RU2243269C1 - Method of melting low-carbon titanium-containing steel - Google Patents

Abstract

FIELD: ferrous metallurgy; making titanium-alloyed steels at low content of nitrogen.

SUBSTANCE: proposed method includes tapping of melt, introduction of deoxidizing agents, evacuation followed by introduction of titanium-containing ferroalloys in form of titanium-containing powder wire at the following relationship: Qp.w_Ti=100Q_st (0.022-1.652 (Mn)+61.559 (S)+1.091(N)+7.585 (Al)+3.063 [Ti]_reqo/[Ti]_p.w, where Qp.w_Ti is consumption of powder wire with ferro-titanium filler (by filler), kg; Q_st is mass of molten steel, t; (Mn), (S), (N), (Al) is content of magnese, sulfur, nitrogen and aluminum in sample of metal before introduction of powder wire, [Ti]_reqo is required content of titanium in steel, %; [Ti]_p.w is content of titanium in power wire, %.

EFFECT: low cost of process; increased yield of finished product; enhanced resistance of steel-teeming ladles; reduced content of non-metallic inclusions.

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Description

The invention relates to ferrous metallurgy, and in particular to the production of titanium alloy steels with a low nitrogen content, and can be used in steelmaking workshops.

A known method of deoxidation and steel modification, including the supply of synthetic slag to the ladle, the release of the melt, the introduction of deoxidizers and titanium-containing ferroalloys, purging with silicocalcium (Bulletin of the NTI Ferrous Metallurgy, 1984, No. 19, p. 9-30).

The disadvantages of this method are the high fumes of titanium, its unstable content in the finished steel, high nitrogen content.

The closest analogue of the claimed invention is a method for the production of titanium-containing steel, comprising feeding synthetic slag into the ladle, releasing the melt, introducing deoxidizers and titanium-containing ferroalloys, blowing with powdered silicocalcium, while the melt in the ladle is additionally vacuumized, and titanium-containing ferroalloys are introduced in two portions, the first of which into 65-85% of the total amount is introduced before the melt is purged with silicocalcium, and the second is introduced during or after evacuation, while the silicocalcium is blown they are consumed at a rate of 3-5 kg / t of slag per 1% of titanium oxides oxidized to slag, and the melt is evacuated after purging with powdered silicocalcium (see description of AS USSR No. 1786109, IPC ⁷ C 21 C 7/06, publ. 07.01.93., Bulletin No. 1).

Signs of the closest analogue, coinciding with the essential features of the claimed invention: the release of the melt, the introduction of deoxidizers, titanium-containing ferroalloys, evacuation.

The known method does not provide the desired technical result for the following reasons.

Found in the known method, the recovery of titanium from synthetic slag by blowing powder of silicocalcium slag will lead to a rise in the cost of steelmaking due to the use of special equipment for blowing, and the use of an expensive deoxidizer.

The introduction of titanium in two portions, the first in the bucket along with all deoxidizers, and the second during evacuation, causes its high waste, increase in specific consumption, decrease in yield.

At the same time, the oxidation of silicon from silicocalcium will lead to a decrease in the basicity of slag, metal resulfurization, a decrease in the resistance of steel-pouring ladles, and an increase in the content of non-metallic inclusions.

In addition, this method cannot be used in the smelting of steels with a silicon content of less than 0.03%, since silicon from silicocalcium partially passes into the metal.

The above disadvantages lead to increased costs in the production of titanium-containing steels and do not allow it to be used in the production of steels with a low carbon and silicon content and a normalized content of non-metallic inclusions.

The basis of the invention is the task of improving the method of steelmaking, in which the required titanium content is obtained at the lowest cost and increasing yield, increasing the durability of steel casting ladles, reducing the content of non-metallic inclusions.

The problem is solved in that in the method of smelting titanium-containing steel, including the release of the melt, the introduction of deoxidizers and titanium-containing ferroalloys, evacuation, titanium-containing ferroalloys are introduced after evacuation in the form of a titanium-containing flux-cored wire from the following ratio

Qpp _Ti = 100Q _st (0.022-1.652 [Mn] +61.559 [S] +1.091 [N] +7.585 [Al] +3.063 [Ti] _teb ) / [Ti] _pp ,

where Qpp _Ti - flow rate of flux-cored wire with a filler of ferrotitanium (by filler), kg;

Q _article - the mass of liquid steel, t;

[Mn], [S], [N], [Al] - the content of manganese, sulfur, nitrogen and aluminum in the metal sample before entering the flux-cored wire,%;

[Ti] _req - required titanium content in steel,%;

[Ti] _pp - titanium content in flux-cored wire,%;

100; 0.022; 1.652; 61,559; 1.091; 7.585; 3,063 empirical coefficients obtained experimentally.

The essence of the proposed technical solution is to prepare the metal before introducing a titanium-containing wire by reducing the activity of oxygen and nitrogen before introducing titanium-containing ferroalloys in the form of a titanium-containing flux-cored wire after deoxidation of the metal in the ladle with aluminum and ferromanganese and vacuum.

Deoxidation of metal with aluminum and ferromanganese and evacuation of the metal before the introduction of titanium-containing ferroalloys allows to obtain a low oxygen content in the metal and slag, to bind nitrogen with aluminum and the required titanium content in the finished steel.

This method is illustrated by the following example.

Smelted steel grade 08 ps according to GOST 9045-93. 320 tons of molten iron containing 4.3% carbon, 0.59% silicon, 0.21% manganese, 0.014% sulfur, 0.053% phosphorus were poured into an oxygen converter, and 20 tons of solid pig iron and 60 tons of scrap metal were heaped up from trimmed sheet metal.

The melting was purged in a 370-t oxygen converter. During the smelting production, 546 kg of ferromanganese FMN70 and 75 kg of pig aluminum were added to the ladle. The metal after release from the converter contained 0.05% carbon, 0.15% manganese, 0.011% sulfur, 0.011% phosphorus, 0.02% chromium, 0.02% nickel and 0.04% copper.

Next, the metal was subjected to vacuum in a circulating mode. The mass of the metal before the start of evacuation was 364 tons.

The metal was subjected to vacuum decarburization for 35 minutes. The residual vacuum at the end of the evacuation was 0.01 mm Hg.

After averaging, 680 kg of aluminum wire was introduced into the metal. After that, the metal contained 0.005% carbon, 0.15% manganese, 0.009% sulfur, 0.003% nitrogen, 0.011% phosphorus, 0.02% chromium, 0.02% nickel, 0.04% copper and 0.05% aluminum.

Then a flux-cored wire filled with ferro-titanium filler containing 69.7% titanium was introduced into the metal to obtain 0.05% titanium in steel. The flux-cored wire consumption was determined from the expression

Opp _ti = 100 · 363 · (0.022-1.652 · 0.15 + 61.559 · 0.009 + 1.091 · 0.003 + 7.585 · 0.05 + 3.063 · 0.05) / 69.7 = 450 kg.

Finished steel contained 0.005% carbon, 0.14% manganese, 0.009% sulfur, 0.009% phosphorus, 0.02% chromium, 0.02% nickel, 0.04% copper, 0.05% aluminum, 0.05% titanium and 0.005% nitrogen.

With this method of smelting titanium-containing steels, the required titanium content is obtained at the lowest cost, the yield is increased, the durability of steel casting ladles is increased, the content of non-metallic inclusions is reduced, the volume of production and profit from sales of products increase.

Claims (1)

A method of smelting low-carbon titanium-containing steel, including the release of the melt, the introduction of deoxidizers and titanium-containing ferroalloys, evacuation, characterized in that the titanium-containing ferroalloys are introduced into the metal after evacuation in the form of a titanium-containing flux-cored wire from the following ratio: Qpp _Ti = 100Q _st (0.022-1.652 [Mn] +61.559 [S] +1.091 [N] +7.585 [A1] +3.063 [Ti] required) / [Ti] pp, where - Qpp _Ti - consumption of flux-cored wire with a filler of ferrotitanium (for filler), kg; Q _article - the mass of liquid steel, t; [Mn], [S], [N], [A1] - the content of manganese, sulfur, nitrogen and aluminum in the metal sample before entering the flux-cored wire,%; [Ti] _req - required titanium content in steel,%; [Ti] _pp - titanium content in flux-cored wire,%; 100; 0.022; 1.652; 61,559; 1.091; 7.585; 3,063 - empirical coefficients obtained experimentally.