CN116732273A - Continuous casting production method for reducing crack rate of continuous casting billet - Google Patents

Continuous casting production method for reducing crack rate of continuous casting billet Download PDF

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Publication number
CN116732273A
CN116732273A CN202310529049.5A CN202310529049A CN116732273A CN 116732273 A CN116732273 A CN 116732273A CN 202310529049 A CN202310529049 A CN 202310529049A CN 116732273 A CN116732273 A CN 116732273A
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less
continuous casting
slag
section
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赵晓敏
惠治国
卜向东
宋振东
刘丽娟
王刚
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Baotou Iron and Steel Group Co Ltd
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Baotou Iron and Steel Group Co Ltd
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    • 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
    • B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
    • B22D11/043—Curved moulds
    • 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
    • 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
    • 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
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/12—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
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Treatment Of Steel In Its Molten State (AREA)

Abstract

The invention discloses a smelting continuous casting production method for reducing the crack rate of a continuous casting billet, which relates to a method for reducing the mass percentage of chemical components of steel types and comprises the following steps: 0.12-0.20% of C, 0.10-0.35% of Si, 0.30-1.50% of Mn, less than or equal to 0.015% of P, less than or equal to 0.008% of S, less than or equal to 0.005% 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 smelting process comprises the following steps: converter smelting, LF refining and beam blank continuous casting. By implementing the smelting continuous casting production method for reducing the crack rate of the continuous casting blank, the crack rate of the sections of different special-shaped blanks is reduced to be within 0.20%, the quality of the special-shaped casting blank is improved, and meanwhile, obvious economic benefits are obtained.

Description

Continuous casting production method for reducing crack rate of continuous casting billet
Technical Field
The invention relates to the technical field of smelting, in particular to a continuous casting production method for reducing the crack rate of a continuous casting billet.
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 uses common carbon steel and low alloy steel as main production materials and is matched with a small amount of weather-resistant steel and high-strength low-temperature-resistant steel, wherein the steel types with the largest yield are Q235B and Q355B. The production rate of the quality defects of the special-shaped blank produced by the special-shaped blank casting machine is far greater than that of the special-shaped blank produced by the conventional casting machine. According to incomplete statistics, the crack rate of the domestic special-shaped blank after rolling is 2% -4%. In order to reduce the crack rate of the special-shaped blank, key factors for controlling the crack rate are finally determined through correlation analysis of chemical components, drawing speed, superheat degree, refining time and converter tapping components of the furnace number with the crack rate, and the smelting continuous casting production method for reducing the crack rate of the continuous casting blank is provided, so that the crack rate of sections of different special-shaped blanks is reduced to be within 0.20%, the quality of the special-shaped blank is improved, and meanwhile, obvious economic benefits are obtained.
Disclosure of Invention
The invention aims to provide a continuous casting production method for reducing the crack rate of a continuous casting blank, and particularly relates to a continuous casting blank with a special-shaped section.
In order to solve the technical problems, the invention adopts the following technical scheme:
the invention relates to a continuous casting production method for reducing the crack rate of a continuous casting blank, which comprises the following steps:
1) Smelting in combined blown converter
The sulfur content of molten iron in the furnace is not more than 0.030%; the iron ball must be added within 5min in the earlier stage, the steel end point component C is more than or equal to 0.06 percent, T is more than or equal to 1600 ℃, and the alloy is used for baking, so that the three hit rate of molten steel for refining is ensured, and the refining treatment time is ensured; for refining target components: c is more than or equal to 0.15% and less than or equal to 0.20%, si is more than or equal to 0.10% and less than or equal to 0.30%, mn is more than or equal to 0.35% and less than or equal to 1.45%, and P is less than 0.015%; the whole process is blocked, and the P difference is less than or equal to 0.004%;
2) External refining in LF furnace
The dislocation S is controlled to be less than or equal to 0.010%, the refining soft blowing time is more than or equal to 15min, the early slag formation and the quick slag formation of refining are ensured, the refined slag completely realizes white slag, and the deoxidizer is deoxidized by aluminum iron, aluminum particles and silicon calcium barium; the consumption of the silicon-calcium-barium per furnace is not more than 50kg, and the superheat degree is controlled: 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 0.010 percent, and simultaneously meeting the Mn/S value of more than 30; the refining treatment time is more than or equal to 40min, and the steel feeding temperature is 1570-1585 ℃;
3) 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 thickness of the tundish slag is not more than 90mm; baking the covering slag before using; 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; the long water gap of the big ladle adopts an asbestos bowl and an argon seal; protecting and pouring; 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; 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 continuous casting mold flux is selected from Stobeger L7, and the density is as follows: 0.89g/ml; melting point: 1241 ℃; viscosity: 7.9Poise, controlling the thickness of the covering slag to 40-50mm; 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;
4) Rolling
When the casting blank enters the heating furnace, the total heating time is more than or equal to 3 hours, the soaking section temperature is 1100-1200 ℃, the casting blank is rolled at a low temperature on the basis of ensuring the size of the section steel, and the final rolling temperature is less than or equal to 950 ℃.
Further, the continuous casting blank comprises the following chemical components in percentage by mass: 0.12-0.20% of C, 0.10-0.35% of Si, 0.30-1.50% of Mn, less than or equal to 0.015% of P, less than or equal to 0.008% of S, less than or equal to 0.005% 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.
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, the crystallizer water amount: the pressure is more than or equal to 0.8MPa, BB1: broad face 1300L/min and narrow face 850L/min; BB2: broad face 2200L/min and narrow face 1200L/min; BB3: 2400L/min for wide surface and 900L/min for narrow surface; BB4: 2500L/mi wide and 1000L/min narrow; BB3: 2400L/min for wide surface and 900L/min for narrow surface; BB4: 2500L/min on the broad side and 1000L/min on the narrow side.
Compared with the prior art, the invention has the beneficial technical effects that:
by implementing the smelting continuous casting production method for reducing the crack rate of the continuous casting blank, the crack rate of the sections of different special-shaped blanks is reduced to be within 0.20%, the quality of the special-shaped casting blank is improved, and meanwhile, obvious economic benefits are obtained.
Detailed Description
The invention will be described in further detail below for the sake of better:
the invention discloses a smelting continuous casting production method for reducing the crack rate of a continuous casting billet, which relates to a method for producing the continuous casting billet by smelting, and comprises the following chemical components in percentage by mass: 0.12-0.20% of C, 0.10-0.35% of Si, 0.30-1.50% of Mn, less than or equal to 0.015% of P, less than or equal to 0.008% of S, less than or equal to 0.005% 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 carbon structural steel special-shaped blank and a production method thereof, wherein the smelting process comprises the following steps: converter smelting, LF refining and beam blank continuous casting.
1. Smelting in combined blown converter
The sulfur content of molten iron in the furnace is not more than 0.030%; the iron ball must be added within 5min in the earlier stage, the steel end point component C is more than or equal to 0.06 percent, T is more than or equal to 1600 ℃, and the alloy is used for baking (hydrogen control), so that the three hit rate of molten steel for refining is ensured, and the refining treatment time is ensured; for refining target components: c is more than or equal to 0.15% and less than or equal to 0.20%, si is more than or equal to 0.10% and less than or equal to 0.30%, mn is more than or equal to 0.35% and less than or equal to 1.45%, and P is less than 0.015%. The whole process is carried out slag blocking, and the P difference is less than or equal to 0.004 percent.
2. LF external refining
The dislocation S is controlled to be less than or equal to 0.010 percent, the refining soft blowing time is more than or equal to 15 minutes, the early slag formation and the quick slag formation of the refining are ensured, the white slag is realized by the refining slag, and the deoxidizer is deoxidized by aluminum iron, aluminum particles and silicon calcium barium. The consumption of the silicon-calcium-barium per furnace is not more than 50kg, and the superheat degree is controlled: the section superheat degree of BB1, BB2, BB3 and BB4 is less than or equal to 35 ℃. The S of the finished product is controlled to be less than or equal to 0.010 percent, and the Mn/S value is satisfied to be more than 30. The refining treatment time is more than or equal to 40min, and the steel feeding temperature is 1570-1585 ℃.
The refining needs to make alkaline slag, different colors of the slag are observed during slag making, the slag is black along with strong oxidizing property of the slag, the color of the slag becomes gradually lighter along with weakening of oxidizing property of the slag, namely, the slag is reduced, and the slag is changed from black, gray, brown, yellow, pale yellow and white. Black indicates poor deoxidization of slag and further removal of oxygen from slag is required. The grey to brown color also requires a certain reduction time. Yellow to white slag is reduced best.
(1) If the section is smooth and not easy to crack, the alkalinity is low; if glassy, this indicates that the slag is slightly more acidic. The lime addition amount is controlled to be 6-9kg/t of steel (including converter added top slag) according to actual conditions, and the process is observed in a slag dipping manner.
(2) When calcium carbide is used for removing oxygen in slag to form calcium carbide slag, the color of slag is gradually changed into gray-white, and the analysis and control measures of the cause of cracks on the surface of the special-shaped blank are deep gray and colored, so that the slag is easy to carburette.
(3) The evaluation of the white slag is to pay attention to the slag color, not only the degree of white slag, but also the holding time of the white slag. The white slag has stable color or white color with a little gray color, and the long holding time can prove that the molten steel deoxidizes well. The repeated change of slag color shows poor deoxidization of slag, and a proper amount of deoxidizing agent is needed to be added at the moment, so that the white slag is required to be kept for more than 20min in the process.
3. 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. Argon blowing of the long nozzle is strictly performed. The thickness of the tundish slag is not more than 90mm. Baking the covering slag before using; 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. 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. 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 water quantity of the special-shaped blank is in the range of 0.7-0.8m/min, and the special-shaped blank has high cooling strength. The surface area of the H-shaped steel special-shaped blank is generally larger than that of a plate blank and a square blank, so that the temperature of the special-shaped blank surface of a secondary cooling section can be rapidly reduced, and according to actual temperature measurement and simulation data, the special-shaped blank surface is found to be a brittle area of the secondary cooling section at low temperature, and therefore cracks are easy to occur in the area. 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 face 2200L/min and narrow face 1200L/min; BB3: 2400L/min for wide surface and 900L/min for narrow surface; BB4: 2500L/mi wide and 1000L/min narrow; BB3: 2400L/min for wide surface and 900L/min for narrow surface; BB4: 2500L/min on the broad side and 1000L/min on the narrow side.
The casting powder is Stoberg L7 (density: 0.89g/ml; melting point: 1241 ℃ C.; viscosity: 7.9 Poise) and the thickness of the casting powder 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 is <20mg/L, and the total iron is <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. 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).
Or as needed: the mold flux can be HDK-2 and 16Mn plate blank mold flux with low viscosity, and the two mold fluxes can form mixed slag after being mixed. The crystallization temperature of the mixed slag is higher and can reach 1216 ℃, so that the mixed slag is more suitable for casting deformed steel, but the change of the viscosity of the mixed slag is larger, the crack is influenced, and the viscosity of the mixed slag is required to be stabilized within the range of 0.286-0.438. Considering the problems of the drawing speed, the double water gap and the like of the H-shaped steel profiled bar, the heating type casting powder can be tried to be used in continuous casting.
Table 1 chemical composition/%
TABLE 2 concrete examples casting section, degree of superheat and draw speed
4. Rolling
Specific rolling examples are given in the following table.
TABLE 3 specific examples are furnace time, start rolling temperature, finish rolling temperature
Examples of the invention At the time of the furnace Initial rolling temperature (. Degree. C.) Finishing temperature (. Degree. C.)
Example 1 3 hours 41 minutes 1151 935
Example 2 3 hours 55 minutes 1163 933
Example 3 3 hours 02 min 1175 930
Example 4 3 hours 38 minutes 1160 939
Example 5 3 hours 22 minutes 1179 950
Example 6 3 hours 08 minutes 1180 943
Example 7 3 hours 11 minutes 1191 944
Example 8 3 hours 27 minutes 1195 938
By implementing the smelting continuous casting production method for reducing the crack rate of the continuous casting blank, the crack rate of the sections of different special-shaped blanks is reduced to be within 0.20%, the quality of the special-shaped casting blank is improved, and meanwhile, obvious economic benefits are obtained, and the specific crack rate is shown in the following table.
Table 4 concrete examples post-rolling crack ratio
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 (4)

1. A continuous casting production method for reducing the crack rate of a continuous casting blank is characterized by comprising the following steps: comprising the following steps:
1) Smelting in combined blown converter
The sulfur content of molten iron in the furnace is not more than 0.030%; the iron ball must be added within 5min in the earlier stage, the steel end point component C is more than or equal to 0.06 percent, T is more than or equal to 1600 ℃, and the alloy is used for baking, so that the three hit rate of molten steel for refining is ensured, and the refining treatment time is ensured; for refining target components: c is more than or equal to 0.15% and less than or equal to 0.20%, si is more than or equal to 0.10% and less than or equal to 0.30%, mn is more than or equal to 0.35% and less than or equal to 1.45%, and P is less than 0.015%; the whole process is blocked, and the P difference is less than or equal to 0.004%;
2) External refining in LF furnace
The dislocation S is controlled to be less than or equal to 0.010%, the refining soft blowing time is more than or equal to 15min, the early slag formation and the quick slag formation of refining are ensured, the refined slag completely realizes white slag, and the deoxidizer is deoxidized by aluminum iron, aluminum particles and silicon calcium barium; the consumption of the silicon-calcium-barium per furnace is not more than 50kg, and the superheat degree is controlled: 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 0.010 percent, and simultaneously meeting the Mn/S value of more than 30; the refining treatment time is more than or equal to 40min, and the steel feeding temperature is 1570-1585 ℃;
3) 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 thickness of the tundish slag is not more than 90mm; baking the covering slag before using; 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; the long water gap of the big ladle adopts an asbestos bowl and an argon seal; protecting and pouring; 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; 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 continuous casting mold flux is selected from Stobeger L7, and the density is as follows: 0.89g/ml; melting point: 1241 ℃; viscosity: 7.9Poise, controlling the thickness of the covering slag to 40-50mm; 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;
4) Rolling
When the casting blank enters the heating furnace, the total heating time is more than or equal to 3 hours, the soaking section temperature is 1100-1200 ℃, the casting blank is rolled at a low temperature on the basis of ensuring the size of the section steel, and the final rolling temperature is less than or equal to 950 ℃.
2. The continuous casting production method for reducing the crack rate of a continuous casting slab according to claim 1, wherein: the continuous casting blank comprises the following chemical components in percentage by mass: 0.12-0.20% of C, 0.10-0.35% of Si, 0.30-1.50% of Mn, less than or equal to 0.015% of P, less than or equal to 0.008% of S, less than or equal to 0.005% 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.
3. The continuous casting production method for reducing the crack rate of a continuous casting slab according to claim 1, wherein: 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).
4. The continuous casting production method for reducing the crack rate of a continuous casting slab according to claim 1, wherein: 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 face 2200L/min and narrow face 1200L/min; BB3: 2400L/min for wide surface and 900L/min for narrow surface; BB4: 2500L/mi wide and 1000L/min narrow; BB3: 2400L/min for wide surface and 900L/min for narrow surface; BB4: 2500L/min on the broad side and 1000L/min on the narrow side.
CN202310529049.5A 2023-05-11 2023-05-11 Continuous casting production method for reducing crack rate of continuous casting billet Pending CN116732273A (en)

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