Nosov Magnitogorsk State Technical University, Magnitogorsk, Russia:

E. M. Golubchik, Dr. Eng., Prof., Dept. of Materials Processing Technologies, Associate Prof., e-mail: e.golubchik@magtu.ru
D. N. Chikishev, Dr. Eng., Prof., Dept. of Materials Processing Technologies, Associate Prof., e-mail: d.chikishev@magtu.ru
O. A. Kupriyanova, Cand. Eng., Associate Prof., Dept. of Materials Processing Technologies, e-mail: o.nikitenko@magtu.ru

The article describes a fundamentally new approach to improving the technology for the production of high-quality rolled metal for enamelling. It has been established that the most significant technological factors influencing the quality of such rolled metal products are the temperature and speed conditions of hot rolling and coiling of the strip on a wide-strip mill, as well as the strategy for cooling the surface of the strip on the discharge roller table. To assess the quality level of rolled metal for enamelling, the indicator of steel resistance to hydrogen embrittlement is traditionally used, which is determined on the basis of laboratory bending of samples-plates from rolled metal. If the values fall within the allowable ranges, it must be guaranteed (with a certain degree of probability) that there is no “fish scale” defect on the enamelled products. However, the traditional methods for determining the propensity of rolled metal products to the formation of a “fish scale” defect today can be considered outdated, of a subjective nature and requiring significant updating. Therefore, it is proposed to apply a new quality indicator - the volume fraction of structurally free cementite in the microstructure of rolled metal. The article considers a new research methodology for determining the proposed indicator using digital technologies. It has been proven that an insufficient level of structurefree cementite in the microstructure of rolled products increases the tendency to form a “fish scale” defect. The high content of cementite globules (more than 2.7%) makes it possible to effectively capture and retain hydrogen and prevent its release to the surface of the product, which guarantees the absence of a “fish scale” defect. An innovative technology of wide-strip hot rolling has been developed, which makes it possible to provide high values of the volume fraction of cementite in the microstructure of rolled metal.

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