Zirconium-containing B10 copper-nickel alloy and preparation method thereof

Abstract

The invention relates to the technical field of metal materials, in particular to a zirconium-containing B10 copper-nickel alloy and a preparation method thereof. The alloy comprises the following chemical components in percentage by mass: 10.0 to 11.0 percent of Ni, 1.5 to 1.8 percent of Fe, 0.5 to 1.0 percent of Mn, 0.01 to 0.03 percent of Zr and the balance of Cu and inevitable impurities. The preparation method comprises the following steps: smelting zirconium-free raw materials in a protective atmosphere to form an alloy melt, adding a copper-zirconium intermediate alloy, stirring to obtain a zirconium-containing alloy melt, carrying out semi-continuous casting to obtain an alloy ingot, carrying out hot processing on the ingot at 800-1000 DEG C, and carrying out high-temperature elongation of an alloy product obtained by hot processing at 1000 DEG C of greater than or equal to 78%. Through addition of trace zirconium elements and a synergistic process, the high-temperature plasticity of the B10 copper-nickel alloy is remarkably improved, the hot working cracking problem is fundamentally solved, meanwhile, the original corrosion resistance and machining performance of the B10 copper-nickel alloy are reserved, and the B10 copper-nickel alloy is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of metallic materials technology, and in particular to a zirconium-containing B10 copper-nickel alloy and its preparation method. Background Technology

[0002] Copper-nickel alloys, as a class of key metallic materials possessing excellent resistance to seawater corrosion, marine biofouling, and good cold and hot working properties, are widely used in shipbuilding and marine engineering, coastal power plants, seawater desalination systems, petrochemicals, and power equipment. Among them, the C70600 (B10) copper-nickel alloy system typically uses copper as the base material, adding approximately 10% nickel and appropriate amounts of iron, manganese, and other elements to enhance strength, improve corrosion resistance, and refine the microstructure, making it an ideal material for manufacturing key components such as seawater pipelines, heat exchangers, and pumps and valves.

[0003] However, in actual industrial production, especially in the hot working processes such as extrusion, forging, or rolling after ingot casting, copper-nickel alloys often exhibit surface or internal cracking due to insufficient high-temperature plasticity. This high-temperature hot cracking problem seriously affects the product yield, quality stability, and safety in use, becoming a common technical challenge in the industry that restricts the large-scale, high-efficiency production of this type of alloy.

[0004] Hot cracking occurs because copper-nickel alloys have insufficient plasticity reserves and reduced grain boundary strength under high-temperature conditions, making them prone to intergranular cracks during plastic deformation. This is especially true under conditions of large deformation and rapid thermal cycling, where stress concentration within the copper-nickel alloy can lead to microcracks along grain boundaries, which can then expand into macroscopic defects. In severe cases, this can result in ingot scrap and a significant drop in yield. The hot working yield of traditional B10 copper-nickel alloys is typically only 70-85%, and the large amount of waste generated by high-temperature cracking not only increases production costs but also wastes resources. More seriously, if microcracks generated during hot working are not detected in time, they can gradually expand during subsequent service, causing pipeline leaks, structural failures, and other safety accidents, posing significant safety hazards and economic losses to fields such as marine engineering and power systems. Therefore, improving the resistance of copper-nickel alloys to high-temperature hot cracking has long been a common problem in the field of metallic materials, and developing targeted solutions has significant practical and industrial value.

[0005] Existing patent CN120464891A discloses a method for improving the high-temperature crack resistance of cupronickel alloys by adding modifiers. This method improves the high-temperature performance of cupronickel alloys by sequentially adding copper-magnesium alloy (deoxidizer) and pure titanium (modifier) ​​during the smelting process. Magnesium can effectively reduce the oxygen content of the melt and reduce oxide inclusions; while titanium, as a strong carbide and nitride forming element and grain refiner, can significantly refine the as-cast grains, increase the grain boundary area, thereby hindering crack propagation and improving the plasticity of the alloy under high-temperature forging or hot rolling conditions. Although this method improves the crack resistance of the alloy to a certain extent, its core depends on the modifying effect of titanium. Although the addition of titanium can refine the grains, in the B10 copper-nickel alloy system, it easily forms coarse intermetallic compounds with elements such as Fe and Mn, which may affect the corrosion resistance of the alloy; at the same time, titanium has high reactivity, and the requirements for smelting protective atmosphere and process stability are extremely stringent, increasing the difficulty and cost of industrial production control.

[0006] Existing patent CN118127365A discloses a high-strength, wear-resistant copper alloy based on an aluminum-containing Cu-Ni cupronickel alloy. It utilizes microwave synthesis of iron-manganese boride powder to replace the iron and manganese additives in traditional alloys, thereby improving the alloy's strength, wear resistance, and resistance to high-temperature thermal cracking. This approach goes beyond traditional single-element microalloying, using pre-synthesized iron-manganese boride compounds to replace the iron and manganese elements added in traditional cupronickel alloys. The introduction of iron-manganese boride refines the grain size and improves microstructure stability. After 5000 thermal cycles, the crack depth is only 0.6~0.8 mm, significantly superior to traditional alloys. However, this technology targets aluminum-containing cupronickel alloys. The presence of aluminum alters the phase composition and high-temperature mechanical properties of the alloy, resulting in significant differences compared to aluminum-free B10 copper-nickel alloys. Furthermore, this approach relies on the synthesis and addition of iron-manganese boride, a complex microwave synthesis process with low industrial production efficiency. The introduction of iron-manganese boride may also affect the excellent seawater corrosion resistance of B10 copper-nickel alloys. In addition, the core optimization direction of this approach is strength and wear resistance, with high-temperature thermal cracking resistance only as a secondary improvement. It does not perform targeted optimization for high-temperature plasticity and does not provide any data related to high-temperature elongation.

[0007] Therefore, there is an urgent need in this field for a solution that can be directly applied to B10 copper-nickel alloy, is simple to process, has controllable cost, and can significantly improve its resistance to high-temperature hot cracking, thereby effectively improving the plasticity of the alloy at high temperatures, fundamentally suppressing the tendency of hot working cracking, while ensuring that the original excellent corrosion resistance and processing performance of B10 copper-nickel alloy are not damaged, and has good feasibility for industrial production. Summary of the Invention

[0008] In view of this, the present invention aims to propose a zirconium-containing B10 copper-nickel alloy and its preparation method, so as to solve the problem that the existing B10 copper-nickel alloy is prone to cracking during hot working due to insufficient high-temperature plasticity, resulting in low yield and high product quality risks.

[0009] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0010] This invention discloses a zirconium-containing B10 copper-nickel alloy, whose chemical composition by mass percentage includes: 10.0~11.0% Ni, 1.5~1.8% Fe, 0.5~1.0% Mn, 0.01~0.03% Zr, with the balance being Cu and unavoidable impurities.

[0011] Optionally, the mass fraction of impurity elements shall satisfy: Pb≤0.01%, S≤0.005%, C≤0.05%, Zn≤0.05%, P≤0.02%, and the total of other impurities≤0.20%.

[0012] The present invention also discloses an alloy product, which is made of the above-mentioned B10 copper-nickel alloy and has a high-temperature elongation of ≥78% at 1000℃.

[0013] The present invention also discloses a preparation method for preparing the above-mentioned B10 copper-nickel alloy and alloy products. The preparation method includes: smelting a zirconium-free raw material into an alloy melt under a protective atmosphere; adding a zirconium-containing raw material to the alloy melt and stirring to obtain a zirconium-containing alloy melt; and casting the zirconium-containing alloy melt into an alloy ingot.

[0014] Optionally, the zirconium-containing raw material is a copper-zirconium master alloy; and the mass fraction of zirconium in the copper-zirconium master alloy is 10~30%.

[0015] Optionally, the zirconium-containing alloy melt is cast using a semi-continuous casting process.

[0016] Optionally, the preparation method may also include hot working of the alloy ingot.

[0017] Optionally, the hot working is at least one of hot extrusion, hot forging, and hot rolling.

[0018] Optionally, when the hot working is hot forging, the final forging temperature is ≥800℃ and the total forging ratio is ≥3.

[0019] Optionally, the temperature range for heat treatment is 800℃~1000℃.

[0020] Compared with existing technologies, the zirconium-containing B10 copper-nickel alloy and its preparation method described in this invention have the following advantages:

[0021] (1) By precisely adding 0.01~0.03% of trace zirconium, this invention enables zirconium-containing B10 copper-nickel alloy products to achieve a high-temperature elongation of over 78% at 1000℃ without changing the basic composition and corrosion resistance of B10 copper-nickel alloy. This fundamentally solves the cracking problem caused by insufficient high-temperature plasticity during the hot working of traditional B10 copper-nickel alloy, and significantly reduces the risk of ingot scrap and product quality problems.

[0022] (2) The amount of zirconium added in this invention is controlled in the trace range of 0.01~0.03%, and it has good compatibility with elements such as copper, nickel, iron, and manganese. It is not easy to form coarse and harmful intermetallic compounds, effectively preserving the inherent seawater corrosion resistance, marine biofouling resistance and excellent cold and hot working performance of B10 copper-nickel alloy, without changing the original core performance system of B10 copper-nickel alloy.

[0023] (3) The zirconium-containing raw material uses copper-zirconium master alloy, which avoids the technical difficulties of adding active elements; the combination of protective atmosphere smelting and semi-continuous casting realizes the efficient, uniform and stable addition of active element zirconium. The process is simple to operate and the cost is controllable, and it has good feasibility for large-scale production. Detailed Implementation

[0024] The present invention will be further described below with reference to specific embodiments. First, it should be noted that the data in the following experimental examples were obtained by the inventors through numerous experiments. Due to space limitations, only a portion of these data is shown in the specification, and those skilled in the art can understand and implement the present invention based on this data. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various modifications or alterations to the invention, and these modifications or alterations also fall within the scope of protection of this application.

[0025] This invention provides a zirconium-containing B10 copper-nickel alloy, whose chemical composition by mass percentage includes: 10.0~11.0% Ni, 1.5~1.8% Fe, 0.5~1.0% Mn, 0.01~0.03% Zr, with the balance being Cu and unavoidable impurities.

[0026] Zirconium can act as a grain refiner and grain boundary strengthener. By refining the grains of the alloy in the as-cast and hot-worked states and improving the grain boundary bonding strength, it fundamentally inhibits the initiation and propagation of intergranular cracks during hot working, significantly improving the high-temperature hot cracking resistance of traditional B10 copper-nickel alloys. Furthermore, zirconium has good compatibility with copper, nickel, iron, and manganese, and will not form coarse and harmful intermetallic compounds, thus fully preserving the inherent seawater corrosion resistance, marine biofouling resistance, and cold and hot working properties of B10 copper-nickel alloys.

[0027] More specifically, zirconium, as a highly reactive metallic element, significantly enhances the resistance to high-temperature hot cracking in the B10 copper-nickel alloy system through grain boundary strengthening and purification mechanisms, without compromising the original properties of the alloy. Zirconium primarily exists in solid solution form in B10 copper-nickel alloys. The solid-solution zirconium atoms interact with defects at grain boundaries, forming solid solution-strengthened zones that improve the bonding strength and plastic deformation capacity of the grain boundaries. Simultaneously, zirconium has a strong affinity for impurity elements such as oxygen and sulfur, preferentially forming high-melting-point, fine, stable compounds, thereby purifying the grain boundaries and reducing low-melting-point fragile phases on the grain boundaries. In traditional B10 copper-nickel alloy systems, grain boundary strength decreases significantly at high temperatures, leading to easy intergranular cracking during deformation. By adding zirconium to the B10 copper-nickel alloy system, its segregation and purification effects at grain boundaries enhance grain boundary strength, ensuring stability even during large-deformation hot working and preventing the generation and propagation of microcracks.

[0028] Preferably, the mass percentage of zirconium is 0.015% to 0.025%. Within this range, zirconium-containing B10 copper-nickel alloys achieve optimal high-temperature elongation while also exhibiting better process stability and economic efficiency.

[0029] It should be noted that when the zirconium content is <0.01%, its grain boundary strengthening and grain refinement effects are insufficient, and it cannot effectively suppress intergranular cracks during hot working. The high-temperature elongation of the alloy is limited, and the improvement in hot crack resistance is not significant. When the zirconium content is >0.03%, excessive zirconium may form Zr-Cu intermetallic compounds. The aggregation of these compounds at the grain boundaries will reduce the plasticity and toughness of the zirconium-containing B10 copper-nickel alloy, while increasing the difficulty and cost of composition control during the smelting process.

[0030] Specifically, the mass fraction of impurity elements must satisfy the following: Pb≤0.01%, S≤0.005%, C≤0.05%, Zn≤0.05%, P≤0.02%, and the total of other impurities≤0.20%.

[0031] Strictly limiting the types and contents of impurity elements is one of the key control measures of this invention. This ensures that while the alloy achieves the high-temperature plasticity enhancement brought by zirconium, its grain boundary purity and overall metallurgical quality are fundamentally guaranteed. By minimizing the content of impurity elements that are prone to segregation, forming low-melting-point eutectics, or brittle compounds, their enrichment at grain boundaries during high-temperature hot working can be effectively avoided, enabling the zirconium-containing B10 copper-nickel alloy to maintain stable performance under harsh processing and service conditions.

[0032] It should be noted that elements such as Pb, S, and P readily segregate at grain boundaries. Pb tends to form low-melting-point films, while S and P readily form brittle sulfides and phosphides. These significantly reduce grain boundary strength and plasticity during high-temperature deformation, and are major factors inducing hot cracking. Limiting these elements to extremely low levels is essential for eliminating hot brittleness and ensuring high-temperature plasticity. Excessive carbon content may lead to carbide formation at grain boundaries, affecting plasticity. Although Zn is soluble, excessive amounts may affect the phase stability and corrosion resistance of zirconium-containing B10 copper-nickel alloys. Controlling C ≤ 0.05% and Zn ≤ 0.05% helps maintain the alloy's homogeneous structure and overall performance. Specifying that the total amount of other impurities ≤ 0.20% is a constraint on the total amount of unlisted trace impurities, ensuring the overall purity of the alloy and preventing the synergistic effect of multiple impurities from having uncontrollable negative impacts on performance.

[0033] The present invention also provides an alloy article made of the above-mentioned B10 copper-nickel alloy, wherein the alloy article has a high-temperature elongation of ≥78% at 1000℃.

[0034] It should be noted that, more specifically, the high-temperature elongation is the core indicator for measuring the hot crack resistance of zirconium-containing B10 copper-nickel alloys. It is measured according to the national standard GB / T228.2-2015, with the test environment being 1000℃ static air. The samples are taken from alloy products after actual hot working. The results directly reflect the plastic behavior and crack resistance of zirconium-containing B10 copper-nickel alloys under actual high-temperature hot working conditions.

[0035] This invention, by adding trace amounts of zirconium, stably increases the high-temperature elongation of B10 copper-nickel alloy at 1000℃ to over 78%, fundamentally solving the industry-wide common problem of cracking due to insufficient high-temperature plasticity in B10 copper-nickel alloy during hot working. This not only significantly improves product yield, reduces production costs and scrap rates, but also reduces service safety hazards caused by microcrack residues at the material level, providing crucial material support for the manufacture of high-reliability pipelines and structural components in fields such as shipbuilding, marine engineering, and power.

[0036] The present invention also provides a preparation method for preparing the above-mentioned B10 copper-nickel alloy and alloy products. The preparation method includes: smelting a zirconium-free raw material into an alloy melt under a protective atmosphere; adding a zirconium-containing raw material to the alloy melt and stirring to obtain a zirconium-containing alloy melt; and casting the zirconium-containing alloy melt into an alloy ingot.

[0037] The preparation method of this invention employs a stepwise smelting strategy of first melting the base material and then adding zirconium. First, the main elements such as copper, nickel, iron, and manganese are smelted into a homogeneous alloy melt, and then the zirconium-containing raw material is added. This avoids premature reaction between zirconium and oxygen and nitrogen in the alloy melt, reducing oxidation loss. Combined with a protective atmosphere and thorough stirring, this achieves efficient, uniform, and stable addition of the trace active element zirconium. Furthermore, the stepwise smelting method does not require changing the core smelting process of existing B10 copper-nickel alloys; only the addition of the zirconium-containing raw material step is added, making industrialization difficult and cost-controllable.

[0038] Preferably, the protective atmosphere should be argon gas with a purity of ≥99.99%, and the smelting equipment should be a medium-frequency induction furnace.

[0039] More specifically, the step-by-step smelting process includes: completely melting and homogenizing the base materials such as copper, nickel, iron, and manganese under a protective atmosphere to form a clean and uniform alloy melt, creating an ideal environment for the subsequent addition of zirconium; adding zirconium-containing raw materials in the later stage of smelting; and immediately after adding zirconium, vigorous stirring is carried out to promote the rapid diffusion of zirconium elements, prevent local segregation, and ensure the uniformity of its macroscopic and microscopic distribution in the alloy ingot, which is a prerequisite for exerting its grain boundary strengthening effect.

[0040] It should be noted that the entire smelting and casting process is carried out under inert gas protection, which aims to minimize melt oxidation and gas absorption, especially to prevent the oxidation and burn-off of the active element zirconium, and to ensure its effective utilization and alloy cleanliness.

[0041] Specifically, the zirconium-containing raw material is a copper-zirconium master alloy; and the mass fraction of zirconium in the copper-zirconium master alloy is 10~30%.

[0042] More specifically, the zirconium mass fraction in copper-zirconium master alloys is 10-30%. This is because if the zirconium content is less than 10%, a large amount of copper-zirconium master alloy needs to be added to achieve the target zirconium addition of 0.01-0.03% in zirconium-containing B10 copper-nickel alloys. This would significantly increase the total melt volume, introduce excessive copper matrix, potentially interfere with the main component balance, and reduce smelting efficiency, increase energy consumption, and increase raw material costs. If the zirconium content is higher than 30%, the hardness and brittleness of the copper-zirconium master alloy will increase significantly, making it difficult to cut or break into blocks suitable for smelting, and inconvenient for storage, weighing, and pretreatment. Furthermore, excessively high zirconium content easily forms high-melting-point Zr-Cu intermetallic compounds, leading to a decrease in the dissolution rate of the copper-zirconium master alloy in the alloy melt, which may prolong smelting time. Incomplete local dissolution can also impair the uniformity and stability of the final alloy product's properties and may induce local stress concentration due to undissolved hard particles, which is detrimental to subsequent hot working.

[0043] It should be noted that zirconium is introduced in the form of a copper-zirconium master alloy because pure metallic zirconium has an extremely high melting point and is chemically very reactive. At conventional copper alloy smelting temperatures, directly adding zirconium powder or fragments would readily and violently react with oxygen and nitrogen in the melt, causing severe oxidation loss and increased inclusions. This results in extremely low and unstable actual zirconium yield, making precise composition control impossible. Furthermore, the density of solid zirconium differs significantly from that of molten copper, making rapid dissolution and uniform diffusion difficult after direct addition. Therefore, by using a copper-zirconium master alloy with good compatibility with the copper matrix, where zirconium is already stably present in the copper matrix as a solid solution or intermetallic compound, its activity during smelting is significantly reduced, minimizing burn-off and effectively avoiding the oxidation loss and uneven distribution problems caused by directly adding elemental zirconium. Calculations of the master alloy dosage ensure that the zirconium addition error is ≤ ±0.001%. The copper-zirconium master alloy must be wrapped in aluminum or copper foil beforehand to reduce oxidation before addition.

[0044] This invention uses a copper-zirconium master alloy with stable morphology and low burn-off rate as the zirconium source, which can maintain the zirconium content in the alloy within ±0.001%, ensuring the consistency and reproducibility of the alloy product performance. At the same time, the copper-zirconium master alloy is easy to store, weigh and add, which significantly improves the process operability and production efficiency, and reduces the raw material cost caused by the burn-off of pure zirconium. In addition, this method effectively avoids the oxidation inclusions that may be introduced by the addition of elemental zirconium, improves the purity of the melt, and through its rapid dissolution and uniform diffusion, lays a uniform microstructure for zirconium to exert its grain boundary strengthening and grain refinement effects, thereby ensuring that the zirconium-containing B10 copper-nickel alloy obtains excellent high-temperature plasticity.

[0045] Specifically, the zirconium-containing alloy melt is cast using a semi-continuous casting process.

[0046] It should be noted that semi-continuous casting features a faster, directionally controllable cooling rate, which effectively refines the as-cast grains, suppresses macroscopic segregation of zirconium and other alloying elements, and reduces casting defects such as central porosity and shrinkage cavities. This results in ingots with dense microstructure, uniform composition, and high internal quality. It provides high-quality billets with uniform structure and fewer defects for subsequent hot working, avoiding processing cracks induced by poor casting microstructure, which is a crucial prerequisite for ensuring the high-temperature plasticity of alloy products. Furthermore, the semi-continuous casting process can rapidly form a uniform and dense solidified shell on the ingot surface, resulting in good surface quality and a thin, uniform oxide scale. This surface scale can be used directly or after minimal surface processing as a hot-working billet, reducing material loss and improving yield.

[0047] Specifically, the preparation method also includes hot working of the alloy ingot.

[0048] More specifically, the temperature range for hot working is 800℃~1000℃; hot working is at least one of hot extrusion, hot forging and hot rolling; when hot working is hot forging, the final forging temperature is ≥800℃ and the total forging ratio is ≥3.

[0049] It should be noted that the forging ratio is defined as the ratio of the cross-sectional area of ​​the billet before drawing to the cross-sectional area after drawing during the drawing process; and as the ratio of the height of the billet before upsetting to the height after upsetting during the upsetting process. When performing multi-fire composite forging, the total forging ratio is the product of the forging ratios of each process. The setting of a total forging ratio ≥3 is to ensure that the ingot undergoes sufficient plastic deformation through a sufficiently large amount of plastic deformation, thereby effectively breaking up coarse cast grains, welding internal micropores and porosity defects, and promoting the further uniform distribution of alloy components such as zirconium, ultimately obtaining a high-quality forging billet with dense structure and uniform properties. When the hot working temperature is below 800℃, the deformation resistance of zirconium-containing B10 copper-nickel alloy increases, its plasticity decreases, and it is prone to work hardening leading to cracking. When the hot working temperature is above 1000℃, it may cause excessive grain growth and intensified oxidation, weakening the grain boundary strength. During hot forging, ensuring that the final forging temperature is not lower than 800℃ is to avoid deformation in the low plasticity temperature range of zirconium-containing B10 copper-nickel alloy and prevent internal cracks caused by excessively low temperature.

[0050] By limiting the process parameters of hot working, this invention ensures that the zirconium-containing B10 copper-nickel alloy remains in a state of high plasticity and low resistance during hot deformation. This not only effectively avoids work hardening and cracking caused by excessively low temperatures, but also prevents grain coarsening and performance degradation caused by excessively high temperatures. With a total forging ratio of not less than 3, the as-cast microstructure is fully broken down and reorganized, allowing the strengthening effect of zirconium to be evenly distributed in the B10 copper-nickel alloy. This significantly improves the high-temperature crack resistance of the alloy products and the consistency of the final products, providing a reliable guarantee for obtaining high-performance, high-yield zirconium-containing B10 copper-nickel alloy products.

[0051] Example 1

[0052] This example provides a method for preparing B10 copper-nickel alloy forgings with a Zr content of 0.015%, the target product being a round bar with a diameter of Ф80mm × 80mm. The specific steps include:

[0053] S1 Raw Material Preparation

[0054] Raw materials such as copper plates, nickel plates, iron powder, and manganese powder with a purity ≥99% are proportioned according to the chemical composition requirements of the zirconium-containing B10 copper-nickel alloy of this invention. The mass fractions of each component are: Ni 10.70%, Fe 1.69%, Mn 0.796%, Zr 0.015%, Cu balance. The contents of each impurity are: Pb 0.00071%, S 0.0021%, C 0.017%, Zn 0.0020%, P 0.00075%, and the total of other impurities ≤0.20%. Zr is introduced in the form of a copper-zirconium master alloy, with a Zr content of 20%. Dry charcoal or a commercially available copper alloy covering agent is used to cover the surface of the melt during smelting to prevent oxidation; the protective gas is argon with a purity ≥99.99%.

[0055] S2 Alloy Smelting and Casting

[0056] S21 Charging and Melting: Smelting is carried out in a gas-protected medium-frequency induction furnace. Before smelting, the furnace body is vacuum-baked to a vacuum degree ≤5Pa and a baking temperature of 850℃ for 1 hour to further remove residual gases and impurities in the furnace. First, all copper plates are added, then the power is turned on, and the furnace is slowly heated to about 1150℃ to completely melt the copper and form molten copper.

[0057] S22 Addition of main alloying elements: Add nickel plate, iron powder, and manganese powder to the molten copper in sequence. After each addition, raise the temperature appropriately and stir slightly, waiting for it to completely melt before adding the next one. Maintain the melt temperature within the range of 1200℃~1250℃ during this process.

[0058] S23 Refining and Homogenization: After all main alloying elements have been added, maintain the melt temperature at 1240℃~1260℃. Turn on the electromagnetic stirring function to stir the melt with electromagnetic force induced by medium-frequency current, so that Ni, Fe, and Mn elements can be fully diffused and homogenized. Then, sprinkle in an appropriate amount of covering agent and let it stand, and use a preheated graphite slag rake to thoroughly remove the slag from the surface of the melt.

[0059] S24 Zirconium addition: The copper-zirconium master alloy prepared in step S1 is quickly and smoothly pressed into the molten pool below the surface using a feeder. Immediately, the electromagnetic stirring intensity is adjusted to the maximum, and manual stirring is performed using a graphite rod to assist stirring. This allows the highly reactive zirconium to dissolve rapidly upon contact with the molten pool, and the strong stirring prevents local enrichment and promotes its uniform distribution throughout the entire molten pool.

[0060] S25 Final Deoxidation and Pre-casting Treatment: After adding zirconium and stirring, the melt is allowed to stand again to allow any trace oxide inclusions to float to the surface, followed by a final slag removal. After slag removal, a small amount of melt is taken for rapid pre-furnace spectral analysis to check if the Zr content reaches the target of approximately 0.015%. Once the composition is confirmed to be acceptable, the melt temperature is adjusted to 1175℃~1180℃.

[0061] S26 Semi-Continuous Casting: A bottom-feed semi-continuous casting machine is used. The molten metal, with its temperature adjusted, is poured into a preheated Φ100mm graphite crystallizer. The casting process is carried out under an argon atmosphere. After casting, a Φ100mm zirconium-containing B10 copper-nickel alloy ingot is obtained.

[0062] S3 Hot Working

[0063] S31 Billet Preparation: The ingot obtained in step S26 is sawn into a 50mm long billet. Both ends of the billet are machined flat to remove burrs and oxide scale, so as to avoid stress concentration and cracks during forging.

[0064] S32 Heating: The billet is placed in a heating furnace and heated to 960℃~1000℃. It is then held at this temperature to ensure that the temperature inside and outside the billet is uniform and to fully complete the solid solution and diffusion of alloying elements.

[0065] S33 Forging: The heated billet is quickly transferred to the worktable of an air hammer or hydraulic forging press for forging. The forging process employs multi-stage free forging, using a combination of upsetting and drawing techniques, with a total forging ratio ≥3. After forging, a round bar with dimensions of Φ80mm × 80mm is obtained. Throughout the forging process, the final forging temperature is ensured to be no lower than 800℃ to prevent work hardening cracking due to excessively low temperatures.

[0066] Performance testing

[0067] Samples were taken from the round bars obtained in step S3 and prepared as standard tensile specimens according to GB / T228.2-2015. Tensile tests were conducted at 1000℃ using a high-temperature tensile testing machine. Each standard tensile specimen was tested 3 times and the average value was taken.

[0068] The test results show that the B10 copper-nickel alloy with a Zr content of 0.015% in this embodiment has a high-temperature elongation of 78.0% when made into a round bar at 1000℃.

[0069] Example 2

[0070] This example provides a method for preparing B10 copper-nickel alloy tubing with a Zr content of 0.021%. The target product is an intermediate tubing with a diameter of Ф140mm × 10mm. The only difference from Example 1 is the chemical composition and subsequent heat treatment process. The other steps are the same as in Example 1, as follows:

[0071] S1 Raw Material Preparation

[0072] Using copper plates, nickel plates, iron powder, and manganese powder with a purity ≥99%, the raw materials are proportioned according to the chemical composition requirements of the zirconium-containing B10 copper-nickel alloy in this invention. The mass fractions of each component are: Ni 10.20%, Fe 1.76%, Mn 0.947%, Zr 0.021%, Cu balance, and the contents of each impurity are: Pb < 0.00010%, S 0.0012%, C 0.0011%, Zn < 0.000050%, P 0.0011%.

[0073] S26 Semi-Continuous Casting: A bottom-feed semi-continuous casting machine is used. The molten metal, with its temperature adjusted, is poured into a preheated Φ310mm graphite crystallizer. The casting process is carried out under an argon atmosphere. After casting, Φ310mm zirconium-containing B10 copper-nickel alloy round ingots are obtained.

[0074] S3 Hot Working

[0075] S31 billet preparation: The obtained round ingot is sawn into a billet with a length of 410mm.

[0076] S32 Heating: The billet is placed in a heating furnace and heated to a temperature of 880℃~960℃. It is then held at this temperature to ensure that the temperature inside and outside the billet is uniform and to fully complete the solid solution and diffusion of alloying elements.

[0077] S33 Hot Extrusion: The extrusion cylinder of the horizontal hydraulic extruder is preheated, and then the heated billet is quickly transferred into the extrusion cylinder of the horizontal hydraulic extruder. The extruder is started to perform hot extrusion processing on the billet to obtain an intermediate tube blank with a diameter of 140mm × 10mm.

[0078] The test results show that the intermediate tube blank made of B10 copper-nickel alloy with a Zr content of 0.021% in this embodiment has a high-temperature elongation of 122% at 1000℃.

[0079] Example 3

[0080] This example provides a method for preparing B10 copper-nickel alloy tubing with a Zr content of 0.017%, with the target product being a high-precision tubing with a diameter of Ф38mm × 3.5mm. This example differs from Example 2 in the specific chemical composition of the alloy, the ingot processing dimensions, and subsequent deep processing steps; however, the other steps are the same as in Example 2, as detailed below:

[0081] S1 Raw Material Preparation

[0082] Using copper plates, nickel plates, iron powder, and manganese powder with a purity ≥99%, the raw materials are proportioned according to the chemical composition requirements of the zirconium-containing B10 copper-nickel alloy in this invention. The mass fractions of each component are: Ni 10.20%, Fe 1.75%, Mn 0.926%, Zr 0.017%, Cu balance, and the contents of each impurity are: Pb < 0.00010%, S 0.0012%, C 0.0012%, Zn < 0.000050%, P 0.0016%.

[0083] S3 Hot Working

[0084] S31 billet preparation: The obtained round ingot is sawn into a billet with a length of 310mm.

[0085] S33 Hot Extrusion: The extruder is started to hot extrude the billet to obtain an intermediate tube blank of Φ100mm×10mm; then the intermediate tube blank of Φ100mm×10mm is subjected to multiple rolling, stretching and heat treatment to finally obtain a high-precision finished tube of Φ38mm×3.5mm with the target specifications.

[0086] The test results show that the intermediate tube blank made of B10 copper-nickel alloy with Zr content of 0.021% in this embodiment has a high-temperature elongation of 135.5% at 1000℃, and the finished tube made from the intermediate tube blank still has a high-temperature elongation of 128.5% at 1000℃.

[0087] Comparative Example 1

[0088] This comparative example provides a method for preparing B10 copper-nickel alloy forgings without adding Zr. The target product is a round bar with a specification of Ф80mm×80mm. The specific steps and performance testing methods are consistent with those in Example 1. The difference is that the alloy does not contain Zr in its specific chemical composition.

[0089] The test results showed that, since the B10 copper-nickel alloy in this comparative example did not contain Zr, the round bar made from it had a high-temperature elongation of only 56.2% at 1000℃.

[0090] In summary, the high-temperature elongation of Comparative Example 1 at 1000℃ was only 56.2%, reflecting the inherent defect of insufficient high-temperature plasticity in traditional B10 copper-nickel alloys. In contrast, the high-temperature elongation of the alloy products in Examples 1-3 was ≥78%, reaching a maximum of 135.5%, a significant improvement over Comparative Example 1. This demonstrates that trace amounts of Zr, through grain refinement and grain boundary strengthening, can fundamentally improve the high-temperature plasticity of B10 copper-nickel alloys and suppress hot working cracking. Furthermore, Example 1 employed hot forging, Example 2 employed hot extrusion, and Example 3 employed a multi-pass deep processing method of "hot extrusion + rolling + stretching." Under these three different processing paths, no cracking occurred in the alloy products, and the high-temperature elongation was ≥78% in all cases. In particular, Example 3, even after complex deep processing, did not show any performance degradation, proving that the zirconium-containing B10 copper-nickel alloy of this invention can flexibly adapt to various hot processing methods such as hot forging, hot extrusion, and hot rolling, meeting the production needs of different end products such as forgings, tube blanks, and high-precision pipes.

[0091] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A zirconium-containing B10 copper-nickel alloy, characterized in that, Its chemical composition, by mass percentage, includes: 10.0-11.0% Ni, 1.5-1.8% Fe, 0.5-1.0% Mn, 0.01-0.03% Zr, with the balance being Cu and unavoidable impurities.

2. The B10 copper-nickel alloy according to claim 1, characterized in that, The mass fractions of the impurity elements satisfy the following: Pb≤0.01%, S≤0.005%, C≤0.05%, Zn≤0.05%, P≤0.02%, and the total of other impurities≤0.20%.

3. An alloy article, made of the B10 copper-nickel alloy according to any one of claims 1 to 2, characterized in that, The alloy product has a high-temperature elongation of ≥78% at 1000℃.

4. A preparation method for preparing the B10 copper-nickel alloy as described in any one of claims 1-2 and the alloy article as described in claim 3, characterized in that, The preparation method includes: smelting a zirconium-free raw material into an alloy melt under a protective atmosphere; adding a zirconium-containing raw material to the alloy melt and stirring to obtain a zirconium-containing alloy melt; and casting the zirconium-containing alloy melt to obtain an alloy ingot.

5. The preparation method according to claim 4, characterized in that, The zirconium-containing raw material is a copper-zirconium master alloy; and the mass fraction of zirconium in the copper-zirconium master alloy is 10~30%.

6. The preparation method according to claim 4, characterized in that, The zirconium-containing alloy melt is cast using a semi-continuous casting process.

7. The preparation method according to claim 4, characterized in that, The preparation method further includes hot working of the alloy ingot.

8. The preparation method according to claim 7, characterized in that, The hot working is at least one of hot extrusion, hot forging and hot rolling.

9. The preparation method according to claim 8, characterized in that, When the hot working is hot forging, the final forging temperature is ≥800℃ and the total forging ratio is ≥3.

10. The preparation method according to claim 7, characterized in that, The temperature range for the heat treatment is 800℃~1000℃.