Copper alloy pipe and method for producing the same

Abstract

The application provides a copper alloy pipe and a preparation method thereof. The copper alloy pipe comprises the following elements in percentage by mass: 0.5-2.1% of Al element, 0.5-2.0% of Si element, 0.5-2.0% of Ni element, 0.05-0.08% of Ce element, 0.05-0.1% of Cr element, 0.05-0.08% of V element, the total content of inevitable impurities is less than or equal to 0.02%, and the balance is Cu element; the copper alloy pipe comprises alpha phase and beta phase, and the mass ratio of the alpha phase to the beta phase is 40-80:20-60. The copper alloy pipe can have high strength, high conductivity and corrosion resistance, the directional regulation of the ratio of the alpha phase to the beta phase can be realized by controlling the mass ratio, the adjustment can be optimized according to the requirements of strength and conductivity, and the copper alloy pipe is better applied to the scene of sea optical cable connecting piece and underwater equipment joint.

Description

Technical Field

[0001] This invention relates to the field of copper alloy technology, and more specifically, to a copper alloy tube and its preparation method. Background Technology

[0002] With the rapid development of marine engineering technology, submarine optical cable communication systems have placed higher demands on the mechanical and corrosion resistance of underwater equipment connectors. While traditional naval brass (such as C46400 and HSn62-1) possesses a certain degree of resistance to seawater corrosion, it still has the following shortcomings:

[0003] 1) Insufficient strength and conductivity matching: The tensile strength of current naval brass is usually below 400MPa, while the conductivity is generally no more than 28%IACS, which is difficult to meet the dual requirements of modern submarine optical cable equipment for signal transmission efficiency and mechanical load-bearing capacity.

[0004] 2) Dezincification corrosion sensitivity: Traditional brass with a zinc content of more than 35% is prone to dezincification corrosion in seawater environment, with a corrosion rate of up to 0.0198 mm / year, and the corrosion products can easily block precision cavities, thus affecting the reliability of the equipment.

[0005] 3) Inadequate control of trace elements: Insufficient research on the synergistic mechanism of rare earth elements such as Ce, Cr and V and transition elements, and lack of precise composition control range, resulting in poor uniformity of alloy structure, coarse grains and uneven distribution of precipitates.

[0006] 4) Weak targeting of heat treatment process: The heat treatment of brass usually adopts a wide temperature range (annealing temperature is 600~700℃), without taking into account the phase transformation kinetics of thin-walled tubes in the solution-aging process, resulting in large fluctuations in the performance of the tubes.

[0007] 5) Difficulty in controlling dimensional accuracy: Traditional extrusion processes are insufficient in controlling the dimensional accuracy of small-diameter thin-walled tubes of Φ5~Φ10mm, and improper selection of extrusion ratio can easily lead to problems such as uneven wall thickness and surface oxidation.

[0008] Therefore, there is an urgent need to develop a high-strength, high-conductivity, and corrosion-resistant brass material specifically for underwater equipment connectors for submarine optical cables. Summary of the Invention

[0009] The main objective of this invention is to provide a copper alloy pipe and its preparation method, so as to solve the problem that copper alloy materials in the prior art are difficult to achieve simultaneously with high strength, high conductivity and corrosion resistance.

[0010] To achieve the above objectives, according to one aspect of the present invention, a copper alloy tubing is provided, comprising, by mass percentage: 0.5-2.1% Al, 0.5-2.0% Si, 0.5-2.0% Ni, 0.05-0.08% Ce, 0.05-0.1% Cr, and 0.05-0.08% V, with the total content of unavoidable impurities ≤0.02%. The balance is Cu; the copper alloy tubing contains α and β phases, with a mass ratio of 40–80:20–60; the electrical conductivity of the copper alloy tubing is 35% IACS–42% IACS; the tensile strength is 580–650 MPa; the yield strength is 450–520 MPa; the elongation is 12–22%; and the self-corrosion current density is 0.8–1.0 μA / cm. 2 When copper alloy pipes are immersed in a NaCl solution with a mass concentration of 3.5%, a pH value of 7.5~8.2, a dissolved oxygen value of 6.0~8.0 mg / L, and a flow rate of 0.5 m / s, the corrosion rate of the copper alloy pipes is ≤0.0025 mm / yr, and the corrosion depth is ≤5 μm / year.

[0011] Furthermore, by mass percentage, the copper alloy tubing comprises the following elements: 0.55~1.8% Al; 0.6~1.8% Si; 0.6~1.8% Ni; 0.06~0.075% Ce; 0.06~0.09% Cr; 0.06~0.07% V, with unavoidable impurities totaling ≤0.02%, and the balance being Cu.

[0012] Furthermore, the mass ratio of Al to Si is 1.0~1.2:1; and / or, the mass ratio of Ni to Al is 0.8~1.0:1; and / or, the mass ratio of Cr to V is 1.2~1.5:1; and / or, the mass of Ce: the total mass of Cr and V is 0.4~0.6:1; and / or, the total mass of Al, Si and Ni: the total mass of Ce, Cr and V is 15~20:1.

[0013] Furthermore, the average grain size of the copper alloy tube is 15~50μm; and / or, the outer diameter of the copper alloy tube is Φ5~Φ10mm, the inner diameter of the copper alloy tube is Φ2~Φ4mm, and the length of the copper alloy tube is 1500~5000mm.

[0014] According to another aspect of the present invention, a method for preparing the above-mentioned copper alloy tubing is provided. The method includes: batching raw materials corresponding to the copper alloy and sequentially performing melting, casting, homogenization annealing, hot extrusion molding, multi-pass cold drawing, solution treatment, aging treatment, and surface passivation treatment to obtain copper alloy tubing; wherein the cooling intensity of casting is 0.5~1.0 MPa; and the temperature difference between solution treatment and aging treatment is 430~470℃.

[0015] Further, the smelting temperature is 1100~1150℃, and the smelting time is 70~110min; and / or, the smelting process includes: after the electrolytic copper undergoes a first smelting, pure zinc is added to the system after the first smelting for a second smelting, Al-Ni master alloy and Si-Cu master alloy are added sequentially to the system after the second smelting for a third smelting, and finally Ce-Cu master alloy, Cr-Cu master alloy and -Cu master alloy are added to the system after the third smelting for a fourth smelting followed by refining; wherein, the temperature of the first smelting is 1100~1130℃, and the time of the first smelting is 25~35min; the temperatures of the second, third, and fourth smeltings are each independently 1130~1150℃, and the times of the second, third, and fourth smeltings are each independently 15~25min; the refining time is 30~45min, and electromagnetic stirring is performed during the refining process.

[0016] Further, after casting, a cast tube blank is obtained; the casting is horizontal continuous casting and / or semi-continuous casting; and / or, the casting temperature is 1040~1080℃, the casting speed is 60~120mm / min; the outer diameter of the cast tube blank is Φ80~Φ120mm, the wall thickness is 15~20mm, and the length is 500~1000mm; the homogenization annealing temperature is 850~900℃, the homogenization annealing time is 2~4h, and the cooling process of homogenization annealing includes: cooling the cast tube blank to 150~200℃ and then air cooling.

[0017] Further, after hot extrusion molding, a hot-extruded tube is obtained; the hot extrusion molding temperature is 720~760℃, the hot extrusion molding ratio is 15~25:1, the hot extrusion molding speed is 5~15mm / s; the preheating temperature of the hot extrusion molding die is 360~460℃; and / or, the outer diameter of the hot-extruded tube is Φ5~Φ10mm, and the inner diameter of the hot-extruded tube is Φ2~Φ4mm; after multiple cold drawing, a multi-pass cold-drawn tube is obtained. In the multi-pass cold drawing process, the deformation amount of each pass is 15~25%; intermediate annealing is carried out during the multi-pass cold drawing process, which includes: holding the hot-extruded tube at 400~500℃ for 1~2 hours and then air cooling; the outer diameter of the tube after multi-pass cold drawing is Φ5~Φ10mm, the inner diameter of the tube after multi-pass cold drawing is Φ2~Φ4mm, the wall thickness accuracy of the tube after multi-pass cold drawing is ±0.05mm, and the length of the tube after multi-pass cold drawing is 1500~5000mm.

[0018] Furthermore, the solution treatment temperature is 870~930℃, the solution treatment time is 30~60min; the cooling method for the solution treatment is rapid water quenching, and the rapid water quenching cooling rate is ≥50℃ / s; and / or, the aging treatment temperature is 400~480℃, the aging treatment time is 4~8h; the cooling method for the aging treatment is air cooling.

[0019] Further, the surface passivation treatment includes pickling, passivation, cleaning, and drying performed sequentially; wherein, pickling is performed using an acid solution with a mass concentration of 5-10%, and the acid solution is selected from any one or more of sulfuric acid solution, hydrochloric acid solution, and nitric acid solution; the pickling temperature is 50-60℃, and the pickling time is 3-5 min; passivation is performed using a passivation solution containing benzotriazole with a mass concentration of 0.5-1% and a pH value of 7.5-8.5; the passivation temperature is 30-40℃, and the passivation time is 10-15 min.

[0020] By applying the technical solution of this invention, and controlling the types and mass content of elements within the aforementioned ranges, the resulting copper alloy tubing exhibits high strength, conductivity, and corrosion resistance. Specifically, this application significantly improves the corrosion resistance, strength, and conductivity of copper alloy tubing by constructing an Al-Si-Ni ternary strengthening system. Specifically, by controlling the mass content of Al within the aforementioned range, a dual-phase structure comprising α and β phases can be formed, thus enabling the copper alloy tubing to achieve both high strength and high conductivity. Controlling the mass ratio of the α and β phases within the aforementioned range allows for directional control of the dual-phase ratio, enabling optimization based on strength and conductivity requirements. Controlling the mass content of Si within the aforementioned range allows it to form an Al-Si eutectic phase with Al, thereby improving the wear resistance of the copper alloy tubing. Adding Ni and Cu elements at the aforementioned mass contents allows for the formation of a continuous solid solution, thereby improving the corrosion resistance and strength of the copper alloy tubing. Controlling the mass content of rare earth Ce within the aforementioned range significantly refines the β-phase grains, hindering the selective dissolution of Cu atoms, thereby improving the corrosion resistance of the copper alloy tubing. When the Ce content exceeds 0.08%, a Ce-enriched phase is easily formed, which reduces the plasticity of the copper alloy tubing. Controlling the Cr content within the aforementioned range allows for the formation of a dense Cr2O3 passivation film on the surface of the copper alloy tubing, thereby reducing the self-corrosion current density. Controlling the V content within the aforementioned range refines the grains and stabilizes the β phase, thus inhibiting corrosion. The synergistic effect of Cr and V further improves the corrosion resistance of the copper alloy tubing, reducing the corrosion rate to less than one-third of that of traditional naval brass. Furthermore, by controlling the total impurities within the aforementioned range, this application avoids galvanic corrosion caused by grain boundary segregation. In summary, the copper alloy tubing of this application combines high strength, high conductivity, and corrosion resistance, making it better suited for applications such as submarine optical cable connectors and underwater equipment joints. Attached Figure Description

[0021] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0022] Figure 1 An SEM image of the copper alloy tubing in Embodiment 1 of this application is shown. Detailed Implementation

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] As analyzed in the background section of this application, the existing technology has the problem that copper alloy materials have difficulty in simultaneously achieving high strength, high conductivity and corrosion resistance. In order to solve the above problems, this application provides a copper alloy pipe and its preparation method.

[0025] In a typical embodiment of this application, a copper alloy tubing is provided, comprising, by mass percentage, the following elements: 0.5-2.1% Al, 0.5-2.0% Si, 0.5-2.0% Ni, 0.05-0.08% Ce, 0.05-0.1% Cr, and 0.05-0.08% V, with the total unavoidable impurities content ≤0.02%, and the remainder... The copper alloy tubing contains Cu; it contains α and β phases in a mass ratio of 40–80:20–60; its electrical conductivity is 35% IACS–42% IACS; its tensile strength is 580–650 MPa; its yield strength is 450–520 MPa; its elongation is 12–22%; and its self-corrosion current density is 0.8–1.0 μA / cm². 2 When copper alloy pipes are immersed in a NaCl solution with a mass concentration of 3.5%, a pH value of 7.5~8.2, a dissolved oxygen value of 6.0~8.0 mg / L, and a flow rate of 0.5 m / s, the corrosion rate of the copper alloy pipes is ≤0.0025 mm / yr, and the corrosion depth is ≤5 μm / year.

[0026] By controlling the types and mass content of elements within the aforementioned ranges, this application yields copper alloy tubing exhibiting high strength, conductivity, and corrosion resistance. Specifically, this application significantly improves the corrosion resistance, strength, and conductivity of copper alloy tubing by constructing an Al-Si-Ni ternary strengthening system. Specifically, by controlling the mass content of Al within the aforementioned range, a two-phase microstructure comprising α and β phases can be formed, thus enabling the copper alloy tubing to achieve both high strength and high conductivity. Controlling the mass ratio of the α and β phases within the aforementioned range allows for directional control of the two-phase ratio, enabling optimization based on strength and conductivity requirements. Controlling the mass content of Si within the aforementioned range allows it to form an Al-Si eutectic phase with Al, thereby improving the wear resistance of the copper alloy tubing. Adding Ni and Cu elements at the aforementioned mass contents forms a continuous solid solution, thereby improving the corrosion resistance and strength of the copper alloy tubing. Controlling the mass content of rare earth Ce within the aforementioned range significantly refines the β-phase grains, hindering the selective dissolution of Cu atoms, thereby improving the corrosion resistance of the copper alloy tubing. When the Ce content exceeds 0.08%, a Ce-enriched phase is easily formed, which reduces the plasticity of the copper alloy tubing. Controlling the Cr content within the aforementioned range allows for the formation of a dense Cr2O3 passivation film on the surface of the copper alloy tubing, thereby reducing the self-corrosion current density. Controlling the V content within the aforementioned range refines the grains and stabilizes the β phase, thus inhibiting corrosion. The synergistic effect of Cr and V further improves the corrosion resistance of the copper alloy tubing, reducing the corrosion rate to less than one-third of that of traditional naval brass. Furthermore, by controlling the total impurities within the aforementioned range, this application avoids galvanic corrosion caused by grain boundary segregation. In summary, the copper alloy tubing of this application combines high strength, high conductivity, and corrosion resistance, making it better suited for applications such as submarine optical cable connectors and underwater equipment joints.

[0027] The preferred copper alloy pipe has a hardness of 160~190HV and a corrosion potential of -0.25~-0.18V.

[0028] To further improve the strength, conductivity, and corrosion resistance of the copper alloy tubing, in one embodiment of this application, the copper alloy tubing comprises the following elements by mass percentage: 0.55~1.8% Al, 0.6~1.8% Si, 0.6~1.8% Ni, 0.06~0.075% Ce, 0.06~0.09% Cr, 0.06~0.07% V, with the total content of unavoidable impurities ≤0.02%, and the balance being Cu.

[0029] In one embodiment of this application, the mass ratio of Al to Si is 1.0~1.2:1; and / or, the mass ratio of Ni to Al is 0.8~1.0:1; and / or, the mass ratio of Cr to V is 1.2~1.5:1; and / or, the mass of Ce: the total mass of Cr and V is 0.4~0.6:1; and / or, the total mass of Al, Si and Ni: the total mass of Ce, Cr and V is 15~20:1.

[0030] Preferably controlling the mass ratio of Al and Si elements within the above range helps to promote the uniform dispersion and precipitation of the Al-Si eutectic phase (Mg2Si type), reduce the formation of brittle phases due to the segregation of single elements, thereby further improving the wear resistance of copper alloy tubing. Furthermore, refining the size of the precipitated phase to 50~100nm helps to reduce its impact on the conductive channel, thus maintaining high conductivity.

[0031] Preferably controlling the mass ratio of Ni to Al within the above range helps Ni and Al to synergistically integrate into the Cu matrix to form a continuous solid solution, while alleviating grain boundary embrittlement caused by excessive Al segregation, thereby further improving the tensile strength and seawater corrosion resistance of copper alloy pipes.

[0032] Preferably controlling the mass ratio of Cr and V within the above range helps to promote the formation of a dense Cr2O3 passivation film through Cr, while V helps to refine the grains and stabilize the interface between the passivation film and the substrate, preventing the film from falling off, thereby further reducing the self-corrosion current density and corrosion depth of copper alloy pipes.

[0033] Preferably controlling the mass ratio of Ce to the total mass of Cr and V within the above range helps to purify matrix impurities (O, H) through Ce while refining the β-phase grains, thereby forming a dual barrier of "grain refinement + passivation film protection" with Cr and V, thus further reducing the corrosion rate of copper alloy pipes.

[0034] Preferably controlling the ratio of the total mass of Al, Si, and Ni elements to the total mass of Ce, Cr, and V elements within the above range helps to promote the precipitation of strengthening phases and simultaneously adapts them in synergy with the corrosion resistance mechanism, thereby enabling copper alloy pipes to better balance strength and corrosion resistance.

[0035] In one embodiment of this application, the average grain size of the copper alloy tube is 15~50μm; and / or, the outer diameter of the copper alloy tube is Φ5~Φ10mm, the inner diameter of the copper alloy tube is Φ2~Φ4mm, and the length of the copper alloy tube is 1500~5000mm.

[0036] Preferably controlling the average grain size of the copper alloy tubing within the aforementioned range helps to better balance strength, conductivity, and corrosion resistance. The copper alloy tubing of this application achieves the dimensional accuracy and surface quality of precision thin-walled tubes, thereby better meeting the requirements of submarine optical cable equipment.

[0037] In another typical embodiment of this application, a method for preparing the above-mentioned copper alloy tube is provided. The method includes: batching raw materials corresponding to the copper alloy and then sequentially performing melting, casting, homogenization annealing, hot extrusion molding, multi-pass cold drawing, solution treatment, aging treatment and surface passivation treatment to obtain the copper alloy tube; wherein, the cooling intensity of casting is 0.5~1.0MPa; and the temperature difference between solution treatment and aging treatment is 430~470℃.

[0038] The copper alloy tubing prepared by the method described in this application achieves a balance of high strength, high electrical conductivity, and good corrosion resistance. Specifically, smelting ensures a uniform distribution of the alloying elements. Casting, with controlled cooling intensity within the aforementioned range, improves the compactness of the billet, reduces casting defects such as shrinkage cavities and cracks, and facilitates the formation of a uniform microstructure, providing a more stable matrix for subsequent heat treatment. Homogenization annealing eliminates dendritic segregation, ensuring a uniform distribution of the β phase, thereby improving the alloy's plasticity and corrosion resistance. Hot extrusion molding ensures uniform deformation and prevents cracking. Multi-pass cold drawing not only allows for precise control of the tubing wall thickness but also eliminates work hardening, thus improving the tubing's plasticity and dimensional stability. Solution treatment allows for the complete dissolution of alloying elements, forming a supersaturated solid solution. Aging treatment promotes the formation of fine, dispersed precipitates such as Ni2Si and AlCu3, achieving precipitation strengthening. By controlling the temperature difference between solution treatment and aging treatment within the aforementioned range, phase transformation kinetics can be optimized, thereby reducing performance fluctuations to <5% (compared to >15% in traditional processes), and further improving the product consistency of copper alloy tubing. Surface passivation treatment can form a dense protective film, thereby enhancing the corrosion resistance of the copper alloy tubing. In summary, the preparation method of this application solves the problems of poor performance stability and the difficulty in processing precision thin-walled tubes. Furthermore, the prepared copper alloy tubing not only possesses high strength, conductivity, and corrosion resistance, but also, as a precision thin-walled tube, meets the stringent requirements of submarine optical cable equipment in terms of dimensional accuracy and surface quality.

[0039] In one embodiment of this application, the melting temperature is 1100~1150℃, and the melting time is 70~110min; and / or, the melting process includes: after electrolytic copper undergoes a first melting, pure zinc is added to the system after the first melting for a second melting, Al-Ni master alloy and Si-Cu master alloy are added sequentially to the system after the second melting for a third melting, and finally Ce-Cu master alloy, Cr-Cu master alloy and -Cu master alloy are added to the system after the third melting for a fourth melting followed by refining; wherein, the temperature of the first melting is 1100~1130℃, and the time of the first melting is 25~35min; the temperatures of the second, third, and fourth meltings are each independently 1130~1150℃, and the times of the second, third, and fourth meltings are each independently 15~25min; the refining time is 30~45min, and electromagnetic stirring is performed during the refining process.

[0040] Compared to a single-pot smelting method, this application utilizes a phased feeding of raw materials and electromagnetic stirring during refining, which helps to achieve a uniform distribution of alloy components while removing impurities and gases, thereby improving microstructure uniformity. Preferably, the temperature and time of the first smelting are within the aforementioned range to ensure complete melting of the copper. Preferably, the temperatures and times of the second, third, and fourth smeltings are within the aforementioned range to ensure sufficient distribution of the alloying elements within the copper matrix. Preferably, charcoal covering is used for protection during the refining process to help reduce oxidation and gas absorption.

[0041] In one embodiment of this application, after casting is completed, a cast tube blank is obtained; the casting is horizontal continuous casting and / or semi-continuous casting; and / or, the casting temperature is 1040~1080℃, the casting speed is 60~120mm / min; the outer diameter of the cast tube blank is Φ80~Φ120mm, the wall thickness of the cast tube blank is 15~20mm, and the length of the cast tube blank is 500~1000mm; the homogenization annealing temperature is 850~900℃, the homogenization annealing time is 2~4h, and the cooling process of homogenization annealing includes: cooling the cast tube blank to 150~200℃ and then air cooling.

[0042] Preferably controlling the casting method, temperature, and casting speed within the above-mentioned ranges helps to obtain the cast tube blank of the above-mentioned dimensions and improve the microstructure density of the tube blank. Preferably controlling the homogenization annealing temperature and time within the above-mentioned ranges and controlling the air cooling after cooling the cast tube blank to the above-mentioned temperature helps to eliminate dendritic segregation and make the β phase uniformly distributed.

[0043] In one embodiment of this application, after hot extrusion molding, a hot-extruded tube is obtained; the hot extrusion molding temperature is 720~760℃, the hot extrusion molding ratio is 15~25:1, and the hot extrusion molding speed is 5~15mm / s; the preheating temperature of the hot extrusion molding die is 360~460℃; and / or, the outer diameter of the hot-extruded tube is Φ5~Φ10mm, and the inner diameter of the hot-extruded tube is Φ2~Φ4mm; and / or, after multiple cold drawing passes, a multi-pass cold-drawn tube is obtained. Pipe; the deformation amount of each pass in the multi-pass cold drawing process is 15~25%; intermediate annealing is carried out during the multi-pass cold drawing process, which includes: holding the hot-extruded pipe at 400~500℃ for 1~2 hours and then air cooling; and / or, the outer diameter of the pipe after multi-pass cold drawing is Φ5~Φ10mm, the inner diameter of the pipe after multi-pass cold drawing is Φ2~Φ4mm, the wall thickness accuracy of the pipe after multi-pass cold drawing is ±0.05mm, and the length of the pipe after multi-pass cold drawing is 1500~5000mm.

[0044] Preferably controlling the temperature and extrusion ratio of hot extrusion molding within the above-mentioned range helps to ensure sufficient deformation of the pipe without cracking. Preferably controlling the extrusion speed of hot extrusion molding within the above-mentioned range helps to control the temperature rise. Preferably using a flow-dividing die structure for hot extrusion molding with a die angle of 45-60° and a working zone length of 3-5 mm, and preheating the die within the above-mentioned range, helps to obtain hot-extruded pipes of the above-mentioned dimensions.

[0045] Preferably controlling the deformation amount in each pass of the multi-pass cold drawing process within the aforementioned range helps to control the wall thickness accuracy of the pipe after multi-pass cold drawing within the aforementioned range. Preferably performing intermediate annealing during the multi-pass cold drawing process, and controlling the intermediate annealing conditions within the aforementioned range, helps to further reduce work hardening, thereby obtaining pipes with higher dimensional accuracy.

[0046] In one embodiment of this application, the solution treatment temperature is 870~930℃, the solution treatment time is 30~60min; the cooling method for the solution treatment is rapid water quenching, the rapid water quenching cooling rate is ≥50℃ / s, preferably 50~120℃ / s; and / or, the aging treatment temperature is 400~480℃, the aging treatment time is 4~8h; the cooling method for the aging treatment is air cooling.

[0047] The solution treatment time can be determined based on the pipe wall thickness. Preferably, controlling the solution treatment temperature and time within the aforementioned range helps to fully dissolve alloying elements, especially Al, Ni, and Si. Preferably, the cooling method and cooling rate of the solution treatment are within the aforementioned range, which helps to form a highly supersaturated solid solution. Preferably, controlling the aging treatment temperature, time, and cooling method within the aforementioned range helps to promote the formation of fine, dispersed precipitates such as Ni₂Si and AlCu₃, achieving precipitation strengthening.

[0048] In one embodiment of this application, the surface passivation treatment includes pickling, passivation, cleaning, and drying performed sequentially; wherein, pickling is performed using an acid solution with a mass concentration of 5-10%, and the acid solution is selected from any one or more of sulfuric acid solution, hydrochloric acid solution, and nitric acid solution; the pickling temperature is 50-60°C, and the pickling time is 3-5 min; passivation is performed using a passivation solution containing benzotriazole with a mass concentration of 0.5-1% and a pH value of 7.5-8.5; the passivation temperature is 30-40°C, and the passivation time is 10-15 min.

[0049] The surface passivation treatment described above is preferred to facilitate the formation of a dense Cu₂O / CuO double oxide film with a thickness of 200-300 nm. Pickling with an acid solution of the type and concentration described above is preferred; further, immersing the pipe in the acid solution is more preferred to help remove the oxide scale from the pipe surface. Passivation with a passivation solution of the type, pH value, and concentration described above helps to form a dense protective film. Passivation by immersing the pickled pipe in the passivation solution, controlling the passivation temperature and time, helps to improve the density of the protective film, thereby improving the corrosion resistance of the copper alloy pipe. Cleaning with deionized water followed by hot air drying is preferred.

[0050] It is preferable to completely cool the copper alloy pipe products to room temperature, then seal and package them with plastic film, and place desiccant and rust inhibitor inside the packaging to prevent oxidation of the copper alloy pipes during storage and transportation.

[0051] The beneficial effects of this application will be further illustrated below with reference to the embodiments.

[0052] Example 1

[0053] By mass percentage, the raw materials for the copper alloy are weighed and proportioned as follows: 1.3% Al, 1.2% Si, 1.0% Ni, 0.06% Ce, 0.07% Cr, 0.06% V, with unavoidable impurities totaling ≤0.02%, and the balance being Cu. Electrolytic copper, pure zinc, Al-Ni master alloy, Si-Cu master alloy, Ce-Cu master alloy, Cr-Cu master alloy, and V-Cu master alloy are then prepared.

[0054] The melting process was carried out using an industrial frequency induction furnace. First, electrolytic copper was added at 1120℃ for a first melting process of 30 minutes until melting occurred. The temperature was then increased to 1150℃, and pure zinc was added to the system after the first melting for a second melting process, held for 15 minutes. Subsequently, Al-Ni master alloy and Si-Cu master alloy were added sequentially to the system after the second melting process for a third melting process, held for 20 minutes. Finally, Ce-Cu master alloy, Cr-Cu master alloy, and V-Cu master alloy were added to the system after the third melting process for a fourth melting process, held for 25 minutes. Refining was then carried out for 30 minutes to obtain the alloy liquid. Electromagnetic stirring was performed during the refining process, and charcoal covering was used for protection.

[0055] A semi-continuous casting method was used at 1050℃ to obtain a tube blank with an outer diameter of Φ100mm, a wall thickness of 15mm, and a length of 500mm. The casting speed was 100mm / min, and the water-cooling strength was 0.8MPa.

[0056] The tube blank was heated to 880℃ for homogenization annealing, held at that temperature for 3 hours, and then cooled in the furnace to 200℃ before air cooling. The homogenized annealed tube blank was then heated to 740℃ and hot-extruded in a die to obtain an extruded tube with an outer diameter of Φ10mm and an inner diameter of Φ4mm. The extrusion ratio was 20:1, and the extrusion speed was 10mm / s. The die used a split-flow die structure with a die angle of 50°, a working zone length of 4mm, and a die preheating temperature of 400℃.

[0057] The extruded tubes were subjected to multiple cold drawing processes to obtain tubes with an outer diameter of Φ5mm, an inner diameter of Φ2mm, a wall thickness accuracy of ±0.05mm, and a length of 2000mm. The deformation in each pass was controlled within 20%. Intermediate annealing was performed during the multiple cold drawing process, consisting of holding at 450℃ for 1 hour followed by air cooling.

[0058] After multiple cold drawing processes, the pipes were solution-treated at 930℃ for 30 minutes, with rapid water quenching at a rate of 50℃ / s as the cooling method. Subsequently, they underwent aging treatment at 480℃ for 6 hours, cooled by air cooling. Finally, surface passivation was performed. The specific process was as follows: the aged pipes were immersed in an 8% sulfuric acid solution for 4 minutes, pickled at 55℃, then immersed in a passivation solution containing benzotriazole at a pH of 8 and a concentration of 0.8% for 12 minutes, passivated at 35℃, and finally rinsed with deionized water and dried with hot air to obtain copper alloy pipes with an outer diameter of Φ5mm, an inner diameter of Φ2mm, and a length of 2000mm.

[0059] Example 2

[0060] The raw materials for the copper alloy are formulated by weight percentage as follows: 0.5% Al, 2.0% Si, 0.5% Ni, 0.08% Ce, 0.05% Cr, 0.08% V, with the total unavoidable impurities content ≤0.02%, and the balance being Cu, to finally obtain the copper alloy pipe.

[0061] Example 3

[0062] The raw materials for the copper alloy are formulated by weight percentage as follows: 2.1% Al, 0.5% Si, 2.0% Ni, 0.05% Ce, 0.1% Cr, 0.05% V, with the total unavoidable impurities content ≤0.02%, and the balance being Cu, to finally obtain the copper alloy pipe.

[0063] Example 4

[0064] The difference from Example 1 is that the total mass content of Al and Si elements is 2.5%, and the mass ratio of Al to Si elements is 1.2:1, ultimately resulting in copper alloy tubing.

[0065] Example 5

[0066] The difference from Example 1 is that the total mass content of Al and Si elements is 2.5%, and the mass ratio of Al to Si elements is 2:1, ultimately resulting in copper alloy tubing.

[0067] Example 6

[0068] The difference from Example 1 is that the total mass content of Ni and Al elements is 2.3%, and the mass ratio of Ni to Al elements is 0.8:1, resulting in copper alloy tubing.

[0069] Example 7

[0070] The difference from Example 1 is that the total mass content of Ni and Al elements is 2.3%, and the mass ratio of Ni to Al elements is 0.5:1, ultimately resulting in copper alloy tubing.

[0071] Example 8

[0072] The difference from Example 1 is that the total mass content of Cr and V elements is 0.13%, and the mass ratio of Cr to V elements is 1.5:1, ultimately resulting in copper alloy tubing.

[0073] Example 9

[0074] The difference from Example 1 is that the total mass content of Cr and V elements is 0.13%, and the mass ratio of Cr to V elements is 0.7:1, ultimately resulting in copper alloy tubing.

[0075] Example 10

[0076] The difference from Example 1 is that the total mass of Ce, Cr and V is 0.19%, and the mass ratio of Ce to the total mass of Cr and V is 0.6:1, resulting in a copper alloy pipe.

[0077] Example 11

[0078] The difference from Example 1 is that the total mass of Ce, Cr and V is 0.19%, and the mass of Ce: the total mass of Cr and V is 0.05:0.14, resulting in a copper alloy pipe.

[0079] Example 12

[0080] The difference from Example 1 is that the hot extrusion molding temperature is 720°C and the extrusion ratio is 15:1, resulting in copper alloy tubing.

[0081] Example 13

[0082] The difference from Example 1 is that the hot extrusion molding temperature is 780°C and the extrusion ratio is 12:1, resulting in copper alloy tubing.

[0083] Example 14

[0084] The difference from Example 1 is that the deformation amount of each pass in the multi-pass cold drawing is 15%, and intermediate annealing is carried out during the multi-pass cold drawing process at a temperature of 400°C, finally obtaining copper alloy tubing.

[0085] Example 15

[0086] The difference from Example 1 is that the deformation amount of each pass in the multi-pass cold drawing is 30%, and intermediate annealing is carried out during the multi-pass cold drawing process at a temperature of 550°C, finally obtaining copper alloy tubing.

[0087] Example 16

[0088] The difference from Example 1 is that the surface passivation process is as follows: the aged pipe is immersed in a 10% sulfuric acid solution for 3 minutes, pickled at 50°C, then immersed in a passivation solution containing benzotriazole at a pH of 7.5 and a concentration of 1.0% for 15 minutes, passivated at 40°C, and finally cleaned with deionized water and dried with hot air to obtain the copper alloy pipe.

[0089] Example 17

[0090] The difference from Example 1 is that the surface passivation process is as follows: the aged pipe is immersed in a 15% sulfuric acid solution for 2 minutes, pickled at 45°C, then immersed in a passivation solution containing benzotriazole at pH 7.5 and a concentration of 0.3% for 20 minutes, passivated at 25°C, and finally cleaned with deionized water and dried with hot air to obtain the copper alloy pipe.

[0091] Example 18

[0092] The difference from Example 1 is that the cooling intensity of the casting is 1.0 MPa, and the final product is a copper alloy tube.

[0093] Example 19

[0094] The difference from Example 1 is that the solution treatment temperature is 870°C, the aging treatment temperature is 470°C, and the temperature difference between the solution treatment and the aging treatment is 400°C, ultimately yielding a copper alloy pipe.

[0095] Comparative Example 1

[0096] The copper alloy tubing is made of brass C46400.

[0097] Comparative Example 2

[0098] By mass percentage, the raw materials for the copper alloy were weighed according to the following composition: 3.5% Al, 0.1% Ni, and the balance Cu. The total content of unavoidable impurities was ≤0.3%. Electrolytic copper and Al-Ni master alloy were weighed and mixed, melted at 1150℃, and then refined for 30 minutes to obtain the alloy liquid.

[0099] The tube blank was produced by gravity casting at 1050℃, with an outer diameter of Φ100mm, a wall thickness of 15mm, and a length of 500mm. The casting speed was 100mm / min, and the water-cooling strength was 0.1MPa.

[0100] The tube blank was heated to 880℃ for homogenization annealing, held at that temperature for 3 hours, and then cooled in the furnace to 200℃ before air cooling. The homogenized annealed tube blank was then heated to 740℃ and hot-extruded in a die to obtain an extruded tube with an outer diameter of Φ10mm and an inner diameter of Φ4mm. The extrusion ratio was 20:1, and the extrusion speed was 10mm / s. The die used a split-flow die structure with a die angle of 50°, a working zone length of 4mm, and a die preheating temperature of 400℃.

[0101] The extruded tube is cold-drawn once to obtain a cold-drawn tube with an outer diameter of Φ5mm, an inner diameter of Φ2mm, a wall thickness accuracy of ±0.05mm, and a length of 2000mm.

[0102] After cold drawing, the tube is annealed at 650℃ for 30 minutes, and finally cleaned with deionized water and dried with hot air to obtain a copper alloy tube with an outer diameter of Φ5mm, an inner diameter of Φ2mm and a length of 2000mm.

[0103] Comparative Example 3

[0104] The difference from Example 1 is that, by mass percentage, the raw materials of the copper alloy are formulated with 2.5% Al, 0.4% Si, 0.4% Ni, 1.2% Ce, 0.02% Cr, 1.0% V, with the total content of unavoidable impurities ≤0.15%, and the balance being Cu, to finally obtain the copper alloy pipe.

[0105] Comparative Example 4

[0106] The difference from Example 1 is that the cooling intensity of the casting is 1.5 MPa, and the final product is a copper alloy tube.

[0107] Comparative Example 5

[0108] The difference from Example 1 is that the solution treatment temperature is 850°C, the aging treatment temperature is 450°C, and the temperature difference between the solution treatment and the aging treatment is 400°C, ultimately yielding a copper alloy pipe.

[0109] Test method:

[0110] Mechanical properties:

[0111] 1) Tensile strength, yield strength and elongation test: The test shall be conducted in accordance with GB / T 228.1 at room temperature and a tensile rate of 5 mm / min. The tensile specimen shall be prepared in accordance with GB / T 228.1 and cut longitudinally from the finished pipe with a gauge length of 25 mm.

[0112] 2) Hardness HV: Tested according to GB / T 4340.1, with a load of 0.5 kgf and a holding time of 15 s. The hardness test was conducted on the cross-section of the pipe, and the average value of 5 points was taken.

[0113] Electrical properties:

[0114] 1) Conductivity test: Tested according to GB / T 351-2019, 20℃, eddy current method.

[0115] 2) Resistivity test: The test is conducted according to ASTM B193 and measured using a micro-ohmmeter.

[0116] The sample surface was mechanically polished to Ra≤0.4μm. A conductivity meter was used to measure each sample three times, and the average value was taken and converted to IACS standard values.

[0117] Corrosion resistance test:

[0118] 1) Seawater immersion test

[0119] Testing standard: GB / T 42654-2023

[0120] Test conditions: 3.5% NaCl solution (w / v), temperature 25±2℃, pH 8.0, dissolved oxygen 6 mg / L, flow rate 0.5 m / s (simulating seawater environment).

[0121] Trial period: 90 days, 180 days, and 360 days.

[0122] 2) Electrochemical testing: polarization curve method (Tafel) and electrochemical impedance spectroscopy (EIS).

[0123] Average grain size test: The test was conducted according to GB / T 6394-2017 Test method for average grain size of metals.

[0124] The test results are shown in Tables 1 to 3.

[0125] Table 1

[0126]

[0127] Table 2

[0128]

[0129] Table 3

[0130]

[0131] In this embodiment, the copper alloy pipe retains its α+β dual-phase structure after 360 days of immersion, exhibiting excellent corrosion resistance. This application utilizes the synergistic effect of multiple trace elements to form a dual mechanism of "Al-Si-Ni reinforcing phase + Ce-Cr-V passivation film," overcoming the limitations of traditional brass's single-element tin resistance to zinc removal.

[0132] Figure 1 This is a SEM image of the copper alloy tubing from Example 1. Figure 1 As can be seen, the copper alloy pipe has a uniform microstructure.

[0133] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0134] By controlling the types and mass content of elements within the aforementioned ranges, this application yields copper alloy tubing exhibiting high strength, conductivity, and corrosion resistance. Specifically, this application significantly improves the corrosion resistance, strength, and conductivity of copper alloy tubing by constructing an Al-Si-Ni ternary strengthening system. Specifically, by controlling the mass content of Al within the aforementioned range, a two-phase microstructure comprising α and β phases can be formed, thus enabling the copper alloy tubing to achieve both high strength and high conductivity. Controlling the mass ratio of the α and β phases within the aforementioned range allows for directional control of the two-phase ratio, enabling optimization based on strength and conductivity requirements. Controlling the mass content of Si within the aforementioned range allows it to form an Al-Si eutectic phase with Al, thereby improving the wear resistance of the copper alloy tubing. Adding Ni and Cu elements at the aforementioned mass contents forms a continuous solid solution, thereby improving the corrosion resistance and strength of the copper alloy tubing. Controlling the mass content of rare earth Ce within the aforementioned range significantly refines the β-phase grains, hindering the selective dissolution of Cu atoms, thereby improving the corrosion resistance of the copper alloy tubing. When the Ce content exceeds 0.08%, a Ce-enriched phase is easily formed, which reduces the plasticity of the copper alloy tubing. Controlling the Cr content within the aforementioned range allows for the formation of a dense Cr2O3 passivation film on the surface of the copper alloy tubing, thereby reducing the self-corrosion current density. Controlling the V content within the aforementioned range refines the grains and stabilizes the β phase, thus inhibiting corrosion. The synergistic effect of Cr and V further improves the corrosion resistance of the copper alloy tubing, reducing the corrosion rate to less than one-third of that of traditional naval brass. Furthermore, by controlling the total impurities within the aforementioned range, this application avoids galvanic corrosion caused by grain boundary segregation. In summary, the copper alloy tubing of this application combines high strength, high conductivity, and corrosion resistance, making it better suited for applications such as submarine optical cable connectors and underwater equipment joints.

[0135] The above are merely embodiments of the present invention and are not intended to limit the invention. Those skilled in the art will recognize that the present invention can have various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A copper alloy pipe, characterized in that, The copper alloy tubing comprises the following elements by weight percentage: 0.5~2.1% Al, 0.5~2.0% Si, 0.5~2.0% Ni, 0.05~0.08% Ce, 0.05~0.1% Cr, 0.05~0.08% V, with unavoidable impurities totaling ≤0.02%, and the balance being Cu. The copper alloy tubing contains α phase and β phase, and the mass ratio of the α phase to the β phase is 40~80:20~60; The copper alloy tubing has an electrical conductivity of 35% IACS to 42% IACS, a tensile strength of 580 to 650 MPa, a yield strength of 450 to 520 MPa, and an elongation of 12% to 22%. The self-corrosion current density of the copper alloy pipe is 0.8~1.0 μA / cm. 2 ; The copper alloy pipe is immersed in a NaCl solution with a mass concentration of 3.5%, a pH value of 7.5~8.2, a dissolved oxygen value of 6.0~8.0 mg / L, and a flow rate of 0.5 m / s. The corrosion rate of the copper alloy pipe is ≤0.0025 mm / yr, and the corrosion depth of the copper alloy pipe is ≤5 μm / year.

2. The copper alloy tubing according to claim 1, characterized in that, The copper alloy tubing comprises the following elements by weight percentage: 0.55~1.8% of the Al element; 0.6~1.8% of the Si element; 0.6-1.8% of the Ni element; 0.06-0.075% of the Ce element; 0.06-0.09% of the Cr element; The V element is 0.06-0.07%, the total content of unavoidable impurities is ≤0.02%, and the balance is Cu element.

3. The copper alloy tubing according to claim 1 or 2, characterized in that, The mass ratio of Al to Si is 1.0 to 1.2:1; and / or the mass ratio of Ni to Al is 0.8 to 1.0:

1. And / or, the mass ratio of the Cr element to the V element is 1.2~1.5:1; and / or, the mass of the Ce element: the total mass of the Cr element and the V element = 0.4~0.6:1; And / or, the total mass of the Al, Si, and Ni elements : the total mass of the Ce, Cr, and V elements = 15~20 :

1.

4. The copper alloy tubing according to claim 1 or 2, characterized in that, The average grain size of the copper alloy tube is 15~50μm; and / or, the outer diameter of the copper alloy tube is Φ5~Φ10mm, the inner diameter of the copper alloy tube is Φ2~Φ4mm, and the length of the copper alloy tube is 1500~5000mm.

5. A method for preparing the copper alloy tubing according to any one of claims 1 to 4, characterized in that, The preparation method includes: batching the raw materials corresponding to the copper alloy and then sequentially performing melting, casting, homogenization annealing, hot extrusion molding, multi-pass cold drawing, solution treatment, aging treatment and surface passivation treatment to obtain the copper alloy tube; The cooling intensity of the casting is 0.5~1.0 MPa; The temperature difference between the solution treatment and the aging treatment is 430~470℃.

6. The preparation method according to claim 5, characterized in that, The melting temperature is 1100~1150℃, and the melting time is 70~110min; And / or, the smelting process includes: after electrolytic copper is smelted for the first time, pure zinc is added to the system after the first smelting for the second smelting, Al-Ni master alloy and Si-Cu master alloy are added to the system after the second smelting for the third smelting, and finally Ce-Cu master alloy, Cr-Cu master alloy and -Cu master alloy are added to the system after the third smelting for the fourth smelting and then refined; The temperature of the first melting is 1100~1130℃, and the melting time is 25~35min; the temperatures of the second melting, the third melting, and the fourth melting are each independently 1130~1150℃, and the melting times of the second melting, the third melting, and the fourth melting are each independently 15~25min. The refining time is 30-45 minutes, and electromagnetic stirring is carried out during the refining process.

7. The preparation method according to claim 6, characterized in that, After the casting is completed, a cast tube blank is obtained; the casting is horizontal continuous casting and / or semi-continuous casting; and / or, the casting temperature is 1040~1080℃, and the casting speed is 60~120mm / min. The outer diameter of the cast tube blank is Φ80~Φ120mm, the wall thickness of the cast tube blank is 15~20mm, and the length of the cast tube blank is 500~1000mm. The homogenization annealing temperature is 850~900℃, the homogenization annealing time is 2~4h, and the cooling process of the homogenization annealing includes: cooling the cast tube blank to 150~200℃ and then air cooling.

8. The preparation method according to any one of claims 5 to 7, characterized in that, After the hot extrusion molding is completed, a hot-extruded pipe is obtained; the hot extrusion molding temperature is 720~760℃, the hot extrusion molding ratio is 15~25:1, the hot extrusion molding speed is 5~15mm / s; the preheating temperature of the hot extrusion molding die is 360~460℃; and / or, the outer diameter of the hot-extruded pipe is Φ5~Φ10mm, and the inner diameter of the hot-extruded pipe is Φ2~Φ4mm; After completing the multi-pass cold drawing, a multi-pass cold-drawn tube is obtained; the deformation amount of each pass in the multi-pass cold drawing process is 15~25%; Intermediate annealing is performed during the multi-pass cold drawing process. The intermediate annealing process includes: holding the hot-extruded tube at 400~500℃ for 1~2 hours and then air cooling. The outer diameter of the tube after multiple cold drawing is Φ5~Φ10mm, the inner diameter of the tube after multiple cold drawing is Φ2~Φ4mm, the wall thickness accuracy of the tube after multiple cold drawing is ±0.05mm, and the length of the tube after multiple cold drawing is 1500~5000mm.

9. The preparation method according to any one of claims 5 to 7, characterized in that, The solution treatment temperature is 870~930℃, and the solution treatment time is 30~60min; the solution treatment cooling method is rapid water quenching, and the rapid water quenching cooling rate is ≥50℃ / s. And / or, the aging treatment temperature is 400~480℃, the aging treatment time is 4~8h; the aging treatment cooling method is air cooling.

10. The preparation method according to any one of claims 5 to 7, characterized in that, The surface passivation treatment includes pickling, passivation, cleaning and drying performed sequentially; The pickling process involves using an acid solution with a mass concentration of 5-10%, and the acid solution is selected from any one or more of sulfuric acid solution, hydrochloric acid solution, and nitric acid solution; the pickling temperature is 50-60℃, and the pickling time is 3-5 minutes. The passivation is performed using a passivation solution containing benzotriazole, wherein the mass concentration of the passivation solution is 0.5-1% and the pH value of the passivation solution is 7.5-8.5; the passivation temperature is 30-40℃ and the passivation time is 10-15 min.

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