CN116752048A - Ultrahigh-strength and high-toughness medium-manganese steel with strength-plastic product of more than 90GPa% and preparation method thereof - Google Patents
Ultrahigh-strength and high-toughness medium-manganese steel with strength-plastic product of more than 90GPa% and preparation method thereof Download PDFInfo
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- 229910000617 Mangalloy Inorganic materials 0.000 title claims abstract description 130
- 238000002360 preparation method Methods 0.000 title abstract description 26
- 238000005096 rolling process Methods 0.000 claims abstract description 62
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 61
- 238000001816 cooling Methods 0.000 claims abstract description 55
- 238000010438 heat treatment Methods 0.000 claims abstract description 52
- 238000005242 forging Methods 0.000 claims abstract description 41
- 238000000137 annealing Methods 0.000 claims abstract description 35
- 238000005098 hot rolling Methods 0.000 claims abstract description 34
- 238000000034 method Methods 0.000 claims abstract description 33
- 229910001566 austenite Inorganic materials 0.000 claims abstract description 32
- 229910000734 martensite Inorganic materials 0.000 claims abstract description 18
- 238000004519 manufacturing process Methods 0.000 claims abstract description 17
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 17
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 15
- 239000010959 steel Substances 0.000 claims abstract description 15
- 239000012535 impurity Substances 0.000 claims abstract description 10
- 238000005266 casting Methods 0.000 claims abstract description 9
- 239000000126 substance Substances 0.000 claims abstract description 9
- 239000002994 raw material Substances 0.000 claims description 24
- 239000003963 antioxidant agent Substances 0.000 claims description 16
- 230000003078 antioxidant effect Effects 0.000 claims description 16
- 238000003723 Smelting Methods 0.000 claims description 9
- 238000005520 cutting process Methods 0.000 claims description 8
- 230000006698 induction Effects 0.000 claims description 8
- 238000005303 weighing Methods 0.000 claims description 8
- 239000011248 coating agent Substances 0.000 claims description 7
- 238000000576 coating method Methods 0.000 claims description 7
- 238000010791 quenching Methods 0.000 abstract description 10
- 230000000171 quenching effect Effects 0.000 abstract description 10
- 238000005265 energy consumption Methods 0.000 abstract description 3
- 239000002609 medium Substances 0.000 description 99
- 239000003973 paint Substances 0.000 description 18
- 238000010586 diagram Methods 0.000 description 13
- 238000009826 distribution Methods 0.000 description 6
- 238000001887 electron backscatter diffraction Methods 0.000 description 6
- 239000013630 prepared media Substances 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 5
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 238000009776 industrial production Methods 0.000 description 3
- 229910052748 manganese Inorganic materials 0.000 description 3
- 239000011572 manganese Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 230000000717 retained effect Effects 0.000 description 3
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
- 229910000937 TWIP steel Inorganic materials 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 229910000794 TRIP steel Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
- RMLPZKRPSQVRAB-UHFFFAOYSA-N tris(3-methylphenyl) phosphate Chemical compound CC1=CC=CC(OP(=O)(OC=2C=C(C)C=CC=2)OC=2C=C(C)C=CC=2)=C1 RMLPZKRPSQVRAB-UHFFFAOYSA-N 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- 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
-
- 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
- C21D8/0226—Hot rolling
-
- 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
- C21D8/0231—Warm rolling
-
- 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
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
Abstract
The invention provides ultra-high strength and toughness medium manganese steel with a strength-plastic product of more than 90GPa% and a preparation method thereof, and relates to the technical field of ultra-high strength and toughness automobile steel. The ultra-high strength and toughness medium manganese steel comprises the following chemical components in percentage by mass: c:0.2-0.8%, mn:2-8%, si:1.10-3.35%, al:2.00-4.45%, V+Nb: less than or equal to 0.12 percent, less than or equal to 0.008 percent of S, less than or equal to 0.015 percent of P, and the balance of Fe and unavoidable impurities. The preparation method comprises the steps of ingot casting, forging to form a blank, heating at high temperature, carrying out multi-pass hot rolling, carrying out primary water cooling, carrying out multi-pass warm rolling, carrying out secondary water cooling and carrying out critical annealing. The invention adopts an on-line quenching production mode to greatly shorten the whole production flow, omits secondary quenching, and has the processes of hot forging, multi-pass hot rolling, multi-pass warm rolling and critical annealing, thereby not only improving the production efficiency, but also saving the energy consumption and obtaining the layered structure with martensite/ferrite and austenite alternately arranged.
Description
Technical Field
The invention belongs to the technical field of ultrahigh-strength and high-toughness automobile steel, and particularly relates to ultrahigh-strength and high-toughness medium-manganese steel with a strength-plastic product of more than 90GPa percent and a preparation method thereof.
Background
With the push of the 'two carbon' background, the automobile light weight research is the main direction of future development, so the materials of the automobile steel are also continuously updated. The first generation of automobile steel, low alloy high-strength steel, DP steel and the like are mature in process and reliable in product, but the strength and plastic product is difficult to break through 40GPa, and is generally kept at 20-30GPa, and only TRIP steel can reach more than 30 GPa%; in order to realize higher strength-plastic product, high manganese steel is generated as second-generation automobile steel, TWIP steel is a typical representation of the high manganese steel, the strength-plastic product can reach 60GPa, the performance is quite considerable, but the high manganese steel is difficult to further develop due to the fact that the components are designed to be heavy in smelting and subsequent processing processes; the third-generation automobile steel, namely the advanced high-strength steel, is the most representative as the medium manganese steel, and generally has 3-12% Mn content, so that the third-generation automobile steel has more popularization prospect. However, compared with the second-generation TWIP steel, the strength-to-plastic product of the medium manganese steel can reach 40GPa percent, but relatively less breakthrough is made through 60GPa percent. Therefore, in order to better complete the carbon neutralization and the carbon peak, the automobile is lightened to realize the great progress, and the improvement of the strength-plastic product of the medium manganese steel is an important research direction for realizing the high-strength toughening of the medium manganese steel.
At present, the high-strength plastic product of the medium manganese steel is mostly limited to 60-78GPa percent, which is more difficult to achieve or expected to be prepared, and in the preparation process of the medium manganese steel with the high-strength plastic product, the situation that the yield strength or the elongation is too low exists, the preparation cost is higher, and the capacity of improving the high-strength plastic product by combining warm rolling and critical annealing treatment in the preparation mode is poor.
For example: chinese patent CN112410681a discloses a high-strength-plastic product medium manganese steel and a preparation method thereof, the high-strength-plastic product of the prepared medium manganese steel is not more than 90GPa%, and the yield strength and elongation are lower, and the tensile strength is higher, so that the yield ratio is lower, which can make the steel not be effectively utilized, and waste is caused; and the critical annealing treatment is carried out between warm rolling, and the obtained tissue structure has no obvious effect on improving yield strength and strength-plastic product.
Chinese patent CN109666862A discloses a high-strength and high-toughness hot-rolled medium manganese steel with a strength-plastic product of more than 60GPa percent and a preparation method, wherein the selection range of carbon content and manganese content is narrower, the influences of forging, hot rolling and two-phase zone annealing in the preparation process on a structure are not in accordance with actual requirements, and particularly the effects on the improvement of the elongation and the strength-plastic product are poor.
Chinese patent CN109930078A discloses a high strength and high plasticity hot rolled medium manganese steel and a preparation method thereof, which is prepared by quenching and cooling a hot rolled plate twice to room temperature and tempering at 200 ℃, but the maximum product of strength and plasticity of the medium manganese steel can only reach 74gpa·, obviously the tensile strength is lower, and the tensile strength and the elongation can not be synergistically improved.
Chinese patent CN115627328A discloses a heat treatment method for a high-strength plastic product 51GPa% aluminum-containing cold-rolled medium manganese steel, wherein the components of the medium manganese steel are fixed and not modifiable, the protection range is narrow, and the high-cost alloy elements are more selected, so that the production cost is increased; the elongation is not obviously improved by the cyclic annealing pretreatment and the critical annealing treatment, so that the strong plastic product is lower.
Disclosure of Invention
The technical problems to be solved by the invention are that the technical scheme of the ultra-high strength and toughness medium manganese steel with the strength-plastic product of more than 90GPa% is difficult to achieve or expect, most of the technical schemes are in the research field of medium manganese steel with the strength-plastic product of less than 80GPa%, the selection range of carbon content and manganese content is narrow, the preparation cost is increased due to the selection of other high-cost alloy elements, and the matching relationship between critical annealing treatment and hot rolling and warm rolling is unfavorable for improving the strength-plastic product and the like.
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
the ultra-high strength and toughness medium manganese steel with the strength and elongation product of more than 90GPa percent comprises the following chemical components in percentage by mass: c:0.2-0.8%, mn:2-8%, si:1.10-3.35%, al:2.00-4.45%, V+Nb: less than or equal to 0.12 percent, less than or equal to 0.008 percent of S, less than or equal to 0.015 percent of P, and the balance of Fe and unavoidable impurities.
Preferably, the yield strength of the ultra-high strength and toughness medium manganese steel is maximally over 896MPa, the tensile strength is maximally over 1165MPa, the yield ratio is maximally over 0.768, the fracture elongation is maximally over 84%, and the strength-plastic product is maximally over 97GPa%.
Preferably, the yield strength of the ultra-high strength and toughness medium manganese steel is not lower than 869MPa, the tensile strength is not lower than 1136MPa, the yield ratio is not lower than 0.761, the fracture elongation is not lower than 82%, and the product of strength and elongation is not lower than 26.9GPa%.
Preferably, the room temperature structure of the ultra-high strength and toughness medium manganese steel is composed of martensite, ferrite and residual austenite, wherein the proportion of the residual austenite is 20-50%; and its microstructure exhibits lamellar features that alternate along the rolling direction.
The preparation method for the ultra-high strength and toughness medium manganese steel with the strength-plastic product of more than 90GPa percent comprises the following steps:
s1, preparing cast ingots
Weighing the raw material components of the ultra-high strength and toughness medium manganese steel with the strength and elongation product of more than 90GPa percent according to the proportion, smelting the raw material components by a vacuum induction furnace, and casting the raw material components into cast ingots;
s2, forging into a blank
Carrying out hot forging on the cast ingot of the step S1 to obtain a square billet, and cooling the forged square billet to room temperature by a furnace after forging to obtain a forged square billet;
s3, heating at high temperature
Carrying out high-temperature heating treatment on the forged square billet of the S2 to obtain a heated square billet;
s4, multi-pass hot rolling
Carrying out multi-pass hot rolling on the heated square billet in the step S3 to obtain a hot rolled plate;
s5, primary water cooling
Carrying out primary rapid water cooling treatment on the hot rolled plate in the step S4 to obtain a primary water cooling plate;
s6, multi-pass warm rolling
Cutting the primary water-cooled plate in the step S5, and then heating to perform multi-pass warm rolling to obtain a warm-rolled plate;
s7, secondary water cooling
Performing secondary rapid water cooling treatment on the warm rolled plate in the step S6 to obtain a secondary water cooling plate;
s8, critical annealing
And (3) carrying out critical annealing treatment on the secondary water-cooled plate of the S7, and then rapidly cooling the plate to room temperature by water to obtain the ultra-high strength and toughness medium manganese steel with the strength-plastic product of more than 90GPa percent.
Preferably, the square billet size of S2 is 50mm by 50mm to 70mm by 70mm, and the final forging temperature is greater than 1100 ℃.
Preferably, the surface of the S3 is required to be coated with an antioxidant coating before high-temperature heating treatment, the high-temperature heating treatment temperature is 1150-1200 ℃, the heat is preserved for 9-12 hours under the protection of the antioxidant coating, and the surface coating is required to be removed after the furnace is discharged for the next process.
Preferably, the S4 multi-pass hot rolling is performed at a start rolling temperature of 1050-1100 ℃, a finish rolling temperature of 950-1000 ℃ and a thickness of 7-8mm.
Preferably, the temperature of the S6 is increased to 600-1000 ℃ by multi-pass warm rolling, and the temperature is kept for 20-60min.
Preferably, the thickness of the warm rolled sheet material of S6 is 2-2.5mm.
Preferably, the critical annealing treatment of S7 needs to be heated to 600-850 ℃, the temperature is kept for 20-60min, and the heating rate is 8-15 ℃/S.
The technical principle of the invention is as follows:
the strength-plastic product is more than 90GPa, the layered structure ultrahigh strength-toughness medium manganese steel and the preparation method thereof have the alloy element mass percent (wt%) content of C:0.20-0.80, mn:2-8, si:1.10-3.35, al:2.00-4.45, V+Nb: less than or equal to 0.12, less than or equal to 0.008, less than or equal to 0.015, and the balance of Fe and other unavoidable impurities. The yield strength of the medium manganese steel which is formed by martensite/ties element and austenite and has the strength-plastic product of more than 90GPa percent is more than 1100MPa, the tensile strength is more than 850MPa, the elongation after fracture is more than 78 percent, and the strength-plastic product is kept above 90GPa percent.
The invention also provides a specific manufacturing method of the medium manganese steel, the product is smelted by adopting a vacuum furnace, the content of harmful elements such as P, S and the like is strictly controlled, then the product is forged into a forging stock waiting for rolling in a laboratory, the laboratory rolling is carried out by adopting a method simulating a field TMCP+ on-line quenching process, the forging stock is placed in a heating furnace, the temperature is raised to 1150-1200 ℃, the temperature is kept for 10 hours, the surface protection coating is removed after being taken out, the rolling is carried out on a laboratory rolling mill, the biting temperature is 1100-1050 ℃, the steel plate with the thickness of 7-10mm is rolled after 6 times of rolling, the final rolling temperature is higher than 960 ℃, then the water quenching is carried out to room temperature, the water quenching sample is heated to 600-1000 ℃, the furnace temperature is kept stable for 20-120min, the final rolling thickness is 2-3mm, the water is cooled to the room temperature directly, and finally the rolled sample is subjected to critical annealing at 600-850 ℃, so that the ultrahigh-strength high-toughness medium manganese steel plate with the strength and the strength of more than 90GPa% can be obtained.
Compared with the prior art, the technical scheme has at least the following beneficial effects:
according to the scheme, the ultra-high strength and toughness medium manganese steel with the lamellar structure formed by martensite/ferrite and austenite and the strength-plastic product of more than 90GPa percent and the preparation method thereof are provided, meanwhile, the yield strength is always higher than 869MPa, the fracture elongation is higher than 78 percent, the problem that the strength-plastic product of the medium manganese steel is lower is solved, and meanwhile, the blank that the strength-plastic product of the medium manganese steel is 90-100 GPa percent is filled.
According to the invention, the sizes, shapes and volume fractions of martensite, ferrite and residual austenite of the prepared ultra-high strength and toughness medium manganese steel are regulated and controlled, so that the strength and plastic product of the prepared medium manganese steel is obviously improved on the basis of the traditional preparation of the medium manganese steel with the high strength and plastic product, the application range of the medium manganese steel is expanded, and the use value of the medium manganese steel is improved.
The invention adopts an on-line quenching production mode to greatly shorten the whole production flow, omits secondary quenching, and has the processes of hot forging, multi-pass hot rolling, multi-pass warm rolling and critical annealing, thereby not only improving the production efficiency, but also saving the energy consumption and obtaining the layered structure with martensite/ferrite and austenite alternately arranged.
The invention has simple process, greatly shortens the production period, has strong controllability and greatly improves the efficiency, can synergistically improve the strength, the elongation and the impact toughness, and has important guiding function on the industrial production of the automobile steel.
In a word, compared with other traditional methods, the method provided by the invention adopts the processes of hot forging, multi-pass hot rolling, multi-pass warm rolling and critical annealing, has the advantages of simple and convenient process, low operation difficulty and high efficiency, ensures that the structure of the prepared medium manganese steel is formed by alternately arranging martensite/ferrite and austenite after hot rolling, cooperatively improves the strength, the room-temperature impact toughness and the strength-plastic product, widens the upper limit of performance, improves the lower limit of performance, and is beneficial to industrial mass production and popularization and use.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is an SEM morphology diagram of an ultra-high strength and toughness medium manganese steel with a strength-to-plastic product of more than 90GPa% in the embodiment 1 of the invention;
FIG. 2 is an SEM morphology diagram of an ultra-high strength and toughness medium manganese steel with a strength-plastic product of more than 90GPa% in the embodiment 2;
FIG. 3 is an SEM morphology diagram of an ultra-high strength and toughness medium manganese steel with a strength-plastic product of more than 90GPa% in the embodiment 3 of the invention;
FIG. 4 is a graph of engineering stress strain of the ultra-high strength and toughness medium manganese steel with the strength-plastic product of more than 90GPa% in the embodiment 1 of the invention;
FIG. 5 is a graph of engineering stress strain of the ultra-high strength and toughness medium manganese steel with the strength-plastic product of more than 90GPa% in the embodiment 2 of the invention;
FIG. 6 is a graph of engineering stress strain of the ultra-high strength and toughness medium manganese steel with the strength-plastic product of more than 90GPa% in the embodiment 3 of the invention;
FIG. 7 is a graph showing the comparison of the mechanical properties of the ultra-high strength and toughness medium manganese steel with the strength-plastic product of more than 90GPa% and CN114262778A, CN115323252A, CN112410681A, CN109930078A, CN109666862A, CN110408861A in the embodiment 1-3;
FIG. 8 is a stress-strain curve comparison chart of the medium manganese steel prepared by different processes of the invention; wherein: HR represents a hot rolled sample; HR-IA represents a direct critical annealing sample after hot rolling; HR-WR represents a direct warm rolling sample after hot rolling; HR-WR-IA represents a sample of critical annealing after hot rolling and direct warm rolling;
FIG. 9 is a graph showing the actual comparison between the measured elongation after fracture and the unstretched sample size of the ultra-high strength and toughness medium manganese steel with the strength and elongation product of more than 90 GPa%; wherein: the unstretched sample is an original sample, and the measurement of the elongation after fracture aims at the sample after the stretching fracture of the invention sample;
FIG. 10 is an EBSD analysis of ultra-high strength and toughness medium manganese steel with a strength-to-plastic product of more than 90GPa%, a BC diagram, an austenite ratio diagram and an IPF diagram in the embodiment 1 of the invention;
FIG. 11 is an EBSD analysis of ultra-high strength and toughness medium manganese steel with a strength-to-plastic product of more than 90GPa%, a BC diagram, an austenite ratio diagram and an IPF diagram in the embodiment 2 of the invention;
FIG. 12 is an EBSD analysis of ultra-high strength and toughness medium manganese steel with a strength-to-plastic product of more than 90GPa%, BC diagram, austenite ratio diagram and IPF diagram of example 3 of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. It will be apparent that the described embodiments are some, but not all, embodiments of the invention. All other embodiments, which can be made by a person skilled in the art without creative efforts, based on the described embodiments of the present invention fall within the protection scope of the present invention.
Example 1
The ultra-high strength and toughness medium manganese steel with the strength and elongation product of more than 90GPa percent comprises the following chemical components in percentage by mass: c:0.33%, mn:3.2%, si:1.25%, al:2.50%, v+nb: less than or equal to 0.06 percent, less than or equal to 0.007 percent of S, less than or equal to 0.008 percent of P, and the balance of Fe and unavoidable impurities.
The preparation method for the ultra-high strength and toughness medium manganese steel with the strength-plastic product of more than 90GPa percent comprises the following steps:
s1, preparing cast ingots
Weighing the raw material components of the ultra-high strength and toughness medium manganese steel with the strength and elongation product of more than 90GPa percent according to the proportion, smelting the raw material components by a vacuum induction furnace, and casting the raw material components into cast ingots;
s2, forging into a blank
Carrying out hot forging on the cast ingot of the step S1 to obtain a square billet, wherein the square billet is 50mm multiplied by 50mm, the final forging temperature is 1120 ℃, and the furnace is cooled to room temperature after forging to obtain a forged square billet;
s3, heating at high temperature
Carrying out high-temperature heating treatment on the forged square billet in the step S2, wherein the surface of the forged square billet is required to be coated with antioxidant paint before the high-temperature heating treatment, the high-temperature heating treatment temperature is 1200 ℃, the heat is preserved for 10 hours under the protection of the antioxidant paint, and the surface paint is required to be removed after the forged square billet is discharged from a furnace for the next working procedure, so that the heated square billet is obtained;
s4, multi-pass hot rolling
Carrying out multi-pass hot rolling on the heated square billet in the step S3, wherein the initial rolling temperature is 1080 ℃, the final rolling temperature is 960 ℃, and the thickness of a hot rolled plate is 7.5mm, so as to obtain a hot rolled plate;
s5, primary water cooling
Carrying out primary rapid water cooling treatment on the hot rolled plate in the step S4 to obtain a primary water cooling plate;
s6, multi-pass warm rolling
Cutting the primary water-cooled plate in the step S5, heating to 850 ℃ for multi-pass warm rolling, and preserving the temperature for 30min, wherein the thickness of the warm rolled plate is 2.1mm, so as to obtain a warm rolled plate;
s7, secondary water cooling
Performing secondary rapid water cooling treatment on the warm rolled plate in the step S6 to obtain a secondary water cooling plate;
s8, critical annealing
And (3) carrying out critical annealing treatment on the secondary water-cooled plate of the S7, wherein the heating rate is 12 ℃/S, the temperature is raised to 780 ℃, the heat is preserved for 33 minutes, and then the plate is rapidly cooled to room temperature by water, so that the ultra-high strength and toughness medium manganese steel with the strength and plastic product of more than 90GPa% is obtained.
The final mechanical property curve is shown in fig. 4, the yield strength of the ultra-high strength and toughness medium manganese steel in the embodiment is 869.8MPa, the tensile strength is 1136.5MPa, the yield ratio is 0.765, the fracture elongation is 82.39%, and the strength and elongation product is 93.64GPa%.
The room-temperature structure of the ultra-high strength and toughness medium manganese steel is composed of martensite, ferrite and residual austenite, and the microstructure and morphology of the ultra-high strength and toughness medium manganese steel are shown in figure 1; wherein the ratio of the retained austenite is 32.3%; and its microstructure exhibits lamellar features that alternate along the rolling direction.
The EBSD versus its contrast distribution, austenite ratio and orientation distribution is shown in fig. 10.
Example 2
The ultra-high strength and toughness medium manganese steel with the strength and elongation product of more than 90GPa percent comprises the following chemical components in percentage by mass: c:0.63%, mn:5.1%, si:1.76%, al:2.36%, V+Nb: less than or equal to 0.09%, S less than or equal to 0.007%, P less than or equal to 0.006%, and the balance of Fe and unavoidable impurities.
The preparation method for the ultra-high strength and toughness medium manganese steel with the strength-plastic product of more than 90GPa percent comprises the following steps:
s1, preparing cast ingots
Weighing the raw material components of the ultra-high strength and toughness medium manganese steel with the strength and elongation product of more than 90GPa percent according to the proportion, smelting the raw material components by a vacuum induction furnace, and casting the raw material components into cast ingots;
s2, forging into a blank
Carrying out hot forging on the cast ingot of the step S1 to obtain a square billet, wherein the square billet is 50mm multiplied by 50mm in size, the final forging temperature is 1130 ℃, and the furnace is cooled to room temperature after forging to obtain a forged square billet;
s3, heating at high temperature
Carrying out high-temperature heating treatment on the forged square billet in the step S2, wherein the surface of the forged square billet is required to be coated with antioxidant paint before the high-temperature heating treatment, the high-temperature heating treatment temperature is 1180 ℃, the heat is preserved for 10 hours under the protection of the antioxidant paint, and the surface paint is required to be removed after the forged square billet is discharged from a furnace for the next working procedure, so that the heated square billet is obtained;
s4, multi-pass hot rolling
Carrying out multi-pass hot rolling on the heated square billet in the step S3, wherein the initial rolling temperature is 1090 ℃, the final rolling temperature is 970 ℃, and the thickness of a hot rolled plate is 7.8mm, so as to obtain a hot rolled plate;
s5, primary water cooling
Carrying out primary rapid water cooling treatment on the hot rolled plate in the step S4 to obtain a primary water cooling plate;
s6, multi-pass warm rolling
Cutting the primary water-cooled plate in the step S5, heating to 840 ℃ for multi-pass warm rolling, and preserving the heat for 40min, wherein the thickness of the warm rolled plate is 2.3mm, so as to obtain a warm rolled plate;
s7, secondary water cooling
Performing secondary rapid water cooling treatment on the warm rolled plate in the step S6 to obtain a secondary water cooling plate;
s8, critical annealing
And (3) carrying out critical annealing treatment on the secondary water-cooled plate of the S7, wherein the heating rate is 13 ℃/S, the temperature is raised to 800 ℃, the heat is preserved for 30min, and then the plate is rapidly cooled to room temperature by water, so that the ultra-high strength and toughness medium manganese steel with the strength and plastic product of more than 90GPa% is obtained.
The final mechanical property curve is shown in fig. 5, and the ultra-high strength and toughness medium manganese steel of the embodiment has the yield strength of 896.4MPa, the tensile strength of 1165.8MPa, the yield ratio of 0.768, the fracture elongation of 82.92% and the strength-plastic product of 96.67GPa%.
The room-temperature structure of the ultra-high strength and toughness medium manganese steel is composed of martensite, ferrite and residual austenite, and the microstructure and morphology of the ultra-high strength and toughness medium manganese steel are shown in figure 2; wherein the proportion of retained austenite is 32%; and its microstructure exhibits lamellar features that alternate along the rolling direction.
The EBSD versus its contrast distribution, austenite ratio and orientation distribution is shown in fig. 11.
Example 3
The ultra-high strength and toughness medium manganese steel with the strength and elongation product of more than 90GPa percent comprises the following chemical components in percentage by mass: c:0.42%, mn:4.3%, si:1.40%, al:2.78%, v+nb: less than or equal to 0.07 percent, less than or equal to 0.006 percent, less than or equal to 0.007 percent of P, and the balance of Fe and unavoidable impurities.
The preparation method for the ultra-high strength and toughness medium manganese steel with the strength-plastic product of more than 90GPa percent comprises the following steps:
s1, preparing cast ingots
Weighing the raw material components of the ultra-high strength and toughness medium manganese steel with the strength and elongation product of more than 90GPa percent according to the proportion, smelting the raw material components by a vacuum induction furnace, and casting the raw material components into cast ingots;
s2, forging into a blank
Carrying out hot forging on the cast ingot of the step S1 to obtain a square billet, wherein the square billet is 50mm multiplied by 50mm in size, the final forging temperature is 1125 ℃, and the furnace is cooled to room temperature after forging to obtain a forged square billet;
s3, heating at high temperature
Carrying out high-temperature heating treatment on the forged square billet in the step S2, wherein the surface of the forged square billet is required to be coated with antioxidant paint before the high-temperature heating treatment, the high-temperature heating treatment temperature is 1185 ℃, the heat is preserved for 11 hours under the protection of the antioxidant paint, and the surface paint is required to be removed after the forged square billet is discharged from a furnace for the next working procedure, so that the heated square billet is obtained;
s4, multi-pass hot rolling
Carrying out multi-pass hot rolling on the heated square billet in the step S3, wherein the initial rolling temperature is 1075 ℃, the final rolling temperature is 970 ℃, and the thickness of a hot rolled plate is 7.3mm, so as to obtain a hot rolled plate;
s5, primary water cooling
Carrying out primary rapid water cooling treatment on the hot rolled plate in the step S4 to obtain a primary water cooling plate;
s6, multi-pass warm rolling
Cutting the primary water-cooled plate in the step S5, heating to 800 ℃ for multi-pass warm rolling, and preserving the temperature for 35min, wherein the thickness of the warm rolled plate is 2.1mm, so as to obtain a warm rolled plate;
s7, secondary water cooling
Performing secondary rapid water cooling treatment on the warm rolled plate in the step S6 to obtain a secondary water cooling plate;
s8, critical annealing
And (3) carrying out critical annealing treatment on the secondary water-cooled plate of the S7, wherein the heating rate is 10 ℃/S, the temperature is raised to 790 ℃, the temperature is kept for 25 minutes, and then the plate is rapidly cooled to room temperature by water, so that the ultra-high strength and toughness medium manganese steel with the strength and plastic product of more than 90GPa% is obtained.
The final mechanical property curve is shown in fig. 6, the yield strength of the ultra-high strength and toughness medium manganese steel in the embodiment is 880.3MPa, the tensile strength is 1156.5MPa, the yield ratio is 0.761, the fracture elongation is 84.25%, and the strength and elongation product is 97.43GPa%.
The room-temperature structure of the ultra-high strength and toughness medium manganese steel is composed of martensite, ferrite and residual austenite, and the microstructure and morphology of the ultra-high strength and toughness medium manganese steel are shown in figure 3; wherein the retained austenite ratio is 33.8%; and its microstructure exhibits lamellar features that alternate along the rolling direction.
The EBSD versus its contrast distribution, austenite ratio and orientation distribution is shown in fig. 12.
As shown in FIG. 7, as can be seen from the comparison of the mechanical properties of the ultra-high strength and toughness medium manganese steel with the strength-to-plastic product of more than 90GPa% in the embodiments 1-3 of the present invention and the CN114262778A, CN115323252A, CN112410681A, CN109930078B, CN109666862B, CN110408861B patent in the prior art, the strength-to-plastic product of the embodiments 1-3 of the present invention can exceed 90GPa%, while the strength-to-plastic product of the various patents in the prior art is up to 85.36GPa%, and basically, most of the strength-to-plastic products are between 60 and 75 GPa%; and the patent document with the strength-plastic product reaching 85.36GPa% is CN112410681A, wherein the yield strength is very low, so that the yield ratio is also very low, and the prepared medium manganese steel is poor in material utilization rate and is not suitable for industrial production and popularization.
Wherein: the mechanical properties of the CN114262778A, CN115323252A, CN112410681A, CN109930078A, CN109666862A, CN110408861a patent in the prior art are specifically as follows:
the yield strength of the medium manganese steel prepared by CN114262778A is 849MPa, the tensile strength is 1314.9MPa, the yield ratio is 0.646, the fracture elongation is 41.77%, and the strength-plastic product is 54.94 GPa;
the yield strength of the medium manganese steel prepared by CN115323252A is 891.5MPa, the tensile strength is 1216.3MPa, the yield ratio is 0.733, the fracture elongation is 53.4%, and the strength-plastic product is 64.8GPa%;
the yield strength of the medium manganese steel prepared by CN112410681A is 625.19MPa, the tensile strength is 1112.1MPa, the yield ratio is 0.562, the fracture elongation is 76.75%, and the strength-plastic product is 85.36 GPa;
the yield strength of the medium manganese steel sample a prepared by CN109930078A is 598MPa, the tensile strength is 1030MPa, the yield ratio is 0.581, the fracture elongation is 58%, and the strength-plastic product is 60 GPa; the yield strength of the medium manganese steel sample d is 601MPa, the tensile strength is 860MPa, the yield ratio is 0.699, the fracture elongation is 85.3%, and the strength-plastic product is 74 GPa;
the yield strength of the manganese steel in the example 1 prepared by CN109666862A is 893.7MPa, the tensile strength is 1071.1MPa, the yield ratio is 0.834, the fracture elongation is 64.8%, and the strength-plastic product is 69.4 GPa; in example 3, the manganese steel had a yield strength of 698.8MPa, a tensile strength of 1183.3MPa, a yield ratio of 0.591, a fracture elongation of 61.0% and a strength-plastic product of 72.2 GPa;
the yield strength of the medium manganese steel prepared by CN110408861A is 791MPa, the tensile strength is 1061MPa, the yield ratio is 0.746, the fracture elongation is 63%, and the strength-plastic product is 67GPa%.
As shown in fig. 8, stress-strain curve comparison diagrams of the medium manganese steel prepared by different processes of the invention; wherein: HR represents a hot rolled sample; HR-IA represents a direct critical annealing sample after hot rolling; HR-WR represents a direct warm rolling sample after hot rolling; HR-WR-IA represents a sample of critical annealing after hot rolling and direct warm rolling; it is obvious from the results that compared with other traditional preparation processes, the sample prepared by the HR-WR-IA process has the best yield strength and plastic product performance;
as shown in FIG. 9, a 15mm extensometer stretch was used, and it was seen that the gauge length after break was 27.28mm, i.e., the elongation after break was 81.87%; the measurement result is accurate and reliable, and the medium manganese steel prepared by the HR-WR-IA technology has longer elongation after breaking on the basis of higher yield strength.
Example 4
The ultra-high strength and toughness medium manganese steel with the strength and elongation product of more than 90GPa percent comprises the following chemical components in percentage by mass: c:0.47%, mn:4.5%, si:1.42%, al:2.75%, V+Nb: less than or equal to 0.09%, less than or equal to 0.006% S, less than or equal to 0.006% P, and the balance of Fe and unavoidable impurities.
The preparation method for the ultra-high strength and toughness medium manganese steel with the strength-plastic product of more than 90GPa percent comprises the following steps:
s1, preparing cast ingots
Weighing the raw material components of the ultra-high strength and toughness medium manganese steel with the strength and elongation product of more than 90GPa percent according to the proportion, smelting the raw material components by a vacuum induction furnace, and casting the raw material components into cast ingots;
s2, forging into a blank
Carrying out hot forging on the cast ingot of the step S1 to obtain a square billet, wherein the square billet is 70mm multiplied by 70mm in size, the final forging temperature is 1130 ℃, and the furnace is cooled to room temperature after forging to obtain a forged square billet;
s3, heating at high temperature
Carrying out high-temperature heating treatment on the forged square billet in the step S2, wherein the surface of the forged square billet is required to be coated with antioxidant paint before the high-temperature heating treatment, the high-temperature heating treatment temperature is 1170 ℃, the heat is preserved for 11 hours under the protection of the antioxidant paint, and the surface paint is required to be removed after the forged square billet is discharged from a furnace for the next working procedure, so that the heated square billet is obtained;
s4, multi-pass hot rolling
Carrying out multi-pass hot rolling on the heated square billet in the step S3, wherein the initial rolling temperature is 1090 ℃, the final rolling temperature is 960 ℃, and the thickness of a hot rolled plate is 7.6mm, so as to obtain a hot rolled plate;
s5, primary water cooling
Carrying out primary rapid water cooling treatment on the hot rolled plate in the step S4 to obtain a primary water cooling plate;
s6, multi-pass warm rolling
Cutting the primary water-cooled plate in the step S5, heating to 840 ℃ for multi-pass warm rolling, and preserving the temperature for 35min, wherein the thickness of the warm rolled plate is 2.2mm, so as to obtain a warm rolled plate;
s7, secondary water cooling
Performing secondary rapid water cooling treatment on the warm rolled plate in the step S6 to obtain a secondary water cooling plate;
s8, critical annealing
And (3) carrying out critical annealing treatment on the secondary water-cooled plate of the S7, wherein the heating rate is 12 ℃/S, the temperature is raised to 760 ℃, the temperature is kept for 45 minutes, and then the plate is rapidly cooled to room temperature by water, so that the ultra-high strength and toughness medium manganese steel with the strength and plastic product of more than 90GPa% is obtained.
The ultra-high strength and toughness medium manganese steel has the yield strength of 888.6MPa, the tensile strength of 1159.3MPa, the yield ratio of 0.766, the fracture elongation of 83.42% and the strength-plastic product of 96.71GPa%.
The room-temperature structure of the ultra-high strength and toughness medium manganese steel is composed of martensite, ferrite and residual austenite, wherein the proportion of the residual austenite is 32.7%; and its microstructure exhibits lamellar features that alternate along the rolling direction.
Example 5
The ultra-high strength and toughness medium manganese steel with the strength and elongation product of more than 90GPa percent comprises the following chemical components in percentage by mass: c:0.72%, mn:6.3%, si:2.16%, al:3.11%, V+Nb: less than or equal to 0.10 percent, less than or equal to 0.008 percent of S, less than or equal to 0.009 percent of P, and the balance of Fe and unavoidable impurities.
The preparation method for the ultra-high strength and toughness medium manganese steel with the strength-plastic product of more than 90GPa percent comprises the following steps:
s1, preparing cast ingots
Weighing the raw material components of the ultra-high strength and toughness medium manganese steel with the strength and elongation product of more than 90GPa percent according to the proportion, smelting the raw material components by a vacuum induction furnace, and casting the raw material components into cast ingots;
s2, forging into a blank
Carrying out hot forging on the cast ingot of the step S1 to obtain a square billet, wherein the square billet is 60mm multiplied by 60mm in size, the final forging temperature is 1125 ℃, and the furnace is cooled to room temperature after forging to obtain a forged square billet;
s3, heating at high temperature
Carrying out high-temperature heating treatment on the forged square billet in the step S2, wherein the surface of the forged square billet is required to be coated with antioxidant paint before the high-temperature heating treatment, the high-temperature heating treatment temperature is 1175 ℃, the heat is preserved for 11 hours under the protection of the antioxidant paint, and the surface paint is required to be removed after the forged square billet is discharged from a furnace for the next working procedure, so that the heated square billet is obtained;
s4, multi-pass hot rolling
Carrying out multi-pass hot rolling on the heated square billet in the step S3, wherein the initial rolling temperature is 1083 ℃, the final rolling temperature is 97 ℃, and the thickness of a hot rolled plate is 7.7mm, so as to obtain a hot rolled plate;
s5, primary water cooling
Carrying out primary rapid water cooling treatment on the hot rolled plate in the step S4 to obtain a primary water cooling plate;
s6, multi-pass warm rolling
Cutting the primary water-cooled plate in the step S5, heating to 820 ℃ for multi-pass warm rolling, and preserving heat for 38min, wherein the thickness of the warm rolled plate is 2.4mm, so as to obtain a warm rolled plate;
s7, secondary water cooling
Performing secondary rapid water cooling treatment on the warm rolled plate in the step S6 to obtain a secondary water cooling plate;
s8, critical annealing
And (3) carrying out critical annealing treatment on the secondary water-cooled plate of the S7, wherein the heating rate is 8-15 ℃/S, the temperature is raised to 760 ℃, the heat is preserved for 50min, and then the plate is rapidly cooled to room temperature by water, so that the ultra-high strength and toughness medium manganese steel with the strength and plastic product of more than 90GPa% is obtained.
The ultra-high strength and toughness medium manganese steel has the yield strength of 904MPa, the tensile strength of 1176MPa, the yield ratio of 0.769, the fracture elongation of 82.57 percent and the strength-plastic product of 97.10GPa percent.
The room-temperature structure of the ultra-high strength and toughness medium manganese steel is composed of martensite, ferrite and residual austenite, wherein the proportion of the residual austenite is 31.7%; and its microstructure exhibits lamellar features that alternate along the rolling direction.
Example 6
The ultra-high strength and toughness medium manganese steel with the strength and elongation product of more than 90GPa percent comprises the following chemical components in percentage by mass: c:0.78%, mn:7.4%, si:2.25%, al:3.35%, V+Nb: less than or equal to 0.11%, less than or equal to 0.008%, less than or equal to 0.010% of P, and the balance of Fe and unavoidable impurities.
The preparation method for the ultra-high strength and toughness medium manganese steel with the strength-plastic product of more than 90GPa percent comprises the following steps:
s1, preparing cast ingots
Weighing the raw material components of the ultra-high strength and toughness medium manganese steel with the strength and elongation product of more than 90GPa percent according to the proportion, smelting the raw material components by a vacuum induction furnace, and casting the raw material components into cast ingots;
s2, forging into a blank
Carrying out hot forging on the cast ingot of the S1 to obtain a square billet, wherein the square billet is 55mm multiplied by 55mm in size, the final forging temperature is 1122 ℃, and the furnace is cooled to room temperature after forging to obtain a forged square billet;
s3, heating at high temperature
Carrying out high-temperature heating treatment on the forged square billet in the step S2, wherein the surface of the forged square billet is required to be coated with antioxidant paint before the high-temperature heating treatment, the high-temperature heating treatment temperature is 1170 ℃, the heat is preserved for 11 hours under the protection of the antioxidant paint, and the surface paint is required to be removed after the forged square billet is discharged from a furnace for the next working procedure, so that the heated square billet is obtained;
s4, multi-pass hot rolling
Carrying out multi-pass hot rolling on the heated square billet in the step S3, wherein the initial rolling temperature is 1085 ℃, the final rolling temperature is 967 ℃, and the thickness of a hot rolled plate is 7.2mm, so as to obtain a hot rolled plate;
s5, primary water cooling
Carrying out primary rapid water cooling treatment on the hot rolled plate in the step S4 to obtain a primary water cooling plate;
s6, multi-pass warm rolling
Cutting the primary water-cooled plate in the step S5, heating to 810 ℃ for multi-pass warm rolling, and preserving the temperature for 36min, wherein the thickness of the warm rolled plate is 2.5mm, so as to obtain a warm rolled plate;
s7, secondary water cooling
Performing secondary rapid water cooling treatment on the warm rolled plate in the step S6 to obtain a secondary water cooling plate;
s8, critical annealing
And (3) carrying out critical annealing treatment on the secondary water-cooled plate of the S7, wherein the heating rate is 12 ℃/S, the temperature is raised to 790 ℃, the heat is preserved for 42min, and then the plate is rapidly cooled to room temperature by water, so that the ultra-high strength and toughness medium manganese steel with the strength and plastic product of more than 90GPa% is obtained.
The ultra-high strength and toughness medium manganese steel has the yield strength of 916MPa, the tensile strength of 1188MPa, the yield ratio of 0.771, the fracture elongation of 82.34 percent and the strength-plastic product of 97.82GPa percent.
The room-temperature structure of the ultra-high strength and toughness medium manganese steel is composed of martensite, ferrite and residual austenite, wherein the proportion of the residual austenite is 32.1%; and its microstructure exhibits lamellar features that alternate along the rolling direction.
According to the scheme, the ultra-high strength and toughness medium manganese steel with the lamellar structure formed by martensite/ferrite and austenite and the strength-plastic product of more than 90GPa percent and the preparation method thereof are provided, meanwhile, the yield strength is always higher than 869MPa, the fracture elongation is higher than 78 percent, the problem that the strength-plastic product of the medium manganese steel is lower is solved, and meanwhile, the blank that the strength-plastic product of the medium manganese steel is 90-100 GPa percent is filled.
According to the invention, the sizes, shapes and volume fractions of martensite, ferrite and residual austenite of the prepared ultra-high strength and toughness medium manganese steel are regulated and controlled, so that the strength and plastic product of the prepared medium manganese steel is obviously improved on the basis of the traditional preparation of the medium manganese steel with the high strength and plastic product, the application range of the medium manganese steel is expanded, and the use value of the medium manganese steel is improved.
The invention adopts an on-line quenching production mode to greatly shorten the whole production flow, omits secondary quenching, and has the processes of hot forging, multi-pass hot rolling, multi-pass warm rolling and critical annealing, thereby not only improving the production efficiency, but also saving the energy consumption and obtaining the layered structure with martensite/ferrite and austenite alternately arranged.
The invention has simple process, greatly shortens the production period, has strong controllability and greatly improves the efficiency, can synergistically improve the strength, the elongation and the impact toughness, and has important guiding function on the industrial production of the automobile steel.
In a word, compared with other traditional methods, the method provided by the invention adopts the processes of hot forging, multi-pass hot rolling, multi-pass warm rolling and critical annealing, has the advantages of simple and convenient process, low operation difficulty and high efficiency, ensures that the structure of the prepared medium manganese steel is formed by alternately arranging martensite/ferrite and austenite after hot rolling, cooperatively improves the strength, the room-temperature impact toughness and the strength-plastic product, widens the upper limit of performance, improves the lower limit of performance, and is beneficial to industrial mass production and popularization and use.
While the foregoing is directed to the preferred embodiments of the present invention, it will be appreciated by those skilled in the art that various modifications and adaptations can be made without departing from the principles of the present invention, and such modifications and adaptations are intended to be comprehended within the scope of the present invention.
Claims (10)
1. The ultra-high strength and toughness medium manganese steel with the strength-plastic product of more than 90GPa percent is characterized by comprising the following chemical components in percentage by mass: c:0.2-0.8%, mn:2-8%, si:1.10-3.35%, al:2.00-4.45%, V+Nb: less than or equal to 0.12 percent, less than or equal to 0.008 percent of S, less than or equal to 0.015 percent of P, and the balance of Fe and unavoidable impurities.
2. The ultra-high strength and toughness medium manganese steel with a strength-plastic product of more than 90GPa% according to claim 1, wherein the yield strength of the ultra-high strength and toughness medium manganese steel is maximally over 896MPa, the tensile strength is maximally over 1165MPa, the yield ratio is maximally over 0.768, the fracture elongation is maximally over 84%, and the strength-plastic product is maximally over 97GPa%.
3. The ultra-high strength and toughness medium manganese steel with a strength-to-plastic product of more than 90GPa% according to claim 1, wherein the yield strength of the ultra-high strength and toughness medium manganese steel is not lower than 869MPa, the tensile strength is not lower than 1136MPa, the yield ratio is not lower than 0.761, the fracture elongation is not lower than 82%, and the strength-to-plastic product is not lower than 26.9GPa%.
4. The ultra-high strength and toughness medium manganese steel with the strength-plastic product of more than 90GPa percent according to claim 1, wherein the room temperature structure of the ultra-high strength and toughness medium manganese steel is composed of martensite, ferrite and residual austenite, and the proportion of the residual austenite is 20-50%; and its microstructure exhibits lamellar features that alternate along the rolling direction.
5. A method for preparing the ultra-high strength and toughness medium manganese steel with the product of strength and elongation of more than 90GPa% according to any one of claims 1 to 4, which is characterized by comprising the following steps:
s1, preparing cast ingots
Weighing the raw material components of the ultra-high strength and toughness medium manganese steel with the strength and elongation product of more than 90GPa percent according to the proportion, smelting the raw material components by a vacuum induction furnace, and casting the raw material components into cast ingots;
s2, forging into a blank
Carrying out hot forging on the cast ingot of the step S1 to obtain a square billet, and cooling the forged square billet to room temperature by a furnace after forging to obtain a forged square billet;
s3, heating at high temperature
Carrying out high-temperature heating treatment on the forged square billet of the S2 to obtain a heated square billet;
s4, multi-pass hot rolling
Carrying out multi-pass hot rolling on the heated square billet in the step S3 to obtain a hot rolled plate;
s5, primary water cooling
Carrying out primary rapid water cooling treatment on the hot rolled plate in the step S4 to obtain a primary water cooling plate;
s6, multi-pass warm rolling
Cutting the primary water-cooled plate in the step S5, and then heating to perform multi-pass warm rolling to obtain a warm-rolled plate;
s7, secondary water cooling
Performing secondary rapid water cooling treatment on the warm rolled plate in the step S6 to obtain a secondary water cooling plate;
s8, critical annealing
And (3) carrying out critical annealing treatment on the secondary water-cooled plate of the S7, and then rapidly cooling the plate to room temperature by water to obtain the ultra-high strength and toughness medium manganese steel with the strength-plastic product of more than 90GPa percent.
6. The method for producing ultra-high strength and toughness medium manganese steel having a product of strength and elongation of more than 90GPa% according to claim 5, wherein the square billet size of S2 is 50mm×50mm-70mm×70mm and the final forging temperature is more than 1100 ℃.
7. The method for preparing the ultra-high strength and toughness medium manganese steel with the product of strength and elongation more than 90GPa percent according to claim 5, wherein the surface is required to be coated with an antioxidant coating before the high-temperature heating treatment of S3, the high-temperature heating treatment temperature is 1150-1200 ℃, the heat is preserved for 9-12 hours under the protection of the antioxidant coating, and the surface coating is required to be removed after the steel is discharged from a furnace for the next process.
8. The method for producing ultra-high strength and toughness medium manganese steel with a product of strength and elongation of more than 90GPa% according to claim 5, wherein the multi-pass hot rolling of S4 is performed at a start rolling temperature of 1050-1100 ℃, a finish rolling temperature of 950-1000 ℃ and a thickness of the hot rolled plate of 7-8mm.
9. The method for preparing the ultra-high strength and toughness medium manganese steel with the product of strength and elongation being more than 90GPa percent according to claim 5, wherein the temperature of the S6 is required to be increased to 600-1000 ℃ by multi-pass warm rolling, and the temperature is kept for 20-60min.
10. The method for preparing the ultra-high strength and toughness medium manganese steel with the product of strength and elongation being more than 90GPa percent according to claim 5, wherein the critical annealing treatment of S7 is carried out by heating to 600-850 ℃, preserving heat for 20-60min and heating up at a speed of 8-15 ℃/S.
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Citations (12)
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