SU1761378A1 - Slag-forming material for continuous casting of aluminium- containing steels - Google Patents

Abstract

Use: improving the quality of uninterrupted casting. The invention: a slag-forming material, including oxides of silicon, calcium, sodium, boron, barium, zirconium and fluorine, additionally contains graphite in the following ratio of ingredients, wt.%: Calcium oxide 20-32; sodium oxide 6-9: boron oxide 6-9; barium oxide 6-12; zirconium oxide 6-9; fluorine 5-10; graphite 4-10; silicon oxide the rest, 1 tab.

Description

The invention relates to ferrous metallurgy, in particular to slag-forming materials, and can be used in the continuous casting of steel.

An effective way to protect steel from secondary oxidation and to improve the quality of a continuously cast metal is to use slag-forming materials supplied to the metal mirror in the mold.

Known slag-forming material to protect the liquid metal mirror containing nepheline, a carbon-containing substance, silicate lump, calcium fluoride, Portland cement, which forms the slag composition,% by weight: SI02 - 25-35; CaO - 25-35; А120з - 8-12; Na20 - 6-8; F 8-10; C - 8-12. This slag-forming material is used in a number of enterprises of ferrous metallurgy, in particular, at the Cherepovets Metallurgical Plant, however, when casting aluminum-containing steels, it does not ensure the production of high-quality, continuous castings.

Slag-forming material is known for feeding into the crystallizer of the UN PC, which in the molten state has the composition (% by mass): Si02 - 15-60; CaO - 5-40: AlzOa + TI02 - up to 5; BaO - 5-70; C - 2-5.

The disadvantage of this slag-forming material is that it does not provide high quality continuously cast billets from aluminum-containing steels.

The closest to the claimed is a slag-forming material containing,% by weight: SI02-25-45; CaO-20-41; ABOZ - 0-8; MDO - 0-10; BaO - 0-5; Na20 - 10-30; K20-0.5-6.0; SrO-0-5; B203-0-10; TiO2 - 0-5: Zr02 - 0-3; F - 0-16. A disadvantage of the known slag-forming material is the insufficient quality of continuously cast billets produced by

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its use for continuous casting of aluminum-containing steels.

The purpose of the invention is to improve the quality of continuously cast billets.

This goal is achieved by the fact that slag-forming material for continuous casting of aluminum-containing steels, including oxides of silicon, calcium, sodium, boron, barium, zirconium and fluorine, additionally contains graphite in the following ratio of components,% by mass:

CaO20-32

Ma206-9

B20z6-9

BaO6-12

Zr026-9

F5-10

graphite 4-10

SI02

A comparative analysis of the known technical solutions and the claimed one did not reveal similar signs, therefore the claimed slag-forming material has significant differences.

The introduction of graphite into the slag-forming material controls the rate of melting. When using the proposed slag-forming material in the claimed quantitative ratio of the components, an increase in the quality of a continuously cast billet is achieved. In the case of using a slag-forming material with a component content beyond the specified boundary limits, the quality of the continuous cast billet deteriorates.

The preparation of the proposed slag-forming material is no different from that known and consists in melting the components with the exception of graphite, grinding the resulting alloy to particle sizes less than 1 mm and mixing it with graphite.

The proposed and well-known slag-forming materials were tested in continuous casting of 22 HU steel in

conditions of the Cherepovets Metallurgical Plant on a two-strand UNRS in a size of 250x1440 mm. The temperature of the metal during casting is about 1550 ° C. Slag-forming material was poured into the mold and filled in the casting process to ensure full protection of the metal mirror. The thickness of the layer of slag-forming material was 5-10 mm, its consumption was about 1 kg / t of steel.

The test results are presented in the table.

As can be seen from the table, when using a known slag-forming material, the surface quality of continuous slabs was unsatisfactory. The metal surface is affected by slag inclusions and cracks.

By using the proposed slag-forming material, an increase in the surface quality of continuous slabs is achieved by reducing the sorting by defect Fracture and reducing slag inclusions.

These data indicate the validity of the selected limits of the content of the components of the slag-forming material.

Claims (1)

Invention Formula Slag-forming material for continuous casting of aluminum-containing steels, including oxides of silicon, calcium, sodium, boron, barium, zirconium and fluorine, characterized in that, in order to improve the quality of continuous casting, it also contains graphite in the following ratio of ingredients, wt.%: calcium oxide sodium oxide boron oxide barium oxide zirconium fluorine graphite silicon oxide 20-32 6-9 6-9 6-12 6-9 5-10 4-10 rest Table continuation