Ultra-high strength steel, method for manufacturing the same, electronic device structural member, and electronic device

Abstract

The application provides a preparation method of ultrahigh-strength steel, comprising the following steps: mixing alloy powder and a binder, and then performing close mixing and granulation to obtain a feedstock; performing injection, degreasing and sintering on the feedstock to obtain a preformed material; and performing heat treatment on the preformed material to obtain the ultrahigh-strength steel, wherein the ultrahigh-strength steel comprises 16wt%-19wt% of Ni, 7.5wt%-11.5wt% of Co, 5wt%-7wt% of Mo, 0.2wt%-0.8wt% of V, 0.1wt%-1wt% of Cr, less than or equal to 0.025wt% of C, 0.0215wt%-0.3wt% of O and the balance of Fe. The preparation method is simple in operation and can be used to prepare ultrahigh-strength steel with excellent performance. The application further provides the ultrahigh-strength steel, an electronic device structure and an electronic device.

Description

Technical Field

[0001] This application belongs to the field of electronic product technology, specifically relating to ultra-high strength steel and its preparation method, electronic device structural components, and electronic devices. Background Technology

[0002] Ultra-high strength steel refers to steel with a yield strength greater than 1180 MPa and a tensile strength greater than 1380 MPa. Due to its superior strength, it is widely used. However, ultra-high strength steel is relatively hard and difficult to process, which limits its application. Furthermore, its performance needs further improvement. Summary of the Invention

[0003] In view of this, this application provides ultra-high strength steel and its preparation method, electronic device structural components, and electronic devices.

[0004] In a first aspect, this application provides a method for preparing ultra-high strength steel, comprising:

[0005] The alloy powder is mixed with the binder and then granulated by kneading to obtain the feed.

[0006] The feed is injected, degreased, and sintered to obtain a preformed material;

[0007] The prefabricated material is heat-treated to obtain ultra-high strength steel, the chemical composition of which includes 16wt% to 19wt% Ni, 7.5wt% to 11.5wt% Co, 5wt% to 7wt% Mo, 0.2wt% to 0.8wt% V, 0.1wt% to 1wt% Cr, less than or equal to 0.025wt% C, 0.0215wt% to 0.3wt% O and the balance Fe.

[0008] Secondly, this application provides an ultra-high strength steel, the chemical composition of which includes 16wt% to 19wt% Ni, 7.5wt% to 11.5wt% Co, 5wt% to 7wt% Mo, 0.2wt% to 0.8wt% V, 0.1wt% to 1wt% Cr, less than or equal to 0.025wt% C, 0.0215wt% to 0.3wt% O, and the balance Fe.

[0009] Thirdly, this application provides an electronic device structural component, the material of which includes ultra-high strength steel prepared by the preparation method described in the first aspect or ultra-high strength steel described in the second aspect.

[0010] Fourthly, this application provides an electronic device including the electronic device structure described in the third aspect.

[0011] The method for preparing ultra-high strength steel provided in this application is simple and easy to operate. This method can obtain ultra-high strength steel of the desired shape, shortening the processing flow and reducing manufacturing costs. Simultaneously, it can produce ultra-high strength steel with excellent plasticity. Electronic device structural components made with this ultra-high strength steel exhibit good overall performance, improving the service life of electronic devices and enhancing their product competitiveness. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments of this application will be described below.

[0013] Figure 1 This is a flowchart illustrating a method for preparing ultra-high strength steel according to an embodiment of this application.

[0014] Figure 2 This is a particle size distribution diagram of the alloy powder provided in one embodiment of this application.

[0015] Figure 3 This is a electron microscope image of the fracture surface of ultra-high strength steel obtained according to one embodiment of this application.

[0016] Figure 4 The image shows a fracture surface electron microscope (EM) image of ultra-high strength steel obtained according to another embodiment of this application.

[0017] Figure 5 A flowchart illustrating a method for preparing ultra-high strength steel according to another embodiment of this application.

[0018] Figure 6 A flowchart illustrating the fabrication method of an electronic device structural component provided in one embodiment of this application.

[0019] Figure 7 A front view of an electronic device provided according to an embodiment of this application.

[0020] Figure 8 The image shows the metallographic diagram of the preform material prepared in Experiment 1 of Example 1.

[0021] Figure 9 The image shows the metallographic diagram of the preform material prepared in Experiment 2 of Example 1.

[0022] Figure 10 The image shows the metallographic diagram of the preform material prepared in Experiment 3 of Example 1.

[0023] Figure 11 Metallographic images of the preforms prepared in Example 2 are shown below. (a) is the metallographic image of the preforms prepared in Experiment 1 of Example 2, (b) is the metallographic image of the preforms prepared in Experiment 2 of Example 2, and (c) is the metallographic image of the preforms prepared in Experiment 3 of Example 2.

[0024] Figure 12 This is an electron microscope image of the alloy powder prepared in Experiment 1 of Example 5.

[0025] Figure 13 The image shows the metallographic structure of the preform material prepared in Experiment 1 of Example 5.

[0026] Figure 14 The image shows the metallographic structure of the preform material prepared in Experiment 1 of Example 6. Detailed Implementation

[0027] The following are exemplary embodiments of this application. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principles of this application, and these improvements and modifications are also considered to be within the scope of protection of this application.

[0028] The following disclosure provides many different implementations or examples for implementing the technical solutions of this application. To simplify the disclosure, specific example settings are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various implementations and / or settings discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0029] Please see Figure 1 The flowchart below shows a method for preparing ultra-high strength steel according to an embodiment of this application, including:

[0030] S101: The alloy powder and binder are mixed and then granulated by kneading to obtain the feed.

[0031] S102: The precast material is obtained after the feed is injected, degreased and sintered.

[0032] S103: The precast material is heat-treated to obtain ultra-high strength steel. The chemical composition of the ultra-high strength steel includes 16wt% to 19wt% Ni, 7.5wt% to 11.5wt% Co, 5wt% to 7wt% Mo, 0.2wt% to 0.8wt% V, 0.1wt% to 1wt% Cr, less than or equal to 0.025wt% C, 0.0215wt% to 0.3wt% O and the balance Fe.

[0033] In related technologies, steel can be machined to obtain the desired shape. However, due to the high strength of steel, machining is difficult, time-consuming, and yields a low pass rate, leading to a significant increase in manufacturing costs and sometimes making it impossible to obtain products that meet dimensional accuracy requirements. The ultra-high strength steel preparation method provided in this application can directly obtain ultra-high strength steel of the desired shape through intensive mixing and granulation, injection molding, debinding, sintering, and heat treatment. This avoids further processing of the ultra-high strength steel, improves the pass rate, reduces manufacturing costs, and the ultra-high strength steel obtained by this method has excellent comprehensive properties, which is beneficial for its application.

[0034] In S101, the feed material is obtained by mixing alloy powder and binder, kneading and granulating, which is beneficial for subsequent injection.

[0035] In this embodiment, the particle size D50 of the alloy powder is 7.5 μm to 9.5 μm. A particle size D50 of 7.5 μm to 9.5 μm is beneficial for improving the density and porosity of the preform material, facilitating subsequent decarburization, reducing shrinkage before and after sintering, and contributing to increased strength of the resulting ultra-high strength steel while minimizing dimensional and shape changes. Specifically, the particle size D50 of the alloy powder can be, but is not limited to, 7.5 μm, 7.75 μm, 7.8 μm, 7.95 μm, 8 μm, 8.1 μm, 8.25 μm, 8.35 μm, 8.4 μm, 8.45 μm, 8.47 μm, 8.5 μm, 8.7 μm, 8.9 μm, 9 μm, 9.1 μm, 9.3 μm, or 9.45 μm. In some embodiments of this application, the particle size D50 of the alloy powder can be from 8.5 μm to 9.5 μm. In some embodiments of this application, the particle size D50 of the alloy powder can be from 7.5 μm to 7.95 μm. In one embodiment, under the same process conditions, the shrinkage rate of the alloy powder with a particle size D50 of 7.5 μm before and after sintering is 0.1% to 0.3% greater than that of the alloy powder with a particle size D50 of 9.5 μm before and after sintering. Controlling the particle size of the alloy powder is beneficial to improving the shrinkage rate before and after sintering, improving the performance of the obtained ultra-high strength steel, and reducing changes in size and shape, which helps to obtain ultra-high strength steel with excellent performance and shape requirements.

[0036] In the embodiments of this application, the particle size D10 of the alloy powder is less than 5 μm, the particle size D50 is 7.5 μm to 9.5 μm, and the particle size D90 is 17 μm to 23 μm. This is beneficial for obtaining precast materials with small grain size and low porosity, further improving the performance of the precast materials, and helping to obtain ultra-high strength steel with low carbon content and good strength. Specifically, the particle size D10 of the alloy powder can be, but is not limited to, 2μm, 2.8μm, 3μm, 3.1μm, 3.18μm, 3.3μm, 3.5μm, 4μm, 4.3μm, 4.4μm or 4.7μm, etc., and the particle size D90 can be, but is not limited to, 17μm, 17.5μm, 17.7μm, 18μm, 18.3μm, 18.7μm, 18.9μm, 19.5μm, 20.5μm, 20.7μm, 21μm, 21.5μm, 21.8μm, 22μm, 22.4μm, 22.9μm or 23μm, etc. In some embodiments of this application, the particle size D10 of the alloy powder can be less than or equal to 3.18 μm, the particle size D50 can be 7.5 μm to 9.5 μm, and the particle size D90 can be 17 μm to 23 μm. In some embodiments of this application, the particle size D10 of the alloy powder can be less than or equal to 3.18 μm, the particle size D50 can be 7.5 μm to 9.5 μm, and the particle size D90 can be 17 μm to 18.9 μm. In some embodiments of this application, the particle size D10 of the alloy powder can be less than or equal to 3.18 μm, the particle size D50 can be 7.5 μm to 9.5 μm, and the particle size D90 can be 20.5 μm to 23 μm. In some embodiments of this application, the particle size D10 of the alloy powder can be less than or equal to 3.18 μm, the particle size D50 can be 8.5 μm to 9.5 μm, and the particle size D90 can be 17 μm to 23 μm. In some embodiments of this application, the particle size D10 of the alloy powder can be less than or equal to 3.18 μm, the particle size D50 can be from 8.5 μm to 9.5 μm, and the particle size D90 can be from 17 μm to 18.9 μm. In some embodiments of this application, the particle size D10 of the alloy powder can be less than or equal to 3.18 μm, the particle size D50 can be from 8.5 μm to 9.5 μm, and the particle size D90 can be from 20.5 μm to 23 μm. In some embodiments of this application, the particle size D10 of the alloy powder can be less than or equal to 3.18 μm, the particle size D50 can be from 7.5 μm to 7.95 μm, and the particle size D90 can be from 17 μm to 23 μm. In some embodiments of this application, the particle size D10 of the alloy powder can be less than or equal to 3.18 μm, the particle size D50 can be 7.5 μm to 7.95 μm, and the particle size D90 can be 17 μm to 18.9 μm.In some embodiments of this application, the particle size D10 of the alloy powder can be less than or equal to 3.18 μm, the particle size D50 can be from 7.5 μm to 7.95 μm, and the particle size D90 can be from 20.5 μm to 23 μm. In this application, the particle size distribution of the alloy powder can be detected by a laser particle size analyzer. D50 in this application refers to the volume median diameter. Please refer to [link / reference]. Figure 2 The image shows the particle size distribution of the alloy powder provided in one embodiment of this application. The curve that first increases and then decreases is the frequency curve, which is a normal distribution curve. The curve that continuously increases is the cumulative curve. The particle size of the alloy powder is D10 of 2.9 μm, D50 of 8.33 μm, and D90 of 18.9 μm. Using this alloy powder is beneficial for producing ultra-high strength steel with tensile strength greater than 1900 MPa, yield strength greater than 1800 MPa, and hardness greater than 500 HV.

[0037] In this embodiment of the application, the tap density of the alloy powder is greater than 4.4 g / cm³. 3 This is beneficial for improving the density of subsequent precast materials, thereby increasing the strength and hardness of the resulting ultra-high strength steel. Specifically, the particle size and sphericity of the alloy powder can be controlled to obtain a tap density greater than 4.4 g / cm³. 3 The alloy powder is used to ensure the production of ultra-high strength steel with superior performance. Specifically, the tap density of the alloy powder can be, but is not limited to, greater than 4.41 g / cm³. 3 Greater than 4.42 g / cm 3 Greater than 4.43 g / cm 3 Greater than 4.44 g / cm 3 Greater than 4.45 g / cm 3 Greater than 4.46 g / cm 3 Greater than 4.47 g / cm 3 Greater than 4.48 g / cm 3 Greater than 4.49 g / cm 3 Greater than 4.5 g / cm 3 Greater than 4.51 g / cm 3 Greater than 4.52 g / cm 3 or greater than 4.53 g / cm 3 In some embodiments of this application, the tap density of the alloy powder can be greater than 4.45 g / cm³. 3 .

[0038] In this embodiment, the carbon content in the alloy powder is less than or equal to 0.035 wt%. Controlling the carbon content can increase the density after sintering, which is beneficial for promoting the transformation of austenite to martensite and the formation of plate martensite during sintering, thereby improving the strength and plasticity of ultra-high strength steel. Specifically, the carbon content in the alloy powder can be, but is not limited to, less than or equal to 0.035 wt%, less than or equal to 0.033 wt%, less than or equal to 0.031 wt%, less than or equal to 0.03 wt%, less than or equal to 0.028 wt%, less than or equal to 0.027 wt%, less than or equal to 0.025 wt%, less than or equal to 0.023 wt%, less than or equal to 0.022 wt%, less than or equal to 0.02 wt%, etc.

[0039] In this embodiment, the oxygen content in the alloy powder is 0.1 wt% to 1 wt%, which is beneficial for subsequent decarburization, reduces the carbon content in the ultra-high strength steel, and also reduces the shrinkage rate before and after sintering, improves the strength of the ultra-high strength steel, and ensures that the dimensions of the obtained ultra-high strength steel do not change significantly. Specifically, the oxygen content in the alloy powder can be, but is not limited to, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt%, 0.26 wt%, 0.3 wt%, 0.35 wt%, 0.4 wt%, 0.47 wt%, 0.5 wt%, 0.57 wt%, 0.59 wt%, 0.6 wt%, 0.63 wt%, 0.7 wt%, 0.75 wt%, 0.8 wt%, 0.88 wt%, 0.9 wt%, or 0.92 wt%. In some embodiments of this application, the oxygen content in the alloy powder can be 0.1 wt% to 0.8 wt%. In some embodiments of this application, the oxygen content in the alloy powder can be from 0.2 wt% to 0.6 wt%. In some embodiments of this application, the oxygen content in the alloy powder can be from 0.25 wt% to 0.49 wt%.

[0040] In this application embodiment, the alloy powder inevitably contains impurity elements, and the content of these impurity elements in the alloy powder is less than or equal to 0.7 wt%. By controlling the content of impurity elements in the alloy powder, their influence on the performance of ultra-high strength steel can be avoided, which is beneficial for obtaining ultra-high strength steel with excellent performance. Specifically, the content of impurity elements in ultra-high strength steel may be, but is not limited to, less than or equal to 0.7 wt%, less than or equal to 0.6 wt%, less than or equal to 0.5 wt%, less than or equal to 0.4 wt%, less than or equal to 0.3 wt%, less than or equal to 0.2 wt%, etc. In some embodiments of this application, the impurity elements include at least one of sulfur, manganese, and silicon. In some embodiments of this application, the content of sulfur in the alloy powder is less than or equal to 0.02 wt%. Specifically, the sulfur content in the alloy powder may be, but is not limited to, less than or equal to 0.02 wt%, less than or equal to 0.015 wt%, less than or equal to 0.013 wt%, less than or equal to 0.01 wt%, less than or equal to 0.009 wt%, less than or equal to 0.008 wt%, less than or equal to 0.006 wt%, less than or equal to 0.005 wt%, less than or equal to 0.003 wt%, etc. In some embodiments of this application, the manganese content in the alloy powder is less than or equal to 0.1 wt%. Specifically, the manganese content in the alloy powder may be, but is not limited to, less than or equal to 0.1 wt%, less than or equal to 0.08 wt%, less than or equal to 0.07 wt%, less than or equal to 0.06 wt%, less than or equal to 0.05 wt%, less than or equal to 0.04 wt%, less than or equal to 0.03 wt%, etc. In some embodiments of this application, the silicon content in the alloy powder is less than or equal to 0.5 wt%. Specifically, the silicon content in the alloy powder can be, but is not limited to, less than or equal to 0.5 wt%, less than or equal to 0.45 wt%, less than or equal to 0.4 wt%, less than or equal to 0.39 wt%, less than or equal to 0.37 wt%, less than or equal to 0.35 wt%, less than or equal to 0.33 wt%, less than or equal to 0.31 wt%, less than or equal to 0.29 wt%, less than or equal to 0.23 wt%, less than or equal to 0.22 wt%, less than or equal to 0.2 wt%, etc.

[0041] In some embodiments of this application, the chemical composition of the alloy powder includes 16 wt% to 19 wt% nickel, 7.5 wt% to 11.5 wt% cobalt, 5 wt% to 7 wt% molybdenum, 0.2 wt% to 0.8 wt% vanadium, 0.1 wt% to 1 wt% chromium, less than or equal to 0.035 wt% carbon, 0.1 wt% to 1 wt% oxygen, and the balance iron. In some embodiments of this application, the chemical composition of the alloy powder includes 16 wt% to 19 wt% nickel, 7.5 wt% to 11.5 wt% cobalt, 5 wt% to 7 wt% molybdenum, 0.2 wt% to 0.8 wt% vanadium, 0.1 wt% to 1 wt% chromium, less than or equal to 0.035 wt% carbon, 0.1 wt% to 1 wt% oxygen, and unavoidable impurity elements and the balance iron.

[0042] In this embodiment, the binder includes polyethylene, vinyl acetate polymer, and polyoxymethylene (POM). POM can decompose into water and gas under the action of nitric acid, exhibiting excellent removal efficiency. The content of POM in the binder is adjusted by adding polyethylene. The vinyl acetate polymer acts as the binder, and both polyethylene and vinyl acetate polymer can be removed during sintering, avoiding carbon residue. In some embodiments of this application, the binder includes 3 wt% to 5.5 wt% polyethylene, 2 wt% to 6 wt% vinyl acetate polymer, and the balance being POM. Specifically, the content of polyethylene in the binder can be, but is not limited to, 3 wt%, 3.2 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 4.7 wt%, 5 wt%, 5.2 wt%, or 5.4 wt%, etc., and the content of vinyl acetate polymer in the binder can be, but is not limited to, 2 wt%, 2.5 wt%, 3 wt%, 4 wt%, 5 wt%, 5.5 wt%, or 6 wt%. For example, the binder comprises 3 wt% to 4 wt% polyethylene, 4 wt% to 6 wt% vinyl acetate polymer, and the balance polyoxymethylene; or the binder comprises 4 wt% to 5.5 wt% polyethylene, 2 wt% to 5 wt% vinyl acetate polymer, and the balance polyoxymethylene; or the binder comprises 3.5 wt% to 4.5 wt% polyethylene, 3 wt% to 5.5 wt% vinyl acetate polymer, and the balance polyoxymethylene. Other additives may also be present in the binder. In some embodiments of this application, the binder further comprises 1 wt% to 2.5 wt% of an antioxidant to avoid the influence of oxygen during the preparation process. Specifically, the antioxidant content in the binder may be, but is not limited to, 1 wt%, 1.5 wt%, 1.8 wt%, 2 wt%, 2.3 wt%, or 2.5 wt%, etc. In some embodiments of this application, the adhesive comprises 3 wt% to 5.5 wt% polyethylene, 2 wt% to 6 wt% vinyl acetate polymer, 1 wt% to 2.5 wt% antioxidant, and 86 wt% to 90 wt% polyoxymethylene. In some embodiments of this application, the adhesive is obtained by mixing the components of the above-mentioned adhesive (such as polyoxymethylene, polyethylene, vinyl acetate polymer, antioxidant, etc.) at 150°C to 160°C (such as 150°C, 153°C, 155°C, 156°C, 158°C, or 160°C, etc.) for 90 min to 150 min (such as 90 min, 95 min, 100 min, 105 min, 110 min, 115 min, 120 min, 130 min, 140 min, or 150 min, etc.).

[0043] In this embodiment, the volume ratio of binder to alloy powder when mixed is 0.53:1 to 0.82:1, which is beneficial for obtaining injection feedstock, improving the density after sintering, and enhancing the performance of the preform, thereby contributing to the acquisition of high-performance ultra-high-strength steel. Specifically, the volume ratio of binder to alloy powder when mixed can be, but is not limited to, 0.53:1, 0.55:1, 0.57:1, 0.6:1, 0.63:1, 0.65:1, 0.67:1, 0.7:1, 0.75:1, 0.78:1, 0.8:1, or 0.82:1. In one embodiment of this application, the volume percentage of alloy powder in the mixture formed by alloy powder and binder is 55% to 65%, and the volume percentage of binder is 35% to 45%. Specifically, the volume percentage of alloy powder in the mixture may be, but is not limited to, 55%, 57%, 58%, 60%, 61%, 63%, 64%, or 65%, and the volume percentage of binder may be, but is not limited to, 36%, 38%, 39%, 40%, 41%, 43%, or 45%.

[0044] In this application embodiment, the internal mixing granulation includes processing at 150°C to 160°C for 90 to 120 minutes. Specifically, the internal mixing granulation temperature can be, but is not limited to, 150°C, 152°C, 154°C, 155°C, 156°C, 157°C, 158°C, or 160°C, etc., and the internal mixing granulation time can be, but is not limited to, 90 minutes, 95 minutes, 100 minutes, 105 minutes, 110 minutes, 115 minutes, or 120 minutes, etc. In this application, the internal mixing granulation can be, but is not limited to, carried out in an internal mixer.

[0045] In this application, the melt flow index of the feedstock can be from 1000 g / 10 min to 1700 g / 10 min to ensure its fluidity, which is beneficial for injection molding. It also improves the shrinkage rate before and after sintering, which helps reduce the dimensional differences in the resulting ultra-high strength steel and increases the yield rate. Specifically, the melt flow index of the feedstock can be from 1000 g / 10 min to 1350 g / 10 min, 1200 g / 10 min to 1450 g / 10 min, 1300 g / 10 min to 1500 g / 10 min, or 1450 g / 10 min to 1650 g / 10 min, etc. In this application, the melt flow index is obtained under testing conditions of 190°C and 21.5 kg. In some embodiments of this application, when the melt flow index of the feedstock is from 1000 g / 10 min to 1700 g / 10 min, the shrinkage rate after injection molding, debinding, and sintering is 1.135-1.195. In this application, the shrinkage rate is the ratio between the diameters of the ingot-shaped preforms after injection and the diameter of the preform after sintering. Specifically, the shrinkage rate may be, but is not limited to, 1.135, 1.14, 1.145, 1.15, 1.155, 1.16, 1.17, 1.18, or 1.19.

[0046] In S102, this application uses metal injection molding (MIM) to obtain preformed materials. The feedstock undergoes injection molding, and the injection mold can be set according to the desired shape of the ultra-high strength steel, thereby avoiding the need for processing the ultra-high strength steel, improving the yield rate of ultra-high strength steel preparation, and enabling the preparation of ultra-high strength steel of different sizes and shapes. This is particularly beneficial for the preparation and use of ultra-high strength steel with high dimensional precision and thinness. The degreasing process removes volatile and easily decomposed components from the feedstock, reducing carbon and oxygen content. Sintering further enhances density, contributing to the acquisition of high-performance ultra-high strength steel.

[0047] In this embodiment, the injection temperature is 170°C to 220°C, the pressure is 130MPa to 230MPa, and the mold cavity temperature is 100°C to 140°C. Specifically, the injection temperature can be, but is not limited to, 170°C, 180°C, 190°C, 200°C, 210°C, or 220°C, etc.; the pressure can be, but is not limited to, 130MPa, 150MPa, 165MPa, 180MPa, 190MPa, 200MPa, 210MPa, 220MPa, or 230MPa, etc.; and the mold cavity temperature can be, but is not limited to, 100°C, 110°C, 120°C, 130°C, or 140°C, etc. In this embodiment, a preform is obtained after injection, and the density of the preform is greater than 5.35 g / cm³. 3 This is beneficial for improving the density of the sintered precast material and enhancing the performance of ultra-high strength steel. Specifically, the density of the billet can be, but is not limited to, greater than 5.35 g / cm³.3 Greater than 5.38 g / cm 3 Greater than 5.39 g / cm 3 Greater than 5.4 g / cm 3 Greater than 5.44 g / cm 3 Greater than 5.45 g / cm 3 Greater than 5.47 g / cm 3 Greater than 5.48 g / cm 3 or greater than 5.5 g / cm 3 wait.

[0048] In this application, polyoxymethylene (POM) is removed by degreasing. In embodiments of this application, degreasing includes heating to 105°C to 125°C and holding at that temperature for 4 to 10 hours in a nitric acid and inert gas atmosphere. By using a nitric acid atmosphere, the nitric acid reacts with the POM, removing it from the binder. The reaction products are gas and water, leaving no residue in the material. Furthermore, nitric acid is volatile and will not remain in the material. An inert gas is introduced to prevent oxygen from affecting the alloy powder. The inert gas can be, but is not limited to, nitrogen or argon. Specifically, the degreasing temperature can be, but is not limited to, 108°C, 110°C, 112°C, 115°C, 120°C, 123°C, 124°C, or 125°C, and the degreasing time can be, but is not limited to, 5 hours, 6 hours, 8 hours, 9 hours, or 10 hours. In some embodiments of this application, the rate of nitric acid introduction during degreasing is 0.5 L / min to 3 L / min, and the rate of inert gas introduction is 60 L / min to 120 L / min. Specifically, the rate of nitric acid introduction can be, but is not limited to, 0.5 L / min, 1 L / min, 1.5 L / min, 2 L / min, 2.5 L / min, or 3 L / min, and the rate of inert gas introduction can be, but is not limited to, 60 L / min, 80 L / min, 100 L / min, 110 L / min, or 120 L / min. In the embodiments of this application, the degreasing rate is greater than 7.7%, thereby ensuring the removal of organic components. The degreasing rate is the ratio of the weight reduction before and after degreasing to the weight before degreasing.

[0049] In this application, decarburization is achieved through sintering to obtain a high-density preform, which generates austenite and transforms into martensite. During the martensitic transformation, the large number of high-density dislocations aggregated increase the difficulty of dislocation movement, thus playing a strengthening role. In the embodiments of this application, sintering includes treatment at 1360°C to 1400°C for 3 to 6 hours, resulting in lower carbon and oxygen content and smaller grain size in the preform, thereby improving the hardness and density of the preform. Specifically, the sintering temperature can be, but is not limited to, 1360°C, 1370°C, 1380°C, 1385°C, 1390°C, 1395°C, or 1400°C, and the sintering time can be, but is not limited to, 3 hours, 4 hours, 5 hours, or 6 hours. In some embodiments of this application, sintering includes treatment at 1360°C to 1380°C for 4 to 6 hours. In some embodiments of this application, sintering includes treatment at 1370°C to 1390°C for 3 to 5 hours.

[0050] In this application, the hardness of the prefabricated material is between 250 HV and 330 HV, which improves the hardness, strength, and plasticity of the resulting ultra-high-strength steel, resulting in ultra-high-strength steel with excellent comprehensive performance. Specifically, the hardness of the prefabricated material can be, but is not limited to, 250 HV, 260 HV, 275 HV, 280 HV, 290 HV, 300 HV, 310 HV, 320 HV, or 330 HV. In some embodiments of this application, the hardness of the prefabricated material can be between 260 HV and 315 HV, which is beneficial for further improving the performance of the resulting ultra-high-strength steel.

[0051] In this embodiment of the application, the density of the precast material is greater than or equal to 7.85 g / cm³. 3 This helps to improve the hardness of the precast material and obtain ultra-high strength steel with excellent performance. Specifically, the density of the precast material can be, but is not limited to, greater than or equal to 7.85 g / cm³. 3 ≥7.88 g / cm³ 3 ≥7.9g / cm 3 ≥7.93 g / cm³ 3 ≥7.95g / cm 3 ≥7.97 g / cm³ 3 ≥7.98 g / cm³ 3 ≥8g / cm 3 ≥8.05 g / cm³ 3 ≥8.1 g / cm 3 ≥8.12 g / cm 3 wait.

[0052] In this embodiment, the carbon content of the precast material is less than or equal to 0.025 wt%, which facilitates the transformation of austenite to martensite, promotes the formation of plate martensite, improves the hardness and density of the precast material, and reduces the shrinkage rate before and after sintering, thus contributing to the improvement of the hardness and plasticity of ultra-high strength steel. Specifically, the carbon content of the precast material may be, but is not limited to, less than or equal to 0.025 wt%, less than or equal to 0.024 wt%, less than or equal to 0.022 wt%, less than or equal to 0.02 wt%, less than or equal to 0.018 wt%, less than or equal to 0.017 wt%, less than or equal to 0.015 wt%, less than or equal to 0.01 wt%, less than or equal to 0.008 wt%, less than or equal to 0.005 wt%, etc. In one embodiment, when the carbon content in the alloy powder is 0.008wt%-0.017wt%, a preform is obtained after sintering at 1385℃ for 4 hours. The preform has a carbon content of 0.002wt%-0.006wt% and a density of 7.93 g / cm³. 3 The shrinkage rate before and after sintering was 1.168%. In another embodiment, when the carbon content in the alloy powder was 0.023wt%-0.029wt%, a preform was obtained after sintering at 1385℃ for 4 hours. The carbon content of the preform was 0.015wt%-0.021wt%, and the density was 7.89 g / cm³. 3 The shrinkage rate before and after sintering was 1.163. In another embodiment, when the carbon content in the alloy powder was 0.037wt%-0.04wt%, a preform was obtained after sintering at 1385℃ for 4 hours. The carbon content of the preform was 0.026wt%-0.028wt%, and the density was 7.78 g / cm³. 3 The shrinkage rate before and after sintering was 1.58. In another embodiment, when the carbon content in the alloy powder was 0.042wt%-0.053wt%, a preform was obtained after sintering at 1385℃ for 4 hours. The carbon content of the preform was 0.031wt%-0.035wt%, and the density was 7.69 g / cm³. 3 The shrinkage rate before and after sintering is 1.54. In this application, the shrinkage rate is calculated by measuring the diameter of the disc-shaped preform formed after injection molding and the diameter of the disc-shaped preform after sintering; the ratio of the two is the shrinkage rate. It can be seen that when the carbon content of the preform is less than or equal to 0.025 wt%, the density after sintering is high, and the shrinkage rate is appropriate, which can effectively prevent excessive shrinkage before and after sintering from affecting the performance of the preform and ultra-high strength steel.

[0053] In this embodiment of the application, the oxygen content of the prefabricated material is 0.0215wt% to 0.3wt%, which is beneficial to decarburization and does not affect the performance of the prefabricated material and ultra-high strength steel. It helps to improve the strength of ultra-high strength steel and can effectively reduce the shrinkage rate and improve the yield of ultra-high strength steel. Specifically, the oxygen content of the precast material may be, but is not limited to, 0.022wt%, 0.023wt%, 0.025wt%, 0.028wt%, 0.03wt%, 0.035wt%, 0.037wt%, 0.04wt%, 0.042wt%, 0.045wt%, 0.048wt%, 0.05wt%, 0.055wt%, 0.06wt%, 0.07wt%, 0.1wt%, 0.13wt%, 0.15wt%, 0.18wt%, 0.2wt%, 0.24wt%, 0.25wt%, 0.27wt%, 0.28wt%, or 0.3wt%. In one embodiment, when the oxygen content in the alloy powder is 0.37 wt%, a preform is obtained after sintering at 1385°C for 4 hours. The preform has an oxygen content of 0.022 wt% and a density of 7.94 g / cm³. 3 The shrinkage rate before and after sintering was 1.168%. In another embodiment, when the oxygen content in the alloy powder was 0.48 wt%, a preform was obtained after sintering at 1385°C for 4 hours. The oxygen content of the preform was 0.035 wt%, and the density was 7.93 g / cm³. 3 The shrinkage rate before and after sintering was 1.167. In another embodiment, when the oxygen content in the alloy powder was 0.78 wt%, a preform was obtained after sintering at 1385°C for 4 hours. The oxygen content of the preform was 0.112 wt%, and the density was 7.85 g / cm³. 3 The shrinkage rate before and after sintering was 1.162. In another embodiment, when the oxygen content in the alloy powder was 1.22 wt%, a preform was obtained after sintering at 1385°C for 4 hours. The oxygen content of the preform was 0.324 wt%, and the density was 7.8 g / cm³. 3 The shrinkage rate before and after sintering was 1.158. It can be seen that when the oxygen content in the precast material is too high, the density of the precast material decreases, which will affect the strength of the ultra-high strength steel. Controlling the oxygen content of the precast material to 0.0215wt% to 0.3wt% is beneficial to improving the comprehensive performance of the ultra-high strength steel.

[0054] In this embodiment, the grain size of the precast material is less than or equal to 250 μm. In this application, the precast material is examined using a metallographic microscope, and seven grain sizes are randomly selected. After removing the maximum and minimum values, the average value of the remaining grains is calculated as the grain size value. A grain size of less than 250 μm in the precast material helps to mitigate grain boundary slip during stress, thereby avoiding brittle fracture and improving the performance and service life of the ultra-high strength steel. Specifically, the grain size of the precast material can be, but is not limited to, less than or equal to 240 μm, less than or equal to 230 μm, less than or equal to 220 μm, less than or equal to 210 μm, less than or equal to 200 μm, less than or equal to 190 μm, less than or equal to 180 μm, less than or equal to 170 μm, etc. In one embodiment, when the grain size of the precast material is less than 250 μm, the fracture surface electron microscope image of the obtained ultra-high strength steel is as follows. Figure 3 As shown, where Figure 3 Images (a) and (b) are from different locations, with a scale bar of 50 μm; when the grain size of the prefabricated material is greater than 300 μm, the fracture surface electron micrograph of the obtained ultra-high strength steel is shown in Figure 1. Figure 4 As shown, where Figure 4 In the middle (a) and (b), the figures are at different locations, with scale bars of 100 μm and 200 μm, respectively; Figure 4 Ultra-high strength steel exhibits brittle fracture and poor plasticity. Figure 3 Ultra-high strength steel does not undergo brittle fracture and has good plasticity.

[0055] In S103, high-strength steel with excellent performance is obtained through heat treatment. In the embodiments of this application, the heat treatment includes solution treatment, cryogenic treatment, and aging treatment in sequence. Through solution treatment, alloying elements, impurity elements, and impurity phases are dissolved in the iron matrix phase and completely transformed into austenite during high-temperature holding. At the same time, some austenite is transformed into martensite through rapid cooling. Through cryogenic treatment, the content of residual austenite is minimized, thereby improving the strength of the material. Through aging treatment, a large number of dispersed intermetallic compounds precipitate in the supersaturated solid solution. The intermetallic compounds hinder the movement of dislocations, playing a strengthening role and significantly improving strength while minimizing the loss of toughness and plasticity.

[0056] In this embodiment, the solution treatment includes treatment at 920°C to 1020°C for 35 to 70 minutes, which is beneficial for further refining the grains and improving the strengthening effect. Specifically, the solution treatment temperature can be, but is not limited to, 920°C, 935°C, 940°C, 950°C, 985°C, 990°C, 1000°C, 1010°C, or 1020°C, etc., and the solution treatment time can be, but is not limited to, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 60 minutes, or 70 minutes, etc. Solution treatment can be carried out under vacuum conditions or an inert atmosphere to prevent the influence of oxygen on the material. In this embodiment, after the solution treatment, the temperature is lowered at a rate greater than or equal to 20°C / min to increase the martensite transformation. Specifically, the cooling rate after the solution treatment can be, but is not limited to, 20°C / min, 25°C / min, 30°C / min, 40°C / min, or 50°C / min, etc.

[0057] In this application embodiment, cryogenic treatment includes treatment at -196°C to -160°C for 25 to 60 minutes. Cryogenic treatment is beneficial for generating more martensite and reducing the content of retained austenite. Specifically, the cryogenic treatment temperature can be, but is not limited to, -196°C, -195°C, -190°C, -185°C, -180°C, -170°C, -165°C, or -160°C, etc., and the cryogenic treatment time can be, but is not limited to, 25 minutes, 30 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, or 60 minutes, etc. In some embodiments of this application, cryogenic treatment is performed in liquid nitrogen. In this application embodiment, the hardness of the preform after cryogenic treatment is 280 HV-340 HV. Specifically, the hardness of the preform after cryogenic treatment can be, but is not limited to, 280 HV, 290 HV, 300 HV, 310 HV, 320 HV, 330 HV, or 340 HV, etc.

[0058] In this application's embodiments, the aging treatment includes treatment at 470°C to 520°C for 3 to 6 hours, which helps in the precipitation and uniform distribution of the dispersed phase, further enhancing the strengthening effect. Simultaneously, a small amount of reverse-transformed austenite is formed, improving plasticity. Specifically, the aging treatment temperature can be, but is not limited to, 470°C, 475°C, 485°C, 490°C, 500°C, 510°C, or 515°C, and the aging treatment time can be, but is not limited to, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, or 6 hours. In some embodiments of this application, nitrogen cooling can be performed after the aging treatment.

[0059] The method for preparing ultra-high strength steel provided in this application allows for control of the shape of the injection mold according to actual production needs, thereby obtaining ultra-high strength steel of the required shape, eliminating processing steps, reducing costs and preparation difficulty, and also obtaining ultra-high strength steel with excellent performance, which is beneficial for its use, especially as structural parts with precision dimensions and shapes or small dimensions and shapes.

[0060] Please see Figure 5 The flowchart of a method for preparing ultra-high strength steel according to another embodiment of this application includes:

[0061] S201: Iron source, nickel source, cobalt source, molybdenum source and vanadium source are mixed and melted, and then atomized to obtain alloy powder.

[0062] S202: The alloy powder is mixed with the binder and then granulated by kneading to obtain the feed.

[0063] S203: The precast material is obtained after the feed is injected, degreased and sintered.

[0064] S204: The precast material is heat-treated to obtain ultra-high strength steel. The chemical composition of the ultra-high strength steel includes 16wt% to 19wt% Ni, 7.5wt% to 11.5wt% Co, 5wt% to 7wt% Mo, 0.2wt% to 0.8wt% V, 0.1wt% to 1wt% Cr, less than or equal to 0.025wt% C, 0.0215wt% to 0.3wt% O and the balance Fe.

[0065] S202, S203 and S204 are described in S101, S102 and S103 above, and will not be repeated here.

[0066] In S201, the raw materials are mixed and melted, then atomized and granulated to form alloy powder. The amount of each raw material added during mixing and melting can be determined based on the content of each element in the ultra-high strength steel. During the mixing and melting process, the element content can be detected and compared with the required element content in the ultra-high strength steel to determine whether it is necessary to add one or more raw materials, thereby ensuring that the element content in the obtained ultra-high strength steel meets the requirements.

[0067] In the embodiments of this application, the iron source, nickel source, cobalt source, molybdenum source, or vanadium source may be, but is not limited to, elemental iron, elemental nickel, elemental cobalt, elemental molybdenum, or elemental vanadium; the purity of the iron source, nickel source, cobalt source, molybdenum source, and vanadium source is greater than 99.5%, greater than 99.7%, greater than 99.8%, greater than 99.88%, greater than 99.9%, or greater than 99.99%, etc. In the embodiments of this application, the iron source, nickel source, cobalt source, molybdenum source, or vanadium source may be, but is not limited to, iron-containing alloys, nickel-containing alloys, cobalt-containing alloys, molybdenum-containing alloys, or vanadium-containing alloys. It is understood that other elements in the above alloys can be selected as needed, but it is necessary to ensure that the content of each element in the obtained ultra-high strength steel meets the requirements. In some embodiments of this application, the elements of an iron source, nickel source, cobalt source, molybdenum source, and vanadium source are analyzed after being mixed and melted. The mixture contains 16 wt% to 19 wt% Ni, 7.5 wt% to 11.5 wt% Co, 5 wt% to 7 wt% Mo, 0.2 wt% to 0.8 wt% V, 0.1 wt% to 1 wt% Cr, and more than 59 wt% Fe. In this application, the raw materials may contain chromium to ensure the chromium content in the resulting ultra-high strength steel.

[0068] In this embodiment, atomization is performed under an inert atmosphere to prevent oxidation of the alloy by oxygen. Specifically, alloy powder can be obtained through water-air combined atomization. For example, based on the content of each element in ultra-high strength steel, iron, nickel, cobalt, and molybdenum sources are mixed and melted. The molten metal is poured into an atomizer, first broken into droplets by high-pressure gas, and then formed into alloy powder by high-pressure water flow. The alloy powder can be spherical or near-spherical. Water-air combined atomization can produce alloy powder with good sphericity and uniform particle dispersion, which is beneficial to improving the tap density of the alloy powder and thus improving the overall performance of ultra-high strength steel. In this application, the obtained alloy powder can also be sieved to obtain alloy powder with the desired particle size range or particle size distribution, which helps to further improve the performance of the produced ultra-high strength steel.

[0069] This application provides an ultra-high strength steel. The chemical composition of the ultra-high strength steel includes 16 wt% to 19 wt% Ni, 7.5 wt% to 11.5 wt% Co, 5 wt% to 7 wt% Mo, 0.2 wt% to 0.8 wt% V, 0.1 wt% to 1 wt% Cr, less than or equal to 0.025 wt% C, 0.0215 wt% to 0.3 wt% O, and the balance Fe. The ultra-high strength steel provided by this application has high yield strength and tensile strength, high surface hardness, good elongation, and suitable elastic modulus. Its comprehensive performance is excellent, which is beneficial for its application. Understandably, wt% is a weight percentage, meaning that the chemical composition of ultra-high strength steel includes 16% to 19% Ni, 7.5% to 11.5% Co, 5% to 7% Mo, 0.2% to 0.8% V, 0.1% to 1% Cr, less than or equal to 0.025% C, and 0.0215% to 0.3% O by weight.

[0070] In this application, iron (Fe) is used as the basic element of ultra-high strength steel to ensure its fundamental properties. Specifically, the iron content in the ultra-high strength steel can be, but is not limited to, greater than or equal to 60 wt%, greater than or equal to 62 wt%, greater than or equal to 65 wt%, greater than or equal to 66 wt%, greater than or equal to 67 wt%, greater than or equal to 68 wt%, or greater than or equal to 69 wt%. In some embodiments of this application, the iron content in the ultra-high strength steel is between 60 wt% and 71.3 wt%, which is beneficial for ensuring the performance of the ultra-high strength steel. In some embodiments of this application, the iron content in the ultra-high strength steel can be between 61 wt% and 70 wt%. In some embodiments of this application, the iron content in the ultra-high strength steel can be between 63 wt% and 68.3 wt%.

[0071] In this application, nickel (Ni) is an austenite-forming element. The addition of nickel is beneficial to the formation of lath martensite, increasing the strength of ultra-high strength steel. Furthermore, nickel can improve the ductility and toughness of ultra-high strength steel, thereby enhancing its overall performance. Too low a nickel content in ultra-high strength steel will affect the formation of lath martensite, reducing its strength; too high a nickel content will affect its ductility. An amount of 16wt% to 19wt% nickel in ultra-high strength steel ensures both strength and ductility, contributing to the acquisition of ultra-high strength steel with excellent overall performance. Specifically, the nickel content in ultra-high strength steel can be, but is not limited to, 16 wt%, 16.24 wt%, 16.5 wt%, 16.67 wt%, 16.81 wt%, 16.9 wt%, 16.95 wt%, 17 wt%, 17.05 wt%, 17.2 wt%, 17.36 wt%, 17.48 wt%, 17.74 wt%, 17.85 wt%, 17.9 wt%, 17.97 wt%, 18 wt%, 18.2 wt%, 18.35 wt%, 18.5 wt%, 18.63 wt%, 18.79 wt%, 18.8 wt%, or 19 wt%. In the embodiments of this application, the Ni content in the ultra-high strength steel is 17 wt% to 18 wt%, which is beneficial for further improving the strength and plasticity of the ultra-high strength steel. Specifically, the nickel content in ultra-high strength steel can be, but is not limited to, 17.05wt% to 18wt%, 17.05wt% to 17.95wt%, 17.1wt% to 17.9wt%, 17.15wt% to 17.89wt%, 17.2wt% to 17.8wt%, 17.3wt% to 17.75wt%, or 17.35wt% to 17.7wt%.

[0072] In this application, cobalt (Co) can promote the complete transformation of austenite into martensite and also promote the precipitation and distribution of molybdenum-containing intermetallic compounds, resulting in a strengthening effect and improving the strength of ultra-high strength steel. Too low a cobalt content in ultra-high strength steel is detrimental to strengthening and affects its strength, while too high a cobalt content affects its plasticity. An amount of 7.5 wt% to 11.5 wt% cobalt in ultra-high strength steel ensures both strength and plasticity, which is beneficial for obtaining ultra-high strength steel with excellent overall performance. Specifically, the cobalt content in ultra-high strength steel can be, but is not limited to, 7.5 wt%, 7.75 wt%, 7.89 wt%, 7.95 wt%, 8 wt%, 8.05 wt%, 8.1 wt%, 8.5 wt%, 8.7 wt%, 9 wt%, 9.2 wt%, 9.8 wt%, 9.9 wt%, 10.5 wt%, 10.7 wt%, 11.2 wt%, or 11.5 wt%. In the embodiments of this application, the Co content in the ultra-high strength steel is 8.5 wt% to 10 wt%, which is beneficial for further improving the strength and plasticity of the ultra-high strength steel. Specifically, the cobalt content in ultra-high strength steel can be, but is not limited to, 7.76wt% to 11wt%, 7.8wt% to 10.8wt%, 7.9wt% to 10.5wt%, 8wt% to 10wt%, 8.05wt% to 9.8wt%, 8.05wt% to 9.8wt%, 8.1wt% to 9.6wt%, or 8.2wt% to 9.5wt%.

[0073] In this application, molybdenum (Mo) is the main strengthening element, promoting precipitation strengthening and improving the overall strength and toughness of ultra-high strength steel, as well as its fracture toughness. Too low a molybdenum content in ultra-high strength steel is detrimental to strengthening and affects its strength, while too high a content affects its plasticity. A molybdenum content of 5 wt% to 7 wt% ensures both improved strength and enhanced plasticity. Specifically, the molybdenum content in ultra-high strength steel can be, but is not limited to, 5.1 wt%, 5.35 wt%, 5.5 wt%, 5.6 wt%, 5.75 wt%, 5.9 wt%, 6 wt%, 6.1 wt%, 6.32 wt%, 6.5 wt%, 6.63 wt%, 6.78 wt%, 6.8 wt%, 6.9 wt%, 6.95 wt%, or 7 wt%. In this embodiment, the Mo content in the ultra-high strength steel is 5.5 wt% to 6.5 wt%, which is beneficial for further improving the elongation and strength of the ultra-high strength steel and enhancing its overall performance. Specifically, the molybdenum content in the ultra-high strength steel can be, but is not limited to, 5.6 wt%, 5.73 wt%, 5.85 wt%, 5.9 wt%, 6 wt%, 6.05 wt%, 6.1 wt%, 6.2 wt%, 6.27 wt%, 6.3 wt%, 6.32 wt%, 6.38 wt%, 6.4 wt%, 6.46 wt%, 6.48 wt%, or 6.5 wt%.

[0074] In this application, vanadium (V) facilitates decarburization, reduces the carbon content in ultra-high strength steel, and improves its performance. A vanadium content of 0.2 wt% to 0.8 wt% ensures carbon removal during the preparation process and also contributes to improved performance. Specifically, the vanadium content in the ultra-high strength steel can be, but is not limited to, 0.2 wt%, 0.26 wt%, 0.3 wt%, 0.33 wt%, 0.4 wt%, 0.45 wt%, 0.5 wt%, 0.58 wt%, 0.6 wt%, 0.66 wt%, 0.7 wt%, 0.73 wt%, or 0.8 wt%. In this embodiment, the V content in the ultra-high strength steel is 0.42 wt% to 0.55 wt%, which further enhances the overall performance of the ultra-high strength steel. Specifically, the vanadium content in ultra-high strength steel can be, but is not limited to, 0.42wt%, 0.43wt%, 0.437wt%, 0.44wt%, 0.442wt%, 0.45wt%, 0.456wt%, 0.46wt%, 0.473wt%, 0.48wt%, 0.49wt%, 0.495wt%, 0.5wt%, 0.51wt%, 0.52wt%, 0.525wt%, 0.53wt%, 0.54wt%, or 0.55wt%.

[0075] In this application, chromium (Cr) in ultra-high strength steel can improve its strength, wear resistance, and corrosion resistance. Excessive chromium content hinders carbon removal during the manufacturing process, increasing the carbon content and reducing the steel's performance. Conversely, insufficient chromium content affects the steel's strength, reduces its surface wear resistance and corrosion resistance, and is detrimental to its use. A chromium content of 0.1 wt% to 1 wt% ensures both effective carbon removal during manufacturing, reducing the carbon content, and maintains the steel's strength, wear resistance, and corrosion resistance, thus enhancing its overall performance. Specifically, the chromium content in ultra-high strength steel can be, but is not limited to, 0.1 wt%, 0.2 wt%, 0.22 wt%, 0.3 wt%, 0.35 wt%, 0.4 wt%, 0.48 wt%, 0.5 wt%, 0.6 wt%, 0.67 wt%, 0.7 wt%, 0.8 wt%, 0.85 wt%, 0.9 wt%, or 1 wt%. In the embodiments of this application, the Cr content in the ultra-high strength steel is from 0.2 wt% to 0.5 wt%, which is beneficial for further improving the overall performance of the ultra-high strength steel. Specifically, the chromium content in ultra-high strength steel can be, but is not limited to, 0.2wt%, 0.21wt%, 0.23wt%, 0.28wt%, 0.3wt%, 0.34wt%, 0.35wt%, 0.39wt%, 0.4wt%, 0.43wt%, 0.45wt%, 0.47wt%, 0.48wt%, or 0.5wt%.

[0076] In this application, an excessively low oxygen (O) content in ultra-high strength steel is detrimental to decarburization, while an excessively high oxygen content affects the performance of ultra-high strength steel. An oxygen content of 0.0215 wt% to 0.3 wt% ensures the removal of carbon during the preparation process, thereby helping to reduce the carbon content in ultra-high strength steel, and also avoids the influence of oxygen on ultra-high strength steel. Specifically, the oxygen content in ultra-high strength steel can be, but is not limited to, 0.0215wt%, 0.0218wt%, 0.022wt%, 0.0223wt%, 0.0225wt%, 0.023wt%, 0.024wt%, 0.025wt%, 0.028wt%, 0.03wt%, 0.034wt%, 0.037wt%, 0.04wt%, 0.05wt%, 0.07wt%, 0.09wt%, 0.1wt%, 0.14wt%, 0.16wt%, 0.2wt%, 0.25wt%, 0.28wt%, or 0.3wt%.

[0077] In this application, the carbon (C) content in the ultra-high strength steel is less than or equal to 0.025 wt%. By controlling the carbon content, the impact on the performance of the ultra-high strength steel can be avoided. Specifically, the carbon content in the ultra-high strength steel may be, but is not limited to, less than or equal to 0.025 wt%, less than or equal to 0.022 wt%, less than or equal to 0.02 wt%, less than or equal to 0.018 wt%, less than or equal to 0.015 wt%, less than or equal to 0.014 wt%, or less than or equal to 0.013 wt%.

[0078] In this application embodiment, the ultra-high strength steel contains unavoidable impurity elements, and the content of these impurity elements is less than or equal to 0.7 wt%. Controlling the content of these impurity elements helps avoid their impact on the performance of the ultra-high strength steel, which is beneficial for its use. Specifically, the content of impurity elements in the ultra-high strength steel can be, but is not limited to, less than or equal to 0.6 wt%, less than or equal to 0.5 wt%, less than or equal to 0.4 wt%, less than or equal to 0.3 wt%, less than or equal to 0.2 wt%, less than or equal to 0.1 wt%, etc. In some embodiments of this application, the impurity elements include at least one of sulfur, manganese, and silicon. It is understood that the ultra-high strength steel in this application may also contain impurity elements other than sulfur, manganese, and silicon, and this is not limited. In some embodiments of this application, the content of sulfur in the ultra-high strength steel is less than or equal to 0.02 wt%. Specifically, the sulfur content in ultra-high strength steel can be, but is not limited to, less than or equal to 0.02 wt%, less than or equal to 0.015 wt%, less than or equal to 0.013 wt%, less than or equal to 0.01 wt%, less than or equal to 0.009 wt%, less than or equal to 0.008 wt%, less than or equal to 0.006 wt%, less than or equal to 0.005 wt%, less than or equal to 0.003 wt%, etc. In some embodiments of this application, the manganese content in ultra-high strength steel is less than or equal to 0.1 wt%. Specifically, the manganese content in ultra-high strength steel can be, but is not limited to, less than or equal to 0.1 wt%, less than or equal to 0.08 wt%, less than or equal to 0.07 wt%, less than or equal to 0.06 wt%, less than or equal to 0.05 wt%, less than or equal to 0.04 wt%, less than or equal to 0.03 wt%, etc. In some embodiments of this application, the silicon content in ultra-high strength steel is less than or equal to 0.5 wt%. Specifically, the silicon content in ultra-high strength steel can be, but is not limited to, less than or equal to 0.5 wt%, less than or equal to 0.45 wt%, less than or equal to 0.4 wt%, less than or equal to 0.39 wt%, less than or equal to 0.37 wt%, less than or equal to 0.35 wt%, less than or equal to 0.33 wt%, less than or equal to 0.31 wt%, less than or equal to 0.29 wt%, less than or equal to 0.23 wt%, less than or equal to 0.22 wt%, less than or equal to 0.2 wt%, etc.

[0079] The ultra-high strength steel described in this application is a martensitic aging steel, which is an ultra-high strength steel that undergoes precipitation hardening of intermetallic compounds during aging. It is strengthened by the dispersed precipitation of these intermetallic compounds and can be prepared using any of the aforementioned methods. In the embodiments of this application, the yield strength of the ultra-high strength steel is greater than or equal to 1800 MPa. Specifically, the yield strength of the ultra-high strength steel can be, but is not limited to, 1820 MPa or higher, 1835 MPa or higher, 1850 MPa or higher, 1880 MPa or higher, 1900 MPa or higher, 1915 MPa or higher, 1930 MPa or higher, 1940 MPa or higher, etc. In the embodiments of this application, the tensile strength of the ultra-high strength steel is greater than or equal to 1900 MPa. Specifically, the tensile strength of ultra-high strength steel can be, but is not limited to, 1900 MPa or higher, 1930 MPa or higher, 1950 MPa or higher, 1975 MPa or higher, 1990 MPa or higher, 2000 MPa or higher, 2020 MPa or higher, 2030 MPa or higher, 2050 MPa or higher, etc. In the embodiments of this application, the elongation of ultra-high strength steel is greater than or equal to 4%. Specifically, the elongation of ultra-high strength steel can be, but is not limited to, 4% or higher, 4.1% or higher, 4.2% or higher, 4.3% or higher, 4.4% or higher, 4.5% or higher, 4.6% or higher, 4.7% or higher, 4.8% or higher, 4.9% or higher, 5% or higher, etc. In the embodiments of this application, the elastic modulus of ultra-high strength steel is 170 GPa to 190 GPa. Specifically, the elastic modulus of ultra-high strength steel can be, but is not limited to, 170 GPa, 173 GPa, 175 GPa, 180 GPa, 185 GPa, 188 GPa, or 190 GPa. In the embodiments of this application, the hardness of ultra-high strength steel is 520 HV to 630 HV. Specifically, the hardness of ultra-high strength steel can be, but is not limited to, 520 HV, 525 HV, 530 HV, 540 HV, 550 HV, 575 HV, 590 HV, 600 HV, 610 HV, 620 HV, or 630 HV. In this application, the yield strength, tensile strength, elongation, and elastic modulus of ultra-high strength steel are tested according to GB / T 228.1-2021; the hardness of ultra-high strength steel is tested using a Vickers hardness tester. The ultra-high strength steel provided in this application has excellent yield strength and tensile strength, high elongation and elastic modulus, and high surface hardness. Its comprehensive performance is excellent and is conducive to the application of ultra-high strength steel.

[0080] This application also provides an electronic device structural component made of ultra-high strength steel, as described in any of the above embodiments. In other words, using ultra-high strength steel to make the electronic device structural component results in good strength, excellent plasticity, and superior overall performance, which is beneficial for improving the performance of the electronic device.

[0081] This application also provides a method for fabricating structural components for electronic devices. Please refer to [link / reference]. Figure 6 The flowchart illustrates a method for fabricating an electronic device structural component according to an embodiment of this application, including:

[0082] S301: The alloy powder and binder are mixed and then granulated by kneading to obtain the feed.

[0083] S302: The precast material is obtained after the feed is injected, degreased and sintered.

[0084] S303: Prefabricated materials are heat-treated to obtain electronic device structural components. The materials of the electronic device structural components include ultra-high strength steel. The chemical composition of ultra-high strength steel includes 16wt% to 19wt% Ni, 7.5wt% to 11.5wt% Co, 5wt% to 7wt% Mo, 0.2wt% to 0.8wt% V, 0.1wt% to 1wt% Cr, less than or equal to 0.025wt% C, 0.0215wt% to 0.3wt% O, and the balance Fe.

[0085] The method for manufacturing electronic device structural components provided in this application can directly form structural components of the required shape, reducing the difficulty of the manufacturing process, improving the yield rate, and facilitating the use of electronic device structural components. The manufacturing method for electronic device structural components can be referred to the description of the manufacturing method for ultra-high strength steel mentioned above, and will not be repeated here.

[0086] In this application, surface treatment can also be performed on electronic device structural components to improve their corrosion resistance, wear resistance, and oxidation resistance. In some embodiments of this application, a coating can be applied to the surface of the electronic device structural components to improve their corrosion resistance and also to alter their appearance. Specifically, coating can be performed, but is not limited to, chemical plating and physical vapor deposition. In one embodiment, a nickel layer can be formed on the surface of the electronic device structural components through chemical plating; the neutral salt spray time of the electronic device structural components with the nickel layer reached 24 hours. The test conditions for the neutral salt spray experiment in this application are as follows: a 4.5% to 5.5% sodium chloride aqueous solution with a pH of 6.5 to 7.2 is sprayed using a spray device, causing the salt spray to settle onto the product under test. The surface corrosion state is observed after a certain period of time in a test chamber. The test chamber temperature is required to be between 33°C and 37°C, the humidity greater than 95%, and the mist drop rate is 1 mL / (h·cm). 2 ) to 2 mL / (h·cm 2 The nozzle pressure ranges from 78.5 kPa to 137.3 kPa (0.8-1.4 kgf / cm²). 2The product can withstand a neutral salt spray test for up to 24 hours, meaning that there is no significant change on the surface of the electronic device structural components after 24 hours of testing. Specifically, the coating thickness can be 1μm-3μm, such as 1.2μm, 1.5μm, 1.7μm, 1.9μm, 2μm, 2.3μm, 2.5μm, 2.7μm, 2.8μm, or 3μm. In some embodiments of this application, the surface of the electronic device structural components can be subjected to manganese phosphating treatment to form a phosphating layer, improving its corrosion resistance and wear resistance. Specifically, the manganese phosphating treatment uses a manganese phosphating solution, which includes manganese salts and phosphates. The manganese salt can be selected from at least one of manganate, manganese sulfate, and manganese chloride, and the phosphate can be selected from at least one of potassium dihydrogen phosphate and trisodium phosphate; the thickness of the phosphating layer can be less than 2μm. In some embodiments of this application, passivation treatment is performed after manganese phosphating treatment. Specifically, passivation treatment can be, but is not limited to, using mineral oil for passivation sealing. In one embodiment, the electronic device structural components are treated with a manganese-based phosphating solution, and then passivated with an oil-based sealant to achieve corrosion protection; the product can withstand a neutral salt spray test of up to 48 hours.

[0087] This application also provides an electronic device, including the aforementioned structural components, which can improve the performance and lifespan of the electronic device and enhance its competitiveness. It is understood that the electronic device may be, but is not limited to, mobile phones, tablets, laptops, watches, MP3 players, MP4 players, GPS navigators, digital cameras, drones, vehicles, etc., and the structural components may be, but are not limited to, the device's housing, frame, buttons, hinges (such as slide rails), gears, support components, protective components, etc. Please refer to [link to relevant documentation]. Figure 7 This is a front view of an electronic device provided in one embodiment of this application. The electronic device 700 includes a flexible screen 710 and a foldable mechanism. The foldable mechanism supports the flexible screen 710 and can cause the flexible screen 710 to fold or unfold when the electronic device is folded or unfolded. The foldable mechanism includes a hinge assembly 721, a first housing 722, and a second housing 723. The first housing 722, the second housing 723, and the flexible screen 710 are connected and enclosed to form an accommodating area. The hinge assembly 721 is disposed within the accommodating area. In one embodiment, the hinge assembly 721 is a structural component of the electronic device in any of the above embodiments, thereby improving the reliability and service life of the electronic device 700. In another embodiment, at least one of the first housing 722 and the second housing 723 can be a structural component of the electronic device in any of the above embodiments, thereby improving the reliability and service life of the electronic device 700.

[0088] The following specific examples further illustrate the effects of the ultra-high strength steel provided in this application.

[0089] Example 1

[0090] Experiment 1

[0091] Iron, nickel, cobalt, molybdenum, and vanadium sources were mixed and melted in a vacuum environment at 1650℃, and alloy powder was prepared by water-gas combined atomization. The tap density of the alloy powder was sieved to achieve a density of 4.5 g / cm³. 3 The particle size D50 is 8.5 μm.

[0092] A binder was prepared by mixing 93 wt% polyoxymethylene, 2.6 wt% antioxidant, 3.4 wt% polyethylene, and 1 wt% vinyl acetate polymer in a kneader at 170°C for 120 min. The binder and alloy powder were mixed at a volume ratio of 45:55 and placed in an internal mixer at 155°C for 100 min to obtain a feedstock with a melt flow index of 1500 g / 10 min. The feedstock was injected into a mold at an injection temperature of 200°C, an injection pressure of 120 MPa, and a mold cavity temperature of 120°C to form a preform. The preform was then heated to 120°C and held for 10 h in nitric acid (2 L / min) and nitrogen (80 L / min) for degreasing to remove polyoxymethylene, achieving a degreasing rate greater than 7.7%. Finally, the preform was sintered at 1385°C for 4 h to obtain the final product.

[0093] The precast material was placed in a vacuum heat treatment furnace and subjected to solution treatment at 940℃ for 60 min. Then it was treated in liquid nitrogen at -196℃ for 60 min and then subjected to aging treatment at 490℃ for 4 h to obtain ultra-high strength steel. The content of each element in the ultra-high strength steel meets the requirements of this application.

[0094] Experiment 2

[0095] Similar to Experiment 1, except that the tap density of the alloy powder is 4.65 g / cm³. 3 The particle size D50 is 7.2 μm.

[0096] Experiment 3

[0097] Similar to Experiment 1, except that the tap density of the alloy powder is 4.38 g / cm³. 3 The particle size D50 is 10.3 μm.

[0098] The preforms prepared in Experiments 1 to 3 of Example 1 were examined using a metallographic microscope, and the results are as follows: Figures 8 to 10 As shown, where, Figure 8 The image shows the metallographic structure of the preform material prepared in Experiment 1 of Example 1. Figure 9 The image shows the metallographic structure of the preform obtained in Experiment 2 of Example 1. Figure 10The image shows the metallographic diagram of the preform material prepared in Experiment 3 of Example 1. Compared with Experiment 2, the grain size of the preform material in Experiment 1 is smaller. Compared with Experiment 3, the porosity of the preform material in Experiment 1 is smaller. The performance of the ultra-high strength steel prepared in Experiment 1 is better than that of the ultra-high strength steel prepared in Experiments 2 and 3.

[0099] Example 2

[0100] Experiment 1

[0101] Iron, nickel, cobalt, molybdenum, and vanadium sources were mixed and melted in a vacuum environment at 1650℃, with the carbon content controlled to be less than 0.035 wt%. Alloy powder was prepared by water-air combined atomization, and the tap density of the alloy powder was achieved to 4.5 g / cm³ through sieving. 3 The particle size D50 is 8.5 μm.

[0102] A binder was prepared by mixing 93 wt% polyoxymethylene, 2.6 wt% antioxidant, 3.4 wt% polyethylene, and 1 wt% vinyl acetate polymer in a kneader at 170°C for 120 min. The binder and alloy powder were mixed at a volume ratio of 45:55 and placed in an internal mixer at 155°C for 100 min to obtain a feedstock with a melt flow index of 1500 g / 10 min. The feedstock was injected into a mold at an injection temperature of 200°C, an injection pressure of 120 MPa, and a mold cavity temperature of 120°C to form a preform. The preform was then heated to 120°C and held for 10 h in nitric acid (2 L / min) and nitrogen (80 L / min) for degreasing to remove polyoxymethylene, achieving a degreasing rate greater than 7.7%. Finally, the preform was sintered at 1385°C for 4 h to obtain a preform with a carbon content of 0.002 wt% to 0.006 wt%.

[0103] The precast material was placed in a vacuum heat treatment furnace and subjected to solution treatment at 940℃ for 60 min. Then it was treated in liquid nitrogen at -196℃ for 60 min and then subjected to aging treatment at 490℃ for 4 h to obtain ultra-high strength steel. The content of each element in the ultra-high strength steel meets the requirements of this application.

[0104] Experiment 2

[0105] Similar to Experiment 1, except that the carbon content in the raw materials was adjusted to be between 0.024 wt% and 0.0025 wt% in the prefabricated material.

[0106] Experiment 3

[0107] Similar to Experiment 1, except that the carbon content in the raw materials was adjusted to be between 0.036 wt% and 0.0037 wt% in the prefabricated material.

[0108] The preforms prepared in Experiments 1 to 3 of Example 2 were examined using a metallographic microscope, and the results are as follows: Figure 11 As shown, where, Figure 11 (a) is the metallographic image of the preform material prepared in Experiment 1 of Example 2, (b) is the metallographic image of the preform material prepared in Experiment 2 of Example 2, and (c) is the metallographic image of the preform material prepared in Experiment 3 of Example 2. It can be seen that a lower carbon content is conducive to promoting the formation of plate martensite, while a higher carbon content makes the austenite grain boundaries more obvious. The elongation of the ultra-high strength steel prepared in Experiments 1 and 2 is better than that of the ultra-high strength steel prepared in Experiment 3.

[0109] Example 3

[0110] Experiments 1-6

[0111] Using the preparation conditions of Experiment 1 in Example 1, ultra-high strength steel was prepared. The test results of the alloy powders of Experiments 1-6 in Example 3 are shown in Table 1. The properties of the precast materials after sintering and the properties of the ultra-high strength steel are shown in Table 2. Two parallel experiments were conducted to test the hardness, tensile strength, yield strength, elongation and elastic modulus and the average value was calculated. The results in Table 2 are the average values.

[0112] Table 1. Test results of alloy powder in Example 3

[0113]

[0114]

[0115] Table 2 shows the test results of prefabricated materials and ultra-high strength steel in Example 3.

[0116]

[0117] Among them, the contents of Ni, Co, Mo, V, and Cr in the obtained ultra-high strength steel are the same as those in the alloy powder, and the carbon content in the ultra-high strength steel is the same as that in the precast material. As can be seen from Tables 1 and 2, the excessive carbon content in the alloy powder of Experiments 1-2 resulted in excessive carbon content in both the precast material and the ultra-high strength steel, leading to excessive hardness in the precast material, a significant decrease in the elongation of the ultra-high strength steel, and a reduction in strength, thus affecting the overall performance of the ultra-high strength steel. In Experiments 3-6, by controlling the carbon content in the alloy powder, the carbon content in the obtained precast material and ultra-high strength steel was low, meeting the carbon content requirements for ultra-high strength steel in this application, and the obtained ultra-high strength steel exhibited excellent overall performance.

[0118] Example 4

[0119] Experiment 1

[0120] Using the preparation conditions of Experiment 1 in Example 1, ultra-high strength steel was prepared. The alloy powder contained 17.51 ​​wt% nickel, 9.31 wt% cobalt, 6.02 wt% molybdenum, 0.53 wt% vanadium, 0.41 wt% chromium, 0.014 wt% carbon, 0.33 wt% oxygen, 0.006 wt% sulfur, 0.04 wt% manganese, 0.33 wt% silicon, and the balance iron. The powder particle size D50 is 8.21μm; the ultra-high strength steel contains 17.51wt% nickel, 9.31wt% cobalt, 6.02wt% molybdenum, 0.53wt% vanadium, 0.41wt% chromium, less than 0.014wt% carbon, oxygen in the range of 0.0215wt% to 0.3wt%, 0.006wt% sulfur, 0.04wt% manganese, 0.33wt% silicon, and the balance iron.

[0121] Experiment 2

[0122] The experiment was largely the same as Experiment 1, except that the aging conditions were 520℃ for 4 hours.

[0123] The tensile strength, yield strength, elongation, elastic modulus and hardness of the ultra-high strength steels obtained in Experiment 1 and Experiment 2 were tested. Six parallel experiments were conducted on each sample and the average value was calculated. The results are shown in Table 3.

[0124] Table 3 shows the test results of ultra-high strength steel in Example 4.

[0125]

[0126] It can be seen that both Experiment 1 and Experiment 2 in Example 4 can produce ultra-high strength steel with high tensile strength, high yield strength, good elongation, high elastic modulus, and excellent hardness, which is beneficial for the application of ultra-high strength steel. Compared with Experiment 2, the ultra-high strength steel obtained by Experiment 1 has better strength and can be used in applications with strict strength requirements. Compared with Experiment 1, the ultra-high strength steel obtained by Experiment 2 has better elongation performance and can be used in applications with strict elongation performance requirements. Therefore, the ultra-high strength steel provided in this application has excellent comprehensive performance and can be applied to different application scenarios.

[0127] Example 5

[0128] Experiment 1

[0129] Iron, nickel, cobalt, molybdenum, and vanadium sources were mixed and melted in a vacuum environment at 1650℃. The resulting alloy powder was prepared by water-air combined atomization. The alloy powder contained 17.42 wt% nickel, 8.5 wt% cobalt, 6.3 wt% molybdenum, 0.55 wt% vanadium, 0.21 wt% chromium, 0.014 wt% carbon, 0.29 wt% oxygen, 0.003 wt% sulfur, 0.08 wt% manganese, 0.31 wt% silicon, and the balance iron. The tap density of the alloy powder was 4.47 g / cm³ after sieving. 3 The particle size D10 is 3.11 μm, the particle size D50 is 8.47 μm, and the particle size D90 is 21.57 μm; please refer to [link / reference]. Figure 12 The image shown is an electron microscope image of the alloy powder prepared in Experiment 1 of Example 5. Figure 12 The four images in the image show the results of four sampling tests, which can be seen that the alloy powder has good sphericity and relatively uniform powder distribution.

[0130] A binder was prepared by mixing 92.3 wt% polyoxymethylene, 2.6 wt% antioxidant, 3.4 wt% polyethylene, 1 wt% vinyl acetate polymer, and other additives in a kneader at 170°C for 120 min. The binder and alloy powder were mixed at a volume ratio of 45:55 and then internally mixed in a mixer to obtain a feedstock with a melt flow index of 1351 g / 10 min. The feedstock was injected into a mold at an injection temperature of 200°C, an injection pressure of 120 MPa, and a mold cavity temperature of 120°C to form a preform with a density of 5.45 g / cm³. 3 The blank was placed in nitric acid and nitrogen atmosphere and heated to 120℃ for 10 hours for degreasing treatment to remove polyoxymethylene, with a degreasing rate of 7.79%. Then, it was sintered at 1385℃ for 4 hours under an argon atmosphere to obtain the preform. The preform was examined using a metallographic microscope, and the results are as follows: Figure 13 As shown, the grain size of the preform material is less than 200 μm, and the density of the preform material is greater than 7.93 g / cm³. 3 The carbon content is 0.006 wt%, and the oxygen content is 0.028 wt%.

[0131] The precast material was placed in a vacuum heat treatment furnace and solution treated at 980℃ for 60 minutes, followed by cooling. The hardness after solution treatment was 285HV-295HV. Then, it was treated in liquid nitrogen at -196℃ for 60 minutes, followed by aging treatment at 490℃ for 4 hours to obtain ultra-high strength steel. The ultra-high strength steel contained 17.42wt% nickel, 8.5wt% cobalt, 6.3wt% molybdenum, 0.55wt% vanadium, 0.21wt% chromium, less than 0.014wt% carbon, 0.0215wt%-0.28wt% oxygen, 0.003wt% sulfur, 0.08wt% manganese, 0.31wt% silicon, and the balance iron.

[0132] Experiment 2

[0133] The experiment was largely the same as Experiment 1, except that the aging conditions were 520℃ for 4 hours.

[0134] Experiment 3

[0135] Similar to Experiment 1, except that the tap density of the alloy powder was adjusted to 4.31 g / cm³. 3 .

[0136] The tensile strength, yield strength, elongation, elastic modulus and hardness of the ultra-high strength steels obtained in Experiments 1-3 were tested. Each sample was tested in three parallel experiments and the average value was calculated. The results are shown in Table 4.

[0137] Table 4 shows the test results of ultra-high strength steel in Example 5.

[0138]

[0139] It can be seen that both Experiments 1 and 2 in Example 5 can yield ultra-high strength steel with high tensile strength, high yield strength, good elongation, high elastic modulus, and excellent hardness, which is beneficial for the application of ultra-high strength steel. Compared with Experiment 3, Experiment 1, by controlling the tap density of the alloy powder, helps to improve the strength and hardness of the ultra-high strength steel, resulting in excellent comprehensive performance. Compared with Experiment 2, the ultra-high strength steel obtained in Experiment 1 has superior strength and can be used in applications with strict strength requirements. Compared with Experiment 1, the ultra-high strength steel obtained in Experiment 2 has better elongation performance and can be used in applications with strict elongation performance requirements. Therefore, the ultra-high strength steel provided in this application has excellent comprehensive performance and can be applied to different application scenarios. The ultra-high strength steel material obtained in Experiment 1 was subjected to anti-corrosion and blackening treatment by manganese phosphating method, and its neutral salt spray test can reach 24 hours.

[0140] Example 6

[0141] Experiment 1

[0142] Iron, nickel, cobalt, molybdenum, and vanadium sources were mixed and melted in a vacuum environment at 1650℃. The resulting alloy powder was prepared by water-air combined atomization. The alloy powder contained 17.91 wt% nickel, 9.3 wt% cobalt, 6.1 wt% molybdenum, 0.42 wt% vanadium, 0.25 wt% chromium, 0.017 wt% carbon, 0.26 wt% oxygen, 0.013 wt% sulfur, 0.06 wt% manganese, 0.22 wt% silicon, and the balance iron. The tap density of the alloy powder was 4.56 g / cm³ after sieving. 3 The particle size D10 is 3.18 μm, the particle size D50 is 7.92 μm, and the particle size D90 is 21.8 μm.

[0143] A binder was prepared by mixing 92.3 wt% polyoxymethylene, 2.6 wt% antioxidant, 3.4 wt% polyethylene, and 1 wt% vinyl acetate polymer in a kneader at 170°C for 120 min. The binder and alloy powder were mixed at a volume ratio of 45:55 and then internally mixed in a mixer to obtain a feedstock with a melt flow index of 1458 g / 10 min. The feedstock was injected into a mold at an injection temperature of 200°C, an injection pressure of 180 MPa, and a mold cavity temperature of 110°C to form a preform with a density of 5.45 g / cm³. 3 The blank was placed in nitric acid and nitrogen atmosphere and heated to 120℃ for 10 hours for degreasing treatment to remove polyoxymethylene, with a degreasing rate of 7.84%. Then, it was sintered at 1390℃ for 4 hours under an argon atmosphere to obtain the preform material. The preform material was examined using a metallographic microscope, and the results are as follows: Figure 14 As shown, the grain size of the prefabricated material is less than 250 μm, and the carbon content of the prefabricated material is 0.003 wt% and the oxygen content is 0.021 wt%.

[0144] The precast material was placed in a vacuum heat treatment furnace and solution treated at 940℃ for 60 minutes, followed by cooling. The hardness after solution treatment was 290HV-300HV. Then, it was treated in liquid nitrogen at -196℃ for 60 minutes, followed by aging treatment at 490℃ for 4 hours to obtain ultra-high strength steel. The ultra-high strength steel contained 17.91wt% nickel, 9.3wt% cobalt, 6.1wt% molybdenum, 0.42wt% vanadium, 0.25wt% chromium, less than 0.017wt% carbon, 0.0215wt%-0.25wt% oxygen, 0.013wt% sulfur, 0.06wt% manganese, 0.22wt% silicon, and the balance iron.

[0145] Experiment 2

[0146] The experiment was largely the same as Experiment 1, except that the aging conditions were 510℃ for 5 hours.

[0147] The tensile strength, yield strength, elongation, elastic modulus and hardness of the ultra-high strength steels obtained in Experiment 1 and Experiment 2 were tested. Each sample was tested in three parallel experiments and the average value was calculated. The results are shown in Table 5.

[0148] Table 5 shows the test results of ultra-high strength steel in Example 6.

[0149]

[0150] It can be seen that both Experiment 1 and Experiment 2 in Example 6 can produce ultra-high strength steel with high tensile strength, high yield strength, good elongation, high elastic modulus, and excellent hardness, which is beneficial for the use of ultra-high strength steel. Compared with Experiment 2, the ultra-high strength steel obtained by Experiment 1 has better strength and can be used in applications with strict strength requirements. Compared with Experiment 1, the ultra-high strength steel obtained by Experiment 2 has better elongation performance and can be used in applications with strict elongation performance requirements. Therefore, the ultra-high strength steel provided by this application has excellent comprehensive performance and can be applied to different application scenarios. A 1μm-3μm nickel-phosphorus alloy layer is formed on the surface of the ultra-high strength steel materials obtained by Experiment 1 and Experiment 2 by chemical plating, and coloring is performed by physical vapor deposition, with a hardness of over 800HV; then, a neutral salt spray test is performed, which can last for 24 hours.

[0151] Example 7

[0152] Experiments 1-4

[0153] Ultra-high strength steel was prepared using the preparation conditions of Experiment 1 in Example 1. The test results of the alloy powders of Experiments 1-4 in Example 7 are shown in Table 6, and the test results of the ultra-high strength steel are shown in Table 7.

[0154] Table 6 shows the test results of the alloy powder in Example 7.

[0155] Ni Co Mo V Cr C O S Mn Si Fe Experiment 1 17.42 8.5 6.21 0.55 0.21 0.014 0.19 0.003 0.08 0.31 66.513 Experiment 2 17.13 9.38 5.94 0.45 0.23 0.011 0.35 0.004 0.04 0.23 66.235 Experiment 3 17.81 9.22 6.33 0.38 0.31 0.009 0.57 0.008 0.07 0.39 64.903 Experiment 4 17.63 9.06 6.14 0.53 0.41 0.017 1.18 0.011 0.06 0.27 64.692

[0156] Table 7 shows the test results of ultra-high strength steel in Example 7.

[0157]

[0158] The contents of Ni, Co, Mo, V, and Cr in the obtained ultra-high strength steel were the same as those in the alloy powder. Tables 6 and 7 show that the oxygen content in the alloy powder of Experiment 4 was too high, resulting in an oxygen content exceeding 0.3 wt% in the ultra-high strength steel. This negatively impacted both the strength and elongation of the ultra-high strength steel. In contrast, the oxygen content in Experiments 1-3 was appropriate, ensuring decarburization while avoiding the negative effects of oxygen on the ultra-high strength steel, thus yielding ultra-high strength steel with excellent overall performance.

[0159] Example 8

[0160] Experiments 1-4

[0161] Ultra-high strength steel was prepared using the preparation conditions of Experiment 1 in Example 1. The test results of the alloy powders of Experiments 1-4 in Example 8 are shown in Table 8, and the test results of the ultra-high strength steel are shown in Table 9.

[0162] Table 8. Test results of alloy powder in Example 8

[0163] Ni Co Mo V Cr C O S Mn Si Fe Experiment 1 17.22 8.6 6.01 0.55 0.24 0.014 0.19 0.003 0.08 0.31 66.783 Experiment 2 16.93 9.18 5.74 0.45 0.26 0.045 0.33 0.004 0.04 0.23 66.791 Experiment 3 17.61 9.02 6.13 0.41 0.34 0.37 0.27 0.008 0.07 0.39 65.382 Experiment 4 17.43 8.86 5.94 0.53 0.44 0.58 0.29 0.008 0.06 0.27 65.592

[0164] Table 9 shows the test results of ultra-high strength steel in Example 8.

[0165]

[0166] The contents of Ni, Co, Mo, V, and Cr in the obtained ultra-high strength steel were the same as those in the alloy powder. Tables 8 and 9 show that the carbon content in the alloy powder of Experiments 3-4 was too high, resulting in a carbon content exceeding 0.025 wt% in the ultra-high strength steel. This negatively impacted both the strength and elongation of the ultra-high strength steel. In contrast, the carbon content in Experiments 1-2 was appropriate, ensuring both the strength and elongation of the ultra-high strength steel and improving its overall performance.

[0167] Example 9

[0168] Experiments 1-5

[0169] Ultra-high strength steel was prepared using the preparation conditions of Experiment 1 in Example 1. The test results of the alloy powders of Experiments 1-5 in Example 9 are shown in Table 10, and the test results of the ultra-high strength steel are shown in Table 11.

[0170] Table 10 shows the test results of the alloy powder in Example 9.

[0171] Ni Co Mo V Cr C O S Mn Si Fe Experiment 1 17.58 9.3 6.8 0.45 0.23 0.012 0.27 0.003 0.08 0.31 64.965 Experiment 2 17.27 8.65 6.06 0.55 0.36 0.011 0.19 0.003 0.08 0.31 66.516 Experiment 3 16.98 9.23 5.79 0.45 1.28 0.013 0.33 0.004 0.04 0.23 65.653 Experiment 4 17.66 9.07 6.18 0.41 1.81 0.017 0.27 0.008 0.07 0.39 64.115 Experiment 5 17.5 9.3 6.8 0.51 0.05 0.01 0.23 0.003 0.08 0.31 65.207

[0172] Table 11 shows the test results of ultra-high strength steel in Example 9.

[0173]

[0174]

[0175] The contents of Ni, Co, Mo, V, and Cr in the obtained ultra-high strength steel were the same as those in the alloy powder. Tables 10 and 11 show that the chromium content in the alloy powder and ultra-high strength steel of Experiment 4 was too high, affecting the strength and elongation of the ultra-high strength steel; the chromium content in the alloy powder and ultra-high strength steel of Experiment 5 was too low, affecting the elongation and reducing the plasticity of the ultra-high strength steel; while the chromium content in Experiments 1-3 was appropriate, resulting in ultra-high strength steel with high tensile strength, yield strength, and good elongation.

[0176] Example 10

[0177] Experiments 1-9

[0178] Ultra-high strength steel was prepared using the preparation conditions of Experiment 1 in Example 1. The test results of the alloy powders of Experiments 1-9 in Example 10 are shown in Table 12, and the test results of the ultra-high strength steel are shown in Table 13.

[0179] Table 12 Detection results of alloy powder in Example 10

[0180] Ni Co Mo V Cr C O S Mn Si Fe Experiment 1 15.58 9.33 5.95 0.48 0.33 0.005 0.31 0.013 0.03 0.21 67.762 Experiment 2 19.47 9.32 6.03 0.51 0.38 0.012 0.35 0.011 0.05 0.18 63.687 Experiment 3 17.54 7.33 5.8 0.49 0.35 0.011 0.38 0.008 0.07 0.22 67.801 Experiment 4 17.61 11.68 5.9 0.55 0.29 0.013 0.27 0.013 0.04 0.23 63.404 Experiment 5 17.34 9.31 4.35 0.45 0.31 0.014 0.29 0.015 0.02 0.23 67.671 Experiment 6 17.48 9.27 7.23 0.44 0.29 0.012 0.32 0.016 0.04 0.27 64.632 Experiment 7 17.59 9.19 6.17 0.15 0.41 0.013 0.28 0.018 0.05 0.23 65.899 Experiment 8 17.31 9.19 6.2 0.9 0.38 0.015 0.27 0.01 0.07 0.31 65.345 Experiment 9 17.45 9.1 6.05 0.48 0.51 0.018 0.32 0.003 0.02 0.42 65.629

[0181] Table 13 shows the test results of ultra-high strength steel in Example 10.

[0182]

[0183] The contents of Ni, Co, Mo, V, and Cr in the obtained ultra-high strength steel were the same as those in the alloy powder. Tables 12 and 13 show that the nickel content in the ultra-high strength steel obtained in Experiment 1 was too low, affecting its tensile strength and yield strength, thus reducing its strength properties. The nickel content in the ultra-high strength steel obtained in Experiment 2 was too high, affecting its elongation and reducing its plasticity. The cobalt content in the ultra-high strength steel obtained in Experiment 3 was too low, affecting its yield strength. The cobalt content in the ultra-high strength steel obtained in Experiment 4 was too high, resulting in a significant decrease in elongation and affecting its plasticity. The molybdenum content in the ultra-high strength steel obtained in Experiment 5 was too low, affecting its tensile strength and yield strength, thus reducing its overall strength. The ultra-high strength steel prepared in Experiment 6 had an excessively high molybdenum content, resulting in a significant decrease in elongation and affecting its plasticity. The ultra-high strength steel prepared in Experiment 7 had an excessively low vanadium content, leading to a decrease in tensile strength, yield strength, and elongation, thus affecting the overall performance of the ultra-high strength steel. The ultra-high strength steel prepared in Experiment 8 had an excessively high vanadium content, resulting in a decrease in elongation and affecting its plasticity. The content of each element in Experiment 9 met the requirements of this application, enabling the preparation of ultra-high strength steel with a tensile strength greater than 1900 MPa, a yield strength greater than 1800 MPa, an elongation greater than 4%, and an elastic modulus of 170 GPa to 190 GPa.

[0184] The above provides a detailed description of the embodiments provided in this application. This document elucidates and explains the principles and implementation methods of this application. The above description is only intended to help understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for preparing ultra-high strength steel, characterized in that, include: After the alloy powder is mixed with the binder, it is granulated by intensive mixing to obtain the feedstock. The tap density of the alloy powder is greater than 4.4 g / cm³. 3 ; The feedstock is injected, degreased, and sintered to obtain a preform material. The preform material has a grain size of less than or equal to 250 μm, a carbon content of less than or equal to 0.025 wt%, and an oxygen content of 0.0215 wt% to 0.3 wt%. The prefabricated material is heat-treated to obtain ultra-high strength steel. The chemical composition of the ultra-high strength steel includes 16wt% to 19wt% Ni, 7.5wt% to 11.5wt% Co, 5wt% to 7wt% Mo, 0.2wt% to 0.8wt% V, 0.1wt% to 1wt% Cr, less than or equal to 0.025wt% C, 0.0215wt% to 0.3wt% O, and the balance Fe. The hardness of the ultra-high strength steel is 520HV to 630HV.

2. The preparation method according to claim 1, characterized in that, The hardness of the prefabricated material is 250HV to 330HV; The density of the precast material is greater than 7.85 g / cm³. 3 .

3. The preparation method according to claim 1, characterized in that, The alloy powder has a particle size D10 of less than 5 μm, a particle size D50 of 7.5 μm to 9.5 μm, and a particle size D90 of 17 μm to 23 μm.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The sintering process involves treating at 1360°C to 1400°C for 3 to 6 hours.

5. The preparation method according to claim 1, characterized in that, The alloy powder contains less than or equal to 0.035 wt% carbon and 0.1 wt% to 1 wt% oxygen.

6. The preparation method according to claim 1, characterized in that, The heat treatment includes solution treatment, cryogenic treatment and aging treatment in sequence; The solution treatment includes treatment at 920°C to 1020°C for 35 min to 70 min; The cryogenic treatment includes treatment at -196°C to -160°C for 25 to 60 minutes; The aging process includes treatment at 470°C to 520°C for 3 to 6 hours.

7. An ultra-high strength steel prepared by the method according to any one of claims 1-6, characterized in that, The chemical composition of the ultra-high strength steel includes 16wt% to 19wt% Ni, 7.5wt% to 11.5wt% Co, 5wt% to 7wt% Mo, 0.2wt% to 0.8wt% V, 0.1wt% to 1wt% Cr, less than or equal to 0.025wt% C, 0.0215wt% to 0.3wt% O, and the balance Fe, with a hardness of 520HV to 630HV.

8. The ultra-high strength steel as described in claim 7, characterized in that, The Ni content in the ultra-high strength steel is 17wt% to 18wt%.

9. The ultra-high strength steel as described in claim 7, characterized in that, The content of Co in the ultra-high strength steel is 8.5 wt% to 10 wt%.

10. The ultra-high strength steel as described in claim 7, characterized in that, The content of Mo in the ultra-high strength steel is 5.5 wt% to 6.5 wt%.

11. The ultra-high strength steel as described in claim 7, characterized in that, The V content in the ultra-high strength steel is from 0.42 wt% to 0.55 wt%.

12. The ultra-high strength steel as described in claim 7, characterized in that, The ultra-high strength steel has a yield strength greater than or equal to 1800 MPa, a tensile strength greater than or equal to 1900 MPa, an elongation greater than or equal to 4%, and an elastic modulus of 170 GPa to 190 GPa.

13. A structural component for an electronic device, characterized in that, The material of the electronic device structural components includes ultra-high strength steel prepared by the preparation method according to any one of claims 1 to 6 or ultra-high strength steel according to any one of claims 7 to 12.

14. An electronic device, characterized in that, Includes the electronic device structural component as described in claim 13.

Images