CN116287969B - Production method of low-crack-rate low-alloy high-strength steel special-shaped blank - Google Patents
Production method of low-crack-rate low-alloy high-strength steel special-shaped blank Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 23
- 239000010959 steel Substances 0.000 title claims abstract description 23
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 21
- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 14
- 239000000956 alloy Substances 0.000 title claims abstract description 14
- 238000005096 rolling process Methods 0.000 claims abstract description 20
- 238000005266 casting Methods 0.000 claims abstract description 15
- 238000007670 refining Methods 0.000 claims abstract description 15
- 238000000034 method Methods 0.000 claims abstract description 11
- 238000003723 Smelting Methods 0.000 claims abstract description 9
- 238000009749 continuous casting Methods 0.000 claims abstract description 5
- 239000000126 substance Substances 0.000 claims abstract description 5
- 239000012535 impurity Substances 0.000 claims abstract description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 30
- 239000002893 slag Substances 0.000 claims description 28
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 22
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 21
- 238000007664 blowing Methods 0.000 claims description 12
- 238000010079 rubber tapping Methods 0.000 claims description 12
- 229910052786 argon Inorganic materials 0.000 claims description 11
- 238000001816 cooling Methods 0.000 claims description 11
- 239000007788 liquid Substances 0.000 claims description 11
- 238000010438 heat treatment Methods 0.000 claims description 10
- 230000001276 controlling effect Effects 0.000 claims description 9
- 229910052742 iron Inorganic materials 0.000 claims description 9
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 6
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 6
- NCJRLCWABWKAGX-UHFFFAOYSA-N [Si].[Ca].[Ba] Chemical compound [Si].[Ca].[Ba] NCJRLCWABWKAGX-UHFFFAOYSA-N 0.000 claims description 6
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 6
- 229910052782 aluminium Inorganic materials 0.000 claims description 6
- 229910052799 carbon Inorganic materials 0.000 claims description 6
- 238000003780 insertion Methods 0.000 claims description 6
- 230000037431 insertion Effects 0.000 claims description 6
- 230000001105 regulatory effect Effects 0.000 claims description 6
- 239000007921 spray Substances 0.000 claims description 6
- 229910052717 sulfur Inorganic materials 0.000 claims description 6
- 239000011593 sulfur Substances 0.000 claims description 6
- 230000000694 effects Effects 0.000 claims description 5
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 3
- 208000029154 Narrow face Diseases 0.000 claims description 3
- CYUOWZRAOZFACA-UHFFFAOYSA-N aluminum iron Chemical compound [Al].[Fe] CYUOWZRAOZFACA-UHFFFAOYSA-N 0.000 claims description 3
- 239000010425 asbestos Substances 0.000 claims description 3
- 230000015572 biosynthetic process Effects 0.000 claims description 3
- 229910052791 calcium Inorganic materials 0.000 claims description 3
- 239000011575 calcium Substances 0.000 claims description 3
- 239000000498 cooling water Substances 0.000 claims description 3
- 230000003031 feeding effect Effects 0.000 claims description 3
- 238000007654 immersion Methods 0.000 claims description 3
- 239000002245 particle Substances 0.000 claims description 3
- 230000010287 polarization Effects 0.000 claims description 3
- 229910052895 riebeckite Inorganic materials 0.000 claims description 3
- 238000002791 soaking Methods 0.000 claims description 3
- 238000012360 testing method Methods 0.000 claims description 3
- 238000007789 sealing Methods 0.000 claims description 2
- 238000009628 steelmaking Methods 0.000 abstract 1
- 239000002253 acid Substances 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting 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
- 238000012856 packing Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
Classifications
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- 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
-
- 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
- B22D11/18—Controlling or regulating processes or operations for pouring
- B22D11/181—Controlling or regulating processes or operations for pouring responsive to molten metal level or slag level
- B22D11/182—Controlling or regulating processes or operations for pouring responsive to molten metal level or slag level by measuring temperature
-
- 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
- B22D11/20—Controlling or regulating processes or operations for removing cast stock
-
- 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
-
- 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
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
-
- 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
-
- 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
- C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
-
- 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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
-
- 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
- C22C38/16—Ferrous alloys, e.g. steel alloys containing 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
- C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium 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
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
-
- 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
- C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
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- 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
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- 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
-
- 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
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- 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)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
The invention discloses a production method of a low-crack-rate low-alloy high-strength steel special-shaped blank, which comprises the following chemical components, by mass, 0.18-0.21% of C, 0.35-0.45% of Si, 1.30-1.40% of Mn, less than or equal to 0.030% of P, less than or equal to 0.008% of S, 0.010-0.020% of V, less than or equal to 0.01% of Cr, less than or equal to 0.01% of Ni, less than or equal to 0.01% of Mo, less than or equal to 0.012% of N, and the balance Fe and impurities, wherein the mass fraction is 100% in total; the smelting process comprises the following steps: converter smelting, LF refining and beam blank continuous casting are optimized and controlled by each process of steelmaking, and the crack generation rate of casting blanks after rolling is lower than 0.3 percent.
Description
Technical Field
The invention relates to the technical field of smelting, in particular to a production method of a low-crack-rate low-alloy high-strength steel special-shaped blank and a production method thereof.
Background
The special-shaped blank has complex cross section shape, large difference of heat dissipation speeds at different parts, and poor uniformity of temperature distribution compared with a conventional casting blank, so that the crack sensitivity is enhanced, and the defect proportion of the casting blank is increased. The steel-clad beam blank casting machine mainly produces plain carbon steel and low alloy steel since production, wherein the steel types with the largest yield are Q235B and Q355B. The generation rate of the quality defects of the special-shaped blank is far greater than that of a conventional casting machine, and the main defects are longitudinal cracks of the casting blank. According to incomplete statistics, the crack rate of the domestic special-shaped blank after rolling is 2% -4%.
Disclosure of Invention
In order to solve the technical problems, the invention aims to provide a production method of a low-crack-rate low-alloy high-strength steel special-shaped blank.
In order to solve the technical problems, the invention adopts the following technical scheme:
the invention relates to a production method of a low-crack-rate low-alloy high-strength steel special-shaped blank, which comprises the following chemical components, by mass, 0.18-0.21% of C, 0.35-0.45% of Si, 1.30-1.40% of Mn, less than or equal to 0.030% of P, less than or equal to 0.008% of S, 0.010-0.020% of V, less than or equal to 0.01% of Cr, less than or equal to 0.01% of Ni, less than or equal to 0.01% of Mo, less than or equal to 0.012% of Cu, and the balance of Fe and impurities, wherein the mass fraction is 100% in total; the production process specifically comprises the following steps:
smelting by a combined blowing converter: the iron ball must be added within 5min in the earlier stage; the sulfur content of molten iron in the furnace is not more than 0.050%; tapping a carbon target: c > 0.08%; the aluminum of the converter for refining target in place is 0.005% -0.015%, and the specific deoxidizer addition amount is properly adjusted according to the carbon and sulfur content of the converter; endpoint control: t is more than or equal to 1600 ℃; the tapping time is more than 4min; the whole process is blocked, and the P difference is less than or equal to 0.004%;
LF refining: the refining feeding amount is required to be 70-100m, and the feeding speed is strictly controlled; argon must be regulated before feeding, the liquid level of the slag to be blown off is ensured to be 25-30cm, the viscosity of the slag must be regulated before feeding, the wire feeding effect is ensured, the wire is ensured to be beaten into molten steel, the soft blowing time is more than 15min, and the deoxidizer is deoxidized by aluminum iron, aluminum particles and silicon calcium barium; the consumption of the silicon-calcium-barium in each furnace is not more than 50kg, the steel tapping S condition of the converter is concerned, and the timely slag formation is ensured; and (3) controlling the superheat degree: the section superheat degree of BB1, BB2, BB3 and BB4 is less than or equal to 35 ℃; controlling the S content of the finished product to be less than or equal to 0.008 percent and simultaneously meeting the Mn/S value of more than 60; the refining treatment time is more than or equal to 40min, and the steel feeding temperature is 1570-1585 ℃;
continuous casting: the arc alignment precision of the crystallizer and the section I is controlled within 0.2 mm; the casting machine ensures the centering of the water gap and avoids bias flow; strictly executing argon blowing of a long nozzle; the liquid level of the middle ladle is required to be fully packed; the thickness of the tundish slag is not more than 100mm; baking the covering slag before using, wherein the thickness of the covering slag is controlled to be 40-50mm; ensuring that the water content of the used covering slag is less than or equal to 0.5 percent; the arc alignment of the crystallizer and the sector I section is less than or equal to 0.3mm; ensuring the water blowing effect of the water blower; crystallizer water quantity: the pressure is more than or equal to 0.8mpa, BB1: broad face 1300L/min and narrow face 850L/min;
BB2, broad surface 2200L/min and narrow surface 1200L/min; BB3: 2400L/min for wide surface and 900L/min for narrow surface;
BB4: 2500L/min on the wide surface and 1000L/min on the narrow surface; the long water gap of the big ladle is cast by adopting an asbestos bowl and an argon seal; automatically controlling the liquid level in the crystallizer, and controlling the fluctuation of the liquid level to +/-3 mm; the superheat degree is controlled at 20-35 ℃; long nozzle insertion depth: 150-200mm, and the insertion depth of the immersion nozzle is 50-70mm; drawing speed control BB1 section: 1.0-1.1m/min, BB2 section: 0.75-0.85m/min, BB3 section: 0.75-0.90m/min, BB4 section: 0.7-0.80m/min;
the heating process comprises the following steps: the temperature of the preheating section is less than or equal to 900 ℃, the temperature of the heating section I is less than or equal to 1200 ℃, the temperature of the heating section II is 1100-1330 ℃, the temperature of the soaking section is 1200-1300 ℃, and the tapping temperature is more than or equal to 1150 ℃; the furnace time is more than or equal to 2 hours and 20 minutes;
the rolling process comprises the following steps: cogging BD1, wherein the initial rolling temperature is more than or equal to 1150 ℃; CCS universal rolling, wherein the temperature of the last pass of final rolling is controlled below 940 ℃; and naturally cooling the cooling bed, and straightening and sawing after the temperature of the finished product is lower than 100 ℃.
Further, it is characterized in that: argon sealing pressure during casting protection: 1.1Mpa, flow rate: 20-30L/s.
Further, the method is applicable to the profile sections of 350X 290X 100mm (BB 1), 555X 440X 105mm (BB 2), 730X 370X 90mm (BB 3), 1024X 390X 120mm (BB 4).
Further, it is characterized in that: the secondary cooling adopts a weak cooling water meter, the covering slag is Sidoberg 73A, and the thickness of the covering slag is controlled to be 40-50mm.
Further, it is characterized in that: the quality of the crystallizer and the spray water must meet the standard requirements, the turbidity (NTU) is <10, the calcium hardness (mg/l) is <20, and the total iron (mg/l) is <0.5; the spray water pressure is not lower than 0.80Mpa, the water inlet temperature of the crystallizer is required to be 20-35 ℃, and the water inlet and outlet temperature difference is 4-6 ℃; the opposite arc of the segment I, II is not more than 0.5mm, and the vibration polarization test requirement is less than or equal to 0.20mm.
Compared with the prior art, the invention has the beneficial technical effects that:
by the production method, the crack rate of the special-shaped blank after rolling is lower than 0.3 percent.
Drawings
The invention is further described with reference to the following description of the drawings.
FIG. 1 shows the crack appearance of a hot acid casting blank in the original production process.
FIG. 2 shows the morphology of a hot acid casting blank in the prior production process.
Detailed Description
The invention will be described in further detail with reference to examples
The invention relates to a low-crack-rate low-alloy high-strength steel special-shaped blank and a production method thereof, wherein the low-crack-rate low-alloy high-strength steel special-shaped blank comprises the following chemical components in percentage by mass: 0.18-0.21% of C, 0.35-0.45% of Si, 1.30-1.40% of Mn, less than or equal to 0.030% of P, less than or equal to 0.008% of S, 0.010-0.020% of V, less than or equal to 0.01% of Cr, less than or equal to 0.01% of Ni, less than or equal to 0.01% of Mo, less than or equal to 0.01% of Cu, less than or equal to 0.012% of N, and the balance of Fe and impurities, wherein the mass fraction is 100% in total.
The invention relates to a low-crack-rate low-alloy high-strength steel special-shaped blank and a smelting process of a production method thereof, wherein the smelting process comprises the following steps: converter smelting, LF refining and beam blank continuous casting.
Smelting in a combined blown converter, wherein iron sheet balls are added within 5min in the earlier stage; the sulfur content of molten iron in the furnace is not more than 0.050%; tapping a carbon target: c > 0.08%; the aluminum of the converter for refining target in place is 0.005% -0.015%, and the specific deoxidizer addition amount is properly adjusted according to the carbon and sulfur content of the converter; endpoint control: t is more than or equal to 1600 ℃; for refining target components, C is more than or equal to 0.13% and less than or equal to 0.18%, si is more than or equal to 0.30% and less than or equal to 0.45%, mn is more than or equal to 1.25% and less than or equal to 1.40%, and P is less than 0.025%. The tapping time is more than 4min; the whole process is carried out slag blocking, and the P difference is less than or equal to 0.004 percent.
LF refining: the refining feeding amount is required to be 70-100m, and the feeding speed is strictly controlled. Argon must be regulated before feeding the wire, the liquid level of the slag to be blown off is ensured to be about 25-30cm, the viscosity of the slag must be regulated before feeding the wire, the wire feeding effect is ensured, the wire is ensured to be beaten into molten steel, the soft blowing effect (about 300 mm) is ensured, the soft blowing time is longer than 15min, and the deoxidizer is deoxidized by aluminum iron, aluminum particles and silicon calcium barium. The consumption of the silicon-calcium-barium in each furnace is not more than 50kg, the steel tapping S condition of the converter is concerned, and the timely slag formation is ensured; and (3) controlling the superheat degree: the section superheat degree of BB1, BB2, BB3 and BB4 is less than or equal to 35 ℃. The S content of the finished product is controlled to be less than or equal to 0.008 percent, and the Mn/S value is satisfied to be more than 60. The refining treatment time is more than or equal to 40min, and the steel feeding temperature is 1570-1585 ℃.
Continuous casting: the arc alignment precision of the crystallizer and the section I is controlled within 0.2 mm. The casting machine ensures the centering of the water gap and avoids bias flow. Strictly executing argon blowing of a long nozzle; the tundish level must be full of the packing operation. The thickness of the ladle slag is not more than 100mm. Baking the covering slag before using, wherein the thickness of the covering slag is controlled to be 40-50mm; the water content of the used covering slag is ensured to be less than or equal to 0.5 percent. The arc alignment between the crystallizer and the sector I section is less than or equal to 0.3mm. Ensure the water blowing effect of the water blower. Crystallizer water quantity: the pressure is more than or equal to 0.8mpa, BB1: broad face 1300L/min and narrow face 850L/min;
BB2, broad surface 2200L/min and narrow surface 1200L/min; BB3: 2400L/min for wide surface and 900L/min for narrow surface;
BB4: 2500L/min on the wide surface and 1000L/min on the narrow surface; the long water gap of the big ladle is protected and poured by an asbestos bowl and an argon seal (the pressure is 1.1Mpa, the flow is 20-30L/s); the liquid level in the crystallizer is automatically controlled, and the fluctuation of the liquid level is controlled to be +/-3 mm. The superheat degree is controlled at 20-35 ℃. Long nozzle insertion depth: 150-200mm, and the immersion nozzle insertion depth is 50-70mm. Drawing speed control BB1 section: 1.0-1.1m/min, BB2 section: 0.75-0.85m/min, BB3 section: 0.75-0.90m/min, BB4 section: 0.7-0.80m/min.
The secondary cooling adopts a weak cooling water meter, the covering slag is Sidoberg 73A (density: 0.81g/ml; melting point: 1139 ℃ C.; viscosity: 3.36 Poise), and the thickness of the covering slag is controlled to 40-50mm.
The quality of the crystallizer and the spray water must meet the standard requirements, the turbidity (NTU) is <10, the calcium hardness (mg/l) is <20, and the total iron (mg/l) is <0.5. The spray water pressure is not lower than 0.80Mpa, the water inlet temperature of the crystallizer is required to be 20-35 ℃, and the water inlet and outlet temperature difference is 4-6 ℃. The opposite arc of the segment I, II is not more than 0.5mm, and the vibration polarization test requirement is less than or equal to 0.20mm.
The method is suitable for the section of the special blank of 350X 290X 100mm (BB 1), 555X 440X 105mm (BB 2), 730X 370X 90mm (BB 3) and 1024X 390X 120mm (BB 4).
The rolling process comprises the following steps: step heating furnace, BD cogging, CCS universal rolling and step cooling bed cooling.
The heating process comprises the following steps: the preheating section temperature is less than or equal to 900 ℃, the heating section temperature is less than or equal to 1200 ℃, the heating section temperature is 1100-1330 ℃, the soaking section temperature is 1200-1300 ℃, and the tapping temperature is more than or equal to 1150 ℃. The furnace time is more than or equal to 2 hours and 20 minutes.
The rolling process comprises the following steps: and cogging BD1, wherein the initial rolling temperature is more than or equal to 1150 ℃. CCS universal rolling, and the final rolling temperature is controlled below 940 ℃. And naturally cooling the cooling bed, and straightening and sawing after the temperature of the finished product is lower than 100 ℃.
Table 1 chemical composition of each example
TABLE 2 casting blank section, degree of superheat and drawing speed in each example
TABLE 3 examples at furnace time, start rolling temperature, finish rolling temperature
TABLE 4 post-rolling crack ratios for the examples
As shown in fig. 1, the crack morphology of the casting blank in the original production process is shown; as shown in FIG. 2, the hot acid of the cast billet in the process of the invention does not find cracks.
The above embodiments are only illustrative of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention, and various modifications and improvements made by those skilled in the art to the technical solutions of the present invention should fall within the protection scope defined by the claims of the present invention without departing from the design spirit of the present invention.
Claims (5)
1. A production method of a low-crack-rate low-alloy high-strength steel special-shaped blank is characterized by comprising the following steps of: the chemical components comprise, by mass, 0.18-0.21% of C, 0.35-0.45% of Si, 1.30-1.40% of Mn, less than or equal to 0.030% of P, less than or equal to 0.008% of S, 0.010-0.020% of V, less than or equal to 0.01% of Cr, less than or equal to 0.01% of Ni, less than or equal to 0.01% of Mo, less than or equal to 0.012% of Cu, and the balance of Fe and impurities, wherein the mass fraction is 100% in total; the production process specifically comprises the following steps:
smelting by a combined blowing converter: the iron ball must be added within 5min in the earlier stage; the sulfur content of molten iron in the furnace is not more than 0.050%; tapping a carbon target: c > 0.08%; the aluminum of the converter for refining target in place is 0.005% -0.015%, and the specific deoxidizer addition amount is properly adjusted according to the carbon and sulfur content of the converter; endpoint control: t is more than or equal to 1600 ℃; the tapping time is more than 4min; the whole process is blocked, and the P difference is less than or equal to 0.004%;
LF refining: the refining feeding amount is required to be 70-100m, and the feeding speed is strictly controlled; argon must be regulated before feeding, the liquid level of the slag to be blown off is ensured to be 25-30cm, the viscosity of the slag must be regulated before feeding, the wire feeding effect is ensured, the wire is ensured to be beaten into molten steel, the soft blowing time is more than 15min, and the deoxidizer is deoxidized by aluminum iron, aluminum particles and silicon calcium barium; the consumption of the silicon-calcium-barium in each furnace is not more than 50kg, the steel tapping S condition of the converter is concerned, and the timely slag formation is ensured; and (3) controlling the superheat degree: the section superheat degree of BB1, BB2, BB3 and BB4 is less than or equal to 35 ℃; controlling the S of the finished product to be less than or equal to 0.008 percent, and simultaneously meeting the Mn/S value of more than 60; the refining treatment time is more than or equal to 40min, and the steel feeding temperature is 1570-1585 ℃;
continuous casting: the arc alignment precision of the crystallizer and the section I is controlled within 0.2 mm; the casting machine ensures the centering of the water gap and avoids bias flow; strictly executing argon blowing of a long nozzle; the liquid level of the middle ladle is required to be fully packed; the thickness of the tundish slag is not more than 100mm; baking the covering slag before using, wherein the thickness of the covering slag is controlled to be 40-50mm; ensuring that the water content of the used covering slag is less than or equal to 0.5 percent; the arc alignment of the crystallizer and the sector I section is less than or equal to 0.3mm; ensuring the water blowing effect of the water blower; crystallizer water quantity: the pressure is more than or equal to 0.8mpa, BB1: broad face 1300L/min and narrow face 850L/min;
BB2, broad surface 2200L/min and narrow surface 1200L/min; BB3: 2400L/min for wide surface and 900L/min for narrow surface;
BB4: 2500L/min on the wide surface and 1000L/min on the narrow surface; the long water gap of the big ladle is cast by adopting an asbestos bowl and an argon seal; automatically controlling the liquid level in the crystallizer, and controlling the fluctuation of the liquid level to be +/-3 mm; the superheat degree is controlled at 20-35 ℃; long nozzle insertion depth: 150-200mm, and the insertion depth of the immersion nozzle is 50-70mm; drawing speed control BB1 section: 1.0-1.1m/min, BB2 section: 0.75-0.85m/min, BB3 section: 0.75-0.90m/min, BB4 section: 0.7-0.80m/min;
the heating process comprises the following steps: the temperature of the preheating section is less than or equal to 900 ℃, the temperature of the heating section I is less than or equal to 1200 ℃, the temperature of the heating section II is 1100-1330 ℃, the temperature of the soaking section is 1200-1300 ℃, and the tapping temperature is more than or equal to 1150 ℃; the furnace time is more than or equal to 2 hours and 20 minutes;
the rolling process comprises the following steps: cogging BD1, wherein the initial rolling temperature is more than or equal to 1150 ℃; CCS universal rolling, wherein the temperature of the last pass of final rolling is controlled below 940 ℃; and naturally cooling the cooling bed, and straightening and sawing after the temperature of the finished product is lower than 100 ℃.
2. The method for producing a low-crack-rate low-alloy high-strength steel parison according to claim 1, characterized by: argon sealing pressure during casting protection: 1.1Mpa, flow rate: 20-30L/s.
3. The method for producing a low-crack-rate low-alloy high-strength steel parison according to claim 1, characterized by: the method is suitable for the sections of the special-shaped blanks of 350 multiplied by 290 multiplied by 100mm BB1, 555 multiplied by 440 multiplied by 105mm BB2, 730 multiplied by 370 multiplied by 90mm BB3 and 1024 multiplied by 390 multiplied by 120mm BB4.
4. The method for producing a low-crack-rate low-alloy high-strength steel parison according to claim 1, characterized by: the secondary cooling adopts a weak cooling water meter, the covering slag is Sidoberg 73A, and the thickness of the covering slag is controlled to be 40-50mm.
5. The method for producing a low-crack-rate low-alloy high-strength steel parison according to claim 1, characterized by: the quality of the crystallizer and the spray water must meet the standard requirements, the turbidity NTU is less than 10, the calcium hardness is less than 20mg/l, and the total iron is less than 0.5mg/l; the spray water pressure is not lower than 0.80Mpa, the water inlet temperature of the crystallizer is required to be 20-35 ℃, and the water inlet and outlet temperature difference is 4-6 ℃; the opposite arc of the segment I, II is not more than 0.5mm, and the vibration polarization test requirement is less than or equal to 0.20mm.
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