CN113088818B - Ultra-high strength steel cord, wire rod for ultra-high strength steel cord and production method thereof - Google Patents

Ultra-high strength steel cord, wire rod for ultra-high strength steel cord and production method thereof Download PDF

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Publication number
CN113088818B
CN113088818B CN202110350315.9A CN202110350315A CN113088818B CN 113088818 B CN113088818 B CN 113088818B CN 202110350315 A CN202110350315 A CN 202110350315A CN 113088818 B CN113088818 B CN 113088818B
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wire rod
steel cord
strength steel
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CN113088818A (en
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麻晗
孙国才
沈奎
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Jiangsu Shagang Group Co Ltd
Jiangsu Shagang Iron and Steel Research Institute Co Ltd
Zhangjiagang Rongsheng Special Steel Co Ltd
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Jiangsu Shagang Group Co Ltd
Jiangsu Shagang Iron and Steel Research Institute Co Ltd
Zhangjiagang Rongsheng Special Steel 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
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/16—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling wire rods, bars, merchant bars, rounds wire or material of like small cross-section
    • 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
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/02—Dephosphorising or 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
    • C21C7/0025—Adding carbon material
    • 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
    • C21C7/064—Dephosphorising; Desulfurising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/002—Heat treatment of ferrous alloys containing Cr
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/008—Heat treatment of ferrous alloys containing Si
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
    • C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/525—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length for wire, for rods
    • 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
    • C22C33/06—Making ferrous alloys by melting using master alloys
    • 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
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • 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
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • 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
    • C22C38/008—Ferrous alloys, e.g. steel alloys containing tin
    • 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
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • 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
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/009—Pearlite
    • 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 an ultrahigh-strength steel cord, a wire rod for the ultrahigh-strength steel cord and a production method of the wire rod. The wire rod for the extra-high strength steel cord comprises the following chemical components in percentage by mass: 0.90-0.94% of C, 0.17-0.23% of Si, 0.35-0.48% of Mn, 0.17-0.23% of Cr, less than or equal to 0.001% of Ti, less than or equal to 0.0018% of Al, less than or equal to 0.005% of Sn, less than or equal to 0.005% of As, less than or equal to 0.005% of S, less than or equal to 0.0025% of O, less than or equal to 0.0020% of N, and the balance of Fe and other inevitable impurities; wherein, the content of Mn and Si satisfies: Mn/Si is 1.8-2.2; the diameter of the wire rod is 5.0-5.5 mm, the tensile strength is 1250-1350 MPa, the reduction of area is not less than 40%, the size of maximum inclusion is not more than 25 μm, the area ratio of sorbite and pearlite in a metallographic structure is not less than 99%, a monofilament with the diameter of 0.30mm can be drawn out, the tensile strength of the monofilament is 3750-3900 MPa, and then the ultrahigh-strength steel cord can be twisted. The production method comprises the working procedures of pretreatment, converter smelting, refining, continuous casting, cogging, high-speed wire rolling and temperature-controlled cooling, and the control of chemical components and proportion is combined, so that the center segregation can be reduced, the abnormal structure of the net-shaped carbide can be controlled, the tensile strength of the product can be improved, and the wire breakage rate can be reduced.

Description

Ultra-high strength steel cord, wire rod for ultra-high strength steel cord and production method thereof
Technical Field
The invention belongs to the technical field of steel smelting, and relates to a wire rod for an ultrahigh-strength steel cord, an ultrahigh-strength steel cord further processed by the wire rod for the ultrahigh-strength steel cord, and a production method of the wire rod for the ultrahigh-strength steel cord.
Background
The steel cord is a common rubber framework material and is widely applied to radial tires of various automobiles, trucks and airplanes. The automobile output and sale quantity and the automobile retention quantity in China are the first in the world, and along with the development of society and economy, people put higher requirements on the safety, comfort and low energy consumption of automobiles, so that tire products with smaller rolling resistance, lighter weight and more wear resistance need to be developed. As an important framework of the tire, the steel cord plays a central role in tire load bearing, and increasing the tensile strength of the steel cord can reduce the weight of the tire and reduce the rolling resistance of the tire. In the national standard GB/T11181-2016 Steel cord for radial tires, four tensile strength grades of the steel cord are specified: normal strength (NT), high strength (HT), ultra-high Strength (ST), and ultra-high strength (UT).
At present, a wire rod with the diameter of 5.5mm is drawn into a filament with the diameter of 0.15-0.38 mm in the industry, and then the filament is twisted into a steel cord for use.
Disclosure of Invention
In order to solve at least one of the above-mentioned technical problems, an object of the present invention is to provide a wire rod for an ultra high strength steel cord, an ultra high strength steel cord further processed from the wire rod for an ultra high strength steel cord, and a method for producing the wire rod for an ultra high strength steel cord.
In order to achieve one of the above objects, an embodiment of the present invention provides a wire rod for an ultra-high strength steel cord, which comprises the following chemical components by mass percent: 0.90-0.94% of C, 0.17-0.23% of Si, 0.35-0.48% of Mn, 0.17-0.23% of Cr, less than or equal to 0.001% of Ti, less than or equal to 0.0018% of Al, less than or equal to 0.005% of Sn, less than or equal to 0.005% of As, less than or equal to 0.005% of S, less than or equal to 0.0025% of O, less than or equal to 0.0020% of N, and the balance of Fe and other inevitable impurities; wherein, the content of Mn and Si satisfies: Mn/Si is 1.8 to 2.2. The wire rod for the extra-high-strength steel cord can be used as a base material for producing the extra-high-strength steel cord with the diameter of 0.30mm and the tensile strength of 3750-3900 MPa.
The size, the strength, the inclusion type and the size, the plastic toughness, the mechanical property uniformity and the like of the wire rod for the ultra-high strength steel cord are controlled by controlling the chemical components and the mass percentage thereof, wherein the structure and the strength of the wire rod for the ultra-high strength steel cord are controlled by controlling the content of elements such as C, Si, Mn, Cr and the like in the wire rod, the generation of network cementite is effectively inhibited, the segregation of cementite in an austenite crystal boundary is weakened, and the stability of austenite is improved; controlling the element content of brittle inclusions generated by Ti, Al, O, N, S and the like so as to control the number and size of the inclusions and the drawing performance; the plasticity and toughness of the wire rod for the ultra-high strength steel cord is controlled by controlling the content of low-melting-point elements such As Sn and As which are easy to be segregated in the grain boundary; the content ratio of Si and Mn is controlled to control the inclusion in a low melting point region, so that the deformability of the wire rod for the ultrahigh-strength steel cord in the hot rolling and drawing processes is improved.
Preferably, the diameter of the wire rod for the ultrahigh-strength steel cord is 5.0-5.5 mm, the tensile strength is 1250-1350 MPa, the reduction of area is more than or equal to 40%, the ultrahigh-strength steel cord with higher strength and excellent drawing performance can be further prepared by drawing, and the higher requirement of the steel cord for the tire is met.
Preferably, the size of the largest inclusion of the wire rod for the ultrahigh-strength steel cord is less than or equal to 25 microns, and the area ratio of sorbite to pearlite in a metallographic structure is more than or equal to 99%, so that the structure of the wire rod for the ultrahigh-strength steel cord is uniform, the generation of network cementite and the segregation of cementite in an austenite crystal boundary are reduced, the stability of austenite is improved, and the generation of internal microcracks is reduced.
Accordingly, in order to achieve one of the above objects, an embodiment of the present invention further provides an ultra high strength steel cord prepared by using the wire rod for the ultra high strength steel cord as a base material.
Preferably, the ultra-high strength steel cord is formed by twisting monofilaments with the diameter of 0.30mm, the monofilaments are prepared by drawing the ultra-high strength steel cord by using a wire rod as a base material, the tensile strength of the monofilaments is 3750-3900 MPa, and the ultra-high strength steel cord not only meets the requirements on the diameter and the strength of the ultra-high strength (UT) steel cord in the national standard GB/T11181-2016 radial tire steel cord, but also can realize large-scale production.
Accordingly, in order to achieve one of the above objects, an embodiment of the present invention further provides a method for producing an ultra high strength steel cord, the method comprising the following steps performed in sequence:
pretreatment: desulfurizing the molten iron;
smelting in a converter: feeding the pretreated molten iron into a converter to be mixed with scrap steel to form molten steel, and carrying out desiliconization, dephosphorization and oxygen blowing decarburization, wherein the molten iron accounts for 82-88% of the molten steel, the tapping temperature of the molten steel is more than or equal to 1640 ℃, and the C in the molten steel is more than or equal to 0.05% during tapping;
refining: adjusting chemical components and temperature of molten steel smelted by the converter, and adjusting and controlling impurities in the molten steel by soft stirring, wherein the soft stirring time is more than or equal to 30min, and the flow of argon blown from the bottom of a steel ladle during soft stirring is 0.5-0.7L/min.t;
continuous casting: casting the molten steel obtained by refining into a continuous casting billet;
cogging: heating the obtained continuous casting billet by a heating furnace, and then continuously rolling and cogging the continuous casting billet into an intermediate billet;
high-speed wire rolling: rolling the obtained intermediate blank into a wire rod, wherein the wire rod comprises the following chemical components in percentage by mass: 0.90-0.94% of C, 0.17-0.23% of Si, 0.35-0.48% of Mn, 0.17-0.23% of Cr, less than or equal to 0.001% of Ti, less than or equal to 0.0018% of Al, less than or equal to 0.005% of Sn, less than or equal to 0.005% of As, less than or equal to 0.005% of S, less than or equal to 0.0025% of O, less than or equal to 0.0020% of N, and the balance of Fe and other inevitable impurities; wherein, the content of Mn and Si satisfies: Mn/Si is 1.8-2.2;
temperature control and cooling: and (3) carrying out temperature control cooling on the wire rod on a stelmor cooling line, wherein the spinning temperature is 900-920 ℃, the air quantity of a No. 1-4 fan is 100%, the rest fans are closed, and the average speed of a roller way is 72-75 m/min.
Thus, according to the production method of one embodiment of the invention, on one hand, the precise control of the chemical components of the wire rod for the extra-high strength steel cord is realized through the procedures of pretreatment, converter smelting, refining, continuous casting, cogging, high-speed wire rolling, temperature control cooling and the like, the center segregation is reduced, and the strength and the drawing performance are improved; on the other hand, the quantity and the size of the inclusions and the structure and the strength of the wire rod are controlled by controlling parameters such as the proportion of molten iron in molten steel, the tapping temperature, the tapping carbon content, the soft stirring, the stelmor controlled cooling and the like, the generation of netlike cementite is reduced, the generation of a martensite quenching structure is prevented, the finally prepared wire rod for the extra-high-strength steel cord has good drawing performance, the wire breakage rate in the drawing and twisting processes is reduced, and the monofilament strength of a finished product reaches an extra-high-strength level.
In a further improvement of an embodiment of the present invention, in the pretreatment step, the blast furnace hot metal is desulfurized in a KR desulfurization apparatus, and the blast furnace hot metal satisfies, before desulfurization: the temperature is more than or equal to 1360 ℃, the C is 4.0-4.5%, the S is less than or equal to 0.04%, the Si is 0.20-0.60%, the Ti is less than or equal to 0.04%, the P is less than or equal to 0.10%, and the balance is Fe and other inevitable impurities. The desulfurization effect of the pretreatment process can be ensured by optimizing the temperature and the components of the equipment and the blast furnace molten iron, and the low-Ti molten iron is adopted for smelting, so that the phenomenon that slag is discharged to cause Ti return can be effectively avoided, and further the phenomenon that fragile inclusions such as titanium oxide and titanium nitride are separated out in the continuous casting process is avoided.
In a further improvement of an embodiment of the present invention, in the pretreatment step, the molten iron is desulfurized until S in the molten iron is not more than 0.002%. The sulfur content in the molten iron is reduced to a lower level through the pretreatment process, slag entrapment or strong slag-metal reaction caused by a large amount of desulfurization in the subsequent refining process can be avoided, so that the generation of large-size inclusion in the molten steel is reduced, the type of the inclusion can be effectively controlled, and the size of the inclusion is reduced.
In a further improvement of an embodiment of the present invention, the scrap in the converter smelting process is high-quality scrap, and the high-quality scrap satisfies the following conditions: the thickness is more than or equal to 2cm, S is less than or equal to 0.02 percent, and P is less than or equal to 0.02 percent. By selecting high-quality scrap steel, the content of residual elements in the molten steel can be effectively controlled, and the cleanliness and the mechanical property of the wire rod for the ultrahigh-strength steel cord and the ultrahigh-strength steel cord are improved.
As a further improvement of one embodiment of the invention, in the smelting process of the converter, a recarburizing agent, ferrosilicon and manganese metal are added into a steel ladle to perform deoxidation alloying treatment on molten steel, wherein N in the recarburizing agent is less than or equal to 0.0095%. Therefore, on one hand, the oxygen content in the molten steel can be effectively reduced, the content of oxides formed in the deoxidation process is greatly reduced, and the increase of the N content in the molten steel caused in the deoxidation alloying process is controlled, so that the generation of fragile inclusions such as aluminum oxide, titanium oxide and titanium nitride is effectively avoided, and the cleanliness of the wire rod for the extra-high strength steel cord and the extra-high strength steel cord is improved; on the other hand, the aging hardening caused in the drawing process due to the addition of the carburant in the deoxidation alloying process can be controlled, and the drawing wire breakage rate is reduced.
In a further improvement of an embodiment of the present invention, in the refining step, the molten steel smelted in the converter is fed into an LF refining furnace, 8 to 12kg/t of a refining covering agent is added to the surface of the molten steel, and the refining covering agent is electrically melted, so that the type of inclusions in the molten steel is adjusted to make SiO in the inclusions in the molten steel2The content of the component is more than or equal to 40 percent, the content of the CaO component is less than or equal to 30 percent, and Al2O3The content of the components is less than or equal to 10 percent, thereby further effectively controlling the content of each component in the inclusions.
As a further improvement of one embodiment of the invention, slag is adopted in the refining process for slagging, the slag alkalinity of the slag is 2.5-3.0, and the slag is beneficial to largeThe acidic impurities generated in the smelting process of the converter are absorbed, and the SiO in the molten steel is reduced2The content of the similar inclusion reduces the violent fluctuation and uncontrollable property of the inclusion components in the molten steel and reduces the corrosion to the refractory wall of the steel ladle.
In a further improvement of an embodiment of the present invention, in the continuous casting step, the superheat degree of the tundish is controlled to be 15 to 20 ℃, and the casting pulling speed is controlled to be 0.64 to 0.66 m/min. The liquid level fluctuation of the tundish in the casting process can be reduced by adopting low superheat degree and constant drawing speed in the continuous casting process, and slag rolling is avoided, so that the macrosegregation of the continuous casting billet is reduced.
In a further improvement of an embodiment of the present invention, in the continuous casting step, the total rolling reduction is 23 to 28mm, and the rolling reduction of a single roll is not more than 5 mm. By controlling the total reduction and reasonably distributing the reduction of the single roller, the cavity negative pressure generated by solidification shrinkage of the central area of the continuous casting billet can be prevented, the molten steel with solute elements enriched in crystal is prevented from flowing to the central area, the macrosegregation is greatly reduced, cracks are prevented from being generated in the billet, and the tissue uniformity of the wire rod for the extra-high-strength steel cord is improved.
In a further improvement of an embodiment of the present invention, in the temperature-controlled cooling step, the average cooling rate before pearlite transformation is 13 to 17 ℃/s, and the average cooling rate at pearlite transformation is 5 to 10 ℃/s. By controlling the temperature and the cooling speed, the transformation from super-cooled austenite to pearlite can be promoted, the pearlite transformation time is shortened, the formation of reticular cementite, low-temperature bainite and martensite is avoided, and the structure uniformity of the wire rod for the extra-high-strength steel cord is improved.
Detailed Description
An embodiment of the invention provides a wire rod for an ultrahigh-strength steel cord and a production method of the wire rod for the ultrahigh-strength steel cord.
The invention relates to a wire rod for a prestressed steel strand, which comprises the following chemical components in percentage by mass: 0.90-0.94% of C, 0.17-0.23% of Si, 0.35-0.48% of Mn, 0.17-0.23% of Cr, less than or equal to 0.001% of Ti, less than or equal to 0.0018% of Al, less than or equal to 0.005% of Sn, less than or equal to 0.005% of As, less than or equal to 0.005% of S, less than or equal to 0.0025% of O, less than or equal to 0.0020% of N, and the balance of Fe and other inevitable impurities; wherein, the content of Mn and Si satisfies: Mn/Si is 1.8 to 2.2.
And the diameter of the wire rod for the ultrahigh-strength steel cord is 5.0-5.5 mm, and a large number of experimental researches prove that the tensile strength of the wire rod for the ultrahigh-strength steel cord is 1250-1350 MPa, the reduction of area is more than or equal to 40%, the size of maximum inclusions is less than or equal to 25 mu m, and the area ratio of sorbite to pearlite in a metallographic structure is more than or equal to 99%.
And, the wire rod for the ultra high strength steel cord can be used as a base material for producing the ultra high strength steel cord.
In another aspect, an embodiment of the present invention further provides an ultra-high strength steel cord, which is prepared from the wire rod for the ultra-high strength steel cord as a base material. For example, the wire rod for the ultrahigh-strength steel cord is further subjected to a drawing process to prepare monofilaments with the diameter of 0.30mm, the tensile strength of the monofilaments is 3750-3900 MPa, and a plurality of the monofilaments can be twisted into the ultrahigh-strength steel cord.
An embodiment of the present invention further provides a method for manufacturing the wire rod for the ultra high strength steel cord, wherein the method is obtained according to a large number of experimental studies, and each step of the method is further described below with reference to specific examples.
A production method for preparing the wire rod for the ultrahigh-strength steel cord comprises the following steps:
(1) pretreatment: desulfurizing the molten iron;
preferably, the blast furnace molten iron is adopted to carry out desulphurization in a KR desulphurization device, and the blast furnace molten iron meets the following requirements before desulphurization: the temperature is more than or equal to 1360 ℃, the C is 4.0-4.5%, the S is less than or equal to 0.04%, the Si is 0.20-0.60%, the Ti is less than or equal to 0.04%, the P is less than or equal to 0.10%, and the balance is Fe and other inevitable impurities.
Preferably, the molten iron is desulfurized until the S in the molten iron is less than or equal to 0.002 percent.
Preferably, the blast furnace slag in the ladle is removed before desulfurization, and the slag removing rate is 80-90%.
(2) Smelting in a converter: and (2) feeding the pretreated molten iron into a converter to be mixed with scrap steel to form molten steel, and carrying out desiliconization, dephosphorization, oxygen blowing and decarburization, wherein the molten iron accounts for 82-88% of the molten steel, the tapping temperature of the molten steel is more than or equal to 1640 ℃, and the C in the molten steel is more than or equal to 0.05% during tapping.
Preferably, the scrap steel adopts high-quality scrap steel, and the high-quality scrap steel meets the following requirements: the thickness is more than or equal to 2cm, S is less than or equal to 0.02 percent, and P is less than or equal to 0.02 percent.
Preferably, a recarburizer, ferrosilicon and manganese metal are added into the steel ladle to perform deoxidation alloying treatment on the molten steel, wherein N in the recarburizer is less than or equal to 0.0095%.
Specifically, when tapping is started, ferrosilicon, manganese metal and 30% of carburant are added into a ladle for deoxidation alloying, the rest of carburant is added when 85% of tapping is finished, and lime and synthetic slag are added for slagging after the tapping is finished. The carburant is added in batches, so that the boiling degree of the molten steel can be reduced, the safety is improved, the carburant is dissolved in the molten steel, the time required by deoxidation alloying is shortened, and the amount of air entering the molten steel is reduced.
(3) Refining: and (3) carrying out chemical component adjustment and temperature regulation on the molten steel smelted by the converter, regulating and controlling impurities in the molten steel by soft stirring, wherein the soft stirring time is more than or equal to 30min, and the flow of argon blown from the bottom of the steel ladle during soft stirring is 0.5-0.7L/min.t.
Preferably, an LF refining furnace is adopted for refining, 8-12 kg/t of refining covering agent is added to the surface of molten steel, electricity is conducted to melt the refining covering agent, and the type of inclusions in steel is adjusted so that SiO in the inclusions in the molten steel2The content of the component is more than or equal to 40 percent, the content of the CaO component is less than or equal to 30 percent, and Al2O3The content of the components is less than or equal to 10 percent.
Preferably, slag is adopted for slagging, and the slag alkalinity of the slag is 2.5-3.0.
(4) Continuous casting: and casting the molten steel obtained by refining into a continuous casting billet.
Preferably, the superheat degree of the tundish is controlled to be 15-20 ℃, and the casting pulling speed is 0.64-0.66 m/min.
Preferably, the total rolling reduction is controlled to be 23-28 mm, and the rolling reduction of a single roller is less than or equal to 5 mm.
(5) Cogging: the obtained continuous casting billet is heated by a heating furnace and then continuously rolled and cogging into an intermediate billet.
(6) High-speed wire rolling: rolling the obtained intermediate blank into a wire rod, wherein the wire rod comprises the following chemical components in percentage by mass: 0.90-0.94% of C, 0.17-0.23% of Si, 0.35-0.48% of Mn, 0.17-0.23% of Cr, less than or equal to 0.001% of Ti, less than or equal to 0.0018% of Al, less than or equal to 0.005% of Sn, less than or equal to 0.005% of As, less than or equal to 0.005% of S, less than or equal to 0.0025% of O, less than or equal to 0.0020% of N, and the balance of Fe and other inevitable impurities; wherein, the content of Mn and Si satisfies: Mn/Si is 1.8 to 2.2.
(7) Temperature control and cooling: the wire rod is cooled at a controlled temperature on a stelmor cooling line, the spinning temperature is 900-920 ℃, the air quantity of a No. 1-4 fan is 100%, and specifically the air quantity of the No. 1-4 fan is 19400m3And h, closing the rest fans, and controlling the average speed of the roller way to be 72-75 m/min.
Preferably, the average cooling rate before pearlite transformation is controlled to be 13-17 ℃/s, and the average cooling rate during pearlite transformation is controlled to be 5-10 ℃/s.
In order to make the objects, technical solutions and advantages of an embodiment of the present invention more clear, the embodiment will be further described with reference to examples 1 to 10 according to an embodiment of the present invention and comparative examples 1 to 6 not according to an embodiment of the present invention. It is apparent that the embodiments 1 to 10 described are some, not all, embodiments of the present invention.
Specifically, examples 1 to 10 and comparative examples 1 to 6 each provide a wire rod, each of which has chemical components in mass percentage as shown in table 1.
[ Table 1]
Figure BDA0003002222730000081
As can be seen from table 1, examples 1 to 10 all conform to the design scheme of the chemical components of the wire rod for the ultra-high strength steel cord in one embodiment of the present invention, that is, the chemical components include, by mass: 0.90-0.94% of C, 0.17-0.23% of Si, 0.35-0.48% of Mn, 0.17-0.23% of Cr, less than or equal to 0.001% of Ti, less than or equal to 0.0018% of Al, less than or equal to 0.005% of Sn, less than or equal to 0.005% of As, less than or equal to 0.005% of S, less than or equal to 0.0025% of O, less than or equal to 0.0020% of N, and the balance of Fe and other inevitable impurities; wherein, the content of Mn and Si satisfies: Mn/Si is 1.8 to 2.2. And the comparative examples 1 to 6 do not conform to the chemical composition design scheme. The production methods of the respective examples are described in detail below.
Example 1
(1) Pretreatment of
The method comprises the following steps of removing blast furnace slag in a ladle, wherein the slag removal rate is 81%, desulfurizing the blast furnace molten iron in a KR desulfurizing device until the S content in the molten iron is 0.0013%, the temperature of the blast furnace molten iron before desulfurization is 1363 ℃, and the chemical components of the blast furnace molten iron before desulfurization meet the following requirements in percentage by mass: 4.0-4.5% of C, less than or equal to 0.040% of S, 0.20-0.60% of Si, less than or equal to 0.04% of Ti, less than or equal to 0.10% of P, and the balance of Fe and other inevitable impurities.
(2) Smelting in a converter: the pretreated molten iron is fed into a converter to be mixed with high-quality scrap steel to form molten steel, wherein the molten iron accounts for 85% of the molten steel, and the high-quality scrap steel meets the following requirements: the thickness is more than or equal to 2cm, S is less than or equal to 0.02 percent, and P is less than or equal to 0.02 percent; desiliconizing, dephosphorizing, blowing oxygen for decarbonization, when tapping begins, adding ferrosilicon, manganese metal and 30% of carburant into a steel ladle for deoxidization and alloying, when the tapping reaches 85%, adding the rest carburant, and after the tapping is finished, adding lime and synthetic slag for slagging, wherein N in the carburant is less than or equal to 0.0095%; the tapping temperature of the molten steel is 1645 ℃, and the content of C in the molten steel is 0.06 percent during tapping.
(3) Refining: sending the molten steel smelted in the converter to an LF refining furnace for chemical component adjustment and temperature control, adding 9kg/t of refining covering agent to the surface of the molten steel, electrifying to melt the refining covering agent, and adjusting the type of inclusions in the steel so as to enable SiO in the inclusions in the molten steel245% of CaO component, 28% of Al2O3The content of the components is 9 percent; the slag alkalinity of slag materials adopted for slagging is 2.7; the soft stirring time is 33min, and the flow of argon blown from the bottom of the steel ladle during the soft stirring is 0.5L/min t.
(4) Continuous casting: and casting the molten steel obtained by refining into a continuous casting billet, controlling the superheat degree of a tundish to be 16 ℃, the casting drawing speed to be 0.64m/min, the total reduction to be 24mm, and the reduction of a No. 5-11 withdrawal and straightening machine to be 2mm, 4mm, 5mm, 3mm and 3mm respectively.
(5) Cogging: the obtained continuous casting billet is heated by a heating furnace and then continuously rolled and cogging into an intermediate billet.
(6) High-speed wire rolling: the resulting intermediate billet was rolled into a wire rod having a diameter of 5.0mm and the chemical composition of the wire rod is shown in table 1.
(7) Temperature control and cooling: carrying out temperature-controlled cooling on the wire rod on a stelmor cooling line, wherein the spinning temperature is 915 ℃, the average cooling speed before pearlite phase transformation is 15 ℃/s, the average cooling speed during pearlite phase transformation is 7 ℃/s, the air volume of a No. 1-4 fan is 100%, and specifically, the air volume of the No. 1-4 fan is 19400m3And h, closing the rest fans, and keeping the average speed of the roller way at 72m/min until the temperature is reduced to 630 ℃, and collecting coils to finally obtain the finished wire rod product.
Example 2
(1) Pretreatment of
The method comprises the following steps of removing blast furnace slag in a ladle, wherein the slag removal rate is 84%, desulfurizing the blast furnace molten iron in a KR desulfurizing device until the S content in the molten iron is 0.0015%, the temperature of the blast furnace molten iron before desulfurization is 1370 ℃, and the chemical components of the blast furnace molten iron before desulfurization meet the following requirements in percentage by mass: 4.0-4.5% of C, less than or equal to 0.040% of S, 0.20-0.60% of Si, less than or equal to 0.04% of Ti, less than or equal to 0.10% of P, and the balance of Fe and other inevitable impurities.
(2) Smelting in a converter: the pretreated molten iron is fed into a converter to be mixed with high-quality scrap steel to form molten steel, wherein the molten iron accounts for 86% of the molten steel, and the high-quality scrap steel meets the following requirements: the thickness is more than or equal to 2cm, S is less than or equal to 0.02 percent, and P is less than or equal to 0.02 percent; desiliconizing, dephosphorizing, blowing oxygen for decarbonization, adding ferrosilicon, manganese metal and 30% of carburant into a steel ladle for deoxidization and alloying when tapping begins, adding the rest carburant when the tapping is 85%, and adding lime and synthetic slag for slagging after the tapping is finished, wherein N in the carburant is less than or equal to 0.0095%; the tapping temperature of the molten steel is 1644 ℃, and the content of C in the molten steel is 0.05 percent during tapping.
(3) Refining: the molten steel smelted by the converter is sent to an LF refining furnace for chemical component adjustment and temperature adjustmentControlling, adding 11kg/t of refining covering agent to the surface of the molten steel, electrifying to melt the refining covering agent, and adjusting the type of inclusions in the steel so as to enable SiO in the inclusions in the molten steel245% of CaO component, 27% of Al2O3The content of the components is 8 percent; the slag alkalinity of slag materials used for slagging is 2.8; the soft stirring time is 34min, and the flow of argon blown from the bottom of the steel ladle during the soft stirring is 0.6L/min t.
(4) Continuous casting: and casting the molten steel obtained by refining into a continuous casting billet, controlling the superheat degree of a tundish to be 19 ℃, the casting drawing speed to be 0.66m/min, the total reduction to be 25mm, and the reduction of a No. 5-11 withdrawal and straightening machine to be 2mm, 4mm, 5mm, 4mm and 3mm respectively.
(5) Cogging: the obtained continuous casting billet is heated by a heating furnace and then continuously rolled and cogging into an intermediate billet.
(6) High-speed wire rolling: the resulting intermediate billet was rolled into a wire rod having a diameter of 5.0mm and the chemical composition of the wire rod is shown in table 1.
(7) Temperature control and cooling: carrying out temperature-controlled cooling on the wire rod on a stelmor cooling line, wherein the spinning temperature is 911 ℃, the average cooling speed before pearlite phase transformation is 16 ℃/s, the average cooling speed during pearlite phase transformation is 9 ℃/s, the air volume of a No. 1-4 fan is 100%, and specifically, the air volume of the No. 1-4 fan is 19400m3And h, closing the rest fans, wherein the average speed of the roller way is 73m/min until the temperature is reduced to 635 ℃, and collecting coils to finally obtain the finished wire rod product.
Example 3
(1) Pretreatment of
The method comprises the following steps of removing blast furnace slag in a ladle, wherein the slag removal rate is 89%, desulfurizing the blast furnace molten iron in a KR desulfurizing device until the S content in the molten iron is 0.002%, the temperature of the blast furnace molten iron before desulfurization is 1360 ℃, and the chemical components of the blast furnace molten iron before desulfurization meet the following requirements in percentage by mass: 4.0-4.5% of C, less than or equal to 0.040% of S, 0.20-0.60% of Si, less than or equal to 0.04% of Ti, less than or equal to 0.10% of P, and the balance of Fe and other inevitable impurities.
(2) Smelting in a converter: the pretreated molten iron is fed into a converter to be mixed with high-quality scrap steel to form molten steel, wherein the molten iron accounts for 82% of the molten steel, and the high-quality scrap steel meets the following requirements: the thickness is more than or equal to 2cm, S is less than or equal to 0.02 percent, and P is less than or equal to 0.02 percent; desiliconizing, dephosphorizing, blowing oxygen for decarbonization, when tapping begins, adding ferrosilicon, manganese metal and 30% of carburant into a steel ladle for deoxidization and alloying, when the tapping reaches 85%, adding the rest carburant, and after the tapping is finished, adding lime and synthetic slag for slagging, wherein N in the carburant is less than or equal to 0.0095%; the tapping temperature of the molten steel is 1645 ℃, and the content of C in the molten steel is 0.06 percent during tapping.
(3) Refining: sending the molten steel smelted in the converter to an LF refining furnace for chemical component adjustment and temperature control, adding 10kg/t of refining covering agent to the surface of the molten steel, electrifying to melt the refining covering agent, and adjusting the type of inclusions in the steel so as to enable SiO in the inclusions in the molten steel247% of CaO component, 23% of Al2O3The content of the components is 9 percent; the slag alkalinity of slag materials used for slagging is 2.6; the soft stirring time is 33min, and the flow of argon blown from the bottom of the steel ladle during the soft stirring is 0.7L/min t.
(4) Continuous casting: and casting the molten steel obtained by refining into a continuous casting billet, controlling the superheat degree of a tundish to be 15 ℃, the casting drawing speed to be 0.64m/min, the total reduction to be 26mm, and the reduction of a No. 5-11 withdrawal and straightening machine to be 2mm, 5mm, 4mm and 3mm respectively.
(5) Cogging: the obtained continuous casting billet is heated by a heating furnace and then continuously rolled and cogging into an intermediate billet.
(6) High-speed wire rolling: the resulting intermediate billet was rolled into a wire rod having a diameter of 5.0mm and the chemical composition of the wire rod is shown in table 1.
(7) Temperature control and cooling: carrying out temperature-controlled cooling on the wire rod on a stelmor cooling line, wherein the spinning temperature is 914 ℃, the average cooling speed before pearlite phase transformation is 17 ℃/s, the average cooling speed during pearlite phase transformation is 7 ℃/s, the air volume of a No. 1-4 fan is 100%, and specifically, the air volume of the No. 1-4 fan is 19400m3And h, closing the rest fans, and keeping the average speed of the roller way at 72m/min until the temperature is reduced to 644 ℃, and collecting coils to finally obtain the finished wire rod.
Example 4
(1) Pretreatment of
The method comprises the following steps of removing blast furnace slag in a ladle, wherein the slag removal rate is 85%, desulfurizing the blast furnace molten iron in a KR desulfurizing device until the S content in the molten iron is 0.0013%, the temperature of the blast furnace molten iron before desulfurization is 1368 ℃, and the chemical components of the blast furnace molten iron before desulfurization meet the following requirements in percentage by mass: 4.0-4.5% of C, less than or equal to 0.040% of S, 0.20-0.60% of Si, less than or equal to 0.04% of Ti, less than or equal to 0.10% of P, and the balance of Fe and other inevitable impurities.
(2) Smelting in a converter: the pretreated molten iron is fed into a converter to be mixed with high-quality scrap steel to form molten steel, wherein the molten iron accounts for 87% of the molten steel, and the high-quality scrap steel meets the following requirements: the thickness is more than or equal to 2cm, S is less than or equal to 0.02 percent, and P is less than or equal to 0.02 percent; desiliconizing, dephosphorizing, blowing oxygen for decarbonization, when tapping begins, adding ferrosilicon, manganese metal and 30% of carburant into a steel ladle for deoxidization and alloying, when the tapping reaches 85%, adding the rest carburant, and after the tapping is finished, adding lime and synthetic slag for slagging, wherein N in the carburant is less than or equal to 0.0095%; the tapping temperature of the molten steel is 1647 ℃, and the content of C in the molten steel is 0.07 percent during tapping.
(3) Refining: sending the molten steel smelted in the converter to an LF refining furnace for chemical component adjustment and temperature control, adding 11kg/t of refining covering agent to the surface of the molten steel, electrifying to melt the refining covering agent, and adjusting the type of inclusions in the steel so as to enable SiO in the inclusions in the molten steel244% of CaO component, 29% of Al2O3The content of the components is 9 percent; the slag alkalinity of slag materials used for slagging is 2.6; the soft stirring time is 34min, and the flow of argon blown from the bottom of the steel ladle during the soft stirring is 0.6L/min t.
(4) Continuous casting: and casting the molten steel obtained by refining into a continuous casting billet, controlling the superheat degree of a tundish to be 18 ℃, the casting drawing speed to be 0.65m/min, the total reduction to be 25mm, and the reduction of a No. 5-11 withdrawal and straightening machine to be 2mm, 4mm, 5mm, 4mm and 3mm respectively.
(5) Cogging: the obtained continuous casting billet is heated by a heating furnace and then continuously rolled and cogging into an intermediate billet.
(6) High-speed wire rolling: the resulting intermediate billet was rolled into a wire rod having a diameter of 5.0mm and the chemical composition of the wire rod is shown in table 1.
(7) Temperature control and cooling: controlling the wire rod on a stelmor cooling lineCarrying out warm cooling, wherein the spinning temperature is 909 ℃, the average cooling speed before pearlite transformation is 17 ℃/s, the average cooling speed during pearlite transformation is 6 ℃/s, the air volume of a No. 1-4 fan is 100%, and specifically, the air volume of the No. 1-4 fan is 19400m3And h, closing the rest fans, wherein the average speed of the roller way is 74m/min, cooling to 641 ℃, collecting coils, and finally obtaining the finished wire rod product.
Example 5
(1) Pretreatment of
The method comprises the following steps of removing blast furnace slag in a ladle, wherein the slag removal rate is 88%, desulfurizing the blast furnace molten iron in a KR desulfurizing device until the S content in the molten iron is 0.0012%, the temperature of the blast furnace molten iron before desulfurization is 1360 ℃, and the chemical components of the blast furnace molten iron before desulfurization meet the following requirements in percentage by mass: 4.0-4.5% of C, less than or equal to 0.040% of S, 0.20-0.60% of Si, less than or equal to 0.04% of Ti, less than or equal to 0.10% of P, and the balance of Fe and other inevitable impurities.
(2) Smelting in a converter: the pretreated molten iron is fed into a converter to be mixed with high-quality scrap steel to form molten steel, wherein the molten iron accounts for 84% of the molten steel, and the high-quality scrap steel meets the following requirements: the thickness is more than or equal to 2cm, S is less than or equal to 0.02 percent, and P is less than or equal to 0.02 percent; desiliconizing, dephosphorizing, blowing oxygen for decarbonization, when tapping begins, adding ferrosilicon, manganese metal and 30% of carburant into a steel ladle for deoxidization and alloying, when the tapping reaches 85%, adding the rest carburant, and after the tapping is finished, adding lime and synthetic slag for slagging, wherein N in the carburant is less than or equal to 0.0095%; the tapping temperature of the molten steel is 1645 ℃, and the content of C in the molten steel is 0.06 percent during tapping.
(3) Refining: sending the molten steel smelted in the converter to an LF refining furnace for chemical component adjustment and temperature control, adding 8kg/t of refining covering agent to the surface of the molten steel, electrifying to melt the refining covering agent, and adjusting the type of inclusions in the steel so as to enable SiO in the inclusions in the molten steel246% of CaO component, 30% of Al2O3The content of the components is 6 percent; the slag alkalinity of the adopted slag is 2.8; the soft stirring time is 34min, and the flow of argon blown from the bottom of the steel ladle during the soft stirring is 0.5L/min t.
(4) Continuous casting: and casting the molten steel obtained by refining into a continuous casting billet, controlling the superheat degree of a tundish to be 18 ℃, the casting drawing speed to be 0.65m/min, the total reduction to be 25mm, and the reduction of a No. 5-11 withdrawal and straightening machine to be 2mm, 4mm, 5mm, 4mm and 3mm respectively.
(5) Cogging: the obtained continuous casting billet is heated by a heating furnace and then continuously rolled and cogging into an intermediate billet.
(6) High-speed wire rolling: the resulting intermediate billet was rolled into a wire rod having a diameter of 5.0mm and the chemical composition of the wire rod is shown in table 1.
(7) Temperature control and cooling: carrying out temperature-controlled cooling on the wire rod on a stelmor cooling line, wherein the spinning temperature is 905 ℃, the average cooling speed before pearlite phase transformation is 16 ℃/s, the average cooling speed during pearlite phase transformation is 5 ℃/s, the air volume of a No. 1-4 fan is 100%, and specifically, the air volume of the No. 1-4 fan is 19400m3And h, closing the rest fans, and keeping the average speed of the roller way at 75m/min until the temperature is reduced to 650 ℃, collecting coils, and finally obtaining the finished wire rod.
Example 6
(1) Pretreatment of
The method comprises the following steps of removing blast furnace slag in a ladle, wherein the slag removal rate is 88%, desulfurizing the blast furnace molten iron in a KR desulfurizing device until the S content in the molten iron is 0.001%, the temperature of the blast furnace molten iron before desulfurization is 1364 ℃, and the chemical components of the blast furnace molten iron before desulfurization meet the following requirements in percentage by mass: 4.0-4.5% of C, less than or equal to 0.040% of S, 0.20-0.60% of Si, less than or equal to 0.04% of Ti, less than or equal to 0.10% of P, and the balance of Fe and other inevitable impurities.
(2) Smelting in a converter: the pretreated molten iron is fed into a converter to be mixed with high-quality scrap steel to form molten steel, wherein the molten iron accounts for 87% of the molten steel, and the high-quality scrap steel meets the following requirements: the thickness is more than or equal to 2cm, S is less than or equal to 0.02 percent, and P is less than or equal to 0.02 percent; desiliconizing, dephosphorizing, blowing oxygen for decarbonization, when tapping begins, adding ferrosilicon, manganese metal and 30% of carburant into a steel ladle for deoxidization and alloying, when the tapping reaches 85%, adding the rest carburant, and after the tapping is finished, adding lime and synthetic slag for slagging, wherein N in the carburant is less than or equal to 0.0095%; the tapping temperature of the molten steel is 1648 ℃, and the content of C in the molten steel is 0.08 percent during tapping.
(3) Refining: the molten steel smelted by the converter is sent to an LF refining furnace for chemical component adjustment and temperature adjustmentAdjusting and controlling the degree, adding 9kg/t of refining covering agent to the surface of the molten steel, electrifying to melt the refining covering agent, and adjusting the type of inclusions in the steel so as to enable SiO in the inclusions in the molten steel244% of CaO component, 27% of Al2O3The content of the components is 7 percent; the slag alkalinity of slag materials used for slagging is 3.0; the soft stirring time is 35min, and the flow of argon blown from the bottom of the steel ladle during the soft stirring is 0.6L/min t.
(4) Continuous casting: and casting the molten steel obtained by refining into a continuous casting billet, controlling the superheat degree of a tundish to be 15 ℃, the casting drawing speed to be 0.64m/min, the total reduction to be 25mm, and the reduction of a No. 5-11 withdrawal and straightening machine to be 2mm, 4mm, 5mm, 4mm and 3mm respectively.
(5) Cogging: the obtained continuous casting billet is heated by a heating furnace and then continuously rolled and cogging into an intermediate billet.
(6) High-speed wire rolling: the resulting intermediate billet was rolled into a wire rod having a diameter of 5.5mm and the chemical composition of the wire rod is shown in table 1.
(7) Temperature control and cooling: performing temperature-controlled cooling on the wire rod on a stelmor cooling line, wherein the spinning temperature is 920 ℃, the average cooling speed before pearlite phase transformation is 17 ℃/s, the average cooling speed during pearlite phase transformation is 8 ℃/s, the air volume of a No. 1-4 fan is 100%, and specifically, the air volume of the No. 1-4 fan is 19400m3And h, closing the rest fans, and keeping the average speed of the roller way at 74m/min until the temperature is reduced to 612 ℃, and collecting coils to finally obtain the finished wire rod product.
Example 7
(1) Pretreatment of
The method comprises the following steps of removing blast furnace slag in a ladle, wherein the slag removal rate is 87%, desulfurizing the blast furnace molten iron in a KR desulfurizing device until the S content in the molten iron is 0.0015%, the temperature of the blast furnace molten iron before desulfurization is 1369 ℃, and the chemical components of the blast furnace molten iron before desulfurization meet the following requirements in percentage by mass: 4.0-4.5% of C, less than or equal to 0.040% of S, 0.20-0.60% of Si, less than or equal to 0.04% of Ti, less than or equal to 0.10% of P, and the balance of Fe and other inevitable impurities.
(2) Smelting in a converter: the pretreated molten iron is fed into a converter to be mixed with high-quality scrap steel to form molten steel, wherein the molten iron accounts for 86% of the molten steel, and the high-quality scrap steel meets the following requirements: the thickness is more than or equal to 2cm, S is less than or equal to 0.02 percent, and P is less than or equal to 0.02 percent; desiliconizing, dephosphorizing, blowing oxygen for decarbonization, when tapping begins, adding ferrosilicon, manganese metal and 30% of carburant into a steel ladle for deoxidization and alloying, when the tapping reaches 85%, adding the rest carburant, and after the tapping is finished, adding lime and synthetic slag for slagging, wherein N in the carburant is less than or equal to 0.0095%; the tapping temperature of the molten steel is 1647 ℃, and the content of C in the molten steel is 0.07 percent during tapping.
(3) Refining: sending the molten steel smelted in the converter to an LF refining furnace for chemical component adjustment and temperature control, adding 10kg/t of refining covering agent to the surface of the molten steel, electrifying to melt the refining covering agent, and adjusting the type of inclusions in the steel so as to enable SiO in the inclusions in the molten steel245% of component, 30% of CaO component, Al2O3The content of the components is 10 percent; the slag alkalinity of slag materials used for slagging is 2.6; the soft stirring time is 31min, and the flow of argon blown from the bottom of the steel ladle during the soft stirring is 0.5L/min t.
(4) Continuous casting: and casting the molten steel obtained by refining into a continuous casting billet, controlling the superheat degree of a tundish to be 16 ℃, the casting drawing speed to be 0.65m/min, the total reduction to be 25mm, and the reduction of a No. 5-11 withdrawal and straightening machine to be 2mm, 4mm, 5mm, 4mm and 3mm respectively.
(5) Cogging: the obtained continuous casting billet is heated by a heating furnace and then continuously rolled and cogging into an intermediate billet.
(6) High-speed wire rolling: the resulting intermediate billet was rolled into a wire rod having a diameter of 5.5mm and the chemical composition of the wire rod is shown in table 1.
(7) Temperature control and cooling: carrying out temperature-controlled cooling on the wire rod on a stelmor cooling line, wherein the spinning temperature is 911 ℃, the average cooling speed before pearlite phase transformation is 13 ℃/s, the average cooling speed during pearlite phase transformation is 8 ℃/s, the air volume of a No. 1-4 fan is 100%, and specifically, the air volume of the No. 1-4 fan is 19400m3And h, closing the rest fans, and keeping the average speed of the roller way at 73m/min until the temperature is reduced to 608 ℃, collecting coils, and finally obtaining the finished wire rod product.
Example 8
(1) Pretreatment of
The method comprises the following steps of removing blast furnace slag in a ladle, wherein the slag removal rate is 90%, desulfurizing the blast furnace molten iron in a KR desulfurizing device until the S content in the molten iron is 0.001%, the temperature of the blast furnace molten iron before desulfurization is 1377 ℃, and the chemical components of the blast furnace molten iron before desulfurization meet the following requirements in percentage by mass: 4.0-4.5% of C, less than or equal to 0.040% of S, 0.20-0.60% of Si, less than or equal to 0.04% of Ti, less than or equal to 0.10% of P, and the balance of Fe and other inevitable impurities.
(2) Smelting in a converter: the pretreated molten iron is fed into a converter to be mixed with high-quality scrap steel to form molten steel, wherein the molten iron accounts for 88% of the molten steel, and the high-quality scrap steel meets the following requirements: the thickness is more than or equal to 2cm, S is less than or equal to 0.02 percent, and P is less than or equal to 0.02 percent; desiliconizing, dephosphorizing, blowing oxygen for decarbonizing, when tapping begins, adding ferrosilicon, manganese metal and 30% of carburant into a ladle for deoxidation alloying, when the tapping reaches 85%, adding the rest carburant, and after the tapping is finished, adding lime and synthetic slag for slagging, wherein N in the carburant is less than or equal to 0.0095%; the tapping temperature of the molten steel is 1644 ℃, and the content of C in the molten steel is 0.09 percent during tapping.
(3) Refining: sending the molten steel smelted in the converter to an LF refining furnace for chemical component adjustment and temperature control, adding 10kg/t of refining covering agent to the surface of the molten steel, electrifying to melt the refining covering agent, and adjusting the type of inclusions in the steel so as to enable SiO in the inclusions in the molten steel241 percent of component, 24 percent of CaO component and Al2O3The content of the components is 8 percent; the slag alkalinity of slag materials used for slagging is 2.8; the soft stirring time is 35min, and the flow of argon blown from the bottom of the steel ladle during the soft stirring is 0.5L/min t.
(4) Continuous casting: and casting the molten steel obtained by refining into a continuous casting billet, controlling the superheat degree of a tundish to be 18 ℃, the casting drawing speed to be 0.65m/min, the total reduction to be 25mm, and the reduction of a No. 5-11 withdrawal and straightening machine to be 2mm, 4mm, 5mm, 4mm and 3mm respectively.
(5) Cogging: the obtained continuous casting billet is heated by a heating furnace and then continuously rolled and cogging into an intermediate billet.
(6) High-speed wire rolling: the resulting intermediate billet was rolled into a wire rod having a diameter of 5.5mm and the chemical composition of the wire rod is shown in table 1.
(7) Temperature control and cooling: feeding the wire rod on a stelmor cooling lineCooling at controlled temperature, wherein the spinning temperature is 913 ℃, the average cooling speed before pearlite transformation is 17 ℃/s, the average cooling speed during pearlite transformation is 10 ℃/s, the air volume of the No. 1-4 fan is 100%, and specifically, the air volume of the No. 1-4 fan is 19400m3And h, closing the rest fans, and keeping the average speed of the roller way at 75m/min until the temperature is reduced to 600 ℃, and collecting coils to finally obtain the finished wire rod.
Example 9
(1) Pretreatment of
The method comprises the following steps of removing blast furnace slag in a ladle, wherein the slag removal rate is 90%, desulfurizing the blast furnace molten iron in a KR desulfurizing device until the S content in the molten iron is 0.001%, the temperature of the blast furnace molten iron before desulfurization is 1366 ℃, and the chemical components of the blast furnace molten iron before desulfurization meet the following requirements in percentage by mass: 4.0-4.5% of C, less than or equal to 0.040% of S, 0.20-0.60% of Si, less than or equal to 0.04% of Ti, less than or equal to 0.10% of P, and the balance of Fe and other inevitable impurities.
(2) Smelting in a converter: the pretreated molten iron is fed into a converter to be mixed with high-quality scrap steel to form molten steel, wherein the molten iron accounts for 84% of the molten steel, and the high-quality scrap steel meets the following requirements: the thickness is more than or equal to 2cm, S is less than or equal to 0.02 percent, and P is less than or equal to 0.02 percent; desiliconizing, dephosphorizing, blowing oxygen for decarbonization, when tapping begins, adding ferrosilicon, manganese metal and 30% of carburant into a steel ladle for deoxidization and alloying, when the tapping reaches 85%, adding the rest carburant, and after the tapping is finished, adding lime and synthetic slag for slagging, wherein N in the carburant is less than or equal to 0.0095%; the tapping temperature of the molten steel is 1640 ℃, and the content of C in the molten steel is 0.08% during tapping.
(3) Refining: sending the molten steel smelted in the converter to an LF refining furnace for chemical component adjustment and temperature control, adding 12kg/t of refining covering agent to the surface of the molten steel, electrifying to melt the refining covering agent, and adjusting the type of inclusions in the steel so as to enable SiO in the inclusions in the molten steel250% of CaO component, 30% of Al2O3The content of the components is 10 percent; the slag alkalinity of slag materials used for slagging is 2.5; the soft stirring time is 30min, and the flow of argon blown from the bottom of the steel ladle during the soft stirring is 0.5L/min t.
(4) Continuous casting: and casting the molten steel obtained by refining into a continuous casting billet, controlling the superheat degree of a tundish to be 17 ℃, the casting drawing speed to be 0.65m/min, the total reduction to be 25mm, and the reduction of a No. 5-11 withdrawal and straightening machine to be 2mm, 4mm, 5mm, 4mm and 3mm respectively.
(5) Cogging: the obtained continuous casting billet is heated by a heating furnace and then continuously rolled and cogging into an intermediate billet.
(6) High-speed wire rolling: the resulting intermediate billet was rolled into a wire rod having a diameter of 5.5mm and the chemical composition of the wire rod is shown in table 1.
(7) Temperature control and cooling: carrying out temperature-controlled cooling on the wire rod on a stelmor cooling line, wherein the spinning temperature is 909 ℃, the average cooling speed before pearlite phase transformation is 15 ℃/s, the average cooling speed during pearlite phase transformation is 6 ℃/s, the air volume of a No. 1-4 fan is 100%, and specifically, the air volume of the No. 1-4 fan is 19400m3And h, closing the rest fans, and keeping the average speed of the roller way at 74m/min until the temperature is reduced to 640 ℃, collecting coils, and finally obtaining the finished wire rod product.
Example 10
(1) Pretreatment of
The method comprises the following steps of removing blast furnace slag in a ladle, wherein the slag removal rate is 80%, desulfurizing the blast furnace molten iron in a KR desulfurizing device until the S content in the molten iron is 0.0015%, the temperature of the blast furnace molten iron before desulfurization is 1370 ℃, and the chemical components of the blast furnace molten iron before desulfurization meet the following requirements in percentage by mass: 4.0-4.5% of C, less than or equal to 0.040% of S, 0.20-0.60% of Si, less than or equal to 0.04% of Ti, less than or equal to 0.10% of P, and the balance of Fe and other inevitable impurities.
(2) Smelting in a converter: the pretreated molten iron is fed into a converter to be mixed with high-quality scrap steel to form molten steel, wherein the molten iron accounts for 85% of the molten steel, and the high-quality scrap steel meets the following requirements: the thickness is more than or equal to 2cm, S is less than or equal to 0.02 percent, and P is less than or equal to 0.02 percent; desiliconizing, dephosphorizing, blowing oxygen for decarbonization, when tapping begins, adding ferrosilicon, manganese metal and 30% of carburant into a steel ladle for deoxidization and alloying, when the tapping reaches 85%, adding the rest carburant, and after the tapping is finished, adding lime and synthetic slag for slagging, wherein N in the carburant is less than or equal to 0.0095%; the tapping temperature of the molten steel is 1648 ℃, and the content of C in the molten steel is 0.06 percent during tapping.
(3) Refining: sending the molten steel smelted by the converter to an LF refining furnace for chemical formationSeparately adjusting and controlling the temperature, adding 9kg/t of refining covering agent to the surface of the molten steel, electrifying to melt the refining covering agent, and adjusting the type of inclusions in the steel so as to enable SiO in the inclusions in the molten steel240% of component, 25% of CaO component, Al2O3The content of the components is 9 percent; the slag alkalinity of slag materials used for slagging is 2.5; the soft stirring time is 32min, and the flow of argon blown from the bottom of the steel ladle during the soft stirring is 0.7L/min t.
(4) Continuous casting: and casting the molten steel obtained by refining into a continuous casting billet, controlling the superheat degree of a tundish to be 20 ℃, the casting drawing speed to be 0.66m/min, the total reduction to be 27mm, and the reduction of a No. 5-11 withdrawal and straightening machine to be 2mm, 3mm, 4mm, 5mm and 3mm respectively.
(5) Cogging: the obtained continuous casting billet is heated by a heating furnace and then continuously rolled and cogging into an intermediate billet.
(6) High-speed wire rolling: the resulting intermediate billet was rolled into a wire rod having a diameter of 5.5mm and the chemical composition of the wire rod is shown in table 1.
(7) Temperature control and cooling: carrying out temperature-controlled cooling on the wire rod on a stelmor cooling line, wherein the spinning temperature is 900 ℃, the average cooling speed before pearlite phase transformation is 16 ℃/s, the average cooling speed during pearlite phase transformation is 9 ℃/s, the air volume of a No. 1-4 fan is 100%, and specifically, the air volume of the No. 1-4 fan is 19400m3And h, closing the rest fans, wherein the average speed of the roller way is 73m/min, cooling to 630 ℃, collecting coils, and finally obtaining the finished wire rod product.
Comparative example 1
(1) Pretreatment of
The method comprises the following steps of removing blast furnace slag in a ladle, wherein the slag removal rate is 75%, desulfurizing the blast furnace molten iron in a KR desulfurizing device until the S content in the molten iron is 0.002%, wherein the temperature of the blast furnace molten iron before desulfurization is 1350 ℃, and the chemical components of the blast furnace molten iron before desulfurization are calculated in percentage by mass: 4.0% of C, 0.044% of S, 0.20% of Si, 0.04% of Ti, 0.10% of P, and the balance of Fe and other inevitable impurities.
(2) Smelting in a converter: the pretreated molten iron is fed into a converter to be mixed with scrap steel to form molten steel, wherein the molten iron accounts for 80% of the molten steel, and the scrap steel meets the following requirements: the thickness is more than or equal to 1cm, S is less than or equal to 0.02 percent, and P is less than or equal to 0.02 percent; desiliconizing, dephosphorizing, blowing oxygen for decarbonization, when tapping begins, adding ferrosilicon, manganese metal and 30% of carburant into a steel ladle for deoxidization and alloying, when the tapping reaches 85%, adding the rest carburant, and after the tapping is finished, adding lime and synthetic slag for slagging, wherein N in the carburant is less than or equal to 0.0095%; the tapping temperature of the molten steel is 1634 ℃, and the content of C in the molten steel is 0.01% during tapping.
(3) Refining: sending the molten steel smelted in the converter to an LF refining furnace for chemical component adjustment and temperature control, adding 7kg/t of refining covering agent to the surface of the molten steel, electrifying to melt the refining covering agent, and adjusting the type of inclusions in the steel so as to enable SiO in the inclusions in the molten steel239% of CaO component, 30% of Al2O3The content of the components is 14 percent; the slag alkalinity of slag materials used for slagging is 2.3; the soft stirring time is 26min, and the flow of argon blown from the bottom of the steel ladle during the soft stirring is 0.4L/min t.
(4) Continuous casting: and casting the molten steel obtained by refining into a continuous casting billet, controlling the superheat degree of a tundish to be 13 ℃, the casting drawing speed to be 0.60m/min, the total reduction to be 25mm, and the reduction of 5-11 # withdrawal and straightening machines to be 2mm, 3mm, 6mm, 5mm, 4mm and 3mm respectively.
(5) Cogging: the obtained continuous casting billet is heated by a heating furnace and then continuously rolled and cogging into an intermediate billet.
(6) High-speed wire rolling: the resulting intermediate billet was rolled into a wire rod having a diameter of 5.0mm and the chemical composition of the wire rod is shown in table 1.
(7) Temperature control and cooling: carrying out temperature-controlled cooling on the wire rod on a stelmor cooling line, wherein the spinning temperature is 935 ℃, the average cooling speed before pearlite phase transformation is 18 ℃/s, the average cooling speed during pearlite phase transformation is 8 ℃/s, the air volume of a No. 1-4 fan is 100%, and specifically, the air volume of the No. 1-4 fan is 19400m3And h, closing the rest fans, and keeping the average speed of the roller way at 73m/min until the temperature is reduced to 620 ℃, and collecting coils to finally obtain the finished wire rod product.
Comparative example 2
(1) Pretreatment of
The method comprises the following steps of removing blast furnace slag in a ladle, wherein the slag removal rate is 75%, desulfurizing the blast furnace molten iron in a KR desulfurizing device until the S content in the molten iron is 0.002%, the temperature of the blast furnace molten iron before desulfurization is 1355 ℃, and the chemical components of the blast furnace molten iron before desulfurization are calculated in percentage by mass: 4.05% of C, 0.036% of S, 0.50% of Si, 0.05% of Ti, 0.07% of P, and the balance of Fe and other inevitable impurities.
(2) Smelting in a converter: the pretreated molten iron is fed into a converter to be mixed with high-quality scrap steel to form molten steel, wherein the molten iron accounts for 90% of the molten steel, and the high-quality scrap steel meets the following requirements: the thickness is more than or equal to 2cm, S is less than or equal to 0.02 percent, and P is less than or equal to 0.02 percent; desiliconizing, dephosphorizing, blowing oxygen for decarbonization, when tapping begins, adding ferrosilicon, manganese metal and 30% of carburant into a steel ladle for deoxidization and alloying, when the tapping reaches 85%, adding the rest carburant, and after the tapping is finished, adding lime and synthetic slag for slagging, wherein N in the carburant is less than or equal to 0.0095%; the tapping temperature of the molten steel is 1636 ℃, and the content of C in the molten steel is 0.01% during tapping.
(3) Refining: sending the molten steel smelted in the converter to an LF refining furnace for chemical component adjustment and temperature control, adding 12kg/t of refining covering agent to the surface of the molten steel, electrifying to melt the refining covering agent, and adjusting the type of inclusions in the steel so as to enable SiO in the inclusions in the molten steel240% of component, 30% of CaO component, Al2O3The content of the components is 15 percent; the slag alkalinity of slag materials used for slagging is 2.2; the soft stirring time is 27min, and the flow of argon blown from the bottom of the steel ladle during the soft stirring is 0.9L/min t.
(4) Continuous casting: and casting the molten steel obtained by refining into a continuous casting billet, controlling the superheat degree of a tundish to be 16 ℃, the casting drawing speed to be 0.64m/min, the total reduction to be 22mm, and the reduction of a No. 5-11 withdrawal and straightening machine to be 2mm, 3mm, 4mm and 3mm respectively.
(5) Cogging: the obtained continuous casting billet is heated by a heating furnace and then continuously rolled and cogging into an intermediate billet.
(6) High-speed wire rolling: the resulting intermediate billet was rolled into a wire rod having a diameter of 5.0mm and the chemical composition of the wire rod is shown in table 1.
(7) Temperature control and cooling: cooling the wire rod on stelmor cooling line at 928 deg.CThe average cooling rate before pearlite transformation is 15 ℃/s, the average cooling rate during pearlite transformation is 9 ℃/s, the air volume of the No. 1-4 fan is 100%, and specifically, the air volume of the No. 1-4 fan is 19400m3And h, closing the rest fans, and keeping the average speed of the roller way at 72m/min until the temperature is reduced to 610 ℃, and collecting coils to finally obtain the finished wire rod product.
Comparative example 3
(1) Pretreatment of
The method comprises the following steps of removing blast furnace slag in a ladle, wherein the slag removal rate is 84%, desulfurizing the blast furnace molten iron in a KR desulfurizing device until the S content in the molten iron is 0.001%, the temperature of the blast furnace molten iron before desulfurization is 1370 ℃, and the chemical components of the blast furnace molten iron before desulfurization are calculated in percentage by mass: 4.0% of C, 0.030% of S, 0.28% of Si, 0.03% of Ti, 0.13% of P, and the balance of Fe and other inevitable impurities.
(2) Smelting in a converter: the pretreated molten iron is fed into a converter to be mixed with scrap steel to form molten steel, wherein the molten iron accounts for 91% of the molten steel, and the scrap steel meets the following requirements: the thickness is more than or equal to 1cm, S is less than or equal to 0.02 percent, and P is less than or equal to 0.02 percent; desiliconizing, dephosphorizing, blowing oxygen for decarbonization, when tapping begins, adding ferrosilicon, manganese metal and 30% of carburant into a steel ladle for deoxidization and alloying, when the tapping reaches 85%, adding the rest carburant, and after the tapping is finished, adding lime and synthetic slag for slagging, wherein N in the carburant is less than or equal to 0.0095%; the tapping temperature of the molten steel is 1634 ℃, and the content of C in the molten steel is 0.13% during tapping.
(3) Refining: sending the molten steel smelted in the converter to an LF refining furnace for chemical component adjustment and temperature control, adding 8kg/t of refining covering agent to the surface of the molten steel, electrifying to melt the refining covering agent, and adjusting the type of inclusions in the steel so as to enable SiO in the inclusions in the molten steel234% of component, 25% of CaO component, Al2O3The content of the components is 25 percent; the slag alkalinity of slag materials used for slagging is 2.5; the soft stirring time is 27min, and the flow of argon blown from the bottom of the steel ladle during the soft stirring is 0.7L/min t.
(4) Continuous casting: and casting the molten steel obtained by refining into a continuous casting billet, controlling the superheat degree of a tundish to be 18 ℃, the casting drawing speed to be 0.65m/min, the total reduction to be 25mm, and the reduction of a No. 5-11 withdrawal and straightening machine to be 2mm, 4mm, 5mm, 4mm and 3mm respectively.
(5) Cogging: the obtained continuous casting billet is heated by a heating furnace and then continuously rolled and cogging into an intermediate billet.
(6) High-speed wire rolling: the resulting intermediate billet was rolled into a wire rod having a diameter of 5.0mm and the chemical composition of the wire rod is shown in table 1.
(7) Temperature control and cooling: carrying out temperature-controlled cooling on the wire rod on a stelmor cooling line, wherein the spinning temperature is 938 ℃, the average cooling speed before pearlite phase transformation is 8 ℃/s, the average cooling speed during pearlite phase transformation is 5 ℃/s, the air volume of a No. 1-2 fan is 100%, and specifically, the air volume of the No. 1-2 fan is 19400m3And h, closing the rest fans, wherein the average speed of the roller way is 70m/min, cooling to 680 ℃, collecting coils, and finally obtaining the finished wire rod product.
Comparative example 4
(1) Pretreatment of
The method comprises the following steps of removing blast furnace slag in a ladle, wherein the slag removal rate is 89%, desulfurizing the blast furnace molten iron in a KR desulfurizing device until the S content in the molten iron is 0.002%, the temperature of the blast furnace molten iron before desulfurization is 1356 ℃, and the chemical components of the blast furnace molten iron before desulfurization are calculated in percentage by mass: 5.0 percent of C, 0.040 percent of S, 0.47 percent of Si, 0.05 percent of Ti, 0.12 percent of P, and the balance of Fe and other inevitable impurities.
(2) Smelting in a converter: the pretreated molten iron is fed into a converter to be mixed with high-quality scrap steel to form molten steel, wherein the molten iron accounts for 92% of the molten steel, and the high-quality scrap steel meets the following requirements: the thickness is more than or equal to 2cm, S is less than or equal to 0.02 percent, and P is less than or equal to 0.02 percent; desiliconizing, dephosphorizing, blowing oxygen for decarbonization, when tapping begins, adding ferrosilicon, manganese metal and 30% of carburant into a steel ladle for deoxidization and alloying, when the tapping reaches 85%, adding the rest carburant, and after the tapping is finished, adding lime and synthetic slag for slagging, wherein N in the carburant is less than or equal to 0.0095%; the tapping temperature of the molten steel is 1635 ℃, and the content of C in the molten steel is 0.12% during tapping.
(3) Refining: sending the molten steel smelted in the converter to an LF refining furnace for chemical component adjustment and temperature control, adding 7g/t of refining covering agent to the surface of the molten steel, and electrifying to melt the refining covering agentCovering agent for adjusting the type of inclusions in steel to make SiO in the inclusions in molten steel235% of component, 33% of CaO component, Al2O3The content of the components is 18 percent; the slag alkalinity of slag materials used for slagging is 2.4; the soft stirring time is 26min, and the flow of argon blown from the bottom of the steel ladle during the soft stirring is 0.5L/min t.
(4) Continuous casting: and casting the molten steel obtained by refining into a continuous casting billet, controlling the superheat degree of a tundish to be 19 ℃, the casting drawing speed to be 0.64m/min, the total reduction to be 25mm, and the reduction of a No. 5-11 withdrawal and straightening machine to be 2mm, 4mm, 5mm, 4mm and 3mm respectively.
(5) Cogging: the obtained continuous casting billet is heated by a heating furnace and then continuously rolled and cogging into an intermediate billet.
(6) High-speed wire rolling: the resulting intermediate billet was rolled into a wire rod having a diameter of 5.5mm and the chemical composition of the wire rod is shown in table 1.
(7) Temperature control and cooling: carrying out temperature-controlled cooling on the wire rod on a stelmor cooling line, wherein the spinning temperature is 929 ℃, the average cooling speed before pearlite phase transformation is 12 ℃/s, the average cooling speed during pearlite phase transformation is 7 ℃/s, the air volume of a No. 1-3 fan is 100%, and specifically, the air volume of the No. 1-3 fan is 19400m3And h, closing the rest fans, and keeping the average speed of the roller way at 72m/min until the temperature is reduced to 620 ℃, and collecting coils to finally obtain the finished wire rod product.
Comparative example 5
(1) Pretreatment of
The method comprises the following steps of removing blast furnace slag in a ladle, wherein the slag removal rate is 87%, desulfurizing the blast furnace molten iron in a KR desulfurizing device until the S content in the molten iron is 0.001%, the temperature of the blast furnace molten iron before desulfurization is 1367 ℃, and the chemical components of the blast furnace molten iron before desulfurization are calculated in percentage by mass: 4.5% of C, 0.033% of S, 0.26% of Si, 0.034% of Ti, 0.10% of P, and the balance of Fe and other inevitable impurities.
(2) Smelting in a converter: the pretreated molten iron is fed into a converter to be mixed with high-quality scrap steel to form molten steel, wherein the molten iron accounts for 91% of the molten steel, and the high-quality scrap steel meets the following requirements: the thickness is more than or equal to 2cm, S is less than or equal to 0.02 percent, and P is less than or equal to 0.02 percent; desiliconizing, dephosphorizing, blowing oxygen for decarbonization, when tapping begins, adding ferrosilicon, manganese metal and 30% of carburant into a steel ladle for deoxidization and alloying, when the tapping reaches 85%, adding the rest carburant, and after the tapping is finished, adding lime and synthetic slag for slagging, wherein N in the carburant is less than or equal to 0.0095%; the tapping temperature of the molten steel is 1629 ℃, and the content of C in the molten steel is 0.12 percent during tapping.
(3) Refining: sending the molten steel smelted by the converter to an LF refining furnace for chemical component adjustment and temperature control, adding 13kg/t of refining covering agent to the surface of the molten steel, electrifying to melt the refining covering agent, and adjusting the type of inclusions in the steel so as to enable SiO in the inclusions in the molten steel245% of component, 35% of CaO component, Al2O3The content of the components is 8 percent; the slag alkalinity of slag materials used for slagging is 2.9; the soft stirring time is 27min, and the flow of argon blown from the bottom of the steel ladle during the soft stirring is 0.7L/min t.
(4) Continuous casting: and casting the molten steel obtained by refining into a continuous casting billet, controlling the superheat degree of a tundish to be 17 ℃, the casting drawing speed to be 0.65m/min, the total reduction to be 25mm, and the reduction of a No. 5-11 withdrawal and straightening machine to be 2mm, 4mm, 5mm, 4mm and 3mm respectively.
(5) Cogging: the obtained continuous casting billet is heated by a heating furnace and then continuously rolled and cogging into an intermediate billet.
(6) High-speed wire rolling: the resulting intermediate billet was rolled into a wire rod having a diameter of 5.5mm and the chemical composition of the wire rod is shown in table 1.
(7) Temperature control and cooling: carrying out temperature-controlled cooling on the wire rod on a stelmor cooling line, wherein the spinning temperature is 934 ℃, the average cooling speed before pearlite phase transformation is 20 ℃/s, the average cooling speed during pearlite phase transformation is 15 ℃/s, the air volume of a No. 1-5 fan is 100%, and specifically, the air volume of the No. 1-5 fan is 19400m3And h, closing the rest fans, wherein the average speed of the roller way is 75m/min, cooling to 510 ℃, collecting coils, and finally obtaining the finished wire rod.
Comparative example 6
(1) Pretreatment of
The method comprises the following steps of removing blast furnace slag in a ladle, wherein the slag removal rate is 80%, desulfurizing the blast furnace molten iron in a KR desulfurizing device until the S content in the molten iron is 0.003%, the temperature of the blast furnace molten iron before desulfurization is 1357 ℃, and the chemical components of the blast furnace molten iron before desulfurization are calculated in percentage by mass: 3.5 percent of C, 0.05 percent of S, 0.66 percent of Si, 0.05 percent of Ti, 0.15 percent of P, and the balance of Fe and other inevitable impurities.
(2) Smelting in a converter: the pretreated molten iron is fed into a converter to be mixed with high-quality scrap steel to form molten steel, wherein the molten iron accounts for 91% of the molten steel, and the high-quality scrap steel meets the following requirements: the thickness is more than or equal to 2cm, S is less than or equal to 0.02 percent, and P is less than or equal to 0.02 percent; desiliconizing, dephosphorizing, blowing oxygen for decarbonization, when tapping begins, adding ferrosilicon, manganese metal and 30% of carburant into a steel ladle for deoxidization and alloying, when the tapping reaches 85%, adding the rest carburant, and after the tapping is finished, adding lime and synthetic slag for slagging, wherein N in the carburant is less than or equal to 0.0095%; the tapping temperature of the molten steel is 1633 ℃, and the content of C in the molten steel is 0.13% during tapping.
(3) Refining: sending the molten steel smelted in the converter to an LF refining furnace for chemical component adjustment and temperature control, adding 8kg/t of refining covering agent to the surface of the molten steel, electrifying to melt the refining covering agent, and adjusting the type of inclusions in the steel so as to enable SiO in the inclusions in the molten steel242% of component, 26% of CaO component, Al2O3The content of the components is 11%; the slag alkalinity of slag materials used for slagging is 2.4; the soft stirring time is 28min, and the flow of argon blown from the bottom of the steel ladle during the soft stirring is 0.5L/min t.
(4) Continuous casting: and casting the molten steel obtained by refining into a continuous casting billet, controlling the superheat degree of a tundish to be 17 ℃, the casting drawing speed to be 0.65m/min, the total reduction to be 25mm, and the reduction of a No. 5-11 withdrawal and straightening machine to be 2mm, 4mm, 5mm, 4mm and 3mm respectively.
(5) Cogging: the obtained continuous casting billet is heated by a heating furnace and then continuously rolled and cogging into an intermediate billet.
(6) High-speed wire rolling: the resulting intermediate billet was rolled into a wire rod having a diameter of 5.5mm and the chemical composition of the wire rod is shown in table 1.
(7) Temperature control and cooling: the wire rod is cooled at a controlled temperature on a stelmor cooling line, the spinning temperature is 940 ℃, the average cooling speed before pearlite phase transformation is 25 ℃/s, and the average cooling speed during pearlite phase transformation is 18 ℃/s, the air volume of the No. 1-6 fan is 100%, specifically, the air volume of the No. 1-6 fan is 19400m3And h, closing the rest fans, wherein the average speed of the roller way is 75m/min until the temperature is reduced to 480 ℃, collecting coils, and finally obtaining the finished wire rod product.
The inclusions, the structures and the mechanical properties of the finished wire rods of examples 1 to 10 and comparative examples 1 to 6 were respectively detected, and the results are shown in table 2, specifically including the size of the largest inclusion of the wire rod, the mesh cementite (i.e., the mesh carbon in table 2) grade, the martensite grade and the tensile strength; in addition, the area ratio of sorbite and pearlite in the metallographic structure of the wire rod finished products of examples 1 to 10 was not less than 99%, and the area ratio of sorbite and pearlite in the metallographic structure of the wire rod finished products of comparative examples 1 to 6 was less than 97%. The finished wire rod is drawn into a monofilament with a diameter of 0.3mm, the tensile strength and the breakage rate of the monofilament are detected, and the measured results are shown in table 2.
[ Table 2]
Figure BDA0003002222730000251

Claims (14)

1. A production method of a wire rod for an ultra-high strength steel cord is characterized by comprising the following steps in sequence:
pretreatment: desulfurizing the molten iron;
smelting in a converter: feeding the pretreated molten iron into a converter to be mixed with scrap steel to form molten steel, and carrying out desiliconization, dephosphorization and oxygen blowing decarburization, wherein the molten iron accounts for 82-88% of the molten steel, the tapping temperature of the molten steel is more than or equal to 1640 ℃, and the C in the molten steel is more than or equal to 0.05% during tapping;
refining: adjusting chemical components and temperature of molten steel smelted by the converter, and adjusting and controlling impurities in the molten steel by soft stirring, wherein the soft stirring time is more than or equal to 30min, and the flow of argon blown from the bottom of a steel ladle during soft stirring is 0.5-0.7L/min.t;
continuous casting: casting the molten steel obtained by refining into a continuous casting billet;
cogging: heating the obtained continuous casting billet by a heating furnace, and then continuously rolling and cogging the continuous casting billet into an intermediate billet;
high-speed wire rolling: rolling the obtained intermediate blank into a wire rod, wherein the wire rod comprises the following chemical components in percentage by mass: 0.90-0.94% of C, 0.17-0.23% of Si, 0.35-0.48% of Mn, 0.17-0.23% of Cr, less than or equal to 0.001% of Ti, less than or equal to 0.0018% of Al, less than or equal to 0.005% of Sn, less than or equal to 0.005% of As, less than or equal to 0.005% of S, less than or equal to 0.0025% of O, less than or equal to 0.0020% of N, and the balance of Fe and other inevitable impurities; wherein, the content of Mn and Si satisfies: Mn/Si is 1.8-2.2;
temperature control and cooling: and (3) carrying out temperature-controlled cooling on the wire rod on a stelmor cooling line, wherein the spinning temperature is 900-920 ℃, the air quantity of a No. 1-4 fan is 100%, the rest fans are closed, the average speed of a roller way is 72-75 m/min, the average cooling speed before pearlite phase transformation is 13-17 ℃/s, and the average cooling speed during pearlite phase transformation is 5-10 ℃/s.
2. The method for producing a wire rod for an extra-high strength steel cord according to claim 1, wherein in the pretreatment step, the blast furnace molten iron is used for desulfurization in a KR desulfurization apparatus, and the blast furnace molten iron satisfies, before desulfurization: the temperature is more than or equal to 1360 ℃, the C is 4.0-4.5%, the S is less than or equal to 0.04%, the Si is 0.20-0.60%, the Ti is less than or equal to 0.04%, the P is less than or equal to 0.10%, and the balance is Fe and other inevitable impurities.
3. The method of manufacturing a wire rod for an extra high strength steel cord according to claim 1, wherein in the pretreatment step, molten iron is desulfurized until S in the molten iron becomes 0.002% or less.
4. The method for producing a wire rod for an extra-high strength steel cord according to claim 1, wherein the scrap in the converter smelting process is high-quality scrap, and the high-quality scrap satisfies: the thickness is more than or equal to 2cm, S is less than or equal to 0.02 percent, and P is less than or equal to 0.02 percent.
5. The method for producing the wire rod for the extra-high strength steel cord according to claim 1, wherein in the converter smelting process, the molten steel is deoxidized and alloyed by adding a carburant, ferrosilicon and manganese metal into the steel ladle, wherein N in the carburant is not more than 0.0095%.
6. The method for producing a wire rod for an ultra high strength steel cord as claimed in claim 1, wherein in the refining step, the molten steel smelted in the converter is fed into an LF refining furnace, 8 to 12kg/t of a refining covering agent is added to the surface of the molten steel and the refining covering agent is electrically melted, and the type of inclusions in the steel is adjusted so that SiO in the inclusions in the molten steel2The content of the component is more than or equal to 40 percent, the content of the CaO component is less than or equal to 30 percent, and Al2O3The content of the components is less than or equal to 10 percent.
7. The method for producing a wire rod for an extra-high strength steel cord according to claim 1, wherein slag is used for slagging in the refining step, and the slag basicity of the slag is 2.5 to 3.0.
8. The method for producing a wire rod for an extra-high strength steel cord according to claim 1, wherein in the continuous casting process, the degree of superheat of the tundish is controlled to be 15 to 20 ℃, and the casting pulling rate is controlled to be 0.64 to 0.66 m/min.
9. The method for producing a wire rod for an extra-high strength steel cord according to claim 1, wherein in the continuous casting step, the total rolling reduction is 23 to 28mm, and the rolling reduction of a single roll is not more than 5 mm.
10. A wire rod for an extra-high strength steel cord, characterized by being produced by the method for producing the wire rod for an extra-high strength steel cord according to any one of claims 1 to 9, wherein the wire rod for an extra-high strength steel cord comprises the following chemical components in percentage by mass: 0.90-0.94% of C, 0.17-0.23% of Si, 0.35-0.48% of Mn, 0.17-0.23% of Cr, less than or equal to 0.001% of Ti, less than or equal to 0.0018% of Al, less than or equal to 0.005% of Sn, less than or equal to 0.005% of As, less than or equal to 0.005% of S, less than or equal to 0.0025% of O, less than or equal to 0.0020% of N, and the balance of Fe and other inevitable impurities; wherein, the content of Mn and Si satisfies: Mn/Si is 1.8 to 2.2.
11. The wire rod for an extra-high strength steel cord according to claim 10, wherein the diameter thereof is 5.0 to 5.5mm, the tensile strength thereof is 1250 to 1350MPa, and the reduction of area thereof is not less than 40%.
12. The wire rod for an ultra high strength steel cord according to claim 10, wherein the size of the largest inclusions is not more than 25 μm, and the area ratio of sorbite and pearlite in a metallographic structure is not less than 99%.
13. An extra high strength steel cord prepared from the wire rod for an extra high strength steel cord according to any one of claims 10 to 12 as a base material.
14. The ultrahigh strength steel cord of claim 13 wherein said ultrahigh strength steel cord is twisted from a monofilament having a diameter of 0.30mm, said monofilament is drawn from said ultrahigh strength steel cord using a wire rod as a base material, and said monofilament has a tensile strength of 3750 to 3900 MPa.
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