Ultra-high strength steel and its preparation methods, structural components for electronic devices and electronic devices

Abstract

This application provides an ultra-high strength steel comprising 15wt%-20wt% nickel, 11wt%-12.5wt% cobalt, 4.5wt%-5.5wt% molybdenum, 0.2wt%-0.5wt% titanium, less than 0.1wt% carbon, and the balance iron. This ultra-high strength steel exhibits excellent strength and good ductility, which is beneficial for its use in electronic device structural components. This application also provides a method for preparing the ultra-high strength steel, electronic device structural components, and electronic devices.

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] With the continuous development of electronic devices, the materials used for structural components of electronic devices are becoming increasingly diverse. Steel, with its low price and reliable performance, has become one of the most widely used materials in the world, among which ultra-high strength steel is widely used due to its excellent strength. Currently, the performance of ultra-high strength steel 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 one aspect, this application provides an ultra-high strength steel comprising 15wt%-20wt% nickel, 11wt%-12.5wt% cobalt, 4.5wt%-5.5wt% molybdenum, 0.2wt%-0.5wt% titanium, less than 0.1wt% carbon, and the balance iron.

[0005] Secondly, this application provides a method for preparing ultra-high strength steel, comprising: mixing alloy powder with a binder, and then granulating the mixture to obtain a feedstock; the feedstock being injected, degreased, and sintered to obtain a preform material; the preform material being subjected to solution treatment, cryogenic treatment, and aging treatment to obtain ultra-high strength steel, wherein the ultra-high strength steel comprises 15wt%-20wt% nickel, 11wt%-12.5wt% cobalt, 4.5wt%-5.5wt% molybdenum, 0.2wt%-0.5wt% titanium, less than 0.1wt% carbon, and the balance iron.

[0006] Thirdly, this application provides an electronic device structural component, the material of which includes the ultra-high strength steel described in the first aspect.

[0007] Fourthly, this application provides an electronic device, including an electronic device structural component, wherein the material of the electronic device structural component includes the ultra-high strength steel described in the first aspect.

[0008] The ultra-high strength steel provided in this application combines high strength and high ductility, which is beneficial for improving the performance of structural components in electronic devices. Furthermore, the preparation method of this ultra-high strength steel is simple, allowing for the production of structural components of the desired shape without the need for machining. This method is convenient, convenient, and has low manufacturing costs. The resulting electronic device structural component exhibits excellent performance, which is advantageous for its use in electronic devices. Attached Figure Description

[0009] 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.

[0010] Figure 1 This is a flowchart illustrating a method for preparing ultra-high strength steel according to an embodiment of this application.

[0011] Figure 2 A flowchart illustrating a method for preparing ultra-high strength steel according to another embodiment of this application.

[0012] Figure 3 A flowchart illustrating the fabrication method of an electronic device structural component provided in one embodiment of this application.

[0013] Figure 4 This is a schematic diagram of the structure of an electronic device provided in one embodiment of this application.

[0014] Figure 5 The force-displacement curve is shown for the ultra-high strength steel obtained in Example 1.

[0015] Figure 6 The force-displacement curve is shown for the ultra-high strength steel obtained in Example 2.

[0016] Figure 7 The force-displacement curve is shown for the ultra-high strength steel obtained in Example 3.

[0017] Figure 8 The force-displacement curve is shown for the ultra-high strength steel obtained in Example 4. Detailed Implementation

[0018] The following are preferred embodiments of this application. It should be noted that, for those skilled in the art, several improvements and modifications can be made 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.

[0019] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure, specific examples of components and arrangements 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 embodiments and / or arrangements 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.

[0020] This application provides an ultra-high strength steel comprising 15wt%-20wt% nickel, 11wt%-12.5wt% cobalt, 4.5wt%-5.5wt% molybdenum, 0.2wt%-0.5wt% titanium, less than 0.1wt% carbon, and the balance iron. This ultra-high strength steel exhibits excellent strength while also possessing good ductility, thus allowing it to balance strength and ductility, which is beneficial for its use in electronic device structural components.

[0021] In this application, nickel (Ni) is an austenite-forming element, making it easier for steel to obtain single-phase austenite during heating. It also lowers the onset temperature of martensitic transformation, making it easier to obtain martensite during cooling. Furthermore, it helps increase the content of retained austenite, improving plasticity. Simultaneously, nickel can inhibit the decomposition of screw dislocations in martensitic aging steel structures, ensuring cross-slip can occur. The ability of a material to undergo cross-slip is an indicator of its plasticity and toughness, and nickel is an element contributing to plasticity and toughness in ultra-high strength steel. Nickel can also promote precipitation strengthening, increasing the strength of ultra-high strength steel. Austenite is a solid solution formed by carbon dissolved in γ-Fe, while martensite is a supersaturated solid solution of carbon in α-Fe, formed by the diffusionless transformation of austenite. In this application, the ultra-high strength steel contains 15wt%-20wt% nickel. Too low a nickel content makes it difficult to form a single austenite, reducing the content of retained austenite in the ultra-high strength steel and hindering the improvement of its ductility. Too high a nickel content hinders martensite formation, increasing the content of retained austenite and thus negatively impacting the strength. Therefore, using 15wt%-20wt% nickel ensures both increased strength and avoids reduced plasticity, resulting in ultra-high strength steel with excellent strength and plasticity. Specifically, the nickel content in the ultra-high strength steel can be, but is not limited to, 15wt%, 16wt%, 17wt%, 17.3wt%, 17.5wt%, 17.8wt%, 18wt%, 19wt%, or 20wt%. Furthermore, the nickel content in the ultra-high strength steel can be, but is not limited to, 15wt%-19.8wt%, 15.23wt%-19.76wt%, 15.1wt%-15.9wt%, 15.3wt%-16.7wt%, 15.8wt%-17.2wt%, 16.1wt%-16.9wt%, 16.2wt%-17.3wt%, 16.5wt%-19.5wt%, 16.63wt%-18.9wt%, 17wt%-18wt%, 17.3wt%-18.9wt%, 18.17wt%-19.78wt%, 18.4wt%-19.5wt%, etc. In one embodiment of this application, the ultra-high strength steel contains 16.63wt%-18.9wt% nickel, which is beneficial for further improving the strength and plasticity of the ultra-high strength steel. For example, the nickel content in ultra-high strength steel can be, but is not limited to, 16.63wt%-18.47wt%, 16.9wt%-18.5wt%, 17wt%-18wt%, 17.13wt%-17.94wt%, 17.3wt%-18.42wt%, 17.5wt%-18.5wt%, or 17.7wt%-18.6wt%.

[0022] In this application, cobalt (Co) promotes austenite formation, lowers the onset temperature of martensitic transformation, increases plasticity, and promotes precipitation hardening. Cobalt only dissolves in the martensitic matrix and does not form intermetallic compounds. It primarily influences the dislocation substructure, providing uniform nucleation sites for the precipitated phase. Cobalt reduces the solubility of molybdenum, thereby promoting the precipitation and uniform distribution of molybdenum-containing intermetallic compounds. Therefore, the combination of cobalt and molybdenum produces a strengthening effect. In this application, the ultra-high strength steel contains 11wt%-12.5wt% cobalt. Too low a cobalt content is detrimental to the precipitation of molybdenum-containing intermetallic compounds, thus hindering the improvement of the ultra-high strength steel's strength. Too high a cobalt content makes it difficult to dissolve at high temperatures, reducing the strength of the ultra-high strength steel. Therefore, using 11wt%-12.5wt% cobalt ensures both the improvement of the ultra-high strength steel's strength and the acquisition of ultra-high strength steel with excellent yield strength and tensile strength. Specifically, the cobalt content in ultra-high strength steel can be, but is not limited to, 11wt%, 11.2wt%, 11.5wt%, 11.8wt%, 12wt%, 12.3wt%, or 12.5wt%. Furthermore, the cobalt content in ultra-high strength steel can be, but is not limited to, 11wt%-12wt%, 11.1wt%-12.4wt%, 11.1wt%-11.96wt%, 11.23wt%-11.87wt%, 11.1wt%-11.47wt%, 11.3wt%-12.37wt%, 11.36wt%-12.2wt%, 11.4wt%-12.5wt%, 11.42wt%-12.35wt%, 11.52wt%-12.48wt%, 11.53wt%-11.98wt%, 11.67wt%-12.38wt%, 11.7wt%-12.2wt%, 11.8wt%-12.46wt%, etc. In one embodiment of this application, the ultra-high strength steel contains 11.4wt%-12.5wt% cobalt, which further improves the strength and plasticity of the ultra-high strength steel.

[0023] In this application, molybdenum (Mo) enhances the overall strength and toughness of ultra-high-strength steel, contributing to both its strength and toughness. Molybdenum lowers the martensitic transformation initiation temperature, promotes the precipitation of intermetallic compounds and the formation of precipitated phases, and prevents the strengthening phase from precipitating in a grid pattern along the original austenite grain boundaries, thus preventing its segregation and improving fracture toughness. In this application, the ultra-high-strength steel contains 4.5 wt%-5.5 wt% molybdenum. Too low a molybdenum content hinders the precipitation of molybdenum-containing intermetallic compounds, thus negatively impacting the strength of the ultra-high-strength steel. Too high a molybdenum content hinders the martensitic transformation and produces molybdenum-rich intermetallic compounds that are difficult to dissolve even under high-temperature solution treatment, leading to a decrease in the ductility of the ultra-high-strength steel. Therefore, using 4.5 wt%-5.5 wt% molybdenum ensures both improved strength and enhanced ductility of the ultra-high-strength steel. Specifically, the molybdenum content in ultra-high strength steel can be, but is not limited to, 4.5wt%, 4.7wt%, 4.8wt%, 5wt%, 5.2wt%, 5.3wt%, or 5.5wt%. Furthermore, the molybdenum content in ultra-high strength steel can be, but is not limited to, 4.6wt%-5.4wt%, 4.62wt%-5.37wt%, 4.62wt%-4.98wt%, 4.67wt%-4.94wt%, 4.72wt%-5.41wt%, 4.75wt%-5.15wt%, 4.78wt%-4.96wt%, 4.8wt%-5.3wt%, 4.83wt%-5.42wt%, 4.83wt%-5.3wt%, 4.9wt%-5.45wt%, 5wt%-5.5wt%, 5.07wt%-5.5wt%, 5.1wt%-5.48wt%, 5.23wt%-5.49wt%, etc. In one embodiment of this application, the ultra-high strength steel contains 4.8wt%-5.3wt% molybdenum, which gives the ultra-high strength steel better strength and plasticity.

[0024] In this application, titanium (Ti) is used as a supplementary hardener, which can lower the onset temperature of martensitic transformation, promote the precipitation of intermetallic compounds and the formation of martensite, and also refine the grains, further improving plasticity. In this application, the ultra-high strength steel contains 0.2wt%-0.5wt% titanium. If the titanium content is too low, fewer intermetallic compounds will precipitate, limiting the improvement in the strength of the ultra-high strength steel; however, titanium has good reactivity, and if the titanium content is too high, it can easily form harmful impurities, which is detrimental to the improvement of the ultra-high strength steel's performance. Therefore, using 0.2wt%-0.5wt% titanium ensures the improvement of both the strength and plasticity of the ultra-high strength steel. Specifically, the titanium content in the ultra-high strength steel can be, but is not limited to, 0.2wt%, 0.25wt%, 0.3wt%, 0.35wt%, 0.4wt%, 0.45wt%, or 0.5wt%. Furthermore, the titanium content in the ultra-high strength steel can be, but is not limited to, 0.22wt%-0.49wt%, 0.24wt%-0.37wt%, 0.26wt%-0.34wt%, 0.21wt%-0.29wt%, 0.32wt%-0.48wt%, 0.32wt%-0.5wt%, 0.35wt%-0.45wt%, 0.31wt%-0.39wt%, 0.37wt%-0.42wt%, 0.41wt%-0.5wt%, 0.41wt%-0.47wt%, 0.46wt%-0.49wt%, etc. In one embodiment of this application, the ultra-high strength steel contains 0.32wt%-0.5wt% titanium, which gives the ultra-high strength steel better strength and plasticity.

[0025] 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 ultra-high strength steel may be, but is not limited to, greater than 60 wt%, greater than 61 wt%, greater than 64 wt%, greater than 65 wt%, greater than 67 wt%, greater than 68 wt%, etc.

[0026] In this application, the carbon (C) content in the ultra-high strength steel is less than or equal to 0.1 wt%, meaning that the ultra-high strength steel provided in this application is a low-carbon steel. By controlling the carbon content, the plasticity and toughness of the ultra-high strength steel are avoided from being affected. In one embodiment of this application, the carbon content in the ultra-high strength steel is less than or equal to 0.03 wt%. That is, the ultra-high strength steel provided in this application is a low-carbon steel, which is beneficial for significantly improving the plasticity of the ultra-high strength steel. For example, the carbon content in the ultra-high strength steel may be, but is not limited to, less than or equal to 0.028 wt%, less than or equal to 0.024 wt%, less than or equal to 0.021 wt%, less than or equal to 0.019 wt%, less than or equal to 0.017 wt%, less than or equal to 0.014 wt%, less than or equal to 0.011 wt%, less than or equal to 0.007 wt%, less than or equal to 0.003 wt%, etc. Furthermore, the carbon content in ultra-high strength steel is less than or equal to 0.02 wt%, which is beneficial to further improving the plasticity of ultra-high strength steel.

[0027] In this application, ultra-high strength steel inevitably contains impurity elements. By controlling the content of these impurity elements, their impact on the performance of the ultra-high strength steel is avoided. In the embodiments of this application, the content of impurity elements in the ultra-high strength steel is less than or equal to 0.4 wt%, thus minimizing their influence on the strength and plasticity of the ultra-high strength steel. In one embodiment of this application, the impurity elements include at least one of sulfur (S), silicon (Si), and manganese (Mn). In one embodiment, the content of sulfur in the ultra-high strength steel is less than or equal to 0.025 wt%. Sulfur can segregate at grain boundaries, thereby weakening the grain boundaries and affecting the thermoplasticity, fatigue strength, and toughness of the ultra-high strength steel. By controlling the content of sulfur, the thermoplasticity, fatigue strength, and toughness of the ultra-high strength steel are ensured. Specifically, the sulfur content in ultra-high strength steel can be, but is not limited to, 0, 0.002 wt%, 0.005 wt%, 0.007 wt%, 0.01 wt%, 0.013 wt%, 0.015 wt%, 0.018 wt%, 0.002 wt%, 0.0022 wt%, etc. In one embodiment, the silicon content in ultra-high strength steel is less than or equal to 0.2 wt%, thereby avoiding the influence on the solubility of elements such as molybdenum. Specifically, the silicon content in ultra-high strength steel can be, but is not limited to, 0, 0.01 wt%, 0.026 wt%, 0.047 wt%, 0.05 wt%, 0.063 wt%, 0.089 wt%, 0.1 wt%, 0.128 wt%, 0.15 wt%, 0.175 wt%, 0.2 wt%, etc. In one embodiment, the manganese content in the ultra-high strength steel is less than or equal to 0.1 wt%, thereby ensuring the plasticity and strength of the ultra-high strength steel. Specifically, the manganese content in the ultra-high strength steel can be, but is not limited to, 0, less than 0.01 wt%, less than 0.018 wt%, less than 0.02 wt%, less than 0.037 wt%, less than 0.044 wt%, less than 0.05 wt%, less than 0.069 wt%, less than 0.08 wt%, less than 0.092 wt%, less than 0.1 wt%, etc. In one embodiment, the aluminum content in the ultra-high strength steel is less than or equal to 0.01 wt%. Further, the aluminum content in the ultra-high strength steel is less than or equal to 0.002 wt%. Even further, the ultra-high strength steel does not contain aluminum. Aluminum easily forms brittle inclusions in steel, affecting toughness; controlling the aluminum content helps ensure the toughness of the ultra-high strength steel.

[0028] In one embodiment of this application, the ultra-high strength steel includes iron, nickel, cobalt, molybdenum, titanium, and impurity elements. Further, the ultra-high strength steel is composed of iron, nickel, cobalt, molybdenum, titanium, and impurity elements. Further, the ultra-high strength steel is composed of iron, nickel, cobalt, molybdenum, titanium, carbon, and impurity elements.

[0029] In this application, the ultra-high strength steel is a martensitic aging steel. Martensitic aging steel uses carbon-free or low-carbon martensite as a matrix and undergoes precipitation hardening of intermetallic compounds during aging, thus strengthening the steel through the dispersed precipitation of these compounds. In the embodiments of this application, the mass content of martensite in the ultra-high strength steel is greater than or equal to 82%. That is, during the production process of ultra-high strength steel, carbon dissolves in γ-Fe to form austenite. After reaching the martensitic transformation temperature (Ms), the γ-Fe lattice in the austenite instantly reorganizes into an α-Fe lattice. The carbon atoms dissolved in the austenite do not have time to diffuse out of the γ-Fe lattice and directly enter the α-Fe lattice. This lattice has a very low carbon solubility, forming a supersaturated interstitial solid solution, thereby causing a diffusionless phase transformation into martensite. This results in a large amount of austenite transforming into martensite, thus achieving a strengthening effect and increasing the strength of the ultra-high strength steel. Specifically, the martensite content in ultra-high strength steel can be, but is not limited to, 82% or more, 82.5% or more, 83% or more, 84% or more, 85% or more, 85.7% or more, 86% or more, or 87% or more. Furthermore, the mass content of lath martensite in the martensite is above 99%. Lath martensite ensures that ultra-high strength steel possesses both high strength and excellent plasticity. Moreover, during the preparation of ultra-high strength steel, the high-density dislocations contained in lath martensite provide numerous nucleation sites for the precipitation of intermetallic compounds, which is beneficial for further strengthening of the ultra-high strength steel. In the embodiments of this application, the ultra-high strength steel also contains retained austenite, which plays a certain role in improving plasticity. Furthermore, the mass content of retained austenite in the ultra-high strength steel is less than or equal to 14%. Thus, the plasticity of the ultra-high strength steel can be improved without affecting its strength. Specifically, the mass content of retained austenite in ultra-high strength steel can be, but is not limited to, below 8%, 9%, 10%, 11%, 12%, or 13%. In this embodiment, the ultra-high strength steel also contains a dispersed phase. This dispersed phase is an intermetallic compound, which precipitates and is uniformly distributed within the ultra-high strength steel, achieving dispersion strengthening. Specifically, the dispersed phase can be, but is not limited to, intermetallic compounds of molybdenum, titanium, and nickel; the dispersed phase can be, but is not limited to, nanoscale, for example, the diameter of the dispersed phase can be, but is not limited to, 2nm-10nm. Further, the mass content of the dispersed phase in the ultra-high strength steel is 2%-4% (e.g., 2.1%, 2.45%, 2.67%, 3%, 3.49%, 3.6%, 3.83%, or 4%). This improves the strength of the ultra-high strength steel without significantly affecting its plasticity.

[0030] Yield strength is the yield limit of ultra-high strength steel when it yields, that is, the stress resisting a small amount of plastic deformation; tensile strength is the critical value at which ultra-high strength steel transitions from uniform plastic deformation to localized concentrated plastic deformation, and it is also the maximum load-bearing capacity of ultra-high strength steel under static tensile conditions; elongation is an indicator describing the plastic properties of ultra-high strength steel. Specifically, the yield strength, tensile strength, and elongation of ultra-high strength steel can be tested according to GB / T 228.1-2010. In the embodiments of this application, the yield strength of ultra-high strength steel is greater than 1800 MPa, the tensile strength is greater than 1900 MPa, and the elongation is greater than 4%. The ultra-high strength steel provided in this application has high yield strength, tensile strength, and elongation, ensuring excellent strength and plasticity; ultra-high strength steel with the above-mentioned yield strength, tensile strength, and elongation can buffer external forces and improve the ability of ultra-high strength steel to resist drops, impacts, etc. Specifically, the yield strength of ultra-high strength steel can be, but is not limited to, above 1820 MPa, 1850 MPa, 1870 MPa, 1890 MPa, 1900 MPa, 1910 MPa, 1920 MPa, 1930 MPa, or 1950 MPa; the tensile strength can be, but is not limited to, above 1920 MPa, 1950 MPa, 1980 MPa, 1990 MPa, 2000 MPa, 2020 MPa, 2040 MPa, 2050 MPa, 2060 MPa, or 2070 MPa; and the elongation can be, but is not limited to, above 4.1%, 4.2%, 4.25%, or 4.3%. In one embodiment, the yield strength of the ultra-high strength steel is above 1850 MPa, the tensile strength is above 1950 MPa, and the elongation is greater than 4%. In another embodiment, the ultra-high strength steel has a yield strength of 1850 MPa or higher, a tensile strength of 1950 MPa or higher, and an elongation of 4.1% or higher. In yet another embodiment, the ultra-high strength steel has a yield strength of 1900 MPa or higher, a tensile strength of 2000 MPa or higher, and an elongation of 4.1% or higher. In yet another embodiment, the ultra-high strength steel has a yield strength of 1900 MPa or higher, a tensile strength of 2050 MPa or higher, and an elongation of 4.1% or higher. In yet another embodiment, the ultra-high strength steel has a yield strength of 1900 MPa or higher, a tensile strength of 2050 MPa or higher, and an elongation of 4.2% or higher.

[0031] In one embodiment of this application, the ultra-high strength steel comprises 15wt%-20wt% nickel, 11wt%-12.5wt% cobalt, 4.5wt%-5.5wt% molybdenum, 0.2wt%-0.5wt% titanium, less than 0.1wt% carbon, and the balance iron; the ultra-high strength steel has a yield strength greater than 1800 MPa, a tensile strength greater than 1900 MPa, and an elongation greater than 4%. In another embodiment of this application, the ultra-high strength steel comprises 15wt%-20wt% nickel, 11wt%-12.5wt% cobalt, 4.5wt%-5.5wt% molybdenum, 0.2wt%-0.5wt% titanium, less than 0.03wt% carbon, and the balance iron; the ultra-high strength steel has a yield strength greater than 1800 MPa, a tensile strength greater than 1900 MPa, and an elongation greater than 4.1%. In another embodiment of this application, the ultra-high strength steel comprises 16.63wt%-18.9wt% nickel, 11wt%-12.5wt% cobalt, 4.5wt%-5.5wt% molybdenum, 0.2wt%-0.5wt% titanium, less than 0.1wt% carbon, and the balance iron. The ultra-high strength steel has a yield strength of 1850 MPa or higher, a tensile strength of 1950 MPa or higher, and an elongation greater than 4%. Further, when the carbon content is less than or equal to 0.03wt%, the ultra-high strength steel has a yield strength of 1850 MPa or higher, a tensile strength of 1950 MPa or higher, and an elongation of 4.1% or higher.

[0032] The ultra-high strength steel provided in this application has excellent strength and plasticity, and can be used as a material for electronic device structural components. This is beneficial for obtaining high-performance electronic device structures and helps to improve the performance and service life of electronic device structural components.

[0033] This application also provides a method for preparing ultra-high strength steel, which can produce the ultra-high strength steel in any of the above embodiments. Please refer to... Figure 1 The flowchart below shows a method for preparing ultra-high strength steel according to an embodiment of this application, including:

[0034] S101: The alloy powder and binder are mixed and then granulated by kneading to obtain the feed.

[0035] S102: The precast material is obtained after the feed is injected, degreased and sintered.

[0036] S103: The precast material is subjected to solution treatment, cryogenic treatment and aging treatment to obtain ultra-high strength steel. The ultra-high strength steel includes 15wt%-20wt% nickel, 11wt%-12.5wt% cobalt, 4.5wt%-5.5wt% molybdenum, 0.2wt%-0.5wt% titanium, less than 0.1wt% carbon and the balance iron.

[0037] In related technologies, the preparation of ultra-high strength steel requires smelting through electric arc furnaces and electroslag remelting. For high purity requirements, vacuum induction furnaces or vacuum consumable arc furnaces are also necessary, resulting in high equipment requirements. Furthermore, the ultra-high strength structural steel material obtained has high hardness, requiring a long processing time during structural component production, leading to high manufacturing costs and limitations on component shape design. In this application, a pre-formed material is obtained through alloy powder injection molding, followed by heat treatment to produce ultra-high strength steel. This preparation method is simple and convenient to operate. In practical applications, by controlling the shape of the mold during injection, structural components for electronic devices can be obtained simultaneously with the ultra-high strength steel, eliminating the need for further processing of the ultra-high strength steel material, saving on process steps and manufacturing costs. Moreover, structural components of the desired shape can be obtained simply by designing the mold, making it more convenient. The resulting ultra-high strength steel exhibits excellent strength and plasticity, which is beneficial for improving the reliability and service life of structural components.

[0038] In step S101, the alloy powder is mixed with a binder, kneaded, and granulated to obtain a feedstock for injection molding. In this embodiment, the binder comprises 3 wt%-5 wt% (e.g., 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, or 5 wt%) of polyethylene, 2 wt%-6 wt% (e.g., 2 wt%, 3 wt%, 4 wt%, 5 wt%, or 6 wt%) of vinyl acetate polymer, and the balance being polyoxymethylene (POM). POM can decompose into water and gas under the action of nitric acid, exhibiting excellent removal efficiency. The POM content in the binder is adjusted by adding polyethylene. The vinyl acetate polymer acts as a binder, and both polyethylene and vinyl acetate polymer can be removed during sintering, avoiding carbon residue. Specifically, the content of polyethylene in the adhesive can be, but is not limited to, 3wt%-4.8wt%, 3.3wt%-4.5wt%, 3.8wt%-4wt%, 4wt%-5wt%, 4.1wt%-4.9wt%, etc., and the content of vinyl acetate polymer can be, but is not limited to, 2wt%-5.7wt%, 2.1wt%-4.4wt%, 2.2wt%-3.8wt%, 3wt%-5wt%, 4wt%-5.5wt%, etc. Furthermore, the adhesive also includes 1wt%-3wt% (e.g., 1wt%, 1.5wt%, 2wt%, 2.5wt%, or 3wt%) of antioxidant to avoid the influence of oxygen during the preparation process. In one embodiment, the adhesive is obtained by mixing polyoxymethylene, polyethylene, and vinyl acetate polymers at 150°C-170°C (e.g., 150°C, 155°C, 160°C, 165°C, or 170°C) for 60 min-120 min (e.g., 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, or 120 min). In a specific embodiment, the components of the above adhesive can be mixed in a kneader according to the specified proportions.

[0039] In this embodiment, the volume ratio of alloy powder to binder during mixing is (29-31):(19-21). This ensures both the availability of injection feed and the density after sintering, which is beneficial for obtaining high-strength materials. Specifically, the volume ratio of alloy powder to binder during mixing can be, but is not limited to, 29:21, 29.5:21.5, 30:20, 30.5:20.5, 31:19, etc. In one embodiment, the volume percentage of alloy powder in the mixture formed by alloy powder and binder is 58%-62% (e.g., 58%, 59%, 60%, 61%, or 62%), and the volume percentage of binder is 38%-42% (e.g., 38%, 39%, 40%, 41%, or 42%). Specifically, in the mixture formed by the alloy powder and the binder, the volume percentage of the alloy powder may be, but is not limited to, 58%-61.8%, 58.2%-59.8%, 58.5%-61.3%, 59%-59.9%, 60.1%-61.5%, 60.8%-61.9%, etc., and the volume percentage of the binder may be, but is not limited to, 38.1%-39.2%, 38.5%-39.9%, 40.1%-41%, 38.7%-41.5%, 40.2%-41.8%, 38.2%-42%, etc.

[0040] In this application, internal mixing and granulation can be carried out, but is not limited to, in an internal mixer. In the embodiments of this application, internal mixing and granulation includes processing at 150℃-160℃ for 90min-120min. Specifically, the temperature of internal mixing and granulation can be, but is not limited to, 150℃, 152℃, 155℃, 156℃, 158℃, or 160℃, etc., and the processing time can be, but is not limited to, 90min, 95min, 100min, 110min, 115min, or 120min, etc.

[0041] In S102, the feedstock can be injection molded into the desired shape of the structural component, thereby obtaining the desired structural component while producing ultra-high strength steel. In the embodiments of this application, the injection temperature is 150℃-250℃ (e.g., 150℃, 160℃, 180℃, 200℃, 220℃, or 250℃, etc.), the injection pressure is 80MPa-150MPa (e.g., 80MPa, 100MPa, 120MPa, 130MPa, or 150MPa, etc.), and the mold cavity temperature is 100℃-140℃ (e.g., 100℃, 110℃, 120℃, 130℃, or 140℃, etc.). It is understood that during the injection process, by controlling the injection temperature, the feedstock becomes fluid, and under the action of injection pressure, the feedstock flows into the mold. By controlling the temperature of the mold cavity, the feedstock entering the mold cools and solidifies, forming a fixed shape; wherein, by controlling the morphology and structure of the mold cavity, the desired structural component is obtained. Specifically, the injection temperature can be, but is not limited to, 150℃-240℃, 155℃-245℃, 160℃-205℃, 180℃-235℃, or 200℃-250℃, etc.; the injection pressure can be, but is not limited to, 80MPa-140MPa, 90MPa-145MPa, 100MPa-135MPa, 105MPa-140MPa, or 110MPa-130MPa, etc.; and the mold cavity temperature can be, but is not limited to, 105℃-140℃, 108℃-145℃, 110℃-135℃, 115℃-143℃, or 125℃-140℃, etc.

[0042] In this application, polyoxymethylene (POM) is removed by degreasing. In the embodiments of this application, degreasing includes heating to 110°C-125°C in nitric acid and an inert gas atmosphere and holding at that temperature for 4-6 hours. 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. Specifically, the degreasing temperature can be, but is not limited to, 110°C, 112°C, 115°C, 119°C, 120°C, 124°C, or 125°C, and the holding time can be, but is not limited to, 4 hours, 5 hours, or 6 hours.

[0043] In this application, decarburization is achieved through sintering to obtain a high-density preform, which generates austenite and transforms it into martensite. During the martensitic phase transformation, the large number of high-density dislocations that accumulate increase the difficulty of dislocation movement, thus playing a strengthening role. In the embodiments of this application, sintering includes a first stage and a second stage. The first stage includes holding at 570℃-630℃ for 150min-200min, and the second stage includes holding at 1300℃-1340℃ for 100min-150min, followed by cooling at a rate of 35℃ / min-45℃ / min. The first stage involves decarburization. The holding temperature and time in this first stage are conducive to the complete removal of residual binder, avoiding its impact on material properties. The second stage, during holding, increases density, which is beneficial for strength enhancement, and simultaneously generates austenite, facilitating the subsequent formation of martensite. Finally, during cooling, austenite transforms into martensite. The holding temperature and time in the second stage are conducive to increased density and austenite formation, while the cooling rate promotes the transformation of more austenite into martensite, thus improving the material's strength and plasticity. In this application, after the above sintering process, the martensite mass content is above 99%. Specifically, the holding temperature in the first stage can be, but is not limited to, 570℃, 580℃, 590℃, 600℃, 625℃, or 630℃, and the holding time can be, but is not limited to, 150min, 165min, 170min, 175min, 180min, 185min, 190min, or 200min; the holding temperature in the second stage can be, but is not limited to, 1300℃, 1310℃, 1320℃, 1330℃, or 1340℃, and the holding time can be, but is not limited to, 100min, 110min, 120min, 130min, 140min, or 150min, and the cooling rate can be, but is not limited to, 35℃ / min, 36℃ / min, 38℃ / min, 40℃ / min, 42℃ / min, 43℃ / min, or 45℃ / min. In one embodiment, the density of the alloy powder is greater than 7.79 g / cm³. 3 The density of the precast material is greater than 7.7 g / cm³. 3 In other words, debinding and sintering can remove the binder from the material and increase its density, thereby improving the performance of ultra-high strength steel. In one embodiment, the volume shrinkage rate before and after sintering is less than 3% to ensure the performance of the precast material. Further, the volume shrinkage rate before and after sintering is less than 1.5%.

[0044] In one embodiment of this application, the first stage includes heating at a rate of 8°C / min-12°C / min (e.g., 8°C / min, 9°C / min, 10°C / min, 11°C / min, or 12°C / min). This facilitates a slow temperature increase during the first stage, which is more conducive to the outward overflow of the binder inside the material, thereby achieving decarburization. Specifically, the temperature can be raised to 570°C-630°C within 55-65 minutes. Further, the first stage can be heated to 570°C-630°C at a rate of 8°C / min-12°C / min and held for 175-185 minutes. In one embodiment of this application, the pressure in the first stage is less than 5 kPa. That is, the sintering in the first stage is carried out under negative pressure conditions, which is more conducive to decarburization. In one embodiment of this application, the first stage is carried out under an inert atmosphere, such as nitrogen, which avoids the influence of oxygen on the material.

[0045] In one embodiment of this application, the heating rate in the first stage is greater than that in the second stage. The second stage temperature is higher than that in the first stage, and the slower heating helps to avoid the formation of closed pores. In one embodiment, the second stage includes heating from the first stage to 1300℃-1340℃ at a rate of 1℃ / min-5℃ / min (e.g., 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, or 5℃ / min). This effectively avoids the effect of closing pores inside the material caused by excessively rapid heating, thereby improving density and contributing to the improvement of the performance of ultra-high strength steel. In one embodiment of this application, the second stage adopts segmented heating, which can effectively avoid the closure of pores, thereby improving the performance of ultra-high strength steel. Furthermore, the second stage includes raising the temperature from the first stage to 870℃-930℃ (e.g., 870℃-900℃, 880℃-920℃, 900℃-925℃, or 910℃-930℃, etc.) and holding it for 90min-150min (e.g., 90min-110min, 100min-140min, 115min-125min, or 120min-150min, etc.), then raising the temperature to 1050℃-1110℃ (e.g., 1050℃-1090℃, 1050℃-1100℃, 1060℃-1100℃, or 1080℃-1110℃, etc.) and holding it for 20min-50min (e.g., 20min-40min, 25min-45min, 25min-35min, or 30min-50min, etc.), and then raising the temperature to... Set the temperature to 1170℃-1230℃ (e.g., 1170℃-1200℃, 1180℃-1220℃, 1200℃-1230℃, or 1185℃-1225℃, etc.) and hold for 20min-50min (e.g., 20min-40min, 25min-45min, 25min-35min, or 30min-50min, etc.). Then raise the temperature to 1300℃-1340℃ (e.g., 1300℃-1320℃, 1310℃-1330℃, or 1325℃-1340℃, etc.) and hold for 100min-150min (e.g., 100min-125min, 115min-145min, 115min-125min, or 130min-150min, etc.) and then cool down at a rate of 35℃ / min-45℃ / min. By heating in stages, the temperature can be increased slowly in the second stage, which is beneficial for increasing density and forming austenite. The second stage can be heated at a rate of 1℃ / min to 5℃ / min.Furthermore, the second stage includes heating from the first stage to 870℃-930℃ under a pressure less than 5 kPa and holding for 90-150 min, then heating to 1050℃-1110℃ under a pressure less than 5 kPa and holding for 20-50 min, then heating to 1170℃-1230℃ under a pressure less than 15 kPa and holding for 20-50 min, and finally heating to 1300℃-1340℃ under a pressure less than 15 kPa and holding for 100-150 min, followed by cooling in a nitrogen atmosphere at a rate of 35℃ / min-45℃ / min. The second stage can be heated at a rate of 1℃ / min-5℃ / min. Specifically, the second stage heating can be carried out in an argon atmosphere, thus avoiding the influence of oxygen on the material properties and ensuring the smooth progress of the second stage heating without affecting the heat generation intensity of the metal. In one specific embodiment, the temperature can be raised to 870℃-930℃ within 55min-65min and held for 115min-125min, then raised to 1050℃-1110℃ within 45min-55min and held for 25min-35min, then raised to 1170℃-1230℃ within 55min-65min and held for 25min-35min, then raised to 1300℃-1340℃ within 55min-65min and held for 115min-125min, and then cooled at a rate of 35℃ / min-45℃ / min.

[0046] In this application, solution treatment allows alloying elements to dissolve in the matrix phase to form a solid solution, which strengthens the material. Cryogenic treatment minimizes the content of retained austenite and increases the strength of the material. Aging treatment causes a large number of dispersed intermetallic compounds to precipitate in the supersaturated solid solution. These intermetallic compounds hinder the movement of dislocations and strengthen the material, significantly increasing the strength while minimizing the loss of toughness and plasticity.

[0047] In this embodiment, the solution treatment includes treatment at 800℃-900℃ for 60-120 minutes. This solution treatment can refine the grains and further enhance the strengthening effect. Specifically, the solution temperature can be, but is not limited to, 800℃-890℃, 820℃-880℃, 840℃-860℃, or 845℃-869℃, and the treatment time can be, but is not limited to, 60 minutes, 75 minutes, 90 minutes, 105 minutes, or 120 minutes. In this application, after the above solution treatment, the martensite mass content is above 99.9%. In one embodiment of this application, the solution treatment adopts a segmented heating method, which makes the solution treatment more stable, the solution effect better, and more conducive to the precipitation of dispersed phases during subsequent aging processes. In one embodiment, the solution treatment includes heating at a rate of 5°C / min-10°C / min (e.g., 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, or 10°C / min) to 150°C-250°C (e.g., 150°C-195°C, 160°C-220°C, 175°C-230°C, or 205°C-240°C, etc.) and holding at that temperature for 20 min-60 min (e.g., 20 min-50 min, 25 min-45 min, 30 min-55 min, or 35 min-50 min, etc.), and then heating at a rate of 10°C / min-15°C / min (e.g., 11°C / min, 12°C / min, 13°C / min, 14°C / min, or 15°C / min, etc.) to 550°C-650°C (e.g., 550°C-595°C, 5... Heat at 60℃-640℃, 580℃-630℃, or 610℃-640℃, etc. and hold for 15min-40min (e.g., 15min-30min, 20min-35min, 25min-50min, or 30min-40min, etc.), at a rate of 5℃ / min-10℃ / min (e.g., 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, or 10℃ / min, etc.) to 800℃-900℃ (e.g., 800℃-880℃, 815℃-890℃, 820℃-870℃, or 850℃-895℃, etc.) and hold for 60min-120min (e.g., 60min-90min, 70min-100min, 75min-100min, or 105min-120min, etc.). This facilitates the solid solution treatment of alloying elements, contributing to the improvement of the performance of ultra-high strength steel. In one embodiment of this application, the solution treatment is performed in a vacuum environment, thus avoiding the influence of oxygen on the material. The vacuum level can be, but is not limited to, 5 Pa. Specifically, the solution treatment can be, but is not limited to, performed in a vacuum heat treatment furnace, and the cooling process can be carried out in an inert atmosphere, such as nitrogen.

[0048] In this embodiment, cryogenic treatment includes treatment at -211℃ to -191℃ for 50-70 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, -211℃, -210℃, -205℃, -200℃, -199℃, -196℃, or -193℃, and the treatment time can be, but is not limited to, 50 minutes, 55 minutes, 60 minutes, 65 minutes, or 70 minutes. In one embodiment, the cryogenic treatment is performed in liquid nitrogen.

[0049] In this embodiment, the aging treatment includes treatment at 450℃-560℃ for 3-7 hours. This aging treatment helps the precipitation and uniform distribution of the dispersed phase, further enhancing the strengthening effect, while also generating a small amount of reverse-transformed austenite, improving plasticity. Specifically, the aging temperature can be, but is not limited to, 450℃, 460℃, 470℃, 485℃, 500℃, 520℃, 535℃, or 550℃, and the treatment time can be, but is not limited to, 3 hours, 4 hours, 5 hours, 6 hours, or 7 hours. In one embodiment of this application, the aging treatment uses segmented heating, which makes the aging treatment more stable, the aging effect better, and more conducive to the precipitation of the dispersed phase. In one embodiment, the aging treatment includes heating at a rate of 5°C / min-10°C / min (e.g., 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, or 10°C / min) to 150°C-250°C (e.g., 150°C-195°C, 160°C-220°C, 175°C-230°C, or 205°C-240°C) and holding at that temperature for 20 min-60 min (e.g., 20 min-50 min, 25 min-45 min, 3 min). The aging process can be carried out at a rate of 5℃ / min-10℃ / min (e.g., 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, or 10℃ / min) to 450℃-560℃ (e.g., 450℃-495℃, 460℃-525℃, 540℃-560℃, or 460℃-550℃) and held for 3h-7h (e.g., 3h-5h, 4h-7h, or 5h-7h). This process first forms a large number of finely dispersed nucleation particles, then the dispersed phase precipitates, refining the size of the dispersed phase, reducing the solid solution content of alloying elements in the matrix phase, and improving the performance of ultra-high strength steel. Specifically, the aging cooling process can be carried out in an inert atmosphere, such as nitrogen.

[0050] The preparation method provided in this application can produce ultra-high strength structural steel that combines high strength and high plasticity, which is more conducive to its application.

[0051] Please see Figure 2The flowchart of a method for preparing ultra-high strength steel according to another embodiment of this application includes:

[0052] S201: Iron source, nickel source, cobalt source, molybdenum source and titanium source are mixed and melted, and then atomized to obtain alloy powder.

[0053] S202: The alloy powder is mixed with the binder and then granulated by kneading to obtain the feed.

[0054] S203: The precast material is obtained after the feed is injected, degreased and sintered.

[0055] S204: The precast material is subjected to solution treatment, cryogenic treatment and aging treatment to obtain ultra-high strength steel. The ultra-high strength steel includes 15wt%-20wt% nickel, 11wt%-12.5wt% cobalt, 4.5wt%-5.5wt% molybdenum, 0.2wt%-0.5wt% titanium, less than 0.1wt% carbon and the balance iron.

[0056] S202, S203 and S204 are described in S101, S102 and S103 above, and will not be repeated here.

[0057] In step S201, iron, nickel, cobalt, molybdenum, and titanium sources are mixed and melted according to the content of each element in the ultra-high strength steel. A carbon source may or may not be added during the mixing process, as long as the carbon content in the ultra-high strength steel is below 0.1 wt%. In one embodiment, after mixing the iron, nickel, cobalt, molybdenum, and titanium sources, the impurity elements need to be tested to ensure that the impurity element content in the ultra-high strength steel is within the required range. By mixing and melting the iron, nickel, cobalt, molybdenum, and titanium sources, the elements can be uniformly distributed in the alloy powder, ensuring the performance of the ultra-high strength steel. In one embodiment, the iron, nickel, cobalt, molybdenum, and titanium sources can be, but are not limited to, elemental iron, elemental nickel, elemental cobalt, and elemental molybdenum. Furthermore, the purity of the elemental metal is greater than 99.7%, greater than 99.8%, greater than 99.85%, greater than 99.9%, or greater than 99.99%, etc. In this application, atomization is performed under an inert atmosphere to prevent oxidation of the alloy by oxygen. Specifically, the alloy powder can be obtained through integrated water-air atomization. In one embodiment, the particle size D50 of the alloy powder is 7μm-10μm. Specifically, the particle size D50 of the alloy powder can be, but is not limited to, 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 9.5μm, or 10μm. This facilitates the preparation of the feedstock and effectively prevents excessive volume shrinkage before and after debinding and sintering from affecting the properties of the final ultra-high strength steel. Further, the particle size D50 of the alloy powder is 8μm-9μm. In one embodiment, the melt flow index of the alloy powder is 300g / 10min-1700g / 10min. Specifically, the melt flow index of the alloy powder is 300 g / 10 min, 400 g / 10 min, 500 g / 10 min, 800 g / 10 min, 1000 g / 10 min, 1300 g / 10 min, 1500 g / 10 min, or 1700 g / 10 min, etc. This ensures the flowability of the feed during injection.

[0058] This application also provides an electronic device structural component made of the aforementioned ultra-high strength steel. The electronic device structural component made of this ultra-high strength steel exhibits good strength and excellent ductility, which is beneficial for its application in electronic devices.

[0059] This application also provides a method for manufacturing a structural component for an electronic device. Please refer to [link / reference]. Figure 3 The flowchart illustrates a method for fabricating an electronic device structural component according to an embodiment of this application, including:

[0060] S301: The alloy powder and binder are mixed and then granulated by kneading to obtain the feed.

[0061] S302: The preform is obtained after the feed is injected, degreased and sintered.

[0062] S303: Prefabricated parts are solution treated, cryogenically treated and aged to obtain electronic equipment structural parts. The materials of electronic equipment structural parts include ultra-high strength steel, which includes 15wt%-20wt% nickel, 11wt%-12.5wt% cobalt, 4.5wt%-5.5wt% molybdenum, 0.2wt%-0.5wt% titanium, less than 0.1wt% carbon, and the balance iron.

[0063] The preparation method of electronic device structural components can be referred to the description of the preparation method of ultra-high strength steel mentioned above, and will not be repeated here.

[0064] The method for fabricating electronic device structural components provided in this application is simple and easy to operate. It allows for direct molding of structural components of the desired shape without additional machining. The structural components exhibit strong shape variability and excellent strength and plasticity, which is beneficial for their application in electronic devices. Specifically, but not limited to, miniaturized electronic device structural components can be fabricated, helping to reduce weight while maintaining excellent performance, long service life, and low manufacturing cost.

[0065] In this application embodiment, the surface of the electronic device structural components can also be treated. In one embodiment, a coating can be applied to the surface of the electronic device structural components to improve their corrosion resistance and alter their appearance. Specifically, the coating can be performed, but is not limited to, by physical vapor deposition. In another embodiment, the surface of the electronic device structural components can be passivated to prevent oxidation by oxygen. Specifically, but not limited to, the surface of the electronic device structural components can be treated with a citrate passivation solution at 60°C-70°C for 120-200 seconds to form a passivation film.

[0066] This application also provides an electronic device, including the aforementioned electronic device structural components, which can improve the performance of the electronic device. It is understood that the electronic device may be, but is not limited to, a mobile phone, tablet computer, laptop computer, watch, MP3 player, MP4 player, GPS navigator, digital camera, etc., and the electronic device structural components may be, but are not limited to, the electronic device's frame, buttons, dial, hinge, etc. Please refer to [link to relevant documentation]. Figure 4 This is a schematic diagram of the structure of an electronic device provided in one embodiment of this application. The electronic device 100 includes an electronic device structural component 11, a flexible screen 12, a first housing 13, and a second housing 14. The first housing 13 is rotatably connected to the second housing 14 through the electronic device structural component 11. The flexible screen 12 is fixedly connected to the first housing 13 and the second housing 14 and covers the electronic device structural component 11. The electronic device structural component 11 is a pivot to improve the reliability and service life of the electronic device.

[0067] The effects of the ultra-high strength steel provided in this application will be further illustrated by specific embodiments below.

[0068] Example 1

[0069] Iron, nickel, cobalt, molybdenum, and titanium sources were mixed and melted in a vacuum environment at 1650℃, and then atomized with water vapor to obtain alloy powder with a particle size of 8 μm and a density of 7.795 g / cm³. 3 The melt flow index is 1200 g / 10 min. A binder is prepared by mixing 90 wt% polyoxymethylene, 3 wt% antioxidant, 4 wt% polyethylene, and 3 wt% vinyl acetate polymer in a kneader at 170°C for 120 min. The alloy powder and binder are mixed at a volume ratio of 3:2 and placed in an internal mixer, where they are mixed at 160°C for 120 min to obtain the feedstock. The material was injected into the mold at an injection temperature of 200℃, an injection pressure of 120MPa, and a mold cavity temperature of 120℃. Then, it was degreased by heating to 120℃ and holding for 10 hours in nitric acid and nitrogen atmosphere, followed by sintering. The sintering process included two stages: the first stage involved heating to 600℃ for 60 minutes and holding for 180 minutes under a pressure less than 5 kPa; the second stage involved heating to 900℃ for 60 minutes and holding for 120 minutes, then heating to 1080℃ for 50 minutes and holding for 30 minutes, then heating to 1200℃ for 60 minutes and holding for 30 minutes under a pressure less than 15 kPa, then heating to 1340℃ for 60 minutes and holding for 120 minutes. Finally, it was cooled to room temperature under a nitrogen atmosphere for 30 minutes to obtain the preform material with a density of 7.755 g / cm³. 3 .

[0070] The precast material is placed in a vacuum heat treatment furnace with a pressure of less than -0.1 kPa. The temperature is raised to 200°C in 30 minutes and held for 30 minutes, then raised to 600°C in 30 minutes and held for 20 minutes, and finally raised to 860°C in 30 minutes and held for 120 minutes for solution treatment. Then, it undergoes cryogenic treatment in liquid nitrogen for 60 minutes, followed by aging treatment. The aging treatment includes heating to 200℃ for 30 minutes and holding for 30 minutes, heating to 550℃ for 360 minutes and holding for 30 minutes, and then purging with nitrogen and cooling to room temperature for 30 minutes to obtain ultra-high strength steel material. The ultra-high strength steel includes 17.5 wt% nickel, 12.5 wt% cobalt, 5.1 wt% molybdenum, 0.32 wt% titanium, 0.02 wt% carbon, 0.005 wt% sulfur, 0.14 wt% sulfur, 0.06 wt% manganese, and the balance iron.

[0071] Examples 2-8

[0072] The difference between Examples 2-8 and Example 1 lies in the different contents of each element in the ultra-high strength steel, as shown in Table 1.

[0073] Table 1. Content of each element in the ultra-high strength steel obtained in Examples 2-8

[0074]

[0075]

[0076] Example 9

[0077] Similar to Example 1, except that the second stage of sintering involves heating from 600°C to 1340°C at a rate of 10°C / min and holding at that temperature for 120 min, followed by cooling to room temperature for 30 min under a nitrogen atmosphere.

[0078] Example 10

[0079] Similar to Example 1, except that the temperature is directly raised to 860°C and held for 120 minutes for solution treatment.

[0080] Example 11

[0081] The process is largely the same as in Example 1, except that the temperature is directly raised to 550°C and held for 360 minutes for aging treatment.

[0082] Comparative Examples 1-10

[0083] The difference between Comparative Examples 1-10 and Example 1 lies in the different amounts of each element in the prepared materials, as shown in Table 2.

[0084] Table 2 shows the content of each element in the materials obtained from Comparative Examples 1-10.

[0085]

[0086] The strength and plasticity of the materials obtained in the examples and comparative examples were tested to obtain force (MPa)-displacement (mm) curves, yield strength, tensile strength and elongation were obtained. The standard was that the yield strength was greater than 1800MPa, the tensile strength was greater than 1900MPa and the elongation was greater than 4%. The ultra-high strength steels obtained in Examples 1 to 11 all met the standard, and the test results of Example 1 were better than those of Examples 7 to 11. The steel structures obtained in Comparative Examples 1 to 10 did not meet the standard.

[0087] Meanwhile, the force-displacement curves of the ultra-high strength steel obtained in Examples 1-4 are as follows: Figures 5-8As shown in Table 3, the specific test values ​​are as follows. The force-displacement curves and specific test values ​​of Examples 5-11 are similar to those of Examples 1-4, and will not be repeated here. It can be seen that the method of this application can produce ultra-high strength steel with good strength and excellent plasticity, which is beneficial to its use.

[0088] Table 3. Properties of the ultra-high strength steels obtained in Examples 1-4

[0089]

[0090]

[0091] 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. An ultra-high strength steel, characterized in that, The ultra-high strength steel comprises 17.7wt%-20wt% nickel, 11wt%-12.5wt% cobalt, 4.5wt%-5.5wt% molybdenum, 0.2wt%-0.5wt% titanium, less than 0.1wt% carbon, and the balance iron. The preparation method of the ultra-high strength steel includes: The alloy powder is mixed with the binder and then granulated by kneading to obtain the feed. The feed is injected, degreased and sintered to obtain a preform material. The sintering includes a first stage and a second stage. The first stage includes heating to 570℃-630℃ at a rate of 8℃ / min-12℃ / min and holding for 150min-200min. The second stage includes heating at a rate of 1℃ / min-5℃ / min, heating to 870℃-930℃ from the first stage and holding for 90min-150min, then heating to 1050℃-1110℃ and holding for 20min-50min, then heating to 1170℃-1230℃ and holding for 20min-50min, then heating to 1300℃-1340℃ and holding for 100min-150min, and then cooling at a rate of 35℃ / min-45℃ / min. The prefabricated material is subjected to solution treatment, cryogenic treatment and aging treatment to obtain the ultra-high strength steel.

2. The ultra-high strength steel as described in claim 1, characterized in that, The ultra-high strength steel contains a martensite content of 82% or greater by mass.

3. The ultra-high strength steel as described in claim 1, characterized in that, The nickel content in the ultra-high strength steel is 17.7wt%-18.9wt%. The carbon content in the ultra-high strength steel is less than or equal to 0.03 wt%.

4. The ultra-high strength steel as described in claim 1, characterized in that, The cobalt content in the ultra-high strength steel is 11.4 wt%-12.5 wt%. The molybdenum content in the ultra-high strength steel is 4.8 wt%-5.3 wt%. The titanium content in the ultra-high strength steel is 0.32wt%-0.5wt%.

5. The ultra-high strength steel as described in claim 1, characterized in that, The ultra-high strength steel also includes impurity elements, the content of which is less than or equal to 0.4 wt%. The impurity elements include at least one of sulfur, silicon, and manganese, wherein the sulfur content in the ultra-high strength steel is less than or equal to 0.025 wt%, the silicon content is less than or equal to 0.2 wt%, and the manganese content is less than or equal to 0.1 wt%.

6. The ultra-high strength steel as described in claim 1, characterized in that, The ultra-high strength steel has a yield strength greater than 1800 MPa, a tensile strength greater than 1900 MPa, and an elongation greater than 4%.

7. A method for preparing ultra-high strength steel, characterized in that, include: The alloy powder is mixed with the binder and then granulated by kneading to obtain the feed. The feed is injected, degreased and sintered to obtain a preform material. The sintering includes a first stage and a second stage. The first stage includes heating to 570℃-630℃ at a rate of 8℃ / min-12℃ / min and holding for 150min-200min. The second stage includes heating at a rate of 1℃ / min-5℃ / min, heating to 870℃-930℃ from the first stage and holding for 90min-150min, then heating to 1050℃-1110℃ and holding for 20min-50min, then heating to 1170℃-1230℃ and holding for 20min-50min, then heating to 1300℃-1340℃ and holding for 100min-150min, and then cooling at a rate of 35℃ / min-45℃ / min. The prefabricated material is subjected to solution treatment, cryogenic treatment and aging treatment to obtain ultra-high strength steel, which includes 17.7wt%-20wt% nickel, 11wt%-12.5wt% cobalt, 4.5wt%-5.5wt% molybdenum, 0.2wt%-0.5wt% titanium, less than 0.1wt% carbon and the balance iron.

8. The preparation method according to claim 7, characterized in that, The solution treatment includes treatment at 800℃-900℃ for 60min-120min; The cryogenic treatment includes treatment at -211℃ to -191℃ for 50-70 minutes; The aging treatment includes treatment at 450℃-560℃ for 3-7 hours.

9. The preparation method according to claim 8, characterized in that, The solution treatment includes heating to 150℃-250℃ at a rate of 5℃ / min-10℃ / min and holding for 20min-60min, heating to 550℃-650℃ at a rate of 10℃ / min-15℃ / min and holding for 15min-40min, and heating to 800℃-900℃ at a rate of 5℃ / min-10℃ / min and holding for 60min-120min; The aging process includes heating to 150℃-250℃ at a rate of 5℃ / min-10℃ / min and holding at that temperature for 20min-60min, and then heating to 450℃-560℃ at a rate of 5℃ / min-10℃ / min and holding at that temperature for 3h-7h.

10. The preparation method according to claim 7, characterized in that, The alloy powder has a particle size D50 of 7μm-10μm and a melt index of 300g / 10min-1700g / 10min; The adhesive comprises 3wt%-5wt% polyethylene, 2wt%-6wt% vinyl acetate polymer, and the balance polyoxymethylene; During the mixing process, the volume ratio of the alloy powder to the binder is (29-31):(19-21). The injection temperature is 150℃-250℃, the injection pressure is 80MPa-150MPa, and the mold cavity temperature is 100℃-140℃. The degreasing process involves heating in nitric acid and inert gas to 110°C-125°C and holding at that temperature for 4-6 hours.

11. A structural component for an electronic device, characterized in that, The material of the electronic device structural components includes the ultra-high strength steel described in any one of claims 1-6.

12. An electronic device, characterized in that, The invention includes electronic device structural components, wherein the material of the electronic device structural components includes the ultra-high strength steel as described in any one of claims 1-6.

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