Maraging steel, preparation method for maraging steel and electronic device

Abstract

Embodiments of the present application provide a maraging steel, a preparation method for maraging steel and an electronic device. The maraging steel comprises the following alloy elements: Co, Mo and Ti, by weight percentage, the Co content being 12 wt%-17 wt%, the Mo content being 6 wt%-8 wt%, and the Ti content being 0.4 wt%-1.5 wt%; the maraging steel also comprises the following alloy elements: Ni, Al and Fe, as well as impurity elements, the Ni content being 15 wt%-18 wt%, Al ≤ 0.3 wt%, and the remainder being Fe and impurity elements. The maraging steel, the preparation method for maraging steel and the electronic device provided in the embodiments of the present application can cause the maraging steel to have both high strength and high plasticity.

Description

Maraging steel, method for preparing maraging steel, and electronic device

[0001] This application claims priority to Chinese patent application number 202310694134.7, filed with the State Intellectual Property Office of China on June 12, 2023, entitled “Martening steel, method for preparing maraging steel, and electronic device,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] The embodiments of the present application relate to the technical field of alloy steel, and more specifically, to a maraging steel, a method for preparing the maraging steel, and an electronic device. Background Art

[0003] Maraging steel is an ultra-high-strength steel based on an iron-nickel martensite matrix. Due to its excellent strength and ductility, it is widely used in aerospace, instrumentation, machinery, and other fields. Existing maraging steels contain high levels of Ni and Ti to strengthen the material through the formation of intermetallic Ni3Ti precipitates. However, during the smelting process, Ti reacts with the impurity element N to form TiN inclusions, which further reduce the material's plasticity. Consequently, as the strength of maraging steel increases, its plasticity also decreases significantly, significantly limiting its application and reducing the safety and reliability of its application.

[0004] Summary of the Invention

[0005] The embodiments of the present application provide a maraging steel, a method for preparing the maraging steel, and an electronic device, which can ensure that the maraging steel has both high strength and high plasticity.

[0006] In a first aspect, a maraging steel is provided, comprising the following alloying elements: Co, Mo, and Ti, wherein, by weight percentage, the Co content is 12 wt% to 17 wt%, the Mo content is 6 wt% to 8 wt%, and the Ti content is 0.4 wt% to 1.5 wt%.

[0007] In the embodiments provided herein, by controlling the Ti content, large Ti-containing inclusions in the maraging steel can be reduced, thereby preventing the large Ti-containing inclusions from reducing the plasticity of the steel. At the same time, by increasing the Co and Mo contents, the strength loss of the maraging steel caused by reducing the Ti content can be compensated, thereby enabling the maraging steel to have good comprehensive mechanical properties, combining high strength and high plasticity.

[0008] In combination with the first aspect, in certain implementations of the first aspect, the maraging steel further includes the following alloying elements: Ni, Al, and Fe, and impurity elements, wherein, by weight percentage, the Ni content is 15 wt% to 18 wt%, Al is ≤ 0.3 wt%, and the balance is Fe and impurity elements.

[0009] In the embodiments provided herein, by controlling the Al content to a relatively low level, the generation of large inclusions such as AlN can be reduced, thereby avoiding adverse effects on the plasticity of the maraging steel. Furthermore, by controlling the Ni content to an appropriate level, the maraging steel can have both high strength and high plasticity.

[0010] In combination with the first aspect, in certain implementations of the first aspect, the impurity elements include one or more of the following elements: C, Mn, O, S, N and P, and the contents of the impurity elements, calculated by weight percentage, are: C ≤ 0.01 wt%, Mn ≤ 0.01 wt%, total oxygen content TO ≤ 0.0015 wt%, S ≤ 0.0020 wt%, N ≤ 0.0015 wt%, and P ≤ 0.0050 wt%.

[0011] In the embodiments provided herein, by controlling the content of impurity elements to be relatively low, it is possible to avoid the adverse effects of impurity elements on the plasticity of the maraging steel, so that the maraging steel can have both high strength and high plasticity.

[0012] In combination with the first aspect, in certain implementations of the first aspect, the tensile strength of the maraging steel is greater than or equal to 2500 MPa, and the yield strength is greater than or equal to 2500 MPa.

[0013] In combination with the first aspect, in certain implementations of the first aspect, the elongation of the maraging steel is greater than or equal to 12%.

[0014] In combination with the first aspect, in certain implementations of the first aspect, the reduction of area of ​​the maraging steel is greater than or equal to 60%.

[0015] In a second aspect, a method for preparing maraging steel is provided, for preparing the maraging steel according to the first aspect or any possible implementation of the first aspect, the method comprising: weighing metal raw materials corresponding to alloying elements according to a designed composition, smelting and casting the metal raw materials; performing multiple forging on the cast steel ingot, wherein the total forging ratio after the multiple forgings is greater than or equal to 10; and performing deep cryogenic treatment and aging treatment on the steel ingot after the multiple forgings.

[0016] In the embodiments provided herein, the ingot obtained after smelting and casting is subjected to multiple forgings, and the total forging ratio after the multiple forgings is greater than or equal to 10. This can refine the internal structure of the maraging steel, thereby improving both the strength and the plasticity of the maraging steel. The mechanical properties of the maraging steel can be further optimized through cryogenic treatment and aging treatment.

[0017] In combination with the second aspect, in certain implementations of the second aspect, the temperature of the last forging process in the multiple forging processes is 750° C. to 1050° C.

[0018] In the embodiment provided in the present application, the temperature of the last forging process in the multiple forging processes is 750° C. to 1050° C., which can further refine the internal structure of the maraging steel, thereby improving both the strength and the plasticity of the maraging steel.

[0019] In combination with the second aspect, in certain implementations of the second aspect, the temperature of the cryogenic treatment is lower than -73°C, and the holding time is 1 hour to 10 hours.

[0020] In the embodiments provided in the present application, the steel ingot is cryogenically treated at a temperature below -73°C and kept warm for 1 to 10 hours, which can effectively improve the plasticity of the steel without reducing the strength of the steel.

[0021] In combination with the second aspect, in certain implementations of the second aspect, the heating temperature of the aging treatment is 450° C. to 530° C., and the holding time is 3 h to 10 h.

[0022] In the embodiments provided in the present application, the steel ingot is heated to 450° C. to 530° C. and kept warm for 3 h to 10 h for aging treatment, which can make the steel ingot have both high strength and high plasticity.

[0023] In combination with the second aspect, in certain implementations of the second aspect, smelting the raw materials includes smelting the raw materials in one or more of the following ways: converter smelting, refining outside the furnace, vacuum induction, vacuum consumables, and electroslag remelting.

[0024] In the embodiments provided herein, smelting the metal raw material by one or more of converter smelting, external refining, vacuum induction, vacuum consumable metal, and electroslag remelting can improve smelting efficiency. Smelting the metal raw material in two or more steps can further improve the quality of maraging steel and its mechanical properties. Smelting by vacuum induction and vacuum consumable metal can reduce the impurity content in the maraging steel, thereby preventing the impurity elements from adversely affecting the plasticity of the maraging steel.

[0025] In combination with the second aspect, in certain implementations of the second aspect, before the multiple forging of the cast steel ingot, the method further includes: homogenizing the cast steel ingot, and the temperature of the homogenization treatment is 1170°C to 1230°C.

[0026] In the embodiments provided in the present application, after the steel ingot is cast, the steel ingot is homogenized within a temperature range of 1170°C to 1230°C, which can improve the internal crystal structure of the steel, eliminate casting stress, and optimize the mechanical properties of the steel ingot.

[0027] In a third aspect, an electronic device is provided, comprising one or more parts made of the maraging steel as described in the first aspect or any possible implementation of the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG1 is a schematic flow chart of a method for preparing maraging steel provided in an embodiment of the present application.

[0029] FIG2 is a fracture morphology diagram of a maraging steel sample after stretching provided in an embodiment of the present application. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

[0031] References to "one embodiment" or "some embodiments" in this specification mean that a particular feature, structure, or characteristic described in conjunction with that embodiment is included in one or more embodiments of the present application. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in yet other embodiments" appearing in various places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized.

[0032] The terms "include", "comprising", "having" and variations thereof mean "including but not limited to", unless specifically emphasized otherwise.

[0033] Martensite is a hard but low-plastic microstructure in steel. It is relatively stable at low temperatures (including room temperature) and provides strength to the material as a whole. Maraging steel mainly achieves strengthening effect by precipitating intermetallic compounds during aging treatment, and toughening effect by reversing austenite in thin film. Typical representatives are 18Ni series, including C200, C250 and C500. Table 1 shows the content of main alloying elements (by weight percentage) in several typical maraging steels C200, C250, C300 and C350, and Table 2 shows the room temperature mechanical properties parameters of maraging steels C200, C250, C300 and C350. Among them, σ b is the tensile strength of the material, that is, the maximum stress value that the material can withstand before breaking in a tensile test; σ 0.2 is the yield strength, that is, the stress value that the material withstands when yielding in a tensile test. Metal materials are generally stipulated to have a stress value of 0.2% residual deformation as their yield strength; A is the elongation at break, which can also be referred to as elongation, that is, the ratio of the difference between the length of the test section and the original length after the material is broken to the original length; Z is the cross-sectional shrinkage, that is, the ratio of the difference between the cross-sectional area at the fracture and the original cross-sectional area after the material is broken to the original cross-sectional value.

[0034] It can be seen from Table 1 and Table 2 that the yield strength σ of 18Ni series steel is improved by increasing the content of Co, Mo and Ti. 0.2 and tensile strength σ b The steel grade with the highest strength is C350, which is continuously improved from C200 to C350. b and σ 0.2 Approximately 2410MPa and 2340MPa, respectively. The Mo content in maraging steels C250 to C350 is 4.8%, and their strength is enhanced by the combined strengthening of Co and Ti. As the Ti content increases, the strength of maraging steel increases, but its plasticity also decreases significantly. The elongation of C350 is approximately 7%, while the plasticity of the higher-strength C400 decreases further, significantly limiting its application. Therefore, while increasing the strength of maraging steel, further improving its plasticity is crucial for its scope of engineering applications and its safety and reliability.

[0035] Table 1

[0036] Table 2

[0037] In view of the above problems, the embodiments of the present application provide a maraging steel having a new alloy composition ratio, which can make the maraging steel have both high strength and high plasticity.

[0038] The maraging steel may include the following alloying elements: Co, Mo, and Ti, wherein, by weight percentage, the Co content is 12 wt% to 17 wt%, the Mo content is 6 wt% to 8 wt%, and the Ti content is 0.4 wt% to 1.5 wt%.

[0039] For example, the content of Co in weight percentage may be 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt% or 17 wt%, etc. For example, the content of Co may be 14 wt% to 16 wt%, or 14.5 wt% to 15.5 wt%, or 14.6 wt% to 15.4 wt%, or 14.7 wt% to 15.3 wt%, or 14.8 wt% to 15.2 wt%, or 14.9 wt% to 15.1 wt%, etc.

[0040] For example, the content of Mo may be 6 wt%, 6.4 wt%, 6.8 wt%, 7.2 wt%, 7.6 wt% or 8 wt%, etc. For example, the content of Mo may be 7 wt% to 8 wt%, or 7 wt% to 7.5 wt%, or 6.9 wt% to 7.6 wt%, or 6.8 wt% to 7.7 wt%, or 6.7 wt% to 7.8 wt%, etc.

[0041] For example, the Ti content may be 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, or 1.5 wt%, etc. For example, the Ti content may be 0.5 wt% to 1.2 wt%, or 0.4 wt% to 1.3 wt%, or 0.3 wt% to 1.4 wt%, etc.

[0042] In maraging steel, Co does not form compounds with other elements in the alloy system. However, Co can inhibit dislocation recovery in the martensitic matrix, increase the dislocation density of the martensitic matrix, and provide nucleation sites for the precipitation of the second phase in the steel during the subsequent aging process, effectively promoting the aging strengthening reaction. Furthermore, Co can increase the martensitic transformation starting temperature (martensite start, Ms point), reducing the tendency of martensite to transform into reverse austenite, thereby helping to improve the strength of maraging steel. The Ms point is the temperature at which the difference in free energy between the austenite and martensite phases reaches the minimum driving force (critical driving force) required for phase transformation. Therefore, in the examples of the present application, a higher Co content is controlled to improve the strength of maraging steel.

[0043] Mo can form Ni3Mo intermetallic compounds with Ni, thereby strengthening the matrix. In the embodiment of the present application, by increasing the Mo content to 6% to 8%, a strong precipitation strengthening effect can be achieved, meeting the strength requirements of the material.

[0044] Ti can increase the strength of steel by forming Ni3Ti during the aging process, but this can lead to a significant loss of toughness. Furthermore, when the Ti content is too high, it easily combines with nitrogen in the steel to form large, angular TiN inclusions, which can cause localized stress concentration and lead to crack initiation. Therefore, in the examples of this application, a low Ti content is maintained to balance the strength and ductility of maraging steel.

[0045] In summary, in the embodiments provided herein, by controlling the Ti content, large Ti-containing inclusions in the maraging steel can be reduced, thereby preventing the large Ti-containing inclusions from damaging the properties of the steel. At the same time, by increasing the Co and Mo contents, the strength loss of the maraging steel caused by reducing the Ti content can be compensated, so that the maraging steel can have good comprehensive mechanical properties, with both high strength and high plasticity.

[0046] The maraging steel may further include the following alloying elements: Ni, Al, Fe, and impurity elements, wherein, by weight percentage, the Ni content is 15wt% to 18wt%, Al≤0.3wt%, and the balance is Fe and impurity elements.

[0047] For example, in terms of weight percentage, the Ni content may be 15 wt%, 15.5 wt%, 16 wt%, 16.5 wt%, 17 wt%, 17.5 wt%, or 18 wt%, etc. For example, the Ni content may range from 15 wt% to 16.1 wt%, or from 14.9 wt% to 16.2 wt%, or from 14.8 wt% to 16.2 wt%, or from 14.7 wt% to 16.3 wt%, or from 14.6 wt% to 16.4 wt%, etc.

[0048] For example, the Al content may be 0.05 wt%, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt% or 0.3 wt%, etc. For example, the Al content may be less than 0.2 wt%, or less than 0.5 wt%, or 0.1 wt% to 0.15 wt%, etc.

[0049] In maraging steel, nickel has no direct strengthening effect on the martensite matrix. However, nickel is an austenite-stabilizing element and can promote the formation of reverse-transformed austenite during aging, which has a positive effect on improving the plasticity and toughness of maraging steel. In the examples provided herein, nickel can form certain amounts of Ni3Ti and Ni3Mo with Ti and Mo, which can play a role in precipitation strengthening.

[0050] Al easily forms large-sized AlN inclusions in steel, which impairs the toughness and plasticity of the steel. Therefore, in the embodiment of the present application, the Al content can be controlled to not exceed 0.3 wt %.

[0051] In summary, in the embodiments provided herein, by controlling the Al content to a relatively low level, the adverse effects of compounds such as AlN on the plasticity of the maraging steel are reduced, and by comprehensively considering the strength and plasticity of the maraging steel and controlling the appropriate Ni content, the maraging steel can have both high strength and high plasticity.

[0052] The impurity elements in the maraging steel include one or more of the following elements: C, Mn, O, S, N and P. In terms of weight percentage, the contents of the impurity elements are: C≤0.01wt%, Mn≤0.01wt%, total oxygen content TO≤0.0015wt%, S≤0.0020wt%, N≤0.0015wt%, and P≤0.0050wt%.

[0053] The total oxygen (TO) content is the total oxygen content in the steel, including oxygen atoms in the solid solution, molecular oxygen in defects, and oxygen contained in oxides in inclusions.

[0054] C has a significant effect on the strength of martensite, but in steel, C easily combines with Ti to form large-sized TiC, which is detrimental to the plasticity of the steel. S easily segregates at grain boundaries. The higher the S content in the steel, the higher the S content at the grain boundaries, which reduces the grain boundary strength and easily has an adverse effect on the plasticity of the steel. P has strong solid solution strengthening and cold work hardening in steel, which can improve the strength and hardness of the steel. However, P also easily segregates at the grain boundaries, resulting in a decrease in the plasticity and toughness of the steel. N in steel can cause age hardening of the steel, and the strength and hardness of the steel will increase over time, while the plasticity will decrease. The amount of O that can be dissolved in solid steel is extremely low. Excess O will precipitate from the molten steel during solidification, forming inclusions or foam, affecting the mechanical properties of the steel, especially the plasticity and toughness. In addition, O in steel will aggravate the hot brittleness hazard of S.

[0055] In the embodiments provided herein, by controlling the content of impurity elements to be relatively low, it is possible to avoid the adverse effects of impurity elements on the plasticity of maraging steel, thereby improving the strength and plasticity of maraging steel.

[0056] The maraging steel provided in the embodiments of the present application has a tensile strength and a yield strength of greater than or equal to 2500 MPa, an elongation of greater than or equal to 12%, and a cross-sectional reduction rate of greater than or equal to 60%, and has both high strength and high plasticity.

[0057] The maraging steel provided in the embodiments of the present application can be used in various product components with high load-bearing requirements. For example, it can be used in components of electronic devices, including components of mobile phones, foldable phones, personal computers, tablet computers, or wearable devices. It can also be used in load-bearing components in aerospace, instruments and equipment, tools and equipment, etc., and this application does not limit this.

[0058] An embodiment of the present application further provides an electronic device comprising one or more components made of the aforementioned maraging steel.

[0059] The embodiment of the present application further provides a method for preparing maraging steel, which is used to prepare maraging steel having the above alloy element content ratio. As shown in FIG. 1 , the preparation method may include steps S101 to S103 .

[0060] S101, weighing metal raw materials corresponding to the alloy elements according to the designed composition, smelting and casting the metal raw materials.

[0061] That is, based on the weight content of the alloying elements of the maraging steel, namely, Co 12wt% to 17wt%, Mo 6wt% to 8wt%, Ti 0.4wt% to 1.5wt%, Ni 15wt% to 18wt%, Al ≤ 0.3wt%, and Fe, a certain mass of single metal raw materials, such as Co blocks, Mo blocks, Ti blocks, Ni blocks, Al blocks, and Fe blocks, can be weighed, smelted, and cast into steel ingots, etc., so that the alloying element contents in the cast steel ingots meet the above ratios.

[0062] It should be noted that the metal element raw materials in the embodiments of the present application may not be 100% pure elements, and the presence of inevitable impurity elements introduced during the production and processing process is allowed. The above-mentioned impurity elements such as S, O, P, etc. can be inevitable impurity elements introduced into the metal element raw materials, or impurity elements introduced into the smelting atmosphere.

[0063] In some embodiments, the raw materials may be smelted in one or more of the following ways: converter smelting, external refining, vacuum induction, vacuum consumables, and electroslag remelting.

[0064] Converter smelting, among other processes, relies on the physical heat of the molten iron and the heat generated by chemical reactions between its components to complete steelmaking in the converter without the need for external energy. Impurities are removed by blowing high-pressure air or oxygen into the converter. Off-furnace refining involves transferring molten iron from a vessel such as a converter to another vessel for refining. The molten steel, after initial smelting, is then subjected to desulfurization, deoxygenation, and inclusion removal in an inert gas or vacuum environment to improve steel quality. Vacuum induction involves melting metal in a vacuum environment using electromagnetic induction to generate eddy currents. Vacuum smelting can remove dissolved nitrogen, hydrogen, oxygen, and carbon from the steel to levels far lower than smelting under atmospheric pressure. Vacuum consumable smelting involves using the raw materials as an electrode in a vacuum. The raw materials are gradually melted by the arc at high temperatures, dripped into a mold, and gradually condensed into a steel ingot. Vacuum consumable smelting achieves rapid melting and condensation rates, resulting in a more uniform alloy composition. Furthermore, vacuum smelting effectively removes impurities dissolved in the steel. Electroslag remelting (ESR) is a smelting method that uses the resistance heat generated by passing an electric current through molten slag as a heat source. For example, it can be used to refine steel ingots obtained after smelting processes such as converter smelting or vacuum induction smelting.

[0065] The smelting process may include one or more smelting steps. For example, the smelting process may include two smelting steps. For example, the raw materials may be first smelted by a vacuum induction method, and then secondary refined by vacuum consumable remelting or electroslag remelting to improve the purity of the steel, further reduce the impurity content, improve the internal structure of the steel, and optimize the mechanical properties of the steel.

[0066] S102, forging the steel ingot obtained by casting multiple times, and the total forging ratio after the multiple forgings is greater than or equal to 10.

[0067] The forging ratio, also known as the forging ratio, is the ratio of the steel's cross-sectional area before and after forging. A total forging ratio of 10 or greater refers to the ratio of the steel's cross-sectional area before forging to its cross-sectional area after multiple forgings. Alternatively, it can be the ratio of the steel's length before forging to its length after forging.

[0068] For example, the total forging ratio of the multiple forgings may be 10, 11, 12, 13, 14 or 15, etc.

[0069] In some embodiments, the temperature of the last forging process in the multiple forging processes may be 750°C to 1050°C.

[0070] For example, the temperature of the last forging process in the multiple forging processes may be 750° C., 800° C., 850° C., 900° C., 950° C., 1000° C., or 1050° C., etc.

[0071] The initial forging temperature of the steel ingot can be less than or equal to 1220°C, or in other words, the temperature at the start of forging can be less than or equal to 1220°C. The temperature of the steel ingot can be continuously reduced during the multiple forging processes. The embodiments of this application do not limit the number of forging processes; it is only necessary that the temperature of the final forging and the total forging ratio achieved meet the above requirements.

[0072] In the embodiment of the present application, the steel ingot obtained by casting is forged, and the temperature of the last forging process is 750°C to 1050°C, and the total forging ratio is greater than or equal to 10, which can refine the internal structure of the steel, thereby improving both the strength and the plasticity of the steel.

[0073] In some embodiments, before the cast steel ingot is forged multiple times, the steel ingot may be homogenized. The homogenization temperature may be 1170° C. to 1230° C., and the homogenization time may be 3 h to 10 h.

[0074] For example, the temperature of the homogenization treatment can be 1170°C, 1180°C, 1190°C, 1200°C, 1210°C or 1230°C, etc.; the time of the homogenization treatment can be, for example, 3h, 4h, 5h, 6h, 7h, 8h, 9h or 10h, etc.

[0075] The homogenization time can be adjusted according to the sample size. The larger the sample size, the longer the homogenization time can be to ensure that the sample is heated through and to avoid coarsening of steel grains due to long-term heat preservation.

[0076] In the embodiment of the present application, after the steel ingot is cast, the steel ingot is subjected to a homogenization treatment, which can improve the internal crystal structure of the steel, eliminate casting stress, and optimize the mechanical properties of the steel ingot.

[0077] S103, performing deep cryogenic treatment and aging treatment on the steel ingot after multiple forging.

[0078] Cryogenic treatment is a method of treating steel ingots at low temperatures using liquid nitrogen as a refrigerant.

[0079] In some embodiments, the temperature of the cryogenic treatment is lower than -73°C, and the holding time is 1 hour to 10 hours.

[0080] Illustratively, the temperature of the cryogenic treatment can be -73°C, -80°C, -90°C, -100°C, -110°C, -120°C, -130°C, -140°C or -150°C, etc.; the holding time can be, for example, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h or 10h, etc.

[0081] In the embodiment of the present application, the steel ingot is cryogenically treated at a temperature below -73°C and kept warm for 1 to 10 hours, which can effectively improve the plasticity of the steel without reducing the strength of the steel.

[0082] Aging is a heat treatment process that places the steel ingot at a higher temperature to maintain its shape and size, allowing its properties to change over time. This aging process can be performed after cryogenic treatment. Before aging, the cryogenically treated steel ingot can be warmed to room temperature in air before aging.

[0083] In some embodiments, the heating temperature of the aging treatment may be 450° C. to 530° C., and the holding time may be 3 hours to 10 hours.

[0084] For example, the aging treatment temperature can be 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, 510, 520°C or 530°C, etc.; the holding time can be, for example, 3h, 4h, 5h, 6h, 7h, 8h, 9h or 10h, etc.

[0085] The holding time refers to the time the steel ingot is held at the preset temperature. A holding time of 3 to 10 hours refers to heating the steel ingot to the preset temperature and then holding it there for 3 to 10 hours. After aging, the steel ingot can be allowed to air cool to room temperature to obtain the desired maraging steel.

[0086] In the embodiment of the present application, the steel ingot is heated to 450° C. to 530° C. and kept warm for 3 hours to 10 hours for aging treatment, which can make the steel ingot have both high strength and high plasticity.

[0087] As an example, Table 3 shows the alloying element contents (by weight percentage) in the maraging steel obtained using the above-described preparation method. The remaining impurity element contents all satisfy the following requirements: C ≤ 0.01 wt%, TO ≤ 0.0020 wt%, S ≤ 0.0030 wt%, N ≤ 0.0050 wt%, and P ≤ 0.0050 wt%. The preparation processes for steel grades 1 and 2 can be identical. Specifically, after smelting and casting into ingots, the steel is homogenized at 1200°C for 5 hours, then cooled and forged. The initial forging temperature is 1150°C, and the final forging temperature is 1000°C. The ingots are then forged into 12 mm (12 mm diameter) round bars. The forged specimens are first processed into drawn blanks and cryogenically treated at -73°C for 2 hours. The steel is then heated to room temperature in air and aged. The steel is then heated to 480°C, held for 6 hours, and then air-cooled. The resulting differences in alloying element content between steel #1 and steel #2 can be due to the test environment and experimental errors. Table 4 shows a comparison of the mechanical properties of steel #1 and steel #2 after heat treatment with those of C200, C250, C300, and C350 in the prior art. The mechanical property parameters corresponding to steel #1 and steel #1-2 are those obtained in repeated tests of steel #1, and the mechanical property parameters corresponding to steel #2 and steel #2-1 are those obtained in repeated tests of steel #2.

[0088] Table 3

[0089] Table 4

[0090] As can be seen from the data in Table 4, the maraging steel provided in the examples of the present application has significantly improved strength and ductility compared to existing maraging steels. The tensile strength and yield strength are both greater than 2500 MPa, the elongation is greater than 12.0%, and the reduction of area is greater than or equal to 60%. It has both high strength and high ductility.

[0091] Table 5

[0092] As another example, Table 5 shows the mechanical properties of steel grades 1 and 2, obtained through smelting and casting, after undergoing different aging treatments. Specifically, steel grades 1 and 2 were cryogenically treated after forging at a temperature of -73°C for 2 hours. The steels were then heated to room temperature in air before undergoing aging at 510°C.

[0093] Similarly, after aging treatment at different temperatures, the tensile strength and yield strength of steel #1 and steel #2 can both reach greater than or equal to 2500 MPa, the elongation can both reach greater than or equal to 12%, and the reduction of area can both reach greater than or equal to 60%. This maraging steel has both high strength and high plasticity.

[0094] FIG2 is a scanning electron microscope (SEM) image of a tensile fracture surface of the maraging steel provided in an example of the present application. As can be seen from the image, the fracture surface morphology includes a large number of dimples, exhibiting characteristics of plastic fracture, further demonstrating that the maraging steel provided in an example of the present application has good plasticity.

[0095] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A maraging steel, characterized in that: The maraging steel comprises the following alloy elements: Co, Mo, and Ti, wherein, by weight percentage, the content of Co is 12wt% to 17wt%, the content of Mo is 6wt% to 8wt%, and the content of Ti is 0.4wt% to 1.5wt%.

2. The maraging steel according to claim 1, characterized in that: The maraging steel further comprises the following alloy elements: Ni, Al and Fe, and impurity elements, wherein, by weight percentage, the Ni content is 15wt% to 18wt%, Al≤0.3wt%, and the balance is Fe and impurity elements.

3. The maraging steel according to claim 2, characterized in that: The impurity elements include one or more of the following elements: C, Mn, O, S, N and P. In terms of weight percentage, the contents of the impurity elements are: C≤0.01wt%, Mn≤0.01wt%, total oxygen content TO≤0.0015wt%, S≤0.0020wt%, N≤0.0015wt%, and P≤0.0050wt%.

4. The maraging steel according to any one of claims 1 to 3, characterized in that The tensile strength of the maraging steel is greater than or equal to 2500 MPa, and the yield strength is greater than or equal to 2500 MPa.

5. The maraging steel according to any one of claims 1 to 4, characterized in that: The elongation of the maraging steel is greater than or equal to 12%.

6. The maraging steel according to any one of claims 1 to 5, characterized in that The cross-sectional reduction rate of the maraging steel is greater than or equal to 60%.

7. A method for preparing maraging steel, for preparing the maraging steel according to any one of claims 1 to 6, characterized in that: The preparation method comprises: Weighing metal single substance raw materials corresponding to the alloy elements according to the designed composition, smelting and casting the metal single substance raw materials; The cast steel ingot is subjected to multiple forgings, wherein the total forging ratio after the multiple forgings is greater than or equal to 10; The steel ingot after the multiple forgings is subjected to deep cryogenic treatment and aging treatment.

8. The preparation method according to claim 7, characterized in that: The temperature of the last forging process in the multiple forging processes is 750°C to 1050°C.

9. The preparation method according to claim 7 or 8, characterized in that: The temperature of the deep freezing treatment is lower than -73°C, and the insulation time is 1 hour to 10 hours.

10. The preparation method according to any one of claims 7 to 9, characterized in that: The heating temperature of the aging treatment is 450° C. to 530° C., and the insulation time is 3 h to 10 h.

11. The preparation method according to any one of claims 7 to 10, characterized in that: The smelting of the metal element raw material comprises: The metal element raw material is smelted by one or more of the following methods: Converter smelting, external refining, vacuum induction, vacuum consumable and electroslag remelting.

12. The preparation method according to any one of claims 7 to 11, characterized in that: Before the steel ingot obtained by casting is forged multiple times, the preparation method further comprises: The cast steel ingot is homogenized at a temperature of 1170°C to 1230°C.

13. An electronic device, characterized in that: A component comprising one or more parts made of the maraging steel according to any one of claims 1 to 6.

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