CN115125351B - 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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- CN115125351B CN115125351B CN202210539665.4A CN202210539665A CN115125351B CN 115125351 B CN115125351 B CN 115125351B CN 202210539665 A CN202210539665 A CN 202210539665A CN 115125351 B CN115125351 B CN 115125351B
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- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 40
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 40
- 238000000034 method Methods 0.000 title claims abstract description 18
- 238000005266 casting Methods 0.000 claims abstract description 51
- 238000001816 cooling Methods 0.000 claims abstract description 34
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 18
- 239000002893 slag Substances 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 11
- 239000010936 titanium Substances 0.000 claims abstract description 11
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 11
- 238000007670 refining Methods 0.000 claims abstract description 9
- 238000005275 alloying Methods 0.000 claims abstract description 8
- 229910000616 Ferromanganese Inorganic materials 0.000 claims abstract description 4
- DALUDRGQOYMVLD-UHFFFAOYSA-N iron manganese Chemical compound [Mn].[Fe] DALUDRGQOYMVLD-UHFFFAOYSA-N 0.000 claims abstract description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 45
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 36
- 229910000831 Steel Inorganic materials 0.000 claims description 19
- 239000010959 steel Substances 0.000 claims description 19
- 229910052786 argon Inorganic materials 0.000 claims description 18
- 238000003756 stirring Methods 0.000 claims description 11
- 238000003723 Smelting Methods 0.000 claims description 9
- NRTOMJZYCJJWKI-UHFFFAOYSA-N Titanium nitride Chemical compound [Ti]#N NRTOMJZYCJJWKI-UHFFFAOYSA-N 0.000 claims description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 5
- 229910052799 carbon Inorganic materials 0.000 claims description 5
- 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 group [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 4
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 4
- 230000004907 flux Effects 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
- 230000001681 protective effect Effects 0.000 claims description 2
- -1 aluminum-manganese-iron Chemical compound 0.000 claims 1
- 238000005070 sampling Methods 0.000 claims 1
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 abstract description 14
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 7
- 239000000843 powder Substances 0.000 abstract description 6
- 230000008569 process Effects 0.000 abstract description 3
- 230000035945 sensitivity Effects 0.000 abstract description 3
- 238000012797 qualification Methods 0.000 abstract description 2
- 238000007664 blowing Methods 0.000 description 9
- 238000009529 body temperature measurement Methods 0.000 description 7
- 238000009826 distribution Methods 0.000 description 7
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 229910000519 Ferrosilicon Inorganic materials 0.000 description 3
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 3
- 238000010923 batch production Methods 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
- 229910052748 manganese Inorganic materials 0.000 description 3
- 239000011572 manganese Substances 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
- 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
- 229910000640 Fe alloy Inorganic materials 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000009851 ferrous metallurgy Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003345 natural gas Substances 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
- 230000003595 spectral effect Effects 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000010183 spectrum analysis Methods 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 239000002352 surface water Substances 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
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
Landscapes
- 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 for transverse cracks of an ultrathin aluminum-containing special-shaped blank, which specifically comprises the following steps: the converter adopts aluminum ferromanganese for deoxidization; after LF refining alloying, feeding titanium wires according to nitrogen components; the continuous casting process adopts a single-point full-protection casting process of a flange of a crystallizer, wide circular cooling water holes of the crystallizer are distributed in unequal intervals, the narrow surface of the crystallizer adopts asymmetric cooling water quantity, the second cooling section adopts an asymmetric cooling mode, and the covering slag adopts high-alkalinity low-viscosity covering slag. According to the invention, nitrogen is fixed through titanium, so that the sensitivity of transverse cracks of the casting blank is reduced. Meanwhile, the continuous casting cooling mode, the casting powder components and the consumption are optimized, the problem of transverse cracks of the ultrathin aluminum-containing special-shaped blank is solved, and the primary qualification rate of the casting blank reaches 99.72%.
Description
Technical Field
The invention belongs to the field of ferrous metallurgy steelmaking, and particularly relates to a control method for transverse cracks of an ultrathin aluminum-containing special-shaped blank.
Background
At present, petroleum and natural gas are important strategic materials, and in order to meet the safety requirements of buildings in extremely high and cold areas, some key projects put higher requirements on steel purity, aluminum content, low-temperature impact performance, stability, weldability and the like, so that the ultra-thin special-shaped blank full-protection casting technology for realizing aluminum deoxidization and aluminum-containing steel production becomes a problem to be solved urgently.
The lye special-shaped blank continuous casting machine is a near-net special-shaped blank continuous casting machine with the thinnest web plate in the world, the thickness of the web plate is only 90mm, the crystallizer flange single-point full-protection casting technology is adopted to produce aluminum-containing steel aiming at the problems, but transverse cracks of casting blanks still exist in the batch production process, the blanks are required to be removed in a descending mode, and the metal yield and the production efficiency of the casting blanks are reduced. Overcomes the problems, continuously optimizes the ultra-thin special-shaped blank full-protection casting technology, and has important significance for upgrading special-shaped blank varieties and improving production efficiency.
Therefore, there is a need for a method of controlling transverse cracks in ultra-thin aluminum-containing green articles that overcomes the above-described problems.
Disclosure of Invention
The invention aims to overcome the problems and provide a control method for transverse cracks of an ultrathin aluminum-containing special-shaped blank. According to the invention, nitrogen is fixed through titanium, so that the sensitivity of transverse cracks of the casting blank is reduced. Meanwhile, the continuous casting cooling mode, the casting powder components and the consumption are optimized, the stability of the quality of the ultrathin aluminum-containing special-shaped blank casting blank is improved, the problem of transverse cracks of the ultrathin aluminum-containing special-shaped blank is solved, and the one-time qualification rate of the casting blank reaches 99.72%.
In order to achieve the above purpose, the invention adopts the following technical scheme:
1. converter smelting
Smelting by adopting a top-bottom combined blown converter, wherein a ladle adopts a red clean ladle with good bottom blowing, and the baking temperature is more than or equal to 800 ℃.
Deoxidizing with Al-Mn-Fe alloy in the amount of 2.0-2.5 kg/t steel.
The converter is carbon-pulled once, and the terminal phosphorus is controlled to be 0.011-0.015%.
The sliding plate is adopted to automatically block slag, the slag discharging amount is strictly controlled, and synthetic slag is added along with the steel flow according to 800-820 kg/furnace.
2. LF refining
After refining and entering a station, 80-160 kg/furnace of calcium carbide, 530-640 kg/furnace of lime and 10-30 kg/furnace of aluminum particles are added for deoxidization and slagging, and meanwhile, large argon is adopted for stirring, the argon pressure is 0.8-1.2 MPa, and the stirring time is 1-2 min.
Alloying according to the component requirement of the steel grade after the first sample is refined, adding ferrosilicon, medium manganese and other alloys, then feeding aluminum wires 150-180 m/furnace, feeding wire speed 2.0-4.0 m/s, argon pressure 0.8-1.6 MPa, and stirring for 2-3 min.
Taking a second sample after alloying, feeding titanium wires according to nitrogen components, calculating wire feeding quantity according to 70-75% of titanium recovery rate under the condition of ensuring the titanium-nitrogen ratio to be 3-3.42, and controlling the wire feeding speed to be 3.0-4.5 m/s and the argon pressure to be 0.3-0.4 MPa during feeding the titanium wires.
And soft blowing with small pressure is adopted before the station is out, and the soft argon blowing time is longer than 15min.
3. Continuous casting
1) At present, two water gaps are commonly used for introducing molten steel into a crystallizer from a tundish by a special-shaped blank continuous casting machine, and no matter a two-point semi-open two-point sleeve protection casting process is adopted, batch production of aluminum-containing special-shaped blanks can not be realized. The invention adopts the single-point full-protection casting technology of the flange of the crystallizer, namely, a single water gap is arranged at the joint of the flange and the web plate to introduce molten steel into the crystallizer from a tundish, thereby realizing full-protection casting and meeting the batch production of aluminum-containing special-shaped blanks.
2) According to the on-site casting blank surface temperature measurement test, the wide-face transverse temperature distribution difference of the aluminum-containing special-shaped blank produced by adopting a crystallizer flange single-point full-protection casting process according to the original equidistant cooling mode of the crystallizer is larger, the transverse temperature distribution of the casting blank after secondary cooling is 600-1150 ℃, a high-temperature area is concentrated at the inner edge, the lowest temperature is at the flange, the transverse temperature distribution difference is large, and meanwhile, the temperature of the casting side is 40-100 ℃ higher than that of the non-casting side. Meanwhile, the casting blank has a temperature return phenomenon in a first section of air cooling area before secondary cooling and straightening, the temperature return of the inner edge and the web plate is negligible according to the on-site temperature measurement, and the temperature return of the flange is 80-120 ℃. The transverse temperature distribution of the broad surface of the casting blank is uneven, and transverse thermal stress is generated, which is one of the important reasons for the formation of transverse cracks; meanwhile, the temperature of the casting blank flange after the temperature is returned is in a third brittle zone, which is also one of the reasons for the occurrence of the transverse crack of the corner.
According to the invention, an asymmetric cooling mode is adopted, the wide-surface cooling water hole distribution of the crystallizer, the narrow-surface water quantity of the crystallizer and the secondary cooling water quantity are designed, the temperature uniformity of the aluminum-containing special-shaped blank is improved, and the third brittle zone of the casting blank is avoided.
The specific embodiment is as follows:
the wide water volume of the crystallizer is kept to be 1600-1610L/min, the wide circular cooling water holes are distributed at unequal intervals, the distance between two adjacent water holes on the wing tips is 18-19mm, the distance between two adjacent water holes on the inner edge with a large R angle is 7-8mm, and the distance between two adjacent water holes on the web plate is kept to be 10-11mm.
The narrow surface of the crystallizer adopts asymmetric cooling water quantity, the water quantity of the narrow surface on the pouring side is increased to 1000-1100L/min, and the water quantity of the narrow surface on the non-pouring side is reduced to 800-900L/min;
the second cooling section adopts an asymmetric cooling mode, and the water quantity of the first cooling section is kept constant at 230-235L/min; the water quantity of the narrow surface of the non-pouring side of the second cooling two sections to the fifth section is kept unchanged and is respectively 179 to 183L/min, 85 to 90L/min, 40 to 43L/min and 20 to 24L/min, and the water quantity of the narrow surface of the pouring side of the second cooling two sections to the fifth section is increased by 10 to 20 percent on the basis of the non-pouring side.
3) In the production process, transverse cracks are found to easily appear at the bottom of the vibration mark, and the deeper the vibration mark is, the larger the probability of transverse cracks. The formation of the vibration mark is due to the formation of the green shell under the periodical pressure of the mold flux during the continuous casting. For this purpose, the invention adopts high alkalinity low viscosity covering slagThe high-alkalinity low-viscosity mold flux comprises the following components in percentage by weight: siO (SiO) 2 27.6～29.5％；CaO 38.7～40.1％；Al 2 O 3 5.9 to 7.25 percent; mgO 1.72-2.95%; 12.6 to 14.8 percent of TC; alkalinity is 1.3-1.5; the viscosity is 0.45-0.55. The addition amount of the casting side covering slag is 1.3-1.4 kg/m 2 The addition amount of the non-pouring side protective slag 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 at 20-30 ℃, and the pulling speed is 0.95-1.05 m/min.
The thickness of the web plate of the ultrathin aluminum-containing special-shaped blank is only 90mm.
Compared with the prior art, the invention has the advantages that:
1. according to the invention, from the mechanism of appearance of the transverse cracks of the aluminum-containing special-shaped blank, the influencing factors of the transverse cracks of the ultrathin aluminum-containing special-shaped blank are found out through metallographic analysis, scanning electron microscope analysis, energy spectrum analysis and casting blank surface temperature measurement test, and the occurrence of the transverse cracks of the aluminum-containing special-shaped blank is fundamentally solved through microstructure control, precipitate control, vibration mark control and casting blank surface temperature uniformity control, so that the metal yield of the casting blank is improved.
2. According to the invention, accurate nitrogen control is adopted, meanwhile, a proper titanium-nitrogen ratio is controlled according to the N content, a titanium nitride is formed in a high-temperature state, an austenite grain boundary is pinned, an austenite structure is refined, and the sensitivity of transverse cracks of a casting blank is reduced.
3. The invention combines the thermodynamics and dynamics of second phase precipitation, adopts titanium to fix nitrogen, reduces the generation of aluminum nitride second phase from aluminum-containing special-shaped blank, and reduces the deterioration of casting blank thermoplasticity caused by the aggregation of aluminum nitride at the grain boundary.
4. According to the invention, through optimizing the arrangement of the wide cooling water holes of the crystallizer, the water quantity of the narrow surface of the crystallizer and the water quantity of the secondary cooling water, the transverse temperature uniformity of the aluminum-containing special-shaped blank is improved, and meanwhile, the straightening stage is avoided from entering the third brittle zone of the casting blank, so that the good effect of controlling the transverse cracks of the aluminum-containing special-shaped blank is achieved.
5. According to the invention, through optimizing the composition and consumption of the covering slag, the shape of vibration marks is effectively improved, and the occurrence positions of transverse cracks are reduced.
Drawings
FIG. 1 is a cross-sectional view of an H-beam of the present invention;
FIG. 2 is a temperature cloud chart of a casting blank after secondary cooling in embodiment 1 of the invention;
FIG. 3 shows the results of a transverse temperature measurement experiment of a casting blank after secondary cooling in example 1 of the present invention;
FIG. 4 is a temperature cloud chart of a casting blank subjected to secondary cooling in embodiment 2 of the invention;
FIG. 5 shows the result of the transverse temperature measurement experiment of the cast slab of example 2 of the present invention after secondary cooling.
Detailed Description
The invention will be further illustrated with reference to 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 90mm.
Smelting in a converter: smelting in a top-bottom combined blown converter, wherein a ladle adopts a ladle with good bottom blowing and red purity, and the baking temperature is 810 ℃. Deoxidizing by adopting aluminum ferromanganese, wherein the addition amount is 2.05kg/t steel. The converter is pulled carbon once, the carbon end point is controlled at 0.056%, and the phosphorus end point is controlled at 0.012%. The sliding plate is adopted to automatically block slag, the slag discharging amount is strictly controlled, and synthetic slag is added along with the steel flow according to 800 kg/furnace.
LF refining:
after refining enters a station, 90 kg/furnace of calcium carbide, 535 kg/furnace of lime and 17 kg/furnace of aluminum particles are added for deoxidization and slagging, and meanwhile, large argon is adopted for stirring, the argon pressure is 1.0MPa, and the stirring time is 1.5min. After the first sample is refined, alloying according to the component requirement of the steel grade, adding ferrosilicon, medium manganese and other alloys, then feeding the alloy into an aluminum wire 162 m/furnace, wherein the wire feeding speed is 2.5m/s, the argon pressure is 1.2MPa, and the stirring time is 3min. Taking a second sample after alloying, determining the spectrum to be 40ppm, calculating the wire feeding amount according to the titanium recovery rate of 75% under the condition of ensuring the titanium-nitrogen ratio to be 3.42, then feeding the titanium wire to a furnace at the wire feeding speed of 3.5m/s, and controlling the argon pressure according to 0.3MPa during feeding the titanium wire. And soft blowing with small pressure is adopted before the station is out, and the soft argon blowing time is longer than 15min.
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 in a non-equidistant way, the distance between two adjacent water holes of the wing tip is 18mm, the distance between two adjacent water holes of the large R angle of the inner edge is 8mm, and the distance between two adjacent water holes of the web plate keeps the original arrangement unchanged to 10mm. The narrow surface of the crystallizer adopts asymmetric cooling water quantity, the water quantity of the narrow surface on the pouring side is increased to 1050L/min, and the water quantity of the narrow surface on the non-pouring side is reduced to 850L/min. The secondary cooling section adopts an asymmetric cooling mode, and the water quantity of the primary cooling section is 230L/min; the water quantity of the narrow surface on the non-pouring side of the secondary cooling two sections to the non-pouring side of the five sections is 181L/min, 86L/min, 40L/min and 24L/min respectively, and the water quantity of the narrow surface on the pouring side is increased by 15% on the basis of the water quantity on the non-pouring side.
High alkalinity low viscosity protecting slag and SiO are adopted 2 27.9％；CaO 40.1％；Al 2 O 3 6.21%; mgO 1.83%; TC 12.9%; alkalinity 1.43; viscosity 0.48. The addition amount of casting powder on the pouring side is 1.3kg/m 2 The addition amount of the casting powder on the non-pouring side 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 1.0m/min.
According to the on-site casting blank surface temperature measurement test, the broad-side 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 broad-side transverse temperature distribution is uniform, and a third brittle zone is avoided. And (3) checking the whole casting blank in a landing way, wherein transverse cracks are not found on the surface of the casting blank, and no abnormality is caused after the casting blank is rolled in a steel mill.
Example 2
The smelting steel is C345-5B, the aluminum content is required to be 0.02-0.03%, and the section size is 555 x 440 x 90mm.
Smelting in a converter: smelting in a top-bottom combined blown converter, wherein a ladle adopts a ladle with good bottom blowing and red purity, and the baking temperature is 820 ℃. Deoxidizing by adopting aluminum ferromanganese, wherein the addition amount is 2.18kg/t steel. The converter is pulled carbon once, the carbon at the end point is controlled at 0.061%, and the phosphorus at the end point 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 and entering a station, 120 kg/furnace of calcium carbide, 556 kg/furnace of lime and 25 kg/furnace of aluminum particles are added for deoxidization and slagging, and meanwhile, large argon is adopted for stirring, the argon pressure is 1.1MPa, and the stirring time is 2min. After the first sample is refined, alloying according to the component requirement of the steel grade, adding ferrosilicon, medium manganese and other alloys, then feeding aluminum wires into a 170 m/furnace, wherein the wire feeding speed is 3.0m/s, the argon pressure is 1.25MPa, and the stirring time is 2.5min. Taking a second sample after alloying, determining 35ppm of spectral nitrogen, calculating the wire feeding amount according to the titanium recovery rate of 75% under the condition of ensuring the titanium-nitrogen ratio to be 3.42, then feeding the titanium wire to a 14 m/furnace, controlling the wire feeding speed to be 4.0m/s, and controlling the argon pressure according to 0.35MPa during feeding the titanium wire. And soft blowing with small pressure is adopted before the station is out, and the soft argon blowing time is longer than 15min.
Continuous casting:
the water level of the wide surface of the crystallizer is 1600L/min, the inner arc and outer arc circular cooling water holes are distributed in a non-equidistant way, the distance between two adjacent water holes of the wing tips is 18mm, the distance between two adjacent water holes of the large R angle of the inner edge is 8mm, and the distance between two adjacent water holes of the web plate keeps the original arrangement unchanged to 10mm. The narrow surface of the crystallizer adopts asymmetric cooling water quantity, the water quantity of the narrow surface on the pouring side is increased to 1100L/min, and the water quantity of the narrow surface on the non-pouring side is reduced to 900L/min. The secondary cooling section adopts an asymmetric cooling mode, and the water quantity of the primary cooling section is 230L/min; the water quantity of the narrow surface on the non-pouring side of the secondary cooling two sections to the non-pouring side of the five sections is 182L/min, 87L/min, 42L/min and 22L/min respectively, and the water quantity of the narrow surface on the pouring side is increased by 17% on the basis of the water quantity on the non-pouring side.
High alkalinity low viscosity protecting slag and SiO are adopted 2 28.5％；CaO 39.8％；Al 2 O 3 6.92%; mgO 2.01%; TC13.2%; alkalinity 1.4; viscosity 0.5. The addition amount of casting powder on the pouring side is 1.4kg/m 2 The addition amount of the casting powder on the non-pouring side 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 1.05m/min.
According to the on-site casting blank surface temperature measurement test, the broad-side transverse temperature of the aluminum-containing special-shaped blank after secondary cooling is distributed at 750-1060 ℃, the casting blank temperature is 885-1065 ℃ during straightening, the broad-side transverse temperature distribution is uniform, and a third brittle zone is avoided. And (3) checking the whole casting blank in a landing way, wherein transverse cracks are not found on the surface of the casting blank, and no abnormality is caused after the casting blank is rolled in a steel mill.
The method can be realized by the upper and lower limit values of the interval and the interval value of the process parameters (such as temperature, time and the like), and the examples are not necessarily listed here.
The invention may be practiced without these specific details, using any knowledge known in the art.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and are not limiting. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the present invention, which is intended to be covered by the appended claims.
Claims (8)
1. A control method for transverse cracks of ultrathin aluminum-containing special-shaped blanks comprises the following steps:
1) Smelting in a converter: adopting aluminum ferromanganese for deoxidization, pulling carbon for one time in a converter, and controlling the terminal phosphorus to be 0.011% -0.015%;
2) LF refining: sampling after alloying, and feeding titanium wires;
3) Continuous casting: adopting a crystallizer flange single-point full-protection casting process, wherein wide-face circular cooling water holes are distributed in a non-equidistant manner;
the narrow surface of the crystallizer adopts asymmetric cooling water quantity;
the second cooling section adopts an asymmetric cooling mode, and the asymmetric cooling mode comprises the following steps: the water quantity of the second cooling first section is 230-235L/min; the water quantity of the narrow surfaces of the non-pouring sides of the two-cooling two-section and the five-section is 179-183L/min, 85-90L/min, 40-43L/min and 20-24L/min respectively, and the water quantity of the narrow surfaces of the pouring sides of the two-cooling two-section and the five-section is increased by 10% -20% on the basis of the non-pouring sides.
2. The control method according to claim 1, wherein the amount of the aluminum-manganese-iron added in the step 1) is 2.0-2.5 kg/t steel.
3. The control method according to claim 1, wherein in the step 2), 80-160 kg/furnace of calcium carbide, 530-640 kg/furnace of lime and 10-30 kg/furnace of aluminum particles are added for deoxidization and slagging after the refining is finished, and simultaneously, large argon stirring is adopted, wherein the argon pressure is 0.8-1.2 MPa, and the stirring time is 1-2 min.
4. The control method according to claim 1, wherein in the step 2), the titanium wire feeding amount is calculated according to 70-75% of the titanium recovery rate in the case of a titanium-nitrogen ratio of 3-3.42, the wire feeding speed of the titanium wire is 3.0-4.5 m/s, and the argon pressure is 0.3-0.4 MPa when the titanium wire is fed.
5. The control method according to claim 1, wherein in the step 3), the water quantity of the wide surface of the crystallizer is 1600-1610L/min, the wide surface circular cooling water holes are arranged in a non-equidistant mode, the distance between two adjacent water holes of the wing tip is 18-19mm, the distance between two adjacent water holes of the large R angle of the inner edge is 7-8mm, and the distance between two adjacent water holes of the web is 10-11mm.
6. The control method according to claim 1, wherein in the step 3), the use of an asymmetric cooling water amount for the narrow surface of the crystallizer includes: the water quantity of the narrow surface on the pouring side is increased to 1000-1100L/min, and the water quantity of the narrow surface on the non-pouring side is reduced to 800-900L/min.
7. The control method according to claim 1, wherein in the step 3), high-alkalinity low-viscosity mold flux is used, and the high-alkalinity low-viscosity mold flux comprises, in weight percent: siO (SiO) 2 27.6～29.5％；CaO 38.7～40.1％；Al 2 O 3 5.9 to 7.25 percent; mgO 1.72-2.95%; 12.6 to 14.8 percent of TC; alkalinity is 1.3-1.5; the viscosity is 0.45-0.55; the addition amount of the casting side covering slag is 1.3-1.4 kg/m 2 The addition amount of the non-pouring side protective slag is 1.1-1.2 kg/m 2 。
8. 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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