CN111455125A - Production method for increasing continuous casting heat of high-aluminum steel - Google Patents
Production method for increasing continuous casting heat of high-aluminum steel Download PDFInfo
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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
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- 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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
- B22D41/50—Pouring-nozzles
- B22D41/58—Pouring-nozzles with gas injecting means
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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
- 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
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- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/10—Handling in a vacuum
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- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
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Abstract
The invention discloses a production method for improving continuous casting heat of high-aluminum steel, which comprises the working procedures of molten iron pretreatment, converter, L F refining, RH refining and slab continuous casting, wherein in the working procedure of the converter, steel grit aluminum is automatically added into a converter bin, and slag-free steel tapping is realized through front and back double slag blocking operation, in the working procedure of the L F refining, the working procedure of L F furnace micro-positive pressure operation is adopted, in the continuous casting working procedure, a high-alkalinity carbon-free low-silicon covering agent is added into tundish casting, and a tundish stopper rod uses an argon blowing stopper rod.
Description
Technical Field
The invention relates to a steelmaking method, in particular to a production method for improving the continuous casting heat of high-aluminum steel.
Background
The high-aluminum steel (Al content is 0.5wt% -2.0 wt%) realizes good matching of high strength and high toughness, has become an important group in advanced high-strength steel, and is widely applied to the automobile industry and widely paid attention by various automobile plate manufacturing enterprises.
However, the high aluminum content can change the property of the casting powder in the smelting process to form high-melting-point substances which are adhered to the wall of a nozzle to form nozzle nodulation, so that the problem of serious nozzle blockage is caused, the pouring is interrupted, and the smooth operation of the process is influenced; meanwhile, the problems of rising of a stopper rod, fluctuation of liquid level, slag entrapment and the like caused by the nodulation of a water gap affect the surface quality of a casting blank.
Disclosure of Invention
The invention aims to provide a production method for improving the continuous casting heat of high-aluminum steel, which has good casting blank quality.
In order to solve the technical problems, the method adopts the technical scheme that the method comprises the working procedures of molten iron pretreatment, converter, L F refining, RH refining and slab continuous casting, wherein in the converter working procedure, steel grit aluminum is automatically added into a converter bin, and slag-free tapping is realized through front and back double slag blocking operations, in the L F refining working procedure, L F furnace micro-positive pressure operation is carried out, in the continuous casting working procedure, a high-alkalinity carbon-free low-silicon covering agent is poured into a tundish, and an argon blowing stopper is used as a tundish stopper.
In the continuous casting process, submerged casting and full-process protection casting are adopted, a long water gap and argon blowing protection casting are adopted from a continuous casting ladle to a tundish, the protection casting pressure is 10-11 Mpa, and the argon flow is 100-110L/min.
In the continuous casting process, the argon flow of the argon blowing stopper rod is 3-4L/min, and the argon sealing flow between the immersion type water inlet plates is 6-9L/min.
In the continuous casting process, the adopted casting powder comprises the following components in percentage by mass: SiO 2233%～37%，CaO 27%～30%，MgO 2.4%～2.5%，Al2O32.4%～3.5%，Fe2O30.6%～1.7%，MnO23%～4%，Na2O 10%～12%，CaF211%～13%，C 4.5%～6.0%。
Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: the invention can smoothly realize that the number of continuous casting furnaces is 8 or more, and quality accidents such as water gap blockage, bonded bleed-out or casting blank cracks and the like do not occur; the obtained casting blank has good surface quality and no recess and crack, and reaches the international advanced level. The high-aluminum steel product produced by the method has high structure uniformity and good bending performance, and is widely applied to automobile parts with complex structures.
Drawings
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
FIG. 1 is a surface quality chart of a steel strip product obtained in example 1 of the present invention;
FIG. 2 is a surface quality chart of a steel strip product obtained in example 2 of the present invention;
FIG. 3 is a surface quality chart of a steel strip product obtained in example 3 of the present invention;
FIG. 4 is a surface quality chart of a steel strip product obtained in example 4 of the present invention.
Detailed Description
The production method for improving the continuous casting heat of the high-aluminum steel comprises the process flows of molten iron pretreatment-100 t converter-L F refining-RH refining-slab continuous casting production line and the duplex process route of L F refining and RH deep treatment process, can control the H content in molten steel, prevent the hydrogen embrittlement phenomenon of the high-aluminum steel, further remove the inclusion content in steel, control the total oxygen content in the molten steel to be less than 10ppm, improve the cleanliness and the castability of the molten steel, inevitably bring nitrogen, hydrogen and other gases into materials added in the converter, influence the quality of a casting blank by the gases, increase RH vacuum degassing treatment after L F, and mainly remove the gases such as nitrogen, hydrogen, oxygen and the like and Al2O3And the quality of the high-aluminum steel smelting and casting blank can be ensured by impurities. The process of each procedure is as follows:
(1) a converter process: an automatic steelmaking model based on an infrared flue gas analysis system is adopted, and the alkalinity of the final slag is increased to 3.8-4.2, so that harmful elements such as sulfur, phosphorus and the like can be removed; the converter end point oxygen is controlled to be 400-600 ppm so as to reduce the generation amount of inclusions, and the front and rear double slag blocking operations realize slag-free tapping, so that the aluminum burning loss is reduced, and the cleanliness of molten steel is effectively improved. Controlling the end point temperature of the converter to be 1680 ℃ and above; the manual addition of the aluminum wire section in the tapping process is optimized to automatically add steel grit aluminum into the stock bin, so that the labor intensity of workers is reduced, the addition efficiency is improved, the absorption rate of aluminum is improved, and the addition uniformity and the timeliness of aluminum are ensured; the alloy charge was started at and after the time of tapping 1/5, and was completed at and before the time of tapping 4/5.
Under normal conditions, the materialThe bin is added with aluminum wires, aluminum particles or aluminum iron; the aluminum particles are light and are easy to stay in a slag layer to react with the steel slag, and the molten steel cannot be absorbed; the aluminum wire is directly driven into molten steel, so that the steel slag is easy to deoxidize insufficiently, and the steel slag on the surface of the molten steel reacts with Al to generate Al2O3The method selects the steel grit aluminum with high density, the steel slag and the molten steel can be fully deoxidized when entering the molten steel from the steel slag, and the absorption rate is obviously higher than that of the aluminum iron.
(2) L F refining process, adopting L F furnace micro positive pressure operation, controlling the micro positive pressure at 1.05-1.15 bar, controlling slag alkalinity at 11-14, adopting L F furnace refining station white slag operation, ensuring that smelting process is completely in reducing atmosphere, adopting bottom blowing argon system, fine-adjusting molten steel components, strictly controlling nitrogen content in steel, preventing generation of a large amount of AlN to cause casting blank defects, wherein the bottom blowing argon system is divided into 4 modes, namely strong blowing, middle blowing, soft blowing and static blowing, strong blowing mould type single-way argon flow 600-1000N L/min, mainly carrying out deoxidation and desulfurization by slag washing and power transmission, medium blowing mould type single-way argon flow 300-500N L/min, mainly aiming at uniform components and temperature, soft blowing mode single-way argon flow 40-100N L/min, mainly aiming at uniform temperature, adjusting single-way argon flow 300-500N L/min, mainly aiming at uniform components and fine-adjusting molten steel surface argon flow to less than 50ppm, and ensuring that the deviation of molten steel surface of pure molten steel and molten steel surface elements is less than 50ppm, wherein the deviation of molten steel is controlled by micro blowing standard nitrogen flow deviation of pure argon flow and fine-30 ppm.
(3) RH refining process: adopting an RH deep treatment method, ensuring that the vacuum degree is less than 2mbar, the treatment time is more than 15min, and ensuring that the H content and the N content in the molten steel are less than 1.5ppm and less than 30ppm after the treatment.
(4) The slab continuous casting process comprises the steps of in the continuous casting process, pouring ladle molten steel at the temperature of 1540 ℃ or above, preferably 1540-1550 ℃, pouring ladle superheat degree of 25-30 ℃, adopting submerged start pouring and full-process protection pouring, pouring from a continuous casting ladle to a pouring ladle through a long nozzle and argon blowing protection, protecting pouring pressure of 10-11 Mpa and argon flow of 100-110L/min, preventing molten steel from being secondarily oxidized when the molten steel is poured into the pouring ladle from the ladle to cause reduction of clean molten steel degree and difficulty in pouring, adding a high-alkalinity carbon-free low-silicon covering agent during pouring, preventing secondary oxidation of the molten steel after entering the pouring ladle, using an argon blowing stopper rod for the pouring ladle stopper rod, controlling the argon flow of 3-4L/min, using a magnesium aluminate spinel lining anti-blocking nozzle for the submerged nozzle, and controlling argon sealing flow between the submerged nozzles at 6-9L/min.
The alkalinity of the high-alkalinity carbon-free low-silicon covering agent is more than 10, and the main components require the weight as follows: SiO 223%±0.5%、CaO 45%±5%、MgO≤0.3%、Fe2O3Less than or equal to 1 percent and Al2O335%±5%。
When the molten steel for casting submerges a side hole of the submersed nozzle, special covering slag for high-aluminum steel is added, heat transfer and lubrication are controlled, good cooling conditions are provided for a casting blank, and the covering slag comprises the following components in percentage by mass: SiO 2233%～37%，CaO 27%～30%，MgO 2.4%～2.5%，Al2O32.4%～3.5%，Fe2O30.6%～1.7%，MnO23%～4%，Na2O 10%～12%，CaF211 to 13 percent of acid oxide Si0 percent, 4.5 to 6.0 percent of C, 0.8 to 0.9 percent of alkalinity, 0.15 to 0.20 Pa.s of viscosity and 0.7 to 0.9 kg/L of density, and the casting powder can quickly realize the stability of the performance of the steel slag after reaction and inclusion absorption2The alkalinity of the slag is increased, and the alkalinity in the slag is balanced by adopting acid oxides, so that coarse slag strips are prevented from being formed to a certain extent. The mold flux with low viscosity is adopted to increase the consumption of the mold flux, perform good lubrication on the casting blank and prevent steel leakage. The continuous casting speed is controlled to be 1.4-1.5 m/min.
The obtained continuous casting billet comprises the following chemical components in percentage by mass: 0.070 to 0.100 percent of C, 2.0 to 2.4 percent of Mn, less than or equal to 0.010 percent of S, less than or equal to 0.015 percent of P, 0.10 to 0.15 percent of Si, 0.50 to 0.80 percent of Als, less than or equal to 0.0040 percent of N, 0.010 to 0.030 percent of Nb, 0.010 to 0.030 percent of Ti, 0.15 to 0.30 percent of Mo, 0.0010 to 0.0030 percent of B, and the balance of Fe and inevitable impurities.
Example 1: the production method for improving the continuous casting heat of the high-aluminum steel adopts the following specific process.
(1) Controlling the components of the high-aluminum steel: the chemical composition and the mass percentage of the high-aluminum steel are shown in the table 1.
(2) The high-aluminum steel process flow is a duplex process production line of molten iron pretreatment-100 t converter-L F refining-RH refining-slab caster.
(3) Controlling the end point temperature of the converter to be 1680 ℃, controlling the alkalinity of the final slag to be 4.0 and controlling the end point oxygen to be 400 ppm; the slag blocking mode of the front sliding plate for blocking slag, the rear slag blocking mark and the sliding plate for blocking slag is adopted, the steel sand aluminum is automatically added by using the bin, the alloy material is added when the steel is tapped 1/5, and the alloy material is added when the steel is tapped 4/5.
(4) L F refining adopts 1.10bar micro-positive pressure operation, enters a station to make white slag operation, ensures that the smelting process is completely in a reducing atmosphere, controls the alkalinity of slag at 12, adopts a bottom argon blowing system, finely adjusts the components of molten steel, strictly controls the nitrogen content in the steel to be less than 30ppm, and prevents casting blank defects caused by a large amount of AlN.
(5) Adopting RH deep processing method with vacuum degree less than 2mbar and vacuum processing time 20 min; the H content was 1ppm and the N content was 25ppm after the vacuum treatment.
(6) In the continuous casting process, the molten steel temperature of a tundish is 1545 ℃, the superheat degree of the tundish is 27 ℃, the submerged casting is started and the whole protective casting is carried out, the continuous casting ladle is cast from a large ladle to the tundish by adopting a long nozzle and argon blowing protection, the protective casting pressure is 10.4Mpa and the argon flow is 105L/min, the high-alkalinity carbon-free low-silicon covering agent is added when the continuous casting ladle is started, the tundish stopper is an argon blowing stopper, the argon flow is 3.4L/min, the submerged nozzle is a magnesium aluminate spinel lining anti-blocking nozzle, the argon sealing flow between plates of the submerged nozzles is controlled to be 7.8L/min, the special protective slag for the high-alumina steel is added when the molten steel during casting does not pass through the submerged side holes, and theThe casting powder is prepared, transferred heat and lubricated, good cooling conditions are provided for casting blanks, and the casting powder comprises the following components in percentage by mass: SiO 2235%、CaO 28%、MgO 2.5%、Al2O32.9%、Fe2O31.0%、MnO23.4%、Na2O 11%、CaF211 percent, C5.2 percent, alkalinity of 0.84, viscosity of 0.20 Pa.s and density of 0.8 kg/L, and the continuous casting drawing speed is controlled to be 1.5 m/min.
The continuous casting heat number of the embodiment is 8; the surface quality diagram of the obtained strip steel product is shown in figure 1, and the surface quality diagram is good and has no recess and crack.
Example 2: the production method for improving the continuous casting heat of the high-aluminum steel adopts the following specific process.
(1) Controlling the components of the high-aluminum steel: the chemical composition and the mass percentage of the high-aluminum steel are shown in the table 1.
(2) The high-aluminum steel process flow is a duplex process production line of molten iron pretreatment-100 t converter-L F refining-RH refining-slab caster.
(3) Controlling the end point temperature of the converter to be 1690 ℃, the alkalinity of the final slag to be 3.8 and the end point oxygen to be 460 ppm; the slag blocking mode of the front sliding plate for blocking slag, the rear slag blocking mark and the sliding plate for blocking slag is adopted, the steel sand aluminum is automatically added by using the bin, the alloy material is added when the steel is tapped 1/5, and the alloy material is added when the steel is tapped 4/5.
(4) L F refining adopts 1.15bar micro-positive pressure operation, enters a station to make white slag operation, ensures that the smelting process is completely in a reducing atmosphere, controls the alkalinity of slag at 13, adopts a bottom blowing argon system, finely adjusts the components of molten steel, strictly controls the nitrogen content in steel to be less than 30ppm, and prevents the defect of casting blank caused by the generation of a large amount of AlN.
(5) Adopting an RH deep processing method, wherein the vacuum degree is less than 2mbar, the vacuum processing time is 22min, and the H content and the N content are 1ppm and 22ppm respectively after the vacuum processing.
(6) In the continuous casting process, the temperature of molten steel in a tundish is 1548 ℃, the superheat degree of the tundish is 30 ℃, the submerged casting is started and the whole-process protective casting is adopted, the continuous casting ladle is cast from a large ladle to the tundish by adopting a long nozzle and argon blowing protection, the protective casting pressure is 10.5Mpa and the argon flow is 102L/min, the high-alkalinity carbon-free low-silicon covering agent is added when the continuous casting is started, and a tundish stopper is usedArgon blowing stopper rod, argon flow 4.0L/min, magnesium aluminate spinel lining anti-blocking water port used for submerged nozzle, argon sealing flow control between submerged nozzle plates 7.5L/min, special casting powder for high-alumina steel is added when molten steel poured on the submerged nozzle passes through a side hole of the submerged nozzle, heat transfer and lubrication are controlled, good cooling conditions are provided for casting blanks, and the casting powder comprises SiO233%、CaO 30%、MgO 2.4%、Al2O33.2%、Fe2O30.6%、MnO23.3%、Na2O 12%、CaF211 percent, 4.5 percent of C, 0.9 percent of alkalinity, 0.18 Pa.s of viscosity and 0.7 kg/L of density, argon blowing control is adopted among a ladle sleeve, a tundish upper nozzle, a lower nozzle and a sliding plate, and the continuous casting drawing speed is controlled to be 1.4 m/min.
The continuous casting heat number of the embodiment is 8; the surface quality diagram of the obtained strip steel product is shown in figure 2, and the surface quality diagram is good and has no recess and crack.
Example 3: the production method for improving the continuous casting heat of the high-aluminum steel adopts the following specific process.
(1) Controlling the components of the high-aluminum steel: the chemical composition and the mass percentage of the high-aluminum steel are shown in the table 1.
(2) The high-aluminum steel process flow is a duplex process production line of molten iron pretreatment-100 t converter-L F refining-RH refining-slab caster.
(3) Controlling the end point temperature of the converter to be 1692 ℃, the final slag alkalinity to be 3.9 and the end point oxygen to be 600 ppm; the slag blocking mode of the front sliding plate for blocking slag, the rear slag blocking mark and the sliding plate for blocking slag is adopted, the steel sand aluminum is automatically added by using the bin, the alloy material is added when the steel is tapped 1/5, and the alloy material is added when the steel is tapped 4/5.
(4) L F refining adopts 1.05bar micro-positive pressure operation, enters a station to make white slag operation, ensures that the smelting process is completely in a reducing atmosphere, controls the alkalinity of slag at 14, adopts a bottom argon blowing system, finely adjusts the components of molten steel, strictly controls the nitrogen content in steel to be less than 30ppm, and prevents the defect of casting blank caused by the generation of a large amount of AlN.
(5) Adopting an RH deep processing method, wherein the vacuum degree is less than 2mbar, the vacuum processing time is 18min, and the H content and the N content after the vacuum processing are 1.2ppm and 28ppm respectively.
(6) Continuous castingIn the pouring process, the molten steel temperature of a tundish is 1550 ℃, the superheat degree of the tundish is 30 ℃, the submerged casting is adopted and the whole protective casting is carried out, the continuous casting from a large ladle to the tundish is carried out by adopting a long water gap and argon blowing protective casting, the protective casting pressure is 11Mpa and the argon flow is 108L/min, the casting is carried out, the high-alkalinity carbon-free low-silicon covering agent is added, the stopper of the tundish is an argon blowing stopper, the argon flow is 3.6L/min, the submerged nozzle is a magnesium aluminate spinel lining anti-blocking nozzle, the flow between submerged nozzle plates is sealed and controlled to be 9L/min, the special protective slag for the high-alumina steel is added when the molten steel for casting does not pass through the side holes of the submerged nozzle, the heat transfer and the lubrication are controlled, good cooling conditions are provided for the casting blank, and the protective slag is237%、CaO 27%、MgO2.5%、Al2O32.4%、Fe2O31.1%、MnO23.0%、Na2O 10%、CaF211 percent, 6.0 percent of C, 0.8 percent of alkalinity, 0.16 Pa.s of viscosity and 0.9 kg/L of density, argon blowing control is adopted among a ladle sleeve, a tundish upper nozzle, a lower nozzle and a sliding plate, and the continuous casting drawing speed is controlled to be 1.5 m/min.
The continuous casting heat number of the embodiment is 8; the surface quality chart of the obtained strip steel product is shown in figure 3, and the surface quality chart is good and has no recess and crack.
Example 4: the production method for improving the continuous casting heat of the high-aluminum steel adopts the following specific process.
(1) Controlling the components of the high-aluminum steel: the chemical composition and the mass percentage of the high-aluminum steel are shown in the table 1.
(2) The high-aluminum steel process flow is a duplex process production line of molten iron pretreatment-100 t converter-L F refining-RH refining-slab caster.
(3) Controlling the end point temperature of the converter to be 1683 ℃, controlling the alkalinity of the final slag to be 4.2 and controlling the end point oxygen to be 500 ppm; the slag blocking mode of the front sliding plate for blocking slag, the rear slag blocking mark and the sliding plate for blocking slag is adopted, the steel sand aluminum is automatically added by using the bin, the alloy material is added when the steel is tapped 1/5, and the alloy material is added when the steel is tapped 4/5.
(4) L F refining adopts 1.12bar micro-positive pressure operation, enters a station to make white slag operation, ensures that the smelting process is completely in a reducing atmosphere, controls the alkalinity of slag at 11, adopts a bottom argon blowing system, finely adjusts the components of molten steel, strictly controls the nitrogen content in steel to be less than 30ppm, and prevents the defect of casting blank caused by the generation of a large amount of AlN.
(5) Adopting an RH deep processing method, wherein the vacuum degree is less than 2mbar, the vacuum processing time is 15.5min, and the H content and the N content after the vacuum processing are respectively 1.4ppm and 21 ppm.
(6) In the continuous casting process, the molten steel temperature of a tundish is 1540 ℃, the superheat degree of the tundish is 25 ℃, the whole protective casting is carried out by adopting submerged casting, the continuous casting from a large ladle to the tundish is carried out by adopting a long water gap and argon blowing for protective casting, the protective casting pressure is 10Mpa and the argon flow is 110L/min, the casting is carried out by adding a high-alkalinity carbon-free low-silicon covering agent, an argon blowing stopper is used as a tundish stopper, the argon flow is 3.2L/min, a magnesium aluminate spinel lining anti-blocking water gap is used as a submerged nozzle, the argon sealing flow between submerged nozzles is controlled to be 6L/min, special high-alumina protective slag is added when the molten steel for casting does not pass through the side hole of the submerged nozzle, the heat transfer and lubrication are controlled, good cooling conditions are provided for a casting blank, and the protective slag comprises the following components of SiO234%、CaO 28%、MgO2.4%、Al2O33.5%、Fe2O31.3%、MnO24%、Na2O 10.3%、CaF211.8 percent, 4.7 percent of C, 0.82 percent of alkalinity, 0.15 Pa.s of viscosity and 0.8 kg/L of density, argon blowing control is adopted among a ladle sleeve, a tundish upper nozzle, a lower nozzle and a sliding plate, and the continuous casting drawing speed is controlled to be 1.45 m/min.
The continuous casting heat number of the embodiment is 8; the surface quality chart of the obtained strip steel product is shown in figure 4, and the surface quality chart is good and has no recess and crack.
Example 5: the production method for improving the continuous casting heat of the high-aluminum steel adopts the following specific process.
(1) Controlling the components of the high-aluminum steel: the chemical composition and the mass percentage of the high-aluminum steel are shown in the table 1.
(2) The high-aluminum steel process flow is a duplex process production line of molten iron pretreatment-100 t converter-L F refining-RH refining-slab caster.
(3) Controlling the end point temperature of the converter to be 1688 ℃, controlling the alkalinity of the final slag to be 4.1 and controlling the end point oxygen to be 520 ppm; the slag blocking mode of the front sliding plate for blocking slag, the rear slag blocking mark and the sliding plate for blocking slag is adopted, the steel sand aluminum is automatically added by using the bin, the alloy material is added when the steel is tapped 1/5, and the alloy material is added when the steel is tapped 4/5.
(4) L F refining adopts 1.08bar micro-positive pressure operation, enters a station to make white slag operation, ensures that the smelting process is completely in a reducing atmosphere, controls the alkalinity of slag to be 12.5, adopts a bottom argon blowing system, finely adjusts the components of molten steel, strictly controls the nitrogen content in the steel to be less than 30ppm, and prevents the defect of casting blank caused by a large amount of AlN.
(5) Adopting an RH deep processing method, wherein the vacuum degree is less than 2mbar, the vacuum processing time is 15.2min, and the H content and the N content after the vacuum processing are respectively 1.45ppm and 29 ppm.
(6) In the continuous casting process, the molten steel temperature of a tundish is 1542 ℃, the superheat degree of the tundish is 28 ℃, the whole protective casting is carried out by adopting immersed casting, the continuous casting from a large ladle to the tundish is carried out by adopting a long nozzle and argon blowing protective casting, the protective casting pressure is 10.7Mpa and the argon flow is 100L/min, the casting is carried out by adding a high-alkalinity carbon-free low-silicon covering agent, an argon blowing stopper is used as a tundish stopper, the argon flow is 3.0L/min, a magnesium aluminate spinel lining anti-blocking nozzle is used as an immersed nozzle, the argon sealing flow between immersed nozzle plates is controlled to be 8.2L/min, special protective slag for high-alumina steel is added when the molten steel for casting does not pass through the immersed side holes, the heat transfer and the lubrication are controlled, good cooling conditions are provided for a casting blank, and the protective slag is measured by mass percentage233.5%、CaO27.3%、MgO 2.5%、Al2O32.7%、Fe2O31.7%、MnO23.8%、Na2O 10.7%、CaF213 percent, 4.8 percent of C, 0.87 percent of alkalinity, 0.17 Pa.s of viscosity and 0.8 kg/L of density, argon blowing control is adopted among a ladle sleeve, a tundish upper nozzle, a lower nozzle and a sliding plate, and the continuous casting drawing speed is controlled to be 1.42 m/min.
The continuous casting heat number of the embodiment is 8; the obtained strip steel product has good surface quality and no recess and crack.
Table 1: the chemical composition and mass percentage (wt%) of the high-aluminum steel obtained in each example
The balance of the ingredients in table 1 is Fe and unavoidable impurities.
Claims (4)
1. A production method for improving continuous casting heat of high-aluminum steel is characterized by comprising the working procedures of molten iron pretreatment, converter, L F refining, RH refining and slab continuous casting, wherein in the working procedure of the converter, steel grit aluminum is automatically added into a converter bin, and slag-free steel tapping is realized through front and back double slag blocking operations, in the working procedure of the converter, L F refining is carried out through L F furnace micro-positive pressure operation, in the continuous casting working procedure, a high-alkalinity carbon-free low-silicon covering agent is added into pouring of a tundish, and an argon blowing stopper is used as a tundish stopper.
2. The production method for increasing the continuous casting heat of the high-aluminum steel according to claim 1 is characterized in that in the continuous casting process, submerged casting and full-process protective casting are adopted, a long nozzle and argon blowing protection casting are adopted from a continuous casting ladle to a tundish, the protective casting pressure is 10-11 MPa, and the argon flow is 100-110L/min.
3. The production method for increasing the continuous casting heat of the high-aluminum steel according to claim 1, wherein in the continuous casting process, the flow of argon gas of the argon blowing stopper rod is 3-4L/min, and the flow of argon seal between the immersion nozzle plates is 6-9L/min.
4. The production method for increasing the continuous casting heat of the high-aluminum steel according to any one of claims 1 to 3, characterized by comprising the following steps of: in the continuous casting process, the adopted casting powder comprises the following components in percentage by mass: SiO 2233%～37%，CaO 27%～30%，MgO 2.4%～2.5%，Al2O32.4%～3.5%，Fe2O30.6%～1.7%，MnO23%～4%，Na2O 10%～12%，CaF211%～13%，C 4.5%～6.0%。
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