SU582053A1 - Slag-forming mixture for steel casting - Google Patents

Description

(54) SLAG-FORMING MIXTURE FOR CASTING STEEL

one

The invention relates to the field of metallurgy, namely to slag-forming mixtures for protection of the metal mirror in a mold or mold when casting steel.

Known slag-forming mixture for casting steel, deoxidized with aluminum in the amount of not less than 0.6 kg / t, containing powdered graphite and fluoride mat in the following ratio of components, weight. %: Powdered graphite 60-79

Fluorspar21-40

Due to the partial fluxing of solid alumina inclusions, the ingot intensity of the ingot is reduced by cracks.

However, the quality of the metal remains rather low, since the ingots are struck by irodol cracks.

This is explained by the fact that the number of inclusions of LLOZ, which come up from liquid metal and coming in with graphite ash is so great that the volume of the silt cloth, but with the mixture, is not enough to flux the entire amount of AlO3. In addition, the melting temperature of the resulting mixture is very small (up to 1400-1500 ° C), and the slag on the meniscus is in solid or iol-solid state. As a result, clean or fluxed inclusions AIjOs enter the gap between the walls of the crystallizer and the ingot crust.

solid or iolhtat condition, which causes quite a BbicoKjw impact of ingots by longitudinal cracks.

Also known is a slag-forming mixture for steel casting, which includes the following components, wt. %: fluorspar 5-20; the slag containing SiO2 and CaO, (for example, the convectional slag of vanadium pig iron into intermediate) is 10–20 and fine graphite is mineral.

The disadvantage of the known mixture is that it contains heavy vanadium sclac, which leads to the delamination of the finished mixture: the content of the wahiadium sclac in the upper layers of the mixture is less than the average, and in the inhrinal layers of the mixture - more than the average. The heterogeneity of the composition of the mixture when it is irimeeeeei can cause a higher quality and surface of the mixture.

The aim of the invention is to improve the quality of the ingot.

This is achieved by introducing blast furnace slag into the mixture at the following ratio of components, (wt.%):

Powdered graphite 30-60

Fluorspar10-20

Blast furnace slag30-50

Improving the quality of the ingot is achieved due to a more complete fluxing of the hot melt composites of graphite ash and the prevention of

their pelletizing. This is explained by the fact that the minimum temperature of the melting of slag systems, including alumina, is the presence of the system - SiO2 - CaO of eutectic composition. With the introduction of blast furnace slag, silicon dioxide SiOa, calcium oxide CaO is introduced into the mixture. As a result of this, when inclusions from a liquid metal on the meniscus emerge, slag is formed, consisting practically of the components of АООз, SiO2 and (Са04 Сар2) - composition, close to eutectic, with a melting point of about 1260-1300 ° C. This slag on the meniscus is in liquid state, and, falling into the gap between the crust of the ingot

Claims (1)

Invention Formula Slag-forming mixture for steel casting, including powdered graphite, fluorite material and slag containing 5102I CaO, characterized in that and the walls of the mold, plays the role of a lubricant and contributes to the reduction of the churning of the ingot. A content of less than 30% in the proposed blast-shlak mixture does not give a positive effect, since the refractory components (ABO3 and others) ofl: They do not fully fit. A content of more than 50% in the proposed blast furnace slak mixture results in the formation of large lumps of slag on the meniscus, which leads to an impulse of the workpiece and the ingot contamination by nonmetallic inclusions. This also dramatically increases the flow rate of the mixture. In tab. examples of the composition of the mixture and the results of their testing are presented. improving the quality of the ingot, blast furnace slag was introduced into the mixture at the following ratio of components, weight. %: Powdered graphite30-60 Navigator Shchpat10-20 Domain Schlak30-50