SU779408A1 - Method of low-carbon steel killing - Google Patents

Description

one

The invention relates to ferrous metallurgy, namely, to the production of non-aging steel, intended for the manufacture of cold-rolled sheet with a special complex stretch with an aluminum content of at least 0.02% in steelmaking aggregates, mainly in converters.

A known method for the production of low-carbon non-aging steel for Yu deep drawing, in which metal is smelted in the smelting unit, the metal is released and deoxidized in a steel-teeming ladle to produce boiling steel, and 15 in the process of casting while filling the ingots at levels from 40 -90% of the total height of the ingot loading is attached to aluminum in the form of pellets or rods p. .

The disadvantage of this method is 20 unsatisfactory quality of the surface of the sheet, the presence of heterogeneity

chemical composition and mechanical

properties, which results in special stretching at the development of Lüders line 25 on the surface of finished products from rolled intermediate.

A known method for the production of aging steel for deep drawing with aluminum content in the finished 30

steel 0.05-0.08%, in which metal is smelted in a steel-smelting aggregate, and during output all aluminum necessary for deoxidation and alloying in the amount of 2.0-2.8 kg / t 2 is introduced into the steel.

There is also known a method for producing basic steel, which consists in melting the charge, deoxidizing metal with aluminum in a ladle with simultaneous treatment with slag-forming materials on an acidic basis. Closer contact of the metal with the slag is provided by forced mixing, purging with gases, such as argon Z.

A disadvantage of these methods is the high chemical heterogeneity of the cast metal due to the unstable assimilation of aluminum, and its irregular distribution throughout the volume of aluminum. In addition, the metal deoxidized in this way is characterized by the presence of zones with a high content of aluminate inclusions as a result of aluminum alloying of the peroxidized metal.

The purpose of the invention is to reduce chemical heterogeneity while simultaneously reducing the number of non-metallic inclusions in the cast metal.

 The goal is achieved by introducing aluminum at the bottom of the bucket 10-30% of the stoichiometrically necessary and slag mixture,%: calcium oxide 30-40, fluorspar 30-40 and magnesium 20-40, the rest of the aluminum is introduced after filling the bucket into metal purging process: apirUHOM.

Additive simultaneously with aluminum fluxing materials (CaFj) leads to a dilution of the formed inclusions of alumina, facilitating their Coagil l tsyy in Large logkdudalye stems particles, moreover, the presence in the composition of the slag mixture / lime (CaO) sobmestno with CaFj8 leads to bbrazyvayyy sydybgo izvostkbvogo slag the metal mirror, which captures and keeps up the oxide nonmetallic inclusions. It was shown that if prior to the release of the metal cladding, the magnesium is added, good conditions are created for removing non-metallic inclusions due to the strong gas generation of the oxidation reaction, while the resulting gas bubbles stir the melt and penetrate the weight of the volume of metal, which contributes to enlargement and more complete removal of non-metallic inclusions from metal Content of less than 30% CaO in the mixture does not ensure the production of lime slag with sufficient assimilative ability, an increase in CaO content of more than 40% It is used for the formation of goeth; pulp slag at the expense of undissolved lime. The content of CaF in the mixture depends on the amount of aluminum introduced by the first portion, and in the amount of lime. A CaF2 content of less than 30% does not ensure the formation of a homogeneous liquid slag / slug in the slag mixture of more than 40%. CaF2 does not increase the desired effect. Md content less than 20% does not provide sufficient mixing of the metal bath to remove nonmetallic inclusions, and an increase in Md content of more than 40% can lead to metal emissions from the ladle and a sharp decrease in the durability of the lining of the ladle due to the large thermal effect of the magnesium oxidation reaction.

 Example. In the production of steel 08U in converters1X, a low-carbon semi-product is obtained that is practically the port of chemical composition, C 0.03–0.65; MP 0.10-0.15; S 0.01550, 025j P 0.007-0.010. Before the release of smelting and sieve-pouring ladle, 0.6 t of low-melting mixture of the composition is sown, wt.%: Sab 30; taf 30; Mg 40 and 170 kg of pig aluminum, Momeite of melt production before filling the bucket by 1/4 lead; 0.85 t Metallic manganese. The resulting metal contains 0.010% aluminum. In plants during the argon purge process (argon consumption 50, purge duration 10 min), 650 kg of aluminum in the form of wire is introduced into the metal. Get the steel of the following composition,%: C 0.05; Mp 0.26; S 0.014; P 0.010; Si 0.01; A 0.067

PRI mme R 2. Before launching the melting, 1.5 tons of low-melting mixture of the composition, wt.%: CaO 40; CaF240, Mg 20 and 350 kg of aluminum. During the discharge of the pore filling smelting 1/3 of the ladle, 0.80 tons of manganese metal was introduced. The resulting metal contains 0,019% aluminum. In installations in an argon purge process (argon 50 operation, purge duration 8 min), 440 kg of a Upomini are introduced into the metal in the form of a wire. Get the steel of the following composition,%: C 0.04; Mp 0.23; S 0.012; P 0, C09; Si 0.01; A | 0.065.

PRI mme R 3. Before releasing the smelting, 0.96 tons of low-melting slag mixture of the composition, wt.%: CaO 35, Sar2 35 Md 30 and 250 kg of plastic: aluminum are placed in the steel-teeming ladle. During the melt production after filling 1/3 of the ladle, 0.82 tons of manganese metal was introduced. Get the aluminum content in the metal 0,016%. In facilities during the arson purge process (argon consumption 50, purge duration 9 min), c. metal 550 kg of aluminum in the form of wire. Steel is obtained from the following composition,%: C 0.04, Mp 0.24, S 0.016, P 0.008, Si 0.01, A1 0.066.

When Conducting pilot steel 08U melts, it was established that the optimum is the technology carried out according to the proposed method, which allows improving the quality of the metal, reducing the number of non-metallic inclusions and reducing the scrap of the finished metal.

The results of the heats, carried out by the proposed and known technology are shown in the table.

The consumption of slag mixture, depending on the consumption of aluminum for preliminary deoxidation, is in the range of 2–5 kg / t of steel. Bringing the mixture to the ladle of less than 2 kg / ton of steel does not ensure proper slagging and removal of the resulting aluminate inclusions, and its consumption of more than 5 kg / ton of steel is impractical. The production of residual aluminum in the semiconductor less than 0.010% does not ensure the production of calm steel before the final alloying of the metal in the argon installation, and therefore, in the ladle 5, the segregation of elements is highly developed, and the same in the intermediate product is more than 0.020% aluminum. aluminate inclusions and, consequently, the uneven distribution of aluminum by volume of the bucket. The best should be considered to receive a semi-product with an aluminum content of 0.0150, 018%.

As can be seen from the table, the deoxidation of steel for a cold-rolled non-aging auto sheet by the proposed method improves the quality of the metal by reducing the content of non-metallic inclusions and more uniform distribution of aluminum and improves the mechanical properties of the cold-rolled sheet.

Suggested 2.0 10 5.0 30 3.2 20

Known

Claims (3)

1. Authors certificate of the USSR 443918, cl. C 21 S 7/06, 1975. 2.Povolrtsky D.Ya. Aluminum 6 structural steel. M., Metallurgists, 1970, pp.159-166. 3. Authors certificate of the USSR 9 521320, -kl. C 21 C 7/00, 1974.