SU712193A1 - Method of making ingots - Google Patents

Description

The invention relates to ferrous metallurgy, in particular to the casting of metals and alloys.

It is known that the refractory slag-forming mixture is introduced during the filling of the mold on Vs-7z part 1.

This method eliminates the ingress of slag particles into the lower part of the ingot, but ife eliminates the likelihood of slag inclusions in the middle part of the ingot due to their entrainment by convective currents deep into the metal. As a consequence, the use of such a method is impractical when casting steel from above, when the jet causes intense mixing of the metal at the ingot solidification front. In addition, it is difficult to determine the moment of introduction of the slag-forming components into the mold, as the temperature of the metal and the rate of lifting of the metal during casting change.

- Technical solutions are also known in which the contamination of the metal of this part of the ingot by slag inclusions is reduced by reducing the oxidation of the first portions of the metal that fall into the mold when casting steel from above. Such a solution includes, for example, a method for the production of ingots, which consists in adding 0.05-1.0 kg / ton of deoxidizing agents to the bottom of the mold before casting with an additive of synthetic slag, which eliminates entanglement at the initial moment of casting. slag inclusions in metal 2.

However, during high-speed casting of metal, splashes and splashes form from the top when the jet hits the bottom of the mold or pan, which do not have time to react with the deoxidizing agents laid on the bottom, are oxidized and cooled on the walls of the mold, and on the ingot there are surface flaws like captivity and subcortical bubbles. In addition, for a number of steel grades of responsible purpose, there is a danger of changes in the 1M1 composition of the ingot above the limits of GOST due to the elements included in the deoxidizers. The disadvantage of this method is that, during the process of adding solid synthetic slag under the stream, the particles of the latter can be shaken by convective flows to the solidification front of the metal in the mold and become entangled in the crystallizing ingot. Sclake additives under the jet require installation of bulky equipment on the casting platform in order to evenly feed them.

The aim of the invention is to improve the surface quality by eliminating

oxidation of the first portions of the metal and the macrostructure of the ingot.

This is achieved by pouring the slag-forming mixture through the bed; placed in the mold above the level.

The drawing shows one of the devices for implementing the method. The method is carried out as follows. A thin steel sheath 2 with a thickness of 1–2.5 mm is installed on the profitable extension / 2 and fixed to the “edges of the extension 1.

A slag-forming mixture 5 or solid synthetic slag for metal refining is poured into the steel shell 2. The metal stream, emerging from the ladle when the stopper is opened, falls into the shell 2 with slag and melts it. When the slag melts, the last one pops up.

upward, and the liquid metal, due to the larger specific gravity, sinks to the bottom of the shell, heats and burns it.

As further portions of the liquid metal arrive, the hole increases and the entire metal, together with the liquid slag, goes into the mold.

In this case, the pressure of the metal entering the mold is much less than the jet flowing out of the ladle due to a decrease in the ferrostatic pressure and the height of its fall, as a result of which splashings are not formed on the walls of the mold. After the shell has been burned, the stream from the ladle falls into the mold already on a liquid pad consisting of a layer of slag and metal. After the ingot body is filled, the remains of the shell are removed from the profitable extension hook.

The described method allows simultaneously with metal treatment with slag to eliminate oxidation of the first portions of metal flowing from the ladle and entanglement of slag particles in the metal.

After installing the mold with a profitable extension / at last, sheath 2 is installed, made in the form of a crate with bent sides. The shell 2 is made of carbon steel with a thickness of 2 mm. On the two opposite sides of the shell, the holes are made in such a way that the ears of the profitable extension, on which the shell is attached, pass through them.

At the bottom of the shell 2, the slag-forming refining mixture 3 is placed, on the red brick 30,

composition example.

blast slach 30, silicate lump 30, fluorspar 10, in the amount of 3.5 kg / t. The shell 2 can be made with a central hole, which is covered with a metal sheet larger than the hole, and with holes in the upper part of the side faces.

The mixture is supplied with metal from a ladle, first by a slowed down jet, and then with a full opening of the stopper. After the slag is melted, part of it flows through the side openings of the shell into the mold, and most of the metal that burns through the bottom of the shell is poured into the mold. Gases released from metal into the mold are impeded. air suction from the surrounding atmosphere and reduce the likelihood of a secondary oxidation of the jet.

In addition, the absence of the smearing effect of the jet and the rapid filling of the bottom part of the mold eliminates the welding of the ingots.

After the ingot body is filled during the jet break, the shell is removed and placed on the casting platform. The shell may be used several times.

The application of this method of producing an ingot allows for an improvement in the quality of the surface and macrostructure of the ingots in comparison with the known methods of refining metal with solid synthetic slag and slag-forming mixtures.

Claims (2)

1. Authors certificate of the USSR L 505502, cl. B 22 D 7/00, 1974. 2. USSR author's certificate number 508338, cl. On 22 D 27/00, 1974.