CN116574965B - Method for improving inclusion level of wind power steel - Google Patents
Method for improving inclusion level of wind power steel Download PDFInfo
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- CN116574965B CN116574965B CN202310845466.0A CN202310845466A CN116574965B CN 116574965 B CN116574965 B CN 116574965B CN 202310845466 A CN202310845466 A CN 202310845466A CN 116574965 B CN116574965 B CN 116574965B
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 109
- 239000010959 steel Substances 0.000 title claims abstract description 109
- 238000000034 method Methods 0.000 title claims abstract description 93
- 239000002893 slag Substances 0.000 claims abstract description 128
- 230000008569 process Effects 0.000 claims abstract description 76
- 238000007670 refining Methods 0.000 claims abstract description 63
- 238000003723 Smelting Methods 0.000 claims abstract description 28
- 238000009792 diffusion process Methods 0.000 claims abstract description 27
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims abstract description 23
- 235000011941 Tilia x europaea Nutrition 0.000 claims abstract description 23
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 23
- 239000004571 lime Substances 0.000 claims abstract description 23
- 238000010079 rubber tapping Methods 0.000 claims abstract description 23
- 238000009489 vacuum treatment Methods 0.000 claims abstract description 23
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 22
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 19
- 238000009749 continuous casting Methods 0.000 claims abstract description 19
- 229910000616 Ferromanganese Inorganic materials 0.000 claims abstract description 14
- DALUDRGQOYMVLD-UHFFFAOYSA-N iron manganese Chemical compound [Mn].[Fe] DALUDRGQOYMVLD-UHFFFAOYSA-N 0.000 claims abstract description 14
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 13
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims abstract description 12
- 238000004140 cleaning Methods 0.000 claims abstract description 10
- 239000010436 fluorite Substances 0.000 claims abstract description 10
- 235000010627 Phaseolus vulgaris Nutrition 0.000 claims abstract description 8
- 244000046052 Phaseolus vulgaris Species 0.000 claims abstract description 8
- 229910052918 calcium silicate Inorganic materials 0.000 claims abstract description 8
- 239000000378 calcium silicate Substances 0.000 claims abstract description 8
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 claims abstract description 8
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229910010271 silicon carbide Inorganic materials 0.000 claims abstract description 8
- 229910001570 bauxite Inorganic materials 0.000 claims abstract description 7
- 239000008186 active pharmaceutical agent Substances 0.000 claims abstract description 5
- 229910052747 lanthanoid Inorganic materials 0.000 claims abstract description 5
- 150000002602 lanthanoids Chemical class 0.000 claims abstract description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 80
- 229910052786 argon Inorganic materials 0.000 claims description 40
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 34
- 238000007664 blowing Methods 0.000 claims description 25
- 238000005266 casting Methods 0.000 claims description 15
- 229910052742 iron Inorganic materials 0.000 claims description 15
- 229910052717 sulfur Inorganic materials 0.000 claims description 13
- 230000001965 increasing effect Effects 0.000 claims description 10
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 9
- 239000011575 calcium Substances 0.000 claims description 9
- 229910052791 calcium Inorganic materials 0.000 claims description 9
- 238000006477 desulfuration reaction Methods 0.000 claims description 8
- 230000023556 desulfurization Effects 0.000 claims description 8
- 229910052684 Cerium Inorganic materials 0.000 claims description 7
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims description 7
- 239000012535 impurity Substances 0.000 claims description 7
- 229910001200 Ferrotitanium Inorganic materials 0.000 claims description 6
- 239000000126 substance Substances 0.000 claims description 6
- 239000002994 raw material Substances 0.000 claims description 5
- 229910052698 phosphorus Inorganic materials 0.000 claims description 4
- 238000009628 steelmaking Methods 0.000 claims description 3
- 238000007599 discharging Methods 0.000 claims description 2
- 230000001502 supplementing effect Effects 0.000 abstract 1
- 230000000052 comparative effect Effects 0.000 description 44
- 238000003756 stirring Methods 0.000 description 18
- 230000015572 biosynthetic process Effects 0.000 description 12
- 239000007788 liquid Substances 0.000 description 11
- 238000002844 melting Methods 0.000 description 11
- 230000008018 melting Effects 0.000 description 11
- 238000005096 rolling process Methods 0.000 description 10
- 229910045601 alloy Inorganic materials 0.000 description 9
- 239000000956 alloy Substances 0.000 description 9
- 229910052746 lanthanum Inorganic materials 0.000 description 9
- 238000007254 oxidation reaction Methods 0.000 description 9
- -1 aluminum-silicon-calcium Chemical compound 0.000 description 8
- 230000000694 effects Effects 0.000 description 8
- 239000011159 matrix material Substances 0.000 description 8
- 230000003647 oxidation Effects 0.000 description 8
- 239000002245 particle Substances 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 7
- 238000007667 floating Methods 0.000 description 7
- 239000011819 refractory material Substances 0.000 description 7
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 6
- 239000002131 composite material Substances 0.000 description 6
- 239000000498 cooling water Substances 0.000 description 6
- 230000006378 damage Effects 0.000 description 6
- 229910004298 SiO 2 Inorganic materials 0.000 description 5
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 5
- 238000001816 cooling Methods 0.000 description 5
- 238000005261 decarburization Methods 0.000 description 5
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 5
- 239000012071 phase Substances 0.000 description 5
- 238000007711 solidification Methods 0.000 description 5
- 230000008023 solidification Effects 0.000 description 5
- 150000004763 sulfides Chemical class 0.000 description 5
- 239000011593 sulfur Substances 0.000 description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 4
- 230000002411 adverse Effects 0.000 description 4
- 238000004220 aggregation Methods 0.000 description 4
- 230000002776 aggregation Effects 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 238000001179 sorption measurement Methods 0.000 description 4
- 238000009849 vacuum degassing Methods 0.000 description 4
- 229910000519 Ferrosilicon Inorganic materials 0.000 description 3
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- XFWJKVMFIVXPKK-UHFFFAOYSA-N calcium;oxido(oxo)alumane Chemical compound [Ca+2].[O-][Al]=O.[O-][Al]=O XFWJKVMFIVXPKK-UHFFFAOYSA-N 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 230000024121 nodulation Effects 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical compound S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 229910000604 Ferrochrome Inorganic materials 0.000 description 2
- 229910001309 Ferromolybdenum Inorganic materials 0.000 description 2
- 229910001634 calcium fluoride Inorganic materials 0.000 description 2
- OSMSIOKMMFKNIL-UHFFFAOYSA-N calcium;silicon Chemical compound [Ca]=[Si] OSMSIOKMMFKNIL-UHFFFAOYSA-N 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 230000002708 enhancing effect Effects 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 230000001788 irregular Effects 0.000 description 2
- 230000006911 nucleation Effects 0.000 description 2
- 238000010899 nucleation Methods 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 239000011800 void material Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 229910000805 Pig iron Inorganic materials 0.000 description 1
- 206010039897 Sedation Diseases 0.000 description 1
- 229910000746 Structural steel Inorganic materials 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000009847 ladle furnace Methods 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 238000005502 peroxidation Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000036280 sedation Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 229910052815 sulfur oxide Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
- C22C33/06—Making ferrous alloys by melting using master alloys
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/30—Regulating or controlling the blowing
- C21C5/35—Blowing from above and through the bath
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/36—Processes yielding slags of special composition
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0006—Adding metallic additives
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0056—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0075—Treating in a ladle furnace, e.g. up-/reheating of molten steel within the ladle
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/06—Deoxidising, e.g. killing
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/10—Handling in a vacuum
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
-
- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
The invention relates to a method for improving inclusion level of wind power steel, which comprises the following steps: sequentially adding aluminum blocks, high-carbon ferromanganese, a cleaning promoter, lime and fluorite into a steel ladle in the tapping process of the converter smelting process to ensure slag layer thickness, slag making alkalinity and slag making viscosity, supplementing lime and bauxite for slag adjustment in the early stage of LF refining, adopting a diffusion deoxidizer consisting of aluminum beans, carbon powder and silicon carbide for diffusion deoxidization in the middle and later stages of LF refining, and controlling the final slag alkalinity of refining slag; before the steel is discharged, furnace charging is carried out on the molten steel by a calcium silicate wire, a lanthanide wire is fed after the steel is broken in the VD vacuum treatment process, the generation and quantity of inclusions in the steel are limited, the inclusion grades are improved and stabilized, the inclusion grade of the continuous casting billet A, B, C, D, DS is 1.0 grade or less, and the yield strength, the tensile strength and the fatigue life of the wind power steel are promoted to be improved.
Description
Technical Field
The invention belongs to the technical field of wind power steel, and particularly relates to a method for improving inclusion level of wind power steel.
Background
The megawatt wind generating set prepared from wind power steel has high requirements on the strength, low-temperature impact toughness, surface and internal quality of the steel due to strong long-term field service, severe environment and load and fatigue effects, and inclusions in the steel have high harm to the quality and performance of molten steel in the smelting process, so that the problems of casting blank inclusion, cracks and the like are easily caused, the damage of brittle inclusion to fatigue performance is high, the compactness and continuity of steel tissues are damaged, and therefore, the generation and quantity of inclusions in the steel are limited, and the improvement and stabilization of inclusion grades are the key for improving the wind power steel quality.
In the prior art, the steel for wind power parts generally adopts alloy structural steel, the comprehensive mechanical properties of materials are improved by adding Cr, ni, mn, si, B and other alloy elements into steel types, the steel for continuous casting is generally obtained by adopting the process flows of blast furnace, molten iron desulfurization, converter smelting, LF refining and VD/RH vacuum treatment, nonmetallic inclusions are derived from raw materials, deoxidized products, slag, refractory materials, secondary oxidation products in the casting process and the like, and the method for improving the inclusion level of the wind power steel is mainly adopted, and mainly adopts converter endpoint control, deoxidized alloy type selection, addition time and sequence, LF refining and long-time treatment of large argon gas, continuous casting protection casting and the like.
The main defects are that the viscosity and the surface tension of the slag system are large, the deoxidizing condition is poor, and the deoxidizing product Al 2 O 3 Higher melting point, class B Al 2 O 3 The volume of the inclusion is small, the aggregation and growth are difficult, the floating is difficult to enter slag, and a large amount of fine Al is remained in the steel 2 O 3 The particles have nucleation effect for the subsequent Ds inclusion formation, the submerged nozzle nodulation is easy to cause blockage and stop casting, chain CaS-based inclusions are easy to generate by using excessive silicon-calcium wires, large particle phases and fine strip phases are formed by inclusion particles with the diameter of more than 10 mu m in the rolling process, the aluminum-silicon-calcium inclusions with higher melting point and hardness are distributed in a chain manner along the processing direction to damage the uniform continuity of a matrix, and the yield strength and the tensile strength of steel are reduced to damage the fatigue life.
Secondly, the fixed gun position of the converter is adopted to blow the slag, decarburization reaction and diffusion are not facilitated, slag overflow and splashing are easy, refining deoxidization load is increased, siAlBa alloy is used for deoxidization during the process of tapping and argon blowing, and lime is adopted during the LF refining processCalcium fluoride slag formation, although rapid, silicate inclusion in steel and steel ladle refractory materials are easy to erode, ferrosilicon powder is adopted for precipitation deoxidation, slag alkalinity is reduced, fluidity becomes poor, re-drying is easy, floating of inclusions is not facilitated, and deoxidization products cause Al in slag 2 O 3 、SiO 2 The increase of the pulling speed is too high to cause the liquid level slag to be rolled and mixed, further causes larger size and irregular shape of the inclusion, and has poor yield.
In addition, the fluctuation of the LF refining liquid level is easy to cause slag rolling and secondary oxidation, oxygen can reduce the solubility of sulfur in steel, residual S in the steel reacts with Mn to generate MnS class A inclusions, slag is involved in the VD vacuum degassing process, foreign inclusions are introduced, the size of the inclusions is increased along with the extension of solidification time, grain boundaries or aggregation is easy to be biased, deformation is easy to occur along the rolling direction in the rolling process, the serious anisotropy of the steel performance is caused, and string-shaped or spherical sulfides are adverse to impact energy, so that the fatigue performance and the corrosion resistance are influenced.
Disclosure of Invention
The invention aims to solve at least one of the technical problems to a certain extent, and provides a method for improving the inclusion level of wind power steel, which limits the generation and quantity of inclusions in the steel, improves and stabilizes the inclusion grade, improves the uniform continuity of a matrix, reduces the anisotropy of the steel, and promotes the yield strength, the tensile strength and the fatigue life of the wind power steel.
The technical scheme adopted for solving the technical problems is as follows:
a method of increasing inclusion levels in wind power steel, the method comprising:
the steelmaking raw material sequentially obtains a continuous casting blank according to KR molten iron pretreatment, converter smelting, LF refining, VD vacuum treatment and continuous casting procedures;
in the converter smelting process, aluminum blocks, high-carbon ferromanganese, a cleaning promoter, lime and fluorite are sequentially added into a steel ladle in the tapping process;
the good dynamic conditions in the tapping process of the converter are utilized to carry out pre-deoxidation and slagging pre-refining so as to control the oxidizing property of molten steel top slag and release enriched free state CaO and steelAl of (C) 2 O 3 Inclusion formation of low melting point calcium aluminate 12 cao.7al 2 O 3 Meanwhile, ferromanganese is precipitated for deoxidization, mnO can shorten the reaction time of acid slag in the furnace, and the reaction time is matched with MgO to slow down the corrosion of a furnace lining, and CaF in a small amount of fluorite is adopted 2 Can lower the melting point of CaO in slag and enlarge CaO-FeO-SiO 2 The ternary phase liquid phase region of the ladle furnace is used for rapidly generating slag with enough fluidity and slag alkalinity, ensuring the thickness of a slag layer to be less than or equal to 30mm, ensuring the slag making alkalinity to be 1.8-2.2, reducing the viscosity and surface tension of a slag system, ensuring the slag making viscosity to be 0.2-0.25 Pa.s, avoiding the worsening of desulfurization power due to excessive viscosity, and avoiding the increase of the penetrability of slag to a refractory material due to excessively small viscosity so as to fully adsorb impurities and reduce the consumption of LF refining slag melting;
in the LF refining process, lime and bauxite are added in the early stage of LF refining to adjust slag, deoxidization type pre-refining slag formation is adopted to be matched with lime, the lime is melted to form slag, and Si and Mn have strong affinity with oxygen to generate SiO 2 Oxides such as MgO, feO and the like, bauxite has slag strengthening capability and can increase the oxidizing property of slag; in the middle and later stage of LF refining, a diffusion deoxidizer consisting of aluminum beans, carbon powder and silicon carbide is adopted for diffusion deoxidization, the final slag alkalinity of refined slag is 3.5-4.2, the slag is promoted to be fully contacted with molten steel, and S and Al are treated 2 O 3 Has stronger adsorption effect and avoids unstable oxide SiO caused by too low alkalinity 2 Decomposition, namely avoiding the decrease of slag fluidity and adsorption capacity caused by excessive alkalinity and increasing Ds inclusion probability;
before the molten steel is discharged, 2 kg to 3.5kg of calcium silicate wires per furnace are added to carry out weak calcium treatment on the molten steel, and the hard alumina inclusions are deformed into soft inclusions 2 CaO.3Al through the weak calcium treatment 2 O 3 ·SiO 2 The aluminum-silicon-calcium inclusion with higher melting point and higher hardness is easy to float and remove, so that the phenomenon that the uniform continuity of a matrix is damaged due to the fact that the aluminum-silicon-calcium inclusion with higher melting point and higher hardness is distributed in a chain shape along the machining direction is avoided, and the fact that excessive silicon-calcium wires generate chain-shaped CaS-based inclusions is avoided;
in the VD vacuum treatment process, lanthanum wires of 2-3m/t molten steel are fed after the vacuum breaking, the linear speed is 5-7m/min, and because La has high activity, under the existence of chemical position gradient, the concentration difference between crystal nucleus and La atoms around the crystal nucleus can generate a diffusion promotion effect, and lanthanum can be further usedThe Al in the inclusion is replaced, the blocking and stopping pouring caused by the nodulation of the immersed nozzle is avoided, and La is generated by the reaction of La and MnS 2 O 2 S, spherical lanthanum aluminate and small circular oxysulfide are generated, the anisotropy of steel is reduced, and the purity of molten steel is improved.
Further, in the KR molten iron pretreatment process, the thickness of a slag layer at the liquid level of molten iron is less than or equal to 18mm, S is less than or equal to 0.005%, the desulfurization temperature is reduced by less than or equal to 20 ℃, the dynamic conditions are good, the sulfur recovery is low, and the increase of MnS inclusion in sulfur content is further reduced.
Further, in the converter smelting process, top-bottom combined blowing is adopted, the gun position is higher than a fixed gun position by blowing according to the earlier stage of 1.1-1.4m, the middle stage of 1.3-1.7m and the later stage of 0.9-1.0m, the earlier stage and the middle stage can adapt to different blowing stages, the foam degree and the viscosity difference of slag are adopted, and the later stage adopts a low gun position, so that the slag formation and decarburization reaction diffusion are facilitated, the reaction and slag withdrawal in the converter can be stably carried out, slag overflow and splashing are avoided, and the yield is further facilitated to be improved.
Further, in the converter smelting process, the tapping target is that: p is less than or equal to 0.012%, C is less than or equal to 0.05%, S is less than or equal to 0.011%, carbon content is improved to control free oxygen content in molten steel and slag, refining deoxidization load is prevented from being increased, target temperature T is more than or equal to 1600 ℃, molten steel peroxidation is prevented, proper tapping temperature is controlled, and molten steel return P is effectively controlled.
Further, in the converter smelting process, each furnace of molten steel is 90-110t, 220-370kg of aluminum blocks, 120-220kg of high-carbon ferromanganese, 300-350kg of cleaning accelerator, 280-320kg of lime and 10-15kg of fluorite are sequentially added into a steel ladle in the tapping process, argon is blown in the whole process of converter tapping, and the flow rate of the argon is 300-500NL/min.
Further, in the LF refining process, aluminum beans, carbon powder and silicon carbide are adopted according to the mass ratio of (3-4): 1: the diffusion deoxidizer formed by the steps (1-2) is used for diffusion deoxidizing, so that the burning loss of aluminum is reduced, the slag is whitened, the white slag time is more than or equal to 23min, the smelting time is more than or equal to 44min, the inclusions are fully floated, the slag quantity is less than 4.5kg/t steel, the FeO and MnO content in the slag is less than 1.1%, the desulfurization efficiency is improved, the generation of CaS is reduced, the damage of sulfide inclusions is inhibited, the diffusion deoxidizer is added in a small amount for a plurality of batches in the middle and later stages of smelting to maintain the reducing atmosphere, and further the secondary oxidation and nitrogen increment of the slag are avoided.
Further, argon is blown in the whole process in the LF refining process; 20-100 kg lime and 2-10kg bauxite are added in the early stage of LF refining to regulate slag, the argon flow is 250-275 NL/min, and the formation of CaO-SiO with compact texture and high melting point is avoided 2 But the slag formation is hindered, the steel ladle refractory material is prevented from being corroded by fluoride, the interface tension of slag steel is low, the slag formation speed is high, the absorption and floating up to slag are facilitated, the desulfurization capability is further improved, and the deoxidation and alloying are promoted.
Further, in the LF refining process, caO and SiO in the middle of LF refining 2 Is stronger than other oxides to form CaO.SiO 2 、3CaO·2SiO 2 The alkalinity of slag is 2.5-3.0, micro-carbon ferrochrome (FeCr69C0.03), ferromolybdenum alloy (FeMo 60-C) and low-carbon ferromanganese (FeMn85C0.2) are added, mnO exists in the slag in a free state, and the fluidity of slag is promoted to lead CaO and SiO on the surface of lime 2 、3CaO·2SiO 2 Loosening, preventing back drying, maintaining medium argon strength, and argon flow of 170-230 NL/min, further improving floating force condition on the inclusions, stabilizing blowing, and reducing splashing.
Further, in the LF refining process, the argon flow is 50-90 NL/min in the later stage of LF refining, stirring and sedation are weak, slag rolling caused by the fact that molten steel is severely rolled is prevented, alloy components are precisely controlled through the process, and fluctuation of chemical components is further reduced.
Further, in the LF refining process, cerium wires of 0.5-0.6m/t molten steel are fed in the later stage of LF refining, so that easily deformed MnS inclusions are converted into high-melting-point CeS-MnS and CeS-MnS-TiS composite inclusions, the decrease of toughness caused by the MnS inclusions is avoided, the adverse effect of string-shaped or spherical sulfides on impact energy is avoided, the S content before LF outlet is less than or equal to 0.0015%, and the temperature is more than or equal to 1625 ℃.
Further, in the VD vacuum treatment process, the highest vacuum degree is controlled to be less than or equal to 67pa, the vacuum holding time is controlled to be more than or equal to 13min, H in molten steel is removed, the impurities are ensured to float upwards sufficiently, the argon soft blowing time is controlled to be more than or equal to 25min, low-carbon ferroboron is added after the vacuum treatment is finished, the element burning loss in the microalloying process is reduced, and the alloy components are controlled accurately.
Further, in the VD vacuum treatment process, the flow of bottom blowing argon is 10-20 NL/min, so that secondary oxidization of molten steel is prevented, stirring is performed by weak argon, and small bubble flow is formed, so that the inclusion is favorably wrapped and clamped to float upwards.
Further, in the VD vacuum treatment process, ferrotitanium cored wires of 0.1-0.2m/t molten steel are fed after the vacuum breaking, and micro titanium treatment is adopted to improve the toughness of a heat affected zone, so that spherical composite inclusions can be wrapped by TiN in the cooling solidification process, and the size of the inclusions is further reduced.
Furthermore, in the continuous casting process, the whole process protects casting, prevents secondary oxidation, controls the superheat degree to be between 15 and 25 ℃, controls the pulling speed to be 0.22 to 0.29m/min, and steady casting avoids liquid level slag mixing caused by overlarge pulling speed, and the inclusion of a continuous casting billet A, B, C, D, DS class is 1.0 grade or less, thereby effectively improving the inclusion level of wind power steel.
Further, two sections of water cooling are adopted to match with the electromagnetic stirring, the casting flow stirring and the end electromagnetic stirring of the crystallizer, the flow rate of the first cooling water is 4000-4150L/min, the flow rate of the first area of the second cooling water is 25-28L/min, the flow rate of the second area of the second cooling water is 49-52L/min, the electromagnetic stirring (M-EMS) current of the crystallizer is 250-270A, the frequency is 2-3Hz, the casting flow stirring (S-EMS) current is 400-430A, the frequency is 7-8Hz, the end electromagnetic stirring (F-EMS) current is 1020-1080A, the frequency is 6-8Hz, and further steady-state casting is performed to avoid liquid level slag mixing.
Compared with the prior art, the invention has the beneficial effects that:
(1) The converter smelting process adopts aluminum blocks, high-carbon ferromanganese, a cleaning promoter, lime and fluorite to form deoxidized pre-refining slag formation, so that slag with enough fluidity and slag alkalinity is quickly generated, the viscosity and surface tension of a slag system are reduced, and low-melting-point calcium aluminate 12CaO 7Al is formed 2 O 3 The aluminum bean and carbon powder and silicon carbide are adopted to form diffusion deoxidizer for diffusion deoxidization to create proper alkalinity, thereby enhancing the S and Al of the furnace 2 O 3 The adsorption of the hard alumina inclusions is changed into soft inclusions by weak calcium treatment, and the uniformity and the continuity of the matrix are improvedThe method has the advantages that chain CaS-based inclusions are prevented from being generated by excessive calcium silicate wires, lanthanum wires are used for further replacing Al in the inclusions after VD vacuum treatment and void breaking, spherical lanthanum aluminate and small circular sulfur oxide compounds are generated, the size and the number of the inclusions are reduced, the anisotropy of steel is reduced, and therefore the yield strength, the tensile strength and the fatigue life of wind power steel are promoted to be improved.
(2) The converter smelting process adopts a gun position system to adapt to different converting stages, is favorable for slagging and decarburization reaction diffusion, improves the carbon distribution amount, prevents the increase of refining deoxidization load, further controls the slag forming amount in the tapping argon blowing process and the LF refining process, avoids adopting fluoride to erode steel ladle refractory materials, and MnO exists in slag in a free state, promotes slag fluidity, prevents back drying, and steady casting avoids liquid level slag mixing caused by overlarge pulling speed, further reduces the size and irregular shape of inclusions and improves the yield.
(3) The argon blowing system in the LF refining process adopts medium argon intensity in the middle stage and weak stirring and calm in the later stage, VD vacuum treatment and weak argon stirring, further improves floating force conditions on inclusions, ensures stable blowing, reduces splashing, avoids slag rolling and secondary oxidation caused by large fluctuation of liquid level, converts easily-deformed MnS inclusions into high-melting-point composite inclusions by feeding cerium wires in the later stage of LF refining, and feeds ferrotitanium cored wires after the breakage, so that spherical composite inclusions can be wrapped by TiN in the cooling and solidification process, further reduces the size of the inclusions, avoids adverse impact energy caused by string-shaped or spherical sulfides, and further improves fatigue performance and corrosion resistance.
Detailed Description
The following detailed description of embodiments of the invention is exemplary and intended to be illustrative of the invention and not to be construed as limiting the invention.
To improve the viscosity and surface tension of slag system, the deoxidizing condition is poor, deoxidizing product Al 2 O 3 Higher melting point of class B Al 2 O 3 Inclusions and Ds-type inclusions, chain-like CaS-based inclusions generated by excessive calcium silicate wires, avoiding the formation of large particle phase and fine rod phase of inclusion particles of more than 10 mu m in the rolling process, and having higher melting point and hardnessThe aluminum-silicon-calcium inclusions are distributed in a chain manner along the processing direction so as to break the uniform continuity of the matrix.
The invention provides a method for improving inclusion level of wind power steel, which comprises the following steps: the steelmaking raw material is subjected to KR molten iron pretreatment, converter smelting, LF refining, VD vacuum treatment and continuous casting process flow to obtain a continuous casting blank;
in the converter smelting process, aluminum blocks, high-carbon ferromanganese, a cleaning promoter, lime and fluorite are sequentially added into a steel ladle in the tapping process, the thickness of a slag layer is ensured to be less than or equal to 30mm, the slag making alkalinity is 1.8-2.2, and the slag making viscosity is 0.2-0.25 Pa.s;
in the LF refining process, lime and bauxite are added in the early stage of LF refining to regulate slag, a diffusion deoxidizer consisting of aluminum beans, carbon powder and silicon carbide is adopted in the middle and later stages of LF refining to carry out diffusion deoxidization, and the alkalinity of the final slag of refining slag is 3.5-4.2; 2-3.5 kg/furnace calcium silicate wire is added before the molten steel is discharged to carry out weak calcium treatment on the molten steel;
in the VD vacuum treatment process, lanthanum wires of 2-3m/t molten steel and ferrotitanium cored wires of 0.1-0.2m/t molten steel are fed after the vacuum breaking, and the wire speed is 5-7m/min.
Further, the method comprises the following steps:
KR molten iron pretreatment: when the molten iron reaches the station, the thickness of a slag layer at the liquid level is less than or equal to 18mm, after the molten iron is stirred by KR and pre-desulfurized, the molten iron S is less than or equal to 0.005 percent, and the desulfurization temperature is reduced by less than or equal to 20 ℃;
smelting in a converter: molten iron and scrap steel raw materials of KR molten iron pretreatment are smelted by an electric furnace to obtain molten steel, wherein the scrap steel ratio=scrap steel/scrap steel+pig iron block+molten iron is less than 12%, top-bottom combined blowing is adopted, and the gun position is 1.1-1.4m in the early stage, 1.3-1.7m in the middle stage and 0.9-1.0m in the later stage;
tapping target: p is less than or equal to 0.012 percent, C is more than or equal to 0.05 percent, S is less than or equal to 0.011 percent, and the target temperature T is more than or equal to 1600 ℃;
adding 220-370kg of aluminum blocks, 120-220kg of high-carbon ferromanganese (FeMn68C7.0) and 300-350kg of cleaning promoter (CaO 53.5% and SiO) into a steel ladle in sequence during tapping at 90-110t of molten steel per furnace 2 3.5％，Al 2 O 3 34.3 percent of MgO 8.7 percent), 280-320kg of lime and 10-15kg of fluorite, ensures that the thickness of a slag layer is less than or equal to 30mm, the slag-making alkalinity is 1.8-2.2, the slag-making viscosity is 0.2-0.25 Pa.s, and the tapping process of the converterArgon is blown in the whole process, and the argon flow is 300-500NL/min;
LF refining: refining molten steel in a ladle, wherein aluminum beans, carbon powder and silicon carbide are adopted according to the mass ratio of (3-4): 1: the diffusion deoxidizer formed by the steps (1-2) is used for diffusion deoxidization, the white slag time is more than or equal to 23min, the smelting time is more than or equal to 44min, the slag discharging amount is less than 4.5kg/t steel, the FeO and MnO contents in the slag are less than 1.1%, and the final slag alkalinity of the refining slag is 3.5-4.2;
argon is kept unobstructed in the LF refining process, argon is blown in the whole process, 20-100 kg lime and 2-10kg bauxite are added in the early stage of LF refining to adjust slag, and the flow rate of the argon is 250-275 NL/min;
the temperature of a molten pool and the alkalinity of slag in the middle of LF refining are increased to 2.5-3.0, the alkalinity of slag is increased, the distribution coefficient of sulfur is improved, slag forming difficulty caused by overlarge alkalinity is avoided, micro-carbon ferrochrome (FeCr69C0.03), ferromolybdenum (FeMo 60-C) and low-carbon ferromanganese (FeMn85C0.2) are added, and the flow rate of argon is 170-230 NL/min;
argon flow is 50-90 NL/min at the later stage of LF refining, cerium wire of 0.5-0.6m/t molten steel is fed, and the linear speed is 9-12m/min;
2-3.5 kg/furnace calcium silicate wire (containing 55-65% of Si) is added before the steel is discharged to the station to perform weak calcium treatment on the molten steel, the S content is less than or equal to 0.0015% before the steel is discharged to the station, and the temperature is more than or equal to 1625 ℃;
and (3) VD vacuum treatment: vacuum treatment is carried out on molten steel in a VD station, the highest vacuum degree is controlled to be less than or equal to 67pa, the vacuum holding time is controlled to be more than or equal to 13min, the argon soft blowing time is controlled to be more than or equal to 25min, and low-carbon ferroboron (FeB 18C 0.1) is added after the vacuum treatment is finished;
in the soft blowing process, the flow rate of bottom blowing argon is 10-20 NL/min, and after the bottom blowing argon is broken, 2-3m/t of lanthanide and 0.1-0.2m/t of ferrotitanium cored wire of molten steel are fed, and the linear speed is 5-7m/min;
continuous casting: the molten steel is protected and poured through a continuous casting machine in the whole process to prevent secondary oxidation, the superheat degree is controlled to be between 15 and 25 ℃, two sections of water cooling are adopted to match with the electromagnetic stirring, the casting flow stirring and the end electromagnetic stirring of a crystallizer, the flow rate of first cooling water is 4000 to 4150L/min, the flow rate of first area of second cooling water is 25 to 28L/min, the flow rate of second area of second cooling water is 49 to 52L/min, the electromagnetic stirring (M-EMS) current of the crystallizer is 250 to 270A, the frequency is 2 to 3Hz, the casting flow stirring (S-EMS) current is 400 to 430A, the frequency is 7 to 8Hz, the end electromagnetic stirring (F-EMS) current is 1020 to 1080A, the frequency is 6 to 8Hz, the pulling speed is controlled to be 0.22 to 0.29M/min, and the continuous casting billet is obtained by cutting to a fixed length, and A, B, C, D, DS types of inclusions are controlled to be within 1.0 level or less.
The steel grades of examples 1-3, comparative example 1, comparative example 3, comparative example 6 are: 42CrMo4, which comprises the following chemical components: c:0.42%, si:0.26%, mn:0.85%, S:0.001%, P:0.0012%, cr:1.1%, ni:0.15%, mo:0.25%, the balance being Fe and unavoidable impurities.
The steel grades of examples 4-6, comparative example 2, comparative example 4, comparative example 5, comparative example 7, comparative example 8, comparative example 9 are: GCr15SiMn comprises the following chemical components: c:0.99%, si:0.22%, mn:0.36%, S:0.0011%, P:0.0012%, cr:1.43%, ni:0.15%, mo:0.05%, cu:0.15%, the balance being Fe and unavoidable impurities.
The difference between the comparative example 1 and the example 3 is that in the converter smelting process, aluminum blocks, high-carbon ferromanganese, a cleaning promoter, lime, fluorite and SiAlBa alloy are sequentially added into a ladle in the tapping process, the thickness of a slag layer is more than 30mm, the slag making alkalinity and the slag making viscosity are smaller, lime is added in the early stage of LF refining to adjust slag, a diffusion deoxidizer consisting of lime, calcium fluoride and ferrosilicon powder is adopted in the middle and later stages of LF refining to carry out diffusion deoxidization, the alkalinity of the final slag of refined slag is higher, and the strong calcium treatment is adopted before the tapping treatment, so that the lanthanide line treatment is not carried out.
The difference between the comparative example 2 and the example 6 is that in the converter smelting process, aluminum blocks, high-carbon ferromanganese, a cleaning accelerator, lime and SiAlBa alloy are sequentially added into a ladle in the tapping process, the thickness of a slag layer is more than 30mm, the slag making alkalinity and the slag making viscosity are larger, a diffusion deoxidizer consisting of lime, calcium fluoride and ferrosilicon powder is adopted in the middle and later stages of LF refining for diffusion deoxidation, the final slag alkalinity of refining slag is lower, and the strong calcium treatment is adopted before the tapping and no lanthanide line treatment is carried out.
The converter smelting slagging technical parameters of examples 1-6, comparative example 1 and comparative example 2 are shown in the following table 1:
TABLE 1
The LF refining slag-forming technical parameters of examples 1-6, comparative example 1 and comparative example 2 are shown in Table 2 below:
TABLE 2
As can be seen from the comparison of comparative example 1 and example 3, the slag forming alkalinity and slag forming viscosity are smaller, the penetration of slag into refractory material is increased, and as can be seen from the comparison of comparative example 2 and example 6, the slag forming alkalinity and slag forming viscosity are larger, the desulfurization power is deteriorated, and the deoxidization product Al is deoxidized 2 O 3 Higher melting point, class B Al 2 O 3 The volume of the inclusion is small, the aggregation and growth are difficult, the floating is difficult to enter slag, and a large amount of fine Al is remained in the steel 2 O 3 The particles have nucleation effect for the subsequent Ds inclusion formation, and are easy to cause the submerged nozzle to nodulation to cause blockage and stop casting, and the inclusion particles with the particle diameter of more than 10 mu m can reduce the yield strength and the tensile strength of the steel, damage the fatigue life and destroy the uniformity and the continuity of the matrix.
As can be seen from the comparison results of examples 1-6, comparative examples 1 and 3, comparative examples 2 and 6, the converter smelting process adopts aluminum block, high carbon ferromanganese, a cleaning accelerator, lime and fluorite to form deoxidized pre-refined slag, slag with sufficient fluidity and slag alkalinity is rapidly generated, the viscosity and surface tension of the slag system are reduced, so that impurities are fully adsorbed and LF refining slag consumption is reduced, and low-melting-point calcium aluminate 12 CaO.7Al is generated 2 O 3 The aluminum bean and carbon powder and silicon carbide are adopted to form diffusion deoxidizer for diffusion deoxidization to create proper alkalinity, thereby enhancing the S and Al of the furnace 2 O 3 The adsorption of the matrix is improved by deforming hard alumina inclusions into soft inclusions by weak calcium treatment, the matrix uniformity and continuity can be improved, chain CaS-based inclusions generated by excessive calcium silicate wires can be avoided, and Al in the inclusions is further replaced by lanthanum wires after vacuum treatment and void breaking by VD, so that spherical lanthanum aluminate and spherical lanthanum aluminate are generatedThe small circular sulfur oxides reduce the size and the number of inclusions, reduce the anisotropy of steel, enable the inclusion of continuous casting billets A, B, C, D, DS to be 1.0 grade or less, effectively improve the inclusion level of wind power steel, and further promote the improvement of the yield strength, the tensile strength and the fatigue life of the wind power steel.
Comparative example 3 differs from example 1 in that top-bottom combined blowing is adopted in the converter smelting process, and the lance position is blown according to the height of the lance position; comparative example 4 differs from example 4 in that in the converter smelting process, top-bottom combined blowing is adopted, and lance positions are blown according to the height of the lance positions which are fixed at low; comparative example 5 differs from example 6 in that the tapping target is different in the converter smelting process.
The technical parameters of the lance positions and tapping targets of the converter smelting in examples 1 to 6 and comparative examples 3 to 5 are shown in the following Table 3:
TABLE 3 Table 3
As can be seen from the comparison results of comparative examples 1 and 3 and comparative examples 4 and 4, the high blowing at the fixed lance position of the converter is unfavorable for slag formation and decarburization reaction diffusion, slag overflow and splashing are easy, refining deoxidization load is increased, and as can be seen from the comparison results of comparative examples 5 and 6, the improper control of carbon distribution amount increases refining deoxidization load and molten steel return P, which is unfavorable for inclusion level.
As can be seen from the comparison results of examples 1-6, comparative examples 1 and 3, and comparative examples 4 and 4, the converter smelting process adopts a gun position system to adapt to different converting stages, is favorable for slagging and decarburization reaction diffusion, improves the carbon distribution amount, prevents the increase of refining deoxidization load, further controls the slag forming amount in the tapping argon blowing process and the LF refining process, avoids the erosion of steel ladle refractory materials by fluoride, ensures that MnO exists in slag in a free state, promotes slag fluidity, prevents backdrying, prevents liquid level slag from being mixed due to overlarge pulling speed in steady casting, further reduces the size and shape irregularity of inclusions, and improves the yield.
Comparative example 6 differs from example 2 in that the argon regime in the LF refining process is different; comparative example 7 differs from example 5 in that the argon regime in the LF refining process is different; comparative example 8 differs from example 6 in that no cerium wire was fed.
The LF refiner argon blowing and cerium wire specifications of examples 1-6, comparative examples 6-8 are shown in Table 4 below:
TABLE 4 Table 4
As can be seen from the comparison results of comparative example 6 with example 2 and comparative example 7 with example 5, the fluctuation of the LF refining liquid level is large, slag inclusion and secondary oxidation are easy to occur, and oxygen can reduce the solubility of sulfur in steel.
As is clear from the comparison result between comparative example 8 and example 6, residual S in the steel reacts with Mn to produce a type A inclusion of MnS type.
Comparative example 9 differs from example 6 in that the VD vacuum degassing parameters are different, and the degree of superheat and pull rate are high.
Examples 1-6, comparative examples 1-2, comparative example 9, VD vacuum degassing and continuous casting parameters are shown in table 5 below:
TABLE 5
The continuous casting billets of examples 1 to 6 and comparative examples 1 to 9 were subjected to microscopic examination of the non-metallic inclusion content in steel and the standard rating chart according to the GB/T10561 standard, and the results are shown in Table 6 below:
TABLE 6
As is apparent from the comparison of the results of comparative example 9 and example 6, slag is involved in the VD vacuum degassing process, foreign inclusions are introduced, and the size of the inclusions increases with the increase of the solidification time, grain boundaries or aggregation are easily biased, and deformation is easily generated in the rolling direction during rolling, resulting in serious anisotropy of the steel properties, and string-like or spherical sulfides are disadvantageous to impact work.
As can be seen from the comparison results of examples 1-6, comparative examples 6 and 2, comparative examples 7 and 5, comparative examples 8 and 6, and comparative examples 9 and 6, the argon blowing system in the LF refining process adopts medium argon intensity in the middle period and weak stirring and calm in the later period, VD vacuum treatment and weak argon stirring are further improved on floating force conditions on inclusions, blowing is stable, splashing is reduced, slag rolling and secondary oxidation are avoided due to large fluctuation of liquid level, the easily deformed MnS inclusions are converted into high-melting-point composite inclusions by cerium wire fed in the later period of LF refining, and ferrotitanium cored wires are fed after the breakage, so that spherical composite inclusions can be wrapped by TiN in the cooling and solidification process, the size of the inclusions is further reduced, the adverse effects of string-shaped or spherical sulfides on impact work are avoided, and the fatigue performance and corrosion resistance are further improved.
The above list of detailed descriptions is only specific to practical embodiments of the present invention, and they are not intended to limit the scope of the present invention, and all equivalent embodiments or modifications that do not depart from the spirit of the present invention should be included in the scope of the present invention.
Claims (4)
1. A method of increasing inclusion levels in a wind power steel, the method comprising:
the steel-making raw material with the steel grade of 42CrMo4 or GCr15SiMn is sequentially subjected to KR molten iron pretreatment, converter smelting, LF refining, VD vacuum treatment and continuous casting to obtain a continuous casting blank;
in the converter smelting process, top-bottom combined blowing is adopted, the gun position is 1.1-1.4m in the early stage, 1.3-1.7m in the middle stage and 0.9-1.0m in the later stage, and the tapping target is that: p is less than or equal to 0.012 percent, C is more than or equal to 0.05 percent, S is less than or equal to 0.011 percent, the target temperature T is more than or equal to 1600 ℃, each furnace of molten steel is 90 to 110T, 220 to 370kg of aluminum blocks, 120 to 220kg of high-carbon ferromanganese, 300 to 350kg of cleaning accelerator, 280 to 320kg of lime and 10 to 15kg of fluorite are sequentially added into a steel ladle in the tapping process, argon is blown in the whole tapping process of a converter, the argon flow is 300 to 500NL/min, the thickness of a slag layer is less than or equal to 30mm, the slag making alkalinity is 1.8 to 2.2, and the slag making viscosity is 0.2 to 0.25 Pa.s;
in the LF refining process, aluminum beans, carbon powder and silicon carbide are adopted according to the mass ratio of (3-4): 1: the diffusion deoxidizer formed by (1-2) is used for diffusion deoxidization, the white slag time is more than or equal to 23min, the smelting time is more than or equal to 44min, the slag discharging amount is less than 4.5kg/t of steel, and the FeO and MnO contents in the slag are less than 1.1%; the final slag alkalinity of the refining slag is 3.5-4.2; argon is blown in the whole process, 20-100 kg lime and 2-10kg bauxite are added in the early stage of LF refining to adjust slag, and the flow rate of the argon is 250-275 NL/min; the alkalinity of slag in the middle stage of LF refining is 2.5-3.0, low-carbon ferromanganese is added, and the flow rate of argon is 170-230 NL/min; argon flow is 50-90 NL/min at the later stage of LF refining, and cerium wire of 0.5-0.6m/t molten steel is fed; 2-3.5 kg/furnace calcium silicate wire is added before the steel is discharged to carry out weak calcium treatment on the molten steel, the S content is less than or equal to 0.0015% before the steel is discharged from the LF, and the temperature is more than or equal to 1625 ℃;
in the VD vacuum treatment process, after the vacuum is broken, feeding a lanthanide line of 2-3m/t molten steel, wherein the line speed is 5-7m/min;
in the continuous casting process, the whole process protects casting, the superheat degree is controlled between 15 ℃ and 25 ℃, the pulling speed is controlled to be 0.22 m/min to 0.29m/min, and the class A, B, C, D, DS of the continuous casting blanks is included in the class 1.0 or less;
the steel grade is: 42CrMo4, which comprises the following chemical components: c:0.42%, si:0.26%, mn:0.85%, S:0.001%, P:0.0012%, cr:1.1%, ni:0.15%, mo:0.25% of Fe and the balance of unavoidable impurities;
the steel grade is: GCr15SiMn comprises the following chemical components: c:0.99%, si:0.22%, mn:0.36%, S:0.0011%, P:0.0012%, cr:1.43%, ni:0.15%, mo:0.05%, cu:0.15%, the balance being Fe and unavoidable impurities.
2. The method for improving the inclusion level of wind power steel according to claim 1, wherein in the KR molten iron pretreatment process, the thickness of a slag layer at the molten iron reaching a station is less than or equal to 18mm, S is less than or equal to 0.005%, and the desulfurization temperature drop is less than or equal to 20 ℃.
3. The method for improving the inclusion level of wind power steel according to claim 1, wherein in the VD vacuum treatment process, the highest vacuum degree is controlled to be less than or equal to 67pa, the vacuum holding time is controlled to be more than or equal to 13min, the argon soft blowing time is controlled to be more than or equal to 25min, the low-carbon ferroboron is added after the vacuum treatment is finished, and the ferrotitanium cored wire of molten steel with the thickness of 0.1-0.2m/t is fed after the vacuum treatment is broken.
4. The method for improving the inclusion level of wind power steel according to claim 1, wherein the flow rate of bottom blowing argon in the VD vacuum treatment process is 10-20 NL/min.
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