St. Petersburg State Polytechnical University, St. Petersburg, Russia:

Kazakov A. A., Head of the chair “Steel and Alloys”, kazakov@thixomet.ru

Pakhomova O. V., Dr. Eng., Prof., Leading engineer, the chair “Steel and Alloys”

Kazakova E. I., Leading engineer, the chair “Steel and Alloys”

Dendritic structure of industrial slab of ferrite-pearlite steel has been investigated by methods of metallographic analysis and X-ray spectrometry analysis. Some regularities of elements correspondence of dendritic and cast grain structure were established. Dispersity and density of dendritic structure of continuously cast slab of 15 steel has been examined and it was shown that dispersity and density in different slab structural areas differ by two and three times respectively. Absence of distinct visual correspondence between dendritic and cast grain structure is displayed. Primary and secondary dendritic axes are located non depending on boundaries or body of cast grain; several dendritic axes can cross one or several cast grains. It was found out that ferrite is forming on the most “dirty” areas of inter-dendrite space that solidifies in the last turn, while further along grain body is located ferrite with “widmanstätten” pattern, pure from segregations and formed of dendritic axes. At the same time, boundaries of cast grain are decorated by allotriomorphic ferrite formed by inter-dendrite space with moderate content of segregations, formed from inter-dendrite space of early stage of solidification. It was established that axes of dendrites are formed according to mechanism of cellular growth, thereby they are characterized by heterogeneous structure.

1. Merton C. Flemings.  Protsessy zatverdevaniya (Solidification processes). Translated from English. Under the editorship of A. A. Zhukov and B. V. Rabinovich. Moscow : Mir, 1977. 424 p.

2. Ruiz-Aparicio А.  MS Evolution in Nb-bearing microalloyed steels produced by the compact strip production process. University of Pittsburgh, 2004.

3. Kudrya A. V., Sokolovskaya E. A., Vodopyanov E. A.  et al. Sovmestnoe vliyanie raznomasshtabnykh struktur na kolebanie kachestva metalloproduktsii (Combined influence of non-uniformly scale structures on the fluctuation of metal products quality). Bernshteynovskie Chteniya po termomekhanicheskoy obrabotke metallicheskikh materialov (Bernshteyn Readings on the thermal treatment of metallic materials). Moscow : MISiS, 2006.

4. Formirovanie stalnogo slitka : sbornik nauchnykh trudov (Formation of the steel ingot : collection of scientific proceedings). Acade my of Sciences of Ukrainian SSR, Institute of Foundry Problems. Moscow : Metallurgiya, 1986. 88 p.

5. Khvorinov N. I. Kristallizatsiya i neodnorodnost stali (Crystallization and heterogeneity of steel). Moscow : State Scientific and Engineering Publishing House of Machine-building Literature, 1958. 392 p.

6. Kostyleva L. V., Gabelchenko N. I., Ilinskiy V. A. Issledovaniya faktorov, opredelyayushchikh dispersnost dendritnykh struktur staley (Researches of the factors, which determine the dispersibility of dendrite structures of steels). Metally — Russian metallurgy. 2008. No. 5.

7. Metallografiya zheleza. Tom III. “Kristallizatsiya i deformatsiya staley” (s atlasom mikrofotografiy) (Metallography of iron. Volume III. “Crystallization and deformation of steels” (with the microphotography atlas)). Translation of “Metallurgiya” Publishing House, 1972. 236 p.

8. Kazakov A. A., Chigintsev L. S., Kazakova E. I.  et al. Metodika otsenki likvatsionnoy polosy listovogo prokata (Estimation methodology of the liquate flat of product strip). Chernye Metally — Ferrous metals. 2009. No. 12.

9. Anastasiadi G. P., Silnikov M. V. Neodnorodnost i rabotosposobnost stali (Heterogeneity and operability of steel). Saint Petersburg : LLC “Poligon” Publishing House, 2002. 624 p.

10. Kiessling R. Non-metallic inclusions in steel, Part V. London : The metals society, 1978. pp. 173–177.

11. Livshits B. G. Metallografiya (Metallography). Moscow : Metallurgizdat, 1963. 422 p.