CN111074157B - Low-niobium microalloyed HRB400E ultrafine-grain high-toughness anti-seismic steel bar and preparation method thereof - Google Patents
Low-niobium microalloyed HRB400E ultrafine-grain high-toughness anti-seismic steel bar and preparation method thereof Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 260
- 239000010959 steel Substances 0.000 title claims abstract description 260
- 239000010955 niobium Substances 0.000 title claims abstract description 40
- 229910052758 niobium Inorganic materials 0.000 title claims abstract description 24
- 238000002360 preparation method Methods 0.000 title claims abstract description 18
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 105
- 238000001816 cooling Methods 0.000 claims abstract description 72
- 239000012535 impurity Substances 0.000 claims abstract description 64
- 238000005096 rolling process Methods 0.000 claims abstract description 60
- 239000000126 substance Substances 0.000 claims abstract description 32
- 238000000034 method Methods 0.000 claims abstract description 29
- 230000008569 process Effects 0.000 claims abstract description 24
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 21
- 238000010438 heat treatment Methods 0.000 claims abstract description 21
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 96
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 56
- 229910052786 argon Inorganic materials 0.000 claims description 48
- 238000010079 rubber tapping Methods 0.000 claims description 38
- 239000011572 manganese Substances 0.000 claims description 29
- 238000005266 casting Methods 0.000 claims description 24
- 229910052742 iron Inorganic materials 0.000 claims description 24
- 238000007664 blowing Methods 0.000 claims description 18
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 18
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 18
- 229910052710 silicon Inorganic materials 0.000 claims description 16
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 12
- 229910000616 Ferromanganese Inorganic materials 0.000 claims description 12
- 229910000592 Ferroniobium Inorganic materials 0.000 claims description 12
- 229910000519 Ferrosilicon Inorganic materials 0.000 claims description 12
- 229910000805 Pig iron Inorganic materials 0.000 claims description 12
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 12
- 238000005275 alloying Methods 0.000 claims description 12
- 229910000514 dolomite Inorganic materials 0.000 claims description 12
- 239000010459 dolomite Substances 0.000 claims description 12
- DALUDRGQOYMVLD-UHFFFAOYSA-N iron manganese Chemical compound [Mn].[Fe] DALUDRGQOYMVLD-UHFFFAOYSA-N 0.000 claims description 12
- 239000004571 lime Substances 0.000 claims description 12
- 239000001095 magnesium carbonate Substances 0.000 claims description 12
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 claims description 12
- 229910000021 magnesium carbonate Inorganic materials 0.000 claims description 12
- 235000014380 magnesium carbonate Nutrition 0.000 claims description 12
- 238000007670 refining Methods 0.000 claims description 12
- 239000002893 slag Substances 0.000 claims description 12
- 238000005406 washing Methods 0.000 claims description 12
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 11
- ZFGFKQDDQUAJQP-UHFFFAOYSA-N iron niobium Chemical compound [Fe].[Fe].[Nb] ZFGFKQDDQUAJQP-UHFFFAOYSA-N 0.000 claims description 10
- 229910052748 manganese Inorganic materials 0.000 claims description 10
- 238000003723 Smelting Methods 0.000 claims description 7
- 229910045601 alloy Inorganic materials 0.000 claims description 7
- 239000000956 alloy Substances 0.000 claims description 7
- 239000000498 cooling water Substances 0.000 claims description 7
- 229910000914 Mn alloy Inorganic materials 0.000 claims description 6
- 229910000720 Silicomanganese Inorganic materials 0.000 claims description 6
- 239000011575 calcium Substances 0.000 claims description 6
- 239000003795 chemical substances by application Substances 0.000 claims description 6
- PYLLWONICXJARP-UHFFFAOYSA-N manganese silicon Chemical compound [Si].[Mn] PYLLWONICXJARP-UHFFFAOYSA-N 0.000 claims description 6
- -1 silicon-aluminum-calcium Chemical compound 0.000 claims description 6
- 238000002791 soaking Methods 0.000 claims description 6
- 229910052681 coesite Inorganic materials 0.000 claims description 5
- 229910052906 cristobalite Inorganic materials 0.000 claims description 5
- 239000000377 silicon dioxide Substances 0.000 claims description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 5
- 229910052682 stishovite Inorganic materials 0.000 claims description 5
- 229910052905 tridymite Inorganic materials 0.000 claims description 5
- 239000002131 composite material Substances 0.000 claims description 4
- 238000012545 processing Methods 0.000 claims description 3
- 229910000859 α-Fe Inorganic materials 0.000 abstract description 8
- 238000005728 strengthening Methods 0.000 abstract description 6
- 229910001566 austenite Inorganic materials 0.000 abstract description 4
- 239000013078 crystal Substances 0.000 abstract description 4
- 239000011159 matrix material Substances 0.000 abstract description 4
- 230000000694 effects Effects 0.000 abstract description 3
- 238000001556 precipitation Methods 0.000 abstract description 3
- 230000032683 aging Effects 0.000 abstract description 2
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 2
- 238000003466 welding Methods 0.000 abstract description 2
- JMAHHHVEVBOCPE-UHFFFAOYSA-N [Fe].[Nb] Chemical compound [Fe].[Nb] JMAHHHVEVBOCPE-UHFFFAOYSA-N 0.000 abstract 1
- 238000004519 manufacturing process Methods 0.000 description 9
- 229910001294 Reinforcing steel Inorganic materials 0.000 description 7
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 5
- 239000010703 silicon Substances 0.000 description 5
- 238000007689 inspection Methods 0.000 description 4
- 229910052720 vanadium Inorganic materials 0.000 description 4
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 4
- 238000009749 continuous casting Methods 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- SKKMWRVAJNPLFY-UHFFFAOYSA-N azanylidynevanadium Chemical compound [V]#N SKKMWRVAJNPLFY-UHFFFAOYSA-N 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000018109 developmental process Effects 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 229910000628 Ferrovanadium Inorganic materials 0.000 description 1
- 229910001199 N alloy Inorganic materials 0.000 description 1
- 229910000756 V alloy Inorganic materials 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- PNXOJQQRXBVKEX-UHFFFAOYSA-N iron vanadium Chemical compound [V].[Fe] PNXOJQQRXBVKEX-UHFFFAOYSA-N 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 239000011150 reinforced concrete Substances 0.000 description 1
- 239000012779 reinforcing material Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 230000035882 stress Effects 0.000 description 1
Classifications
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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
-
- 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
- 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
- C21D8/08—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires for concrete reinforcement
-
- 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
-
- 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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
-
- 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
- C21D2211/001—Austenite
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- 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
- C21D2211/002—Bainite
-
- 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
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- 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
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- Organic Chemistry (AREA)
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Abstract
The invention discloses a low-niobium microalloyed HRB400E ultrafine-grain high-toughness anti-seismic steel bar and a preparation method thereof, wherein the steel bar comprises the following chemical components in parts by weight: 0.20-0.24 wt% of C, 0.38-0.48 wt% of Si, 1.30-1.50 wt% of Mn, 0.014-0.019 wt% of Nb, less than or equal to 0.040wt% of S, less than or equal to 0.045wt% of P, less than or equal to 0.0070wt% of O, less than or equal to 0.0075wt% of N, and the balance of Fe and inevitable impurities; the preparation method adopts lower heating temperature and start rolling temperature for steel rolling, refines original austenite grains, promotes the refinement of ferrite grains when austenite is transformed into ferrite, has grain size reaching more than 11.0 grade, has obvious fine-grain strengthening effect, and simultaneously improves the plastic toughness of the steel; the niobium-iron is added into the steel, the low initial rolling temperature is controlled, and the multi-section low-water-pressure grading controlled cooling process after rolling is adopted, so that the driving force for Nb (C, N) precipitation is increased, and a large amount of fine and dispersed second phases are precipitated on a low-temperature ferrite matrix, a crystal boundary and a dislocation line, so that the ferrite matrix is strengthened, the strength of the steel is obviously improved, and the performances of the steel, such as welding, aging and the like, are improved.
Description
Technical Field
The invention belongs to the technical field of metallurgy, and particularly relates to a low-niobium microalloyed HRB400E ultrafine-grain high-toughness anti-seismic steel bar and a preparation method thereof.
Background
Hot rolled ribbed bars are the primary reinforcing material for reinforced concrete building structures, carrying stress and strain loads in the structure, such as tensile, compressive and strain loads. At present, the annual output of hot-rolled ribbed steel bars in China is about 2 hundred million tons, and the hot-rolled ribbed steel bars are steel materials which are most used for the construction of national economic building engineering structures. With the continuous development of buildings in China towards high-rise, large-span and anti-seismic structures, the development of fine-grained anti-seismic steel bars with high toughness and excellent comprehensive performance is one of the important tasks of improving the technical level and adjusting the product structure in the steel industry.
With the continuous upgrading of building structures in recent years, the strength of steel is continuously improved, and the upgrading and updating of the reinforcing steel bars for buildings and the modification and perfection of product standards are promoted. The national standard GB/T1499.2-2018 of the hot-rolled ribbed steel bar is formally implemented in 2018, 11/1.2018, the new standard adds metallographic structure inspection regulations and a matched macroscopic metallographic structure, section Vickers hardness and microstructure inspection method, makes stricter and more definite regulations on steel bar performance, quality inspection and judgment, puts higher and stricter requirements on the production process, and has a positive propulsion effect on improving the quality of the hot-rolled ribbed steel bar product, promoting energy conservation and emission reduction and eliminating the backward capacity.
After the GB/T1499.2-2018 standard is implemented, domestic main hot-rolled ribbed steel bar production enterprises basically adopt a vanadium microalloying process to produce straight ribbed steel bars, and simultaneously, through optimizing chemical component control and a rolling process, the Vickers hardness of macroscopic metallographic phase, microstructure and section of the steel bars is ensured to meet the new standard inspection requirements. The HRB400E is produced by adopting a vanadium microalloying process, a certain amount of vanadium-nitrogen alloy or nitrided ferrovanadium is added into steel, and the vanadium alloy is expensive, so that the production cost is higher, and the reduction of the production cost of a reinforcing steel bar enterprise and the improvement of the market competitiveness of a product are not facilitated.
At present, related research reports of HRB400E straight anti-seismic steel bar production technology after GB/T1499.2-2018 standard implementation exist in China, but a vanadium-nitrogen microalloying process is mainly adopted, the content of V in steel is controlled to be 0.025-0.035 wt%, HRB400E steel bars with macroscopic metallographic phase, section Vickers hardness and microstructure meeting GB/T1499.2-2018 standard are obtained through a proper controlled rolling and controlled cooling process, and the grain size of the microstructure of the steel bars is mostly controlled to be 9.5-10.5 grade. At present, no research report on the preparation method of the low-niobium (Nb is less than or equal to 0.019 wt%) microalloyed HRB400E ultrafine grain high-toughness anti-seismic reinforcing steel bar adopted by the invention exists in China.
Disclosure of Invention
Aiming at the situation that the production cost of HRB400E steel bars produced by adopting a vanadium microalloying process after the implementation of GB/T1499.2-2018 standard is high, the invention aims to provide a low-niobium microalloyed HRB400E ultrafine-grain high-toughness anti-seismic steel bar in a first mode, and aims to provide a preparation method of a low-niobium microalloyed HRB400E ultrafine-grain high-toughness anti-seismic steel bar in a second mode.
The first purpose of the invention is realized by that, the low-niobium microalloyed HRB400E ultra-fine grain high-toughness anti-seismic steel bar comprises the following chemical components by weight: 0.20 to 0.24wt% of C, 0.38 to 0.48wt% of Si, 1.30 to 1.50wt% of Mn, 0.014 to 0.019wt% of Nb, less than or equal to 0.040wt% of S, less than or equal to 0.045wt% of P, less than or equal to 0.0070wt% of O, less than or equal to 0.0075wt% of N, and the balance of Fe and inevitable impurities.
The second purpose of the invention is realized in such a way that the preparation method of the low-niobium microalloyed HRB400E ultrafine-grained high-toughness anti-seismic steel bar specifically comprises the following steps:
A. smelting molten steel: respectively processing the scrap steel, the pig iron and the molten iron according to the temperature of 120-Steel、20kg/tSteel915 and 940kg/t are added into an LD converter, then conventional top-bottom composite blowing is carried out, conventional lime, light-burned dolomite and magnesite balls are added for slagging, and the addition amount of the lime is 20-25kg/tSteelThe addition amount of light-burned dolomite is 15-20kg/tSteelThe adding amount of the magnesite balls is 0.5kg/tSteelControlling the end point carbon content to be more than or equal to 0.08wt% and the tapping temperature to be less than or equal to 1650 ℃; 1.0kg/t of steel ladle bottom before tappingSteelAdding the following slag washing desulfurizer in mass ratio for slag washing: al (Al)2O321.5wt％，SiO25.2wt%, 46.5wt% of CaO, 9.2wt% of Al, 6.5wt% of MgO6, and the balance of Fe and inevitable impurities, wherein a whole bottom argon blowing process is adopted in the tapping process, and the argon flow is controlled to be 10-15 NL/min; the chemical components of the scrap steel comprise 0.12-0.20wt% of C, 0.35-0.60wt% of Si, 0.45-0.70wt% of Mn0.035-0.046 wt% of P, 0.028-0.039wt% of S, and the balance of Fe and inevitable impurities; 3.3-3.6wt% of pig iron chemical components C, 0.30-0.50wt% of Si, 0.32-0.55wt% of Mn, 0.058-0.075wt% of P, 0.018-0.027wt% of S, and the balance of Fe and inevitable impurities; the chemical components of the molten iron are C4.0-4.5 wt%, Si 0.15-0.35wt%, Mn 0.30-0.50wt%, P0.080-0.120 wt% and S less than or equal to 0.035wt%, and the temperature of the molten iron is more than or equal to 1280 ℃;
B. and (3) deoxidation alloying: tapping the molten steel, and when the amount of the molten steel in the ladle is more than 1/4, deoxidizing alloy as followsThe chemical sequence is as follows: silico-aluminum-calcium deoxidizer → silicon carbide → ferrosilicon → silicomanganese → high carbon ferromanganese → high silicon ferroniobium, the following substances are added into the steel ladle in sequence: at a rate of 1.0kg/tSteelAdding the following silicon-aluminum-calcium deoxidizer in mass ratio: 32.5wt% of Si, 16.8wt% of Ca, 10.6wt% of Al and the balance of Fe and inevitable impurities; at a rate of 1.8kg/tSteelAdding the following silicon carbide in mass ratio: 82.5wt% of SiC, 26.5wt% of C, 0.053wt% of P, 0.035wt% of S and the balance of inevitable impurities; according to 3.4-4.7 kg/tSteelAdding the following ferrosilicon in percentage by mass: 73.5wt% of Si, and the balance of Fe and inevitable impurities; at 9.1kg/tSteelAdding the following silicon-manganese alloy in mass ratio: 65.2wt% of Mn, 17.3wt% of Si, 1.8wt% of C, and the balance of Fe and inevitable impurities; according to the ratio of 10.2-12.2 kg/tSteelAdding the following high-carbon ferromanganese in mass ratio: mn75.3wt%, C7.1 wt%, and the balance Fe and inevitable impurities; according to 0.24-0.32kg/tSteelAdding the following ferroniobium in percentage by mass: 65.6wt% of Nb, 6.7wt% of Si, 0.35wt% of C, 0.214wt% of P, 0.075wt% of S, and the balance of Fe and inevitable impurities; when the amount of the molten steel in the steel ladle reaches 3/4, the alloy is added; after tapping, hoisting the molten steel to an argon station for refining treatment;
C. refining in a molten steel argon station: hoisting the molten steel to an argon station, connecting an argon band, starting argon, blowing the molten steel with argon at the flow rate of 15-25 NL/min for 4 minutes, and adding a molten steel covering agent, wherein the addition amount is controlled to be 1.0kg/tSteelThen, hoisting the molten steel to a casting station;
D. casting molten steel: the temperature of the tundish is 1523-1535 ℃, the pulling speed is 2.5-2.7 m/min, and the flow of the cooling water of the crystallizer is 110-120 m3H, adopting an R9m straight-arc continuous straightening 5-machine 5-flow small square billet casting machine to cast the molten steel into a billet with the cross section of 150mm multiplied by 150mm under the condition that the secondary cooling specific water amount is 1.5-1.7L/kg;
E. heating a steel billet: and (3) feeding the steel billet into a heating furnace with the furnace temperature of 1060-1100 ℃ in a soaking section, heating for 70-80 minutes, tapping, and then pushing to a full-continuous bar mill for rolling.
F. Controlling rolling and cooling of steel billets: roughly rolling the steel billet for 6 passes under the rolling condition of the speed of 0.5-1.0 m/s; then, carrying out medium rolling for 4-6 passes under the rolling condition with the speed of 3.0-4.0 m/s; finally, finish rolling for 2-5 passes under the rolling condition with the speed of 9.0-13.5 m/s; performing controlled cooling on the finish-rolled steel through 1 long-pipe water cooling section device with the length of 4.5 meters and 1-3 short-pipe water cooling section devices with the length of 0.8 meter, wherein the number of water pumps in the long-pipe water cooling section is 1, and the pressure of the water pumps is 1.4-1.7 MPa; the number of water pumps in the water cooling section of the short pipe is 1-2, and the pressure of the water pumps is 1.0-1.5 MPa; and naturally cooling the steel bars to room temperature in a cooling bed after cooling control, and obtaining the target object.
The invention has the beneficial effects that:
1. the method for rolling steel adopts lower heating temperature and start rolling temperature, original austenite grains are refined, the refinement of ferrite grains is promoted when austenite is converted into ferrite, the grain size reaches more than 11.0 grade, the fine grain strengthening effect is obvious, and the ductility and toughness of the steel are improved; the ferrocolumbium is added into the steel, the lower initial rolling temperature is controlled, and the multi-section low-water-pressure grading controlled cooling process after rolling is adopted, so that the driving force for Nb (C, N) precipitation is increased, and a large amount of fine and dispersed second phases are precipitated on a low-temperature ferrite matrix, a crystal boundary and a dislocation line, so that the ferrite matrix is strengthened, the strength of the steel is obviously improved, and the performances of the steel, such as welding, aging and the like, are improved; granular bainite with the content of 2-5% is formed in the center of the cross section of the steel bar, the dislocation density is high, the tensile strength of the steel can be obviously improved, and the anti-seismic performance is improved. The invention fully exerts various strengthening functions of fine grain strengthening, precipitation strengthening, multiphase structure composite strengthening and the like by integrating and innovating chemical component design, converter smelting, deoxidation alloying, continuous casting, steel rolling heating system, rolling temperature and controlled cooling process, and the produced steel bar has the advantages of excellent and stable process mechanical property, fine and uniform microstructure, good plasticity and toughness, low strain timeliness, excellent earthquake resistance and the like.
2. The method has the characteristics of low production cost, strong process applicability and controllability and the like, various indexes of the produced steel bar are comprehensively superior to GB/T1499.2-2018, and the production cost is the same as that of the existing vanadium microalloy chemical industryThe reduction of the art is 50 yuan/tSteelBy the method, the production cost of the HRB400E steel bar is greatly reduced after GB/T1499.2-2018 is implemented, the market competitiveness of the product is improved, and the method has remarkable economic and social benefits.
Detailed Description
The present invention is further illustrated by the following examples, which are not intended to be limiting in any way, and any modifications or alterations based on the teachings of the present invention are intended to fall within the scope of the present invention.
The invention relates to a low-niobium microalloyed HRB400E ultrafine-grain high-toughness anti-seismic steel bar, which comprises the following chemical components in parts by weight: 0.20 to 0.24wt% of C, 0.38 to 0.48wt% of Si, 1.30 to 1.50wt% of Mn, 0.014 to 0.019wt% of Nb0.040 wt% or less of S, 0.045wt% or less of P, 0.0070wt% or less of O, 0.0075wt% or less of N, and the balance of Fe and inevitable impurities.
The invention discloses a preparation method of a low-niobium microalloyed HRB400E ultrafine-grain high-toughness anti-seismic steel bar, which comprises the following steps:
A. smelting molten steel: respectively processing the scrap steel, the pig iron and the molten iron according to the temperature of 120-Steel、20kg/tSteel915 plus 940kg/t is added into an LD converter, then conventional top-bottom composite blowing is carried out, conventional lime, light-burned dolomite and magnesite balls are added for slagging, the addition amount of the lime is 20-25kg/t steel, the addition amount of the light-burned dolomite is 15-20kg/t steel, and the addition amount of the magnesite balls is 0.5kg/tSteelControlling the end point carbon content to be more than or equal to 0.08wt% and the tapping temperature to be less than or equal to 1650 ℃; 1.0kg/t of steel ladle bottom before tappingSteelAdding the following slag washing desulfurizer in mass ratio for slag washing: al (Al)2O321.5wt％，SiO25.2wt%, 46.5wt% of CaO, 9.2wt% of Al, 6.5wt% of MgO6, and the balance of Fe and inevitable impurities, wherein a whole bottom argon blowing process is adopted in the tapping process, and the argon flow is controlled to be 10-15 NL/min; the chemical components of the scrap steel comprise 0.12-0.20wt% of C, 0.35-0.60wt% of Si, 0.45-0.70wt% of Mn0.035-0.046 wt% of P, 0.028-0.039wt% of S, and the balance of Fe and inevitable impurities; 3.3 to 3.6 weight percent of pig iron chemical component C, 0.30 to 0.50 weight percent of Si, 0.32 to 0.55 weight percent of Mn, 0.058 to 0.075 weight percent of P, 0.018 to 0.027 weight percent of S and the balance ofFe and inevitable impurities; the chemical components of the molten iron are C4.0-4.5 wt%, Si 0.15-0.35wt%, Mn 0.30-0.50wt%, P0.080-0.120 wt% and S less than or equal to 0.035wt%, and the temperature of the molten iron is more than or equal to 1280 ℃;
B. and (3) deoxidation alloying: tapping the molten steel, and when the amount of the molten steel in the ladle is more than 1/4, carrying out the following deoxidation alloying sequence: silico-aluminum-calcium deoxidizer → silicon carbide → ferrosilicon → silicomanganese → high carbon ferromanganese → high silicon ferroniobium, the following substances are added into the steel ladle in sequence: at a rate of 1.0kg/tSteelAdding the following silicon-aluminum-calcium deoxidizer in mass ratio: 32.5wt% of Si, 16.8wt% of Ca, 10.6wt% of Al and the balance of Fe and inevitable impurities; at a rate of 1.8kg/tSteelAdding the following silicon carbide in mass ratio: 82.5wt% of SiC, 26.5wt% of C, 0.053wt% of P, 0.035wt% of S and the balance of inevitable impurities; according to 3.4-4.7 kg/tSteelAdding the following ferrosilicon in percentage by mass: 73.5wt% of Si, and the balance of Fe and inevitable impurities; at 9.1kg/tSteelAdding the following silicon-manganese alloy in mass ratio: 65.2wt% of Mn, 17.3wt% of Si, 1.8wt% of C, and the balance of Fe and inevitable impurities; according to the ratio of 10.2-12.2 kg/tSteelAdding the following high-carbon ferromanganese in mass ratio: mn75.3wt%, C7.1 wt%, and the balance Fe and inevitable impurities; according to 0.24-0.32kg/tSteelAdding the following ferroniobium in percentage by mass: 65.6wt% of Nb, 6.7wt% of Si, 0.35wt% of C, 0.214wt% of P, 0.075wt% of S, and the balance of Fe and inevitable impurities; when the amount of the molten steel in the steel ladle reaches 3/4, the alloy is added; after tapping, hoisting the molten steel to an argon station for refining treatment;
C. refining in a molten steel argon station: hoisting the molten steel to an argon station, connecting an argon band, starting argon, blowing the molten steel with argon at the flow rate of 15-25 NL/min for 4 minutes, and adding a molten steel covering agent, wherein the addition amount is controlled to be 1.0kg/tSteelThen, hoisting the molten steel to a casting station;
D. casting molten steel: the temperature of the tundish is 1523-1535 ℃, the pulling speed is 2.5-2.7 m/min, and the flow of the cooling water of the crystallizer is 110-120 m3The water content of the secondary cooling is 1.5-1.7L/kgThen, casting the molten steel into a billet with the cross section of 150mm multiplied by 150mm by adopting an R9m straight-arc continuous straightening 5-machine 5-flow small square billet casting machine;
E. heating a steel billet: and (3) feeding the steel billet into a heating furnace with the furnace temperature of 1060-1100 ℃ in a soaking section, heating for 70-80 minutes, tapping, and then pushing to a full-continuous bar mill for rolling.
F. Controlling rolling and cooling of steel billets: roughly rolling the steel billet for 6 passes under the rolling condition of the speed of 0.5-1.0 m/s; then, carrying out medium rolling for 4-6 passes under the rolling condition with the speed of 3.0-4.0 m/s; finally, finish rolling for 2-5 passes under the rolling condition with the speed of 9.0-13.5 m/s; performing controlled cooling on the finish-rolled steel through 1 long-pipe water cooling section device with the length of 4.5 meters and 1-3 short-pipe water cooling section devices with the length of 0.8 meter, wherein the number of water pumps in the long-pipe water cooling section is 1, and the pressure of the water pumps is 1.4-1.7 MPa; the number of water pumps in the water cooling section of the short pipe is 1-2, and the pressure of the water pumps is 1.0-1.5 MPa; and naturally cooling the steel bars to room temperature in a cooling bed after cooling control, and obtaining the target object.
And D, controlling the straightening temperature of the casting blank discharged from the withdrawal and straightening machine to be 1020-1030 ℃.
The secondary cooling specific water amount in the step D is as follows: the ratio of the total water consumption in unit time of the secondary cooling area of the continuous casting machine to the mass of the casting blank passing through the secondary cooling area in unit time is an index of the secondary cooling water spray intensity of continuous casting by taking L/kg as a unit.
And in the step E, the steel tapping temperature of the steel billet is 1010-1030 ℃.
And in the step F, controlling the temperature of the steel bar on the cooling bed to be 850-880 ℃.
The mechanical properties, the microstructure and the Vickers hardness difference of the 12-28mm low-niobium microalloyed HRB400E ultrafine-grained high-toughness anti-seismic steel bar are shown in tables 1 and 2.
TABLE 1 mechanical properties of 12-28mm HRB400E superfine crystal high-toughness aseismic steel bar
TABLE 2 metallographic structure and Vickers hardness of 12-28mm HRB400E superfine crystal high-strength and toughness aseismic steel bar of the present invention
Example 1
A preparation method of a low-niobium microalloyed HRB400E ultrafine-grain high-toughness anti-seismic steel bar specifically comprises the following steps:
A. smelting molten steel: at 120kg/t respectivelySteel、20kg/tSteelThe cold charge charging ratio of (1) adding scrap steel (chemical components: C0.12 wt%, Si 0.35wt%, Mn0.45 wt%, P0.035wt%, S0.028 wt%, and the balance Fe and unavoidable impurities) and pig iron (chemical components: C3.3wt%, Si 0.30 wt%, Mn 0.32 wt%, P0.058 wt%, S0.018 wt%, and the balance Fe and unavoidable impurities) in the mass ratio in an LD converter; then 940kg/tSteelThe molten iron charging proportion is that molten iron with the following temperature and mass ratio is added into an LD converter: the temperature of molten iron is 1280 ℃, the components of the molten iron comprise 4.0 wt% of C, 0.15 wt% of Si, 0.30wt% of Mn0.080 wt% of P and 0.020wt% of S, and the balance of Fe and inevitable impurities; after adding scrap steel, pig iron and molten iron into an LD converter, carrying out conventional top-bottom combined blowing, adding conventional lime, light-burned dolomite and magnesite balls for slagging, wherein the adding amount of the lime is 20kg/tSteelThe addition amount of light-burned dolomite is 15kg/tSteelThe adding amount of the magnesite balls is 0.5kg/tSteelControlling the final carbon content to be 0.08wt% and the tapping temperature to be 1635 ℃; 1.0kg/t of steel ladle bottom before tappingSteelAdding the following slag washing desulfurizer in mass ratio for slag washing: Al2O321.5wt%, SiO25.2wt%, CaO 46.5wt%, Al 9.2wt%, MgO6.5wt%, and the balance Fe and inevitable impurities, wherein the whole bottom argon blowing process is adopted in the tapping process, and the argon flow is controlled to be 10 NL/min.
B. And (3) deoxidation alloying: tapping the molten steel smelted in the step A, and when the amount of the molten steel in the ladle is more than 1/4, carrying out the following deoxidation alloying sequence: silico-aluminum-calcium deoxidizer → silicon carbide → ferrosilicon → silicomanganese → high carbon ferromanganese → high silicon ferroniobium, the following substances are added into the steel ladle in sequence: at a rate of 1.0kg/tSteelAdding the following silicon-aluminum-calcium deoxidizer in mass ratio: 32.5wt% of Si, 16.8wt% of Ca, 10.6wt% of Al and the balance of Fe and inevitable impurities; at a rate of 1.8kg/tSteelAdding the following silicon carbide in mass ratio: 82.5wt% of SiC, 26.5wt% of C, 0.053wt% of P, 0.035wt% of S and the balance of inevitable impurities; at 3.4kg/tSteelAdding the following ferrosilicon in percentage by mass: 73.5wt% of Si, and the balance of Fe and inevitable impurities; at 9.1kg/tSteelAdding the following silicon-manganese alloy in mass ratio: 65.2wt% of Mn, 17.3wt% of Si, 1.8wt% of C, and the balance of Fe and inevitable impurities; at a rate of 10.2kg/tSteelAdding the following high-carbon ferromanganese in mass ratio: 75.3wt% of Mn, 7.1wt% of C, and the balance of Fe and inevitable impurities; according to the ratio of 0.24-0.32kg/tSteelAdding the following ferroniobium in percentage by mass: 65.6wt% of Nb, 6.7wt% of Si, 0.35wt% of C, 0.214wt% of P, 0.075wt% of S and the balance of Fe and inevitable impurities; when the amount of the molten steel in the steel ladle reaches 3/4, the alloy is added; and after tapping, hoisting the molten steel to an argon station for refining treatment.
C. Refining in a molten steel argon station: hoisting the molten steel to an argon station, connecting an argon band, starting argon, blowing argon at the flow rate of 15NL/min for 4 minutes, adding a molten steel covering agent, and controlling the adding amount to be 1.0kg/tSteelAnd then hoisting the molten steel to a casting station.
D. Casting molten steel: c, under the conditions that the temperature of a tundish is 1535 ℃, the pulling speed is 2.5m/min, the flow of cooling water of a crystallizer is 120m3/h, and the secondary cooling specific water is 1.5L/kg, adopting an R9m straight arc-shaped continuous straightening 5-machine 5-flow small square billet casting machine to cast the molten steel in the step C into a billet with the section of 150mm multiplied by 150 mm; the straightening temperature of the casting blank discharged from the tension leveler is controlled to be 1030 ℃.
E. Heating a steel billet: and D, feeding the steel billet obtained in the step D into a heating furnace with the furnace temperature of a soaking section of 1060 ℃, heating for 70 minutes, wherein the steel tapping temperature of the steel billet is 1030 ℃, and then pushing the steel billet to a full-continuous bar mill for rolling.
F. Controlling rolling and cooling of steel billets: roughly rolling the billet steel obtained in the step E for 6 passes under the rolling condition of the speed of 1.0 m/s; then, carrying out medium rolling for 6 passes under the rolling condition with the speed of 4.0 m/s; finally, finish rolling is carried out for 5 passes under the rolling condition with the speed of 13.5 m/s; performing controlled cooling on the rolled steel through 1 long-pipe water cooling section device (with the length of 4.5 meters) and 1 short-pipe water cooling section device (with the length of 0.8 meter), wherein the number of long-pipe water cooling section water pumps is 1, and the pressure of the water pumps is 1.4 MPa; 1 water pump is started at the water cooling section of the short pipe, and the pressure of the water pump is 1.0 MPa; controlling the temperature of the steel bars on a cooling bed to 850 ℃ after controlled cooling, and then naturally cooling the steel bars in the cooling bed to room temperature to obtain the HRB400E ultrafine-grain high-toughness anti-seismic steel bars with the following chemical components in percentage by weight: 0.20wt% of C, 0.38wt% of Si, 1.30 wt% of Mn, 0.014 wt% of Nb, 0.025wt% of S, 0.030wt% of P0.0070 wt% of N, 0.0075wt% of O, and the balance of Fe and inevitable impurities.
The mechanical properties, the microstructure and the Vickers hardness difference of the 12mm low-niobium microalloyed HRB400E ultrafine-grained high-toughness anti-seismic steel bar provided by the embodiment 1 are shown in tables 3 and 4.
HRB400E ultra-fine grain high-strength and toughness aseismic reinforcing steel bar with surface of 312 mm and process mechanical property
TABLE 412 mm HRB400E super fine grain high strength and toughness aseismic reinforcing steel bar metallographic microstructure and Vickers hardness
Example 2
A preparation method of a low-niobium microalloyed HRB400E ultrafine-grain high-toughness anti-seismic steel bar specifically comprises the following steps:
A. smelting molten steel: at 130kg/t respectivelySteel、20kg/tSteelThe cold charge charging ratio of (1) is that scrap steel (chemical components: C0.17 wt%, Si0.48 wt%, Mn 0.58 wt%, P0.040wt%, S0.034 wt%, and the balance Fe and inevitable impurities) and pig iron (chemical components: C3.4 wt%, Si 0.40 wt%, Mn 0.39 wt%, P0.065 wt%) are added into an LD converter in the following mass ratiowt%, S0.023 wt%, the balance being Fe and inevitable impurities); then according to 928kg/tSteelThe molten iron charging proportion is that molten iron with the following temperature and mass ratio is added into an LD converter: the temperature of the molten iron is 1295 ℃, the components of the molten iron are 4.3wt percent of C, 0.25wt percent of Si, 0.40wt percent of Mn, 0.100wt percent of P, 0.030wt percent of S, and the balance of Fe and inevitable impurities; after waste steel, pig iron and molten iron are added into an LD converter, conventional top-bottom combined blowing is carried out, conventional lime, light-burned dolomite and magnesite balls are added for slagging, and the addition amount of the lime is 23kg/tSteelThe addition amount of the light-burned dolomite is 18kg/tSteelThe adding amount of the magnesite balls is 0.5kg/tSteelControlling the end point carbon content to be 0.09 wt% and the tapping temperature to be 1640 ℃; 1.0kg/t of steel ladle bottom before tappingSteelAdding the following slag washing desulfurizer in mass ratio for slag washing: Al2O321.5wt%, SiO25.2wt%, CaO 46.5wt%, Al 9.2wt%, MgO6.5wt%, and the balance of Fe and inevitable impurities, wherein the whole bottom argon blowing process is adopted in the tapping process, and the argon flow is controlled to be 15 NL/min.
B. And (3) deoxidation alloying: tapping the molten steel smelted in the step A, and when the amount of the molten steel in the ladle is more than 1/4, carrying out the following deoxidation alloying sequence: silico-aluminum-calcium deoxidizer → silicon carbide → ferrosilicon → silicomanganese → high carbon ferromanganese → high silicon ferroniobium, the following substances are added into the steel ladle in sequence: at a rate of 1.0kg/tSteelAdding the following silicon-aluminum-calcium deoxidizer in mass ratio: 32.5wt% of Si, 16.8wt% of Ca, 10.6wt% of Al and the balance of Fe and inevitable impurities; according to the amount of 1.8kg/t steel, the following silicon carbide is added in mass ratio: 82.5wt% of SiC, 26.5wt% of C, 0.053wt% of P, 0.035wt% of S and the balance of inevitable impurities; at 3.4kg/tSteelAdding the following ferrosilicon in percentage by mass: 73.5wt% of Si, and the balance of Fe and inevitable impurities; at 9.1kg/tSteelAdding the following silicon-manganese alloy in mass ratio: 65.2wt% of Mn, 17.3wt% of Si, 1.8wt% of C, and the balance of Fe and inevitable impurities; at a rate of 10.2kg/tSteelAdding the following high-carbon ferromanganese in mass ratio: 75.3wt% of Mn, 7.1wt% of C, and the balance of Fe and inevitable impurities; at a rate of 0.24kg/tSteelIn the following mass ratio of niobiumIron: 65.6wt% of Nb, 6.7wt% of Si, 0.35wt% of C, 0.214wt% of P, 0.075wt% of S and the balance of Fe and inevitable impurities; when the amount of the molten steel in the steel ladle reaches 3/4, the alloy is added; and after tapping, hoisting the molten steel to an argon station for refining treatment.
C. Refining in a molten steel argon station: hoisting the molten steel to an argon station, connecting an argon band, starting argon, blowing the molten steel with argon at the flow rate of 20L/min for 4 minutes, and then adding a molten steel covering agent, wherein the adding amount is controlled to be 1.0kg/tSteelAnd then hoisting the molten steel to a casting station.
D. Casting molten steel: under the conditions that the temperature of a tundish is 1530 ℃, the pulling speed is 2.6m/min, the flow of cooling water of a crystallizer is 115m3/h, and the secondary cooling specific water amount is 1.6L/kg, the molten steel in the step C is cast into a billet with the section of 150mm multiplied by 150mm by a small billet casting machine with a R9m straight arc-shaped continuous straightening 5 machine 5 flow; the straightening temperature of the casting blank discharged from the withdrawal and straightening machine is controlled to be 1025 ℃.
E. Heating a steel billet: and D, feeding the steel billets obtained in the step D into a heating furnace with the furnace temperature of the soaking section of 1080 ℃, heating for 75 minutes, wherein the steel tapping temperature of the steel billets is 1020 ℃, and then pushing the steel billets to a full-continuous bar mill for rolling.
F. Controlling rolling and cooling of steel billets: roughly rolling the billet steel obtained in the step E for 6 passes under the rolling condition of the speed of 1.0 m/s; then, carrying out medium rolling for 5 passes under the rolling condition with the speed of 4.0 m/s; finally, finish rolling is carried out for 4 passes under the rolling condition with the speed of 11.5 m/s; performing controlled cooling on the rolled steel through 1 long-pipe water cooling section device (with the length of 4.5 meters) and 2 short-pipe water cooling section devices (with the length of 0.8 meter), wherein the number of long-pipe water cooling section water pumps is 1, and the pressure of the water pumps is 1.6 MPa; 2 water pumps of the water cooling section of the short pipe are started, and the pressure of the water pumps is 1.2 MPa; controlling the temperature of the steel bars on a cooling bed to 870 ℃ after controlled cooling, and then naturally cooling the steel bars in the cooling bed to room temperature to obtain the HRB400E ultrafine-grain high-toughness anti-seismic steel bars with the following chemical components in percentage by weight: 0.22 wt% of C, 0.44wt% of Si, 1.40 wt% of Mn, 0.017 wt% of Nb, 0.035wt% of S, 0.038 wt% of P, 0.0050 wt% of O, 0.0070wt% of N, and the balance of Fe and inevitable impurities.
The mechanical properties, the microstructure and the difference in Vickers hardness of the low-niobium microalloyed HRB400E ultrafine-grained high-toughness anti-seismic steel bar provided by the embodiment 2 are shown in tables 5 and 6.
Table 520 mm low-niobium microalloyed HRB400E ultra-fine grain high-toughness anti-seismic reinforcing steel bar process mechanical property
Table 620 mm low-niobium microalloyed HRB400E ultra-fine grain high-toughness anti-seismic reinforcing steel bar metallographic microstructure and Vickers hardness
Example 3
A preparation method of a low-niobium microalloyed HRB400E ultrafine-grain high-toughness anti-seismic steel bar specifically comprises the following steps:
A. smelting molten steel: according to 135kg/t respectivelySteel、20kg/tSteelThe cold charge charging ratio of (1) adding scrap steel (chemical components: C0.20 wt%, Si 0.60wt%, Mn 0.70wt%, P0.046 wt%, S0.039 wt%, and the balance Fe and unavoidable impurities) and pig iron (chemical components: C3.6 wt%, Si 0.50wt%, Mn 0.55wt%, P0.075 wt%, S0.027 wt%, and the balance Fe and unavoidable impurities) in the following mass ratio into an LD converter; then according to 915kg/tSteelThe molten iron charging proportion is that molten iron with the following temperature and mass ratio is added into an LD converter: the temperature of molten iron is 1310 ℃, the components of the molten iron are C4.5 wt%, Si 0.35wt%, Mn0.50wt%, P0.120 wt% and S0.035wt%, and the balance is Fe and inevitable impurities; after waste steel, pig iron and molten iron are added into an LD converter, conventional top-bottom combined blowing is carried out, conventional lime, light-burned dolomite and magnesite balls are added for slagging, and the addition amount of the lime is 25kg/tSteelThe addition amount of light-burned dolomite is 20kg/tSteelThe adding amount of the magnesite balls is 0.5kg/tSteelControlling the end point carbon content to be 0.10 wt% and the tapping temperature to be 1650 ℃; 1.0kg/t of steel ladle bottom before tappingSteelAdding the following slag washing desulfurizer in mass ratio for slag washing: Al2O321.5wt%, SiO25.2wt%, CaO 46.5wt%, Al 9.2wt%, MgO6.5wt%, and the balance Fe and inevitable impurities, wherein a whole bottom argon blowing process is adopted in the tapping process, and the argon flow is controlled to be 15 NL/min.
B. And (3) deoxidation alloying: tapping the molten steel smelted in the step A, and when the amount of the molten steel in the ladle is more than 1/4, carrying out the following deoxidation alloying sequence: silico-aluminum-calcium deoxidizer → silicon carbide → ferrosilicon → silicomanganese → high carbon ferromanganese → high silicon ferroniobium, the following substances are added into the steel ladle in sequence: at a rate of 1.0kg/tSteelAdding the following silicon-aluminum-calcium deoxidizer in mass ratio: 32.5wt% of Si, 16.8wt% of Ca, 10.6wt% of Al and the balance of Fe and inevitable impurities; at a rate of 1.8kg/tSteelAdding the following silicon carbide in mass ratio: 82.5wt% of SiC, 26.5wt% of C, 0.053wt% of P, 0.035wt% of S and the balance of inevitable impurities; at 4.7kg/tSteelAdding the following ferrosilicon in percentage by mass: 73.5wt% of Si, and the balance of Fe and inevitable impurities; at 9.1kg/tSteelAdding the following silicon-manganese alloy in mass ratio: 65.2wt% of Mn, 17.3wt% of Si, 1.8wt% of C, and the balance of Fe and inevitable impurities; at 12.2kg/tSteelAdding the following high-carbon ferromanganese in mass ratio: 75.3wt% of Mn, 7.1wt% of C, and the balance of Fe and inevitable impurities; at a rate of 0.32kg/tSteelAdding the following ferroniobium in percentage by mass: 65.6wt% of Nb, 6.7wt% of Si, 0.35wt% of C, 0.214wt% of P, 0.075wt% of S and the balance of Fe and inevitable impurities; when the amount of the molten steel in the steel ladle reaches 3/4, the alloy is added; and after tapping, hoisting the molten steel to an argon station for refining treatment.
C. Refining in a molten steel argon station: hoisting the molten steel to an argon station, connecting an argon band, starting argon, blowing the molten steel with the argon with the flow of 25NL/min for 4 minutes, and then adding a molten steel covering agent, wherein the adding amount is controlled to be 1.0kg/tSteelAnd then hoisting the molten steel to a casting station.
D. Casting molten steel: under the conditions that the temperature of a tundish is 1523 ℃, the pulling speed is 2.7m/min, the flow of cooling water of a crystallizer is 110m3/h, and the secondary cooling specific water is 1.7L/kg, adopting an R9m straight arc-shaped continuous straightening 5-machine 5-flow small square billet casting machine to cast the molten steel in the step C into a billet with the section of 150mm multiplied by 150 mm; the straightening temperature of the casting blank discharged from the withdrawal and straightening machine is controlled to be 1020 ℃.
E. Heating a steel billet: and D, feeding the steel billet obtained in the step D into a heating furnace with the furnace temperature of the soaking section of 1100 ℃, heating for 80 minutes, wherein the steel tapping temperature of the steel billet is 1010 ℃, and then pushing the steel billet to a full-continuous bar mill for rolling.
F. Controlling rolling and cooling of steel billets: roughly rolling the billet steel obtained in the step E for 6 passes under the rolling condition of the speed of 0.5 m/s; then, rolling for 4 passes under the rolling condition with the speed of 3.0 m/s; finally, finish rolling is carried out for 2 passes under the rolling condition with the speed of 9.0 m/s; performing controlled cooling on the rolled steel through 1 long-pipe water cooling section device (with the length of 4.5 meters) and 3 short-pipe water cooling section devices (with the length of 0.8 meter), wherein the number of long-pipe water cooling section water pumps is 1, and the pressure of the water pumps is 1.7 MPa; 2 water pumps of the water cooling section of the short pipe are started, and the pressure of the water pumps is 1.5 MPa; controlling the temperature of the steel bar on a cooling bed to 880 ℃ after controlled cooling, and then naturally cooling the steel bar in the cooling bed to room temperature to obtain the HRB400E ultrafine-grain high-toughness anti-seismic steel bar with the following chemical components in percentage by weight: 0.24wt% of C, 0.48wt% of Si, 1.50wt% of Mn, 0.019wt% of Nb, 0.040wt% of S, 0.045wt% of P, 0.0050 wt% of O, and N0.0060wt% of Nb, and the balance of Fe and inevitable impurities.
The mechanical properties, the microstructure and the Vickers hardness difference of the 28mm low-niobium microalloyed HRB400E ultrafine-grained high-toughness anti-seismic steel bar in the embodiment are shown in tables 7 and 8.
Mechanical properties of ultra-fine grain high-toughness anti-seismic steel bar with low-niobium microalloying HRB400E in table 728 mm
Mechanical properties of ultra-fine grain high-toughness anti-seismic steel bar with low-niobium microalloying HRB400E in table 828 mm
Claims (5)
1. A preparation method of a low-niobium microalloyed HRB400E ultrafine-grained high-toughness anti-seismic steel bar is characterized in that the steel comprises the following chemical components by weight: 0.20-0.24 wt% of C, 0.38-0.48 wt% of Si, 1.30-1.50 wt% of Mn, 0.014-0.019 wt% of Nb, less than or equal to 0.040wt% of S, less than or equal to 0.045wt% of P, less than or equal to 0.0070wt% of O, less than or equal to 0.0075wt% of N, and the balance of Fe and inevitable impurities; the preparation method specifically comprises the following steps:
A. smelting molten steel: respectively processing the scrap steel, the pig iron and the molten iron according to the temperature of 120-Steel、20kg/tSteel915 and 940kg/t are added into an LD converter, then conventional top-bottom composite blowing is carried out, conventional lime, light-burned dolomite and magnesite balls are added for slagging, and the addition amount of the lime is 20-25kg/tSteelThe addition amount of light-burned dolomite is 15-20kg/tSteelThe adding amount of the magnesite balls is 0.5kg/tSteelControlling the end point carbon content to be more than or equal to 0.08wt% and the tapping temperature to be less than or equal to 1650 ℃; 1.0kg/t of steel ladle bottom before tappingSteelAdding the following slag washing desulfurizer in mass ratio for slag washing: al (Al)2O3 21.5wt%，SiO25.2wt%, 46.5wt% of CaO, 9.2wt% of Al, 6.5wt% of MgO6, and the balance of Fe and inevitable impurities, wherein a whole bottom argon blowing process is adopted in the tapping process, and the argon flow is controlled to be 10-15 NL/min; the chemical components of the scrap steel comprise 0.12-0.20wt% of C, 0.35-0.60wt% of Si, 0.45-0.70wt% of Mn, 0.035-0.046wt% of P, 0.028-0.039wt% of S, and the balance of Fe and inevitable impurities; 3.3-3.6wt% of pig iron chemical components C, 0.30-0.50wt% of Si, 0.32-0.55wt% of Mn, 0.058-0.075wt% of P, 0.018-0.027wt% of S, and the balance of Fe and inevitable impurities; the chemical components of the molten iron are C4.0-4.5 wt%, Si 0.15-0.35wt%, Mn 0.30-0.50wt%, P0.080-0.120 wt% and S less than or equal to 0.035wt%, and the temperature of the molten iron is more than or equal to 1280 ℃;
B. and (3) deoxidation alloying: tapping the molten steel, and when the amount of the molten steel in the ladle is more than 1/4, carrying out the following deoxidation alloying sequence: silico-aluminum-calcium deoxidizer → silicon carbide → ferrosilicon → silicomanganese → high-carbon ferromanganese → highSilicon ferrocolumbium, the following substances are sequentially added into a steel ladle: at a rate of 1.0kg/tSteelAdding the following silicon-aluminum-calcium deoxidizer in mass ratio: 32.5wt% of Si, 16.8wt% of Ca, 10.6wt% of Al and the balance of Fe and inevitable impurities; according to the amount of 1.8kg/t steel, the following silicon carbide is added in mass ratio: 82.5wt% of SiC, 26.5wt% of C, 0.053wt% of P, 0.035wt% of S and the balance of inevitable impurities; according to 3.4-4.7 kg/tSteelAdding the following ferrosilicon in percentage by mass: 73.5wt% of Si, and the balance of Fe and inevitable impurities; at 9.1kg/tSteelAdding the following silicon-manganese alloy in mass ratio: 65.2wt% of Mn, 17.3wt% of Si, 1.8wt% of C, and the balance of Fe and inevitable impurities; adding the following high-carbon ferromanganese according to the amount of 10.2-12.2 kg/t steel: 75.3wt% of Mn, 7.1wt% of C, and the balance of Fe and inevitable impurities; according to 0.24-0.32kg/tSteelAdding the following ferroniobium in percentage by mass: 65.6wt% of Nb, 6.7wt% of Si, 0.35wt% of C, 0.214wt% of P, 0.075wt% of S and the balance of Fe and inevitable impurities; when the amount of the molten steel in the steel ladle reaches 3/4, the alloy is added; after tapping, hoisting the molten steel to an argon station for refining treatment;
C. refining in a molten steel argon station: hoisting the molten steel to an argon station, connecting an argon band, starting argon, blowing the molten steel with argon at the flow rate of 15-25 NL/min for 4 minutes, and adding a molten steel covering agent, wherein the addition amount is controlled to be 1.0kg/tSteelThen, hoisting the molten steel to a casting station;
D. casting molten steel: the temperature of the tundish is 1523-1535 ℃, the pulling speed is 2.5-2.7 m/min, and the flow of the cooling water of the crystallizer is 110-120 m3H, adopting an R9m straight-arc continuous straightening 5-machine 5-flow small square billet casting machine to cast the molten steel into a billet with the cross section of 150mm multiplied by 150mm under the condition that the secondary cooling specific water amount is 1.5-1.7L/kg;
E. heating a steel billet: feeding the steel billet into a heating furnace with the furnace temperature of 1060-1100 ℃ at a soaking section, heating for 70-80 minutes, tapping, and then pushing to a full-continuous bar mill for rolling;
F. controlling rolling and cooling of steel billets: roughly rolling the steel billet for 6 passes under the rolling condition of the speed of 0.5-1.0 m/s; then, carrying out medium rolling for 4-6 passes under the rolling condition with the speed of 3.0-4.0 m/s; finally, finish rolling for 2-5 passes under the rolling condition with the speed of 9.0-13.5 m/s; performing controlled cooling on the finish-rolled steel through 1 long-pipe water cooling section device with the length of 4.5 meters and 1-3 short-pipe water cooling section devices with the length of 0.8 meter, wherein the number of water pumps in the long-pipe water cooling section is 1, and the pressure of the water pumps is 1.4-1.7 MPa; the number of water pumps in the water cooling section of the short pipe is 1-2, and the pressure of the water pumps is 1.0-1.5 MPa; and naturally cooling the steel bars to room temperature in a cooling bed after cooling control, and obtaining the target object.
2. The preparation method according to claim 1, wherein the straightening temperature of the cast blank discharged from the withdrawal straightening machine in the step D is controlled to be 1020-1030 ℃.
3. The preparation method according to claim 1, wherein the steel blank tapping temperature in the step E is 1010-1030 ℃.
4. The preparation method according to claim 1, wherein the temperature of the cooling bed on the steel bar in the step F is controlled to be 850-880 ℃.
5. The low-niobium microalloyed HRB400E ultrafine-grained high-toughness anti-seismic steel bar prepared by the preparation method according to any one of claims 1 to 4.
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| CN115739986A (en) * | 2022-10-31 | 2023-03-07 | 武钢集团昆明钢铁股份有限公司 | Preparation method for producing fine-grain high-toughness anti-seismic steel bar with nominal diameter of 16-20mmHRB400E by using high-speed bar |
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