CN115710668A - Method for designing and preparing 48GPa% strength-elongation product medium manganese steel component - Google Patents
Method for designing and preparing 48GPa% strength-elongation product medium manganese steel component Download PDFInfo
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Abstract
The invention relates to the field of advanced high-strength steel design and preparation, in particular to a method for designing and preparing a medium manganese steel with a strength-elongation product of 48GPa%, wherein the medium manganese steel comprises the following chemical components in percentage by mass: 0.1% -0.15%, mn:7.5% -7.9%, si:1.45% -2%, al:3% -4.5%, cu:0.5% -0.51%, mo:0.2%, cr:0.3% -0.35%, nb:0.11%, sc:0.05% -0.06%, B:0.001%, ni:0.011% -0.027%, and the balance of Fe and inevitable impurities; the preparation method comprises the steps of smelting and blank making, forging, heating and heat preservation, hot rolling, cold rolling and Q & P (quenching and partitioning) heat treatment. The elongation percentage of the medium manganese steel produced by the method is more than or equal to 48 percent, the product of strength and elongation is more than or equal to 48GPa percent, the alloy cost is lower, the preparation process is simple, and the method has good application prospect in actual production.
Description
Technical Field
The invention relates to the field of design and preparation of advanced high-strength steel, in particular to a design and preparation method of a medium manganese steel with a strength-plastic product of 48GPa%.
Background
The enormous development of automobile manufacturing industry has promoted the development of world petroleum, steel, transportation industry and social economy, but at the same time, the great amount of automobile fuel consumption and exhaust emissions have great pressure and influence on the global energy development and greenhouse gas effect. With the enhancement of awareness of protecting the environment and saving energy and reducing emission of people, the light weight of automobiles becomes a development trend of the automobile industry. With the trend of light weight of automobiles, researchers are actively researching and developing third-generation advanced high-strength steel. The third generation advanced high-strength steel represented by medium manganese steel is widely researched due to low cost and excellent performance, the microstructure characteristics of the first generation advanced high-strength steel and the second generation advanced high-strength steel are considered, the strong plasticity of the steel is improved by means of grain refinement, solid solution strengthening, precipitation strengthening, dislocation strengthening and the like, the strength and the plasticity of the steel are improved by the TRIP effect of metastable austenite, and the automobile safety is better met. The high-strength medium manganese steel with excellent anti-collision deformation capability, high strength, high elongation and stable performance becomes a pursuit target of the third generation of advanced high-strength steel.
The expert scholars design a plurality of medium manganese steels with different alloy component contents, such as: cold rolled Fe-0.11C-7.2Mn-1.0Si (wt.%), cold rolled Fe-8.3Mn-5.5Al-0.25C (wt.%), hot rolled Fe-0.1C-10Mn-1Si-0.3Mo-0.5V (wt.%), hot rolled Fe-8Mn-0.2C-3Al-1.3Si (wt.%), hot rolled Fe-8Mn-0.2C-3Al (wt.%), etc., with the above-described intermediate manganese steels having different alloy composition contents, there are significant performance differences. Although the traditional C-Mn-Si series medium manganese steel has excellent mechanical properties, the matching of strength and plasticity is still not ideal, and the comprehensive mechanical properties need to be further improved. The alloy components and the content of the medium manganese steel have great influence on the mechanical property and the microstructure evolution of the medium manganese steel, so that the medium manganese steel with more reasonable alloy components and content, higher strength, better plasticity and more excellent comprehensive performance is designed and is the trend of the development of the automobile steel preparation industry in the current society.
Speer et al in 2003 put forward a Q & P process on the basis of the traditional martensite and bainite phase transformation theory to produce high-strength plastic Q & P steel with TRIP effect. The Q & P process can diffuse carbon elements from the carbon-rich martensite into austenite, realize that part of austenite is rich in carbon, improve the stability, further keep the austenite to room temperature and obtain martensite and a large amount of retained austenite tissues.
Disclosure of Invention
The invention provides a method for designing and preparing a medium manganese steel component with a 48GPa% product of strength and elongation; by reasonably designing and optimizing components, wherein Al and Sc elements are added to update the component design, optimizing the production process scheme and combining the cold rolling and Q & P processes, the medium manganese steel with high strength, good plasticity and high product of strength and elongation is obtained; residual austenite which can be largely reserved and stabilized at room temperature is obtained by further optimizing the Q & P heat treatment process, the elongation of the steel is improved by the continuous TRIP effect of the residual austenite, and a higher product of strength and elongation is obtained.
The composition proportion of the invention is realized by changing the content of some elements and adding some alloy elements which can strengthen and improve the mechanical property of steel materials on the basis of the traditional medium manganese steel, and follows the principle of 'multi-element and small amount' alloying, and simultaneously the invention obtains the medium manganese steel with high strength, good plasticity and high product of strength and plasticity by matching the cold rolling and Q & P (quenching-distribution) heat treatment process, and the product of strength and plasticity is more than or equal to 48GPa%.
The invention provides a method for designing and preparing a medium manganese steel with a 48GPa% strength-elongation product, which comprises the following chemical components in percentage by mass: 0.1% -0.15%, mn:7.5% -7.9%, si:1.45% -2%, al:3% -4.5%, cu:0.5% -0.51%, mo:0.2%, cr:0.3% -0.35%, nb:0.11%, sc:0.05% -0.06%, B:0.001%, ni: 0.011-0.027%, and the balance of Fe and inevitable impurities. In the design and preparation method of the components of the medium manganese steel with the strength-elongation product of 48GPa%, the design basis of the effects and contents of all elements in the steel is as follows:
c element: carbon can greatly improve the properties of strength, hardness and the like of the material, but simultaneously reduces the plasticity, toughness and welding performance of the material, and when the carbon content exceeds 0.23%, the welding performance of steel is deteriorated. Meanwhile, the C element is an austenite stabilizing element and can enlarge an austenite phase region, so that the content of residual austenite is increased, and a remarkable TRIP effect occurs during deformation, thereby improving the strength, plasticity and work hardening capacity of the steel. Therefore, the content of the C element is selected to be 0.1-0.15%.
Mn element: the content and the stability of austenite can be improved by adding the Mn element, an austenite phase region is enlarged, the stacking fault energy and the stability of the austenite can be obviously influenced by the content of the Mn element, and then the deformation mechanism of steel is determined, so that the TRIP effect and the TWIP effect occur, and the mechanical property of the steel is influenced. However, the content of Mn element is too high, which increases the production cost and affects the welding performance of the steel plate. Therefore, the content of Mn element is selected to be 7.5% -7.9%.
Al element: al is a lightweight element, can greatly reduce the density of the material, is a ferrite stabilizing element, can enlarge a ferrite area, and stabilizes and increases the content of alpha-ferrite; meanwhile, the effect of Al on Stacking Fault Energy (SFE) affects the strengthening and toughening mechanism of the material, but too high Al causes the strength of the material to decrease. Therefore, the content of Al element is selected to be 3% -4.5%.
Si element: the Si element can obviously improve the elastic limit, yield point and tensile strength of the steel and does not obviously reduce the plasticity of the steel; most importantly, si can inhibit the precipitation of cementite; however, si content too high adversely affects weldability of steel and lowers surface coating properties of steel sheet, so that Si content is selected from 1.45% to 2%.
Cr element: the Cr element is an alloy element which is widely applied in actual industrial production, and can obviously improve the strength, the hardness and the high-temperature mechanical property of the steel, so that the steel has good oxidation resistance, corrosion resistance, wear resistance, hardenability and fatigue resistance. However, the reserves of the Cr element in China are small, and the Cr element is used sparingly or replaced by other elements as much as possible, so the strength, the resource reserves, the cost and other factors are considered. Therefore, the content of Cr element is selected to be 0.3% -0.35%.
Cu element and Ni element: the Cu element has an enrichment effect in steel, can distribute second phase particles with a certain size in a martensite matrix to play a role in dispersion strengthening, and the addition of the Cu element in the steel can enable a steel plate to have good welding performance and corrosion resistance, and has the defect that when the Cu content exceeds 0.5 percent, the steel is easy to generate a hot brittleness phenomenon in a hot working process, so that a proper amount of Ni element is added and matched with the Ni element for use, so that the hot brittleness phenomenon caused by the Cu element in the hot working of the material is eliminated, and precipitation strengthening is generated; meanwhile, the addition of the Ni element is beneficial to improving the strength of the steel and keeping good plasticity and toughness. Therefore, the content of Cu element is selected to be 0.5% -0.51%, and the content of Ni element is selected to be 0.011% -0.027%.
Sc element: sc element can greatly influence the phase change process of steel, thereby changing the composition and structure of phase change products, and Sc element has the function of 'modification', and oxide, sulfide or oxysulfide generated by reaction with oxygen and sulfur in molten steel can partially remain in the molten steel to become inclusion in the steel. The inclusions have high melting points and can be used as heterogeneous nucleation centers during solidification of molten steelThe function of refining the solidification structure of the steel is achieved; and because the inclusions are not easy to deform at the steel rolling temperature and still keep fine spherical or spindle shapes, the shapes of the inclusions in the steel are controlled, thereby avoiding or overcoming the anisotropy of the steel performance caused by the extension deformation of other types of inclusions when the steel is subjected to hot pressure processing, and leading the longitudinal and transverse performances of the steel to be consistent with the performance in the thickness direction. The Sc element can make the precipitated phase more uniformly distributed, so that the fatigue performance and the corrosion resistance of the steel are improved, the microhardness of the steel is obviously improved, and meanwhile, al is precipitated in the heat treatment process 3 Sc, which hinders the movement of dislocations, thereby improving the strength of the steel. Therefore, the content of Sc element is selected to be 0.05-0.06%.
B element: the main function of the B element is to improve the hardenability of the steel, the trace boron element has obvious effect on improving the hardenability of the steel, the hardenability of the steel can be greatly improved by adding a very small amount of the B element, and the B element content is selected to be 0.001% in consideration of the phenomenon of boron brittleness caused by the fact that the toughness of the steel is strongly reduced when the B element content is more than 0.004%.
The smelting process comprises the following steps: the industrial pure iron with a rustless and smooth surface is placed into a magnesium oxide crucible in a vacuum induction melting furnace in advance, then the vacuum induction furnace is pumped to the limit vacuum degree and is filled with argon, the vacuum induction furnace is electrified and heated, and after the industrial pure iron is completely melted, the alloy materials with the specific proportion designed by the invention are sequentially added at different time points. Firstly, silicon powder and aluminum particles are added into the smelting furnace, which can improve the yield of subsequent alloy materials. Manganese is easy to volatilize at high temperature to generate a large amount of smoke, so that the condition of molten steel is difficult to observe through a visual window, and the judgment of smelting conditions in the furnace is influenced, therefore, electrolytic manganese is added finally. And after power failure, pouring molten steel into a steel ingot mold in a vacuum induction furnace to be cast into an ingot, reversely knocking the bottom of the mold after the ingot is cooled to 1200 ℃, and finally taking out and air-cooling. And then putting the cast ingot into a refining furnace, heating and melting again, and refining to ensure that various alloy elements are distributed more uniformly. Finally obtaining a casting blank.
The casting blank is subjected to the following steps:
(1) Forging and heating the casting blank, hot rolling and coiling to obtain a hot rolled steel plate: forging the casting blank, heating to 1500 ℃ for uniform austenitizing for 1.5h, then carrying out 4-pass hot rolling deformation, wherein the initial rolling temperature is 1400 ℃, the final rolling temperature is 1250 ℃, then coiling, and then air cooling to room temperature to obtain the hot rolled steel plate with the thickness of 3 mm.
(2) Pickling and cold rolling the hot-rolled steel plate to prepare a cold-rolled steel plate: and (2) preserving the heat of the hot rolled steel plate obtained in the step (1) at 900 ℃ for 1h, performing solution treatment, then cooling the hot rolled steel plate to room temperature in air, and then cold rolling the hot rolled steel plate to 1.5mm after acid cleaning.
(3) And (3) carrying out Q & P (quenching and partitioning) treatment on the cold-rolled steel plate obtained in the step (2):
(1) placing the cold-rolled medium manganese steel in a muffle furnace, annealing at 750 ℃, and keeping the temperature for 15-60min; and quickly transferring the annealed material to a constant-temperature water bath furnace to quench the annealed material to 25 ℃, keeping the temperature for 90s, and finally performing Water Quenching (WQ) to room temperature.
(2) Placing the cold-rolled medium manganese steel in a muffle furnace, annealing at 680 ℃, and keeping the temperature for 20min; and quickly transferring the annealed material to a salt bath furnace to quench to 150 ℃, keeping the temperature for 60-300s, and finally performing Water Quenching (WQ) to room temperature.
The following chemical compositions were applied to a non-Q sample using a TA instruments thermal expansion phase Change Instrument DIL805&The P heat-treated cold-rolled medium manganese steel is tested, and the chemical components are C:0.1%, mn:7.5%, si:2.0%, al:4.5%, cu:0.5%, mo:0.2%, cr:0.3%, nb:0.11%, sc:0.06%, 0.001% of B, 0.011% (wt%) of Ni, and the balance Fe and inevitable impurities. Austenite transformation start temperature (Ac) of the alloy 1 ) Austenite transformation end temperature (Ac) 3 ) Respectively as follows: a. The C1 =728.4℃，A C3 =1227℃。
The following chemical compositions were applied to a non-Q sample using a TA instruments thermal expansion phase Change Instrument DIL805&The P heat-treated cold-rolled medium manganese steel is tested, and the chemical components are C:0.15%, mn:7.9%, si:1.45%, al:3%, cu:0.51%, mo:0.2%, cr:0.35%, nb:0.11%, sc:0.05%, B:0.001%, ni:0.027%, the balance being Fe and unavoidable impurities. Austenite transformation start temperature (Ac) thereof 1 ) Austenite transformation end temperature (Ac) 3 ) Are respectively provided withComprises the following steps: a. The C1 =660℃，A C3 =1227℃。
The medium manganese steel produced by the invention has the following characteristics:
(1) The medium manganese steel produced by the method has the advantages of high tensile strength, large elongation, high product of strength and elongation, and good matching between strength and ductility, and the formability and the collision absorption capacity of the steel are greatly improved; the elongation of the prepared medium manganese steel is more than or equal to 48 percent, and the product of strength and elongation is more than or equal to 48GPa percent;
(2) The medium manganese steel produced by the invention is observed under a transmission electron microscope to form a multi-shape and multi-scale heterogeneous austenite structure (granular, blocky and lamellar austenite), blocky and lamellar retained austenite; the austenite structure is transformed into irregular orientation, which is not only beneficial to the TRIP effect of residual austenite with different orientations, but also increases the microstructure such as homogeneous lattice distortion, dislocation density and the like of the internal structure, increases the chemical stability of the internal structure, and greatly improves the comprehensive mechanical property of the internal structure; the heterostructure of the steel of the invention conforms to the development trend of advanced high-strength steel, namely 'multiphase, metastable and multi-scale' (M) 3 ) An organization regulation and control thought.
(3) Compared with the traditional medium manganese steel, the steel grade is creatively added with the rare earth element Sc, and the rare earth element Sc greatly influences the structure transformation in the steel by influencing the type, the quantity and the form of a precipitated phase; meanwhile, crystal grains are refined, and the transverse performance and the cold brittleness of the steel are improved; also inhibits the temper brittleness, and improves the thermoplasticity, the heat strength, the fatigue property, the wear resistance and the like of the steel. Meanwhile, cu and NiAl are compositely precipitated, and second phase particles are distributed in a martensite matrix to play a role in dispersion strengthening. Finally, the TRIP effect of metastable austenite is utilized through Q & P treatment to further improve the strength and the plasticity of the steel. The performance is obviously improved while the cost is saved.
Drawings
FIG. 1 is a flow chart of the production process of the present invention;
FIG. 2 is a process flow diagram of examples 1 to 4 of the present invention;
FIG. 3 is a process flow diagram of examples 5-8 of the present invention;
FIG. 4 is a SEM image of example 1 of the present invention;
FIG. 5 is a stress-strain diagram of example 1 of the present invention;
FIG. 6 is a TEM image of example 1 of the present invention;
FIG. 7 is a SEM image of example 2 of the present invention;
FIG. 8 is a stress-strain diagram of example 2 of the present invention;
FIG. 9 is a SEM image of example 3 of the present invention;
FIG. 10 is a stress-strain diagram of example 3 of the present invention;
FIG. 11 is a SEM image of example 4 of the present invention;
FIG. 12 is a stress-strain diagram of example 4 of the present invention;
FIG. 13 is a TEM image of example 4 of the present invention;
FIG. 14 is a SEM image of example 5 of the present invention;
FIG. 15 is a stress-strain diagram of example 5 of the present invention;
FIG. 16 is a SEM image of example 6 of the present invention;
FIG. 17 is a stress-strain diagram of example 6 of the present invention;
FIG. 18 is a SEM image of example 7 of the present invention;
FIG. 19 is a stress-strain diagram of example 7 of the present invention;
FIG. 20 is a SEM image of example 8 of the present invention;
FIG. 21 is a stress-strain diagram of example 8 of the present invention.
Detailed Description
The following detailed description is to be read with reference to the drawings and examples, as illustrated in FIGS. 1-21.
Detailed description of the invention
The scanning electron microscope image in the embodiment of the invention is in SUPRA TM The microstructure picture is obtained by shooting under a type 55 scanning electron microscope, the tensile sample is prepared by using an NSC-M3 wire cutting machine according to the ASTM E8 standard, the tensile sample is subjected to tensile treatment at the tensile rate of 1mm/min by using a WDW-100E type electronic universal testing machine at room temperature, and the tensile strength, the elongation after fracture and the product of strength and elongation of each sample are obtained through testing and calculation.
In addition, the present invention relates to some terms in the heat treatment of iron-carbon alloys, and the terms are explained for the convenience of the skilled person to understand the present invention, but the contents of the explanations do not necessarily constitute the common general knowledge in the art, and specifically include:
the term "martensite": is a supersaturated solid solution formed by dissolving carbon element in alpha-Fe, and is formed after austenite quenching. The martensite obtained after quenching has different forms due to different carbon contents in austenite, generally speaking, lath-shaped martensite is formed after quenching when the carbon content in austenite is less than or equal to 0.25%, and bamboo leaf or convex lens-shaped martensite is formed after quenching when the carbon content is more than the carbon content.
The term "ferrite": is an interstitial solid solution formed by dissolving carbon element in alpha-Fe and has a body-centered cubic unit cell structure.
The term "austenite": is an interstitial solid solution formed by dissolving carbon element in gamma-Fe and has a face-centered cubic unit cell structure.
The terms "austenite transformation start temperature", "A C1 ": refers to the starting temperature of ferrite to austenite transformation upon heating. Above this temperature both ferrite and austenite phases are present in the steel and the complete transformation of ferrite to austenite requires an ever increasing temperature.
The terms "austenite finish temperature", "A C3 ": refers to the end temperature of ferrite to austenite transformation upon heating. When the temperature is exceeded, the transformation of ferrite into austenite in the steel is completed, and ferrite is completely transformed into austenite.
FIG. 1 is a production process diagram of the present invention; FIG. 2 is a process flow diagram of examples 1-4 of the present invention; FIG. 3 is a flow chart of the process of examples 5 to 8 of the present invention; as shown in the figure, the industrial pure iron is smelted in an electric furnace, and after the industrial pure iron is completely melted, the alloy materials with the specific proportion designed by the invention are added in sequence at different time points. Then casting into cast ingot, cooling in air, and refining in a refining furnace to make the distribution of various alloy elements more uniform. Finally obtaining a casting blank. Then forging, heating, hot rolling and coiling the casting blank to obtain a hot rolled steel plate; then coiling, and then air-cooling to room temperature to obtain a hot-rolled steel plate with the thickness of 3 mm; pickling and cold rolling the hot-rolled steel plate to obtain a cold-rolled steel plate: and finally, carrying out Q & P (quenching and partitioning) treatment on the cold-rolled steel plate with different process parameters.
Detailed description of the preferred embodiment 1
The casting blank comprises the following chemical components: 0.1%, mn:7.5%, si:2.0%, al:4.5%, cu:0.5%, mo:0.2%, cr:0.3%, nb:0.11%, sc:0.06%, 0.001% of B, 0.011% (wt%) of Ni, and the balance Fe and inevitable impurities.
(1) Forging and heating the casting blank, hot rolling and coiling to obtain a hot rolled steel plate: forging the casting blank, heating to 1500 ℃ for uniform austenitizing for 1.5h, then carrying out 4-pass hot rolling deformation, wherein the initial rolling temperature is 1400 ℃, the final rolling temperature is 1250 ℃, then coiling, and then air cooling to room temperature to obtain the hot rolled steel plate with the thickness of 3 mm.
(2) Pickling and cold rolling the hot-rolled steel plate to prepare a cold-rolled steel plate: and (2) keeping the temperature of the hot rolled steel plate obtained in the step (1) at 900 ℃ for 1h, performing solution treatment, then air-cooling to room temperature, then pickling, and then cold-rolling to 1.5mm.
(3) And (3) carrying out Q & P (quenching and partitioning) treatment on the cold-rolled steel plate obtained in the step (2): placing the cold-rolled medium manganese steel in a muffle furnace, annealing at 750 ℃ and keeping the temperature for 20min; and quickly transferring the annealed material to a constant-temperature water bath furnace to quench to 25 ℃, keeping the temperature for 90s, and finally performing Water Quenching (WQ) to room temperature.
(4) The microstructure of the medium manganese steel prepared in the example under a scanning electron microscope is shown in FIG. 4, the stress-strain curve is shown in FIG. 5, the microstructure under a transmission electron microscope is shown in FIG. 6, the microstructure is martensite, ferrite and retained austenite, the elongation is 48%, the tensile strength is 1000MP, and the product of strength and elongation is 48GPa%.
Specific example 2
The casting blank comprises the following chemical components: 0.1%, mn:7.5%, si:2.0%, al:4.5%, cu:0.5%, mo:0.2%, cr:0.3%, nb:0.11%, sc:0.06%, 0.001% of B, 0.011% (wt%) of Ni, and the balance Fe and unavoidable impurities.
(1) Forging and heating the casting blank, hot rolling and coiling to obtain a hot rolled steel plate: forging the casting blank, heating to 1500 ℃ for uniform austenitizing for 1.5h, then carrying out 4-pass hot rolling deformation, wherein the initial rolling temperature is 1400 ℃, the final rolling temperature is 1250 ℃, then coiling, and then air cooling to room temperature to obtain the hot rolled steel plate with the thickness of 3 mm.
(2) Pickling and cold rolling the hot-rolled steel plate to prepare a cold-rolled steel plate: and (2) preserving the heat of the hot rolled steel plate obtained in the step (1) at 900 ℃ for 1h, performing solution treatment, then cooling the hot rolled steel plate to room temperature in air, and then cold rolling the hot rolled steel plate to 1.5mm after acid cleaning.
(3) And (3) performing Q & P (quenching and partitioning) treatment on the cold-rolled steel sheet obtained in the step (2): placing the cold-rolled medium manganese steel in a muffle furnace, annealing at 750 ℃ and keeping the temperature for 30min; and quickly transferring the annealed material to a constant-temperature water bath furnace to quench the annealed material to 25 ℃, keeping the temperature for 90s, and finally performing Water Quenching (WQ) to room temperature.
(4) The microstructure of the medium manganese steel prepared in the example under a scanning electron microscope is shown in FIG. 7, the stress-strain curve is shown in FIG. 8, the microstructure is martensite, ferrite and retained austenite, the elongation is 31.28%, the tensile strength is 942MPa, and the product of strength and elongation is 29.47GPa%.
Specific example 3
The casting blank comprises the following chemical components: 0.1%, mn:7.5%, si:2.0%, al:4.5%, cu:0.5%, mo:0.2%, cr:0.3%, nb:0.11%, sc:0.06%, 0.001% of B, 0.011% (wt%) of Ni, and the balance Fe and inevitable impurities.
(1) Forging and heating the casting blank, hot rolling and coiling to obtain a hot rolled steel plate: forging the casting blank, heating to 1500 ℃ for uniform austenitizing for 1.5h, then carrying out 4-pass hot rolling deformation, wherein the initial rolling temperature is 1400 ℃, the final rolling temperature is 1250 ℃, then coiling, and then air cooling to room temperature to obtain the hot rolled steel plate with the thickness of 3 mm.
(2) Pickling and cold rolling the hot-rolled steel plate to prepare a cold-rolled steel plate: and (2) preserving the heat of the hot rolled steel plate obtained in the step (1) at 900 ℃ for 1h, performing solution treatment, then cooling the hot rolled steel plate to room temperature in air, and then cold rolling the hot rolled steel plate to 1.5mm after acid cleaning.
(3) And (3) performing Q & P (quenching and partitioning) treatment on the cold-rolled steel sheet obtained in the step (2): placing the cold-rolled medium manganese steel in a muffle furnace, annealing at 750 ℃ and keeping the temperature for 40min; and quickly transferring the annealed material to a constant-temperature water bath furnace to quench to 25 ℃, keeping the temperature for 90s, and finally performing Water Quenching (WQ) to room temperature.
(4) The microstructure of the medium manganese steel prepared in the embodiment under a scanning electron microscope is shown in fig. 9, the stress-strain curve is shown in fig. 10, the microstructure is martensite, ferrite and retained austenite, the elongation is 37.32% through determination, the tensile strength is 946MPa, and the product of strength and elongation is 35.3GPa%.
Specific example 4
The casting blank comprises the following chemical components: 0.1%, mn:7.5%, si:2.0%, al:4.5%, cu:0.5%, mo:0.2%, cr:0.3%, nb:0.11%, sc:0.06%, 0.001% of B, 0.011% (wt%) of Ni, and the balance Fe and unavoidable impurities.
(1) Forging and heating the casting blank, hot rolling and coiling to obtain a hot rolled steel plate: forging the casting blank, heating to 1500 ℃ for uniform austenitizing for 1.5h, then carrying out 4-pass hot rolling deformation, wherein the initial rolling temperature is 1400 ℃, the final rolling temperature is 1250 ℃, then coiling, and then air cooling to room temperature to obtain the hot rolled steel plate with the thickness of 3 mm.
(2) Pickling and cold rolling the hot-rolled steel plate to prepare a cold-rolled steel plate: and (2) preserving the heat of the hot rolled steel plate obtained in the step (1) at 900 ℃ for 1h, performing solution treatment, then cooling the hot rolled steel plate to room temperature in air, and then cold rolling the hot rolled steel plate to 1.5mm after acid cleaning.
(3) And (3) performing Q & P (quenching and partitioning) treatment on the cold-rolled steel sheet obtained in the step (2): placing the cold-rolled medium manganese steel in a muffle furnace, annealing at 750 ℃ and keeping the temperature for 60min; and quickly transferring the annealed material to a constant-temperature water bath furnace to quench the annealed material to 25 ℃, keeping the temperature for 90s, and finally performing Water Quenching (WQ) to room temperature.
(4) The microstructure of the medium manganese steel prepared in this example under a scanning electron microscope is shown in FIG. 11, the stress-strain curve is shown in FIG. 12, the microstructure under a transmission electron microscope is shown in FIG. 13, the microstructure is martensite, ferrite and retained austenite, the elongation is 43.22%, the tensile strength is 936MPa, and the product of strength and elongation is 40.55GPa%.
Specific example 5
The casting blank comprises the following chemical components: 0.15%, mn:7.9%, si:1.45%, al:3%, cu:0.51%, mo:0.2%, cr:0.35%, nb:0.11%, sc:0.05%, B:0.001%, ni:0.027%, the balance being Fe and unavoidable impurities.
(1) Forging and heating the casting blank, hot rolling and coiling to obtain a hot rolled steel plate: and forging the casting blank, heating to 1500 ℃, uniformly austenitizing for 1.5h, performing 4-pass hot rolling deformation, rolling at the beginning temperature of 1400 ℃ and the final rolling temperature of 1250 ℃, then coiling, and then air-cooling to room temperature to obtain the hot rolled steel plate with the thickness of 3 mm.
(2) Pickling and cold rolling the hot-rolled steel plate to prepare a cold-rolled steel plate: and (2) preserving the heat of the hot rolled steel plate obtained in the step (1) at 900 ℃ for 1h, performing solution treatment, then cooling the hot rolled steel plate to room temperature in air, and then cold rolling the hot rolled steel plate to 1.5mm after acid cleaning.
(3) And (3) performing Q & P (quenching and partitioning) treatment on the cold-rolled steel sheet obtained in the step (2): placing the cold-rolled medium manganese steel in a muffle furnace, annealing at 680 ℃, and keeping the temperature for 20min; and quickly transferring the annealed material to a salt bath furnace to quench to 150 ℃ after annealing, keeping the temperature for 60s, and finally performing Water Quenching (WQ) to room temperature.
(4) The microstructure of the medium manganese steel prepared in the example under a scanning electron microscope is shown in FIG. 14, the stress-strain curve is shown in FIG. 15, the microstructure is martensite, ferrite and retained austenite, the elongation is 29.8%, the tensile strength is 1210MPa, and the product of strength and elongation is 36.06GPa%.
Specific example 6
The casting blank comprises the following chemical components: 0.15%, mn:7.9%, si:1.45%, al:3%, cu:0.51%, mo:0.2%, cr:0.35%, nb:0.11%, sc:0.05%, B:0.001%, ni:0.027%, the balance being Fe and unavoidable impurities.
(1) Forging and heating the casting blank, hot rolling and coiling to obtain a hot rolled steel plate: forging the casting blank, heating to 1500 ℃ for uniform austenitizing for 1.5h, then carrying out 4-pass hot rolling deformation, wherein the initial rolling temperature is 1400 ℃, the final rolling temperature is 1250 ℃, then coiling, and then air cooling to room temperature to obtain the hot rolled steel plate with the thickness of 3 mm.
(2) Pickling and cold rolling the hot-rolled steel plate to prepare a cold-rolled steel plate: and (2) preserving the heat of the hot rolled steel plate obtained in the step (1) at 900 ℃ for 1h, performing solution treatment, then cooling the hot rolled steel plate to room temperature in air, and then cold rolling the hot rolled steel plate to 1.5mm after acid cleaning.
(3) And (3) performing Q & P (quenching and partitioning) treatment on the cold-rolled steel sheet obtained in the step (2): placing the cold-rolled medium manganese steel in a muffle furnace, annealing at 680 ℃, and keeping the temperature for 20min; and quickly transferring the annealed material to a salt bath furnace to be quenched to 150 ℃, keeping the temperature for 90s, and finally performing Water Quenching (WQ) to room temperature.
(4) The microstructure of the medium manganese steel prepared in the example under a scanning electron microscope is shown in FIG. 16, the stress-strain curve is shown in FIG. 17, the microstructure is martensite, ferrite and retained austenite, the elongation is 34.52%, the tensile strength is 1260MPa, and the product of strength and elongation is 43.5GPa%.
Specific example 7
The casting blank comprises the following chemical components: 0.15%, mn:7.9%, si:1.45%, al:3%, cu:0.51%, mo:0.2%, cr:0.35%, nb:0.11%, sc:0.05%, B:0.001%, ni:0.027%, the balance being Fe and unavoidable impurities.
(1) Forging and heating the casting blank, hot rolling and coiling to obtain a hot rolled steel plate: forging the casting blank, heating to 1500 ℃ for uniform austenitizing for 1.5h, then carrying out 4-pass hot rolling deformation, wherein the initial rolling temperature is 1400 ℃, the final rolling temperature is 1250 ℃, then coiling, and then air cooling to room temperature to obtain the hot rolled steel plate with the thickness of 3 mm.
(2) Pickling and cold rolling the hot-rolled steel plate to prepare a cold-rolled steel plate: and (2) keeping the temperature of the hot rolled steel plate obtained in the step (1) at 900 ℃ for 1h, performing solution treatment, then air-cooling to room temperature, then pickling, and then cold-rolling to 1.5mm.
(3) And (3) carrying out Q & P (quenching and partitioning) treatment on the cold-rolled steel plate obtained in the step (2): placing the cold-rolled medium manganese steel in a muffle furnace, annealing at 680 ℃, and keeping the temperature for 20min; and quickly transferring the annealed material to a salt bath furnace to quench the annealed material to 150 ℃, keeping the temperature for 180s, and finally performing Water Quenching (WQ) to room temperature.
(4) The microstructure of the medium manganese steel prepared in the embodiment under a scanning electron microscope is shown in FIG. 18, the stress-strain curve is shown in FIG. 19, the microstructure is martensite, ferrite and retained austenite, the elongation is 31.12% through measurement, the tensile strength is 1210MPa, and the product of strength and elongation is 37.66GPa%.
Specific example 8
The casting blank comprises the following chemical components: 0.15%, mn:7.9%, si:1.45%, al:3%, cu:0.51%, mo:0.2%, cr:0.35%, nb:0.11%, sc:0.05%, B:0.001%, ni:0.027%, the balance being Fe and unavoidable impurities.
(1) Forging and heating the casting blank, hot rolling and coiling to obtain a hot rolled steel plate: forging the casting blank, heating to 1500 ℃ for uniform austenitizing for 1.5h, then carrying out 4-pass hot rolling deformation, wherein the initial rolling temperature is 1400 ℃, the final rolling temperature is 1250 ℃, then coiling, and then air cooling to room temperature to obtain the hot rolled steel plate with the thickness of 3 mm.
(2) Pickling and cold rolling the hot-rolled steel plate to prepare a cold-rolled steel plate: and (2) keeping the temperature of the hot rolled steel plate obtained in the step (1) at 900 ℃ for 1h, performing solution treatment, then air-cooling to room temperature, then pickling, and then cold-rolling to 1.5mm.
(3) And (3) performing Q & P (quenching and partitioning) treatment on the cold-rolled steel sheet obtained in the step (2): placing the cold-rolled medium manganese steel in a muffle furnace, annealing at 680 ℃, and keeping the temperature for 20min; and quickly transferring the annealed material to a salt bath furnace to quench the annealed material to 150 ℃, keeping the temperature for 300s, and finally performing Water Quenching (WQ) to room temperature.
(4) The microstructure of the medium manganese steel prepared in the embodiment under a scanning electron microscope is shown in fig. 20, the stress-strain curve is shown in fig. 21, the microstructure is martensite, ferrite and retained austenite, the elongation is 28.2% by measurement, the tensile strength is 1220MPa, and the product of strength and elongation is 34.4 GPa.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made without departing from the spirit and principle of the present invention shall fall within the protection scope of the present invention.
Claims (1)
1. A method for designing and preparing a 48GPa% strength-elongation medium manganese steel component is characterized in that the medium manganese steel comprises the following chemical components in percentage by mass: 0.1% -0.15%, mn:7.5% -7.9%, si:1.45% -2%, al:3% -4.5%, cu:0.5% -0.51%, mo:0.2%, cr:0.3% -0.35%, nb:0.11%, sc:0.05% -0.06%, B:0.001%, ni:0.011% -0.027%, and the balance of Fe and inevitable impurities; the components are proportioned and smelted in a converter, secondary refining is carried out in a vacuum furnace to obtain a casting blank, and the specific preparation method comprises the following steps:
(1) Forging and heating the casting blank, hot rolling and coiling to obtain a hot rolled steel plate: forging a casting blank, heating to 1500 ℃, uniformly austenitizing for 1.5h, then performing 4-pass hot rolling deformation, wherein the initial rolling temperature is 1400 ℃, the final rolling temperature is 1250 ℃, then coiling, and then air-cooling to room temperature to obtain a hot-rolled steel plate with the thickness of 3 mm;
(2) Pickling and cold rolling the hot-rolled steel plate to prepare a cold-rolled steel plate: preserving the heat of the hot rolled steel plate obtained in the step (1) at 900 ℃ for 1h, performing solution treatment, then air-cooling to room temperature, then pickling, and then cold-rolling to 1.5mm;
(3) And (3) performing Q & P (quenching and partitioning) treatment on the cold-rolled steel sheet obtained in the step (2):
(1) placing the cold-rolled medium manganese steel in a muffle furnace, annealing at 750 ℃ and keeping the temperature for 20-60 min; quickly transferring the annealed material to a constant-temperature water bath furnace to quench to 25 ℃ after annealing, keeping the temperature for 90s, and finally carrying out Water Quenching (WQ) to room temperature;
(2) placing the cold-rolled medium manganese steel in a muffle furnace, annealing at 680 ℃, and keeping the temperature for 20min; and quickly transferring the annealed material to a salt bath furnace to quench the annealed material to 150 ℃, keeping the temperature for 60-300s, and finally performing Water Quenching (WQ) to room temperature.
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