CN116875918B - 2000 MPa-grade high-plasticity hot forging quenching distribution steel and preparation method thereof - Google Patents

2000 MPa-grade high-plasticity hot forging quenching distribution steel and preparation method thereof Download PDF

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CN116875918B
CN116875918B CN202310984224.XA CN202310984224A CN116875918B CN 116875918 B CN116875918 B CN 116875918B CN 202310984224 A CN202310984224 A CN 202310984224A CN 116875918 B CN116875918 B CN 116875918B
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CN116875918A (en
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周雯
张绍龙
胡锋
胡丞杨
吴开明
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Wuhan University of Science and Engineering WUSE
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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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C—CHEMISTRY; METALLURGY
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    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
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    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
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    • C21D6/00—Heat treatment of ferrous alloys
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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
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips 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
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • 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
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • 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
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
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    • 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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    • 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
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    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/008—Martensite
    • 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
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Abstract

The invention relates to 2000 MPa-grade high-plasticity hot forging quenching distribution steel and a preparation method thereof, wherein the steel comprises the following chemical components ：C：0.26～0.40%,Mn：2.50～5.50%,Si：0.25～0.75%,Al：1.20～3.00%,Cr：0.22～0.36%,Ni：0.26～0.38%,Mo：0.19～0.34%,Nb：0.02～0.04%,P≤0.010%,S≤0.002%, in percentage by mass and the balance of Fe and unavoidable impurities; and the contents of the elements must satisfy the following relationships at the same time: cr+Ni+Mo is more than or equal to 0.50% and less than or equal to 1.00%, si+Al is more than or equal to 3.50%; smelting molten iron according to the chemical composition requirement of a steel plate, casting or continuously casting into a casting blank, homogenizing, forging, quenching and distributing, and performing cryogenic tempering treatment; the steel prepared by the chemical components and the method is composed of martensite, ferrite and high-stability residual austenite, the yield strength is equal to or more than 1635MPa, the tensile strength is equal to or more than 2200MPa, the KV 2 at 25 ℃ is equal to or more than 100J, the elongation is equal to or more than 17.0%, and the steel has good processing performance and anti-collision performance.

Description

2000 MPa-grade high-plasticity hot forging quenching distribution steel and preparation method thereof
Technical Field
The invention relates to the technical field of preparation of steel for automobiles, in particular to 2000 MPa-grade high-plasticity hot forging quenching distribution steel and a preparation method thereof.
Background
With the rapid development of the automobile industry, the safety of automobiles and the protection of the environment have become an important problem to be considered in the automobile design production, the safety of automobiles is ensured, the steel for automobiles is required to have higher strength and plasticity for the environmental protection, the weight of the automobile body is reduced by 10%, and the fuel oil can be saved by 3% -8%. The most effective way to solve this problem is currently to meet the demand by developing Advanced High Strength Steels (AHSS).
As a representative quenching distribution steel of the third-generation high-strength steel, a great deal of researches on the process and structure properties of the steel are carried out at home and abroad. The quenching and partitioning steel production process is to heat the steel plate to a temperature above Ac3 to be completely austenitized, cool the steel plate to a certain temperature of Ms-Mf at a certain cooling speed, keep the temperature for a period of time, then partition carbon at a certain temperature above Ms, and finally quench the steel plate to room temperature to obtain martensite and a certain amount of stable residual austenite. In recent years, researchers have improved the traditional Q & P process to regulate the microstructure in steel to achieve a certain performance improvement in steel. For example, chinese patent publication No. CN108285965A discloses a quenching-partitioning-cryogenic-tempering treatment process for steel materials, the main function of which is to increase the stability of retained austenite in steel, but the strength of steel is not improved well. For another example, chinese patent documents with publication numbers CN 111321281A, CN109554622a and CN112375881a disclose a method for achieving enhanced plasticization of I & QP steel by microstructure control, a hot rolled Fe-Mn-Al-C steel and a manufacturing method for obtaining Q & P structure from quenching to bainitic region, and a method for producing manganese steel by cyclic quenching+i-Q & P treatment and application thereof, and by controlling the heat treatment process, martensitic/bainitic+ferrite+austenitic steels with different volume contents are obtained, which also greatly improves the toughness of the steel, but when the strength is increased, the elongation of the steel is significantly reduced. The Chinese patent documents with publication numbers of CN111455282A, CN 110129680A and CN109694992A disclose quenching distribution steel with tensile strength more than or equal to 1500MPa produced by adopting a short process and a method for preparing the quenching distribution steel, medium-manganese light Q & P steel and a method for preparing the quenching distribution steel, and quenching distribution steel with tensile strength more than 1500MPa and a method for producing the quenching distribution steel, wherein the quenching distribution steel effectively improves the tensile strength of the steel, but has higher Si content, reduces the welding performance of the steel, and is easy to generate cracks in the rapid cooling process due to low heat conductivity, so that the service performance of the steel is influenced.
In most quenched, split steels, the strength is increased at the expense of ductility and does not enhance both properties at the same time. However, in the event of a crash, the structural components of interest require not only high strength but also high elongation. From the currently published patent, no method for preparing and heat treating Q & P steel with plasticity of more than or equal to 15.0% at the level of 2000MPa is realized.
Disclosure of Invention
The invention aims to obtain the Q & P steel for the automobile with high strength, high elongation and low cost. Therefore, the invention provides 2000MPa grade high-plasticity hot forging quenching distribution steel and a preparation method thereof. The hot-forging quenching distribution steel (Q & P steel) obtained by the process has a martensitic structure, a ferritic structure and high-stability residual austenite structure, has tensile strength of more than or equal to 2200MPa, KV 2 of more than or equal to 100J at 25 ℃, elongation of more than or equal to 17.0%, and has good processing performance and anti-collision performance.
The invention relates to 2000MPa grade high plasticity hot forging quenching distribution steel, which comprises the following chemical components ：C：0.26～0.40%,Mn：2.50～5.50%,Si：0.25～0.75%,Al：1.20～3.00%,Cr：0.22～0.36%,Ni：0.26～0.38%,Mo：0.19～0.34%,Nb：0.02～0.04%,P≤0.010%,S≤0.002%, by mass percent, and the balance of Fe and unavoidable impurities; and the contents of the elements must satisfy the following relationships at the same time: cr+Ni+Mo is more than or equal to 0.50% and less than or equal to 1.00%, si+Al is more than or equal to 3.50%.
Preferably, the 2000MPa grade high-plasticity hot forging quenching distribution steel comprises the following chemical components ：C：0.28～0.36%,Mn：2.79～4.36%,Si：0.32～0.62%,Al：1.59～2.74%,Cr：0.29～0.35%,Ni：0.27～0.38%,Mo：0.22～0.31%,Nb：0.02～0.04%,P≤0.010%,S≤0.002%, in percentage by mass, and the balance of Fe and unavoidable impurities; and the contents of the elements must satisfy the following relationships at the same time: cr+Ni+Mo is more than or equal to 0.50% and less than or equal to 1.00%, si+Al is more than or equal to 3.50%.
The invention relates to a preparation method of 2000 MPa-grade high-plasticity hot forging quenching distribution steel, which comprises the following steps:
(1) Smelting and casting: smelting molten iron according to the chemical composition requirements of a steel plate, and casting or continuously casting into a casting blank;
(2) Homogenization treatment + forging process: homogenizing the casting blank at 1150-1250 deg.c for 1.5-2 hr; the forging process, the forging temperature is 1000-1050 ℃, the final forging temperature is 800-900 ℃, the forging is performed for multiple times, the forging ratio of the forging is controlled to be 2.3-2.6, the total forging ratio is 12-15, a columnar parent austenite structure is formed, and then air cooling is performed;
(3) The quenching and distribution process comprises the following steps: heating the forged steel billet to 650-750 ℃ and preserving heat for 15-20 min for annealing treatment, then placing the sample in a salt bath furnace for quenching to a certain temperature of 170-225 ℃ and preserving heat for 5-10 min, and quenching to room temperature after partitioning treatment;
(4) Deep cooling and tempering: and (3) performing cryogenic treatment on the distributed steel, and then heating to room temperature and tempering. Cryogenic temperature is-80 to-196 ℃, and cryogenic time is 6-12 hours; tempering temperature is 250-450 ℃ and tempering time is 1-3h.
The casting blank is a cube, wherein the cross section is 63-65 x 63-65 mm, the finished products of the steel are cubes, and the cross section size is 14-16 x 15-18 mm. The yield strength of the steel is 1635-1723 MPa, the tensile strength is 2200-2390 MPa, the KV 2 at 25 ℃ is more than or equal to 100J, and the elongation is 17.0-20.5%.
The reason why the main chemical components of the present invention are limited in amount is described in detail below:
The low-density steel takes C-Mn-Si-Al as a main alloy element, wherein C plays a role in solid solution strengthening in the steel, and C promotes austenite to form and precipitates carbide to achieve a precipitation strengthening effect; however, the increase in the carbon content deteriorates the weldability of the steel, and increases the cold shortness and aging sensitivity. Considering the strength and toughness matching property of the steel plate, the mass percentage of C in the steel plate is 0.26-0.40%. Mn can be infinitely dissolved with Fe, so that the strength of the steel is improved, the Mn element can stabilize an austenite matrix, and good plasticity is ensured, but the excessive Mn content can cause segregation in the steel, so that the mass percentage of Mn is 2.50-5.50%. The addition of Al can reduce the density of steel and improve the stacking fault energy, and Al is a ferrite strong stability element, which improves the ferrite stability to ensure that delta ferrite can exist stably, but the hot workability of the steel is deteriorated due to the excessive content of Al, so that the mass percentage of Al is 1.20-3.00%. Si can be added to assist Al in reducing the density of steel, but excessive Si and Al affect the surface quality of steel, so that the mass percentage of Si is 0.25-0.75% and the mass percentage of Si+Al is less than or equal to 3.50%. The invention also adds the alloying elements Mo, ni and Cr, which is beneficial to improving the strength of the steel, and the sum of the mass percentages of the alloying elements Mo, ni and Cr is less than or equal to 0.50 percent and less than or equal to 1.00 percent in consideration of the cost of the steel. In addition, the invention also adds an alloy element Nb to refine the structure in the steel and disperse carbide, thereby playing roles of fine crystal strengthening and dispersion strengthening.
The following details the production process and the reason for setting the process parameters of the low-density steel sheet of the present invention:
(1) According to the invention, the prior austenite can be in a columnar form by adopting the process of carrying out transverse forging for multiple times along two vertical directions, and in addition, the dislocation density in the steel is greatly increased and more high-density dispersed nano precipitates can be generated due to the fact that the prior austenite is subjected to transverse forging for multiple times, so that the prior austenite has higher yield strength than the prior hot rolled steel.
(2) Annealing treatment is carried out after multiple transverse forging, and on one hand, the process enables the steel to keep a certain amount of soft phase ferrite structure in a room temperature environment; on the other hand, the carbon content in the austenite is increased during annealing, so that the stability is increased, and more metastable austenite is retained during quenching. This plays a critical role in increasing the elongation of the steel. Martensite and relatively stable retained austenite are obtained through a quenching partitioning process.
(3) The deep cooling treatment leads part of unstable residual austenite to be decomposed again, the microstructure is thinned in the process, carbon is distributed again in the tempering treatment, and the stability of the residual austenite is further enhanced.
Finally, the multiphase structure of ferrite, martensite, metastable austenite and high-density dispersed nano-precipitate is obtained at room temperature. Compared with other existing ultra-high-strength steel, the steel developed by the invention has better strength-plasticity synergistic effect. When the tensile strength is more than or equal to 2200Mpa, the elongation can still reach more than 17.0%, and the KV 2 at 25 ℃ of the steel reaches more than 100J, which shows that the method of the invention obviously improves the elongation and impact toughness of the steel.
Drawings
FIG. 1 is a flow chart of a production process for preparing a thin 2000 MPa-grade quenched and distributed steel according to the invention;
FIG. 2 is a metallographic structure of a steel material produced in example 3 of the present invention.
Detailed Description
In order to better explain the technical solution of the present invention, the following description of the technical solution of the present invention is given by way of example only and not by way of limitation in any way, in conjunction with specific examples. The following example numbers are merely for the purpose of description and do not represent the advantages or disadvantages of the examples.
Table 1 below is a list of chemical component values for each example of the present invention and comparative example;
Table 2 below is a list of the values of the main process parameters for each example and comparative example of the present invention;
table 3 below shows the results of the main mechanical tests of the examples and comparative examples of the present invention.
Referring to fig. 1, the preparation method of the 2000 MPa-grade high-plasticity hot forging quenching split steel according to the embodiments of the invention comprises the following steps:
(1) Smelting and casting: smelting molten iron according to the chemical composition requirements of a steel plate, and casting or continuously casting into a casting blank;
(2) Homogenization treatment + forging process: homogenizing the casting blank at 1150-1250 deg.c for 1.5-2 hr; the forging process, the forging temperature is 1000-1050 ℃, the final forging temperature is 800-900 ℃, the forging is performed for multiple times, the forging ratio of the forging is controlled to be 2.3-2.6, the total forging ratio is 12-15, a columnar parent austenite structure is formed, and then air cooling is performed;
(3) The quenching and distribution process comprises the following steps: heating the forged steel billet to 650-750 ℃ and preserving heat for 15-20 min for annealing treatment, then placing the sample in a salt bath furnace for quenching to a certain temperature of 170-225 ℃ and preserving heat for 5-10 min, and quenching to room temperature after partitioning treatment;
(4) Deep cooling and tempering: and (3) performing cryogenic treatment on the distributed steel, and then heating to room temperature and tempering. Cryogenic temperature is-80 to-196 ℃, and cryogenic time is 6-12 hours; tempering temperature is 250-450 ℃ and tempering time is 1-3h.
TABLE 1 list of chemical components (wt.%)
TABLE 2 list of values of the main process parameters for each example and comparative example of the present invention (comparative example 2 is hot rolled)
TABLE 3 Performance test analysis results List for each example and comparative example of the present invention
As can be seen from Table 3, the steel prepared by the invention has the yield strength of more than or equal to 1635MPa, the tensile strength of more than or equal to 2200MPa, the 25 ℃ KV 2 of more than or equal to 100J, the elongation rate of more than or equal to 17.0%, and compared with the traditional Q & P steel, the impact toughness and the elongation rate of the steel are greatly improved under the condition of no strength reduction, and the combination of the ultra-high strength and the excellent plasticity is obtained. Compared with the traditional Q & P steel, a certain amount of ferrite is added through an annealing process for improving the toughness. In addition, the content of the residual austenite and the content of C in the residual austenite in the steel are detected through XRD, and the detection result shows that the volume fraction and the carbon content of the residual austenite in the steel prepared by the method are increased, and the residual austenite is enriched in more carbon in the austenite in the first annealing process, so that more residual austenite can be reserved at room temperature. In the deep cooling process, the unstable residual austenite is converted into martensite with higher carbon content, and the supersaturated carbon content in the martensite is distributed into the surrounding residual austenite when tempering is finally carried out, so that the finally obtained finished steel has higher residual austenite content and the carbon content is increased by 0.42 weight percent. The martensite structure is effectively refined by forging and cryogenic treatment, and a large number of dislocation and nano precipitation can be generated by forging, so that the yield strength is greatly improved. In conclusion, the steel prepared by the method greatly improves the yield strength, the impact toughness and the elongation.
FIG. 2 is a metallographic structure diagram of the steel produced in example 3 of the present invention, and it can be seen from the diagram that the structure of the test steel is mainly composed of ultrafine martensite, ferrite and retained austenite, the austenite is distributed between lath bainite, and the bulk martensite austenite island content is extremely small.
In the steel of comparative example 1, the contents of Mn and Al are smaller than the set values, and since Mn and Al are stable elements of retained austenite and ferrite, respectively, the reduction of the element contents thereof results in the reduction of the contents of retained austenite and ferrite, which are the main participants in improving the plasticity of the test steel, the reduction of the contents results in the reduction of the plasticity. In addition, the annealing process temperature of comparative example 1 is higher than the set temperature, no ferrite is generated at the temperature, and the process of comparative example 1 does not perform the carbon partitioning process, eventually resulting in a reduction of the carbon content in austenite, and cannot retain much residual austenite when quenched to room temperature. In summary, although the tensile strength and the yield strength are not quite different, the elongation is significantly reduced. The steel of comparative example 2, whose composition meets the composition requirements of the present invention, adopts a hot rolling process instead of the forging process of the present invention, and although the elongation is comparable to that of the steel of the present invention, its yield strength and tensile strength are greatly reduced, on the one hand, the dislocation density introduced by the rolling process is significantly reduced (dislocation in the forged steel is 2.5 times that of the hot rolled steel) compared with that of the forging process, and on the other hand, severe multiple transverse forging deformation promotes the dispersion distribution of nano precipitates in the matrix, while coarse carbides are formed in martensite in the hot rolled steel.
The above-described embodiments are merely specific examples for illustrating the present invention and do not limit the present invention in any way, and any insubstantial changes made in the contents and form without departing from the scope of the claims of the present invention should be construed as falling within the scope of the claims of the present invention. The invention is not limited to the specific examples described above.

Claims (4)

1. The 2000MPa grade high-plasticity hot forging quenching distribution steel is characterized by comprising the following chemical components by mass percent ：C：0.26～0.40%,Mn：2.50～5.50%,Si：0.25～0.75%,Al：1.20～3.00%,Cr：0.22～0.36%,Ni：0.26～0.38%,Mo：0.19～0.34%,Nb：0.02～0.04%,P≤0.010%,S≤0.002%, and the balance of Fe and unavoidable impurities; and the contents of the elements must satisfy the following relationships at the same time: cr+Ni+Mo is more than or equal to 0.50% and less than or equal to 1.00%, si+Al is more than or equal to 3.50%;
The yield strength of the steel is 1635-1723 MPa, the tensile strength is 2200-2390 MPa, the KV 2 at 25 ℃ is more than or equal to 100J, and the elongation is 17.0-20.5%;
the preparation method of the 2000MPa grade high-plasticity hot forging quenching distribution steel comprises the following steps:
(1) Smelting and casting: smelting molten iron according to the chemical composition requirements of a steel plate, and casting or continuously casting into a casting blank;
(2) Homogenization treatment + forging process: homogenizing the casting blank at 1150-1250 deg.c for 1.5-2 hr; the forging process, the forging temperature is 1000-1050 ℃, the final forging temperature is 800-900 ℃, the forging is performed for multiple times, the forging ratio of the forging is controlled to be 2.3-2.6, the total forging ratio is 12-15, a columnar parent austenite structure is formed, and then air cooling is performed;
(3) The quenching and distribution process comprises the following steps: heating the forged steel billet to 650-750 ℃ and preserving heat for 15-20 min for annealing treatment, then placing the sample in a salt bath furnace for quenching to a certain temperature of 170-225 ℃ and preserving heat for 5-10 min, and quenching to room temperature after partitioning treatment;
(4) Deep cooling and tempering: cryogenic treatment is carried out on the steel after the distribution, then the temperature is raised to room temperature and tempering treatment is carried out, the cryogenic temperature is between minus 196 ℃ and minus 80 ℃, and the cryogenic time is between 6 hours and 12 hours; tempering temperature is 250-450 ℃ and tempering time is 1-3h.
2. The 2000MPa grade high-plasticity hot forging quenching split steel according to claim 1, wherein the steel comprises the following chemical components ：C：0.28～0.36%,Mn：2.79～4.36%,Si：0.32～0.62%,Al：1.59～2.74%,Cr：0.29～0.35%,Ni：0.27～0.38%,Mo：0.22～0.31%,Nb：0.02～0.04%,P≤0.010%,S≤0.002%, in percentage by mass, and the balance of Fe and unavoidable impurities; and the contents of the elements must satisfy the following relationships at the same time: cr+Ni+Mo is more than or equal to 0.50% and less than or equal to 1.00%, si+Al is more than or equal to 3.50%.
3. The 2000 MPa-grade high-plasticity hot-forging and quenching split steel according to claim 1, wherein: the casting blank is a cube, wherein the cross section is 63-65 mm, the finished products of the steel are cubes, and the cross section size is 14-16 mm 15-18 mm.
4. A method for preparing a 2000 MPa-grade high-plasticity hot-forging quenching split steel as claimed in claim 1 or 2, characterized by comprising the following steps:
(1) Smelting and casting: smelting molten iron according to the chemical composition requirements of a steel plate, and casting or continuously casting into a casting blank;
(2) Homogenization treatment + forging process: homogenizing the casting blank at 1150-1250 deg.c for 1.5-2 hr; the forging process, the forging temperature is 1000-1050 ℃, the final forging temperature is 800-900 ℃, the forging is performed for multiple times, the forging ratio of the forging is controlled to be 2.3-2.6, the total forging ratio is 12-15, a columnar parent austenite structure is formed, and then air cooling is performed;
(3) The quenching and distribution process comprises the following steps: heating the forged steel billet to 650-750 ℃ and preserving heat for 15-20 min for annealing treatment, then placing the sample in a salt bath furnace for quenching to a certain temperature of 170-225 ℃ and preserving heat for 5-10 min, and quenching to room temperature after partitioning treatment;
(4) Deep cooling and tempering: cryogenic treatment is carried out on the steel after the distribution, then the temperature is raised to room temperature and tempering treatment is carried out, the cryogenic temperature is between minus 196 ℃ and minus 80 ℃, and the cryogenic time is between 6 hours and 12 hours; tempering temperature is 250-450 ℃ and tempering time is 1-3h.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017214647A (en) * 2016-05-30 2017-12-07 株式会社神戸製鋼所 High strength steel sheet and manufacturing method therefor
CN113061698A (en) * 2021-03-16 2021-07-02 北京理工大学 Heat treatment method for preparing quenching-partitioning steel by taking pearlite as precursor
CN115710668A (en) * 2022-11-15 2023-02-24 山东建筑大学 Method for designing and preparing 48GPa% strength-elongation product medium manganese steel component

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017214647A (en) * 2016-05-30 2017-12-07 株式会社神戸製鋼所 High strength steel sheet and manufacturing method therefor
CN113061698A (en) * 2021-03-16 2021-07-02 北京理工大学 Heat treatment method for preparing quenching-partitioning steel by taking pearlite as precursor
CN115710668A (en) * 2022-11-15 2023-02-24 山东建筑大学 Method for designing and preparing 48GPa% strength-elongation product medium manganese steel component

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