CN113215477B - Preparation method of low-carbon-emission cold-rolled base steel strip - Google Patents
Preparation method of low-carbon-emission cold-rolled base steel strip Download PDFInfo
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- 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
- C22C33/06—Making ferrous alloys by melting using master alloys
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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
- B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
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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
- B22D11/16—Controlling or regulating processes or operations
- B22D11/18—Controlling or regulating processes or operations for pouring
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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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- 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
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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
- C21C7/0056—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
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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
- C21C7/0087—Treatment of slags covering the steel bath, e.g. for separating slag from the molten metal
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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
- C21C7/064—Dephosphorising; Desulfurising
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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
- C21C7/072—Treatment with gases
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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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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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
- C22C38/002—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
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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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
- C21C7/0006—Adding metallic additives
- C21C2007/0018—Boron
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- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
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- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/009—Pearlite
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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
Abstract
The invention discloses a preparation method of a low-carbon-emission cold-rolled base steel strip, which belongs to the field of ferrous metallurgy and comprises the process routes of smelting in a top-bottom combined blown converter, washing slag discharged from the converter to remove impurities, continuously casting a plate blank and hot continuous rolling to produce a low-carbon low-silicon boron-containing cold-rolled deep-drawing base steel strip. The material prepared by the method is designed by adopting low-carbon and low-silicon components, the LF refining process is omitted, inclusions are removed by deoxidation in the converter tapping process, continuous casting is carried out, the recovery rate of boron is ensured, and the performance stability of steel is improved. The LF refining process is omitted, the nitrogen content in the steel is reduced, the quality of the strip steel is improved, electrode consumption does not exist in the production process, the power consumption and the carbon dioxide emission are reduced, and a new method is provided for converter smelting and slab continuous casting of the boron-containing low-carbon low-silicon cold-rolled base steel strip.
Description
Technical Field
The invention relates to a preparation method of a low-carbon-emission cold-rolled base steel strip, which belongs to the field of ferrous metallurgy and comprises the process routes of smelting in a top-bottom combined blown converter, washing slag discharged from the converter to remove impurities, continuously casting a plate blank and hot continuous rolling to produce a low-carbon low-silicon boron-containing cold-rolled deep-drawing base steel strip.
Technical Field
A cold-rolled steel base band and a production method of steelmaking are generally used for preparing a plate blank meeting the specification requirement by molten iron pretreatment desulfurization, converter smelting, LF refining or RH vacuum treatment and plate blank continuous casting, and then producing a steel coil (base band) meeting the cold-rolled requirement through hot continuous rolling.
The literature retrieval shows that the smelting method of boron-containing steel in the ferrous metallurgy industry needs to be subjected to LF treatment, and some boron and iron need to be added for alloying through VD or RH vacuum treatment to improve the yield of boron.
For the steel for the cold-rolled base band with low carbon, low silicon and low manganese content, the silicon and manganese content is extremely low, the silicon and manganese deoxidation is weakened, and only the aluminum deoxidation can be adopted, so that the Al generated by the aluminum deoxidation2O3Is mixed with or formed by Al2O3The main factor of the composite impurities of oxides of calcium and magnesium is that the main factor influences the product quality, even influences the smooth running of the continuous casting of the plate blank, and secondly, because boron is very easy to oxidize in steel for the cold-rolled base band with low carbon, low silicon and low manganese content, the steel can be produced only by manufacturing reducing slag through LF refining, but the mechanical property and the cold stamping forming property of the cold-rolled base material are influenced by increasing nitrogen in molten steel caused by the LF refining treatment process.
Disclosure of Invention
The invention aims to provide a preparation method of a cold-rolled base steel strip with low carbon emission, which achieves the production purpose of a cold-rolled base strip with low cost and low carbon dioxide emission, which cannot be achieved by the existing steelmaking technology.
The technical scheme adopted by the invention is as follows: a preparation method of a low-carbon-emission cold-rolled base steel strip comprises the following steps:
1. the process flow comprises the following steps: carrying out desulfurization pretreatment on molten iron, smelting by a 120t top-bottom combined blown converter, carrying out deoxidation alloying on converter tapping, removing impurities, continuously casting a plate blank and carrying out 1750 hot continuous rolling;
2. designing the components of the steel: the steel comprises the following components: c: 0.04-0.08 wt%, Si: less than or equal to 0.030 wt%, Mn: 0.15-0.25 wt%, P: less than or equal to 0.018 wt%, S: less than or equal to 0.012 wt%, Al: 0.020-0.035 wt%, N: less than or equal to 0.0035 wt%, B: 0.0010-0.0018 wt%, and the balance of iron and impurities;
3. the slag washing material comprises the following components in parts by weight: preparing a slag washing material: the slag washing material is sintered synthetic slag which comprises the following components: pre-melted slag is prepared according to the following weight percentage of CaO: al (Al)2O3The mass percentage ratio of the active lime to the fluorite is 1.4-1.6, the active lime, the fluorite and the synthetic slag are mixed uniformly and sintered, the sintered premelting slag is mixed with the active lime, the fluorite and the synthetic slag according to the mass percentage of 30%, 5% and 65%, and the granularity of the mixture is not more than 5mm and is used as a slag washing material in the converter tapping process;
4. ladle management: in order to accurately control the temperature drop of molten steel in the continuous casting process, the steel ladle is immediately baked after the continuous casting is finished, the temperature of the inner wall of the steel ladle is not less than 800 ℃, a new steel ladle or a new overhaul steel ladle is not allowed to be used, and 3 steel ladles are turned over;
5. the preparation method comprises the following steps: [1]Molten iron desulphurization pretreatment: after desulfurization, the sulfur content of the molten iron is not more than 0.003 percent, and the temperature of the molten iron is more than 1280 ℃; [2]Smelting in a converter: charging the molten iron into a furnace by about 100 tons, scrap steel by 25-30 tons, active lime by 3 tons, magnesite by 1 ton, and oxygen blowing strength of a converter by 2.8-3.2 Nm3At the time of blowing for 4 minutes, adding 500-1500 tons of iron oxide cold bonded pellet coolant into each furnace steel according to the temperature of molten steel in the converter for cooling and dephosphorization; the carbon of converter tapping is not more than 0.060%; phosphorus is not more than 0.015 percent; sulfur is not more than 0.010%; the temperature of molten steel is 1665-1675 ℃, and the converter tapping adopts a sliding plate to block slag; [3]Tapping by a converter: the converter adopts a sliding plate to block slag and tap steel, the slag discharge amount of steel in each furnace is controlled to be 260-320 kg, alloy is added in the tapping process, when the tapping amount of the converter reaches one fourth, 1.75kg/t of sintered manganese balls are added into steel per ton, the manganese content of the sintered manganese balls is more than 95%, then 100-150 kg of aluminum iron is added, 300kg of slag washing material is added into steel per furnace while the aluminum iron is added, according to the slag fluidity, 50-220 kg of active lime is added into steel per furnace, the lime granularity is not more than 5mm, after tapping, 150-200 kg of slag modifying accelerant is added into the slag at the top of a steel ladle, the main components of the accelerant are shown in the following table, the temperature of molten steel is reduced by 35-45 ℃ in the tapping process, and the difference value between the blowing endpoint of the converter and the molten steel temperature of the steel in an argon blowing station is obtained;
main component of steel ladle top slag modifying accelerant
[4] After tapping of the converter is finished, argon is blown to the bottom of molten steel in a steel ladle for strong stirring, oxygen is determined at the same time, an aluminum wire is fed according to the oxygen content in the steel, the recovery rate of aluminum is calculated according to 40%, and the aluminum content in the steel is more than 0.035%; continuously stirring for 10-12 min, wherein the sum of FeO and MnO in the slag is less than or equal to 1.5%, and the mass percentage is calculated;
[5] after the argon blowing and strong stirring at the bottom of the steel ladle are finished, feeding a 350-400 m calcium-iron wire into the steel ladle, strictly forbidding using a calcium-silicon wire to prevent silicon increase of molten steel, performing calcium treatment, wherein the feeding speed of the calcium wire is 3.5-4 m/s, and the temperature drop of the molten steel in the calcium treatment process is set to be not more than 15 ℃;
[6] after the calcium treatment is finished, the molten steel is subjected to soft blowing, argon is blown from the bottom of the steel ladle for weak stirring, and the molten steel is preferably turned over but not exposed: and covering and protecting the molten steel by ladle top slag, and controlling the soft blowing time to be 8-10 min. The inclusion is promoted to float upwards and be removed by the entrainment and the driving of the soft argon blowing tail bubbles;
[7] and adding ferroboron after the weak stirring, wherein the content of boron is 14%, the weight of the molten steel is calculated according to 120 tons, the adding amount of the ferroboron is 15-17 kg per furnace steel, the argon blowing weak stirring time is 4min after the ferroboron is added, and the recovery rate of boron can reach 88-93%. The continuous casting and steel feeding temperature is 1585-1590 ℃ in a continuous casting furnace, and 1600-1605 ℃ in a tundish casting furnace;
[8] and (3) continuously casting the slab, wherein the thickness of the continuously cast slab is 250mm, the width of the continuously cast slab is 1260mm, all connecting parts through which the continuously cast molten steel passes are cast by adopting argon gas closed protection, and the steel is continuously cast at a constant casting speed in each furnace, wherein the casting speed is controlled to be 1.5-1.55 m/min. Because of low carbon and low manganese, the center segregation of the plate blank can be ignored;
[9] rolling a hot-rolled coil with the thickness of 1.80-3.0 mm by adopting a 1750 hot continuous rolling mill, hot-charging and rolling a plate blank, wherein the temperature of the plate blank in a heating furnace is 650-720 ℃, the discharging temperature of the plate blank from the heating furnace is 1180-1210 ℃, the outlet temperature of a rough rolling is 1150-1180 ℃, the finish rolling temperature of a finish rolling is 865-880 ℃, the design target finish rolling temperature is 870 ℃, and the coiling temperature is 632-640 ℃.
The 10-furnace steel produced by the method has the components of a smelted product and the oxygen and nitrogen analysis results of materials, namely the components of a finished smelted steel product; the mechanical property, the material structure and the grain size of the material of the hot continuous rolling rolled steel coil and the analysis result of the nonmetallic inclusion in the steel are shown as the performance, the structure and the purity of the rolled steel. The carbon content in the steel is not more than 0.060% and the maximum silicon content is 0.030%. And (3) detecting steel, wherein the oxygen content is not more than 0.0040%, the maximum nitrogen content is 0.0033%, and the boron content is controlled to be 0.0012-0.0016%. It is shown that it is completely feasible to produce low carbon, low silicon, low nitrogen, boron containing cold rolling base stock without LF refining treatment.
Test steel smelting finished product composition
Rolled steel properties, structure and purity
The material prepared by the method is designed by adopting low-carbon and low-silicon components, the LF refining process is omitted, inclusions are removed by deoxidation in the converter tapping process, continuous casting is carried out, the recovery rate of boron is ensured, and the performance stability of steel is improved. The LF refining process is omitted, the nitrogen content in the steel is reduced, the quality of the strip steel is improved, electrode consumption does not exist in the production process, the power consumption and the carbon dioxide emission are reduced, and a new method is provided for converter smelting and slab continuous casting of the boron-containing low-carbon low-silicon cold-rolled base steel strip.
Detailed Description
The technical scheme adopted by the invention is as follows: a preparation method of a low-carbon-emission cold-rolled base steel strip comprises the following steps:
1. the process flow comprises the following steps: carrying out desulfurization pretreatment on molten iron, smelting by a 120t top-bottom combined blown converter, carrying out deoxidation alloying on converter tapping, removing impurities, continuously casting a plate blank and carrying out 1750 hot continuous rolling;
2. designing the components of the steel: the steel comprises the following components: c: 0.04-0.08 wt%, Si: less than or equal to 0.030 wt%, Mn: 0.15-0.25 wt%, P: less than or equal to 0.018 wt%, S: less than or equal to 0.012 wt%, Al: 0.020-0.035 wt%, N: less than or equal to 0.0035 wt%, B: 0.0010-0.0018 wt%, and the balance of iron and impurities;
3. the slag washing material comprises the following components in parts by weight: preparing a slag washing material: the slag washing material is sintered synthetic slag which comprises the following components: pre-melted slag is prepared according to the proportion of CaO: al (Al)2O3The mass percentage ratio of the active lime to the fluorite is 1.4-1.6, the active lime, the fluorite and the synthetic slag are mixed according to the mass percentage of 30%, 5% and 65%, the granularity of the mixture is not more than 5mm, and the mixture is prepared by mixing the active lime, the fluorite and the synthetic slag uniformlyWashing slag in the converter tapping process;
4. ladle management: in order to accurately control the temperature drop of molten steel in the continuous casting process, the steel ladle is immediately baked after the continuous casting is finished, the temperature of the inner wall of the steel ladle is not less than 800 ℃, a new steel ladle or a new overhaul steel ladle is not allowed to be used, and 3 steel ladles are turned over;
5. the preparation method comprises the following steps: [1]Molten iron desulphurization pretreatment: after desulfurization, the sulfur content of the molten iron is not more than 0.003 percent, and the temperature of the molten iron is more than 1280 ℃; [2]Smelting in a converter: charging the molten iron into a furnace by about 100 tons, scrap steel by 25-30 tons, active lime by 3 tons, magnesite by 1 ton, and oxygen blowing strength of a converter by 2.8-3.2 Nm3At the time of blowing for 4 minutes, adding 500-1500 tons of iron oxide cold-bonded pellet coolant into each steel furnace according to the temperature of molten steel in the converter for cooling and dephosphorizing; the carbon of converter tapping is not more than 0.060%; phosphorus is not more than 0.015 percent; sulfur is not more than 0.010%; the temperature of molten steel is 1665-1675 ℃, and the converter tapping adopts a sliding plate to block slag; [3]Tapping by a converter: the converter adopts a sliding plate to block slag and tap steel, the slag discharging amount of steel in each furnace is controlled to be 260-320 kg, alloy is added in the tapping process, when the tapping amount of the converter reaches one fourth, 1.75kg/t of sintered manganese balls are added into steel per ton to sinter manganese balls, the manganese content is more than 95%, then 100-150 kg of aluminum iron is added, 300kg of slag washing material is added into steel per furnace while adding aluminum iron, according to the fluidity of slag, 50-220 kg of active lime is added into steel per furnace, the granularity of lime is not more than 5mm, after tapping is finished, 150-200 kg of slag modifying accelerant is added into slag at the top of steel ladle, and the main components of the accelerant are shown in Table 1. The temperature of molten steel is reduced by 35-45 ℃ in the tapping process, and the difference between the converter blowing end point and the temperature of molten steel in a steel ladle of an argon blowing station is obtained;
the main component of the steel ladle top slag modification accelerant%
[4] After tapping of the converter is finished, argon is blown to the bottom of molten steel in a steel ladle for strong stirring, oxygen is determined at the same time, an aluminum wire is fed according to the oxygen content in the steel, the recovery rate of aluminum is calculated according to 40%, and the aluminum content in the steel is more than 0.035%; the strong stirring is continued for 10-12 min, the sum of FeO and MnO in the slag is less than or equal to 1.5%, and the mass percentage is calculated;
[5] after the argon blowing and strong stirring at the bottom of the steel ladle are finished, feeding a 350-400 m calcium-iron wire into the steel ladle, strictly forbidding using a calcium-silicon wire to prevent silicon increase of molten steel, performing calcium treatment, wherein the feeding speed of the calcium wire is 3.5-4 m/s, and the temperature drop of the molten steel in the calcium treatment process is set to be not more than 15 ℃;
[6] after the calcium treatment is finished, the molten steel is subjected to soft blowing, argon is blown from the bottom of the steel ladle for weak stirring, and the molten steel is preferably turned over but not exposed: covering and protecting the molten steel by ladle top slag, and controlling the soft blowing time to be 8-10 min. The inclusion is promoted to float upwards and be removed by the entrainment and the driving of the soft argon blowing tail bubbles;
[7] and adding ferroboron after the weak stirring, wherein the content of boron is 14%, the weight of the molten steel is calculated according to 120 tons, the adding amount of the ferroboron is 15-17 kg per furnace steel, the argon blowing weak stirring time is 4min after the ferroboron is added, and the recovery rate of boron can reach 88-93%. The continuous casting and steel feeding temperature is 1585-1590 ℃ in a continuous casting furnace, and 1600-1605 ℃ in a tundish casting furnace;
[8] and (3) continuously casting the slab, wherein the thickness of the continuously cast slab is 250mm, the width of the continuously cast slab is 1260mm, all connecting parts through which the continuously cast molten steel passes are cast by adopting argon gas closed protection, and the steel is continuously cast at a constant casting speed in each furnace, wherein the casting speed is controlled to be 1.5-1.55 m/min. Because of low carbon and low manganese, the center segregation of the plate blank can be ignored;
[9] rolling a hot-rolled coil with the thickness of 1.80-3.0 mm by adopting a 1750 hot continuous rolling mill, hot-charging and rolling a plate blank, wherein the temperature of the plate blank in a heating furnace is 650-720 ℃, the discharging temperature of the plate blank from the heating furnace is 1180-1210 ℃, the outlet temperature of a rough rolling is 1150-1180 ℃, the finish rolling temperature of a finish rolling is 865-880 ℃, the design target finish rolling temperature is 870 ℃, and the coiling temperature is 632-640 ℃.
Claims (1)
1. A preparation method of a low-carbon-emission cold-rolled base steel strip is characterized by comprising the following steps:
1) and the process flow is as follows: carrying out molten iron desulphurization pretreatment, smelting by a 120-ton top-bottom combined blown converter, carrying out deoxidation alloying on converter tapping, removing impurities, carrying out slab continuous casting, and carrying out 1750 hot continuous rolling;
2) and designing the components of the steel: the steel comprises the following components: c: 0.04-0.08 wt%, Si: less than or equal to 0.030 wt%, Mn: 0.15-0.25 wt%, P: less than or equal to 0.018 wt%, S: less than or equal to 0.012 wt%, Al: 0.020-0.035 wt%, N: less than or equal to 0.0035 wt%, B: 0.0010-0.0018 wt%, and the balance of iron and impurities;
3) the slag washing material comprises the following components in parts by weight: preparation of slag washing material: the slag washing material is sintered synthetic slag which comprises the following components: pre-melted slag is prepared according to the following weight percentage of CaO: al (Al)2O3The pre-melted slag is mixed with active lime and fluorite according to the mass percentage of 30%, 5% and 65%, the granularity of the mixture is not more than 5mm, and the mixture is used as slag washing material in the converter tapping process;
4) and steel ladle management: in order to accurately control the temperature drop of molten steel in the continuous casting process, the steel ladle is immediately baked after the continuous casting is finished, the temperature of the inner wall of the steel ladle is not less than 800 ℃, a new steel ladle is not allowed to be used, and 3 steel ladles are turned over;
5) the preparation method comprises the following steps:
[1] molten iron desulphurization pretreatment: after desulfurization, the sulfur content of the molten iron is not more than 0.003 percent, and the temperature of the molten iron is more than 1280 ℃;
[2]smelting in a converter: charging molten iron into a furnace of 100 tons, scrap steel of 25-30 tons, active lime of 3 tons and magnesite of 1 ton, wherein the oxygen blowing strength of the converter is 2.8-3.2 Nm/ton steel3And/min, after blowing for 4 minutes, adding 500-1500 tons of iron oxide cold-bonded pellet coolant into each steel furnace according to the temperature of molten steel in the converter for cooling and dephosphorization; the carbon of converter tapping is not more than 0.060%, the phosphorus is not more than 0.015%, the sulfur is not more than 0.010%, the temperature of molten steel is 1665-1675 ℃, and the converter tapping adopts a sliding plate to block slag;
[3]tapping by a converter: the converter adopts a sliding plate to block slag and tap steel, the slag amount of steel in each furnace is controlled to be 260-320 kg, alloy is added in the tapping process, when the tapping amount of the converter reaches one fourth, 1.75 kg/ton of sintered manganese balls are added into each ton of steel, the manganese content of the sintered manganese balls is more than 95%, then 100-150 kg of aluminum iron is added, 300kg of slag washing material is added into each ton of steel while the aluminum iron is added, 50-220 kg of active lime is added into each ton of steel according to the slag fluidity, the lime granularity is not more than 5mm, after tapping, 150-200 kg of slag modifying accelerant is added into the slag at the top of a steel ladle, the temperature of molten steel is reduced by 35-45 ℃ in the tapping process, and the temperature of molten steel in the converter is between the blowing end point and the molten steel temperature of steel in a ladle in an argon blowing stationA difference of (d); the steel ladle top slag modification accelerant comprises the following components: CaO content 35%, Al2O3Content of 30% SiO2Content is less than or equal to 5 percent, CaF25 percent of MgO, less than or equal to 4 percent of S, less than 0.01 percent of Al and 30 percent of Al;
[4] after tapping of the converter is finished, argon is blown to the bottom of molten steel in a steel ladle for strong stirring, oxygen is determined at the same time, an aluminum wire is fed according to the oxygen content in the steel, the recovery rate of aluminum is calculated according to 40%, and the aluminum content in the steel is more than 0.035%; continuously stirring for 10-12 min, wherein the sum of FeO and MnO in the slag is less than or equal to 1.5 wt%;
[5] after the argon blowing and strong stirring at the bottom of the steel ladle are finished, feeding a 350-400 m calcium-iron wire into the steel ladle, strictly forbidding using a calcium-silicon wire to prevent silicon increase of molten steel, performing calcium treatment, wherein the feeding speed of the calcium wire is 3.5-4 m/s, and the temperature drop of the molten steel in the calcium treatment process is set to be not more than 15 ℃;
[6] after the calcium treatment is finished, the molten steel is subjected to soft blowing, argon is blown from the bottom of the steel ladle for weak stirring, and the molten steel is preferably turned over but not exposed: covering and protecting the molten steel by ladle top slag, controlling the soft blowing time to be 8-10 min, and driving inclusions to float upwards and remove through soft blowing of argon tail bubble entrainment;
[7] adding ferroboron after the weak stirring, wherein the boron content is 14%, the weight of the molten steel is calculated according to 120 tons, the adding amount of the ferroboron is 15-17 kg per furnace steel, the argon blowing weak stirring time is 4min after the adding, the recovery rate of boron is 88-93%, the continuous casting steel feeding temperature is 1585-1590 ℃ in a continuous casting furnace, and the tundish casting furnace is 1600-1605 ℃;
[8] continuously casting the plate blank, wherein the thickness of the continuously cast plate blank is 250mm, the width of the continuously cast plate blank is 1260mm, all connecting parts through which the continuously cast molten steel passes are cast by adopting argon gas closed protection, the steel is continuously cast at a constant casting speed in each furnace, the casting speed is controlled to be 1.5-1.55 m/min, and the center segregation of the plate blank is negligible due to low carbon and low manganese;
[9] rolling a hot-rolled coil with the thickness of 1.80-3.0 mm by adopting a 1750 hot continuous rolling mill, hot-charging and rolling a plate blank, wherein the temperature of the plate blank in a heating furnace is 650-720 ℃, the discharging temperature of the plate blank from the heating furnace is 1180-1210 ℃, the outlet temperature of a rough rolling is 1150-1180 ℃, the finish rolling temperature of a finish rolling is 865-880 ℃, the design target finish rolling temperature is 870 ℃, and the coiling temperature is 632-640 ℃.
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