Copper-aluminum composite copper strip and short-process processing method thereof

Abstract

The application discloses a copper-aluminum composite copper strip and a short-process processing method thereof, and belongs to the technical field of copper alloy strip preparation. The copper-aluminum composite copper strip is prepared through the procedures of horizontal continuous casting, face milling, heat treatment, cold rolling, primary cleaning, finished product annealing and finished product cleaning. The copper-aluminum composite copper strip is prepared by adopting the horizontal continuous casting and heat treatment processes, so that the red copper casting blank with refined grains is obtained, the hot rolling process is omitted, the processing process is simplified, the processing time is reduced, and the production efficiency is improved; the annealing-cleaning collaborative high surface treatment technology is adopted, so that the quality and efficiency of surface treatment are improved, and the copper-aluminum composite copper strip exhibits extraordinary advantages in enhancing the surface smoothness of the material; trace aluminum is added to the copper-aluminum composite copper strip for doping, so that the bonding force of the copper strip and the aluminum strip can be improved; and the annealing process realizes unprecedented high-precision control over the grain size.

Description

Technical Field

[0001] This invention belongs to the field of copper alloy strip preparation technology, specifically relating to a copper strip for copper-aluminum composite and its short-process processing method. Background Technology

[0002] Copper / aluminum bimetallic composite strip is a composite material prepared from copper and aluminum through rolling, compounding, and heat treatment. Compared with pure copper strip, copper-aluminum composite strip retains the good electrical and thermal conductivity of copper strip while leveraging the lightweight, easy-to-process, and corrosion-resistant properties of aluminum strip. It also offers high cost-effectiveness and is widely used in power, new energy vehicles, and construction industries. Among various copper-aluminum compounding methods, the rolling compounding method, with its low cost, high processing efficiency, and simple operation, has become one of the mainstream production methods.

[0003] Rolling composite processing is a commonly used method for producing copper-aluminum composite strips. However, its production faces several challenges: firstly, ensuring sufficient bonding strength between the copper and aluminum strips; and secondly, addressing the issue of uneven copper-aluminum thickness ratios due to inhomogeneous plastic deformation of the copper and aluminum strips during the rolling process. Existing technologies also include research on copper strips for copper-aluminum composites. For example, Chinese patent CN117259463 A discloses a copper strip for copper-aluminum composites, its preparation method, and its application. This method involves preparing copper alloy raw materials, smelting, semi-continuous casting, hot rolling, milling, rough rolling, primary cleaning, precision rolling, secondary cleaning, final annealing, and final cleaning. The process involves controlling the gloss and crystal structure of the strip surface to eliminate stress during processing, allowing the copper strip to effectively combine with aluminum. However, this patented method for preparing copper strips for copper-aluminum composites involves numerous steps, a complex process, and is time-consuming. Summary of the Invention

[0004] To address the problems of numerous and time-consuming processes and poor copper-aluminum composite bonding in existing copper-aluminum composite strip manufacturing technologies, this invention provides a copper-aluminum composite strip and its short-process manufacturing method. By employing aluminum element homogenization doping, horizontal continuous casting, heat treatment, cold rolling, annealing, and high surface treatment technologies, the manufacturing process is simplified. This achieves efficient and low-cost production of copper-aluminum composite strips while ensuring high surface cleanliness, strong copper-aluminum composite bonding, and uniform and stable mechanical properties.

[0005] This invention is achieved through the following technical solution: A short-process method for processing copper strip for copper-aluminum composite applications includes the following steps: (1) Horizontal continuous casting: The raw materials are added to the horizontal continuous casting furnace for melting. The melting temperature is controlled at 1100-1160℃. The copper liquid is transferred to the holding furnace. The holding furnace temperature is controlled at 1160~1200℃. The copper billet is obtained through the graphite crystallizer. (2) Milling: The cast billet after heat treatment in step (2) is milled to remove the oxide scale on the surface; (3) Heat treatment: The billet in step (1) is heat treated at 550~680℃; (4) Cold rolling: The milled billet is cold rolled with a cold rolling rate of 70-90% and a roll roughness Ra of 0.2-0.4μm; (5) First cleaning: The strip after cold rolling in step (4) is cleaned once to remove residual emulsion from the surface. (6) Finished product annealing: The strip after cleaning in step (5) is annealed at a temperature of 380~500℃ for 3~8h. (7) Cleaning of finished products.

[0006] Further, the raw materials in step (1) are electrolytic copper and electrolytic aluminum; the mass percentage composition of each component in the billet is as follows: P: 0.001~0.005wt%, Fe: 0.001~0.005wt%, Al: 0.001~0.01wt%, impurities less than 0.01%, and the balance is Cu.

[0007] Furthermore, the heat treatment time in step (3) is 2~3h, and the heating rate is 80~100℃ / h.

[0008] Furthermore, in step (2), the thickness of the upper and lower surfaces milled is 0.6~1.0mm, and the thickness of the side single-sided milling is 0.8~1.5mm.

[0009] Furthermore, in step (5) the first cleaning and in step (7) the finished product cleaning, nylon filaments with a mesh size of 600~1000 are used for cleaning, the cleaning speed is 20-40m / min, and the reduction amount is 18~30A.

[0010] Furthermore, the coiling tension of the first cleaning in step (5) and the finished product cleaning in step (7) is 8000~12000KN. The smaller coiling tension ensures that the strip does not stick after annealing in the bell-type furnace.

[0011] Furthermore, the atmosphere for annealing the finished product in step (6) is a nitrogen-hydrogen mixture containing 60-90% hydrogen. The high hydrogen content atmosphere is used to ensure the reduction of the oxide film on the strip surface by hydrogen. This allows for control of the surface gloss of the strip during subsequent cleaning of the finished product.

[0012] Furthermore, the heating rate for annealing the finished product in step (6) is 50~100℃ / h.

[0013] In this invention, the copper strip for copper-aluminum composite is obtained by the processing method described above.

[0014] Furthermore, the copper strip used in the copper-aluminum composite process has a grain size of 10~18μm, a Vickers hardness of 65-75, a surface gloss level of less than 350GU parallel to the rolling direction, and a surface gloss level of less than 180GU perpendicular to the rolling direction.

[0015] Beneficial effects (1) Compared with the prior art, the present invention uses horizontal continuous casting and heat treatment (heat treatment after milling) process to prepare a copper billet with refined grains. Compared with the semi-continuous casting process, the hot rolling process is omitted, the processing steps are simplified, the number of hot rolling passes and cleaning are reduced, the processing time is effectively reduced, and the production efficiency is improved. (2) This invention employs a high-efficiency surface treatment technology that combines annealing and cleaning, significantly improving the quality and efficiency of surface treatment. Furthermore, its unique synergistic mechanism demonstrates exceptional advantages in enhancing the surface finish of materials, enabling the prepared copper strips to be better applied in the copper-aluminum composite field. (3) The present invention improves the bonding force between copper strip and aluminum strip by adding a trace amount of aluminum to copper strip for copper-aluminum composite; (4) The annealing process of the present invention, such as heating temperature, holding time and heating rate, achieves unprecedented high-precision control of grain size. Detailed Implementation

[0016] The present invention will be described in detail below through implementation examples. However, it should be noted that these implementation examples are not intended to limit the present invention. Equivalent changes or substitutions in function, method, or structure made by those skilled in the art based on these implementation examples are all within the protection scope of the present invention.

[0017] Example 1 (1) Horizontal continuous casting: A certain proportion of electrolytic copper and electrolytic aluminum are added to the horizontal continuous casting melting furnace for melting. The melting temperature is controlled at 1140℃. The copper liquid is transferred to the holding furnace, and the holding furnace temperature is controlled at 1180℃. A copper billet is obtained through a graphite crystallizer. The billet composition by mass percentage is: Fe: 0.002%, P: 0.0013, Al: 0.0025wt%, total impurities < 0.1%, balance is copper, and the billet thickness is 16.8mm. (2) Milling: The casting in step (1) is milled with a milling amount of 0.6 mm per side and a side milling thickness of 1.2 mm to remove the oxide scale on the surface. (3) Heat treatment: The milled billet is heat treated at 600℃, the heating rate is 100℃ / h, and the heat treatment time is 2.5h. (4) Cold rolling: The heat-treated billet is cold rolled with a cold rolling rate of 82% and a roll roughness Ra of 0.26μm to obtain a copper strip with a thickness of 2.8mm; (5) First cleaning: The strip after cold rolling in step (4) is cleaned once. The cleaning is done with a nylon filament brush with a mesh size of 800, a cleaning speed of 24m / min, a brush pressing current of 16A, and a curling tension of 10000KN to remove residual emulsion from the surface. (6) Finished product annealing: The strip cleaned in step (5) is annealed in a bell furnace. The annealing heating rate is 80℃ / h, the annealing temperature is 470℃, the annealing time is 5h, and the annealing atmosphere is a nitrogen-hydrogen mixture containing 80% hydrogen. (7) Finished product cleaning: The cleaning is done with a nylon filament brush with a mesh size of 800, a cleaning speed of 24m / min, a brush pressing current of 16A, and a curling tension of 10000KN to obtain copper strip for copper-aluminum composite.

[0018] Example 2 (1) Horizontal continuous casting: A certain proportion of electrolytic copper and electrolytic aluminum are added to the horizontal continuous casting melting furnace for melting. The melting temperature is controlled at 1140℃. The copper liquid is transferred to the holding furnace, and the holding furnace temperature is controlled at 1180℃. A copper billet is obtained through a graphite crystallizer. The billet composition by mass percentage is: Fe: 0.002%, P: 0.0013, Al: 0.0025wt%, total impurities < 0.1%, balance is copper, and the billet thickness is 16.8mm. (2) Milling: The casting in step (1) is milled with a milling amount of 0.6 mm per side and a side milling thickness of 1.2 mm to remove the oxide scale on the surface. (3) Heat treatment: The milled billet is heat treated at 650℃, the heating rate is 80℃ / h, and the heat treatment time is 3h. (4) Cold rolling: The heat-treated billet is cold rolled with a cold rolling rate of 82% and a roll roughness Ra of 0.26μm to obtain a copper strip with a thickness of 2.8mm; (5) First cleaning: The strip after cold rolling in step (4) is cleaned once. The cleaning is done with a nylon filament brush with a mesh size of 800, a cleaning speed of 24m / min, a brush pressing current of 16A, and a curling tension of 10000KN to remove residual emulsion from the surface. (6) Finished product annealing: The strip cleaned in step (5) is annealed in a bell furnace. The annealing heating rate is 100℃ / h, the annealing temperature is 450℃, the annealing time is 4h, and the annealing atmosphere is a nitrogen-hydrogen mixture containing 80% hydrogen. (7) Finished product cleaning: The cleaning is done with a nylon filament brush with a mesh size of 800, a cleaning speed of 24m / min, a brush pressing current of 16A, and a curling tension of 10000KN to obtain copper strip for copper-aluminum composite.

[0019] Example 3 (1) Horizontal continuous casting: A certain proportion of electrolytic copper and electrolytic aluminum are added to the horizontal continuous casting melting furnace for melting. The melting temperature is controlled at 1140℃. The copper liquid is transferred to the holding furnace, and the holding furnace temperature is controlled at 1180℃. A copper billet is obtained through a graphite crystallizer. The billet composition by mass percentage is: Fe: 0.002%, P: 0.0013, Al: 0.0025wt%, total impurities < 0.1%, balance is copper, and the billet thickness is 16.8mm. (2) Milling: The casting in step (1) is milled with a milling amount of 0.6 mm per side and a side milling thickness of 1.2 mm to remove the oxide scale on the surface. (3) Heat treatment: The milled billet is heat treated at 580℃, the heating rate is 100℃ / h, and the heat treatment time is 2.5h. (4) Cold rolling: The heat-treated billet is cold rolled with a cold rolling rate of 82% and a roll roughness Ra of 0.26μm to obtain a copper strip with a thickness of 2.8mm; (5) First cleaning: The strip after cold rolling in step (4) is cleaned once. The cleaning is done with a nylon filament brush with a mesh size of 800, a cleaning speed of 24m / min, a brush pressing current of 16A, and a curling tension of 10000KN to remove residual emulsion from the surface. (6) Finished product annealing: The strip cleaned in step (5) is annealed in a bell furnace. The annealing heating rate is 60℃ / h, the annealing temperature is 400℃, the annealing time is 6h, and the annealing atmosphere is a nitrogen-hydrogen mixture containing 80% hydrogen. (7) Finished product cleaning: The cleaning is done with a nylon filament brush with a mesh size of 800, a cleaning speed of 24m / min, a brush pressing current of 16A, and a curling tension of 10000KN to obtain copper strip for copper-aluminum composite.

[0020] Comparative Example 1 (1) Semi-continuous casting: A certain proportion of electrolytic copper and electrolytic aluminum are added to a horizontal continuous casting furnace for melting and then processed into ingots by semi-continuous casting; the composition of the ingot by mass percentage is: Fe: 0.002%, P: 0.0013, Al: 0.0025wt%, total impurities < 0.1%, and the balance is copper; (2) Hot rolling: The ingot in step (1) is heated in the walking beam furnace for 4.5 hours and then taken out of the furnace. The ingot at 760°C is hot rolled and a 16.8 mm thick hot rolled billet is obtained after 8 passes of hot rolling. (3) Milling: The cast billet after heat treatment in step (2) is milled with a milling amount of 0.6 mm on one side and a side milling thickness of 1.2 mm to remove the oxide scale on the surface. (4) Cold rolling: The milled billet is cold rolled with a cold rolling rate of 82% and a roll roughness Ra of 0.26μm to obtain a copper strip with a thickness of 2.8mm; (5) First cleaning: The strip after cold rolling in step (4) is cleaned once. The cleaning is done with a nylon filament brush with a mesh size of 800, a cleaning speed of 24m / min, a brush pressing current of 16A, and a curling tension of 10000KN to remove residual emulsion from the surface. (6) Finished product annealing: The strip cleaned in step (5) is annealed in a bell furnace. The annealing heating rate is 80℃ / h, the annealing temperature is 400℃, the annealing time is 5h, and the annealing atmosphere is a nitrogen-hydrogen mixture containing 80% hydrogen. (7) Finished product cleaning: The cleaning is done with a nylon filament brush with a mesh size of 800, a cleaning speed of 24m / min, a brush pressing current of 16A, and a curling tension of 10000KN to obtain copper strip for copper-aluminum composite.

[0021] Comparative Example 2 Compared with Example 1, in Comparative Example 2, the annealing of the finished product in step (6) was set to 570°C and the annealing time was 5h. The remaining operations were the same as in Example 1, and a 2.8mm copper strip for copper-aluminum composite was obtained.

[0022] Comparative Example 3 Compared with Example 1, Comparative Example 3 does not perform step (3) processing. After milling the surface of the horizontal continuous casting billet, it is directly cold rolled. The remaining operations are the same as in Example 1, and a 2.8mm copper strip for copper-aluminum composite is obtained.

[0023] Comparative Example 4 Compared with Example 1, Comparative Example 4 step (1) does not dop with trace aluminum elements (i.e., no electrolytic aluminum is added), and the composition of the billet by mass percentage is: Fe: 0.002%, P: 0.0013, Al: 0.0025wt%, total impurities < 0.1%, and the balance is copper; the rest of the operation is the same as in Example 1, and a 2.8mm copper-aluminum composite copper strip is obtained.

[0024] Performance testing: The grain size, hardness and surface gloss of the 2.8 mm copper-aluminum composite copper strips prepared in Examples 1-3 and Comparative Examples 1-4 were tested. The results are shown in Table 1 below. As can be seen from Table 1, the cleanliness and mechanical properties of the copper-aluminum composite copper strips prepared by the present invention are controllable, and the grains are refined. Through the micro-uniform doping of aluminum, it can be better applied in the field of copper-aluminum composite materials.

[0025] Table 1 Performance Test Table for Copper Strips Used in Copper-Aluminum Composites .

Claims

1. A short-process processing method for copper strip used in copper-aluminum composite applications, characterized in that, Includes the following steps: (1) Horizontal continuous casting: The raw materials are added to the horizontal continuous casting furnace for melting. The melting temperature is controlled at 1100-1160℃. The copper liquid is transferred to the holding furnace, and the holding furnace temperature is controlled at 1160~1200℃. A copper billet is obtained through a graphite crystallizer. The raw materials are electrolytic copper and electrolytic aluminum. The mass percentage composition of each component in the billet is as follows: P: 0.001~0.005wt%, Fe: 0.001~0.005wt%, Al: 0.001~0.01wt%, impurities less than 0.01%, and the balance is Cu. (2) Milling: The cast billet in step (1) is milled to remove the oxide scale on the surface; (3) Heat treatment: The milled billet is heat treated at 550~680℃ for 2~3h, and the heating rate is 80~100℃ / h. (4) Cold rolling: The milled billet is cold rolled with a cold rolling rate of 70-90% and a roll roughness Ra of 0.2-0.4μm; (5) First cleaning: The strip after cold rolling in step (4) is cleaned once to remove residual emulsion from the surface; (6) Finished product annealing: The strip after cleaning in step (5) is annealed at a temperature of 380~500℃ for 3~8h. (7) Cleaning of finished products.

2. The short-process processing method for copper strip for copper-aluminum composite as described in claim 1, characterized in that, In step (2), the thickness of the upper and lower surfaces milled is 0.6~1.0mm, and the thickness of the side single-sided milling is 0.8~1.5mm.

3. The short-process processing method for copper strip for copper-aluminum composite as described in claim 1, characterized in that, Step (5) First cleaning and step (7) Finished product cleaning use nylon filaments with a mesh size of 600~1000 for cleaning, with a cleaning speed of 20-40m / min and a reduction of 18~30A.

4. The short-process processing method for copper strip for copper-aluminum composite as described in claim 1, characterized in that, Step (5) First cleaning and step (7) Finished product cleaning. The coiling tension is 8000~12000KN. The smaller coiling tension ensures that the strip does not stick after annealing in the bell furnace.

5. The short-process processing method for copper strip for copper-aluminum composite as described in claim 1, characterized in that, Step (6) The atmosphere for annealing the finished product is a nitrogen-hydrogen mixture containing 60-90% hydrogen.

6. The short-process processing method for copper strip for copper-aluminum composite as described in claim 1, characterized in that, Step (6) The heating rate for annealing the finished product is 50~100℃ / h.

7. A copper strip for copper-aluminum composite processing obtained by the processing method according to any one of claims 1 to 6.

8. The copper strip for copper-aluminum composite as described in claim 7, characterized in that, The copper strip used in the copper-aluminum composite process has a grain size of 10~18μm, a Vickers hardness of 65-75, a surface gloss of less than 350GU parallel to the rolling direction, and a surface gloss of less than 180GU perpendicular to the rolling direction.