High-strength high-hardness nickel-based corrosion-resistant alloy and preparation method thereof

Abstract

The alloy comprises the following components in percentage by weight: 32.0 to 43.0 percent of Cr, 2.5 to 3.5 percent of Al, 1.0 to 5.0 percent of Fe, 1.0 to 3.0 percent of Mo, 0.5 to 3.0 percent of Nb, 0.1 to 1.5 percent of Co, 0.1 to 0.3 percent of Mn, 0.1 to 0.2 percent of V, 0.01 to 0.1 percent of lanthanide rare earth, 0.02 to 0.1 percent of Zr, 0.01 to 0.015 percent of C, less than or equal to 0.2 percent of Si, less than or equal to 0.05 percent of Ti, less than or equal to 0.03 percent of Mg, less than or equal to 0.001 percent of S and the balance of Ni element. On the premise of ensuring corrosion resistance, oxidation resistance, high temperature resistance and manufacturability of the alloy, the strength and hardness of the material are further improved, and the alloy can be used as a corrosion-resistant alloy, a high-temperature-resistant corrosion-resistant alloy, a wear-resistant corrosion-resistant alloy and the like, and is applied to complex working conditions in which high temperature, corrosion, wear or scouring and the like exist at the same time in a high-stress state.

Description

Technical Field

[0001] This invention relates to a metallic material, and more particularly to a high-strength, high-hardness nickel-based corrosion-resistant alloy and its preparation method. Background Technology

[0002] Nickel-based alloys maintain excellent mechanical properties and long service life even under extreme environments such as high temperature, high pressure, and high corrosion, and are widely used in aerospace, oil and gas drilling, chemical, and energy fields. After years of development, researchers have developed a series of nickel-based alloys for different application scenarios, but research results on high-strength, high-hardness, corrosion-resistant nickel-based alloys are relatively limited.

[0003] Nickel-based alloys cannot achieve high hardness and strength through quenching heat treatment like steel. They are generally strengthened through solution treatment followed by aging, but their strength and hardness are usually relatively low. Although solution treatment followed by cold working and aging can further improve the strength and hardness of nickel-based alloys, it is difficult to perform cold working on workpieces with a diameter or wall thickness of 100 mm or more. This method is generally only suitable for plates, small-diameter bars, and wires, and the improvement in strength and hardness is limited. In recent years, researchers have developed medium-entropy and high-entropy nickel-based alloys, achieving higher strength and hardness. However, these alloys are difficult to manufacture, costly, and produce small-sized products, making mass production and application difficult.

[0004] This invention discloses a high-strength, high-hardness nickel-based corrosion-resistant alloy composition and preparation method. The alloy is a wrought alloy obtained by vacuum induction melting and electroslag remelting. While ensuring the material's corrosion resistance, oxidation resistance, high-temperature resistance, and processability, the alloy further improves the material's strength and hardness through composite strengthening methods such as solid solution strengthening, grain refinement strengthening, and dispersion strengthening. This meets the high requirements of key components in important fields such as aerospace, oil and gas drilling, chemical industry, and energy for materials with high corrosion resistance, wear resistance, erosion resistance, and high-temperature resistance. Summary of the Invention

[0005] The purpose of this invention is to provide a high-strength, high-hardness nickel-based corrosion-resistant alloy and its preparation method. The alloy of this invention is smelted by vacuum induction melting + electroslag remelting, and formed by forging, hot rolling, cold rolling or cold drawing and other processes. After heat treatment, it has the advantages of corrosion resistance, wear resistance, erosion resistance and high temperature resistance. The manufacturing cost is comparable to that of traditional nickel-based alloys. It can be used as a corrosion-resistant alloy, a high-temperature corrosion-resistant alloy, a wear-resistant and corrosion-resistant alloy, etc. It can be applied under high stress conditions in complex working conditions where high temperature, corrosion, wear or erosion coexist.

[0006] The technical solution of this invention is: The high-strength, high-hardness nickel-based corrosion-resistant alloy has the following weight percentage composition: Cr: 32.0–43.0%, Al: 2.5–3.5%, Fe: 1.0–5.0%, Mo: 1.0–3.0%, Nb: 0.5–3.0%, Co: 0.1–1.5%, Mn: 0.1–0.3%, V: 0.1–0.2%, lanthanide rare earth elements: 0.01–0.1%; Zr: 0.02–0.1%, C: 0.01–0.015%, Si≤0.2%, Ti≤0.05%, Mg≤0.03%, S≤0.001%, with the balance being Ni.

[0007] The lanthanide rare earth elements are any one or more of Er, Ce, La, Yb, and Nd.

[0008] Preferred embodiment one, wherein the alloy comprises the following components by weight percentage: Cr: 38.0–42.0%, Al: 3.0–3.5%, Fe: 1.0–3.0%, Mo: 1.5–2.5%, Nb: 1.5–3.0%, Co: 0.5–1.5%, Mn: 0.1–0.3%, V: 0.1–0.2%, Er: 0.01–0.1%, Zr: 0.02–0.1%, C: 0.01–0.015%, Si≤0.2%, Ti≤0.05%, Mg≤0.03%, S≤0.001%, with the balance being Ni. This configuration achieves high strength and hardness.

[0009] In preferred embodiment two, the weight percentage of each component of the alloy is as follows: Cr: 32.0-35.0%, Al: 2.5-3.0%, Fe: 1.0-5.0%, Mo: 2.0-3.0%, Nb: 1.0-2.5%, Co: 0.1-1.0%, Mn: 0.1-0.3%, V: 0.1-0.2%, Ce: 0.01-0.1%, Zr: 0.02-0.1%, C: 0.01-0.015%, Si≤0.2%, Ti≤0.05%, Mg≤0.03%, S≤0.001%, with the balance being Ni, thus achieving higher strength, hardness, and toughness.

[0010] The preparation method of the above alloy includes the following steps: 1) Ingredients: Take each component according to the above alloy ratio.

[0011] 2) Vacuum induction melting: First add Ni, Cr, Fe, Mo, and Co. After they are completely melted, control the temperature of the molten steel at 1600-1650℃, maintain a vacuum of ≤5Pa for 20 minutes, and stir mechanically. Add C, Mn, and Al, maintain the temperature at 1550-1600℃ and vacuum degree ≤3Pa for 30 minutes, using a combination of mechanical and electromagnetic stirring. V, Zr, and rare earth elements are added sequentially, with a 5-minute interval between each addition. Stir for 10 minutes, reduce the molten steel temperature to 1470-1530℃, let stand for 15 minutes, and then pour. The rare earth element content is 0.05% to 0.5%.

[0012] 3) Electroslag remelting and diffusion annealing.

[0013] 4) After forging, the finished product is processed. The finished product processing method is one or more of forging, hot rolling, extrusion, cold rolling, and cold drawing. The forging / hot rolling deformation ratio is ≥3:1.

[0014] Cold rolling and cold drawing are applicable to products with a diameter or wall thickness not exceeding 50mm. 5) Heat treatment: Solution treatment + aging or aging.

[0015] The weight ratio of the slag material in the electroslag remelting is: CaF2:Al2O3:CaO:MgO=60~80:15~20:10~15:0~8; The diffusion annealing method is as follows: furnace heating + 1100℃×6h + 1140℃×12h + 1200℃×24~36h + air cooling; The heating temperature for forging / hot rolling is 1120-1170℃, and the final forging / rolling temperature is 850℃; The solution treatment method is as follows: heat to 950-1000℃, hold for 1-2 hours, heat to 1100-1200℃, hold for 1-4 hours, and then cool with water. The heating time is 20 to 40 minutes, preferably 30 minutes.

[0016] The aging method is as follows: heat to 740-850℃ and hold for 1-6 hours; then cool down in the furnace to 630-730℃ and hold for 3-10 hours, followed by air cooling. The furnace cooling time is 1 to 3 hours; preferably, it is 1 hour.

[0017] The main roles of various elements in the alloy described in this invention are as follows: Nickel: A matrix element. High nickel content ensures resistance to stress corrosion. It also works synergistically with elements such as niobium and aluminum to form fine γ′ and γ″ phases.

[0018] Chromium: When dissolved in the austenitic matrix, it causes lattice distortion and forms solid solution strengthening; in high-temperature environments, it forms a dense oxide film, improving oxidation resistance; in corrosive environments, it forms a dense passivation film, improving corrosion resistance and pitting resistance in strongly oxidizing acidic environments; a higher chromium content is designed to ensure the self-repairing ability of the passivation film; it combines with carbon to form carbides.

[0019] Molybdenum: When dissolved in the austenitic matrix, it causes lattice distortion and forms solid solution strengthening; it improves corrosion resistance, especially resistance to pitting corrosion, sulfuric acid, and phosphoric acid; it slows down the precipitation of harmful phases such as σ phase and μ phase during long-term high-temperature use; and it enhances the self-repair ability of the passivation film.

[0020] Cobalt: It is dissolved in the austenitic matrix, causing lattice distortion and forming solid solution strengthening; it improves the stability of the γ′ phase at high temperatures, so that it can still exist stably at high temperatures without coarsening or dissolving, thereby significantly improving the high-temperature creep resistance and heat resistance of the alloy; it slows down the precipitation of harmful phases such as σ phase and μ phase during long-term high-temperature use; and it improves hot working performance.

[0021] Iron: Reduces the tendency to carburize at high temperatures; optimizes the composition and structure of the passivation film of the alloy, thereby enhancing its corrosion resistance in specific environments such as reducing acids and hydrofluoric acid; improves hot deformation processing performance; and reduces alloy costs.

[0022] Manganese: deoxidizes; improves process performance.

[0023] Carbon: Deoxidation during vacuum smelting; forming highly stable carbides such as vanadium carbide, niobium carbide, and chromium carbide, which hinder grain growth at high temperatures, pin grain boundaries, and improve strength; however, if the carbon content is too high, the carbides will lead to chromium-depleted areas, reducing corrosion resistance, so the carbon content needs to be strictly controlled.

[0024] Aluminum: During aging, a diffusely distributed γ′ phase precipitates, improving the alloy's strength and hardness; deoxidation and denitrification improve the alloy's purity.

[0025] Niobium: During aging, it works synergistically with nickel and aluminum to precipitate a diffusely distributed γ″ phase, which improves strength and hardness; it also fixes carbon, which improves resistance to intergranular corrosion.

[0026] Vanadium: It fixes carbon, forming fine and dispersed vanadium nitride and vanadium carbide, which become nucleation sites in solidification, dynamic recrystallization, and other processes, improving segregation and refining the microstructure. When heated at high temperatures, the fine and dispersed vanadium nitride and vanadium carbide pin the grain boundaries, hindering grain growth. It also consumes carbon and nitrogen in the alloy, preventing the precipitation of harmful phases such as Ti (C, N) and improving corrosion resistance.

[0027] Zirconium: Purifies grain boundaries; improves mechanical properties; reduces low-melting-point phases and improves processing performance.

[0028] Lanthanide rare earth elements: They work synergistically with trace elements to remove harmful impurities, improve metallurgical quality, and enhance process performance; they work synergistically with vanadium and zirconium to refine microstructure and purify grain boundaries; they reduce low-melting-point phases and improve high-temperature resistance.

[0029] The alloy described in this invention, when heat-treated to the solution state, has relatively low strength and hardness, which is beneficial for machining. Its tensile strength is ≤1000MPa, yield strength is ≤500MPa, elongation is ≥30%, and hardness is ≤35HRC. After aging, the microstructure consists of matrix + γ′ phase + γ″ phase, exhibiting high strength, high hardness, and good corrosion resistance. It can be applied under high stress conditions in complex working conditions where high temperature, corrosion, wear, or erosion coexist. Its tensile strength is ≥1600MPa, yield strength is ≥1500MPa, and hardness is ≥55HRC.

[0030] The alloy obtained according to preferred embodiment one has the following mechanical properties in the solution-treated and aged state: tensile strength ≥ 2000 MPa, yield strength ≥ 1800 MPa, hardness ≥ 58 HRC, and hardness ≥ 54 HRC at 600℃; and in the directly aged state: hardness ≥ 62 HRC, and hardness ≥ 54 HRC at 600℃. The alloy obtained according to preferred embodiment two has the following mechanical properties in the solution-treated and aged state: tensile strength ≥ 1600 MPa, yield strength ≥ 1500 MPa, elongation ≥ 10%, and hardness ≥ 55 HRC; and in the directly aged state: tensile strength ≥ 1800 MPa, yield strength ≥ 1600 MPa, elongation ≥ 8%, and hardness ≥ 57 HRC.

[0031] The alloy described in this invention can be used as a corrosion-resistant alloy, a high-temperature corrosion-resistant alloy, and a wear-resistant corrosion-resistant alloy, and can be applied under high stress conditions in complex working conditions where high temperature, corrosion, wear, or erosion coexist.

[0032] The present invention will be further described below with reference to specific embodiments, but this does not limit the present invention to the scope of the embodiments described. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating the preparation process of the alloy described in this invention. Figure 2 This is a typical microstructure photograph of the alloy described in this invention. Detailed Implementation

[0034] For a process flow diagram of the alloy preparation method in this embodiment, please refer to [link / reference]. Figure 1 For typical microstructures of alloys prepared using the described method, see [link to relevant documentation]. Figure 2 . Example 1

[0035] The weight percentages of each component are as follows: Cr: 40.2%, Al: 3.4%, Fe: 1.0%, Mo: 1.8%, Nb: 2.5%, Co: 0.7%, Mn: 0.2%, V: 0.1%, Er: 0.1%, Zr: 0.03%, C: 0.01%, Si: 0.1%, Ti: 0.002%, Mg: 0.01%, S: 0.0005%, with the balance being Ni.

[0036] The main steps and parameters for alloy preparation are as follows.

[0037]

[0038] The mechanical properties of the obtained alloy bars were tested according to commonly used national standards: tensile strength 2170MPa, yield strength 2030MPa, hardness 60HRC, and hardness at 600℃ 55HRC. Example 2

[0039] The weight percentages of each component are as follows: Cr: 39.7%, Al: 3.2%, Fe: 1.1%, Mo: 2.1%, Nb: 1.3%, Co: 0.6%, Mn: 0.2%, V: 0.1%, Ce: 0.01%, Zr: 0.04%, C: 0.01%, Si: 0.1%, Ti: 0.003%, Mg: 0.01%, S: 0.0006%, with the balance being Ni.

[0040] The main steps and parameters for alloy preparation are as follows.

[0041]

[0042] The mechanical properties of the obtained alloy bars are as follows: tensile strength 2050MPa, yield strength 1910MPa, hardness 58.5HRC, and hardness at 600℃ 54HRC. Example 3

[0043] The weight percentages of each component are as follows: Cr: 32.6%, Al: 2.7%, Fe: 3.0%, Mo: 2.9%, Nb: 2.5%, Co: 0.5%, Mn: 0.2%, V: 0.1%, Ce: 0.02%, Zr: 0.05%, C: 0.015%, Si: 0.1%, Ti: 0.05%, Mg: 0.02%, S: 0.001%, with the balance being Ni.

[0044] The main steps and parameters for alloy preparation are as follows.

[0045]

[0046] The mechanical properties of the obtained alloy bars are: tensile strength 1650MPa, yield strength 1530MPa, elongation 12%, and hardness 56HRC. Example 4

[0047] The weight percentages of each component are as follows: Cr: 34.0%, Al: 2.8%, Fe: 2.5%, Mo: 2.8%, Nb: 2.5%, Co: 0.7%, Mn: 0.1%, V: 0.2%, Ce: 0.01%, Zr: 0.02%, C: 0.01%, Si: 0.1%, Ti: 0.05%, Mg: 0.02%, S: 0.0005%, with the balance being Ni.

[0048] The main steps and parameters for alloy preparation are as follows.

[0049]

[0050] The mechanical properties of the obtained alloy bars are: tensile strength 1730MPa, yield strength 1620MPa, elongation 10%, and hardness 57HRC. Example 5

[0051] The weight percentages of each component are as follows: Cr: 36.3%, Al: 2.8%, Fe: 1.5%, Mo: 2.8%, Nb: 2.5%, Co: 1.0%, Mn: 0.3%, V: 0.2%, Nd: 0.06%, Zr: 0.03%, C: 0.013%, Si: 0.1%, Ti: 0.05%, Mg: 0.02%, S: 0.0006%, with the balance being Ni.

[0052] The main steps and parameters for alloy preparation are as follows.

[0053]

[0054] Mechanical properties of the obtained alloy bars: tensile strength 2130MPa, yield strength 2020MPa, hardness 62HRC, hardness at 600℃ 56HRC.

[0055] This invention is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the principles of this invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all of these fall within the scope of protection claimed by this invention.

Claims

1. A high-strength, high-hardness nickel-based corrosion-resistant alloy, characterized in that, The weight percentage of each component is as follows: Cr: 32.0–43.0%, Al: 2.5–3.5%, Fe: 1.0–5.0%, Mo: 1.0–3.0%, Nb: 0.5–3.0%, Co: 0.1–1.5%, Mn: 0.1–0.3%, V: 0.1–0.2%, and lanthanide rare earth elements: 0.01–0.1%. Zr: 0.02~0.1%, C: 0.01~0.015%, Si≤0.2%, Ti≤0.05%, Mg≤0.03%, S≤0.001%, balance is Ni.

2. The alloy according to claim 1, characterized in that, The lanthanide rare earth elements are any one or more of Er, Ce, La, Yb, and Nd.

3. The alloy according to claim 1, characterized in that, The alloy comprises the following components by weight percentage: Cr: 38.0–42.0%, Al: 3.0–3.5%, Fe: 1.0–3.0%, Mo: 1.5–2.5%, Nb: 1.5–3.0%, Co: 0.5–1.5%, Mn: 0.1–0.3%, V: 0.1–0.2%, Er: 0.01–0.1%, Zr: 0.02–0.1%, C: 0.01–0.015%, Si≤0.2%, Ti≤0.05%, Mg≤0.03%, S≤0.001%, with the balance being Ni.

4. The alloy according to claim 1, characterized in that, The alloy comprises the following components by weight percentage: Cr: 32.0–35.0%, Al: 2.5–3.0%, Fe: 1.0–5.0%, Mo: 2.0–3.0%, Nb: 1.0–2.5%, Co: 0.1–1.0%, Mn: 0.1–0.3%, V: 0.1–0.2%, Ce: 0.01–0.1%, Zr: 0.02–0.1%, C: 0.01–0.015%, Si≤0.2%, Ti≤0.05%, Mg≤0.03%, S≤0.001%, with the balance being Ni.

5. The method for preparing the alloy according to any one of claims 1-4, characterized in that, Includes the following steps: 1) Ingredients: Take each component according to the alloy proportions described in any one of claims 1-4; 2) Vacuum induction melting: First add Ni, Cr, Fe, Mo, and Co. After they are completely melted, control the temperature of the molten steel at 1600-1650℃, maintain a vacuum of ≤5Pa for 20 minutes, and stir mechanically. Add C, Mn, and Al, maintain the temperature at 1550-1600℃ and vacuum degree ≤3Pa for 30 minutes, using a combination of mechanical and electromagnetic stirring. V, Zr, and rare earth elements are added sequentially, with a 5-minute interval between each addition. Stir for 10 minutes, reduce the molten steel temperature to 1470-1530℃, let stand for 15 minutes, and then pour. The rare earth element content is 0.05% to 0.5%. 3) Electroslag remelting and diffusion annealing; 4) After forging, the finished product is processed. The finished product processing method is one or more of forging, hot rolling, extrusion, cold rolling, and cold drawing. The forging / hot rolling deformation ratio is ≥3:

1. 5) Heat treatment: Solution treatment + aging or aging.

6. The preparation method according to claim 5, characterized in that, The weight ratio of the slag material in the electroslag remelting is: CaF2:Al2O3:CaO:MgO = 60~80:15~20:10~15:0~8.

7. The preparation method according to claim 5, characterized in that, The diffusion annealing method is as follows: furnace heating + 1100℃×6h + 1140℃×12h + 1200℃×24~36h + air cooling.

8. The preparation method according to claim 5, characterized in that, The heating temperature for forging / hot rolling is 1120-1170℃, and the final forging / rolling temperature is 850℃.

9. The preparation method according to claim 5, characterized in that, The solution treatment method is as follows: heat to 950-1000℃, hold for 1-2 hours, heat to 1100-1200℃, hold for 1-4 hours, and then cool with water. The heating time is 20 to 40 minutes, preferably 30 minutes.

10. The preparation method according to claim 5, characterized in that, The aging method is as follows: heat to 740-850℃ and hold for 1-6 hours; then cool down to 630-730℃ in the furnace and hold for 3-10 hours, followed by air cooling; wherein the furnace cooling time is 1-3 hours; preferably, it is 1 hour.

Images