A double heterogeneous structure high-strength plasticity low-density steel and its preparation method

Abstract

The present invention belongs to the technical field of metal material design and preparation, and specifically relates to a double heterogeneous structure high-strength plasticity low-density steel and a preparation method thereof. The double heterogeneous structure high-strength plasticity low-density steel proposed in the present invention includes the addition of a large amount of Al elements, which can greatly reduce the material density, and introduces the non-shearable NiAl type B2 phase through Ni alloying, and forms a double heterogeneous structure through multiple rolling and annealing processes. The double heterogeneous structure low-density steel can have higher strength, greater plasticity and higher work hardening rate at a lower density. And the addition of Al and Ni elements can greatly improve the corrosion resistance of steel materials, and the preparation method is simple and economical, and can realize large-scale industrial production. The research and development and application of the finished steel have important economic value and social significance for promoting lightweight material design, improving strength and plasticity, reducing energy consumption, and reducing greenhouse gas emissions.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal material design and preparation, and specifically relates to a double heterogeneous structure high-strength plasticity low-density steel and a preparation method thereof. Background Art

[0002] In order to achieve lightweight design in the fields of marine engineering, automobiles, and national defense, the lightweight and high service performance of steel structural materials are increasingly valued. Lightweight can be achieved through light metal materials such as aluminum, magnesium, and titanium, or by reducing the density of steel materials, while high service performance requires high strength and plasticity to avoid catastrophic accidents caused by low strength of parts during collision. Since magnesium, aluminum, and titanium alloy materials have low densities, they are conducive to lightweighting, but the materials have low strength, high prices, and are difficult to recycle, which results in significant restrictions on their scope and area of ​​use in practical applications. Therefore, the research and development of high-strength, plastic, and low-density steels is particularly important.

[0003] High manganese and high aluminum low-density steel has attracted widespread attention due to its good mechanical properties, low density and relatively low cost. It has become a new type of structural material with broad application prospects in the automotive industry, marine engineering, national defense and military industries. In order to obtain a lower density, a large amount of Al needs to be added. Adding 8-11wt.% Al will reduce the density by 11.7-14.3%. However, with the increase of Al content, coarse κ-carbide or B2 phase is easily formed, which greatly reduces the strength, plasticity and work hardening ability of steel, becoming a bottleneck for engineering applications. Studies have shown that introducing heterogeneous structures is one of the most effective ways to achieve an ideal combination of high strength and high plasticity. However, there is currently a lack of relevant research on heterogeneous low-density steel.

[0004] CN 113278896A patent discloses a Fe-Mn-Al-C series high-strength low-density steel and its preparation method. The composition is C1.0-2.0%, Mn 20-40%, Al 10-14%, 2%≤Ni+Cr≤15%, and the balance is Fe. Through steel smelting, solidification casting, hot working and solution treatment, a uniformly organized austenite-based high-strength low-density steel is finally obtained, wherein the better performance combination is a yield strength of 1050MPa, a tensile strength of 1087MPa, and an elongation of only 33.2%. Because the scheme improves the strength by precipitating the B2 phase, but does not fully regulate the morphology of the B2 phase, the coarse B2 phase will greatly reduce the strength and plasticity.

[0005] CN 114480984B patent discloses a Ti alloyed low-density high-strength steel and a preparation method thereof, the composition of which is: 4.5% ≥ C ≥ 1%, 35% ≥ Mn ≥ 25%, 12% ≥ Al ≥ 8%, 10% ≥ Ti ≥ 1%, the remainder being Fe and unavoidable impurities, on which Mo ≤ 5%, V ≤ 5%, Nb ≤ 0.5%, and rare earth microalloying elements are added, and through smelting, forging and solid solution treatment, by utilizing the regulation of TiC precipitation phase and the grain refinement effect, an austenite-based low-density steel is obtained, with a density of ≤ 6.6 g / cm3 and a tensile strength of ≥ 1000 MPa, but the plasticity of the low-density steel is poor, the elongation is less than 30%, and the prices of Ti and rare earth microalloying elements are relatively expensive, which increases the cost. Summary of the invention

[0006] The present invention provides a double heterogeneous structure high-strength plasticity low-density steel and a preparation method thereof, so as to solve the problem in the prior art that there is a lack of a low-density steel that meets the strength and plasticity standards while ensuring low cost.

[0007] To achieve the above object, the present invention proposes the following technical solutions:

[0008] A double heterogeneous structure high-strength plasticity low-density steel, the low-density steel comprises the following element components in percentage by mass: C 0.7-1.2wt.%, Mn 14-35wt.%, Al 8-14wt.%, Ni 3-7wt.%, and the rest is Fe and unavoidable impurities.

[0009] Preferably, the low-density steel further comprises: V 0-3wt.%, Nb 0-3wt.%, Ti 0-3wt.%, Mo 0-3wt.%.

[0010] Preferably, the grain sizes of austenite and B2 phase of the low-density steel are bimodal in distribution.

[0011] Preferably, the yield strength of the low-density steel is 800-1200 MPa, the tensile strength is 1100-1400 MPa, the elongation is 30-50%, the strength-plasticity product is 40-60 GPa%, and the density is 6.1-6.9 g / cm 3 .

[0012] A method for preparing double heterogeneous structure high-strength ductility low-density steel comprises the following steps:

[0013] Step 1, material preparation: selecting alloy raw materials according to the chemical composition ratio of the double heterogeneous structure high-strength plasticity low-density steel, melting the alloy raw materials, and casting them into ingots;

[0014] Step 2, hot rolling: hot rolling the ingot at 1200-900° C. for multiple passes to obtain a hot-rolled sample;

[0015] Step 3, cold rolling: performing multiple passes of rolling on the hot-rolled sample after heat preservation to obtain a cold-rolled steel sheet;

[0016] Step 4, cold rolling after annealing; the cold-rolled steel sheet is kept warm, cooled to room temperature, and then rolled for multiple passes to obtain a secondary cold-rolled steel sheet;

[0017] Step 5, after heat preservation, the secondary cold-rolled steel plate is cooled to room temperature to obtain a finished product of a double heterogeneous structure high-strength plasticity and low-density steel.

[0018] Preferably, the temperature of the heat preservation treatment in step 3 is 1180±80°C, and the heat preservation time is 2-10h.

[0019] Preferably, the rolling operation in step 3 is cold rolling, the rolling multi-pass rolling is 3-4 passes, and the total rolling reduction is ≥50%.

[0020] Preferably, the insulation temperature in step 4 is 900-1100° C. and the time is 10-60 min.

[0021] Preferably, the rolling in step 4 is cold rolling, the cold rolling multi-pass rolling is 5-6 passes, and the total rolling reduction is ≥60%.

[0022] Preferably, the insulation temperature in step 5 is 900-1100° C., and the insulation time is 3-60 min.

[0023] The present invention is beneficial in that:

[0024] The present invention proposes a double heterogeneous structure high-strength plasticity low-density steel, wherein the addition of a large amount of Al elements can greatly reduce the material density, and introduce the non-shearable NiAl type B2 phase through Ni alloying, and form a double heterogeneous structure through multiple rolling and annealing processes. The double heterogeneous structure low-density steel can still have high strength, large plasticity and high work hardening rate at a lower density. And the addition of Al and Ni elements can greatly improve the corrosion resistance of steel materials.

[0025] The present invention proposes a method for preparing a double heterogeneous structure low-density steel, which has a simple and economical process and can realize large-scale industrial production. The research and development and application of the finished steel have important economic value and social significance for promoting lightweight design of materials, improving strength and plasticity, reducing energy consumption, and reducing greenhouse gas emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0027] Figure 1 The present invention is a flow chart of a method for preparing a double heterogeneous structure high-strength ductility low-density steel;

[0028] Figure 2 The SEM and corresponding EBSD images of the double heterogeneous structure low-density steel of Example 1 of the present invention;

[0029] Figure 3 The SEM and corresponding EBSD images of the double heterogeneous structure low-density steel of Example 2 of the present invention;

[0030] Figure 4 The SEM and corresponding EBSD images of the double heterogeneous structure low-density steel of Example 3 of the present invention;

[0031] Figure 5 The SEM and corresponding EBSD images of the double heterogeneous structure low-density steel of Example 4 of the present invention;

[0032] Figure 6 The engineering stress-strain curves of the double heterogeneous structure low-density steels of Examples 1-4 of the present invention subjected to uniaxial tension at room temperature are shown. DETAILED DESCRIPTION

[0033] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0034] The following detailed description is an exemplary description, which is intended to provide further detailed description of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. The terms used in the present invention are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present invention.

[0035] The present invention provides a double heterogeneous structure high-strength plastic low-density steel, comprising the following element components in percentage by mass: C 0.7-1.2wt.%, Mn 14-35wt.%, Al 8-14wt.%, Ni 3-7wt.%; on this basis, V 0-3wt.%, Nb 0-3wt.%, Ti 0-3wt.%, Mo 0-3wt.% can also be added, and the rest is Fe and inevitable impurities. The large amount of Al added can greatly reduce the density of steel materials and improve corrosion resistance; the addition of Mn and C can regulate the stability of austenite and improve the yield strength through solid solution strengthening; the addition of Ni can promote the formation of NiAl type B2 phase, and high strength, excellent work hardening ability and greater plasticity can be obtained by adjusting the morphology of the B2 phase; the addition of microalloying elements V, Nb, Ti and Mo can promote the formation of carbides, thereby improving strength.

[0036] The double heterogeneous structure high-strength plasticity low-density steel is subjected to multiple rolling and annealing treatments to obtain a double heterogeneous structure low-density steel with austenite and B2 phase grain sizes showing a bimodal distribution.

[0037] In a specific embodiment, the double heterogeneous structure high-strength plasticity low-density steel, the invention adjusts the organization and mechanical properties by changing the alloy composition and processing technology, and finally obtains the double heterogeneous structure high-strength plasticity low-density steel, the yield strength of which is 800-1200MPa, the tensile strength is 1100-1400MPa, the elongation is 30-50%, the strength-plasticity product is 40-60GPa%, and the density is 6.1-6.9g / cm 3 .

[0038] See also Figure 1 As shown, the present invention also provides a method for preparing a double heterogeneous structure high-strength plasticity low-density steel, including common die casting and continuous casting. The following preparation method takes die casting as an example, and specifically includes the following steps:

[0039] Step 1, material preparation: Fe, Mn, C, Al, Ni, V, Nb, Ti, Mo, etc. with a purity of ≥99.8% are weighed as alloy raw materials according to the chemical composition ratio of the double heterostructure high-strength plasticity low-density steel; the alloy raw materials are placed in an electric arc furnace or an induction furnace for smelting, and then the smelted molten steel is cast into an ingot;

[0040] Step 2, hot rolling: hot rolling the ingot in step 1 at 1200-900° C. for multiple passes, with a hot rolling reduction of ≥60%;

[0041] Step 3, cold rolling: homogenization treatment, the hot-rolled sample in step 2 is kept at 1180±80°C for 2-10h, and then multiple rolling is performed using a cold rolling mill, and the total rolling reduction is ≥50%;

[0042] Step 4, cold rolling after annealing: to eliminate dislocations and further cold rolling, the cold rolled steel sheet in step 3 is kept at 900-1100°C for 10-60 minutes, then quickly quenched in water and cooled to room temperature, and then rolled in multiple passes using a cold rolling mill, with a total rolling reduction of ≥60%;

[0043] Step 5, annealing treatment: In order to obtain recrystallized austenite and B2 precipitate phases with different morphologies, the cold-rolled steel sheet described in step 4 is kept at 900-1100°C for 3-60 minutes, and then quickly quenched in water and cooled to room temperature to obtain a double heterogeneous structure high-strength plasticity low-density steel.

[0044] In a specific embodiment, the temperature of the homogenization treatment in step 3 is 1180±80°C, the holding time is 2-10h, the cold rolling multi-pass rolling is 3-4 passes, and the total rolling reduction is ≥50%.

[0045] In a specific embodiment, the annealing temperature in step 4 is 900-1100° C., the annealing time is 10-60 min, the cold rolling multi-pass rolling is 5-6 passes, and the total rolling reduction is ≥60%;

[0046] In a specific embodiment, the annealing temperature in step 5 is 900-1100° C., and the holding time is 3-60 min.

[0047] The present invention

[0048] Embodiment 1:

[0049] A double heterogeneous structure low-density steel, whose chemical composition is calculated by mass percentage: C 0.9wt.%, Mn 24wt.%, Al 11wt.%, Ni 5wt.%, and the rest is Fe and inevitable impurities.

[0050] The method for preparing the double heterogeneous structure low-density steel comprises the following steps:

[0051] Step 1, material preparation: Fe, Mn, C, Al, and Ni with a purity of ≥99.8% are weighed as alloy raw materials according to the chemical composition ratio of the double heterostructure high-strength plasticity low-density steel; the alloy raw materials are placed in an arc melting furnace, and smelted under argon protection, and then the smelted molten steel is cast into ingots;

[0052] Step 2, hot rolling: the ingot in step 2 is subjected to multiple hot rolling at 1100-900° C., with a hot rolling reduction of 70%;

[0053] Step 3, cold rolling after annealing: the ingot in step 2 is kept at 1180° C. for 2 hours, and then rolled in multiple passes using a cold rolling mill with a total rolling reduction of 50%;

[0054] Step 4, cold rolling after annealing: the cold-rolled steel sheet in step 3 is kept at 1050° C. for 15 minutes, then quickly quenched in water and cooled to room temperature, and then rolled in multiple passes using a cold rolling mill, with a total rolling reduction of 60%;

[0055] Step 5, annealing treatment: the cold-rolled steel sheet described in step 4 is kept at 900° C. for 15 minutes, and then quickly quenched in water and cooled to room temperature to obtain a double heterogeneous structure high-strength plasticity low-density steel.

[0056] like Figure 2 As shown in the figure, the microstructure of the double heterogeneous structure high strength ductility low density steel is austenite and B2 phase with bimodal distribution of grain size, among which the B2 phase has three morphologies, namely, layered B2 (type I), B2 particles distributed at the austenite grain boundary (type II), and nano-scale B2 particles distributed inside the unrecrystallized austenite (type III). The tensile properties of the double heterogeneous structure high strength ductility low density steel prepared in this embodiment were tested. The engineering stress-strain curve is shown in Figure 1. Figure 6 The yield strength of the high-strength, plastic, and low-density double heterogeneous steel prepared in Example 1 is 1039 MPa, the tensile strength is 1300 MPa, the total elongation is 40%, and the strength-plasticity product is 52 GPa%, reaching the strength-plasticity product level of current advanced high-strength automotive steel.

[0057] Embodiment 2:

[0058] A double heterogeneous structure low-density steel, whose chemical composition is calculated by mass percentage: C 1wt.%, Mn 30wt.%, Al 12wt.%, Ni 6wt.%, Nb 0.03wt.%, V 0.1wt%, and the rest is Fe and unavoidable impurities.

[0059] The method for preparing the double heterogeneous structure low-density steel comprises the following steps:

[0060] Step 1, material preparation: Fe, Mn, C, Al, Ni, Nb and V with a purity of ≥99.8% are weighed as alloy raw materials according to the chemical composition ratio of the double heterostructure high-strength plasticity low-density steel; the alloy raw materials are placed in an arc melting furnace, smelted under argon protection, and then the smelted steel liquid is cast into an ingot;

[0061] Step 2, hot rolling: hot rolling the ingot in step 2 at 1050-900° C. for multiple passes with a hot rolling reduction of 60%;

[0062] Step 3, cold rolling: the hot-rolled sample described in step 2 is kept at 1100° C. for 3 h, and then rolled in multiple passes using a cold rolling mill, with a total rolling reduction of ≥50%;

[0063] Step 4, cold rolling after annealing: the cold-rolled steel sheet described in step 3 is kept at 1050° C. for 30 minutes, and then quickly quenched in water to cool to room temperature, and then rolled in multiple passes using a cold rolling mill, with a total rolling reduction of 60%;

[0064] Step 5, annealing treatment: the cold-rolled steel sheet described in step 4 is kept at 1000° C. for 10 minutes, and then quickly quenched in water and cooled to room temperature to obtain a double heterogeneous structure high-strength plasticity low-density steel.

[0065] like Figure 3 As shown in the figure, the microstructure of the double heterogeneous structure high strength plasticity low density steel is austenite and B2 phase with bimodal distribution of grain size, among which the B2 phase has three morphologies, namely B2 strips (type I), B2 particles distributed at the austenite grain boundary (type II) and B2 particles inside the recrystallized austenite grains (type III). The tensile properties of the double heterogeneous structure high strength plasticity low density steel prepared in this embodiment were tested. The engineering stress-strain curve is shown in Figure 1. Figure 6 The yield strength of the double heterogeneous structure high-strength plasticity low-density steel prepared in Example 2 is 918MPa, the tensile strength is 1228MPa, the total elongation is 45%, and the strength-plasticity product is 55.3GPa%, reaching the strength-plasticity product level of current advanced high-strength automotive steel.

[0066] Embodiment 3:

[0067] A double heterogeneous structure low-density steel, whose chemical composition is calculated by mass percentage: C 0.9wt.%, Mn 26wt.%, Al 11wt.%, Ni 5wt.%, and the rest is Fe and inevitable impurities.

[0068] The preparation method of the double heterogeneous structure low-density steel comprises the following steps:

[0069] Step 1, material preparation: Fe, Mn, C, Al, and Ni with a purity of ≥99.8% are weighed as alloy raw materials according to the chemical composition ratio of the double heterostructure high-strength plasticity low-density steel; the alloy raw materials are placed in an arc melting furnace, vacuum melted under argon protection, and then the molten steel is cast into an ingot;

[0070] Step 2, hot rolling: the ingot in step 2 is subjected to multiple hot rolling at 1100-900° C. with a hot rolling reduction of 50%;

[0071] Step 3, cold rolling: the hot-rolled sample described in step 2 is kept at 1180° C. for 2 h, and then rolled in multiple passes using a cold rolling mill, with a total rolling reduction of ≥50%;

[0072] Step 4, cold rolling after annealing: the cold-rolled steel sheet in step 3 is kept at 900° C. for 15 minutes, and then quickly quenched in water to cool to room temperature, and then rolled in multiple passes using a cold rolling mill, with a total rolling reduction of 40%;

[0073] Step 5, annealing treatment: the cold-rolled steel sheet described in step 4 is kept at 1050° C. for 15 minutes, and then quickly quenched in water and cooled to room temperature to obtain a double heterogeneous structure high-strength plasticity low-density steel.

[0074] like Figure 4 As shown in the figure, the microstructure of the double heterogeneous structure high strength ductility low density steel is austenite and B2 phase with bimodal distribution of grain size, wherein the B2 phase has two morphologies, namely B2 particles distributed at the austenite grain boundary and nano-scale B2 particles inside the recrystallized austenite grains. The tensile properties of the double heterogeneous structure high strength ductility low density steel prepared in this embodiment were tested. The engineering stress-strain curve is shown in Figure 6 The double heterogeneous structure high-strength plasticity low-density steel prepared in Example 3 has a yield strength of 943 MPa, a tensile strength of 1236 MPa, a total elongation of 46%, and a strength-plasticity product of 56.9 GPa%, reaching the strength-plasticity product level of current advanced high-strength automotive steel.

[0075] Embodiment 4:

[0076] A double heterogeneous structure low-density steel, whose chemical composition is calculated by mass percentage: C 0.8wt.%, Mn 16wt.%, Al 9wt.%, Ni 4wt.%, Nb 0.05wt.%, V 0.3wt.%, Ti 0.3wt.%, Mo 0.05wt.%, and the rest is Fe and unavoidable impurities.

[0077] The preparation method of the double heterogeneous structure low-density steel comprises the following steps:

[0078] Step 1, material preparation: Fe, Mn, C, Al, Ni, Nb, V, Ti and Mo with a purity of ≥99.9% are weighed as alloy raw materials according to the chemical composition ratio of the double heterostructure high-strength plasticity low-density steel; the alloy raw materials are placed in an arc melting furnace, vacuum melted under argon protection, and then the molten steel is cast into an ingot;

[0079] Step 2, hot rolling: the ingot in step 2 is subjected to multiple hot rolling at 1200-900° C., with a hot rolling reduction of 80%;

[0080] Step 3, cold rolling: the hot-rolled sample described in step 2 is kept at 1180° C. for 3 hours, and then rolled in multiple passes using a cold rolling mill, with a total rolling reduction of ≥50%;

[0081] Step 4, cold rolling after annealing: the cold-rolled steel sheet in step 3 is kept at 1000° C. for 15 minutes, and then quickly quenched in water to cool to room temperature, and then rolled in multiple passes using a cold rolling mill, with a total rolling reduction of 60%;

[0082] Step 5, annealing treatment: the cold-rolled steel sheet described in step 4 is kept at 950° C. for 30 minutes, and then quickly quenched in water and cooled to room temperature to obtain a double heterogeneous structure high-strength plasticity low-density steel.

[0083] like Figure 5 As shown in the figure, the microstructure of the double heterogeneous structure high strength ductility low density steel is austenite and B2 phase with bimodal distribution of grain size, wherein the B2 phase has two morphologies, namely B2 particles distributed at the austenite grain boundary and nano-scale B2 particles inside the recrystallized austenite grains. The tensile properties of the double heterogeneous structure high strength ductility low density steel prepared in this embodiment were tested. The engineering stress-strain curve is shown in Figure 6 The yield strength of the high-strength, plastic, and low-density double heterogeneous steel prepared in Example 4 is 1046 MPa, the tensile strength is 1289 MPa, the total elongation is 43%, and the strength-plasticity product is 55.4 GPa%, reaching the strength-plasticity product level of current advanced high-strength automotive steel.

[0084] Compared with the high-strength low-density steel in the prior art, the addition of a large amount of Al elements in the present invention can significantly reduce the density of steel, and introduce the non-shearable NiAl type B2 phase through Ni alloying, and construct a double heterogeneous structure low-density steel through multiple cold rolling and annealing processes. The double heterogeneous structure low-density steel can still have high strength, large plasticity and high work hardening rate at a lower density. And the addition of Al and Ni elements can greatly improve the corrosion resistance of steel materials.

[0085] The composition design of the double heterogeneous structure low-density steel ingot of the present invention adds Ni element and more Al element to promote the formation of NiAl type B2 phase and retain it to room temperature. The as-cast structure contains B2 and coarse austenite dual-phase structure, and then undergoes homogenization treatment, cold rolling and annealing treatment to obtain a double heterogeneous structure low-density steel with austenite and B2 phases with bimodal distribution of grain size. The B2 phase can include a variety of morphologies, such as B2 strips distributed along the rolling direction, polygonal B2 particles at the recrystallized austenite grain boundaries, nano-scale B2 particles inside unrecrystallized austenite grains, and nano-scale B2 particles inside recrystallized austenite grains. This double heterogeneous structure can effectively reduce the density of steel while improving the strength, plasticity and work hardening rate of steel. Its yield strength is 800-1200MPa, tensile strength is 1100-1400MPa, elongation is 30-50%, strength-plasticity product is 40-60GPa%, and density is 6.1-6.9g / cm 3, meeting the performance requirements of the third-generation automotive steel and having greater practical application value than ordinary third-generation automotive steel.

[0086] The preparation process of the dual heterogeneous structure low-density steel of the present invention is simple and economical, and can realize large-scale industrial production. The research and development and application of the finished steel have important economic value and social significance for promoting lightweight design of automobiles, improving strength and plasticity, reducing energy consumption, and reducing greenhouse gas emissions.

[0087] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

[0088] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0089] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0090] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0091] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A double heterogeneous structure high-strength ductility low-density steel, characterized in that: The low-density steel comprises the following mass percentage element components: C 0.7-1.2wt.%, Mn 14-35wt.%, Al 8-14wt.%, Ni 3-7wt.; the rest is Fe and unavoidable impurities; The grain size of the austenite and B2 phase of the low-density steel is bimodal distribution; The low-density steel has a yield strength of 800-1200 MPa, a tensile strength of 1100-1400 MPa, an elongation of 30-50%, a strength-plasticity product of 40-60 GPa%, and a density of 6.1-6.9 g / cm 3 ; The low-density steel further comprises: V 0-3wt.%, Nb 0-3wt.%, Ti 0-3wt.%, Mo 0-3wt.%; The preparation of the double heterogeneous structure high-strength ductility low-density steel comprises the following steps: Step 1, material preparation: selecting alloy raw materials according to the chemical composition ratio of the double heterogeneous structure high-strength plasticity low-density steel, melting the alloy raw materials, and casting them into ingots; Step 2, hot rolling: hot rolling the ingot at 900-1200° C. for multiple passes to obtain a hot-rolled sample; Step 3, cold rolling: performing multiple passes of rolling on the hot-rolled sample after heat preservation to obtain a cold-rolled steel sheet; Step 4, cold rolling after annealing; the cold-rolled steel sheet is kept warm, cooled to room temperature, and then rolled for multiple passes to obtain a secondary cold-rolled steel sheet; Step 5, after heat preservation, the secondary cold-rolled steel plate is cooled to room temperature to obtain a finished product of a double heterogeneous structure high-strength plasticity low-density steel; The temperature of the heat preservation treatment in step 3 is 1180±80°C, and the heat preservation time is 2-10h; The rolling operation in step 3 is cold rolling, which is performed for 3-4 passes, with a total rolling reduction of ≥50%; The holding temperature in step 4 is 900-1100° C. and the holding time is 10-60 min; In step 4, the rolling is cold rolling, and 5-6 passes are performed, and the total rolling reduction is ≥60%; The insulation temperature in step 5 is 900-1100° C., and the insulation time is 3-60 min.

2. A method for preparing the double heterogeneous structure high-strength ductility low-density steel according to claim 1, characterized in that: The steps include: Step 1, material preparation: selecting alloy raw materials according to the chemical composition ratio of the double heterogeneous structure high-strength plasticity low-density steel, melting the alloy raw materials, and casting them into ingots; Step 2, hot rolling: hot rolling the ingot at 900-1200° C. for multiple passes to obtain a hot-rolled sample; Step 3, cold rolling: performing multiple passes of rolling on the hot-rolled sample after heat preservation to obtain a cold-rolled steel sheet; Step 4, cold rolling after annealing; the cold-rolled steel sheet is kept warm, cooled to room temperature, and then rolled for multiple passes to obtain a secondary cold-rolled steel sheet; Step 5, after heat preservation, the secondary cold-rolled steel plate is cooled to room temperature to obtain a finished product of a double heterogeneous structure high-strength plasticity low-density steel; The temperature of the heat preservation treatment in step 3 is 1180±80°C, and the heat preservation time is 2-10h; The rolling operation in step 3 is cold rolling, which is performed for 3-4 passes, with a total rolling reduction of ≥50%; The holding temperature in step 4 is 900-1100° C. and the holding time is 10-60 min; In step 4, the rolling is cold rolling, and 5-6 passes are performed, and the total rolling reduction is ≥60%; The insulation temperature in step 5 is 900-1100° C., and the insulation time is 3-60 min.

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