CN101492758B - Method for controlling non-metallic inclusion in pipeline steel - Google Patents

Method for controlling non-metallic inclusion in pipeline steel Download PDF

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CN101492758B
CN101492758B CN200910079465XA CN200910079465A CN101492758B CN 101492758 B CN101492758 B CN 101492758B CN 200910079465X A CN200910079465X A CN 200910079465XA CN 200910079465 A CN200910079465 A CN 200910079465A CN 101492758 B CN101492758 B CN 101492758B
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inclusion
molten steel
cao
steel
slag
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CN101492758A (en
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朱国森
王新华
李海波
刘建辉
李强
李明
周德光
亢小敏
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Shougang Group Co Ltd
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Shougang Corp
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
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Abstract

A method for controlling non-metal inclusions in pipe line steel belongs to the refining controlling field of steel making. The method comprises a step of controlling the following chemical components of non-metal inclusions of oxides in pipe line steel casts: 20wt%-35wt% of CaO, 10wt%-20wt% of MgO, 30wt%-60wt% of Al2O3 and not more than 5wt% of others. Sulfide inclusions in the pipe line steel casts comprise 90wt%-100wt% of CaS and not more than 10wt% of others, and no MnS inclusion exists in the pipe line steel casts. In the LF refining process, reaction between molten steel and high-alkalinity furnace slag is used to control contents of Ca, Mg and S in the molten steel, and Ca dosage in the calcium treatment process, so as to control melting point of the non-metal inclusions in the molten steel to be between 1500 DEG C and 1650 DEG C. The method has the advantage that deformation index of the non-metal inclusions in post rolling process is controlled to be not more than 0.5 while good oxidizing and desulfurizing effects of the molten steel are achieved, thus avoiding cracks caused in use process of the pipe line steel by linear or stripe-shaped non-metal inclusions after being rolled.

Description

A kind of method of controlling the pipeline nonmetallic inclusionsin steel
Technical field
The invention belongs to steel-making refining controlling technical field.Relate in particular to the control method of pipeline nonmetallic inclusionsin steel.
Background technology
Pipe line steel is mainly used in transfer oil, Sweet natural gas etc., in use except requiring to have the higher intensity and low temperature impact properties, the non-metallic inclusion in the steel is had relatively high expectations, and does not allow to occur the inclusion of distortion such as MnS in the pipe line steel.If the inclusion of distortion, in the operation of rolling, non-metallic inclusion is out of shape along with the distortion of steel matrix, can form the wire parallel with rolling direction or the inclusion of strip, and these inclusiones can become formation of crack in the use of pipe line steel.
Because S is strong segregation element, in process of setting, form the MnS inclusion easily.At present both at home and abroad during the production flow line steel, the method for mainly taking Ca to handle is avoided the generation of MnS inclusion.[Ca]/[S] generally 〉=2 do not have the MnS inclusion substantially in the steel, sulfide inclusion is mainly CaS.At this moment, the oxide inclusion in the molten steel then mainly is low-melting 12CaO7Al2O3, and this inclusion also can be deformed into wire with stocking in the operation of rolling.Therefore, low-melting calcium aluminate inclusion has become the subject matter of current pipeline steel Control and Inclusion Removal to the harm of pipe line steel performance.
Summary of the invention
The object of the present invention is to provide a kind of method of controlling the pipeline steel inclusion, solved the Inclusion Problem of harm pipe line steel performance.
The oxide-based inclusion that the present invention controls in the pipe line steel strand consists of: CaO:20wt%-35wt%, MgO:10wt%-20wt%, Al 2O 3: 30wt%-60wt%, other :≤5wt%, the fusing point of (weight percent) oxide inclusion are 1500 ℃-1650 ℃, the consisting of of sulfide-based inclusion in the steel: CaS:90～100wt%, other≤10wt%, no MnS inclusion.Concrete control method is the following processing parameter of control in each operation:
(1) converter tapping begins back molten steel in ladle and adds iron alloy (ferrosilicon, ferromanganese etc.), aluminium deoxidizer (aluminum shot, ferroaluminium, aluminium ferromanganese etc.), slowly-releasing reductor (Al powder+CaO), pre-melted slag (CaO+Al2O3), lime etc., feed in raw material in the tapping process and must guarantee before tap is 1/5-1/4, to finish, [Al] content of molten steel was between the 0.015wt%-0.060wt% after wherein the add-on of aluminium must satisfiedly be tapped and be finished, and the non-metallic inclusion composition after the tapping end in the molten steel is Al 2O 3: 90～100wt%, other :≤10wt%.
(2) adopt high basicity (dual alkalinity CaO/SiO2 〉=6) slag refining in the LF refining process, the compositing range that should control slag behind the LFization slag is: CaO:45wt%-60wt%, MgO:5wt%-12wt%, Al 2O 3: 20wt%-35wt%, SiO 2:≤8wt%, other :≤2wt%; The controlization slag time was at 10～15 minutes.
(3) after the change slag finishes, carry out ladle bottom blowing Ar gas strong mixing desulfurization, bottom blowing Ar airshed is controlled at 800～1600NL/min, and after the strong mixing desulfurization, molten steel [S] content can control to below the 0.0010wt%.
(4) in the strong mixing process, by [Mg] in the reaction between the slag control molten steel: 0.0003-0.0008wt%, [Ca]: 0.0005-0.0010wt%, when the LF refining finished, the inclusion in the molten steel was mainly CaO:10wt%-20wt%, MgO:15wt%-30wt%, Al 2O 3: 30wt%-55wt%, SiO 2:≤5wt%, CaS≤10wt%, MnO≤10wt%.
(5) molten steel carries out Ca and handles through after the vacuum-treat.[wt%Ca]/[wt%S] of control in the molten steel be at 1.2-1.8, soft blow flow control 30～80NL/min, when refining finishes in the molten steel main component of oxide-based inclusion be: CaO:20wt%-35wt%, MgO:10wt%-20wt%, Al 2O 3: 30wt%-60wt%, other :≤5wt%.The fusing point of this type impurity is: 1500～1650 ℃.The main component of sulfide-based inclusion is: CaS:90～100wt%, other≤10wt%.
The invention has the advantages that molten steel is when obtaining good deoxidation, sweetening effectiveness, control nonmetallic inclusionsin steel deformation index≤0.5 in the follow-up operation of rolling, the non-metallic inclusion of wire or strip can not appear in the pipe line steel coiled sheet, thus the crackle of having avoided pipe line steel in use to form because of non-metallic inclusion.
Description of drawings
Fig. 1 is the pattern of the inclusion in the molten steel of converter tapping end back, and the inclusion in the correspondence table one is formed.
Fig. 2 is the inclusion pattern in the molten steel after the LF refining, and the inclusion in the correspondence table two is formed.
Inclusion pattern when Fig. 3 finishes for refining in the molten steel, the inclusion in the correspondence table three is formed.
Fig. 4 is parallel to observed non-metallic inclusion pattern on the rolling direction for the coiled sheet sample, and the inclusion in the correspondence table four is formed.Do not observe the inclusion of obvious distortion.
Embodiment
Embodiment (10 heat test-results)
210 tons of oxygen combined blown converters, and converter tapping process adding ferro-aluminum 800kg (aluminium content: 40wt%), lime 1600kg, fluorite 400kg.It is 0.030wt% that tapping finishes back molten steel aluminium content,
The LF refining was changed slag in 11 minutes and is finished, and slag composition is CaO:55.8wt%, MgO:8.0wt%, Al2O3:29.8wt%, SiO2:5.3wt%, TFe:0.46wt%, MnO:0.15wt%.
Carry out bottom blowing Ar strong mixing desulfurization after changing slag, bottom blowing intensity is 1000Nl/min, and the bottom blowing time is 15 minutes.After the bottom blowing strong mixing desulfurization, the molten steel sulphur content is 0.0008wt%, [Mg]: 0.0005wt%, [Ca]: 0.0007wt% in the molten steel.
The RH vacuum-treat is fed the Si-Ca line and is carried out the Ca processing after 20 minutes, the Ca total amount that line feeding adds is 18kg, carries out the soft blow of steel ladle bottom argon blowing gas after the line feeding, and the control argon flow amount is 80Nl/min, soft blow [Ca] of molten steel after 15 minutes: 0.0012wt%, [S]: 0.0008, [Ca]/[S] is 1.5.
Table one is the chemical constitution of the inclusion in the molten steel of converter tapping end back, and the inclusion in the molten steel is mainly the Al2O3 inclusion at this moment.
Table two is the chemical constitution of the inclusion in the molten steel after the LF refining, and the inclusion main component in the molten steel is Al2O3, CaO, MgO at this moment.
The chemical constitution of the inclusion when table three finishes for refining in the molten steel, oxide-based inclusion main component is Al2O3, CaO, MgO in the molten steel at this moment.The fusing point of oxide-based inclusion is controlled between 1550 ℃～1600 ℃.All the other inclusiones are CaS inclusion (inclusion is numbered 15-20).
Table four is the chemical constitution of observed non-metallic inclusion in the coiled sheet, and the inclusion that inclusion is numbered 1-17 is oxide-based inclusion, and inclusion is numbered 18-20's and foreign material are sulfide-based inclusion.
Table one, converter tapping finish the chemical constitution (mass percent wt%) of the inclusion in the molten steel of back
The chemical constitution (mass percent wt%) of the inclusion after table two, the LF refining in the molten steel
Numbering MgO Al2O3 SiO2 CaS MnS CaO MnO
1 25.6 42.6 4.9 4.0 0.0 14.5 8.4
2 19.7 51.6 0.0 0.0 0.0 19.3 9.5
3 27.0 44.6 5.0 0.0 0.0 18.0 5.4
4 26.2 50.4 2.0 6.4 0.0 15.0 0.0
5 20.4 54.1 0.0 0.0 0.0 17.6 8.0
6 15.5 48.6 3.9 5.1 0.0 19.2 7.8
7 27.7 49.6 3.3 0.0 0.0 19.5 0.0
8 16.3 47.0 1.4 6.6 0.0 20.6 8.2
9 19.8 47.7 2.0 4.8 0.0 16.2 9.6
10 26.9 49.4 4.9 0.0 0.0 18.8 0.0
Numbering MgO Al2O3 SiO2 CaS MnS CaO MnO
11 23.2 49.0 0.0 0.0 0.0 19.4 8.4
12 28.4 46.5 0.0 1.7 0.0 19.3 4.1
13 26.2 38.8 5.0 3.6 3.8 16.7 5.9
14 18.8 48.3 2.9 6.5 0.0 14.0 9.5
15 16.6 47.4 0.0 6.9 0.0 19.4 9.7
16 23.6 42.6 4.9 4.0 0.0 15.5 9.4
17 21.2 55.3 2.7 6.3 0.0 12.9 1.6
18 16.8 50.8 0.0 9.2 0.0 20.2 3.0
19 27.3 42.9 0.0 3.1 0.0 19.7 7.0
20 23.0 49.9 4.2 3.0 0.0 20.0 0.0
The chemical constitution of table three, the inclusion when refining finishes in the molten steel
The inclusion numbering MgO Al2O3 SiO2 CaS MnS CaO MnO
1 16.5 52.2 0.0 2.4 0.0 28.6 0.4
2 18.8 45.6 0.0 5.0 0.0 29.4 1.3
3 20.0 47.3 2.3 1.3 0.0 29.2 0.0
4 11.0 53.0 0.0 2.1 0.0 33.9 0.0
5 17.3 49.7 0.0 3.7 0.0 29.0 0.4
6 18.2 50.1 0.0 1.9 0.0 27.2 2.6
7 16.4 45.6 0.0 4.0 0.0 34.0 0.0
8 18.5 56.1 0.0 4.2 1.0 20.0 0.2
9 18.5 43.9 0.0 3.9 0.0 33.7 0.0
The inclusion numbering MgO Al2O3 SiO2 CaS MnS CaO MnO
10 11.3 54.4 0.0 0.0 0.0 29.8 4.5
11 14.6 58.8 0.0 2.6 0.0 20.8 3.1
12 16.3 58.9 0.0 0.9 0.0 21.1 2.8
13 19.5 51.3 0.0 4.2 0.0 24.9 0.0
14 16.1 53.0 0.0 3.6 0.0 27.4 0.0
15 0.0 0.0 0.0 100.0 0.0 0.0 0.0
16 0.0 0.0 1.7 98.3 0.0 0.0 0.0
17 0.0 0.0 0.0 100.0 0.0 0.0 0.0
18 0.0 0.0 0.0 100.0 0.0 0.0 0.0
19 0.0 0.7 0.0 99.3 0.0 0.0 0.0
20 0.0 0.0 0.0 100.0 0.0 0.0 0.0
The chemical constitution of observed non-metallic inclusion in table four, the coiled sheet
The inclusion numbering MgO Al2O3 SiO2 CaS CaO MnO
1 14.8 56.6 0.0 0.0 28.6 0.0
2 10.1 55.0 0.0 0.0 34.9 0.0
3 15.6 52.6 0.0 0.0 31.8 0.0
4 17.8 53.1 0.0 0.0 25.9 3.2
5 12.1 50.7 0.0 0.0 34.9 2.3
6 13.8 51.9 0.0 0.0 34.3 0.0
7 18.4 51.7 0.0 0.0 29.9 0.0
8 16.8 55.1 1.5 0.0 26.6 0.0
The inclusion numbering MgO Al2O3 SiO2 CaS CaO MnO
9 11.7 54.5 0.0 2.2 31.6 0.0
10 12.5 58.5 0.0 0.0 26.2 2.9
11 12.6 52.1 0.0 0.0 31.5 3.9
12 13.1 52.5 0.0 2.8 31.6 0.0
13 19.6 58.0 2.1 0.0 20.4 0.0
14 19.2 53.3 1.4 0.0 26.1 0.0
15 19.7 59.0 0.0 0.0 21.3 0.0
16 12.3 55.2 0.0 0.0 32.6 0.0
17 18.8 48.3 0.0 1.5 31.3 0.0
18 0.0 0.0 0.0 93.2 6.8 0.0
19 0.0 0.0 0.0 97.7 2.3 0.0
20 0.0 0.0 0.0 100 0.0 0.0

Claims (1)

1. method of controlling the pipeline nonmetallic inclusionsin steel, the chemical constitution of oxide-based non-metallic inclusion is at CaO:20wt%-35wt%, MgO:10wt%-20wt%, Al in the control pipe line steel strand 2O 3: 30wt%-60wt%, other :≤5wt%; Consisting of of sulfide-based inclusion: CaS:90～100wt%, other≤10wt%, no MnS inclusion; Concrete control method is the following processing parameter of control in each operation:
(1) converter tapping begins back molten steel adding iron alloy, aluminium deoxidizer, slowly-releasing reductor, pre-melted slag CaO+Al in ladle 2O 3, lime, feed in raw material in the tapping process and must guarantee before tap is 1/5-1/4, to finish, wherein, [Al] content that the add-on of aluminium must satisfy tapping end back molten steel is between the 0.015wt%-0.060wt%, and the non-metallic inclusion composition that finishes in the molten steel of back in tapping is Al 2O 3: 90～100wt%, other :≤10wt%;
(2) adopt high basicity slag refining in the LF refining process, the compositing range of control slag is behind the LFization slag: CaO:45wt%-60wt%, MgO:5wt%-12wt%, Al 2O 3: 20wt%-35wt%, SiO 2:≤8wt%, other :≤2wt%; The controlization slag time was at 10～15 minutes;
(3) after the change slag finishes, carry out ladle bottom blowing Ar gas strong mixing desulfurization, bottom blowing Ar airshed is controlled at 800～1600NL/min, and after the strong mixing desulfurization, molten steel [S] content controls to below the 0.0010wt%;
(4) in the strong mixing process, by [Mg] in the reaction between the slag control molten steel: 0.0003-0.0008wt%, [Ca]: 0.0005-0.0010wt%, when the LF refining finished, the inclusion in the molten steel was CaO:10wt%-20wt%, MgO:15wt%-30wt%, Al 2O 3: 30wt%-55wt%, SiO 2:≤5wt%, CaS≤10wt%, MnO≤10wt%;
(5) molten steel is through after the vacuum-treat, carrying out Ca handles: [wt%Ca]/[wt%S] in the control molten steel is at 1.2-1.8, soft blow flow control 30～80NL/min, when refining finishes in the molten steel composition of oxide-based inclusion be: CaO:20wt%-35wt%, MgO:10wt%-20wt%, Al 2O 3: 30wt%-60wt%, other :≤5wt%; The fusing point of this type impurity is: 1500～1650 ℃, the composition of sulfide-based inclusion is: CaS:90～100wt%, other≤10wt%;
Described slowly-releasing reductor is Al powder+CaO;
Described high basicity is meant dual alkalinity CaO/SiO 2〉=6.
CN200910079465XA 2009-03-12 2009-03-12 Method for controlling non-metallic inclusion in pipeline steel Active CN101492758B (en)

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Families Citing this family (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102031334B (en) * 2009-09-30 2013-03-13 鞍钢股份有限公司 Inclusion control method for pipeline welding wire steel
CN101760585B (en) * 2010-02-03 2012-11-21 衡阳华菱连轧管有限公司 Deep-desulphurizing slag system containing BaO and Li2O and method for producing ultralow-sulfur steel by adopting same
CN101880753B (en) * 2010-06-10 2013-03-06 衡阳华菱钢管有限公司 Strong desulphurizer containing BaO and Li2O, production method thereof and method for deeply desulfurizing liquid steel
CN102337378B (en) * 2011-10-31 2013-06-26 首钢总公司 Process for removing non-metallic inclusions in molten steel
CN102676725A (en) * 2012-05-29 2012-09-19 南京钢铁股份有限公司 Method for controlling nonmetal inclusions in X70 stage acidoresistant pipeline steel
CN102719602A (en) * 2012-06-26 2012-10-10 山西太钢不锈钢股份有限公司 Clean steel-refining slagging method
CN102732666A (en) * 2012-07-05 2012-10-17 首钢总公司 Method for controlling non-metallic slag inclusion in medium and heavy plate of hydrogen-induced cracking resistance pipe line steel
CN103045806B (en) * 2013-01-15 2014-12-17 北京科技大学 Method for controlling low-melting-point inclusion in high-strength low-alloy steel
CN103060526A (en) * 2013-01-24 2013-04-24 宝山钢铁股份有限公司 Slag for controlling impurities of pipeline steel
CN107586918B (en) * 2017-08-30 2020-08-04 武汉钢铁有限公司 Method for controlling inclusions in thin-gauge hot-rolled dual-phase steel
CN113151639A (en) * 2021-02-08 2021-07-23 北京科技大学 Method for controlling deformation capacity of non-metallic inclusions in steel matrix based on viscosity
CN113549731A (en) * 2021-07-14 2021-10-26 鞍钢股份有限公司 Method for reducing aluminum killed steel inclusions

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

Patentee after: Shougang Group Co. Ltd.

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

Patentee before: Capital Iron & Steel General Company