CN111500825A - Method for controlling titanium content behind steelmaking converter - Google Patents

Method for controlling titanium content behind steelmaking converter Download PDF

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Publication number
CN111500825A
CN111500825A CN202010501125.8A CN202010501125A CN111500825A CN 111500825 A CN111500825 A CN 111500825A CN 202010501125 A CN202010501125 A CN 202010501125A CN 111500825 A CN111500825 A CN 111500825A
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China
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molten steel
covering agent
tundish
mass
ladle
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CN202010501125.8A
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CN111500825B (en
Inventor
孙亮
刘珍童
刘风刚
赵艳宇
成天兵
朱良
毕泽阳
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Beijing Shougang Co Ltd
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Beijing Shougang Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/076—Use of slags or fluxes as treating agents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10—Supplying or treating molten metal
    • B22D11/108—Feeding additives, powders, or the like
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10—Supplying or treating molten metal
    • B22D11/11—Treating the molten metal
    • B22D11/111—Treating the molten metal by using protecting powders
    • 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
    • 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
    • C21C7/072—Treatment with gases
    • 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
    • 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

Abstract

The invention belongs to the technical field of steel making, and particularly relates to a method for controlling titanium content behind a steel-making converter, which comprises the following steps: carrying out top slag modification on a ladle behind the furnace to obtain molten steel with modified top slag; sequentially carrying out RH refining and continuous casting on the molten steel modified by the top slag; the molten steel in the ladle after the furnace comprises the following components in percentage by mass: ti is less than 0.01 percent; the method for modifying the top slag of the ladle after the furnace comprises the following steps: in the tapping process, fluorite, lime and light-burned dolomite are added into a ladle behind the furnace; the mass ratio of the fluorite to the lime to the light-burned dolomite is (0.5-1.5) to (2-5) to (3-8); the RH refining comprises RH decarburization, deoxidation alloying and RH pure circulation. According to the method, each process is optimized and controlled, so that the steel plate blank with low titanium content and various corresponding products thereof are obtained, and the average titanium content is controlled within 0.0010-0.0015%.

Description

Method for controlling titanium content behind steelmaking converter
Technical Field
The invention belongs to the technical field of steel making, and particularly relates to a method for controlling titanium content behind a steel-making converter.
Background
In the field of steel making, titanium element is added as an alloy element to most steel grades. However, in a small part of steel grades (such as silicon steel), titanium element becomes a harmful element, and the existence of titanium element can affect the fatigue performance and electromagnetic performance of the steel grade. Generally, for steel grades such as silicon steel, the titanium content cannot exceed 0.0020%.
At present, no method for effectively and stably controlling the titanium content after the converter of the steel-making converter exists.
Disclosure of Invention
In view of the above problems, the present invention provides a method for controlling titanium content after a steelmaking converter. According to the method, a series of processes of ladle after furnace, top slag modification, RH decarburization, deoxidation alloying, RH pure circulation and continuous casting treatment are selected, and the processes are optimized and controlled, so that the steel plate blank with low titanium content and various corresponding products are obtained, and the average titanium content is controlled within 0.0010-0.0015%.
The technical scheme of the invention for realizing the purpose is as follows:
the invention provides a method for controlling titanium content after a steelmaking converter, which comprises the following steps: carrying out top slag modification on a ladle behind the furnace to obtain molten steel with modified top slag; sequentially carrying out RH refining and continuous casting on the molten steel modified by the top slag;
wherein, the molten steel in the ladle after the furnace comprises the following components in percentage by mass: ti is less than 0.01 percent;
the method for modifying the top slag of the ladle after the furnace comprises the following steps: in the tapping process, fluorite, lime and light-burned dolomite are added into a ladle behind the furnace;
the mass ratio of the fluorite to the lime to the light-burned dolomite is (0.5-1.5) to (2-5) to (3-8);
the RH refining comprises RH decarburization, deoxidation alloying and RH pure circulation.
In one embodiment, in the method for controlling the titanium content after the steelmaking converter, the mass ratio of the fluorite to the lime to the light-burned dolomite is 0.8:3.5: 3.6;
in a preferred embodiment, in the method for controlling the titanium content after the converter of the steelmaking converter, the mass ratio of the fluorite, the lime, the light-burned dolomite and the molten steel in the ladle after the converter is (0.5-1.5) kg, 2-5) kg, 3-8 kg, 2.2-2.3 t;
in a preferred embodiment, in the method for controlling the titanium content after the converter of the steelmaking converter, the mass ratio of the fluorite, the lime, the light-burned dolomite and the molten steel in the ladle after the converter is 0.8kg to 3.5kg to 3.6kg to 2.2 t.
In one embodiment, in the method for controlling the content of titanium after the converter of the steelmaking converter, during the top slag modification of the ladle after the converter, the bottom blowing flow of the ladle is 280-350L/min;
the molten steel after the top slag modification comprises the following components in percentage by mass: 0.00015 to 0.0002% of Ti.
In one embodiment, the method for controlling titanium content after steelmaking converter according to the present invention, the ladle after the converter includes: the grade of the steel returns to the ladle or the non-grade of the steel returns to the ladle;
in a preferred embodiment, in the method for controlling the titanium content after the steelmaking converter of the invention, the steel grade returning ladle is a silicon steel returning ladle;
in a preferred embodiment, in the method for controlling the titanium content after the converter of the steelmaking converter, the molten steel in the ladle after the converter comprises the following components in percentage by mass: ti is less than 0.002%;
in a preferred embodiment, in the method for controlling the titanium content after the steelmaking converter, the molten steel temperature is 1580-1610 ℃ in the RH decarburization process;
when the RH decarburization is finished, the content of C in the molten steel is less than or equal to 0.003 percent by mass percent;
in a preferred embodiment, in the method for controlling the content of titanium after the steelmaking converter furnace, the deoxidation alloying comprises a first low-carbon ferrosilicon deoxidation alloying and a second aluminum deoxidation alloying which are sequentially carried out (wherein, aluminum particles and tin particles are adopted, or aluminum particles and copper particles are adopted); the interval time between the first low-carbon ferrosilicon deoxidation alloying and the second aluminum deoxidation alloying is 2-3 min; the RH pure cycle time is 7-8 min;
wherein, the first time of low carbon ferrosilicon deoxidation alloying comprises: adding low-carbon ferrosilicon into the molten steel subjected to RH decarburization; the mass ratio of the low-carbon ferrosilicon to the molten steel after RH decarburization is (40-55) kg (0.9-1.1) t; preferably 48kg to 1 t;
the second aluminum deoxidation alloying comprises the following steps: adding aluminum particles and tin particles into the molten steel after the first deoxidation alloying of the low-carbon ferrosilicon is completed, or adding aluminum particles and copper particles into the molten steel after the first deoxidation alloying of the low-carbon ferrosilicon is completed;
wherein the mass ratio of the aluminum particles to the molten steel after the first low-carbon ferrosilicon deoxidation alloying is (4-14) kg, (0.9-1.1) t; preferably 9.5kg:1 t;
the mass ratio of the tin particles to the molten steel after the first low-carbon ferrosilicon deoxidation alloying is (0-0.1) kg and (0.9-1.1) t; preferably 0.05kg:1 t;
the mass ratio of the copper particles to the molten steel after the first low-carbon ferrosilicon deoxidation alloying is (0-0.1) kg and (0.9-1.1) t; preferably 0.03kg:1 t.
In one embodiment, in the method for controlling the content of titanium after the steelmaking converter according to the present invention, the low-carbon silicon-iron comprises, by mass: 76-79% of Si and less than or equal to 0.01% of Ti;
in the low-carbon ferrosilicon, the mass percentage of particles with the particle size of 10-50 mm is more than or equal to 90 percent, the mass percentage of particles with the particle size of less than 10mm is less than or equal to 5 percent, and the mass percentage of particles with the particle size of more than 10mm is less than or equal to 5 percent;
in a preferred embodiment, in the method for controlling the titanium content after the steelmaking converter according to the present invention, the aluminum particles comprise, by mass: more than or equal to 99.95 percent of Al and less than or equal to 0.01 percent of Ti; the particle size of the aluminum particles is 3-20 mm;
in a preferred embodiment, in the method for controlling the titanium content after the steelmaking converter according to the present invention, the copper particles comprise, by mass: cu is more than or equal to 99.95 percent, and Ti is less than or equal to 0.01 percent; the particle size of the copper particles is 40-50 mm;
in a preferred embodiment, in the method for controlling the titanium content after the steelmaking converter, the tin particles comprise, by mass, more than or equal to 99.90% of Sn and less than or equal to 0.01% of Ti, and the size of the tin particles is less than or equal to 70mm × 60mm, × 50 mm.
In one embodiment, in the method for controlling titanium content after a steelmaking converter according to the present invention, after the RH refining is completed, the molten steel after the RH refining includes, by mass: 0.0012-0.0013% of Ti;
in a preferred embodiment, in the method for controlling the content of titanium after a steelmaking converter according to the present invention, after the RH refining is completed, the increase of Ti in molten steel during the RH refining (i.e., the increase of Ti in molten steel during the RH refining compared to molten steel after the top dross modification) is 0.00105 to 0.0011% by mass;
in a preferred embodiment, in the method for controlling the content of titanium after the converter of the steelmaking converter, in the RH refining process, when the ladle after the converter is a non-parent steel type and returns to the ladle, the RH refining furnace is rinsed; wherein, in the rinsing furnace water adopted by rinsing furnace treatment, the Ti is less than or equal to 0.0002 percent by mass percent.
In one embodiment, in the method for controlling titanium content after steelmaking converter according to the present invention, the continuous casting includes: pouring the molten steel refined by RH into a tundish to obtain molten steel of the tundish; covering the liquid level of the molten steel in the tundish by using a double-layer covering agent, and carrying out continuous casting;
the double-layer covering agent comprises an upper-layer covering agent and a lower-layer covering agent, the lower-layer covering agent is in contact with molten steel of the tundish, and the upper-layer covering agent is positioned above the lower-layer covering agent;
the upper covering agent comprises the following components in percentage by mass: SiO 2242～62％，CaO≤10％， Ti 1.8％，Fe2O3≤15％，Al2O38～18％，C≤1％，MgO 2～10％；
The lower layer covering agent comprises the following components in percentage by mass: SiO 2245～55％，CaO 38～48％， Ti≤0.15％，Fe2O3≤3％，Al2O3≤3％，C≤1％，MgO≤3％；
In a preferred embodiment, in the method for controlling the titanium content after the steelmaking converter, the upper covering agent comprises the following components in percentage by mass: SiO 2252％，CaO 5％，Ti 1.8％， Fe2O310％，Al2O312％，C≤1％，MgO 5％；
The lower layer covering agent comprises the following components in percentage by mass: SiO 2247％，CaO 40％，Ti 0.15％， Fe2O32％，Al2O31％，C≤1％，MgO 1％。
In a preferred embodiment, in the method for controlling the titanium content after the steelmaking converter of the invention, the SiO is2One or two selected from expanded perlite or vermiculite; the CaO is selected from one or two of quicklime or dolomite; the Al is2O3Is calcium aluminate.
In one embodiment, in the method for controlling the titanium content after the steelmaking converter is used, the mass ratio of the double-layer covering agent to the molten steel in the tundish is (0.55-0.70) kg (0.9-1.1) t; the mass ratio of the upper covering agent to the lower covering agent is (7-7.5) to (2.5-3);
in a preferred embodiment, in the method for controlling the titanium content after the steelmaking converter furnace, the method for covering the liquid level of the molten steel in the tundish by using the double-layer covering agent comprises the following steps: when the quality of the molten steel of the tundish reaches 1/9 of the normal casting quality, adding a lower covering agent, wherein the mass ratio of the lower covering agent to the molten steel of the tundish is (66-77) kg, (21-22) t; when the quality of the molten steel of the tundish reaches 2/9-2/3 of the normal casting quality, adding a lower covering agent, wherein the mass ratio of the lower covering agent to the molten steel of the tundish is (6-7) kg, (21-22) t; when the quality of the tundish molten steel reaches the normal casting quality, adding an upper covering agent, wherein the mass ratio of the upper covering agent to the tundish molten steel is (6-7) kg, (21-22) t;
in a preferred embodiment, in the method for controlling the titanium content after the steelmaking converter furnace, the method for covering the liquid level of the molten steel in the tundish by using the double-layer covering agent comprises the following steps: when the quality of the molten steel of the tundish reaches 1/9 of the normal casting quality, respectively adding a lower covering agent into temperature measurement sampling holes at two sides of the tundish and rod dropping holes, wherein the mass ratio of the lower covering agent to the molten steel of the tundish is (66-77) kg, (21-22) t; when the quality of the molten steel of the tundish reaches 2/9-2/3 of the normal casting quality, adding a lower covering agent into a large ladle casing pipe hole of the tundish, wherein the mass ratio of the lower covering agent to the molten steel of the tundish is (6-7) kg, (21-22) t; when the quality of the tundish molten steel reaches the normal casting quality, adding an upper covering agent, wherein the mass ratio of the upper covering agent to the tundish molten steel is (6-7) kg, (21-22) t;
in a preferred embodiment, in the method for controlling the titanium content after the steelmaking converter, when the molten steel in the tundish is exposed or turned over, the covering agent at the lower layer is added, and then the covering agent at the upper layer is added.
In one embodiment, in the method for controlling titanium content after a steelmaking converter according to the present invention, the steel slab obtained after the continuous casting includes, by mass: 0.0010-0.0015% of Ti;
in a preferred embodiment, in the method for controlling the content of titanium after the steelmaking converter according to the present invention, the increase of Ti in the steel slab during the continuous casting process is 0.00015 to 0.0002% by mass.
One or more technical embodiments of the present invention have at least the following technical effects or advantages:
(1) the invention selects the ladle after the furnace according to the purpose of the invention. The main idea is as follows: as steel slag inevitably adheres to the ladle at the slag line part and the ladle wall after the furnace, the steel slag contains more TiO2Which can cause TiO in the steel slag when in subsequent smelting of high-silicon and high-aluminum steel grades2Is reduced and enters into the molten steel, thereby causing the titanium increase phenomenon of the molten steel. In particular, two or more successive passes of the same steel type are carried out on the production structure, so that the molten steel which is then smelted can be used for the TiO front2The low-content ladle can further reduce the titanium increase phenomenon of molten steel. In addition, it is also possible to select ladles for steel grades that do not have a requirement for titanium content (i.e. ladles without added titanium-containing alloy). The molten steel in the ladle after the furnace selected by the invention contains Ti less than 0.01 percent, preferably Ti less than 0.002 percent, so that the phenomenon of 'titanium return' in the subsequent process caused by ladle slag can be reduced to the greatest extent;
(2) and carrying out top slag modification on the ladle after the furnace, adding fluorite, lime and light-burned dolomite into the ladle after the furnace in the tapping process, and limiting the mass ratio of the fluorite, the lime and the light-burned dolomite to be (0.5-1.5) to (2-5) to (3-8). In the process, fluorite is added to ensure that top slag materials are completely melted; the addition of lime is used for adjusting the top slag component and can dilute TiO in the top slag of the steel ladle2The inclusion in the molten steel is adsorbed while the content is maintained; the light-burned dolomite is added for thickening the ladle top slag in the subsequent RH refining treatment process, so that the titanium return phenomenon of the ladle top slag can be reduced under the condition that a large amount of ferrosilicon, aluminum particles and the like are added in the subsequent RH refining. The method aims at the modification of the top slag of the ladle after the furnace, so that the top slag of the ladle is thickened more effectively, the slag steel reaction is prevented, and the subsequent titanium return phenomenon is reduced efficiently;
(3) in the invention, a series of process designs are carried out aiming at the deoxidation alloying process, and the aim is to ensure that the titanium increase phenomenon of molten steel caused by adding alloy is reduced; in addition, the grain size and the size of the low-carbon ferrosilicon, the aluminum grains, the tin grains and the like are limited, so that the alloy melting effect and the alloy yield are greatly improved;
(4) in the deoxidation alloying process, the prior art generally adopts aluminum particle deoxidation, which is a strong deoxidation process, and the deoxidation and alloying aluminum particles are mainly added into the steel ladle in 2-3 batches, wherein the adding amount is 4-14Kg/t, so the operation can cause partial ladle top slag entering RH vacuum and TiO in steel slag in the steel ladle2Is reduced, thereby causing the titanium return phenomenon of the molten steel; the process adopted by the invention is to add the low-titanium ferrosilicon for weak deoxidation, so that adverse factors aiming at controlling the titanium content caused by strong deoxidation can be reduced; after the weak deoxidation, the aluminum particles, the tin particles and the like are adopted for alloying treatment, thereby further effectively reducing the titanium return phenomenon of the molten steel.
(5) In the prior art, a single-layer covering agent is usually adopted, the Ti content is less than or equal to 1.2 percent, the price is relatively low, but the titanium increase phenomenon in molten steel of 1-3 furnaces before casting is serious due to the adoption of the single-layer covering agent because the molten steel for casting is high-silicon and high-aluminum; the invention adopts the double-layer covering agent to cover the liquid level of the molten steel in the tundish, and correspondingly limits each component and the content of the double-layer covering agent, thereby further reducing the titanium increase of the molten steel in the molten steel casting process and controlling the average titanium content of a final product within 0.0010-0.0015%.
Detailed Description
The present invention will be described in detail below with reference to specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly apparent therefrom. It will be understood by those skilled in the art that these specific embodiments and examples are for the purpose of illustrating the invention and are not to be construed as limiting the invention.
Throughout the specification, unless otherwise specifically noted, terms used herein should be understood as having meanings as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. If there is a conflict, the present specification will control.
Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.
In order to solve the technical problems, the embodiment of the invention provides the following general ideas:
the invention provides a method for controlling titanium content after a steelmaking converter, which comprises the following steps: carrying out top slag modification on a ladle behind the furnace to obtain molten steel with modified top slag; sequentially carrying out RH refining and continuous casting on the molten steel modified by the top slag;
wherein, the molten steel in the ladle after the furnace comprises the following components in percentage by mass: ti is less than 0.01 percent;
the method for modifying the top slag of the ladle after the furnace comprises the following steps: in the tapping process, fluorite, lime and light-burned dolomite are added into a ladle behind the furnace;
the mass ratio of the fluorite to the lime to the light-burned dolomite is (0.5-1.5) to (2-5) to (3-8);
the RH refining comprises RH decarburization, deoxidation alloying and RH pure circulation.
In one embodiment, in the method for controlling the titanium content after the steelmaking converter, the mass ratio of the fluorite to the lime to the light-burned dolomite is 0.8:3.5: 3.6;
in a preferred embodiment, in the method for controlling the titanium content after the converter of the steelmaking converter, the mass ratio of the fluorite, the lime, the light-burned dolomite and the molten steel in the ladle after the converter is (0.5-1.5) kg, 2-5) kg, 3-8 kg, 2.2-2.3 t;
in a preferred embodiment, in the method for controlling the titanium content after the converter of the steelmaking converter, the mass ratio of the fluorite, the lime, the light-burned dolomite and the molten steel in the ladle after the converter is 0.8kg to 3.5kg to 3.6kg to 2.2 t.
In one embodiment, in the method for controlling the content of titanium after the converter of the steelmaking converter, during the top slag modification of the ladle after the converter, the bottom blowing flow of the ladle is 280-350L/min;
the molten steel after the top slag modification comprises the following components in percentage by mass: 0.00015 to 0.0002% of Ti.
In one embodiment, the method for controlling titanium content after steelmaking converter according to the present invention, the ladle after the converter includes: the grade of the steel returns to the ladle or the non-grade of the steel returns to the ladle;
in a preferred embodiment, in the method for controlling the titanium content after the steelmaking converter of the invention, the steel grade returning ladle is a silicon steel returning ladle;
in a preferred embodiment, in the method for controlling the titanium content after the converter of the steelmaking converter, the molten steel in the ladle after the converter comprises the following components in percentage by mass: ti is less than 0.002%;
in a preferred embodiment, in the method for controlling the titanium content after the steelmaking converter, the molten steel temperature is 1580-1610 ℃ in the RH decarburization process;
when the RH decarburization is finished, the content of C in the molten steel is less than or equal to 0.003 percent by mass percent;
in a preferred embodiment, in the method for controlling the content of titanium after the steelmaking converter furnace, the deoxidation alloying comprises a first low-carbon ferrosilicon deoxidation alloying and a second aluminum deoxidation alloying which are sequentially carried out (wherein, aluminum particles and tin particles are adopted, or aluminum particles and copper particles are adopted); the interval time between the first low-carbon ferrosilicon deoxidation alloying and the second aluminum deoxidation alloying is 2-3 min; the RH pure cycle time is 7-8 min;
wherein, the first time of low carbon ferrosilicon deoxidation alloying comprises: adding low-carbon ferrosilicon into the molten steel subjected to RH decarburization; the mass ratio of the low-carbon ferrosilicon to the molten steel after RH decarburization is (40-55) kg (0.9-1.1) t; preferably 48kg to 1 t;
the second aluminum deoxidation alloying comprises the following steps: adding aluminum particles and tin particles into the molten steel after the first deoxidation alloying of the low-carbon ferrosilicon is completed, or adding aluminum particles and copper particles into the molten steel after the first deoxidation alloying of the low-carbon ferrosilicon is completed;
wherein the mass ratio of the aluminum particles to the molten steel after the first low-carbon ferrosilicon deoxidation alloying is (4-14) kg, (0.9-1.1) t; preferably 9.5kg:1 t;
the mass ratio of the tin particles to the molten steel after the first low-carbon ferrosilicon deoxidation alloying is (0-0.1) kg and (0.9-1.1) t; preferably 0.05kg:1 t;
the mass ratio of the copper particles to the molten steel after the first low-carbon ferrosilicon deoxidation alloying is (0-0.1) kg and (0.9-1.1) t; preferably 0.03kg:1 t.
In one embodiment, in the method for controlling the content of titanium after the steelmaking converter according to the present invention, the low-carbon silicon-iron comprises, by mass: 76-79% of Si and less than or equal to 0.01% of Ti;
in the low-carbon ferrosilicon, the mass percentage of particles with the particle size of 10-50 mm is more than or equal to 90 percent, the mass percentage of particles with the particle size of less than 10mm is less than or equal to 5 percent, and the mass percentage of particles with the particle size of more than 10mm is less than or equal to 5 percent;
in a preferred embodiment, in the method for controlling the titanium content after the steelmaking converter according to the present invention, the aluminum particles comprise, by mass: more than or equal to 99.95 percent of Al and less than or equal to 0.01 percent of Ti; the particle size of the aluminum particles is 3-20 mm;
in a preferred embodiment, in the method for controlling the titanium content after the steelmaking converter according to the present invention, the copper particles comprise, by mass: cu is more than or equal to 99.95 percent, and Ti is less than or equal to 0.01 percent; the particle size of the copper particles is 40-50 mm;
in a preferred embodiment, in the method for controlling the titanium content after the steelmaking converter, the tin particles comprise, by mass, more than or equal to 99.90% of Sn and less than or equal to 0.01% of Ti, and the size of the tin particles is less than or equal to 70mm × 60mm, × 50 mm.
In one embodiment, in the method for controlling titanium content after a steelmaking converter according to the present invention, after the RH refining is completed, the molten steel after the RH refining includes, by mass: 0.0012-0.0013% of Ti;
in a preferred embodiment, in the method for controlling the content of titanium after a steelmaking converter according to the present invention, after the RH refining is completed, the increase of Ti in molten steel during the RH refining (i.e., the increase of Ti in molten steel during the RH refining compared to molten steel after the top dross modification) is 0.00105 to 0.0011% by mass;
in a preferred embodiment, in the method for controlling the content of titanium after the converter of the steelmaking converter, in the RH refining process, when the ladle after the converter is a non-parent steel type and returns to the ladle, the RH refining furnace is rinsed; wherein, in the rinsing furnace water adopted by rinsing furnace treatment, the Ti is less than or equal to 0.0002 percent by mass percent.
In one embodiment, in the method for controlling titanium content after steelmaking converter according to the present invention, the continuous casting includes: pouring the molten steel refined by RH into a tundish to obtain molten steel of the tundish; covering the liquid level of the molten steel in the tundish by using a double-layer covering agent, and carrying out continuous casting;
the double-layer covering agent comprises an upper-layer covering agent and a lower-layer covering agent, the lower-layer covering agent is in contact with molten steel of the tundish, and the upper-layer covering agent is positioned above the lower-layer covering agent;
the upper covering agent comprises the following components in percentage by mass: SiO 2242～62％，CaO≤10％， Ti 1.8％，Fe2O3≤15％，Al2O38～18％，C≤1％，MgO 2～10％；
The lower layer covering agent comprises the following components in percentage by mass: SiO 2245～55％，CaO 38～48％， Ti≤0.15％，Fe2O3≤3％，Al2O3≤3％，C≤1％，MgO≤3％；
In a preferred embodiment, in the method for controlling the titanium content after the steelmaking converter, the upper covering agent comprises the following components in percentage by mass: SiO 2252％，CaO 5％，Ti 1.8％，Fe2O310％，Al2O312％，C≤1％，MgO 5％；
According to mass percentThe lower layer covering agent comprises: SiO 2247％，CaO 40％，Ti 0.15％， Fe2O32％，Al2O31％，C≤1％，MgO 1％。
In a preferred embodiment, in the method for controlling the titanium content after the steelmaking converter of the invention, the SiO is2One or two selected from expanded perlite or vermiculite; the CaO is selected from one or two of quicklime or dolomite; the Al is2O3Is calcium aluminate.
In one embodiment, in the method for controlling the titanium content after the steelmaking converter is used, the mass ratio of the double-layer covering agent to the molten steel in the tundish is (0.55-0.70) kg (0.9-1.1) t; the mass ratio of the upper covering agent to the lower covering agent is (7-7.5) to (2.5-3);
in a preferred embodiment, in the method for controlling the titanium content after the steelmaking converter furnace, the method for covering the liquid level of the molten steel in the tundish by using the double-layer covering agent comprises the following steps: when the quality of the molten steel of the tundish reaches 1/9 of the normal casting quality, adding a lower covering agent, wherein the mass ratio of the lower covering agent to the molten steel of the tundish is (66-77) kg, (21-22) t; when the quality of the molten steel of the tundish reaches 2/9-2/3 of the normal casting quality, adding a lower covering agent, wherein the mass ratio of the lower covering agent to the molten steel of the tundish is (6-7) kg, (21-22) t; when the quality of the tundish molten steel reaches the normal casting quality, adding an upper covering agent, wherein the mass ratio of the upper covering agent to the tundish molten steel is (6-7) kg, (21-22) t;
in a preferred embodiment, in the method for controlling the titanium content after the steelmaking converter furnace, the method for covering the liquid level of the molten steel in the tundish by using the double-layer covering agent comprises the following steps: when the quality of the molten steel of the tundish reaches 1/9 of the normal casting quality, respectively adding a lower covering agent into temperature measurement sampling holes at two sides of the tundish and rod dropping holes, wherein the mass ratio of the lower covering agent to the molten steel of the tundish is (66-77) kg, (21-22) t; when the quality of the molten steel of the tundish reaches 2/9-2/3 of the normal casting quality, adding a lower covering agent into a large ladle casing pipe hole of the tundish, wherein the mass ratio of the lower covering agent to the molten steel of the tundish is (6-7) kg, (21-22) t; when the quality of the tundish molten steel reaches the normal casting quality, adding an upper covering agent, wherein the mass ratio of the upper covering agent to the tundish molten steel is (6-7) kg, (21-22) t;
in a preferred embodiment, in the method for controlling the titanium content after the steelmaking converter, when the molten steel in the tundish is exposed or turned over, the covering agent at the lower layer is added, and then the covering agent at the upper layer is added.
In one embodiment, in the method for controlling titanium content after a steelmaking converter according to the present invention, the steel slab obtained after the continuous casting includes, by mass: 0.0010-0.0015% of Ti;
in a preferred embodiment, in the method for controlling the content of titanium after the steelmaking converter according to the present invention, the increase of Ti in the steel slab during the continuous casting process is 0.00015 to 0.0002% by mass.
Example 1:
in this embodiment, the method for controlling the titanium content after the steelmaking converter comprises the following steps:
(1) after the converter finishes smelting qualified molten steel, tapping is started, the grade of the steel is selected and returned to a steel ladle (220t of molten steel), wherein the titanium content of the molten steel in the steel ladle is 0.0016%;
(2) in the tapping process, 80kg of fluorite, 350kg of lime and 360kg of light-burned dolomite are added into a ladle behind the furnace, the bottom blowing flow of the ladle adopted in the tapping process is 280L/min, and the Ti content in the obtained molten steel is 0.00015 percent by mass percent;
(3) performing RH decarburization on the molten steel obtained in the step (2), wherein the temperature of the molten steel is 1580 ℃, and when the RH decarburization is completed, the content of C in the molten steel is less than or equal to 0.003 percent by mass;
(4) performing deoxidation alloying and RH pure circulation on the molten steel obtained in the step (3);
the deoxidation alloying comprises a first low-carbon ferrosilicon deoxidation alloying and a second aluminum deoxidation alloying which are sequentially carried out; the interval time between the first low-carbon ferrosilicon deoxidation alloying and the second aluminum deoxidation alloying is 2 min; the RH pure cycle time is 7 min;
adding low-carbon ferrosilicon into the molten steel obtained in the step (3) in the first low-carbon ferrosilicon deoxidation alloying; the mass ratio of the low-carbon ferrosilicon to the molten steel subjected to RH decarburization is 48kg to 1 t;
in the second aluminum deoxidation alloying, adding aluminum particles and tin particles into the molten steel after the first low-carbon ferrosilicon deoxidation alloying is finished;
wherein the mass ratio of the aluminum particles to the molten steel after the first low-carbon ferrosilicon deoxidation alloying is 9.5kg to 1 t;
the mass ratio of the tin particles to the molten steel after the first low-carbon ferrosilicon deoxidation alloying is 0.05kg to 1 t;
wherein, the RH refining furnace is a station which has already processed the steel grade, and the rinsing furnace operation is not needed.
In the above process, the low-carbon ferrosilicon comprises: 76 percent of Si and less than or equal to 0.01 percent of Ti;
in the low-carbon ferrosilicon, the mass percentage of particles with the particle size of 10-50 mm is more than or equal to 90 percent, the mass percentage of particles with the particle size of less than 10mm is less than or equal to 5 percent, and the mass percentage of particles with the particle size of more than 10mm is less than or equal to 5 percent;
the aluminum particles comprise, by mass percent: more than or equal to 99.95 percent of Al and less than or equal to 0.01 percent of Ti; the particle size of the aluminum particles is 3-20 mm;
the tin particles comprise, by mass, more than or equal to 99.90% of Sn and less than or equal to 0.01% of Ti, and the size of the tin particles is less than or equal to 70mm, × 60mm and × 50 mm.
After the RH refining is finished, the molten steel after the RH refining comprises the following components in percentage by mass: 0.0012% of Ti; the Ti increase amount in the molten steel in the RH refining process is 0.00085% by mass percent;
(5) continuously casting the molten steel obtained in the step (4), and injecting the molten steel refined by RH into a tundish to obtain molten steel of the tundish; covering the liquid level of the molten steel in the tundish by using a double-layer covering agent, and carrying out continuous casting;
the double-layer covering agent comprises an upper-layer covering agent and a lower-layer covering agent, the lower-layer covering agent is in contact with molten steel of the tundish, and the upper-layer covering agent is positioned above the lower-layer covering agent;
the upper covering agent comprises the following components in percentage by mass: SiO 2252％，CaO 5％，Ti 1.8％， Fe2O310％，Al2O312％，C≤1％，MgO 5％；
The lower layer covering agent comprises the following components in percentage by mass: SiO 2247％，CaO 40％，Ti 0.15％， Fe2O32％，Al2O31％，C≤1％，MgO 1％；
The SiO2Is expanded perlite; the CaO is quicklime; the Al is2O3Is calcium aluminate.
The mass ratio of the double-layer covering agent to the tundish molten steel is 0.55kg to 0.9 t; the mass ratio of the upper-layer covering agent to the lower-layer covering agent is 7: 2.5;
when the liquid level of the molten steel in the tundish is covered by the double-layer covering agent, when the molten steel in the tundish is exposed or turned over, the covering agent at the lower layer is replenished, and then the covering agent at the upper layer is replenished.
According to the mass percentage, the steel plate blank in the continuous casting process comprises the following components: 0.0010% of Ti; the increase of Ti in the steel slab in the continuous casting process is 0.00015% by mass.
Example 2:
in this embodiment, the method for controlling the titanium content after the steelmaking converter comprises the following steps:
(1) after the converter finishes smelting qualified molten steel, tapping is started, non-parent steel is selected and returned to a ladle (220t of molten steel), wherein the titanium content of the molten steel in the ladle is 0.0045%;
(2) in the tapping process, adding 50kg of fluorite, 200kg of lime and 300kg of light-burned dolomite into a ladle behind the furnace, wherein the bottom blowing flow of the ladle adopted in the tapping process is 350L/min, and the Ti content in the obtained molten steel is 0.0002 percent by mass percent;
(3) performing RH decarburization on the molten steel obtained in the step (2), wherein the temperature of the molten steel is 1610 ℃, and when the RH decarburization is completed, the content of C in the molten steel is less than or equal to 0.003 percent by mass;
in the RH refining process, the ladle at the back of the furnace is a non-parent steel type and returns to the ladle, and the RH refining furnace needs to be rinsed before the step (3) is started; wherein, in rinsing furnace water adopted by rinsing furnace treatment, Ti is less than or equal to 0.0002 percent by mass;
(4) performing deoxidation alloying and RH pure circulation on the molten steel obtained in the step (3);
the deoxidation alloying comprises a first low-carbon ferrosilicon deoxidation alloying and a second aluminum deoxidation alloying which are sequentially carried out; the interval time between the first low-carbon ferrosilicon deoxidation alloying and the second aluminum deoxidation alloying is 3 min; the RH pure cycle time is 8 min;
adding low-carbon ferrosilicon into the molten steel obtained in the step (3) in the first low-carbon ferrosilicon deoxidation alloying; the mass ratio of the low-carbon ferrosilicon to the molten steel subjected to RH decarburization is 55kg to 1.1 t;
in the second aluminum deoxidation alloying, adding aluminum particles and tin particles into the molten steel after the first low-carbon ferrosilicon deoxidation alloying is finished;
wherein the mass ratio of the aluminum particles to the molten steel after the first low-carbon ferrosilicon deoxidation alloying is 4kg:0.9 t;
the mass ratio of the tin particles to the molten steel after the first low-carbon ferrosilicon deoxidation alloying is 0.1kg to 1.1 t;
wherein, the RH refining furnace is a station which has already processed the steel grade, and the rinsing furnace operation is not needed.
In the above process, the low-carbon ferrosilicon comprises: 79 percent of Si and less than or equal to 0.01 percent of Ti;
in the low-carbon ferrosilicon, the mass percentage of particles with the particle size of 10-50 mm is more than or equal to 90 percent, the mass percentage of particles with the particle size of less than 10mm is less than or equal to 5 percent, and the mass percentage of particles with the particle size of more than 10mm is less than or equal to 5 percent;
the aluminum particles comprise, by mass percent: more than or equal to 99.95 percent of Al and less than or equal to 0.01 percent of Ti; the particle size of the aluminum particles is 3-20 mm;
the tin particles comprise, by mass, more than or equal to 99.90% of Sn and less than or equal to 0.01% of Ti, and the size of the tin particles is less than or equal to 70mm, × 60mm and × 50 mm.
After the RH refining is finished, the molten steel after the RH refining comprises the following components in percentage by mass: 0.0013 percent of Ti; according to the mass percentage, the increase of Ti in the molten steel in the RH refining process is 0.0010%;
(5) continuously casting the molten steel obtained in the step (4), and injecting the molten steel refined by RH into a tundish to obtain molten steel of the tundish; covering the liquid level of the molten steel in the tundish by using a double-layer covering agent, and carrying out continuous casting;
the double-layer covering agent comprises an upper-layer covering agent and a lower-layer covering agent, the lower-layer covering agent is in contact with molten steel of the tundish, and the upper-layer covering agent is positioned above the lower-layer covering agent;
the upper covering agent comprises the following components in percentage by mass: SiO 2242％，CaO 2％，Ti 1.8％， Fe2O38％，Al2O38％，C≤1％，MgO 2％；
The lower layer covering agent comprises the following components in percentage by mass: SiO 2245％，CaO 38％，Ti 0.12％， Fe2O31％，Al2O32％，C≤1％，MgO 1％；
The SiO2Is vermiculite; the CaO is dolomite; the Al is2O3Is calcium aluminate.
The method adopts a double-layer covering agent to cover the liquid level of the molten steel in the tundish, and comprises the following steps: when the quality of the molten steel of the tundish reaches 1/9 of the normal casting quality, respectively adding lower covering agents into temperature measurement sampling holes at two sides of the tundish and rod-racing holes, wherein the mass ratio of the lower covering agents to the molten steel of the tundish is 66kg:21 t; when the quality of the molten steel of the tundish reaches 2/9-2/3 of the normal casting quality, adding a lower covering agent into a large ladle casing pipe hole of the tundish, wherein the mass ratio of the lower covering agent to the molten steel of the tundish is 6kg:21 t; when the quality of the tundish molten steel reaches the normal casting quality, adding an upper-layer covering agent, wherein the mass ratio of the upper-layer covering agent to the tundish molten steel is 6kg:21 t;
when the liquid level of the molten steel in the tundish is covered by the double-layer covering agent, when the molten steel in the tundish is exposed or turned over, the covering agent at the lower layer is replenished, and then the covering agent at the upper layer is replenished.
According to the mass percentage, the steel plate blank in the continuous casting process comprises the following components: 0.0015 percent of Ti; the increase of Ti in the steel slab in the continuous casting process is 0.0002% in percentage by mass.
Example 3:
in this embodiment, the method for controlling the titanium content after the steelmaking converter comprises the following steps:
(1) after the converter finishes smelting qualified molten steel, tapping is started, the grade of the steel is selected and returned to a steel ladle (230t of molten steel), wherein the titanium content of the molten steel in the steel ladle is 0.0013%;
(2) in the tapping process, 150kg of fluorite, 500kg of lime and 800kg of light-burned dolomite are added into a ladle behind the furnace, the bottom blowing flow of the ladle adopted in the tapping process is 300L/min, and the Ti content in the obtained molten steel is 0.0002 percent by mass percent;
(3) performing RH decarburization on the molten steel obtained in the step (2), wherein the temperature of the molten steel is 1590 ℃, and when the RH decarburization is completed, the content of C in the molten steel is less than or equal to 0.003 percent by mass;
(4) performing deoxidation alloying and RH pure circulation on the molten steel obtained in the step (3);
the deoxidation alloying comprises a first low-carbon ferrosilicon deoxidation alloying and a second aluminum deoxidation alloying which are sequentially carried out; the interval time between the first low-carbon ferrosilicon deoxidation alloying and the second aluminum deoxidation alloying is 3 min; the RH pure cycle time is 8 min;
adding low-carbon ferrosilicon into the molten steel obtained in the step (3) in the first low-carbon ferrosilicon deoxidation alloying; the mass ratio of the low-carbon ferrosilicon to the molten steel subjected to RH decarburization is 40kg:0.9 t;
in the second aluminum deoxidation alloying, aluminum particles and copper particles are added into the molten steel after the first low-carbon ferrosilicon deoxidation alloying is finished;
wherein the mass ratio of the aluminum particles to the molten steel after the first low-carbon ferrosilicon deoxidation alloying is 14kg:1.1 t;
the mass ratio of the copper particles to the molten steel after the first low-carbon ferrosilicon deoxidation alloying is 0.03kg to 1 t;
wherein, the RH refining furnace is a station which has already processed the steel grade, and the rinsing furnace operation is not needed.
In the above process, the low-carbon ferrosilicon comprises: 79 percent of Si and less than or equal to 0.01 percent of Ti;
in the low-carbon ferrosilicon, the mass percentage of particles with the particle size of 10-50 mm is more than or equal to 90 percent, the mass percentage of particles with the particle size of less than 10mm is less than or equal to 5 percent, and the mass percentage of particles with the particle size of more than 10mm is less than or equal to 5 percent;
the aluminum particles comprise, by mass percent: more than or equal to 99.95 percent of Al and less than or equal to 0.01 percent of Ti; the particle size of the aluminum particles is 3-20 mm;
the copper particles comprise, by mass percent: cu is more than or equal to 99.95 percent, and Ti is less than or equal to 0.01 percent; the particle size of the copper particles is 40-50 mm;
after the RH refining is finished, the molten steel after the RH refining comprises the following components in percentage by mass: 0.0013 percent of Ti; according to the mass percentage, the increase of Ti in the molten steel in the RH refining process is 0.0010%;
(5) continuously casting the molten steel obtained in the step (4), and injecting the molten steel refined by RH into a tundish to obtain molten steel of the tundish; covering the liquid level of the molten steel in the tundish by using a double-layer covering agent, and carrying out continuous casting;
the double-layer covering agent comprises an upper-layer covering agent and a lower-layer covering agent, the lower-layer covering agent is in contact with molten steel of the tundish, and the upper-layer covering agent is positioned above the lower-layer covering agent;
the upper covering agent comprises the following components in percentage by mass: SiO 2262％，CaO 8％，Ti 1.8％，Fe2O310％，Al2O318％，C≤1％，MgO 10％；
The lower layer covering agent comprises the following components in percentage by mass: siO255％，CaO 48％，Ti 0.15％， Fe2O32％，Al2O32％，C≤1％，MgO 1％；
The SiO2Is vermiculite; the CaO is dolomite; the Al is2O3Is calcium aluminate.
The method adopts a double-layer covering agent to cover the liquid level of the molten steel in the tundish, and comprises the following steps: when the quality of the molten steel of the tundish reaches 1/9 of the normal casting quality, respectively adding a lower covering agent into temperature measuring sampling holes at two sides of the tundish and a rod-racing hole, wherein the mass ratio of the lower covering agent to the molten steel of the tundish is 77kg:22 t; when the quality of the molten steel of the tundish reaches 2/9-2/3 of the normal casting quality, adding a lower covering agent into a large ladle casing pipe hole of the tundish, wherein the mass ratio of the lower covering agent to the molten steel of the tundish is 7kg:22 t; when the quality of the tundish molten steel reaches the normal casting quality, adding an upper-layer covering agent, wherein the mass ratio of the upper-layer covering agent to the tundish molten steel is 7kg:22 t;
when the liquid level of the molten steel in the tundish is covered by the double-layer covering agent, when the molten steel in the tundish is exposed or turned over, the covering agent at the lower layer is replenished, and then the covering agent at the upper layer is replenished.
According to the mass percentage, the steel plate blank in the continuous casting process comprises the following components: 0.0015 percent of Ti; the increase of Ti in the steel slab in the continuous casting process is 0.0002% in percentage by mass.
Example 4:
in this embodiment, the method for controlling the titanium content after the steelmaking converter comprises the following steps:
(1) after the converter finishes smelting qualified molten steel, tapping is started, the grade of the steel is selected and returned to a steel ladle (220t of molten steel), wherein the titanium content of the molten steel in the steel ladle is 0.0016%;
(2) in the tapping process, 80kg of fluorite, 350kg of lime and 360kg of light-burned dolomite are added into a ladle behind the furnace, the bottom blowing flow of the ladle adopted in the tapping process is 280L/min, and the Ti content in the obtained molten steel is 0.00015 percent by mass percent;
(3) performing RH decarburization on the molten steel obtained in the step (2), wherein the temperature of the molten steel is 1610 ℃, and when the RH decarburization is completed, the content of C in the molten steel is less than or equal to 0.003 percent by mass;
(4) performing deoxidation alloying and RH pure circulation on the molten steel obtained in the step (3);
the deoxidation alloying comprises a first low-carbon ferrosilicon deoxidation alloying and a second aluminum deoxidation alloying which are sequentially carried out; the interval time between the first low-carbon ferrosilicon deoxidation alloying and the second aluminum deoxidation alloying is 2 min; the RH pure cycle time is 7 min;
adding low-carbon ferrosilicon into the molten steel obtained in the step (3) in the first low-carbon ferrosilicon deoxidation alloying; the mass ratio of the low-carbon ferrosilicon to the molten steel subjected to RH decarburization is 48kg to 1 t;
in the second aluminum deoxidation alloying, adding aluminum particles and tin particles into the molten steel after the first low-carbon ferrosilicon deoxidation alloying is finished;
wherein the mass ratio of the aluminum particles to the molten steel after the first low-carbon ferrosilicon deoxidation alloying is 9.5kg to 1 t;
the mass ratio of the tin particles to the molten steel after the first low-carbon ferrosilicon deoxidation alloying is 0.05kg to 1 t;
wherein, the RH refining furnace is a station which has already processed the steel grade, and the rinsing furnace operation is not needed.
In the above process, the low-carbon ferrosilicon comprises: 76 percent of Si and less than or equal to 0.01 percent of Ti;
in the low-carbon ferrosilicon, the mass percentage of particles with the particle size of 10-50 mm is more than or equal to 90 percent, the mass percentage of particles with the particle size of less than 10mm is less than or equal to 5 percent, and the mass percentage of particles with the particle size of more than 10mm is less than or equal to 5 percent;
the aluminum particles comprise, by mass percent: more than or equal to 99.95 percent of Al and less than or equal to 0.01 percent of Ti; the particle size of the aluminum particles is 3-20 mm;
the tin particles comprise, by mass, more than or equal to 99.90% of Sn and less than or equal to 0.01% of Ti, and the size of the tin particles is less than or equal to 70mm, × 60mm and × 50 mm.
After the RH refining is finished, the molten steel after the RH refining comprises the following components in percentage by mass: 0.0012% of Ti; the Ti increase amount in the molten steel in the RH refining process is 0.00085% by mass percent;
(5) continuously casting the molten steel obtained in the step (4), and injecting the molten steel refined by RH into a tundish to obtain molten steel of the tundish; covering the liquid level of the molten steel in the tundish by using a double-layer covering agent, and carrying out continuous casting;
the double-layer covering agent comprises an upper-layer covering agent and a lower-layer covering agent, the lower-layer covering agent is in contact with molten steel of the tundish, and the upper-layer covering agent is positioned above the lower-layer covering agent;
the upper covering agent comprises the following components in percentage by mass: SiO 2242％，CaO 2％，Ti 1.8％， Fe2O38％，Al2O38％，C≤1％，MgO 2％；
The lower layer covering agent comprises the following components in percentage by mass: SiO 2245％，CaO 38％，Ti 0.12％， Fe2O31％，Al2O32％，C≤1％，MgO 1％；
The SiO2Is expanded perlite; the CaO is quicklime; the Al is2O3Is calcium aluminate.
The mass ratio of the double-layer covering agent to the molten steel of the tundish is 0.70kg to 1.1 t; the mass ratio of the upper covering agent to the lower covering agent is 7.5: 3;
when the liquid level of the molten steel in the tundish is covered by the double-layer covering agent, when the molten steel in the tundish is exposed or turned over, the covering agent at the lower layer is replenished, and then the covering agent at the upper layer is replenished.
According to the mass percentage, the steel plate blank in the continuous casting process comprises the following components: 0.0010% of Ti; the increase of Ti in the steel slab in the continuous casting process is 0.00015% by mass.
Through the above embodiments, the present invention has at least the following technical effects or advantages:
(1) the molten steel in the ladle after the furnace selected by the invention contains Ti less than 0.01 percent, preferably Ti less than 0.002 percent, so that the phenomenon of 'titanium return' in the subsequent process caused by ladle slag can be reduced to the greatest extent;
(2) the method aims at the modification of the top slag of the ladle after the furnace, so that the top slag of the ladle is thickened more effectively, the slag steel reaction is prevented, and the subsequent titanium return phenomenon is reduced efficiently;
(3) according to the invention, the grain size and size of the low-carbon ferrosilicon, the aluminum grains, the tin grains and the like are limited, so that the alloy melting effect and the alloy yield are greatly improved;
(4) according to the invention, low-titanium ferrosilicon is added for weak deoxidation, so that adverse factors aiming at controlling titanium content caused by strong deoxidation can be reduced; after the weak deoxidation, the aluminum particles, the tin particles and the like are adopted for alloying treatment, thereby further effectively reducing the titanium return phenomenon of the molten steel.
(5) The invention adopts the double-layer covering agent to cover the liquid level of the molten steel in the tundish, and correspondingly limits each component and the content of the double-layer covering agent, thereby further reducing the titanium increase of the molten steel in the molten steel casting process, and controlling the average titanium content of a final product within 0.0010-0.0015%.
Finally, it should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims (10)

1. A method of controlling titanium content after a steelmaking converter, the method comprising the steps of: carrying out top slag modification on a ladle behind the furnace to obtain molten steel with modified top slag; sequentially carrying out RH refining and continuous casting on the molten steel modified by the top slag;
wherein, the molten steel in the ladle after the furnace comprises the following components in percentage by mass: ti is less than 0.01 percent;
the method for modifying the top slag of the ladle after the furnace comprises the following steps: in the tapping process, fluorite, lime and light-burned dolomite are added into a ladle behind the furnace;
the mass ratio of the fluorite to the lime to the light-burned dolomite is (0.5-1.5) to (2-5) to (3-8);
the RH refining comprises RH decarburization, deoxidation alloying and RH pure circulation.
2. The method of controlling titanium content after steelmaking converter according to claim 1, wherein the mass ratio of said fluorite, said lime and said light-burned dolomite is 0.8:3.5: 3.6;
preferably, the mass ratio of the fluorite, the lime, the light-burned dolomite to the molten steel in the ladle after the furnace is (0.5-1.5) kg, (2-5) kg, (3-8) kg, (2.2-2.3) t;
preferably, the mass ratio of the fluorite, the lime, the light-burned dolomite to the molten steel in the ladle after the furnace is 0.8kg to 3.5kg to 3.6kg to 2.2 t.
3. The method for controlling the titanium content after the steelmaking converter is used as claimed in claim 1 or 2, wherein during the top slag modification of the ladle after the converter, the ladle bottom blowing flow is 280-350L/min;
the molten steel after the top slag modification comprises the following components in percentage by mass: 0.00015 to 0.0002% of Ti.
4. The method of controlling titanium content after steelmaking converter according to claim 1 or 2, wherein the ladle after the converter includes: the grade of the steel returns to the ladle or the non-grade of the steel returns to the ladle;
preferably, the steel grade return ladle is a silicon steel return ladle;
preferably, the molten steel in the ladle after the furnace comprises the following components in percentage by mass: ti is less than 0.002%;
preferably, in the RH decarburization process, the temperature of molten steel is 1580-1610 ℃;
when the RH decarburization is finished, the content of C in the molten steel is less than or equal to 0.003 percent by mass percent.
5. The method of controlling titanium content after steelmaking converter according to claim 1 or 2, characterized in that the deoxidation alloying includes a first low-carbon ferrosilicon deoxidation alloying and a second aluminum deoxidation alloying which are performed in this order; the interval time between the first low-carbon ferrosilicon deoxidation alloying and the second aluminum deoxidation alloying is 2-3 min; the RH pure cycle time is 7-8 min;
wherein, the first time of low carbon ferrosilicon deoxidation alloying comprises: adding low-carbon ferrosilicon into the molten steel subjected to RH decarburization; the mass ratio of the low-carbon ferrosilicon to the molten steel subjected to RH decarburization is (40-55) kg (0.9-1.1) t; preferably 48kg to 1 t;
the second aluminum deoxidation alloying comprises the following steps: adding aluminum particles and tin particles into the molten steel after the first deoxidation alloying of the low-carbon ferrosilicon is completed, or adding aluminum particles and copper particles into the molten steel after the first deoxidation alloying of the low-carbon ferrosilicon is completed;
wherein the mass ratio of the aluminum particles to the molten steel after the first low-carbon ferrosilicon deoxidation alloying is (4-14) kg, (0.9-1.1) t; preferably 9.5kg:1 t;
the mass ratio of the tin particles to the molten steel after the first low-carbon ferrosilicon deoxidation alloying is (0-0.1) kg and (0.9-1.1) t; preferably 0.05kg:1 t;
the mass ratio of the copper particles to the molten steel after the first low-carbon ferrosilicon deoxidation alloying is (0-0.1) kg and (0.9-1.1) t; preferably 0.03kg:1 t.
6. The method of controlling titanium content after steelmaking converter according to claim 5, characterized in that the low-carbon ferrosilicon contains, in mass percent: 76-79% of Si and less than or equal to 0.01% of Ti;
in the low-carbon ferrosilicon, the mass percentage of particles with the particle size of 10-50 mm is more than or equal to 90 percent, the mass percentage of particles with the particle size of less than 10mm is less than or equal to 5 percent, and the mass percentage of particles with the particle size of more than 10mm is less than or equal to 5 percent;
preferably, the aluminum particles comprise, in mass percent: more than or equal to 99.95 percent of Al and less than or equal to 0.01 percent of Ti; the particle size of the aluminum particles is 3-20 mm;
preferably, the copper particles comprise, in mass percent: cu is more than or equal to 99.95 percent, and Ti is less than or equal to 0.01 percent; the particle size of the copper particles is 40-50 mm;
preferably, the tin particles comprise, by mass, not less than 99.90% of Sn and not more than 0.01% of Ti, and the size of the tin particles is not more than 70mm, × 60mm and × 50 mm.
7. The method of controlling titanium content after steelmaking converter according to claim 1 or 2, wherein the molten steel after RH refining includes, in mass percent, after completion of RH refining: 0.0012-0.0013% of Ti;
preferably, after the RH refining is finished, the increase of Ti in molten steel in the RH refining process is 0.00105-0.0011% by mass percent;
preferably, in the RH refining process, when the ladle after the furnace is a non-parent steel type returning ladle, the furnace rinsing treatment is carried out on the RH refining furnace; wherein, in the rinsing furnace water adopted by rinsing furnace treatment, the Ti is less than or equal to 0.0002 percent by mass percent.
8. The method of controlling titanium content after steelmaking converter according to claim 1 or 2, characterized in that the continuous casting includes: pouring the molten steel refined by RH into a tundish to obtain molten steel of the tundish; covering the liquid level of the molten steel in the tundish by using a double-layer covering agent, and carrying out continuous casting;
the double-layer covering agent comprises an upper-layer covering agent and a lower-layer covering agent, the lower-layer covering agent is in contact with molten steel of the tundish, and the upper-layer covering agent is positioned above the lower-layer covering agent;
the upper covering agent comprises the following components in percentage by mass: SiO 2242～62％，CaO≤10％，Ti 1.8％，Fe2O3≤15％，Al2O38～18％，C≤1％，MgO 2～10％；
The lower layer covering agent comprises the following components in percentage by mass: SiO 2245～55％，CaO 38～48％，Ti≤0.15％，Fe2O3≤3％，Al2O3≤3％，C≤1％，MgO≤3％；
Preferably, the upper covering agent comprises, in mass percent: SiO 2252％，CaO 5％，Ti 1.8％，Fe2O310％，Al2O312％，C≤1％，MgO 5％；
The lower layer covering agent comprises the following components in percentage by mass: SiO 2247％，CaO 40％，Ti 0.15％，Fe2O32％，Al2O31％，C≤1％，MgO 1％；
Preferably, the SiO2One or two selected from expanded perlite or vermiculite; the CaO is selected from one or two of quicklime or dolomite; the Al is2O3Is calcium aluminate.
9. The method for controlling the titanium content after the steelmaking converter according to claim 8, wherein the mass ratio of the double-layer covering agent to the tundish molten steel is (0.55-0.70) kg (0.9-1.1) t; the mass ratio of the upper covering agent to the lower covering agent is (7-7.5) to (2.5-3);
preferably, the covering of the liquid surface of the molten steel in the tundish by using the double-layer covering agent comprises the following steps: when the quality of the molten steel of the tundish reaches 1/9 of the normal casting quality, adding a lower covering agent, wherein the mass ratio of the lower covering agent to the molten steel of the tundish is (66-77) kg, (21-22) t; when the quality of the molten steel of the tundish reaches 2/9-2/3 of the normal casting quality, adding a lower covering agent, wherein the mass ratio of the lower covering agent to the molten steel of the tundish is (6-7) kg, (21-22) t; when the quality of the tundish molten steel reaches the normal casting quality, adding an upper covering agent, wherein the mass ratio of the upper covering agent to the tundish molten steel is (6-7) kg, (21-22) t;
preferably, the covering of the liquid surface of the molten steel in the tundish by using the double-layer covering agent comprises the following steps: when the quality of the molten steel of the tundish reaches 1/9 of the normal casting quality, respectively adding a lower covering agent into temperature measurement sampling holes at two sides of the tundish and rod dropping holes, wherein the mass ratio of the lower covering agent to the molten steel of the tundish is (66-77) kg, (21-22) t; when the quality of the molten steel of the tundish reaches 2/9-2/3 of the normal casting quality, adding a lower covering agent into a large ladle casing pipe hole of the tundish, wherein the mass ratio of the lower covering agent to the molten steel of the tundish is (6-7) kg, (21-22) t; when the quality of the tundish molten steel reaches the normal casting quality, adding an upper covering agent, wherein the mass ratio of the upper covering agent to the tundish molten steel is (6-7) kg, (21-22) t;
preferably, when the molten steel in the tundish is exposed or turned over, the covering agent at the lower layer is supplemented, and then the covering agent at the upper layer is supplemented.
10. The method for controlling the titanium content after steelmaking converter according to claim 1 or 2, characterized in that the steel slab obtained after the completion of continuous casting comprises, in mass percent: 0.0010-0.0015% of Ti0.0010;
preferably, the increase of Ti in the steel slab in the continuous casting process is 0.00015-0.0002% by mass.
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