A copper-nickel alloy clad plate and a method for manufacturing the same

Abstract

The present application relates to the technical field of metal composite material, and specifically discloses a copper-nickel alloy composite plate and a preparation method thereof. The copper-nickel alloy composite plate comprises the following steps: S1, preparing a film forming additive, vacuum degassing, establishing a main melt, adding materials after cooling, and air-atomizing granulation to obtain a granular additive containing chromium, tin, cerium and niobium; S2, complex layer smelting, adding the film forming additive into a copper-nickel base and casting into a complex layer slab; S3-S4, superimposing the complex layer slab with a base layer steel plate treated by removing the oxide skin, sealing and vacuumizing; S5-S6, hot composite rolling of the superimposed slab, and then carrying out sectional diffusion annealing treatment; and S7, surface pre-passivation treatment of the plate. The present application precisely introduces trace elements into the complex layer through the film forming additive, induces the generation of a dense composite passivation film, significantly improves the erosion resistance and pitting corrosion resistance of the composite plate in a sulfur hydrogen-rich and sand-containing seawater environment, and has a good service life.

Description

Technical Field

[0001] This invention relates to the field of metal composite materials technology, and in particular to a copper-nickel alloy composite plate and its preparation method. Background Technology

[0002] Copper-nickel alloy composite plates are a widely used material in marine engineering, such as ships, offshore platforms, and seawater pipeline systems. Their excellent durability in seawater is primarily due to the spontaneous formation of a dense layer of cuprous oxide on their surface. A protective film that effectively blocks further erosion by seawater.

[0003] However, in some more demanding marine industrial environments, such as deep-sea oil and gas extraction platforms or circulating water systems in coastal chemical plants, the seawater contains not only hydrogen sulfide produced by anaerobic bacteria metabolism (… It also often carries a large amount of high-speed flowing mud and sand.

[0004] In this environment, the originally stable cuprous oxide protective film on the surface of the copper-nickel alloy reacts with sulfur ions in the water, transforming into a loosely structured, poorly adhered cuprous sulfide layer. The loose cuprous sulfide film itself has very low mechanical strength. If it is continuously washed by high-speed water containing mud and sand, it will be easily torn off in pieces.

[0005] Once the protective film is torn off, the newly exposed alloy matrix becomes very reactive, creating a potential difference with the surrounding areas still covered by the film. This leads to a sharp increase in the corrosion rate and rapid occurrence of severe localized pitting corrosion and material loss.

[0006] To address this issue, a common approach is to directly increase the thickness of the copper-nickel cladding. While this method can extend the service life somewhat, it doesn't fundamentally change the corrosion mechanism of the material and significantly increases costs. Another approach is to replace it with a more corrosion-resistant material, such as a titanium alloy composite plate. However, titanium alloys are very expensive and also lose the excellent processing properties and resistance to marine organism adhesion inherent in copper-nickel alloys.

[0007] Currently, although some studies have attempted to improve the performance of copper-nickel alloys by adding a single alloying element, there is still no systematic solution to the corrosion problem caused by the combined effects of hydrogen sulfide and mud. Summary of the Invention

[0008] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is how to improve the resistance of copper-nickel alloy composite plates to erosion corrosion and pitting corrosion in sulfur-rich sandy seawater environment, and ensure the metallurgical bonding strength of the interface.

[0009] To achieve the above objectives, the present invention provides a copper-nickel alloy composite plate, comprising a base layer and a cladding layer. The cladding layer contains the following components by weight percentage: nickel 28.0%–32.0%, iron 1.0%–1.5%, manganese 0.5%–1.0%, chromium 0.35%–0.65%, tin 0.25%–0.55%, cerium 0.02%–0.06%, niobium 0.015%–0.045%, with the balance being copper and unavoidable impurities. In a preferred embodiment of the present invention, the weight percentage of each component in the cladding layer satisfies the relationship: 0.8 ≤ (chromium + niobium) / (tin + cerium) ≤ 1.8. This synergistic effect ensures a balance between the reinforcing phase formed by chromium and niobium and the interfacial active phase formed by tin and cerium, thereby improving the hardness of the film to resist erosion and enhancing the chemical bonding between the film and the substrate. In another preferred embodiment of the present invention, the chromium, tin, cerium, and niobium in the multilayer are introduced by adding a specific film-forming aid, which comprises the following components by weight percentage: copper 45.0%–55.0%, nickel 22.0%–28.0%, chromium 10.0%–15.0%, tin 8.0%–12.0%, cerium 1.0%–2.0%, and niobium 0.5%–1.0%.

[0010] The present invention also provides a method for preparing the above-mentioned copper-nickel alloy composite plate, comprising the following steps: S1. Preparation of film-forming aids: Particles containing high concentrations of trace elements are prepared using a specific gas atomization granulation process, which solves the problems of uneven distribution of refractory elements such as chromium and niobium and large loss of easily oxidized elements such as cerium.

[0011] S2. Multilayer melting: Melt the matrix under a protective atmosphere and add 3.2% to 4.5% of film-forming aids, then cast to obtain a multilayer slab.

[0012] S3. Base treatment: Grind the base steel plate (such as Q345R) to a roughness level. And wash and degrease.

[0013] S4. Assembly and Welding: Stacking and sealing welding, vacuuming to absolute pressure. .

[0014] S5. Hot composite rolling: After holding at 880-940℃, the rolling process is carried out with the total reduction rate controlled at 55%-75% to achieve initial interface bonding.

[0015] S6. Segmented diffusion annealing: A unique two-stage process is adopted. First, the temperature is kept at 650℃ for 2 hours to promote element diffusion, and then the temperature is kept at 400℃ for 4 hours to induce trace elements to segregate at the interface and grain boundaries.

[0016] S7. Surface pre-passivation: Immerse in oxygenated brine simulated solution to build an initial passivation film in advance.

[0017] In a further optimized embodiment of the present invention, the preparation of the film-forming aid in step S1 specifically includes the following sub-steps: P1. Degassing treatment: The raw materials copper, nickel, chromium and niobium are degassed for 1 to 2 hours under a vacuum of no more than 5 Pa and a temperature of 180 to 220°C to remove impurities adsorbed on the surface and inside of the raw materials and prevent porosity from being generated during smelting.

[0018] P2. Preparation of copper-cerium master alloy: Copper is melted in a vacuum induction furnace at 1230–1280℃, and cerium is added after switching to argon protection to obtain a primary copper-cerium master alloy containing 20% ​​by weight of cerium. This step effectively avoids the severe oxidation loss of the rare earth element cerium at high temperatures.

[0019] P3. Establishment of the main melt: In another smelting furnace, copper and nickel are melted at 1320-1380°C, and chromium and niobium treated in P1 are added in batches to establish the base melt with a high melting point composition.

[0020] P4. High-temperature melting and stirring: Electromagnetic stirring is performed at 1320–1380℃, with a rotation speed of 300–500 rpm and a holding time of 30–50 min. Forced convection diffusion ensures that refractory elements such as chromium and niobium are fully dissolved and evenly distributed in the main melt.

[0021] P5. Cooling and Feeding: Cool the main melt to 1180–1230°C, then add raw tin and the copper-cerium primary master alloy obtained in step P2 sequentially. Hold at this temperature for no more than 10 minutes. Adding vulnerable elements at low temperatures can significantly improve the yield of tin and cerium.

[0022] P6. Purification and Casting: Argon gas with a flow rate of 0.15-0.30 L / (min·kg) is bubbled through for 5-10 minutes for purification, and then cast into rods to further remove non-metallic inclusions from the melt.

[0023] P7. Homogenization and Granulation: The rods are homogenized at 860–920℃ for 2–4 hours, followed by gas atomization granulation using argon gas at a pressure of 4.0–6.0 MPa to obtain particles with a diameter of 50–250 μm. This particle size ensures instantaneous melting and secondary dispersion of components in the subsequent S2 step.

[0024] The present invention has the following technical effects: 1. By using a prepared film-forming aid, trace alloying elements such as chromium, tin, cerium, and niobium are precisely introduced into the cladding layer of the copper-nickel composite plate. These trace elements work synergistically during the corrosion process on the plate surface to form a multi-layered gradient composite passivation film. The inner layer of this film is rich in dense chromium oxide, while the outer layer is rich in stable tin oxide. Simultaneously, cerium and niobium are enriched at the film / substrate interface, effectively enhancing the adhesion and erosion resistance of the film. Seawater-resistant pipe systems and flanges manufactured using this copper-nickel alloy composite plate exhibit significantly improved protection against corrosive fluids containing hydrogen sulfide and silt, effectively resisting sulfide-induced passivation film sulfidation and peeling, as well as film damage caused by silt erosion, thereby extending the service life of components in extreme marine environments.

[0025] 2. The film-forming aid is prepared using a unique process involving two-stage melting, cooling followed by the addition of active elements (tin and cerium), and gas atomization granulation. This process effectively avoids the burn-off and macroscopic segregation of highly active elements during melting, and allows elements such as chromium and niobium to form nanoscale dispersed phases within the aid particles. Introducing this aid into the multilayer melt ensures that each trace element is uniformly and stably distributed within the copper-nickel alloy matrix. This stable elemental distribution guarantees that the copper-nickel alloy composite plate of this invention can stably form a high-performance composite passivation film during the preparation process. Marine engineering components made from this composite plate exhibit significantly reduced erosion corrosion rates compared to existing technologies, with significantly improved pitting depth and critical flow velocity for film peeling, thus enhancing service reliability in harsh environments.

[0026] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0027] Figure 1 This is a SEM image of the surface microstructure of the copper-nickel alloy composite plate cladding prepared in Embodiment 1 of the present invention after being subjected to 360 hours of scouring and corrosion in simulated seawater containing sulfur and sand. Figure 2 The image shows the surface microstructure of the copper-nickel alloy composite plate cladding prepared in Comparative Example 1 of this invention after being subjected to 360 hours of scouring and corrosion in simulated seawater containing sulfur and sand. Detailed Implementation

[0028] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0029] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the shape, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0030] Some exemplary embodiments of the invention have been described for illustrative purposes. It should be understood that the invention may be implemented in other ways not specifically shown in the accompanying drawings.

[0031] The copper-nickel alloy composite plate provided by this invention contains, in addition to 28.0%–32.0% nickel, 1.0%–1.5% iron, and 0.5%–1.0% manganese, 0.35%–0.65% chromium, 0.25%–0.55% tin, 0.02%–0.06% cerium, and 0.015%–0.045% niobium in its cladding layer. The weight percentage of trace elements in the cladding layer satisfies the following relationship: 0.8 ≤ (chromium + niobium) / (tin + cerium) ≤ 1.8. Chromium and niobium promote the formation of a dense oxide inner layer on the alloy surface, blocking the penetration of sulfur ions; tin and cerium are enriched in the outer layer of the film and at the interface between the film and the substrate. Tin enhances the chemical stability of the outer film, while cerium strengthens the mechanical adhesion between the passivation film and the substrate through pinning.

[0032] In order to incorporate these elements into the copper-nickel matrix, the present invention employs the following steps to prepare the film-forming aid: The raw materials copper, nickel, chromium, and niobium are subjected to a degassing treatment at a vacuum of no more than 5 Pa and a temperature of 180–220°C for 1–2 hours. This step utilizes the vacuum environment to remove moisture and gases from the surface of the raw materials, preventing the formation of porosity during smelting.

[0033] Pure copper is melted in a vacuum induction furnace at 1230–1280°C, then protected with argon gas and cerium is added to produce a copper-cerium primary master alloy containing 20% ​​by weight of cerium. Pre-alloying cerium with copper reduces the burn-off rate of cerium when it is subsequently added to the main melt.

[0034] When establishing the main melt, copper and nickel are melted at 1320–1380℃, and degassed chromium and niobium are added in batches. Electromagnetic stirring at 300–500 rpm is used, and the temperature is maintained for 30–50 minutes. Electromagnetic force is employed to eliminate the concentration gradient within the melt, allowing high-melting-point elements to diffuse and dissolve in the copper-nickel melt.

[0035] The main melt was then cooled to 1180–1230°C, and tin and the previously prepared copper-cerium primary master alloy were added sequentially, with the holding time controlled within 10 minutes. This short holding time at a relatively low melt temperature ensured that the tin and cerium melted and mixed evenly, and suppressed their volatilization and oxidation.

[0036] Argon gas with a flow rate of 0.15–0.30 L / (min·kg) is introduced into the melt for 5–10 minutes to purify it by bubbling. The non-metallic inclusions in the melt are carried away by the rising process of the argon gas bubbles, and then the melt is cast into bars.

[0037] The rods were homogenized at 860–920℃ for 2–4 hours to eliminate dendritic segregation in the as-cast microstructure. After treatment, argon gas at 4.0–6.0 MPa was used for gas atomization granulation. The microstructure was fixed using rapid cooling to obtain film-forming aid particles with a particle size of 50–250 μm. Chromium and niobium were dispersed within these particles.

[0038] In the preparation of the composite plate, a copper-nickel-iron-manganese matrix is ​​melted under a protective atmosphere. When the temperature is 1240–1280℃, film-forming aid particles accounting for 3.2%–4.5% of the total weight are added and the plate is cast into a composite slab. The film-forming aid particles melt and disperse into the slab at this temperature.

[0039] For the composite process, the surface of the base steel plate is ground to a roughness Ra of no more than 1.6 μm, the oxide scale is removed, and it is cleaned and degreased. Then, the cladding plate is stacked and sealed with the base steel plate, and a vacuum is applied to an absolute pressure of no more than 1.0 Pa. The vacuum environment eliminates oxygen at the interface, preventing high-temperature oxidation during the thermal composite process.

[0040] The laminated slabs are held at 880–940℃ and then subjected to hot composite rolling. The first pass reduction is controlled to be no less than 20%, and the total reduction is 55%–75%. The micro-roughness of the interface is broken through mechanical plastic deformation, which promotes the diffusion of interfacial atoms and forms a metallurgical bond.

[0041] The hot-rolled sheet is subjected to segmented diffusion annealing: first, it is held at 650℃ for 2 hours to release residual rolling stress; then it is cooled to 400℃ and held for 4 hours. The medium-temperature holding causes trace alloying elements inside the cladding layer to segregate towards grain boundaries and defects, providing nucleation sites for the formation of the passivation film.

[0042] Finally, the panels are immersed in an oxygenated brine-simulated solution for pre-passivation. Under this environment, trace elements on the multilayer surface react to form a multi-layered composite passivation film. This provides the composite panels with an initial protective barrier against the marine environment before they are put into use.

[0043] Example 1 This embodiment provides a copper-nickel alloy composite plate and its preparation method.

[0044] In this embodiment, the clad copper-nickel alloy comprises the following components by weight percentage: nickel 30.0%, iron 1.25%, manganese 0.75%, chromium 0.50%, tin 0.40%, cerium 0.04%, niobium 0.03%, with the balance being copper and unavoidable impurities. The synergistic coefficient of the trace elements K = (chromium + niobium) / (tin + cerium) ≈ 1.20.

[0045] 1. Preparation of film-forming aids The film-forming aid used in this embodiment contains the following components by weight percentage: copper 49.3%, nickel 25.0%, chromium 12.5%, tin 10.0%, cerium 2.5%, and niobium 0.7%. The specific preparation steps are as follows: P1. Raw material pretreatment: Place the raw materials copper, nickel, chromium and niobium in a vacuum furnace and degas them at a vacuum of 3 Pa and a temperature of 200 °C for 1.5 hours; place cerium and tin in a drying oven for inert gas protection.

[0046] P2. Preparation of copper-cerium master alloy: Pure copper is heated to 1250℃ and melted in a vacuum induction furnace. After switching to argon protection, metallic cerium is added and smelted to produce a copper-cerium primary master alloy ingot containing 20.0% cerium by weight.

[0047] P3. Main melt construction: Add raw materials copper and nickel to another smelting furnace, heat to 1350℃ for complete melting, and then add chromium and niobium treated in P1 in batches.

[0048] P4. High-temperature melting and stirring: Turn on the electromagnetic stirrer at 1350℃, control the speed at 400rpm, and keep stirring for 40 minutes.

[0049] P5. Adding materials after cooling: Cool the main melt to 1200℃, add raw material tin and copper-cerium primary master alloy obtained in step P2 in sequence, and hold for 8 minutes.

[0050] P6. Purification and Casting: Argon gas with a flow rate of 0.22 L / (min·kg) is bubbled through the melt for 8 minutes for purification, and then cast into rods.

[0051] P7. Homogenization and atomization granulation: The rods were homogenized at 890℃ for 3 hours, and then atomized with 5.0MPa argon gas to obtain particulate film-forming aids with a particle size of 50-250μm.

[0052] 2. Preparation of copper-nickel alloy composite plates This embodiment prepares a copper-nickel alloy composite plate, wherein the base layer is Q345R steel, and the cladding layer is prepared according to the above-mentioned component ratio. The specific steps are as follows: S1. Prepare film-forming aid particles according to steps P1 to P7 above.

[0053] S2. Multilayer melting: Melt copper, nickel, iron and manganese matrix in an argon-protected induction furnace. When the temperature reaches 1260℃, add 4.0% of the above-mentioned film-forming aid particles by weight and stir evenly, then cast into a multilayer slab.

[0054] S3. Treatment of base steel plate: Grind the surface of the base Q345R steel plate to a roughness Ra of 1.2μm, and clean and degrease with acetone.

[0055] S4. Assembly and Packaging: The cladding plate is stacked with the base steel plate, sealed and welded around the perimeter, and then vacuumed to make the absolute pressure at the interface reach 0.8Pa.

[0056] S5. Hot composite rolling: The composite slab is held at 910℃ for 2 hours and then hot rolled. The first pass reduction rate is 25% and the total reduction rate is 65%.

[0057] S6. Diffusion annealing: The rolled composite plate is annealed in sections. First, it is held at 650℃ for 2 hours, and then cooled to 400℃ and held for 4 hours.

[0058] S7. Surface pre-passivation: The annealed composite plate is immersed in 3.5% NaCl simulated brine filled with oxygen for 24 hours to generate an initial passivation film on the surface before leaving the factory.

[0059] Example 2 This embodiment provides a copper-nickel alloy composite plate and its preparation method.

[0060] In this embodiment, the clad copper-nickel alloy comprises the following components by weight percentage: nickel 28.0%, iron 1.0%, manganese 0.5%, chromium 0.35%, tin 0.40%, cerium 0.06%, niobium 0.015%, with the balance being copper and unavoidable impurities. The synergistic coefficient of the trace elements K = (chromium + niobium) / (tin + cerium) ≈ 0.79.

[0061] 1. Preparation of film-forming aids The film-forming aid used in this embodiment contains the following components by weight percentage: copper 55.0%, nickel 22.0%, chromium 10.0%, tin 11.4%, cerium 1.0%, and niobium 0.6%. The specific preparation steps are as follows: P1. Raw material pretreatment: Place the raw materials copper, nickel, chromium and niobium in a vacuum furnace and degas them at a vacuum of 5 Pa and a temperature of 180°C for 1.0 hour; place cerium and tin in a drying oven for inert gas protection.

[0062] P2. Preparation of copper-cerium master alloy: Pure copper is heated to 1230℃ and melted in a vacuum induction furnace. After switching to argon protection, metallic cerium is added and smelted to produce a copper-cerium primary master alloy ingot containing 20.0% cerium by weight.

[0063] P3, Main Melt Construction: Add raw materials copper and nickel to another smelting furnace, heat to 1320℃ for complete melting, and then add chromium and niobium treated in P1 in batches.

[0064] P4. High-temperature melting and stirring: Turn on the electromagnetic stirrer at 1320℃, control the speed at 300rpm, and keep stirring for 30 minutes.

[0065] P5. Adding materials after cooling: Cool the main melt to 1180℃, add raw material tin and copper-cerium primary master alloy obtained in step P2 in sequence, and keep it at the temperature for 10 minutes.

[0066] P6. Purification and Casting: Argon gas with a flow rate of 0.15 L / (min·kg) is bubbled through the melt for 5 minutes for purification, and then cast into rods.

[0067] P7. Homogenization and atomization granulation: The rods were homogenized at 860℃ for 2 hours, and then atomized with 4.0MPa argon gas to obtain particulate film-forming aids with a particle size of 50-250μm.

[0068] 2. Preparation of copper-nickel alloy composite plates This embodiment prepares a copper-nickel alloy composite plate, wherein the base layer is Q345R steel, and the cladding layer is prepared according to the above-mentioned component ratio. The specific steps are as follows: S1: Prepare film-forming aid particles according to steps P1 to P7 above.

[0069] S2. Multilayer melting: Melt copper, nickel, iron and manganese matrix in an argon-protected induction furnace. When the temperature reaches 1240℃, add 3.2% of the above-mentioned film-forming aid particles by weight and stir evenly, then cast into a multilayer slab.

[0070] S3. Treatment of base steel plate: Grind the surface of the base Q345R steel plate to a roughness Ra of 1.6μm, and clean and degrease with acetone.

[0071] S4. Assembly and Packaging: The cladding plate is stacked with the base steel plate, sealed and welded around the perimeter, and then vacuumed to make the absolute pressure at the interface reach 1.0 Pa.

[0072] S5. Hot composite rolling: The composite slab is held at 880℃ for 2 hours and then hot rolled. The first pass reduction rate is 20% and the total reduction rate is 55%.

[0073] S6. Diffusion annealing: The steps are exactly the same as in Example 1.

[0074] S7. Surface pre-passivation: The steps are exactly the same as in Example 1.

[0075] Example 3 This embodiment provides a copper-nickel alloy composite plate and its preparation method.

[0076] In this embodiment, the clad copper-nickel alloy comprises the following components by weight percentage: nickel 32.0%, iron 1.5%, manganese 1.0%, chromium 0.65%, tin 0.38%, cerium 0.02%, niobium 0.045%, with the balance being copper and unavoidable impurities. The synergistic coefficient of the trace elements is: The synergy coefficient K = (chromium + niobium) / (tin + cerium) ≈ 1.74.

[0077] 1. Preparation of film-forming aids The film-forming aid used in this embodiment contains the following components by weight percentage: copper 44.1%, nickel 28.0%, chromium 16.0%, tin 9.5%, cerium 1.3%, and niobium 1.1%. The specific preparation steps are as follows: P1. Raw material pretreatment: Place the raw materials copper, nickel, chromium and niobium in a vacuum furnace and degas them at a vacuum of 2 Pa and a temperature of 220°C for 2.0 hours; place cerium and tin in a drying oven for inert gas protection.

[0078] P2. Preparation of copper-cerium master alloy: Pure copper is heated to 1280℃ and melted in a vacuum induction furnace. After switching to argon protection, metallic cerium is added and smelted to produce a copper-cerium primary master alloy ingot containing 20.0% cerium by weight.

[0079] P3. Main Melt Setup: Add raw materials copper and nickel to another smelting furnace and heat to 1380°C for complete melting. Then add chromium and niobium treated in P1 in batches.

[0080] P4. High-temperature melting and stirring: Turn on the electromagnetic stirrer at 1380℃, control the speed at 500rpm, and keep stirring for 50 minutes.

[0081] P5. Adding materials after cooling: Cool the main melt to 1220℃, add raw material tin and copper-cerium primary master alloy obtained in step P2 in sequence, and hold for 6 minutes.

[0082] P6. Purification and Casting: Argon gas with a flow rate of 0.30 L / (min·kg) is bubbled through the melt for 10 minutes for purification, and then cast into rods.

[0083] P7. Homogenization and atomization granulation: The rods were homogenized at 920℃ for 4 hours, and then atomized with 6.0MPa argon gas to obtain particulate film-forming aids with a particle size of 50-250μm.

[0084] 2. Preparation of copper-nickel alloy composite plates This embodiment prepares a copper-nickel alloy composite plate, wherein the base layer is Q345R steel, and the cladding layer is prepared according to the above-mentioned component ratio. The specific steps are as follows: S1: Prepare film-forming aid particles according to steps P1 to P7 above.

[0085] S2. Multilayer melting: The copper, nickel, iron and manganese matrix is ​​melted in an argon-protected induction furnace. When the temperature reaches 1280℃, 4.1% of the above-mentioned film-forming aid particles are added and stirred evenly, and then cast into a multilayer slab.

[0086] S3. Treatment of base steel plate: Grind the surface of the base Q345R steel plate to a roughness Ra of 0.8μm, and clean and degrease with acetone.

[0087] S4. Assembly and Packaging: The cladding plate is stacked with the base steel plate, sealed and welded around the perimeter, and then vacuumed to make the absolute pressure at the interface reach 0.5Pa.

[0088] S5. Hot composite rolling: The laminated slab is held at 940℃ for 2.5 hours and then hot rolled. The first pass reduction rate is 30%, and the total reduction rate is 75%.

[0089] S6. Diffusion annealing: The steps are exactly the same as in Example 1.

[0090] S7. Surface pre-passivation: The steps are exactly the same as in Example 1.

[0091] Comparative Example 1 This comparative example provides a copper-nickel alloy composite plate and its preparation method.

[0092] In this comparative example, the clad copper-nickel alloy is conventional B30 cupronickel, containing the following components by weight percentage: 30.0% nickel, 1.25% iron, 0.75% manganese, with the balance being copper and unavoidable impurities.

[0093] 1. Preparation of film-forming aids This comparative example does not involve the preparation of film-forming aids.

[0094] 2. Preparation of copper-nickel alloy composite plates This comparative example prepares a copper-nickel alloy composite plate, wherein the base layer is Q345R steel, and the cladding layer is prepared according to the above-mentioned component proportions. The specific steps are as follows: S1. This step is not required.

[0095] S2. Multilayer Smelting: Copper, nickel, iron and manganese matrix is ​​smelted in an argon-protected induction furnace, and directly cast when the temperature reaches 1260℃ to produce multilayer slabs.

[0096] S3-S5: The steps are exactly the same as in Example 1.

[0097] S6. Diffusion annealing: Using a conventional single-temperature annealing process, the temperature is maintained at 650℃ for 4 hours.

[0098] S7. Surface pre-passivation: The steps are exactly the same as in Example 1.

[0099] Comparative Example 2 This comparative example provides a copper-nickel alloy composite plate and its preparation method.

[0100] In this comparative example, the clad copper-nickel alloy comprises the following components by weight percentage: nickel 30.0%, iron 1.25%, manganese 0.75%, chromium 0.50%, niobium 0.03%, with the balance being copper and unavoidable impurities. Tin and cerium were not added in this comparative example.

[0101] 1. Preparation of film-forming aids The film-forming aid used in this comparative example contains the following components by weight percentage: copper 61.8%, nickel 25.0%, chromium 12.5%, and niobium 0.7%. The specific preparation steps are as follows: P1. Raw material pretreatment: The steps are exactly the same as in Example 1.

[0102] P2. Preparation of copper-cerium master alloy: This step is not required.

[0103] P3. Main melt construction: The steps are exactly the same as in Example 1.

[0104] P4. High-temperature dissolution and stirring: The steps are exactly the same as in Example 1.

[0105] P5. Adding material after cooling: Cool the main melt to 1200℃ and hold for 8 minutes.

[0106] P6. Purification and casting: The steps are exactly the same as in Example 1.

[0107] P7. Homogenization and atomization granulation: The steps are exactly the same as in Example 1.

[0108] 2. Preparation of copper-nickel alloy composite plates This comparative example prepares a copper-nickel alloy composite plate, wherein the base layer is Q345R steel, and the cladding layer is prepared according to the above-mentioned component proportions. The specific steps are as follows: S1: Prepare film-forming aid particles according to the above steps.

[0109] S2-S7: The steps are exactly the same as in Example 1.

[0110] Comparative Example 3 This comparative example provides a copper-nickel alloy composite plate and its preparation method.

[0111] In this comparative example, the clad copper-nickel alloy contains the following components by weight percentage: 30.0% nickel, 1.25% iron, 0.75% manganese, 0.65% chromium, 0.25% tin, 0.01% cerium, 0.045% niobium, with the balance being copper and unavoidable impurities.

[0112] The synergistic coefficient of trace elements is: The synergy coefficient K = (chromium + niobium) / (tin + cerium) ≈ 2.67.

[0113] 1. Preparation of film-forming aids The film-forming aid used in this comparative example contains the following components by weight percentage: copper 44.4%, nickel 28.0%, chromium 16.2%, tin 8.5%, cerium 1.8%, and niobium 1.1%. The specific preparation steps are as follows: P1-P7: The steps are exactly the same as in Example 1.

[0114] 2. Preparation of copper-nickel alloy composite plates This comparative example prepares a copper-nickel alloy composite plate, wherein the base layer is Q345R steel, and the cladding layer is prepared according to the above-mentioned component proportions. The specific steps are as follows: S1-S7: The steps are exactly the same as in Example 1.

[0115] Comparative Example 4 This comparative example provides a copper-nickel alloy composite plate and its preparation method.

[0116] In this comparative example, the tandem copper-nickel alloy comprises the following components by weight percentage: nickel 30.0%, iron 1.25%, manganese 0.75%, chromium 0.50%, tin 0.40%, cerium 0.04%, niobium 0.03%, with the balance being copper and unavoidable impurities. The synergistic coefficient of the trace elements, K = (chromium + niobium) / (tin + cerium) ≈ 1.20.

[0117] 1. Preparation of film-forming aids This comparative example does not involve the preparation of film-forming aids.

[0118] 2. Preparation of copper-nickel alloy composite plates This comparative example demonstrates the preparation of a copper-nickel alloy composite plate, wherein the base layer is Q345R steel. The specific steps are as follows: S1: This step is not required.

[0119] S2. Multilayer melting: Copper, nickel, iron and manganese matrix is ​​melted in an argon-protected induction furnace. When the temperature reaches 1350℃, untreated elemental chromium, tin, cerium and niobium are directly added to the melt in the proportion of Example 1. After turning on the electromagnetic stirring for 40 minutes, it is cast into a multilayer slab.

[0120] S3-S7: The steps are exactly the same as in Example 1.

[0121] Comparative Example 5 This comparative example provides a copper-nickel alloy composite plate and its preparation method.

[0122] In this comparative example, the tandem copper-nickel alloy comprises the following components by weight percentage: nickel 30.0%, iron 1.25%, manganese 0.75%, chromium 0.50%, tin 0.40%, cerium 0.04%, niobium 0.03%, with the balance being copper and unavoidable impurities. The synergistic coefficient of the trace elements, K = (chromium + niobium) / (tin + cerium) ≈ 1.20.

[0123] 1. Preparation of film-forming aids P1-P7: The steps are exactly the same as in Example 1.

[0124] 2. Preparation of copper-nickel alloy composite plates This comparative example demonstrates the preparation of a copper-nickel alloy composite plate, wherein the base layer is Q345R steel. The specific steps are as follows: S1-S5: The steps are exactly the same as in Example 1.

[0125] S6. Diffusion annealing: The rolled composite plate is annealed at a single temperature and held at 650°C for 6 hours, and then cooled to room temperature in the furnace (without secondary constant temperature cooling treatment at 400°C).

[0126] S7. Surface pre-passivation: The steps are exactly the same as in Example 1.

[0127] To verify the effectiveness of this invention, the test samples were prepared as follows: Q345R steel was selected as the base material and processed into a standard test plate of 100mm×100mm×10mm. Following the complete processing steps of Examples 1, 2, and 3, and Comparative Examples 1, 2, 3, 4, and 5, a 3mm thick copper-nickel alloy cladding was applied to its surface, thus obtaining test samples completely corresponding to each process scheme, sequentially labeled CNCP-01 to CNCP-08. Subsequently, the following performance tests were performed on all grouped samples.

[0128] 1. Seawater erosion corrosion test with sulfur-rich sand. Referring to GB / T 42654-2023 "Test Method for Seawater Erosion Corrosion of Copper and Copper Alloys", a pipe-flow erosion corrosion testing machine was used, in a solution containing 3.5wt% NaCl and 100mg / L... In simulated seawater containing 5 wt% quartz sand, with a flow velocity of 5 m / s and an impact angle of 45°, the material was continuously operated for 720 hours. Quantitative indicators included the weight loss corrosion rate (mm / a) and the maximum pitting depth (μm). A lower corrosion rate indicates a stronger overall resistance to the chemical corrosion of hydrogen sulfide and the physical abrasion of mud and sand. A smaller maximum pitting depth indicates that the passivation film formed by the synergistic effect of trace elements effectively prevents localized electrochemical corrosion, significantly improving the service life and perforation resistance of the composite plate under extremely harsh conditions.

[0129] 2. Critical flow rate test for passivation film peeling. Referring to the assessment method for flow-accelerated corrosion in GB / T 10123-2022 "Corrosion Terminology of Metals and Alloys", in the simulated sulfur-containing seawater medium, the fluid flow rate was gradually increased (from 2 m / s to 12 m / s), and the open-circuit potential (OCP) of the sample was monitored in real time using an electrochemical workstation. The quantitative index is the critical flow rate (…). The critical flow rate (m / s) represents the characteristic flow velocity at which a significant negative shift in potential occurs, indicating physical tearing and peeling of the film. The magnitude of this index directly reflects the degree to which elements such as cerium and niobium enhance the adhesion between the film and the substrate through the "pinning effect" in this invention. A higher critical flow rate means better mechanical stability of the passivation film under high-speed fluid impact, effectively preventing sudden accelerated corrosion of the substrate due to protective film failure.

[0130] 3. Electrochemical Characteristics Testing in Sulfur-Containing Environments. Referring to GB / T 24196-2009 "Guidelines for Electrochemical Testing Methods for Corrosion of Metals and Alloys - Potentiostatic and Potentiodynamic Polarization Measurements", potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) scans were performed on samples in simulated sulfur-containing seawater. Quantitative indicators included pitting breakdown potential (…). mV) and film polarization resistance ( A higher breakdown potential indicates a higher penetration resistance of the passivation film to chloride and sulfide ions, making it less prone to pitting corrosion. A higher polarization resistance value, on the other hand, demonstrates, from a microscopic perspective, that the oxide film structure formed by the chromium-tin composite is increasingly dense. This test, from an electrochemical standpoint, verifies the contribution of the "component synergy effect" in this invention to improving interfacial charge transfer resistance.

[0131] 4. Interfacial Shear Strength Test. In accordance with GB / T 6396-2008 "Test Methods for Mechanical and Technological Properties of Composite Steel Plates", the tensile and shear strength of the interface between the base layer Q345R and the cladding copper-nickel alloy was tested using a universal testing machine. The quantitative index is the interfacial shear strength (…). (MPa). This index is a core parameter for measuring the bonding quality of composite panels. A larger and more stable index value indicates that excellent metallurgical bonding has been achieved between the base layer and the cladding layer through high-vacuum preforming and segmented diffusion annealing processes. This property ensures that the material will not delaminate due to thermal stress or mechanical vibration during subsequent processing and long-term service, thus ensuring the reliability of the overall structural components.

[0132] The test results are summarized in the table below: 1. Analysis of the results of the sulfur-rich sandy seawater erosion corrosion test. Experimental data show that the corrosion rate in Examples 1 to 3 under a high-velocity, sulfur-rich sandy environment was controlled between 0.012 and 0.028 mm / a, a significant difference in magnitude compared to 0.450 mm / a in Comparative Example 1 (previous technology benchmark); simultaneously, the maximum pitting depth decreased from 115.0 μm in Comparative Example 1 to below 22.5 μm. Combined with observation of the surface micromorphology, such as... Figure 1 As shown, the surface substrate of Example 1 remains intact, with only slight scratches along the scouring direction and no obvious pitting, reflecting that chromium and tin elements, with the assistance of film-forming aids, induce the formation of a dense composite oxide film on the alloy surface in this invention. In contrast, as... Figure 2 As shown, Comparative Example 1 exhibits large areas of material spalling and pitting of varying depths on its surface; while Comparative Example 3 (imbalanced composition), due to element ratios outside the range defined by this invention, results in coarse precipitates and the formation of localized electrochemical microcells, leading to a corrosion rate of 0.220 mm / a. This comparative result verifies the critical role of specific component relationships in suppressing localized pitting corrosion and enhancing the stability of the passivation film.

[0133] 2. Analysis of the Critical Flow Rate Test Results for Passivation Film Peeling. Experimental data show that the critical flow rate for each embodiment is above 7.8 m / s, with Example 1 reaching 9.5 m / s, higher than Comparative Example 1's 4.5 m / s. This change reflects the "pinning effect" produced by trace amounts of cerium and niobium in this invention. Cerium aggregates at the interface between the film and the substrate, improving interfacial wettability and enhancing chemical bonding, while niobium provides physical support. Compared to Comparative Example 2, which lacks cerium and tin, its critical flow rate is 5.5 m / s, indicating that improving film adhesion through specific trace elements is a technical approach to solving passivation film peeling failure under high flow rate conditions.

[0134] 3. Analysis of the electrochemical characteristics test results in sulfur-containing environments. The pitting breakdown potentials of Examples 1 to 3 were in the range of 385~420mV, a positive shift compared to 185mV in Comparative Example 1, and the polarization resistance decreased from 1200... Increased to a maximum of 8500 The positive potential shift reflects the inhibitory effect of the passivation film on the cathodic process, increasing the difficulty of pitting corrosion initiation. Data from Comparative Example 4 (without film-forming aids) shows that, with identical chemical composition, due to the absence of gas atomization granulation, its polarization resistance is 4200 Ω. This demonstrates that the process described in this invention has a regulating effect on the construction of high-impedance passivation films.

[0135] 4. Analysis of the interfacial shear strength test results. Regarding mechanical properties, the interfacial shear strength of all embodiments ranged from 235 to 245 MPa. Although this was slightly lower than the 250 MPa of Comparative Example 1, it was still higher than the 200 MPa specified by the national standard. This numerical fluctuation is a performance trade-off: while microalloying elements adjust corrosion resistance, they also affect the atomic diffusion rate at the interface. This invention compensates for this deviation through the segmented diffusion annealing process in step S6. In contrast, Comparative Example 5, which did not undergo segmented annealing, showed weaker corrosion resistance than the embodiments, indicating that the heat treatment process of this invention achieves a balance between the interfacial metallurgical bonding strength and the improvement of the cladding corrosion resistance.

[0136] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A copper-nickel alloy composite plate, characterized in that: It includes a base layer and a cladding layer, the cladding layer comprising the following components by weight percentage: Nickel 28.0%–32.0%, iron 1.0%–1.5%, manganese 0.5%–1.0%, chromium 0.35%–0.65%, tin 0.25%–0.55%, cerium 0.02%–0.06%, niobium 0.015%–0.045%, with the balance being copper and unavoidable impurities.

2. The copper-nickel alloy composite plate according to claim 1, characterized in that: The weight percentages of each component in the composite layer satisfy the following relationship: 0.8 ≤ (chromium + niobium) / (tin + cerium) ≤ 1.8; the chromium, tin, cerium, and niobium in the composite layer are introduced by adding a film-forming aid, which comprises the following components by weight percentage: Copper 45.0%–55.0%, Nickel 22.0%–28.0%, Chromium 10.0%–15.0%, Tin 8.0%–12.0%, Cerium 1.0%–2.0%, Niobium 0.5%–1.0%.

3. A method for preparing a copper-nickel alloy composite plate, characterized in that, Includes the following steps: S1. Preparation of film-forming aids; S2. Melt copper, nickel, iron and manganese matrix under a protective atmosphere, add the film-forming aid, and cast to obtain a multilayer slab. S3. Remove oxide scale and clean and degrease the base steel plate; S4. The composite slab blank is stacked with the base steel plate, sealed and welded, and then vacuumed to obtain the composite slab blank. S5. The laminated slab is insulated and then subjected to hot rolling composite treatment; S6. Perform diffusion annealing on the hot-rolled composite plate. S7. Perform surface pre-passivation treatment on the plate after diffusion annealing.

4. The preparation method according to claim 3, characterized in that: In step S1, the preparation of the film-forming aid includes the following sub-steps: P1. Perform heat preservation and degassing treatment on raw materials copper, nickel, chromium, and niobium; P2. Preparation of copper-cerium master alloy; P3. Melt the raw materials copper and nickel to obtain the main melt, and add the treated chromium and niobium in batches; P4. Heat and maintain the temperature of the main melt while stirring; P5. Cool the main melt, add raw tin and the copper-cerium master alloy obtained in step P2 in sequence, and keep it at the temperature. P6. Introduce protective gas to bubble and purify the melt after heat preservation in step P5, and then cast it into shape. P7. The product after casting is homogenized and then granulated by gas atomization to obtain the granular film-forming aid.

5. The preparation method according to claim 4, characterized in that: In the sub-steps P1, P2, and P3: In P1, the raw materials copper, nickel, chromium, and niobium are degassed for 1 to 2 hours under a vacuum of no more than 5 Pa and a temperature of 180 to 220°C. In P2, copper is melted in a vacuum induction furnace at 1230-1280°C, and cerium is added after switching to argon protection to obtain a copper-cerium primary master alloy containing 20% ​​by weight of cerium. In step P3, copper and nickel are melted at 1320–1380°C in another smelting furnace, and chromium and niobium treated in step P1 are added in batches.

6. The preparation method according to claim 4, characterized in that: In the sub-steps P4, P5, P6, and P7: In P4, electromagnetic stirring is performed at 1320–1380°C, with a rotation speed of 300–500 rpm and a holding time of 30–50 min. In P5, the main melt is cooled to 1180-1230°C, and tin and the copper-cerium primary master alloy are added sequentially, with a holding time of no more than 10 minutes. In P6, argon gas with a flow rate of 0.15 to 0.30 L / (min·kg) is bubbled through for purification for 5 to 10 minutes, and then cast into a rod; In P7, the rod is homogenized at 860–920°C for 2–4 hours, and then granulated by gas atomization using argon gas at a pressure of 4.0–6.0 MPa to obtain particles with a particle size of 50–250 μm.

7. The preparation method according to claim 3, characterized in that: In steps S2, S3, and S4: In step S2, a copper, nickel, iron, and manganese matrix is ​​smelted under a protective atmosphere, and 3.2% to 4.5% of the film-forming aid is added by weight, followed by casting at 1240 to 1280°C. In step S3, the surface of the base steel plate is ground until the roughness Ra is no greater than 1.6 μm; In step S4, the cladding slab is stacked with the steel base layer, sealed and welded around the perimeter, and then evacuated to an absolute pressure not exceeding 1.0 Pa.

8. The preparation method according to claim 3, characterized in that: In step S5, hot composite rolling is performed after holding at 880-940℃, with a first pass reduction rate of not less than 20% and a total reduction rate of 55%-75%.

9. The preparation method according to claim 3, characterized in that: In step S6, segmented diffusion annealing is performed, including holding at 650°C for 2 hours and then holding at 400°C for 4 hours.

10. The preparation method according to claim 3, characterized in that: In step S7, the board is immersed in an oxygenated saline solution.

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