CN115125351A - Control method for transverse cracks of ultrathin aluminum-containing special-shaped blank - Google Patents
Control method for transverse cracks of ultrathin aluminum-containing special-shaped blank Download PDFInfo
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- CN115125351A CN115125351A CN202210539665.4A CN202210539665A CN115125351A CN 115125351 A CN115125351 A CN 115125351A CN 202210539665 A CN202210539665 A CN 202210539665A CN 115125351 A CN115125351 A CN 115125351A
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- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 41
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 41
- 238000000034 method Methods 0.000 title claims abstract description 26
- 238000005266 casting Methods 0.000 claims abstract description 71
- 238000001816 cooling Methods 0.000 claims abstract description 40
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 20
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 18
- 239000000498 cooling water Substances 0.000 claims abstract description 16
- 238000009749 continuous casting Methods 0.000 claims abstract description 10
- 238000007670 refining Methods 0.000 claims abstract description 10
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 9
- 239000000843 powder Substances 0.000 claims abstract description 9
- 238000005275 alloying Methods 0.000 claims abstract description 8
- 239000010936 titanium Substances 0.000 claims abstract description 8
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 47
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 28
- 229910000831 Steel Inorganic materials 0.000 claims description 25
- 239000010959 steel Substances 0.000 claims description 25
- 229910052786 argon Inorganic materials 0.000 claims description 14
- 238000003723 Smelting Methods 0.000 claims description 9
- 238000003756 stirring Methods 0.000 claims description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 6
- 229910052799 carbon Inorganic materials 0.000 claims description 6
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 4
- 239000005997 Calcium carbide Substances 0.000 claims description 4
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 4
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 4
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 4
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 4
- 239000007789 gas Substances 0.000 claims description 4
- 238000007654 immersion Methods 0.000 claims description 4
- 239000004571 lime Substances 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 4
- 229910052698 phosphorus Inorganic materials 0.000 claims description 4
- 239000011574 phosphorus Substances 0.000 claims description 4
- 238000011084 recovery Methods 0.000 claims description 4
- CLZWAWBPWVRRGI-UHFFFAOYSA-N tert-butyl 2-[2-[2-[2-[bis[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]amino]-5-bromophenoxy]ethoxy]-4-methyl-n-[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]anilino]acetate Chemical compound CC1=CC=C(N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)C(OCCOC=2C(=CC=C(Br)C=2)N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)=C1 CLZWAWBPWVRRGI-UHFFFAOYSA-N 0.000 claims description 4
- 230000004907 flux Effects 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 2
- 229910000616 Ferromanganese Inorganic materials 0.000 claims 1
- -1 aluminum-manganese-iron Chemical compound 0.000 claims 1
- DALUDRGQOYMVLD-UHFFFAOYSA-N iron manganese Chemical compound [Mn].[Fe] DALUDRGQOYMVLD-UHFFFAOYSA-N 0.000 claims 1
- 238000005070 sampling Methods 0.000 claims 1
- 239000002893 slag Substances 0.000 abstract description 16
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 8
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 abstract description 7
- 229910052748 manganese Inorganic materials 0.000 abstract description 7
- 239000011572 manganese Substances 0.000 abstract description 7
- 229910052742 iron Inorganic materials 0.000 abstract description 4
- 230000035945 sensitivity Effects 0.000 abstract description 3
- 238000007664 blowing Methods 0.000 description 9
- 238000009529 body temperature measurement Methods 0.000 description 7
- 238000009826 distribution Methods 0.000 description 6
- NRTOMJZYCJJWKI-UHFFFAOYSA-N Titanium nitride Chemical compound [Ti]#N NRTOMJZYCJJWKI-UHFFFAOYSA-N 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000005096 rolling process Methods 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 229910000519 Ferrosilicon Inorganic materials 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 238000010923 batch production Methods 0.000 description 3
- 230000005856 abnormality Effects 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 229910001566 austenite Inorganic materials 0.000 description 2
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229910001349 ledeburite Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 239000003209 petroleum derivative Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000010183 spectrum analysis Methods 0.000 description 1
- 238000009865 steel metallurgy Methods 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
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Classifications
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/10—Supplying or treating molten metal
- B22D11/11—Treating the molten metal
- B22D11/111—Treating the molten metal by using protecting powders
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
- B22D11/22—Controlling or regulating processes or operations for cooling cast stock or mould
- B22D11/225—Controlling or regulating processes or operations for cooling cast stock or mould for secondary cooling
-
- 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
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/06—Deoxidising, e.g. killing
-
- 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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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Continuous Casting (AREA)
Abstract
The invention discloses a control method of transverse cracks of an ultrathin special-shaped blank containing aluminum, which specifically comprises the following steps: deoxidizing by adopting aluminum, manganese and iron in a converter; feeding the titanium wire according to nitrogen components after LF refining alloying; the continuous casting process adopts a crystallizer flange single-point full-protection pouring process, round cooling water holes on the wide surface of the crystallizer are distributed at unequal intervals, the narrow surface of the crystallizer adopts asymmetric cooling water quantity, the two cooling sections adopt asymmetric cooling modes, and the covering slag adopts high-alkalinity low-viscosity covering slag. According to the invention, nitrogen is fixed by titanium, so that the sensitivity of transverse cracks of the casting blank is reduced. Meanwhile, the continuous casting cooling mode, the components of the casting powder and the consumption are optimized, the transverse crack problem of the ultrathin aluminum-containing beam blank is solved, and the one-time qualified rate of the casting blank reaches 99.72%.
Description
Technical Field
The invention belongs to the field of steel metallurgy and steel making, and particularly relates to a control method of transverse cracks of an ultrathin aluminum-containing beam blank.
Background
At present, petroleum and natural gas are important strategic materials, and in order to meet the safety requirements of buildings in extremely cold regions, some key projects put forward higher requirements on the purity, the aluminum content, the low-temperature impact property, the stability, the weldability and the like of steel, so that the ultra-thin special-shaped blank full-protection casting technology for realizing aluminum deoxidation and aluminum-containing steel production becomes a problem to be solved urgently.
The ledeburite steel beam blank continuous casting machine is a near-net-shape beam blank continuous casting machine with the thinnest web plate in the world, the thickness of the web plate is only 90mm, aiming at the problems, the production of the aluminum-containing steel is carried out by adopting a single-point full-protection casting process of a crystallizer flange, but transverse cracks still exist in the batch production process of the casting blank, the blank is required to be removed off line, and the metal yield and the production efficiency of the casting blank are reduced. The method overcomes the problems, continuously optimizes the ultra-thin beam blank full-protection casting technology, and has important significance for upgrading the beam blank variety and improving the production efficiency.
Therefore, a method for controlling the transverse cracks of the ultra-thin aluminum-containing beam blank, which can overcome the above problems, is needed.
Disclosure of Invention
The invention aims to overcome the problems and provide a method for controlling transverse cracks of an ultrathin aluminum-containing special blank. According to the invention, nitrogen is fixed by titanium, so that the sensitivity of transverse cracks of the casting blank is reduced. Meanwhile, the continuous casting cooling mode, the components of the covering slag and the consumption are optimized, the quality stability of the ultrathin aluminum-containing profiled blank is improved, the problem of transverse cracks of the ultrathin aluminum-containing profiled blank is solved, and the one-time qualified rate of the casting blank reaches 99.72%.
In order to achieve the purpose, the invention adopts the following technical scheme:
1. smelting in a converter
Smelting by a top-bottom combined blown converter, wherein the steel ladle adopts a red clean steel ladle with good bottom blowing, and the baking temperature is more than or equal to 800 ℃.
Deoxidizing by adopting aluminum, manganese and iron, wherein the addition amount is 2.0-2.5 kg/t steel.
The converter draws carbon once and uniformly, and the end point phosphorus is controlled to be 0.011 percent to 0.015 percent.
The sliding plate is adopted for automatically blocking slag, the slag discharging amount is strictly controlled, and the synthetic slag is added along with the steel flow according to 800-820 kg/furnace.
2. LF refining
After refining, adding 80-160 kg of calcium carbide, 530-640 kg of lime and 10-30 kg of aluminum particles into a furnace for deoxidation and slagging, and simultaneously stirring with argon gas at the pressure of 0.8-1.2 MPa for 1-2 min.
After the first sample is refined, alloying is carried out according to the component requirements of steel, ferrosilicon, medium manganese and other alloys are added, then an aluminum wire is fed into a furnace at the speed of 150-180 m/s, the wire feeding speed is 2.0-4.0 m/s, the argon pressure is 0.8-1.6 MPa, and the stirring time is 2-3 min.
And feeding a second sample into a titanium wire according to nitrogen components after alloying, calculating the wire feeding amount according to 70-75% of titanium recovery rate under the condition of ensuring that the titanium-nitrogen ratio is 3-3.42, wherein the wire feeding speed is 3.0-4.5 m/s, and the argon pressure is controlled according to 0.3-0.4 MPa when the titanium wire is fed.
And soft blowing is carried out under low pressure before the station is out, and the soft argon blowing time is more than 15 min.
3. Continuous casting
1) At present, two water gaps are commonly used for introducing molten steel into a crystallizer from a tundish, and no matter a two-point semi-open and two-point sleeve protection casting process is adopted, the batch production of aluminum-containing special-shaped blanks cannot be realized. The invention adopts a crystallizer flange single-point full-protection pouring process, namely, a single water gap is arranged at the joint of the flange and the web to introduce molten steel into the crystallizer from a tundish, so that full-protection pouring can be realized, and the requirement of batch production of aluminum-containing special-shaped blanks is met.
2) According to a field casting blank surface temperature measurement test, a crystallizer flange single-point full-protection pouring process is adopted according to the fact that the difference of the transverse temperature distribution of the broad surface of an aluminum-containing special-shaped blank produced in an original equidistant cooling mode of a crystallizer is large, the transverse temperature of the casting blank after secondary cooling is distributed at 600-1150 ℃, a high-temperature area is concentrated at the inner edge, the lowest temperature is at the flange, the difference of the transverse temperature distribution is large, and the temperature of a pouring side is 40-100 ℃ higher than that of a non-pouring side. Meanwhile, the casting blank is cooled twice and then enters a section of air cooling area before straightening, the temperature return phenomenon exists, according to the field temperature measurement, the temperature return of the inner edge and the web plate can be ignored, and the flange temperature return is 80-120 ℃. The transverse temperature distribution of the wide surface of the casting blank is not uniform, and transverse thermal stress is generated, which is one of important reasons for forming transverse cracks; meanwhile, the temperature of the casting blank flange after being cooled back is in a third brittle zone, which is also one of the reasons for the generation of corner transverse cracks.
The invention adopts an asymmetric cooling mode, designs the distribution of wide-surface cooling water holes of the crystallizer, the water quantity of the narrow surface of the crystallizer and the water quantity of secondary cooling water, improves the temperature uniformity of the aluminum-containing beam blank and avoids the third brittleness area of the casting blank.
The specific embodiment is as follows:
the water quantity of the wide surface of the crystallizer is kept to be 1600-1610L/min, the circular cooling water holes of the wide surface are distributed at unequal intervals, the interval between two adjacent water holes at the wing tip is 18-19mm, the interval between two adjacent water holes at the large R angle of the inner edge is 7-8mm, and the interval between two adjacent water holes at the web plate is kept to be 10-11 mm.
The narrow surface of the crystallizer adopts asymmetric cooling water quantity, the water quantity of the narrow surface of the casting side is increased to 1000-1100L/min, and the water quantity of the narrow surface of the non-casting side is reduced to 800-900L/min;
the second cooling section adopts an asymmetric cooling mode, and the water quantity of the second cooling section is kept unchanged from 230L/min to 235L/min; the water amount of the narrow surface of the non-casting side from the second cooling second section to the fifth cooling section is kept unchanged and is respectively 179-183L/min, 85-90L/min, 40-43L/min and 20-24L/min, and the water amount of the narrow surface of the non-casting side from the second cooling second section to the fifth cooling section is increased by 10% -20% on the basis of the non-casting side.
3) Transverse cracks are found to be easy to appear at the bottom of the vibration marks in the production process, and the deeper the vibration marks are, the higher the probability of the occurrence of the transverse cracks is. The chatter mark was formed due to the formation of the primary shell under the periodic pressure of the mold flux during the continuous casting. Therefore, the invention adopts the high-alkalinity low-viscosity covering slag which comprises the following components in percentage by weight: SiO 2 2 27.6～29.5％；CaO 38.7～40.1％；Al 2 O 3 5.9-7.25%; 1.72 to 2.95 percent of MgO; 12.6-14.8% of TC; the alkalinity is 1.3-1.5; the viscosity is 0.45-0.55. The addition amount of the casting side casting powder is 1.3-1.4 kg/m 2 The addition amount of the non-casting side casting powder is 1.1-1.2 kg/m 2 。
4) The immersion depth of the water gap is 50-60 mm, the superheat degree of the tundish is controlled according to 20-30 ℃, and the pulling speed is 0.95-1.05 m/min.
The web plate of the ultrathin aluminum-containing special-shaped blank disclosed by the invention is only 90mm in thickness.
Compared with the prior art, the invention has the advantages that:
1. the method is based on the mechanism that the transverse cracks of the aluminum-containing beam blank occur, finds out the influencing factors generated by the transverse cracks of the ultrathin aluminum-containing beam blank through metallographic analysis, scanning electron microscope analysis, energy spectrum analysis and casting blank surface temperature measurement test, fundamentally solves the generation of the transverse cracks of the aluminum-containing beam blank through microstructure control, precipitate control, oscillation mark control and casting blank surface temperature uniformity control, and improves the metal yield of the casting blank.
2. According to the invention, the method adopts accurate nitrogen control, and simultaneously controls a proper titanium-nitrogen ratio to dynamically feed a titanium wire according to the content of N, so that titanium nitride is formed at a high temperature, austenite crystal boundaries are pinned, an austenite structure is refined, and the sensitivity of transverse cracks of a casting blank is reduced.
3. According to the invention, thermodynamics and kinetics of second phase precipitation are combined, nitrogen is fixed by titanium, the generation of an aluminum nitride second phase by an aluminum-containing beam blank is reduced, and the phenomenon of casting blank thermoplasticity deterioration caused by aluminum nitride gathering at a crystal boundary is reduced.
4. According to the invention, the transverse temperature uniformity of the aluminum-containing beam blank is improved by optimizing the arrangement of cooling water holes on the wide surface of the crystallizer, the water quantity on the narrow surface of the crystallizer and the water quantity of secondary cooling water, and meanwhile, the aluminum-containing beam blank enters the third brittleness area of the casting blank in the straightening stage, so that a good effect of controlling the transverse cracks of the aluminum-containing beam blank is achieved.
5. According to the invention, by optimizing the components and consumption of the covering slag, the shape of the vibration mark is effectively improved, and the occurrence position of transverse cracks is reduced.
Drawings
FIG. 1 is a sectional view of an H-shaped steel of the present invention;
FIG. 2 is a temperature cloud chart of a casting blank cooled twice in embodiment 1 of the invention;
FIG. 3 is a transverse temperature measurement experiment result after a casting blank is cooled twice in embodiment 1 of the invention;
FIG. 4 is a temperature cloud chart of a casting blank after secondary cooling in example 2 of the present invention;
FIG. 5 shows the results of the transverse temperature measurement experiment after the casting blank is cooled twice in example 2 of the present invention.
Detailed Description
The present invention will be further described with reference to the following specific examples.
Example 1
The smelting steel is S355NL-1, the aluminum content is required to be 0.015-0.035%, and the section size is 555 x 440 x 90 mm.
Smelting in a converter: smelting in a top-bottom combined blown converter, wherein the steel ladle adopts a red clean steel ladle with good bottom blowing, and the baking temperature is 810 ℃. The aluminum, manganese and iron are adopted for deoxidation, and the addition amount is 2.05kg/t steel. The converter draws carbon once uniformly, the end point carbon is controlled at 0.056%, and the end point phosphorus is controlled at 0.012%. The sliding plate is adopted to automatically block slag, the slag discharge amount is strictly controlled, and the synthetic slag is added along with the steel flow according to 800 kg/furnace.
LF refining:
after refining, adding 90kg of calcium carbide, 535kg of lime and 17kg of aluminum particles into the furnace for deoxidation and slagging, and simultaneously stirring by adopting big argon gas with the pressure of 1.0MPa for 1.5 min. After the first sample is refined, alloying is carried out according to the component requirements of steel, ferrosilicon, medium manganese and other alloys are added, then an aluminum wire is fed into a furnace at a wire feeding speed of 2.5m/s and an argon pressure of 1.2MPa, and the stirring time is 3 min. And taking a second sample after alloying, determining the nitrogen content by the spectrum to be 40ppm, calculating the wire feeding amount according to the titanium recovery rate of 75% under the condition of ensuring that the titanium-nitrogen ratio is 3.42, then feeding a titanium wire into a furnace at a wire feeding speed of 3.5m/s, and controlling the argon pressure when feeding the titanium wire according to 0.3 MPa. And soft blowing is carried out under low pressure before the station is out, and the soft argon blowing time is more than 15 min.
Continuous casting:
the water quantity of the wide surface of the crystallizer is 1600L/min, the circular cooling water holes of the inner arc and the outer arc of the wide surface are distributed at unequal intervals, the distance between two adjacent water holes at the wing tip is 18mm, the distance between two adjacent water holes at the large R angle of the inner edge is 8mm, and the distance between two adjacent water holes of the web plate is kept to be 10 mm. The narrow surface of the crystallizer adopts asymmetric cooling water quantity, the water quantity of the narrow surface of the casting side is increased to 1050L/min, and the water quantity of the narrow surface of the non-casting side is reduced to 850L/min. The second cooling section adopts an asymmetric cooling mode, and the water amount of the second cooling section and the first cooling section is 230L/min; the water amount of the non-casting side narrow surface from the second cooling section to the fifth cooling section is 181L/min, 86L/min, 40L/min and 24L/min respectively, and the water amount of the casting side narrow surface is increased by 15 percent on the basis of the water amount of the non-casting side.
Using high-basicity low-viscosity covering slag, SiO 2 27.9％；CaO 40.1％；Al 2 O 3 6.21 percent; 1.83 percent of MgO; 12.9 percent of TC; alkalinity of 1.43; viscosity 0.48. The addition amount of casting side casting powder is 1.3kg/m 2 The addition amount of the non-casting side casting powder is 1.15kg/m 2 。
The immersion depth of the water gap is 55mm, the superheat degree of the tundish is controlled according to 24 ℃, and the pulling speed is 1.0 m/min.
According to an on-site casting blank surface temperature measurement test, the wide-surface transverse temperature of the aluminum-containing special-shaped blank after secondary cooling is distributed at 750-1100 ℃, the casting blank temperature is 890-1100 ℃ during straightening, the wide-surface transverse temperature is distributed uniformly, and a third brittle zone is avoided. And (4) inspecting all the casting blanks on the ground, wherein no transverse crack is found on the surfaces of the casting blanks, and no abnormality occurs after the casting blanks are sent to a rolling mill for rolling.
Example 2
The smelting steel grade is C345-5B, the aluminum content is required to be 0.02-0.03%, and the section size is 555 x 440 x 90 mm.
Smelting in a converter: smelting in a top-bottom combined blown converter, wherein the steel ladle adopts a red clean steel ladle with good bottom blowing, and the baking temperature is 820 ℃. The aluminum, manganese and iron are adopted for deoxidation, and the addition amount is 2.18kg/t steel. The converter draws carbon once, the end point carbon is controlled at 0.061%, and the end point phosphorus is controlled at 0.013%. The sliding plate is adopted to automatically block slag, the slag discharging amount is strictly controlled, and the synthetic slag is added along with the steel flow according to 810 kg/furnace.
LF refining:
after refining, adding 120kg of calcium carbide, 556kg of lime and 25kg of aluminum particles into the furnace for deoxidation and slagging after the refining is finished, and simultaneously stirring the mixture by adopting big argon gas with the pressure of 1.1MPa for 2 min. After the first sample is refined, alloying is carried out according to the component requirements of steel, ferrosilicon, medium manganese and other alloys are added, then an aluminum wire is fed into a furnace at the speed of 170 m/s, the wire feeding speed is 3.0m/s, the argon pressure is 1.25MPa, and the stirring time is 2.5 min. Taking a second sample after alloying, determining the nitrogen content by spectrum to be 35ppm, calculating the wire feeding amount according to the titanium recovery rate of 75 percent under the condition of ensuring the titanium-nitrogen ratio to be 3.42, then feeding a titanium wire into a furnace at a wire feeding speed of 4.0m/s, and controlling the argon pressure when feeding the titanium wire according to 0.35 MPa. And soft blowing is carried out under low pressure before the station is out, and the soft argon blowing time is longer than 15 min.
Continuous casting:
the water level of the wide surface of the crystallizer is 1600L/min, the circular cooling water holes of the inner arc and the outer arc are arranged at unequal intervals, the interval between two adjacent water holes at the wing tip is 18mm, the interval between two adjacent water holes at the large R angle of the inner edge is 8mm, and the interval between two adjacent water holes of the web plate is kept to be 10 mm. The narrow surface of the crystallizer adopts asymmetric cooling water quantity, the water quantity of the narrow surface of the casting side is increased to 1100L/min, and the water quantity of the narrow surface of the non-casting side is reduced to 900L/min. The second cooling section adopts an asymmetric cooling mode, and the water amount of the second cooling section and the first cooling section is 230L/min; the water amount of the non-casting side narrow surface from the second cooling section to the fifth cooling section is respectively 182L/min, 87L/min, 42L/min and 22L/min, and the water amount of the casting side narrow surface is increased by 17 percent on the basis of the water amount of the non-casting side.
Using high-basicity low-viscosity covering slag, SiO 2 28.5％；CaO 39.8％；Al 2 O 3 6.92 percent; 2.01 percent of MgO; 13.2 percent of TC; alkalinity of 1.4; viscosity 0.5. The addition amount of casting side casting powder is 1.4kg/m 2 The addition amount of non-casting side casting powder is 1.12kg/m 2 。
The immersion depth of the water gap is 58mm, the superheat degree of the tundish is controlled according to 25 ℃, and the pulling speed is 1.05 m/min.
According to the surface temperature measurement test of the cast blank on site, the transverse temperature distribution of the wide surface of the aluminum-containing special-shaped blank after secondary cooling is 750-1060 ℃, the temperature of the cast blank during straightening is 885-1065 ℃, the transverse temperature distribution of the wide surface is more uniform, and the third brittle zone is avoided. And (4) inspecting all the casting blanks on the ground, wherein no transverse crack is found on the surfaces of the casting blanks, and no abnormality occurs after the casting blanks are sent to a rolling mill for rolling.
The method can be realized by upper and lower limit values of intervals of process parameters (such as temperature, time and the like) and interval values, and embodiments are not listed.
Conventional technical knowledge in the art can be used for the details which are not described in the present invention.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and are not limited. Although the present invention has been described in detail with reference to the embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (9)
1. A method for controlling transverse cracks of an ultrathin aluminum-containing special-shaped blank comprises the following steps:
1) smelting in a converter: deoxidizing by adopting aluminum-manganese-iron, uniformly drawing carbon in the converter for the second time, and controlling the end point phosphorus to be 0.011-0.015%;
2) LF refining: sampling after alloying, and feeding a titanium wire;
3) continuous casting: adopting a crystallizer flange single-point full-protection pouring process, wherein wide-surface circular cooling water holes are distributed at unequal intervals;
the narrow surface of the crystallizer adopts asymmetric cooling water amount;
the second cooling section adopts an asymmetric cooling mode.
2. The control method according to claim 1, wherein the amount of the ferromanganese added in the step 1) is 2.0-2.5 kg/t of steel.
3. The control method according to claim 1, wherein in the step 2), after the refining station, 80 to 160kg of calcium carbide, 530 to 640kg of lime and 10 to 30kg of aluminum particles are added into the furnace for deoxidation and slagging, and the mixture is stirred by using argon gas with the pressure of 0.8 to 1.2MPa and the stirring time of 1 to 2 min.
4. The control method according to claim 1, wherein in the step 2), the amount of the titanium wire is calculated according to the recovery rate of 70-75% of titanium under the condition that the ratio of titanium to nitrogen is 3-3.42, the wire feeding speed of the titanium wire is 3.0-4.5 m/s, and the argon pressure when the titanium wire is fed is 0.3-0.4 MPa.
5. The control method according to claim 1, wherein in the step 3), the amount of water in the wide surface of the crystallizer is 1600-1610L/min, the circular cooling water holes in the wide surface are arranged at unequal intervals, the interval between two adjacent water holes at the wing tip is 18-19mm, the interval between two adjacent water holes at the large R angle of the inner edge is 7-8mm, and the interval between two adjacent water holes at the web plate is 10-11 mm.
6. The control method according to claim 1, wherein the step 3) of using asymmetric cooling water amount for the narrow side of the crystallizer comprises the following steps: the water amount of the narrow surface of the casting side is increased to 1000-1100L/min, and the water amount of the narrow surface of the non-casting side is reduced to 800-900L/min.
7. The control method according to claim 1, wherein in the step 3), the asymmetric cooling mode adopted by the second cooling section comprises the following steps: the water amount of the secondary cooling and primary cooling is 230-235L/min; the water amount of the narrow surface of the non-casting side from the second cooling second section to the fifth cooling section is 179-183L/min, 85-90L/min, 40-43L/min and 20-24L/min respectively, and the water amount of the narrow surface of the non-casting side from the second cooling second section to the fifth cooling section is increased by 10% -20% on the basis of the non-casting side.
8. The control method according to claim 1, wherein in the step 3), a high basicity low viscosity mold flux is used, and the high basicity low viscosity mold flux comprises, in weight percent: SiO 2 2 27.6～29.5％；CaO 38.7～40.1％；Al 2 O 3 5.9-7.25%; 1.72 to 2.95 percent of MgO; 12.6-14.8% of TC; alkalinity is 1.3-1.5; the viscosity is 0.45-0.55; the addition amount of the casting side casting powder is 1.3-1.4 kg/m 2 The addition amount of the non-casting side casting powder is 1.1-1.2 kg/m 2 。
9. The control method according to claim 1, wherein in the step 3), the immersion depth of the nozzle is 50-60 mm, the superheat degree of the tundish is controlled at 20-30 ℃, and the pulling speed is 0.95-1.05 m/min.
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