Fe-Mn-Al-C series lightweight steel and preparation method thereof, terminal, steel structure and electronic equipment

Abstract

The present application provides a Fe-Mn-Al-C series lightweight steel, comprising: Fe, whose weight percentage is greater than or equal to 50.4wt%; Mn, whose weight percentage is 25-35wt%; Al, whose weight percentage is 6-12wt%; C, whose weight percentage is 0.8-2.0wt%; and O, whose weight percentage is 0.005-0.6wt%. The present application also provides a terminal using the Fe-Mn-Al-C series lightweight steel, a preparation method of the Fe-Mn-Al-C series lightweight steel, a steel structure and an electronic device. The lightweight steel of the present application has low density, high strength and high ductility.

Description

Technical Field

[0001] The present application relates to a Fe-Mn-Al-C series lightweight steel and a preparation method thereof, as well as a terminal, a steel structure and an electronic device using the Fe-Mn-Al-C series lightweight steel. Background Art

[0002] The hinge mechanism of existing folding mobile phones is basically composed of two materials. One is precipitation hardened steel, which has good comprehensive mechanical properties, high strength, good toughness, yield strength of about 1000Mp, elongation of about 6%, but high density, about 7.8g / cm 3 The other is made of aluminum alloy, which has a lower density of about 2.7g / cm 3 , but the strength is low. For the 7 series aluminum alloy with the highest strength grade currently widely used in commercial applications, such as 7075, the yield strength is about 500Mpa, which is easy to deform during use. Summary of the invention

[0003] A first aspect of the embodiments of the present application provides a Fe-Mn-Al-C series lightweight steel, comprising:

[0004] Fe, the weight percentage of which is greater than or equal to 50.4wt%;

[0005] Mn, the weight percentage is 25-35wt%;

[0006] Al, the weight percentage thereof is 6 to 12 wt%;

[0007] C, whose weight percentage is 0.8-2.0wt%; and

[0008] O, its weight percentage is 0.11~0.6wt%.

[0009] The Al element improves the density of the lightweight steel, making the lightweight steel lightweight, the C element forms a carbide phase reinforcement phase to improve the strength of the lightweight steel, and the O element forms a reinforcement. The Fe-Mn-Al-C lightweight steel of the present application is a material with high strength, high ductility and low density.

[0010] In the implementation manner of the present application, the lightweight steel further contains Si, Ni and Cr, wherein the weight percentage of Si is ≤0.2wt%, the weight percentage of Ni is ≤0.6wt%, and the weight percentage of Cr is ≤0.4wt%.

[0011] The Si is used to increase the activity of C and promote the dissolution of the C element in the precipitate during aging; the Cr improves the corrosion resistance of the steel to a certain extent; and the Ni helps to refine the grains and will be enriched at the second phase interface.

[0012] In an embodiment of the present application, the lightweight steel further contains at least one of Cu, V, Ti, Nb, W, Zr, Mo, and Re, wherein the total weight percentage of Cu, V, Ti, Nb, W, Zr, Mo, and Re is ≤1wt%.

[0013] The lightweight steel also contains at least one of Cu, V, Ti, Nb, W, Zr, Mo, and Re to further improve the performance of the lightweight steel; for example, Cu can be used as a dispersed phase in the lightweight steel.

[0014] In the embodiment of the present application, the lightweight steel is formed by a metal injection molding process using powder raw materials.

[0015] The metal injection molding process can be used to produce small, precise, lightweight steel parts with complex curves, which can be widely used in various electronic products.

[0016] In the embodiment of the present application, the powder raw material includes the following chemical composition: 28wt%≤Mn≤35wt%, 6wt%≤Al≤12wt%, 0.7wt%≤C≤1.8wt%, 0.003wt%≤O≤0.4wt%, 0≤Si≤0.2wt%, 0≤Ni≤0.6wt%, 0≤Cr≤0.4wt%, 0≤Cu+V+Ti+Nb+W+Zr+Mo+Re≤1wt%, and the rest is Fe; wherein Cu+V+Ti+Nb+W+Zr+Mo+Re refers to containing at least one of Cu, V, Ti, Nb, W, Zr, Mo and Re, and the total weight percentage of Cu, V, Ti, Nb, W, Zr, Mo and Re.

[0017] The Fe-Mn-Al-C lightweight steel of the present application can be obtained by using the above powder raw materials, which has high strength, high ductility and low density.

[0018] In the embodiment of the present application, the density of the lightweight steel is 5.9-7.0 g / cm 3 , yield strength is 800~1200Mpa, and elongation is 2%~20%.

[0019] The lightweight steel has low density, high strength and high ductility; the steel has high strength, and the steel structure using the lightweight steel does not need to increase the thickness to ensure the reliability of the steel structure, which is conducive to the miniaturization of the steel structure, and thus is conducive to the miniaturization of electronic equipment.

[0020] In the implementation manner of the present application, a functional coating is formed on the surface of the lightweight steel.

[0021] The functional coating is used as a decorative layer to further beautify the lightweight layer, or as a functional coating to further protect or functionalize the lightweight steel.

[0022] A second aspect of an embodiment of the present application provides a terminal, comprising the Fe-Mn-Al-C series lightweight steel.

[0023] The Fe-Mn-Al-C series lightweight steel has low density / light weight, high strength, high ductility, and can be prepared by a metal injection molding process suitable for small, precise, and complex curved parts, which can effectively improve the performance and / or service life of the terminal.

[0024] In the implementation manner of the present application, the terminal is a consumer electronic sample, which includes structural components, and at least one structural component is made of the Fe-Mn-Al-C series lightweight steel.

[0025] The Fe-Mn-Al-C series is lightweight, has low density, high strength, and high ductility, reduces the risk of fracture and deformation of structural parts in the terminal, improves the quality of the terminal, and has low density, which is conducive to the lightweight of terminal products.

[0026] In the implementation manner of the present application, the terminal is a folding mobile phone including a rotating shaft, and the rotating shaft is made of the Fe-Mn-Al-C series lightweight steel.

[0027] The rotating shaft is made of the Fe-Mn-Al-C series lightweight steel, which reduces the risk of the rotating shaft of the folding mobile phone breaking when falling from a height, and reduces the risk of the rotating shaft deforming during use, thereby improving the quality of the folding mobile phone.

[0028] A third aspect of the embodiments of the present application provides a method for preparing Fe-Mn-Al-C based lightweight steel, comprising:

[0029] Prepare a powder raw material, the powder raw material includes the following chemical components:

[0030] 28wt%≤Mn≤35wt%, 6wt%≤Al≤12wt%, 0.7wt%≤C≤1.8wt%, 0.003wt%≤O≤0.4wt%, 0≤Si≤0.2wt%, 0≤Ni≤0.6wt%, 0≤Cr≤0.4wt%, 0≤Cu+V+Ti+Nb+W+Zr+Mo+Re≤1wt%, and the remainder is Fe; wherein Cu+V+Ti+Nb+W+Zr+Mo+Re refers to at least one of Cu, V, Ti, Nb, W, Zr, Mo and Re, and the total weight percentage of Cu, V, Ti, Nb, W, Zr, Mo and Re; and

[0031] The Fe-Mn-Al-C series lightweight steel is prepared by using the powder raw material and a metal injection molding process.

[0032] By using the above-mentioned powder raw materials and undergoing a metal injection molding process, a Fe-Mn-Al-C lightweight steel having the composition ratio of the present application can be obtained, which has high strength, high ductility, and low density; the Fe-Mn-Al-C lightweight steel is not easily deformed or broken under high-intensity forces.

[0033] In the embodiment of the present application, the metal injection molding process includes:

[0034] forming the powder raw material into a green compact;

[0035] sintering the green compact to form a sintered compact; and

[0036] The sintered compact is heat treated.

[0037] The lightweight steel formed by the metal injection molding process provided in the present application can effectively obtain three-dimensional complex and precise steel structural parts in one time. Compared with traditional mechanical processing, such as computer numerical control machine tools forming complex and precise steel structural parts without additional processing, it improves the production efficiency of preparing complex and precise steel materials, reduces the cost of preparing steel materials, and is conducive to the large-scale production of steel materials.

[0038] In the embodiment of the present application, forming the green compact from the powder raw material includes: mixing the powder raw material with a binder; and molding the mixture of the powder raw material and the binder into a green compact by injection molding.

[0039] The green billet of lightweight steel is formed by injection molding, which not only has high forming efficiency and low cost, but also can effectively obtain three-dimensional complex and precise green billets of lightweight steel at one time, thereby improving the production efficiency of preparing complex and precise lightweight steel. The powder raw material is mixed with a binder, and the powder raw material has a certain fluidity, which reduces or avoids defects such as cracks or corner loss in the green billet. At the same time, the powder raw material is mixed with a binder, and the green billet after forming has a certain strength, and can maintain its shape when it is released from the mold cavity, which reduces or avoids the deformation of the green billet, thereby improving the yield rate.

[0040] In the embodiment of the present application, before sintering the green body, the preparation method further includes degreasing the green body to remove part of the binder in the green body.

[0041] In some embodiments, the binder in the green body is removed by catalytic degreasing. Catalytic degreasing to remove the binder utilizes the property that the polymer can be rapidly degraded in a specific atmosphere, so that the green body is degreased in the corresponding atmosphere, and the binder is decomposed to remove the binder. In the embodiments of the present application, the binder in the green body is removed by catalytic degreasing, which can not only achieve fast and defect-free degreasing, but also increase the efficiency of degreasing, thereby improving the efficiency of preparing steel.

[0042] In the embodiment of the present application, heat treating the sintered green body comprises: solutionizing the sintered green body; and aging the sintered green body after solutionizing.

[0043] Heat treatment can further enhance the properties of the lightweight steel.

[0044] A fourth aspect of the embodiments of the present application provides a steel structure, which is formed using the above-mentioned preparation method.

[0045] The steel structure is manufactured by the above method, so that the steel structure has low density, high strength, and high ductility; the steel structure is not prone to breakage and deformation and has a long service life.

[0046] A fifth aspect of an embodiment of the present application provides a steel structure, wherein the material used for the steel structure includes the above-mentioned Fe-Mn-Al-C series lightweight steel.

[0047] The material used for the steel structure includes the above-mentioned Fe-Mn-Al-C series lightweight steel, which increases the strength of the steel structure. This steel structure does not need to increase the thickness of the steel structure to further ensure the reliability of the steel structure, which is conducive to the miniaturization of the steel structure.

[0048] A sixth aspect of the embodiments of the present application provides an electronic device, comprising the above-mentioned steel structure.

[0049] The steel structure is applied to electronic equipment, reducing the risk of the steel structure in the electronic equipment breaking due to falling from a height and deforming during use, thereby improving the quality of the electronic equipment. At the same time, the steel structure has a high strength, and the steel structure does not need to increase the thickness to ensure the reliability of the steel structure, which is conducive to the miniaturization of electronic equipment; and the steel structure is light in weight, which is conducive to the lightweight of electronic equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic diagram of the structure of the terminal of an embodiment of the present application.

[0051] Figure 2 It is a schematic flow chart of the method for preparing Fe-Mn-Al-C based lightweight steel according to an embodiment of the present application.

[0052] Main component symbols

[0053] Terminal 100

[0054] Part 110

[0055] Part 2130

[0056] Axis 20 DETAILED DESCRIPTION

[0057] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0058] The structural components of consumer electronic products are generally small precision parts with complex three-dimensional curved surface structures. They are responsible for the smooth operation of the mechanism and the reliability of the structure. Therefore, the requirements for materials are multi-dimensional. In addition to the requirements of light weight / low density, they at least include strength (such as yield strength, tensile strength), plasticity (such as elongation), and molding process (casting, forging, stamping, digital control precision machining (CNC)), and each dimension restricts each other.

[0059] The terminal of the embodiment of the present application includes Fe-Mn-Al-C series lightweight steel. The terminal is a consumer electronic product, which includes structural parts, at least one of which is made of the Fe-Mn-Al-C series lightweight steel. The Fe-Mn-Al-C series lightweight steel has the advantages of low density / light weight, high strength, and can be prepared by metal injection molding (Metal injection molding) process. The metal injection molding process is suitable for the preparation of small, precise, and complex curved parts due to its molding characteristics.

[0060] For example, Figure 1 As shown, the terminal 100 is a foldable mobile phone, which includes a first part 110 and a second part 130 that can be folded with each other, and a rotating shaft 20 arranged between the first part 110 and the second part 130, and the first part 110 and the second part 130 are relatively rotated through the rotating shaft 20. The material of the rotating shaft 20 is the Fe-Mn-Al-C series lightweight steel. It can be understood that the Fe-Mn-Al-C series lightweight steel is not limited to forming the rotating shaft of a foldable mobile phone, but can also be a camera decoration of a mobile phone, other types of structural parts in a mobile phone; the Fe-Mn-Al-C series lightweight steel can also be used to form structural parts in other consumer electronic products. It can be understood that the Fe-Mn-Al-C series lightweight steel can also be used in vehicles as a vehicle-mounted structural part.

[0061] The Fe-Mn-Al-C lightweight steel of the embodiment of the present application includes the following chemical composition (the following range values ​​include end values):

[0062] Fe, weight percentage is greater than or equal to 50.4wt%;

[0063] Mn, weight percentage is 25-35wt%;

[0064] Al, weight percentage is 6-12wt%;

[0065] C, with a weight percentage of 0.8 to 2.0 wt%; and

[0066] O, weight percentage 0.005~0.6wt%.

[0067] The lightweight steel may also selectively contain Si, Ni and Cr, wherein the weight percentage of Si is ≤0.2wt%, the weight percentage of Ni is ≤0.6wt%, and the weight percentage of Cr is ≤0.4wt%.

[0068] The lightweight steel also selectively contains at least one of Cu, V, Ti, Nb, W, Zr, Mo and Re, wherein the total weight percentage of Cu, V, Ti, Nb, W, Zr, Mo and Re is ≤1wt%.

[0069] It is understandable that the lightweight steel may contain other unavoidable impurity elements, but their content is extremely low and can be ignored.

[0070] The lightweight steel has a low density of 5.9-7.0 g / cm 3 ; Compared with the density of conventional steel 7.98g / cm 3 , reducing weight by about 25% to 14%; thus, the weight of mobile phone consumer electronic products can be significantly reduced, and the user experience can be improved. In addition, the lightweight steel has high strength, with a yield strength of 800 to 1200 MPa; high plasticity and toughness, and an elongation of 2% to 20%.

[0071] The Fe-Mn-Al-C series lightweight steel can be formed by using powder raw materials through a metal injection molding process. Figure 2 As shown, the preparation method of the Fe-Mn-Al-C series lightweight steel specifically includes the following steps:

[0072] S1: Prepare a powder raw material, the powder raw material includes the following chemical components:

[0073] 28wt%≤Mn≤35wt%, 6wt%≤Al≤12wt%, 0.7wt%≤C≤1.8wt%, 0.003wt%≤O≤0.4wt%, 0≤Si≤0.2wt%, 0≤Ni≤0.6wt%, 0≤Cr≤0.4wt%, 0≤Cu+V+Ti+Nb+W+Zr+Mo+Re≤1wt%, and the rest is Fe; wherein Cu+V+Ti+Nb+W+Zr+Mo+Re refers to containing at least one of Cu, V, Ti, Nb, W, Zr, Mo and Re, and the total weight percentage of Cu, V, Ti, Nb, W, Zr, Mo and Re.

[0074] S2: forming the powder raw material into a green body.

[0075] S3: Sintering the green compact to form a sintered compact.

[0076] S4: heat treating the sintered compact.

[0077] Forming the powder raw material into the green compact includes: mixing the powder raw material with a binder; and molding the mixture of the powder raw material and the binder into a green compact by injection molding (injecting into a mold cavity).

[0078] Before sintering the green compact, the preparation method further comprises degreasing the green compact to remove part of the binder in the green compact.

[0079] The heat treatment of the sintered green body comprises: solutionizing the sintered green body; and aging the solutionized green body.

[0080] Debinding refers to the process of removing most of the organic binder from the green body formed by injection molding by catalysis, heating, dissolution and other methods before sintering.

[0081] The binder is a binder specifically used for alloy powders, usually an organic binder, which is used to bind the powder raw materials together to facilitate subsequent injection molding.

[0082] The sintering refers to the process of converting a powdered material (the powdered raw material described in this application) into a dense body, which is a process in which the molecules or atoms in the solid state obtain enough energy to migrate by heating, so that the powder body produces particle bonding, generates strength, and leads to densification and recrystallization. For example, the sintering of the embodiment of this application can be heated to 1200℃~1300℃ and kept warm for 0.5~3h. During the sintering process, the binder will be removed.

[0083] The solid solution treatment refers to the heat treatment process of heating the alloy (the product after sintering in this application) to a high temperature single-phase region and maintaining it at a constant temperature, so that the excess phase is fully dissolved into the solid solution and then rapidly cooled to obtain a supersaturated solid solution; the purpose of the solid solution treatment is to dissolve the carbides and γ' phases in the matrix to obtain a uniform supersaturated solid solution, so as to facilitate the re-precipitation of fine-grained and uniformly distributed carbides and γ' strengthening phases during aging, and at the same time eliminate the stress caused by hot and cold processing to cause the alloy to recrystallize. For example, the solid solution treatment in the embodiment of this application can be solid solution treatment at a temperature of 980 to 1150°C for 0.5 to 4 hours.

[0084] The aging process refers to the heat treatment process in which the product after sintering and solutionizing is placed at a higher temperature or room temperature to maintain its shape and size, and the performance changes over time. For example, the aging process in the embodiment of the present application can be aging at a temperature of 450-600°C for 0.5-36h.

[0085] In the embodiment of the present application, the powder raw material can be prepared by an atomization method, a reduction method, a mechanical grinding method, etc.; the particle size distribution range of the powder raw material, the binder system and ratio, the degreasing method, etc. adopt conventional methods in the field and can be adjusted accordingly as needed.

[0086] By controlling the chemical composition and ratio of the powder raw materials and adopting the above-mentioned metal injection molding process, the composition and properties of the Fe-Mn-Al-C lightweight steel disclosed in this application can be obtained. In addition, by selecting and adjusting the specific process parameters of the metal injection molding process, there is a possibility of further reducing the density of the lightweight steel and improving the strength and plasticity.

[0087] In the embodiment of the present application, the powder raw material includes the following chemical components:

[0088] 28wt%≤Mn≤35wt%, 6wt%≤Al≤12wt%, 0.7wt%≤C≤1.8wt%, 0.003wt%≤O≤0.4wt%, 0≤Si≤0.2wt%, 0≤Ni≤0.6wt%, 0≤Cr≤0.4wt%, 0≤Cu+V+Ti+Nb+W+Zr+Mo+Re≤1wt%, and the rest is Fe; wherein Cu+V+Ti+Nb+W+Zr+Mo+Re refers to containing at least one of Cu, V, Ti, Nb, W, Zr, Mo and Re, and the total weight percentage of Cu, V, Ti, Nb, W, Zr, Mo and Re.

[0089] Powder raw materials can generally be made in two ways: one is to make powders after pre-alloying, and all elements exist in the form of alloys, and the other is to mix multiple single elements or multiple compounds in an adjusted proportion, which is still reflected as multiple single elements or multiple compounds. In the embodiments of the present application, oxygen (O) can exist in the form of iron oxide, aluminum oxide, chromium oxide, etc., or oxygen atoms exist in the gaps between metal atoms (such as Fe) at the microscopic level.

[0090] The C element in the powder raw material forms a carbide phase reinforcement phase to improve the strength of the steel; Cu can be used as a dispersed phase; Cr improves corrosion resistance to a certain extent; O forms reinforcement that can be adjusted during the sintering process; Si is used to increase C activity and promote the dissolution of C elements in precipitates during aging; Ni helps to refine the grains, and studies have shown that it will be enriched at the second phase interface.

[0091] The main crystal structure of the lightweight steel is austenite, and the main strengthening phase includes intermetallic compound type strengthening phases, such as FeMn, FeAl, Fe 3 Al, etc.; carbide strengthening phase, such as MC 3 、M 7 C 3 、M 23 C 6 etc. (wherein M represents a metal element). The composition of the lightweight steel in the embodiment of the present application innovatively introduces an oxide strengthening phase, which is mainly a strengthening phase formed by oxygen and aluminum. However, oxygen in conventional smelting steel is an impurity element and needs to be controlled.

[0092] The surface of the Fe-Mn-Al-C series lightweight steel may be formed with a functional coating as required, and the coating may be formed by passivation, electroplating, spraying, physical vapor deposition (PVD) and other processes.

[0093] The embodiment of the present application also provides a steel structure (not shown), which is formed by the above-mentioned preparation method. The steel structure is made by the above-mentioned method, so that the steel structure has low density, high strength, and high ductility; the steel structure is not easy to break and deform, and has a long service life.

[0094] The embodiment of the present application also provides a steel structure (not shown), the material used in the steel structure includes the above-mentioned Fe-Mn-Al-C series lightweight steel. The material used in the steel structure includes the above-mentioned Fe-Mn-Al-C series lightweight steel, so that the strength of the steel structure is increased, and the steel structure does not need to increase the thickness of the steel structure to further ensure the reliability of the steel structure, which is conducive to the miniaturization of the steel structure.

[0095] The embodiment of the present application also provides an electronic device (not shown), which includes the above-mentioned steel structure. The steel structure is applied to the electronic device, which reduces the risk of the steel structure in the electronic device breaking due to falling from a height and deforming during use, thereby improving the quality of the electronic device. At the same time, the steel structure has a high strength, and the steel structure does not need to increase the thickness to ensure the reliability of the steel structure, which is conducive to the miniaturization of the electronic device; and the steel structure is light, which is conducive to the lightweight of the electronic device.

[0096] The preparation method of the Fe-Mn-Al-C lightweight steel of the embodiment of the present application is further described below through specific examples.

[0097] Step 1: Prepare alloy powder by atomization method, the powder particle size D50 is 5-15μm (50% of the particles have a particle size of 5-15μm), D90≤45μm (90% of the particles have a particle size ≤45μm), and a total of seven groups of different alloy powder raw materials are prepared. The powder chemical composition is shown in Powder Examples 1 to 7 in Table 1, wherein Table 1 does not list the weight percentage of Fe. The weight percentage of Fe in each powder component is obtained by subtracting the weight percentage of all other elements from 1.

[0098] Step 2: The above seven groups of powders were respectively mixed with a binder in a volume ratio of 56:44 at 180°C to prepare seven groups of feeds. The binder components used were: polyoxymethylene (POM): ethylene-vinyl acetate copolymer (EVA): polyethylene (PE): microcrystalline wax (CW): stearic acid (SA) in a weight ratio of 85:1:5.5:2:1.

[0099] Step 3: seven groups of feed materials are placed in the injection molding machine respectively, and injected into the mold cavity respectively to shape seven groups of green billets; and the green billets are subjected to a catalytic degreasing process at a temperature of 130° C. and a fuming nitric acid catalyst to remove part of the binder in the green billets.

[0100] Step 4: Each group of green billets is subjected to high-temperature sintering for 2 to 3 hours, solution treatment for 1 hour, and aging for 2 hours to obtain at least one sample (lightweight steel). Please refer to Table 2 for the sintering temperature, solution temperature, and aging temperature corresponding to each sample (lightweight steel). For example, sample 1-1 is sintered by heating to 1200℃±5℃ and keeping it for 2 to 3 hours, solution treatment at 1100±5℃ for 1 hour, and aging at 500±5℃ for 2 hours.

[0101] The chemical composition of each sample (light steel) is shown in Table 1. Each group of powder raw materials in the first to sixth groups finally obtains 3 to 5 samples (light steel) with different chemical compositions after sintering, solid solution and aging, and the difference in chemical composition is mainly caused by the difference in process parameters of sintering, solid solution and aging; the seventh group of powder raw materials corresponds to one sample (light steel).

[0102] Table 1

[0103]

[0104]

[0105] All the samples (lightweight steel) obtained above were tested for performance, including density, yield strength and elongation. The test results of each sample (lightweight steel) are shown in Table 2. For example, the density of sample 1-1 is 6.96 g / cm 3 , yield strength is 881MPa and elongation is 12%.

[0106] Table 2

[0107]

[0108]

[0109] As can be seen from the above, the density of 5.9-7.0 g / cm can be obtained by powder sintering and subsequent solution and aging heat treatment. 3 The yield strength is 800~1200Mpa, and it is a lightweight steel with an elongation of 2%~20%. This is mainly attributed to the sintering forming brought about by the formulation of material components and the introduction of oxide strengthening phase.

[0110] It should be noted that the above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application; the implementation methods of the present application and the features in the implementation methods can be combined with each other without conflict. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A Fe-Mn-Al-C lightweight steel, characterized in that: include: Fe, the weight percentage of which is greater than or equal to 50.4wt%; Mn, the weight percentage is 25-35wt%; Al, the weight percentage thereof is 6 to 12 wt%; C, whose weight percentage is 0.8-2.0wt%; and O, its weight percentage is 0.11~0.6wt%.

2. The Fe-Mn-Al-C lightweight steel according to claim 1, characterized in that: The lightweight steel further contains Si, Ni and Cr, wherein the weight percentage of Si is ≤0.2wt%, the weight percentage of Ni is ≤0.6wt%, and the weight percentage of Cr is ≤0.4wt%.

3. The Fe-Mn-Al-C lightweight steel according to claim 1, characterized in that: The lightweight steel also contains at least one of Cu, V, Ti, Nb, W, Zr, Mo and Re, wherein the total weight percentage of Cu, V, Ti, Nb, W, Zr, Mo and Re is ≤1wt%.

4. The Fe-Mn-Al-C lightweight steel according to claim 1, characterized in that: The lightweight steel is formed by a metal injection molding process using a powder raw material.

5. The Fe-Mn-Al-C based lightweight steel according to claim 4, characterized in that: The powder raw material includes the following chemical components: 28wt%≤Mn≤35wt%, 6wt%≤Al≤12wt%, 0.7wt%≤C≤1.8wt%, 0.003wt%≤O≤0.4wt%, 0≤Si≤0.2wt%, 0≤Ni≤0.6wt%, 0≤Cr≤0.4wt%, 0≤Cu+V+Ti+Nb+W+Zr+Mo+Re≤1wt%, and the rest is Fe; wherein Cu+V+Ti+Nb+W+Zr+Mo+Re refers to at least one of Cu, V, Ti, Nb, W, Zr, Mo and Re, and the total weight percentage of Cu, V, Ti, Nb, W, Zr, Mo and Re.

6. The Fe-Mn-Al-C lightweight steel according to claim 1, characterized in that: The density of the lightweight steel is 5.9-7.0 g / cm 3 , yield strength is 800~1200Mpa, and elongation is 2%~20%.

7. The Fe-Mn-Al-C lightweight steel according to claim 1, characterized in that: A functional coating is formed on the surface of the lightweight steel.

8. A terminal, characterized in that: It comprises the Fe-Mn-Al-C based lightweight steel as claimed in any one of claims 1 to 7.

9. The terminal according to claim 8, characterized in that: The terminal is a consumer electronic product, which includes structural parts, at least one of which is made of the Fe-Mn-Al-C series lightweight steel.

10. The terminal according to claim 8, characterized in that: The terminal is a foldable mobile phone comprising a rotating shaft, and the rotating shaft is made of the Fe-Mn-Al-C series lightweight steel.

11. A method for preparing Fe-Mn-Al-C lightweight steel, characterized in that: include: Prepare a powder raw material, the powder raw material includes the following chemical components: 28wt%≤Mn≤35wt%, 6wt%≤Al≤12wt%, 0.7wt%≤C≤1.8wt%, 0.003wt%≤O≤0.4wt%, 0≤Si≤0.2wt%, 0≤Ni≤0.6wt%, 0≤Cr≤0.4wt%, 0≤Cu+V+Ti+Nb+W+Zr+Mo+Re≤1wt%, and the remainder is Fe; wherein Cu+V+Ti+Nb+W+Zr+Mo+Re refers to at least one of Cu, V, Ti, Nb, W, Zr, Mo and Re, and the total weight percentage of Cu, V, Ti, Nb, W, Zr, Mo and Re; and The Fe-Mn-Al-C series lightweight steel is prepared by using the powder raw material and a metal injection molding process.

12. The method for preparing Fe-Mn-Al-C lightweight steel according to claim 11, characterized in that: The metal injection molding process comprises: forming the powder raw material into a green compact; sintering the green compact to form a sintered compact; and The sintered compact is heat treated.

13. The method for preparing Fe-Mn-Al-C lightweight steel according to claim 12, characterized in that: Forming the powder raw material into the green compact includes: mixing the powder raw material with a binder; and molding the mixture of the powder raw material and the binder into a green compact by injection molding.

14. The method for preparing Fe-Mn-Al-C lightweight steel according to claim 13, characterized in that: Before sintering the green compact, the preparation method further comprises degreasing the green compact to remove part of the binder in the green compact.

15. The method for preparing Fe-Mn-Al-C lightweight steel according to claim 12, characterized in that: The heat treatment of the sintered green body comprises: solutionizing the sintered green body; and aging the solutionized green body.

16. A steel structure, characterized in that: The method is formed by the preparation method according to any one of claims 11 to 15.

17. A steel structure, characterized in that: The material used for the steel structure includes the Fe-Mn-Al-C lightweight steel as described in any one of claims 1 to 7.

18. An electronic device, characterized in that: Comprising the steel structural member as claimed in claim 16 or 17.

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