CN117165827A - 400 MPa-level anti-seismic steel bar and preparation method thereof - Google Patents
400 MPa-level anti-seismic steel bar and preparation method thereof Download PDFInfo
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- 239000010959 steel Substances 0.000 title claims abstract description 122
- 238000002360 preparation method Methods 0.000 title claims abstract description 14
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- 229910052786 argon Inorganic materials 0.000 claims abstract description 77
- 238000007664 blowing Methods 0.000 claims abstract description 76
- 238000009749 continuous casting Methods 0.000 claims abstract description 36
- 238000003723 Smelting Methods 0.000 claims abstract description 30
- 238000010079 rubber tapping Methods 0.000 claims abstract description 25
- 238000005096 rolling process Methods 0.000 claims abstract description 24
- 229910001294 Reinforcing steel Inorganic materials 0.000 claims abstract description 17
- 239000012535 impurity Substances 0.000 claims abstract description 17
- 238000000034 method Methods 0.000 claims description 39
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- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 31
- 229910052719 titanium Inorganic materials 0.000 claims description 31
- 229910052782 aluminium Inorganic materials 0.000 claims description 29
- 229910045601 alloy Inorganic materials 0.000 claims description 26
- 239000000956 alloy Substances 0.000 claims description 26
- 229910052760 oxygen Inorganic materials 0.000 claims description 26
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 25
- 238000005266 casting Methods 0.000 claims description 25
- 239000001301 oxygen Substances 0.000 claims description 25
- IXQWNVPHFNLUGD-UHFFFAOYSA-N iron titanium Chemical compound [Ti].[Fe] IXQWNVPHFNLUGD-UHFFFAOYSA-N 0.000 claims description 21
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 19
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 17
- 229910052717 sulfur Inorganic materials 0.000 claims description 16
- 238000005275 alloying Methods 0.000 claims description 15
- 229910000600 Ba alloy Inorganic materials 0.000 claims description 14
- NCJRLCWABWKAGX-UHFFFAOYSA-N [Si].[Ca].[Ba] Chemical compound [Si].[Ca].[Ba] NCJRLCWABWKAGX-UHFFFAOYSA-N 0.000 claims description 14
- 229910052799 carbon Inorganic materials 0.000 claims description 14
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 14
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 14
- 229910052742 iron Inorganic materials 0.000 claims description 13
- 229910052698 phosphorus Inorganic materials 0.000 claims description 12
- 235000007164 Oryza sativa Nutrition 0.000 claims description 10
- 235000009566 rice Nutrition 0.000 claims description 10
- 239000002893 slag Substances 0.000 claims description 10
- 229910000519 Ferrosilicon Inorganic materials 0.000 claims description 9
- 238000001816 cooling Methods 0.000 claims description 9
- 238000010438 heat treatment Methods 0.000 claims description 9
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- 229910000914 Mn alloy Inorganic materials 0.000 claims description 6
- XWHPIFXRKKHEKR-UHFFFAOYSA-N iron silicon Chemical compound [Si].[Fe] XWHPIFXRKKHEKR-UHFFFAOYSA-N 0.000 claims description 6
- PYLLWONICXJARP-UHFFFAOYSA-N manganese silicon Chemical compound [Si].[Mn] PYLLWONICXJARP-UHFFFAOYSA-N 0.000 claims description 6
- 239000000843 powder Substances 0.000 claims description 6
- 239000002994 raw material Substances 0.000 claims description 6
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- 229910052748 manganese Inorganic materials 0.000 claims description 5
- 239000011572 manganese Substances 0.000 claims description 5
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- 240000007594 Oryza sativa Species 0.000 claims 1
- 238000005452 bending Methods 0.000 abstract description 2
- 229910001200 Ferrotitanium Inorganic materials 0.000 description 9
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- XFWJKVMFIVXPKK-UHFFFAOYSA-N calcium;oxido(oxo)alumane Chemical compound [Ca+2].[O-][Al]=O.[O-][Al]=O XFWJKVMFIVXPKK-UHFFFAOYSA-N 0.000 description 1
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Classifications
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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
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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Abstract
The invention provides a 400 MPa-level anti-seismic reinforcing steel bar and a preparation method thereof. The preparation method comprises the following steps: converter smelting, converter tapping, argon blowing, continuous casting and steel rolling. The anti-seismic steel bar comprises the following components in percentage by weight: c:0.22 to 0.26 percent, si:0.44 to 0.51 percent, mn:1.36 to 1.53 percent, ti:0.012 to 0.050 percent, S:0.015 to 0.020 percent, P:0.020 to 0.025 percent, and the balance of Fe and unavoidable impurity elements. The steel bar structure and the performance of the invention can meet the HRB400E requirement, the yield and tensile strength of the steel bar structure and the performance of the steel bar structure respectively reach more than 400MPa and 600MPa, the mechanical property is good, the strength-to-bending ratio is more than 1.25, the requirement of the anti-seismic steel bar is met, and the surface quality is good.
Description
Technical Field
The invention relates to the field of metallurgy, in particular to a 400 MPa-level anti-seismic steel bar and a preparation method thereof.
Background
In recent years, natural disasters such as earthquakes worldwide are frequent, and engineering earthquake resistance is an important means for resisting natural disasters. The hot rolled ribbed steel bars are used in a large amount in the infrastructure, the quality of the hot rolled ribbed steel bars directly influences the use effect of the building, and the aspects of people's safety life are related.
At present, vanadium series and niobium series are commonly adopted in the screw steels in China, however, vanadium and niobium are expensive, and the problem of high cost of HRB400E steel bars is caused. The titanium resource in China is rich, the price is stable, and the titanium is used in the HRB400E steel bar, so that the titanium is one of effective means for reducing the production cost. However, titanium is chemically active and is extremely susceptible to chemical reaction with O, N, S in steel, which results in unstable and low titanium yields during smelting. At present, titanium is added in a refining furnace for alloying, however, the demand of ribbed anti-seismic steel bars is larger, and the smelting cost and period of steel can be greatly improved by adding titanium into the refining furnace for alloying, so that the development of a low-cost Ti micro-alloying 400 MPa-level anti-seismic steel bar production process which does not exceed the refining furnace and can obtain stable titanium yield has great significance for cost reduction and synergy of enterprises.
Disclosure of Invention
An object of the present invention is to solve one or more of the problems occurring in the prior art, in view of the disadvantages of the prior art. For example, one of the purposes of the invention is to provide a preparation method of the 400 MPa-level anti-seismic steel bar, which has low cost, good titanium yield and stability and meets the new national standard requirements of the anti-seismic steel bar.
One aspect of the invention provides a preparation method of a 400 MPa-level anti-seismic steel bar, which comprises the following steps: converter smelting, wherein molten iron and scrap steel are used as raw materials, and the smelting endpoint components are controlled to be C in percentage by mass: 0.05 to 0.12 percent, less than or equal to 0.20 percent of Mn, less than or equal to 0.035 percent of P, less than or equal to 0.03 percent of S, and the tapping temperature is 1600 to 1650 ℃; tapping in a converter, and carrying out deoxidization alloying and carburetion in the tapping process; argon blowing, wherein the oxygen content of molten steel after entering an argon outlet station is controlled to be 35.0-42.5 ppm, titanium-containing materials are added 3-4 min before the argon outlet station, the oxygen content after argon blowing is controlled to be 15.8-18.5 ppm, the temperature of the argon outlet station is controlled to be 1570-1590 ℃, and the molten steel is sent to continuous casting after argon blowing; continuous casting, namely adopting whole-process protection casting; and (3) rolling steel, namely heating the casting blank to 1140-1190 ℃, controlling the initial rolling temperature to 1050-1100 ℃, and feeding the casting blank to a cooling bed at 890-1100 ℃ to obtain the 400 MPa-level anti-seismic steel bar after rolling.
Further, the 400 MPa-level anti-seismic reinforcing steel bar can comprise the following components in percentage by weight: c:0.22 to 0.26 percent, si:0.44 to 0.51 percent, mn:1.36 to 1.53 percent, ti:0.012 to 0.050 percent, S:0.015 to 0.020 percent, P:0.020 to 0.025 percent, and the balance of Fe and unavoidable impurity elements.
Further, deoxidizing alloying and carburising may include deoxidizing alloying and carburising by adding silicon-calcium-barium alloy, silicon-iron alloy, silicon-manganese alloy, silicon carbide, carburant in that order to the molten steel.
Further, the addition amount of the ferrosilicon alloy can be 2 kg/t-2.5 kg/t, the addition amount of the ferrosilicon alloy can be 24 kg/t-25 kg/t, and the addition amount of the carburant can be 1-1.5 kg/t; when the mass fraction content of the smelting end point component C can be 0.05-0.07%, the adding amount of silicon carbide can be 0.5-0.7 kg/t, and the adding amount of the silicon-calcium-barium alloy can be 0.9-1.1 kg/t; when the mass fraction content of the smelting end point component C is more than 0.07%, the adding amount of silicon carbide can be 0.3-0.5 kg/t, and the adding amount of the silicon-calcium-barium alloy can be 0.9-1.1 kg/t.
Further, the argon blowing process can comprise the steps of ensuring that argon with the bottom strong blowing pressure of 0.8-1.0 mpa is not less than 1min after molten steel enters an argon station, ensuring that the medium air quantity with the strong blowing pressure of 0.3-0.4 mpa is adjusted after carbon, alloy and top slag are well melted, fine adjusting components and temperature, then adjusting the pressure to be 0.1-0.2 mpa for weak blowing, adding a low aluminum titanium iron wire, and enabling the weak blowing time to be more than 5 min.
Further, the total argon blowing time may be 13 to 16 minutes.
Further, the titanium-containing material can be low-aluminum titanium iron wire, the adding amount of the low-aluminum titanium iron wire can be 1.5-1.6 m/t, wherein the low-aluminum titanium iron wire core powder can be 390-394 g/m, and the titanium content of the low-aluminum titanium iron wire can be 67-70%. For example, the low-aluminum titanium wire may be added in an amount of 95 to 100m, and the titanium content in the low-aluminum titanium wire may be 68.3%.
Further, adding the low-aluminum titanium iron wire can also comprise adding 1-1.5 kg/t carbonized rice husk and keeping the soft blowing time to be more than or equal to 3min.
Further, continuous casting may be carried outThe pulling speed is set to be 2.10-2.60 m/min, and the water flow of the crystallizer is 150-170 m 3 And/h, controlling the superheat degree of molten steel in the continuous casting process at 25-40 ℃.
Further, the scrap steel in the raw material may be 17 to 20%.
The invention provides a 400 MPa-level anti-seismic steel bar, which is characterized by comprising the following components in percentage by weight: c:0.22 to 0.26 percent, si:0.44 to 0.51 percent, mn:1.36 to 1.53 percent, ti:0.012 to 0.050 percent, S:0.015 to 0.020 percent, P:0.020 to 0.025 percent, and the balance of Fe and unavoidable impurity elements.
Compared with the prior art, the invention has the beneficial effects that at least one of the following components is contained:
(1) The steel bar structure and the performance of the invention can meet the HRB400E requirement, the yield and tensile strength of the steel bar structure and the performance of the steel bar structure respectively reach more than 400MPa and 600MPa, the mechanical property is good, the strength-to-bending ratio is more than 1.25, the requirement of the anti-seismic steel bar is met, and the surface quality is good.
(2) The component design of the invention adopts low-cost element Ti to replace Nb and V, reduces the alloy cost, saves precious alloy resources and is beneficial to sustainable development.
(3) The preparation method does not enter a refining furnace, and titanium wires are added for alloying in an argon blowing station, so that the smelting period and duration are greatly reduced, the preparation method has the advantage of simple process, and the market competitiveness of mass production of anti-seismic reinforcing steel bars is improved.
Drawings
The foregoing and other objects and features of the invention will become more apparent from the following description taken in conjunction with the accompanying drawings in which:
fig. 1 is a microstructure of the reinforcing bar prepared in example 1;
fig. 2 is an SEM image of the reinforcing steel bar prepared in example 1;
fig. 3 is a microstructure of the reinforcing bar prepared in example 2;
fig. 4 is an SEM image of the reinforcing steel bar prepared in example 2;
fig. 5 is a microstructure of the reinforcing bar prepared in example 3;
fig. 6 is an SEM image of the reinforcing steel bar prepared in example 3;
fig. 7 is a graph showing a tensile test of the reinforcing steel bar prepared in example 2.
Detailed Description
Hereinafter, a 400 MPa-level vibration-resistant reinforcing bar and a method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings and exemplary embodiments.
In one aspect of the present invention, a method for preparing a 400 MPa-level anti-seismic rebar is provided, which may include the following steps:
s01, converter smelting, wherein molten iron and scrap steel are used as raw materials, and the smelting endpoint ingredients are controlled to be C in percentage by mass: 0.05 to 0.12 percent, mn is less than or equal to 0.20 percent, P is less than or equal to 0.035 percent, S is less than or equal to 0.03 percent, and tapping temperature is 1600 to 1650 ℃.
S02, tapping through the converter, and carrying out deoxidization alloying and carburetion in the tapping process.
S03, argon blowing, wherein the oxygen content of molten steel after entering an argon station is controlled to be 35.0-42.5 ppm, titanium-containing materials are added 3-4 min before the argon outlet station, the oxygen content after argon blowing is controlled to be 15.8-18.5 ppm, and the temperature of the argon outlet station is controlled to be 1570-1590 ℃, and the molten steel is sent to continuous casting after argon blowing.
S04, continuous casting and casting by adopting whole-process protection.
S05, rolling steel, namely heating a casting blank to 1140-1190 ℃, controlling the initial rolling temperature to 1050-1100 ℃, and feeding the casting blank to a cooling bed at 890-1100 ℃, thereby obtaining the 400 MPa-level anti-seismic steel bar after rolling.
In some embodiments, the temperature of the raw molten iron in the furnace can be controlled between 1340 ℃ and 1406 ℃, and the ingredients of the molten iron comprise C in mass percent: 5.0 to 5.15 percent of Si:0.23 to 0.30 percent of Mn:0.26 to 0.32%, P.ltoreq.0.14%, e.g. C:5.10 to 5.12 percent of Si:0.25 to 0.28 percent of Mn:0.27 to 0.30 percent and P is less than or equal to 0.12 percent. In some embodiments, the scrap mass ratio in the feedstock may be 17-20%. For example, the mass ratio of the scrap steel may be 17.6% or 18.5% or 19.4% using the molten iron as a raw material. Of course, the types and the proportion of the molten iron and the scrap steel used in the invention can be adjusted according to the smelting end point component requirements, and the smelting end point component is satisfied as C in percentage by mass: 0.05 to 0.12 percent, less than or equal to 0.20 percent of Mn, less than or equal to 0.035 percent of P and less than or equal to 0.03 percent of S.
In some embodiments, limestone and light burned dolomite may be added for slagging after molten iron and scrap steel are smelted into molten steel during converter smelting.
In some embodiments, the converter smelting endpoint ingredients may be C:0.07 to 0.10 percent, mn is less than or equal to 0.15 percent, P is less than or equal to 0.030 percent, S is less than or equal to 0.025 percent, and the tapping temperature can be 1620 to 1645 ℃; or the smelting end point component of the converter can be C: 0.08-0.09%, mn less than or equal to 0.12%, P less than or equal to 0.028%, S less than or equal to 0.020%, and the tapping temperature can be 1625-1635 ℃ or the combination of the above ranges.
In the above step S01, the control of the terminal carbon of the transfer furnace may be a hit, that is, oxygen is used for blowing when the carbon content is higher than the control value, and a carburant may be used for carburating when the carbon content is lower than the control value. The converter adopts a sublance to sample and measure C, S, P in molten steel, and the two times of measurement are respectively a process sample TSC and an end point sample TSO, and whether components meet the process requirements of the converter or not is generally determined according to the TSC, and whether measures are adopted to adjust elements or not is generally determined.
According to the reaction balance principle, along with the reduction of the carbon content in steel, the oxygen content in molten steel tends to increase, the dosage of adding a deoxidizing modifier in the tapping process of a converter increases, and the alloy yield is reduced due to the oxidation of the alloy, so that the alloy consumption is increased; the oxygen content of the molten steel of the converter is high, so that the corrosion of the lining of the converter is serious, and the consumption of refractory materials of the converter is high; the inclusion in the steel is increased due to high oxygen content of the molten steel, so that the blocking of a casting nozzle can be caused to influence continuous casting performance, meanwhile, the purity of the molten steel is reduced, and the internal quality of the steel is adversely affected, so that the smelting endpoint component is controlled to be C:0.05 to 0.12 percent, mn is less than or equal to 0.20 percent, P is less than or equal to 0.035 percent, S is less than or equal to 0.03 percent, and tapping temperature is 1600 to 1650 ℃.
In some embodiments, the deoxidizing alloying and carburising process during tapping comprises sequentially adding a silicon-calcium-barium alloy, a silicon-iron alloy, a silicon-manganese alloy, silicon carbide, a carburant to the ladle for deoxidizing alloying and carburising. By sequentially adding the deoxidized alloy and the carburant in the sequence, the oxygen content of molten steel is controlled to be 35.0-42.5 ppm before entering an argon station through weak deoxidization. In certain embodiments, the ferrosilicon alloy is added in an amount of 2kg/t to 2.5kg/t, the ferrosilicon alloy is added in an amount of 24kg/t to 25kg/t, and the carburant is added in an amount of 1kg/t to 1.5kg/t; when the mass fraction content of the smelting end point component C is 0.05-0.07%, the adding amount of silicon carbide can be 0.5-0.7 kg/t, and the adding amount of the silicon-calcium-barium alloy can be 0.9-1.1 kg/t; when the mass fraction content of the smelting end point component C is more than 0.07%, the adding amount of silicon carbide can be 0.3-0.5 kg/t, and the adding amount of the silicon-calcium-barium alloy can be 0.9-1.1 kg/t. The alloy deoxidizer is added to greatly regulate and control the oxygen content (35.0-42.5 ppm) of molten steel, so that the problem that the yield of Ti element in the hot rolled steel bar is unstable, the continuous casting performance is influenced by the blocking of a casting nozzle, and the product performance can be ensured. For example, the addition amount of the ferrosilicon alloy is 2.1-2.4 kg/t, the addition amount of the ferrosilicon alloy is 24.2-24.8 kg/t, the addition amount of the carburant is 1.2-1.4 kg/t, when the mass fraction content of the smelting end point component C is 0.05-0.07%, the addition amount of the silicon carbide is 0.6kg/t, and the addition amount of the calcium silicon-barium alloy is 1kg/t; when the mass fraction content of the smelting end point component C is more than 0.07%, the adding amount of silicon carbide is 0.4kg/t, and the adding amount of the silicon-calcium-barium alloy is 1.05kg/t. The unit kg/t refers to the amount of molten steel tapped from the converter per ton.
In some embodiments, a calcium aluminate detergent and lime may be added to the ladle sequentially after the ferrosilicon is added during tapping.
In some embodiments, the oxygen content of the molten steel after entering the argon station can be controlled to be 35.0-42.5 ppm, a low aluminum titanium iron wire can be added 3-4 min before exiting the argon station, the oxygen content after argon blowing can be controlled to be 15.8-18.5 ppm, and the temperature of the argon exiting station can be 1570-1590 ℃. The low-aluminum ferrotitanium wire can be added 3-4 min before the argon outlet station, so that the oxidation loss of Ti can be effectively reduced, and the yield of Ti in the steelmaking stage can be obviously improved. For example, the oxygen content of molten steel after entering an argon station can be controlled to be 36.5-41.0 ppm, a low-aluminum titanium iron wire is added 3.5-3.8 min before exiting the argon station, the oxygen content after argon blowing can be controlled to be 16.2-18.1 ppm, and the temperature of the argon exiting station can be 1575-1585 ℃; or, the oxygen content of molten steel after entering an argon station can be controlled to be 37.8-39.5 ppm, a low-aluminum titanium iron wire is added 3.6-3.7 min before exiting the argon station, the oxygen content after argon blowing is controlled to be 16.9-17.5 ppm, and the temperature of the argon exiting station can be 1578-1582 ℃; or a combination of the above ranges. Through setting the argon blowing process, the molten steel can be boiled and refined, so that the purposes of homogenizing the chemical components and the temperature of the molten steel, accelerating the chemical reaction, removing harmful gases and impurities, purifying the molten steel and the like are achieved.
In some embodiments, to better achieve the acceleration of chemical reactions, the removal of harmful gases and inclusions, the purging of molten steel, to achieve a predetermined oxygen content of molten steel, the argon blowing process may include: feeding a proper amount of carbon wires according to the difference between the carbon content before argon blowing and target components, carrying out bottom strong blowing for argon not less than 1min under the pressure of 0.8-1.0 mpa after entering a station, for example, carrying out strong blowing for 3-5 min, ensuring that the soft blowing time of regulating the bottom blowing to the pressure of 0.3-0.4 mpa after the carbon powder, alloy and top slag are well melted, measuring the temperature and sampling, finely regulating to the target components, keeping the temperature at 1580-1590 ℃, regulating the bottom blowing to the pressure of 0.1-0.2 mpa, feeding low-aluminum titanium iron wires for 1.5-1.6 m/t, wherein the low-aluminum titanium iron wire core powder is 390-394 g/m (for example, 392 g/m), the low-aluminum titanium wire titanium content is 67-70% (for example, the content is 68.3%), adding carbonized rice hulls for a soft blowing time of not less than 3min with the pressure of 0.1-0.15 mpa, carrying out fine adjustment to the target components after supplementing the rice hulls according to the condition of slag surface red, feeding the low-aluminum iron wire is stopped after the high-level titanium iron wire is tightly forbidden.
In some embodiments, the total time of argon blowing may be 13 to 16 minutes. For example, the total time of argon blowing may be 14 to 15 minutes, or a combination of the above ranges.
In some embodiments, the continuous casting pouring process may include: setting the pulling speed to be 2.10-2.60 m/min, and setting the water flow of the crystallizer to be 150-170 m 3 And/h, controlling the superheat degree of molten steel in the continuous casting process at 25-40 ℃. For example, the pulling speed is set to be 2.20-2.50 m/min, and the water flow of the crystallizer is 155-167 m 3 And/h, controlling the superheat degree of molten steel in the continuous casting process at 28-37 ℃; or setting the pulling speed to be 2.35-2.45 m/min, and crystallizing the waterThe flow rate is 158-162 m 3 And/h, controlling the superheat degree of molten steel in the continuous casting process at 31-35 ℃; or a combination of the above ranges.
In some embodiments, the continuous casting process may further include: the ladle and the tundish are cast in a protecting way by adopting a long nozzle, and the ladle is connected with the tundish by utilizing the long nozzle, so that molten steel is prevented from directly contacting air. The pouring basket and the crystallizer are protected and cast by adopting a submerged nozzle, and the pouring basket is connected with the crystallizer by utilizing the submerged nozzle to avoid the direct contact of molten steel with air, wherein the insertion depth of the submerged nozzle can be 90-120 mm. A sliding plate is arranged between the long water gap and the bottom of the ladle, between the immersed water gap and the bottom of the tundish, argon is blown at the surface of the sliding plate for protection, air is prevented from entering, and the sliding plate is favorable for replacing the ladle and the water gap. After continuous casting is started, a covering agent is added into the tundish, so that molten steel is prevented from contacting air and adsorbing impurities. The argon flow in the ladle can be set to 130-180L/min. For example, the flow rate may be set to 135 to 170L/min, 142 to 162L/min, 149 to 158L/min, or a combination of the above ranges. After the continuous casting process, the titanium yield is 50-60%, and the titanium yield is good.
In some embodiments, the rolling process may include heating the billet to 1140-1190 ℃, controlling the start rolling temperature to 1050-1100 ℃, and the upper cooling bed temperature to 890-1100 ℃. For example, the method comprises heating a casting blank to 1145-1182 ℃, controlling the initial rolling temperature to 1060-1090 ℃ and the upper cooling bed temperature to 895-1080 ℃; or heating the casting blank to 1150-1175 ℃, controlling the initial rolling temperature to 1070-1080 ℃ and the upper cooling bed temperature to 950-1030 ℃; or a combination of the above ranges.
In some embodiments, the 400 MPa-level earthquake-resistant steel obtained by the above preparation method comprises the following components in weight percentage: c:0.22 to 0.26 percent, si:0.44 to 0.51 percent, mn:1.36 to 1.53 percent, ti:0.012 to 0.050 percent, S:0.015 to 0.020 percent, P:0.020 to 0.025 percent, and the balance of Fe and unavoidable impurity elements. The microstructure of the earthquake-resistant steel bar obtained above is composed of ferrite and pearlite, and has no bainitic structure. The content of titanium is controlled below 0.050%, so that the occurrence of bainite can be avoided, and a yield platform is formed. For example, a 400 MPa-grade earthquake-resistant rebar comprises the following components in weight percent: c:0.23 to 0.25 percent, si:0.47 to 0.50 percent, mn:1.39 to 1.48 percent, ti:0.013 to 0.045 percent, S:0.016 to 0.015 percent, P: 0.021-0.024%, and the balance being Fe and unavoidable impurity elements; or the 400 MPa-level anti-seismic reinforcing steel bar comprises the following components in percentage by weight: c:0.23 to 0.24 percent, si:0.47 to 0.49 percent, mn:1.41 to 1.51 percent, ti: 0.020-0.040%, S:0.016 to 0.019 percent, P: 0.021-0.024%, and the balance of Fe and unavoidable impurity elements.
In some embodiments, the dimensions of the continuous casting billet may be 165mm by 165mm.
In some embodiments, the rebar may be of a gauge Φ10-28 mm. For example, the rebar gauge may be Φ15mm, Φ18mm, Φ20mm, or Φ25mm.
In another aspect, the invention provides a 400 MPa-level anti-seismic steel bar. In some embodiments, the following components may be included in weight percent: c:0.22 to 0.26 percent, si:0.44 to 0.51 percent, mn:1.36 to 1.53 percent of Ti:0.012% -0.050%, S:0.015 to 0.020 percent, P:0.020 to 0.025 percent, and the balance of Fe and unavoidable impurity elements. The microstructure of the 400 MPa-level anti-seismic steel bar consists of ferrite and pearlite, the yield and tensile strength of the steel bar reach 400MPa and above 600MPa respectively, the mechanical property is good, and the strength-to-deflection ratio is more than 1.25.
For a better understanding of the present invention, the content of the present invention is further elucidated below in connection with the specific examples, but the content of the present invention is not limited to the examples below.
Example 1
The 400 MPa-level anti-seismic reinforcing steel bar and the preparation method thereof can comprise the following steps:
s1, steelmaking: smelting molten iron and scrap steel into molten steel in a 50-ton converter, adding lime blocks, and lightly burning dolomite, wherein the smelting end point is C:0.05%, mn:0.07%, P is less than or equal to 0.01%, S is less than or equal to 0.02% and tapping temperature is 1650 ℃. In the tapping process, 50kg of silicon-calcium-barium alloy, 100kg of silicon-iron alloy, 1210kg of silicon-manganese alloy, 30kg of composite silicon carbide and 60kg of carburant are added into a ladle in sequence for deoxidization alloying and carburant. Ladle temperature 804 ℃; after tapping, conveying the steel ladle to an argon blowing station for argon blowing temperature adjustment and alloy fine adjustment.
S2, argon blowing: after molten steel enters an argon station, temperature measurement, sampling and oxygen determination are carried out: 36.8ppm, 26m of carbon wire is fed, the strong blowing of the carbon wire is more than or equal to 1min, the bottom blowing is regulated to the weak blowing and the temperature measurement sampling are carried out after the carbon powder, alloy and top slag are well melted, the strong blowing is more than or equal to 1min after the components and the temperature are finely regulated, then the bottom blowing is regulated to the weak blowing, 95m of low-aluminum ferrotitanium wire is fed 3min before the low-aluminum ferrotitanium wire is discharged, 392g/m of low-aluminum ferrotitanium wire core powder is fed, the titanium content of the low-aluminum ferrotitanium wire is 68.3%, 5 bags (10 kg of each bag) of carbonized rice hulls are added and the soft blowing time is kept for 5min, the low-aluminum ferrotitanium wire is discharged after the carbonized rice hulls are properly added according to the red leakage condition of the slag surface, and the liquid level is greatly turned over after the titanium iron wire is strictly forbidden to be fed. Oxygen was set at 16.8ppm after argon and total argon blowing time was 13min at an outbound temperature of 1576 ℃.
S3, continuous casting: the continuous casting adopts whole-course protection casting. The long nozzle is used for protecting casting, and the ladle is connected with the tundish by the long nozzle, so that molten steel is prevented from directly contacting air; the immersed nozzle is used for protecting casting, and the immersed nozzle is used for connecting the tundish with the crystallizer, so that molten steel is prevented from directly contacting air; the sliding plate is protected by blowing argon, and the sliding plate is arranged between the long water gap and the bottom of the ladle, and between the immersed water gap and the bottom of the tundish, so that the sliding plate is beneficial to replacing the ladle and the water gap; argon is blown to protect the surface of the sliding plate to prevent air from entering; after continuous casting is started, a covering agent is added into the tundish, so that molten steel is prevented from contacting air and adsorbing impurities. The superheat degree is 32 ℃, the pulling speed is 2.30m/min, and the water flow of the crystallizer is 160cm 3 And/h, obtaining the billet for rolling. Wherein, the immersion nozzle insertion depth is 120mm, and the ladle argon flow is set to 130L/min. The yield of titanium after continuous casting is 55%.
S4, rolling: heating a casting blank to 1170 ℃ and starting rolling temperature: 1075 ℃, upper cooling bed temperature: 894 ℃ to prepare the Ti microalloying 400 MPa-level anti-seismic steel bar.
The chemical components of the 400 MPa-level anti-seismic reinforcing steel bar prepared by the embodiment are as follows in percentage by mass: c:0.22%, si:0.47%, mn:1.47%, ti:0.022%, S:0.017%, P:0.021% of Fe and the balance of unavoidable impurity elements, wherein the microstructure diagram is shown in figure 1, the SEM is shown in figure 2, the reinforcing steel bar structure is ferrite and pearlite, and the mechanical properties are shown in table 1.
Example 2
The 400 MPa-level anti-seismic reinforcing steel bar and the preparation method thereof can comprise the following steps:
s1, steelmaking: smelting molten iron and scrap steel into molten steel in a 50-ton converter, adding lime blocks, and lightly burning dolomite, wherein the smelting end point is C:0.08%, mn:0.07%, P is less than or equal to 0.02%, S is less than or equal to 0.03%, and tapping temperature is 1670 ℃. In the tapping process, sequentially adding 50kg of silicon-calcium-barium alloy, 125kg of silicon-iron alloy, 1230kg of silicon-manganese alloy, 35kg of composite silicon carbide and 75kg of carburant into a ladle to deoxidize, alloy and carburant; ladle temperature 825 ℃; after tapping, conveying the steel ladle to an argon blowing station for argon blowing temperature adjustment and alloy fine adjustment.
S2, argon blowing: after molten steel enters an argon station, temperature measurement, sampling and oxygen determination are carried out: feeding a carbon wire of 37.2ppm, feeding the carbon wire of 76m, performing strong blowing for more than or equal to 1min, adjusting the bottom blowing to weak blowing and measuring the temperature and sampling after ensuring that carbon powder, alloy and top slag are well melted, performing strong blowing for more than or equal to 1min after fine adjustment of components and temperature, then adjusting the bottom blowing to weak blowing, adding a low-aluminum titanium iron wire of 97m, low-aluminum titanium iron wire core powder of 392g/m 4min before discharging, adding carbonized rice hulls of 68.3 percent of titanium content of the low-aluminum titanium iron wire, packaging and keeping soft blowing for 6min, discharging after supplementing the carbonized rice hulls in proper amount according to the condition of red slag surface exposure, and strictly forbidding liquid level turning after feeding the titanium iron wire. Oxygen is fixed for 17ppm after argon, total argon blowing time is 15min, outlet temperature is 1588 ℃, and the mixture is sent to continuous casting.
S3, continuous casting: the continuous casting adopts whole-course protection casting. The long nozzle is used for protecting casting, and the ladle is connected with the tundish by the long nozzle, so that molten steel is prevented from directly contacting air; the immersed nozzle is used for protecting casting, and the immersed nozzle is used for connecting the tundish with the crystallizer, so that molten steel is prevented from directly contacting air; the sliding plate is protected by blowing argon, and the sliding plate is arranged between the long water gap and the bottom of the ladle, and between the immersed water gap and the bottom of the tundish, so that the sliding plate is beneficial to replacing the ladle and the water gap; argon is blown to protect the surface of the sliding plate to prevent air from entering; after continuous casting is started, a covering agent is added into the tundish, so that molten steel is prevented from contacting air and adsorbing impurities. The superheat degree is 36 ℃, the pulling speed is 2.30m/min, and the water flow of the crystallizer is 165m 3 And/h, obtaining the billet for rolling. Wherein, the immersion nozzle insertion depth is 120mm, and the ladle argon flow is set to 130L/min. The yield of titanium after continuous casting was 56%.
S4, rolling: heating the casting blank to 1175 ℃ and starting rolling temperature: 1078 ℃, upper cooling bed temperature: 894 ℃ to prepare the Ti microalloying 400 MPa-level anti-seismic steel bar.
The chemical components of the 400 MPa-level anti-seismic reinforcing steel bar prepared by the embodiment are as follows in percentage by mass: c:0.23%, si:0.47%, mn:1.44%, ti:0.028%, S:0.016%, P:0.022 percent of Fe and the balance of unavoidable impurity elements.
The microstructure diagram of the 400 MPa-level anti-seismic steel bar prepared by the method is shown in fig. 3, and the SEM is shown in fig. 4, so that the steel bar structure is ferrite and pearlite. The tensile test curve graph of the 400 MPa-level anti-seismic steel bar prepared in the example is shown in FIG. 7, and the mechanical properties are shown in Table 1.
Example 3
The 400 MPa-level anti-seismic reinforcing steel bar and the preparation method thereof can comprise the following steps:
s1, steelmaking: smelting molten iron and scrap steel into molten steel in a 50-ton converter, adding lime blocks, and lightly burning dolomite, wherein the smelting end point is C:0.09%, mn:0.08%, P:0.02%, S:0.03% and a tapping temperature of 1680 ℃. In the tapping process, 45kg of silicon-calcium-barium alloy, 120kg of silicon-iron alloy, 1250kg of silicon-manganese alloy, 28kg of composite silicon carbide and 70kg of carburant are added into a ladle in sequence for deoxidization alloying and carburating. Ladle temperature 847 ℃. After tapping, conveying the steel ladle to an argon blowing station for argon blowing temperature adjustment and alloy fine adjustment.
S2, argon blowing: after molten steel enters an argon station, temperature measurement, sampling and oxygen determination are carried out: 39.7ppm, adding 126m of carbon wire, feeding the alloy into a station, performing strong blowing for more than or equal to 1min, ensuring that carbon powder, alloy and top slag are well melted, adjusting bottom blowing to weak blowing, measuring temperature, sampling, fine adjusting components, performing strong blowing for more than or equal to 1min after temperature, adjusting bottom blowing to weak blowing, feeding 100m of low-aluminum ferrotitanium wire, 392g/m of low-aluminum ferrotitanium wire core powder 4min before discharging, adding 5 bags of carbonized rice hulls, keeping soft blowing for 7min, discharging after supplementing the carbonized rice hulls in proper amount according to the condition of red slag surface exposure, and strictly disabling the liquid level turning after feeding the ferrotitanium wire. Oxygen is fixed at 17.5ppm after argon, the total argon blowing time is 16min, the outlet temperature is 1585 ℃, and the continuous casting is carried out.
S3, continuous casting: the continuous casting adopts whole-course protection casting. The long nozzle is used for protecting casting, and the ladle is connected with the tundish by the long nozzle, so that molten steel is prevented from directly contacting air; the immersed nozzle is used for protecting casting, and the immersed nozzle is used for connecting the tundish with the crystallizer, so that molten steel is prevented from directly contacting air; the sliding plate is protected by blowing argon, and the sliding plate is arranged between the long water gap and the bottom of the ladle, and between the immersed water gap and the bottom of the tundish, so that the sliding plate is beneficial to replacing the ladle and the water gap; argon is blown to protect the surface of the sliding plate to prevent air from entering; after continuous casting is started, a covering agent is added into the tundish, so that molten steel is prevented from contacting air and adsorbing impurities. The superheat degree is 39 ℃, the pulling speed is 2.50m/min, and the water flow rate of the crystallizer is 166m 3 And/h, obtaining the billet for rolling. Wherein, the immersion nozzle insertion depth is 120mm, and the ladle argon flow is set to 130L/min. The yield of titanium after continuous casting is 55%.
S4, rolling: heating a casting blank to 1180 ℃ and starting rolling temperature: 1082 ℃, upper cooling bed temperature: 891 ℃ to prepare the Ti microalloying 400 MPa-level anti-seismic steel bar.
The chemical components of the 400 MPa-level anti-seismic reinforcing steel bar prepared by the implementation are as follows in percentage by mass: c:0.26%, si:0.50%, mn:1.53%, ti:0.050%, S:0.017%, P:0.022 percent of Fe and the balance of unavoidable impurity elements, wherein a microstructure chart is shown in fig. 5, an SEM is shown in fig. 6, the reinforcing steel bar structure is shown as ferrite and pearlite, and the mechanical properties are shown in table 1.
Table 1 mechanical properties table for preparing reinforcing bars of examples 1 to 3
As shown in the mechanical properties of figures 1-7 and table 1, the steel bar microstructures of examples 1-3 of the invention are ferrite and pearlite, the yield and tensile strength reach 400MPa and 600MPa respectively, and the strength-to-deflection ratio is more than 1.25. The technical requirements of performance can be met by combining the design of titanium microalloying components and the design of technological parameters of converter steelmaking, argon blowing stations, continuous casting and rolling procedures.
Although the present invention has been described above by way of the combination of the exemplary embodiments, it should be apparent to those skilled in the art that various modifications and changes can be made to the exemplary embodiments of the present invention without departing from the spirit and scope defined in the appended claims.
Claims (10)
1. The preparation method of the 400 MPa-level anti-seismic steel bar is characterized by comprising the following steps of:
converter smelting, wherein molten iron and scrap steel are used as raw materials, and the smelting endpoint components are controlled to be C:0.05 to 0.12 percent, less than or equal to 0.20 percent of Mn, less than or equal to 0.035 percent of P, less than or equal to 0.03 percent of S, and the tapping temperature is 1600 to 1650 ℃;
tapping in a converter, and carrying out deoxidization alloying and carburetion in the tapping process;
argon blowing, wherein the oxygen content of molten steel after entering an argon station is controlled to be 35.0-42.5 ppm, titanium-containing materials are added before an argon outlet station, the oxygen content after argon blowing is controlled to be 15.8-18.5 ppm, the temperature of the argon outlet station is controlled to be 1570-1590 ℃, and the molten steel is sent to continuous casting after argon blowing;
continuous casting, namely adopting whole-process protection casting;
and (3) rolling steel, namely heating the casting blank to 1140-1190 ℃, controlling the initial rolling temperature to 1050-1100 ℃, and feeding the casting blank to a cooling bed at 890-1100 ℃ to obtain the 400 MPa-level anti-seismic steel bar after rolling.
2. The method for preparing the 400 MPa-level anti-seismic steel bar according to claim 1, wherein the 400 MPa-level anti-seismic steel bar comprises the following components in percentage by mass: c:0.22 to 0.26 percent, si:0.44 to 0.51 percent, mn:1.36 to 1.53 percent of Ti:0.012% -0.050%, S:0.015 to 0.020 percent, P:0.020 to 0.025 percent, and the balance of Fe and unavoidable impurity elements.
3. The method for preparing a 400 MPa-level earthquake-resistant steel according to claim 1 or 2, wherein the deoxidizing alloying and carburising comprises deoxidizing alloying and carburising by sequentially adding a silicon-calcium-barium alloy, a silicon-iron alloy, a silicon-manganese alloy, silicon carbide and a carburising agent to the molten steel.
4. The method for preparing a 400 MPa-level earthquake-resistant steel bar according to claim 3, wherein the adding amount of the ferrosilicon alloy is 2 kg/t-2.5 kg/t, the adding amount of the ferrosilicon alloy is 24 kg/t-25 kg/t, and the adding amount of the carburant is 1 kg/t-1.5 kg/t;
when the mass fraction content of the smelting end point component C is 0.05-0.07%, the adding amount of silicon carbide is 0.5 kg/t-0.7 kg/t, and the adding amount of the silicon-calcium-barium alloy is 0.9 kg/t-1.1 kg/t;
when the mass fraction content of the smelting end point component C is more than 0.07%, the adding amount of silicon carbide is 0.3 kg/t-0.5 kg/t, and the adding amount of the silicon-calcium-barium alloy is 0.9 kg/t-1.1 kg/t.
5. The method for preparing the anti-seismic steel bar at 400MPa level according to claim 1, 2 or 4, wherein the argon blowing process comprises the steps of ensuring that argon with the bottom strong blowing pressure of 0.8-1.0 MPa is not less than 1min after molten steel enters an argon station, adjusting the strong blowing pressure to the medium air quantity with the pressure of 0.3-0.4 MPa after carbon, alloy and top slag are well melted, fine adjusting the components and the temperature, adjusting the pressure to the weak blowing pressure of 0.1-0.2 MPa, adding a low-aluminum titanium iron wire, and the weak blowing time is more than 5 min.
6. The method for preparing the 400 MPa-level earthquake-resistant steel bar according to claim 1, 2 or 4, wherein the titanium-containing material is low-aluminum titanium iron wire, the adding amount of the low-aluminum titanium iron wire is 1.5 m/t-1.6 m/t, wherein 390 g/m-394 g/m of low-aluminum titanium iron wire core powder is adopted, and the mass ratio of the titanium content of the low-aluminum titanium iron wire is 67% -70%.
7. The method for preparing a 400 MPa-level earthquake-resistant steel bar according to claim 6, wherein the method further comprises adding 1 kg/t-1.5 kg/t carbonized rice husk after adding the low-aluminum titanium iron wire, and keeping the soft blowing time to be more than or equal to 3min.
8. The method for preparing the 400 MPa-level earthquake-resistant steel bar according to claim 1, 2, 4 or 7, wherein,continuous casting comprises setting the pulling speed to be 2.10 m/min-2.60 m/min, and setting the water flow rate of a crystallizer to be 150m 3 /h～170m 3 And/h, controlling the superheat degree of molten steel in the continuous casting process at 25-40 ℃.
9. The method for preparing the 400 MPa-level earthquake-resistant steel bar according to claim 1, 2, 4 or 7, wherein the mass ratio of the scrap steel in the raw materials is 17% -20%.
10. A400 MPa-level anti-seismic reinforcing steel bar is characterized by comprising the following components in percentage by weight: c:0.22 to 0.26 percent, si:0.44 to 0.51 percent, mn:1.36 to 1.53 percent of Ti:0.012% -0.050%, S:0.015 to 0.020 percent, P:0.020 to 0.025 percent, and the balance of Fe and unavoidable impurity elements.
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