CN114871392A - Production method for smelting steel of different slag system components in modularized classification manner - Google Patents
Production method for smelting steel of different slag system components in modularized classification manner 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
- 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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- 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
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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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- 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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- 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
- 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
- C21C7/10—Handling in a vacuum
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Abstract
The invention discloses a production method for smelting variety steel by modularly classifying different slag system components, which comprises the following specific operation steps: step 1, converter primary smelting; step 2, LF refining; step 3, VD vacuum degassing; step 4, continuous casting and pouring; and 5, continuous rolling. The invention adopts low-phosphorus control, so that the cleanliness of molten steel is greatly improved, the average level of A-type and B-type inclusions is reduced by 0.5, the level of C-type inclusions is reduced by 1.0, and the occurrence probability of D-type inclusions is reduced by 70%. The production method not only effectively improves the surface quality of the steel after cogging, continuous rolling and scalping, reduces or avoids the tower-shaped hairline defects of rolled materials and forged materials, particularly greatly reduces the hairline defects of S-containing steel, and improves the magnetic powder inspection qualification rate of finished samples of downstream customers; but also effectively solves the quality problem of overproof inclusions, so that the rejection rate is reduced, and the economic benefit of enterprises is effectively improved.
Description
Technical Field
The invention belongs to the technical field of high-speed wire rod smelting, and particularly relates to a production method of steel of different slag system component modularization classification smelting product types.
Background
With the rapid development of the special steel industry in China, the demand of various industries on various steel products is higher and higher, and the special steel products are various, and relate to steel products such as low, medium and high carbon, microalloy, high alloy, rare earth alloy and the like. The steel products have different varieties and different performance requirements, the steel plant frequently adjusts different slag systems of various types of steel to seriously affect the smelting work efficiency, and the slag systems are changed along with the switching of the varieties, so the difficulty of high-efficiency smelting production is difficult to overcome.
Before the traditional steel smelting, the steel slag system has various types and is not highly instructive to the field operation; the operation of workers is easy to make mistakes, which causes the instability of slag systems, and the unstable slag systems cause large quality fluctuation.
Disclosure of Invention
The invention aims to provide a production method for smelting various steels by modularly classifying different slag system components, which solves the problem that the smelting work efficiency is seriously influenced by frequently adjusting different slag systems of various steels in the prior art.
The invention adopts the technical scheme that the production method for smelting the variety steel by modularly classifying different slag system components comprises the following specific operation steps:
1, dividing steel modules into eight categories according to various steel characteristics, pretreating KR molten iron, and carrying out converter primary smelting;
step 2, tapping from a converter: adding deoxidized aluminum into a ladle for pre-deoxidation in steel flow, then adding premelting slag and a deoxidizer to reduce the total oxygen content of molten steel, and adding lime when tapping 1/3;
step 3, LF refining: controlling the time from the end of the primary smelting and tapping of the converter to the time of entering an LF refining station within 12 min; before refining, the argon flow is 150 plus 200NL/min, the stirring is carried out for 2-3min, and the argon flow is controlled to be 100 plus 150NL/min in the LF refining process; feeding the materials into a tank, supplying power and heating the materials, adding alloy and lime ash into the tank in 2-3 batches, and adding aluminum particles and silicon carbide into the tank; during the period, a steel sample and a slag sample are taken for analyzing chemical components, and before LF refining is finished, when the chemical components of the steel sample and the slag system components reach the control target requirement and the temperature is controlled at 1600-;
step 4, VD vacuum degassing: the control conditions of the vacuum degassing process are that the argon flow is 50-100NL/min in rough vacuum, and the argon flow is 100-150NL/min in extreme vacuum; the steam pressure is more than or equal to 0.90Mpa, the steam temperature is more than or equal to 175 ℃, and the water temperature is less than or equal to 30 ℃; the extreme vacuum retention time is more than or equal to 20 minutes; h is less than or equal to 1.5ppm when measured by a Herrie online hydrogen determination instrument;
wherein, the rough vacuum means the vacuum degree is more than 200 torr, and the extreme vacuum means the vacuum degree is less than or equal to 0.5 torr;
and 5, continuous casting: step 4, after vacuum degassing, moving the ladle into a refining furnace for heating and soft blowing, and when the temperature of the molten steel meets the continuous casting temperature, hanging the ladle into a continuous casting machine for continuous casting and casting a continuous casting blank to obtain a semi-finished casting blank with O, N content and endogenous inclusions meeting the standard requirement of high-quality steel; the standard requirements of the high-quality steel are as follows: o is less than or equal to 10 ppm.
And 5, continuously rolling to obtain the corresponding variety of steel.
The present invention is also characterized in that,
step 1 the steel is classified according to modularization and comprises the following steps:
one type is as follows: sulfur-containing non-quenched and tempered steel: comprises C38+ N, C70S6BY, C38N2, 49MnVS3 and 36MnVS4 series steel grades;
the second type is as follows: high-aluminum steel: 38CrMo Al and 09Cr2AlMoRe series steel grades;
three types are as follows: low silicon sulfur and aluminum control steel: MnCr5 series steel grade;
four types: high carbon bearing steel: GCr15, GCr18Mo series steel grade;
and five types are as follows: high carbon steel: 605M36, 55SiMoMo, 80B, T8, T10 series steel grade;
six types: medium carbon alloy structural steel: 42CrMo, 40Mn2, 40Cr series steel grade;
seven types: low-carbon alloy structural steel: 15Ni4Mo, 18CrNiMo7-6, 19CrNi5, 20CrMnTiH, 20CrNiMo and gear steel series steel grades;
eight types: carburizing bearing steel: g20CrNi2Mo and G20Cr2Ni4 series steel grades.
And 2, adding the following materials in the converter tapping process:
sulfur-containing non-quenched and tempered steel: 6.5-7.0 g of lime per ton of steel, 1.2-1.5 g of deoxidizer per ton of steel, 2.6-3.0 g of premelting slag per ton of steel and 0.6-0.8 g of deoxidized aluminum per ton of steel;
high aluminum steel (medium carbon): 8.5-10 kg of lime per ton of steel, 1.5-1.8 kg of deoxidizer per ton of steel, 3.0-3.5 kg of premelting slag per ton of steel and 2.5-2.8 kg of deoxidized aluminum per ton of steel;
high aluminum steel (low carbon): 10-12 kg of lime per ton of steel, 1.5-1.8 kg of deoxidizing agent per ton of steel, 2.8-3.2 kg of premelting slag per ton of steel, 1.0-1.2 kg of fluorite per ton of steel, and 3.4-3.6 kg of deoxidized aluminum per ton of steel;
low silicon sulfur and aluminum control steel: 8-10 kg of lime per ton of steel, 1.3-1.6 kg of deoxidizer per ton of steel, 3.7-4.0 kg of premelting slag per ton of steel and 1.6-2.0 kg of deoxidized aluminum per ton of steel;
high carbon bearing steel: lime 7-8 kg/ton steel, pre-melted slag 5-7 kg/ton steel and deoxidized aluminum 1.1-1.3 kg/ton steel;
high carbon steel: 6-8 kg of lime per ton of steel, 1.4-1.7 kg of deoxidizer per ton of steel, 2.6-2.9 kg of premelting slag per ton of steel and 0.8-1.0 kg of deoxidized aluminum per ton of steel;
medium carbon alloy structural steel: lime 7-10 kg/ton steel, deoxidizer 1.3-1.5 kg/ton steel, premelting slag 4.0-4.3 kg/ton steel and deoxidized aluminum 1.0-1.3 kg/ton steel;
low-carbon alloy structural steel: 8-10 kg of lime per ton of steel, 1.4-1.6 kg of deoxidizer per ton of steel, 3.5-3.8 kg of premelting slag per ton of steel and 1.3-1.6 kg of deoxidized aluminum per ton of steel;
carburizing bearing steel: lime 7-9 kg/ton steel, premelting slag 5.5-5.8 kg/ton steel and deoxidized aluminum 1.2-1.5 kg/ton steel.
In the refining process in the step 3, the types and the contents of the added ingredients are as follows:
sulfur-containing non-quenched and tempered steel: 0-1.2 kg of lime and 0.5-0.8 kg of silicon carbide per ton of steel; the slag system target is controlled as follows according to the mass percentage: FeO: not more than 0.85 percent and SiO 2 12～18％，CaO50～55％，MgO3～7％， Al 2 O 3 15-20%, wherein the sum of the mass percentages is 100%; wherein the basic oxide CaO and the acidic oxide SiO are 2 The ratio R of the mass percentages of the components is 3-5;
high aluminum steel (medium carbon): lime 1.0-2.0 kg/ton steel, silicon carbide 0.4-0.6 kg/ton steel and aluminum particles 0.15-0.20 kg/ton steel; the slag system target is controlled as follows according to the mass percentage: FeO: not more than 0.60 percent and SiO 2 ≤8％，CaO 50～ 55％，MgO3～7％，Al 2 O 3 25-35%, wherein the sum of the mass percentages is 100%; wherein the basic oxide CaO and the acidic oxide SiO are 2 The ratio R of the mass percentages of the components is 6-9;
high aluminum steel (low carbon): lime 1.0-1.4 kg/ton steel, silicon carbide 0.4 kg/ton steel and aluminum particles 0.20-0.30 kg/ton steel; the slag system target is controlled by the following mass percentage: FeO: not more than 0.60 percent and SiO 2 ≤8％，CaO 50～ 55％，MgO3～7％，Al 2 O 3 28-35%, wherein the sum of the mass percentages is 100%; wherein the basic oxide CaO and the acidic oxide SiO are 2 The ratio R of the mass percentages of the components is 7-10;
low silicon sulfur and aluminum control steel: 0-1.5 kg of lime per ton of steel, 0.3-0.5 kg of silicon carbide per ton of steel and 0.30-0.50 kg of aluminum particles per ton of steel; the slag system target is controlled as follows according to the mass percentage: FeO: not more than 0.80 percent and SiO 2 ≤8％，CaO 50～ 55％，MgO 3～7％，Al 2 O 3 20-28%, wherein the sum of the mass percentages is 100%; wherein the basic oxide CaO and the acidic oxide SiO are 2 The ratio R of the mass percentages of the components is 5-8;
high carbon bearing steel: 0-1.0 kg of lime per ton of steel, 0.7-1.0 kg of silicon carbide per ton of steel and 0.15-0.20 kg of aluminum particles per ton of steel; the slag system target is controlled as follows according to the mass percentage: FeO: not more than 0.60 percent and SiO 2 6～10％，CaO 55～ 60％，MgO 3～7％，Al 2 O 3 25-28%, wherein the sum of the mass percentages is 100%; wherein the basic oxide CaO and the acidic oxide SiO are 2 The ratio R of the mass percentages of the components is 6-8;
high-carbon steel: 0-0.8 kg of lime per ton of steel, 0.8-1.0 kg of silicon carbide per ton of steel and 0.12-0.16 kg of aluminum particles per ton of steel; the slag system target is controlled by the following mass percentage: FeO: not more than 0.80 percent and SiO 2 8～10％，CaO 55～ 60％，MgO 3～7％，Al 2 O 3 20-28%, wherein the sum of the mass percentages is 100%; wherein the basic oxide CaO and the acidic oxide SiO are 2 The ratio R of the mass percentages of the components is 6-8;
medium carbon alloy structural steel: 0-1.5 kg of lime per ton of steel, 1.0-1.5 kg of silicon carbide per ton of steel and 0-1.0 kg of pre-melted slag per ton of steel; the slag system target is controlled as follows according to the mass percentage: FeO: not more than 0.80 percent and SiO 2 8～12％，CaO 53～58％，MgO 3～7％，Al 2 O 3 22-28%, wherein the sum of the mass percentages is 100%; wherein the basic oxide CaO and the acidic oxide SiO are 2 The ratio R of the mass percentages of the components is 5-7;
low-carbon alloy structural steel: 0-1.2 kg of lime and 1.0-1.5 kg of silicon carbide per ton of steel; the slag system target is controlled as follows according to the mass percentage: FeO: not more than 0.80 percent and SiO 2 8～12％，CaO 50～60％，MgO 3～7％，Al 2 O 3 20-28%, wherein the sum of the mass percentages is 100%; wherein the basic oxide CaO and the acidic oxide SiO are 2 The ratio R of the mass percentages of the components is 5-8;
carburizing bearing steel: 0 to 1.4kg of lime per ton of steel, 0.8 to 1.2kg of silicon carbide per ton of steel and 0.15 kg of aluminum particles-0.25 kg/ton steel; the slag system target is controlled as follows according to the mass percentage: FeO: not more than 0.80 percent and SiO 2 7～10％，CaO 50～60％，MgO 3～7％，Al 2 O 3 22-28%, wherein the sum of the mass percentages is 100%; wherein the basic oxide CaO and the acidic oxide SiO are 2 The ratio R of the mass percentages of (A) to (B) is 6-8.
And 4, the continuous casting and pouring specifically comprises the following steps: and (3) adopting the pulling speed control of a crystallizer: when the degree of superheat is 11-20 ℃, the pulling speed is 0.38 m/min; when the degree of superheat is 20-29 ℃, the pulling speed is 0.36 m/min; when the degree of superheat is 30-40 ℃, the pulling speed is 0.34 m/min; electromagnetic stirring: head end 450A/1.5Hz, tail end 660A/7.5 Hz; the baking time of the tundish is more than 5 hours; before casting, the time for purging the tundish with argon is more than or equal to 8 minutes, and the flow of the argon is 10 +/-5 NL/min; the insertion depth of the immersion type water gap: 160-190 mm; the casting furnace uses stainless steel covering slag.
The continuous rolling in the step 6 specifically comprises the following steps:
the first step is as follows: heating the blank in a heating furnace, wherein the temperature of a heating section is 1000-1280 ℃, and the temperature of a soaking section is 1200-1270 ℃; the high-temperature diffusion time is more than or equal to 3.5 h; the total heating time is 8-12h, and the tapping speed is less than or equal to 15 pieces/h;
and a second step of rolling: firstly, a BD rolling mill is adopted: the initial rolling temperature is more than or equal to 1050 ℃, and the continuous rolling finishing temperature is more than or equal to 1000 ℃; and then adopting a horizontal and vertical rolling mill: the initial rolling temperature is 920 +/-10 ℃; the finishing temperature is 900 plus or minus 20 ℃; cooling the steel by a rack type cooling bed and then putting the steel into a heat preservation pit, wherein the temperature of the steel entering the pit is more than or equal to 450 ℃; the heat preservation time of the steel entering the pit is more than or equal to 48 hours.
And (3) dephosphorization control of water in the rolling process: and (3) water is sprayed twice to remove phosphorus, and the water phosphorus removal pressure is 20-25 MPa.
The invention has the beneficial effects that:
(1) the production method for smelting various steels by modularly classifying different slag system components, disclosed by the invention, modularly classifies hundreds of steels according to various steel characteristics, and introduces eight types of modularization standards: sulfur-containing non-quenched and tempered steel, high-aluminum steel, low-silicon sulfur-controlled and aluminum-controlled steel, high-carbon bearing steel, high-carbon steel, medium-carbon alloy structural steel, low-carbon alloy structural steel, gear steel and carburized bearing steel.
(2) The production method for smelting the variety steel by modularizing and classifying different slag system components adopts the technology of combining the converter modularized slag system, the smelting low-phosphorus control technology and the LF refining modularized slag system to smelt the variety steel with high cleanliness.
(3) According to the production method for smelting the steel of the variety by modularly classifying the different slag system components, low P control is adopted, the cleanliness of molten steel is greatly improved, the average level of A-type and B-type inclusions is reduced by 0.5, the level of C-type inclusions is reduced by 1.0, and the occurrence probability of D-type inclusions is reduced by 70%.
(4) The production method for smelting the variety steel by modularly classifying different slag system components not only effectively improves the surface quality of steel after cogging, continuous rolling and scalping; but also effectively solves the quality problem of overproof inclusions, so that the rejection rate is reduced, and the economic benefit of the steel-making branch plants is effectively improved.
(5) The production method of the steel of the modularized classification smelting variety with different slag system components leads the smelting casting times of the steel smelting separate factory to be promoted from the prior five-continuous casting and six-continuous casting steel types to the ten-continuous casting, even to reach the twelve-continuous casting, improves the production efficiency by 38.56 percent, and promotes the yield from the prior 4.93 ten thousand tons per month to the prior 7.64 ten thousand tons per month
Detailed Description
Example 1
The embodiment relates to a production method for smelting variety steel by modularly classifying different slag system components, which comprises four steps of converter primary smelting, LF refining, VD vacuum degassing, continuous casting and pouring, and continuous rolling, and specifically comprises the following steps: the examples are exemplified by a class of sulfur-containing non-quenched and tempered steels:
(1) converter primary smelting
The steel material consists of molten iron, scrap steel and pig iron, and the converter slag is added according to a modular standard, as shown in the following table 1:
TABLE 1
The converter steel tapping C is more than or equal to 0.08 percent, the P is less than or equal to 0.012 percent, the steel tapping amount is 120 +/-3 tons, the steel tapping time is more than or equal to 240s, 0.6 to 0.8Kg of pure aluminum is added into the converter steel tapping per ton according to the conversion, and the adding sequence of the deoxidizer is as follows: al ingot → premelting slag → alloy → lime.
(2) LF refining + VD
The temperature of the LF refining furnace is required to be more than or equal to 1510 ℃, and the refining slag-regulating slag is added according to a modular standard, as shown in the following table 2:
TABLE 2
The use of silicon-calcium-aluminum powder is forbidden in the LF refining process, white slag is quickly formed in a tank, carbon powder and silicon carbide are used for diffusion deoxidation, the white slag is kept in the whole process, the white slag keeping time is more than or equal to 40 minutes, and Al: 0.015-0.020%, the alloy components before VD meet the internal control requirement, the extreme vacuum holding time is more than or equal to 15min (nitrogen is blown when the extreme vacuum is carried out, the nitrogen blowing amount after VD is reduced), the nitrogen control target is 150 ppm, the argon cleaning time is more than or equal to 40min after nitrogen blowing is finished for preventing the continuous casting billet from having surface and subcutaneous defects, and the Ti and Al + Ti requirements are adjusted: 0.016-0.024% (controlled by upper limit), adding Ti after N is controlled to be qualified, and the weak argon time must be more than or equal to 20min after the components are adjusted for the last time.
(3) Continuous casting:
2300 × 2L/min of crystallizer water, secondary cooling curve: B-GR2MC-GR2, target superheat degree: 20-30 ℃; and (3) pulling speed control: the drawing speed is 0.38m/min at the superheat degree of 11-20 ℃, 0.36m/min at the superheat degree of 20-29 ℃, 0.34m/min at the superheat degree of 30-40 ℃; height of liquid level of crystallizer: 135 mm; electromagnetic stirring: head end 450A/1.5Hz, tail end 660A/7.5 Hz; the baking time of the tundish is more than 5 hours; before casting, the time for purging the tundish with argon is more than or equal to 8 minutes, and the flow of the argon is 10 +/-5 NL/min; immersion type water gap insertion depth: 160-190 mm; the casting furnace uses stainless steel covering slag, the continuous casting furnace uses special covering slag for continuous casting medium carbon, and the thickness of a slag layer is 30-40 mm; the secondary package uses alkaline covering agent.
(4) Continuous rolling
Heating the blank with the thickness of 400mm multiplied by 560mm in a heating furnace, wherein the temperature of a heating section is 1000-1280 ℃, and the temperature of a soaking section is 1200-1270 ℃; the high-temperature diffusion time is more than or equal to 3.5 h; the total heating time is 8-12h, and the tapping speed is less than or equal to 15 pieces/h. BD rolling mill: the initial rolling temperature is more than or equal to 1050 ℃, and the continuous rolling finishing temperature is more than or equal to 1000 ℃; a horizontal and vertical rolling mill: the initial rolling temperature is 920 +/-10 ℃; the finishing temperature is 900 +/-20 ℃. Cooling the steel by a rack type cooling bed, and then putting the steel into a heat preservation pit, wherein the temperature of the steel entering the pit is more than or equal to 450 ℃; the heat preservation time of the steel entering the pit is more than or equal to 48 hours.
Comparative example 1
This comparative example relates to a conventional steel type production method.
The production flow comprises the following steps: converter smelting → LF + VD → continuous casting 400mm multiplied by 560mm → pit cold insulation or red conveying → (inspection, cleaning) → large rod wire stepping heating furnace heating → cogging + flat and vertical rolling mill production → steel pit cold insulation → peeling → cleaning, inspection. The main process flow and the production process are shown in the following table 22:
TABLE 3
Example 2
In the embodiment 2, three groups of C38+ N steel are prepared from one type of steel by adopting the production method for smelting the steel variety by modular classification of different slag system components in the embodiment 1, and experiments 1-3 are obtained; three sets of control C38+ N steels were prepared using the manufacturing method of comparative example 1 to obtain control test pieces, and comparative examples 1-3, as shown in table 4.
And (3) carrying out characteristic detection on the six test pieces of the experiments 1-3 and the comparisons 1-3 and the six control test pieces of the experiments 1-3 and the comparisons 1-3, wherein specific detection items comprise: gas content, non-metallic inclusions, austenite grain grade of rolled material, mechanical property and smelting efficiency. From the comparison condition, after modularization, sulfide inclusion is dispersed and distributed in the steel, and oxide inclusion single particles are dispersed and distributed; before modularization, sulfide inclusions in steel are clustered, and oxide inclusions are clustered in a granular mode. Therefore, the steel prepared by the modularized smelting method has excellent performance and can meet the use requirements of users; the specific detection results are as follows:
(1) gas content detection
The gas content testing method comprises the following steps: respectively taking C38+ N molten steel smelted in normal smelting furnaces with different furnace numbers, and detecting the contents of oxygen and nitrogen in the molten steel.
The specific detection data are shown in table 5 (gas content in module-class prepared C38+ N molten steel):
TABLE 5
The average oxygen content of the C38+ N steel prepared in example 1 is 5.7ppm, the average oxygen content of comparative example 1 is 8.9ppm, oxide inclusions in the steel are reduced after the oxygen content is reduced, and the advantages of the modular smelting technology are obvious.
(2) Non-metallic inclusion detection
The non-metallic inclusion test method comprises the following steps: and respectively taking C38+ N molten steel smelted in normal smelting furnaces with different furnace numbers, and detecting A, B, C, D types of non-metallic inclusions in the molten steel.
The specific test data are shown in table 6 (test data of nonmetallic inclusions in C38+ N molten steel of the present invention):
TABLE 6
The data show that the A-type and B-type inclusions in the steel produced by the method are averagely reduced by 0.5 grade, the C-type inclusions are reduced by 1.0 grade, and the occurrence probability of the D-type inclusions is reduced by 70 percent.
(3) Rolled material austenite grain grade detection
The austenite grain grade of the rolled C38+ N steel is tested, and the detection shows that the austenite structure grain of the high-quality C38+ N steel rolled material obtained by the invention is uniform: the austenite grains are stabilized at 7.0 grade, the austenite grains of the cross section are extremely poor at 0 grade, and the specific detection data is shown in table 7 (the detection data of the austenite grains of the C38+ N steel rolling material of the invention).
TABLE 7
(4) Mechanical property detection
The mechanical properties of the C38+ N steel are tested, and the detection shows that the elongation after fracture A of the C38+ N steel is obtained by the invention: 11-12.5%, face shrinkage ratio Z: specific detection data of 10-14%, yield ratio of 0.57-0.58, impact energy AKV of more than or equal to 60J, tensile strength Rm and stability of about 730MPa are shown in Table 8 (mechanical properties of C38+ N steel).
TABLE 8
| Categories | Test batch number | Number plate | Test directions | Tensile strength value, Mpa | Elongation after fracture% | Reduction of area achievement% | Yield ratio |
| Comparative example 1 | B61910220008 | C38+N | Transverse direction | 714 | 6.5 | 9 | 0.59 |
| Comparative example 1 | B61910220008 | C38+N | Transverse direction | 698 | 6.5 | 12 | 0.61 |
| Comparative example 2 | B61910190001 | C38+N | Transverse direction | 769 | 11.5 | 16 | 0.63 |
| Comparative example 2 | B61910190001 | C38+N | Transverse direction | 756 | 13.5 | 20 | 0.6 |
| Comparison 3 | B61910190006 | C38+N | Transverse direction | 792 | 12.5 | 13 | 0.61 |
| Comparison 3 | B61910190006 | C38+N | Transverse direction | 788 | 13 | 13 | 0.6 |
| Experiment 1 | DB6202084401 | C38+N | Transverse direction | 725 | 11.5 | 11 | 0.57 |
| Experiment 1 | DB6202084401 | C38+N | Transverse direction | 739 | 12 | 13 | 0.58 |
| Experiment 2 | DB6202084601 | C38+N | Transverse direction | 733 | 11.5 | 10 | 0.57 |
| Experiment 2 | DB6202084601 | C38+N | Transverse direction | 734 | 11 | 10 | 0.58 |
| Experiment 3 | DB6202084801 | C38+N | Transverse direction | 730 | 12.5 | 10 | 0.58 |
| Experiment 3 | DB6202084801 | C38+N | Transverse direction | 731 | 11.5 | 14 | 0.57 |
(5) Efficiency of smelting
By carrying out comparative analysis on the slagging time and the smelting time of the converter and the LF refining furnace, the efficiency of producing C38+ N steel in a modularized manner is obviously and greatly improved, the time is saved, and the benefit is created. The smelting efficiency is shown in Table 9 (the smelting efficiency of a type of C38+ N steel).
TABLE 9
By observing the nonmetallic inclusion structure of the modularized C38+ N steel, the sulfide of the modularized C38+ N steel is dispersed and uniformly distributed, so that the transverse performance of the C38+ N steel is stable, and the magnetic mark objection proposed by a user is reduced. Therefore, the C38+ N steel prepared by the method is used for the automobile crankshaft, and the performance requirements of users on the C38+ N steel can be completely met due to stable material performance and obvious improvement effect. More importantly, the method of adopting the modularized converter and the LF refining slag system greatly improves the smelting efficiency, reduces the labor intensity of steelmaking workers, and improves the production efficiency and the economic benefit. Table 10 shows the efficiency improvement comparison after the modularization.
Watch 10
| Categories | Number of steel furnaces per day | Number of continuous casting furnaces | Monthly output, ton | Percent per month rejection rate% |
| Before modularization | 37 | 5 | 49331 | 1.81 |
| After modularization | 48 | 10 | 76376 | 0.45 |
Compared with the prior art, the invention has the following advantages: the invention relates to a production method for smelting various steels by modularly classifying different slag system components, which modularly classifies hundreds of steels according to the characteristics of various steels and introduces eight types of modularization standards: sulfur-containing non-quenched and tempered steel, high-aluminum steel, low-silicon sulfur-controlled and aluminum-controlled steel, high-carbon bearing steel, high-carbon steel, medium-carbon alloy structural steel, low-carbon alloy structural steel, gear steel and carburized bearing steel. The invention relates to a production method for smelting variety steel by modularizing and classifying different slag system components, which adopts the technology of combining converter modularized slag system, smelting low P control technology and LF refining modularized slag system to smelt high-cleanliness variety steel. The production method for smelting the variety steel by modularly classifying different slag system components adopts low P control, so that the cleanliness of molten steel is greatly improved, the average level of A-type and B-type inclusions is reduced by 0.5, the level of C-type inclusions is reduced by 1.0, and the occurrence probability of D-type inclusions is reduced by 70%. The production method for smelting the variety steel by modularly classifying different slag system components not only effectively improves the surface quality of steel after cogging, continuous rolling and scalping; but also effectively solves the quality problem of overproof inclusions, so that the rejection rate is reduced, and the economic benefit of enterprises is effectively improved. The invention relates to a production method for smelting variety steel by modularly classifying different slag system components, which enables smelting casting times of enterprises to be improved from the prior five-continuous casting and six-continuous casting steel types to ten-continuous casting, even to twelve-continuous casting, improves the production efficiency by 38.56 percent, and improves the yield from the prior 4.93 ten thousand tons to 7.64 ten thousand tons per month.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without affecting the spirit of the invention.
Claims (7)
1. The production method for smelting variety steel by modular classification of different slag system components is characterized by comprising the following specific operation steps:
1, dividing steel modules into eight categories according to various steel characteristics, pretreating KR molten iron, and carrying out converter primary smelting;
step 2, tapping from a converter: adding deoxidized aluminum into a ladle for pre-deoxidation in steel flow, then adding premelting slag and a deoxidizer to reduce the total oxygen content of molten steel, and adding lime when tapping 1/3;
step 3, LF refining: controlling the time from the end of the primary smelting and tapping of the converter to the time of entering an LF refining station within 12 min; before refining, the argon flow is 150 plus 200NL/min, the stirring is carried out for 2-3min, and the argon flow is controlled to be 100 plus 150NL/min in the LF refining process; feeding the materials into a tank, supplying power and heating the materials, adding alloy and lime ash into the tank in 2-3 batches, and adding aluminum particles and silicon carbide into the tank; during the period, a steel sample and a slag sample are taken for analyzing chemical components, and before LF refining is finished, when the steel sample and the slag system chemical components reach the control target requirement and the temperature is controlled at 1600-;
step 4, VD vacuum degassing: the control conditions of the vacuum degassing process are that the argon flow is 50-100NL/min in rough vacuum, and the argon flow is 100-150NL/min in extreme vacuum; the steam pressure is more than or equal to 0.90Mpa, the steam temperature is more than or equal to 175 ℃, and the water temperature is less than or equal to 30 ℃; the extreme vacuum retention time is more than or equal to 20 minutes; h is less than or equal to 1.5ppm when measured by a Herrie online hydrogen determination instrument;
wherein, the rough vacuum means the vacuum degree is more than 200 torr, and the extreme vacuum means the vacuum degree is less than or equal to 0.5 torr;
and 5, continuous casting: step 4, after vacuum degassing, driving the ladle into a refining furnace to be heated and soft-blown, and when the temperature of molten steel meets the continuous casting temperature, hanging the ladle into a continuous casting machine to continuously cast a continuous casting blank to obtain a semi-finished casting blank with O, N content and endogenous inclusions meeting the standard requirement of high-quality steel; the standard requirements of the high-quality steel are as follows: o is less than or equal to 10 ppm;
and 6, continuously rolling to obtain the corresponding variety of steel.
2. The production method for smelting steel of different slag system component modularized classification according to claim 1 is characterized in that the step 1 of modularly classifying the steel comprises the following steps:
one type is as follows: sulfur-containing non-quenched and tempered steel: comprises C38+ N, C70S6BY, C38N2, 49MnVS3 and 36MnVS4 series steel grades;
the second type is as follows: high-aluminum steel: 38CrMo Al and 09Cr2AlMoRe series steel grades;
three types are as follows: low silicon sulfur and aluminum control steel: MnCr5 series steel grade;
four types: high carbon bearing steel: GCr15, GCr18Mo series steel grade;
and five types are as follows: high carbon steel: 605M36, 55SiMoMo, 80B, T8, T10 series steel grade;
six types: medium carbon alloy structural steel: 42CrMo, 40Mn2, 40Cr series steel grade;
seven types: low-carbon alloy structural steel: 15Ni4Mo, 18CrNiMo7-6, 19CrNi5, 20CrMnTiH, 20CrNiMo and gear steel series steel grades;
eight types: carburizing bearing steel: g20CrNi2Mo and G20Cr2Ni4 series steel grades.
3. The production method of the modular classified smelting grades of steel with different slag system components according to claim 2, wherein the contents of the added materials in the converter tapping process in the step 2 are as follows:
sulfur-containing non-quenched and tempered steel: 6.5-7.0 g of lime per ton of steel, 1.2-1.5 g of deoxidizer per ton of steel, 2.6-3.0 g of premelting slag per ton of steel and 0.6-0.8 g of deoxidized aluminum per ton of steel;
high aluminum steel (medium carbon): 8.5-10 kg of lime per ton of steel, 1.5-1.8 kg of deoxidizing agent per ton of steel, 3.0-3.5 kg of premelting slag per ton of steel, and 2.5-2.8 kg of deoxidized aluminum per ton of steel;
high aluminum steel (low carbon): 10-12 kg of lime per ton of steel, 1.5-1.8 kg of deoxidizer per ton of steel, 2.8-3.2 kg of premelting slag per ton of steel, 1.0-1.2 kg of fluorite per ton of steel and 3.4-3.6 kg of deoxidized aluminum per ton of steel;
low silicon sulfur and aluminum control steel: 8-10 kg of lime per ton of steel, 1.3-1.6 kg of deoxidizer per ton of steel, 3.7-4.0 kg of premelting slag per ton of steel and 1.6-2.0 kg of deoxidized aluminum per ton of steel;
high carbon bearing steel: lime 7-8 kg/ton steel, pre-melted slag 5-7 kg/ton steel and deoxidized aluminum 1.1-1.3 kg/ton steel;
high carbon steel: 6-8 kg of lime per ton of steel, 1.4-1.7 kg of deoxidizer per ton of steel, 2.6-2.9 kg of premelting slag per ton of steel and 0.8-1.0 kg of deoxidized aluminum per ton of steel;
medium carbon alloy structural steel: lime 7-10 kg/ton steel, deoxidizer 1.3-1.5 kg/ton steel, premelting slag 4.0-4.3 kg/ton steel and deoxidized aluminum 1.0-1.3 kg/ton steel;
low-carbon alloy structural steel: 8-10 kg of lime per ton of steel, 1.4-1.6 kg of deoxidizer per ton of steel, 3.5-3.8 kg of premelting slag per ton of steel and 1.3-1.6 kg of deoxidized aluminum per ton of steel;
carburizing bearing steel: lime 7-9 kg/ton steel, premelting slag 5.5-5.8 kg/ton steel and deoxidized aluminum 1.2-1.5 kg/ton steel.
4. The production method of the modular classified smelting grades of steel with different slag system components according to claim 2, wherein the types and contents of the added ingredients in the refining process in the step 3 are as follows:
sulfur-containing non-quenched and tempered steel: 0-1.2 kg of lime and 0.5-0.8 kg of silicon carbide per ton of steel; the slag system target is controlled as follows according to the mass percentage: FeO: not more than 0.85 percent and SiO 2 12～18％，CaO50～55％，MgO3～7％，Al 2 O 3 15-20%, wherein the sum of the mass percentages is 100%; wherein the basic oxide CaO and the acidic oxide SiO are 2 The ratio R of the mass percentages of the components is 3-5;
high aluminum steel (medium carbon): lime 1.0-2.0 kg/ton steel, silicon carbide 0.4-0.6 kg/ton steel, aluminum particles 0.15-0.20 kg/ton steel; the slag system target is controlled as follows according to the mass percentage: FeO: not more than 0.60 percent and SiO 2 ≤8％，CaO 50～55％，MgO3～7％，Al 2 O 3 25-35%, wherein the sum of the mass percentages is 100%; wherein the basic oxide CaO and the acidic oxide SiO are 2 The ratio R of the mass percentages of the components is 6-9;
high aluminum steel (low carbon): lime 1.0-1.4 kg/ton steel, silicon carbide 0.4 kg/ton steel and aluminum particles 0.20-0.30 kg/ton steel; the slag system target is controlled as follows according to the mass percentage: FeO: not more than 0.60 percent and SiO 2 ≤8％，CaO 50～55％，MgO3～7％，Al 2 O 3 28-35%, wherein the sum of the mass percentages is 100%; wherein the basic oxide CaO and the acidic oxide SiO are 2 The ratio R of the mass percentages of the components is 7-10;
low silicon sulfur and aluminum control steel: 0-1.5 kg of lime per ton of steel, 0.3-0.5 kg of silicon carbide per ton of steel and 0.30-0.50 kg of aluminum particles per ton of steel; the slag system target is controlled as follows according to the mass percentage: FeO: not more than 0.80 percent and SiO 2 ≤8％，CaO 50～55％，MgO 3～7％，Al 2 O 3 20-28%, wherein the sum of the mass percentages is 100%; wherein the basic oxide CaO and the acidic oxide SiO are 2 The ratio R of the mass percentages of the components is 5-8;
high carbon bearing steel: 0-1.0 kg of lime per ton of steel, 0.7-1.0 kg of silicon carbide per ton of steel and 0.15-0.20 kg of aluminum particles per ton of steel; the slag system target is controlled as follows according to the mass percentage: FeO: not more than 0.60 percent and SiO 2 6～10％，CaO 55～60％，MgO 3～7％，Al 2 O 3 25-28%, wherein the sum of the mass percentages is 100%; wherein the basic oxide CaO and the acidic oxide SiO are 2 The ratio R of the mass percentages of the components is 6-8;
high carbon steel: 0 to 0.8kg of lime per ton of steel, 0.8 to 1.0kg of silicon carbide per ton of steel, and aluminum0.12-0.16 kg of grains per ton of steel; the slag system target is controlled as follows according to the mass percentage: FeO: not more than 0.80 percent and SiO 2 8～10％，CaO 55～60％，MgO 3～7％，Al 2 O 3 20-28%, wherein the sum of the mass percentages is 100%; wherein the basic oxide CaO and the acidic oxide SiO are 2 The ratio R of the mass percentages of the components is 6-8;
medium carbon alloy structural steel: 0-1.5 kg of lime per ton of steel, 1.0-1.5 kg of silicon carbide per ton of steel and 0-1.0 kg of pre-melted slag per ton of steel; the slag system target is controlled as follows according to the mass percentage: FeO: less than or equal to 0.80 percent and SiO 2 8～12％，CaO53～58％，MgO 3～7％，Al 2 O 3 22-28%, wherein the sum of the mass percentages is 100%; wherein the basic oxide CaO and the acidic oxide SiO are 2 The ratio R of the mass percentages of the components is 5-7;
low-carbon alloy structural steel: 0-1.2 kg of lime and 1.0-1.5 kg of silicon carbide per ton of steel; the slag system target is controlled as follows according to the mass percentage: FeO: not more than 0.80 percent and SiO 2 8～12％，CaO 50～60％，MgO 3～7％，Al 2 O 3 20-28%, wherein the sum of the mass percentages is 100%; wherein the basic oxide CaO and the acidic oxide SiO are 2 The ratio R of the mass percentages of the components is 5-8;
carburizing bearing steel: 0-1.4 kg of lime per ton of steel, 0.8-1.2 kg of silicon carbide per ton of steel and 0.15-0.25 kg of aluminum particles per ton of steel; the slag system target is controlled as follows according to the mass percentage: FeO: not more than 0.80 percent and SiO 2 7～10％，CaO50～60％，MgO 3～7％，Al 2 O 3 22-28%, wherein the sum of the mass percentages is 100%; wherein the basic oxide CaO and the acidic oxide SiO are 2 The ratio R of the mass percentages of (A) to (B) is 6-8.
5. The production method for smelting the grade steel by modular classification of different slag system components according to claim 1, wherein the continuous casting and pouring in the step 5 are specifically as follows: controlling the pulling speed of the crystallizer: when the degree of superheat is 11-20 ℃, the pulling speed is 0.38 m/min; when the superheat degree is 20-29 ℃, the pulling speed is 0.36 m/min; when the degree of superheat is 30-40 ℃, the pulling speed is 0.34 m/min; electromagnetic stirring: head end 450A/1.5Hz, tail end 660A/7.5 Hz; the baking time of the tundish is more than 5 hours; before casting, the time for purging the tundish with argon is more than or equal to 8 minutes, and the flow of the argon is 10 +/-5 NL/min; immersion type water gap insertion depth: 160-190 mm; the casting furnace uses stainless steel covering slag.
6. The production method for smelting grades of steel by modular classification of different slag system components according to claim 1, wherein the continuous rolling in step 6 is specifically as follows:
the first step is as follows: heating the blank in a heating furnace, wherein the temperature of a heating section is 1000-1280 ℃, and the temperature of a soaking section is 1200-1270 ℃; the high-temperature diffusion time is more than or equal to 3.5 h; the total heating time is 8-12h, and the tapping speed is less than or equal to 15 pieces/h;
and a second step of rolling: firstly, a BD rolling mill is adopted: the initial rolling temperature is more than or equal to 1050 ℃, and the continuous rolling finishing temperature is more than or equal to 1000 ℃; and then adopting a horizontal and vertical rolling mill: the initial rolling temperature is 920 +/-10 ℃; the finishing temperature is 900 +/-20 ℃; cooling the steel by a rack type cooling bed and then putting the steel into a heat preservation pit, wherein the temperature of the steel entering the pit is more than or equal to 450 ℃; the heat preservation time of the steel entering the pit is more than or equal to 48 hours.
7. The method for producing the different slag system component modular classification smelting grades of steel according to claim 1, characterized in that the dephosphorization control of the rolling process water: and (3) water is sprayed twice to remove phosphorus, and the water phosphorus removal pressure is 20-25 MPa.
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