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Method for increasing number of continuous drawing furnaces of sulfur-containing gear steel

A technology of gear steel and continuous drawing, which is applied in the field of metallurgy, can solve the problems of stopper rod rising, shutdown, and flow loss, and achieve the goals of improving the pass rate of cast billets and molten steel yield, broad application prospects, and increasing the number of continuous drawing furnaces Effect

Inactive Publication Date: 2021-11-30
HANDAN IRON & STEEL GROUP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Especially when the billet with a cross section of ≤200mm*200mm is used for production, it is easy to cause the stopper rod to rise, the nozzle to be blocked and the flow to drop, or even an accident to shut down, which disrupts the normal production rhythm of the steelmaking plant and makes the production cost high.

Method used

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  • Method for increasing number of continuous drawing furnaces of sulfur-containing gear steel

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Effect test

Embodiment 1

[0037] A method of increasing the number of continuous drawing furnaces of sulfur-containing gear steel in this embodiment comprises the following steps:

[0038] (1) Converter smelting: Converter smelting end point C: 0.08%, P: 0.012%, tapping temperature 1636°C, adding 100kg of aluminum block and 400kg of synthetic slag when tapping 1 / 3 (synthetic slag composition: CaO: 48% , SiO 2 : 9%, Al 2 o 3 : 36%, MgO: 7%); oxygen content in steel 35 ppm; tapping time 4min15s, ladle argon blowing time 4min30s, the alloy material on the surface of the slag layer is not agglomerated; the ladle headroom for converter tapping is 350mm, and the amount of slag is 3kg / ton of steel;

[0039] (2) LF refining: micro positive pressure operation throughout the whole process, the damper opening of the side suction in the early stage of refining is controlled at 72%, and the damper opening is controlled at 31% in the middle and later stages; 7.5kg / t of lime is added during the heating process, ...

Embodiment 2

[0044] (1) Converter smelting: Converter smelting end point C: 0.09%, P: 0.013%, tapping temperature 1631°C, adding 120kg of aluminum block and 400kg of synthetic slag when tapping 1 / 3 (synthetic slag composition: CaO: 42% , SiO 2 : 10%, Al 2 o 3 : 40%, MgO: 8%); the oxygen content in the steel is 40 ppm; the tapping time is 4min21s, the ladle argon blowing time is 3min26s, the alloy material on the surface of the slag layer is not lumpy; the ladle headroom for converter tapping is 300mm; 3.5kg / ton of steel;

[0045] (2) LF refining: micro positive pressure operation throughout the whole process, the damper opening of side suction is controlled at 80% in the early stage of refining; the damper opening is controlled at 26% in the middle and late stages; 9.8kg / t of lime is added during the heating process, and silicon carbide is added in total Amount of 0.3kg / t, refining final slag composition: TFe 0.56%, CaO 54.8%, SiO 2 15%, Al 2 o 3 22.6%, MgO 7.04%, heat storage of th...

Embodiment 3

[0050] (1) Converter smelting: Converter smelting end point C: 0.10%, P: 0.014%, tapping temperature 1633°C, adding 150kg of aluminum block and 400kg of synthetic slag when tapping 1 / 3 (synthetic slag composition: CaO: 55% , SiO 2 : 3%, Al 2 o 3 : 32%, MgO: 10%); oxygen content in steel 26 ppm; tapping time 5min13s, ladle argon blowing time 3min20s, alloy material on the surface of slag layer is not agglomerated; converter tapping ladle clearance is 400mm, slag amount 2kg / ton of steel;

[0051] (2) LF refining: micro positive pressure operation throughout the whole process, the damper opening of the side suction in the early refining is controlled at 85%; the damper opening is controlled at 38% in the middle and late stages; 10.2kg / t of lime is added during the heating process, and silicon carbide is added in total Amount of 0.30㎏ / t, refining final slag composition: TFe 0.5%, CaO 55.5%, SiO 2 13%, Al 2 O3 23%, MgO 8.0%; during the refining process, the ladle heat is st...

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Abstract

The invention discloses a method for increasing the number of continuous drawing furnaces of sulfur-containing gear steel. The method comprises the working procedures of converter smelting, LF refining, RH refining and continuous casting. The method comprises the following steps of (1) at a converter smelting end point, C is not less than 0.06%, P is not more than 0.015%, and the tapping temperature is 1640 + / -10 degrees Celsius, during tapping, aluminum blocks and synthetic slag are added into molten steel, and the oxygen content in the steel is smaller than or equal to 50 ppm; (2) LF refining target slag comprises the following components of less than or equal to 0.6% of TFe, 54%-56% of CaO, 13%-15% of SiO2, 21%-23% of Al2O3 and 6%-8% of MgO, after slag is formed, white slag is kept by adopting a method of supplementing lime and silicon carbide, and adding a calcium line before outbound; (3) RH refining, after vacuum treatment is completed, adding a sulfur line, after soft argon blowing is carried out for more than or equal to 15 minutes, and discharging the molten steel; and (4) continuous casting, adopting a submersed nozzle. According to the method provided, the average continuous casting furnace number reaches 15, and the low-power grade of the produced gear steel reaches 2.0 grade.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a method for increasing the number of continuous drawing furnaces of sulfur-containing gear steel. Background technique [0002] Free-cutting gear steel is currently the most widely used steel type in my country for the manufacture of transmission gears and gear shaft materials for various construction machinery, automobiles, and agricultural vehicles. It is required to have excellent strength and toughness and high surface hardness, specific hardenability and narrow hardenability bandwidth, high purity, high crystal block degree and avoid mixed crystals, good surface quality, in order to improve the wear resistance of gears. Abrasion resistance, bending strength, bending fatigue strength, fatigue life, pitting resistance, abrasion resistance and scratch resistance. Therefore, it is one of the most demanding steel grades in all steel production. [0003] Due to t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21C5/28C21C7/00C21C7/072C21C7/076C21C7/10
CPCC21C5/28C21C7/076C21C7/0056C21C7/072C21C7/10Y02P10/20
Inventor 肖步庆李瑞生杨之俊师艳秋王建飞李阳王晓栋
Owner HANDAN IRON & STEEL GROUP
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