Injection molding material, obtained maraging steel with ultra-high yield strength and application thereof

Abstract

The present invention belongs to the field of powder metallurgy materials and intelligent manufacturing technology, and relates to a metal material, in particular to an injection molding material, a maraging steel with ultra-high yield strength, and its application. An injection molding material, the mass percentage content of each chemical element of the material is: Ni 16.5~19wt%, Co 8.5~15wt%, Mo 5.6~8wt%, C≤0.03wt%, the balance is Fe, and unavoidable impurity elements. The material has excellent plasticity, and within this composition range, ultra-high strength steel with yield strength greater than 1800MPa, 1900MPa, and 2000MPa can be adjusted. The maraging steel described in the present invention can be used in aerospace, medical equipment, and especially in "3C" smart wearable devices, where both high strength and lightweight design are required.

Description

Technical Field

[0001] The present invention belongs to the field of powder metallurgy materials and intelligent manufacturing technology, and relates to a metal material, in particular to an injection molding material, a prepared maraging steel with ultra-high yield strength, and applications thereof. Background Art

[0002] Metal Injection Molding (MIM) is a novel powder metallurgy near-net-shape forming technology derived from the powder metallurgy and plastic injection molding industries. In recent years, this technology has evolved to maximize the solid particle content and completely remove the binder during the subsequent sintering process, resulting in densification of the preform. The basic MIM process involves selecting metal powder and a binder that meet MIM requirements. The powder and binder are then mixed into a uniform feed using an appropriate method at a specific temperature. After granulation, the feed is then injection molded. The resulting preform is then degreased and sintered to densify it into the final product.

[0003] MIM has high requirements for raw material powder. The selection of powder should be conducive to mixing, injection molding, degreasing and sintering, which are often contradictory. The research on MIM raw material powder includes: powder shape, particle size and particle size composition, specific surface area, etc.

[0004] Sintering is the final step in the MIM process. It eliminates the pores between powder particles, allowing MIM products to achieve full or near-full density. Because metal injection molding uses a large amount of binder, shrinkage during sintering is significant, typically reaching 13%-25%. This creates challenges in controlling deformation and dimensional accuracy.

[0005] In recent years, Metal Powder Injection Molding (MIM) products have primarily been used for key components in numerous industrial sectors, including electronics, automotive, and aerospace. Currently, the research and development of new materials in the MIM industry focuses on alloys such as specialty stainless steel, titanium alloys, and ultra-high-strength steel, with applications gradually expanding into high-end sectors such as automotive (including new energy vehicles), medical (including implants), aviation, and specialty hardware.

[0006] The report ranks MIM as the second most advanced technology among the top 10 advanced manufacturing technologies, and its development maturity far exceeds that of additive manufacturing (AM), which ranks first. This indicates that the MIM industry will continue to flourish globally. Ultra-high-strength steel, the material of choice for lightweight design of future equipment components and energy conservation and emission reduction, has significant military significance and commercial application value in its MIM preparation process and the development of new materials.

[0007] As one of the most important materials in ultra-high strength steel, maraging steel is widely used in aerospace, marine development and military fields due to its high strength, high toughness and good weldability. However, when it comes to hot-sintered ultra-high strength steel with a tensile strength of more than 2000MPa and an elongation greater than 5%, especially 18Ni series maraging steels such as C200, C250, C300, C350, etc., although excellent performance materials can be obtained through casting, forging and other processing methods, 18Ni (350) or C350 has excellent mechanical properties, with a yield strength of 2400MPa.

[0008] However, since the 18Ni series maraging steel matrix contains highly oxidizing elements such as Al and Ti, there are many problems in the injection molding technology based on powder technology, which is different from the preparation process such as casting and forging: (1) Oxidation during powder production. Since the specific surface area of ​​the powder is large, which can reach 1000 to 10000 times that of cast and forged materials, if the oxide formed cannot be reduced during high-temperature sintering, it will become a very sensitive inclusion defect in the ultra-high strength steel matrix, greatly weakening the material performance; (2) The metal powder is in a strong oxidizing environment to varying degrees during the feeding, mixing, injection, acid degreasing and other processes, which will further accelerate the process oxidation of the powder. It is precisely this inevitable process characteristic of the injection molding process that causes the material to undergo excessive oxidation, resulting in the loss of the main strengthening elements Al and Ti of the 18Ni series maraging steel as metal compound forming elements, and the formation of oxide inclusions in the material matrix, which ultimately makes it difficult for the MIM-related products of the 18Ni series maraging steel to meet the standard requirements of ultra-high strength and high plasticity. The main reasons for this problem are as follows:

[0009] 1. 18Ni series maraging steels, especially those with a tensile strength greater than 2000MPa, have stringent requirements on the content of C, O, and N in the steel. The injection molding process in MIM technology increases the content of C, O, and N in the steel, thereby reducing the toughness and plasticity of the material.

[0010] 2. The strengthening elements Al and Ti in the 18Ni series maraging steel are oxidized and lost during the MIM process, resulting in a decrease in material strength;

[0011] 3. In addition to the grain size and substructure in the martensitic structure, regulating the retained austenite in the matrix is ​​also an effective way to increase plasticity. Therefore, how to obtain maraging steel that meets the requirements of strength and plasticity through a reasonable heat treatment process is also one of the key technologies.

[0012] Given the above background, in actual engineering practice, metal parts currently molded using MIM technology struggle to simultaneously achieve the high plasticity standards of yield strength exceeding 1800 MPa and elongation exceeding 4%. Therefore, through rational composition design, thermal sintering process control, and subsequent heat treatment process design, injection molded sintered maraging steel with ultra-high tensile strength and good plasticity can be achieved. This can further expand the application of high-strength steel produced by MIM in high-end fields such as "3C", automotive (including new energy vehicles), medical (including implants), aviation, and specialty hardware. Summary of the Invention

[0013] The object of the present invention is to provide an injection molding material having excellent plasticity, a tensile strength greater than 1800 MPa, and suitable elongation.

[0014] The present invention also provides a maraging steel with ultra-high yield strength made from the injection molding material.

[0015] The technical solution adopted by the present invention to solve its technical problem is:

[0016] An injection molding material comprises the following chemical elements in percentage by weight: Ni 16.5-19wt%, Co 8.5-15wt%, Mo 5.6-8wt%, C≤0.03wt%, and the balance being Fe and unavoidable impurity elements.

[0017] Preferably, the material comprises the following chemical elements by weight: Ni 16.5-18.7wt%, Co 8.5-15wt%, Mo 5.6-7.0wt%, C ≤ 0.03wt%, with the balance being Fe and unavoidable impurities. This maraging steel exhibits a high yield strength and an elongation of 4.0-4.6%.

[0018] Preferably, the material comprises the following chemical elements by weight: Ni 17-19wt%, Co 13-15wt%, Mo 7.0-8.0wt%, C ≤ 0.03wt%, with the balance being Fe and unavoidable impurities. With this formulation, the resulting maraging steel exhibits a high yield strength exceeding 2000 MPa.

[0019] Preferably, the material comprises the following chemical elements by weight: Ni 17-19wt%, Co 13-15wt%, Mo 7.0-7.5wt%, C ≤ 0.03wt%, with the balance being Fe and unavoidable impurities. With this formulation, the maraging steel produced has a high yield strength exceeding 2000 MPa and a suitable elongation of 2.2-4.2%. Further preferably, the Ni content in the material is 17.5-19wt%. Further preferably, the Ni content is 18.5-18.7wt%, Co 13-15wt%, Mo 7.0-7.2wt%, C ≤ 0.03wt%, with the balance being Fe and unavoidable impurities. With this formulation, the maraging steel produced has a high yield strength exceeding 2000 MPa and a high elongation of 4.0-4.2%.

[0020] Preferably, the material comprises the following chemical elements by weight: Ni 17.5-19wt%, Co 10-15wt%, Mo 6.5-7.0wt%, C ≤ 0.03wt%, with the balance being Fe and unavoidable impurities. Further preferably, the material comprises the following chemical elements by weight: Ni 17.5-18.7wt%, Co 11-15wt%, Mo 6.5-7.0wt%, C ≤ 0.03wt%, with the balance being Fe and unavoidable impurities. With this formulation, the maraging steel produced exhibits high yield strength and a high elongation of 4.0-4.2%.

[0021] Preferably, the mass percentage content of each chemical element in the material is: Ni 16.5-18.5wt%, Co 8.5-13wt%, Mo 5.6-6.5wt%, C ≤ 0.03wt%, the balance being Fe and inevitable impurity elements. Under this formula, the maraging steel produced has a suitable high yield strength and a high elongation of 3.5-4.6%. Further preferably, the mass percentage content of each chemical element in the material is: Ni 17.0-18.5wt%, Co 8.8-13wt%, Mo 5.6-6.1wt%, C ≤ 0.03wt%, the balance being Fe and inevitable impurity elements. Further preferably, the mass percentage content of each chemical element in the material is: Ni 16.5-18.5wt%, Co 8.5-13wt%, Mo 6.1-6.5wt%, C ≤ 0.03wt%, the balance being Fe and inevitable impurity elements.

[0022] Preferably, the carbon content of the material after sintering is ≤0.02%. More preferably, the carbon content of the material after sintering is ≤0.015%. More preferably, the carbon content of the material after sintering is 0.0081% to 0.0133%.

[0023] As a preferred method, the metal powder raw material of the material is prepared by feeding, injection, degreasing, and sintered at 1380-1395℃, and the sintered density of the material is 7.8-8.1g / cm 3 The maximum sintered density of this material can reach about 8.1g / cm 3 It is further preferred that the sintered density of the material is 7.83-7.96 g / cm 3 .

[0024] A maraging steel made from the injection molding material of the present invention.

[0025] Preferably, the metal powder raw material for the injection molding material is prepared by feeding, injection, degreasing, sintering at 1380-1395°C, and solution heat treating at 920-1050°C for 1-3 hours to obtain maraging steel. The sintering time is generally controlled within 4-6 hours depending on the process requirements. Lower temperatures result in shorter sintering times, while higher temperatures result in longer sintering times.

[0026] Preferably, the metal powder raw material of the injection molding material is prepared by feeding, injection, degreasing, sintering at 1380-1395° C., solution heat treatment at 920-1050° C. for 1-3 hours, and then aging heat treatment at a temperature range of 460-500° C. for 1-8 hours to obtain maraging steel.

[0027] Preferably, the metal powder raw material of the injection molding material is prepared by feeding, injection, degreasing, sintering at 1380-1395° C., solution heat treatment at 920-1050° C. for 1-3 hours, followed by cryogenic treatment, and then aging heat treatment, wherein the aging heat treatment temperature range is 460-500° C. and the aging heat treatment time is 1-8 hours, to obtain maraging steel;

[0028] The cryogenic treatment is performed in liquid nitrogen at -193°C ± 5°C for 1 to 2 hours. The medium for the cryogenic treatment can be liquid nitrogen, dry ice, etc.

[0029] An application of the maraging steel of the present invention in the manufacture of 3C products, aviation products, and medical products.

[0030] An application of the maraging steel described in the present invention in the manufacture of smart wearable devices and their components.

[0031] The term "3C products" used in this article collectively refers to computer, communication, and consumer electronics products, also known as "information appliances." Examples include computers, tablets, mobile phones, and digital audio players. These products require wear resistance and lightweight design, so the choice of materials is unique.

[0032] Compared with the prior art, the present invention has the following advantages: the maraging steel made of the injection molding material of the present invention has an ultra-high yield strength, which can be increased to 1800-2100 MPa. While maintaining the yield strength of the material, its elongation can be increased to more than 4%. This material has sufficient toughness to avoid accidental impact during use (such as Therefore, it is suitable for applications in the manufacturing of 3C products, aviation products, and medical products, as well as in the manufacturing of smart wearable devices and their components. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The metallographic structures of the material obtained in Example 1 are shown in Figures a and b, respectively.

[0034] Figure 2 The metallographic structures of the material obtained in comparative example 1 are shown in Figures a and b, respectively, where a shows a large number of voids in the 18Ni300 material after sintering and b shows an abnormal metallographic image of the 18Ni300 material after corrosion. DETAILED DESCRIPTION

[0035] The following specific examples are used to further illustrate the technical solution of the present invention. It should be understood that the implementation of the present invention is not limited to the following examples, and any modifications and / or changes made to the present invention will fall within the scope of protection of the present invention.

[0036] In the present invention, unless otherwise specified, all parts and percentages are by weight, and the equipment and raw materials used are commercially available or commonly used in the art. The methods in the following examples are all conventional methods in the art unless otherwise specified.

[0037] Tensile strength, yield strength, and elongation testing methods: Materials are injected and sintered into mechanical tensile test bars. Testing is performed according to the national standard for tensile testing of metallic materials, GB / T228.1-2010. The sintered bars have a diameter of 3.20 ± 0.05 mm and a standard length of 25 mm. Elongation is calculated by measuring the fracture length. Tensile strength and yield strength are recorded using a microcomputer on the testing machine.

[0038] The core of the present invention is to provide an injection molding material comprising the following chemical elements by weight: Ni 16.5-19wt%, Co 8.5-15wt%, Mo 5.6-8wt%, C ≤ 0.03wt%, with the balance being Fe and unavoidable impurities. This material exhibits excellent plasticity, a tensile strength exceeding 1800 MPa, and suitable elongation.

[0039] Specifically, the material preferably comprises the following chemical elements by weight: Ni 16.5-18.7wt%, Co 8.5-15wt%, Mo 5.6-7.0wt%, C ≤ 0.03wt%, with the balance being Fe and unavoidable impurities. This formulation produces maraging steel with a high yield strength and an elongation of 4.0-4.6%.

[0040] Specifically, the material preferably comprises the following chemical elements by weight: Ni 17-19wt%, Co 13-15wt%, Mo 7.0-8.0wt%, C ≤ 0.03wt%, with the balance being Fe and unavoidable impurities. With this formulation, the resulting maraging steel exhibits a high yield strength exceeding 2000 MPa.

[0041] Another core of the present invention is to provide a maraging steel made from the injection molding material of the present invention.

[0042] In the present invention, the metal powder raw material for injection molding is prepared by feeding, injection, degreasing, sintering at 1380-1395°C, and solution heat treating at 920-1050°C for 1-3 hours to obtain maraging steel. The sintering time is generally controlled to be 4-6 hours depending on the process requirements. Lower temperatures result in shorter sintering times, while higher temperatures result in longer sintering times.

[0043] In the present invention, the metal powder raw material of the injection molding material is prepared by feeding, injection, degreasing, sintering at 1380-1395°C, solution heat treatment at 920-1050°C for 1-3 hours, and then aging heat treatment at a temperature range of 460-500°C for 1-8 hours to obtain maraging steel.

[0044] In the present invention, the metal powder raw material for injection molding is prepared through feeding, injection, degreasing, sintering at 1380-1395°C, solution heat treatment at 920-1050°C for 1-3 hours, followed by cryogenic treatment, and finally aging heat treatment at a temperature range of 460-500°C for 1-8 hours to produce maraging steel. The cryogenic treatment is performed in liquid nitrogen at -193°C ± 5°C for 1-2 hours. The cryogenic treatment medium can be liquid nitrogen, dry ice, or other media. This cryogenic treatment results in maraging steel with higher yield strength, tensile strength, and elongation.

[0045] Another core of the present invention is to provide an application of the maraging steel described in the present invention in the manufacturing of 3C products, aviation products, and medical products.

[0046] Another core of the present invention is to provide an application of the maraging steel described in the present invention in the manufacture of smart wearable devices and their components.

[0047] The invention is further described below through various embodiments.

[0048] Example Preparation Method of Maraging Steel

[0049] A method for preparing maraging steel, the method specifically comprising the following steps:

[0050] S1. Feed preparation: The raw metal powder of the injection molding material is mixed according to the formula with an appropriate amount of binder (generally about 10% by weight of the metal powder, the binder is mainly composed of polyoxymethylene plastic (POM), the binder and its amount are common knowledge in the art and are not the focus of the present invention) in a plastic mixer at a temperature of 175-200°C and granulated to produce metal powder feed;

[0051] S2, injection tensile test specimen: the above metal powder is fed into an injection molding machine to make a material tensile test standard specimen;

[0052] S3. Acid degreasing: In a degreasing furnace for injection molding, the above-mentioned tensile strips are catalytically degreased using nitric acid as a medium; the temperature condition for nitric acid degreasing is about 110°C.

[0053] The degreasing time is determined according to the degreasing rate of different materials to ensure that the acid degreasing rate is ≥95% (the amount of POM digested);

[0054] S4. Thermal debinding and sintering: The specimens obtained by acid debinding are thermally debinded and sintered in a MIM negative pressure sintering furnace at a temperature range of 1380-1395°C.

[0055] S5. Solution heat treatment: The sintered test specimens were heated to 920-1050°C in a vacuum quenching furnace at a heating rate of 15-20°C / min, kept at this temperature for 45-120 min, and then rapidly cooled to room temperature by high-pressure (6-10 atm) nitrogen quenching.

[0056] S6. Aging heat treatment hardening (control of material strength and plasticity): After solution heat treatment, the specimens are first cryogenically treated in liquid nitrogen at -193°C for 1-2 hours (this process is optional), and then aged at 460-500°C for 2-8 hours.

[0057] The following examples adopt this method to prepare maraging steel.

[0058] Example 1

[0059] An injection molding material, wherein the mass percentage content of each chemical element of the powder material is: Ni17.0, Co8.8, Mo5.6, C≤0.03, and the balance is Fe and a trace amount of inevitable impurity elements.

[0060] According to the process S1 to S4 described in the method for preparing maraging steel in the embodiment, feed material preparation, specimen injection, nitric acid degreasing, and then thermal degreasing and sintering at 1390° C. in a sintering furnace are carried out.

[0061] The sintered density of the sample is 7.85g / cm 3 The material's sintered oxygen content was 158 ppm and its carbon content was 98 ppm. The sintered specimens were held at 960°C for 2 hours in a vacuum quenching furnace, then rapidly cooled with nitrogen at 6 atmospheres, and then aged at 480°C for 4 hours. The resulting samples exhibited a yield strength of 1835 MPa, a tensile strength of 1901 MPa, and an elongation of 4.5%. Figure 1 The metallographic structure of this material is Figure 1 a is the metallographic structure of sintered material, Figure 1 b is the metallographic structure after aging treatment. Figure 1 It can be seen that after solution treatment, the grains of the material are fully refined compared with the sintered state.

[0062] Comparative Example 1

[0063] According to the composition of 18Ni300 (C300), alloy powder is made by gas atomization. Its composition is Ni18.5Co9.1Mo5.1Ti0.7Al0.06, as well as inevitable impurities. The oxygen content of the powder is 150ppm, and the particle size D90 of the powder is less than 22 microns.

[0064] The powder was fed according to the process steps S1 to S4 described in the Example for preparing maraging steel, degreased in an oxalic acid-nitrogen atmosphere, and sintered at 1390°C. To prevent excessive oxidation of the powder material, this degreasing process specifically used oxalic acid degreasing instead of nitric acid degreasing.

[0065] The sintered density of the sample is 7.43 g / cm 3 The sintered oxygen content was 2100 ppm. After the same heat treatment as Example 1, the material's tensile strength was 1276 MPa, the material fractured brittlely, and its elongation was zero. These test results indicate that materials containing highly oxidizing elements are difficult to achieve the properties expected under casting and forging conditions through metal injection molding.

[0066] Figure 2 These are the voids and metallographic structure of the material. A large number of voids are produced in the 18Ni300 material after sintering in a, and the metallographic structure of the 18Ni300 material after corrosion in b is abnormal.

[0067] Comparative Example 2

[0068] This comparative example examines a composition similar to 18Ni300 (C300), removing the elements titanium and aluminum in the formula of comparative example 1: preparing a Ni18.5Co9.1Mo5.2 alloy powder, sintering it into tensile specimens according to the steps of Example 1, and undergoing the same heat treatment process as Example 1.

[0069] The density of the obtained material is 7.85 g / cm 3 The sintered oxygen content of the material is 133ppm, the carbon content is 127ppm, and the yield strength of the material after solution aging treatment is 1561MPa, the tensile strength is 1770MPa, and the elongation is 5.1%. The yield strength of this material is relatively low.

[0070] Example 2

[0071] An injection molding material, wherein the mass percentage content of each chemical element of the powder material is: Ni16.5, Co8.5, Mo5.6, C≤0.03, and the balance is Fe and a trace amount of inevitable impurity elements.

[0072] According to the process S1 to S4 described in the method for preparing maraging steel in the embodiment, feed material preparation, specimen injection, nitric acid degreasing, and then thermal degreasing and sintering at 1390° C. in a sintering furnace are carried out.

[0073] The sintered density of the specimen is 7.83 g / cm 3 The sintered oxygen content of the material was 139 ppm and the carbon content was 108 ppm. The sintered specimens were held at 920°C for 3 hours in a vacuum quenching furnace, then rapidly cooled with nitrogen at 6 atmospheres, and then aged at 460°C for 8 hours. The resulting samples had a yield strength of 1811 MPa, a tensile strength of 1886 MPa, and an elongation of 3.5%.

[0074] Example 3

[0075] An injection molding material, wherein the mass percentage content of each chemical element of the powder material is: Ni16.5, Co8.5, Mo6.1, C≤0.03, and the balance is Fe and a trace amount of inevitable impurity elements.

[0076] According to the process S1 to S4 described in the method for preparing maraging steel in the embodiment, feed material preparation, specimen injection, nitric acid degreasing, and then thermal degreasing and sintering at 1390° C. in a sintering furnace are carried out.

[0077] The sintered density of the specimen is 7.85 g / cm 3The material's sintered oxygen content was 210 ppm and its carbon content was 90 ppm. The sintered specimens were held at 960°C for 2 hours in a vacuum quenching furnace, then rapidly cooled with nitrogen at 6 atmospheres, and then aged at 480°C for 4 hours. The resulting samples exhibited a yield strength of 1837 MPa, a tensile strength of 1907 MPa, and an elongation of 4.1%.

[0078] Example 4

[0079] An injection molding material, wherein the mass percentage content of each chemical element of the powder material is: Ni17.0, Co9.0, Mo6.1, C≤0.03, and the balance is Fe and a trace amount of inevitable impurity elements.

[0080] According to the process S1 to S4 described in the preparation method of maraging steel in the embodiment, feed material preparation, specimen injection, nitric acid degreasing, and then thermal degreasing and sintering at 1395° C. in a sintering furnace are carried out.

[0081] The sintered density of the specimen is 7.86 g / cm 3 The sintered oxygen content of the material was 147ppm and the carbon content was 109ppm. The sintered specimens were held at 1000°C for 1.5 hours in a vacuum quenching furnace, then rapidly cooled with nitrogen at 6 atmospheres. The specimens were then deep-cooled in liquid nitrogen at -193°C and then aged at 480°C for 5 hours. The resulting samples exhibited a yield strength of 1850MPa, a tensile strength of 1928MPa, and an elongation of 4.3%.

[0082] Example 5

[0083] An injection molding material, wherein the mass percentage content of each chemical element of the powder material is: Ni17.6, Co10.2, Mo6.0, C≤0.03, and the balance is Fe and a trace amount of inevitable impurity elements.

[0084] According to the process S1 to S4 described in the preparation method of maraging steel in the embodiment, feed material preparation, specimen injection, nitric acid degreasing, and then thermal degreasing and sintering at 1380° C. in a sintering furnace are carried out.

[0085] The sintered density of the specimen is 7.85 g / cm 3 The sintered oxygen content of the material is 147ppm and the carbon content is 113ppm. The heat treatment of the material is divided into two processes:

[0086] Process 1: The sintered specimens were kept at 1000°C for 1.5 hours in a vacuum quenching furnace, then rapidly cooled with nitrogen at 6 atmospheres, and then aged at 490°C for 4 hours. The resulting sample had a yield strength of 1862 MPa, a tensile strength of 1933 MPa, and an elongation of 4.1%.

[0087] Process 2: The sintered specimens are kept at 1000℃ in a vacuum quenching furnace for 1.5 hours, then quickly cooled with nitrogen at 6 atmospheres, and then deep-cooled in liquid nitrogen at -193℃, and then aged at 490℃ for 4 hours. The yield strength of the obtained sample is 1881MPa, the tensile strength is 1959MPa, and the elongation is 4.6%.

[0088] It can be seen that deep cryogenic treatment promotes the full transformation of martensite, improves the strength of the material and increases the elongation of the material.

[0089] Example 6

[0090] An injection molding material, wherein the mass percentage content of each chemical element of the powder material is: Ni18.5, Co13, Mo6.1, C≤0.03, and the balance is Fe and a trace amount of inevitable impurity elements.

[0091] According to the process S1 to S4 described in the preparation method of maraging steel in the embodiment, feed material preparation, specimen injection, nitric acid degreasing, and then thermal degreasing and sintering at 1395° C. in a sintering furnace are carried out.

[0092] The sintered density of the sample is 7.87g / cm 3 The material's sintered oxygen content is 147ppm and its carbon content is 87ppm. The sintered specimens were held at 1050°C for 1 hour in a vacuum quenching furnace, then rapidly cooled with nitrogen at 6 atmospheres. The specimens were then deep-cooled in liquid nitrogen at -193°C and then aged at 500°C for 1 hour. The resulting samples exhibited a yield strength of 1903MPa, a tensile strength of 1987MPa, and an elongation of 4.5%.

[0093] Example 7

[0094] An injection molding material, wherein the mass percentage content of each chemical element of the powder material is: Ni17.5, Co10.0, Mo6.5, C≤0.03, and the balance is Fe and a trace amount of inevitable impurity elements.

[0095] According to the process S1 to S4 described in the preparation method of maraging steel in the embodiment, feed material preparation, specimen injection, nitric acid degreasing, and then thermal degreasing and sintering at 1395° C. in a sintering furnace are carried out.

[0096] The sintered density of the sample is 7.87g / cm 3The material's sintered oxygen content is 147ppm and its carbon content is 133ppm. The sintered specimens were held at 1000°C for 1.5 hours in a vacuum quenching furnace, then rapidly cooled with nitrogen at 6 atmospheres. The specimens were then deep-cooled in liquid nitrogen at -193°C and then aged at 480°C for 5 hours. The resulting samples exhibited a yield strength of 1947MPa, a tensile strength of 2021MPa, and an elongation of 3.6%.

[0097] Example 8

[0098] An injection molding material, wherein the mass percentage content of each chemical element of the powder material is: Ni17.5, Co11.0, Mo6.5, C≤0.03, and the balance is Fe and a trace amount of inevitable impurity elements.

[0099] According to the process S1 to S4 described in the preparation method of maraging steel in the embodiment, feed material preparation, specimen injection, nitric acid degreasing, and then thermal degreasing and sintering at 1395° C. in a sintering furnace are carried out.

[0100] The sintered density of the sample is 7.88g / cm 3 The material's sintered oxygen content is 181ppm and its carbon content is 92ppm. The sintered specimens were held at 980°C for 2 hours in a vacuum quenching furnace, then rapidly cooled with nitrogen at 6 atmospheres. The specimens were then deep-cooled in liquid nitrogen at -193°C and then aged at 480°C for 5 hours. The resulting samples exhibited a yield strength of 1978MPa, a tensile strength of 2033MPa, and an elongation of 4.1%.

[0101] Example 9

[0102] An injection molding material, wherein the mass percentage content of each chemical element of the powder material is: Ni18.5, Co13.0, Mo7.0, C≤0.03, and the balance is Fe and a trace amount of inevitable impurity elements.

[0103] According to the process S1 to S4 described in the preparation method of maraging steel in the embodiment, feed material preparation, specimen injection, nitric acid degreasing, and then thermal degreasing and sintering at 1395° C. in a sintering furnace are carried out.

[0104] The sintered density of the sample is 7.92g / cm 3 The material's sintered oxygen content was 181 ppm and its carbon content was 105 ppm. The sintered specimens were held at 980°C for 2 hours in a vacuum quenching furnace, then rapidly cooled with nitrogen at 6 atmospheres. The specimens were then deep-cooled in liquid nitrogen at -193°C and then aged at 480°C for 5 hours. The resulting samples exhibited a yield strength of 2015 MPa, a tensile strength of 2058 MPa, and an elongation of 4.2%.

[0105] Example 10

[0106] An injection molding material, wherein the mass percentage content of each chemical element of the powder material is: Ni18.5, Co15.0, Mo7.0, C≤0.03, and the balance is Fe and a trace amount of inevitable impurity elements.

[0107] According to the process S1 to S4 described in the preparation method of maraging steel in the embodiment, feed material preparation, specimen injection, nitric acid degreasing, and then thermal degreasing and sintering at 1395° C. in a sintering furnace are carried out.

[0108] The sintered density of the sample is 7.93g / cm 3 The sintered oxygen content of the material was 119 ppm and the carbon content was 81 ppm. The sintered specimens were held at 980°C for 2 hours in a vacuum quenching furnace, then rapidly cooled with nitrogen at 6 atmospheres. The specimens were then deep-cooled in liquid nitrogen at -193°C and then aged at 480°C for 5 hours. The resulting samples exhibited a yield strength of 2035 MPa, a tensile strength of 2091 MPa, and an elongation of 4.0%.

[0109] Example 11

[0110] An injection molding material, wherein the mass percentage content of each chemical element of the powder material is: Ni17.5, Co15.0, Mo7.5, C≤0.03, and the balance is Fe and a trace amount of inevitable impurity elements.

[0111] According to the process S1 to S4 described in the preparation method of maraging steel in the embodiment, feed material preparation, specimen injection, nitric acid degreasing, and then thermal degreasing and sintering at 1395° C. in a sintering furnace are carried out.

[0112] The sintered density of the sample is 7.94g / cm 3 The sintered oxygen content of the material was 132 ppm and the carbon content was 109 ppm. The sintered specimens were held at 980°C for 2 hours in a vacuum quenching furnace, then rapidly cooled with nitrogen at 6 atmospheres. The specimens were then deep-cooled in liquid nitrogen at -193°C and then aged at 480°C for 5 hours. The resulting samples exhibited a yield strength of 2051 MPa, a tensile strength of 2133 MPa, and an elongation of 2.2%.

[0113] Example 12

[0114] An injection molding material, wherein the mass percentage content of each chemical element of the powder material is: Ni19, Co15.0, Mo7.5, C≤0.03, and the balance is Fe and a trace amount of inevitable impurity elements.

[0115] According to the process S1 to S4 described in the preparation method of maraging steel in the embodiment, feed material preparation, specimen injection, nitric acid degreasing, and then thermal degreasing and sintering at 1395° C. in a sintering furnace are carried out.

[0116] The sintered density of the sample is 7.94g / cm 3 The material's sintered oxygen content is 162ppm and its carbon content is 92ppm. The sintered specimens were held at 980°C for 2 hours in a vacuum quenching furnace, then rapidly cooled with nitrogen at 6 atmospheres. The specimens were then deep-cooled in liquid nitrogen at -193°C and then aged at 480°C for 5 hours. The resulting samples exhibited a yield strength of 2038MPa, a tensile strength of 2118MPa, and an elongation of 2.9%.

[0117] Example 13

[0118] An injection molding material, wherein the mass percentage content of each chemical element of the powder material is: Ni17.2, Co15.0, Mo8.0, C≤0.03, and the balance is Fe and a trace amount of inevitable impurity elements.

[0119] According to the process S1 to S4 described in the preparation method of maraging steel in the embodiment, feed material preparation, specimen injection, nitric acid degreasing, and then thermal degreasing and sintering at 1395° C. in a sintering furnace are carried out.

[0120] The sintered density of the sample is 7.96g / cm 3 The material's sintered oxygen content was 141 ppm and its carbon content was 101 ppm. The sintered specimens were held at 980°C for 2 hours in a vacuum quenching furnace, then rapidly cooled with nitrogen at 6 atmospheres. The specimens were then deep-cooled in liquid nitrogen at -193°C and then aged at 480°C for 5 hours. The resulting samples exhibited a yield strength of 2070 MPa, a tensile strength of 2127 MPa, and an elongation of 0.9%.

[0121] Example 14

[0122] An injection molding material, wherein the mass percentage content of each chemical element of the powder material is: Ni19, Co15.0, Mo8.0, C≤0.03, and the balance is Fe and a trace amount of inevitable impurity elements.

[0123] According to the process S1 to S4 described in the preparation method of maraging steel in the embodiment, feed material preparation, specimen injection, nitric acid degreasing, and then thermal degreasing and sintering at 1395° C. in a sintering furnace are carried out.

[0124] The sintered density of the sample is 7.95g / cm 3The material's sintered oxygen content is 157ppm and its carbon content is 117ppm. The sintered specimens were held at 980°C for 2 hours in a vacuum quenching furnace, then rapidly cooled with nitrogen at 6 atmospheres. The specimens were then deep-cooled in liquid nitrogen at -193°C and then aged at 500°C for 5 hours. The resulting samples exhibited a yield strength of 2059MPa, a tensile strength of 2094MPa, and an elongation of 1.2%.

[0125] The metal powder raw material formulas and properties of the above embodiments of the present invention are shown in Table 1.

[0126] Table 1 Metal powder raw material formula and properties of each example

[0127]

[0128] According to Table 1, in the design materials of the present invention:

[0129] (1) When the Mo content in the material is in the range of 5.6-6.1 wt%, the yield strength of the ultra-high strength steel is in the range of 1800-1900 MPa, and a relatively high elongation, such as greater than 4%, can be maintained;

[0130] (2) When the Mo content in the material is in the range of 6.1-6.5 wt%, the yield strength of the ultra-high strength steel is in the range of 1900-2000 MPa, and a relatively high elongation, such as greater than 4%, can be maintained;

[0131] (3) When the Mo content in the material is in the range of 6.5-7.5 wt%, the yield strength of the ultra-high strength steel is in the range of 2000-2050 MPa, and a relatively high elongation, such as greater than 2.2%, can be maintained;

[0132] (4) When the Mo content in the designed material reaches 8%, the yield strength of the material is further improved, but the elongation begins to decrease.

[0133] (5) The higher the content of molybdenum, cobalt, nickel and other elements in the material, the higher the material performance, but the higher the cost. You can choose a more economical material according to your actual needs.

[0134] In summary, the injection molding material described in this invention exhibits excellent plasticity. Within the compositional ranges described herein, ultra-high-strength steels with yield strengths exceeding 1800 MPa, 1900 MPa, and 2000 MPa can be produced. The resulting maraging steel is suitable for applications in aerospace, medical devices, and particularly in "3C" smart wearable devices, where both high strength and lightweight design are required.

[0135] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from the other embodiments. Reference can be made to the descriptions of the identical or similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and the relevant parts can be referred to the descriptions of the methods.

[0136] The above describes in detail the injection molding material, the resulting maraging steel with ultra-high yield strength, and its applications provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The above examples are intended only to facilitate understanding of the present invention's methods and core concepts. It should be noted that those skilled in the art will be able to make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications fall within the scope of protection of the claims.

Claims

1. An injection molding material, characterized in that The weight percentage content of each chemical element of the material is: Ni 17~19wt%, Co 13~15wt%, Mo 7.0~8.0wt%, C ≤0.03wt%, and the balance is Fe and inevitable impurity elements. The metal powder raw material of the material is prepared by feeding, injection, degreasing, and sintered at 1380~1395℃, and the sintered density of the material is greater than 7.8g / cm 3 The carbon content of the material after sintering is ≤0.02%.

2. The injection molding material according to claim 1, wherein: The mass percentage content of each chemical element in the material is: Ni 17 ~19wt%, Co 13~15wt%, Mo 7.0~7.5wt%, C≤0.03wt%, the balance is Fe, and inevitable impurity elements.

3. The injection molding material according to claim 2, wherein: The Ni content in this material is 17.5~19wt%.

4. The injection molding material according to claim 2, characterized in that The mass percentage content of each chemical element of the material is: Ni 18.5~18.7wt%, Co 13~15wt%, Mo 7.0~7.2wt%, C≤0.03wt%, and the balance is Fe and inevitable impurity elements.

5. An injection molding material, characterized in that The weight percentage content of each chemical element in the material is: Ni 17.5~19wt%, Co 10~15wt%, Co excluding 10%, Mo 6.5~7.0wt%, Mo excluding 6.5wt%, C ≤ 0.03wt%, and the balance is Fe and unavoidable impurity elements; the metal powder raw material of the material is prepared by feeding, injection, degreasing, and sintered at 1380~1395℃, and the sintered density of the material is greater than 7.8 g / cm 3 The carbon content of the material after sintering is ≤0.02%.

6. The injection molding material according to claim 5, wherein: The mass percentage content of each chemical element of the material is: Ni 17.5~18.7wt%, Co 11~15wt%, Mo 6.5~7.0wt%, C≤0.03wt%, and the balance is Fe and inevitable impurity elements.

7. The injection molding material according to claim 1 or 5, characterized in that: The carbon content of the material after sintering is ≤0.015%.

8. The injection molding material according to claim 1 or 5, characterized in that: The carbon content of the material after sintering is 0.0081%~0.0133%.

9. Maraging steel made from the injection molding material according to any one of claims 1 to 6.

10. The maraging steel according to claim 9, characterized in that: The metal powder raw material of the injection molding material is prepared by feeding, injection, degreasing, sintering at 1380-1395°C, solution heat treatment at 920-1050°C for 1-3 hours, and then aging heat treatment at a temperature range of 460-500°C for 1-8 hours to obtain maraging steel.

11. The maraging steel according to claim 9, characterized in that: The metal powder raw material of the injection molding material is prepared by feeding, injection, degreasing, sintering at 1380-1395°C, solution heat treatment at 920-1050°C for 1-3 hours, followed by cryogenic treatment, and then aging heat treatment at a temperature range of 460-500°C and a time of 1-8 hours to obtain maraging steel; The cryogenic treatment is performed in liquid nitrogen at -193°C±5°C for 1-2 hours.

12. Use of the maraging steel according to claim 9 in the manufacture of 3C products, aviation products, and medical products.

13. Use of the maraging steel according to claim 9 in the manufacture of smart wearable devices and components thereof.

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