Nitrogen-containing cobalt-based alloy Co40CrNiMo and preparation method and application thereof

Abstract

The invention relates to a nitrogen-containing cobalt-based alloy Co40CrNiMo and a preparation method and application thereof, and belongs to the technical field of metallurgy. The nitrogen-containing cobalt-based alloy Co40CrNiMo is prepared from the following chemical components in percentage by mass: 0.05%-0.5% of N, less than or equal to 0.15% of C, 1.5%-2.5% of Mn, less than or equal to 1.2% of Si, less than or equal to 0.015% of P, less than or equal to 0.015% of S, 39%-41% of Co, 19%-21% of Cr, 14%-16% of Ni, 6%-8% of Mo and the balance of Fe. The obtained nitrogen-containing Co40CrNiMo alloy is good in elasticity and high in strength, has plasticity and is particularly suitable for extreme environments such as precise instruments, aerospace and deep sea petroleum exploration.

Description

Technical Field

[0001] This invention relates to a nitrogen-containing cobalt-based alloy Co40CrNiMo, its preparation method, and its application, belonging to the field of metallurgical technology. Background Technology

[0002] Cobalt-based alloy Co40CrNiMo (Elgiloy, Phynox, DIN 2.4711, 3J21) is renowned for its excellent comprehensive properties and belongs to the category of elastic alloys. Compared to traditional iron-based, copper-based, and nickel-based elastic alloys, Co40CrNiMo alloy possesses superior strength, hardness, and fatigue resistance, making it widely used in the manufacture of precision instruments such as springs and telescopic rods. Furthermore, it exhibits excellent corrosion resistance, ergonomics, and non-magnetic properties, leading to its widespread application in the medical and petrochemical industries. The chemical composition of a traditional Co40CrNiMo alloy is as follows (by mass percentage): C≤0.15%, Mn: 1.5%-2.5%, Si≤1.2%, P≤0.015%, S≤0.015%, Cr: 19%-21%, Ni: 14%-16%, Co: 39%-41%, Mo: 6%-8%, with the remainder being Fe.

[0003] While existing Co40CrNiMo alloys perform well, their current performance is insufficient to meet high-end demands due to technological advancements and expanding applications. Co40CrNiMo alloys primarily improve strength through cold working, but this often leads to decreased ductility, with elongation sometimes falling below the minimum standard by 3%. This makes it difficult to meet the needs of future high-end elastic alloys that require both high strength and high toughness. Furthermore, although Co40CrNiMo alloys possess some corrosion resistance, they can still experience corrosion cracking in the highly corrosive extreme environments of the petrochemical industry, affecting equipment lifespan and safety stability. Simultaneously, with the development of cutting-edge fields such as deep-sea exploration and aerospace, related equipment places increasingly stringent demands on material performance at low temperatures. Currently, Co40CrNiMo alloys face problems such as embrittlement, abnormal thermal expansion, and performance instability at low temperatures, resulting in insufficient stability in cryogenic applications such as satellite telescopic booms, deep space probes, and deep-sea petrochemicals. Therefore, balancing and optimizing the trade-off between strength and ductility, as well as improving corrosion resistance and low-temperature performance, has become a crucial technical challenge for addressing the expansion of key equipment or components into more advanced applications. Summary of the Invention

[0004] To address the shortcomings and deficiencies in the physical properties of existing Co40CrNiMo alloys, and to meet the increasingly stringent performance requirements in high-end applications, this invention provides a nitrogen-containing cobalt-based alloy, Co40CrNiMo, its preparation method, and its applications. The nitrogen-containing Co40CrNiMo alloy obtained by this invention exhibits good elasticity, high strength, and good ductility, making it particularly suitable for extreme environments such as precision instruments, aerospace, and deep-sea oil exploration.

[0005] A nitrogen-containing cobalt-based alloy Co40CrNiMo, wherein the nitrogen-containing cobalt-based alloy Co40CrNiMo is composed of the following chemical composition by mass percentage: N: 0.05%~0.5%, C≤0.15%, Mn: 1.5%~2.5%, Si≤1.2%, P≤0.015%, S≤0.015%, Co: 39%~41%, Cr: 19%~21%, Ni: 14%~16%, Mo: 6%~8%, with the balance being Fe.

[0006] Furthermore, the nitrogen-containing cobalt-based alloy Co40CrNiMo has a solution-treated yield strength of 440~480 MPa, a tensile strength of 880~920 MPa, and an elongation of 60%~67%.

[0007] Another object of the present invention is to provide a method for preparing the above-mentioned nitrogen-containing cobalt-based alloy Co40CrNiMo, comprising the following steps: Step 1: Smelt the alloy according to its chemical composition. During the smelting process, nitriding is carried out in a pressure induction furnace using gas-phase or solid-phase nitriding methods. After smelting, the alloy is cast into steel ingots. The chemical composition of the steel ingots, by mass percentage, is as follows: C≤0.15%, Mn: 1.5%~2.5%, Si≤1.2%, P≤0.015%, S≤0.015%, Co: 39%~41%, Cr: 19%~21%, Ni: 14%~16%, Mo: 6%~8%, with the balance being Fe. Step 2: Heat the steel ingot to 1100~1250℃ in the furnace and hold it for 2~4 hours, then cool it in the furnace to obtain a homogeneous ingot; Step 3: After removing the head and tail of the homogeneous ingot, forge it at 1100~1200℃ for 2~3 hours, and finally forge it at 950~1050℃. Wrap it with asbestos and air cool it to room temperature to make a forging. Step 4: The forging is solution treated at 1100~1150℃ for 2~3 h. The solution-treated part obtained after water quenching is the nitrogen-containing cobalt-based alloy Co40CrNiMo.

[0008] In the above technical solution, the specific process of preparing steel ingots by gas-phase nitriding in step 1 using a pressure induction furnace is as follows: high-purity cobalt sheets, nickel blocks, metallic chromium, industrial pure iron, molybdenum rods, and other alloy materials are placed in an alloy crucible, and a vacuum is drawn to a vacuum degree ≤ 5 Pa. The vacuum is then stopped, and argon gas is introduced to a pressure of 0.02~0.05 MPa in the material hopper. Subsequently, water and electricity are supplied, and the temperature is raised to 1490~1510℃ until all the materials are completely melted. Then, a vacuum is drawn to a vacuum degree ≤ 20 Pa, and nitrogen gas at a pressure of 0.01~1 MPa is introduced using the gas-phase nitriding method to make the nitrogen content 0.05~0.5 wt%. The temperature of the molten steel is maintained at 1490~1510℃ and held for 1~2 h. The steel ingot is then poured to obtain the steel ingot.

[0009] Furthermore, maintaining the molten steel temperature at 1490~1510℃ and holding it at that temperature for 1~2 hours aims to nitrogen-enrich the alloy and ensure the combined deoxidation effect of Si and Mn.

[0010] In the above technical solution, the specific process of preparing steel ingots by solid-phase nitriding in step 1 using a pressure induction furnace is as follows: Nitrides, cobalt sheets, nickel blocks, metallic chromium, industrial pure iron, molybdenum rods, silicon, and manganese are placed in an alloy silo, and a vacuum is drawn until the vacuum degree is ≤5 Pa. The vacuum is then stopped and argon gas is introduced until the pressure in the silo is 0.02~0.05 MPa. Subsequently, water and electricity are supplied, and the temperature is raised to 1490~1510℃ until all the materials are melted. The holding time is 2 hours, and the steel ingot is then cast.

[0011] Furthermore, the nitride is a chromium-containing nitride, an iron-containing nitride, or an iron-chromium complex nitride.

[0012] More preferably, the nitride is chromium nitride, dichromium nitride, iron nitride, or ferrochrome nitride.

[0013] More preferably, the nitride is ferrochromium nitride, which, by mass fraction, consists of the following chemical composition: Fe 35%, Cr 60%, N 5.0%.

[0014] In the above technical solution, the purpose of homogenization treatment in step 2, which involves heating the furnace, is to make the chemical composition of the ingot more uniformly distributed, thereby improving the internal quality of the material.

[0015] In the above technical solution, in step 3, the forging ratio during the forging process is 2 to 5.

[0016] Another object of the present invention is to provide the application of the above-mentioned nitrogen-containing cobalt-based alloy Co40CrNiMo in the preparation of rolled products.

[0017] Furthermore, the rolled material is wire or strip.

[0018] Furthermore, the method for preparing the rolled material includes rolling the nitrogen-containing cobalt-based alloy Co40CrNiMo, with a rolling amount of 30% to 80%.

[0019] Furthermore, the hardness of the rolled material obtained after rolling is 400~530 HV, the yield strength is 1150~1750 MPa, the tensile strength is 1400~1950 MPa, and the elongation is 3%~15%.

[0020] Furthermore, the method for preparing the rolled material also includes aging the rolled part at a temperature of 450~550℃ for 2~6 h.

[0021] Furthermore, the rolled material has a hardness of 475~650 HV, a yield strength of 1350~2200 MPa, a tensile strength of 1650~2400 MPa, and an elongation of 3%~8%.

[0022] The rolling amount and aging treatment described in this invention can be determined according to the required strength, hardness, elongation and other indicators. When the rolling amount increases and aging treatment is performed, the yield strength, tensile strength and hardness will increase accordingly, while the elongation will decrease. By adjusting the nitrogen-containing cobalt-based alloy Co40CrNiMo obtained by this invention within the range described, a balance between strength, hardness and elongation can be achieved, meeting the dual requirements of "high strength + high toughness" in high-end scenarios.

[0023] The beneficial effects of this invention are: 1. Achieving a precise balance between strength and ductility, breaking through traditional performance bottlenecks: When traditional Co40CrNiMo alloys are strengthened by cold working to improve strength, ductility tends to decrease significantly, with elongation often falling below the minimum standard of 3%, making it difficult to meet the dual requirements of "high strength + high toughness" in high-end applications. Compared to traditional alloys, this invention, through precise control of nitrogen content (0.05~0.5 wt.%) and optimization of the preparation process, achieves nearly double the elongation without reducing or even increasing strength, thus realizing synergistic optimization of strength and ductility.

[0024] 2. Enhanced Mechanical Properties to Meet High-End Load-Bearing Requirements: This invention allows for flexible control of alloy properties through the combination of rolling amount and aging treatment, meeting the high-strength requirements of different scenarios. When the rolling amount is 50%, the hardness of the rolled material is stable at 450~500 HV, the yield strength is 1500~1550 MPa, and the tensile strength is 1600~1850 MPa. When the rolling amount is increased to 80%, the yield strength further increases to 1700~1750 MPa, the tensile strength reaches 1900~1950 MPa, and the elongation remains at 3%~5%, far exceeding the strength level of traditional alloys, thus meeting the high load-bearing requirements of high-end components such as precision instrument springs and aerospace telescopic rods.

[0025] 3. Stable and controllable preparation process, balancing mass production feasibility and performance consistency: This invention employs a combination of vacuum induction melting and vapor-phase nitriding (or solid nitride nitriding). By precisely controlling the melting temperature (1490~1510℃), vacuum level, nitriding pressure, and holding time, it ensures uniform nitrogen distribution and precise controllable nitrogen content. The process exhibits strong stability, is suitable for large-scale mass production, and can meet the batch supply needs of high-end industrial components. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the heat treatment process of homogenization-forging-solution annealing-aging in Embodiment 1 of the present invention. The aging process is a post-rolling process.

[0027] Figure 2 This is a comparison chart of the room temperature tensile stress-strain curves of the nitrogen-containing Co40CrNiMo alloy in Example 2 of the present invention and the nitrogen-free Co40CrNiMo alloy in Comparative Example 1, obtained under the condition of 50% rolling amount. Detailed Implementation

[0028] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way.

[0029] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are commercially available unless otherwise specified.

[0030] The yield strength and tensile strength described in the following embodiments were measured by cutting dog-bone shaped tensile specimens with a length of 45 mm, a width of 4 mm, and a thickness of 1 mm along the length of the solution-treated and rolled plates. Tensile mechanical properties were tested at room temperature using a Shimadzu AGS-X100kn electronic universal tensile testing machine at a tensile rate of 1 mm / min.

[0031] The elongation described in the following embodiments is obtained by the following method: After the tensile test, the two broken specimens are immediately removed and aligned along the fracture surface (ensuring that the axes of the two specimens coincide after fracture) to avoid misalignment or gaps. The distance between the two marked points after fracture is measured with vernier calipers to obtain the gauge length (L) after fracture. u The difference between the elongation and the original gauge length (L0) of the parallel segment is ΔL. The ratio of the elongation ΔL to L0 is the elongation rate.

[0032] Example 1 A method for preparing a nitrogen-containing cobalt-based alloy Co40CrNiMo strip includes the following steps: (1) Ingredients: Prepare 8 kg of cobalt sheets (Co), 4 kg of metallic chromium (Cr), 3 kg of nickel blocks (Ni), 1.4 kg of molybdenum rods (Mo), 0.4 kg of manganese (Mn), 0.24 kg of silicon (Si), 3 kg of industrial pure iron (Fe) and a bottle of nitrogen gas for the vacuum induction furnace. (2) Smelting: Place the above cobalt sheets, nickel blocks, metallic chromium, industrial pure iron, molybdenum rods, silicon, and manganese in the alloy silo, turn on the power, start the vacuum pump to evacuate the silo, and maintain the vacuum degree in the silo at 3 Pa before the material in the silo begins to melt; introduce argon gas until the pressure in the silo is 0.03 MPa, then turn on water and electricity to start the melting period; after all the material in the silo has melted, control the temperature in the silo to keep the material melting and maintain 1496℃; then evacuate the silo to a vacuum degree of 15 Pa, and use the gas phase nitriding method to fill the silo with nitrogen gas at a pressure of 0.08 MPa to make the nitrogen content 0.1 wt.%, keep it at the temperature for 2 h, and control the temperature of the molten steel in the silo at 1496℃ during the process, and finally cast the steel ingot. (3) Homogenization: The steel ingot is heated to 1150℃ in the furnace and held for 2 hours, then cooled in the furnace to obtain a homogeneous ingot; (4) Forging: After removing the head and tail of the homogeneous ingot, raise the temperature to 1180℃ and hold for 2 hours for forging. The final forging temperature is 960℃. Wrap it with asbestos and air cool it to room temperature to make forgings. The forging ratio is 3. (5) Solution treatment: The forging was kept at 1100℃ for 2 h for solution treatment, and then taken out after water quenching. The solution-treated part is the nitrogen-containing cobalt-based alloy Co40CrNiMo, with a solution-treated yield strength of 440 MPa, a tensile strength of 882 MPa, and an elongation of 66.5%. (6) Rolling: The solution-treated part is rolled with a rolling amount of 50% to obtain the finished strip. The yield strength of the obtained strip is 1480 MPa, the tensile strength is 1620 MPa, and the elongation is 5.8%. (7) Aging treatment: The rolled strip is kept at 450℃ for 5 h for aging treatment to obtain a high-strength strip with a yield strength of 1720 MPa, a tensile strength of 2000 MPa and an elongation of 3.8%.

[0033] Example 2 A method for preparing a nitrogen-containing cobalt-based alloy Co40CrNiMo strip includes the following steps: (1) Ingredients: Prepare 8 kg of cobalt sheets (Co), 4 kg of metallic chromium (Cr), 3 kg of nickel blocks (Ni), 1.4 kg of molybdenum rods (Mo), 0.4 kg of manganese (Mn), 0.24 kg of silicon (Si), 3 kg of industrial pure iron (Fe) and a bottle of nitrogen gas for the vacuum induction furnace. (2) Smelting: Place the cobalt sheets, nickel blocks, metallic chromium, industrial pure iron, molybdenum rods, silicon, and manganese in the alloy silo, turn on the power, start the vacuum pump to evacuate, and maintain the vacuum degree in the silo at 3 Pa before the material in the silo begins to melt; introduce argon gas until the pressure in the silo is 0.03 MPa, then turn on water and electricity to start the melting period; after all the material in the silo has melted, control the temperature in the silo to keep the material melting and maintain 1496℃; then evacuate to a vacuum degree of 15 Pa in the silo, and use the gas phase nitriding method to fill with nitrogen gas at a pressure of 0.2 MPa to make the nitrogen content 0.2 wt.%, keep warm for 2 h, and control the temperature of the molten steel in the silo at 1496℃ during the process, and finally cast to obtain steel ingots; (3) Homogenization: The steel ingot is heated to 1150℃ in the furnace and held for 2 hours, then cooled in the furnace to obtain a homogeneous ingot; (4) Forging: After removing the head and tail of the homogeneous ingot, raise the temperature to 1180℃ and hold for 2 hours for forging. The final forging temperature is 960℃. Wrap it with asbestos and air cool it to room temperature to make forgings. The forging ratio is 3. (5) Solution treatment: The forging was kept at 1100℃ for 2 h for solution treatment, and then taken out after water quenching. The solution-treated part is the nitrogen-containing cobalt-based alloy Co40CrNiMo, with a solution-treated yield strength of 456 MPa, a tensile strength of 922 MPa, and an elongation of 63.5%. (6) Rolling: The solution-treated part is rolled with a rolling amount of 50% to obtain the finished strip. The yield strength of the rolled strip is 1508 MPa, the tensile strength is 1624 MPa, and the elongation is 5.6%. (7) Aging treatment: The rolled strip is kept at 450℃ for 5 h for aging treatment to obtain a high-strength strip with a yield strength of 1750 MPa, a tensile strength of 2120 MPa and an elongation of 3.5%.

[0034] Example 3 A method for preparing a nitrogen-containing cobalt-based alloy Co40CrNiMo rolled product includes the following steps: (1) Ingredients: Prepare 1.6 kg of ferrochrome nitride (Fe 35%, Cr 60%, N 5.0% in ferrochrome nitride, with an absorption rate of 50%), 8 kg of cobalt sheet (Co), 3.04 kg of metallic chromium (Cr), 3 kg of nickel block (Ni), 1.4 kg of molybdenum rod (Mo), 0.4 kg of manganese (Mn), 0.24 kg of silicon (Si), and 2.3 kg of industrial pure iron (Fe); (2) Smelting: Place the above-mentioned ferrochrome nitride, cobalt sheets, nickel blocks, metallic chromium, industrial pure iron, molybdenum rods, silicon, and manganese in the alloy silo, turn on the power, start the vacuum pump to draw a vacuum, and maintain the vacuum degree in the silo at 3 Pa before the material in the silo begins to melt; introduce argon gas until the pressure in the silo is 0.03 MPa, then turn on water and electricity to start the melting period; after all the material in the silo has melted, control the temperature in the silo to keep the material melting and maintain it at 1510℃, and appropriately extend the heat preservation time by 2 h. During the process, control the temperature of the molten steel in the silo at 1510℃, and finally cast to obtain steel ingots; (3) Homogenization: The ingot is heated to 1150℃ and held for 2 hours. After cooling in the furnace, a homogeneous ingot is obtained. (4) Forging: After removing the head and tail of the homogeneous ingot, forging is carried out. The temperature is raised to 1180℃ and held for 2 hours for forging. The final forging temperature is 960℃. The ingot is wrapped with asbestos and air-cooled to room temperature to make forgings. The forging ratio is 3. (5) Solution treatment: The forging was kept at 1100℃ for 2 h for solution treatment, and then taken out after water quenching. The solution-treated part is the nitrogen-containing cobalt-based alloy Co40CrNiMo, with a solution-treated yield strength of 440 MPa, a tensile strength of 918 MPa, and an elongation of 61.5%. (6) Rolling: The solution-treated part is rolled with a rolling amount of 50% to obtain the finished strip. The yield strength of the rolled strip is 1495 MPa, the tensile strength is 1615 MPa, and the elongation is 5.3%. (7) Aging treatment: The rolled strip is kept at 450℃ for 5 h for aging treatment to obtain a high-strength strip with a yield strength of 1740 MPa, a tensile strength of 2110 MPa and an elongation of 3.3%.

[0035] Comparative Example 1 The difference between this comparative example and Example 2 is that it does not include the nitrogen gas introduction process. The specific steps are as follows: (1) Ingredients: Prepare 8 kg of cobalt sheets (Co), 4 kg of metallic chromium (Cr), 3 kg of nickel blocks (Ni), 1.4 kg of molybdenum rods (Mo), 0.4 kg of manganese (Mn), 0.2 kg of silicon (Si), and 3 kg of industrial pure iron (Fe); (2) Smelting: Cobalt sheets, nickel blocks, metallic chromium, industrial pure iron, molybdenum rods, silicon, and manganese are placed in the alloy silo. The power is turned on and the vacuum pump is started to draw a vacuum. Before the material in the silo begins to melt, the vacuum degree in the silo is maintained at 3 Pa. Argon gas is introduced until the pressure in the silo is 0.03 MPa. Then water and electricity are supplied to start the melting period. After all the material in the silo is melted, the temperature in the silo is controlled to keep the material melting and maintain 1496℃. The heat preservation time is appropriately extended by 2 h. During the process, the temperature of the molten steel in the silo is controlled at 1496℃. Finally, the steel ingot is obtained by casting. (3) Homogenization: The steel ingot is heated to 1150℃ in the furnace and held for 2 hours, then cooled in the furnace to obtain a homogeneous ingot; (4) Forging: After removing the head and tail of the homogeneous ingot, raise the temperature to 1180℃ and hold for 2 hours for forging. The final forging temperature is 960℃. Wrap it with asbestos and air cool it to room temperature to make forgings. The forging ratio is 3. (5) Solution treatment: The forging is held at 1100℃ for 2 h for solution treatment, and then taken out after water quenching. The solution-treated part is the nitrogen-containing cobalt-based alloy Co40CrNiMo, which has a yield strength of 370 MPa, a tensile strength of 864 MPa, and an elongation of 70.6%. (6) Rolling: The solution-treated part is rolled with a rolling amount of 50% to obtain the finished strip. The yield strength of the rolled strip is 1436 MPa, the tensile strength is 1628 MPa, and the elongation is 3.5%. (7) Aging treatment: The rolled strip is kept at 450℃ for 5 h for aging treatment to obtain a strip with a yield strength of 1720 MPa, a tensile strength of 2090 MPa and an elongation of 3.2%.

[0036] Figure 2 The chart compares the room temperature tensile stress-strain curves of the nitrogen-containing Co40CrNiMo alloy in Example 2 and the nitrogen-free Co40CrNiMo alloy in Comparative Example 1 under a 50% rolling weight condition. It can be seen that both exhibit typical stress-strain behavior of metallic materials, entering plastic deformation after the elastic stage, with the stress reaching a peak and then slowly decreasing before finally fracturing. However, the 0.2N Co40NiCrMo alloy exhibits superior yield strength and plasticity. The interstitial solid solution strengthening and precipitation strengthening effects of nitrogen addition increase the yield strength of the Co40NiCrMo alloy from 1436 MPa to 1508 MPa, and the peak stress increases by approximately 5%. Simultaneously, the fracture strain increases from 7.16% to 7.84%, an increase of approximately 0.7%, indicating that nitriding simultaneously improves both the strength and plasticity of the material.

Claims

1. A nitrogen-containing cobalt-based alloy Co40CrNiMo, characterized in that: The nitrogen-containing cobalt-based alloy Co40CrNiMo is composed of the following chemical composition by mass percentage: N: 0.05%~0.5%, C≤0.15%, Mn: 1.5%~2.5%, Si≤1.2%, P≤0.015%, S≤0.015%, Co: 39%~41%, Cr: 19%~21%, Ni: 14%~16%, Mo: 6%~8%, with the balance being Fe.

2. The nitrogen-containing cobalt-based alloy Co40CrNiMo according to claim 1, characterized in that: The nitrogen-containing cobalt-based alloy Co40CrNiMo has a solid solution yield strength of 440~480 MPa, a tensile strength of 880~920 MPa, and an elongation of 60%~67%.

3. The method for preparing the nitrogen-containing cobalt-based alloy Co40CrNiMo according to claim 1 or 2, characterized in that: Includes the following steps: Step 1: Smelt the alloy according to its chemical composition. During the smelting process, nitriding is carried out in a pressure induction furnace using gas-phase or solid-phase nitriding methods. After smelting, the alloy is cast into steel ingots. The chemical composition of the steel ingots, by mass percentage, is as follows: C≤0.15%, Mn: 1.5%~2.5%, Si≤1.2%, P≤0.015%, S≤0.015%, Co: 39%~41%, Cr: 19%~21%, Ni: 14%~16%, Mo: 6%~8%, with the balance being Fe. Step 2: Heat the steel ingot to 1100~1250℃ in the furnace and hold it for 2~4 hours, then cool it in the furnace to obtain a homogeneous ingot; Step 3: After removing the head and tail of the homogeneous ingot, forge it at 1100~1200℃ for 2~3 hours, and finally forge it at 950~1050℃. Wrap it with asbestos and air cool it to room temperature to make a forging. Step 4: The forging is solution treated at 1100~1150℃ for 2~3 h. The solution-treated part obtained after water quenching is the nitrogen-containing cobalt-based alloy Co40CrNiMo.

4. The preparation method according to claim 3, characterized in that: In step 1, the specific process of preparing steel ingots by gas-phase nitriding in a pressure induction furnace is as follows: high-purity cobalt sheets, nickel blocks, metallic chromium, industrial pure iron, molybdenum rods, silicon, and manganese are placed in an alloy crucible, and a vacuum is drawn to a vacuum degree ≤5 Pa. The vacuum is then stopped, and argon gas is introduced into the silo to a pressure of 0.02~0.05 MPa. Subsequently, water and electricity are supplied, and the temperature is raised to 1490~1510℃ until all the materials are melted. Then, a vacuum is drawn to a vacuum degree ≤20 Pa, and nitrogen gas at a pressure of 0.01~1 MPa is introduced by gas-phase nitriding to make the nitrogen content 0.05~0.5 wt%. The temperature of the molten steel is maintained at 1490~1510℃ and held for 1~2 h. The steel ingot is then poured to obtain the steel ingot.

5. The preparation method according to claim 3, characterized in that: In step 1, the specific process of preparing steel ingots by solid-phase nitriding in a pressure induction furnace is as follows: Nitrides, cobalt sheets, nickel blocks, metallic chromium, industrial pure iron, molybdenum rods, silicon, and manganese are placed in an alloy silo, and a vacuum is drawn until the vacuum degree is ≤5 Pa. The vacuum is then stopped and argon gas is introduced until the pressure in the silo is 0.02~0.05 MPa. Subsequently, water and electricity are supplied, and the temperature is raised to 1490~1510℃ until all the materials are completely melted. The holding time is 2 hours, and the steel ingot is then cast.

6. The preparation method according to claim 3, characterized in that: In step 3, the forging ratio during the forging process is 2 to 5.

7. The application of the nitrogen-containing cobalt-based alloy Co40CrNiMo according to any one of claims 1 to 6 in the preparation of rolled products, characterized in that: The rolled material is either wire or strip.

8. The application according to claim 7, characterized in that: The method for preparing the rolled material includes rolling the nitrogen-containing cobalt-based alloy Co40CrNiMo according to any one of claims 1 to 6, wherein the rolling amount is 30% to 80%.

9. The application according to claim 8, characterized in that: The method for preparing the rolled material further includes aging the rolled solution-treated part, wherein the aging treatment temperature is 450~550℃ and the time is 2~6 h.

10. The application according to claim 9, characterized in that: The rolled material has a hardness of 475~650 HV, a yield strength of 1350~2200 MPa, a tensile strength of 1650~2400 MPa, and an elongation of 3%~8%.

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