CN117626131A - Ultrahigh-strength steel with strength-plastic product of more than 30 GPa% and preparation method thereof - Google Patents

Ultrahigh-strength steel with strength-plastic product of more than 30 GPa% and preparation method thereof Download PDF

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CN117626131A
CN117626131A CN202311702486.9A CN202311702486A CN117626131A CN 117626131 A CN117626131 A CN 117626131A CN 202311702486 A CN202311702486 A CN 202311702486A CN 117626131 A CN117626131 A CN 117626131A
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ultra
strength steel
high strength
steel
strength
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吴桂林
李国阳
孙飞龙
汪水泽
吴宏辉
赵海涛
高军恒
张朝磊
毛新平
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University of Science and Technology Beijing USTB
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University of Science and Technology Beijing USTB
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
    • B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
    • B21J5/002—Hybrid process, e.g. forging following casting
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    • C21D1/18—Hardening; Quenching with or without subsequent tempering
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    • 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
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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
    • 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
    • C21D8/0226—Hot rolling
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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
    • 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
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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
    • 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
    • C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
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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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
    • C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
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    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
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    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of silicon
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    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
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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
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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    • 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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    • 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
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    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/001—Austenite
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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
    • C21D2211/008—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 the field of high-strength steel, and provides ultra-high strength steel with a strength-plastic product of more than 30GPa percent and a preparation method thereof, wherein the preparation method comprises the following steps: s1, smelting raw materials according to a set proportion, and casting into a casting blank or a steel ingot; s2, cogging and forging a casting blank or a steel ingot, and then air-cooling to room temperature; s3, reheating the cogged and forged bar to austenitizing temperature, preserving heat, carrying out multi-pass hot rolling to form a plate or carrying out multi-pass secondary forging in a rotating state to form a bar, and cooling to room temperature; s4, austenitizing short-time heat preservation quenching treatment which is not lower than one time is carried out; s5, tempering treatment. The ultra-high strength steel provided by the invention has the total alloy element content of less than 10% through low-cost alloy design, and is prepared by hot forging/hot rolling which can be fully industrially produced, and has lower equipment requirements compared with warm rolling, cold rolling and the like. Meanwhile, the alloy has excellent comprehensive mechanical properties, and the tensile strength is more than 2400MPa, and meanwhile, the strength-plastic product is more than 30GPa percent.

Description

Ultrahigh-strength steel with strength-plastic product larger than 30 GPa% and preparation method thereof
Technical Field
The invention relates to the technical field of high-strength steel, in particular to ultra-high-strength steel with a strength-plastic product of more than 30GPa percent and a preparation method thereof.
Background
The high-strength steel has extremely important value in breaking through the application of materials, and has wide application prospect in the fields of civil infrastructure, machinery, transportation, aerospace, ocean engineering and the like in the future. On the basis of meeting the same bearing capacity, the use amount of materials can be greatly reduced by using the ultra-high strength steel with the strength of more than 2000MPa, and the requirement of light weight is met. However, when the strength exceeds 2400MPa, the inversion relation between the strength and the plasticity is particularly obvious, and the elongation of most alloys is reduced to below 2%. Therefore, it is very challenging in the field of ultra-high strength steels to increase the strength of the steel while maintaining its good plasticity. The strength-plastic product is one of the most important indexes for judging the comprehensive mechanical properties of the high-strength steel, and currently, the strength-plastic product of the ultra-high-strength steel is difficult to exceed 30GPa, the ultra-high-strength steel is difficult to meet the index requirements on plasticity, toughness and the like, and the application of the ultra-high-strength steel is severely limited.
Chinese patent CN 113604753a discloses a high-toughness high-corrosion-resistance maraging stainless steel with high plastic toughness of 2700MPa and a preparation method thereof. The steel is the ultra-high strength steel with highest strength and excellent elongation (> 10%) reported in the current patent literature, the highest strength of preferable components and processes can reach 2737MPa, the elongation is 10.3%, and even so, the strength-plastic product of the steel is 27.8GPa percent, and is still lower than 30GPa percent. Meanwhile, the alloy content of the preferable components of the maraging stainless steel with high plasticity and toughness exceeds 30 percent, the cost is extremely high, the steel is also prepared by adopting a cold rolling process, the cold rolling deformation resistance is high, and the requirement on rolling equipment is extremely high. Therefore, the 2700MPa grade high-ductility high-corrosion-resistance maraging stainless steel is difficult to produce and popularize and apply.
The literature "Li Junkui, yang Zhina, ma Hua, et al A medium-C martensite steel with 2.6GPa Tensile strength and large ductility[J ]. Scripta Materialia,2023,228,115327" uses hot rolling+warm rolling+low temperature tempering technology in combination with preferred components to prepare 2590MPa grade ultra-high strength steel, the total elongation is 14.5%, the strength-plastic product is 37.6 GPa%, although the strength-plastic product of the steel is higher than 30 GPa%, the requirement of the rolling equipment for the technology of warm rolling at 400-600 ℃ adopted by the steel is still higher, and the steel is still difficult to realize in practical production.
Chinese patent CN110055465A discloses a medium manganese ultra-high strength steel and a preparation method thereof, wherein the highest strength-plastic product of the patent can reach 40GPa, the comprehensive mechanical property is excellent, but the highest tensile strength is only 1950MPa, and the requirement of higher strength can not be met by more than 2000 MPa.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, and provides the ultra-high strength steel with the strength-plastic product of more than 30GPa percent and the preparation method thereof, wherein the alloy content is low (less than 10 percent), the preparation cost is low, the comprehensive mechanical property of the high strength steel is extremely excellent, and the tensile strength of the ultra-high strength steel can reach more than 30GPa percent while the tensile strength of the ultra-high strength steel is more than 2400MPa under the optimized components and the process.
The invention adopts the following technical scheme:
on the one hand, the invention provides a preparation method of ultra-high strength steel with a strength-plastic product of more than 30GPa percent, which comprises the following steps:
s1, smelting alloy raw materials with a set proportion, and casting into a casting blank or a steel ingot;
s2, cogging and forging the casting blank or the steel ingot at a set temperature to obtain a cogged and forged bar, and then air-cooling to room temperature;
s3, reheating the cogged and forged bar subjected to the treatment in the step S2 to austenitizing temperature, preserving heat, carrying out multi-pass hot rolling on the cogged and forged bar to form a plate or carrying out multi-pass secondary forging on the cogged and forged bar in a rotating state, and cooling to room temperature;
s4, carrying out austenitizing short-time heat preservation quenching treatment for not less than one time on the plate obtained by hot rolling in the step S3 or the bar obtained by forging;
and S5, tempering the plate or bar material treated in the step S4 to obtain the ultra-high strength steel with the strength-plastic product of more than 30GPa percent.
In any one of the possible implementation manners described above, there is further provided an implementation manner, in step S1, the alloy raw materials include, by mass: c:0.4 to 0.7 percent, si:0.2 to 2.0, mn:0.2 to 2.5, cr:0.2 to 2, ni:0.5 to 3, mo:0.3 to 2, V:0.1 to 0.7, nb: less than or equal to 0.3, and the balance of Fe and unavoidable impurities.
In any one of the possible implementation manners described above, there is further provided an implementation manner, wherein in the step S2, the set temperature is 1150-1250 ℃, and the temperature is kept for 1-3 hours.
In any one of the possible implementation manners described above, there is further provided an implementation manner, wherein in the step S3, the austenitizing temperature is 850-1200 ℃, and the heat preservation time is more than 0.5 h.
In any of the possible implementations described above, there is further provided an implementation, in step S3, the total deformation amount of the multi-pass hot rolling or the multi-pass forging is greater than 60%, and the final rolling temperature of the multi-pass hot rolling or the final forging temperature of the multi-pass forging is greater than 700 ℃.
In any one of the possible implementation manners described above, there is further provided an implementation manner, in step S4, the austenitizing temperature of the short-time thermal insulation quenching treatment of not less than one time is 800-950 ℃, and the thermal insulation quenching treatment time is 1-10 min each time.
In any one of the possible implementations as described above, there is further provided an implementation, in step S4, the cooling mode of austenitizing quenching not less than one time includes air cooling, water mist cooling, oil cooling, water cooling or liquid nitrogen cooling.
In any one of the possible implementations as described above, there is further provided an implementation, in step S5, the tempering treatment includes: and (3) preserving the temperature of the plate obtained by rolling or the bar obtained by forging for 0.1-48 h at 100-320 ℃.
On the other hand, the invention also provides the ultra-high strength steel with the strength-plastic product of more than 30GPa percent, which comprises the following components in percentage by weight: c:0.4 to 0.7 percent, si:0.2 to 2.0, mn:0.2 to 2.5, cr:0.2 to 2, ni:0.5 to 3, mo:0.1 to 2, V:0.1 to 0.7, nb: less than or equal to 0.3, and the balance of Fe and unavoidable impurities;
the ultra-high strength steel is obtained by the preparation method, the ultra-high strength steel structure comprises an equiaxed fine martensitic structure and high-stability residual austenite, the content of the residual austenite is 5-15%, and the tensile strength of the ultra-high strength steel is more than 2400MPa.
The design principle of the chemical components of the invention is as follows:
c element: c is the most important alloy element in steel, certain C content in high-strength martensitic steel can guarantee to obtain sufficient strength through interstitial solid solution strengthening and dislocation strengthening effect provided by interaction of carbon and dislocation, but too high carbon content can improve austenite stability, so that the residual austenite content in a structure obtained after quenching is too high, and the strength of the high-strength steel is reduced, and therefore, the invention limits the weight percentage of C to be between 0.4 and 0.7 percent.
Si element: si can improve the tempering stability of martensitic steel and the tempering brittleness temperature range of steel, so that the tempering temperature of steel can be improved, excellent plasticity and toughness can be obtained, and meanwhile, si can provide good solid solution strengthening effect. Therefore, the present invention sets the weight percentage of Si to be limited to 0.2 to 2.0.
Mn, cr and Ni elements: mn, cr and Ni elements are elements for increasing hardenability, and provide a certain solid solution strengthening effect. However, too high Mn and Ni may cause residual austenite to be too stable, which is disadvantageous in maintaining high strength. Too high Cr may result in the formation of coarse carbides easily. Meanwhile, too high contents of Mn, cr and Ni can cause significant increase in alloy cost. Therefore, the invention limits the weight percentage of Mn to 0.2-2.5; the weight percentage of Cr is limited to 0.2-2; the weight percentage of Ni is limited to 0.5-3.
Mo, V, nb element: mo, V and Nb can form carbide with C to obviously improve the strength of steel through precipitation strengthening, and meanwhile, the steel has obvious effect of refining the structure, but excessive addition of Mo, V and Nb can lead to the increase of the size of a precipitated phase, reduce the effect of precipitation strengthening, and obviously increase the alloy cost. Therefore, the weight percentage of Mo is limited to 0.1-2; v is limited to 0.1-0.7 weight percent; the weight percentage of Nb is limited to 0-0.3.
The technological design idea of the invention is as follows: the ultra-high strength steel prepared by adopting the thought of hot forging/hot rolling and matching with subsequent re-austenitizing quenching and tempering treatment is suitable for the existing ultra-high strength steel production line such as 300M steel and the like, and can completely realize industrial production. The invention can effectively reduce deformation resistance by forging or rolling above austenitizing temperature. Refining the prior austenite grains can reduce the Ms temperature of martensite transformation, which is beneficial to obtaining more stable and relatively more residual austenite (5-15%), the more stable residual austenite avoids explosive transformation from the residual austenite to the martensite in the deformation process, thereby reducing the toughness, and the favorable toughening effect is provided by continuous transformation of the residual austenite phase martensite, namely the TRIP effect. Meanwhile, refining original austenite grains can refine the martensite substructure, and refining the original austenite grains and the martensite plate substructure can enable cracks to deflect in the expansion process to effectively block the expansion of the cracks, so that the fracture toughness of the martensitic steel is finally improved. In addition, refinement of the prior austenite grains can suppress brittle twinned martensite formation. Therefore, the core of the process design is tissue refinement, the adopted method is to obtain unrecrystallized or fine dynamic recrystallized tissue through thermal mechanical deformation above the austenitizing temperature so as to prepare for obtaining fine martensitic tissue after subsequent austenitizing, meanwhile, the original austenitic tissue is further refined on the basis of the original fine tissue by using the austenitizing treatment which is not lower than one time, the austenitizing heat preservation time is limited to be 1-10 min so as to inhibit the growth of crystal grains after austenitizing, and finally good strong plastic matching is obtained. Compared with the lower limit temperature of the general martensite tempering temperature range (150-300 ℃), the tempering temperature range (100-300 ℃) provided by the invention is lower, which is favorable for inhibiting the recovery of dislocation and the precipitation of solid solution carbide, thereby retaining higher strength after tempering.
The beneficial effects of the invention are as follows:
(1) The invention adopts the low-cost alloy design scheme, the alloy content is low (less than 10%), the preparation cost is low, the comprehensive mechanical property of the high-strength steel is extremely excellent, and the tensile strength of the ultra-high-strength steel is more than 2400MPa and the strength-plastic product can reach more than 30GPa percent under the optimized components and the process.
(2) The preparation process comprises hot forging/hot rolling, short-time austenitizing quenching and low-temperature tempering which are not lower than one time, and the process is simple and can completely realize industrial production. The hot forging or hot rolling process has lower equipment requirements than those of warm rolling, cold rolling and the like. The hot rolling or forging and then austenitizing quenching for a plurality of times can obtain a fine martensitic structure and 5-15% of more stable residual austenite, and excellent strong plastic matching is provided.
(3) The steel has excellent hardenability, can obtain a large amount of martensite structures (more than 85 percent) through air cooling, water mist cooling, oil cooling, water cooling and liquid nitrogen cooling after hot rolling/hot forging, has flexible cooling mode and has high cooling process selectivity for production enterprises.
(4) Unlike available martensitic steel with tempering temperature over 150-300 deg.c to obtain certain plasticity, the present invention expands the tempering temperature range of martensitic steel to 100-320 deg.c, i.e. the high strength steel of the present invention has excellent plasticity even after tempering at 150 deg.c, and has obviously suppressed dislocation recovering effect, and thus the present invention can maintain the strength product of 30 GPa% and obtain tensile strength up to 2800MPa, far exceeding the highest strength product (19.9 GPa%) of 2800MPa level superhigh strength steel.
Drawings
FIG. 1 is a schematic flow chart of an ultra-high strength steel with a strength-plastic product of more than 30GPa percent in an embodiment of the invention.
Fig. 2 shows engineering stress-strain curves for example 1 and example 2.
Fig. 3 shows the EBSD prior austenite grain structure of example 2.
Detailed Description
Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be regarded as being isolated, and they may be combined with each other to achieve a better technical effect.
As shown in FIG. 1, the preparation method of the ultra-high strength steel with the strength-plastic product of more than 30GPa percent comprises the following steps:
s1, smelting alloy raw materials with a set proportion, and casting into a casting blank or a steel ingot;
s2, cogging and forging the casting blank or the steel ingot at a set temperature to obtain a cogged and forged bar, and then air-cooling to room temperature;
s3, reheating the cogged and forged bar subjected to the treatment in the step S2 to austenitizing temperature, preserving heat, carrying out multi-pass hot rolling on the cogged and forged bar to form a plate or carrying out multi-pass secondary forging on the cogged and forged bar in a rotating state, and cooling to room temperature;
s4, carrying out austenitizing short-time heat preservation quenching treatment on the plate obtained by hot rolling in the step S3 or the bar obtained by forging for a plurality of times;
and S5, tempering the plate or bar material treated in the step S4 to obtain the ultra-high strength steel with the strength-plastic product of more than 30GPa percent.
In a specific embodiment, in step S1, the alloy raw materials are as follows in mass percent: c:0.4 to 0.7 percent, si:0.2 to 2.0, mn:0.2 to 2.5, cr:0.2 to 2, ni:0.5 to 3, mo:0.1 to 2, V:0.1 to 0.7, nb: less than or equal to 0.3, and the balance of Fe and unavoidable impurities.
In a specific embodiment, in the step S2, the set temperature is 1150-1250 ℃, and the temperature is kept for 1-3 hours.
In a specific embodiment, in step S3, the austenitizing temperature is 850-1200 ℃ and the heat preservation time is more than 0.5 h.
In a specific embodiment, in step S3, the total deformation amount of the multi-pass hot rolling or multi-pass forging is greater than 80%, and the final rolling temperature of the multi-pass hot rolling or the final forging temperature of the multi-pass forging is greater than 700 ℃.
In a specific embodiment, in step S4, the austenitizing temperature of the short-time austenitizing quenching treatment not lower than one time is 800-950 ℃, and the time of each heat preservation quenching treatment is 1-10 min.
In a specific embodiment, in step S4, the cooling manner of the multiple short-time austenitizing quenching includes air cooling, water mist cooling, oil cooling, water cooling or liquid nitrogen cooling.
In a specific embodiment, in step S5, the tempering treatment includes: and (3) preserving the temperature of the plate obtained by rolling or the bar obtained by forging for 0.1-48 h at 100-320 ℃.
The embodiment of the invention relates to ultra-high strength steel with a strength-plastic product of more than 30GPa percent, which comprises the following components in percentage by weight: c:0.4 to 0.7 percent, si:0.2 to 2.0, mn:0.2 to 2.5, cr:0.2 to 2, ni:0.5 to 3, mo:0.1 to 2, V:0.1 to 0.7, nb: less than or equal to 0.3, and the balance of Fe and unavoidable impurities;
the ultra-high strength steel is obtained by the preparation method, the ultra-high strength steel structure comprises equiaxed fine martensite and retained austenite, the retained austenite content is 5-15%, and the tensile strength of the ultra-high strength steel is more than 2400MPa.
The invention is further illustrated by the following specific examples.
In the embodiment, the mechanical property detection adopts GB/T228-2021 first part of a tensile test of a metal material: room temperature test methods; the sample gauge length was 10mm.
Example 1
The chemical components of the ultra-high strength steel with the strength-plastic product of more than 30GPa percent comprise the following components in percentage by weight: c:0.43, si:0.4, mn:0.4, cr:0.8, ni:3, mo:0.5, v:0.3, nb:0, the balance of Fe and unavoidable impurity elements, and the total amount of alloy elements is 5.83%.
The preparation process flow comprises the following steps: smelting, casting, cogging, secondary forging, primary austenitizing quenching and tempering.
Technological parameters: the final forging temperature of the secondary forging is 750 ℃, the forging deformation is 95%, and the cooling mode after forging is water cooling; the austenitizing treatment process is to perform one-time austenitizing quenching, namely, air cooling to room temperature after heat preservation for 8min at 800 ℃, wherein the tempering temperature is 90 ℃, the tempering time is 48h, the strength of the obtained high-strength steel is 2433MPa, the elongation is 15.5%, the strength-plastic product is 37.7GPa, and the engineering stress-strain curve is shown in figure 2.
Example 2
The steel comprises the following chemical components in percentage by weight: c:0.58, si:1.4, mn:0.8, cr:1, ni:1.8, mo:0.5, v:0.3, nb:0, the balance of Fe and unavoidable impurity elements, and the total amount of alloy elements is 6.38%.
The preparation process flow comprises the following steps: smelting, casting, cogging, secondary forging, primary austenitizing quenching and tempering.
Technological parameters: the final forging temperature of the secondary forging is 850 ℃, the forging deformation is 85%, and the cooling mode after forging is water cooling; the austenitizing treatment process is to perform one-time austenitizing quenching, namely water-cooling to room temperature after heat preservation for 2min at 900 ℃, wherein the tempering temperature is 100 ℃, the tempering time is 24 hours, the strength of the high-strength steel is 2920MPa, the total elongation is 12.0%, the product of strength and elongation is 35.0GPa, the engineering stress-strain curve is shown in figure 1, the obtained martensite structure is fine, the original austenite grain size is 1.89 mu m after EBSD reconstruction, and the structure refinement effect is obvious, as shown in figure 3.
Example 3
The steel comprises the following chemical components in percentage by weight: c:0.58, si:1.4, mn:0.8, cr:1, ni:1.8, mo:0.5, v:0.3, nb:0, the balance of Fe and unavoidable impurity elements, and the total amount of alloy elements is 6.38%.
The preparation process flow comprises the following steps: smelting, casting, cogging, secondary forging, tertiary austenitizing quenching and tempering.
Technological parameters: the final forging temperature of the secondary forging is 850 ℃, the forging deformation is 85%, and the cooling mode after forging is water cooling; the austenitizing treatment process is to carry out three austenitizing quenching, namely, the sample is circulated for three times, and the sample is cooled to room temperature after being kept at 900 ℃ for 2 min; the tempering temperature is 200 ℃, the tempering time is 1h, the strength of the obtained high-strength steel is 2621MPa, the elongation is 12.5%, the strength-plastic product is 32.8GPa, the original austenite grain size is only 1.7 mu m through EBSD reconstruction, and the structure refinement effect is more remarkable compared with the primary austenitizing treatment.
Example 4
The steel comprises the following chemical components in percentage by weight: c:0.67, si:1.8, mn:2.3, cr:2.0, ni:0.5, mo:1.8, V:0.3, nb:0.1, the balance of Fe and unavoidable impurity elements, and the total amount of alloy elements is 9.47%.
The preparation process flow comprises the following steps: smelting, casting, cogging, rolling and tempering.
Technological parameters: the final rolling temperature is 950 ℃, the total rolling reduction is 85%, and the cooling mode after rolling is air cooling; the austenitizing treatment process is that water is cooled to room temperature after heat preservation is carried out for 1min at 950 ℃, the tempering temperature is 320 ℃, the tempering time is 0.2h, and the high-strength steel with the strength of 2488MPa, the elongation of 13.8% and the strong plastic product of 34.3GPa percent is obtained.
Example 5
The steel comprises the following chemical components in percentage by weight: c:0.52, si:1.0, mn:0.6, cr:0.8, ni:2.2, mo:0.8, v:0.5, nb:0, the balance of Fe and unavoidable impurity elements, and the total amount of alloy elements is 6.42%.
The preparation process flow comprises the following steps: smelting, casting, cogging, rolling, primary austenitizing quenching and tempering.
Technological parameters: the final rolling temperature is 900 ℃, the rolling deformation is 60%, and the cooling mode after forging is oil cooling; the austenitizing treatment process is to carry out austenitizing quenching twice, namely, the sample is cooled to room temperature after being circularly and twice heat-preserving for 2min at 900 ℃, the tempering temperature is 120 ℃, the tempering time is 1h, the strength of the obtained high-strength steel is 2518MPa, the total elongation is 12.1%, and the strength-plastic product is 30.4GPa percent.
The ultra-high strength steel is prepared by combining low-cost alloy component design (the alloy element ratio is less than 10%) with hot rolling/hot forging, re-austenitizing treatment at no lower than one time and low-temperature tempering, the strength of the prepared ultra-high strength steel exceeds 2400MPa, the strength-plastic product exceeds 30GPa, and the ultra-high strength steel is low-cost ultra-high strength steel with extremely excellent comprehensive mechanical properties. Meanwhile, the lower limit of the martensite tempering temperature is widened from 150 ℃ to 100 ℃, and tempering is performed at a temperature lower than 150 ℃ to obviously inhibit dislocation recovery, so that the ultra-high strength steel has extremely high strength and good plasticity, the strength exceeding 2900MPa is obtained after tempering at 100 ℃ for 24 hours in the embodiment 2, and the total elongation of 12% is maintained, and the ultra-high strength steel with the highest strength in the steel with the total elongation exceeding 10% is reported at present.
Although a few embodiments of the present invention have been described herein, those skilled in the art will appreciate that changes can be made to the embodiments herein without departing from the spirit of the invention. The above-described embodiments are exemplary only, and should not be taken as limiting the scope of the claims herein.

Claims (10)

1. The preparation method of the ultra-high strength steel with the strength-plastic product of more than 30GPa percent is characterized by comprising the following steps:
s1, smelting alloy raw materials with a set proportion, and casting into a casting blank or a steel ingot;
s2, cogging and forging the casting blank or the steel ingot at a set temperature to obtain a cogged and forged bar, and then air-cooling to room temperature;
s3, reheating the cogged and forged bar subjected to the treatment in the step S2 to austenitizing temperature, preserving heat, carrying out multi-pass hot rolling on the cogged and forged bar to form a plate or carrying out multi-pass secondary forging on the cogged and forged bar in a rotating state, and cooling to room temperature;
s4, carrying out austenitizing short-time heat preservation quenching treatment for not less than one time on the plate obtained by hot rolling in the step S3 or the bar obtained by forging;
and S5, tempering the plate or bar material treated in the step S4 to obtain the ultra-high strength steel with the strength-plastic product of more than 30GPa percent.
2. The method for preparing the ultra-high strength steel with the strength-plastic product of more than 30GPa percent according to claim 1, wherein in the step S1, the alloy raw materials comprise the following components in percentage by mass: c:0.4 to 0.7 percent, si:0.2 to 2.0, mn:0.2 to 2.5, cr:0.2 to 2, ni:0.5 to 3, mo:0.3 to 2, V:0.1 to 0.7, nb: less than or equal to 0.3, and the balance of Fe and unavoidable impurities.
3. The method for producing an ultra-high strength steel with a yield strength of more than 30 GPa% according to claim 1, wherein in the step S2, the set temperature is 1150-1250 ℃, and the temperature is kept for 1-3 hours.
4. The method for producing an ultra-high strength steel having a yield strength of more than 30 GPa% as set forth in claim 1, wherein in step S3, the austenitizing temperature is 850 to 1200 ℃ and the holding time is 0.5 hours or more.
5. The method for producing an ultra-high strength steel having a yield strength of more than 30 GPa% according to claim 1, wherein in step S3, the total deformation amount of the multi-pass hot rolling or multi-pass forging is more than 60%, and the final rolling temperature of the multi-pass hot rolling or the final forging temperature of the multi-pass forging is more than 700 ℃.
6. The method for producing an ultra-high strength steel having a yield strength of more than 30 GPa% according to claim 1, wherein in step S4, the austenitizing temperature of the short-time heat-preserving quenching treatment for not less than one time is 800 to 950 ℃, and the heat-preserving quenching treatment time is 1 to 10 minutes each time.
7. The method for producing ultra-high strength steel having a yield strength of more than 30 GPa% according to claim 1, wherein in step S4, the cooling means for the plurality of short-time austenitizing quenches comprises air cooling, mist cooling, oil cooling, water cooling or liquid nitrogen cooling.
8. The method for producing an ultra-high strength steel having a yield strength of more than 30 GPa% as set forth in claim 1, wherein in step S5, the tempering treatment includes: and (3) preserving the temperature of the plate obtained by rolling or the bar obtained by forging for 0.1-48 h at 100-320 ℃.
9. An ultra-high strength steel with a strength-to-plastic product of more than 30 GPa% obtained by the preparation method according to any one of claims 1 to 8, wherein the ultra-high strength steel comprises the following components in mass percent: c:0.4 to 0.7 percent, si:0.2 to 2.0, mn:0.2 to 2.5, cr:0.2 to 2, ni:0.5 to 3, mo:0.3 to 2, V:0.1 to 0.7, nb: less than or equal to 0.3, and the balance of Fe and unavoidable impurities;
the ultra-high strength steel structure comprises a fine martensite structure and residual austenite, wherein the content of the residual austenite accounts for 5-15%.
10. The ultra-high strength steel with a yield strength greater than 30 GPa% as set forth in claim 9 wherein said ultra-high strength steel has a tensile strength greater than 2400MPa.
CN202311702486.9A 2023-12-12 2023-12-12 Ultrahigh-strength steel with strength-plastic product of more than 30 GPa% and preparation method thereof Pending CN117626131A (en)

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