A high-strength high-nickel alloy and a method for producing the same

Abstract

The application belongs to the field of metal material processing and specifically relates to a high-strength high-nickel alloy and a preparation method thereof, the alloy comprising the following weight proportions of powder raw materials: C: 0.03-0.07%, Ti: 0.10-0.30%, Al: 0.10-0.30%, Nb: 0.10-0.30%, B: 0.003-0.008%, Zr: 0.01-0.03%, RE: 0.005-0.020%, Fe: 0.10-0.30%, Cu: 0.10-0.25%, Mn: 0.10-0.30%, Si: 0.05-0.10%, the balance being Ni and inevitable impurities; the total content of the impurities is ≤0.05%, and among them, S ≤0.01%, P ≤0.01%; the above raw materials are prepared through the processes of pretreatment, vacuum induction smelting, hot working, softening annealing, cold deformation, medium-temperature stabilization treatment and medium-low temperature aging treatment, and the problem of poor room temperature strength of N6 nickel alloy in the prior art can be effectively solved.

Description

Technical Field

[0001] This invention belongs to the field of metallic materials, specifically relating to a high-strength high-nickel alloy and its preparation method. Background Technology

[0002] N6 nickel alloy (GB / T 5235-2021), as a classic high-purity nickel-based material, possesses excellent resistance to neutral salt spray and weak acid and alkali corrosion, as well as good thermal and electrical conductivity, due to its nickel content ≥99.0%. It is widely used in chemical, marine engineering, electronic vacuum, and other fields. Its mainstream forms include annealed (M-state), hardened (Y-state), semi-hardened (Y2-state), and hot-worked (R-state). Among them, the annealed state accounts for more than 70% of the production and is the most basic and common form. The annealed state accounts for more than 85% of the production of plates and pipes.

[0003] However, all N6 nickel alloys in different forms have significant performance defects, with the core problem being the imbalance between strength and plasticity. Although the annealed state has the best plasticity, with an elongation of 34-40%, which is convenient for complex forming and welding, its room temperature tensile strength is only ≥380MPa and its yield strength is ≥140MPa, which is difficult to meet the requirements of high pressure bearing. The hardened state achieves tensile strength through heavy cold deformation, but this results in a sharp drop in elongation to 2-5%, making it impossible to perform secondary processing. The semi-hardened state balances some strength and plasticity, but its applicable product types are narrow, and it is only suitable for light processing scenarios. The hot-worked state is suitable for large-size parts, but it has the problems of lower plasticity than the annealed state and poor microstructure uniformity.

[0004] For the aforementioned annealed N6 nickel alloy, existing technologies mainly employ the following solutions: 1) Process modification: such as cold working strengthening, although it can improve strength, it comes at the cost of a sharp decrease in plasticity and a significant reduction in processing performance; 2) Formula optimization: alloying with single elements such as Cu and Cr will reduce the nickel content to below 97%, significantly deteriorating corrosion resistance, and the strengthening effect is limited, less than 15%. Both of the above solutions have limitations. Traditional processes are mostly "hot working and single annealing" or "solution and single-stage aging," which are not precisely matched with the microalloying formula, and cannot fully stimulate the strengthening potential, resulting in large fluctuations in product performance and insufficient stability.

[0005] With the technological upgrades in fields such as high-pressure equipment in the chemical industry, load-bearing structures in the nuclear industry, and auxiliary components in aerospace, there is a comprehensive demand for materials that possess "high nickel content, high strength, good plasticity, and stable corrosion resistance." Existing technologies can no longer fill this technological gap, thus limiting the localization process of high-end equipment. Therefore, developing a N6-like nickel alloy that, through formula optimization and process synergy, significantly improves strength without sacrificing plasticity and corrosion resistance while maintaining high nickel content has become a critical issue urgently needing to be addressed by the industry, possessing both strong technological urgency and practical application value. Summary of the Invention

[0006] The purpose of this invention is to address the problem of poor room temperature strength of N6 nickel alloys in existing technologies by providing a novel high-strength high-nickel alloy and its preparation method. This novel high-strength high-nickel alloy, through formulation design and process optimization, can effectively solve the aforementioned problems. To achieve the above objective, the technical solution adopted by this invention to solve its technical problems is as follows: This invention provides a high-strength, high-nickel alloy comprising the following parts by weight of powder raw materials: C: 0.03-0.07%, Ti: 0.10-0.30%, Al: 0.10-0.30%, Nb: 0.10-0.30%, B: 0.003-0.008%, Zr: 0.01-0.03%, RE: 0.005-0.020%, Fe: 0.10-0.30%, Cu: 0.10-0.25%, Mn: 0.10-0.30%, Si: 0.05-0.10%, with the balance being Ni and unavoidable impurities; the total impurity content is ≤0.05%, and wherein S≤0.01% and P≤0.01%.

[0007] Furthermore, the total weight percentage of Ti, Al, and Nb is 0.40-0.70%.

[0008] Furthermore, the weight ratio of Ti to Al is 0.8-1.2 / 1.0.

[0009] Furthermore, the total weight percentage of B, Zr, and RE is 0.028-0.048%.

[0010] Further, the RE is a mixture of Ce and La; and the weight ratio of Ce to La is 2.0-5.0 / 1.0.

[0011] Another object of the present invention is to provide a method for preparing the high-strength high-nickel alloy as described above, comprising the following steps: S1, Raw material pretreatment: Select the above raw materials with a purity ≥ 99.95%, perform plasma cleaning, and then perform pretreatment under a vacuum degree ≤ 1×10⁻⁶. -2 Dry for 2 hours at 120°C and 180°C. S2, Vacuum Induction Melting: Add the raw materials to the vacuum induction furnace according to the formula, and evacuate to a vacuum level of ≤5×10. -3 Pa, heat to 1550-1600℃, hold for 30-40 minutes; and supplement with dynamic electromagnetic stirring; after melting, cast at 1520-1580℃ to obtain an alloy ingot with a diameter of 180-220mm. S3, hot working: The alloy ingot obtained from S2 is heated to 950-1100℃, and the holding time is calculated as 1h / 100mm based on the ingot diameter. Then, multiple forging passes are performed, with the forging deformation controlled at 15-20% / pass and the total deformation ≥60%, to obtain the hot-worked product. S4, softening annealing: Place the heat-treated product obtained in S3 into an annealing furnace, heat it to 780-850℃ and hold it for 0.8-1.5h, then air cool it to room temperature; S5, cold deformation: The S4 annealed product is cold rolled or cold drawn at 50-150℃, with a total deformation of 30-50% and a deformation of 8-12% per pass to obtain cold-worked product. S6, medium-temperature stabilization treatment: heat the cold-worked product obtained from S5 to 450-500℃ and hold for 1-2 hours, then air-cool to room temperature; S7, Low-temperature aging treatment: The product stabilized by S6 is heated to 420-480℃ and kept at that temperature for 10-20 hours, then air-cooled to room temperature; finally, after straightening and inspection, it is packaged to obtain the finished product.

[0012] Furthermore, the initial forging temperature in S3 is 980-1050℃, and the final forging temperature is 900-980℃.

[0013] Another object of the present invention is to provide the application of the above-mentioned high-strength nickel alloy in chemical high-pressure equipment, corrosion-resistant heat exchange tube sheets, storage tank liners or high corrosion-resistant and high load-bearing structural components.

[0014] The present invention has the following beneficial effects: (1) This invention provides a high-strength high-nickel alloy. The alloy composition uses Ni as the matrix. By reasonably adding Ti, Al, and Nb and strictly controlling the total amount of Ti+Al+Nb and the Ti / Al ratio, a composite strengthening system of "carbide + ordered precipitate phase" is constructed. This effectively pins dislocation movement, thereby significantly improving the room temperature and medium temperature strength of the alloy. At the same time, the Ni content is still maintained at about 97.5-99.0%, taking into account both high strength and corrosion resistance.

[0015] (2) This invention adds low amounts of RE, B and Zr to a high-nickel matrix and designs the content and ratio range of the three in a coordinated manner; on the one hand, it effectively reduces stress concentration and grain boundary cracking tendency during cold working, and on the other hand, it inhibits further grain coarsening under medium-temperature service conditions, thus taking into account both good processability and service stability on the basis of high strength.

[0016] (3) The present invention also provides a preparation process that matches the composition of the above-mentioned high-strength high-nickel alloy. The present invention uses moderate cold deformation to construct a high-density dislocation structure, which provides nucleation sites for the dispersed precipitation of carbides and ordered precipitates; medium-temperature stabilization treatment, which allows fine carbides such as NbC / TiC to further precipitate and grow near dislocations and grain boundaries and reach a more stable size and distribution, while stabilizing some of the distorted structures introduced by cold working; medium-low temperature aging treatment, which promotes the uniform precipitation and refined distribution of Ni3(Al,Ti,Nb) ordered precipitates in the matrix, thereby obtaining excellent precipitation strengthening effect without causing obvious recrystallization and coarsening of strengthening phase.

[0017] Under the combined conditions of formulation and process, the high-strength high-nickel alloy of this invention can stably achieve a room temperature tensile strength of ≥520MPa and a yield strength of ≥260MPa. Moreover, the key mechanical properties are significantly better than those of traditional N6 nickel alloys, demonstrating the comprehensive advantage of achieving a significant strength improvement while maintaining high nickel content and good corrosion resistance. Detailed Implementation

[0018] The present invention will be described in detail below with reference to embodiments. However, it should be understood that the following embodiments are merely illustrative examples of implementation of the present invention and are not intended to limit the scope of the present invention.

[0019] The purpose of this invention is to develop a high-strength, high-nickel alloy to address the problem of poor room-temperature strength in existing N6 nickel alloys. The approach is as follows: considering that the root cause of the existing problems lies in the lack of an effective strengthening phase and the tendency for grain boundary slippage in N6 nickel alloys, and that existing solutions do not form a synergistic strengthening system, this invention employs precise formulation design, using Ni as the matrix to construct a Ti-Al-Nb-C composite strengthening system, forming nanoscale carbides and ordered precipitates to improve room-temperature strength. This is combined with a low-content RE-B-Zr grain boundary control system to refine grains and purify grain boundaries. The process utilizes a seven-stage synergistic process, including raw material pretreatment, vacuum melting, moderate cold deformation, and graded heat treatment, adapted to the formulation characteristics to ensure uniform precipitation of the strengthening phase. Furthermore, the synergistic effect of each component and process—Ti-Al-Nb-C ensuring high strength, RE-B-Zr synergistically guaranteeing plasticity and processability, and the formulation design and refined process—significantly improves mechanical strength while retaining the high corrosion resistance and elongation of N6 nickel alloys, meeting the needs of high-end applications and adapting to industrial production. Embodiments of this invention are as follows: This invention provides a high-strength, high-nickel alloy comprising the following parts by weight of powder raw materials: C: 0.03-0.07%, Ti: 0.10-0.30%, Al: 0.10-0.30%, Nb: 0.10-0.30%, B: 0.003-0.008%, Zr: 0.01-0.03%, RE: 0.005-0.020%, Fe: 0.10-0.30%, Cu: 0.10-0.25%, Mn: 0.10-0.30%, Si: 0.05-0.10%, with the balance being Ni and unavoidable impurities; the total impurity content is ≤0.05%, and wherein S≤0.01% and P≤0.01%.

[0020] The total weight percentage of Ti, Al, and Nb is 0.40-0.70%. Ti synergistically forms a Ni3(Al,Ti,Nb) type ordered precipitate phase with Al and Nb, forming TiC particles with C to aid in strengthening. Al synergistically constructs a strengthening system with Ti and Nb, assisting in the purification of trace oxygen in the melt and improving the purity of the microstructure. Nb preferentially forms nanoscale NbC (10-30nm) with C, resulting in significant dislocation pinning while avoiding aggregation and coarsening, thus balancing strengthening and plasticity. Al, Ti, Nb, and Ni together form a Ni3(Al,Ti,Nb) type ordered precipitate phase, which both pins dislocations through carbide particles and hinders dislocation movement through the ordered precipitate phase. Simultaneously, controlling Σ(Ti+Al+Nb) = 0.30-0.70% avoids excessive strengthening phase leading to plasticity deterioration, achieving a balance between strength and plasticity.

[0021] The weight ratio of Ti to Al is 0.8-1.2 / 1.0, which balances strengthening and improving tissue purity.

[0022] The total weight percentage of B, Zr, and RE is 0.028-0.048%. RE (Ce / La) preferentially purifies S and P impurities at grain boundaries, creating a clean grain boundary environment for the effects of B and Zr. B segregates at grain boundaries, reducing grain boundary energy and increasing grain boundary strength. Zr hinders grain boundary migration and suppresses grain coarsening. B, Zr, and RE work synergistically to simultaneously achieve the triple goals of "grain boundary purification - grain boundary strengthening - grain refinement".

[0023] The RE is a mixture of Ce and La; and the weight ratio of Ce to La is 2.0-5.0 / 1.0; it purifies harmful impurities such as S and P at grain boundaries; it helps to refine grains, improve the uniformity of the structure, and prevent grain boundary embrittlement.

[0024] In addition, other trace elements in this invention have the following functions: C: Forms nanoscale carbides (TiC, NbC) with Ti and Nb to achieve particle strengthening; promotes dispersed and ordered precipitates; and ensures sufficient carbide precipitation above 0.030% to meet strengthening requirements; below 0.070% avoids the formation of coarse NbC brittle phases and prevents a decrease in plasticity.

[0025] Fe: Improves room temperature strength; enhances hot working fluidity; reduces the risk of forging cracks.

[0026] Cu: Helps improve resistance to neutral salt spray and weak alkali corrosion; inhibits the tendency of intergranular corrosion.

[0027] Mn: assists in deoxidation, reduces NiO inclusions; improves cold workability, and reduces the risk of roller sticking.

[0028] Si: a deoxidizer used in smelting to remove oxygen from the melt; it also slightly enhances antioxidant properties.

[0029] This invention relates to a high-strength, high-nickel alloy with Ni as the matrix. By rationally incorporating Ti, Al, and Nb, and strictly controlling the total amount of Σ(Ti+Al+Nb) and the Ti / Al ratio, Ti and Nb preferentially form dispersed NbC and TiC carbide particles with C. Simultaneously, Al, Ti, Nb, and Ni jointly form an ordered Ni3(Al,Ti,Nb) precipitate phase, constructing a composite strengthening system of "carbide + ordered precipitate phase." This readily yields dispersed NbC / TiC particles with a particle size of approximately 10-30 nm, which, combined with the fine Ni3(Al,Ti,Nb) ordered precipitate phase, effectively pins dislocation movement, thereby significantly improving the alloy's room temperature and mid-temperature strength. Meanwhile, by controlling the total amount of alloying elements, the Ni content of the alloy of the present invention is kept at about 97.5-99.0%, which achieves strengthening without significantly destroying the intrinsic corrosion resistance of the Ni matrix. This allows the alloy to maintain excellent corrosion resistance in neutral salt spray and weak acid and alkali media, thus balancing high strength and corrosion resistance.

[0030] Meanwhile, this invention incorporates low amounts of RE, B, and Zr into a high-nickel matrix, and synergistically designs the content and ratio range of these three elements. RE preferentially forms stable inclusions with harmful impurities such as S and O, relatively reducing the enrichment level of S at grain boundaries and weakening the embrittlement effect of impurities such as P on grain boundaries. B tends to segregate at grain boundaries, reducing grain boundary energy and improving grain boundary bonding. Zr, through segregation at grain boundaries and in the intragranular second phase, acts as a pinning and hindering mechanism for grain boundary migration. Thus, on the one hand, it effectively reduces stress concentration and grain boundary cracking tendency during cold working, and on the other hand, it inhibits further grain coarsening under medium-temperature service conditions. While ensuring a significant increase in the tensile strength of the alloy, the room temperature elongation can be stably maintained at ≥25%, and the cold working cracking rate can be controlled at ≤5%, thereby achieving both high strength and good processability and service stability.

[0031] Another objective of this invention is to provide a method for preparing a high-strength, high-nickel alloy as described above, comprising the following steps: S1, Raw material pretreatment: Select the above raw materials with a purity ≥ 99.95%, perform plasma cleaning, and then perform pretreatment under a vacuum degree ≤ 1×10⁻⁶. -2 Dry for 2 hours at 120°C and 180°C. S2, Vacuum Induction Melting: Add the raw materials to the vacuum induction furnace according to the formula, and evacuate to a vacuum level of ≤5×10. -3 Pa, heated to 1550-1600℃ at a rate of 4-6℃ / min, held for 30-40min, and supplemented with dynamic electromagnetic stirring; after melting, cast at 1520-1580℃ to obtain an alloy ingot with a diameter of 180-220mm. S3, hot working: The alloy ingot obtained from S2 is heated to 950-1100℃, and the holding time is calculated as 1h / 100mm based on the ingot diameter. Then, multiple forging passes are performed, with the forging deformation controlled at 15-20% / pass and the total deformation ≥60%, to obtain the hot-worked product. S4, softening annealing: Place the heat-treated product obtained in S3 into an annealing furnace, heat it to 780-850℃ and hold it for 0.8-1.5h, then air cool it to room temperature; S5, cold deformation: The S4 annealed product is cold rolled or cold drawn at 50-150℃, with a total deformation of 30-50% and a deformation of 8-12% per pass to obtain cold-worked product. S6, medium-temperature stabilization treatment: heat the cold-worked product obtained from S5 to 450-500℃ and hold for 1-2 hours, then air-cool to room temperature; S7, Low-temperature aging treatment: The product stabilized by S6 is heated to 420-480℃ and kept at that temperature for 10-20 hours, then air-cooled to room temperature; finally, after straightening and inspection, it is packaged to obtain the finished product.

[0032] The initial forging temperature for hot working in S3 is 980-1050℃, and the final forging temperature is 900-980℃.

[0033] The preparation method of high-strength high-nickel alloy in this invention is as follows: In S3, multi-pass small-deformation forging avoids hot working cracking; the total deformation is ≥60%, refining the as-cast grains; matching ingot diameter and heat preservation ensure uniform heating; final forging temperature control prevents abnormal grain growth, facilitating the acquisition of a fine-grained equiaxed structure (grains ≤50μm). In S5, moderate deformation constructs a high dislocation structure (providing sites for strengthening phase precipitation), avoiding stress concentration and cracking caused by heavy deformation (>50%); pass control and lubrication measures improve processing plasticity, ensuring the surface quality and microstructure uniformity of cold-worked products. In S6-S7, the stabilization stage induces initial carbide precipitation and partially recovers dislocations, avoiding recrystallization during subsequent aging; the aging stage precisely controls the uniform precipitation of short-range ordered Ni3(Al,Ti,Nb) clusters, preventing coarsening of the strengthening phase; the two stages work together to ensure the strengthening phase is "fine, uniform, and stable," maximizing the strengthening effect. The aforementioned combined process of "multi-pass hot working, moderate cold deformation, and medium-temperature stabilization / medium-low temperature aging" enables a good match between microstructure evolution and alloy formulation characteristics.

[0034] Another objective of this invention is to provide the application of the above-mentioned high-strength nickel alloy in high-pressure chemical equipment, corrosion-resistant heat exchange tube sheets, storage tank liners, or high corrosion-resistant and high load-bearing structural components.

[0035] To further understand the present invention, the high-strength high-nickel alloy provided by the present invention will be described in detail below with reference to specific embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0036] Example 1 A high-strength, high-nickel alloy comprises the following powder raw materials in parts by weight: C: 0.05%, Ti: 0.20%, Al: 0.20%, Nb: 0.20%, B: 0.005%, Zr: 0.02%, RE: 0.012%, Fe: 0.20%, Cu: 0.18%, Mn: 0.22%, Si: 0.07%, with the balance being Ni and unavoidable impurities.

[0037] The total weight percentage of Ti, Al and Nb is 0.60%.

[0038] The weight ratio of Ti to Al is 1.0 / 1.0.

[0039] The total weight percentage of B, Zr, and RE is 0.037%.

[0040] The RE is a mixture of Ce and La; and the weight ratio of Ce to La is 4.0 / 1.0.

[0041] A method for preparing a high-strength, high-nickel alloy includes the following steps: S1, Raw material pretreatment: Select the above raw materials with a purity ≥ 99.95%, perform plasma cleaning, and then perform pretreatment under a vacuum degree ≤ 1×10⁻⁶. -2 Dry for 2 hours at 120°C and 180°C. S2, Vacuum Induction Melting: Add the raw materials to the vacuum induction furnace according to the formula, and evacuate to a vacuum level of ≤5×10. -3 Pa was heated to 1580℃ at a rate of 5℃ / min and held for 35min; with the aid of dynamic electromagnetic stirring; after melting, it was cast at 1560℃ to obtain an alloy ingot with a diameter of 200mm. S3, Hot working: The alloy ingot obtained from S2 is heated to 1020℃, and the holding time is calculated as 1h / 100mm based on the ingot diameter. Then, multiple forging passes are performed, with the forging deformation controlled at 18% / pass and the total deformation at 60%, to obtain the hot-worked product. S4, softening annealing: The heat-treated product obtained in S3 is placed in an annealing furnace, heated to 820℃ and held for 1.0h, and then air-cooled to room temperature; S5, cold deformation: The product after S4 annealing is cold drawn at 100℃ with a total deformation of 40% and the deformation of each pass is controlled at 10% to obtain a cold-worked product. S6, medium-temperature stabilization treatment: The cold-worked product obtained in S5 is heated to 480℃ and held for 1.5h, then air-cooled to room temperature; S7, Low-temperature aging treatment: The product stabilized by S6 is heated to 460℃ and kept at that temperature for 16 hours, then air-cooled to room temperature; finally, after straightening and inspection, it is packaged to obtain the finished product.

[0042] The initial forging temperature in S3 is 1020℃, and the final forging temperature is 950℃.

[0043] Example 2 A high-strength, high-nickel alloy comprises the following powder raw materials in parts by weight: C: 0.03%, Ti: 0.12%, Al: 0.12%, Nb: 0.16%, B: 0.003%, Zr: 0.015%, RE: 0.010%, Fe: 0.30%, Cu: 0.25%, Mn: 0.10%, Si: 0.10%, with the balance being Ni and unavoidable impurities.

[0044] The total weight percentage of Ti, Al and Nb is 0.40%.

[0045] The weight ratio of Ti to Al is 1.0 / 1.0.

[0046] The total weight percentage of B, Zr, and RE is 0.028%.

[0047] The RE is a mixture of Ce and La; and the weight ratio of Ce to La is 4.0 / 1.0.

[0048] A method for preparing a high-strength, high-nickel alloy includes the following steps: S1, Raw material pretreatment: Select the above raw materials with a purity ≥ 99.95%, perform plasma cleaning, and then perform pretreatment under a vacuum degree ≤ 1×10⁻⁶. -2 Dry for 2 hours at 120°C and 180°C. S2, Vacuum Induction Melting: Add the raw materials to the vacuum induction furnace according to the formula, and evacuate to a vacuum level of ≤5×10. -3 Pa was heated to 1550℃ at a rate of 4℃ / min and held for 40min; with the aid of dynamic electromagnetic stirring; after melting, it was cast at 1520℃ to obtain an alloy ingot with a diameter of 180mm. S3, hot working: The alloy ingot obtained from S2 is heated to 950℃, and the holding time is calculated as 1h / 100mm based on the ingot diameter. Then, multiple forging passes are performed, with the forging deformation controlled at 15% / pass and the total deformation at 60%, to obtain the hot-worked product. S4, softening annealing: The heat-treated product obtained in S3 is placed in an annealing furnace, heated to 780℃ and held for 1.5 hours, and then air-cooled to room temperature; S5, cold deformation: The product after S4 annealing is cold rolled at 50°C with a total deformation of 30% and the deformation of each pass is controlled at 8% to obtain the cold-worked product. S6, medium-temperature stabilization treatment: The cold-worked product obtained in S5 is heated to 450℃ and held for 2 hours, then air-cooled to room temperature; S7, Low-temperature aging treatment: The product stabilized by S6 is heated to 420℃ and kept at that temperature for 20 hours, then air-cooled to room temperature; finally, after straightening and inspection, it is packaged to obtain the finished product.

[0049] The initial forging temperature in S3 is 980℃, and the final forging temperature is 900℃.

[0050] Example 3 A high-strength, high-nickel alloy comprises the following powder raw materials in parts by weight: C: 0.07%, Ti: 0.23%, Al: 0.23%, Nb: 0.24%, B: 0.008%, Zr: 0.025%, RE: 0.015%, Fe: 0.10%, Cu: 0.10%, Mn: 0.30%, Si: 0.05%, with the balance being Ni and unavoidable impurities.

[0051] The total weight percentage of Ti, Al and Nb is 0.70%.

[0052] The weight ratio of Ti to Al is 1.0 / 1.0.

[0053] The total weight percentage of B, Zr, and RE is 0.048%.

[0054] The RE is a mixture of Ce and La; and the weight ratio of Ce to La is 4.0 / 1.0.

[0055] A method for preparing a high-strength, high-nickel alloy includes the following steps: S1, Raw material pretreatment: Select the above raw materials with a purity ≥ 99.95%, perform plasma cleaning, and then perform pretreatment under a vacuum degree ≤ 1×10⁻⁶. -2 Dry for 2 hours at 120°C and 180°C. S2, Vacuum Induction Melting: Add the raw materials to the vacuum induction furnace according to the formula, and evacuate to a vacuum level of ≤5×10. -3 Pa was heated to 1600℃ at a rate of 6℃ / min and held for 30min; dynamic electromagnetic stirring was also used; after melting, the alloy ingot was cast at 1580℃ to obtain an alloy ingot with a diameter of 220mm. S3, hot working: The alloy ingot obtained from S2 is heated to 1100℃, and the holding time is calculated as 1h / 100mm based on the ingot diameter. Then, multiple forging passes are performed, with the forging deformation controlled at 20% / pass and the total deformation at 70%, to obtain the hot-worked product. S4, softening annealing: The heat-treated product obtained in S3 is placed in an annealing furnace, heated to 850℃ and held for 0.8h, and then air-cooled to room temperature; S5, cold deformation: The product after S4 annealing is cold drawn at 150℃ with a total deformation of 50% and the deformation of each pass is controlled at 12% to obtain a cold-worked product. S6, medium-temperature stabilization treatment: The cold-worked product obtained in S5 is heated to 500℃ and held for 1 hour, then air-cooled to room temperature; S7, Low-temperature aging treatment: The product stabilized by S6 is heated to 480℃ and kept at that temperature for 10 hours, then air-cooled to room temperature; finally, after straightening and inspection, it is packaged to obtain the finished product.

[0056] The initial forging temperature of the hot working in S3 is 1050℃, and the final forging temperature is 980℃.

[0057] Example 4 Everything else is the same as in Example 1, except that: In a high-strength, high-nickel alloy formulation, the amount of Ti added is 0.18% and the amount of Ti added is 0.22%; that is, the weight ratio of Ti to Al is 0.8 / 1.0.

[0058] Example 5 Everything else is the same as in Example 1, except that: In a high-strength, high-nickel alloy formulation, the amount of Ti added is 0.22% and the amount of Ti added is 0.18%; that is, the weight ratio of Ti to Al is 1.2 / 1.0.

[0059] Example 6 Everything else is the same as in Example 1, except that: In a high-strength, high-nickel alloy formulation, the amount of Ti added is 0.10%, the amount of Nb added is 0.10%, and the amount of Nb added is 0.10%.

[0060] Example 7 Everything else is the same as in Example 1, except that: In a high-strength, high-nickel alloy formulation, the amount of Ti added is 0.30%, the amount of Nb added is 0.30%, and the amount of Nb added is 0.30%.

[0061] Example 8 Everything else is the same as in Example 1, except that: In a high-strength, high-nickel alloy formulation, the amount of B added is 0.003%, the amount of Zr added is 0.01%, and the amount of RE added is 0.005%.

[0062] Example 9 Everything else is the same as in Example 1, except that: In a high-strength, high-nickel alloy formulation, the amount of B added is 0.008%, the amount of Zr added is 0.03%, and the amount of RE added is 0.020%.

[0063] Example 10 Everything else is the same as in Example 1, except that: In a high-strength, high-nickel alloy formulation, the RE is a mixture of Ce and La; and the weight ratio of Ce to La is 2.0 / 1.0.

[0064] Example 11 Everything else is the same as in Example 1, except that: In a high-strength, high-nickel alloy formulation, the RE is a mixture of Ce and La; and the weight ratio of Ce to La is 5.0 / 1.0.

[0065] The following comparative examples are all compared with Example 1: Comparative Example 1 The rest is the same as in Example 1, except that in a high-strength, high-nickel alloy formulation, the amount of C added is 0; that is, no C is added.

[0066] Comparative Example 2 The rest is the same as in Example 1, except that in a high-strength, high-nickel alloy formulation, the amount of Ti added is 0; that is, no Ti is added.

[0067] Implement Comparative Example 3 The rest is the same as in Example 1, except that in a high-strength, high-nickel alloy formulation, the amount of Al added is 0; that is, no Al is added.

[0068] Comparative Example 4 The rest is the same as in Example 1, except that in a high-strength, high-nickel alloy formulation, the amount of Nb added is 0; that is, no Nb is added.

[0069] Comparative Example 5 The rest is the same as in Example 1, except that in a high-strength, high-nickel alloy formulation, the amount of B added is 0; that is, no B is added.

[0070] Comparative Example 6 The rest is the same as in Example 1, except that in a high-strength, high-nickel alloy formulation, the amount of Zr added is 0; that is, no Zr is added.

[0071] Comparative Example 7 The rest is the same as in Example 1, except that in a high-strength, high-nickel alloy formulation, the amount of RE added is 0; that is, no RE is added.

[0072] Implemented Comparative Example 8 The rest is the same as in Example 1, except that in a high-strength, high-nickel alloy formulation, RE is Ce.

[0073] Comparative Example 9 The rest is the same as in Example 1, except that in a high-strength, high-nickel alloy formulation, RE is La.

[0074] Implement Comparative Example 10 The rest is the same as in Example 1, except that: in the preparation method of a high-strength high-nickel alloy, the deformation amount per pass in step S3 is 30%.

[0075] Comparative Example 11 The rest is the same as in Example 1, except that: in a method for preparing a high-strength high-nickel alloy, the total deformation in step S5 is 60%.

[0076] Comparative Example 12 The rest is the same as in Example 1, except that in the preparation method of a high-strength high-nickel alloy, the medium-temperature stabilization treatment in step S6 is held at 550°C for 1.5 hours.

[0077] Comparative Example 13 The rest is the same as in Example 1, except that in the preparation method of a high-strength high-nickel alloy, the low-temperature aging treatment in step S7 is 500℃ for 16 hours.

[0078] Comparative Example 14 The N6 nickel alloy (annealed state) in GB / T 5235-2021 standard is adopted.

[0079] The physical properties of the high-strength high-nickel alloys prepared in the embodiments and comparative examples of the present invention were measured respectively, and the results are shown in Table 1.

[0080] Table 1 Physical test performance of each embodiment Example 1 572 288 29.2 0.002 Example 2 541 273 29.7 0.002 Example 3 579 292 28.1 0.003 Example 4 555 281 29.3 0.002 Example 5 576 290 28.4 0.003 Example 6 523 261 29.9 0.003 Example 7 582 293 27.0 0.003 Example 8 574 289 26.8 0.003 Example 9 565 282 30.7 0.002 Example 10 561 280 28.4 0.003 Example 11 570 286 28.9 0.002 Comparative Example 1 423 174 32.6 0.002 Comparative Example 2 470 211 31.5 0.002 Implement Comparative Example 3 487 217 24.2 0.004 Comparative Example 4 399 165 33.5 0.003 Comparative Example 5 520 249 23.6 0.004 Comparative Example 6 508 234 25.8 0.003 Comparative Example 7 524 258 22.1 0.006 Implemented Comparative Example 8 566 284 28.7 0.003 Comparative Example 9 557 272 28.0 0.004 Implement Comparative Example 10 525 266 24.3 0.003 Comparative Example 11 593 307 19.4 0.004 Comparative Example 12 521 260 32.1 0.002 Comparative Example 13 534 265 33.0 0.002 Comparative Example 14 388 143 40.3 0.002 As can be observed from Examples 1-11, the high-strength high-nickel alloy of the present invention has excellent mechanical properties (room temperature tensile strength > 520 MPa, 0.2% yield strength > 260 MPa, elongation > 26%) and corrosion resistance (neutral salt spray corrosion rate ≤ 0.003 mm / a).

[0081] As can be observed from Example 1 and Comparative Examples 1-9, Nb and C in the high-strength high-nickel alloy of the present invention have a significant effect on improving strength, while Ti and Al have a positive effect on strengthening and improving strength; RE, B, Al, Zr and other elements play an important role in improving plasticity; RE and B are of great significance in improving corrosion resistance; among them, composite RE has a better effect on performance.

[0082] As can be observed from Examples 1 and Comparative Examples 10-13, in the preparation process of the high-strength high-nickel alloy in this invention, the small deformation per pass can avoid severe local grain deformation during hot working, which would weaken the strengthening effect; heavy cold deformation greatly increases the dislocation density, which can easily lead to brittle fracture during stretching and deteriorate the plasticity; the high stabilization temperature will cause the nano-sized NbC and TiC particles to coarsen rapidly, which will greatly weaken the dislocation pinning effect and reduce the strengthening effect; the aging temperature exceeds the stabilization temperature of the Ni3(Al,Ti,Nb) precipitate phase, which will cause decomposition and coarsening, resulting in a weakening of the strengthening effect.

[0083] As can be observed from Example 1 and Comparative Example 14, the key performance indicators of the product of the present invention are consistently superior to those of N6 nickel alloy (annealed state) in GB / T5235-2021 standard, and the strength is significantly improved while maintaining a certain degree of plasticity.

[0084] In summary, the high-strength, high-nickel alloy of the present invention, through the synergistic effect of optimized formulation design and process preparation, exhibits excellent mechanical properties and resistance to neutral corrosion.

[0085] The testing method is as follows: (1) Tensile strength at room temperature, yield strength at 0.2%, and elongation: Tested in accordance with GB / T 228.1-2021.

[0086] (2) Neutral salt spray corrosion rate: GB / T 10125-2021 (5% NaCl solution, 480h); using the weight loss method and conversion formula: Corrosion rate (mm / a) = (8.76 × 10⁻⁶) 4 ×W) / (A×T×D); Where W: corrosion weight loss (g); A: sample area (dm²) 2 T: Time (h); D: Material density (g / cm³) 3 ).

[0087] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A high-strength, high-nickel alloy, characterized in that: The powder raw material comprises the following weight fractions: C: 0.03-0.07%, Ti: 0.10-0.30%, Al: 0.10-0.30%, Nb: 0.10-0.30%, B: 0.003-0.008%, Zr: 0.01-0.03%, RE: 0.005-0.020%, Fe: 0.10-0.30%, Cu: 0.10-0.25%, Mn: 0.10-0.30%, Si: 0.05-0.10%, with the balance being Ni and unavoidable impurities; the total impurity content is ≤0.05%, and wherein S≤0.01% and P≤0.01%; The total weight fraction of Ti, Al, and Nb is 0.40-0.70%. The weight ratio of Ti to Al is 0.8-1.2 / 1.0; and The total weight fraction of B, Zr, and RE is 0.028-0.048%; The method for preparing the high-strength, high-nickel alloy includes the following steps: S1, Raw material pretreatment: Select the above raw materials with a purity ≥ 99.95%, perform plasma cleaning, and then perform pretreatment under a vacuum degree ≤ 1×10⁻⁶. -2 Dry for 2 hours at 120°C and 180°C. S2, Vacuum Induction Melting: Add the raw materials to the vacuum induction furnace according to the formula, and evacuate to a vacuum level of ≤5×10. -3 Pa, heat to 1550-1600℃, hold for 30-40 minutes; and supplement with dynamic electromagnetic stirring; after melting, cast at 1520-1580℃ to obtain an alloy ingot with a diameter of 180-220mm. S3, hot working: The alloy ingot obtained from S2 is heated to 950-1100℃, and the holding time is calculated as 1h / 100mm based on the ingot diameter. Then, multiple forging passes are performed, with the forging deformation controlled at 15-20% / pass and the total deformation ≥60%, to obtain the hot-worked product. S4, softening annealing: Place the heat-treated product obtained in S3 into an annealing furnace, heat it to 780-850℃ and hold it for 0.8-1.5h, then air cool it to room temperature; S5, cold deformation: The S4 annealed product is cold rolled or cold drawn at 50-150℃, with a total deformation of 30-50% and a deformation of 8-12% per pass to obtain cold-worked product. S6, medium-temperature stabilization treatment: heat the cold-worked product obtained from S5 to 450-500℃ and hold for 1-2 hours, then air-cool to room temperature; S7, Low-temperature aging treatment: The product stabilized by S6 is heated to 420-480℃ and held for 10-20 hours, then air-cooled to room temperature; finally, after straightening and inspection, it is packaged to obtain the finished product; The initial forging temperature for hot working in S3 is 980-1050℃, and the final forging temperature is 900-980℃.

2. The high-strength, high-nickel alloy according to claim 1, characterized in that: The RE is a mixture of Ce and La; and the weight ratio of Ce to La is 2.0-5.0 / 1.

0.

3. The application of the high-strength, high-nickel alloy as described in claim 1 in high corrosion-resistant, high load-bearing structural components.