SU1199441A1 - Method of modifying steel with rare=earth elements in open mould of continuous casting machine - Google Patents

Abstract

1. METHOD OF MODIFICATION OF STEEL OF RARE-EARTH METALS IN A CRYSTALIZER OF A CONTINUOUS CASTING MACHINE, including an uninterrupted supply of slag-forming mixture and rare-earth metals or their alloys to the mold on the mirror of the metal. characterized in that, in order to improve the quality of the continuous-cast billet by increasing the uniformity of distribution of rare-earth swords allah over its cross section, a ptak mixture containing 10 is applied to the surface of the metal mirror, equal to 0.15-0.30 in its total area, around the perimeter of the mold -15% of rare-earth metals in the amount of 15-30% of the total amount of rare-earth metals injected, the rest of the mirror’s surface is supplied with a slag mixture without rare-earth metals, and the rest of the amount is introduced in the center i of the mold rare earth metals. (L 2. The method according to claim 1, characterized in that rare earth metals are introduced in the form of a powder tape in the center of the mold.

Description

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The invention relates to metallurgy, in particular to steelmaking and can be used in the continuous casting of metals.

The purpose of the invention is to improve the quality of a continuously cast billet by increasing the uniform distribution of rare earth metals over its cross section,

PRI meri The smelting of low-alloyed steel (Type 17G1SU and 09G2S of responsible purpose is made in oxygen converters with a capacity of .50 tons. The steel is cast by curved-type continuous casting machines on billets with a section of 250-300x1550-1900 mm.

When casting billets with a section of 250x1550 mm, only 0.6 kg / t of rare earth steel was introduced into the liquid metal. The average casting speed is 0.7 m / min. Using a special metering device, a slag mixture consisting of cement, nepheline concentrate, fluorine fiber, silicate lump, amorphous graphite and containing 10-15% REM is continuously fed along the perimeter of the crystallizer onto the metal mirror surface equal to 0.15 of its total area the amount of 15% of the total input of rare-earth metals (0.09 kg / t of steel). At the same time, the same slag mixture without rare-earth metals is fed to the rest of the mirror surface and the rest of the rare-earth metals with a powder tape (0.51 kg / ton of steel) is introduced with the aid of a tribripper on the mold center.

For comparison, on an adjacent stream of a continuous casting machine, the steel was modified by a known method, i.e. input of rare-earth metals with a slag mixture to the entire metal mirror in the mold. The amount of REM in the slag mixture is 25-30%. Rated consumption of rare-earth metals per ton of steel is 0, 30 kg.

When casting with a section of 300x1900 mm, the techniques and sequence of technological operations are carried out

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the same as when casting with a section of 250x1550 mm7. Along the perimeter of the mold serves a slag mixture containing 10-15% of rare-earth metals, on

5 surface of the metal mirror equal to 0.30 of its total area in the amount of 30% of the total number of input REM (0.60 kg / t of steel),. 0.18 kg / t steel. In the center of the mold

0 enter the rest of the REM

with powder tape - 0.42 kg / t steel.

Test data of the known and proposed methods of modification are given in Table 1 and 2,

From the data obtained it can be seen that when modifying the steel of the proposed method, cerium is evenly distributed throughout the section of the workpiece,

0 The impact viscosity on transverse samples rises against the known modifying method by 20%. At the same time, the Anisotropy decreases and is 0.70-0.78 against 0.50-0.60.

5 Sorting of metal by mechanical properties when modifying steel using the proposed method is 1.5% less, since the values of impact toughness on transverse samples of rolled steel are higher and more stable along the entire length

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Due to the fact that the chemical composition of the slag melt in the mold

, the casting process does not change

(slag thickening does not occur and the temperature of its melting does not increase, as when using the known modification method), it becomes

Q it is possible to introduce higher concentrations of rare-earth metals in steel in the casting process (depending on the concentration of sulfur in the metal), to obtain a uniform distribution of rare-earth

e elements over the section of the workpiece, steel: strong and higher mechanical properties,

The proposed method reduces the sorting of sheet products by 1.5% and converts to low-grade steel, t, e, to obtain higher and more stable values of toughness on transverse samples of low-alloy steel.

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Claims (2)

1. METHOD FOR MODIFICATION OF STEEL RARE-EARTH METALS IN THE CRYSTALIZER OF CONTINUOUS CASTING MACHINE, which includes the continuous supply of slag-forming mixture and rare-earth metals or their alloys to the mold on the mirror, revealing that, in order to improve the quality of the continuously cast billet by increasing the uniformity of the distribution of rare-earth metals over its cross-section, onto the surface of the metal mirror equal to 0.15-0.30 of its total area, along the perimeter of the mold serves a slag mixture containing 10-15% of rare earth metals in an amount of 15-30% of the total amount of input p of rare earth metals, a slag mixture without rare earth metals is fed to the remaining part of the mirror surface, and the remaining amount of rare earth metals is introduced in the center of the crystallizer. 2. The method of pop, 1, characterized in that in the center of the mold rare earth metals are introduced in the form of a powder tape.