FE-MN-AL-C LIGHTWEIGHT STEEL, PRODUCTION METHOD THEREOF, TERMINAL, STEEL MECHANICAL PART, AND ELECTRONIC DEVICE

Abstract

This application provides Fe—Mn—Al—C lightweight steel, including: Fe, wherein a weight percentage of the Fe is greater than or equal to 50.4 wt %; Mn, wherein a weight percentage of the Mn is 25-35 wt %; Al, wherein a weight percentage of the Al is 6-12 wt %; C, wherein a weight percentage of the C is 0.8-2.0 wt %; and O, wherein a weight percentage of the O is 0.005-0.6 wt %. This application further provides a terminal to which the Fe—Mn—Al—C lightweight steel is applied, a production method for the Fe—Mn—Al—C lightweight steel, a steel mechanical part, and an electronic device. The lightweight steel in this application has low density, high strength, and high elongation.

Claims

1. Fe—Mn—Al—C lightweight steel, comprising: Fe, wherein a weight percentage of the Fe is greater than or equal to 50.4 wt %; Mn, wherein a weight percentage of the Mn is 25-35 wt %; Al, wherein a weight percentage of the Al is 6-12 wt %; C, wherein a weight percentage of the C is 0.8-2.0 wt %; and O, wherein a weight percentage of the O is 0.005-0.6 wt %.

2. The Fe—Mn—Al—C lightweight steel according to claim 1, wherein the lightweight steel further comprises Si, Ni, and Cr, a weight percentage of the Si is ≤0.2 wt %, a weight percentage of the Ni is ≤0.6 wt %, and a weight percentage of the Cr is ≤0.4 wt %.

3. The Fe—Mn—Al—C lightweight steel according to claim 1, wherein the lightweight steel further comprises at least one of Cu, V, Ti, Nb, W, Zr, Mo, and Re, and a total weight percentage of Cu, V, Ti, Nb, W, Zr, Mo, and Re is ≤1 wt %.

4. The Fe—Mn—Al—C lightweight steel according to claim 1, wherein the lightweight steel is formed by using a powder raw material and a metal injection molding process.

5. The Fe—Mn—Al—C lightweight steel according to claim 4, wherein the powder raw material comprises the following chemical components: 28 wt %≤Mn≤35 wt %, 6 wt %≤Al≤12 wt %, 0.7 wt %≤C≤1.8 wt %, 0.003 wt %≤O≤0.4 wt %, 0≤Si≤0.2 wt %, 0≤Ni≤0.6 wt %, 0≤Cr≤0.4 wt %, and 0≤Cu+V+Ti+Nb+W+Zr+Mo+Re≤1 wt %, and the rest is Fe, wherein Cu+V+Ti+Nb+W+Zr+Mo+Re means that at least one of Cu, V, Ti, Nb, W, Zr, Mo, and Re is comprised and indicates a 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, wherein density of the lightweight steel is 5.9-7.0 g/cm.sup.3, yield strength of the lightweight steel is 800-1200 MPa, and elongation of the lightweight steel is 2% to 20%.

7. The Fe—Mn—Al—C lightweight steel according to claim 1, wherein a functional coating is formed on a surface of the lightweight steel.

8. A terminal, comprising the Fe—Mn—Al—C lightweight steel comprising: Fe, wherein a weight percentage of the Fe is greater than or equal to 50.4 wt %; Mn, wherein a weight percentage of the Mn is 25-35 wt %; Al, wherein a weight percentage of the Al is 6-12 wt %; C, wherein a weight percentage of the C is 0.8-2.0 wt %; and O, wherein a weight percentage of the O is 0.005-0.6 wt %.

9. The terminal according to claim 8, wherein the lightweight steel further comprises Si, Ni, and Cr, a weight percentage of the Si is ≤0.2 wt %, a weight percentage of the Ni is ≤0.6 wt %, and a weight percentage of the Cr is ≤0.4 wt %.

10. The terminal according to claim 8, wherein the lightweight steel further comprises at least one of Cu, V, Ti, Nb, W, Zr, Mo, and Re, and a total weight percentage of Cu, V, Ti, Nb, W, Zr, Mo, and Re is ≤1 wt %.

11. The terminal according to claim 8, wherein the lightweight steel is formed by using a powder raw material and a metal injection molding process.

12. The terminal according to claim 11, wherein the powder raw material comprises the following chemical components: 28 wt %≤Mn≤35 wt %, 6 wt %≤Al≤12 wt %, 0.7 wt %≤C≤1.8 wt %, 0.003 wt %≤O≤0.4 wt %, 0≤Si≤0.2 wt %, 0≤Ni≤0.6 wt %, 0≤Cr≤0.4 wt %, and 0≤Cu+V+Ti+Nb+W+Zr+Mo+Re≤1 wt %, and the rest is Fe, wherein Cu+V+Ti+Nb+W+Zr+Mo+Re means that at least one of Cu, V, Ti, Nb, W, Zr, Mo, and Re is comprised and indicates a total weight percentage of Cu, V, Ti, Nb, W, Zr, Mo, and Re.

13. The terminal according to claim 8, wherein density of the lightweight steel is 5.9-7.0 g/cm.sup.3, yield strength of the lightweight steel is 800-1200 MPa, and elongation of the lightweight steel is 2% to 20%.

14. The terminal according to claim 8, wherein the terminal is a consumer electronics product, and comprises structural parts, and at least one of the structural parts comprises the Fe—Mn—Al—C lightweight steel.

15. The terminal according to claim 8, wherein the terminal is a foldable mobile phone comprising a rotating shaft, and the rotating shaft comprises the Fe—Mn—Al—C lightweight steel.

16. A production method for Fe—Mn—Al—C lightweight steel, comprising: producing a powder raw material, wherein the powder raw material comprises the following chemical components: 28 wt %≤Mn≤35 wt %, 6 wt %≤Al≤12 wt %, 0.7 wt %≤C≤1.8 wt %, 0.003 wt %≤O≤0.4 wt %, 0≤Si≤0.2 wt %, 0≤Ni≤0.6 wt %, 0≤Cr≤0.4 wt %, and 0≤Cu+V+Ti+Nb+W+Zr+Mo+Re≤1 wt %, and the rest is Fe, wherein Cu+V+Ti+Nb+W+Zr+Mo+Re means that at least one of Cu, V, Ti, Nb, W, Zr, Mo, and Re is comprised and indicates a total weight percentage of Cu, V, Ti, Nb, W, Zr, Mo, and Re; and producing the Fe—Mn—Al—C lightweight steel by using the powder raw material and a metal injection molding process.

17. The production method for the Fe—Mn—Al—C lightweight steel according to claim 16, wherein the metal injection molding process comprises: forming a green body based on the powder raw material; sintering the green body to form a sintered body; and performing heat treatment on the sintered body.

18. The production method for the Fe—Mn—Al—C lightweight steel according to claim 17, wherein the forming the green body based on the powder raw material comprises: mixing the powder raw material with a binder; and molding a mixture of the powder raw material and the binder into the green body through injection molding.

19. The production method for the Fe—Mn—Al—C lightweight steel according to claim 18, wherein before the sintering the green body, the production method further comprises: degreasing the green body to remove a part of binder in the green body.

20. The production method for the Fe—Mn—Al—C lightweight steel according to claim 17, wherein the performing the heat treatment on the sintered body comprises: performing solution treatment on the sintered body; and aging the sintered body obtained after the solution treatment.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0050] FIG. 1 is a schematic diagram of a structure of a terminal according to an embodiment of this application; and

[0051] FIG. 2 is a schematic flowchart of a production method for Fe—Mn—Al—C lightweight steel according to an embodiment of this application.

[0052] Descriptions of reference numerals of main elements

TABLE-US-00001 Terminal 100 First part 110 Second part 130 Rotating shaft 20

DESCRIPTION OF EMBODIMENTS

[0053] The following describes embodiments of this application with reference to the accompanying drawings in embodiments of this application.

[0054] Structural parts of a consumer electronics product are usually small precision parts, have complex three-dimensional curved-surface structure, and are required for smooth operation and structural reliability of a mechanism. Therefore, there are multi-dimensional requirements for a material. In addition to requirements for a light weight/low density, at least strength (for example, yield strength and tensile strength), plastic toughness (for example, elongation), molding processes (casting, forging, stamping, computer numerical control (CNC), and the like) are included. Dimensions constrain each other.

[0055] A terminal in embodiments of this application includes Fe—Mn—Al—C lightweight steel. The terminal is a consumer electronics product, and includes structural parts, and at least one of the structural part includes the Fe—Mn—Al—C lightweight steel. The Fe—Mn—Al—C lightweight steel has advantages of low density/a light weight, high strength, and being capable of being produced by using a metal injection molding process. The metal injection molding process is suitable for production of small and complex precision curve parts due to a molding characteristic of the metal injection molding process.

[0056] For example, as shown in FIG. 1, a terminal 100 is a foldable mobile phone, including a first part 110 and a second part 130 that are collapsible and a rotating shaft 20 disposed between the first part 110 and the second part 130. The first part 110 and the second part 130 rotate relative to each other by using the rotating shaft 20. A material of the rotating shaft 20 is Fe—Mn—Al—C lightweight steel. It may be understood that the Fe—Mn—Al—C lightweight steel is not limited to forming the rotating shaft of the foldable mobile phone, and may be alternatively a camera decorating part of the mobile phone or another type of structural part in the mobile phone. The Fe—Mn—Al—C lightweight steel may also be used to form a structural part in another consumer electronics product. It may be understood that the Fe—Mn—Al—C lightweight steel may be further applied to a vehicle as an in-vehicle mechanical part.

[0057] The Fe—Mn—Al—C lightweight steel in this embodiment of this application includes the following chemical components (the following range values include end values):

[0058] Fe, where a weight percentage of the Fe is greater than or equal to 50.4 wt %;

[0059] Mn whose weight percentage is 25-35 wt %;

[0060] Al whose weight percentage is 6-12 wt %;

[0061] C whose weight percentage is 0.8-2.0 wt %; and

[0062] O whose weight percentage is 0.005-0.6 wt %.

[0063] The lightweight steel further optionally includes Si, Ni, and Cr, a weight percentage of the Si is ≤0.2 wt %, a weight percentage of the Ni is ≤0.6 wt %, and a weight percentage of the Cr is ≤0.4 wt %.

[0064] The lightweight steel further optionally includes at least one of Cu, V, Ti, Nb, W, Zr, Mo, and Re, and a total weight percentage of Cu, V, Ti, Nb, W, Zr, Mo, and Re is ≤1 wt %.

[0065] It may be understood that the lightweight steel may further include another inevitable impurity element, but the another inevitable impurity element has extremely low content and may be ignored.

[0066] The lightweight steel has low density of 5.9-7.0 g/cm.sup.3. Compared with density 7.98 g/cm.sup.3 of a conventional steel material, a weight of the lightweight steel is reduced by approximately 25% to 14%. Therefore, a weight of a consumer electronics product such as a mobile phone can be greatly reduced, so that user experience is improved. In addition, the lightweight steel has high strength and yield strength of 800-1200 MPa. Plastic toughness is high, and elongation reaches 2% to 20%.

[0067] The Fe—Mn—Al—C lightweight steel may be formed by using a powder raw material and a metal injection molding process. As shown in FIG. 2, a production method for the Fe—Mn—Al—C lightweight steel specifically includes the following steps.

[0068] S1: Produce a powder raw material, where the powder raw material includes the following chemical components:

[0069] 28 wt %≤Mn≤35 wt %, 6 wt %≤Al≤12 wt %, 0.7 wt %≤C≤1.8 wt %, 0.003 wt %≤O≤0.4 wt %, 0≤Si≤0.2 wt %, 0≤Ni≤0.6 wt %, 0≤Cr≤0.4 wt %, and 0≤Cu+V+Ti+Nb+W+Zr+Mo+Re≤1 wt %, and the rest is Fe, where Cu+V+Ti+Nb+W+Zr+Mo+Re means that at least one of Cu, V, Ti, Nb, W, Zr, Mo, and Re is included and indicates a total weight percentage of Cu, V, Ti, Nb, W, Zr, Mo, and Re.

[0070] S2: Form a green body based on the powder raw material.

[0071] S3: Sinter the green body to form a sintered body.

[0072] S4: Perform heat treatment on the sintered body.

[0073] The forming a green body based on the powder raw material includes: mixing the powder raw material with a binder; and molding a mixture of the powder raw material and the binder into the green body through injection molding (into a mold cavity).

[0074] Before the sintering the green body, the production method further includes: degreasing the green body to remove a part of binder in the green body.

[0075] The performing heat treatment on the sintered body includes: performing solution treatment on the sintered body; and aging the sintered body obtained after the solution treatment.

[0076] The degreasing refers to a process of removing, by using a method such as catalyzing, heating, or dissolving before the sintering processing, most organic binders in the green body formed through injection molding.

[0077] The binder is an alloy powder-specific binder, and is usually an organic binder. The binder is used to bind the powder raw material into a whole for ease of subsequent injection molding.

[0078] The sintering refers to a process of converting a powdered material (the powder raw material described in this application) into a dense body and enabling, through heating, molecules or atoms in a solid to obtain sufficient energy to migrate, so that particles are bonded on the powder body, thereby generating strength and causing densification and recrystallization. For example, the sintering in this embodiment of this application may be performing heating to 1200° C. to 1300° C. and preserving the heat for 0.5 h to 3 h. During sintering, the binder is removed.

[0079] The solution treatment refers to a heat treatment process in which an alloy (a product sintered in this application) is heated to a high-temperature single-phase region and is kept at a constant temperature, so that an excess phase is fully dissolved in a solid solution and then quickly cooled to obtain a supersaturated solid solution. A purpose of the solution treatment is to dissolve a carbide, a y′ phase, and the like in a matrix to obtain a uniform supersaturated solid solution, so that uniformly distributed fine strengthening phases such as the carbide and the y′ phase are precipitated again during aging. In addition, stress caused by cooling and heating processing is eliminated, so that the alloy is recrystallized. For example, the solution treatment in this embodiment of this application may be performed for 0.5-4 h at a temperature of 980° C. to 1150° C.

[0080] The aging refers to a heat treatment process in which a product obtained after the solution treatment in this application is placed at a high temperature or a room temperature to maintain a shape and a size of the product and to change performance with time. For example, the aging in this embodiment of this application may be performed for 0.5-36 h at a temperature of 450° C. to 600° C.

[0081] In this embodiment of this application, the powder raw material may be produced by using an atomization method, a reduction method, a mechanical polishing method, or the like. A particle diameter distribution range of the powder raw material, a binder system and ratio, a degreasing manner, and the like use a conventional manner in the art, and may be adjusted accordingly as required.

[0082] The chemical components and a ratio of the powder raw material are controlled, and the metal injection molding process is used to obtain components and performance of the Fe—Mn—Al—C lightweight steel disclosed in this application. In addition, a specific process parameter of the metal injection molding process is selected and adjusted, so that it is possible that density of the lightweight steel is further reduced and strength and plastic toughness are improved.

[0083] In this embodiment of this application, the powder raw material includes the following chemical components:

[0084] 28 wt %≤Mn≤35 wt %, 6 wt %≤Al≤12 wt %, 0.7 wt %≤C≤1.8 wt %, 0.003 wt %≤O≤0.4 wt %, 0≤Si≤0.2 wt %, 0≤Ni≤0.6 wt %, 0≤Cr≤0.4 wt %, and 0≤Cu+V+Ti+Nb+W+Zr+Mo+Re≤1 wt %, and the rest is Fe. Cu+V+Ti+Nb+W+Zr+Mo+Re means that at least one of Cu, V, Ti, Nb, W, Zr, Mo, and Re is included and indicates a total weight percentage of Cu, V, Ti, Nb, W, Zr, Mo, and Re.

[0085] The powder raw material may be usually produced by using two methods. In one method, pre-alloying is performed to obtain powder, and all elements exist in an alloy form. In the other method, a plurality of simple-substance elements or compounds are still obtained by mixing a plurality of simple-substance elements or compounds based on an adjusted proportion. In this embodiment of this application, oxygen (O) may exist in a form of iron oxide, aluminum oxide, chromium oxide, or the like, or microscopically, oxygen atoms exist in gaps of metal atoms (for example, Fe).

[0086] The C element in the powder raw material forms a carbide strengthening phase to improve strength of the steel material. The Cu may be used as a dispersed phase. The Cr improves corrosion resistance to some extent. The O forms strengthening, and may be adjusted during sintering. The Si is used to improve activity of the C, and promote dissolution of the C element in a precipitate during aging. The Ni helps refine grains. As studied, the Ni is enriched at a second-phase interface.

[0087] A main crystal structure of the lightweight steel is austenite, and main strengthening phases include a strengthening phase of an intermetallic compound type, for example, FeMn, FeAl, or Fe.sub.3Al and a carbide strengthening phase such as MC.sub.3, M.sub.7C.sub.3, or M.sub.23C.sub.6 (where M represents a metal element). An oxide strengthening phase is creatively introduced to components of the lightweight steel in this embodiment of this application, and is mainly a strengthening phase formed by oxygen and aluminum. In a conventional melting steel material, oxygen is an impurity element and needs to be controlled.

[0088] A functional coating may be formed on a surface of the Fe—Mn—Al—C lightweight steel as required. The coating may be formed by using a process such as passivation, electroplating, spraying, or physical vapor deposition (PVD).

[0089] An embodiment of this application further provides a steel mechanical part (not shown in the figure). The steel mechanical part is molded by using the foregoing production method. The steel mechanical part is produced by using the foregoing method, so that the steel mechanical part has low density, high strength, and high elongation. The steel mechanical part is difficult to break and deform, and has a long service life.

[0090] An embodiment of this application further provides a steel mechanical part (not shown in the figure). A material used by the steel mechanical part includes the foregoing Fe—Mn—Al—C lightweight steel. The material used by the steel mechanical part includes the Fe—Mn—Al—C lightweight steel, so that strength of the steel mechanical part is improved. Therefore, reliability of the steel mechanical part is further ensured without increasing a thickness of the steel mechanical part, to facilitate miniaturization of the steel mechanical part.

[0091] An embodiment of this application further provides an electronic device (not shown in the figure). The electronic device includes the foregoing steel mechanical part. The steel mechanical part is applied to the electronic device, so that a risk that the steel mechanical part in the electronic device falls off and breaks and deforms during use is reduced, thereby improving quality of the electronic device. In addition, strength of the steel mechanical part is high. Therefore, reliability of the steel mechanical part is ensured without increasing a thickness of the steel mechanical part, to facilitate miniaturization of the electronic device. In addition, the steel mechanical part has a light weight, so that miniaturization of the electronic device is facilitated.

[0092] The following further describes the production method for the Fe—Mn—Al—C lightweight steel in embodiments of this application by using a specific embodiment.

[0093] Step 1: Produce alloy powder by using an atomization method. A particle diameter D50 of the powder is 5-15 μm (a particle diameter of 50% of particles is 5-15 μm), and D90 is ≤45 μm (a particle diameter of 90% of the particles is ≤45 μm). A total of seven groups of different alloy powder raw materials are produced. For chemical components of the powder, refer to powder embodiments 1 to 7 in Table 1. A weight percentage of Fe is not listed in Table 1, and the weight percentage of Fe is obtained by subtracting a weight percentage of all other elements from 1 in each powder component.

[0094] Step 2: Fully mix the seven groups of powder with a binder at a volume ratio of 56:44 at 180° C. to produce seven feeders. A weight ratio of components of the used binder, namely, polyformaldehyde (POM), ethylene-vinyl acetate (EVA), polyethylene (PE), ceresin wax (CW), and stearic acid (SA) is 85:1:5.5:2:1.

[0095] Step 3: Place the seven groups of feeders in an injection molding machine, and separately inject the seven groups of feeders into a mold cavity to mold seven groups of green bodies; and use a catalytic degreasing process for the molded green bodies at a temperature of 130° C., to remove a part of binder in the green bodies. A catalyst is fuming nitric acid.

[0096] Step 4: Sequentially perform high-temperature sintering of 2 h to 3 h, solution treatment of 1 h, and aging of 2 h on each group of green bodies to obtain at least one sample (lightweight steel). For a specific sintering temperature, solution treatment temperature, and aging temperature corresponding to each sample (lightweight steel), refer to Table 2. For example, a sample 1-1 is obtained through sintering by performing heating to 1200° C.±5° C. and preserving heat for 2 h to 3 h, solution treatment of 1 h at a temperature of 1100° C.±5° C., and aging of 2 h at a temperature of 500° C.±5° C.

[0097] For details of chemical components of the samples (lightweight steel), refer to Table 1. Sintering, solution treatment, and aging are performed on each group of powder raw materials in the first to the sixth groups to finally obtain three to five samples (lightweight steel) whose chemical components are different, and differences in chemical components are mainly caused by differences in process parameters of sintering, solution treatment, and aging. The seventh group of powder raw materials corresponds to one sample (lightweight steel).

TABLE-US-00002 TABLE 1 wt % Mn Al C Si O Ni Cr Cu V Nb W Zr Mo Re Powder 28 6.7 0.8 0.13 0.018 0.03 0.35 0.05 0.04 0.2  0.01  0.1 \ \ embodiment 1 Sample 1-1 25.2 6.2 0.8 0.14 0.006 0.03 0.35 0.05 0.04 0.12 0.008 0.006 \ \ Sample 1-2 26.7 6.7 1.2 0.18 0.01 0.43 0.2 0.04 0.04 0.14 0.008 0.11 \ \ Sample 1-3 27.7 6.7 1.4 0.17 0.38 0.55 0.21 0.01 0.02 0.2  0.01  0.08 \ \ Powder 34.8 7.6 1.6 0.14 0.038 0.002 0.25 0.04 0.02 0.4  \ \ \ 0.03 embodiment 2 Sample 2-1 34.5 7.1 1.4 0.14 0.01 0.002 0.28 0.04 0.02 0.26 \ \ \ 0.01 Sample 2-2 32.7 7.5 1.9 0.13 0.26 0.002 0.24 0.043 0.004 0.33 \ \ \ 0.02 Sample 2-3 29.3 7.7 1.4 0.11 0.26 0.004 0.27 0.043 0.02 0.42 \ \ \ 0.02 Powder 29.7 8.7 0.8 0.03 0.38 0.58 0.16 0.02 0.004 \ \ 0.1 0.12 \ embodiment 3 Sample 3-1 29.1 8.3 0.8 0.03 0.26 0.51 0.16 0.02 0.01 \ \ 0.008 0.08 \ Sample 3-2 27.5 8.5 0.8 0.02 0.36 0.55 0.08 0.03 0.045 \ \ 0.02 0.11 \ Sample 3-3 28.7 8.7 1.2 0.03 0.56 0.49 0.35 0.006 0.04 \ \ 0.08 0.10 \ Powder 32.3 9.1 0.9 0.083 0.21 0.008 0.32 0.01 0.013 0.26 \ \ \ \ embodiment 4 Sample 4-1 30 9 0.9 0.06 0.21 0.008 0.32 0.01 0.04 0.33 \ \ \ \ Sample 4-2 31.7 9.1 1.1 0.08 0.36 0.003 0.18 0.004 0.014 0.23 \ \ \ \ Sample 4-3 26.1 9.2 1.1 0.07 0.32 0.003 0.13 0.02 0.006 0.22 \ \ \ \ Sample 4-4 28.9 9.2 0.9 0.08 0.34 0.005 0.28 0.03 0.038 0.18 \ \ \ \ Powder 32.2 10.5 1.1 0.032 0.22 0.27 0.07 0.006 0.026 \ \ \ \ 0.03 embodiment 5 Sample 5-1 29.5 9.9 1.2 0.012 0.36 0.24 0.08 0.004 0.01 \ \ \ \ 0.02 Sample 5-2 33.7 9.9 1.2 0.036 0.12 0.32 0.03 0.01 0.04 \ \ \ \ 0.04 Sample 5-3 31.5 10.4 1.3 0.033 0.12 0.23 0.008 0.03 0.04 \ \ \ \ 0.01 Sample 5-4 30.5 10.2 0.9 0.028 0.11 0.24 0.06 0.006 0.02 \ \ \ \ 0.04 Sample 5-5 31.9 10.1 1.4 0.03 0.26 0.3 0.02 0.03 0.04 \ \ \ \  0.008 Powder 34 11.8 1.8 0.002 0.009 0.37 0.02 0.01 0.023 \ \ 0.07 \ \ embodiment 6 Sample 6-1 26.5 11.9 1.8 0.004 0.01 0.36 0.023 0.01 0.004 \ \ 0.06 \ \ Sample 6-2 33.4 12 1.7 0.002 0.28 0.25 0.002 0.037 0.02 \ \ 0.008 \ \ Sample 6-3 30.6 11.2 1.4 0.003 0.006 0.31 0.03 0.05 0.01 \ \ 0.05 \ \ Sample 6-4 31.7 11.5 1.9 0.003 0.32 0.42 0.016 0.01 0.05 \ \ 0.03 \ \ Powder 30 7.7 0.72 0.13 0.22 0.55 0.12 \ \ \ \ \ \ \ embodiment 7 Sample 7-1 30 7.2 0.77 0.12 0.21 0.51 0.1 \ \ \ \ \ \ \

[0098] Performance, including density, yield strength, and elongation, of all obtained samples (lightweight steel) is detected. For details of test results of the samples (lightweight steel), refer to Table 2. For example, density of the sample 1-1 is 6.96 g/cm.sup.3, yield strength of the sample 1-1 is 881 MPa, and elongation of the sample 1-1 is 12%.

TABLE-US-00003 TABLE 2 Solution Yield Sintering treatment Aging Density strength Elongation Embodiment ° C. ° C. ° C. g/cm.sup.3 MPa % Sample 1-1 1200 1100 500 6.96 881 12 Sample 1-2 1280 1150 550 6.8 959 10 Sample 1-3 1300 1080 550 6.82 930 10 Sample 2-1 1250 1050 450 6.72 1023 3 Sample 2-2 1200 1100 600 6.83 1118 2 Sample 2-3 1280 1120 520 6.55 964 6 Sample 3-1 1300 1120 500 6.38 820 6 Sample 3-2 1250 1120 550 6.43 936 7 Sample 3-3 1200 980 500 6.48 961 5 Sample 4-1 1280 1080 550 6.34 1045 9 Sample 4-2 1300 980 550 6.38 1063 10 Sample 4-3 1250 1080 550 6.37 815 16 Sample 4-4 1280 1080 550 6.42 846 18 Sample 5-1 1280 1060 550 6.27 972 14 Sample 5-2 1300 1060 550 6.25 1115 6 Sample 5-3 1250 1060 480 6.12 1176 6 Sample 5-4 1250 1070 480 6.21 1090 15 Sample 5-5 1280 1070 480 6.11 1187 4 Sample 6-1 1300 1000 480 6.02 976 3 Sample 6-2 1250 1100 450 6.02 1100 2 Sample 6-3 1250 1120 490 6.11 860 3 Sample 6-4 1250 1100 490 5.98 950 2 Sample 7-1 1250 1080 560 6.57 970 8

[0099] As can be learned from the above, lightweight steel whose density is 5.9-7.0 g/cm.sup.3, yield strength is 800-1200 MPa, and elongation is 2% to 20% can be obtained through powder sintering and subsequent heat treatment manners of solution treatment and aging. This is mainly attributed to sintering molding and introduction of an oxide strengthening phase that are brought by allocation of material components.

[0100] It should be noted that the foregoing descriptions are merely specific implementations of this application, but are not intended to limit the protection scope of this application. Any change or replacement readily figured out by a person skilled in the art within the technical scope disclosed in this application shall fall within the protection scope of this application. The implementations of this application and features in the implementations may be mutually combined without conflicting. Therefore, the protection scope of this application shall be subject to the protection scope of the claims.