Choice of Refractory Concrete for a Continuous Casting Machine Tundish Nozzle Dispenser
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Vol. 61, No. 4, November, 2020
CHOICE OF REFRACTORY CONCRETE FOR A CONTINUOUS CASTING MACHINE TUNDISH NOZZLE DISPENSER A. S. Timofeeva,1,3 V. D. Shishkin,2 and N. A. Morozova2 Translated from Novye Ogneupory, No. 7, pp. 21 – 24, July, 2020.
Original article submitted September 29, 2019. Experimental studies are presented for choice of refractory concrete for a continuous casting machine tundish nozzle dispenser. Three types of refractory concrete are considered in the experiments governed by their basic thermal properties, and refractory concrete is chosen with the best performance. Nozzle dispensers are manufactured and approved under production conditions that demonstrate good results during steel continuous casting. Keywords: nozzle dispenser, steel continuous casting, CBCM, channel closure, refractory concrete, filler.
Within the world 80% of steel is produced in continuous billet casting machines (CBCM). Compared with casting into a mold this method is most effective with respect to duration of the casting process and saving metal. However, high-temperature complexly shape refractory objects such as the nozzle dispenser are required for a CBCM. One of the problems arising with use of a nozzle dispenser during steel continuous casting is closure of its channel, limiting the amount of cast metal and reducing billet quality [1]. The reason for nozzle dispenser closure is “freezing” of steel in the channel as a result of a reduction in its temperature and the high thermal conductivity of the nozzle dispenser material. Often there is sticking of nonmetallic and slag inclusions to the walls during casting. In this case burning of the nozzle dispenser channel with oxygen has an unfavorable effect on casting as a whole due to deterioration of organization for the stream entering a crystallizer as a result of disruption of the geometry of the nozzle dispenser internal cavity. Correspondingly this considerably increases the degree of steel secondary oxidation. On the other hand, as a result of interaction of molten metal with nozzle dispenser material there may be impregnation by oxides of iron, manganese, silicon, and aluminum, and in the case of forming readily melting fractions at the
metal-refractory boundary there may be nozzle wall washing out (Fig. 1). A feature of casting steel with an open stream through a nozzle dispenser is the small cross section of its inner cavity in relation to casting rate and billet cross section. In this case maintenance of the metal level in the crystallizer is accomplished due to changing the billet withdrawal rate and the
1
Fig. 1. Nozzle dispenser schematic wear during casting: 1 ) breakdown in contact area with head stopper; 2 ) erosion as a result of breakdown on contact with metal stream; 3 ) closure of internal cavity; 4 ) breakdown in contact area with nozzle dispenser.
2 3
A. A. Ugarov Staryi Oskol Technological Institute (branch of FGAOU VO NITU MISiS), Staryi Oskol, Russia. ZAO PKF NK, Staryi Oskol, Russia. [email protected]
360 1083-4877/20/06104-0360 © 2020 Springer
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