CN1263878C - Production technology of steel containing sulphur easy cuwtting - Google Patents
Production technology of steel containing sulphur easy cuwtting Download PDFInfo
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- CN1263878C CN1263878C CN 200410014157 CN200410014157A CN1263878C CN 1263878 C CN1263878 C CN 1263878C CN 200410014157 CN200410014157 CN 200410014157 CN 200410014157 A CN200410014157 A CN 200410014157A CN 1263878 C CN1263878 C CN 1263878C
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Abstract
The present invention relates to technology for producing easy machining steel, particularly to electric furnace continuous casting producing technology of the easy machining steel, which relates to the field of a steel smelting technique in metallurgy industry. The present invention provides a technologic technique for producing sulfur-contained easy machining steel SUM43 by using a continuous casting method; the present invention solves the problem of large casting difficulty by using a process control method. The present invention is characterized in that in the smelting process, the sulfur content in steel is controlled according to a middle limit and an upper limit of requirements on steel grade ingredients, and the manganese content is controlled according to the upper limit; a molten steel pouring box is baked to be above 1000 DEG C; during electric furnace smelting, 30% to 50% of high sulfur iron charges are added; the vulcanization of a refining furnace is achieved by adopting a sulfur iron block method and a sulfur iron wire feeding method. A continuous casting section adopts the process control method; the control of the cooling intensity of a two-cooling system means adopting a secondary cooling system; secondary cooling primary section is cooled in a full water spraying mode, a rear section is cooled in a vapor-water spraying mode, and secondary cooling ratio water quantity is automatically regulated. The present invention has the advantages of low production cost and easy control of operation; the surface smoothness of casting blanks achieves more than six levels; the surfaces of more than 90% of casting blanks do not generate cracks. Besides, the adoption of sulfur and iron sulfur thread feeding technology of the refining furnace not only reduces production cost but also can accurately control the sulfur content.
Description
Technical field
The present invention is the electric furnace continuous casting production method of a kind of production technique of free-cutting steel, particularly free-cutting steel, relates to the smelting iron and steel technical field of metallurgy industry.
Technical background
Free-cutting steel is owing to have good free-cutting machinability, the surface smoothness height, the dimensional precision height, be widely used in many fields such as household electrical appliance, instrument and meter industry, present stage, mass-produced free-cutting steel was mainly sulphur free-cutting steel, sulphur content is high more, machinability is good more, but crack sensitivity is strong more, easy more generation strand crackle and strand bleedout in casting process, because free-cutting steel casting difficulty is big, most of manufacturer produces with die casting process, cost is higher, has restricted the production and the application of such steel.
Continuous casting production process commonly used is as follows: molten steel smelting, refining, vacuum oven denitrogenation deoxidation treatment; Continuous casting working procedure: ladle is to the cast of crystallizer full guard, tundish continuous temperature measurement; In the continuous casting process, adopt induction stirring and level detection; The continuous casting pulling rate is controlled automatically by the tundish superheating temperature, crystallizer and two cold automatic distribution waters; Control secondary cooling system cooling intensity, optimization vibration parameters and stirring parameter, control continuously cast bloom pulling rate and molten steel temperature in tundish.
Summary of the invention
Goal of the invention: in order to overcome the shortcoming that above-mentioned production technique exists, the invention provides a kind of Technology of producing sulphur free-cutting steel SUM43 with continuous metal cast process, adopt the method for process control, solved the big problem of casting difficulty, thereby realized purpose of the present invention.
Technical scheme: a kind of continuous casting producing method of sulphur free-cutting steel comprises smelting procedure: electrosmelting, refining, vacuum oven denitrogenation deoxidation treatment; Continuous casting working procedure: ladle is to the cast of crystallizer full guard, tundish continuous temperature measurement; In the continuous casting process, adopt induction stirring and level detection; The continuous casting pulling rate is controlled automatically by the tundish superheating temperature, crystallizer and two cold automatic distribution waters, and control secondary cooling system cooling intensity, optimization vibration parameters and stirring parameter, control continuously cast bloom pulling rate and molten steel temperature in tundish is characterized in that:
1, in the electrosmelting process, sulphur content is by the middle upper limit control of steel grade composition requirement in the steel, and manganese content is control criterion toward upper limit control with Mn/S＞5; In order to reduce hydrogen in the steel, various raw and auxiliary materials must keep dry, and the tundish baking must be arrived more than 1000 ℃; In order to reduce nitrogen in steel and copper content, reduce cost, alleviate refining furnace simultaneously and increase sulphur pressure, the high-sulfur iron charge of electric furnace with addition of 30%～50%;
2, refining furnace adds sulphur employing sulphur iron and feeds silk thread technology, can reduce cost like this, can accurately control sulphur content again;
3, in the continuous casting section, adopt the method for process control, the described control two cold control secondary cooling system cooling intensity that are meant, adopt secondary cooling system, two cold sections just adopt full water spray cooling, and back segment adopts vapour-water spray cooling, regulates two cold specific waters automatically, control two cold but intensity and cooling performances, the strand tempering temperature is controlled at 200 ℃ ± 50 ℃.
Described two cold specific waters' automatic adjusting is meant that the control ratio water yield fluctuates in the 0.6-1.0L/kg scope with pulling rate, and suitable specific water can obviously reduce the sulphur free-cutting steel internal fissure.
Described vibration parameters is meant the vibration parameters that uses in the crystallizer control software, determines its mutual relationship formula according to selected vibration mode, determines other vibration parameters again, involving vibrations frequency, negative sliding time, crystallizer leading, oscillation mark spacing etc.In normal range, just must in the journey scope of necessarily shaking, determine its corresponding negative slip rate for guaranteeing vibration parameters.Show that through test reduce with the slippage rate, vibrational frequency reduces, it is smooth that casting billet surface is tending towards, and oscillation mark folds oscillation mark to flat straight shape concavity oscillation mark development by bending by convex.The journey of shaking is arranged under the 10mm condition, and the continuous casting pulling rate is when 1.0～2.3m/min, and the negative slip rate is arranged between 38～34.
Described control continuously cast bloom pulling rate fluctuates in 0.7～0.9V scope, takes place and casting blank bulging for preventing the bleed-out accident, and be best pulling rate with 0.9V.
Described molten steel temperature in tundish control is meant the superheating temperature of tundish, lower tundish superheating temperature helps to reduce the bleed-out accident, alleviate composition segregation and casting blank crack, continuous casting is opened and is watered the first stove tundish superheating temperature and be controlled at Δ T=15-40 ℃, normal heat: Δ T=10-30 ℃.
Steel billet is when the continuous casting pulling rate; because the interfacial tension of sulphur free-cutting steel is little, after mixing with it, slag is difficult to separate, and strand easily produces slag inclusion and dry slag; must correctly select crystallizer protecting residue for use, the selected covering slag prescription of the present invention is that Department of Metallurgy of University Of Chongqing provides.
Beneficial effect:
The production technique of sulphur free-cutting steel provided by the invention has following beneficial effect:
1, to have a production cost low in the present invention, and operation being easy to control.
2, casting billet surface smooth finish reaches more than 6 grades; When 4200～4500 rev/mins of turn ups, surface smoothness still reaches 6 grades.
3, continuous casting also can obviously reduce casting blank crack smoothly, reduces the composition segregation.
4, the casting billet surface more than 90% does not crack defective.
5, refining furnace adopts sulphur iron to add to feed sulphur silk thread technology and can reduce production costs, and can accurately control sulphur content again.
6, effectively control the tundish superheating temperature of molten steel, help to reduce the bleed-out accident, alleviate the composition segregation, and can reduce casting blank crack.
Embodiment:
Producing the trade mark with electric furnace is the free-cutting steel of SUM43, and its Chemical Composition is:
C：0.40～0.48％ Mn：1.35～1.65％ P：≤0.040％
S：0.24～0.33％ Si：≤0.35％
Continuously cast bloom requires: 150mm * 150mm
With 70 tons of high resistance electric furnaces, five machines, five stream steel alloy billet casters.Ladle is to the cast of crystallizer full guard, tundish continuous temperature measurement; Adopt induction stirring and level detection in the continuous casting process, level detection adopts the Cs radiation detection, and logic approach for mold level control adopts servomotor automatic control type stopper; The continuous casting pulling rate is controlled automatically by the tundish superheating temperature, crystallizer and two cold automatic distribution waters.
Sulphur content is high more in the steel, and then the cutting ability of steel is good more, in order to improve the cutting ability of SUM43 as far as possible, during smelting in the molten steel S content press the upper limit 0.28～0.33% control in the composition; The sulphur free-cutting steel sulphur content is high more, and its crack sensitivity is strong more, easy more generation strand crackle and strand bleedout in the casting process, should control inclusion morphology well for this reason, manganese content is as far as possible toward upper limit control, and manganese is control criterion by 1.60～1.65% controls with Mn/S＞5; In order to reduce hydrogen in the steel, various raw and auxiliary materials must keep dry, and the tundish baking must be arrived more than 1000 ℃; In order to reduce nitrogen in steel and copper content, reduce cost, alleviate refining furnace simultaneously and increase sulphur pressure, high-sulfur pig iron and the molten iron of electric furnace with addition of 30%～50%; Refining furnace adds sulphur to be adopted sulphur iron and feeds silk thread technology, can reduce cost like this, can accurately control sulphur content again.
Adopt the method for process control during continuous casting, comprise that control is two cold, optimize vibration and stirring parameter, control continuously cast bloom pulling rate and molten steel temperature in tundish.The continuous casting section, control secondary cooling system cooling intensity adopts secondary cooling system, two cold sections just adopt full water spray cooling, and back segment adopts vapour-water spray cooling, regulates two cold specific waters automatically, control two cold but intensity and cooling performances, the strand tempering temperature is controlled at 150 ℃ ± 10 ℃.Secondary cooling system specific water control is fluctuateed in the 0.8-0.95L/kg scope with pulling rate.Suitable specific water can obviously reduce the sulphur free-cutting steel internal fissure.
The crystallizer control software adopts sinusoidal vibration, according to the mutual relationship formula between the sinusoidal vibration form, determines other vibration parameters, involving vibrations frequency, negative sliding time, crystallizer leading, oscillation mark spacing etc.In normal range, just must in the journey scope of necessarily shaking, determine its corresponding negative slip rate for guaranteeing vibration parameters.Show that through test reduce with the slippage rate, vibrational frequency reduces, it is smooth that casting billet surface is tending towards, and oscillation mark folds oscillation mark to flat straight shape concavity oscillation mark development by bending by convex.The journey of shaking is arranged under the 10mm condition, and the continuous casting pulling rate is when 1.0～1.7m/min, and the negative slip rate is set to 38; The continuous casting pulling rate is when 2～2.3m/min, and the negative slip rate is set to 34.
Crystallizer magnetic stirrer stirring coil adopts external placed type, adopts suitable stirring parameter make carbon in the strand, sulphur segregation can be improved significantly, present embodiment employing M-EMS mixing parametric is controlled, its strand is square billet center carbon content C through assay
0, sulphur content S
0With on the square billet diagonal lines apart from summit 20mm, diagonal lines 1/4 place and from the ratio of the mean value of 3 carbon content C in 20mm place, diagonal lines center and sulphur content S, C/C
0Reduce to 1.103, S from 1.18
0/ S reduces to 1.201 from 1.262.
For preventing that the bleed-out accident from taking place and casting blank bulging, the continuously cast bloom pulling rate is selected the 0.9V pulling rate for use.
Molten steel temperature in tundish control is meant the superheating temperature of tundish, lower tundish superheating temperature helps to reduce the bleed-out accident, alleviate composition segregation and casting blank crack, continuous casting is opened and is watered the first stove tundish superheating temperature and be controlled at Δ T=20-30 ℃, normal heat: Δ T=15-25 ℃.
Steel billet is when the continuous casting pulling rate, because the interfacial tension of sulphur free-cutting steel is little, is difficult to after slag mixes with it separate, and strand easily produces slag inclusion and dry slag, so will correctly select covering slag for use.
Cutting ability to the SUM43 free-cutting steel produced detects, and when rotating speed was 4500 rev/mins, casting billet surface smooth finish still reached 6 grades; Smear metal is a sheet.Strand does not have internal fissure and composition segregation phenomena.
Claims (3)
1, a kind of production method of sulphur free-cutting steel comprises smelting procedure: electrosmelting, refining, vacuum oven denitrogenation deoxidation treatment; Continuous casting working procedure: ladle is to the cast of crystallizer full guard, tundish continuous temperature measurement; In the continuous casting process, adopt induction stirring and level detection; The continuous casting pulling rate is controlled automatically by the tundish superheating temperature, crystallizer and two cold automatic distribution waters, and control secondary cooling system cooling intensity, optimization vibration parameters and stirring parameter, control continuously cast bloom pulling rate and molten steel temperature in tundish is characterized in that:
(1) in smelting process, sulphur content is by the middle upper limit control of steel grade composition requirement in the steel, and manganese content is control criterion toward upper limit control with Mn/S＞5; The baking of molten steel tundish must be arrived more than 1000 ℃; During electrosmelting with addition of 30%～50% high-sulfur iron charge;
(2) refining furnace adds sulphur employing sulphur iron block and feeds sulphur iron wire line method;
(3) the continuous casting section adopts the method for process control, and described control secondary cooling system cooling intensity is meant the employing secondary cooling system, and two cold sections just adopt full water spray cooling, and back segment adopts vapour-water spray cooling, regulates two cold specific waters automatically;
Described two cold specific waters' automatic adjusting is meant that the control ratio water yield fluctuates in the 0.6-1.0L/kg scope with the continuous casting pulling rate;
Described vibration parameters is meant the vibration parameters that uses in the crystallizer control software, and the journey of shaking is arranged under the 10mm condition, and the continuous casting pulling rate is when 1.0～2.3m/min, and the negative slip rate is arranged between 34～38;
Described continuously cast bloom pulling rate is controlled at fluctuation in 0.7～0.9V scope;
Described molten steel temperature in tundish is meant the superheating temperature of tundish, and continuous casting opens that the tundish superheating temperature is controlled at Δ T=15-40 ℃ when watering first stove, normal heat: Δ T=10-30 ℃.
2, the production method of sulphur free-cutting steel according to claim 1 is characterized in that: the strand tempering temperature is controlled at 200 ℃ ± 50 ℃.
3, the production method of sulphur free-cutting steel according to claim 1 and 2 is characterized in that: described continuously cast bloom pulling rate is 0.9V.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200410014157 CN1263878C (en) | 2004-02-26 | 2004-02-26 | Production technology of steel containing sulphur easy cuwtting |
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| CN 200410014157 CN1263878C (en) | 2004-02-26 | 2004-02-26 | Production technology of steel containing sulphur easy cuwtting |
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| CN1263878C true CN1263878C (en) | 2006-07-12 |
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Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8545137B2 (en) * | 2010-03-30 | 2013-10-01 | Nippon Steel & Sumitomo Metal Corporation | Cutting method of steel for machine structural use |
| CN102211160B (en) * | 2011-05-13 | 2013-02-27 | 攀钢集团有限公司 | Continuous casting method of sulfur-containing easy-cutting pinion steel |
| CN102329918B (en) * | 2011-05-18 | 2013-03-20 | 首钢贵阳特殊钢有限责任公司 | Widely applicable melting technology of free cutting steel containing lead |
| CN102303108B (en) * | 2011-09-22 | 2016-06-01 | 首钢贵阳特殊钢有限责任公司 | A kind of continuous casting manufacturing technique improving automatic steel slab quality |
| CN103326216B (en) * | 2013-06-18 | 2016-06-22 | 中山品高电子材料有限公司 | The anti-oxidation curing process of binding post |
| CN109112418B (en) * | 2017-06-26 | 2020-09-01 | 鞍钢股份有限公司 | Continuous casting method of high manganese steel |
| CN109252086A (en) * | 2017-07-13 | 2019-01-22 | 鞍钢股份有限公司 | Production method of high-sulfur steel |
| CN111992686B (en) * | 2020-09-03 | 2021-12-17 | 福建三钢闽光股份有限公司 | Aerial fog full-water combined cooling high-carbon steel continuous casting production method |
| CN115852232B (en) * | 2022-11-28 | 2024-04-30 | 阳春新钢铁有限责任公司 | Method for producing chalcogenide free-cutting steel by continuous casting full water cooling |
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Owner name: NANJING NANGANG INDUSTRY DEVELOPMENT CO., LTD. Free format text: FORMER OWNER: NANJING UNITE STEEL CO., LTD. Effective date: 20091120 |
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Effective date of registration: 20091120 Address after: Liuhe District of Nanjing City, Jiangsu Province, xiejiadian Patentee after: Nanjing Iron & Steel United Co., Ltd. Address before: Liuhe District of Nanjing City, Jiangsu Province, xiejiadian Patentee before: Nanjing Iron & Steel United Co., Ltd. |
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