Physical modeling of the asymmetric flow of the metal in the mold slab of continuous casting machine

Шрифт:
302

https://doi.org/10.15407/pmach2019.03.005
Met. litʹe Ukr., 2019, Tom 310-311, №3-4, с.5-9

A.P. Verzilov Ph.D, Researcher, e-mail: verzilovalex@gmail.com, ORCID: https://orcid.org/0000-0003-0463-5006

UDC 669.01.53:621.74.047

Summary:

The service life of the submerged entry nozzle (SEN) can be reduced due to clogging or erosion of its cavity, as well as erosion wear in the zone of the slag belt. At the same time, clogging of the SEN is a serious problem, since it is of a continuous nature and has a significant impact on the hydrodynamic pattern of metal outflow inside the mold of the slab continuous casting machine (CCM), making it asymmetric. This circumstance, in turn, affects the quality of the continuous cast billet.

In the process of continuous casting, the cavity of the SEN gradually grows and the nature of the outflow of flows changes, which leads to disruption of the technological process and can cause wave formation on the meniscus of the metal, as well as washing away the crust of the metal on the narrow walls of the mold. Visual confirmation of a serious violation of the pattern of flow distribution in the mold is possible already at the very last stage of the casting immediately before replacing SEN.

Based on this, the article presents studies aimed at studying the processes of metal outflow in the mold in the middle or end of casting using an SEN, in the cavity of which inclusions deposits are observed.

The article presents the results of physical modeling of the behavior of liquid steel in mold of slab CCM when the cavity of an SEN is clogging with inclusions for several of the most characteristic situations. The process of formation of funnel vortices in the mold was investigated, and the main negative consequences of this phenomenon were revealed. The occurrence of funnel vortices should be associated with the development of clogging processes, namely, the asymmetric nature of the movement of the metal in the mold. As a result, particles of mold powder mixture and residual inclusions are involved in the depth of the liquid bath.

Keywords:

Continuous casting machine (CCM), mold, submerged entry nozzle (SEN), clogging, asymmetric flow, slab.

REFERENCES:

  1. Smirnov, A.N., Verzilov, A.P. (2011). SEN for continuous casting of slabs on CCM. Chermetinformatsiya OJSC. Bul. Ferrous metallurgy, no. 9, pp. 42-51 [in Russian].
  2. Rakeps, K.G., Thomas, B.G. (1995). Clogging in Continuous Casting Nozzles. 78th Steelmaking Conf. Proc., Warrendale, PA. Vol. 78, pp. 723-734 [in English].
  3. Axelrod, L.M. (1996). Increase of durability of graphite-containing SEN for CCM. Refractories, no. 6, pp. 27-30 [in Russian].
  4. Smirnov, A.N., Efmova, V.G., Ukhin, V.E., Verzilov, A.P. (2013). Investigation of sediments formed inside the SEN during casting on a slab CCM. Com. scientifc works "Modern refractories and technology in the production of steel." According to the materials of the XIX International Scientifc-Technical Conference "Modern refractories: resource saving and application in metallurgical technologies". Donetsk: Noulidzh, pp. 92-98 [in Russian].
  5. Smirnov, A.N., Kubersky, S.V., Shtepan, E.V. (2011). Continuous casting of steel. Donetsk: DonNTU, 482 p. [in Russian].
  6. Thomas, B.G., Yuan, Q., Zhang, L., Vanka, S.P. (2003). Flow Dynamics and Inclusion Transport in Continuous Casting of Steel. NSF Design, Service, and Manufacturing Grantees and Research Conf. Proc., R.G. Reddy, ed., pp. 2328-2362 [in English].
  7. Mazumdar, D., Guthrie, R.I. (1999). The Physical and Mathematical Modeling of Continuous Casting Systems. ISIJ International. Vol. 39, no. 3, pp. 525-548 [in English].,
    https://doi.org/10.2355/isijinternational.39.524
  8. Axelrod, L.M., Parshin, V.M., Mazurov, E.F. (2007). The process of clogging SEN with continuous casting of steel. Steel, no. 4, pp. 30-33 [in Russian]