CN116949346A - Method for improving submerged bubbles of welding wire steel continuous casting billet - Google Patents

Method for improving submerged bubbles of welding wire steel continuous casting billet Download PDF

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Publication number
CN116949346A
CN116949346A CN202311197160.5A CN202311197160A CN116949346A CN 116949346 A CN116949346 A CN 116949346A CN 202311197160 A CN202311197160 A CN 202311197160A CN 116949346 A CN116949346 A CN 116949346A
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continuous casting
steel
slag
less
equal
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吴锦圆
彭梦都
时彤彤
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Jiangsu Yonggang Group Co Ltd
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Jiangsu Yonggang Group Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • 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
    • B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
    • 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
    • B22D11/005—Continuous casting of metals, i.e. casting in indefinite lengths of wire
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/30—Regulating or controlling the blowing
    • C21C5/35—Blowing from above and through the bath
    • 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
    • C21C7/0075—Treating in a ladle furnace, e.g. up-/reheating of molten steel within the ladle
    • 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
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • 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 improving submerged bubbles of a welding wire steel continuous casting billet, which relates to the technical field of steel smelting and comprises the following steps: molten iron pretreatment, converter, LF refining, continuous casting and blank forming, and controlling the nitrogen content of the finished product to be 40x10 ‑6 The following are the followingThe oxygen content is controlled to be 35x10 ‑6 The argon is required to be used for blowing the tundish before casting, the argon is used for protecting casting in the whole continuous casting process, the long water gap and the externally-hung water gap are kept vertical, and the nitrogen loading amount is controlled to be 5x10 ‑6 The following is given. The continuous casting billet obtained by the method has few submerged bubble defects, the liquid level in the continuous casting and drawing process is stable, the problem of abnormal billet cutting waste due to flocculation flow is avoided, the molten steel has stronger castability, and the billet forming rate reaches 90% -95%.

Description

Method for improving submerged bubbles of welding wire steel continuous casting billet
Technical Field
The invention relates to the technical field of steel smelting, in particular to a method for improving submerged bubbles of a welding wire steel continuous casting blank.
Background
A welding bar steel refers to a steel material for an electrode. The welding bar steel has the biggest characteristics that the chemical components of the wire rod must be ensured to meet the requirements of various standard components, the deviation of the chemical components is not allowed, the control range of smelting components is narrower than the standard range, and the sulfur and phosphorus contents are lower. The carbon content in the welding wire is increased, the crack tendency of the welding seam is increased, the impact toughness is reduced, but the too low carbon content can lead to the excessive softness of the welding wire, difficult extrusion of welding flux and insufficient metal strength of the welding seam.
With the improvement of welding technology and automation degree, the welding wire has been widely applied to the manufacturing industries such as automobile manufacturing, shipbuilding, bridges, industrial machinery and the like. In the smelting of low-silicon low-carbon manganese deoxidized killed steel for welding wires, as the content of dissolved oxygen balanced with manganese in molten steel is high, ferromanganese is adopted for deoxidization, and a large amount of manganese oxide exists in slag, the deoxidization is difficult in the LF refining process, and the molten steel is easy to form subcutaneous bubble quality defects. After the aluminum deoxidizer is added, once the aluminum content is excessive, the castability of molten steel is deteriorated, the blank forming rate of a casting blank is affected, and when the casting blank is serious, the casting is stopped due to flocculation, so that production faults are caused. The method has the advantages that the defect of no subcutaneous bubble of the casting blank is achieved, the good castability (fluidity) of the molten steel is ensured, and the method is a problem to be solved in the production of the welding wire steel continuous casting blank.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention provides a method for improving the bubbles under the skin of a continuous casting blank of welding wire steel, the obtained continuous casting blank has few bubbles under the skin, the liquid level is stable in the process of continuous casting and steel drawing, the problems of abnormal flocculation flow and blank cutting waste are avoided, and the molten steel has stronger castability.
The present invention achieves the above technical object by the following means.
A method for improving submerged bubbles of a welding wire steel continuous casting billet comprises the following steps:
and (3) molten iron pretreatment: selecting molten iron with the chemical components of less than or equal to 0.03% of Si, 0.4-0.5% of Mn, less than or equal to 0.02% of Cu, less than or equal to 0.02% of Cr, less than or equal to 0.040% of Ni, and treating the sulfur content of the molten iron to be less than 0.005%, wherein slag skimming is carried out before desulfurization, the adding amount of a desulfurizing agent is added according to 7-9.5 kg/tFe, and stirring time is 10-15 min;
and (3) a converter: adding high-quality scrap steel, adding the pretreated molten iron into a converter furnace, performing top blowing oxygen with the strength of 2.5-2.8 Nm for 2/t.min, performing bottom blowing argon blowing, performing low blowing argon with the strength of 0.04-0.08 Nm for 0/t.min, and adding lime, light burned dolomite, fluorite and sinter slag by adopting a double slag method; controlling the temperature range of molten steel to 1630-1660 ℃ in molten steel in a furnace to be C0.04-0.06%, mn less than or equal to 0.05%, S less than or equal to 0.012% and P less than or equal to 0.010% during tapping, and measuring the oxygen activity of molten steel in the furnace; in the tapping process, according to the oxygen determination result of molten steel in a furnace, a Fe-Mn-A1 deoxidizer is adopted for deoxidizing, 1.5-2 kg of lime slag is added into two thirds of the ton of steel during tapping, slag blocking operation is adopted, and 0.8-1 kg of a static aid is added into the ton of steel after tapping;
refining in an LF furnace: 3-4 kg of lime is added into ton of steel before electrifying, strong stirring is carried out for 2-3 minutes, after desulfurization, electrifying is carried out, heating is carried out, lime and synthetic slag are added for slagging, fe-Mn-A1 is intermittently added for diffusion deoxidization to produce reducing slag for desulfurization, S in the steel is required to be less than or equal to 0.010% after refining is finished, and the temperature of molten steel is 1650-1660 ℃;
continuous casting into billets: the initial furnace casting temperature is controlled to 1610-1620 ℃, and finally the superheat degree of the tundish is controlled to 20-35 ℃; the temperature of the continuous casting heat is controlled to be 1570-1580 ℃ and the pulling speed is 2.2-2.6 m/min; and (3) casting 160 a continuous casting square billet of the molten steel subjected to LF refining by using a continuous casting process.
In the scheme, a double slag method is adopted in the converter, the primary slag pouring time is 30% -35% of the total oxygen blowing amount, the temperature of molten steel is controlled within the range of 1380 ℃ -1440 ℃, the alkalinity R of slag is controlled within the range of 1.8% -2.5, the Fe0 in slag is controlled within the range of 8% -15%, and the slag pouring rate is more than 50%.
In the scheme, in the continuous casting blank forming step, a long water gap is used for a ladle, an integral water gap and a carbon-free covering agent are used for a tundish, and a crystallizer is subjected to protective casting by adopting low-carbon covering slag; the crystallizer adopts electromagnetic stirring, and the crystallizer and secondary cooling adopt a forced cooling mode; the liquidus temperature of the molten steel is 1534 ℃, and the casting temperature is controlled to 1554 ℃ to 1574 ℃.
In the scheme, the tensile strength of the billet obtained in the continuous casting billet forming step is less than or equal to 520MPa, and the area reduction rate is more than 85 percent.
In the scheme, in the converter step, high-quality scrap steel with mass fraction S less than or equal to 0.010%, mn less than or equal to 0.35%, cu less than or equal to 0.02%, cr less than or equal to 0.02% and Ni less than or equal to 0.02% is added, and the scrap steel ratio is controlled according to 10% -15%.
In the scheme, the pulling speed in the continuous casting blank forming step is 2.4m/min.
In the scheme, in the continuous casting blank forming step, the nitrogen content of the finished product is controlled to be 40x10 -6 The oxygen content is controlled to be 35x10 -6 The argon is required to be used for blowing the tundish before casting, the argon is used for protecting casting in the whole continuous casting process, the long water gap and the externally-hung water gap are kept vertical, and the nitrogen loading amount is controlled to be 5x10 -6 The following is given.
In the scheme, the refining time of LF furnace refining is 30-50 min, and the reduction of silicon dioxide in slag after long-time steel waiting is prevented.
In the scheme, in the converter step, the oxygen activity of molten steel in the furnace is measured every 15-30 min.
The beneficial effects are that: 1. the Fe-Mn-A1 deoxidizer is adopted to replace an aluminum deoxidizer, so that the problems that the oxygen content is difficult to control and subcutaneous bubbles or nozzle knots are generated due to improper control because of aluminum deoxidization can be reduced.
2. The continuous casting billet obtained by the method has few submerged bubble defects, the liquid level in the continuous casting and drawing process is stable, the problem of abnormal billet cutting waste due to flocculation flow is avoided, the molten steel has stronger castability, and the billet forming rate reaches 90% -95%.
3. The following three problems exist in the prior production process of low-carbon and low-silicon welding wire steel. Firstly, as the components of the welding wire steel play a decisive role in the performance, the components of carbon, nitrogen and chromium have no component allowance deviation, and once the components are not contained, the waste can be judged; secondly, the quality defect of bubbles under the skin of the continuous casting billet is overcome; finally, under the condition of flocculating water gap blocking in the continuous casting steel pouring process, the blank corresponding to the liquid level fluctuation range exceeding 10mm of the soil is completely cut and discarded, the blank forming rate is only 85 percent, and when the blank forming rate is more serious, the blank forming rate is more serious because ofThe water blocking opening of the flocculation flow causes the continuous casting machine to stop casting unplanned, and brings great obstacle to production. The invention summarizes the problems and optimizes the process: the core is that molten iron sulfur is treated to be below 0.005% by using a molten iron pretreatment technology, so that the sulfur content of the end point of the converter is ensured to be about 0.010%; the converter smelting technology is utilized to control the carbon content of the tapping end point to be not more than 0.05 percent, and the oxygen content of the end point to be 35X10 -6 The aluminum deoxidizer is not added in the whole smelting process, fe-Mn-A1 is used for deoxidizing, and no molten steel is exposed; and once the long nozzle and the external nozzle are skewed, gaps are reserved, and air is easy to infiltrate to cause secondary oxidization of molten steel.
Drawings
FIG. 1 is a photograph of a low-magnification photograph of comparative example 1 with submerged bubbles at a level of 3.0 for hot pickling;
FIG. 2 is a photograph of a low-magnification photograph of example 1 with submerged bubbles grade 0 heat pickling;
FIG. 3 is a photograph of comparative example 2 of a submerged bubble grade 3.0 heat acid wash low magnification;
FIG. 4 is a photograph of a low-magnification thermal acid wash of example 2, skin bubble grade 0.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The following examples are illustrative and are intended to be illustrative of the invention and are not to be construed as limiting the invention.
And (3) molten iron pretreatment: selecting molten iron with the chemical components of less than or equal to 0.03% of Si, 0.4-0.5% of Mn, less than or equal to 0.02% of Cu, less than or equal to 0.02% of Cr, less than or equal to 0.040% of Ni, and treating the sulfur content of the molten iron to be less than 0.005%, wherein slag skimming is carried out before desulfurization, the adding amount of a desulfurizing agent is added according to 7-9.5 kg/tFe, and stirring time is 10-15 min;
and (3) a converter: adding high-quality scrap steel, adding the pretreated molten iron into a converter furnace, performing top blowing oxygen with the strength of 2.5-2.8 Nm for 2/t.min, performing bottom blowing argon blowing, performing low blowing argon with the strength of 0.04-0.08 Nm for 0/t.min, and adding lime, light burned dolomite, fluorite and sinter slag by adopting a double slag method; controlling the content of C in the molten steel in the furnace to be 0.04% -0.06%, mn to be less than or equal to 0.05%, S to be less than or equal to 0.012% and P to be less than or equal to 0.010% during tapping, controlling the temperature range of the molten steel to be 1630 ℃ -1660 ℃, and measuring the oxygen activity of the molten steel in the furnace; in the tapping process, according to the oxygen determination result of molten steel in a furnace, a Fe-Mn-A1 deoxidizer is adopted for deoxidizing, 1.5-2 kg of lime slag is added into two thirds of the ton of steel during tapping, slag blocking operation is adopted, and 0.8-1 kg of a static aid is added into the ton of steel after tapping;
refining in an LF furnace: 3-4 kg of lime is added into ton of steel before electrifying, strong stirring is carried out for 2-3 minutes, after desulfurization, electrifying is carried out, heating is carried out, lime and synthetic slag are added for slagging, fe-Mn-A1 is intermittently added for diffusion deoxidization to produce reducing slag for desulfurization, S in the steel is required to be less than or equal to 0.010% after refining is finished, and the temperature of molten steel is 1650-1660 ℃;
continuous casting into billets: the initial furnace casting temperature is controlled to 1610-1620 ℃, and finally the superheat degree of the tundish is controlled to 20-35 ℃; the temperature of the continuous casting heat is controlled to be 1570-1580 ℃ and the pulling speed is 2.2-2.6 m/min; and (3) casting 160 a continuous casting square billet of the molten steel subjected to LF refining by using a continuous casting process.
Comparative example 1: refining in an LF furnace: no Fe-Mn-A1 is added for diffusion deoxidation to produce reducing slag for desulfurization; the other steps are the same as in example 1, and the obtained continuous casting billet comprises the following chemical components in percentage by mass: 0.04% of C, 0.05% of Si, 0.057% of Mn, 0.07% of P, 0.0083% of S, 0.001% of Al, 0.015% of Cu, 0.018% of Cr, 0.004% of Ni and 125x 10% of oxygen -6 。
Example 1: this example is used to illustrate the method for improving submerged blister of continuous casting blank of welding wire steel provided by the invention.
And (5) molten iron pretreatment. Molten iron with the chemical components of Mn0.40%, cu0.012%, cr0.02%, ni0.02% and S0.040% is pretreated and desulfurized by a method of blowing granular magnesium, the sulfur content of the molten iron is treated to be less than 0.005%, slag is removed before desulfurization is needed, the addition amount of a desulfurizing agent is added according to 7 kg/t-9.5 kg/tFe, and stirring time is 10min;
a converter. Adding high-quality scrap steel: adding high-quality scrap steel with the mass fractions of S0.010%, mn0.35%, cu0.02%, cr0.02% and Ni0.02%, controlling the scrap steel ratio to be 10% -15%, adding pretreated molten iron into a converter furnace, performing top-blown oxygen with the strength of 2.5 Nm/t.min, performing bottom-blown argon blowing, performing low-blown argon with the strength of 0.04 Nm m/t.min, and adding lime, light-burned dolomite, fluorite and sinter slag-making materials by adopting a double slag method; controlling the temperature range of C0.04%, mn0.05%, S0.012% and P0.010% in molten steel in a furnace during tapping, and measuring the oxygen activity of the molten steel in the furnace at 1630-1660 ℃; in the tapping process, according to the oxygen determination result of molten steel in a furnace, a Fe-Mn-A1 deoxidizer is adopted for deoxidizing, 1.5-2 kg of lime slag is added into two thirds of the ton of steel during tapping, slag blocking operation is adopted, and 0.8-1 kg of a static aid is added into the ton of steel after tapping;
refining in an LF furnace: 3-4 kg of lime is added into ton of steel before electrifying, strong stirring is carried out for 2-3 minutes, after desulfurization, electrifying is carried out, heating is carried out, lime and synthetic slag are added for slagging, fe-Mn-A1 is intermittently added for diffusion deoxidization to produce reducing slag for desulfurization, S in the steel is required to be less than or equal to 0.010% after refining is finished, and the temperature of molten steel is 1650-1660 ℃;
continuous casting into billets: the initial furnace casting temperature is controlled to 1610-1620 ℃, and finally the superheat degree of the tundish is controlled to 20-35 ℃; the temperature of the continuous casting heat is controlled to 1570-1580 ℃ and the pulling speed is 2.4m/min; and (3) casting 160 a continuous casting square billet of the molten steel subjected to LF refining by using a continuous casting process.
Pouring by a 160mm multiplied by 160mm section billet continuous casting machine, sleeving a long water gap with a large ladle drain gap, protecting and pouring by a tundish integral water gap, starting a crystallizer for electromagnetic stirring by using a carbonless covering agent and low-carbon covering slag, setting the frequency of the crystallizer to be 3Hz, setting the current to be 300A, and setting the molten steel range of the tundish to be 1555-1570 ℃ and the pulling speed range to be 2.4m/min in the pouring process. And continuously casting to obtain the bubble-free billet.
The method comprises the following steps: the continuous casting blank comprises the following chemical components in percentage by mass: 0.04% of C, 0.05% of Si, 0.057% of Mn, 0.07% of P, 0.0083% of S, 0.002% of Al, 0.015% of Cu, 0.018% of Cr, 0.004% of Ni and 30x 10% of oxygen -6 。
Comparative example 2: LF furnace refining does not add Fe-Mn-A1 to carry out diffusion deoxidation to produce reducing slag desulfurization; the other steps are the same as in example 2, and the obtained continuous casting billet comprises the following chemical components in percentage by mass: 0.004% of C, 0.05% of Si, 0.050% of Mn, 0.007% of P, 0.0083% of S, 0.015% of Al, 0.015% of Cu, 0.018% of Cr, 0.004% of Ni and 100x 10% of oxygen -6 。
Example 2
And (5) molten iron pretreatment. Molten iron with the chemical components of Mn0.50%, cu0.02%, cr0.02%, ni0.02% and S0.040% is pretreated and desulfurized by a method of blowing granular magnesium, the sulfur content of the molten iron is treated to be less than 0.005%, slag is removed before desulfurization is needed, the addition amount of a desulfurizing agent is added according to 7 kg/t-9.5 kg/tFe, and stirring time is 20min;
a converter. Adding high-quality scrap steel: adding high-quality scrap steel with the mass fractions of S0.010%, mn0.30%, cu0.02%, cr0.02% and Ni0.02%, controlling the scrap steel ratio to be 10% -15%, adding pretreated molten iron into a converter furnace, performing top-blown oxygen with the strength of 2.5 Nm/t.min, performing bottom-blown argon blowing, performing low-blown argon with the strength of 0.04 Nm m/t.min, and adding lime, light-burned dolomite, fluorite and sinter slag-making materials by adopting a double slag method; controlling the temperature range of C0.04%, mn0.05%, S0.012% and P0.010% in molten steel in a furnace during tapping, and measuring the oxygen activity of the molten steel in the furnace at 1630-1660 ℃; in the tapping process, according to the oxygen determination result of molten steel in a furnace, a Fe-Mn-A1 deoxidizer is adopted for deoxidizing, 1.5-2 kg of lime slag is added into two thirds of the ton of steel during tapping, slag blocking operation is adopted, and 0.8-1 kg of a static aid is added into the ton of steel after tapping;
refining in an LF furnace: 3-4 kg of lime is added into ton of steel before electrifying, strong stirring is carried out for 2-3 minutes, after desulfurization, electrifying is carried out, heating is carried out, lime and synthetic slag are added for slagging, fe-Mn-A1 is intermittently added for diffusion deoxidization to produce reducing slag for desulfurization, S in the steel is required to be less than or equal to 0.010% after refining is finished, and the temperature of molten steel is 1650-1660 ℃;
continuous casting into billets: the initial furnace casting temperature is controlled to 1610-1620 ℃, and finally the superheat degree of the tundish is controlled to 20-35 ℃; the temperature of the continuous casting heat is controlled to 1570-1580 ℃ and the pulling speed is 2.6m/min; and (3) casting 160 a continuous casting square billet of the molten steel subjected to LF refining by using a continuous casting process.
Casting by using a 160mm multiplied by 160mm section billet continuous casting machine, sleeving a long water gap with a large ladle of a lower water gap, protecting and casting by using a tundish integral water gap, starting a crystallizer electromagnetic stirring device by using a carbonless covering agent and low-carbon covering slag, setting the frequency of the crystallizer electromagnetic stirring device to be 3Hz, setting the current to be 300A, and setting the tundish molten steel range at 1550-1568 ℃ and the pulling speed range at 2.4+/-0.2 m/min in the casting process.
The continuous casting blank comprises the following chemical components in percentage by mass: c0.004%, si0.05%, mn0.050%, P0.007%, S0.0083%, al0.002%, cu0.015%, cr0.018%, ni0.004%, and oxygen 25x10 -6 。
From the mass fractions of the chemical components of the continuous casting billets obtained in example 1 and example 2, it can be seen that: the oxygen content is not more than 35x10 -6 。
FIGS. 1 and 3 are comparative examples 1 and 2, respectively, and the detected subcutaneous bubble level is 3.0, and it can be seen from FIGS. 1 and 3 that the pit-like crack defects exist at the outer edge of the pickling cross section of the continuous casting blank as bubbles.
FIGS. 2 and 4 show examples 1 and 2, respectively, and the detected subcutaneous bubble level is 0, and it can be seen from FIGS. 2 and 4 that no obvious crack defects are found in the pickling cross section of the continuous casting billet.
Comparative example 1, comparative example 2 and examples 1 and 2 were each examined for macroscopical microstructure in a continuous casting billet according to YB/T153 and acid-leached with hydrochloric acid at 70-80℃for 1-2 hours, examples 1 and 2 having subcutaneous and internal bubbles on the acid-leached macroscopically low-magnification test piece.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Although embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives, and variations may be made in the above embodiments by those skilled in the art without departing from the spirit and principles of the invention.

Claims (8)

1. The method for improving the submerged bubbles of the continuous casting billet of the welding wire steel is characterized by comprising the following steps of:
and (3) molten iron pretreatment: selecting molten iron with the chemical components of less than or equal to 0.03% of Si, 0.4-0.5% of Mn, less than or equal to 0.02% of Cu, less than or equal to 0.02% of Cr, less than or equal to 0.040% of Ni, and treating the sulfur content of the molten iron to be less than 0.005%, wherein slag skimming is carried out before desulfurization, the adding amount of a desulfurizing agent is added according to 8-9.5 kg/tFe, and stirring time is 10-15 min;
and (3) a converter: adding high-quality scrap steel, adding the pretreated molten iron into a converter furnace, performing top blowing oxygen with the strength of 2.5-2.8 Nm for 2/t.min, performing bottom blowing argon blowing, performing low blowing argon with the strength of 0.04-0.08 Nm for 0/t.min, and adding lime, light burned dolomite, fluorite and sinter slag by adopting a double slag method; controlling the temperature range of molten steel to 1630-1660 ℃ in molten steel in a furnace to be C0.04-0.06%, mn less than or equal to 0.05%, S less than or equal to 0.012% and P less than or equal to 0.010% during tapping, and measuring the oxygen activity of molten steel in the furnace; in the tapping process, according to the oxygen determination result of molten steel in a furnace, a Fe-Mn-A1 deoxidizer is adopted for deoxidizing, 1.5-2 kg of lime slag is added into two thirds of the ton of steel during tapping, slag blocking operation is adopted, and 0.8-1 kg of a static aid is added into the ton of steel after tapping;
refining in an LF furnace: 3-4 kg of lime is added into ton of steel before electrifying, strong stirring is carried out for 2-3 minutes, after desulfurization, electrifying is carried out, heating is carried out, lime and synthetic slag are added for slagging, fe-Mn-A1 is intermittently added for diffusion deoxidization to produce reducing slag for desulfurization, S in the steel is required to be less than or equal to 0.010% after refining is finished, and the temperature of molten steel is 1650-1660 ℃;
continuous casting into billets: the initial furnace casting temperature is controlled to 1610-1620 ℃, and finally the superheat degree of the tundish is controlled to 20-35 ℃; the temperature of the continuous casting heat is controlled to be 1570-1580 ℃ and the pulling speed is 2.2-2.6 m/min; casting 160X 160 continuous casting billets of the molten steel subjected to LF refining by using a continuous casting process; controlling the nitrogen content of the finished product to be 40x10 -6 The oxygen content is controlled to be 35x10 -6 The argon is required to be used for blowing the tundish before casting, the argon is used for protecting casting in the whole continuous casting process, the long water gap and the externally-hung water gap are kept vertical, and the nitrogen loading amount is controlled to be 5x10 -6 The following is given.
2. The method for improving submerged bubble of welding wire steel continuous casting billet according to claim 1, wherein a double slag method is adopted in a converter, the primary slag pouring time is 30% -35% of the total oxygen blowing amount, the temperature of molten steel is controlled within the range of 1380 ℃ -1440 ℃, the basicity of slag R is controlled within the range of 1.8% -2.5, the Fe0 in slag is controlled within the range of 8% -15%, and the slag pouring rate is more than 50%.
3. The method for improving submerged arc of a continuous casting wire steel billet according to claim 1, wherein the continuous casting and forming step comprises a long nozzle for a ladle, an integral nozzle for a tundish and a carbon-free covering agent, and the crystallizer is subjected to protective casting by using low-carbon covering slag; the crystallizer adopts electromagnetic stirring, and the crystallizer and secondary cooling adopt a forced cooling mode; the liquidus temperature of the molten steel is 1534 ℃, and the casting temperature is controlled to 1554 ℃ to 1574 ℃.
4. The method for improving the submerged arc of a continuous casting wire steel billet according to claim 1 wherein the tensile strength of the billet obtained in the continuous casting billet forming step is 520MPa or less and the reduction of area is >85%.
5. The method for improving submerged bubble of continuous casting billet of welding wire steel according to claim 1, wherein in the converter step, high-quality scrap steel is added, the mass fraction of S is less than or equal to 0.010%, the mass fraction of Mn is less than or equal to 0.35%, the mass fraction of Cu is less than or equal to 0.02%, the mass fraction of Cr is less than or equal to 0.02%, and the mass fraction of Ni is less than or equal to 0.02%, wherein the scrap steel ratio is controlled to 10% -15%.
6. The method for improving the submerged arc of a continuous casting wire steel billet in accordance with claim 1 wherein the draw rate in the continuous casting billet forming step is 2.4m/min.
7. The method for improving submerged in-arc bubbling of a continuous casting wire steel blank according to claim 1, wherein the refining time of the LF refining is 30 min-50 min, and the reduction of silicon dioxide in slag is prevented when the steel is left for a long time.
8. The method for improving submerged arc bubbling of a continuous casting wire steel blank according to claim 1, wherein in the converter step, the oxygen activity of molten steel in the furnace is measured every 15 to 30 minutes.
CN202311197160.5A 2023-09-18 2023-09-18 Method for improving submerged bubbles of welding wire steel continuous casting billet Pending CN116949346A (en)

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