RU2241778C1 - Iron-silicium-aluminum-based addition alloy - Google Patents

Abstract

FIELD: metallurgy, in particular complex alloy for deoxidation and doping of steel and cast iron.

SUBSTANCE: claimed addition alloy contains (mass %): iron 25-50; aluminum and silicium 75-50 in Al/Si ratio of (1:1)-(3:2). Claimed Al/Si ratio is the most preferable to produce high quality ingots due to more deep steel deoxidation with aluminum and sufficient steel doping with silicium.

EFFECT: increased coefficient of aluminum utilization; method for producing of silicon steel with improved efficiency.

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Description

The invention relates to the field of metallurgy, in particular to the development of complex alloys for deoxidation and alloying of steel and cast iron.

Known modifier for cast iron containing 23-25% Al, 5-7% Si, the rest is Fe. Processing liquid cast iron with a modifier of the specified composition allows to increase the mechanical properties of cast iron [1].

Known deoxidizer - ferosilicon, which is used for the treatment of boiling steel [2]. To process the ingots of boiling steel in the mold, ferro-silicoaluminium in granular form after 0.5-1.5 minutes after filling the mold is placed on the ingot mirror.

The closest analogue of the invention is the master alloy containing 8-25% Al, 55-70% Si, the rest is Fe [3]. Get a ligature of the specified composition as follows: the required amount of aluminum and low-melting flux consisting of cryolite and lime in a ratio of 4: 1 is loaded into the bucket, and then ferrosilicon is poured into the bucket. The flux mixture and aluminum are melted due to the physical heat of the melt and the heat of formation of iron aluminides. During aging in a ladle under a layer of slag, the ligature is aligned in composition. If the ligature contains more than 20% Al, the ingot aluminum is pre-melted in a ladle with a gas burner under a flux layer.

The proposed iron-silicon-aluminum alloy is a three-component alloy that contains components in the following ratio, wt.%: Iron - 25-50; aluminum and silicon (in total) - 75-50, while the ratio of aluminum to silicon is from 1: 1 to 3: 2.

The objectives of the invention are:

improving the quality of ingots;

increased utilization of aluminum;

increasing the economic efficiency of using the claimed ligature.

The tasks are achieved as a result of obtaining the following technical results when implementing the claimed ligature:

a deeper degree of deoxidation of steel;

increase in alloy density;

reduction of out-of-furnace treatment time due to the combination of aluminum deoxidation and silicon alloying operations.

Technical results are achieved by the fact that the claimed ligature contains components in the following ratio, wt.%: Iron - 25-50; aluminum and silicon (in total) - 75-50, while the ratio of aluminum to silicon is from 1: 1 to 3: 2.

The proposed amount of iron from 25 to 50 wt.% Determines the alloy of high density to increase the utilization of aluminum. The usual deoxidizer - aluminum has a density of from 2.6 to 2.7 g / cm ³ , so a significant part of the aluminum is located above the surface of liquid steel and is oxidized by atmospheric oxygen. So of 100 kg of aluminum used in deoxidation, only 17-20 kg is actually spent to remove oxygen dissolved in the metal, the remaining 80-83 kg burn on the surface of the steel, interacting with atmospheric oxygen, which is due to the low density of aluminum compared to steel, so as an effective part of the deoxidizer is only the one that is immersed in the melt.

An increase in the density of the ligature and its approximation to the density of steel contributes to a greater penetration of the ligature into the melt. So, with an increase in iron content up to 50 wt.%, The density of the ligature increases to 5.0 g / cm ³ and the percentage of assimilation of aluminum increases by 3 times. Therefore, to obtain the same deoxidation effect, it will no longer be necessary to 100 kg of aluminum, but only 33 kg, which is part of the ligature. Thus, the content in the claimed ligature of iron from 25 to 50 wt.% Can significantly increase the utilization of aluminum.

The aluminum and silicon components of the proposed ligature, available in the prototype alloy (3), basically perform the same function as in the known prototype alloy. However, the ratio of aluminum to silicon in the proposed alloy is significantly different from the alloy of the prototype.

The choice of the boundary limits of the content of aluminum and silicon in the proposed ligature is due to the optimal required temperature for its melting, as well as acceptable standards for oxygen and silicon in steel.

The increase in aluminum content in the proposed ligature, firstly, increases its deoxidizing ability, and secondly, reduces its melting temperature by two hundred degrees compared to the prototype alloy, which facilitates the application of the proposed ligature from a technological point of view. Due to the increased aluminum content in the claimed ligature, the required deoxidation of steel is ensured, and alloying with silicon. As practice has shown, the claimed ratio of aluminum and silicon from 1: 1 to 3: 2 is the most optimal for obtaining high-quality ingots due to deeper deoxidation of steel with aluminum and the necessary alloying of steel with silicon. By combining the operations of steel deoxidation with aluminum and its alloying with silicon, the time of out-of-furnace treatment of steel is reduced, which ensures an increase in the economic efficiency of the application of the claimed ligature. In addition, it is assumed that the cost of the declared ligature will be one and a half times lower than the traditional, aluminum, deoxidant AB 87.

The claimed ligature is obtained in a high-frequency induction steelmaking furnace from all types of aluminum and silicon-aluminum waste with a mass fraction of the metal part of aluminum of at least 5% or in an AC arc furnace of any type from aluminum and silicon oxides (bauxite, alunite, nepheline, poor aluminum slag, etc. .) with the addition of steel scrap or iron oxide with an iron oxide content of at least 50 wt.%. The smelting of the mixture, consisting of aluminum and aluminum-silicon waste (or oxides of aluminum and silicon) and steel scrap (or iron oxide), is carried out in a reducing carbon medium. To obtain the required amount of silicon in the claimed ligature, sand (SiO ₂ ) is added to the charge. A reducing environment is created by adding carbon-containing materials: coal of various grades, anthracite, graphite battle with a carbon content of at least 50 wt.%. The calculation of the charge for melting is carried out from the calculation of the iron content in the alloy from 25 to 50 wt.%. The calculation of the carbon-containing material is performed from the calculation of the reduction of iron from iron oxide, taking into account the required excess in carbon. The reducing atmosphere of the smelting of the charge allows to reduce aluminum fumes up to 1-2%. The ligature density is from 3.0 to 5.0 g / cm ³ . Impurities that may be in the alloy do not exceed the values specified by GOST 295-98.

An example of obtaining the claimed ligature.

As the charge materials for the production of 1000 kg of iron-silicon-aluminum alloys with a content, wt.%: Fe - 50; Al - 30; Si - 20, used poor aluminum slag with an Al ₂ O ₃ content of 58%; SiO ₂ - 9%; Fe ₂ O ₃ - 8% in the amount of 1000 kg; sand (SiO ₂ ) with a content of Fe ₂ O ₃ - 2% in an amount of 330 kg; steel shavings in the amount of 440 kg; grade G coal with an ash content of 17% and an Al ₂ O ₃ content of 5% in ash, 5% SiO ₂ in an amount of 520 kg, taking into account a 20% excess.

The initial charge materials in the indicated amounts were mixed and pressed onto a roller press with a specific pressing force of 1.5 t / cm ² without the use of a binder. The volume of one briquette is 65 cm ³ .

Melting was carried out in an open-type arc ore reduction furnace. Briquettes fell asleep and melted for 1 h 25 min. Then it was held for 30 min and the resulting alloy was poured through the lower notch at a temperature of 1540 ° C into molds. Then, through the lower notch, slag was poured into slag.

The use of iron-silicon-aluminum alloys of the claimed composition can significantly increase the utilization of aluminum by increasing the density of the alloy. The claimed amount of aluminum and silicon is 75-50 wt.% And the ratio of aluminum and silicon from 1: 1 to 3: 2 is the most optimal for ensuring high-quality ingots due to deeper deoxidation of steel with aluminum and sufficient alloying of steel with silicon. At the same time, it is possible to combine the operations of steel deoxidation with aluminum and its alloying with silicon, which allows to reduce the time of out-of-furnace processing of steel, and thereby to increase the economic efficiency of obtaining silicon steel grades.

Sources of information

1. A.S. USSR No. 422787, C 22 from 35/00, priority 04/04/1972

2. A.S. USSR No. 418530, C 21 from 35/00, priority dated 11/08/1972

3. A.S. USSR No. 268659, С 22 с 35/00, priority from 11/28/1969

Claims (1)

Iron-silicon-aluminum ligature containing iron, silicon and aluminum, characterized in that it contains components in the following ratio, wt.%: Iron 25-50 Aluminum and silicon 75-50 the ratio of aluminum to silicon is from 1: 1 to 3: 2.