CN113913582A - Smelting production method of large-section grinding ball steel round billet - Google Patents
Smelting production method of large-section grinding ball steel round billet 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
- C21C5/30—Regulating or controlling the blowing
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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
- 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
- C21C7/076—Use of slags or fluxes as treating agents
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- C—CHEMISTRY; METALLURGY
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- 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
- C21C7/10—Handling in a vacuum
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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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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of silicon
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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- 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
- C22C38/18—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
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
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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
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
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Abstract
The invention discloses a smelting production method of a large-section grinding ball steel round billet, which comprises a converter smelting process, an LF refining process, a VD vacuum treatment process and a continuous casting process. The invention solves the problems of high phosphorus and sulfur content of the round grinding ball steel billet, low product plasticity and poor surface quality. According to the invention, the proportion of subcutaneous fine grain regions is increased by controlling the water flow of the crystallizer, so that the generation of cracks is reduced; the submerged nozzle height is improved, the stirring parameters of the tail end of continuous casting are controlled, the level of inclusions in the casting blank is reduced, the generation of cracks on the surface of the casting blank is reduced, the surface quality is improved, and meanwhile, the low-power quality of the casting blank is improved.
Description
Technical Field
The invention belongs to the technical field of metallurgy, and particularly relates to a smelting production method of a large-section grinding ball steel round billet.
Background
The grinding ball steel is applied to the fields of metallurgical mines and cement building materials, the operation environment is very severe, and downstream customers require the grinding ball steel to have higher wear resistance, purity and surface quality. At present, the main technical problems of the grinding ball steel in the industry are as follows: 1. end users require products to have higher purity, which cannot be realized by common means. 2. The large-section carbon segregation control of the phi 600mm round billet is unstable, so that the hardness of the round billet used by an end user is uneven. 3. Cracks are easy to appear on the surface of the large-section high-silicon steel.
The reasons for these problems are: 1. at present, the phosphorus and sulfur contents of grinding ball steel produced by special steel enterprises are high, the control of A-type inclusions is high, and molten iron pretreatment is needed when the grinding ball steel is reproduced, so that the cost is increased. 2. The blast furnace molten iron directly enters a converter for smelting, so that the production of low-phosphorus and low-sulfur steel is difficult; the submerged nozzles of most enterprises have the depth of 110mm, and are easy to cause insufficient floating of inclusions. 3. The higher silicon content can improve the strength, hardness and hardenability of steel, reduce the critical cooling speed of martensite, improve the hardness of quenched martensite, and simultaneously can increase the tempering stability of the steel after quenching, but the surface quality of the grinding ball steel round billet has crack risk.
Therefore, the phosphorus and sulfur content of the large-section grinding ball steel round billet is reduced, the reduction of the product plasticity is avoided, and good surface quality is obtained, which is a problem to be solved urgently in the industry.
Disclosure of Invention
The invention aims to solve the technical problem of providing a smelting production method of a large-section grinding ball steel round billet. The invention can reduce the generation of surface cracks of the round billet, improve the surface quality and simultaneously improve the uniformity of the carbon component of the round billet.
In order to solve the technical problems, the invention adopts the technical scheme that: a large-section grinding ball steel round billet smelting production method comprises a converter smelting process, an LF refining process, a VD vacuum treatment process and a continuous casting process;
1) a converter smelting process: adding 20-25 kg of light burned dolomite per t of steel and 25-30 kg of lime per t of steel in the smelting process of a converter, pouring early-stage slag after blowing in the converter for 3-5min, adding the lime for secondary slagging, wherein the oxygen supply time is 13-17 min, and the oxygen consumption is 40-50m3Steel/t, steel is tapped by high-carbon-pulling of a converter, the tapping C is more than or equal to 0.08 percent, slag is removed and tapping is carried out, slag is strictly forbidden to be added during tapping, and the tapping temperature is 1610 and 1640 ℃; tapping molten steel P is less than or equal to 0.010 percent, S is less than or equal to 0.018 percent, and feeding aluminum wires according to 0.5-0.7 kg per t of steel after tapping;
2) an LF refining procedure: in the refining process, the consumption of lime is 2.5-5.5 kg per ton of steel, the refining slag is 1.0-2.0kg per ton of steel, and the holding time of the lime slag is more than or equal to 20 min; in the LF refining process, the consumption of silicon carbide is 3.0-4.5 kg/t steel, and the argon flow is controlled at 500-700 NL/min;
3) VD vacuum treatment process: the VD vacuum keeping time is more than or equal to 15min, the argon flow in the VD vacuum process is controlled at 100-450NL/min, and after the VD is broken, the Al: 0.020-0.030 percent of aluminum wire is fed, and the argon flow is less than or equal to 15-20L/min during soft blowing;
4) and (3) continuous casting process: the depth of the tundish nozzle is 90-100mm, the continuous casting drawing speed is controlled at 0.24-0.36m/min, a crystallizer is adopted for stirring and the tail end is adopted for stirring, and the electric stirring frequency is 5.0-6.0HZ, so that the large-section grinding ball steel round billet is obtained. The invention improves the height of the submerged nozzle (the depth of the tundish nozzle), controls the height from the liquid level to be 90-100mm, and can realize the reduction of the grade of casting blank inclusions and obtain good surface quality.
The specification of the large-section grinding ball steel round billet is phi 500-600 mm.
In the converter smelting process, in the steel tapping process, 2.0-4.0 kg of carburant per ton of steel, 1.5-2.0 kg of steel core aluminum, 12-14 kg of high-carbon ferromanganese per ton of steel, 13-15 kg of high-carbon ferrochrome per ton of steel, 22-25 kg of silicon-iron alloy per ton of steel, 6-8 kg of lime per ton of steel and 5-7 kg of refined slag per ton of steel are sequentially added.
In the converter smelting process, 2-3 tons of molten steel is left in the later tapping stage of the converter, so that the phosphorus content is high due to slag falling.
In the continuous casting process, the water amount of the crystallizer is 4200-4300L/min, and the specific water amount is 0.11-0.15L/kg. The grinding ball steel has high silicon content, and cracks are easy to generate on the surface, so that the water flow of the crystallizer is controlled, the proportion of a subcutaneous fine-grained region can be increased, a casting blank is timely fed, the generation of surface cracks is reduced, and good surface quality is obtained.
In the continuous casting process, the superheat degree of the continuous casting tundish is controlled at 20-30 ℃, the water quantity of the crystallizer is 4200 and 4300L/min, and the specific water quantity is 0.11-0.15L/kg.
In the continuous casting process, the crystallizer stirring and the tail end stirring are adopted, and the electric stirring current is 100-150A. In the continuous casting production process, the tail end stirring adopts a low current mode for production and low drawing speed, so that the grades of central looseness and shrinkage cavity can be effectively reduced.
The converter smelting process and the LF refining process have the following main components and ranges of refining slag: CaO: 52-58% of Al2O3：19-26%、SiO2：11-18%、MgO：4-5%、TFe≤0.5%。
The large-section grinding ball steel round billet comprises the following components in percentage by weight: 0.60-0.62%, Si: 1.76-1.84%, S is less than or equal to 0.002%, P is less than or equal to 0.010%, Cr: 0.77-0.82%, Cu: 0.01-0.02%, Ni: 0.01-0.02%, Mo: 0.005-0.02%, Ti: 0.017-0.02%, Alt: 0.015-0.024%, and the balance of Fe and inevitable impurities.
The invention discloses a large-section grinding ball steel round billet with the same section composition segregation: c is less than or equal to 0.04 percent, and the surface crack defect rate is less than or equal to 1 percent; the class A, class B, class C and class D inclusions are controlled within 1.0.
The yield of the large-section grinding ball steel round billet is 100% below the level of central porosity 1.0, the yield of the large-section grinding ball steel round billet is 100% below the level of shrinkage cavity 0.5, and the large-section grinding ball steel round billet has no defects of common porosity, subcutaneous cracks, central segregation and subcutaneous bubbles.
The insertion depth of the submerged nozzle has certain influence on the fluctuation value of the liquid level of the crystallizer, when the insertion depth is 110mm, the retention degree of molten steel at the upper part of the crystallizer is increased to inhibit the full floating of inclusions, meanwhile, the insertion depth of the nozzle is a main factor influencing a flow field, the size of the insertion depth determines the size of an upper reflux area and the size of a lower reflux area and the activity degree of the surface, and the surface is excessively stable when the depth is about 110mm, so that the melting of the casting powder is not facilitated. The depth of the tundish nozzle in the continuous casting process is set to be 90-100mm, and the method has the advantages that: (1) can promote the molten steel inclusion on the upper part of the crystallizer to fully float, and (2) the average wave height value of the liquid level of the crystallizer is small, the fluctuation value is stable, the maximum wave height value is small, and products with higher purity and surface quality are obtained.
Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: 1. the grinding ball steel round billet has higher silicon content, cracks are easy to form on the surface, the water flow of the crystallizer is controlled, the proportion of a subcutaneous fine-grained region is increased, and the surface cracks are reduced. 2. The invention improves the height of the submerged nozzle, reduces the grade of casting blank inclusions, obtains good surface quality and improves the uniformity of carbon components. 3. The invention controls the stirring parameters of the continuous casting tail end, and controls the carbon segregation within 0.04 percent. 4. The invention strengthens the early-stage deoxidation strength of the converter without molten iron pretreatment and a mixer, can leave a part of molten steel in the tapping process, avoids slag falling, can produce molten steel with phosphorus less than or equal to 0.010 percent, and saves the production cost. 5. The invention can reduce the generation of cracks on the surface of the casting blank, improve the surface quality and simultaneously improve the low-power quality of the casting blank, the qualification rate is 100 percent below the level of central porosity 1.0, the qualification rate is 100 percent below the level of shrinkage cavity 0.5, and the invention has no defects of common porosity, subcutaneous cracks, central segregation and subcutaneous bubbles.
Detailed Description
The present invention will be described in further detail with reference to specific examples.
Example 1
A smelting production method of a large-section grinding ball steel round billet comprises a converter smelting process, an LF refining process, a VD vacuum treatment process and a continuous casting process, and comprises the following specific production processes:
1. a converter smelting process: adding 21 kg of light-burned dolomite per t of steel and 27kg of lime per t of steel in the smelting process of the converter, pouring early-stage slag after blowing for 3min in the converter, adding lime for secondary slagging, wherein the oxygen supply time is 14 min, and the oxygen consumption is 42m3Steel/t, tapping by high-carbon-drawing of a converter, wherein the tapping C is 0.09 percent, slag-stopping tapping, slag-feeding is strictly prohibited, the tapping temperature is 1617 ℃, and carburant 2.6kg/t of steel is sequentially added in the tapping process,1.8kg of steel core aluminum per t, 13.7 kg of high-carbon ferromanganese per t of steel, 13.9 kg of high-carbon ferrochrome per t of steel, 22.5 kg of silicon-iron alloy per t of steel, 7kg of lime per t of steel, and 6kg of refining slag per t of steel, wherein the molten steel tapping ratio is 0.009%, and the molten steel tapping ratio is S: 0.015% and, to ensure diffusion deoxidation, aluminum wire was fed at 0.6 kg/t steel after tapping.
2 tons of molten steel is left at the later tapping stage of the converter to prevent phosphorus from being high due to slag discharging.
2. An LF refining procedure: in the refining process, the consumption of lime is 2.5 kg per t of steel, the consumption of refining slag is 1.1kg per t of steel, and the time for keeping the lime slag is 21 min; in the LF refining process, the consumption of silicon carbide is 3.5 kg/t steel, the argon flow is controlled at 510NL/min, and the refining slag system is shown in Table 1.
3. VD vacuum treatment process: VD holding time is 19min, the flow of argon in the VD process is controlled at 100NL/min, and after VD is emptied, the mass flow of the argon is controlled according to the following steps: feeding 0.023% of aluminum wires, wherein the flow of argon is 18L/min during soft blowing;
4. and (3) continuous casting process: the depth of a tundish nozzle is 95mm, the continuous casting drawing speed is controlled to be 0.36m/min, the water quantity of a crystallizer is 4300L/min, the specific water quantity is 0.11L/kg, the crystallizer stirring and the tail end stirring are adopted, the electric stirring current is 100A, the electric stirring frequency is 5.0HZ, the superheat degree of a continuous casting tundish is controlled to be 24 ℃, a large-section grinding ball steel round billet is obtained, and the segregation extremely difference C of the components of the same section is as follows: 0.04% and the surface crack defect rate is 0.8%.
The specification of the large-section grinding ball steel round billet is phi 600mm, the chemical composition and the percentage content thereof are shown in table 2, the inspection condition of impurities is shown in table 3, and the low-power quality condition is shown in table 4.
Example 2
A smelting production method of a large-section grinding ball steel round billet comprises a converter smelting process, an LF refining process, a VD vacuum treatment process and a continuous casting process, and comprises the following specific production processes:
1. a converter smelting process: adding 20 kg of light-burned dolomite per t of steel and 28kg of lime per t of steel in the smelting process of a converter, pouring out early-stage slag after blowing for 4min in the converter, adding lime for secondary slagging, wherein the oxygen supply time is 16min, and the oxygen consumption is 40m3Steel/t, tapping by high-carbon-drawing of a converter, tapping C: 0.10 percent of steel, slag-stopping and tapping, strictly stopping tapping and tapping, wherein the tapping temperature is 1620 ℃, 3.0kg/t of steel with carburant, 2.0kg/t of steel core aluminum and the like are sequentially added in the tapping process,13.2 kg of high-carbon ferromanganese per t of steel, 13.9 kg of high-carbon ferromanganese per t of steel, 23.3 kg of silicon-iron alloy per t of steel, 6kg of lime per t of steel, 6kg of refined slag per t of steel, and tapping molten steel P: 0.010%, S: 0.017% and feeding aluminum wires with per ton of steel according to 0.5 kg after tapping, in order to ensure diffusion deoxidation.
3 tons of molten steel is left in the later tapping stage of the converter to prevent phosphorus from being high due to slag discharging.
2. An LF refining procedure: in the refining process, the consumption of lime is 4.6 kg per t of steel, the consumption of refining slag is 1.2kg per t of steel, and the time for keeping the lime slag is 21 min; in the LF refining process, the consumption of silicon carbide is 3.7 kg/t steel, the argon flow is controlled at 550NL/min, and the refining slag system is shown in Table 1.
3. VD vacuum treatment process: VD holding time is 17min, the flow of argon in the VD process is controlled at 140NL/min, and after VD is emptied, the mass flow of the argon is controlled according to the following steps: 0.025% aluminum wire was fed, argon flow during soft blowing: 19L/min;
4. and (3) continuous casting process: the depth of a tundish nozzle is 90mm, the continuous casting drawing speed is controlled to be 0.24m/min, the water quantity of a crystallizer is 4200L/min, the specific water quantity is 0.15L/kg, the crystallizer is adopted for stirring and tail end stirring, the electric stirring current is 120A, the electric stirring frequency is 6.0HZ, the superheat degree of a continuous casting tundish is controlled to be 23 ℃, a large-section grinding ball steel round billet is obtained, and the segregation extremely difference C of the components of the same section is as follows: 0.03 percent and the surface crack defect rate is 0.65 percent.
The specification of the large-section grinding ball steel round billet is phi 500mm, the chemical composition and the percentage content thereof are shown in table 2, the inspection condition of impurities is shown in table 3, and the low-power quality condition is shown in table 4.
Example 3
A smelting production method of a large-section grinding ball steel round billet comprises a converter smelting process, an LF refining process, a VD vacuum treatment process and a continuous casting process, and comprises the following specific production processes:
1. a converter smelting process: adding 23 kg of light-burned dolomite per t of steel and 25kg of lime per t of steel in the smelting process of the converter, pouring early-stage slag after blowing for 3min in the converter, adding lime for secondary slagging, wherein the oxygen supply time is 15min, and the oxygen consumption is 41m3Steel/t, tapping by high-carbon-drawing of a converter, tapping C:0.09 percent of steel, pushing off slag and tapping, strictly tapping and forbidding tapping, wherein the tapping temperature is 1640 ℃, and 2.0kg of carburant per ton of steel, 1.9 kg of steel core aluminum and 14 kg of high-carbon ferromanganese are sequentially added in the tapping processThe steel comprises 14.2 kg of high-carbon ferrochrome per t of steel, 23.1 kg of silicon-iron alloy per t of steel, 8kg of lime per t of steel, 5kg of refining slag per t of steel, and tapping molten steel P: 0.008%, S: 0.016%, and feeding aluminum wires according to 0.7 kg/t steel after tapping, in order to ensure diffusion deoxidation.
3 tons of molten steel is left in the later tapping stage of the converter to prevent phosphorus from being high due to slag discharging.
2. An LF refining procedure: the consumption of lime in the refining process is 4.7 kg/t steel, the consumption of refining slag is 1.0kg/t steel, and the white slag retention time is as follows: 23 min; in the LF refining process, the consumption of silicon carbide is 3.6 kg/t steel, the argon flow is controlled at 500NL/min, and the refining slag system is shown in Table 1.
3. VD vacuum treatment process: VD holding time is 19min, the flow rate of argon in the VD process is controlled at 230NL/min, and after VD is emptied, the mass flow of the argon is controlled according to the following steps: feeding 0.022% of aluminum wires, and performing soft blowing with 18L/min of argon flow;
4. and (3) continuous casting process: the depth of a tundish nozzle is 98mm, the continuous casting drawing speed is controlled to be 0.36m/min, the water quantity of a crystallizer is 4300L/min, the specific water quantity is 0.11L/kg, the crystallizer stirring and the tail end stirring are adopted, the electric stirring current is 140A, the electric stirring frequency is 6.0HZ, the superheat degree of a continuous casting tundish is controlled to be 30 ℃, a large-section grinding ball steel round billet is obtained, and the segregation extremely-poor C of the same section component is obtained: 0.04% and the surface crack defect rate is 0.74%.
The specification of the large-section grinding ball steel round billet is phi 500mm, the chemical composition and the percentage content thereof are shown in table 2, the inspection condition of impurities is shown in table 3, and the low-power quality condition is shown in table 4.
Example 4
A smelting production method of a large-section grinding ball steel round billet comprises a converter smelting process, an LF refining process, a VD vacuum treatment process and a continuous casting process, and comprises the following specific production processes:
1. a converter smelting process: adding 25kg/t of light-burned dolomite into the steel in the smelting process of the converter, pouring early-stage slag after blowing in the converter for 4min, adding lime into the steel for secondary slagging, wherein the oxygen supply time is 17min, and the oxygen consumption is 47m3Steel/t, tapping by high-carbon-drawing of a converter, tapping C: 0.08 percent of steel, pushing off slag, tapping, strictly keeping from tapping, tapping at 1627 ℃, sequentially adding recarburizer 2.6kg/t of steel, steel core aluminum 1.8kg/t of steel, high-carbon ferromanganese 13 kg/t of steel and high-carbon ferrochrome 13 kg/g of steel in the tapping processSteel/t, 23.3 kg of ferrosilicon alloy per steel, 6kg of lime per steel, 6kg of refining slag per steel, and tapping molten steel P: 0.008%, S: 0.018% aluminum wire was fed in per ton of steel at 0.7 kg after tapping to ensure diffusion deoxygenation.
2 tons of molten steel is left at the later tapping stage of the converter to prevent phosphorus from being high due to slag discharging.
2. An LF refining procedure: in the refining process, the consumption of lime is 4.1 kg per ton of steel, the consumption of refining slag is 1.6kg per ton of steel, and the time for keeping the lime slag is 20 min; in the LF refining process, the consumption of silicon carbide is 3.0kg/t steel, the argon flow is controlled at 630NL/min, and the refining slag system is shown in Table 1.
3. VD vacuum treatment process: VD holding time is 17min, the flow of argon in the VD process is controlled at 300NL/min, and after VD is emptied, the mass flow of the argon is controlled according to Al: 0.030 percent of aluminum wire is fed, and the argon flow is 20L/min during soft blowing;
4. and (3) continuous casting process: the depth of a tundish nozzle is 100mm, the continuous casting drawing speed is controlled to be 0.36m/min, the water quantity of a crystallizer is 4300L/min, the specific water quantity is 0.11L/kg, the crystallizer stirring and the tail end stirring are adopted, the electric stirring current is 100A, the electric stirring frequency is 5.0HZ, the superheat degree of a continuous casting tundish is controlled to be 28 ℃, a large-section grinding ball steel round billet is obtained, and the segregation extremely difference C of the components of the same section is as follows: 0.04% and the surface crack defect rate is 0.95%.
The specification of the large-section grinding ball steel round billet is phi 560mm, the chemical composition and the percentage content thereof are shown in Table 2, the inspection condition of impurities is shown in Table 3, and the low-power quality condition is shown in Table 4.
Example 5
A smelting production method of a large-section grinding ball steel round billet comprises a converter smelting process, an LF refining process, a VD vacuum treatment process and a continuous casting process, and comprises the following specific production processes:
1. a converter smelting process: adding 21 kg of light-burned dolomite per t of steel and 30kg of lime per t of steel in the smelting process of the converter, pouring early-stage slag after blowing in the converter for 5min, adding the lime for secondary slagging, wherein the oxygen supply time is 16min, and the oxygen consumption is 50m3Steel/t, tapping by high-carbon-drawing of a converter, tapping C:0.09 percent of steel, slag blocking and tapping are performed, tapping is strictly prohibited, the tapping temperature is 1610 ℃, and in the tapping process, 2.0kg of carburant, 1.8kg of steel core aluminum, 12.7 kg of high-carbon ferromanganese per t of steel, 12.7 kg of high-carbon ferrochrome per t of steel and ferrosilicon alloy are sequentially addedEvery t of steel, every 7kg of lime, every 7kg of refining slag, and tapping molten steel P:0.009%, S: 0.015% and, to ensure diffusion deoxidation, aluminum wire was fed at 0.5 kg/t steel after tapping.
3 tons of molten steel is left in the later tapping stage of the converter to prevent phosphorus from being high due to slag discharging.
2. An LF refining procedure: in the refining process, the consumption of lime is 5.2 kg per t of steel, the consumption of refining slag is 1.7kg per t of steel, and the time for keeping the lime slag is 22 min; in the LF refining process, the consumption of silicon carbide is 4.5 kg/t steel, the argon flow is controlled at 580NL/min, and the refining slag system is shown in Table 1.
3. VD vacuum treatment process: VD holding time is 15min, the flow of argon in the VD process is controlled at 450NL/min, and after VD is emptied, the mass flow of the argon is controlled according to the following steps: feeding 0.028% of aluminum wires, and feeding argon flow of 15L/min during soft blowing;
4. and (3) continuous casting process: the depth of a tundish nozzle is 98mm, the continuous casting drawing speed is controlled to be 0.30m/min, the water quantity of a crystallizer is 4220L/min, the specific water quantity is 0.13L/kg, the crystallizer stirring and the tail end stirring are adopted, the electric stirring current is 100A, the electric stirring frequency is 5.0HZ, the superheat degree of a continuous casting tundish is controlled to be 20 ℃, a large-section grinding ball steel round billet is obtained, and the segregation of the components of the same section is as follows: c: 0.02% and the surface crack defect rate is 0.42%.
The specification of the large-section grinding ball steel round billet is phi 540mm, the chemical composition and the percentage content thereof are shown in table 2, the inspection condition of impurities is shown in table 3, and the low-power quality condition is shown in table 4.
Example 6
A smelting production method of a large-section grinding ball steel round billet comprises a converter smelting process, an LF refining process, a VD vacuum treatment process and a continuous casting process, and comprises the following specific production processes:
1. a converter smelting process: adding 22 kg of light-burned dolomite per t of steel and 27kg of lime per t of steel in the smelting process of a converter, pouring out early-stage slag after blowing for 4min in the converter, adding lime for secondary slagging, wherein the oxygen supply time is 13 min, and the oxygen consumption is 48m3Steel/t, tapping by high-carbon-drawing of a converter, tapping C: 0.08%, slag stopping and tapping are performed, tapping is strictly prohibited, the tapping temperature is 1637 ℃, 3.8kg of carburant per t of steel, 1.7kg of steel core aluminum per t of steel, 12 kg of high-carbon ferromanganese per t of steel, 14.4 kg of high-carbon ferrochrome per t of steel, 25kg of silicon-iron alloy per t of steel, and 7kg of lime per t of steel are sequentially added in the tapping processTapping molten steel P:0.009%, S: 0.017% and feeding aluminum wires with per ton of steel according to 0.6 kg after tapping, in order to ensure diffusion deoxidation.
2-3 tons of molten steel are left in the later tapping period of the converter to prevent phosphorus from being high due to slag.
2. An LF refining procedure: in the refining process, the consumption of lime is 4.5 kg per t of steel, the consumption of refining slag is 1.8kg per t of steel, and the time for keeping the lime slag is 20 min; in the LF refining process, the consumption of silicon carbide is 4.0kg/t steel, the argon flow is controlled at 700NL/min, and the refining slag system is shown in Table 1.
3. VD vacuum treatment process: VD is kept for 16min, the flow of argon in the VD process is controlled at 280NL/min, and after VD is emptied, the mass flow of the argon is controlled according to the following steps: 0.020 feeding aluminum wire, and the argon flow is 19L/min during soft blowing;
4. and (3) continuous casting process: the depth of a tundish nozzle is 90mm, the continuous casting drawing speed is controlled to be 0.24m/min, the water quantity of a crystallizer is 4230L/min, the specific water quantity is 0.14L/kg, the crystallizer stirring and the tail end stirring are adopted, the electric stirring current is 150A, the electric stirring frequency is 5.7HZ, the superheat degree of a continuous casting tundish is controlled to be 24 ℃, a large-section grinding ball steel round billet is obtained, and the segregation extremely difference C of the components of the same section is as follows: 0.03 percent and the surface crack defect rate is 0.6 percent.
The specification of the large-section grinding ball steel round billet is phi 550mm, the chemical composition and the percentage content thereof are shown in table 2, the inspection condition of impurities is shown in table 3, and the low-power quality condition is shown in table 4.
Example 7
A smelting production method of a large-section grinding ball steel round billet comprises a converter smelting process, an LF refining process, a VD vacuum treatment process and a continuous casting process, and comprises the following specific production processes:
1. a converter smelting process: adding 23 kg of light-burned dolomite per t of steel and 26kg of lime per t of steel in the smelting process of the converter, pouring early-stage slag after blowing in the converter for 5min, adding lime for secondary slagging, wherein the oxygen supply time is 15min, and the oxygen consumption is 45m3Steel/t, tapping by high-carbon-drawing of a converter, tapping C: 0.10 percent of steel, slag stopping and tapping, tapping is strictly prohibited, the tapping temperature is 1625 ℃, 4.0kg of carburant, 1.9 kg of steel core aluminum, 12.2 kg of high-carbon ferromanganese per ton of steel, 15 kg of high-carbon ferromanganese per ton of steel, 24.6 kg of silicon-iron alloy per ton of steel, 6kg of lime per ton of steel and 6kg of refined slag per ton of steel are sequentially added in the tapping process,tapping molten steel P: 0.010%, S: 0.016%, and feeding aluminum wires according to 0.7 kg/t steel after tapping, in order to ensure diffusion deoxidation.
2-3 tons of molten steel are left in the later tapping period of the converter to prevent phosphorus from being high due to slag.
2. An LF refining procedure: in the refining process, the consumption of lime is 5.4 kg per t of steel, the consumption of refining slag is 1.8kg per t of steel, and the time for keeping the lime slag is 21 min; in the LF refining process, the consumption of silicon carbide is 4.1 kg per t of steel, the argon flow is controlled at 640NL/min, and the refining slag system is shown in Table 1.
3. VD vacuum treatment process: VD holding time is 15min, the flow of argon in the VD process is controlled at 450NL/min, and after VD is emptied, the mass flow of the argon is controlled according to the following steps: 0.024 feeding aluminum wire, wherein the argon flow is 20L/min during soft blowing;
4. and (3) continuous casting process: the depth of a tundish nozzle is 96mm, the continuous casting drawing speed is controlled to be 0.35m/min, the water quantity of a crystallizer is 4290L/min, the specific water quantity is 0.12L/kg, the crystallizer stirring and the tail end stirring are adopted, the electric stirring current is 100A, the electric stirring frequency is 5.7HZ, the superheat degree of a continuous casting tundish is controlled to be 20 ℃, a large-section grinding ball steel round billet is obtained, and the segregation extremely difference C of the components of the same section is as follows: 0.03 percent and the surface crack defect rate is 0.5 percent.
The specification of the large-section grinding ball steel round billet is 600mm, the chemical composition and the percentage content thereof are shown in table 2, the inspection condition of impurities is shown in table 3, and the low-power quality condition is shown in table 4.
Example 8
A smelting production method of a large-section grinding ball steel round billet comprises a converter smelting process, an LF refining process, a VD vacuum treatment process and a continuous casting process, and comprises the following specific production processes:
1. a converter smelting process: adding 24 kg/t of light-burned dolomite in the smelting process of the converter and 26kg/t of lime into the converter, pouring early-stage slag after blowing in the converter for 3min, adding lime into the converter to carry out secondary slagging, wherein the oxygen supply time is 14 min, and the oxygen consumption is 49m3Steel/t, tapping by high-carbon-drawing of a converter, tapping C: 0.08%, slag stopping and tapping are performed, tapping is strictly prohibited, the tapping temperature is 1638 ℃, 3.4kg of carburant per ton of steel is sequentially added in the tapping process, 1.5 kg of steel core aluminum per ton of steel, 13.4 kg of high-carbon ferromanganese per ton of steel, 14.3 kg of high-carbon ferromanganese per ton of steel, 24 kg of silicon-iron alloy per ton of steel, 8kg of lime per ton of steel, 7kg of refined slag per ton of steel, and tapping molten steel P: 0.010%,S: 0.015% and, to ensure diffusion deoxidation, aluminum wire was fed at 0.6 kg/t steel after tapping.
2-3 tons of molten steel are left in the later tapping period of the converter to prevent phosphorus from being high due to slag.
2. An LF refining procedure: in the refining process, the consumption of lime is 5.5 kg per t of steel, the consumption of refining slag is 2.0kg per t of steel, and the time for keeping the lime slag is 23 min; in the LF refining process, the consumption of silicon carbide is 4.2 kg/t steel, the argon flow is controlled at 620NL/min, and the refining slag system is shown in Table 1.
3. VD vacuum treatment process: VD is kept for 16min, the flow of argon in the VD process is controlled at 170NL/min, and after VD is emptied, the mass flow of the argon is controlled according to the following steps: feeding 0.027% of aluminum wire, and performing soft blowing with the argon flow of 19L/min;
4. and (3) continuous casting process: the depth of a tundish nozzle is 97mm, the continuous casting drawing speed is controlled to be 0.25m/min, the water quantity of a crystallizer is 4250L/min, the specific water quantity is 0.14L/kg, the crystallizer stirring and the tail end stirring are adopted, the electric stirring current is 130A, the electric stirring frequency is 5.3HZ, the superheat degree of a continuous casting tundish is controlled to be 25 ℃, a large-section grinding ball steel round billet is obtained, and the segregation extremely difference C of the components of the same section is as follows: 0.03 percent and the surface crack defect rate is 0.63 percent.
The specification of the large-section grinding ball steel round billet is phi 500mm, the chemical composition and the percentage content thereof are shown in table 2, the inspection condition of impurities is shown in table 3, and the low-power quality condition is shown in table 4.
Table 1 examples 1 to 8 refining slag based composition (%)
Table 2 examples 1-8 round billets of large cross-section grinding ball steel and their chemical compositions and percentages
The balance of the ingredients in table 2 is Fe and unavoidable impurities.
TABLE 3 inspection of inclusions in round billets of large cross-section grinding ball steels in examples 1 to 8
TABLE 4 examples 1-8 low-power quality of large-section round grinding ball steel billets
Although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that: modifications and equivalents may be made thereto without departing from the spirit and scope of the invention and it is intended to cover in the claims the invention as defined in the appended claims.
Claims (10)
1. A smelting production method of a large-section grinding ball steel round billet is characterized by comprising a converter smelting process, an LF refining process, a VD vacuum treatment process and a continuous casting process;
1) a converter smelting process: adding 20-25 kg of light burned dolomite per t of steel and 25-30 kg of lime per t of steel in the smelting process of a converter, pouring early-stage slag after blowing in the converter for 3-5min, adding the lime for secondary slagging, wherein the oxygen supply time is 13-17 min, and the oxygen consumption is 40-50m3Steel/t, steel is tapped by high-carbon-pulling of a converter, the tapping C is more than or equal to 0.08 percent, slag is removed and tapping is carried out, slag is strictly forbidden to be added during tapping, and the tapping temperature is 1610 and 1640 ℃; tapping molten steel P is less than or equal to 0.010 percent, S is less than or equal to 0.018 percent, and feeding aluminum wires according to 0.5-0.7 kg per t of steel after tapping;
2) an LF refining procedure: in the refining process, the consumption of lime is 2.5-5.5 kg per ton of steel, the refining slag is 1.0-2.0kg per ton of steel, and the holding time of the lime slag is more than or equal to 20 min; in the LF refining process, the consumption of silicon carbide is 3.0-4.5 kg/t steel, and the argon flow is controlled at 500-700 NL/min;
3) VD vacuum treatment process: the VD vacuum keeping time is more than or equal to 15min, the argon flow in the VD vacuum process is controlled at 100-450NL/min, and after the VD is broken, the Al: 0.020-0.030 percent of aluminum wire is fed, and the argon flow is less than or equal to 15-20L/min during soft blowing;
4) and (3) continuous casting process: the depth of the tundish nozzle is 90-100mm, the continuous casting drawing speed is controlled at 0.24-0.36m/min, a crystallizer is adopted for stirring and the tail end is adopted for stirring, and the electric stirring frequency is 5.0-6.0HZ, so that the large-section grinding ball steel round billet is obtained.
2. The method for producing large-section grinding ball steel round billet through smelting as claimed in claim 1, wherein the specification of the large-section grinding ball steel round billet is phi 500-600 mm.
3. The smelting production method of the round steel billet of the high-profile grinding ball steel according to claim 1, wherein in the converter smelting process and in the steel tapping process, sequentially adding 2.0 to 4.0kg of carburant, 1.5 to 2.0kg of steel core aluminum, 12 to 14 kg of high-carbon ferromanganese per ton steel, 13 to 15 kg of high-carbon ferrochrome per ton steel, 22 to 25kg of ferrosilicon per ton steel, 6 to 8kg of lime per ton steel and 5 to 7kg of refined slag per ton steel.
4. The method for smelting and producing the large-section grinding ball steel round billet according to the claim 1, characterized in that in the converter smelting process, 2 to 3 tons of molten steel are left at the later stage of converter tapping so as to prevent phosphorus from being high due to slag.
5. The method for producing the large-section grinding ball steel round billet by smelting as claimed in any one of claims 1 to 4, characterized in that in the continuous casting process, the superheat degree of the continuous casting tundish is controlled at 20-30 ℃, the water amount of the crystallizer is 4200-4300L/min, and the specific water amount is 0.11-0.15L/kg.
6. The method for producing large-section grinding ball steel round billet by smelting as claimed in any one of claims 1 to 4, wherein the continuous casting process adopts crystallizer stirring and end stirring, and the electric stirring current is 100-150A.
7. The method for smelting and producing the round steel billet of the large-section grinding ball steel as claimed in any one of claims 1 to 4, wherein the converter smelting process and the LF refining process comprise the following main components and ranges of refining slag: CaO: 52-58% of Al2O3：19-26%、SiO2：11-18%、MgO：4-5%、TFe≤0.5%。
8. The smelting production method of the large-section grinding ball steel round billet according to any one of claims 1 to 4, characterized in that the large-section grinding ball steel round billet has the composition range of C: 0.60-0.62%, Si: 1.76 to 1.84%, Mn: 0.73-0.77%, S is less than or equal to 0.002%, P is less than or equal to 0.010%, Cr: 0.77-0.82%, Cu: 0.01-0.02%, Ni: 0.01-0.02%, Mo: 0.005-0.02%, Ti: 0.017-0.02%, Alt: 0.015-0.024%, and the balance of Fe and inevitable impurities.
9. The smelting production method of the large-section grinding ball steel round billet according to any one of claims 1 to 4, characterized in that the large-section grinding ball steel round billet has the same section component segregation: c is less than or equal to 0.04 percent, and the surface crack defect rate is less than or equal to 1 percent; the class A, class B, class C and class D inclusions are controlled within 1.0.
10. The method for smelting and producing the large-section grinding ball steel round billet according to any one of claims 1 to 4, wherein the yield of the large-section grinding ball steel round billet is 100% below 1.0 grade of center porosity, the yield of the large-section grinding ball steel round billet is 100% below 0.5 grade of shrinkage cavity, and the large-section grinding ball steel round billet has no general porosity, subcutaneous cracks, center segregation and subcutaneous bubble defects.
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