CN111485068A - A kind of smelting method of high surface quality IF steel - Google Patents
A kind of smelting method of high surface quality IF steel Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 226
- 239000010959 steel Substances 0.000 title claims abstract description 226
- 238000000034 method Methods 0.000 title claims abstract description 109
- 238000003723 Smelting Methods 0.000 title claims abstract description 58
- 239000002893 slag Substances 0.000 claims abstract description 110
- 230000008569 process Effects 0.000 claims abstract description 57
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 46
- 239000001301 oxygen Substances 0.000 claims abstract description 43
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 41
- 238000011282 treatment Methods 0.000 claims abstract description 37
- 238000010438 heat treatment Methods 0.000 claims abstract description 34
- 238000009749 continuous casting Methods 0.000 claims abstract description 25
- 239000000463 material Substances 0.000 claims abstract description 8
- 238000001179 sorption measurement Methods 0.000 claims abstract description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 54
- 229910052742 iron Inorganic materials 0.000 claims description 27
- 229910052720 vanadium Inorganic materials 0.000 claims description 24
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 claims description 24
- 238000010079 rubber tapping Methods 0.000 claims description 21
- 238000005261 decarburization Methods 0.000 claims description 20
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 18
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 18
- 239000004571 lime Substances 0.000 claims description 18
- 230000000694 effects Effects 0.000 claims description 17
- 238000000605 extraction Methods 0.000 claims description 13
- 229910052757 nitrogen Inorganic materials 0.000 claims description 13
- 229910052799 carbon Inorganic materials 0.000 claims description 11
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 10
- 238000007664 blowing Methods 0.000 claims description 10
- 238000006477 desulfuration reaction Methods 0.000 claims description 9
- 230000023556 desulfurization Effects 0.000 claims description 9
- 229910052717 sulfur Inorganic materials 0.000 claims description 8
- 238000005275 alloying Methods 0.000 claims description 6
- 229910052786 argon Inorganic materials 0.000 claims description 5
- 239000003795 chemical substances by application Substances 0.000 claims description 5
- 229910052698 phosphorus Inorganic materials 0.000 claims description 5
- 238000005406 washing Methods 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 4
- 229910052719 titanium Inorganic materials 0.000 claims description 3
- 230000003750 conditioning effect Effects 0.000 claims 3
- 230000003647 oxidation Effects 0.000 abstract description 21
- 238000007254 oxidation reaction Methods 0.000 abstract description 21
- 238000004519 manufacturing process Methods 0.000 abstract description 15
- 238000012546 transfer Methods 0.000 abstract description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 20
- 239000003607 modifier Substances 0.000 description 13
- 238000010521 absorption reaction Methods 0.000 description 9
- 230000007547 defect Effects 0.000 description 9
- 239000012535 impurity Substances 0.000 description 8
- 239000004088 foaming agent Substances 0.000 description 6
- 238000007670 refining Methods 0.000 description 6
- 229910052782 aluminium Inorganic materials 0.000 description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 5
- 238000009529 body temperature measurement Methods 0.000 description 5
- 238000012545 processing Methods 0.000 description 5
- 238000009628 steelmaking Methods 0.000 description 5
- 230000001276 controlling effect Effects 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- 230000001105 regulatory effect Effects 0.000 description 4
- GFNGCDBZVSLSFT-UHFFFAOYSA-N titanium vanadium Chemical compound [Ti].[V] GFNGCDBZVSLSFT-UHFFFAOYSA-N 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 230000000903 blocking effect Effects 0.000 description 3
- 125000004122 cyclic group Chemical group 0.000 description 3
- 238000005485 electric heating Methods 0.000 description 3
- 238000007654 immersion Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000002035 prolonged effect Effects 0.000 description 3
- 230000001737 promoting effect Effects 0.000 description 3
- 239000011593 sulfur Substances 0.000 description 3
- 239000010936 titanium Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 206010039897 Sedation Diseases 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 230000009194 climbing Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 230000036280 sedation Effects 0.000 description 2
- 241000894007 species Species 0.000 description 2
- 241000282421 Canidae Species 0.000 description 1
- XHCLAFWTIXFWPH-UHFFFAOYSA-N [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] XHCLAFWTIXFWPH-UHFFFAOYSA-N 0.000 description 1
- MRHSJWPXCLEHNI-UHFFFAOYSA-N [Ti].[V].[Fe] Chemical compound [Ti].[V].[Fe] MRHSJWPXCLEHNI-UHFFFAOYSA-N 0.000 description 1
- 230000003679 aging effect Effects 0.000 description 1
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical compound [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 235000011116 calcium hydroxide Nutrition 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000010891 electric arc Methods 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- IXQWNVPHFNLUGD-UHFFFAOYSA-N iron titanium Chemical compound [Ti].[Fe] IXQWNVPHFNLUGD-UHFFFAOYSA-N 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
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- 229910001935 vanadium oxide Inorganic materials 0.000 description 1
Classifications
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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
-
- 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
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
The smelting method of the IF steel with high surface quality adopts a manufacturing process of BOF-L F-RH-CC, solves the problem of insufficient semi-steel heat source by heating and raising the temperature of molten steel through a L F furnace, reduces the addition of slag materials except necessary slag materials required by submerged arc and adsorption inclusion in the L F treatment heating process after the molten steel is treated and tapped and before RH treatment deoxidation, avoids the transfer of oxygen in the molten steel to slag in the process, and transfers oxygen in the slag to steel in the molten steel carrying and continuous casting pouring processes after the molten steel is decarburized and deoxidized to cause the secondary oxidation of the molten steel and produce endogenous inclusion to pollute the molten steel.
Description
Technical Field
The invention belongs to the technical field of smelting, and particularly relates to a smelting method of IF steel with high surface quality.
Background
IF steel (Interstitial Free Stee1), also known as Interstitial Free steel, is known as third generation extra deep drawing steel because of its excellent deep drawing properties, high plastic strain ratio, high elongation, high hardening index, low yield ratio, and excellent non-aging properties. IF steel is mainly used for inner plates and outer plates of automobiles in automobiles, and in recent years, automobile manufacturing enterprises have higher quality requirements on steel plates for automobiles, and IF steel used as automobile appearance parts has higher surface quality requirements on steel coils. Inclusion defects have always been the major defect causing surface quality problems in IF steels, typically accounting for over 60% of surface quality defects in IF steels. 05, each steel coil is required to have no inclusion defects with the length being more than 100mm, the width being more than 1mm and the number being more than 3 or no inclusion defects with the length being more than 50mm, the width being more than 1mm and the number being more than 10, and the highest grade of the 05 surface is even required to have no inclusion defects.
In 2017, in journal of vanadium and titanium iron (Vol. 38, 156-160 nd 2 nd page of IF steel cold-rolled plate surface strip defect cause and control method, Dengjian Jun et al), a method for controlling inclusion defects of Handy steel in molten iron smelting of IF steel strip is reported, and in journal of steelmaking, in 2019, in 12 th month (Vol. 35, 55-56 th page 6 th page of first Jingtang IF steel production process development practice, Anchao et al), a control method for inclusion defects of first Steel Jingtang adopting molten iron smelting IF steel is also reported. All the reports adopt a control method for smelting IF steel inclusions by molten iron. For semisteel (a product of vanadium-containing molten iron after vanadium slag extraction), after vanadium extraction, the carbon content and the temperature of the semisteel are both lost to a certain extent, and in addition, the vanadium-titanium-iron ore semisteel with high sulfur content (average content is more than or equal to 0.080 percent) needs long-time pre-desulfurization treatment, if the manufacturing process of BOF-RH-CC is still adopted, the ratio of converter end point deep blowing is increased, so that the oxygen activity in molten steel and slag is increased, and the Al activity is increased2O3Chinese scientific and technological project innovation achievement appraisal suggestion database (known halftone) reports "steel climbing" a method for smelting low-oxygen low-carbon IF steel with vanadium-titanium molten iron (2016, bright and the like) ", the low-carbon low-oxygen IF steel is produced by adopting a manufacturing process of" BOF-L F-RH-CC ", the problem of insufficient heat source of the IF steel smelted by semisteel is better solved by utilizing the heating function of a L F furnace, the problem of nitrogen absorption in the heating process of a L F procedure is solved, the component control can reach the level of smelting IF steel by molten iron in the same industry, but the process is applied to the present, the problem of impurity control cannot be well solved, the impurity control level has a certain difference with the IF steel smelted by molten iron in the same industry, the China halftone patent database (known halftone) discloses a method for smelting IF steel by semisteel with low cost, Cheng Luo et al, the patent No. 5/38922, even IF steel used in the same industry, No. 2020, 1 month 17, the China halftone patent database (known halftone) discloses a" steel climbing "method for smelting IF steel by semisteel with low cost, Cheng No. 22C 22/48325C, No. 22/8622C, No. 3C, 3625C, No. 3/8622C38/04, respectively; C22C 38/14; C22C 38/06; C22C38/12), the method uses the thought of smelting IF steel by molten iron, adopts a BOF-RH-CC manufacturing process, aims to solve the problem of insufficient heat source of semi-steel smelting IF steel by increasing the tapping temperature of a converter and improving the heat preservation of the molten steel process, has not been verified in batches at present, can foresee the problem of insufficient heat source when the molten iron resource is insufficient or the production is unstable, and under the condition, the temperature is increased by deep blowing of the converter or the RH aluminum heating (Al is generated while the oxidation heat release of aluminum is carried out) is adopted (the Al is generated while the oxidation heat release of aluminum2O3Inclusions) to increase the temperature all present the problem of increasing the risk of inclusions, while increasing the tapping temperature also may cause a reduction in the life of the lining of the converter. Therefore, a technical breakthrough is still needed in the aspect of smelting high-surface-quality IF steel from semisteel after vanadium extraction treatment of high-sulfur vanadium-titanium molten iron.
In conclusion, the technical personnel in the field need to solve the problem of how to provide an IF steel smelting method which can improve the inclusion control level and reduce the production cost.
Disclosure of Invention
The invention aims to provide a smelting method of IF steel with high surface quality, which can improve the inclusion control level and reduce the production cost.
In order to solve the technical problem, the invention provides a smelting method of IF steel with high surface quality, which comprises the following steps:
1) BOF treatment: smelting molten steel in a converter, and by oxygen blowing decarburization, molten steel heating and slagging dephosphorization, enabling the content of C in the molten steel to be less than or equal to 0.05%, the content of P to be less than or equal to 0.020%, the content of S to be less than or equal to 0.020%, controlling the oxygen activity of molten steel at the end point of the converter to be 500-800 ppm, and controlling the tapping temperature to be 1660 +/-20 ℃, wherein lime is not added for slag washing and pre-deoxidation is not carried out in the tapping process;
2) l F treatment, namely directly conveying the slag from a small platform behind the furnace to a L F furnace for heating, and adding necessary slag required by submerged arc and adsorption inclusion in the heating process;
3) RH treatment: sequentially carrying out decarburization, denitrification, deoxidation, alloying and ladle slag regulation treatment on the molten steel at the RH station in sequence;
4) and (3) CC treatment: and (5) continuous casting and pouring.
Preferably, in the smelting method, in the step 1), the sliding plate is used for blocking slag during the tapping process of the converter, and lime is not added into a ladle.
Preferably, in the smelting method, in the step 2), the small platform behind the furnace does not perform slag regulation treatment on ladle slag, and argon blowing, temperature measurement and oxygen fixing are not performed.
Preferably, in the smelting method, in the step 2), the L F furnace is transported to the RH station in the step 3) after the heating compensation temperature reaches the target temperature of 1635 +/-15 ℃.
Preferably, in the smelting method, the total amount of the slag charge added in the step 2) is less than or equal to 4.0kg/t steel.
Preferably, in the smelting method, in the step 3), the outbound component is controlled to have an Als content of the target component middle limit of + 0.0030%, a C content of 0.0040% or less, a Mn content of 0.05-0.30%, a P content of 0.020% or less, a S content of 0.020% or less, a N content of 0.0040% or less, a Ti content of 0.02-0.08%, and an O content of 0.0020% or less.
Preferably, in the above smelting method, in the step 3), the outlet temperature is controlled to be 1595 ± 15 ℃.
Preferably, in the smelting method, in the step 3), 2.5-3.5 kg/t of slag modifier is added to modify the ladle slag, and after 15-40 minutes of sedation, continuous casting is carried out.
Preferably, in the above smelting method, in the step 1), the molten iron is subjected to vanadium pre-extraction and pre-desulfurization before the molten steel is smelted in the converter.
Preferably, in the smelting method, the vanadium pre-extraction process is as follows: and extracting vanadium from the molten iron to obtain semisteel, wherein the content of C in the semisteel is controlled to be 3.50 +/-0.30%, and the temperature is 1350 +/-30 ℃.
The smelting method of the IF steel with high surface quality adopts a manufacturing process of BOF-L F-RH-CC, solves the problem of insufficient semi-steel heat source by heating and raising the temperature of molten steel through a L F furnace, reduces the addition of slag materials except necessary slag materials required by submerged arc and adsorption inclusion in the L F treatment heating process after the molten steel is treated and tapped and before RH treatment deoxidation, avoids the transfer of oxygen in the molten steel to slag in the process, and transfers oxygen in the slag to steel in the molten steel carrying and continuous casting pouring processes after the molten steel is decarburized and deoxidized to cause the secondary oxidation of the molten steel and produce endogenous inclusion to pollute the molten steel.
Detailed Description
The core of the invention is to provide a smelting method of IF steel with high surface quality, which can improve the inclusion control level and reduce the production cost.
In order to make those skilled in the art better understand the technical solutions provided by the present invention, the present invention will be further described in detail with reference to specific embodiments.
The invention provides a smelting method of IF steel with high surface quality, which adopts a BOF-L F-RH-CC process and specifically comprises the following steps:
1) BOF treatment: smelting molten steel in a converter, and controlling the content of C in the molten steel to be less than or equal to 0.05%, the content of P to be less than or equal to 0.020%, the content of S to be less than or equal to 0.020%, the oxygen activity of the molten steel at the end point of the converter to be 500-800 ppm and the tapping temperature of the converter to be 1660 +/-20 ℃ by blowing oxygen for decarburization, heating the molten steel and slagging and dephosphorizing. Wherein, lime is not added for slag washing and pre-deoxidation are not carried out in the tapping process; before decarburization and deoxidation in RH treatment, because the oxygen activity of the molten steel is at a high oxygen level of 500-800 ppm, the addition of slag is reduced, and the possibility that oxygen absorption and nitrogen absorption pollute the molten steel and influence the control of the nitrogen content of the molten steel is avoided.
2) L F, directly conveying the slag from a small platform behind the furnace to a L F furnace for heating, and adding necessary slag required by submerged arc and adsorption inclusion in the heating process, wherein the slag mainly comprises a slag foaming agent and lime.
3) RH treatment: sequentially carrying out decarburization, denitrification, deoxidation, alloying and ladle slag regulation treatment on the molten steel at an RH station in sequence;
4) and (3) CC treatment: and (5) continuous casting and pouring.
It is to be noted that the main purpose of adding lime slag washing in the steel ladle in the converter tapping process is as follows: 1) promoting the polymerization of the deoxidation product, thereby promoting the floating of the inclusion; 2) certain P is removed by utilizing the dynamic condition of the tapping process; 3) and covering and insulating molten steel. The IF steel does not deoxidize in the converter tapping process, and does not generate a deoxidized product, so that the task of promoting the deoxidized product to polymerize and float does not exist; secondly, the content of P in the vanadium-titanium molten iron is low, and the control of P is not a main contradiction for IF steel; thirdly, IF steel is undeoxidized steel, the covering effect of molten steel is slightly poor, and the problem of nitrogen absorption is not worried about, theoretical research shows that the molten steel is easier to absorb nitrogen in a deoxidized state, the nitrogen absorption amount is extremely low in the undeoxidized state, and the temperature loss can be compensated by accelerating the transfer speed of the molten steel (small platform does not measure temperature and fix oxygen). Therefore, the technical analysis that lime is not added into a steel ladle in the process of converter tapping is considered to be feasible, and the aim of reducing the addition of the lime is to reduce the total slag amount in the steel ladle before RH treatment decarburization and deoxidation, further reduce the oxygen capacity of slag and avoid the transmission of oxygen in steel slag after RH treatment decarburization and deoxidation to steel so as to cause secondary oxidation of molten steel.
The smelting method of the IF steel with high surface quality adopts a manufacturing process of BOF-L F-RH-CC, solves the problem of insufficient semi-steel heat source by heating molten steel through a L F furnace, reduces the addition of slag materials except necessary slag materials required by submerged arc and adsorption inclusion in the L F treatment heating process after the molten steel is treated and tapped and before RH treatment deoxidation, avoids the transfer of oxygen in the molten steel to slag in the process, and transfers oxygen in the slag to the steel in the molten steel carrying and continuous casting pouring processes after the molten steel is decarburized and deoxidized, so that secondary oxidation of the molten steel is caused, and the molten steel is polluted by endogenous inclusion.
By adopting the smelting method, the Als loss (an index for representing secondary oxidation and mainly caused by the secondary oxidation of molten steel) from the vacuum station discharge of the IF steel to the continuous casting is averagely 25ppm, the average loss is reduced by 30ppm compared with the prior art, the inclusion generated by the secondary oxidation is greatly reduced, the steel coil inclusion discovery rate is reduced by 10-20% in a same ratio, meanwhile, lime is not added in the tapping process, the temperature and oxygen are not measured on a small platform behind a furnace, a slag regulating agent is not added in an L F furnace, the aluminum wire addition amount can be reduced due to the reduction of the Als loss from the vacuum station discharge to the continuous casting, the water gap is not changed in the continuous casting pouring process, and the like, and the production cost can be averagely reduced by 13.2 yuan/ton steel, so that the inclusion control level can be improved, and the production.
Because the molten steel is pretreated before being smelted by the converter, vanadium is extracted and desulfurization is carried out. The process of pre-extracting vanadium comprises the following steps: extracting vanadium from the molten iron to obtain semisteel, wherein the content of C in the semisteel is controlled to be 3.50 +/-0.30%, and the temperature is 1350 +/-30 ℃.
In a specific embodiment, a sliding plate is used for blocking slag in the converter tapping process to prevent converter slag from entering a steel ladle, and lime is not added into the steel ladle.
In the specific implementation mode of the L F treatment process, the small platform behind the furnace does not carry out slag regulation treatment on ladle slag, and argon blowing, temperature measurement and oxygen fixing are not carried out.
The L F processing station has the main function of compensating temperature for semi-steel smelting IF steel, and simultaneously, the prior art also carries out slag regulation processing on steel slag in the process, so as to reduce the oxidability of slag and prevent secondary oxidation of molten steel, but the molten steel is not deoxidized at the moment, even IF part of oxygen in the steel slag is removed, the oxygen of the molten steel in the subsequent process is transferred to the slag to achieve new balance, but the oxygen for natural decarburization in an RH process is lost, and meanwhile, the slag regulating agent is added to increase the slag amount, so that the oxygen capacity of the slag is correspondingly increased, and the oxygen in the slag is transferred to the molten steel after the alloying of RH deoxidation, but the secondary oxidation of the molten steel is increased, therefore, the L F process can also carry out slag regulation without adding a ladle slag regulating agent.
The molten steel refining task of IF steel is mainly in RH processing procedure, small platform temperature measurement and oxygen determination have no substantive significance, and the consumption of temperature measurement and oxygen determination probes is increased, so that the production cost is increased, and the method can also be cancelled.
In a specific embodiment, since the L F processing procedure aims at adopting the electric heating compensation temperature, in order to improve the heating efficiency, the L F furnace heats the compensation temperature to the target temperature 1635 +/-15 ℃, and then the temperature is conveyed to the RH station in the step 3).
In a specific embodiment, in the L F treatment process, before RH decarburization and deoxidation, the total amount of slag added into a steel ladle is less than or equal to 4.0kg/t steel, specifically 2.0-3.0 kg/t steel lime and 0.5-1.0 kg/t steel slag foaming agent.
In a specific embodiment, after decarburization and deoxidation alloying are completed in an RH treatment station, oxygen balance between slag and metal is broken, oxygen potential in slag is higher than that in molten steel, oxygen in slag is transferred to the molten steel, so that secondary oxidation of the molten steel is caused, a slag modifier is required to be added in time for slag adjustment, and the addition amount is enough and is 2.5-3.5 kg per ton of steel. The RH outbound component is controlled to have the middle limit of Als content target component of + 0.0030%, C content of less than or equal to 0.0040%, Mn content of 0.05-0.30%, P content of less than or equal to 0.020%, S content of less than or equal to 0.020%, N content of less than or equal to 0.0040%, Ti content of 0.02-0.08% and O content of less than or equal to 0.0020%.
In addition, the outbound temperature was controlled at 1595 ± 15 ℃. Adding 2.5-3.5 kg/t slag modifier to carry out slag modification on the ladle slag, and carrying out continuous casting and pouring after 15-40 minutes of sedation.
The method has no difference from other methods in the control requirement of continuous casting pouring, mainly performs protection pouring, liquid level stability control and the like, and is not described again here.
The complete smelting process is 'molten iron pretreatment → converter smelting molten steel → molten steel L F furnace heating → molten steel RH refining → molten steel continuous casting pouring'.
According to the IF steel smelting process, the method specifically comprises the following steps:
pretreating molten iron
The molten iron is vanadium-titanium molten iron, and is mainly characterized by containing a certain vanadium element, high sulfur content and low temperature, so that the vanadium pre-extraction and the pre-desulfurization treatment are carried out firstly. The vanadium pre-extraction is to blow oxygen to molten iron through an oxygen top-blowing converter, vanadium oxide elements enter vanadium slag, carbon elements in the molten iron are oxidized to a certain degree while vanadium is oxidized, the temperature is increased to a certain degree, the molten iron after vanadium extraction is called semi-steel, the C of the semi-steel after vanadium extraction is controlled to be 3.50 +/-0.30 percent, the temperature is 1350 +/-30 ℃, and the semi-steel is further subjected to pre-desulfurization treatment and then added into a steel-making converter for steel making.
(II) preliminary smelting of molten steel-smelting molten steel in converter
The steel-making converter is continuously blown with oxygen, decarburized, heated, slagging and dephosphorized, the molten steel components are controlled to be less than or equal to 0.05 percent of C, less than or equal to 0.020 percent of P, less than or equal to 0.020 percent of S, less than or equal to 500ppm and less than or equal to 800ppm of O at the end point of the converter, then the molten steel is poured into a ladle, a sliding plate is adopted for slag blocking in the converter tapping process to prevent converter slag from entering the ladle, a slaked lime slag washing process is adopted in the converter tapping process, no other slag material is added, deoxidation is not carried out, the operations of argon blowing, temperature measurement, oxygen determination and the like on a small platform behind the converter are cancelled after the steel is tapped, and.
(III) refining of molten Steel
The refining of the molten steel is carried out in two processes, the molten steel is firstly heated by adopting electric arc in the L F process to compensate the deficiency of a semi-steel steelmaking heat source, and then the molten steel is hung to an RH station to be subjected to decarburization, deoxidation, final component control, slag regulation and other treatments.
1. L F furnace heating of molten steel
The electric heating temperature compensation is adopted, after the molten steel is subjected to the electric heating process, argon blowing and heating are immediately started, 0.5-1.0 kg/t of steel slag foaming agent and 2.0-3.0 kg/t of steel active lime are added in the heating process to make slag and bury foxes so as to improve the heating efficiency and prevent nitrogen absorption, on the premise that the Ca/Al of the ladle slag is kept to be 1.4-1.8 so as to ensure the slag inclusion adsorption capacity, slag is added as little as possible, finally, the temperature of the molten steel is controlled to be 1635 +/-15 ℃ at the L F station so as to reduce the slag quantity, and no aluminum-containing slag regulating agent is added in the L F process.
2. RH refining
The main tasks of RH refining are decarburization, deoxidation and final molten steel alloying, and simultaneously, the oxidizability of steel slag is reduced so as to reduce the secondary oxidation of molten steel after the molten steel is deoxidized and alloyed. The molten steel decarburization is carried out by natural decarburization or forced oxygen decarburization according to the oxygen content of the steel, and the molten steel composition is adjusted according to the composition requirement of the target steel grade after deoxidation. Wherein the content of Als is controlled to be +0.0030 percent (about 0.0020 percent lower than that of the prior art) of the target component middle limit so as to compensate Als loss caused by secondary oxidation, and other outbound components are controlled as follows: less than or equal to 0.0040 percent of C, 0.05 to 0.30 percent of Mn, less than or equal to 0.020 percent of P, less than or equal to 0.020 percent of S, less than or equal to 0.0040 percent of N, 0.02 to 0.08 percent of Ti and less than or equal to 0.0020 percent of O. The outlet temperature is controlled to be 1595 +/-15 ℃. 2.5-3.5 kg/t of steel containing an aluminum slag modifier is added before leaving the station, oxygen in part of steel slag is removed, and secondary oxidation of molten steel caused by transfer of oxygen in slag to molten steel is reduced.
(IV) continuous casting
After RH treatment of the molten steel is finished, the molten steel is calmed for 15-40 minutes, and then continuous casting is carried out, the method has no difference from other methods in the control requirement of continuous casting, and mainly has the advantages of protective casting, liquid level stability control and the like, and is not described again here.
The following examples 1-3 prove that the IF steel obtained by the smelting method of the invention has a technical effect obviously superior to that of the original process.
Example 1:
smelting steel species M3A35, wherein after vanadium extraction and desulfurization of molten iron, semi-steel enters a steel converter, the content of C is 3.7 percent, the content of S is 0.0037 percent, the steel converter is blown for 22 minutes and 19 seconds, the end point C content of the converter is 0.04 percent, the O activity is 655ppm, the temperature is 1656 ℃, lime is not added in the tapping process, slag modifier is not added in a small platform behind the converter, the temperature before heating of a L F furnace is 1622 ℃, the heating is 8 minutes, 481kg and 164kg of lime slag foaming agent are added in the heating process, slag modifier is not added in the leaving station, the leaving temperature is 1642 ℃, RH processing is 32 minutes for 56 seconds, the O activity is 306.35ppm after cyclic decarburization, 404kg of slag modifier is added before the leaving station, the leaving station temperature is 1598 ℃, the Als content of the leaving station molten steel is 0.0353 percent, and the Als content of the.
The practical implementation effects of 1, 645kg of slag is added into the steel ladle before the molten steel enters the RH process, the slag amount is reduced by about 2.43kg/t of steel compared with the original process, 2, the Als hardly has oxidation loss in the process from RH station leaving to continuous casting pouring, which indicates that the secondary oxidation of the molten steel is very slight and is obviously superior to the original process, 3, the content of N in the finished molten steel is 17ppm, the requirement of the standard component of the steel is met, the nitrogen absorption risk of the molten steel is not increased due to the reduction of the slag amount, 4, the castability of the molten steel in the process of continuous casting is good, the continuous casting is carried out in the ladle time, 5, L F furnaces do not replace tundish immersion nozzles, the time of the water changing nozzles is prolonged by about 60 minutes compared with the original process, 6, the inclusion rate of 41.17 percent after the steel coil is rolled into the steel coil3O2The existence rate of fine impurities and large impurities is 0 percent, which is superior to the original process level.
Example 2:
smelting a steel species M3A30, wherein after vanadium extraction and desulfurization of molten iron, the semi-steel is fed into a steel converter, the content of C is 3.3 percent, the content of S is 0.0053 percent, the steel converter is blown for 17 minutes and 34 seconds, the content of C at the end point of the converter is 0.03 percent, the activity of O is 713ppm, the temperature is 1640 ℃, lime is not added in the tapping process, no slag modifier is added in a small platform behind the converter, the temperature is 1580 ℃ before heating in a L F furnace, the heating is 17 minutes, 650kg and 116kg of slag foaming agents are added in the heating process, no slag modifier is added in an off-station, the off-station temperature is 1645 ℃, the RH treatment is 28 minutes and 29 seconds, the O activity is 312.18ppm after cyclic decarburization, 600kg of slag modifier is added before the off-station, the off-station temperature is 1583 ℃, the content of Als in molten steel in the.
The practical implementation effects include 1, 766kg of slag is added into a steel ladle before molten steel enters an RH process, the slag amount is reduced by about 1.85kg/t of steel compared with the slag amount in the original process, 2, Als hardly has oxidation loss in the process from RH departure station to continuous casting pouring, which indicates that secondary oxidation of the molten steel is very slight and is obviously superior to the original process, 3, 23ppm of N content of finished molten steel meets the standard component requirement of steel grade, the nitrogen absorption risk of the molten steel is not increased due to reduction of the slag amount, 4, molten steel has good castability in the process of continuous casting pouring, the ladle is continuously poured, 5, L F furnaces do not replace a tundish immersion type water gap, the time of the water changing gap is prolonged by about 50 minutes compared with the original process, 6, 40% of inclusion finding rate after the steel coil is rolled into cold rolling, one steel coil has 1 large inclusion with the length of 1300mm3O2The existence rate of fine impurities and large impurities is 6.67 percent, which is superior to the original process level.
Example 3:
smelting a steel seed M3A30, wherein after vanadium extraction and desulfurization of molten iron, the semi-steel is fed into a steel converter, the content of C is 3.7%, the content of S is 0.0051%, the steel converter is blown for 15 minutes and 10 seconds, the end C content of the converter is 0.05%, the O activity is 575ppm, the temperature is 1657 ℃, lime is not added in the tapping process, no slag modifier is added in a small platform behind the converter, the temperature before heating of a L F furnace is 1647 ℃, the heating is 10 minutes, 383kg of lime and 200kg of slag foaming agent are added in the heating process, no slag modifier is added in an off-station, the off-station temperature is 1622 ℃, RH treatment is 30 minutes and 14 seconds, the O activity is 334.507ppm after cyclic decarburization, 505kg of slag modifier is added before the off-station, the off-station temperature is 1593 ℃, the Als content of the off-station molten steel is 0.0314%, and.
The actual implementation effect is as follows: 1. before the molten steel is subjected to RH process645kg of slag is added into a steel ladle and is reduced by about 2.73kg/t of steel compared with the slag amount of the prior art, 2, RH leaves a station and almost has no oxidation loss in Als in the continuous casting and pouring process, which indicates that the secondary oxidation of molten steel is very slight and is obviously superior to the prior art, 3, the N content of finished molten steel is 24ppm, which meets the standard component requirement of steel grade and does not increase the nitrogen absorption risk of the molten steel because of reducing the slag amount, 4, the molten steel has good castability in the continuous casting and pouring process, the ladle is continuously poured, 5, L F furnaces do not replace a tundish immersion nozzle, the time of changing the nozzle is prolonged by about 50 minutes compared with the prior art, 6, the inclusion discovery rate is 31.25 percent after the continuous casting slab is rolled into a cold rolled3O2The existence rate of fine impurities and large impurities is 0 percent, which is superior to the original process level.
The method can be used for smelting IF steel by using semisteel and can also be used for smelting IF steel by using molten iron, and the method belongs to the protection scope of the invention.
The principles and embodiments of the present invention are explained herein using specific examples, which are presented only to assist in understanding the method and its core concepts. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113337772A (en) * | 2021-05-24 | 2021-09-03 | 河钢股份有限公司承德分公司 | Method for producing IF steel by using vanadium-extracting semisteel |
| CN113564448A (en) * | 2021-07-28 | 2021-10-29 | 攀钢集团攀枝花钢铁研究院有限公司 | Method for smelting phosphorus-containing high-strength IF steel from semisteel |
| CN113564449A (en) * | 2021-07-28 | 2021-10-29 | 攀钢集团攀枝花钢铁研究院有限公司 | Semi-steel smelting method of phosphorus-containing high-strength IF steel |
| CN115433805A (en) * | 2022-08-31 | 2022-12-06 | 鞍钢股份有限公司 | Production method of ultra-low carbon steel |
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| CN113337772A (en) * | 2021-05-24 | 2021-09-03 | 河钢股份有限公司承德分公司 | Method for producing IF steel by using vanadium-extracting semisteel |
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| CN113564449A (en) * | 2021-07-28 | 2021-10-29 | 攀钢集团攀枝花钢铁研究院有限公司 | Semi-steel smelting method of phosphorus-containing high-strength IF steel |
| CN115433805A (en) * | 2022-08-31 | 2022-12-06 | 鞍钢股份有限公司 | Production method of ultra-low carbon steel |
| CN115433805B (en) * | 2022-08-31 | 2024-03-26 | 鞍钢股份有限公司 | A kind of production method of ultra-low carbon steel |
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