CN113025781A - Method for producing low-carbon low-silicon ultralow-sulfur steel by adopting LF (ladle furnace) single-link process - Google Patents

Method for producing low-carbon low-silicon ultralow-sulfur steel by adopting LF (ladle furnace) single-link process Download PDF

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CN113025781A
CN113025781A CN202110170421.9A CN202110170421A CN113025781A CN 113025781 A CN113025781 A CN 113025781A CN 202110170421 A CN202110170421 A CN 202110170421A CN 113025781 A CN113025781 A CN 113025781A
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steel
low
silicon
sulfur
smelting
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CN113025781B (en
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李战军
刘金刚
初仁生
郝宁
朱志远
朱国森
马长文
李海波
季晨曦
石树东
谢翠红
周磊
王宏宇
关春阳
李光双
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Shougang Corp
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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
    • C21C7/064—Dephosphorising; Desulfurising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0006—Adding metallic additives
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/06—Deoxidising, e.g. killing
    • 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
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/076—Use of slags or fluxes as treating agents
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Abstract

The invention discloses a method for producing low-carbon low-silicon ultralow-sulfur steel by adopting an LF (ladle furnace) single-link process, which comprises the steps of desulfurizing molten iron and carrying out slagging-off pretreatment to obtain pretreated molten iron; smelting the pretreated molten iron, low-sulfur steel scrap and auxiliary materials to obtain molten smelting steel; the oxygen blowing time in smelting is controlled to be 13-15 min, and the oxygen blowing amount is controlled to be 46-52 Nm3Controlling the oxygen lance position to be 1.5-1.7 m; tapping the smelting molten steel to obtain tapped molten steel; adding the molten steel into refining slag for refining to obtain low-carbon low-silicon ultralow-sulfur refined molten steel and refined final slag; bottom blowing of 600-800 NL/min argon gas in the initial slagging stage of refining, and bottom blowing of 40 in the later heating stage of refiningArgon gas of 0-600 NL/min and heating time is controlled to be less than or equal to 15 min; the carbon content in the steel is 0.030 to 0.050 percent, the silicon content is less than or equal to 0.050 percent, and the sulfur content is less than or equal to 0.0020 percent.

Description

Method for producing low-carbon low-silicon ultralow-sulfur steel by adopting LF (ladle furnace) single-link process
Technical Field
The invention relates to the technical field of steel making, in particular to a method for producing low-carbon low-silicon ultralow-sulfur steel by adopting an LF (ladle furnace) single-link process.
Background
The low-carbon steel produced by the continuous casting and rolling production line mainly comprises low-carbon low-silicon steel, the low-carbon low-silicon steel has good tensile property and ductility after hot rolling and cold rolling, and the material has good processability and is widely applied to multiple industrial and civil fields. The low-carbon low-silicon steel requires that the carbon content is 0.010-0.040 percent and the silicon content is less than or equal to 0.05 percent; because the continuous casting and rolling production process is adopted, the sulfur content of the steel grade is required to be less than or equal to 0.0020 percent in order to ensure the quality of a continuous casting billet and the smoothness of the casting process, and therefore the low-carbon steel grade of the continuous casting and rolling production line is a low-carbon, low-silicon and ultralow-sulfur component system. Because the carbon and silicon contents in the steel are lower, the process and parameters need to be controlled when the converter is adopted for smelting, the low-carbon component requirement is met while the low silicon content at the end point is ensured, and the temperature at the end point is ensured to meet the requirement of steel production; meanwhile, in the subsequent refining process, deep desulfurization operation is required, and if the smelting process is improperly controlled in the deep desulfurization process, the silicon return amount is increased, so that the silicon content of the steel grade exceeds the standard, and the smelting yield is seriously influenced.
Comparison document 1: the patent application with the application number of '201210055077. X' discloses a preparation process of low-carbon low-silicon aluminum killed steel, which specifically comprises the following steps: the method comprises the following steps of a desulfurization process, a converter process, an argon station process and a continuous casting process, wherein the control of smelting of low-carbon low-silicon steel is realized, the carbon content is controlled to be 0.03-0.06%, the silicon content is controlled to be less than or equal to 0.03%, and the sulfur content in steel is controlled to be less than or equal to 0.015% and belongs to high-sulfur steel; and the control difficulty of the silicon content in the steel is higher during deep desulfurization, so the patent application can only realize the smelting requirement of low carbon and low silicon and can not realize the smelting requirement of low carbon, low silicon and ultralow sulfur.
Comparison document 2: the patent application with the application number of '201510636195.3' discloses a refining silicon control method of low-carbon low-silicon low-sulfur micro-titanium aluminum killed steel, which is used for controlling the deoxidation and desulfurization depth of molten steel so as to achieve the purpose of controlling the silicon return amount in the molten steel in the deoxidation and desulfurization processes; at the same time, the time for adding ferrotitanium in the refining process is shifted backwards, so that ferrotitanium and SiO are reduced2The reaction time of (2) reduces the silicon content of molten steel caused by adding ferrotitanium; the method can effectively control the silicon content in the molten steel, the carbon content of the steel is controlled to be 0.06% -0.10%, the silicon content is not more than 0.05%, and the sulfur content is not more than 0.010%, belongs to high-sulfur steel, and cannot meet the smelting requirement of ultra-low sulfur, and the silicon content of the steel is difficult to control during deep desulfurization of the ultra-low sulfur, so that the method cannot meet the smelting requirement of low carbon, low silicon and ultra-low sulfur.
Comparison document 3: the patent application with the application number of '201711134626.1' discloses a method for smelting low-carbon low-silicon aluminum killed steel on a CSP production line, and the control process of the method is as follows: the method comprises the steps of molten iron desulfurization, converter smelting, argon station argon blowing, LF furnace refining and continuous casting. The method mainly solves the problems of high rate of judgment, low component percent of pass, frequent casting interruption and the like caused by surface quality defects when smelting low-carbon low-silicon aluminum killed steel, the control range of the sulfur content of steel grades is 0.0038-0.0060%, the control range of the silicon content is less than or equal to 0.04%, the sulfur content of the steel grades belongs to low-sulfur steel grades in the patent application, the control difficulty of the silicon content is low on the premise of the low-sulfur steel grades, and the control of the silicon content can be realized to be less than or equal to 0.05%; and the patent application does not specifically suggest the production of carbon content control levels while only being applicable to short runs of CSP.
Therefore, how to develop a method for producing low-carbon low-silicon ultralow-sulfur steel by adopting an LF single-link process and realize the control requirement of low-carbon low-silicon ultralow-sulfur components becomes a technical problem to be solved urgently.
Disclosure of Invention
The invention aims to provide a method for producing low-carbon low-silicon ultralow-sulfur steel by adopting an LF (ladle furnace) single-link process, which meets the control requirements of low-carbon low-silicon and ultralow-sulfur components of which the carbon content is 0.030-0.050%, the silicon content is less than or equal to 0.05% and the sulfur content is less than or equal to 0.0020% by adopting the LF single-link process.
In order to achieve the aim, the invention provides a method for producing low-carbon low-silicon ultralow-sulfur steel by adopting an LF (ladle furnace) single-link process, which comprises the following steps:
carrying out desulfurization and slagging-off pretreatment on molten iron to obtain pretreated molten iron;
smelting the pretreated molten iron, low-sulfur steel scrap and auxiliary materials to obtain molten smelting steel; wherein oxygen blowing is carried out in the smelting, the oxygen blowing time is controlled to be 13-15 min, and the oxygen blowing amount is controlled to be 46-52 Nm3Controlling the oxygen lance position to be 1.5-1.7 m;
tapping the smelting molten steel to obtain tapped molten steel;
adding the molten steel into refining slag for refining to obtain low-carbon low-silicon ultralow-sulfur refined molten steel and refined final slag; the refining comprises an initial slagging stage and a later heating stage, wherein 600-800 NL/min argon is blown to the bottom of the initial slagging stage, and 400-600 NL/min argon is blown to the bottom of the later heating stage, and the heating time is controlled to be less than or equal to 15 min.
Further, the method for carrying out desulphurization and slagging-off pretreatment on the molten iron to obtain pretreated molten iron specifically comprises the following steps:
carrying out desulfurization pretreatment on molten iron, and controlling the stirring time during the desulfurization pretreatment to be 10-15 min; and then removing top slag, wherein the bright surface rate of slag removal is more than or equal to 95 percent, and obtaining the pretreated molten iron with the S content less than or equal to 0.0015 percent.
Further, the mass fraction of S in the low-sulfur scrap steel is less than or equal to 0.0050%.
Further, the auxiliary materials comprise at least one of lime, light-burned dolomite and fluorite; the mass fraction of S in the auxiliary material is less than or equal to 0.0050%.
Further, the smelting molten steel comprises the following components in parts by mass: less than or equal to 0.030 percent of C, less than or equal to 0.015 percent of Si, less than or equal to 0.0060 percent of S and less than or equal to 480ppm of O.
Further, tapping the smelting molten steel to obtain tapped molten steel, which specifically comprises the following steps:
tapping the smelting molten steel, and adding 1.0-2.5 kg/t of aluminum particles into the tapping steel for strong deoxidation to obtain tapping molten steel; and after tapping, adding 0.3-0.5 kg/t of aluminum particles into the slag surface of the tapped molten steel for slag surface deoxidation.
Further, the low-carbon low-silicon ultra-low sulfur refined molten steel comprises the following components in parts by mass: al: 0.015-0.025 percent of the total weight of the alloy, and less than or equal to 0.0020 percent of S.
Further, the refining final slag comprises the following components in parts by mass: CaO: 40-48% of SiO2：5～8％、Al2O3：18～24％、(FeO+MnO)≤1.0％。
Furthermore, the carbon content in the refining is less than or equal to 0.015 percent, and the silicon content is less than or equal to 0.02 percent.
Further, the adding amount of the refining slag is controlled to be 6-10 kg/t steel; the refining slag is prepared fromThe mass fraction comprises the following components: CaO 75-90%, SiO22-4% of MgO and 8-10% of MgO.
One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:
the invention provides a method for producing low-carbon low-silicon ultralow-sulfur steel by adopting an LF (ladle furnace) single-link process, which is characterized in that the LF single-link process is adopted, and the process parameters of each link in the smelting process are controlled (oxygen blowing is carried out in the smelting process, the oxygen blowing time is controlled to be 13-15 min, and the oxygen blowing amount is controlled to be 46-52 Nm3Controlling the oxygen lance position to be 1.5-1.7 m; argon gas of 600-800 NL/min is blown at the bottom in the initial slagging stage, and argon gas of 400-600 NL/min is blown at the bottom in the later heating stage), so that the carbon content of the steel can be controlled to be 0.030-0.050%, the silicon content is controlled to be not more than 0.050%, and the sulfur content is stably controlled to be not more than 0.0020%, smelting of low-carbon low-silicon ultralow-sulfur steel in a continuous casting and rolling production line is realized, and the requirements of industrialization and batch production of the steel are met.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
FIG. 1 is a flow chart of a method for producing low-carbon low-silicon ultra-low sulfur steel by using an LF single-link process according to an embodiment of the invention.
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:
according to an exemplary embodiment of the present invention, there is provided a method for producing a low-carbon low-silicon ultra-low sulfur steel using an LF single-pass process, as shown in fig. 1, including:
s1, carrying out desulfurization and slagging-off pretreatment on the molten iron to obtain pretreated molten iron;
s2, smelting the pretreated molten iron, low-sulfur steel scrap and auxiliary materials to obtain molten smelting steel; wherein oxygen blowing is carried out in the smelting, the oxygen blowing time is controlled to be 13-15 min, and the oxygen blowing amount is controlled to be 46-52 Nm3Controlling the oxygen lance position to be 1.5-1.7 m;
s3, tapping the smelting molten steel to obtain tapping molten steel;
s4, adding the molten steel into refining slag for refining to obtain low-carbon low-silicon ultra-low-sulfur refined molten steel and refined final slag; the refining comprises an initial slagging stage and a later heating stage, wherein 600-800 NL/min argon is blown to the bottom of the initial slagging stage, and 400-600 NL/min argon is blown to the bottom of the later heating stage, and the heating time is controlled to be less than or equal to 15 min.
According to the method for producing the low-carbon low-silicon ultralow-sulfur steel by adopting the LF single-link process, the LF single-link process is adopted, the process parameters of all links in the smelting process are controlled, the carbon content in the steel is controlled to be 0.030-0.050%, the silicon content is controlled to be less than or equal to 0.050%, and the sulfur content is stably controlled to be less than or equal to 0.0020%, so that the smelting of the low-carbon low-silicon ultralow-sulfur steel on a continuous casting and continuous rolling production line is realized, and the requirements of industrialization and batch production of the steel are met.
Oxygen blowing is carried out in the smelting process by a converter, andthe oxygen blowing time is controlled to be 13-15 min, and the oxygen blowing amount is controlled to be 46-52 Nm3The reason why the position of the oxygen lance is controlled to be 1.5-1.7 m for the steel/t is as follows: the oxygen blowing operation of the converter is to control the contents of C, Si and S in the smelting molten steel, and if the oxygen blowing time is less than 13min, the oxygen blowing amount is less than 46Nm3The steel/t, the oxygen lance position is less than 1.5m, and the C, S content in the steel can not meet the steel grade requirement; if the oxygen blowing time is more than 15min, the oxygen blowing amount is more than 52Nm3The oxygen lance position of the steel/t is more than 1.7m, the peroxidation of molten steel can be caused, and the difficulty of the subsequent process desulfurization is increased.
The reason that argon gas of 600-800 NL/min is blown at the bottom in the initial slagging stage and argon gas of 400-600 NL/min is blown at the bottom in the later heating stage is as follows: the stirring intensity of the molten steel is controlled by controlling the flow of bottom-blown argon, the scouring of the molten steel to the graphite electrode is reduced, the stirring intensity is reduced, the carbon increment in refining is controlled to be less than or equal to 0.015 percent, and the silicon increment is controlled to be less than or equal to 0.02 percent. If the low argon blowing flow rate in the initial slagging stage is less than 600NL/min, the bottom argon blowing flow rate in the later heating stage is less than 400NL/min, the flow rate is small, the stirring strength is weak, and molten steel desulphurization is not facilitated; if the flow of bottom-blown argon in the initial slagging stage is more than 800NL/min, the flow of bottom-blown argon in the later heating stage is more than 600NL/min, the flow in the initial stage is too large, and the temperature drop of the molten steel is not beneficial to desulfurization; the later bottom blowing flow is large, which is not beneficial to controlling the silicon content.
As an optional implementation manner, in the step S1, the molten iron is subjected to desulphurization and slagging-off pretreatment to obtain pretreated molten iron, which specifically includes:
carrying out desulfurization pretreatment on molten iron, and controlling the stirring time during the desulfurization pretreatment to be 10-15 min; and then removing top slag, wherein the bright surface rate of slag removal is more than or equal to 95 percent, and obtaining the pretreated molten iron with the S content less than or equal to 0.0015 percent. If the stirring time is less than 10min, the slagging-off bright surface rate is less than 95%, and the pretreated molten iron with the S content less than or equal to 0.0015% is difficult to obtain. Controlling the stirring time during the desulfurization pretreatment to be 10-15 min; if the stirring time is more than 15min, the temperature drop of the molten iron is increased, and the converter smelting is not favored due to insufficient heat.
As an optional embodiment, the mass fraction of S in the low-sulfur scrap steel is less than or equal to 0.0050%. The auxiliary materials comprise at least one of lime, light-burned dolomite and fluorite; the mass fraction of S in the auxiliary material is less than or equal to 0.0050%. Aiming at controlling the content of S in the smelting molten steel; more preferably, the sum of the mass fraction of S in the low-sulfur steel scrap and the mass fraction of S in the auxiliary materials is less than or equal to 0.0050 percent, and the S in the smelting molten steel is controlled to be less than or equal to 0.0060 percent;
oxygen blowing is carried out in the smelting, the oxygen blowing time is controlled to be 13-15 min, and the oxygen blowing amount is controlled to be 46-52 Nm3Controlling the oxygen lance position to be 1.5-1.7 m for the steel/t so as to control the contents of C, Si, S and O in the molten smelting steel, wherein the molten smelting steel comprises the following components in parts by mass: less than or equal to 0.030 percent of C, less than or equal to 0.015 percent of Si, less than or equal to 0.0060 percent of S and less than or equal to 480ppm of O.
As an optional implementation mode, tapping the molten smelting steel to obtain molten steel, specifically comprising:
tapping the smelting molten steel, and adding 1.0-2.5 kg/t of aluminum particles into the tapping steel for strong deoxidation to obtain tapping molten steel; and after tapping, adding 0.3-0.5 kg/t of aluminum particles into the slag surface of the tapped molten steel for slag surface deoxidation.
In the tapping process, if the adding amount of aluminum particles is less than 1kg/t of steel, the molten steel is not fully deoxidized, which is not beneficial to the occurrence of desulfurization reaction; if the adding amount of the aluminum particles is more than 2.5kg/t of steel, the waste of the deoxidizer can be caused; after the steel discharge is finished, if the adding amount of aluminum particles is less than 0.3kg/t of steel, the deoxidation of the slag surface is insufficient, which is not beneficial to the production of desulfurization products; if the addition amount of the aluminum particles is more than 0.5kg/t steel, the waste of the slag surface deoxidizer is caused.
As an optional implementation manner, argon gas of 600-800 NL/min is blown at the bottom of the initial slagging stage, argon gas of 400-600 NL/min is blown at the bottom of the later heating stage, and the electrode heating time in the later heating stage is controlled to be less than or equal to 15 min; according to the embodiment of the invention, the stirring intensity can be controlled and the electrode scouring is reduced by controlling the flow of bottom-blowing argon and the electrode heating time, so that the carburetion amount and the silicon increment amount are controlled, specifically: the carbureting amount in the refining is controlled to be less than or equal to 0.015 percent, and the siliconizing amount is controlled to be less than or equal to 0.02 percent.
As an alternative embodiment, the refining slagThe adding amount is controlled to be 6-10 kg/t steel; the refining slag comprises the following components in parts by mass: CaO 75-90%, SiO22-4% of MgO and 8-10% of MgO. The refining slag can be added to make the S in the steel]The element reacts with the slag, and the slag with high CaO component system can ensure enough free CaO and S in the refining process]Elements are fully reacted to produce stable desulfurization products CaS; meanwhile, the component system also ensures the good fluidity of the slag and is beneficial to the occurrence of desulfurization reaction. If the addition amount of the refining slag is less than 6kg/t of steel, the slag amount is small, and sufficient free CaO cannot be ensured, so that the desulfurization reaction is insufficient; if the addition amount of the refining slag is more than 10kg/t of steel, the added slag amount is too large, the CaO content in the slag is high, the fluidity of the slag is deteriorated, and the dynamic conditions of the reaction are influenced.
Through the above operations, the low-carbon low-silicon ultra-low sulfur refined molten steel finally comprises the following components in parts by mass: al: 0.015-0.025 percent of the total weight of the alloy, and less than or equal to 0.0020 percent of S.
The refining final slag comprises the following components in parts by mass: CaO: 40-48% of SiO2：5～8％、Al2O3: 18-24% and less than or equal to 1.0% of (FeO + MnO). The refining slag of the component can meet the requirement of deep desulfurization of molten steel, so that the molten steel can realize ultra-low sulfur control under the precondition of controlling carbon and silicon.
The method for producing the low-carbon low-silicon ultra-low sulfur steel by the LF single-link process is described in detail in the following by combining the examples, the comparative examples and the experimental data.
Example 1
The steel type SPHC has the target finished product with the carbon content of 0.030-0.050 percent, the silicon content of less than or equal to 0.050 percent and the sulfur content of less than or equal to 0.0020 percent, and adopts the smelting process route as follows: KR desulfurization pretreatment, converter smelting, LF furnace refining and continuous casting and rolling.
Step S1, controlling the stirring time during the desulfurization pretreatment to be 10 min; then, top slag is removed, the slag removal bright surface rate is 98 percent, and the pretreated molten iron with the S content of 0.0015 percent is obtained;
s2, smelting in a converter by adopting low-sulfur steel scraps and auxiliary materials, and controlling the total sulfur content of the steel scraps and the auxiliary materials to be less than or equal to0.0050%; smelting the pretreated molten iron, low-sulfur steel scrap and auxiliary materials to obtain molten smelting steel; wherein oxygen blowing is carried out in the smelting, the oxygen blowing time is controlled to be 13-15 min, and the oxygen blowing amount is controlled to be 46-52 Nm3Controlling the oxygen lance position to be 1.5-1.7 m; thereby controlling the smelting end point components of the converter to be: the carbon content is 0.025 percent, the silicon content is 0.010 percent, and the sulfur content is controlled to be 0.0050 percent; controlling the oxygen content at the end point of the converter to 430 ppm;
step S3, tapping the smelting molten steel to obtain tapping molten steel; aluminum strong deoxidation is adopted in tapping, and the adding amount is 2.0kg/t steel; after tapping, adding aluminum particles to the slag surface of the steel ladle for deoxidizing the slag surface, wherein the adding amount is 0.5kg/t steel;
s4, adding the molten steel into refining slag for refining to obtain low-carbon low-silicon ultra-low-sulfur refined molten steel and refined final slag; wherein the addition amount of the refining slag is controlled to be 6-10 kg/t steel; the refining slag comprises the following components in parts by mass: CaO 75-90%, SiO22-4% of MgO, 8-10% of MgO; the refining comprises an initial slagging stage and a later heating stage, wherein 600NL/min argon is blown from the bottom of the initial slagging stage, and in the later heating stage, 400NL/min argon is blown from the bottom, and the heating time is controlled for 15min so as to control the carbon increment in the refining process to be 0.012% and the silicon increment to be 0.015%; the sulfur content is 0.0012%.
Refining in steel to station [ Als]Controlling the concentration to be 0.015 percent; the content of the refining final slag is controlled to 48 percent of CaO and SiO 25% of Al2O324 percent and 0.80 percent of (FeO + MnO);
by adopting the LF single-link process and controlling the process parameters of each link in the smelting process, the carbon content in the steel is controlled to be 0.037%, the silicon content is controlled to be 0.022%, and the sulfur content is stably controlled to be 0.0012%, so that the smelting of the low-carbon low-silicon ultralow-sulfur steel of the continuous casting and rolling production line is realized, and the requirement of the industrial production of the steel grades is met.
Example 2
The steel type SPHC has the target finished product with the carbon content of 0.030-0.050 percent, the silicon content of less than or equal to 0.050 percent and the sulfur content of less than or equal to 0.0020 percent, and adopts the smelting process route as follows: KR desulfurization pretreatment, converter smelting, LF furnace refining and continuous casting and rolling.
Step S1, controlling the stirring time in the desulfurization pretreatment to be 15 min; then, removing top slag, wherein the slag removal bright surface rate is 95 percent, and the pretreated molten iron with the S content of 0.0015 percent is obtained;
s2, smelting in a converter by adopting low-sulfur steel scraps and auxiliary materials, and controlling the total sulfur content of the steel scraps and the auxiliary materials to be less than or equal to 0.0050%; smelting the pretreated molten iron, low-sulfur steel scrap and auxiliary materials to obtain molten smelting steel; wherein oxygen blowing is carried out in the smelting, the oxygen blowing time is controlled to be 15min, and the oxygen blowing amount is controlled to be 52Nm3Controlling the oxygen lance position to be 1.5-1.7 m; thereby controlling the smelting end point components of the converter as follows: the carbon content is 0.030 percent, the silicon content is 0.015 percent, and the sulfur content is controlled to be 0.0050 percent; controlling the oxygen content at the end point of the converter to be 480 ppm;
step S3, tapping the smelting molten steel to obtain tapping molten steel; aluminum strong deoxidation is adopted in tapping, and the adding amount is 2.5kg/t steel; after tapping, adding aluminum particles to the slag surface of the steel ladle for deoxidizing the slag surface, wherein the adding amount is 0.3kg/t steel;
s4, adding the molten steel into refining slag for refining to obtain low-carbon low-silicon ultra-low-sulfur refined molten steel and refined final slag; wherein the addition amount of the refining slag is controlled to be 6-10 kg/t steel; the refining slag comprises the following components in parts by mass: CaO 75-90%, SiO22-4% of MgO, 8-10% of MgO; the refining comprises an initial slagging stage and a later heating stage, wherein argon gas of 800NL/min is blown at the bottom of the initial slagging stage, and in the later heating stage, argon gas of 600NL/min is blown at the bottom, and the heating time is controlled for 15min so as to control the carbon increment in the refining process to be 0.012 percent and the silicon increment to be 0.015 percent; the sulfur content is 0.0012%.
Refining in steel to station [ Als]Controlling the concentration at 0.025%; the final slag composition in refining is controlled to 42% CaO and SiO28% of Al2O318 percent and 0.65 percent of (FeO + MnO);
by adopting the LF single-link process and controlling the process parameters of all links in the smelting process, the carbon content in the steel is controlled to be 0.045%, the silicon content is controlled to be 0.035%, and the sulfur content is stably controlled to be 0.0020%, so that the smelting of the low-carbon low-silicon ultralow-sulfur steel of the continuous casting and rolling production line is realized, and the requirement of the industrial production of the steel grades is met.
Example 3
The SPA steel product has the carbon content of 0.025-0.045%, the silicon content of less than or equal to 0.040% and the sulfur content of less than or equal to 0.0020%, and adopts a smelting process route which comprises the following steps: KR desulfurization pretreatment, converter smelting, LF furnace refining and continuous casting and rolling.
Step S1, controlling the stirring time during the desulfurization pretreatment to be 12 min; then, removing top slag, wherein the slag removal bright surface rate is 96 percent, and the pretreated molten iron with the S content of 0.0015 percent is obtained;
s2, smelting in a converter by adopting low-sulfur steel scraps and auxiliary materials, and controlling the total sulfur content of the steel scraps and the auxiliary materials to be less than or equal to 0.0050%; smelting the pretreated molten iron, low-sulfur steel scrap and auxiliary materials to obtain molten smelting steel; wherein oxygen blowing is carried out in the smelting, the oxygen blowing time is controlled to be 14min, and the oxygen blowing amount is controlled to be 50Nm3The steel/t, the oxygen lance position is controlled at 1.6 m; thereby controlling the smelting end point components of the converter as follows: the carbon content is 0.030 percent, the silicon content is 0.010 percent, and the sulfur content is controlled to be 0.0060 percent; controlling the oxygen content at the end point of the converter to be 480 ppm;
step S3, tapping the smelting molten steel to obtain tapping molten steel; aluminum strong deoxidation is adopted in tapping, and the adding amount is 2.2kg/t steel; after tapping, adding aluminum particles to the slag surface of the steel ladle for deoxidizing the slag surface, wherein the adding amount is 0.4kg/t steel;
s4, adding the molten steel into refining slag for refining to obtain low-carbon low-silicon ultra-low-sulfur refined molten steel and refined final slag; wherein the addition amount of the refining slag is controlled to be 6-10 kg/t steel; the refining slag comprises the following components in parts by mass: CaO 75-90%, SiO22-4% of MgO, 8-10% of MgO; the refining comprises an initial slagging stage and a later heating stage, wherein 700NL/min argon is blown to the bottom of the initial slagging stage, and 500NL/min argon is blown to the bottom of the later heating stage, and the heating time is controlled for 15min so as to control the carbon increment to be 0.012 percent and the silicon increment to be 0.020 percent in the refining process; the sulfur content is 0.0018%.
Refining in steel to station [ Als]Controlling the concentration to be 0.020%; the content of the refining final slag is controlled to be 40 percent of CaO and SiO26% of Al2O320 percent and 0.90 percent of (FeO + MnO);
by adopting the LF single-link process and controlling the process parameters of each link in the smelting process, the carbon content in the steel can be controlled to be 0.042%, the silicon content can be controlled to be 0.030%, and the sulfur content can be stably controlled to be 0.0018%, so that the smelting of the low-carbon low-silicon ultralow-sulfur steel of the continuous casting and rolling production line is realized, and the requirement of the industrial production of the steel grades is met.
Comparative example 1
The comparative example changes the 'refining process by an LF furnace' in the example 1 into 'argon blowing process'; the specific method comprises the following steps:
controlling the sulfur content in the molten iron to be 0.005% by adopting the blowing particle magnesium molten iron desulphurization pretreatment process; then adopting a slag skimming process;
controlling the tapping temperature and the bottom blowing strength by adopting the converter, so that the carbon content of the tapped steel is controlled to be 0.05 percent, and the carbon-oxygen product is controlled to be 0.0026 percent; slag blocking operation is adopted in tapping, slag is controlled to be discharged, a deoxidizer and premelting slag are added at the same time, and the slag amount is controlled within 5%;
performing argon blowing operation by using an advanced aluminum feeding wire, performing argon blowing stirring, controlling the liquid level rolling to be 200-300mm, and performing argon blowing stirring for 3-5 min;
the continuous casting process is adopted to protect casting and seal protection, the stopper rod and the long nozzle are subjected to argon blowing operation, and the loss of acid-soluble aluminum is controlled to be below 0.005%.
Comparative example 2
The method of this comparative example comprises:
carrying out desulfurization and slagging-off pretreatment on molten iron to obtain pretreated molten iron; the same as example 1;
smelting the pretreated molten iron, low-sulfur steel scrap and auxiliary materials to obtain molten smelting steel; wherein oxygen blowing is carried out in the smelting, the oxygen blowing time is controlled to be 10min, and the oxygen blowing amount is controlled to be 40Nm3The steel is treated by the method, wherein the position of an oxygen lance is controlled to be 1 m;
tapping the smelting molten steel to obtain tapped molten steel; the same as example 1;
adding the molten steel into refining slag for refining to obtain low-carbon low-silicon ultralow-sulfur refined molten steel and refined final slag; the refining comprises an initial slagging stage and a later heating stage, wherein 500NL/min argon is blown to the bottom of the initial slagging stage, and 300NL/min argon is blown to the bottom of the later heating stage, and the heating time is controlled to be 15 min.
Comparative example 3
The method of this comparative example comprises:
carrying out desulfurization and slagging-off pretreatment on molten iron to obtain pretreated molten iron;
smelting the pretreated molten iron, low-sulfur steel scrap and auxiliary materials to obtain molten smelting steel; wherein oxygen blowing is carried out in the smelting, the oxygen blowing time is controlled to be 18min, and the oxygen blowing amount is controlled to be 55Nm3The steel/t, the oxygen lance position is controlled at 1.8 m;
tapping the smelting molten steel to obtain tapped molten steel;
adding the molten steel into refining slag for refining to obtain low-carbon low-silicon ultralow-sulfur refined molten steel and refined final slag; the refining comprises an initial slagging stage and a later heating stage, wherein the initial slagging stage is subjected to bottom blowing of argon gas at 900NL/min, and in the later heating stage, the argon gas at 800NL/min is subjected to bottom blowing, and the heating time is controlled to be 20 min.
Experimental example 1
The process parameters for each example and each comparative example are tabulated in table 1.
TABLE 1
Figure BDA0002938713400000091
Figure BDA0002938713400000101
The compositions of the low-carbon, low-silicon and ultra-low-sulfur refined molten steels obtained in the examples and comparative examples are shown in Table 2.
TABLE 2
Group of The content of C is wt% Si content wt% The S content is wt%
Example 1 0.037％ 0.022％ 0.0012％
Example 2 0.045％ 0.035％ 0.0020％
Example 3 0.0042％ 0.0030％ 0.0018％
Comparative example 1 0.03％-0.060％ ≤0.03％ ≤0.015％
Comparative example 2 0.06％-0.10％ ≤0.05％ ≤0.010％
Comparative example 3 - ≤0.05％ 0.0038％-0.0060％
From the data in table 2, it can be seen that:
in comparative example 1, there is a disadvantage that silicon control operation can be performed only on the premise of high sulfur and low silicon control under the condition of ultra low sulfur cannot be satisfied; meanwhile, the argon blowing process adopted in the comparison is simple and does not have the defect of common popularization;
in the comparative example 2, in the refining process, parameters are not in the range of the invention, the defect of single process exists, the problem of silicon increase of molten steel is solved only by adopting single LF furnace control, the requirements of low carbon and ultra-low sulfur are realized while silicon control is difficult to ensure, and therefore, the carbon content and the sulfur content are higher.
In the comparative example 3, in the smelting and refining process, the parameters are out of the range of the invention, and the defect of high sulfur content control on the premise of silicon control exists, so that the process can not meet the requirements of ultralow sulfur smelting while achieving low carbon and low silicon.
In examples 1 to 3, low carbon, low silicon and ultra low sulfur having a carbon content of 0.030 to 0.050%, a silicon content of 0.05% or less and a sulfur content of 0.0020% or less;
in conclusion, by adopting the LF single-link process and controlling the process parameters of all links in the smelting process, the carbon content in the steel can be controlled to be 0.030-0.050%, the silicon content is controlled to be less than or equal to 0.050%, and the sulfur content is stably controlled to be less than or equal to 0.0020%, so that the smelting of the low-carbon low-silicon ultralow-sulfur steel of the continuous casting and rolling production line is realized, and the requirements of industrialization and batch production of the steel types are met. The comparative example shows that any link is not well controlled, and the low-carbon low-silicon ultralow-sulfur steel cannot be prepared.
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 for producing low-carbon low-silicon ultralow-sulfur steel by adopting an LF (ladle furnace) single-link process is characterized by comprising the following steps of:
carrying out desulfurization and slagging-off pretreatment on molten iron to obtain pretreated molten iron;
smelting the pretreated molten iron, low-sulfur steel scrap and auxiliary materials to obtain molten smelting steel; wherein oxygen blowing is carried out in the smelting, the oxygen blowing time is controlled to be 13-15 min, and the oxygen blowing amount is controlled to be 46-52 Nm3Controlling the oxygen lance position to be 1.5-1.7 m;
tapping the smelting molten steel to obtain tapped molten steel;
adding the molten steel into refining slag for refining to obtain low-carbon low-silicon ultralow-sulfur refined molten steel and refined final slag; the refining comprises an initial slagging stage and a later heating stage, wherein 600-800 NL/min argon is blown to the bottom of the initial slagging stage, and 400-600 NL/min argon is blown to the bottom of the later heating stage, and the heating time is controlled to be less than or equal to 15 min.
2. The method for producing the low-carbon low-silicon ultralow-sulfur steel by the LF single-link process according to claim 1, wherein the molten iron is subjected to desulphurization and slagging-off pretreatment to obtain pretreated molten iron, and the method specifically comprises the following steps:
carrying out desulfurization pretreatment on molten iron, and controlling the stirring time during the desulfurization pretreatment to be 10-15 min; and then removing top slag, wherein the bright surface rate of slag removal is more than or equal to 95 percent, and obtaining the pretreated molten iron with the S content less than or equal to 0.0015 percent.
3. The method for producing the low-carbon low-silicon ultralow-sulfur steel by the LF single-link process as claimed in claim 1, wherein the mass fraction of S in the low-sulfur scrap steel is less than or equal to 0.0050%.
4. The method for producing the low-carbon low-silicon ultralow-sulfur steel by the LF single-link process as claimed in claim 1, wherein the auxiliary materials comprise at least one of lime, light-burned dolomite and fluorite; the mass fraction of S in the auxiliary material is less than or equal to 0.0050%.
5. The method for producing the low-carbon low-silicon ultralow-sulfur steel by the LF single-link process as claimed in claim 1, wherein the molten smelting steel comprises the following components in parts by mass: less than or equal to 0.030 percent of C, less than or equal to 0.015 percent of Si, less than or equal to 0.0060 percent of S and less than or equal to 480ppm of O.
6. The method for producing the low-carbon low-silicon ultralow-sulfur steel by the LF single-link process as claimed in claim 1, wherein tapping the molten smelting steel to obtain molten tapping steel specifically comprises:
tapping the smelting molten steel, and adding 1.0-2.5 kg/t of aluminum particles into the tapping steel for strong deoxidation to obtain tapping molten steel; and after tapping, adding 0.3-0.5 kg/t of aluminum particles into the slag surface of the tapped molten steel for slag surface deoxidation.
7. The method for producing the low-carbon low-silicon ultra-low sulfur steel by the LF single-link process as claimed in claim 1, wherein the low-carbon low-silicon ultra-low sulfur refined molten steel comprises the following components in parts by mass: al: 0.015-0.025 percent of the total weight of the alloy, and less than or equal to 0.0020 percent of S.
8. The method for producing the low-carbon low-silicon ultralow-sulfur steel by the LF single-link process as claimed in claim 1, wherein the refined final slag comprises the following components in parts by mass: CaO: 40-48% of SiO2：5～8％、Al2O3：18～24％、(FeO+MnO)≤1.0％。
9. The method for producing the low-carbon low-silicon ultralow-sulfur steel by the LF single-link process as claimed in claim 1, wherein the carbon content in the refining is less than or equal to 0.015 percent, and the silicon content is less than or equal to 0.02 percent.
10. The method for producing the low-carbon low-silicon ultralow-sulfur steel by the LF single-link process as claimed in claim 1, wherein the addition amount of the refining slag is controlled to be 6-10 kg/t steel; the refining slag comprises the following components in parts by mass: CaO 75-90%, SiO22-4% of MgO and 8-10% of MgO.
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