A kind of high-strength and high-toughness lightweight steel in a wide temperature range and preparation method thereof

Abstract

The present invention belongs to the technical field of lightweight materials for extreme environments, and specifically discloses a high-strength and high-toughness lightweight steel under a wide temperature range and a preparation method thereof, wherein the chemical composition weight percentage of the lightweight steel is: C is 0.2% to 0.5%, Mn is 25% to 30%, Al is 10% to 15%, V is 0.1% to 1%, W is 0.1% to 1%, and on this basis, the following elements with a content of 0.005% to 0.1% are added: Si, Cr, Ni, Cu, Mo, N, and the balance is Fe. The high-strength and high-toughness lightweight steel under a wide temperature range of the present invention first uses hot forging, solid solution and rolling deformation to refine the austenite structure and fibrous ferrite distribution, and then obtains an equiaxed and layered austenite structure with high work hardening ability through short-time annealing, so as to achieve high strength and high toughness at room temperature, and at the same time has excellent ultra-low temperature deformation ability and good medium temperature performance, so that the service temperature range spans ultra-low temperature (-196°C) to medium temperature (450°C-650°C). It solves the problem that traditional metal materials are limited in extreme environment engineering, aviation equipment, and deep space exploration due to their small service temperature range and low specific strength and plasticity.

Description

Technical Field

[0001] The present invention relates to the technical field of lightweight steel, and in particular to a lightweight steel with high strength and toughness in a wide temperature range and a preparation method thereof. Background Art

[0002] As a key structural material in the future fields of aerospace, rail transit, shipbuilding and ocean, lightweight steel has the characteristics of low density, high toughness, and high formability. It is mainly used in automobile shells, aerospace equipment parts and other fields. Traditional lightweight steels, such as austenite, ferrite, austenite-ferrite dual-phase lightweight steel, etc., although the density is significantly reduced and the toughness is good, the yield strength and tensile strength are difficult to exceed 1000MPa. For example, the Fe-Mn-Al-C lightweight steel disclosed in the Chinese patent publication number: CN202110726399.1 "A 780MPa grade high-strength and plastic product Fe-Mn-Al-C lightweight steel and its preparation method" has a yield strength of only 580MPa, a tensile strength of 780MPa, and an elongation of about 50%. The plasticity and toughness meet engineering applications, but the strength is relatively low, which limits the engineering application of lightweight steel in high-load-bearing structural parts.

[0003] Key technical fields such as aerospace, satellites and ships have a great demand for lightweight structural materials that can adapt to temperature alternating environments, such as deep space probes, satellites, and aircraft heat exchangers. Among them, deep space probes must withstand extreme alternating environments with a temperature difference of 200 to 300°C between day and night during their service on the surface of the moon and Mars, while traditional low-temperature steels, high-temperature alloys, aluminum, and titanium alloys cannot have reliable comprehensive performance over a wide temperature range. For example, the maraging steel disclosed in the Chinese patent publication number: CN202211276286.7 "A high-strength and high-toughness maraging stainless steel for ultra-low temperature engineering and its manufacturing method" has a room temperature tensile strength of 1017MPa, a total elongation of 15.5% at room temperature, and good low-temperature toughness, but it is difficult to meet the service requirements of a wide temperature range, and ~10% of precious metals are used, which limits industrial production.

[0004] With the development of the aerospace industry, higher requirements are placed on the extreme environmental performance of lightweight structural materials. It is necessary to develop lightweight structural materials that have high strength and toughness over a wide temperature range to meet the strategic needs of deep space exploration and hypersonic aircraft. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a high-strength, high-toughness, lightweight steel under a wide temperature range and a preparation method thereof. The multi-level structure of fibrous ferrite and layered austenite embedded in an equiaxed austenite / ferrite dual-phase matrix is ​​regulated by rolling and annealing processes. The high-strength, high-toughness, lightweight steel first uses hot forging, solid solution and rolling deformation to refine the austenite structure and fibrous ferrite distribution, and then obtains an equiaxed and layered austenite structure with high work hardening ability through short-time annealing to achieve high strength and high toughness at room temperature, while having excellent ultra-low temperature deformation ability and good medium temperature performance, so that the serviceable temperature range spans ultra-low temperature (-196°C) to medium temperature (450°C-650°C). It solves the problem that the traditional materials mentioned in the above background technology are limited in engineering application because they cannot have both performance under a wide temperature range, and provides an effective preparation process for high-strength, high-toughness, lightweight materials used in extreme environments.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a high-strength and high-toughness lightweight steel in a wide temperature range, wherein the chemical composition of the lightweight steel includes, by weight percentage: C is 0.2% to 0.5%, Mn is 25% to 30%, Al is 10% to 15%, V is 0.1% to 1%, W is 0.1% to 1%, and on this basis, the following elements are added with a content of 0.005% to 0.1%: Si, Cr, Ni, Cu, Mo, N, and the balance is Fe. Among them, Al is a lightweight element, and adding 10% to 15% of Al can significantly reduce the material density. At the same time, a higher content of Mn elements can expand the austenite phase region, forming a stable austenite-ferrite dual-phase structure, ensuring that the material has good toughness.

[0007] Preferably, the wide temperature range high-strength and high-toughness lightweight steel is based on an equiaxed austenite / ferrite dual-phase structure, embedded with layered austenite and fibrous ferrite; the ferrite (α) content in the lightweight alloy steel is 5% to 40%, and the austenite (γ) content is 60% to 95%; the characteristic grain size of the austenite / ferrite dual-phase structure matrix is ​​200nm to 2μm, the characteristic grain size of the layered austenite is 2μm to 15μm, the average length of the fibrous ferrite is 50μm to 150μm, and the average width is 0.8μm to 5μm; the long axis direction of the layered austenite and the fibrous ferrite is consistent.

[0008] The present invention obtains a high-strength and high-toughness lightweight steel in a wide temperature range through process optimization, and the structure is an equiaxed austenite / ferrite dual-phase matrix, fibrous distributed ferrite and lamellar distributed austenite. Among them, under room temperature deformation, the austenite / ferrite dual-phase matrix has good deformation ability, and fine grain strengthening can effectively improve the strength of the material. The high dislocation storage capacity of fibrous distributed ferrite and lamellar distributed austenite can have a toughening effect. Under ultra-low temperature deformation, the critical shear stress of starting dislocations is significantly improved, and the strength is greatly improved while maintaining its plasticity unchanged. Under medium temperature deformation, the microstructure of the material remains stable, and dislocation plane slip is still the dominant plastic deformation mechanism. Therefore, compared with traditional low-temperature and medium-temperature lightweight alloys, the high-strength and high-toughness lightweight steel in a wide temperature range can maintain excellent comprehensive mechanical properties under a variety of extreme temperature environments.

[0009] On the other hand, in order to achieve the above-mentioned purpose, the present invention also provides the following technical solution: a method for preparing high-strength, high-toughness and lightweight steel in a wide temperature range, comprising the following steps:

[0010] Step 1: Accurately weigh the twelve element raw materials of Fe, Mn, Al, C, V, W, Si, Cr, Ni, Cu, Mo, and N according to the predetermined proportion, then melt the raw materials in a high-frequency vacuum induction melting furnace, mix them evenly, and cast them into a mold to form a steel ingot.

[0011] Step 2: The initial steel ingot is subjected to high temperature forging processing, i.e., reheating - heat preservation - cooling - hot forging to form a bar;

[0012] Step 3: Sampling and solution treating the bar sampled and plated after the high temperature forging process in step 2;

[0013] Step 4: performing room temperature rolling treatment on the plate (steel plate) subjected to the solution treatment in step 3;

[0014] Step 5: After the plate (steel plate) subjected to room temperature rolling treatment in step 4 is subjected to a short-time annealing treatment, a high-strength, tough and lightweight steel is obtained.

[0015] Preferably, the steel ingot in step 2 is reheated to 1200° C., kept at this temperature for 3 h, hot forged into a rod with a diameter of 16-24 mm at 950-1150° C., and finally water-cooled to room temperature.

[0016] Preferably, the solution treatment in step 3 is performed by sampling plates from hot forged bars, the sampling thickness is 1.5 mm to 10 mm, the solution temperature range is 950° C. to 1150° C., the solution holding time range is 1 h to 8 h, and the cooling method is water cooling.

[0017] Preferably, in step 4, the steel plate with a thickness of 1 mm is obtained by the room temperature rolling treatment, the rolling reduction in each pass is less than 5%, and the total cumulative rolling reduction is about 30-90%.

[0018] Preferably, the short-time annealing temperature in step 5 is in the range of 800° C. to 1000° C., the holding time is in the range of 30 to 300 seconds, and the cooling method is water cooling to room temperature.

[0019] Preferably, the high-strength, high-toughness and lightweight steel prepared by the present invention in a wide temperature range has the following mechanical characteristics: room temperature yield strength is 600MPa-1200MPa, tensile strength is 900MPa-1300MPa, uniform elongation is 20%-50%, and elongation at break is close to 30%-60%. Ultra-low temperature (77K) yield strength is 1200MPa-1800MPa, tensile strength is 1500-2000MPa, uniform elongation is 20%-50%, and elongation at break is 30%-50%. Medium temperature (723K) yield strength is 400MPa-800MPa, tensile strength is 600MPa-900MPa, uniform elongation is 30%-50%, and elongation at break is 40%-60%.

[0020] Preferably, the high-strength, high-toughness and lightweight steel prepared by the present invention in a wide temperature range has the following mechanical characteristics: room temperature yield strength is 900MPa-1200MPa, tensile strength is 1000MPa-1300MPa, uniform elongation is 20%-35%, and elongation at break is close to 30%-50%. Ultra-low temperature (77K) yield strength is 1600MPa-1800MPa, tensile strength is 1500-2000MPa, uniform elongation is 20%-25%, and elongation at break is 30%-50%. Medium temperature (723K) yield strength is 600MPa-800MPa, tensile strength is 700MPa-900MPa, uniform elongation is 30%-40%, and elongation at break is 40%-60%.

[0021] The high-strength, high-toughness, lightweight steel in a wide temperature range has high strength and excellent plasticity at ultra-low temperature, room temperature, and medium temperature. The reason is that after high-temperature forging, solid solution and rolling treatment, a deformation structure of high-density dislocation ferrite and austenite is obtained, which has high strength but poor plasticity. After a short annealing, the deformed structure is restored and recrystallized into an equiaxed matrix and layered austenite, as well as fibrous ferrite. The strength is slightly reduced, but the elongation is effectively improved, thereby achieving the purpose of high strength and high toughness.

[0022] The present invention proposes to obtain excellent properties of high strength and high toughness in a wide temperature range by rolling and critical annealing lightweight steel. This material component design and mechanical property control idea will help realize the manufacturing and engineering application of a new generation of high-performance lightweight steel for service in extreme environments.

[0023] The beneficial effects of the present invention are:

[0024] 1) The present invention obtains, through composition design and rolling annealing treatment: a high-strength, high-toughness, lightweight steel with continuous work hardening capability at ultra-low temperature, room temperature and medium temperature, and achieves a fracture plasticity of about 40%.

[0025] 2) The present invention prepares high-strength and high-toughness lightweight steel in a wide temperature range through reasonable composition design and simple rolling annealing process. The processing technology is simple and convenient, and the disadvantages of high price and high density of traditional medium-temperature alloys and low-temperature metal materials can be avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of tensile engineering stress-strain curve of high-strength, high-toughness and lightweight steel prepared in Example 1 under a wide temperature range;

[0027] Figure 2 Schematic diagram of the optical microstructure of the high-strength and high-toughness lightweight alloy steel in a wide temperature range prepared in Example 1;

[0028] Figure 3 Schematic diagram of tensile engineering stress-strain curve of high-strength and high-toughness lightweight alloy steel prepared in Example 2 under wide temperature range;

[0029] Figure 4 Schematic diagram of the optical microstructure of the high-strength and high-toughness lightweight alloy steel in a wide temperature range prepared in Example 2;

[0030] Figure 5 Schematic diagram of tensile engineering stress-strain curve of high-strength and high-toughness lightweight alloy steel in a wide temperature range prepared in Example 3;

[0031] Figure 6 This is a schematic diagram of the optical microstructure photograph of the high-strength and high-toughness lightweight alloy steel under a wide temperature range prepared in Example 3. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Example 1

[0034] Step 1: First, accurately weigh the twelve elements of Fe, Mn, Al, C, V, W, Si, Cr, Ni, Cu, Mo, and N according to the predetermined proportion, then melt the raw materials in a high-frequency vacuum induction melting furnace, mix them evenly, and then cast them into a mold to form a steel ingot;

[0035] The chemical element composition and weight proportion of the embodiment are: C is 0.3%, Mn is 25%, Al is 11%, V is 0.5%, W is 0.5%, Si is 0.02%, Cr and Ni are 0.08%, Cu is 0.03%, N is 0.01%, Mo is 0.005%, and the balance is Fe.

[0036] The diameter of the steel ingot in step 1 is 80-120 mm.

[0037] Step 2: reheating the steel ingot in step 1 - keeping warm - cooling - hot forging;

[0038] In step 2, the steel ingot is reheated to 1200° C., kept at this temperature for 3 hours, cooled to 950-1150° C., and then directly hot-forged into a rod with a diameter of 16-24 mm, and finally water-cooled to room temperature.

[0039] Step 3: Take the plate from the bar in step 2 and perform solution treatment;

[0040] From step 2, an initial steel plate with a thickness of 1.5 mm was selected for solution treatment, the solution temperature was 1050°C, the holding time was 2 h, and the cooling method was water cooling.

[0041] Step 4: performing room temperature rolling treatment on the solution treated plate obtained in step 3;

[0042] The steel plate obtained in step 3 is subjected to room temperature rolling treatment to obtain a steel plate with a thickness of about 1 mm, the rolling reduction in each pass is less than 5%, and the total cumulative rolling reduction is about 30%.

[0043] Step 5: performing a short-time annealing treatment on the rolled steel plate obtained in step 4 to obtain a high-strength, high-toughness and lightweight steel in a wide temperature range;

[0044] The steel plate with a thickness of 1 mm obtained in step 4 was short-term annealed in a box furnace at a temperature of 900° C. for 2 min, and then water-cooled to room temperature.

[0045] Figure 1 The figure below shows the engineering stress-strain curve of Example 1 along the rolling direction under a wide temperature range. Its ultra-low temperature mechanical characteristics are: yield strength of 1251MPa, tensile strength of 1623MPa, uniform elongation of 47.0%, and elongation at break of 52.6%; room temperature mechanical characteristics are: yield strength of 637MPa, tensile strength of 968MPa, uniform elongation of 46.8%, and elongation at break of 59.7%; medium temperature mechanical properties are: yield strength of 450MPa, tensile strength of 676MPa, uniform elongation of 48.3%, and elongation at break of 57.2%. The optical microstructure photos of the prepared high-strength, high-toughness, lightweight steel (Example 1) under a wide temperature range are shown in Figure 1. Figure 2As shown in Figure 1, ferrite is distributed in a fibrous shape, and austenite grains are distributed in an equiaxed shape. This structure can usually coordinate deformation to obtain high strength and toughness.

[0046] Example 2

[0047] Step 1: First, accurately weigh the twelve elements of Fe, Mn, Al, C, V, W, Si, Cr, Ni, Cu, Mo, and N according to the predetermined proportion, then melt the raw materials in a high-frequency vacuum induction melting furnace, mix them evenly, and then cast them into a mold to form a steel ingot;

[0048] The chemical element composition and weight proportion of the embodiment are: C is 0.4%, Mn is 25%, Al is 11%, V is 0.5%, W is 0.5%, Si is 0.02%, Cr and Ni are 0.08%, Cu is 0.03%, N is 0.01%, Mo is 0.005%, and the balance is Fe.

[0049] The diameter of the steel ingot in step 1 is 80-120 mm.

[0050] Step 2: reheating the steel ingot in step 1 - keeping warm - cooling - hot forging;

[0051] In step 2, the steel ingot is reheated to 1200° C., kept at this temperature for 3 hours, cooled to 950-1150° C., and then directly hot-forged into a rod with a diameter of 16-24 mm, and finally water-cooled to room temperature.

[0052] Step 3: Take the plate from the bar in step 2 and perform solution treatment;

[0053] From step 2, an initial steel plate with a thickness of 2.5 mm was selected for solution treatment. The solution temperature was 1050° C., the holding time was 2 h, and the cooling method was water cooling.

[0054] Step 4: performing room temperature rolling treatment on the solution treated plate obtained in step 3;

[0055] The steel plate obtained in step 3 is subjected to room temperature rolling treatment to obtain a steel plate with a thickness of 1 mm, the rolling reduction in each pass is less than 5%, and the total cumulative rolling reduction is about 60%.

[0056] Step 5: performing a short-time annealing treatment on the rolled steel plate obtained in step 4 to obtain a high-strength, high-toughness and lightweight steel in a wide temperature range;

[0057] The steel plate with a thickness of 1 mm obtained in step 4 was short-term annealed in a box furnace at a temperature of 900° C. for 2 min, and then water-cooled to room temperature.

[0058] Figure 3The figure below shows the engineering stress-strain curve of Example 2 along the rolling direction under a wide temperature range. Its ultra-low temperature mechanical characteristics are: yield strength of 1345MPa, tensile strength of 1703MPa, uniform elongation of 38.3%, and elongation at break of 44.4%; room temperature mechanical characteristics are: yield strength of 722MPa, tensile strength of 1059MPa, uniform elongation of 39.0%, and elongation at break of 48.5%; medium temperature mechanical properties are: yield strength of 521MPa, tensile strength of 733MPa, uniform elongation of 40.6%, and elongation at break of 51.5%. The optical microstructure photos of the prepared high-strength, high-toughness, lightweight steel (Example 2) under a wide temperature range are shown in Figure 2. Figure 4 As shown in the figure, the ferrite is distributed in a fiber shape of hundreds of microns, the austenite grains are distributed in an equiaxed shape, and the grain size is smaller than that of Example 1. This structure can obtain high strength and toughness through coordinated deformation.

[0059] Example 3

[0060] Step 1: First, accurately weigh the twelve elements of Fe, Mn, Al, C, V, W, Si, Cr, Ni, Cu, Mo, and N according to the predetermined proportion, then melt the raw materials in a high-frequency vacuum induction melting furnace, mix them evenly, and then cast them into a mold to form a steel ingot;

[0061] The chemical element composition and weight proportion of the embodiment are: C is 0.3%, Mn is 26%, Al is 11%, V is 0.5%, W is 0.5%, Si is 0.02%, Cr and Ni are 0.08%, Cu is 0.03%, N is 0.01%, Mo is 0.005%, and the balance is Fe.

[0062] The diameter of the steel ingot in step 1 is 80-120 mm.

[0063] Step 2: reheating the steel ingot in step 1 - keeping warm - cooling - hot forging;

[0064] In step 2, the steel ingot is reheated to 1200° C., kept at this temperature for 3 hours, cooled to 950-1150° C., and then directly hot-forged into a rod with a diameter of 16-24 mm, and finally water-cooled to room temperature.

[0065] Step 3: Take the plate from the bar in step 2 and perform solution treatment;

[0066] From step 2, an initial steel plate with a thickness of 10 mm was selected for solution treatment, the solution temperature was 1050°C, the holding time was 2 h, and the cooling method was water cooling.

[0067] Step 4: performing room temperature rolling treatment on the solution treated plate obtained in step 3;

[0068] The steel plate obtained in step 3 is subjected to room temperature rolling treatment to obtain a steel plate with a thickness of 1 mm, the rolling reduction in each pass is less than 5%, and the total cumulative rolling reduction is about 90%.

[0069] Step 5: performing a short-time annealing treatment on the rolled steel plate obtained in step 4 to obtain a high-strength, high-toughness and lightweight steel in a wide temperature range;

[0070] The steel plate with a thickness of 1 mm obtained in step 4 was short-term annealed in a box furnace at a temperature of 900° C. for 2 min, and then water-cooled to room temperature.

[0071] See also Figure 5 , Figure 5 The solid line in the figure is the engineering stress-strain curve of Example 3 along the rolling direction under a wide temperature range. Its ultra-low temperature mechanical characteristics are: yield strength of 1677MPa, tensile strength of 1887MPa, uniform elongation of 29.0%, and elongation at break of 38.1%; room temperature mechanical characteristics are: yield strength of 1065MPa, tensile strength of 1215MPa, uniform elongation of 27.5%, and elongation at break of 40.1%; medium temperature mechanical properties are: yield strength of 715MPa, tensile strength of 831MPa, uniform elongation of 33.1%, and elongation at break of 49.0%. The microstructure photos of the prepared high-strength, high-toughness, lightweight steel (Example 3) under a wide temperature range are shown in FIG. Figure 6 As shown in the figure, the microstructure is based on an equiaxed austenite / ferrite dual-phase structure, with layered austenite and fibrous ferrite embedded, and has a more significant fine grain strengthening effect than that of Examples 1 and 2. This structure can achieve high strength and toughness at variable temperatures through the synergistic interaction between ferrite and austenite.

[0072] The mechanical properties of the high-strength, high-toughness and lightweight steel in a wide temperature range in Examples 1-3 are shown in Table 1.

[0073] Table 1 Mechanical properties of high-strength, high-toughness and lightweight steel in wide temperature range of Examples 1-3

[0074]

[0075] The high-strength, high-toughness and lightweight steel of the present invention has high strength and high plasticity in a wide temperature range, and constructs an equiaxed austenite / ferrite dual-phase matrix, fibrous distributed ferrite and layered distributed austenite through rolling and annealing processes. The deformation mechanism dominated by plane slip can play an important role in achieving high strength and high toughness in a wide temperature range. In addition, the addition of elements V and W can effectively improve medium-temperature stability. The method of the present invention solves the problem that traditional steels, high-temperature alloys, medium-entropy and high-entropy alloys are limited in engineering application due to their inability to have both strength and plasticity in a wide temperature range and their high density, providing more possibilities for the service scenarios of metal materials.

[0076] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-strength, high-toughness and lightweight steel in a wide temperature range, characterized in that: The chemical composition of the light alloy steel includes, by weight percentage, 0.2% to 0.5% C, 25% to 30% Mn, 10% to 15% Al, 0.1% to 1% V, 0.1% to 1% W, 0.005% to 0.1% Si, 0.005% to 0.1% Cr, 0.005% to 0.1% Ni, 0.005% to 0.1% Cu, 0.005% to 0.1% Mo, 0.005% to 0.1% N, and the balance is Fe; The high-strength and high-toughness lightweight steel in a wide temperature range is based on an equiaxed austenite / ferrite dual-phase structure, embedded with lamellar austenite and fibrous ferrite; the ferrite content in the lightweight alloy steel is 5% to 40%, and the austenite content is 60% to 95%; the long axis directions of the lamellar austenite and the fibrous ferrite are consistent; The room temperature yield strength of the lightweight steel is 600 MPa~1200 MPa, the tensile strength is 900 MPa~1300 MPa, the uniform elongation is 20%~50%, and the elongation at break is 30%~60%; the yield strength of the lightweight steel at a temperature of -196°C is 1200MPa~1800MPa, the tensile strength is 1500-2000MPa, the uniform elongation is 20%~50%, and the elongation at break is 30%~50%; the yield strength of the lightweight steel at a temperature of 450°C-650°C is 400MPa~800MPa, the tensile strength is 600MPa~900MPa, the uniform elongation is 30%~50%, and the elongation at break is 40%~60%.

2. A method for preparing high-strength, high-toughness and lightweight steel in a wide temperature range according to claim 1, characterized in that: The steps include: Step 1: weigh twelve elements including Fe, Mn, Al, C, V, W, Si, Cr, Ni, Cu, Mo and N, and melt the raw materials into steel ingots; Step 2: reheating the steel ingot described in step 1, keeping it warm, cooling it down, and hot forging it into a bar; Step 3: Sample plates from the bars in step 2 for solution treatment; Step 4: performing room temperature rolling treatment on the plate after the solution treatment in step 3; Step 5: performing a short-time annealing treatment on the plate after the room temperature rolling treatment in step 4 to obtain a high-strength and light-weight steel; The steel ingot in step 2 is reheated to 1200°C, kept at this temperature for 3 hours, hot forged at 950-1150°C into a bar with a diameter of 16-24 mm, and finally water-cooled to room temperature; The solution treatment in step 3 is performed by sampling from the rod, the sampling thickness is 1.5 mm to 10 mm, the solution temperature is 950 to 1150°C, the holding time is 1 to 8 h, and the cooling method is water cooling; The short-time annealing temperature in step 5 is in the range of 800-1000° C., the annealing time is 30-300 s, and the annealing is performed by water cooling to room temperature.

3. The method for preparing high-strength, high-toughness and lightweight steel in a wide temperature range according to claim 2, characterized in that: In step 4, the steel plate with a thickness of 1 mm is obtained by room temperature rolling treatment, the reduction amount of each pass is less than 5%, and the total cumulative reduction amount is 30-90%.

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