CN103045792B - Smelting technology of low-sulfur steel for thick plates during whole-course bottom blowing nitrogen production of converter - Google Patents

Smelting technology of low-sulfur steel for thick plates during whole-course bottom blowing nitrogen production of converter Download PDF

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Publication number
CN103045792B
CN103045792B CN201310005588.5A CN201310005588A CN103045792B CN 103045792 B CN103045792 B CN 103045792B CN 201310005588 A CN201310005588 A CN 201310005588A CN 103045792 B CN103045792 B CN 103045792B
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converter
molten steel
nitrogen
less
blowing
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CN103045792A (en
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朱志远
孙硕猛
周金明
史志强
王星
刘金刚
吕延春
张祥
秦登平
危尚好
王志刚
杨荣光
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Shougang Group Co Ltd
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Shougang Corp
Qinhuangdao Shouqin Metal Materials Co Ltd
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Abstract

The invention provides a smelting technology of low-sulfur steel for thick plates during whole-course bottom blowing nitrogen production of a converter, and belongs to the technical field of low-sulfur steel smelting with converters. The smelting technology mainly comprises the steps of converter smelting, an LF (ladle) furnace refining, and continuous caster pouring, and the whole-course bottom blowing nitrogen of the converter is adopted. The smelting technology has the advantages that when the low-sulfur steel for the thick plates is produced, the bottom blowing cost of the converter smelting is lowered, and the nitrogen content of liquid steel can be controlled below 80ppm.

Description

The smelting technology of low-sulfur steel for the omnidistance bottom blowing nitrogen production of converter plate of moderate thickness
Technical field
The invention belongs to converter smelting low-sulfur steel technical field.Be particularly related to the smelting technology of low-sulfur steel for the omnidistance bottom blowing nitrogen production of a kind of converter plate of moderate thickness.
Background technology
Along with social progress and the development of technology, user requires more and more high to the intensity of steel, toughness, processing characteristics etc., also more and more higher to the requirement of the chemical composition of steel and homogeneity of structure.In metal, the harmful element of trace can reduce physicals and the mechanical property of metal greatly.Therefore, remove impurity element in metal melt is link important in Metal smelting process always.In specific situation, the existence of nitrogen in steel has reduced toughness and the plasticity of steel, make steel produce strain aging, aging precipitation sclerosis or aged brittleness, cause the blue shortness, cold short of steel, impel center porosity or form microscopic pores, produce hairline and bubble, affect deep drawability, welding property, HAZ performance, the hot workability of steel, cause casting blank cleavage and cause intergranular corrosion.So many high-grade steel grades have strict requirement to the nitrogen content in steel.
Because top blowing oxygen, bottom blowing rare gas element technique are degassed to molten steel, remove be mingled with highly beneficial.Converter top bottom compositing blowing steelmaking technology all adopts top blast O 2, it can be N that bottom is blown into gas 2, Ar, O 2, CO 2, CO etc.Consider technique and cost, the most bottom blowing process of existing top and bottom combined blown converter are N 2/ Ar switches, and adopts initial smelting period bottom blowing N 2, the later stage switches to the pattern of Ar.Because nitrogen is compared with argon gas, there is stronger cost advantage, therefore adopt Bottom Blowing Converter nitrogen blowing to have important industrial significance.
Summary of the invention
The object of the present invention is to provide the smelting technology of low-sulfur steel for the omnidistance bottom blowing nitrogen production of a kind of converter plate of moderate thickness.Solve the high problem of low-sulfur steel bottom-blowing of converter cost of producing.
It is plate of moderate thickness low-sulfur steel that this invention is mainly applicable to steel grade scope, and institute's steelmaking kind limited range is S(0.002wt%, 0.015wt%], N is less than 80ppm; Production process route: converter-refining LF stove-continuous caster.For solving the problems of the technologies described above, concrete technology step and parameter are as follows:
1, converter smelting: the sulphur content that enters stove molten iron is 0.003wt%~0.030wt%, converter smelting adopts omnidistance bottom blowing nitrogen, and the span of control of bottom blowing flow is 0.01~0.05Nm 3/ tmin, terminal after-blow is no more than 1 time, and converter smelting endpoint molten steel temperature is 1630~1700 ℃, and converter smelting endpoint molten steel oxygen level is 400~1200ppm, and sulphur content is 0.004wt%~0.025wt%, converter tapping nitrogen is less than 25ppm; Converter tapping process is strong deoxidation after first weak deoxidation, and tap hole is circular jet tapping, and the tapping time is 3~5min, and tapping process nitrogen pick-up is less than 15ppm;
2, LF stove refining: LF stove refining process bottom blown gas is argon gas, during stirring, not exposed molten steel face is in air, and bottom blowing intensity is 0.002~0.008Nm 3/ mint, the electric-arc heating time is 0~12min, and it is 0.0018wt%~0.0145wt% that LF refining treatment finishes molten steel sulphur content, and the nitrogen pick-up of LF refining process is less than 10ppm;
3, continuous caster casting: continuous caster casting adopts full guard cast; guarantee that long nozzle and ladle tap hole contact part are without residual steel; seal washer is 3~6mm; pouring basket liquid level fluctuation is less than 1/3 of the degree of depth; liquid level fluctuation of crystallizer is-3mm~+ 3mm, controls ladle and is less than 3ppm to the nitrogen pick-up of tundish process molten steel, and tundish is less than 2ppm to the nitrogen pick-up of crystallizer process molten steel; finished product molten steel sulphur content is 0.002wt%~0.015wt%, and continuous casting stage nitrogen increased amount is less than 5ppm.
In converter tapping process, weak deoxidation adopts silicomanganese complex deoxidization, and strong deoxidation adopts aluminiferous material to carry out final deoxygenation.
The invention has the advantages that: during slab low-sulfur steel, reduced the bottom blowing cost of converter smelting aborning, and can be by Control of Nitrogen Content in molten steel below 80ppm.
Embodiment
Embodiment 1:
1, converter smelting: 100 tons of converters, entering stove Sulfur Content in Hot Iron content is 0.024wt%, converter smelting adopts omnidistance bottom blowing nitrogen, bottom blowing flow average out to 0.05Nm 3/ tmin, not after-blow is directly tapped, 1647 ℃ of converter smelting endpoint molten steel temperature, converter smelting endpoint molten steel oxygen level is 450ppm, molten steel sulphur content 0.015wt%, converter tapping nitrogen content is 13.8ppm; Converter tapping process deoxidation system is strong deoxidation after first weak deoxidation, taps and adds 500kgSiMn at 1/4 o'clock, adds afterwards 200kg containing aluminium deoxidizer, and tap hole is circular jet tapping, and the tapping time is 4.6min; The LF stove molten steel nitrogen content that enters the station is 22.3ppm, tapping process molten steel nitrogen pick-up 8.5ppm;
2, LF stove refining: LF stove refining process bottom blown gas is argon gas, during stirring, not exposed molten steel face is in air, and bottom blowing intensity is 0.005 Nm 3/ mint, the electric-arc heating time is 10min, it is that 0.007wt%, molten steel nitrogen content are 28.7ppm that LF refining treatment finishes molten steel sulphur content; LF stove refining treatment process molten steel nitrogen pick-up 6.4ppm;
3, continuous caster casting: continuous caster casting adopts full guard cast, guarantee that long nozzle and ladle tap hole contact part are without residual steel, seal washer is 4mm, pouring basket liquid level fluctuation is 1/4 of the degree of depth, liquid level fluctuation of crystallizer-2.4mm~+ 2.4mm, ladle is to tundish process molten steel nitrogen pick-up 1.8ppm, and tundish is to crystallizer process molten steel nitrogen pick-up 0.3ppm, continuous casting stage molten steel nitrogen increased amount 2.1ppm; Finished product molten steel sulphur content is that 0.008wt%, molten steel nitrogen content are 30.8ppm.

Claims (2)

1. a smelting technology for low-sulfur steel for the omnidistance bottom blowing nitrogen production of converter plate of moderate thickness, is characterized in that, concrete technology step and parameter are:
(1) converter smelting: the sulphur content that enters stove molten iron is 0.003wt%~0.030wt%, converter smelting adopts omnidistance bottom blowing nitrogen, and the span of control of bottom blowing flow is 0.01~0.05Nm 3/ tmin, terminal after-blow is no more than 1 time, and converter smelting endpoint molten steel temperature is 1630~1700 ℃, and converter smelting endpoint molten steel oxygen level is 400~1200ppm, and sulphur content is 0.004wt%~0.025wt%, converter tapping nitrogen is less than 25ppm; Converter tapping process is strong deoxidation after first weak deoxidation, and tap hole is circular jet tapping, and the tapping time is 3~5min, and tapping process nitrogen pick-up is less than 15ppm;
(2) LF stove refining: LF stove refining process bottom blown gas is argon gas, during stirring, not exposed molten steel face is in air, and bottom blowing intensity is 0.002~0.008Nm 3/ mint, the electric-arc heating time is 0~12min, and it is 0.0018wt%~0.0145wt% that LF refining treatment finishes molten steel sulphur content, and the nitrogen pick-up of LF refining process is less than 10ppm;
(3) continuous caster casting: continuous caster casting adopts full guard cast; seal washer is 3~6mm; pouring basket liquid level fluctuation is less than 1/3 of the degree of depth; liquid level fluctuation of crystallizer is-3mm~+ 3mm; ladle is less than 3ppm to the nitrogen pick-up of tundish process molten steel; tundish is less than 2ppm to the nitrogen pick-up of crystallizer process molten steel, and finished product molten steel sulphur content is 0.002wt%~0.015wt%, and continuous casting stage nitrogen increased amount is less than 5ppm.
2. technique according to claim 1, is characterized in that, the described weak deoxidation of step (1) adopts silicomanganese complex deoxidization, and strong deoxidation adopts aluminiferous material to carry out final deoxygenation.
CN201310005588.5A 2013-01-08 2013-01-08 Smelting technology of low-sulfur steel for thick plates during whole-course bottom blowing nitrogen production of converter Active CN103045792B (en)

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JPH0686614B2 (en) * 1990-02-14 1994-11-02 川崎製鉄株式会社 Method for producing high nitrogen content steel in bottom blown or top blown converter
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JP3027912B2 (en) * 1994-10-25 2000-04-04 住友金属工業株式会社 Manufacturing method of hot rolled steel sheet with excellent hole spreadability
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Address after: 066326 Du Zhuang Township, Funing County, Qinhuangdao, Hebei

Co-patentee after: Shougang Group Co. Ltd.

Patentee after: Qinhuangdao Shouqin Metal Material Co., Ltd.

Address before: 066326 Du Zhuang Township, Funing County, Qinhuangdao, Hebei

Co-patentee before: Capital Iron & Steel General Company

Patentee before: Qinhuangdao Shouqin Metal Material Co., Ltd.

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Effective date of registration: 20190528

Address after: 100041 Shijingshan Road, Shijingshan District, Shijingshan District, Beijing

Patentee after: Shougang Group Co. Ltd.

Address before: 066326 Du Zhuang Township, Funing County, Qinhuangdao, Hebei

Co-patentee before: Shougang Group Co. Ltd.

Patentee before: Qinhuangdao Shouqin Metal Material Co., Ltd.