CN112267004B - Smelting method of low-cost clean steel - Google Patents

Smelting method of low-cost clean steel Download PDF

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CN112267004B
CN112267004B CN202010954173.2A CN202010954173A CN112267004B CN 112267004 B CN112267004 B CN 112267004B CN 202010954173 A CN202010954173 A CN 202010954173A CN 112267004 B CN112267004 B CN 112267004B
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steel
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李超
李建新
李�杰
张飞
刘占礼
郭子强
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HBIS Co Ltd
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Abstract

The invention discloses a smelting method of low-cost clean steel, and belongs to the technical field of metallurgy. The method comprises the working procedures of converter primary smelting, LF refining and VD vacuum treatment. The procedures of converter primary smelting, LF refining system deoxidation, slagging, alloying and the like are systematically controlled to ensure the refining slag component SiO at the LF end point 2 The mass percent is less than 8 percent, slag removal is carried out after LF refining is finished, the slag amount is controlled within 10 to 15kg/t steel after slag removal, and Al in the steel is adjusted before VD vacuum treatment t The content is 0.03-0.05%. By the measures, the comprehensive Al consumption in the steelmaking process is not more than 2.6kg/t, the product cleanliness is improved, the T.O. content in the steel plate is not more than 12ppm, the number of large-size inclusions is reduced, and the number density of the inclusions larger than 5 mu m in the rolled material is less than 0.5/mm 2 Area percent less than 2X 10 ‑5 。

Description

Smelting method of low-cost clean steel
Technical Field
The invention belongs to the technical field of metallurgy, and relates to a smelting method of low-cost clean steel.
Background
With the development of the technology, the requirements of downstream customers of steel on the performance of steel products are more and more strict, and non-metallic inclusions in steel have influence on the use and processing performance of final products, such as welding, fatigue resistance, corrosion resistance, cutting and the like, because of the customer quality objections caused by the non-metallic inclusions, a large amount of loss is brought to steel enterprises. Because of the change of supply and demand relations and the environmental protection importance of the country, steel enterprises face severe competition and survival pressure, and the high-efficiency and low-cost production of clean steel is a consensus of the metallurgical industry. The LF furnace refining can realize the metallurgical functions of temperature rise, slag formation, alloying and the like, and the VD furnace is a common device for steel-making refining and can realize the decarburization, degassing and removal of molten steel by blowing argon into a steel ladle under the vacuum conditionThe function of sulfur. Compared with an RH furnace, the VD furnace has low investment cost and strong desulphurization capability, but is inferior to the RH furnace in the aspects of deep decarburization and inclusion removal. In the VD working process, slag steel is mixed vigorously, on one hand, slag drops which are involved in molten steel can not be completely removed before casting and remain in the steel to form large-size inclusion, and on the other hand, for Al killed steel, the slag steel reacts in the VD process, and Al in the steel reacts with FeO, mnO and SiO in slag 2 Acting to form new Al 2 O 3 Inclusion, serious aluminum loss of molten steel, and silicon and manganese return of the molten steel, which are shown in formulas (1) to (3). At present, a plurality of steel enterprises using VD refining have definite control targets on the contents of FeO and MnO in refining slag, but have definite control targets on the contents of SiO 2 The knowledge of (a) is not sufficient.
The production of clean steel is a systematic project and is not realized through a certain process. The LF-VD duplex refining process is a common refining process, and how to realize the production of low-aluminum consumption and high-cleanliness steel is always troubled by enterprises on the premise of ensuring the metallurgical function of each refining device.
(FeO)+[Al] → (Al 2 O 3 )+[Fe] (1)
(MnO)+[Al] → (Al 2 O 3 )+[Mn] (2)
(SiO 2 )+[Al] → (Al 2 O 3 )+[Si] (3)。
Disclosure of Invention
In order to solve the technical problems, the invention provides a method for smelting low-cost clean steel, which adopts the technical scheme that:
a smelting method of low-cost clean steel comprises the working procedures of converter primary smelting, LF refining and VD vacuum treatment.
In the converter primary smelting process, the slag blocking cone and the sliding plate are combined to block slag in the tapping process, when the tapping amount is 70%, the slag blocking cone is added into a tapping hole of the converter, the converter is subjected to infrared detection, the sliding plate is immediately closed when the slag is discharged, and the slag discharge amount of the converter tapping is controlled to be less than or equal to 5kg/t steel. When tapping begins, 10-15 kg of carbon powder is added into a ladle for pre-deoxidation, when tapping is 1/3, 3-6 kg/t of steel is added into lime, and simultaneously, 1-2 kg/t of steel is added into aluminum particles or aluminum ingots for forced deoxidationOxygen to ensure Al in molten steel entering the LF refining process t The content is 0.02-0.04%.
In the LF refining process, ferrosilicon or silicomanganese is used for alloying, lime is used for slagging, fluorite is used for adjusting the viscosity and the fluidity of slag particles, calcium carbide and aluminum particles are used for diffusion deoxidation, so that SiO in LF terminal refining slag is ensured 2 Content (wt.)<8 percent of CaO, 50 to 60 percent of other components and Al 2 O 3 20～35%，MgO 5～8%，CaF 2 4～8%，FeO+MnO <1 percent and binary alkalinity R7.0 to 10.0.
After the LF refining process is finished, slagging off is carried out, and the slag amount after slagging off is controlled to be 10-15 kg/t steel.
According to the VD vacuum treatment process, the Al content is adjusted to be 0.03-0.05% according to the LF refining end point component before vacuum treatment. The vacuum degree is less than 60Pa, the holding time is 10-15 min, the bottom blowing argon pressure is 0.5-0.7 MPa for degassing and desulfurizing at the early stage of vacuum, and finally the bottom blowing argon pressure is adjusted to be 0.3-0.4 MPa for 5-10 min, so that the separation of slag and steel and the floating of impurities are promoted. After vacuum breaking, aluminum is supplemented according to the component requirements of the steel, soft blowing is carried out for 10-12 min, and the soft blowing pressure is 0.2-0.3 MPa.
SiO in lime in primary smelting and LF refining procedures of converter 2 The content is less than or equal to 5.5 percent, and the qualified standard of lime is met.
The clean steel continuous casting process adopts a protective casting mode.
The clean steel is low-carbon aluminum killed steel and comprises Q355 and EH36.
The core of the smelting method of the low-cost clean steel lies in inhibiting SiO in the slag in the VD process 2 With [ Al ] in molten steel]The reaction and the promotion of the floating of the inclusion. SiO in slag 2 The main sources are the silicon in the converter tapping slag, ferrosilicon/silicomanganese deoxidization, lime and other raw and auxiliary materials.
The corresponding measures are that the converter adopts a slag blocking cone and sliding plate double slag blocking measure to reduce tapping slag of the converter, and the slag amount of the converter is controlled to be not more than 5kg/t steel; al particles/ingots are used for strong deoxidation in the converter tapping process, the Alt content in LF refining station-entering steel is ensured to be 0.02 to 0.04 percent, and the supersaturation concentrations of Al and O during tapping are utilized to generate large-size alumina inclusion from the steel as soon as possibleRemoving the impurities by floating, wherein the added lime has the functions of slagging and adsorbing alumina impurities; in the LF slagging process, calcium carbide and Al particles are used for diffusion deoxidation, a small amount of fluorite is used for adjusting the viscosity and the fluidity of slag, and ferrosilicon/silicomanganese and other alloys are put in LF for alloying; for controlling SiO in lime used for refining after converter and LF 2 The content is less than or equal to 5.5 percent. The slag amount directly influences the aluminum consumption in the VD process, slag skimming operation is carried out after LF refining is finished, and the slag amount after slag skimming is 10 to 15kg/t steel. Adjusting molten steel Al according to LF end point components before VD vacuum t The content is within the range of 0.03 to 0.05 percent.
The invention carries out system control on the procedures of converter primary smelting, LF refining system deoxidation, slagging, alloying and the like, the comprehensive Al consumption in the steelmaking process is not more than 2.6kg/t, the product cleanliness is improved, the T.O. content in a steel plate is not more than 12ppm, the number of large-size inclusions is reduced, and the number density of inclusions larger than 5 mu m in a rolled material is less than 0.5 per mm 2 Area percent less than 2X 10 -5 。
Detailed Description
The present invention will be described in further detail with reference to the following examples.
Example 1
The smelting method of the low-cost clean steel adopts a process route of BOF → LF → VD → CC, the specific steel type to be smelted is Q355D, and the specific process control is as follows:
(1) And BOF (boil-off oxygen decarburization) working procedure, wherein a slag blocking cone and a sliding plate are combined for blocking slag in the converter tapping process, when the converter tapping amount is 70%, the slag blocking cone is added into a converter tapping hole, the converter tapping is detected by infrared, the sliding plate is immediately closed when the tapping appears, and the converter tapping slag amount is controlled to be 3kg/t steel. Tapping is started, 14.5kg of carbon powder is added into a ladle for pre-deoxidation, 1kg/t of aluminum particles are added for strong deoxidation when 1/3 of tapping is carried out, 3kg/t of lime is added simultaneously, and LF refining station-entering molten steel Al t The content is controlled at 0.02%. SiO in lime used for refining after converter and LF 2 The content is less than or equal to 5.5 percent, and the qualified standard of lime is met.
(2) LF refining process, namely alloying ferrosilicon or silicomanganese, slagging with lime, adjusting slag viscosity and fluidity with fluorite, performing diffusion deoxidation with calcium carbide and aluminum particles, and refining SiO in slag at LF end point 2 The content is 6.44 percent, and the binary alkalinity R is 7.8. The ingredients and contents of the LF end-point refining slag are shown in Table 1.
(3) And after LF refining is finished, carrying out slag skimming operation, and controlling the slag amount after slag skimming to be 15kg/t steel.
(4) VD vacuum treatment, wherein the Al content is adjusted to be 0.04 percent according to the LF refining end point component before vacuum treatment. Keeping the high vacuum degree for 15 min when the pressure is less than 60Pa, degassing and desulfurizing under the bottom blowing argon pressure of 0.7MPa in the early period, and adjusting the bottom blowing argon pressure to 0.4MPa for 5min to promote slag steel separation and inclusion floating. The specific molten steel components before and after VD are shown in Table 2. And (3) supplementing aluminum according to the internal control requirement of the steel grade after the air is broken, and carrying out soft blowing for 11min at the soft blowing pressure of 0.3MPa. The ingredients and contents of the VD refined slag after vacuum breaking are shown in Table 1.
(5) The continuous casting process adopts a protective casting mode.
The molten steel components before the VD vacuum treatment process and after the VD vacuum breaking are shown in the table 2, and the comprehensive aluminum consumption and the steel plate cleanliness are shown in the table 3.
Example 2
The method for producing clean steel by low-cost LF-VD refining adopts the process route of BOF → LF → VD → CC, the specific steel type for smelting is Q355D, and the specific process control is as follows:
(1) And BOF (boil-off-gas) working procedure, wherein a slag blocking cone and a sliding plate are combined to block slag in the converter tapping process, when the converter tapping amount is 70%, the slag blocking cone is added into a converter tapping hole, the converter tapping is detected by infrared, the sliding plate is closed immediately when the tapping appears, and the converter tapping and slag dropping amount is controlled to be 5kg/t steel. Tapping is started, 15kg of carbon powder is added into a ladle for pre-deoxidation, 1.5kg/t of aluminum particles are added for strong deoxidation when 1/3 of tapping is carried out, 5kg/t of lime is added simultaneously, and LF refining station-entering molten steel Al t The content is controlled at 0.03%. SiO in lime used for refining after converter and LF 2 The content is less than or equal to 5.5 percent, and the qualified standard of lime is met.
(2) LF refining process, namely alloying silicon iron or silicon manganese, slagging with lime, adjusting slag viscosity and fluidity with fluorite, and performing diffusion deoxidation with calcium carbide and aluminum particles to ensure SiO in LF end point refining slag 2 The content is 7.7 percent, and the binary alkalinity R is 7.5. The ingredients and contents of the LF end-point refining slag are shown in Table 1.
(3) And after LF refining is finished, carrying out slag skimming operation, and controlling the slag amount after slag skimming to be 10kg/t steel.
(4) VD vacuum treatment process, wherein the Al content is adjusted to be 0.03 percent according to the LF refining end point component before vacuum treatment. Keeping the high vacuum degree for 12 min when the pressure is less than 60Pa, degassing and desulfurizing at the bottom argon blowing pressure of 0.5MPa in the early period, and adjusting the bottom argon blowing pressure to 0.3MPa in the last 6min to promote slag steel separation and inclusion floating. The specific molten steel components before and after VD are shown in Table 2. And (4) supplementing aluminum according to the internal control requirement of the steel grade after the air break, and carrying out soft blowing for 11.5min at the soft blowing pressure of 0.3MPa. The ingredients and contents of the VD refined slag after vacuum breaking are shown in Table 1.
(5) The continuous casting process adopts a protective casting mode.
The molten steel components before the VD vacuum treatment process and after the VD vacuum breaking are shown in the table 2, and the comprehensive aluminum consumption and the steel plate cleanliness are shown in the table 3.
Example 3
The method for producing clean steel by low-cost LF-VD refining adopts the process route of BOF → LF → VD → CC, the specific steel type for smelting is Q355D, and the specific process control is as follows:
(1) And BOF (boil-off-gas) working procedure, wherein a slag blocking cone and a sliding plate are combined to block slag in the converter tapping process, when the converter tapping amount is 70%, the slag blocking cone is added into a converter tapping hole, the converter tapping is detected by infrared, the sliding plate is closed immediately when the tapping appears, and the converter tapping and slag dropping amount is controlled to be 5kg/t steel. Tapping is started, 15kg of carbon powder is added into a ladle for pre-deoxidation, 2.0kg/t of aluminum ingot is added for strong deoxidation when 1/3 of tapping is carried out, 6kg/t of steel is added simultaneously, and LF refining station-entering molten steel Al t The content is controlled to be 0.04 percent. SiO in lime used for refining after converter and LF 2 The content is less than or equal to 5.5 percent, and the qualified standard of lime is met.
(2) LF refining process, namely ferrosilicon or silicomanganese alloying, lime slagging, fluorite adjusting slag viscosity and fluidity, and calcium carbide and aluminum particles are used for diffusion deoxidation to ensure SiO in LF end-point refining slag 2 The content is 6.08 percent, and the binary alkalinity R is 9.9. The ingredients and contents of the LF end-point refining slag are shown in Table 1.
(3) And after LF refining is finished, carrying out slag skimming operation, and controlling the slag amount after slag skimming to be 14kg/t steel.
(4) VD vacuum treatment, wherein the Al content is adjusted to be 0.03 percent according to the LF refining end point component before vacuum treatment. Keeping the high vacuum degree for 10 min when the pressure is less than 60Pa, degassing and desulfurizing under the bottom blowing argon pressure of 0.6MPa in the former period, and adjusting the bottom blowing argon pressure to 0.3MPa in the last 10 min to promote slag steel separation and inclusion floating. The specific molten steel compositions before and after VD are shown in Table 2. And (4) supplementing aluminum according to the internal control requirement of the steel grade after the air break, and carrying out soft blowing for 12 min under the soft blowing pressure of 0.25MPa. The ingredients and contents of the VD refined slag after vacuum breaking are shown in Table 1.
(5) The continuous casting process adopts a protective casting mode.
The molten steel components before the VD vacuum treatment process and after the VD vacuum breaking are shown in the table 2, and the comprehensive aluminum consumption and the steel plate cleanliness are shown in the table 3.
Example 4
The method for producing clean steel by low-cost LF-VD refining adopts the process route of BOF → LF → VD → CC, the specific steel type for smelting is Q355D, and the specific process control is as follows:
(1) And BOF (boil-off-gas) working procedure, wherein a slag blocking cone and a sliding plate are combined to block slag in the converter tapping process, when the converter tapping amount is 70%, the slag blocking cone is added into a converter tapping hole, the converter tapping is detected by infrared, the sliding plate is closed immediately when the tapping appears, and the converter tapping and slag dropping amount is controlled to be 4kg/t steel. Tapping is started, 10kg of carbon powder is added into a ladle for pre-deoxidation, 1.8kg of aluminum ingot is added for strong deoxidation when 1/3 of tapping is carried out, 6kg of lime is added for strong deoxidation at the same time, and LF refining station-entering molten steel Al t The content is controlled to be 0.035%. SiO in lime used for refining after converter and LF 2 The content is less than or equal to 5.5 percent, and the qualified standard of lime is met.
(2) LF refining process, namely alloying silicon iron or silicon manganese, slagging with lime, adjusting slag viscosity and fluidity with fluorite, and performing diffusion deoxidation with calcium carbide and aluminum particles to ensure SiO in LF end point refining slag 2 The content is 5.11 percent, and the binary alkalinity R is 9.8. The ingredients and contents of the LF end-point refining slag are shown in Table 1.
(3) And after LF refining is finished, carrying out slag skimming operation, and controlling the slag amount after slag skimming to be 14kg/t steel.
(4) VD vacuum treatment, wherein the Al content is adjusted to be 0.05 percent according to the LF refining end point component before vacuum treatment. Keeping the high vacuum degree for 10 min when the pressure is less than 60Pa, degassing and desulfurizing under the bottom blowing argon pressure of 0.6MPa in the former period, and adjusting the bottom blowing argon pressure to 0.4MPa in the last 10 min to promote slag steel separation and inclusion floating. The specific molten steel compositions before and after VD are shown in Table 2. And (3) supplementing aluminum according to the internal control requirement of the steel grade after the air is broken, and carrying out soft blowing for 12 min at the soft blowing pressure of 0.2MPa. The ingredients and contents of the refining slag after vacuum breaking by VD are shown in Table 1.
(5) The continuous casting process adopts a protective casting mode.
The molten steel components before the VD vacuum treatment process and after the VD vacuum breaking are shown in the table 2, and the comprehensive aluminum consumption and the steel plate cleanliness are shown in the table 3.
Example 5
The method for producing clean steel by low-cost LF-VD refining adopts the process route of BOF → LF → VD → CC, the specific steel type for smelting is EH36, and the specific process control is as follows:
(1) And BOF (boil-off-gas) working procedure, wherein a slag blocking cone and a sliding plate are combined to block slag in the converter tapping process, when the converter tapping amount is 70%, the slag blocking cone is added into a converter tapping hole, the converter tapping is detected by infrared, the sliding plate is closed immediately when the tapping appears, and the converter tapping and slag amount is controlled to be 2.6kg/t steel. Tapping is started, 10.5kg of carbon powder is added into a ladle for pre-deoxidation, 1.2kg of aluminum particles are added for strong deoxidation when 1/3 of tapping is carried out, 4.3 kg of lime is added for strong deoxidation at the same time, and LF refining is carried out to obtain molten steel Al t The content is controlled at 0.038%. SiO in lime used for refining after converter and LF 2 The content is less than or equal to 5.5 percent, and the qualified standard of lime is met.
(2) LF refining process, namely alloying silicon iron or silicon manganese, slagging with lime, adjusting slag viscosity and fluidity with fluorite, and performing diffusion deoxidation with calcium carbide and aluminum particles to ensure SiO in LF end point refining slag 2 The content is 7.48%, and the binary basicity R is 7.2. The ingredients and contents of the LF end-point refining slag are shown in Table 1.
(3) And after LF refining is finished, carrying out slag skimming operation, and controlling the slag amount after slag skimming to be 11kg/t steel.
(4) VD vacuum treatment, wherein the Al content is adjusted to be 0.035% according to the LF refining end point composition before vacuum treatment. Keeping the high vacuum degree for 14 min when the vacuum degree is less than 60Pa, degassing and desulfurizing at the early stage under the bottom blowing argon pressure of 0.55MPa, and adjusting the bottom blowing argon pressure to 0.32MPa for the last 7 min to promote slag steel separation and inclusion floating. The specific molten steel components before and after VD are shown in Table 2. And (5) supplementing aluminum according to the internal control requirement of the steel grade after the air break, and carrying out soft blowing for 10 min under the soft blowing pressure of 0.26MPa. The ingredients and contents of the VD refined slag after vacuum breaking are shown in Table 1.
(5) The continuous casting process adopts a protective casting mode.
The molten steel components before the VD vacuum treatment process and after the VD vacuum breaking are shown in a table 2, and the comprehensive aluminum consumption and steel plate cleanliness are shown in a table 3.
Example 6
The method for producing clean steel by low-cost LF-VD refining adopts the process route of BOF → LF → VD → CC, the specific steel type for smelting is EH36, and the specific process control is as follows:
(1) And BOF (boil-off-slag) working procedure, wherein a slag blocking cone and a sliding plate are combined to block slag in the converter tapping process, when the converter tapping amount is 70%, the slag blocking cone is added into a converter tapping hole, converter slag discharging is detected in an infrared mode, the sliding plate is closed immediately when slag discharging occurs, and the converter tapping slag discharging amount is controlled to be 4.8kg/t steel. Tapping is started, 13.5kg of carbon powder is added into a ladle for pre-deoxidation, 1.6kg/t of aluminum ingot is added for strong deoxidation when 1/3 of steel is tapped, 5.5 kg/t of lime steel is added simultaneously, and LF refining station entering molten steel Al t The content is controlled at 0.022%. SiO in lime used for refining after converter and LF 2 The content is less than or equal to 5.5 percent, and the qualified standard of lime is met.
(2) LF refining process, namely alloying silicon iron or silicon manganese, slagging with lime, adjusting slag viscosity and fluidity with fluorite, and performing diffusion deoxidation with calcium carbide and aluminum particles to ensure SiO in LF end point refining slag 2 The content is 6.85 percent, and the binary alkalinity R is 8.5. The components and contents of the LF end-point refining slag are shown in Table 1.
(3) And after LF refining is finished, carrying out slag skimming operation, and controlling the slag amount after slag skimming to be 13kg/t steel.
(4) VD vacuum treatment, wherein the Al content is adjusted to be 0.049% according to the LF refining end point component before vacuum treatment. Keeping the high vacuum degree for 11min when the pressure is less than 60Pa, degassing and desulfurizing at the bottom argon blowing pressure of 0.55MPa in the early period, and adjusting the bottom argon blowing pressure to 0.38MPa in the last period for 9min to promote slag steel separation and inclusion floating. The specific molten steel compositions before and after VD are shown in Table 2. And (3) supplementing aluminum according to the internal control requirement of the steel grade after the air is broken, and carrying out soft blowing for 11min at the soft blowing pressure of 0.28MPa. The ingredients and contents of the refining slag after vacuum breaking by VD are shown in Table 1.
(5) The continuous casting process adopts a protective casting mode.
The molten steel components before the VD vacuum treatment process and after the VD vacuum breaking are shown in the table 2, and the comprehensive aluminum consumption and the steel plate cleanliness are shown in the table 3.
Example 7
The method for producing clean steel by low-cost LF-VD refining adopts the process route of BOF → LF → VD → CC, the specific steel type for smelting is EH36, and the specific process control is as follows:
(1) And BOF (boil-off-gas) working procedure, wherein a slag blocking cone and a sliding plate are combined to block slag in the converter tapping process, when the converter tapping amount is 70%, the slag blocking cone is added into a converter tapping hole, the converter tapping is detected by infrared, the sliding plate is closed immediately when the tapping appears, and the converter tapping and slag amount is controlled to be 3.3kg/t steel. Tapping is started, 11.8kg of carbon powder is added into a ladle for pre-deoxidation, 1.9kg of aluminum particles are added into the ladle for strong deoxidation when 1/3 of the steel is tapped, 3.5kg of lime is added into the ladle at the same time, and LF refining is carried out to obtain molten steel Al t The content is controlled to be 0.027%. SiO in lime used for refining after converter and LF 2 The content is less than or equal to 5.5 percent, and the qualified standard of lime is met.
(2) LF refining process, namely ferrosilicon or silicomanganese alloying, lime slagging, fluorite adjusting slag viscosity and fluidity, and calcium carbide and aluminum particles are used for diffusion deoxidation to ensure SiO in LF end-point refining slag 2 The content is 6.96%, and the binary basicity R is 8.2. The ingredients and contents of the LF end-point refining slag are shown in Table 1.
(3) And after LF refining is finished, carrying out slag skimming operation, and controlling the slag amount after slag skimming to be 12kg/t steel.
(4) And VD vacuum treatment, wherein the Al content is adjusted to be 0.045% according to LF refining end point components before vacuum treatment. Keeping the high vacuum degree for 13 min when the vacuum degree is less than 60Pa, degassing and desulfurizing at the bottom blowing argon pressure of 0.65MPa in the early period, and adjusting the bottom blowing argon pressure to 0.35MPa for the last 8min to promote slag steel separation and inclusion floating. The specific molten steel components before and after VD are shown in Table 2. And (3) supplementing aluminum according to the internal control requirement of the steel grade after the air is broken, and carrying out soft blowing for 10.5min at the soft blowing pressure of 0.22MPa. The ingredients and contents of the VD refined slag after vacuum breaking are shown in Table 1.
(5) The continuous casting process adopts a protective casting mode.
The molten steel components before the VD vacuum treatment process and after the VD vacuum breaking are shown in the table 2, and the comprehensive aluminum consumption and the steel plate cleanliness are shown in the table 3.
Comparative example 1
The method for producing clean steel by LF-VD refining of a certain steel rabbet adopts the process route of BOF → LF → VD → CC, the specific smelting steel type is Q355D, and the specific process control is as follows:
(1) And BOF (boil-off-gas) working procedure, wherein a slag blocking cone and a sliding plate are combined to block slag in the converter tapping process, when the converter tapping amount is 70%, the slag blocking cone is added into a converter tapping hole, the converter tapping is detected by infrared, the sliding plate is closed immediately when the tapping appears, and the converter tapping and slag dropping amount is controlled to be 5kg/t steel. Tapping is started, 10kg of carbon powder is added into a ladle for pre-deoxidation, 0.4kg/t of aluminum particles and 1500kg of silicomanganese are added when 1/3 of tapping is carried out, 5kg/t of lime is simultaneously added, and LF station-entering molten steel Al t The content is 0.008%. Lime SiO used for converter post-refining and refining 2 The content is less than or equal to 5.5 percent, and the qualified standard of lime is met.
(2) The LF refining process, the ferrosilicon/silicomanganese alloying carries out fine adjustment on the contents of Si and Mn in the LF stage, the slagging material is mainly lime, fluorite is used for adjusting the viscosity and the fluidity of slag particles, calcium carbide and aluminum particles are used for diffusion deoxidation, an Al wire is used for precipitation deoxidation and alloying, and SiO in LF terminal refining slag 2 The content is 13.33%, and the binary alkalinity R is 3.8. The ingredients and contents of the LF end-point refining slag are shown in Table 1.
(3) And after LF refining is finished, carrying out slag skimming operation, and controlling the slag amount after slag skimming to be 15kg/t steel.
(4) VD vacuum treatment, wherein the Al content is adjusted to be 0.1 percent according to the LF refining end point component before vacuum treatment. Keeping the high vacuum degree for 15 min when the pressure is less than 60Pa, degassing and desulfurizing under the bottom blowing argon pressure of 0.7MPa in the early period, and adjusting the bottom blowing argon pressure to 0.4MPa for 5min to promote slag steel separation and inclusion floating. The specific molten steel components before and after VD are shown in Table 2. And (3) supplementing aluminum according to the internal control requirement of the steel grade after the air is broken, and carrying out soft blowing for 12 min at the soft blowing pressure of 0.3MPa. The ingredients and contents of the VD refined slag after vacuum breaking are shown in Table 1.
(5) The continuous casting process adopts a protective casting mode.
The specific steel slag components are respectively shown in tables 1 and 2, and the comprehensive aluminum consumption and steel plate cleanliness are shown in table 3.
Comparative example 2
The method for producing clean steel by LF-VD refining of a certain steel rabbet adopts the process route of BOF → LF → VD → CC, the specific smelting steel type is Q355D, and the specific process control is as follows:
(1) And BOF (boil-off-gas) working procedure, wherein a slag blocking cone and a sliding plate are combined to block slag in the converter tapping process, when the converter tapping amount is 70%, the slag blocking cone is added into a converter tapping hole, the converter tapping is detected by infrared, the sliding plate is closed immediately when the tapping appears, and the converter tapping and slag dropping amount is controlled to be 5kg/t steel. Tapping is started, 10kg of carbon powder is added into a ladle for pre-deoxidation, 0.5kg/t of aluminum ingot and 1500kg of silicon manganese are added when 1/3 of tapping is carried out, 6kg/t of lime is added simultaneously, and LF station-entering molten steel Al t The content is 0.01 percent. Lime SiO used for converter post-refining and refining 2 The content is less than or equal to 5.5 percent, and the qualified standard of lime is met.
(2) The LF refining process, the ferrosilicon/silicomanganese alloying carries out fine adjustment on the contents of Si and Mn in the LF stage, the slagging material is mainly lime, fluorite is used for adjusting the viscosity and the fluidity of slag particles, calcium carbide and aluminum particles are used for diffusion deoxidation, an Al wire is used for precipitation deoxidation and alloying, and SiO in LF terminal refining slag 2 The content is 10.10 percent, and the binary alkalinity R is 5.4. The ingredients and contents of the LF end-point refining slag are shown in Table 1.
(3) And after LF refining is finished, carrying out slag skimming operation, and controlling the slag amount after slag skimming to be 15kg/t steel.
(4) VD vacuum treatment, wherein the Al content is adjusted to be 0.08 percent according to the LF refining end point component before vacuum treatment. Keeping the high vacuum degree for 15 min when the pressure is less than 60Pa, degassing and desulfurizing under the bottom blowing argon pressure of 0.7MPa in the early period, and adjusting the bottom blowing argon pressure to 0.4MPa for 5min to promote slag steel separation and inclusion floating. The specific molten steel compositions before and after VD are shown in Table 2. And (3) supplementing aluminum according to the internal control requirement of the steel grade after the air is broken, and carrying out soft blowing for 12 min at the soft blowing pressure of 0.3MPa. The ingredients and contents of the VD refined slag after vacuum breaking are shown in Table 1.
(5) The continuous casting process adopts a protective casting mode.
The concrete steel slag components are respectively shown in tables 1 and 2, and the comprehensive aluminum consumption and the steel plate cleanliness are shown in table 3.
Comparative example 3
The method for producing clean steel by LF-VD refining of a certain steel rabbet adopts the process route of BOF → LF → VD → CC, the specific steel type for smelting is EH36, and the specific process control is as follows:
(1) And BOF (boil-off-gas) working procedure, wherein a slag blocking cone and a sliding plate are combined to block slag in the converter tapping process, when the converter tapping amount is 70%, the slag blocking cone is added into a converter tapping hole, the converter tapping is detected by infrared, the sliding plate is closed immediately when the tapping appears, and the converter tapping and slag dropping amount is controlled to be 5kg/t steel. Tapping is started, 10kg of carbon powder is added into a ladle for pre-deoxidation, 0.5kg/t of aluminum ingot and 1600kg of silicon manganese are added when 1/3 of tapping is carried out, 7 kg/t of lime is added simultaneously, and LF station-entering molten steel Al t The content is 0.008%. Lime SiO used for converter post-refining and refining 2 The content is less than or equal to 5.5 percent, and the qualified standard of lime is met.
(2) The LF refining process, the ferrosilicon/silicomanganese alloying carries out fine adjustment on the contents of Si and Mn in the LF stage, the slagging material is mainly lime, fluorite is used for adjusting the viscosity and the fluidity of slag particles, calcium carbide and aluminum particles are used for diffusion deoxidation, an Al wire is used for precipitation deoxidation and alloying, and SiO in LF terminal refining slag 2 The content is 10.10 percent, and the binary alkalinity R is 5.4. The components and contents of the LF end-point refining slag are shown in Table 1.
(3) And after LF refining is finished, carrying out slag skimming operation, and controlling the slag amount after slag skimming to be 15kg/t steel.
(4) VD vacuum treatment, wherein the Al content is adjusted to be 0.08 percent according to the LF refining end point component before vacuum treatment. Keeping the high vacuum degree for 15 min when the vacuum degree is less than 60Pa, degassing and desulfurizing at the bottom blowing argon pressure of 0.7MPa in the early period, and adjusting the bottom blowing argon pressure to 0.4MPa for the last 5min to promote slag steel separation and inclusion floating. The specific molten steel components before and after VD are shown in Table 2. And (3) supplementing aluminum according to the internal control requirement of the steel grade after the air is broken, and carrying out soft blowing for 12 min at the soft blowing pressure of 0.3MPa. The ingredients and contents of the refining slag after vacuum breaking by VD are shown in Table 1.
(5) The continuous casting process adopts a protective casting mode.
The specific steel slag components are respectively shown in tables 1 and 2, and the comprehensive aluminum consumption and steel plate cleanliness are shown in table 3.
TABLE 1 EXAMPLES AND COMPARATIVE EXAMPLES refining slag composition
Figure DEST_PATH_IMAGE001
TABLE 2 composition of molten steel for examples and comparative examples
Figure 686642DEST_PATH_IMAGE002
In table 2, the balance is Fe and inevitable impurity elements.
TABLE 3 examples and comparative examples combine aluminium consumption and steel plate cleanliness
Figure DEST_PATH_IMAGE003
Analyzing the change of the components of the refining slag and the molten steel before and after VD in the examples and comparative examples in the tables 1 and 2, fully contacting and reacting the slag steel in the VD process under the stirring of large-flow argon, and reducing SiO in the Al reducing slag in the steel 2 FeO, mnO, etc. to form new Al 2 O 3 The oxidizability of the slag is reduced, the alkalinity is increased, and the Al content in the steel is reduced. Examples SiO in LF end-point slag due to measures such as strong deoxidation after converter and enhanced diffusion deoxidation in LF process 2 The content of the components which are easy to be reduced by Al is low, and the content of the molten steel S at the LF end point is relatively low. Before VD vacuum, the Al content is adjusted to be in a relatively low level of 0.03-0.05%, and Al loss and new inclusion generation amount caused by slag steel reaction in the VD process are reduced. The comprehensive aluminum consumption in Table 3 is the Al consumption in the whole steel making process from the converter to the continuous casting, and includes all aluminum deoxidizers such as Al wires and Al particles. As is clear from Table 3, the examples showed a significant reduction in the total oxygen content and the inclusion content of the steel sheet in combination with a reduction in the aluminum consumption.

Claims (6)

1. A smelting method of low-cost clean steel comprises the working procedures of converter primary smelting, LF refining and VD vacuum treatment, and is characterized in that in the working procedure of converter primary smelting, a slag blocking cone and a sliding plate are combined for slag blocking in the process of steel tapping, and the slag amount of the converter steel tapping is controlled to be less than or equal to 5kg/t steel; when tapping begins, 10-15 kg of carbon powder is added into a ladle for pre-deoxidation, 3-6 kg of lime is added into the ladle at the time of tapping 1/3,simultaneously adding 1-2 kg/t of aluminum particles or aluminum ingots for strong deoxidation to ensure Al in the molten steel entering the station in the LF refining process t The content is 0.02-0.04%;
in the LF refining process, ferrosilicon or silicomanganese is used for alloying, lime is used for slagging, fluorite is used for adjusting the viscosity and the fluidity of slag particles, and calcium carbide and aluminum particles are used for diffusion deoxidation to ensure SiO in LF end-point refining slag 2 Content (wt.)<8 percent; slagging off is carried out after the LF refining process is finished; the other components and the weight content of the LF end point refining slag are 50-60 percent of CaO and Al 2 O 3 20～35%，MgO 5～8%，CaF 2 4～8%，FeO+MnO <1 percent of binary alkalinity R7.0 to 10.0;
in the VD vacuum treatment process, the Al content is adjusted to be 0.03-0.05% according to the LF refining end point component before vacuum treatment; the vacuum degree is less than 60Pa, the holding time is 10-15 min, the bottom blowing argon pressure is 0.5-0.7 MPa for degassing and desulfurizing at the early stage of vacuum, and finally the bottom blowing argon pressure is adjusted to be 0.3-0.4 MPa for 5-10 min, so that the separation of slag and steel and the floating of impurities are promoted;
the clean steel is low-carbon aluminum killed steel and comprises Q355 and EH36.
2. The method for smelting low-cost clean steel according to claim 1, wherein the method comprises the following steps: in the converter primary smelting process, when the steel tapping amount is 70%, the slag blocking cone is added into a converter steel tapping hole, the converter slag tapping is detected by infrared, and the sliding plate is closed immediately when the slag tapping occurs.
3. The method for smelting low-cost clean steel according to claim 2, wherein the method comprises the following steps: the slag amount after slag skimming is controlled to be 10-15 kg/t steel.
4. The method for smelting low-cost clean steel according to claim 3, wherein the method comprises the following steps: in the VD vacuum treatment process, aluminum is supplemented according to the component requirements of the steel grade after vacuum breaking, soft blowing is carried out for 10-12 min, and the soft blowing pressure is 0.2-0.3 MPa.
5. The method for smelting low-cost clean steel according to any one of claims 1 to 4, characterized in that: the converter primary smelting and LF refiningSiO in process lime 2 The content is less than or equal to 5.5 percent, and the qualified standard of lime is met.
6. The method for smelting low-cost clean steel according to any one of claims 1 to 4, characterized in that: and the clean steel continuous casting process adopts a protective casting mode.
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