CN111020117B - Method for promoting RH decarburization - Google Patents

Method for promoting RH decarburization Download PDF

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CN111020117B
CN111020117B CN201911328810.9A CN201911328810A CN111020117B CN 111020117 B CN111020117 B CN 111020117B CN 201911328810 A CN201911328810 A CN 201911328810A CN 111020117 B CN111020117 B CN 111020117B
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steel
oxygen
aluminum
decarburization
molten steel
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CN111020117A (en
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刘建华
张�杰
何杨
袁保辉
雷铭宇
闫柏军
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University of Science and Technology Beijing USTB
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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
    • 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
    • C21C7/068—Decarburising

Abstract

A method for promoting RH decarburization. Before or during the RH decarburization of the ultra-low carbon steel, adding aluminum or aluminum alloy into the molten steel, and forming dispersed Al in the molten steel by utilizing the aluminum-oxygen reaction2O3Inclusions, Al produced2O3The inclusion has poor wettability and large wetting angle with the molten steel, becomes a heterogeneous nucleation core for generating carbon monoxide bubbles through RH decarburization reaction, promotes the nucleation of the carbon monoxide bubbles, increases the nucleation depth of the carbon monoxide bubbles in the molten steel, enlarges the thickness of a reaction layer of the carbon-oxygen reaction in an RH vacuum tank, and improves the RH deep decarburization capability. By the method, the RH decarburization rate can be effectively increased, and the end point carbon content is reduced by 1-10 multiplied by 10‑6. The generated carbon monoxide has small bubble size and strong capability of capturing impurities, and can promote the Al generated earlier2O3The inclusion is removed, and the molten steel is not polluted.

Description

Method for promoting RH decarburization
Technical Field
The invention belongs to the technical field of metallurgy, and particularly relates to a method for promoting RH decarburization.
Background
In recent years, ultra-low carbon steel has been widely used in the manufacturing industries of electric appliances, electronic devices, automobiles, machinery, and the like, because of its excellent toughness, processability, electromagnetic properties, and the like. With the rapid increase of the demand of ultra-low carbon steel and the strict control requirement on the RH end-point carbon content, the research on the RH rapid deep decarburization has important significance.
Many researches show that the influence of the diffusion speed of carbon and oxygen in molten steel and the shape of carbon monoxide bubble on the decarburization rate is large, and the influence is more obvious especially under the low-carbon condition. According to experimental and practical production results, the decarburization rate can be improved and the end point carbon content can be reduced by reducing the vacuum degree and the vacuumizing speed, increasing the gas flow, increasing the oxygen content of the molten steel before RH treatment of the molten steel, selecting a proper pipe diameter of the dip pipe and the like, but the methods need to greatly change process parameters and equipment or influence the subsequent treatment process, and the operation difficulty is high.
In view of the above problems, it is desirable to develop a method for promoting RH decarburization without changing process parameters and equipment and with little influence on the subsequent processes.
Disclosure of Invention
In view of the above difficulties, the present invention discloses a method for promoting RH decarburization by adding aluminum to molten steel before or during RH decarburization to form dispersed Al in the molten steel by the reaction of aluminum and oxygen2O3Inclusions, carbon monoxide bubbles and Al2O3The inclusions are generated by heterogeneous nucleation cores, so that the nucleation difficulty of carbon monoxide bubbles is reduced, and the decarburization reaction is promoted. The technology has the advantages of obviously promoting the RH decarburization rate, not changing process parameters and equipment and having little influence on subsequent processes.
The invention is realized by the following technical scheme:
a method for promoting RH decarburization comprises adding aluminum or aluminum alloy into molten steel before or during RH decarburization to form dispersed Al in the molten steel by aluminum-oxygen reaction2O3Inclusions, Al produced2O3The inclusion has poor wettability and large wetting angle with the molten steel, becomes a heterogeneous nucleation core for generating carbon monoxide bubbles through RH decarburization reaction, promotes the nucleation of the carbon monoxide bubbles, increases the nucleation depth of the carbon monoxide bubbles in the molten steel, enlarges the thickness of a reaction layer of the carbon-oxygen reaction in an RH vacuum tank, and improves the RH deep decarburization capability. The generated carbon monoxide bubbles have small size and strong capability of capturing impurities, can obviously promote the aggregation and growth of the impurities on the surfaces of the bubbles, and is beneficial to the Al generated earlier2O3The inclusion is removed, and the molten steel is not polluted.
Further, the method specifically comprises the following steps: adding aluminum and aluminum alloy into the molten steel in the tapping process of the converter, or adding aluminum and aluminum alloy into the molten steel before RH treatment, or adding aluminum and aluminum alloy into the molten steel in the vacuum tank from a bin above the vacuum tank in the early stage of RH treatment, wherein the added aluminum reacts with dissolved oxygen in the molten steel to generate Al in the molten steel2O3And (4) inclusion.
Furthermore, the relation between the total aluminium amount w [ Al ] (kg) added to the aluminium or aluminium alloy during tapping from the converter and the mass w [ steel ] (t) of the molten steel is:
w is more than or equal to 0.225w and less than or equal to 1.125w
The relationship between the total amount of aluminum added to the aluminum or aluminum alloy before RH treatment, wAl (kg), and the mass of molten steel, wSteel (t), is:
0.1575w [ steel ] or more and w [ Al ] or less 0.9w [ steel ]
In the earlier stage of RH vacuum treatment, the relation between the total aluminum content (wAl (kg)) added into aluminum or aluminum alloy in molten steel in a vacuum tank from a stock bin above the vacuum tank and the molten steel mass (wSteel (t)) is as follows:
0.1125w [ steel ] is less than or equal to w [ Al ] is less than or equal to 0.45w [ steel ].
Further, when aluminum or an aluminum alloy is added to the molten steel before RH decarburization, for example, the oxygen mass concentration C in the steel at the start of RH decarburization[O]Less than 250X 10-6+1.5C[C](C[C]Carbon mass concentration in steel), blowing oxygen into the steel by using a top lance in the initial stage of RH decarburization, wherein the flow of the oxygen blowing is controlled within a small flow range, and the specific flow is as follows: the oxygen blowing flow of the ladle is controlled to be less than or equal to 180t and is controlled to be 600-1200 m3H; more than 180t of steel ladle, the oxygen blowing flow is more than or equal to 1000-2000 m3H is used as the reference value. Total oxygen blowing amount Nm in RH process3Controlled to be {350w [ steel ]]×[(1.2～1.3)(1.4C[C]+250×10-6)-C[O]]}。
Further, when aluminum or an aluminum alloy is added to the molten steel in the vacuum vessel from a bunker above the vacuum vessel in the early stage of RH refining, for example, the mass concentration C of oxygen in the steel at the start of RH decarburization[O]Less than 250X 10-6+1.5C[C]+0.00113w[Al]Steel/w]When adding aluminum and aluminum alloy, the large-size Al is promoted by adopting top lance to blow oxygen at large flow rate2O3The formation of the inclusion is more beneficial to the inclusion to become the nucleus of the carbon monoxide bubble, and the specific oxygen blowing flow is as follows: the oxygen blowing flow of the ladle is less than or equal to 180t, and is more than or equal to 1200-2000 m3H; more than 180t of steel ladle, the oxygen blowing flow is more than or equal to 2000-3500 m3H is used as the reference value. After the large-flow oxygen blowing is carried out for 1min, the small-flow oxygen blowing is changed, and the specific oxygen blowing flow is as follows: the oxygen blowing flow of the ladle is controlled to be less than or equal to 180t and is controlled to be 600-1200 m3H; more than 180t of steel ladle, the oxygen blowing flow is more than or equal to 1000-2000 m3H is used as the reference value. The total oxygen blowing amount is controlled to be {350w [ steel ]]×[(1.2～1.3)(1.4C[C]+250×10-6+0.00113w[Al]Steel/w])-C[O]]}。
Further, Al generated during the RH decarburization process2O3The inclusions become heterogeneous nucleation cores for generating carbon monoxide bubbles through carbon-oxygen reaction, the generation and decarburization reaction of the carbon monoxide bubbles are promoted, the decarburization reaction kinetic constant is remarkably improved, the RH deep decarburization capability is improved, and the end point carbon content is reduced by 1-10 multiplied by 10-6。
Furthermore, the generated carbon monoxide bubbles have small size and strong inclusion capturing capability, and can obviously promote the aggregation and growth of the inclusions on the surfaces of the bubbles; meanwhile, during RH decarburization, molten steel has strong stirring capability and Al2O3Good effect of removing the impurities, and both are beneficial to the Al generated in advance2O3The inclusion is removed, and the molten steel is not polluted.
The invention has the beneficial technical effects
Before or during RH decarburization, aluminum or aluminum alloy is added into the molten steel, and aluminum oxygen reaction is utilized to form dispersed Al in the molten steel2O3The inclusion promotes nucleation of the carbon monoxide bubbles, increases the nucleation depth of the carbon monoxide bubbles in the molten steel, enlarges the reaction layer thickness of carbon-oxygen reaction in the RH vacuum tank and promotes decarburization of the molten steel. Meanwhile, the generated carbon monoxide bubbles have small size and strong capability of capturing impurities, can obviously promote the aggregation and growth of the impurities on the surfaces of the bubbles, and is beneficial to the Al generated in advance2O3The inclusion is removed, and the molten steel is not polluted. The method can improve the RH decarburization rate and reduce the end point carbon content by 1-10 multiplied by 10-6。
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FIG. 1 is a schematic view of the present invention for promoting RH decarburization.
Detailed Description
For clearly illustrating the objects, technical solutions and advantages of the present invention, the present invention will be described in further detail with reference to examples below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
A method of promoting RH decarburization prior to or during RH decarburizationAdding aluminum or aluminum alloy into the molten steel, and forming dispersed Al in the molten steel by utilizing the aluminum-oxygen reaction2O3Inclusions, Al produced2O3The inclusion has poor wettability and large wetting angle with the molten steel, becomes a heterogeneous nucleation core for generating carbon monoxide bubbles through RH decarburization reaction, promotes the nucleation of the carbon monoxide bubbles, increases the nucleation depth of the carbon monoxide bubbles in the molten steel, enlarges the thickness of a reaction layer of the carbon-oxygen reaction in an RH vacuum tank, and improves the RH deep decarburization capability.
The relation between the total aluminum content (WAl) (kg) added into the aluminum or aluminum alloy during the tapping process of the converter and the molten steel quality (WSTEEL) (t) is as follows:
w is more than or equal to 0.225w and less than or equal to 1.125w
The relationship between the total amount of aluminum added to the aluminum or aluminum alloy before RH treatment, wAl (kg), and the mass of molten steel, wSteel (t), is:
0.1575w [ steel ] or more and w [ Al ] or less 0.9w [ steel ]
In the earlier stage of RH vacuum treatment, the relation between the total aluminum content (wAl (kg)) added into aluminum or aluminum alloy in molten steel in a vacuum tank from a stock bin above the vacuum tank and the molten steel mass (wSteel (t)) is as follows:
0.1125w [ steel ] less than or equal to w [ Al ] less than or equal to 0.45w [ steel ]
To meet the oxygen content of the molten steel required for the aluminum oxidation reaction and the carbon oxygen reaction, when aluminum or an aluminum alloy is added to the molten steel before RH decarburization, for example, the oxygen mass concentration C in the steel at the start of RH decarburization[O]Less than 250X 10-6+1.5C[C](C[C]Carbon mass concentration in steel), after the RH vacuum degree is reduced to less than 10000-5000Pa, blowing oxygen into the steel by using a top lance, wherein the oxygen blowing flow is controlled in a small flow range, and the specific flow is as follows: the oxygen blowing flow of the ladle is controlled to be less than or equal to 180t and is controlled to be 600-1200 m3H; more than 180t of steel ladle, the oxygen blowing flow is more than or equal to 1000-2000 m3H is used as the reference value. Total oxygen blowing amount Nm in RH process3Controlled to be {350w [ steel ]]×[(1.2～1.3)(1.4C[C]+250×10-6)-C[O]]}。
When aluminum and aluminum alloy are added into molten steel in the vacuum tank from a storage bin above the vacuum tank in the early stage of RH refining, such as the mass concentration C of oxygen in steel at the beginning of RH decarburization[O]Less than 250X 10-6+1.5C[C]+0.00113w[Al]Steel/w]When adding aluminum and aluminum alloy, the large-size Al is promoted by adopting top lance to blow oxygen at large flow rate2O3The formation of the inclusion is more beneficial to the inclusion to become the nucleus of the carbon monoxide bubble, and the specific oxygen blowing flow is as follows: the oxygen blowing flow of the ladle is less than or equal to 180t, and is more than or equal to 1200-2000 m3H; more than 180t of steel ladle, the oxygen blowing flow is more than or equal to 2000-3500 m3H is used as the reference value. After the large-flow oxygen blowing is carried out for 1min, the small-flow oxygen blowing is changed, and the specific oxygen blowing flow is as follows: the oxygen blowing flow of the ladle is controlled to be less than or equal to 180t and is controlled to be 600-1200 m3H; more than 180t of steel ladle, the oxygen blowing flow is more than or equal to 1000-2000 m3H is used as the reference value. The total oxygen blowing amount is controlled to be {350w [ steel ]]×[(1.2～1.3)(1.4C[C]+250×10-6+0.00113w[Al]Steel/w])-C[O]]}。
Al produced by the above method in RH decarburization2O3The inclusions become heterogeneous nucleation cores for generating carbon monoxide bubbles through carbon-oxygen reaction, the generation and decarburization reaction of the carbon monoxide bubbles are promoted, the decarburization reaction kinetic constant is remarkably improved, the RH deep decarburization capability is improved, and the end point carbon content is reduced by 1-10 multiplied by 10-6. Meanwhile, the generated carbon monoxide bubbles have small size and strong capability of capturing impurities, can obviously promote the aggregation and growth of the impurities on the surfaces of the bubbles, and is beneficial to the Al generated in advance2O3The inclusion is removed, and the molten steel is not polluted.
Examples 1
The IF steel is produced by adopting a BOF-LF-RH-CC process flow, and the capacity of the converter is 300 t. The converter end point oxygen content is 612X 10-6Then the steel ladle is transported to an RH station, and the mass concentration of carbon in the steel is measured to be 300 multiplied by 10-6. When the technology is not adopted, after RH vacuum decarburization is carried out for 15min, the mass concentration of carbon in steel is measured to be 16 multiplied by 10-6。
When the technology is adopted, the content of dissolved oxygen in the steel before the aluminum particles are added is 612 multiplied by 10-6. Adding aluminum particles into steel in the tapping process, wherein the adding amount is 210kg, operating a ladle to an RH station, and measuring the mass concentration of oxygen in the steel before RH vacuum treatment to be 300 multiplied by 10-6The carbon mass concentration is 300X 10-6. Starting RH refining, vacuumizing for 2min, reducing the pressure in the vacuum tank to 8000Pa, and blowing oxygen into the molten steel by a top lance with the flow rate of 1500m3H, oxygen blowing time of 2.4min and total oxygen blowing amount of 60Nm3. After RH vacuum decarburization for 15min, the mass concentration of carbon in the steel is measured to be 12 multiplied by 10-6Al in steel2O3The inclusions are substantially removed.
EXAMPLES example 2
The IF steel is produced by adopting a BOF-LF-RH-CC process flow, and the capacity of a converter is 120 t. After tapping of the converter, the steel ladle is operated to an RH station, and the content of dissolved oxygen in the steel is measured to be 485 multiplied by 10-6The carbon mass concentration is 250X 10-6. When the technology is not adopted, after 10min of RH vacuum decarburization, the mass concentration of carbon in steel is measured to be 15 multiplied by 10-6。
When the technology is adopted, aluminum particles are added into the steel before RH treatment, the adding amount is 44kg, and the content of dissolved oxygen in the steel before the aluminum particles are added is 485 multiplied by 10-6. Determination of oxygen mass concentration in Steel before RH vacuum treatment 321X 10-6The carbon mass concentration is 250X 10-6. Starting RH refining, vacuumizing for 2min, reducing the pressure in the vacuum tank to 7500Pa, blowing oxygen into the molten steel by a top lance with the flow of 800m3H, oxygen blowing time of 1.4min, total oxygen blowing amount of 19Nm3. After 10min of RH vacuum decarburization, the mass concentration of carbon in the steel is measured to be 10 multiplied by 10-6Al in steel2O3The inclusions are substantially removed.
EXAMPLE 3
DX56D + Z steel is produced by adopting a BOF-LF-RH-CC process flow, and the capacity of a converter is 150 t. After tapping, the ladle is transferred to an RH station, and the content of dissolved oxygen in the steel is measured to be 680 multiplied by 10-6The carbon content concentration was 400X 10-6. When the technology is not adopted, after RH vacuum decarburization is carried out for 14min, the mass concentration of carbon in steel is measured to be 12 multiplied by 10-6。
When the technology is adopted, aluminum particles are added into the steel in the early stage of RH vacuum treatment, the adding amount is 54kg, and the content of dissolved oxygen in the steel before the aluminum particles are added is 680 multiplied by 10-6. The mass concentration of oxygen in the steel is measured to be 520 multiplied by 10 after the aluminum particles are added-6The carbon content concentration was 400X 10-6. Starting RH refining, vacuumizing for 2min, reducing the pressure in the vacuum tank to 8600Pa, blowing large-flow oxygen into molten steel by a top lance, wherein the flow of the top-blown oxygen is 1800m3H, the oxygen blowing time is 1 min; then the oxygen blowing flow is reduced to 800m3The oxygen blowing time is 2min, and the total oxygen blowing amount is 56.7Nm3. After RH vacuum decarburization for 14min, the mass concentration of carbon in the steel is measured to be 8 multiplied by 10-6Al in steel2O3The inclusions are substantially removed.
EXAMPLE 4
50W800 steel is produced by adopting a BOF-LF-RH-CC process flow, and the capacity of the converter is 210 t. After tapping of the converter, the ladle is operated to an RH station, and the content of dissolved oxygen in the steel is measured to be 689 multiplied by 10-6The carbon mass concentration was 240X 10-6. When the technology is not adopted, the mass concentration of carbon in steel is measured to be 32 multiplied by 10 after RH vacuum decarburization is carried out for 12min-6。
When the technology is adopted, aluminum particles are added into steel before RH treatment, the adding amount is 37kg, and the content of dissolved oxygen in the steel before the aluminum particles are added is 689 multiplied by 10-6. Oxygen mass concentration in steel measured before RH vacuum treatment 612X 10-6The carbon mass concentration was 240X 10-6. After which the vacuum treatment is started, during which there is no need to blow oxygen into the liquid steel. After RH vacuum decarburization for 12min, the mass concentration of carbon in the steel is measured to be 26 multiplied by 10-6Al in steel2O3The inclusions are substantially removed.
EXAMPLE 5
The IF steel is produced by adopting a BOF-LF-RH-CC process flow, and the capacity of the converter is 240 t. Determination of the dissolved oxygen content in the steel before tapping in a converter at 692X 10-6Then the steel ladle is transported to an RH station, and the mass concentration of carbon in the steel is measured to be 230 multiplied by 10-6. When the technology is not adopted, after RH vacuum decarburization is carried out for 14min, the mass concentration of carbon in steel is measured to be 15 multiplied by 10-6。
When the technology is adopted, aluminum particles are added into the steel in the tapping process, the adding amount is 55kg, and the content of dissolved oxygen in the steel before the aluminum particles are added is 698 multiplied by 10-6. After adding aluminum particles, the mass concentration of oxygen in steel is measured to be 596 multiplied by 10-6The carbon content concentration is 230X 10-6. Thereafter, vacuum is startedAnd (4) treating, wherein oxygen does not need to be blown into the molten steel in the period. After RH vacuum decarburization for 14min, the mass concentration of carbon in the steel is measured to be 12 multiplied by 10-6Al in steel2O3The inclusions are substantially removed.
EXAMPLE 6
The IF steel is produced by adopting a BOF-LF-RH-CC process flow, and the capacity of the converter is 180 t. After tapping, the ladle was moved to the RH station and the content of dissolved oxygen in the steel was determined to be 683X 10-6The carbon mass concentration was 240X 10-6. When the technology is not adopted, the mass concentration of carbon in steel is measured to be 13 multiplied by 10 after RH vacuum decarburization for 13min-6。
When the technology is adopted, aluminum particles are added into steel before RH treatment, the adding amount is 29kg, and the dissolved oxygen content in the steel before the aluminum particles are added is 683 multiplied by 10-6. The oxygen mass concentration in the steel measured before RH vacuum treatment was 611X 10-6The carbon mass concentration was 240X 10-6. After which the vacuum treatment is started, during which there is no need to blow oxygen into the liquid steel. After RH vacuum decarburization for 13min, the mass concentration of carbon in the steel is measured to be 8 multiplied by 10-6Al in steel2O3The inclusions are substantially removed.
EXAMPLES example 7
50W800 steel is produced by adopting a BOF-LF-RH-CC process flow, and the capacity of the converter is 300 t. The steel ladle is operated to an RH station after the tapping of the converter, and the content of dissolved oxygen in the steel is measured to be 629 multiplied by 10-6The carbon content concentration was 420X 10-6. When the technology is not adopted, the mass concentration of carbon in steel is measured to be 28 multiplied by 10 after RH vacuum decarburization for 16min-6。
When the technology is adopted, the aluminum particles are added into the steel in the early stage of RH vacuum treatment, the adding amount is 134kg, and the dissolved oxygen content in the steel before the aluminum particles are added is 629 multiplied by 10-6. The mass concentration of oxygen in the steel is determined to be 431 multiplied by 10 after the aluminum particles are added-6The carbon content concentration was 420X 10-6. Starting RH refining, vacuumizing for 2min, reducing pressure in vacuum tank to 6200Pa, and blowing large flow of oxygen into molten steel by using top lance at flow rate of 3000m3H, the oxygen blowing time is 1 min; then the oxygen is blown with small flow, and the flow of top blown oxygen is 1500m3H, oxygen blowing time of 3.5min and total oxygen blowing amount of 138Nm3. After RH vacuum decarburization for 16min, the mass concentration of carbon in the steel is measured to be 20 multiplied by 10-6Al in steel2O3The inclusions are substantially removed.
EXAMPLES example 8
The IF steel is produced by adopting a BOF-LF-RH-CC process flow, and the capacity of the converter is 300 t. After tapping of the converter, the ladle is operated to an RH station, and the content of dissolved oxygen in the steel is measured to be 483 multiplied by 10-6The carbon content concentration was 400X 10-6. When the technology is not adopted, after RH vacuum decarburization is carried out for 13min, the mass concentration of carbon in steel is measured to be 14 multiplied by 10-6。
When the technology is adopted, aluminum particles are added into steel before RH treatment, the adding amount is 61kg, and the content of dissolved oxygen in the steel before the aluminum particles are added is 483 multiplied by 10-6. Oxygen mass concentration in steel measured before RH vacuum treatment was 392X 10-6The carbon content concentration was 400X 10-6. Starting RH refining, vacuumizing for 2min, reducing pressure in vacuum tank to 8200Pa, blowing oxygen into molten steel by top lance with flow rate of 1800m3H, oxygen blowing time of 2.1min, total oxygen blowing amount of 63Nm3. After RH vacuum decarburization for 13min, the mass concentration of carbon in steel is measured to be 7 multiplied by 10-6Al in steel2O3The inclusions are substantially removed.
EXAMPLES example 9
DX56D + Z steel is produced by adopting a BOF-LF-RH-CC process flow, and the capacity of a converter is 180 t. The content of dissolved oxygen in steel is 536X 10 after converter tapping-6Then the steel ladle is transported to an RH station, and the mass concentration of carbon in the steel is measured to be 350 multiplied by 10-6. When the technology is not adopted, the mass concentration of carbon in steel is measured to be 18 multiplied by 10 after RH vacuum decarburization is carried out for 15min-6。
When the technology is adopted, aluminum particles are added into steel in the tapping process, the adding amount is 54kg, and the content of dissolved oxygen in the steel before the aluminum particles are added is 536 multiplied by 10-6. The steel ladle is transported to an RH station, and the mass concentration of oxygen in the steel is measured to be 269 multiplied by 10-6The carbon content concentration was 350X 10-6. Starting RH refining, vacuumizing for 2min, reducing pressure in vacuum tank to 6300Pa, blowing oxygen into molten steel by top lance with top blowing oxygen flow of 1200m3H, blowingThe oxygen time is 2min, and the total oxygen blowing amount is 40Nm3. After RH vacuum decarburization for 15min, the mass concentration of carbon in the steel is measured to be 9 multiplied by 10-6Al in steel2O3The inclusions are substantially removed.
The above examples show that the method for promoting RH decarburization can achieve the expected effect, and a proper scheme can be determined by adjusting parameters such as initial steel liquid oxygen content, added aluminum amount, top-blown oxygen flow and the like according to the end point carbon content requirement. It will be appreciated by those skilled in the art that the above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the invention, and that changes may be made in the above embodiments by those skilled in the art without departing from the spirit and scope of the invention. Therefore, variations and modifications of the above-described embodiments are intended to fall within the scope of the claims of the present invention.

Claims (1)

1. A method for promoting RH decarburization comprises adding aluminum or aluminum alloy into molten steel before or during RH decarburization to form dispersed Al in the molten steel by aluminum-oxygen reaction2O3Inclusions, Al produced2O3The inclusion has poor wettability and large wetting angle with the molten steel, becomes a heterogeneous nucleation core for generating carbon monoxide bubbles through RH decarburization reaction, promotes nucleation of the carbon monoxide bubbles, increases the nucleation depth of the carbon monoxide bubbles in the molten steel, enlarges the thickness of a reaction layer of carbon-oxygen reaction in an RH vacuum tank, and improves the RH deep decarburization capability; the generated carbon monoxide bubbles have small size and strong capability of capturing impurities, can obviously promote the aggregation and growth of the impurities on the surfaces of the bubbles, and is beneficial to the Al generated earlier2O3The impurities are removed, and the molten steel is not polluted;
al formed during RH decarburization2O3The inclusions become heterogeneous nucleation cores for generating carbon monoxide bubbles through carbon-oxygen reaction, the generation and decarburization reaction of the carbon monoxide bubbles are promoted, the decarburization reaction kinetic constant is remarkably improved, the RH deep decarburization capability is improved, and the end point carbon content is reduced by 1-10 multiplied by 10-6；
Adding aluminum and aluminum alloy into the molten steel in the tapping process of the converter, or adding aluminum and aluminum alloy into the molten steel before RH treatment, or adding aluminum and aluminum alloy into the molten steel in the vacuum tank from a bin above the vacuum tank in the early stage of RH treatment, wherein the added aluminum reacts with dissolved oxygen in the molten steel to generate Al in the molten steel2O3Impurities;
the relation between the total aluminum amount (WAl) kg added into aluminum or aluminum alloy in the converter tapping process and the molten steel mass (Wt) is as follows:
w is more than or equal to 0.225w and less than or equal to 1.125w
The relationship between the total aluminum content w [ Al ] kg added to the aluminum or aluminum alloy before RH treatment and the mass w [ steel ] t of the molten steel is:
0.1575w [ steel ] or more and w [ Al ] or less 0.9w [ steel ]
The relation between the total aluminum amount (WAl) kg of aluminum or aluminum alloy added into molten steel in the vacuum tank from a bin above the vacuum tank in the early stage of RH vacuum treatment and the molten steel mass (WSTE) t is as follows:
0.1125w [ steel ] is less than or equal to w [ Al ] is less than or equal to 0.45w [ steel ];
when aluminum or aluminum alloy is added to the molten steel before RH decarburization, the mass concentration C of oxygen in the steel at the start of RH decarburization[O]Less than 250X 10-6+1.5C[C]，C[C]For the carbon mass concentration in steel, utilize the top rifle to blow into oxygen in the steel in the initial stage of RH decarbonization, the flow control of blowing oxygen is the low flow range, and specific flow is: the oxygen blowing flow of the ladle is controlled to be less than or equal to 180t and is controlled to be 600-1200 m3H; the oxygen blowing flow of the steel ladle is 1000-2000 m and is larger than 180t3H; total oxygen blowing amount Nm in RH process3Controlled to be {350w [ steel ]]×[(1.2～1.3)(1.4C[C]+250×10-6)-C[O]]}；
When aluminum or aluminum alloy is added into molten steel in the vacuum tank from a bin above the vacuum tank in the early stage of RH refining, the mass concentration C of oxygen in the steel is at the beginning of RH decarburization[O]Less than 250X 10-6+1.5C[C]+0.00113w[Al]Steel/w]When adding aluminum or aluminum alloy, the large-flow oxygen blowing is carried out by adopting a top lance, so as to promote large-size Al2O3The formation of the inclusion is more beneficial to the inclusion to become the nucleation core of the carbon monoxide bubble; specific oxygen blastThe amount is: the flow of oxygen blowing is 1200-2000 m for a ladle with the flow of less than or equal to 180t3H; the oxygen blowing flow of the steel ladle is 2000-3500 m and is larger than 180t3H; after the large-flow oxygen blowing is carried out for 1min, the small-flow oxygen blowing is changed, and the specific oxygen blowing flow is as follows: the oxygen blowing flow of the ladle is controlled to be less than or equal to 180t and is controlled to be 600-1200 m3H; the oxygen blowing flow of the steel ladle is 1000-2000 m and is larger than 180t3H; the total oxygen blowing amount is controlled to be {350w [ steel ]]×[(1.2～1.3)(1.4C[C]+250×10-6+0.00113w[Al]Steel/w])-C[O]]}。
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