A nickel-based alloy for nuclear power and a method for manufacturing the same

Abstract

The application discloses a nickel-based alloy for nuclear power and a manufacturing method thereof, and chemical components of the nickel-based alloy are as follows: C: 0.020-0.050%, Si: ≤0.30%, Mn: ≤0.30%, Cr: 16.0-19.0%, Mo: 2.0-3.0%, Nb: 4.20-5.20%, Ti: 1.00-2.00%, Al: 0.50-0.80%, Fe: 15.0-18.0%, P: 0.005-0.010%, B: 0.0020-0.0040%, S: ≤0.002%, Mg: 0.0010-0.0030%, N: ≤0.010%, Cu: ≤0.20%, and the balance is Ni and other inevitable impurities, and the following conditions are simultaneously met: 1.5 ≤ Mg / S ≤ 3.0, 1.8 ≤ Ti / Al ≤ 2.5, and 6.3 < Al+Ti+Nb < 7.0. The ring prepared from the nickel-based alloy has better room-temperature and high-temperature mechanical properties and corrosion resistance, the room-temperature tensile strength is greater than or equal to 1250 MPa, the room-temperature yield strength is greater than or equal to 1050 MPa, the room-temperature elongation is greater than or equal to 15%, the 350 DEG C tensile strength is greater than or equal to 1100 MPa, the 350 DEG C yield strength is greater than or equal to 950 MPa, and the 350 DEG C elongation is greater than or equal to 20%.

Description

Technical Field

[0001] This invention belongs to the field of nickel-based alloy material manufacturing technology, and specifically relates to a nickel-based alloy for nuclear power and its manufacturing method. Background Technology

[0002] Nuclear reactors operate in extremely harsh environments, with internal components running under conditions of high temperature, high pressure, and radiation for extended periods. In particular, with the continuous improvement of future design parameters, higher requirements are being placed on the strength, plasticity, corrosion resistance, radiation resistance, and long-term stability of raw materials.

[0003] GH4145 alloy is an age-hardening nickel-based alloy, whose strengthening mechanism is mainly solid solution strengthening and γ′ phase age precipitation hardening strengthening. It possesses excellent comprehensive properties such as high-temperature strength, oxidation resistance, fatigue resistance, and relaxation resistance, and is widely used in reactor internals in nuclear power plants, in the form of rods, rings, and wires. GH4145 alloy rings play a crucial role as support components within nuclear power reactors. However, due to the relatively low content of high-temperature strengthening elements in GH4145 alloy, it is difficult to meet the requirements of future nuclear reactors. Therefore, it is necessary to develop a higher-performance nickel-based alloy ring for nuclear power applications.

[0004] Chinese patent CN102085556B discloses a rolling forming method for thin-walled ring parts of GH4033 high-temperature alloy, the steps of which include: billet preparation, loading, rolling, hot rolling, and solution treatment. The main chemical element content (weight percentage) of the nickel-based alloy GH4033 is: C: 0.03~0.08%, Cr: 19.0~22.0%, Al: 0.60~1.00%, Ti: 2.40~2.80%, Fe≤4.0%, B≤0.010%, Ce≤0.010%, Mn≤0.35%, Si≤0.65%, P≤0.015%, S≤0.007%, with the balance being Ni. This patent mainly focuses on the development of nickel-based high-temperature alloy GH4033, which has low levels of high-temperature strengthening elements and is relatively easy to produce. Summary of the Invention

[0005] The purpose of this invention is to provide a nickel-based alloy for nuclear power and its manufacturing method. The nickel-based alloy ring has superior room temperature and high temperature mechanical properties and corrosion resistance. Its room temperature tensile strength is ≥1250MPa, room temperature yield strength is ≥1050MPa, room temperature elongation is ≥15%, 350℃ tensile strength is ≥1100MPa, 350℃ yield strength is ≥950MPa, and 350℃ elongation is ≥20%. It can be used as a support component in a nuclear power reactor.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A nickel-based alloy for nuclear power applications has the following chemical composition by weight percentage: C: 0.020~0.050%, Si≤0.30%, Mn≤0.30%, Cr: 16.0~19.0%, Mo: 2.0~3.0%, Nb: 4.20~5.20%, Ti: 1.00~2.00%, Al: 0.50~0.80%, Fe: 15.0~18.0%, P: 0.005~0.010%, B: 0.0020~0.0040%, S≤0.002%, Mg: 0.0010~0.0030%, N≤0.010%, Cu≤0.20%, with the balance including Ni and other unavoidable impurities, and must simultaneously satisfy the following: 1.5≤Mg / S≤3.0 1.8≤Ti / Al≤2.5 6.3 < Al + Ti + Nb < 7.0.

[0007] Preferably, the balance is Ni and other unavoidable impurities.

[0008] The nickel-based alloy of the present invention has a room temperature tensile strength ≥1250MPa, a room temperature yield strength ≥1050MPa, a room temperature elongation ≥15%, a 350℃ tensile strength ≥1100MPa, a 350℃ yield strength ≥950MPa, and a 350℃ elongation ≥20%.

[0009] This invention also provides a nickel-based alloy ring for nuclear power plants, with the following chemical composition by weight percentage: C: 0.020~0.050%, Si≤0.30%, Mn≤0.30%, Cr: 16.0~19.0%, Mo: 2.0~3.0%, Nb: 4.20~5.20%, Ti: 1.00~2.00%, Al: 0.50~0.80%, Fe: 15.0~18.0%, P: 0.005~0.010%, B: 0.0020~0.0040%, S≤0.002%, Mg: 0.0010~0.0030%, N≤0.010%, Cu≤0.20%, with the balance including Ni and other unavoidable impurities, and must simultaneously satisfy the following: 1.5≤Mg / S≤3.0 1.8≤Ti / Al≤2.5 6.3 < Al + Ti + Nb < 7.0.

[0010] Preferably, the balance is Ni and other unavoidable impurities.

[0011] The nickel-based alloy ring of the present invention has a room temperature tensile strength ≥1250MPa, a room temperature yield strength ≥1050MPa, a room temperature elongation ≥15%, a 350℃ tensile strength ≥1100MPa, a 350℃ yield strength ≥950MPa, and a 350℃ elongation ≥20%.

[0012] In the chemical composition design of the nickel-based alloy and ring components for nuclear power plants described in this invention: Carbon is an essential element for the formation of carbides in high-temperature alloys. An appropriate amount of carbides is beneficial for improving strength and refining grains; when the carbon content is too high, it will lead to increased segregation of the microstructure and a decrease in toughness. Therefore, the carbon content is preferably between 0.020% and 0.050%.

[0013] Silicon plays a deoxidizing role in smelting, but it is a harmful element in some nickel-based superalloys. Excessive silicon content will promote the precipitation of harmful phases in nickel-based alloys and deteriorate processing and toughness. Therefore, silicon content should be controlled at ≤0.30%.

[0014] Manganese plays a role in stabilizing austenite, but it is a harmful element in some nickel-based superalloys. Excessive manganese content is detrimental to corrosion resistance and reduces the hot plasticity and oxidation resistance of nickel-based alloys; therefore, the manganese content should be controlled at ≤0.30%.

[0015] Chromium: An important element for improving corrosion resistance and oxidation resistance, it forms an austenitic matrix together with nickel and iron. Excessive chromium content increases the tendency for intermetallic compound precipitation and deteriorates hot working properties; therefore, the chromium content should be controlled between 16.0% and 19.0%.

[0016] Molybdenum: It can improve high-temperature strength and improve the corrosion resistance of alloys, especially when combined with chromium. Its pitting resistance equivalent is 3.3 times that of chromium. However, too high a concentration can easily exacerbate segregation and affect thermoplasticity. In addition, molybdenum is relatively expensive, so the molybdenum content is controlled at 2.0~3.0%.

[0017] Niobium: It is a high-temperature strengthening phase forming element that can effectively improve the high-temperature strength and high-temperature stability of alloys. Excessive niobium content can easily lead to segregation and deteriorate alloy properties; therefore, the niobium content is controlled between 4.20% and 5.20%.

[0018] Aluminum: It is a high-temperature strengthening phase forming element, which can effectively improve the high-temperature strength and high-temperature stability of the alloy. Excessive aluminum content increases the difficulty of hot working of the alloy, so the aluminum content is controlled between 0.5% and 0.8%.

[0019] Titanium: It is a high-temperature strengthening phase forming element, which can effectively improve the high-temperature strength and high-temperature stability of the alloy. Excessive titanium content will produce harmful phases, resulting in poor alloy plasticity. Therefore, the titanium content should be controlled between 1.00% and 2.00%.

[0020] Iron: Together with nickel and chromium, it forms an austenitic matrix. Appropriate amounts of iron can replace some of the nickel, significantly reducing alloy costs. Excessive iron content promotes the precipitation of harmful phases, leading to deterioration of alloy properties; therefore, the iron content should be controlled between 15.0% and 18.0%.

[0021] Phosphorus: Trace amounts of phosphorus can improve the high-temperature creep rupture properties and creep life of some nickel-based alloys. Excessive phosphorus content is detrimental to the irradiation properties of the alloy and can exacerbate segregation, thus worsening the hot workability of the alloy. Therefore, the phosphorus content should be controlled between 0.005-0.010%.

[0022] Boron: Trace amounts of boron in nickel-based superalloys can strengthen grain boundaries and improve the alloy's high-temperature creep resistance and creep life. Excessive boron content is detrimental to the alloy's irradiation properties and can also lead to excessive borides that worsen the alloy's hot workability. Therefore, the boron content should be controlled between 0.0020 and 0.0040%.

[0023] Sulfur: It is an impurity element in the alloy. For the sake of thermoplasticity and corrosion resistance, the lower the content of this element, the better. Therefore, the sulfur content is controlled at ≤0.0020%.

[0024] Magnesium: Trace amounts of magnesium can purify grain boundaries, improve grain boundary strength, and enhance the high-temperature thermoplasticity of the alloy. Excessive magnesium content will produce low-melting-point harmful phases, deteriorating the thermoplasticity of the alloy. Therefore, the magnesium content should be controlled between 0.0010-0.0030%.

[0025] Nitrogen: It is a strong austenite forming element, which can improve the corrosion resistance of the austenite phase. However, in precipitation hardening nickel-based alloys, nitrogen readily combines with Ti and Nb elements to form brittle nitride phases, which deteriorate the hot working and fatigue properties of the alloy. Therefore, the nitrogen content is controlled at ≤0.010%.

[0026] Copper: An element that improves corrosion resistance, but it is a harmful element in some nickel-based superalloys. Excessive copper content is detrimental to alloy strength and reduces hot workability; therefore, the copper content should be controlled at ≤0.20%.

[0027] Nickel: As a strong element for forming and expanding the austenite region, it can improve the stability of the austenite structure and is a matrix element of nickel-based alloys.

[0028] Al, Ti, and Nb are the main elements forming high-temperature strengthening phases. Different Al, Ti, and Nb contents have a significant impact on the amount and composition of high-temperature strengthening phases. This invention increases the Nb content and appropriately reduces the Al and Ti contents, so that the alloy of this invention adds a γ″ strengthening phase on the basis of the γ′ strengthening phase, achieving a composite strengthening effect. The contents of the three elements meet the following two conditions: 1.8≤Ti / Al≤2.5, 6.3<Al+Ti+Nb<7.0, ensuring a suitable amount and ratio of γ¢ and γ¢¢ phases, which greatly improves the room temperature and high temperature strength of the alloy of this invention.

[0029] Trace amounts of magnesium and boron can purify grain boundaries and ensure that 1.5 ≤ Mg / S ≤ 3.0, which helps reduce the adverse effects of sulfur, an impurity element, improves the grain boundary strength and thermoplasticity of the alloy, and enhances the alloy's creep resistance.

[0030] The manufacturing method of the nickel-based alloy ring for nuclear power plants according to the present invention includes: vacuum induction smelting → electroslag remelting → vacuum arc remelting → forging → punching and ring expansion → rolling → finished ring; wherein... According to the above-mentioned three-stage smelting process consisting of vacuum induction smelting, electroslag remelting and vacuum consumable remelting, consumable ingots are obtained. The forging process is as follows: the forging heating temperature is 1080~1150℃, the consumable ingot is forged into a 350~450mm thick billet by upsetting and drawing with 5~8 heats and upsetting on a high-speed forging machine, and the final forging temperature is ≥960℃. The punching and ring expanding process is as follows: the heating temperature for punching and ring expanding is 1050~1120℃, a Ф300~400mm punch is used to punch the blank, and then the ring is expanded on a high-speed forging mill for 3~6 forging passes. The deformation amount of each ring expansion pass is ≤40%. The ring is expanded to a ring blank with an outer diameter of Ф1400~1600mm, an inner diameter of Ф900~1100mm, and a height of 300~400mm. The final forging temperature is ≥940℃. The ring rolling process is as follows: the ring billet is heated to 1020~1100℃, the ring billet is rolled into a ring 2~3 times, the deformation of the final rolling is ≥30%, the ring is expanded to a ring blank with an outer diameter of Ф2100~2300mm, an inner diameter of Ф1900~2100mm, and a height of 250~350mm, and the final rolling temperature is ≥920℃; Finally, the ring blank was subjected to conventional solution aging treatment and machining to obtain the finished ring.

[0031] Preferably, the vacuum induction smelting process includes: preparing materials according to the chemical composition; controlling the vacuum degree during the melting process at ≤3.0 Pa; firstly, adding Ni, Mo, and Fe main materials during the melting period; refining after melting and clearing; adding Cr, Al, Ti, and Nb alloys in batches; melting and refining; controlling the refining temperature at 1450~1500℃; and refining for a total time of ≥45 min. Finally, taking a sample of the finished product for composition analysis; after the chemical composition of the molten steel meets the control target requirements, tapping the steel and casting the vacuum induction electrode; and controlling the casting temperature of the vacuum induction electrode at 1410~1470℃.

[0032] Preferably, the electroslag remelting process includes: finishing the vacuum induction electrode to remove surface oxide scale, using an argon-protected electroslag furnace for electroslag remelting, setting the electroslag melting rate to 2.5~4.5Kg / min, and air cooling after demolding the electroslag ingot.

[0033] Preferably, the vacuum consumable remelting process includes setting the consumable melting rate at 3.0~4.5Kg / min, air cooling after demolding the consumable ingot, and homogenizing the demolded consumable ingot at a homogenization temperature of 1130~1210℃ for a homogenization time of ≥48h.

[0034] In the manufacturing method described in this invention: The vacuum degree during the smelting process is controlled at ≤3.0Pa. First, Ni, Mo, Fe and other main materials are added during the melting period. After melting and clearing, they are refined. Cr, Al, Ti, Nb and other alloys are added in batches, melted and refined. The refining temperature is controlled at 1450~1500℃, and the total refining time is ≥45min. Finally, a sample of the finished product is taken for composition analysis. After the chemical composition of the molten steel meets the control target requirements, the steel is tapped and cast into vacuum induction electrodes. The casting temperature of the vacuum induction electrodes is controlled at 1410~1470℃.

[0035] In the electroslag remelting process, the vacuum induction electrode is finished to remove the surface oxide scale, and the electroslag remelting is carried out in an argon-protected electroslag furnace. The electroslag melting rate is set to 2.5-4.5 kg / min, and the electroslag ingot is air-cooled after demolding.

[0036] In the vacuum consumable remelting process, the surface of the electroslag ingot is ground to its original metallic color, and oxide scale and other contaminants are not allowed. The consumable melting rate is set at 3.0-4.5 kg / min. After the consumable ingot is demolded, it is air-cooled.

[0037] After demolding, the consumable ingots are homogenized at a temperature of 1130~1210℃ for a time of ≥48h.

[0038] In the forging process, the consumable ingot is ground to remove the surface oxide scale. The forging heating temperature is 1080~1150℃. The consumable ingot is then upset on a high-speed forging mill through 5~8 upsetting and upsetting processes. The multiple upsetting processes break down the as-cast structure and improve the hot plasticity of the alloy. The ingot is then forged into a 350~450mm thick billet, with a final forging temperature ≥960℃.

[0039] In the punching and ring expanding process, the heating temperature is 1050~1120℃. A Ф300~400mm punch is used to punch the blank, and then the ring is expanded on a high-speed forging mill for 3~6 forging passes. The deformation amount per forging pass is ≤40%, expanding the ring to a blank with an outer diameter of Ф1400~1600mm, an inner diameter of Ф900~1100mm, and a height of 300~400mm. The final forging temperature is ≥940℃. Because the content of the high-temperature strengthening elements Al+Ti+Nb in the alloy of this invention is significantly increased compared to the GH4145 alloy, the difficulty of ring expanding is greatly increased. By rationally matching the deformation amount per forging pass, the initial forging temperature, and the final forging temperature during the ring expanding process, cracking does not occur in the ring blank after expansion.

[0040] In the ring rolling process, the ring billet is heated to 1020~1100℃, and undergoes 2~3 heat rolling processes. The deformation amount in the final heat rolling is ≥30%, expanding the ring to a blank with an outer diameter of Ф2100~2300mm, an inner diameter of Ф1900~2100mm, and a height of 250~350mm. The final rolling temperature is ≥920℃. Because the alloy of this invention has a high content of high-temperature strengthening elements, the deformation resistance of the rolled ring is increased, and the thermoplastic range is narrow. By rationally controlling the deformation amount and deformation temperature range during the rolling process, the rolled ring achieves ideal mechanical properties. Finally, the ring blank is solution-treated, aged, and machined to obtain the finished ring.

[0041] Compared with the prior art, the advantages or beneficial effects of the present invention are as follows: Compared to the GH4145 alloy, this invention increases the Nb content, appropriately reduces the Al and Ti contents, and ensures that the contents of the three elements meet the following two conditions: 1.8≤Ti / Al≤2.5, 6.3<Al+Ti+Nb<7.0, so that appropriate amounts of the two strengthening phases γ′ and γ″ precipitate in the alloy, thereby further improving the room temperature and high temperature strength of the alloy.

[0042] This invention controls the Cr content to 16.0~19.0% and the Mo content to 2.0~3.0%, further improving the corrosion resistance of the alloy (corrosion resistance is compared using PREN=Cr%+3.3*Mo%+16*N%). Furthermore, by increasing the Fe content to 15.0~18.0%, the cost of the alloy is reduced.

[0043] The content of trace elements and impurity elements was optimized. By adding appropriate Mg content and exploring the relationship between the addition method and yield, the Mg content was controlled at 0.0010~0.0030% and 1.5≤Mg / S≤3.0 to improve the grain boundary strength and thermoplasticity of the alloy. In addition, the B content was controlled at 0.0020~0.0040% and the P element was controlled at 0.005~0.010% to improve the creep resistance and ensure good radiation resistance.

[0044] By employing a three-stage smelting process consisting of vacuum induction, electroslag remelting, and vacuum arc remelting, high-purity, low-segregation ingots are obtained. Then, by optimizing the hot working parameters for forging, punching, ring expansion, and rolling, a nickel-based alloy ring with superior room-temperature and high-temperature mechanical properties, corrosion resistance, and radiation resistance is finally manufactured.

[0045] The beneficial effects of this invention are: The nickel-based alloy rings prepared according to the chemical composition and production process provided by this invention have good room temperature and high temperature mechanical properties and corrosion resistance. Their room temperature tensile strength is ≥1250MPa, room temperature yield strength is ≥1050MPa, room temperature elongation is ≥15%, 350℃ tensile strength is ≥1100MPa, 350℃ yield strength is ≥950MPa, and 350℃ elongation is ≥20%. They can be used as support components in nuclear power reactors. Detailed Implementation

[0046] The technical solution of the present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are only used to describe the specific implementation of the present invention and are not intended to constitute any limitation on the scope of protection of the present invention.

[0047] Table 1 shows the chemical composition of the alloys in the embodiments and comparative examples of the present invention, with the balance including nickel. Table 2 shows the performance results and PREN values ​​of the alloys in the embodiments and comparative examples of the present invention.

[0048] The manufacturing method of this invention includes the following steps: 1. Vacuum induction smelting The raw materials used should be clean. The vacuum degree during the smelting process should be controlled at ≤3.0Pa. First, Ni, Mo, Fe and other main materials are added during the melting period. After melting and clearing, refining is carried out. Cr, Al, Ti, Nb and other alloys are added in batches, melted and refined. The refining temperature is controlled at 1450~1500℃, and the total refining time is ≥45min. Finally, a sample of the finished product is taken for composition analysis. After the chemical composition of the molten steel meets the control target requirements, the steel is tapped and cast into vacuum induction electrodes. The casting temperature of the vacuum induction electrodes is controlled at 1410~1470℃. 2. Electroslag remelting: The vacuum induction electrode is finished to remove the surface oxide scale, and then electroslag remelting is carried out in an argon-protected electroslag furnace. The electroslag melting rate is set to 2.5-4.5 kg / min. After the electroslag ingot is demolded, it is air-cooled. 3. Vacuum consumable remelting: The surface of the electroslag ingot is ground until it is the natural color of the metal. No oxide scale or other contaminants are allowed. The self-contained melting rate is set at 3.0-4.5 kg / min. After the self-contained ingot is demolded, it is air-cooled. After demolding, the consumable ingots are homogenized at a temperature of 1130~1210℃ for a time of ≥48h. 4. Forging and billet preparation The consumable ingot is ground to remove the surface oxide scale, and the forging heating temperature is 1080~1150℃. The consumable ingot is then upset and drawn on a high-speed forging mill through 5~8 upsetting and drawing processes, and the as-cast structure is broken up by multiple upsetting processes to improve the hot plasticity of the alloy. It is then forged into a 350~450mm thick billet, and the final forging temperature is ≥960℃. 5. Punching and expanding ring The punching and ring expanding heating temperature is 1050~1120℃. A Ф300~400mm punch is used to punch the blank. Then, the ring is expanded on a high-speed forging mill for 3~6 forging passes. The deformation of the ring is ≤40% per forging pass. The ring is expanded to a ring blank with an outer diameter of Ф1400~1600mm, an inner diameter of Ф900~1100mm, and a height of 300~400mm. The final forging temperature is ≥940℃. 6. Ring rolling The ring billet is heated to 1020~1100℃, and the ring billet is rolled into a ring in 2~3 heats. The deformation of the ring in the last heat rolling is ≥30%. The ring is expanded to a ring blank with an outer diameter of Ф2100~2300mm, an inner diameter of Ф1900~2100mm, and a height of 250~350mm. The final rolling temperature is ≥920℃. Finally, the ring blank was subjected to solution treatment at 980℃, aging treatment at 720℃ and 620℃ and machining to obtain the finished ring. The performance of the finished ring is shown in Table 3.

[0049] Comparative Example 1 Comparative Example 1 is a GH4145 nickel-based alloy, produced using the same process as the examples. Its formation composition, main process parameters, and various properties are shown in Tables 1-3.

[0050] As can be seen from the comparison of Tables 1 and 2, compared with the GH4145 nickel-based alloy of Comparative Example 1, the nickel-based alloy for nuclear power described in this invention, by increasing the Nb content, appropriately reducing the Al and Ti content, optimizing the content of trace elements and impurity elements, and using a reasonable manufacturing process, produces nickel-based alloy rings with better room temperature and high temperature mechanical properties and corrosion resistance, and can be used as support components in nuclear power reactors.

[0051] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the invention without departing from the scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

[0052]

[0053]

[0054]

Claims

1. A nickel-based alloy for nuclear power applications, comprising the following components by weight percentage: C: 0.020–0.050%, Si ≤ 0.30%, Mn ≤ 0.30%, Cr: 16.0–19.0%, Mo: 2.0–3.0%, Nb: 4.20–5.20%, Ti: 1.00–2.00%, Al: 0.50–0.80%, Fe: 15.0–18.0%, P: 0.005–0.010%, B: 0.0020–0.0040%, S ≤ 0.002%, Mg: 0.0010–0.0030%, N ≤ 0.010%, Cu ≤ 0.20%, with the balance including Ni and other unavoidable impurities, and simultaneously satisfying the following: 1.5 ≤ Mg / S ≤ 3.0 1.8≤Ti / Al≤2.5 6.3 < Al + Ti + Nb < 7.

0.

2. The nickel-based alloy for nuclear power plants as described in claim 1, characterized in that, The balance is Ni and other unavoidable impurities.

3. The nuclear power nickel-based alloy as described in claim 1 or 2, characterized in that, The nickel-based alloy has a room temperature tensile strength ≥1250MPa, a room temperature yield strength ≥1050MPa, a room temperature elongation ≥15%, a 350℃ tensile strength ≥1100MPa, a 350℃ yield strength ≥950MPa, and a 350℃ elongation ≥20%.

4. A nickel-based alloy ring for nuclear power plants, comprising the following composition by weight percentage: C: 0.020–0.050%, Si ≤ 0.30%, Mn ≤ 0.30%, Cr: 16.0–19.0%, Mo: 2.0–3.0%, Nb: 4.20–5.20%, Ti: 1.00–2.00%, Al: 0.50–0.80%, Fe: 15.0–18.0%, P: 0.005–0.010%, B: 0.0020–0.0040%, S ≤ 0.002%, Mg: 0.0010–0.0030%, N ≤ 0.010%, Cu ≤ 0.20%, with the balance including Ni and other unavoidable impurities, and simultaneously satisfying the following: 1.5≤Mg / S≤3.0 1.8≤Ti / Al≤2.5 6.3 < Al + Ti + Nb < 7.

0.

5. The nickel-based alloy ring for nuclear power plants as described in claim 4, characterized in that, The balance is Ni and other unavoidable impurities.

6. The nickel-based alloy ring for nuclear power plants as described in claim 4 or 5, characterized in that, The nickel-based alloy ring has a room temperature tensile strength ≥1250MPa, a room temperature yield strength ≥1050MPa, a room temperature elongation ≥15%, a 350℃ tensile strength ≥1100MPa, a 350℃ yield strength ≥950MPa, and a 350℃ elongation ≥20%.

7. The method for manufacturing a nickel-based alloy ring for nuclear power plants as described in any one of claims 4 to 6, characterized in that it comprises: Vacuum induction smelting → electroslag remelting → vacuum arc remelting → forging → punching and ring expansion → ring rolling → finished ring; among which... According to the composition of claim 4 or 5, a consumable ingot is obtained by a triple smelting process consisting of vacuum induction smelting, electroslag remelting and vacuum consumable remelting. The forging process is as follows: the forging heating temperature is 1080-1150℃, the consumable ingot is forged into a 350-450mm thick billet by upsetting and drawing with 5-8 heats and upsetting on a high-speed forging machine, and the final forging temperature is ≥960℃. The punching and ring expanding process is as follows: the heating temperature for punching and ring expanding is 1050-1120℃, a Ф300-400mm punch is used to punch the blank, and then the ring is expanded on a high-speed forging mill for 3-6 forging passes. The deformation amount of each ring expansion pass is ≤40%. The ring is expanded to a ring blank with an outer diameter of Ф1400-1600mm, an inner diameter of Ф900-1100mm, and a height of 300-400mm. The final forging temperature is ≥940℃. The ring rolling process is as follows: the ring billet is heated to 1020-1100℃, the ring billet is rolled 2-3 times, the deformation of the last rolling is ≥30%, and the ring is expanded to a ring blank with an outer diameter of Ф2100-2300mm, an inner diameter of Ф1900-2100mm, and a height of 250-350mm. The final rolling temperature is ≥920℃. Finally, the ring blank is subjected to solution aging treatment and machining to obtain the finished ring.

8. The method for manufacturing a nickel-based alloy ring for nuclear power plants as described in claim 7, characterized in that, The vacuum induction smelting process includes: preparing materials according to the chemical composition of claim 4 or 5; controlling the vacuum degree during the melting process at ≤3.0 Pa; firstly, adding Ni, Mo, and Fe main materials during the melting period; refining after melting and clearing; adding Cr, Al, Ti, and Nb alloys in batches; melting and refining; controlling the refining temperature at 1450–1500℃; and refining time ≥45 min. Finally, taking a sample of the finished product for composition analysis; after the chemical composition of the molten steel meets the control target requirements, tapping the steel and casting the vacuum induction electrode; controlling the casting temperature of the vacuum induction electrode at 1410–1470℃.

9. The method for manufacturing a nickel-based alloy ring for nuclear power plants as described in claim 7, characterized in that, The electroslag remelting process includes: finishing the vacuum induction electrode to remove the surface oxide scale, using an argon-protected electroslag furnace for electroslag remelting, setting the electroslag melting rate to 2.5-4.5 kg / min, and air cooling after demolding the electroslag ingot.

10. The method for manufacturing a nickel-based alloy ring for nuclear power plants as described in claim 7, characterized in that, The vacuum consumable remelting process includes setting the consumable melting rate to 3.0–4.5 kg / min, air cooling after demolding of the consumable ingot, and homogenizing treatment of the demolded consumable ingot at a homogenization temperature of 1130–1210 °C for a homogenization time of ≥48 h.

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