CN115141979B - High-cleanliness boron-containing high-hardenability hot-rolled I-shaped steel and preparation method thereof - Google Patents

High-cleanliness boron-containing high-hardenability hot-rolled I-shaped steel and preparation method thereof Download PDF

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CN115141979B
CN115141979B CN202210890402.8A CN202210890402A CN115141979B CN 115141979 B CN115141979 B CN 115141979B CN 202210890402 A CN202210890402 A CN 202210890402A CN 115141979 B CN115141979 B CN 115141979B
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steel
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CN115141979A (en
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刘林刚
陈伟
彭毅
张恒超
邹应春
李艳萍
邓家木
文玉兵
王文锋
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Wugang Group Kunming Iron and 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
    • B21B1/46—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 metal immediately subsequent to continuous casting
    • B21B1/463—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 metal immediately subsequent to continuous casting in a continuous process, i.e. the cast not being cut before rolling
    • 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
    • C21C7/0056—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
    • 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
    • C21C7/0645—Agents used for 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
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/076—Use of slags or fluxes as treating agents
    • 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
    • C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment 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
    • C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
    • 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
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • 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
    • C21D2211/005—Ferrite
    • 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 high-cleanliness boron-containing high-hardenability hot-rolled I-shaped steel and a preparation method thereof, wherein the gas content of the I-shaped steel is less than or equal to 0.0015wt%, N is less than or equal to 0.0030wt%, the waist thickness is less than 16mm, the yield strength ReL is greater than or equal to 245MPa, the tensile strength Rm is 380-500 MPa, the elongation A after fracture is greater than or equal to 29%, the longitudinal impact power Akv at 20 ℃ is greater than or equal to 40J, the microstructure consists of ferrite and pearlite which are greater than 80%, the grain size is greater than or equal to 8.5 grade, and nonmetallic inclusions are less than or equal to 1.5 grade. The preparation method is characterized in that multiple processes such as KR molten iron pretreatment, converter smelting, steel tapping slag washing, deoxidation alloying process, LF furnace refining, continuous casting, steel rolling heating system, billet rolling and the like are integrated and innovated, and the produced high-cleanliness boron-containing high-hardenability hot-rolled I-shaped steel is high in steel cleanliness, low in nitrogen content, appropriate in strength, excellent in ductility and toughness, good in impact toughness and high in hardenability, and remarkably improves cold-hot processing service performance of the steel.

Description

High-cleanliness boron-containing high-hardenability hot-rolled I-shaped steel and preparation method thereof
Technical Field
The invention belongs to the technical field of steel smelting, and particularly relates to high-cleanliness boron-containing high-hardenability hot-rolled I-shaped steel and a preparation method thereof.
Background
The I-shaped steel is I-shaped section steel, the inner surfaces of an upper flange and a lower flange are inclined, so that the flanges are thin at the outer part and thick at the inner part, the section of the I-shaped steel is good in direct pressure and resistant to pulling, and the I-shaped steel is widely applied to various fields of national economic construction, such as buildings, bridges, power stations, oil drilling platforms, vehicles, roads, subways, steel structure plants, large warehouse stores and the like. In the construction process of middle and old railways, the geological appearance of the passed road section is complex, and more mountains need to be penetrated particularly, wherein in some requirements and special tunnel construction processes, secondary processing needs to be carried out on the used I-steel to meet the use requirements, a small amount of boron element is added into the needed I-steel, the needed hardenability and mechanical property of the steel are ensured, and meanwhile, the hot and cold processing properties of the steel are better. Because boron resources are abundant and the price is relatively cheap, the problem of high strength required by some steel products is solved by adding boron into the steel, the problem of high cost is solved, and the technical problem of the defects of boron-containing steel products is solved.
At present, the patent research reports of boron-containing steel in China have been reported, for example, chinese patent application, a high-formability boron-containing steel (CN 202010226801.5) with tensile strength more than or equal to 320MPa, and discloses a high-formability boron-containing steel with tensile strength more than or equal to 320MPa, which comprises the following components in percentage by weight: 0.03 to 0.07 percent of C, 0.01 to 0.3 percent of Si, 0.4 to 0.9 percent of Mn, less than or equal to 0.020 percent of P, less than or equal to 0.010 percent of S, less than or equal to 0.006 percent of N, B:0.0005 to 0.003%, ti:0.03 to 0.08 percent; the preparation method comprises the following steps: continuously casting the smelted mixture into a blank; heating in sections; rough rolling; fine rolling; laminar cooling; coiling, wherein the yield strength is 250-350MPa, the tensile strength is 320-460MPa, the elongation is more than or equal to 32%, and the defect rate of the product is controlled below 0.5%. The application mainly aims at solving the problem of product defect rate, but the defect rate is still high.
As another example, the chinese patent application, a low-cost boron-containing steel and a method for manufacturing the same (CN 201110417373.5) discloses a low-cost boron-containing steel, the steel comprises the following chemical components by weight percent: c: 0.05-0.08%, si: 0.10-0.25%, mn:1.60% -1.80%, als:0.03% -0.045%, ti:0.030% -0.045%, B: 0.003-0.009%, P is less than or equal to 0.025%, S is less than or equal to 0.015%, O is less than or equal to 0.0015%, N is less than or equal to 0.0025%, and the balance is Fe and inevitable impurities. The boron-containing steel with strength grades of 460MPa, 500MPa and 550MPa is obtained by changing the adding amount of boron and adjusting the heating, hot rolling and cooling temperatures without adding elements such as V, mo, cr, ni and Cu. The application is primarily directed to solving the cost problem.
Further, as the chinese patent application, a high-strength boron-containing steel and a method for preparing the same (CN 201910651261.2) discloses a high-strength boron-containing steel, the steel comprises the following chemical components by weight percent: c: 0.15-0.25%, si is less than or equal to 0.2%, mn is less than or equal to 1.5%, cu:0.10% -0.18%, B: 0.001-0.004%, cr: 0.05-0.15%, mo:0.5% -0.8%, W:0.2% -0.4%, V: 0.05-0.1%, ni:0.05 to 0.1 percent of the total weight of the alloy, less than or equal to 0.02 percent of P, less than or equal to 0.01 percent of S, and the balance of Fe and inevitable impurities. The application is directed to solving the problem of mismatch in automotive panel strength to the Qu Jiang ratio.
As another example of the chinese patent application, a high-strength anti-seismic i-beam for tunnel support and a preparation method thereof (CN 201910651261.2) disclose a high-strength anti-seismic i-beam for tunnel support, the steel comprising the following chemical components in percentage by weight: c:0.05 to 0.12wt%, si:0.15 to 0.30wt%, mn:0.50 to 1.00wt%, ti:0.020 to 0.040wt%, V:0.030 to 0.045wt%, B:0.0010 to 0.0025 weight percent, less than or equal to 0.015 weight percent of S, less than or equal to 0.015 weight percent of P, and the balance of Fe and inevitable impurities; the yield strength is ReL: 470-520 MPa, tensile strength Rm of 580-680 MPa, yield ratio of more than or equal to 1.20, elongation after fracture: a: not less than 25.0%, and the 0-degree Charpy absorption energy AkV is: 100 to 135J; the invention mainly solves the problems of high strength, shock resistance and welding performance of the I-shaped steel, and has the defects of high production cost and no specific requirement on molten steel cleanliness because a large amount of V and Ti are added.
In summary, boron-containing steel in the prior art is produced mainly through molten iron pretreatment → converter smelting → continuous casting pouring → rolling process route, and the obtained boron-containing steel meets the use requirements under different working conditions (applications) or solves some product defect problems of B-containing steel production, but the product and the production process thereof have the following problems: has no clear requirement on the cleanliness of products, particularly has low control requirement on harmful elements such as S, P, O, N in steel, and has higher cost because trace elements are added in part of production.
The invention aims to provide high-cleanliness boron-containing high-hardenability hot-rolled I-shaped steel.
Disclosure of Invention
The first purpose of the invention is to provide high-cleanliness boron-containing high-hardenability hot-rolled I-shaped steel, and the second purpose of the invention is to provide a preparation method of the high-cleanliness boron-containing high-hardenability hot-rolled I-shaped steel.
The first purpose of the invention is realized by that the high-cleanliness boron-containing high-hardenability hot-rolled I-shaped steel has the following chemical components in percentage by weight: 0.11 to 0.18 weight percent of C, 0.10 to 0.35 weight percent of Si, 0.35 to 0.60 weight percent of Mn, 0.0018 to 0.0050 weight percent of B, less than or equal to 0.010 weight percent of S, less than or equal to 0.010 weight percent of P, less than or equal to 0.0015 weight percent of O, less than or equal to 0.0030 weight percent of N, and the balance of Fe and inevitable impurities; the gas content of the I-shaped steel is less than or equal to 0.0015wt%, the gas content of N is less than or equal to 0.0030wt%, the thickness of a waist part is less than 16mm, the yield strength ReL is more than or equal to 245MPa, the tensile strength Rm is 380-500 MPa, the elongation after fracture A is more than or equal to 29%, the longitudinal impact energy Akv at 20 ℃ is more than or equal to 40J, the microstructure consists of ferrite and pearlite more than 80%, the grain size is more than or equal to 8.5 grade, and nonmetallic inclusions are less than or equal to 1.5 grade.
The invention provides a preparation method of high-cleanliness boron-containing high-hardenability hot-rolled I-shaped steel, which is characterized in that a special slag washing desulfurizer (Al with mass percentage composition) is added in the converter tapping process through multi-process integrated innovation of KR molten iron pretreatment, converter smelting, tapping slag washing, deoxidation alloying process, LF furnace refining, continuous casting, steel rolling heating system, billet rolling and the like 2 O 3 18~20%、SiO 2 4~5%, caO 44-48%, mgO 3~6%, al 8-10%, TFe 1~3% and the balance of other inevitable impurities), so that the desulfurization and the adsorption of inclusions deoxidized by molten steel are facilitated, and the cleanliness of the molten steel is ensured; the molten steel is processed in a converter, an LF and the likeCheng Chuiya, and meanwhile, the whole process of the continuous casting process is protected for pouring, the content of N in molten steel is controlled to be lower (less than 30 ppm), the addition of trace B is facilitated, the hardenability of free B is fully exerted, and the reasonable matching of the required hardenability and the mechanical property is achieved; the molten steel is treated by a process of manufacturing white slag through LF refining, so that the inclusion in the steel is obviously reduced, the P is less than or equal to 0.010wt%, the S is less than or equal to 0.010wt%, and the oxygen content is less than or equal to 0.0015wt%, which is beneficial to improving the plastic toughness of steel; a steel billet is sent to steel rolling through heating, the heating time of the steel billet in a heating furnace is obviously reduced, the suitable initial rolling temperature and the suitable final rolling temperature are controlled at the same time, the refinement of ferrite grains is promoted, the I-shaped steel is cooled on a cooling bed at a slow cooling speed to complete phase change, a fine grain ferrite + pearlite microstructure is obtained, the 20 ℃ longitudinal impact energy of the obtained I-shaped steel is more than 40J, the toughness of the I-shaped steel is good, and the use performance of the I-shaped steel in a complex environment is greatly improved.
The high-cleanliness boron-containing high-hardenability hot-rolled I-shaped steel produced by the method has the advantages of high steel cleanliness, low nitrogen content, proper strength, excellent plastic toughness, good impact toughness and high hardenability, and the cold-hot processing service performance of the steel is obviously improved.
Detailed Description
The present invention is further illustrated by the following examples, which are not intended to be limiting in any way, and any variations or modifications which are based on the teachings of the present invention are intended to fall within the scope of the present invention.
The invention relates to high-cleanliness boron-containing high-hardenability hot-rolled I-shaped steel which comprises the following chemical components in percentage by weight: 0.11 to 0.18 weight percent of C, 0.10 to 0.35 weight percent of Si, 0.35 to 0.60 weight percent of Mn, 0.0018 to 0.0050 weight percent of B, less than or equal to 0.010 weight percent of S, less than or equal to 0.010 weight percent of P, less than or equal to 0.0015 weight percent of O, less than or equal to 0.0030 weight percent of N, and the balance of Fe and inevitable impurities; the gas content of the I-shaped steel is less than or equal to 0.0015wt%, the gas content of N is less than or equal to 0.0030wt%, the thickness of a waist part is less than 16mm, the yield strength ReL is more than or equal to 245MPa, the tensile strength Rm is 380-500 MPa, the elongation after fracture A is more than or equal to 29%, the longitudinal impact energy Akv at 20 ℃ is more than or equal to 40J, the microstructure consists of more than 80% of ferrite and pearlite, the grain size is more than or equal to 8.5 grade, and the non-metallic inclusion is less than or equal to 1.5 grade, which is specifically shown in Table 1.
TABLE 1A high-cleanliness boron-containing high-hardenability hot-rolled I-steel with mechanical properties and metallographic structure
Figure DEST_PATH_IMAGE001
The preparation method of the high-cleanliness boron-containing high-hardenability hot-rolled I-shaped steel is realized according to the following steps:
A. desulfurizing by a molten iron KR method: conveying the molten iron to a desulfurization station for slag operation before molten iron skimming, and carrying out desulfurization operation on the molten iron to a desulfurization position after slag skimming, wherein CaO + CaF is used 2 As a desulfurizing agent, the desulfurizing agent is 6 to 15kg/t according to the S content and the temperature of molten iron Iron Adding the mixture, wherein the immersion depth of a stirrer is 1100-1500 mm, the starting rotating speed is 25-35r/min, starting the stirrer, the normal rotating speed is 90-120r/min, the stirring time is controlled to be 8-15min, and after stirring, removing the desulphurization slag to obtain pretreated molten iron;
B. smelting in a molten steel converter: adding the pretreated molten iron, high-quality steel scrap and low-phosphorus sulfur pig iron into a converter for top-bottom composite blowing, wherein the blowing is respectively carried out according to the proportion of 20.0-30.0 kg/t Steel 、15.0～20.0kg/t Steel Adding conventional lime and light-burned dolomite for slagging, controlling the end point carbon content to be 0.05-0.08wt%, and the tapping temperature to be 1615-1650 ℃; 2-3 kg/t of steel ladle before tapping Steel The slag washing desulfurizer is added for slag washing desulfurization, and the slag washing desulfurizer consists of the following components in percentage by mass: al (aluminum) 2 O 3 18~20%、SiO 2 4~5%, caO 44-48%, mgO 3~6%, al 8-10%, TFe 1~3%, and the balance of other unavoidable impurities; the whole bottom argon blowing process is adopted in the tapping process, and the flow rate of argon is controlled to be 25-30NL/min;
C. and (3) deoxidation alloying: tapping molten steel, and when the amount of the molten steel in a ladle is more than 1/4, carrying out the following deoxidation alloying sequence: low-silicon deoxidizer → silicon calcium barium → ferrosilicon → silicon manganese → ferro-aluminium, the following substances are added into the ladle in sequence: according to the ratio of 1.4-1.6 kg/t Steel Adding the following low-silicon deoxidizer in mass ratio: caC 2 62wt%, si 5wt%, C6 wt%, P0.080 wt%, S0.150 wt%, and the balance Fe and inevitable impurities; according to the ratio of 2.0-2.5 kg/t Steel Adding the following silicon, calcium and barium in mass ratio: 48 to 52 weight percent of Si, 8 to 10 weight percent of Ca, 12 to 14 weight percent of Ba, less than or equal to 3 weight percent of Al, and the balance of Fe and inevitable impurities; according to the ratio of 0.5-1.0 kg/t Steel Adding the following ferrosilicon in percentage by mass: 72 to 75 weight percent of Si, and the balance of Fe and inevitable impurities; according to the ratio of 5.2-5.8 kg/t Steel Adding the following silicon and manganese in mass ratio: 16-18 wt% of Si, 65-68 wt% of Mn, and the balance of Fe and inevitable impurities; according to the ratio of 0.3-1.0 kg/t Steel Adding the following aluminum iron in mass ratio: al 50wt%, the balance Fe and inevitable impurities; finishing the alloy when the molten steel amount in the steel ladle reaches 3/4; the whole bottom argon blowing process is adopted in the tapping process, and the flow rate of argon is controlled to be 25-30NL/min; after tapping, hoisting the molten steel to an LF furnace for refining;
D. refining in a molten steel LF furnace: hoisting the molten steel to a refining station of an LF furnace, connecting an argon pipe, blowing argon to make the liquid level of the molten steel in a creeping state, electrifying for slagging for 5-8 minutes, determining oxygen in the molten steel, measuring the temperature to obtain a steel sample, adding alloy and aluminum iron according to the analysis result of the steel sample to adjust the components of the molten steel, controlling the oxygen activity of the molten steel to be 15-25 ppm, and then controlling the oxygen activity of the molten steel to be 0.25-0.32 kg/t Steel Adding the following ferroboron in mass ratio: b22 wt%, the balance being Fe and inevitable impurities; soft argon blowing is carried out for 3 minutes, then the molten steel is heated to 1610 to 1630 ℃, and then calcium silicate wire feeding treatment is carried out, wherein the calcium silicate wire with the following mass ratio is fed: ca 25.6 wt%, si 52.8wt%, and the balance Fe and inevitable impurities; the wire feeding amount is 120-150 m/furnace, the wire feeding speed is 3.5m/s, then soft argon blowing is carried out, the argon blowing time is more than or equal to 10min, and alloy, deoxidizing agent or recarburizing agent is strictly forbidden to be added into the steel ladle after the argon blowing is finished; then adding molten steel covering agent, the adding amount is controlled to be 0.6-0.8 kg/t Steel And then, hoisting the molten steel to a continuous casting machine for casting.
E. Casting molten steel: at the temperature of 1535-1555 ℃ of the tundish, the pulling speed is 1.30-1.50 m/min, and the flow of cooling water of the crystallizer is 170-180 m 3 H, performing secondary cooling by adopting gas mist cooling with the compressed air pressure of 0.30MPa, and casting the molten steel into a billet with the thickness of 230mm multiplied by 230mm by using an R12m5 machine 5-flow bloom continuous casting machine under the condition that the secondary cooling specific water amount is 0.38L/kg;
F. heating a steel billet: feeding the steel billet into a stepping heating furnace with the furnace temperature of the soaking section of 1230-1300 ℃ through a hot roller way, heating for 45-50 min, and feeding the steel billet into a BD cogging mill for rolling;
G. rolling a steel billet: rolling the billet for 5 times in a reciprocating way under the rolling conditions that the initial rolling temperature is 1120-1170 ℃ and the speed is 3m/s, then sending the billet into a universal rolling mill for 10 times of continuous rolling at the speed of 5m/s, and controlling the final rolling temperature to be 950-1000 ℃ to obtain I-shaped steel; and (3) feeding the rolled steel to a long ruler on a cooling bed for natural cooling, further feeding the cooled I-steel to a straightening machine for straightening, and shearing according to the fixed length requirement to obtain the target I-steel.
In the step A, the molten iron comprises the following chemical components: 3.80 to 4.5 weight percent of C, 0.20 to 0.50 weight percent of Si, 0.15 to 0.50 weight percent of Mn, 0.070 to 0.090 weight percent of P, less than or equal to 0.030 weight percent of S, and the balance of Fe and inevitable impurities.
In the step A or B, the pretreated molten iron comprises the following components: 3.8 to 4.5 weight percent of C, 0.20 to 0.50 weight percent of Si, 0.15 to 0.50 weight percent of Mn, 0.070 to 0.090 weight percent of P, less than or equal to 0.010 weight percent of S, and the balance of Fe and inevitable impurities.
In the step B, the chemical components of the high-quality scrap steel are as follows: 0.18 to 0.25 weight percent of C, 0.30 to 0.50 weight percent of Si, 1.25 to 1.55 weight percent of Mn, 0.015 to 0.025 weight percent of P, 0.011 to 0.023 weight percent of S, and the balance of Fe and inevitable impurities.
In the step B, the chemical components of the low-phosphorus and low-sulfur pig iron are as follows: c4.10-4.35 wt%, si 0.30-0.55 wt%, mn 0.25-0.40 wt%, P0.060-0.080 wt%, S0.010-0.025 wt%, and the balance Fe and inevitable impurities.
In the step E, a ladle long nozzle (with argon seal protection) and a crystallizer submerged nozzle are adopted for protecting pouring to prevent molten steel from secondary oxidation; in order to prevent the center segregation of the casting blank, dynamic soft reduction is carried out, the reduction of a single roller of a 7-frame withdrawal and straightening machine per stream is 15-18 mm, and the reduction of the single roller is not more than 20mm.
And G, controlling the temperature difference between the head, the middle and the tail of the poker billet to be lower than 50 ℃ and the temperature difference between the sections to be lower than 30 ℃.
The present invention is further illustrated by the following examples.
Example 1
A. Desulfurizing by a molten iron KR method: transporting molten iron (chemical components C3.80 wt%, si 0.20wt%, mn 0.15wt%, P0.070 wt%, S less than or equal to 0.017wt%, and Fe and inevitable impurities as the rest) to a desulfurization station, firstly carrying out slag pre-skimming operation on the molten iron, carrying out desulfurization operation on the molten iron to a desulfurization position after skimming, and carrying out desulfurization operation on the molten iron by using CaO + CaF 2 "(weight ratio: caO:88%, caF2: 12%) as desulfurizing agent, at a ratio of 6.0kg/t Iron Adding, wherein the immersion depth of a stirrer is 1100mm, the starting rotating speed is 25r/min, starting the stirrer, the rotating speed is 90r/min, the stirring time is 8min, removing the desulphurization slag after the stirring is finished, and the pretreated molten iron comprises the following components: 3.80wt% of C, 0.20wt% of Si, 0.15wt% of Mn, 0.070wt% of P, 0.007wt% of S and the balance of Fe and inevitable impurities.
B. Smelting molten steel: the molten iron (weight percentage: C3.80 wt%, si 0.20wt%, mn 0.15wt%, P0.070 wt%, S0.007wt%, the balance being Fe and unavoidable impurities), high-quality scrap (weight percentage: C0.18 wt%, si 0.30wt%, mn 1.25wt%, P0.015 wt%, S0.011 wt%, the balance being Fe and unavoidable impurities) and low-sulfur phosphorus pig iron (weight percentage: C4.10 wt%, si 0.30wt%, mn 0.25wt%, P0.060 wt%, S0.010 wt%, the balance being Fe and unavoidable impurities) after A pretreatment were each 950kg/t Steel 、115kg/t Steel 、20kg/t Steel The mixture ratio is added into a converter for top-bottom composite blowing, and the blowing is carried out according to 20kg/t Steel 、15kg/t Steel According to the addition amount of the slag, lime and light burned dolomite are added for slagging, the end point carbon content is controlled to be 0.05wt%, and the tapping temperature is controlled to be 1615 ℃; in order to reduce nitrogen increase of the molten steel of the converter, smelting in a top-bottom combined blowing full-process bottom argon blowing mode in the first 2 furnaces before smelting; in order to ensure the quality of molten steel, a slag washing desulfurizer (Al is formed by mass percent) is added into a steel ladle in the tapping process 2 O 3 18%、SiO 2 4 percent of CaO, 44 percent of MgO, 3 percent of Al, 1 percent of TFe and the balance of other inevitable impurities) is subjected to slag washing desulfurization, and the addition amount of the slag washing desulfurizer is 2.0kg/t Steel (ii) a The whole bottom argon blowing process is adopted in the tapping process, and the flow rate of argon is controlled to be 25NL/min.
C. And (3) deoxidation alloying: tapping the molten steel smelted in the step B, and when the molten steel amount in the ladle is more than 1/4, carrying out the following deoxidation alloying sequence: low-silicon deoxidizer → silicon calcium barium → ferrosilicon → silicomanganese → ferro-aluminum, the following substances are added into the ladle in sequence: at a rate of 1.4kg/t Steel The following low-silicon deoxidizer is added in the following mass ratio: caC 2 62wt%, si 5wt%, C6 wt%, P0.080 wt%, S0.150 wt%, and the balance Fe and inevitable impurities; at a rate of 2.0kg/t Steel Adding the following silicon, calcium and barium in mass ratio: 49.3wt% of Si, 9.5wt% of Ca, 13.4wt% of Ba, 1.2wt% of Al, and the balance of Fe and inevitable impurities; at a rate of 0.5kg/t Steel Adding the following ferrosilicon in percentage by mass: 73.6wt% of Si, and the balance of Fe and inevitable impurities; at 5.2kg/t Steel Adding the following silicon and manganese in mass ratio: 16.3wt% of Si, 66.2wt% of Mn, and the balance of Fe and inevitable impurities; at a rate of 1.0kg/t Steel Adding the following aluminum iron in mass ratio: al 50wt%, the balance Fe and inevitable impurities; finishing the alloy when the molten steel amount in the steel ladle reaches 3/4; during tapping, a whole-process bottom argon blowing process is adopted, and the flow rate of argon is controlled to be 25NL/min; and after tapping, hoisting the molten steel to an LF furnace for refining.
D. Molten steel LF refining: c, hoisting the molten steel after the steel tapping in the step C to an LF refining station, connecting an argon pipe, blowing argon to enable the liquid level of the molten steel to be in a creeping state, electrifying for slagging for 5 minutes, determining oxygen in the molten steel, measuring the temperature, taking a steel sample, adding alloy and aluminum iron according to the analysis result of the steel sample, adjusting the components of the molten steel, controlling the oxygen activity of the molten steel to be 25ppm, and then controlling the oxygen activity to be 0.25kg/t Steel Adding the following ferroboron in mass ratio: b22 wt%, the balance being Fe and inevitable impurities, blowing argon for 3 minutes in a soft blowing manner, wherein the argon flow range is 15NL/min, then heating the molten steel to 1610 ℃, feeding calcium silicate wire at a wire feeding amount of 150 m/furnace and a wire feeding speed of 3.5m/s (210 m/min), and feeding calcium silicate wire with the following mass ratio: ca 25.6 wt%, si 52.8wt%, and the balance Fe and inevitable impurities; then, soft argon blowing is carried out for 12min; then adding molten steel covering agent, wherein the adding amount is controlled to be 0.6kg/t Steel And then, hoisting the molten steel to a continuous casting machine for casting.
E. Casting molten steel: and (4) hoisting the molten steel in the step E to a R12m5 machine 5-flow bloom continuous casting machine to cast into a billet with the thickness of 230mm multiplied by 230 mm. The casting conditions were: crystallizer cooling water 170m 3 The secondary cooling adopts aerial fog cooling (the compressed air pressure is 0.30 MPa), the specific water amount of the secondary cooling is 0.38L/kg, the casting temperature of the tundish is 1535 ℃, the pulling speed is controlled at 1.50m/min, and a ladle long nozzle (with argon seal protection) and a crystallizer submerged nozzle are adopted for protection casting to prevent the secondary oxidation of the molten steel; in order to prevent the center segregation of the casting blank, dynamic soft reduction is carried out, and the reduction amount of a single roller of each 7-frame withdrawal and straightening machine is 15mm.
F. Heating a steel billet: feeding the steel billet into a stepping heating furnace with the furnace temperature of 1300 ℃ at a soaking section through a hot feeding roller way, heating for 45min, and feeding the steel billet into a BD cogging mill for rolling;
G. rolling a steel billet: c, carrying out reciprocating rolling on the billet obtained in the step F in a BD cogging rolling mill for 5 times under the rolling conditions that the cogging temperature is 1120 ℃ and the speed is 3m/s, then sending the billet into a universal rolling mill, carrying out continuous rolling for 10 times at the speed of 5m/s, and controlling the final rolling temperature to be 950 ℃ to obtain I-shaped steel; the stable and uniform initial rolling temperature of the billet needs to be kept in the rolling process, the temperature difference between the head, the middle and the tail of the billet of the poker bar is 35 ℃, and the temperature difference between the sections is 20 ℃. Sending the rolled I-steel to a cooling bed for long-length natural cooling, further sending the cooled I-steel to a straightening machine for straightening, and shearing according to the fixed-length requirement to obtain the high-cleanliness boron-containing high-hardenability hot-rolled I-steel, which comprises the following chemical components in percentage by weight: 0.11wt% of C, 0.10wt% of Si, 0.35wt% of Mn, 0.0018wt% of B, 0.007wt% of S, 0.009wt% of P, 0.0015wt% of O, and N0.0025wt%, and the balance of Fe and inevitable impurities.
The process mechanical property, microstructure, grain size and non-metallic inclusion inspection of the high-cleanliness boron-containing high-hardenability hot-rolled I-shaped steel provided by the embodiment are shown in table 2.
Table 2 mechanical properties and metallographic structure of high-cleanliness boron-containing high-hardenability hot-rolled I-steel produced in example 1
Figure 765393DEST_PATH_IMAGE002
Example 2
A. Molten iron KR method desulfurization: transporting molten iron (chemical components of C4.20wt%, si 0.36wt%, mn 0.32wt%, P0.079 wt%, S0.023 wt%, and the balance of Fe and inevitable impurities) to a desulfurization station, firstly carrying out slag pre-skimming operation on the molten iron, carrying out desulfurization operation on the molten iron to a desulfurization station after slag skimming, and carrying out desulfurization operation on the molten iron by using CaO + CaF 2 "(the weight ratio: caO:89%, caF) 2 : 11%) as desulfurizing agent at a rate of 12kg/t Iron Adding, controlling the immersion depth of a stirrer to be 1300mm, setting the starting rotating speed to be 30r/min, starting the stirrer, controlling the normal rotating speed to be 110r/min, controlling the stirring time to be 11min, removing the desulphurization slag after the stirring is finished, and controlling the components of the pretreated molten iron to be: c4.20wt%, si 0.36wt%, mn 0.32wt%, P0.079 wt%, S0.08 wt%, and the balance of Fe and inevitable impurities.
B. Smelting molten steel: a pretreated molten iron (weight percentage: C4.20wt%, si 0.36wt%, mn 0.32wt%, P0.079 wt%, S0.08 wt%, and the balance Fe and unavoidable impurities), high-quality scrap steel (weight percentage: C0.22 wt%, si 0.40wt%, mn 1.35wt%, P0.020 wt%, S0.017 wt%, and the balance Fe and unavoidable impurities), and low-sulfur phosphorus pig iron (weight percentage: C4.23 wt%, si 0.45wt%, mn 0.33wt%, P0.070 wt%, S0.013 wt%, and the balance Fe and unavoidable impurities) were, respectively, at 950kg/t Steel 、115kg/t Steel 、20kg/t Steel The mixture ratio is added into a converter for top-bottom composite blowing, and the blowing is carried out according to 25kg/t Steel 、17.5kg/t Steel According to the addition amount of the slag, lime and light burned dolomite are added for slagging, the end point carbon content is controlled to be 0.06wt%, and the tapping temperature is 1633 ℃; in order to reduce nitrogen increase of the molten steel of the converter, the first 2 furnaces before smelting adopt a top-bottom combined blowing whole-course bottom argon blowing mode for smelting; in order to ensure the quality of molten steel, a slag washing desulfurizer (Al is formed by mass percent) is added into a steel ladle in the tapping process 2 O 3 19.0%、SiO 2 4.7 percent of CaO, 46.5 percent of MgO, 4.5 percent of Al, 8.9 percent of TFe and the balance of other inevitable impurities) is subjected to slag washing desulfurization, and the addition amount of the slag washing desulfurizing agent is 2.5kg/t Steel (ii) a The whole bottom argon blowing process is adopted in the tapping process, and the argon flow is controlled to be 28NL/min.
C. And (3) deoxidation alloying: tapping the molten steel smelted in the step B, and when the molten steel amount in the ladle is more than 1/4, carrying out the following deoxidation alloying sequence: low-silicon deoxidizer → silicon calcium barium → ferrosilicon → silicomanganese → ferro-aluminum, the following substances are added into the ladle in sequence: at a rate of 1.5kg/t Steel Adding the following low-silicon deoxidizer in mass ratio: caC 2 62wt%, si 5wt%, C6 wt%, P0.080 wt%, S0.150 wt%, and the balance Fe and inevitable impurities; at a rate of 2.3kg/t Steel Adding the following silicon, calcium and barium in mass ratio: 49.8wt% of Si, 9.1wt% of Ca, 13.2wt% of Ba, 1.4wt% of Al, and the balance of Fe and inevitable impurities; at a rate of 0.7kg/t Steel Adding the following ferrosilicon in percentage by mass: 73.5wt% of Si, and the balance of Fe and inevitable impurities; at 5.5kg/t Steel Adding the following silicon and manganese in mass ratio: 16.8wt% of Si, 66.5wt% of Mn and the balance of Fe and inevitable impurities; at a rate of 0.6kg/t Steel Adding the following aluminum iron in mass ratio: al 50wt%, and the balance of Fe and inevitable impurities; finishing the alloy when the molten steel amount of the steel ladle reaches 3/4; during tapping, a whole-process bottom argon blowing process is adopted, and the flow rate of argon is controlled to be 28NL/min; and after tapping, hoisting the molten steel to an LF furnace for refining.
D. Molten steel LF refining: c, hoisting the molten steel after the steel is discharged in the step C to a refining station of an LF furnace, connecting an argon pipe, blowing argon to enable the liquid level of the molten steel to be in a creeping state, electrifying for slagging for 7 minutes, determining oxygen in the molten steel, measuring the temperature to obtain a steel sample, adding alloy and aluminum iron according to the analysis result of the steel sample to adjust the components of the molten steel, controlling the oxygen activity of the molten steel to be 20ppm, and then controlling the oxygen activity to be 0.28kg/t Steel Adding the following ferroboron in mass ratio: b22 wt%, the balance being Fe and inevitable impurities, blowing argon for 3 minutes in a soft blowing manner, wherein the argon flow range is 18NL/min, then heating the molten steel to 1620 ℃, feeding calcium silicate wire at a wire feeding amount of 135 m/furnace and a wire feeding speed of 3.5m/s (210 m/min), and feeding calcium silicate wire with the following mass ratio: ca 25.6 wt%, si 52.8wt%, and the balance Fe and inevitable impurities; then, soft argon blowing is carried out for 12min; then adding molten steel covering agent, wherein the adding amount is controlled to be 0.7kg/t Steel And then, hoisting the molten steel to a continuous casting machine for casting.
E. Casting molten steel: and D, hoisting the molten steel in the step D to a R12m5 machine 5-flow bloom continuous casting machine to cast into a 230mm multiplied by 230mm steel blank. The casting conditions were: crystallizer cooling water 175m 3 Performing secondary cooling by adopting gas spray cooling (the compressed air pressure is 0.30 MPa), controlling the secondary cooling specific water amount to be 0.38L/kg, the casting temperature of a tundish to be 1545 ℃, controlling the pulling speed to be 1.40m/min, and protecting and casting by adopting a ladle long nozzle (with argon seal protection) and a crystallizer submerged nozzle to prevent molten steel from secondary oxidation; in order to prevent the center segregation of the casting blank, dynamic soft reduction is carried out, and the reduction amount of a single roller of each 7-frame withdrawal and straightening machine is 16mm.
F. Heating a steel billet: feeding the steel billet into a stepping heating furnace with the furnace temperature of the soaking section of 1270 ℃ through a hot roller feeding way, heating for 47min, and feeding the steel billet into a BD cogging mill for rolling;
G. rolling a steel billet: c, carrying out reciprocating rolling on the billet obtained in the step F in a BD cogging rolling mill for 5 times under the rolling conditions that the cogging temperature is 1140 ℃ and the speed is 3m/s, then sending the billet into a universal rolling mill, carrying out continuous rolling for 10 times at the speed of 5m/s, and controlling the final rolling temperature to 970 ℃ to obtain I-steel; the stable and uniform initial rolling temperature of the billet is kept in the rolling process, the temperature difference of the head, the middle and the tail of the billet of the poker bar is 30 ℃, and the temperature difference of the cross section is 25 ℃. Sending the rolled I-steel to a cooling bed for long-length natural cooling, further sending the cooled I-steel to a straightening machine for straightening, and shearing according to the fixed-length requirement to obtain the high-cleanliness boron-containing high-hardenability hot-rolled I-steel, which comprises the following chemical components in percentage by weight: 0.15wt% of C, 0.23wt% of Si, 0.47wt% of Mn, 0.0034wt% of B, less than or equal to 0.007wt% of S, less than or equal to 0.009wt% of P, less than or equal to 0.0008wt% of O0.0025wt% of N, and the balance of Fe and inevitable impurities.
The process mechanical properties, the microstructure, the grain size and the non-metallic inclusion of the high-cleanliness boron-containing high-hardenability hot-rolled I-shaped steel provided by the embodiment are checked and shown in table 3.
TABLE 3 mechanical Properties, texture and grain size of high-cleanliness boron-containing high-hardenability hot-rolled I-steel produced in example 2
Figure DEST_PATH_IMAGE003
Example 3
A. Desulfurizing by a molten iron KR method: transporting molten iron (chemical components of C4.5wt%, si 0.50wt%, mn 0.50wt%, P0.090 wt%, S0.030wt%, and the balance of Fe and inevitable impurities) to a desulfurization station, firstly carrying out slag pre-skimming operation on the molten iron, carrying out desulfurization operation on the molten iron to a desulfurization position after slag skimming, and carrying out desulfurization operation on the molten iron by using CaO + CaF 2 "(the weight ratio: 90% of CaO, caF 2 : 10%) as desulfurizing agent, at a rate of 15kg/t Iron Adding, controlling the immersion depth of a stirrer to be 1500mm, setting the starting rotating speed to be 35r/min, starting the stirrer, controlling the normal rotating speed to be 120r/min, controlling the stirring time to be 15min, removing the desulphurization slag after the stirring is finished, and controlling the components of the pretreated molten iron as follows: 4.5wt% of C, 0.50wt% of Si, 0.50wt% of Mn, 0.090wt% of P, 0.008wt% of S, and the balance of Fe and inevitable impurities.
B. Smelting molten steel: the molten iron (weight percentage: 4.5wt%, si 0.50wt%, mn 0.50wt%, P0.090 wt%, S0.008 wt%, and the balance Fe and unavoidable impurities) after A pretreatment, high-quality scrap (weight percentage: C0.25 wt%, si 0.50wt%, mn 1.55wt%, P0.025 wt%, S0.023 wt%, and the balance Fe and unavoidable impurities), and low-sulfur phosphorus pig iron (weight percentage: C4.35 wt%, si 0.55wt%, mn 0.40wt%, P0.080 wt%, S0.025 wt%, and the balance Fe and unavoidable impurities) were 950kg/t, respectively Steel 、115kg/t Steel 、20kg/t Steel The mixture ratio is added into a converter for top-bottom composite blowing, and the blowing is respectively carried out according to 30.0kg/t Steel 、20kg/t Steel Adding lime and light burned dolomite for slagging, controlling the end point carbon content to be 0.08wt% and the tapping temperature to be 1650 ℃; in order to reduce nitrogen increase of the molten steel of the converter, the first 2 furnaces before smelting adopt a top-bottom combined blowing whole-course bottom argon blowing mode for smelting; in order to ensure the quality of molten steel, a slag washing desulfurizer (Al is formed by mass percent) is added into a steel ladle in the tapping process 2 O 3 20%、SiO 2 5 percent of CaO, 48 percent of MgO, 10 percent of Al, 3 percent of TFe and the balance of other inevitable impurities) is subjected to slag washing desulfurization, and the addition amount of slag washing desulfurizer is 3kg/t Steel (ii) a The whole bottom argon blowing process is adopted in the tapping process, and the argon flow is controlled to be 30NL/min.
C. And (3) deoxidation alloying: tapping the molten steel smelted in the step B, and when the molten steel amount in the ladle is more than 1/4, carrying out the following deoxidation alloying sequence: low-silicon deoxidizer → silicon calcium barium → ferrosilicon → silicomanganese → ferro-aluminum, the following substances are added into the ladle in sequence: at a rate of 1.6kg/t Steel The following low-silicon deoxidizer is added in the following mass ratio: caC 2 62wt%, si 5wt%, C6 wt%, P0.080 wt%, S0.150 wt%, and the balance Fe and inevitable impurities; at a rate of 2.5kg/t Steel Adding the following silicon, calcium and barium in mass ratio: 52wt% of Si, 10wt% of Ca, 14wt% of Ba, 1.5wt% of Al, and the balance of Fe and inevitable impurities; at a rate of 1.0kg/t Steel Adding the following ferrosilicon in percentage by mass: 75wt% of Si, and the balance of Fe and inevitable impurities; at 5.8kg/t Steel Adding the following silicon and manganese in mass ratio: 18wt% of Si, 68wt% of Mn, and the balance of Fe and inevitable impurities; at a rate of 0.3kg/t Steel Adding the following aluminum iron in mass ratio: al 50wt%, the balance Fe and inevitable impurities; finishing the alloy when the molten steel amount in the steel ladle reaches 3/4; during tapping, a whole-process bottom argon blowing process is adopted, and the flow rate of argon is controlled to be 30NL/min; and after tapping, hoisting the molten steel to an LF furnace for refining.
D. Molten steel LF refining: c, hoisting the molten steel after the steel is discharged in the step C to a refining station of an LF furnace, connecting an argon pipe, blowing argon to enable the liquid level of the molten steel to be in a creeping state, electrifying for slagging for 8 minutes, determining oxygen in the molten steel, measuring the temperature to obtain a steel sample, adding alloy and aluminum iron according to the analysis result of the steel sample to adjust the components of the molten steel, controlling the oxygen activity of the molten steel to be 15ppm, and then controlling the oxygen activity to be 0.32kg/t Steel Adding the following ferroboron in mass ratio: b22 wt%, the balance being Fe and inevitable impurities, blowing argon for 3 minutes in a soft blowing manner, wherein the argon flow range is 20NL/min, heating the molten steel to 1630 ℃, feeding calcium silicate wire at a wire feeding rate of 120 m/furnace and a wire feeding speed of 3.5m/s (210 m/min), and feeding calcium silicate wire with the following mass ratio: ca 25.6 wt%, si 52.8wt%, and the balance Fe and inevitable impurities; then, soft argon blowing is carried out for 10min, and alloy, deoxidizing agent or recarburizing agent is strictly forbidden to be added into the steel ladle after the argon blowing is finished; then adding molten steel covering agent, and controlling the adding amount to be 0.8kg/t Steel And then, hoisting the molten steel to a continuous casting machine for casting.
E. Casting molten steel: and D, hoisting the molten steel in the step D to a R12m5 machine 5-flow bloom continuous casting machine to cast into a 230mm multiplied by 230mm steel blank. The casting conditions were: 180m of cooling water of crystallizer 3 The secondary cooling adopts aerial fog cooling (the compressed air pressure is 0.30 MPa), the specific water amount of the secondary cooling is 0.38L/kg, the casting temperature of the tundish is 1555 ℃, the pulling speed is controlled at 1.30m/min, and a ladle long nozzle (with argon seal protection) and a crystallizer submerged nozzle are adopted for protecting casting to prevent the secondary oxidation of the molten steel; in order to prevent the center segregation of the casting blank, dynamic soft reduction is carried out, and the reduction amount of a single roller of each 7-frame withdrawal and straightening machine is 18mm.
F. Heating a steel billet: feeding the steel billet into a stepping heating furnace with the furnace temperature of the soaking section of 1230 ℃ through a hot roller way, heating for 50min, and feeding the steel billet into a BD cogging mill for rolling;
G. rolling a steel billet: c, carrying out reciprocating rolling on the billet obtained in the step F in a BD cogging rolling mill for 5 times under the rolling conditions that the cogging temperature is 1170 ℃ and the speed is 3m/s, then sending the billet into a universal rolling mill, carrying out continuous rolling for 10 times at the speed of 5m/s, and controlling the final rolling temperature to be 1000 ℃ to obtain I-shaped steel; the stable and uniform initial rolling temperature of the billet needs to be kept in the rolling process, the temperature difference of the head, the middle and the tail of the billet of the poker bar is 30 ℃, and the temperature difference of the cross section is 20 ℃. Sending the rolled I-steel to a cooling bed for long-length natural cooling, further sending the cooled I-steel to a straightening machine for straightening, and shearing according to the fixed-length requirement to obtain the high-cleanliness boron-containing high-hardenability hot-rolled I-steel, which comprises the following chemical components in percentage by weight: 0.18wt% of C, 0.35wt% of Si, 0.60wt% of Mn, 0.0050wt% of B, 0.005wt% of S, 0.010wt% of P, 0.0011wt% of O, and N0.0023wt% of N, with the balance being Fe and unavoidable impurities.
The process mechanical properties, microstructure, grain size and non-metallic inclusion inspection of the high-cleanliness boron-containing high-hardenability hot-rolled I-shaped steel provided by the embodiment are shown in table 4.
Table 4 mechanical properties and metallographic structure of high-cleanliness boron-containing high-hardenability hot-rolled I-steel produced in example 3
Figure 563453DEST_PATH_IMAGE004
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Claims (8)

1. The preparation method of the high-cleanliness boron-containing high-hardenability hot-rolled I-shaped steel is characterized in that the I-shaped steel comprises the following chemical components in percentage by weight: 0.11 to 0.18wt% of C, 0.10 to 0.35wt% of Si, 0.35 to 0.60wt% of Mn, 0.0018 to 0.0050wt% of B, less than or equal to 0.010wt% of S, less than or equal to 0.010wt% of P, less than or equal to 0.0015wt% of O, less than or equal to 0.0030wt% of N, and the balance of Fe and inevitable impurities; the gas content of the I-shaped steel is less than or equal to 0.0015wt%, the gas content of N is less than or equal to 0.0030wt%, the thickness of a waist part is less than 16mm, the yield strength ReL is more than or equal to 245MPa, the tensile strength Rm is 380-500 MPa, the elongation A after fracture is more than or equal to 29%, the longitudinal impact energy Akv at 20 ℃ is more than or equal to 40J, a microstructure consists of more than 80% of ferrite and pearlite, the grain size is more than or equal to 8.5 grade, and the non-metallic inclusion is less than or equal to 1.5 grade; the preparation method is realized according to the following steps:
A. molten iron KR method desulfurization: conveying the molten iron to a desulfurization station for slagging-off operation before slagging-off of the molten iron, and desulfurizing the molten iron to a desulfurization position after slagging-off of the molten iron according to the proportion of 6 to 15kg/t Iron Adding CaO + CaF 2 The immersion depth of a desulfurizer and a stirrer is 1100-1500 mm, the starting rotating speed is 25-35r/min, the stirrer is started, the normal rotating speed is 90-120r/min, the stirring time is controlled to be 8-15min, and desulfurized slag is removed after stirring to obtain pretreated molten iron; the CaO + CaF 2 The desulfurizing agent comprises the following components in percentage by mass: caO:88 to 90% of CaF 2 ：10~12％；
B. Smelting in a molten steel converter: respectively treating the pretreated molten iron, high-quality scrap steel and low-phosphorus sulfur pig iron according to the weight ratio of 950kg/t Steel 、115kg/t Steel 、20kg/t Steel The mixture ratio is added into a converter for top-bottom composite blowing, and the blowing is respectively carried out according to the ratio of 20.0 to 30.0kg/t Steel 、15.0~20.0kg/t Steel Adding conventional lime and light-burned dolomite for slagging, controlling the end point carbon content to be 0.05-0.08wt%, and the tapping temperature to be 1615-1650 ℃; 2 to 3kg/t in a ladle before tapping Steel The slag washing desulfurizer is added for slag washing desulfurization, the whole bottom argon blowing process is adopted in the tapping process, and the argon flow is controlled to be 25-30NL/min; the slag washing desulfurizer consists of the following components in percentage by mass: al (Al) 2 O 3 18~20%、SiO 2 4~5%, caO 44-48%, mgO 3~6%, al 8-10%, TFe 1~3%, and the balance of other unavoidable impurities;
C. and (3) deoxidation alloying: tapping molten steel, and when the amount of the molten steel in a ladle is more than 1/4, carrying out the following deoxidation alloying sequence: low-silicon deoxidizer → silicon calcium barium → ferrosilicon → silicomanganese → ferro-aluminum, the following substances are added into the ladle in sequence: according to the ratio of 1.4 to 1.6kg/t Steel Adding the following low-silicon deoxidizer in mass ratio: caC 2 62wt%, si 5wt%, C6 wt%, P0.080 wt%, S0.150 wt%, and the balance Fe and inevitable impurities; at a ratio of 2.0 to 2.5kg/t Steel Adding the following silicon, calcium and barium in mass ratio: 48 to 52wt% of Si, 8 to 10wt% of Ca, 12 to 14wt% of Ba, less than or equal to 3wt% of Al, and the balance of Fe and inevitable impurities; at a ratio of 0.5 to 1.0kg/t Steel Adding the following ferrosilicon in percentage by mass: 72 to 75wt% of Si, and the balance of Fe and inevitable impurities; at 5.2 to 5.8kg/t Steel Adding the following silicon and manganese in mass ratio: si 16 to 18wt%, mn 65 to 68wt%, and the balance of Fe and inevitable impurities; at 0.3 to 1.0kg/t Steel Adding the following aluminum iron in mass ratio: al 50wt%, the balance Fe and inevitable impurities; finishing the alloy when the molten steel amount in the steel ladle reaches 3/4; the whole bottom argon blowing process is adopted in the tapping process, and the flow rate of argon is controlled to be 25 to 30NL/min; after tapping, hoisting the molten steel to an LF furnace for refining;
D. refining in a molten steel LF furnace: hoisting the molten steel to an LF refining station, connecting an argon pipe, blowing argon to enable the liquid level of the molten steel to be in a creeping state, electrifying to melt slag for 5~8 minutes, then fixing oxygen to the molten steel, measuring the temperature to obtain a steel sample, adding alloy and aluminum iron according to the analysis result of the steel sample to adjust the components of the molten steel, controlling the oxygen activity of the molten steel to be 15 to 25ppm, and then controlling the oxygen activity to be 0.25 to 0.32kg/t Steel Adding the following ferroboron in mass ratio: b22 wt%, the balance being Fe and inevitable impurities; soft argon blowing is carried out for 3 minutes, the flow range of the argon is 15 to 20NL/min, then the molten steel is heated to 1610 to 1630 ℃, then calcium silicon wire feeding treatment is carried out, and calcium silicon wires with the following mass ratio are fed: ca 25.6 wt%, si 52.8wt%, and the balance Fe and inevitable impurities; the wire feeding amount is 120 to 150m/furnace, the wire feeding speed is 3.5m/s, and then soft argon blowing is carried out, wherein argon is used for blowingThe flow range is 15 to 20NL/min, and the argon blowing time is more than or equal to 10min; then adding the molten steel covering agent, wherein the adding amount is controlled to be 0.6 to 0.8 kg/t Steel Then, hoisting the molten steel to a continuous casting machine for casting;
E. casting molten steel: the temperature of a tundish ranges from 1535 ℃ to 1555 ℃, the drawing speed ranges from 1.30 to 1.50m/min, and the cooling water flow of a crystallizer ranges from 170 to 180m 3 H, performing secondary cooling by adopting gas mist cooling with the compressed air pressure of 0.30MPa, and casting the molten steel into a billet with the thickness of 230mm multiplied by 230mm by using an R12m5 machine 5-flow bloom continuous casting machine under the condition that the secondary cooling specific water amount is 0.38L/kg;
F. heating a steel billet: feeding the steel blank into a stepping heating furnace with a soaking section furnace temperature of 1230-1300 ℃ through a hot roller conveyor to heat for 45-50min, and feeding the steel blank into a BD cogging mill to roll;
G. billet rolling: carrying out reciprocating rolling on the billet for 5 times under the rolling conditions that the initial rolling temperature is 1120 to 1170 ℃ and the speed is 3m/s, then sending the billet into an universal rolling mill, carrying out continuous rolling for 10 times at the speed of 5m/s, and controlling the final rolling temperature to be 950 to 1000 ℃ to obtain I-shaped steel; and (3) feeding the rolled steel to a long ruler on a cooling bed for natural cooling, further feeding the cooled I-steel to a straightening machine for straightening, and shearing according to the fixed length requirement to obtain the target I-steel.
2. The preparation method according to claim 1, wherein in the step A, the molten iron comprises the following chemical components: c3.80-4.5 wt%, si 0.20-0.50wt%, mn 0.15-0.50wt%, P0.070-0.090wt%, S less than or equal to 0.030wt%, and the balance of Fe and inevitable impurities.
3. The manufacturing method according to claim 1, wherein in the step a or B, the composition of the pretreated molten iron is controlled as follows: 3.8 to 4.5wt% of C, 0.20 to 0.50wt% of Si, 0.15 to 0.50wt% of Mn, 0.070 to 0.090wt% of P, less than or equal to 0.010wt% of S, and the balance of Fe and inevitable impurities.
4. The preparation method according to claim 1, wherein in the step B, the chemical components of the high-quality scrap steel are as follows: 0.18 to 0.25wt% of C, 0.30 to 0.50wt% of Si, 1.25 to 1.55wt% of Mn, 0.015 to 0.025wt% of P, 0.011 to 0.023wt% of S, and the balance of Fe and inevitable impurities.
5. The method as claimed in claim 1, wherein in step B, the chemical composition of the low phosphorus-sulfur pig iron is as follows: c4.10-4.35wt%, si 0.30-0.55wt%, mn 0.25-0.40wt%, P0.060-0.080wt%, S0.010-0.025wt%, and the balance of Fe and inevitable impurities.
6. The preparation method according to claim 1, wherein in the step E, a ladle long nozzle and a crystallizer submerged nozzle are adopted for protecting pouring so as to prevent secondary oxidation of molten steel; the single-roll reduction of a drawing and straightening machine with 7 frames per flow is 15 to 18mm, and the single-roll reduction is not more than 20mm.
7. The method of claim 1, wherein in step G, the temperature difference between the head, the middle and the tail of the billet is controlled to be less than 50 ℃ and the temperature difference between the cross sections is controlled to be less than 30 ℃.
8. A high-cleanliness boron-containing high-hardenability hot-rolled i-steel obtained by the production method of any one of claims 1~7.
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CN101255527A (en) * 2008-03-17 2008-09-03 莱芜钢铁股份有限公司 Boron-modified H-shape steel having well low-temperature impact flexibility and preparation method thereof

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