SU1470778A1 - Method of treating steel - Google Patents

Abstract

The invention relates to methods for the deoxidation and modification of steel and can be used for secondary treatment. The purpose of the invention is to increase the ductility and toughness of steel. The method includes the following operations: deoxidation with ferrosilicon and silicomanganese in the furnace

preliminary ladle deoxidation of 0.15% aluminum and 0.2% silicocalcium when the ladle is filled to 0.2 of its height

final bucket deoxidation of 0.5-5 kg / t of a mixture of aluminum and slag of aluminum alloy production with a ratio of components 1: (0.1 ... 1) when filling a bucket 0.8-0.9 of its height

modification of 0.15% ferroceri, which is introduced into the neutral gas supply zone with a flow rate of 0.005 m ³ / min with a modifier feed rate of 0.02-0.15 m / s. The method allows for the assimilation of the modifier 24 ... 39% and the content of oxides 0.009 ... 0.014% to have δ = 28.7-35.1%

ψ-58.6-63.8%

KCV _- 60 = 0.68-0.81 mJ / m ² . 1 tab.

Description

one

This invention relates to metallurgy and can be used during secondary treatment.

The purpose of the invention is to increase the ductility and toughness of steel.

When creating the invention, the following data obtained during the experiments were used.

The introduction of a mixture of aluminum and slag production of aluminum alloys into the ladle prior to the release of the main amount of steel slag (when the ladle is filled with metal by 0.8-0.9 of its height) allows increasing the interaction time of the reagents and the complete deoxidation of the steelmaking slag. In addition, aluminum partially dissolves in the upper layers of the metal, which, together with the presence of a layer of well deoxidized slag, prevents the secondary oxidation of the metal and za. its oxide inclusions when treated with neutral gas. At the same time, the concentration of dissolved and bound oxygen decreases, which contributes to the improvement of the quality of steel from the degree of absorption of the modifier.

Slag production of aluminum alloys contains, wt%: A1 5-25; AlgOg 25-50, SiOj, 5-15; ZnO 1-4; (KCl + NaCl) 5-35. Inclusions of aluminum in A1-slag help to increase the degree of acidity and refining abilityN il

ABOUT

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tee steelmaking nshaka and improve the quality of steel.

The viscosity and melting temperature of the steelmaking slag does not increase, the resulting deoxidized slag remains ideally sub-nominal due to the presence of potassium and sodium chlorides in the A1-slag composition, the addition of which significantly reduces the viscosity of calc-silicate slags.

The alumina additive in the composition of A1-slag acts in a similar way, which is also smooth for steelmaking slags.

The out-of-furnace treatment of the steel under liquid slurry slag contributes to an increase in the quality of the metal due to a more complete removal of non-metallic inclusions of dissolved oxygen into the slag phase. The latter contributes to the destruction of the carbon monoxide and an increase in the degree of assimilation of the modifier.

The introduction of a modifier into the zone of supplying a neutral gas, characterized by minimal oxygen activity, contributes to the reduction of the corrosion stress of the modifier and, accordingly, to a decrease in the number of oxide inclusions in the metal. The quality of the metal and the assimilation of the modifier increase.

The addition of a mixture of aluminum and A1-slag when Koania is filled with less than OyS metal of its height is impractical, since the aluminum from the mixture has time to be dissolved in a significant amount of metal mixed with neutral gas. This leads to an increase in its concentration in the steel above the grade.

Entering the specified -mixture when filling a bucket more than 0.9 in its height is also undesirable5 because it does not fully complete the processes of heating and melting the components of the mixture by the time the main amount of slag has gone. At the same time, the completeness of slag deacidification decreases, which leads to the contamination of the metal with oxide inclusions and oxygen during the mixing of the melt with neutral gas, with the sniffing of the flatBa of the metal and absorption of the modifier.

The addition of a mixture of aluminum and A1-slag in an amount of less than 0.5 kg / t of steel does not provide a sufficiently complete deoxidation of steelmaking slag and leads to contamination of the steel with oxygen and oxides, a decrease in the quality of steel and the absorption of the modifier.

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five

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35

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The addition of this mixture in the amount of more than 5.0 kg / ton of steel is impractical because of an increase in the aluminum content in the steel above the grade level and an increase in the cost of the treatment process.

A decrease in the slag production ratio of aluminum alloys to the amount of aluminum in the mixture less than 0, 1 leads to sushi; a natural increase in the viscosity of the steelmaking slag during its deoxidation and deterioration of its refining: their protective properties. At the same time, the quality of steel deteriorates due to its mechanical properties, contamination by nonmetallic inclusions, and the absorption of the modifier decreases.

An increase in the ratio of the amount of A1-slag to the amount of aluminum by more than one unit leads to a strong razhering of steel-smelting slag with chlorides, deterioration of the durability of the lining of the ladle and contamination of the metal with exogenous inclusions. The quality of the steel is significantly deteriorated.

Immersion of the modifier into the metal in the zone of supply of neutral gas with speeds less than 0.02 m / s leads to a decrease in the degree of assimilation and uniform distribution of the modifier over the volume of the metal, deterioration of its quality, since at low speeds the melting of the modifier (or the container with it) ) and floating in liquid steel occurs in its upper horizons.

Dipping the modifier with speeds greater than 0.15 m / s is impractical because of possible damage to the input device, detachment of the modifier from the rammers, etc. As a result, the additives are not evenly distributed over the bucket volume, the quality of steel and the modifier absorption are reduced.

The processing parameters and properties after normalization of steel are listed in the table (according to the known method 28.7-35.1%, (58.6-63.8%, KCV.60 0.68-0.8 MJ / m2, P1; 25-26.17, (.52.5-56.3%, 0.45-0.61 MJ / mM

The 20G1FL steels are melted in an EAST-0.16 furnace with a magnesite crucible and a plasma extension. Deoxidation and doping with ferrosilicon and silicone manganese are carried out in a furnace, the final deoxidation with aluminum (0.15%) and

silicocalcium (.0.20%) is carried out in a ladle heated to 800-900 ° C when filled to a height of 0.2.

one

After filling the bucket 0.8–0.9 of its height, a mixture of aluminum section and A1-slag is introduced onto the metal surface,%: A1 16.3; , 36.2; SiO 6.7; ZnO 0.3; ZKCl and NaCl 40.5, with a ratio of ingredients 1: (0.1-1). Then, 0.15% ferrocerium is introduced into the metal, which is fixed in the lower part of the immersion tuyere to supply argon.

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Claims (1)

The data in the table show that, in comparison with the known, the proposed method allows to increase the reliability of castings. Invention Formula A method of treating steel, which includes the introduction of aluminum and the ones that are melted at the release of the melt into the ladle, the introduction of a modifier and purging with a neutral gas at the end of the release, about t l and -; due to the fact that, in order to increase the plasticity and viscosity, into the ladle by filling with melt The lance is immersed together with the modifier b0.8-0.9 of its height, additionally at a speed of 0.02-0.15 m / m when the slag of secondary production of argon 0.005 is produced during the min., While the slag is introduced into the mixture 3 min. After completing the prod with aluminum in a ratio of (0.1-1): 1, duvki and steel modification at the consumption of a mixture of 0.5-5.0 kg / t steel, poured into sand molds and get a 20a modifier introduced at a rate of samples, which are then subjected to a nor-0.02-0.15 m / s in the zone of neutralizing malaria. foot gas. The data in the table show that, in comparison with the known, the proposed method allows to increase the reliability of castings. Invention Formula A method of treating steel, which includes the introduction of aluminum and the ones that are melted at the release of the melt into the ladle, the introduction of a modifier and purging with a neutral gas at the end of the release, about t l and -; due to the fact that, in order to increase the plasticity and viscosity, into the ladle by filling with melt