SU1133019A1 - Method of obtaining semikilled steel ingots - Google Patents

Abstract

A METHOD FOR OBTAINING SILICON STEEL SLIPS, including the deoxidation of steel in a ladle with ferromanganese and introducing into the mold a solid slag-forming mixture containing steelmaking slag and silicon-containing material, characterized in that, in order to intensify the slagging process and improve the uniformity of properties. metal and the yield of a slag-forming mixture consisting of silicon-containing material and steel-smelting slag in a 1: 1 ratio, is introduced into the ingot mold dispersed simultaneously with steel in the amount of 0.9-1.1 kg / ton of steel to fill half of it, then gradually increase the flow rate of the mixture to 1.8-2.2 kg / ton of steel until 2/3 of the mold is filled and the flow rate is kept constant until the end of its filling.

Description

SAE SO

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The invention relates to meta: glurgy, to the production of ferrous metals, namely to the technology of deoxidation and casting of semi-quiet steel.

The known method of producing semi-quiescent steel is by deoxidation in the ladle with silico-manganese fraction of 2060 mm, entering it when filling 0.2-0.5 of the height of the bucket with a speed of 2-9 t / min in the amount of 0.6-12 kg / t of steel Gu.

However, this technology of deoxidation of semi-quiescent steel in the ladle does not ensure stable oxidation of the metal after deacidification, leads to an additional loss of silico-manganese and an increase in metal loss during rolling (as an additional head cut and surface defects), does not provide a stable oxidation of the metal during development, which leads to to the uneven distribution of the mechanical characteristics of the metal due to the uneven distribution of chemical elements throughout the ingot.

The closest to the invention to the technical essence is a method for producing semi-quiescent steel ingots, including deoxidation in a ladle with ferromanganese and treatment with solid slag-forming mixture in a mold during casting, the mixture being introduced when filling 2/3 of the height. its metal in the amount of 9 kg / t of steel with a gradual increase in consumption to 1.4-1.5 kg / t of steel by the end of the filling of the mold. A mixture consisting of 65% FeSi con. wort slag and fluorspar are introduced in a ratio of 1: 2.0–4, 0: 0.4–0.9 2.

However, the known method has inherent drawbacks — a large amount of deficient fluorspar is consumed. The possibility of silicon loss is created, since there is a release of the fluoride compounds in the form of SiF. In a metal cast by a known method, silicon is not evenly distributed in the bulk of the metal, which leads to non-uniformity of the mechanical properties of the metal over the height of the ingot, since the mixture is injected only when filling 2/3 of the height of the mold, and the jet is 330197

This is limited to a limited depth; this is especially pronounced when the metal in the casting ladle is reduced to half and less. 5 In addition, the introduction of the mixture, starting from 2/3 of the height of the mold, leads to a decrease in the degree of use of the mixture, since part of it remains unmelted even after the floor, 10 times filling the mold with steel. This is especially manifested with an increase in the fraction of the mixture over 1 mm, and the use of a mixture with a fraction of up to 1 mm requires the construction of special

15 departments of preparation of a mixture in explosion-proof design. With the introduction of the slag-forming mixture, it is possible in some cases to not melt it, since the thermality is limited

20 (according to the ratio, you can enter only up to 30% ferrosilicon).

The aim of the invention is to intensify the process of slag formation and increase the uniformity of properties

5 metal and yield.

This goal is achieved by the fact that according to the method for producing semi-quiet steel ingots, including the deoxidation of steel in a ladle with ferromanganese and introduction into

solid slag-forming mixture containing steelmaking slag - and silicon-containing material, a slag-forming mixture consisting of silicon-

containing material and steelmaking slag in a 1: 1 ratio. Injected into the mold dispersed simultaneously with steel in an amount of 0.9-1.1 kg / ton of steel before filling

half of it, then gradually increase the flow rate of the mixture to 1.8-2.2 kg / ton of steel until 2/3 of the mold is filled and the flow rate is kept constant until the end of its filling.

A mixture consumption of less than 0.9 kg / ton of steel does not insulate the metal mirror from secondary oxidation; the introduction of a slag-forming mixture of more than 1.1 kg / ton of steel in the lower part of the mold can lead to contamination of the bottom ingot by slag inclusions.

The proposed method for casting steel makes it possible to increase the rate of formation of the spike, to obtain uniform mechanical properties in the metal over the height of the ingot, and to increase the yield of rolling material. Increase3.

Black mixture consumption from 0.9-1.1 to 1.8-2.2 kg / t of steel is necessary, since starting from the middle of the ingot, a zone of cellular bubbles is formed during crystallization, and a metal column prevents this from occurring below the middle. Therefore, in the upper part, it is necessary to obtain an optimum metal oxide metal, which is achieved by increasing the consumption of the slag mixture.

The consumption of the mixture below 1.8 kg / ton of steel does not provide optimal oxidation of the upper part of the metal, an increase in consumption of more than 2.2 kg / ton of steel may lead to a redistribution of steel, which is also accompanied by additional metal losses.

The implementation of the proposed mode of filling the molds with steel with the mixture makes it possible to eliminate the emergence of cellular honeycombs on the surface or their close proximity to the surface of the crystallized ingot. Bubble-free crust thickness in experimental ingots over 50 mm.

An example. The proposed technology for the deoxidization and casting of steel was tested in the converter shop of a metallurgical plant. Steel melted in 140 t converters, ras330194

ferromanganese was squeezed in the ladle, the consumption of which was 4.5-5.0 kg / t of steel and poured into ingots weighing 8 tons and the slag mixture in the ratio 1: 1 (50% ferrosilicon and 50% converter slag) simultaneously with the metal. The mixture consumption was 0.9-1.1 kg / t of steel to complete the half of the mold, then by gradually increasing the pressure of compressed air from 2 to 3 atm, the consumption of the slag mixture increased to 1.8-2.2 kg / t of steel to completely, not 2/3 of the height of the mold, and then the flow remains constant until the mold is completely filled with steel. Indicators of the effectiveness of the proposed and known methods are shown in the table.

The invention provides a reduction in the fluid gap during casting, since the fractional composition of the mixture is increased to 5 mm (no fluorspar in the mixture), a decrease in the head trimmings by 1.0%, and a decrease in surface defects by 0.25%, since a crust is obtained. 50 mm, uniform distribution of silicon throughout the body of the ingot, ranging from 0.07 to 0.09%.

Claims (1)

METHOD FOR PRODUCING SEMI-FLAT STEEL INGOTS, including deoxidation of steel in a ladle with ferromanganese and introduction of a solid slag-forming mixture containing steelmaking slag and silicon-J containing material, characterized in that, in order to intensify the process of slag formation and increase the uniformity of properties. metal and yield, a slag-forming mixture consisting of a silicon-containing material and steel-smelting slag in a ratio of 1: 1, dispersion is simultaneously introduced into the ingot mold simultaneously with steel in an amount 0.9-1.1 kg / t of steel before filling half of it, then gradually increase the consumption of the mixture to 1.8-2.2 kg / t of steel before filling 2/3 of the mold and leave the flow constant until the end of its filling.