CN115612922A - Low-carbon equivalent easy-to-weld 600 MPa-grade high-strength anti-seismic deformed steel bar and preparation method thereof - Google Patents
Low-carbon equivalent easy-to-weld 600 MPa-grade high-strength anti-seismic deformed steel bar and preparation method thereof Download PDFInfo
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- CN115612922A CN115612922A CN202211077186.1A CN202211077186A CN115612922A CN 115612922 A CN115612922 A CN 115612922A CN 202211077186 A CN202211077186 A CN 202211077186A CN 115612922 A CN115612922 A CN 115612922A
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
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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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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Abstract
The invention discloses a 600MPa grade high-strength anti-seismic deformed steel bar with low carbon equivalent and easy welding, which comprises the following chemical components in percentage by mass: 0.15 to 0.20 percent of C, 0.60 to 0.80 percent of Si, 1.10 to 1.50 percent of Mn, less than or equal to 0.045 percent of P/S, 0.20 to 0.30 percent of V, 0.015 to 0.03 percent of Nb, 0.009 to 0.03 percent of N, the balance of Fe and inevitable impurities, and less than or equal to 0.48 percent of Carbon Equivalent (CEV). According to the invention, a certain amount of vanadium-nitrogen-niobium composite microalloy is added while the carbon equivalent in steel is reduced, so that the high strength is maintained, the good welding performance is maintained, and the good strength and the easy welding performance are balanced.
Description
Technical Field
The invention relates to the field of metal material manufacturing, in particular to a 600 MPa-grade high-strength anti-seismic deformed steel bar with low carbon equivalent and easy welding and a preparation method thereof.
Background
The strength of common deformed steel bars is generally improved by increasing the carbon content or carbon equivalent in the steel, and considering the wide application of welding technology in modern buildings, the welding performance of steel is inevitably reduced while the carbon equivalent is improved. Therefore, a novel low-carbon equivalent easily-welded high-strength shock-resistant deformed steel bar is urgently needed.
At present, no easily-welded high-strength anti-seismic deformed steel bar with the yield strength of more than or equal to 600MPa and the strength-to-yield ratio of more than or equal to 1.25 exists. In patent document CN106636961B, a copper-containing nano-reinforcing phase is obtained by adding copper element, and after ultra-fast water cooling, selective solid solution and aging heat treatment after rolling, high-strength, high-toughness and easy-welding steel is obtained, but the performance (yield ratio) and structure of the steel do not meet the requirements of anti-seismic deformed steel.
In a patent document with publication number CN113604729A, a steel plate for a low carbon equivalent easy-welding pressure vessel and a preparation method thereof are disclosed, wherein the steel plate comprises the following chemical components in percentage by weight: c: less than or equal to 0.18 percent, si:0.25 to 0.35%, mn:1.20-1.40%, P is less than or equal to 0.015%, S is less than or equal to 0.005%, nb is less than or equal to 0.015%, ti: not more than 0.015 percent, alt not less than 0.020 percent, as: less than or equal to 0.0050 percent, CEV is controlled to be less than 0.39 percent, and the balance is Fe and inevitable impurities. The production process approach with low cost, simple flow and fast pace is provided for the steel plate with low carbon equivalent and easy welding requirement. However, the steel plate in the patent has low yield strength of only 450MPa, and does not meet the performance requirements of 600 MPa-grade high-strength deformed steel bar.
Disclosure of Invention
The invention aims to provide the low-carbon equivalent easy-welding 600MPa grade high-strength anti-seismic deformed steel bar, a certain amount of vanadium-nitrogen-niobium microalloy is added while the carbon equivalent in the steel is reduced, the high strength is kept, the good welding performance is kept, and the good strength and welding performance balance is presented.
In order to achieve the purpose, the invention provides the following technical scheme:
a low-carbon equivalent easy-welding 600 MPa-grade high-strength anti-seismic deformed steel bar comprises the following chemical components in percentage by mass: 0.15 to 0.20 percent of C, 0.60 to 0.80 percent of Si, 1.10 to 1.50 percent of Mn, less than or equal to 0.045 percent of P/S, 0.20 to 0.30 percent of V, 0.015 to 0.03 percent of Nb, 0.009 to 0.03 percent of N, the balance of Fe and inevitable impurities, and less than or equal to 0.48 percent of Carbon Equivalent (CEV).
The invention also aims to provide a production process of the low-carbon equivalent easy-welding 600 MPa-grade high-strength anti-seismic deformed steel bar, which comprises the following steps:
step one, heating a steel billet to 1150-1220 ℃, and preserving heat for 2-2.5h for homogenization treatment;
step two, air cooling the homogenized billet to 1080-1150 ℃, and hot rolling at the initial rolling temperature of 1080-1150 ℃, the final rolling temperature of 1000-1100 ℃ and the total deformation of 75%;
and step three, cooling the hot rolled steel billet to room temperature.
Preferably, in the third step, the hot-rolled steel slab is air-cooled to room temperature.
Preferably, in the third step, the hot-rolled steel slab is water-cooled to 750-650 ℃, and then air-cooled to room temperature.
The process route of the invention adopts the controlled rolling and controlled cooling technology, controls the conditions in the hot rolling process, leads the phase transformation process to form high-density ferrite crystal nuclei on an austenite matrix, and combines the precipitation strengthening effect brought by the microalloy technology, thereby achieving the purpose of refining the steel tissue after the phase transformation.
The components have the following functions:
carbon (C) the carbon content of steel determines the strength and other properties of the steel. The yield strength and the tensile strength can be respectively improved by 7Mpa and 8Mpa when the carbon content in the steel is increased by 0.01 percent, but the welding performance and the plasticity of the steel are influenced by the excessively high carbon content, C =0.15-0.20 percent, and good obdurability and welding performance can be obtained.
Silicon (Si) acts as a solid solution strengthening effect in steel, improves the strength of steel, and does not substantially increase the carbon equivalent. However, silicon also reduces the plasticity and toughness, and at higher levels, increases the cold embrittlement temperature of the steel. The silicon content control target was Si =0.60-0.80%.
Manganese (Mn) plays a role in solid solution strengthening in steel, and simultaneously can reduce the gamma-alpha phase transition temperature, refine ferrite grains, improve the solid solubility product of vanadium in austenite, enhance the solid solution strengthening and precipitation strengthening effects and improve the strength and toughness of steel, but the carbon equivalent is increased due to the excessively high manganese content, so that the welding performance is influenced. Combined Mn =1.10-1.50%.
Sulfur (S), phosphorus (P): sulfur and phosphorus are harmful elements in steel. Sulfur contributes to high temperature brittleness, while phosphorus contributes to low temperature brittleness. Therefore, the lower the contents of sulfur and phosphorus, the better, but considering the smelting cost, the P/S is less than or equal to 0.045 percent.
Vanadium (V): vanadium is added into molten steel in a vanadium-nitrogen alloy mode, vanadium is used as a microalloy element and can be combined with C and N in the steel to form carbide, nitride or carbonitride, the compounds can play a role in refining crystal grains and improving the strength of a matrix (solid solution strengthening and precipitation strengthening), and the control target of the content of the vanadium is V =0.20-0.30%.
Niobium (Nb): niobium can form a tiny compound with carbon and nitrogen, so that the growth of austenite is effectively inhibited, and the recrystallization temperature can be increased in the steel bar rolling process, so that the recrystallization of austenite is inhibited; the carbonitride precipitated in the rolling process and the cooling process can play roles in precipitation strengthening and grain refinement, but the independent addition of niobium can promote the formation of bainite, and certain loss is caused to the toughness of the steel bar. The niobium content control target was Nb =0.015-0.03%.
Nitrogen (N): micro nitrogen and vanadium are added into the steel to form carbonitride so as to improve the performance, and the specific effects are as follows: (1) Nitrides of microalloy elements are more stable than carbides and have small tendency of polymerization, and the addition of nitrogen elements in the steel bars not only increases the ratio of the volume fraction of second-phase particles to the particle size, but also reduces the column spacing precipitated among the phases; (2) After nitrogen is added into the steel bar, the vanadium in the steel bar which is originally in a solid solution state is converted into vanadium carbonitride in a precipitation state, and the precipitation strengthening effect of the vanadium is fully exerted; (3) The nitrogen content and the vanadium-nitrogen ratio are main factors influencing the size and distribution of a precipitated phase of vanadium nitride. The nitrogen content control target was N =0.009-0.03%.
The invention has the beneficial effects that:
the welding performance of the steel is improved by properly reducing the carbon equivalent, simultaneously vanadium-nitrogen-niobium microalloy elements are added, the vanadium-nitrogen-niobium microalloy elements are combined with C in steel to form carbide, nitride or carbonitride, the compounds are dispersed and separated out in a granular form to play a role in precipitation strengthening, fine V (C, N), nb (C, N) or composite precipitates thereof in austenite become ferrite nucleation points to play a role in refining ferrite, and finally the higher strength of the steel is kept by precipitation strengthening and fine grain strengthening to make up the strength weakening caused by the reduction of the carbon equivalent, so that the balance of good strength and welding performance is presented.
Drawings
FIG. 1 is a production process flow chart of a low-carbon equivalent easy-welding 600MPa grade high-strength anti-seismic deformed steel bar provided by an embodiment of the invention;
FIG. 2 is a microstructure diagram (left: optical lens, right: scanning electron microscope) of a low-carbon equivalent easy-welding 600MPa grade high-strength anti-seismic deformed steel bar provided by an embodiment of the invention.
Detailed Description
The invention is described in further detail below with reference to the following figures and embodiments:
as shown in figure 1, the production process of the 600 MPa-grade high-strength anti-seismic deformed steel bar with low carbon equivalent and easy welding is used for producing the 600 MPa-grade high-strength anti-seismic deformed steel bar, and comprises the following chemical components in percentage by mass: 0.15 to 0.20 percent of C, 0.60 to 0.80 percent of Si, 1.10 to 1.50 percent of Mn, less than or equal to 0.045 percent of P/S, 0.20 to 0.30 percent of V, 0.015 to 0.03 percent of Nb, 0.009 to 0.03 percent of N, the balance of Fe and inevitable impurities, and less than or equal to 0.48 percent of Carbon Equivalent (CEV).
The production process comprises the following steps:
step one, heating a steel billet to 1150-1220 ℃, and preserving heat for 2-2.5h for homogenization treatment;
step two, air cooling the homogenized billet to 1080-1150 ℃, and hot rolling at the initial rolling temperature of 1080-1150 ℃, the final rolling temperature of 1000-1100 ℃ and the total deformation of 75%;
and step three, cooling the hot-rolled steel billet to room temperature through two different controlled cooling processes, namely a controlled cooling process A, which is directly air-cooling to room temperature after rolling, and a controlled cooling process B, which is water-cooling to 750-650 ℃ after rolling, and then air-cooling to room temperature.
Microstructure observation and mechanical test are carried out on the deformed steel bar produced in the way, a microstructure picture is shown in figure 2, mechanical properties are shown in table 1, and when the controlled cooling process B is selected, the yield strength R of the deformed steel bar is el At 665MPa or more, tensile strength R m The high-strength high-elongation concrete has the advantages of being larger than 837MPa, the elongation A of more than 20.3 percent, the maximum total elongation of more than 14.5 percent, the strength-to-yield ratio of 1.26 and excellent performance, and not only meets the performance requirements of new standards on HRB600, but also meets the requirements of anti-seismic performance.
TABLE 1 mechanical Property parameters of the deformed Steel
The foregoing is merely an example of the present invention and common general knowledge in the art of designing and/or characterizing particular aspects and/or features is not described in any greater detail herein. It should be noted that, for those skilled in the art, without departing from the technical solution of the present invention, several variations and modifications can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicability of the patent. The scope of the claims of the present application shall be determined by the contents of the claims, and the description of the embodiments and the like in the specification shall be used to explain the contents of the claims.
Claims (4)
1. The low-carbon equivalent easy-welding 600 MPa-grade high-strength anti-seismic deformed steel bar is characterized by comprising the following chemical components in percentage by mass: 0.15 to 0.20 percent of C, 0.60 to 0.80 percent of Si, 1.10 to 1.50 percent of Mn, less than or equal to 0.045 percent of P/S, 0.20 to 0.30 percent of V, 0.015 to 0.03 percent of Nb, 0.009 to 0.03 percent of N, the balance of Fe and inevitable impurities, and less than or equal to 0.48 percent of Carbon Equivalent (CEV).
2. A production process of the low-carbon equivalent easy-welding 600MPa grade high-strength anti-seismic deformed steel bar as claimed in claim 1, is characterized by comprising the following steps:
step one, heating a steel billet to 1150-1220 ℃, and preserving heat for 2-2.5h for homogenization treatment;
step two, air-cooling the homogenized billet to 1080-1150 ℃, and carrying out hot rolling, wherein the initial rolling temperature is 1080-1150 ℃, the final rolling temperature is 1000-1100 ℃, and the total deformation is 75%;
and step three, cooling the hot rolled steel billet to room temperature.
3. The production process of the low-carbon equivalent easy-welding 600MPa grade high-strength anti-seismic deformed steel bar according to claim 2, is characterized in that: and in the third step, cooling the hot rolled steel billet to room temperature in air.
4. The production process of the low-carbon equivalent easy-welding 600MPa grade high-strength anti-seismic deformed steel bar according to claim 2, is characterized in that: and in the third step, the hot rolled steel billet is cooled to 750-650 ℃ by water and then cooled to room temperature by air.
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| CN202211077186.1A CN115612922A (en) | 2022-09-05 | 2022-09-05 | Low-carbon equivalent easy-to-weld 600 MPa-grade high-strength anti-seismic deformed steel bar and preparation method thereof |
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| CN202211077186.1A CN115612922A (en) | 2022-09-05 | 2022-09-05 | Low-carbon equivalent easy-to-weld 600 MPa-grade high-strength anti-seismic deformed steel bar and preparation method thereof |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102383033A (en) * | 2011-11-08 | 2012-03-21 | 河北钢铁股份有限公司承德分公司 | 600-MPa grade vanadium-containing high-strength hot-rolled steel bar and production method thereof |
| CN104018075A (en) * | 2014-06-25 | 2014-09-03 | 武汉钢铁(集团)公司 | Hot rolled ribbed steel bar with yield-to-tensile ratio of less than or equal to 0.8 and Rel of more than or equal to 600MPa, and production method |
| CN107338392A (en) * | 2017-06-08 | 2017-11-10 | 江阴兴澄特种钢铁有限公司 | High-strength low-yield ratio easily welds moving pressure container steel plate and its manufacture method |
| CN110306116A (en) * | 2019-08-02 | 2019-10-08 | 武汉钢铁集团鄂城钢铁有限责任公司 | A kind of plus ferro-silicon nitride HRB600 high-strength hot rolled ribbed steel bar and its manufacturing method |
| WO2021128590A1 (en) * | 2019-12-24 | 2021-07-01 | 江苏永钢集团有限公司 | 600 mpa-grade steel bar for reinforced concrete and preparation method therefor |
-
2022
- 2022-09-05 CN CN202211077186.1A patent/CN115612922A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102383033A (en) * | 2011-11-08 | 2012-03-21 | 河北钢铁股份有限公司承德分公司 | 600-MPa grade vanadium-containing high-strength hot-rolled steel bar and production method thereof |
| CN104018075A (en) * | 2014-06-25 | 2014-09-03 | 武汉钢铁(集团)公司 | Hot rolled ribbed steel bar with yield-to-tensile ratio of less than or equal to 0.8 and Rel of more than or equal to 600MPa, and production method |
| CN107338392A (en) * | 2017-06-08 | 2017-11-10 | 江阴兴澄特种钢铁有限公司 | High-strength low-yield ratio easily welds moving pressure container steel plate and its manufacture method |
| CN110306116A (en) * | 2019-08-02 | 2019-10-08 | 武汉钢铁集团鄂城钢铁有限责任公司 | A kind of plus ferro-silicon nitride HRB600 high-strength hot rolled ribbed steel bar and its manufacturing method |
| WO2021128590A1 (en) * | 2019-12-24 | 2021-07-01 | 江苏永钢集团有限公司 | 600 mpa-grade steel bar for reinforced concrete and preparation method therefor |
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