SU1763512A1 - Steel and method of its production - Google Patents

Abstract

The essence of the invention: the steel additionally contains hydrogen, active oxygen, acid-soluble aluminum, titanium in the following ratio of components, May. %: carbon 0.03-1.5; manganese 0.05-2.5; silicon 0.001-0.11; chromium 0.01-0.40; Nickel 0.01-0.40; copper 0.01-0.40; nitrogen 0.001-0.030; hydrogen 0.0001-0.0008, oxygen active 0.0001-0.004, aluminum acid-soluble 0.005-0.050; titanium 0.001-0.050, iron - the rest. The method includes the smelting of metal, release into the ladle and deoxidation with manganese and silicon-containing ferroalloys. The steel is additionally deoxidized with aluminum and titanium to obtain an active oxygen content below the equilibrium with carbon at atmospheric pressure and the steel crystallization temperature. The minimum allowable content of aluminum and titanium is determined from the dependence Z (AI + 0.4 Ti) 235 (0.0004 + 0.0013 C / C) -1.26 N - 0.007 N. The use of the proposed steel will increase the density and ductility of cast steel and the quality of the ingots. 2 sec. f-ly, 3 tab. Yo

Description

The invention relates to ferrous metallurgy, in particular, to the composition of steel primarily for casting into molds and on continuous casting machines.

The purpose of the invention is to increase the density and relative elongation and plasticity of the cast metal.

The steel of the proposed and known compositions is melted in a laboratory converter with a capacity of 1.5 tons. The steel is siphoned onto 800 kg ingots. During casting, samples are taken of liquid steel, in which the content of carbon, manganese, silicon, chromium, nickel, copper, nitrogen, acid-soluble aluminum and titanium is determined. To determine the hydrogen content of the liquid steel, it is cast into a massive test probe (providing accelerated

crystallization of the liquid metal) finger sample, which is quenched in water and then stored in dry carbon dioxide until analysis. The analysis is carried out on a specialized Leko instrument. The content of active oxygen in the liquid steel in the mold is determined using a device for controlling the oxidation of steel of the UKOS-1 type. From the obtained ingots, a surface layer of metal 10 mm thick is cut out and samples of cubic shape (for density measurement) and flat samples (for tensile tests) are made. The density of the metal is determined by the ratio of the mass of the sample to its volume. The ductility of the metal is evaluated by the magnitude of the relative elongation of the gaps during tensile tests.

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The chemical composition of the steel proposed and known compositions and the results of tests of the metal are given in table. 1 and 2.

The essence of the method is as follows. To increase the density and plasticity of the cast metal, it is necessary to eliminate the formation of gas during the crystallization of liquid steel, in which carbon monoxide, hydrogen and nitrogen are involved. Since the total pressure of the emitted gases should not exceed atmospheric, the partial pressure of carbon monoxide should be lower than atmospheric and the lower the content of hydrogen and nitrogen in liquid steel. A decrease in the carbon monoxide partial pressure is provided by introducing aluminum and titanium into molten steel to obtain active oxygen concentrations below those in equilibrium with carbon at atmospheric pressure. It was established experimentally that the minimum allowable content of aluminum and titanium can be determined from the dependence

2.35-

Z (AI + 0,4Ti)

0.0004 + 0.0013С

-1.26Н -0.0074N

where C, H, N, Al, Ti - the content of carbon, hydrogen, nitrogen, aluminum soluble and titanium, respectively, in liquid steel,%. Examples of the method. The proposed method for the production of low-silicon liquid steel is used when conducting the experimental heats listed in table. 1. In a 1.5 t converter, intermediate product is melted, which is poured into a casting ladle. During the release process from the unit, the metal is doped in the ladle to obtain the required contents of chromium, nickel, copper, nitrogen, and also deoxidized with manganese, silicon, aluminum and titanium. At the same time, to calculate the consumption of recycled aluminum and ferrotitanium, the minimum allowable content of soluble aluminum and titanium is determined according to the proposed dependence, taking into account the contents of carbon, hydrogen and nitrogen in the liquid steel. The carbon content in the finished steel is calculated from the data on its residual content in the intermediate product, taking into account the input of this element into the steel by alloying and deoxidizing additives. The content of hydrogen and nitrogen is taken according to the results of the experimental determination of their content in the intermediate product before it is released from the converter. The content of active oxygen in the finished molten steel in the mold is determined by the oxidation monitor of the steel type UKOS-1. The calculation of the contents of active oxygen, equilibrium with carbon at atmospheric pressure and

steel crystallization temperature, produced by known thermodynamic data. Steel is poured into moldable molds with a warmed head.

Data on the chemical composition of low-silicon liquid steel and the method of its production are given in table. 1 and 3, and the test results - in table. 2. The obtained results show that the content of aluminum and titanium in the finished low-silicon liquid steel is higher than the minimum allowable values determined by the proposed dependence. At the same time, the content of active oxygen in such a steel was lower than equilibrium with carbon at atmospheric pressure and the steel crystallization temperature. Cast metal from such steel has a higher density and ductility in the cortical zone than metal from known steel.

The application of the proposed method for the production of low-silicon liquid steel allows to increase the density and ductility of the cast metal.

Claims (2)

1. Steel containing carbon, manganese, silicon, chromium, nickel, copper, nitrogen and iron, characterized in that, in order to increase the density and relative elongation, it additionally contains hydrogen, active oxygen, acid-soluble aluminum and titanium the ratio of components, May. %: Carbon 0.03-1.5 5 Manganese 0.05-2.5 Silicon0.001-0.11 Chrome 0,01-0,40 Nickel0.01-0.40 Copper 0.01-0.40 0 Nitrogen0,001-0,030 Hydrogen0,0001-0,0008 Oxygen active 0,0001-0,004 Aluminum acid soluble 0,005-0,050 5 Titan0,001-0,050 IronErest 2. Method of steel production, including the smelting of metal in the steelmaking unit, its release into the ladle, deoxidation 0 with manganese and silicon-containing ferroalloys in the ladle and casting into molds or in continuous casting machines, characterized in that, in order to increase the density and ductility of the metal of the cortical layer, the steel is additionally deoxidized with aluminum and titanium to obtain the content of active oxygen below equilibrium with carbon at atmospheric pressure and temperature of steel crystallization of values, while the minimum allowable content of aluminum and titanium is determined by the following relationship: 2.35- 10 5 YES1 + 0,4Ti) 0.0004 + 0.00130 -1.26Н -0.0074N where C, H, N, AI, and Ti are the contents of carbon, hydrogen, nitrogen, aluminum, and acid-soluble and titanium, respectively. The chemical composition of steel The test results of the cortical layer of ingots Data on the method of production of low-silicon liquid steel Table 1 table 2 Table 3