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Metal Science and Metallography
ArticleName Assessment of central heterogeneity in slab to forecast centerline segregation in plate steel
DOI 10.17580/cisisr.2018.02.10
ArticleAuthor A. A. Kazakov, E. I. Kazakova, A. Kur

Peter the Great St. Petersburg Polytechnic University (St. Petersburg, Russia):

A. A. Kazakov, Dr. Eng., Prof., e-mail:
E. I. Kazakova, Leading Engineer
A. A. Kur, Cand. Eng.


Continuous cast slabs obtained on curvilinear casting machine have an asymmetric macrostructure with reference to their wide faces. This asymmetry is associated with a different coefficient of heat transfer when feeding water from above and from below to wide faces with a small and large radius, respectively. In such complex asymmetric thermo-physical and hydrodynamic conditions of solidification, a centerline segregation of the slab is formed. Slab centerline segregation may be narrow or wide dependent upon the development of the above-mentioned processes. To reveal the slab centerline segregation, the samples were etched with a 15 % aqueous solution of ammonium persulphate for 10–30 minutes. The images of the slab centerline segregation structure and their evaluation were obtained using the Thixomet Pro image analyzer. A wide segregation zone in a slab always leads to a high class of centerline segregation in the plate at any volume fraction of segregation spots in the slab central zone. In the absence of a wide slab centerline segregation, the class of plate centerline segregation is linearly increased with an increase of the volume fraction of segregation spots in the narrow slab centerline segregation.

keywords Central heterogeneity, cast slabs, plate steels, centerline segregation, asymmetric macrostructure, solidification, etching, image analyzing

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Full content Assessment of central heterogeneity in slab to forecast centerline segregation in plate steel