Computer modeling of the process of siphon casting of a large metal cylindrical ingot

Electroslag remelting is one of the main ways to obtain high-quality large ingots from special steels and alloys, and in particular for the needs of power engineering. Casting in a mold is the most common way to obtain large-sized consumable electrodes for electroslag remelting. Computer modeling was carried out to determine the rational parameters of the process of casting large cylindrical ingots by the uphill casting. This paper presents the simulation results of the movement of liquid metal flows during the filling of a mold with liquid metal and the process of forming a crust of solid metal at that time under the conditions of the uphill casting of a round steel ingot with a diameter of 1 m with a height-to-diameter ratio of 6.5 and a mass of about 40 tons. Analysis of the results of computer simulation shows that in the bath of liquid metal in the mold there is a non-stationary hydrodynamic picture, which changes as the internal volume of the caster is filled with liquid metal. Solidification of the metal begins already at the initial stage of filling the mold. However, under the influence of liquid metal flows, the formation of a crust of solidified metal occurs unevenly due to the uneven distribution of the heat flow from the liquid-metal bath around the perimeter and height of the mold wall, which creates conditions for the hot surface cracks occurrence. To prevent the formation of surface defects, it is recommended to take measures to stabilize the upward flow of liquid metal. The effect of mold preheating on the intensity of metal solidification during the filling of the mold with liquid metal was also investigated. Preheating reduces the amount of solid phase formed during the filling of the mold with liquid metal. The most significant inhibition of the formation of a solid phase with a decrease in the solidified metal volume fraction of 40 % is observed under the condition of preheating the mold wall to at least 550–600 °C.