A nickel alloy welding wire for a high temperature gas cooled reactor nuclear power plant and a method of manufacturing the same

Abstract

The application discloses a nickel alloy welding wire for a high-temperature gas cooled reactor nuclear power equipment and a preparation method thereof. By designing alloy components and matching suitable processes, reasonably controlling process parameters such as vacuum induction smelting, electroslag remelting, forging, hot rolling and cold drawing, the uniformity of the components and the structure of the welding wire can be ensured, the surface quality of the nickel alloy welding wire for the high-temperature gas cooled reactor nuclear power equipment is good, the welding process and the welding stability of the welding wire are further ensured, and the welding performance meets the high requirements of advanced nuclear energy technology.

Description

Technical Field

[0001] This invention relates to the field of special alloy smelting and material processing, and more specifically, to a nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment and its preparation method. This nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment is mainly suitable for welding key components of high-temperature reactor nuclear islands that require high-temperature creep resistance and high-temperature steam oxidation resistance. Background Technology

[0002] Currently, commercial nuclear power plants primarily use pressurized water reactors, operating at temperatures of 300–350°C. To improve energy conversion efficiency, the international community has proposed the concept of fourth-generation reactors, identifying six candidate technologies, including fast neutron reactors, ultra-high temperature gas-cooled reactors (UHT reactors), and supercritical water reactors. UHT reactors, based on modular high-temperature gas-cooled reactor technology, are widely recognized by experts as one of the most promising fourth-generation advanced nuclear energy system technologies for near-term realization. These high-temperature reactors use helium for cooling, with helium outlet temperatures reaching 750°C. Therefore, under such strictly controlled high-temperature and high-pressure environments, the main equipment in the nuclear island utilizes a large amount of high-temperature resistant materials; in addition to common 304 and 316 stainless steel, nickel-based materials or iron-nickel-chromium materials are also used. For example, in the steam generator, the heat exchange tubes of the high superheat section, the connecting pipes at the main steam outlet, and the main steam tube plate are made of 800H nickel-based alloy; the components of the heat exchange assembly (including the central cylinder, suspension ribs, heat exchange tube support components, outer cylinder, etc.), the material of the top steam generator positioning plate, the material of the fixing cylinder used to support the top positioning plate, the wrapping material and support structure of the connecting pipes, the hot helium gas shielding plate of the high-temperature top chamber, and the heat shielding cylinder of the outlet connecting pipe are all made of 625 alloy. Due to the use of a large amount of nickel-based alloy, a corresponding amount of nickel-based alloy welding materials are also used.

[0003] High-temperature reactors have long design lifespans and operate in harsh environments. Their components are used for extended periods under high temperature and pressure, requiring materials with sufficiently high high-temperature strength, creep strength, and resistance to high-temperature oxidation. Similarly, the welding materials must possess a high-temperature creep strength ≥55 MPa after 105 hours at 675°C, and exhibit Class I complete oxidation resistance (oxidation rate <0.1 g / m²·h) under high-temperature and high-pressure steam oxidation at 675°C and 14.5 MPa. Therefore, conventional nickel-based alloy welding materials often fail to meet these requirements for high-temperature creep resistance and high-temperature and high-pressure oxidation resistance, necessitating further design of the material composition and manufacturing process.

[0004] The current development trend at home and abroad is mainly to try to improve the above-mentioned shortcomings by adding certain alloying elements. However, elements that improve the high-temperature creep strength and high-temperature oxidation resistance of alloys are often mutually exclusive. Some elements can significantly improve high-temperature strength, but often lose high-temperature oxidation resistance. Therefore, how to effectively improve both properties has become a technical challenge.

[0005] Existing technologies also involve research on alloys that resist high-temperature oxidation. Application No. 201510050073.6 discloses a copper-nickel based alloy that resists high-temperature oxidation and can work stably at a high temperature of 800℃. However, this alloy is a copper-nickel alloy, with copper as the main component and nickel as the alloying element. It is completely different from the alloy system of the present application and has poor durability. Application No. 200810235501.2 discloses a nickel-based alloy for nuclear power steam generators, whose main components are Ni, Cr, Si, C, Mn, RE, Cu, Ti, Co, B, and Fe. The weight percentage content of each component is as follows: Ni: 64.8-77.5%, Cr: 14.0-19.5%, Si: 0.20-0.80%, C: 0.0495-0.100%, Mn: 0.00-1.20%, RE: 0.08-0.22%, Cu: 0.00-0.50%, Ti: 0.150-0.800%, Co: 0.00-0.10%, B: 0-0.001%, Fe: 7.0-12.0%. However, this alloy contains a certain amount of Fe and has a low Cr content, which is not conducive to high-temperature oxidation resistance and high-temperature strength. The high-temperature performance is not disclosed in this patent. Application No. 201310123158.3 discloses a martensitic heat-resistant steel for the main steam pipe of an ultra-supercritical thermal power unit. Its chemical composition is: C 0.07~0.12, Si 0.15~0.50, Mn 0.30~0.55, Cr 8.50~9.50, Mo 0.30~0.60, Nb 0.05~0.09, V 0.15~0.25, W 1.50~2.00, B 0.0010~0.0060, N The composition is 0.03~0.07, P≤0.015, S≤0.005, Altot≤0.01, O≤0.003, with the remainder being Fe and unavoidable impurities. This heat-resistant steel is a new type of martensitic heat-resistant steel formed by adding microalloying elements such as W, B, V, Nb, and N to the Cr-Mo type alloy structural steel. This steel has excellent oxidation resistance, strong corrosion resistance, excellent high-temperature strength, and excellent thermophysical parameters. It is mainly used in the main steam pipeline of ultra-supercritical thermal power units. However, this steel is an Fe-based material, and its creep performance and oxidation resistance at high temperatures are not disclosed, which is completely different from the nickel-based alloy system in this technical solution.Application No. 200910220453.4 discloses a high-chromium martensitic heat-resistant steel and its manufacturing method. The steel's composition range (weight percentage) is: C: 0.07–0.10%, Cr: 10.0–11.0%, Mo: 0.3–0.5%, W: 2.0–3.0%, Co: 2.0–3.0% and 0.8 ≤ (Co content / W content) ≤ 1.2, Mn: 0.3–0.5%, Si: 0.2–0.4%, Ni: <0.5%, B: 0.001– The steel contains 0.006% Fe (balance), 0.03–0.10% N, and 0.15–0.25% V and 0.04–0.08% Nb, resulting in a high-chromium martensitic heat-resistant steel for thermal power plants that exhibits both high oxidation resistance and high creep resistance at high temperatures. However, this steel is also an Fe-based material, with only its properties disclosed for 600–650°C. Its creep resistance and oxidation resistance at higher temperatures do not meet the design requirements for nuclear power plants, making it completely different from the nickel-based alloy system in this technical solution. Since the above technology fails to solve the problems of existing technologies, it is necessary to design alloy compositions and matching processing techniques to achieve a better balance of strength and plasticity, fundamentally addressing issues such as high-temperature creep resistance and oxidation resistance, and meeting the processability and performance indicators of nickel-based alloy welding materials for nuclear power equipment. Summary of the Invention

[0006] To address the aforementioned deficiencies in existing technologies, the present invention aims to provide a nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment and its preparation method. By designing the alloy composition and matching suitable processes, and rationally controlling process parameters such as electroslag remelting, forging, hot rolling, and drawing, the uniformity of the welding wire composition and structure can be ensured, resulting in good surface quality of the nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment. This further guarantees the welding processability and welding stability of the welding wire, enabling the weld performance to meet the high welding requirements of advanced nuclear energy technologies.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The first aspect of this invention provides a nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment, comprising the following components by mass percentage: C: 0.01–0.10%, Cr: 12.0–33.0%, Mn: 0.50–5.0%, Nb: 2.0–3.0%, Te: 0.001–2.8%, Si: 0.05–1.00%, Al: 0.01–1.00%, Ti: 0.10–1 0.20%, Y: 0.01~0.90%, Mo: 0.01~1.00%, Ta: 0.001~0.50%, Mg: 0.001~0.06%, Fe≤2.0%, P≤0.010%, S≤0.008%, Cu≤0.10%, Co≤0.02%, N≤0.030%, Zr≤0.02%, B≤0.005%, with the balance being Ni and unavoidable impurities;

[0009] Among them, Ni ≥ 60.0%, and the impurity content is inevitably ≤ 0.50%.

[0010] Preferably, the composition of the nickel alloy welding wire for the high-temperature gas-cooled reactor nuclear power equipment satisfies: Si+Te≤3.0wt%, Y+Mg≤0.90wt%, 0.5Mo+Ta+Nb≤3.5wt%, and the ratio of (Mo+Ta) / Nb is 0.1 to 0.8.

[0011] Preferably, the composition of the nickel alloy welding wire for the high-temperature gas-cooled reactor nuclear power equipment meets the following requirements: C: 0.015-0.08%, Ni ≥ 63.0%, Cr: 16.0-28.0%, Mn: 1.50-5.0%, Te: 0.05-2.8%, Y: 0.05-0.60%, Mo: 0.05-1.00%, Ta: 0.05-0.50%, Mg: 0.002-0.05%, P ≤ 0.008%, S ≤ 0.006%, Cu ≤ 0.08%, Co ≤ 0.01%, N ≤ 0.025%, Zr ≤ 0.01%, by mass percentage.

[0012] Preferably, the composition of the nickel alloy welding wire for the high-temperature gas-cooled reactor nuclear power equipment meets the following requirements: C: 0.025-0.06%, Ni ≥ 60.0%, Cr: 17.0-23.0%, Mn: 2.0-5.0%, Te: 0.10-2.8%, Mg: 0.006-0.03%, P ≤ 0.006%, S ≤ 0.004%, Cu ≤ 0.05%, by mass percentage.

[0013] A second aspect of this invention provides a method for preparing nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment, comprising the following steps:

[0014] S1, Ingredients: Raw materials for the nickel alloy welding wire composition of high-temperature gas-cooled reactor nuclear power equipment according to the first aspect of the present invention.

[0015] S2, vacuum induction smelting: Ni and Cr are added to the vacuum induction furnace in batches according to the proportion. After the vacuum degree is ≤2.6Pa, the material is melted at high power. After melting, alloying elements Mn, Nb, Te, Si, Mo and Ta are added in batches. After complete melting, the power is reduced and the furnace is held at the temperature for 30 to 60 minutes for refining. Then Al, Ti, Y and Mg are added to adjust the composition to the target composition of nickel alloy welding wire for high temperature gas-cooled reactor nuclear power equipment. The steel is then cast to obtain steel ingots.

[0016] S3, electroslag remelting, the steel ingot is electroslag remelted under Ar gas protection to obtain an electroslag ingot, wherein MgO and Y2O3 are added to the slag material in the electroslag remelting process;

[0017] S4, Forging, forging electroslag ingots into round or square billets;

[0018] S5, hot rolling, rolling the bar billet into wire rod coils, then performing a solution treatment on the wire rod coils, and pickling the wire rod coils using an alkaline bath and mixed acid process;

[0019] S6, cold drawing of wire rod, is a process of cold drawing the pickled wire rod into a coil shape and then drawing it into a nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment through 2 to 5 heat treatments.

[0020] Preferably, in step S2:

[0021] The power consumption during the chemical processing is n*(200~250) kW; the power consumption during the heat preservation and refining process is n*(80~180) kW; where n is the furnace loading capacity in tons. And / or

[0022] The Mg is a Ni-Mg master alloy, with a Mg content of 2-15 wt% of the total mass of the Ni-Mg master alloy; the Y is added using a Ni-Al-Y master alloy, with a Y content of 1-10 wt% of the total mass of the Ni-Al-Y master alloy; and / or

[0023] During the casting and tapping of steel, the tapping temperature T 出钢 Calculate using the following formula:

[0024] T 出钢 =T 熔 +(80~220)℃;

[0025] T 熔 =1450-60[C]-1.6[Cr]-13[Si]-4[Mn]-5[Al]-11[Ti]-7[Nb]-2.7[Ta]-0.6[Y]-1.5[Mo]-18[Te]-10.7[Mg]-0.7[Fe];

[0026] In the formula, T出钢 The tapping temperature is ℃;

[0027] T 熔 The initial melting point of the alloy is ℃;

[0028] [C], [Cr], [Si], [Mn], [Al], [Ti], [Nb], [Ta], [Y], [Mo], [Te], [Mg], [Fe] represent the content (%) of C, Cr, Si, Mn, Al, Ti, Nb, Ta, Y, Mo, Mg, and Fe elements in the alloy raw material; and / or

[0029] In step S3: the amount of MgO added is 0.1 to 2 wt% of the total mass of the slag, and the amount of Y2O3 added is 0.1 to 3 wt% of the total mass of the slag.

[0030] Preferably, in step S5:

[0031] During the rolling process, the heating temperature is 1100–1200℃, and the final rolling temperature is ≥800℃; and / or

[0032] During the solution treatment, the solution temperature is 1020–1100℃; and / or

[0033] The mixed acid consists of HNO3 and HF, with a mass concentration ratio of HNO3 to HF of 4:1 to 6:1, and the remainder is mixed with 60 to 80 wt% water; the pickling temperature is 50 to 75°C.

[0034] Preferably, in step S1, the raw material undergoes rust removal and baking treatment; and / or

[0035] In step S4, during the forging process, the forging is performed 1 to 4 times, the forging heating temperature is 1140 to 1220℃, and the final forging temperature is ≥820℃; and / or

[0036] In step S6:

[0037] During the cold drawing process, the deformation amount per pass is 10-30%, the deformation amount per heat treatment is 20-70%, and the deformation amount in the final heat treatment is 30-60%; and / or

[0038] Between each annealing cycle, a hydrogen-protected continuous annealing furnace is used for softening intermediate annealing at a temperature of 1040–1100℃ and a annealing rate of 3.0–9.5 m / min.

[0039] The third invention provides a welding process for nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment according to the first aspect of the invention, characterized in that an argon arc gas shielded welding process is adopted, and the parameters during the welding process are controlled as follows: preheating temperature is 120-180℃, interpass temperature is 120-180℃, welding current is 200-300A, arc voltage is 10-15V, welding speed is 90-140mm / min, wire feed speed is 850-2000mm / min, argon flow rate is 12-35L / min, and heat input is 1.5-2.8kJ / mm.

[0040] Preferably, the weld metal obtained after welding has a tensile strength ≥380MPa, a yield strength ≥190MPa, and an elongation ≥140MPa at 675℃. 3 The weld metal exhibits a creep rupture strength ≥100MPa and an oxidation rate of <0.08g / m² under high-temperature and high-pressure steam at 675℃ and 14.5MPa. 2 .h

[0041] The composition design and alloy strengthening design principles of the nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment of this invention are as follows:

[0042] Carbon (C): In the nickel alloy welding wire designed in this invention, carbon is a key element for the formation of carbide strengthening, which can ensure the mechanical properties and high-temperature creep performance of the weld metal. However, excessive carbon content will reduce the corrosion performance and welding processability of the alloy. Moreover, interstitial carbon is one of the main elements affecting the hot cracking of nickel-based alloys. In order to avoid or reduce the sensitivity of weld metal to hot cracking, while ensuring strength and creep performance, the carbon content is controlled at 0.01-0.10%, preferably 0.015-0.08%, and even more preferably 0.025-0.06%.

[0043] Chromium (Cr): Cr is the main element ensuring the high-temperature oxidation resistance of the alloy of this invention. It is the most important element for stabilizing the alloy surface, forming a dense Cr2O3 protective layer on the surface of the base material to prevent oxidation and hot corrosion. Generally, a Cr content exceeding 12% results in better high-temperature oxidation resistance. However, when the Cr content exceeds 33%, the increase in Cr content has little effect on improving high-temperature oxidation resistance and will lead to the precipitation of α-Cr phase, which is detrimental to mechanical properties. Therefore, this invention controls the Cr content to 12.0–33.0%, preferably 16.0–28.0%, and more preferably 17.0–23.0%.

[0044] Tellurium (Te) and Yttrium (Y): The rare earth element Y and the near-metallic element Te are key functional elements in this technology for improving high-temperature oxidation resistance. While nickel alloys exhibit excellent heat and corrosion resistance after the addition of Cr, the Cr2O3 formed on the surface is prone to volatilization at temperatures above 600℃, leading to reduced oxidation resistance. The combined addition of Te and Y elements forms new phases Cr2TeO4 and YCrO3, which facilitates the formation of the selective oxide film Cr2O3, improves the adhesion between the oxide film and the substrate, effectively inhibits the volatilization of Cr2O3, reduces the oxidation rate, and enhances the high-temperature oxidation resistance of the alloy. Simultaneously, the rare earth element Y acts as a strong deoxidizer in the secondary metallurgical process of welding, improving the welding processability of the welding wire. However, once the contents of Te and Y reach a certain level, the improvement effect gradually reaches a balance. Furthermore, since excessive amounts of these two elements can negatively impact metallurgical quality and the weldability of the welding wire, the contents of the two elements are controlled as follows: Te: 0.001–2.8%, Y: 0.01–0.90%; preferably Te: 0.05–2.8%, Y: 0.05–0.60%; and further preferably Te: 0.10–2.8%.

[0045] Silicon (Si) and manganese (Mn): These two elements improve weldability. They not only deoxidize during steelmaking but also during secondary metallurgical processes in welding, ensuring weldability and weld metal toughness, stabilizing weld microstructure, and providing solid solution strengthening, thus improving high-temperature mechanical properties. Simultaneously, in high-temperature environments, Mn forms composite oxides of NiMn₂O₄ and NiO in the alloy. These oxides hinder the inward penetration of oxygen and the outward diffusion of metal elements, improving the alloy's oxidation resistance. However, excessive Mn and Si reduce the hot workability of the weld core, and excessively high Si content increases the tendency for weld cracking. Therefore, the optimal concentrations are: Mn: 0.50–5.0%, Si: 0.05–1.00%; preferably Mn: 1.50–5.0%; and even more preferably Mn: 2.0–5.0%.

[0046] Aluminum (Al) and Titanium (Ti): Al and Ti can improve the weldability of alloys. They have a strong affinity for oxygen and can act as deoxidizing elements, protecting the weld from oxidation, effectively inhibiting the formation of CO and N pores, and promoting weld formation. They also have a certain toughening effect on the alloy. Simultaneously, Al generates Al2O3 during the high-temperature oxidation process of the alloy, and this oxide structure is beneficial to improving the alloy's high-temperature oxidation resistance. However, excessively high Al and Ti contents can affect hot workability and weldability, and the formed oxides can easily cause slag inclusions in the weld, reducing resistance to hot cracking. Furthermore, excessively high Al+Ti content can lead to the precipitation of second phases such as γ and γ', reducing the strengthening effect of high-temperature creep resistance and inducing the precipitation of harmful σ phase. Considering all factors, the content is controlled at Al: 0.01–1.00% and Ti: 0.10–1.20%; preferably Al: 0.10–1.00%.

[0047] Niobium (Nb), molybdenum (Mo), and tantalum (Ta): In this invention, Nb, Mo, and Ta are strengthening elements at high temperatures, with similar mechanisms of action but each possessing unique characteristics. Due to their large atomic radii, these three elements can increase lattice distortion and lattice atomic bond attraction in solid solutions, thereby strengthening the matrix and resulting in a significant solid solution strengthening effect. Simultaneously, these three elements are strong carbide-forming elements, capable of forming MC, M6C, or M2C type carbides, which significantly strengthen the weld metal as a second phase, enhancing the high-temperature strength-plasticity combination and improving the high-temperature creep resistance of the nickel alloy of this invention. Furthermore, the combined addition of these three elements can reduce alloy element segregation and improve the plasticity of the weld metal. The carbides formed by Nb, Mo, and Ta have significantly different densities, with NbC having a density of 7600 kg / m³. 3 The density of Mo2C is 9100 kg / m³. 3 The density of TaC is 15800 kg / m³. 3 The density of the matrix is ​​8190 kg / m³. 3This density difference can easily lead to uneven distribution of alloying elements in the matrix, which will affect the plasticity of the weld metal. However, since NbC, Mo2C, and TaC carbides are miscible with each other, meaning that the metal atoms in the carbides can be interchanged arbitrarily, a more complex (Nb,Mo,Ta)C carbide can be formed. The density of the carbide can be adjusted by controlling the ratio between the elements to make it close to the density of the matrix, thereby reducing segregation. It should be noted that in order to reduce the density difference between the carbide and the matrix, it is necessary to ensure that the ratio of Nb, Mo, and Ta is within a suitable range. Excessive Nb readily forms Ni3(Al,Ti,Nb) precipitates with Al, Ti, etc. These precipitates tend to aggregate and grow under prolonged use at high temperatures, affecting the high-temperature creep performance of nickel alloy weld metal. Therefore, in this invention, Nb: 2.0–3.0%, Mo: 0.01–1.00%, Ta: 0.001–0.50%; preferably Mo: 0.05–1.00%, Ta: 0.05–0.50%.

[0048] Iron (Fe): Fe has no significant positive effect on high-temperature oxidation resistance and durability. Therefore, Fe is not intentionally added to this alloy and is a residual element. However, the use of iron molds and some recycled materials in production inevitably results in the presence of iron. In order to control costs, this invention controls the Fe content to ≤2.0%, which is as low as possible.

[0049] Phosphorus (P) and sulfur (S): S and P are harmful elements in the alloy of this invention. These two elements tend to segregate near the grain boundaries, which can easily lead to welding hot cracks and reduce the toughness of the material. Therefore, their content needs to be strictly limited and kept as low as possible. Thus, P ≤ 0.010% and S ≤ 0.008%; preferably P ≤ 0.008% and S ≤ 0.006%; and even more preferably P ≤ 0.006% and S ≤ 0.004%.

[0050] Magnesium (Mg): Mg has a strong binding force with sulfur (S). Adding Mg to the alloy can reduce S segregation, thus significantly improving the susceptibility of the cladding metal to grain boundary cracks during welding. Simultaneously, Mg has a strong binding force with oxygen, which can act as a deoxidizer during welding, improving the purity of the cladding metal, welding processability, and weld appearance quality. However, excessively high Mg content can easily lead to oxide segregation, forming inclusions, which adversely affects mechanical properties. Therefore, Mg content is 0.001–0.06%, preferably 0.002–0.05%, and even more preferably 0.006–0.03%.

[0051] Zirconium (Zr): Zr has a strong affinity for oxygen and easily forms oxides and non-metallic inclusions that accumulate at grain boundaries, forming point defects. This invention strictly limits its content, the lower the better, Zr≤0.020%, preferably Zr≤0.01%.

[0052] Cobalt (Co) and Boron (B): Co and B are elements whose addition is restricted in nuclear power plants, and their content needs to be controlled to be as low as possible. Therefore, Co ≤ 0.02% and B ≤ 0.005%; preferably, Co ≤ 0.01%.

[0053] Nitrogen (N): N can improve the strength of materials, but it is easy to form brittle inclusions with elements such as Al and Ti, which greatly reduces the performance of alloys. Therefore, the N element needs to be as low as possible. However, considering manufacturing costs and cost-effectiveness, it is controlled at N≤0.030%, preferably N≤0.025%.

[0054] Copper (Cu): Cu is prone to brittleness during hot working and tends to form a second phase during welding, which increases the hot cracking tendency of the weld metal. Therefore, Cu should be strictly controlled below 0.10%, preferably Cu≤0.08%, and even more preferably Cu≤0.05%.

[0055] Other unavoidable impurity elements ≤0.50%.

[0056] Both tellurium (Te) and silicon (Si) have quasi-metallic properties. Excessive quasi-metallicity can affect the plasticity and weldability of the alloy. Therefore, the total amount of both should be limited to: Si + Te: ≤3.0%.

[0057] Adding too much of the rare earth element yttrium (Y) and the reactive metal magnesium (Mg) will result in them becoming impurity elements. Therefore, the total amount of both must be limited to: Y + Mg ≤ 0.90%.

[0058] In order to achieve a composite carbide density close to that of the matrix and to control the carbide size while considering a balanced carbon content, it is also necessary to satisfy 0.5Mo+Ta+Nb≤3.5% and the ratio of (Mo+Ta) / Nb between 0.1 and 0.8.

[0059] The present invention has the following beneficial effects:

[0060] 1. The nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment and its preparation method of the present invention, by designing alloy composition and matching suitable processes, and rationally controlling process parameters such as electroslag remelting, forging, hot rolling and drawing, can ensure the uniformity of welding wire composition and structure, resulting in good surface quality of nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment, further ensuring the welding processability and welding stability of the welding wire, and enabling the weld performance to meet the high welding requirements of advanced nuclear energy technology;

[0061] 2. The nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment of the present invention incorporates Al, Mn, Te, Y, and Cr elements to improve the high-temperature steam oxidation resistance of the nickel alloy; by incorporating Nb, Mo, and Ta elements, the high-temperature creep resistance of the alloy is improved; the total amount and proportion of Mo, Ta, and Nb elements are limited to improve the type, distribution, and uniformity of carbides; the content of harmful elements P and S and impurity elements Cu, Zr, and N is strictly limited, and Mg element is added in trace amounts to improve the welding processability of the welding wire;

[0062] 3. The nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment designed in this invention ensures that the weld metal composition meets the requirements and possesses excellent room temperature / high temperature tensile properties, high-temperature creep rupture properties, and resistance to high-temperature and high-pressure steam oxidation. Specifically, at 675℃, the tensile strength is ≥380MPa, the yield strength is ≥190MPa, the 103-hour creep rupture strength is ≥140MPa, the 104-hour creep rupture strength is ≥100MPa, and the oxidation rate under high-temperature and high-pressure steam at 675℃ and 14.5MPa is <0.08g / m2.h. It can be used for argon-arc welding of the main equipment of high-temperature gas-cooled reactors, meeting the high requirements of advanced nuclear energy technology for nuclear-grade nickel-based alloy welding wire. Detailed Implementation

[0063] To better understand the above-mentioned technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with embodiments.

[0064] This invention discloses a nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment, comprising the following components by mass percentage: C: 0.01–0.10%, Cr: 12.0–33.0%, Mn: 0.50–5.0%, Nb: 2.0–3.0%, Te: 0.001–2.8%, Si: 0.05–1.00%, Al: 0.01–1.00%, Ti: 0.10–1.20%, Y: 0.01–0.90%. Mo: 0.01–1.00%, Ta: 0.001–0.50%, Mg: 0.001–0.06%, Fe ≤ 2.0%, P ≤ 0.010%, S ≤ 0.008%, Cu ≤ 0.10%, Co ≤ 0.02%, N ≤ 0.030%, Zr ≤ 0.02%, B ≤ 0.005%, with the balance being Ni and unavoidable impurities; wherein Ni ≥ 60.0%, and unavoidable impurities ≤ 0.50%.

[0065] In a specific embodiment, the composition of the nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment should also meet the following requirements: Si+Te≤3.0wt%, Y+Mg≤0.90wt%, 0.5Mo+Ta+Nb≤3.5wt%, and the ratio of (Mo+Ta) / Nb is 0.1 to 0.8.

[0066] In a preferred embodiment, the nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment comprises the following components by mass: C: 0.015–0.08%, Ni ≥ 63.0%, Cr: 16.0–28.0%, Mn: 1.50–5.0%, Te: 0.05–2.8%, Y: 0.05–0.60%, Mo: 0.05–1.00%, Ta: 0.05–0.50%, Mg: 0.002–0.05%, P ≤ 0.008%, S ≤ 0.006%, Cu ≤ 0.08%, Co ≤ 0.01%, N ≤ 0.025%, and Zr ≤ 0.01%.

[0067] In a further preferred embodiment, the nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment comprises the following components: C: 0.025–0.06%, Ni ≥ 60.0%, Cr: 17.0–23.0%, Mn: 2.0–5.0%, Te: 0.10–2.8%, Mg: 0.006–0.03%, P ≤ 0.006%, S ≤ 0.004%, and Cu ≤ 0.05%, by mass percentage.

[0068] The above-mentioned manufacturing process for nickel alloy welding wire used in high-temperature gas-cooled reactor nuclear power equipment is as follows: vacuum induction smelting → electroslag remelting → forging → hot rolling → cold drawing; specifically including the following steps:

[0069] S1, Ingredients: Prepare raw materials according to the above-mentioned composition of nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment; all raw materials shall be derusted and baked.

[0070] S2, Vacuum Induction Smelting: Ni and Cr are added to the vacuum induction furnace in batches according to the ratio. After evacuating to a vacuum degree ≤2.6Pa, the furnace is melted at high power (power is n*(200~250)kw, where n is the furnace charge in tons). After the materials are completely melted, alloying elements Mn, Nb, Te, Si, Mo, Ta, etc. are added in batches. After they are completely melted, the power is reduced (power is n*(80~180)kw, where n is the furnace charge in tons) and the furnace is held at the temperature for 30~60min to remove harmful impurities, gases and non-metallic inclusions to the maximum extent to ensure the purity of the molten steel. The purity is ensured to guarantee welding processability and weld metal strength and toughness; then, deoxidizing elements such as Al, Ti, Y, and Mg, as well as trace alloying elements, are added to adjust the composition to the target composition of nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment before casting to obtain steel ingots; to ensure yield, Mg is added using a Ni-Mg master alloy, with the Mg content accounting for 2-15 wt% of the total mass of the Ni-Mg master alloy, and Y is added using a Ni-Al-Y master alloy, with the Y content accounting for 1-10 wt% of the total mass of the Ni-Al-Y master alloy; the tapping temperature must be controlled during the tapping process, with the tapping temperature T... 出钢 According to the initial melting point T of the alloy 熔 The specific calculation method is as follows:

[0071] T 出钢 =T 熔 +(80~220)℃;

[0072] T 熔 =1450-60[C]-1.6[Cr]-13[Si]-4[Mn]-5[Al]-11[Ti]-7[Nb]-2.7[Ta]-0.6[Y]-1.5[Mo]-18[Te]-10.7[Mg]-0.7[Fe];

[0073] In the formula, T 出钢 The tapping temperature is ℃;

[0074] T 熔 The initial melting point of the alloy is ℃;

[0075] [C], [Cr], [Si], [Mn], [Al], [Ti], [Nb], [Ta], [Y], [Mo], [Te], [Mg], and [Fe] represent the content of C, Cr, Si, Mn, Al, Ti, Nb, Ta, Y, Mo, Mg, and Fe elements in the alloy raw material, respectively, in percentages (%).

[0076] S3, Electroslag Remelting: The steel ingot is further refined and impurity elements such as sulfur are removed by electroslag remelting furnace under Ar gas protection. After sequential solidification through electroslag remelting, an electroslag ingot is obtained, which improves the solidification structure of the electroslag ingot and enhances the hot working plasticity of the alloy ingot. Simultaneously, because Mg and Y elements are easily oxidized, MgO and Y2O3 are added to the slag during the electroslag remelting process to ensure their yield. The amount of MgO added is 0.1–2 wt% of the total slag mass, and the amount of Y2O3 added is 0.1–3 wt% of the total slag mass. This allows Mg and Y elements to form an oxidation equilibrium with Al, Ti, Mn, Si, etc., ensuring that Mg and Y are not oxidized during the electroslag remelting process.

[0077] S4, Forging: Forging electroslag ingots into suitable round or square billets; the diameter of round billets can be φ50~200mm, the size of square billets can be 60×60~180×180mm, the number of forging passes can be 1~4, the heating temperature during forging is 1140~1220℃, and the final forging temperature is ≥820℃.

[0078] S5, Hot rolling: The bar billet is rolled into Φ4.0-Φ9.0mm wire rod coils using a wire rod mill. During the rolling process, the heating temperature is controlled at 1100-1200℃, and the final rolling temperature is ≥800℃. Then, the wire rod coils are subjected to solution treatment, with the solution treatment temperature controlled at 1020-1100℃. Afterward, the wire rod coils are pickled using an alkaline bath and mixed acid process. The mixed acid uses HNO3 and HF, with the mass concentration ratio of HNO3 to HF being 4:1-6:1, and the remainder is 60-80wt% water. The pickling temperature is 50-75℃. The above method can effectively and thoroughly remove the dense oxide scale on the surface of the nickel alloy and obtain good surface quality of the coils, which is beneficial for subsequent cold drawing.

[0079] S6, Cold drawing of wire: As needed, the pickled wire is cold-drawn into a coil shape through 2-5 passes to achieve the required diameter of nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment. During the cold drawing process, the deformation amount per pass is 10-30%, and the deformation amount per pass is 20-70%. Between each pass, a hydrogen-protected continuous annealing furnace is used for softening intermediate annealing at a temperature of 1040-1100℃ and an annealing speed of 3.0-9.5 m / min. Through the above treatment, the wire is fully softened to overcome the high deformation resistance of nickel alloy. To ensure that the wire has suitable deflection to facilitate welding wire feeding, the deformation amount in the last pass is 30-60%.

[0080] When the nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment prepared above is used to weld high-temperature gas-cooled reactor nuclear power equipment, an argon arc gas shielded welding process is adopted. The parameters during the welding process are controlled as follows: preheating temperature is 120-180℃, interpass temperature is 120-180℃, welding current is 200-300A, arc voltage is 10-15V, welding speed is 90-140mm / min, wire feed speed is 850-2000mm / min, argon flow rate is 12-35L / min, and heat input is 1.5-2.8kJ / mm.

[0081] The weld metal obtained after final welding has a tensile strength ≥380MPa, a yield strength ≥190MPa, and an elongation ≥140MPa at 675℃. 3 The weld metal exhibits a creep rupture strength ≥100 MPa and an oxidation rate of <0.08 g / m² under high-temperature and high-pressure steam at 675℃ and 14.5 MPa. 2 .h

[0082] The following section provides a further description of the nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment and its preparation method, using specific examples.

[0083] Example

[0084] The nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment was prepared using the above-mentioned preparation method. The composition of the nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment in Examples 1 to 5 is shown in Table 1, and the key parameters in the preparation process are shown in Table 2.

[0085] The nickel alloy welding wires for high-temperature gas-cooled reactor nuclear power equipment prepared in Examples 1 to 5 were welded into bevel butt weld test plates using the welding process shown in Table 3. The tensile properties, creep properties, and oxidation resistance of the weld metal under high temperature and high pressure steam at 675℃ and 14.5MPa were tested, and the results are shown in Table 4.

[0086] Table 1. Chemical composition of nickel alloy welding wire (wt%)

[0087]

[0088] Table 2 Key parameters of the manufacturing method

[0089]

[0090] Table 3 Welding process parameters

[0091]

[0092] Table 4. Weld metal properties of nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment

[0093]

[0094] As shown in Tables 1, 2, 3, and 4, the nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment prepared by this invention exhibits good weldability under argon arc gas shielded welding. The welding process is stable, spatter-free, and has good fluidity, producing a beautiful and smooth weld bead free of macroscopic defects such as slag inclusions, porosity, and cracks, as well as microscopic cracks. The tensile properties, creep rupture properties, and oxidation resistance of the weld metal at 675℃ and 14.5MPa high-temperature and high-pressure steam are significantly improved. Specifically, at 675℃, the tensile strength of the weld metal is 400–430MPa, the yield strength is 270–300MPa, and the elongation is 50–55%. 3 Hourly endurance strength ≥160MPa, 10 4 The weld metal exhibits a creep rupture strength ≥110MPa and an oxidation rate of <0.05g / m² under high-temperature and high-pressure steam at 675℃ and 14.5MPa. 2Compared with commercially available welding wires (N06600, ERNiCr-3), the tensile strength at 675℃ is increased by more than 10%; the yield strength is increased by more than 13%; the creep strength is increased by more than 21%; the high-temperature and high-pressure steam oxidation resistance is increased by more than 37%, and the elongation is not reduced. The improvement is very significant and can meet the high requirements of advanced nuclear energy technology for nuclear-grade nickel alloy welding wire.

[0095] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment, characterized in that, The composition includes the following components by mass percentage: C: 0.01–0.10%, Cr: 12.0–33.0%, Mn: 0.50–5.0%, Nb: 2.0–3.0%, Te: 0.001–2.8%, Si: 0.05–1.00%, Al: 0.01–1.00%, Ti: 0.10–1.20%, Y: 0.01–0.90%, Mo: 0.01–1.00%, Ta: 0.001–0.50%, Mg: 0.001–0.06%, Fe≤2.0%, P≤0.010%, S≤0.008%, Cu≤0.10%, Co≤0.02%, N≤0.030%, Zr≤0.02%, B≤0.005%, with the balance being Ni and unavoidable impurities; Among them, Ni ≥ 60.0%, and the unavoidable impurity content ≤ 0.50%. The composition of the nickel alloy welding wire used in the high-temperature gas-cooled reactor nuclear power equipment meets the following requirements: Si+Te≤3.0wt%, Y+Mg≤0.90wt%, 0.5Mo+Ta+Nb≤3.5wt%, and the ratio of (Mo+Ta) / Nb is 0.1~0.

8.

2. The nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment according to claim 1, characterized in that, The composition of the nickel alloy welding wire used in the high-temperature gas-cooled reactor nuclear power equipment meets the following requirements: C: 0.015~0.08%, Ni≥63.0%, Cr: 16.0~28.0%, Mn: 1.50~5.0%, Te: 0.05~2.8%, Y: 0.05~0.60%, Mo: 0.05~1.00%, Ta: 0.05~0.50%, Mg: 0.002~0.05%, P≤0.008%, S≤0.006%, Cu≤0.08%, Co≤0.01%, N≤0.025%, Zr≤0.01%, by mass percentage.

3. The nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment according to claim 2, characterized in that, The composition of the nickel alloy welding wire used in the high-temperature gas-cooled reactor nuclear power equipment meets the following requirements: C: 0.025~0.06%, Ni≥60.0%, Cr: 17.0~23.0%, Mn: 2.0~5.0%, Te: 0.10~2.8%, Mg: 0.006~0.03%, P≤0.006%, S≤0.004%, Cu≤0.05%, by mass percentage.

4. A method for preparing nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment, characterized in that, Includes the following steps: S1, Ingredients, raw materials for the nickel alloy welding wire composition of high-temperature gas-cooled reactor nuclear power equipment according to any one of claims 1 to 3; S2, vacuum induction smelting: Ni and Cr are added to the vacuum induction furnace in batches according to the proportion. After the vacuum degree is ≤2.6Pa, the material is melted at high power. After melting, alloying elements Mn, Nb, Te, Si, Mo and Ta are added in batches. After complete melting, the power is reduced and the furnace is held at the temperature for 30 to 60 minutes for refining. Then Al, Ti, Y and Mg are added to adjust the composition to the target composition of nickel alloy welding wire for high temperature gas-cooled reactor nuclear power equipment. The steel is then cast to obtain steel ingots. S3, electroslag remelting, the steel ingot is electroslag remelted under Ar gas protection to obtain an electroslag ingot, wherein MgO and Y2O3 are added to the slag material in the electroslag remelting process; S4, Forging, forging electroslag ingots into round or square billets; S5, hot rolling, rolling the bar billet into wire rod coils, then performing a solution treatment on the wire rod coils, and pickling the wire rod coils using an alkaline bath and mixed acid process; S6, wire cold drawing, is a process in which the pickled wire is cold drawn into a coil and then into a nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment through 2 to 5 heat treatments. Between each heat treatment, a hydrogen-protected continuous annealing furnace is used for softening intermediate annealing.

5. The method for preparing nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment according to claim 4, characterized in that, In step S2: During the chemical processing, the power is n*(200~250) kW; during the heat preservation and refining process, the power is n*(80~180) kW; where n is the furnace charge in tons; and / or The Mg is a Ni-Mg master alloy, with a Mg content of 2-15 wt% of the total mass of the Ni-Mg master alloy; the Y is added using a Ni-Al-Y master alloy, with a Y content of 1-10 wt% of the total mass of the Ni-Al-Y master alloy; and / or During the casting and tapping of steel, the tapping temperature T 出钢 Calculate using the following formula: T 出钢 =T 熔 +(80~220)℃; T 熔 =1450-60[C]-1.6[Cr]-13[Si]-4[Mn]-5[Al]-11[Ti]-7[Nb]-2.7[Ta]-0.6[Y]- 1.5[Mo]-18[Te]-10.7[Mg]-0.7[Fe]; In the formula, T 出钢 The tapping temperature is ℃; T 熔 The initial melting point of the alloy is ℃; [C], [Cr], [Si], [Mn], [Al], [Ti], [Nb], [Ta], [Y], [Mo], [Te], [Mg], [Fe] represent the content (%) of C, Cr, Si, Mn, Al, Ti, Nb, Ta, Y, Mo, Mg, and Fe elements in the alloy raw material, respectively. In step S3: the amount of MgO added is 0.1 to 2 wt% of the total mass of the slag, and the amount of Y2O3 added is 0.1 to 3 wt% of the total mass of the slag.

6. The method for preparing nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment according to claim 4, characterized in that, In step S5: During the rolling process, the heating temperature is 1100–1200℃, and the final rolling temperature is ≥800℃; and / or During the solution treatment, the solution temperature is 1020–1100℃; and / or The mixed acid consists of HNO3 and HF, with a mass concentration ratio of HNO3 to HF of 4:1 to 6:1, and the remainder is mixed with 60 to 80 wt% water; the pickling temperature is 50 to 75°C.

7. The method for preparing nickel alloy welding wire for high-temperature gas-cooled reactor nuclear power equipment according to claim 4, characterized in that, In step S1, the raw material undergoes rust removal and baking treatment; and / or In step S4, during the forging process, the forging is performed 1 to 4 times, the forging heating temperature is 1140 to 1220℃, and the final forging temperature is ≥820℃; and / or In step S6: During the cold drawing process, the deformation amount per pass is 10-30%, the deformation amount per heat treatment is 20-70%, and the deformation amount in the final heat treatment is 30-60%; and / or The softening intermediate annealing is performed at a temperature of 1040–1100°C and at a rate of 3.0–9.5 m / min.

8. A welding process for nickel alloy welding wire used in high-temperature gas-cooled reactor nuclear power equipment according to any one of claims 1 to 3, characterized in that, Argon arc gas shielded welding process is adopted, and the parameters during the welding process are controlled as follows: preheating temperature is 120~180℃, interpass temperature is 120~180℃, welding current is 200~300A, arc voltage is 10~15V, welding speed is 90~140mm / min, wire feed speed is 850~2000mm / min, argon flow rate is 12~35L / min, and heat input is 1.5~2.8kJ / mm.

9. The welding process for nickel alloy welding wire used in high-temperature gas-cooled reactor nuclear power equipment according to claim 8, characterized in that, The weld metal obtained after welding has a tensile strength ≥380MPa, a yield strength ≥190MPa, and an elongation ≥140MPa at 675℃. 3 The weld metal exhibits a creep rupture strength ≥100 MPa and an oxidation rate of <0.08 g / m² under high-temperature and high-pressure steam at 675℃ and 14.5 MPa. 2 .h

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