used to form MnS sulfides. It was established that combination of high dispersity and density of dendrite structure in the area of columnar grains of continuously cast slab provides forming of more homogeneous and dispersed structure after rolling, comparing with the central area of equiaxial grains.

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