Rolling method of copper-titanium alloy foil
By optimizing the rolling process of copper-titanium alloy foil and using the cross-speed rolling method, the problem of low conductivity of copper-titanium foil is solved, and the conductivity and elongation are improved, while the strength and plasticity of the material are improved.
Patent Information
- Application Number
- CN202510399387.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-01
- Publication Date
- 2025-06-13
AI Technical Summary
The existing copper-titanium foil alloy has low conductivity, and the existing process flow is complex and has poor adaptability.
By optimizing the rolling process parameters, using the cross-speed rolling method, the anovelocity ratio of the upper and lower working rollers is controlled to be 1.1-1.25, and the rolling directions of the adjacent two passages are opposite, and the down pressure rate of each passage is controlled to be 0.4%-0.9%, and rolled 50-70 times to obtain a thin copper-titanium alloy strip with a grain size distribution curve of a bimodal structure.
It effectively improves the conductivity and elongation of copper-titanium alloy foil, reduces the phenomenon of stress concentration, and improves the strength and plasticity of the material.
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Figure CN120133308A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of metal material rolling, and more specifically, to a rolling method for copper-titanium alloy foils. Background Art
[0002] With the rapid development of the fields of micro-forming and micro-fabrication, the demand for metal foils by people is increasing day by day. Among them, copper and its alloys are often made into new energy lithium battery copper foils, electromagnetic flat wires, high-voltage wire harnesses, etc. due to their excellent electrical conductivity. Commonly used copper alloys mainly include copper-beryllium alloys, copper-silver alloys, copper-nickel alloys, copper-tungsten alloys, and copper-phosphorus alloys. Among many high-strength copper alloys, copper-beryllium alloys have comprehensive excellent mechanical properties and relatively high electrical conductivity, and thus are widely used in the manufacture of connectors and sensitive components. However, because beryllium elements are less abundant and more expensive in nature, they have poor stress relaxation resistance and low electrical conductivity stability at high temperatures, and harmful substances will be generated during their production process, causing negative impacts on the environment. Therefore, it is of great practical significance to actively develop and find materials to replace copper-beryllium alloys.
[0003] Research has found that as a typical precipitation-strengthened alloy, copper-titanium alloy (titanium content is 1% - 6%) has mechanical properties no less than those of copper-beryllium alloys due to its excellent strength, hardness, elasticity and heat resistance. At the same time, titanium resources are relatively abundant, and no harmful substances are generated during its production process. Therefore, copper-titanium alloy is expected to become a substitute material for copper-beryllium alloys. However, the existing copper-titanium foil alloy still has a relatively low electrical conductivity.
[0004] After retrieval, a Chinese patent with the application number 2021113656381 discloses a copper alloy foil for 5G terminal device interfaces and its preparation method. The used copper alloy foil uses specific contents of copper, titanium, magnesium, cerium, zirconium and phosphorus elements as billets. The billets are subjected to vacuum degassing melting, semi-continuous casting, walking beam furnace heating, hot rolling, four-sided milling, rough rolling for blooming, trimming and online solution thick washing line grinding in a cushion furnace, medium rolling, finish rolling (20-high rolling), degreasing and cleaning, aging in a bell furnace, and degreasing and cleaning, and the copper alloy foil is obtained through finished product slitting. Although this application can improve the tensile strength, yield strength and electrical conductivity of the copper alloy foil, it needs to limit the composition of the copper alloy foil, and its process flow is relatively complex and its adaptability is not strong. Summary of the Invention
[0005] 1. Technical Problems to be Solved
[0006] Aiming at the technical problem that the existing copper-titanium foil alloy has a relatively low electrical conductivity, the present invention provides a rolling method for copper-titanium alloy foils. Through the optimized design of the process parameters during the rolling process, a copper-titanium alloy thin strip with a bimodal structure of the grain size distribution curve is obtained, thereby effectively improving its electrical conductivity.
[0007] 2. Technical Solutions Adopted
[0008] To achieve the above object, the technical solution provided by the present invention is as follows:
[0009] A rolling method for a copper-titanium alloy foil of the present invention includes the following steps: cold-rolling the copper-titanium alloy foil, the differential speed ratio of the upper and lower working rolls during the rolling process is 1.1 - 1.25, and the rolling directions of adjacent passes are opposite; the reduction per pass is 0.4% - 0.9%, the number of rolling passes is 50 - 70 times, and the grain size distribution curve of the copper-titanium alloy thin strip obtained by rolling is a bimodal structure, and the bimodal peaks are 4 - 6 μm and 19 - 21 μm respectively.
[0010] By cross-async rolling the copper-titanium alloy foil, the overall grains are refined; the fine grains increase the grain boundary area, and the grain boundary, as an obstacle to dislocations, can effectively hinder the movement of dislocations, thereby improving the strength of the material. Moreover, the refined grains after rolling make the plastic deformation generated by rolling more evenly distributed in more grains, reducing the phenomenon of stress concentration, thereby improving the plasticity of the material. More importantly, in the present invention, the speed of the upper working roll is greater than that of the lower working roll, and the rolling directions of adjacent two passes are opposite; thus, during the rolling process of adjacent two passes, the copper-titanium alloy foil is respectively subjected to a shear force in a single direction and a shear force in the direction opposite to the previous pass, that is, the shear forces it receives are symmetrically distributed. Further, after 50 - 70 passes of rolling, and controlling the reduction per pass to be 0.4% - 0.9%, a copper-titanium alloy thin strip with an internal grain size distribution of a bimodal structure is obtained, and the bimodal peaks are 4 - 6 μm and 19 - 21 μm respectively. Through the transition between small-sized grains and large-sized grains, the scattering of charge carriers can be effectively reduced, thereby improving the conductivity.
[0011] Further, the proportion of grains with a particle size between 4 - 6 μm in the copper-titanium alloy thin strip is more than 40%, and the proportion of grains with a particle size between 19 - 21 μm is more than 50%.
[0012] Further, the differential speed ratio of the upper and lower working rolls during the rolling process is 1.2; and / or the number of rolling passes is any even number between 50 - 70, and the reduction per 2 passes is 0.8% - 1.4%.
[0013] Further, the rolling force during the rolling process is 1.8 - 2.2 t; and / or the front tension and the rear tension during the rolling process are the same, and both are 600 N.
[0014] By balancing the front tension, i.e., the inlet tension, and the back tension, i.e., the outlet tension, the "running deviation" of the material can be inhibited and edge cracking can be reduced. For example, when the tension fluctuation ≤ 5%, the thickness tolerance can be controlled within ±0.5%. Moreover, appropriate tension can prevent the rolled piece from slipping during the rolling process, ensuring the stability and continuity of the rolling process. In addition, the rolling tension forms a superimposed tensile stress, reducing the rolling force requirement, while inhibiting the lateral deformation and improving the texture uniformity. By controlling the ratio of the front and back tensions, it is beneficial to reduce surface wrinkles and scratches.
[0015] Furthermore, during the rolling process, there is lubrication at the rolling inlet and no lubrication at the rolling outlet, and the work rolls are lubricated while the backup rolls are not lubricated. During the rolling process, lubricants, such as mineral oil + extreme pressure additives, can reduce the friction coefficient μ from 0.15 to 0.05, reducing the rolling force by 10 - 30%. Moreover, the lubricant takes away the deformation heat, avoiding excessive local temperature rise, and thus preventing excessive dynamic recrystallization, i.e., grain coarsening. In addition, an adsorption film is formed to reduce the adhesion between the roll and the rolled foil, preventing surface oxidation or microcracks.
[0016] Furthermore, the copper - titanium alloy foil is cold - rolled. Specifically, the copper - titanium alloy foil is rolled at room temperature without intermediate annealing treatment during the rolling process.
[0017] Furthermore, the initial thickness of the copper - titanium alloy foil is between 0.1 mm and 0.2 mm.
[0018] Furthermore, the copper - titanium alloy foil comprises the following components by mass ratio: 1 - 6% Ti, and the sum of the contents of copper and titanium elements is not less than 99.5%.
[0019] Furthermore, for a titanium content of 3.25%, the conductivity of the copper - titanium alloy strip obtained by rolling reaches 15.17%, and / or its elongation reaches 1.29%.
[0020] Adopting the technical solution provided by the present invention, compared with the prior art, it has the following beneficial effects:
[0021] (1) By controlling the differential speed ratio of the upper and lower work rolls and setting the rolling directions of adjacent two passes to be opposite in the present invention; thus, the copper - titanium alloy foil is respectively subjected to a single - direction shear force and a shear force in the opposite direction to the previous pass, that is, the shear forces it receives are symmetrically distributed. Further, through multi - pass rolling and controlling the reduction rate of each pass to be 0.4% - 0.9%, a copper - titanium alloy strip with a bimodal structure of internal grain size distribution is obtained, and the bimodal peaks are 4 - 6 μm and 19 - 21 μm respectively. Through the transition between small - sized grains and large - sized grains, the scattering of charge carriers can be effectively slowed down, thereby improving the conductivity.
[0022] (2) By subjecting the copper-titanium alloy foil to cross asynchronous rolling, the overall grain size is refined; the fine grains increase the grain boundary area, and the grain boundaries, as obstacles to dislocations, can effectively hinder the movement of dislocations, thereby improving the strength of the material. Moreover, the refined grains after rolling make the plastic deformation generated by rolling more evenly distributed in more grains, reducing the phenomenon of stress concentration, thereby improving the plasticity of the material. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 FIG. is a schematic diagram of the single-pass and double-pass rolling processes in Example 1 of the present invention.
[0024] Figure 2 FIG. is the inverse pole figure (IPF) of the grain distribution in the cross-section along the thickness direction of the copper-titanium alloy thin strip obtained in Example 1 of the present invention.
[0025] Figure 3 FIG. is a statistical chart of the grain size distribution of the copper-titanium alloy thin strip obtained in Example 1 of the present invention.
[0026] Figure 4 FIG. is a comparison chart of the properties of the copper-titanium alloy foils rolled in Example 1 and Comparative Examples 1 and 2 of the present invention. DETAILED DESCRIPTION OF THE INVENTION
[0027] To further understand the content of the present invention, the present invention will be described in detail in combination with the embodiments.
[0028] The following embodiments are adapted to improve the conductivity and elongation of copper-titanium alloy foils through a specific rolling process, especially applicable to copper-titanium alloys with a titanium content of 1-6%. The conductivity and elongation can be improved through this rolling method. The following embodiments and comparative examples are experimentally carried out with a titanium alloy content of 3.25%, and should not be construed as a limitation on the titanium content in the copper-titanium alloys applicable to the present invention.
[0029] Example 1
[0030] This embodiment provides a rolling method for copper-titanium alloy foils. The copper-titanium alloy foils include the following specific components: the mass ratio of titanium is 3.25%, and the sum of the mass ratios of copper and titanium elements is 99.5%. The rest are inevitable impurities; its initial dimensions are a width of 30 mm and a thickness of 0.1 mm. The copper-titanium alloy foils used have a smooth surface and good flatness. The specific rolling steps are as follows:
[0031] Reference Figure 1As shown, during the rolling process, the speed of the upper working roll is greater than that of the lower working roll, and the differential speed ratio between the two is 1.2. The rolling directions of adjacent passes are opposite. Under the conditions of room temperature and without intermediate annealing, a total of 60 passes are rolled, and the reduction per pass is controlled at 0.5% on average. These 60 passes are divided into 4 stages, and the rolling forces in the four stages are 1.8t, 2t, 2.2t, and 2.1t respectively. The front and rear rolling tensions are equal, both being 600N. This rolling force is set based on trying to control the reduction per pass to be the same.
[0032] The above rolling process uses a 3M-IV asynchronous rolling mill. During the rolling process, rolling inlet lubrication is adopted, and there is no lubrication at the rolling outlet. Moreover, only the upper and lower working rolls are lubricated, and the upper and lower backup rolls are not lubricated.
[0033] It also includes cleaning the surface oil stain of the rolled copper-titanium alloy thin strip and then packaging it and sending it to the warehouse.
[0034] The thickness of the copper-titanium alloy thin strip obtained by rolling in this embodiment is about 0.070mm; for more detailed rolling process parameters during the rolling process, please refer to Table 1.
[0035] The inverse pole figure of the grain distribution of the copper-titanium alloy thin strip obtained in this embodiment is as Figure 2 shown, and the statistical chart of the grain size distribution is as Figure 3 shown. From Figure 2 , Figure 3 it can be seen that the fine grain size is about 5μm, and its quantity proportion is about 42%; the coarse grain size is about 20μm, and its quantity proportion is about 51%.
[0036] Table 1 Rolling process parameters of copper-titanium alloy cross asynchronous in Example 1
[0037]
[0038]
[0039] Comparative Example 1
[0040] This comparative example provides a rolling method for copper-titanium alloy foil. The difference between this comparative example and Example 1 lies in that the reduction per pass and the number of rolling passes are different during the rolling process. Specifically, the rolling force is divided into two stages, which are 4t and 3t respectively, and a total of 4 passes are rolled. For the detailed pressing process parameters, please refer to Table 2. The rest of the preparation processes are basically the same as those in Example 1.
[0041] Table 2 Rolling process parameters of copper-titanium alloy cross asynchronous in Comparative Example 1
[0042] Stage Pass Exit thickness (μm) Rolling force (t) 1 1 98 4 1 2 84 4 2 3 76 3 2 4 70 3
[0043] Comparative Example 2
[0044] This comparative example provides a rolling method for a copper-titanium alloy foil. The difference between this comparative example and Example 1 lies in that the reduction rate and the number of rolling passes are different during the rolling process. Specifically, there is only one stage of rolling force, which is 5t, and a total of 2 rolling passes are carried out. For the detailed pressing process parameters, please refer to Table 3. The remaining preparation processes are basically the same as those in Example 1.
[0045] Table 3 Rolling process parameters of the copper-titanium alloy cross asynchronous in Comparative Example 2
[0046] Stage Pass Exit thickness (μm) Rolling force (t) 1 1 88 5 1 2 70 5
[0047] Example 2
[0048] This example provides a rolling method for a copper-titanium alloy foil. The copper-titanium alloy foil includes the following specific composition: the mass ratio of titanium is 3.25%, and the sum of the mass ratios of copper and titanium elements is 99.5%, and the rest are inevitable impurities; its initial size is a width of 30mm and a thickness of 0.2mm. The used copper-titanium alloy foil has a smooth surface and good flatness. The specific rolling steps are as follows:
[0049] During the rolling process, the speed of the upper working roll is greater than that of the lower working roll, and the speed difference ratio between the two is 1.1, and the rolling directions of adjacent two passes are opposite. Under the conditions of room temperature and no intermediate annealing, a total of 70 passes are rolled, and the reduction rate per pass is controlled to be 0.8%; the selection of the rolling force during the rolling process is set based on trying to control the reduction rate per pass to be the same.
[0050] The above rolling process uses a 3M-IV asynchronous rolling mill. During the rolling process, rolling inlet lubrication is used, and there is no lubrication at the rolling outlet, and only the upper and lower working rolls are lubricated, and the upper and lower backup rolls are not lubricated.
[0051] It also includes cleaning the surface oil stain of the rolled copper-titanium alloy thin strip, packaging it, and sending it to the warehouse.
[0052] The thickness of the copper-titanium thin strip rolled in this example is about 0.088mm.
[0053] The inverse pole figure of the grain distribution of the copper-titanium alloy thin strip obtained in this example is similar to that in Example 1, and the grain size distribution curve is a bimodal structure; the obtained conductivity and elongation are both improved.
[0054] Example 3
[0055] This example provides a rolling method for a copper-titanium alloy foil. The copper-titanium alloy foil includes the following specific composition: the mass ratio of titanium is 3.25%, and the sum of the mass ratios of copper and titanium elements is 99.5%, and the rest are inevitable impurities; its initial size is a width of 30mm and a thickness of 0.15mm. The used copper-titanium alloy foil has a smooth surface and good flatness. The specific rolling steps are as follows:
[0056] During the rolling process, the speed of the upper working roll is greater than that of the lower working roll, and the differential speed ratio between the two is 1.25. The rolling directions of adjacent two passes are opposite. Under the conditions of room temperature and without intermediate annealing, a total of 50 passes are rolled; the reduction rate per pass is controlled at 0.7% on average; the rolling force during the rolling process is selected based on the setting of trying to control the same reduction rate per pass.
[0057] The above rolling process uses a 3M-IV asynchronous rolling mill. During the rolling process, rolling inlet lubrication is adopted, and there is no lubrication at the rolling outlet. Moreover, only the upper and lower working rolls are lubricated, and the upper and lower backup rolls are not lubricated.
[0058] It also includes cleaning the surface oil stain of the rolled copper-titanium alloy thin strip, packaging it, and sending it to the warehouse.
[0059] The thickness of the copper-titanium thin strip obtained by rolling in this embodiment is about 0.097 mm.
[0060] The inverse pole figure of the grain distribution of the copper-titanium alloy thin strip obtained in this embodiment is similar to that of Example 1, and the grain size distribution curve is a bimodal structure; the obtained conductivity and elongation are both improved.
[0061] Performance Test
[0062] The conductivity and elongation of the copper-titanium alloy thin strips obtained by rolling the copper-titanium alloy foils in Example 1 and Comparative Examples 1-2 are compared, and the results are shown in Table 4 in detail.
[0063] Table 4 Performance Parameter Table of Copper-Titanium Alloy Thin Strips Obtained by Rolling in Each Example and Comparative Example
[0064]
Claims
1. A method for rolling a copper-titanium alloy foil, characterized in that: The copper-titanium alloy foil is cold rolled, and the speed ratio of the upper and lower working rolls during the rolling process is 1.1-1.25, and the rolling directions of adjacent passes are opposite; the pressing rate of each pass is 0.4%-0.9%, and the rolling passes are 50-70 times. The grain size distribution curve of the copper-titanium alloy thin strip obtained after rolling is a bimodal structure, and the bimodal peak values are 4-6μm and 19-21μm, respectively.
2. The method for rolling a copper-titanium alloy foil according to claim 1, characterized in that: In the copper-titanium alloy thin strip, the number of grains with a particle size between 4 and 6 μm accounts for more than 40%, and the number of grains with a particle size between 19 and 21 μm accounts for more than 50%.
3. The method for rolling a copper-titanium alloy foil according to claim 1, characterized in that: During the rolling process, the speed ratio of the upper and lower working rolls is 1.2; And / or the rolling passes are any even number between 50 and 70, and the reduction ratio of every two passes is 0.8% to 1.4%.
4. The method for rolling a copper-titanium alloy foil according to claim 1, characterized in that: The rolling force of the rolling process is 1.8 to 2.2 t; And / or the pre-rolling tension and post-rolling tension of the rolling process are the same, and are both 600N.
5. The method for rolling a copper-titanium alloy foil according to claim 4, characterized in that: In the rolling process, the rolling entrance is lubricated, the rolling exit is not lubricated, and the working rolls are lubricated, while the support rolls are not lubricated.
6. The method for rolling a copper-titanium alloy foil according to claim 1, characterized in that: The copper-titanium alloy foil is cold rolled, specifically, the copper-titanium alloy foil is rolled at room temperature without intermediate annealing during the rolling process.
7. The method for rolling a copper-titanium alloy foil according to any one of claims 1 to 6, characterized in that: The initial thickness of the copper-titanium alloy foil is between 0.1 and 0.2 mm.
8. The method for rolling a copper-titanium alloy foil according to any one of claims 1 to 6, characterized in that: The copper-titanium alloy foil comprises the following components in proportion by mass: 1-6% Ti, and the sum of the contents of copper and titanium elements is not less than 99.5%.
9. The method for rolling a copper-titanium alloy foil according to claim 8, characterized in that: For a titanium content of 3.25%, the conductivity of the rolled copper-titanium alloy strip reaches 15.17%; and / or its elongation reaches 1.29%.