A low-cost process for preparing highly homogenized titanium cathode rollers

Abstract

This invention belongs to the field of titanium-based cathode roller technology and discloses a low-cost process for preparing highly homogenized titanium cathode rollers, comprising: a welding process: performing friction stir welding on titanium materials to obtain welded titanium materials; a first heat treatment process: placing the welded titanium materials at 905~915℃ for 3~5 minutes, and then cooling to room temperature; repeating the first heat treatment process 3~4 times to obtain first heat-treated titanium materials; a second heat treatment process: placing the first heat-treated titanium materials at 595~605℃ for 8~10 minutes, and then cooling to room temperature to obtain uniform titanium materials for cathode rollers. This invention, by subjecting the welded industrial pure titanium to a "cyclic heat treatment-annealing" composite heat treatment, can homogenize the grain size, thereby obtaining titanium materials that meet the quality and performance requirements of cathode rollers.

Description

Technical Field

[0001] This invention belongs to the field of titanium-based cathode roller technology, specifically relating to a low-cost process for preparing highly uniform titanium cathode rollers. Background Technology

[0002] Electrolytic copper foil, as a crucial "connection hub" for electronic components, is a key material in the manufacture of high-frequency, high-speed printed circuit boards for 5G communication and high-energy-density lithium-ion batteries. The titanium cathode roller, as the core and key component of a complete electrolytic copper foil production line, determines the grade and quality of the copper foil and is considered the heart of electrolytic copper foil production. Cathode rollers are mainly manufactured using two processes: spinning and welding. Spinning produces titanium cathode rollers with uniform surface grain size, producing copper foil without defects such as bright bands or color differences, and is easy to process. However, the titanium ring blank requires complex and costly processes before spinning, including vacuum melting of sponge titanium, ingot division, forging, punching, hole expansion, ring rolling, ring turning, and spinning. In contrast, welding is a cheaper and simpler process, reducing costs and optimizing the manufacturing process to some extent. However, a longitudinal weld seam exists on the surface of the welded cathode roller. If the welding and post-processing are not properly controlled, bright spots or bands will appear on the corresponding locations of the copper foil, severely affecting and restricting the high-quality and high-efficiency production of copper foil. Therefore, developing welded cathode rollers with high surface grain size, uniform microstructure, and consistent grain size is a key issue.

[0003] The current traditional cathode roller welding process uses fusion welding, which has high heat input and a wide weld area. Impurities are easily introduced during the welding process, which affects the green foil. Furthermore, since the weld microstructure differs significantly from the base material microstructure, processes such as forging, rolling, and heat treatment are needed to further improve the microstructure, but it is still impossible to achieve complete consistency between the weld microstructure and the base material microstructure.

[0004] Friction stir welding (FSW) technology features low heat input, low residual stress, and high welding efficiency, making it advantageous for welding large-size cathode rollers. Furthermore, FSW avoids the influence of impurities introduced by traditional fusion welding on the green foil, improving the efficiency and precision of cathode roller titanium cylinder processing. However, due to the significant difference between the weld microstructure and the base material microstructure after welding, problems such as color difference and bright bands occur during the green foil production of the cathode roller. Summary of the Invention

[0005] In view of the shortcomings and defects of the prior art, the purpose of this invention is to provide a low-cost process for preparing highly uniform titanium cathode rollers, so as to solve the problems of color difference and bright band caused by the difference in grain size between the cathode roller weld and the base material during foil production.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A low-cost process for preparing highly homogenized titanium cathode rollers includes the following steps:

[0008] Welding process: Titanium material is subjected to friction stir welding to obtain welded titanium material;

[0009] First heat treatment process: The welded titanium material is placed at 905~915℃ and held for 3~5 minutes, then cooled to room temperature;

[0010] Repeat the first heat treatment process 3 to 4 times to obtain the first heat-treated titanium material;

[0011] Second heat treatment process: The first heat-treated titanium material is placed at 595~605℃ for 8~10 minutes and then cooled to room temperature.

[0012] Preferably, during the first heat treatment process, the cooling method is air cooling.

[0013] Preferably, the first heat treatment process is carried out in a protective atmosphere.

[0014] Preferably, during the second heat treatment process, the cooling method is air cooling.

[0015] Preferably, the second heat treatment process is carried out in a protective atmosphere.

[0016] Preferably, when performing friction stir welding on titanium materials, the stirring head is made of W-Re alloy, the stirring head rotation speed is 80~200 r / min, and the forward speed is 80~150 mm / min.

[0017] Preferably, the friction stir welding process of titanium materials is carried out in a protective atmosphere.

[0018] Preferably, the composition and content of impurity elements in the titanium material, expressed as a percentage by mass, are as follows:

[0019] Fe≤0.05%, C≤0.03%, N≤0.03%, O≤0.06%, H≤0.002%.

[0020] The present invention also provides a cathode roller, wherein the manufacturing process of the cathode roller includes the low-cost manufacturing process of the highly homogenized titanium cathode roller described above.

[0021] Preferably, the base material, heat-affected zone, and stirring zone of the titanium material in friction stir welding are uniform equiaxed crystals.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The essence of this invention's low-cost process for preparing highly homogenized titanium cathode rollers lies in inducing the α-phase transformation (α→β→α) through a cyclic heat treatment process. During this process, the holding time and cooling rate are controlled to ensure incomplete phase transformation, increasing the number of grain boundaries and nucleation points. This addresses the problem of grain growth occurring in the base material during heat treatment due to the lack of recrystallization driving force. Multiple cycles achieve the goal of homogenizing and refining the weld microstructure with the base material. After treatment with this invention, the average grain size of the titanium material is essentially uniform throughout. Therefore, the method of this invention effectively solves the problems of color difference and bright bands caused by the difference in grain size between the cathode roller weld and the base material during foil production. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the cyclic heat treatment process in the low-cost preparation of highly homogenized titanium cathode rollers of the present invention.

[0025] Figure 2(a) shows the microstructure of the titanium base material (BM) after heat treatment in Example 1 of the present invention; Figure 2(b) shows the microstructure of the heat-affected zone (HAZ) of the titanium material after heat treatment in Example 1 of the present invention; Figure 2(c) shows the microstructure of the stirring zone (SZ) of the titanium material after heat treatment in Example 1 of the present invention.

[0026] Figure 3(a) shows the microstructure of the titanium base material (BM) after heat treatment in Comparative Example 1 of the present invention; Figure 3(b) shows the microstructure of the heat-affected zone (HAZ) of the titanium material after heat treatment in Comparative Example 1 of the present invention; Figure 3(c) shows the microstructure of the stirring zone (SZ) of the titanium material after heat treatment in Comparative Example 1 of the present invention.

[0027] Figure 4(a) shows the microstructure of the titanium base material (BM) after heat treatment in Comparative Example 2 of the present invention; Figure 4(b) shows the microstructure of the heat-affected zone (HAZ) of the titanium material after heat treatment in Comparative Example 2 of the present invention; Figure 4(c) shows the microstructure of the stirring zone (SZ) of the titanium material after heat treatment in Comparative Example 2 of the present invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] The process for preparing a high-uniformity titanium cathode roller at low cost according to the present invention includes the following steps:

[0030] Step 1: Perform friction stir welding on titanium materials to prepare weldable titanium materials;

[0031] Specifically, by mass percentage, the composition and content of impurity elements in industrial pure titanium (the above-mentioned titanium material) are Fe≤0.05%, C≤0.03%, N≤0.03%, O≤0.06%, and H≤0.002%.

[0032] Specifically, the stirring head is made of W-Re alloy, the stirring head rotation speed is 80~200 r / min, and the forward speed is 80~150 mm / min. Argon gas is introduced as a protective gas during friction stir welding.

[0033] Step 2: Use the welding titanium material prepared in Step 1 to perform heat treatment at 905~915℃ and then cool to room temperature;

[0034] Specifically, the welded titanium material is subjected to a heat treatment at 905~915℃ for 3~5 minutes, and the cooling method is air cooling.

[0035] Step 3: Repeat step 2 3 to 4 times;

[0036] Step 4: The titanium material obtained in Step 3 is subjected to heat treatment at 595~605℃ and cooled to room temperature to obtain a uniform titanium material for cathode rollers.

[0037] Specifically, the titanium material obtained in step 3 is subjected to a heat treatment at 595~605℃ for 8~10 minutes, and air cooling is used. Argon gas is introduced as a protective gas during the heat treatment process.

[0038] Preferably, the preparation process in step 1 is friction stir welding. The stirring head rotation speed is 80~200 r / min, for example, 80 r / min, 100 r / min, 150 r / min and 200 r / min and any value between therewith; the forward speed is 80~150 mm / min, for example, 80 mm / min, 100 mm / min, 120 mm / min and 150 mm / min and any value between therewith.

[0039] Preferably, in step 2, the titanium material is subjected to a heat treatment at 905~915℃ for 3~5 minutes after welding, and the cooling method is air cooling. For example, 905℃~915℃, 3~5 minutes, and any value in between.

[0040] Preferably, in step 4, the titanium material is subjected to a heat treatment at 595~605℃ for 8~10 minutes, and the cooling method is air cooling. For example, 595℃~605℃, 8~10 minutes, and any value in between.

[0041] In the following embodiments of the present invention, industrially pure titanium with the above-mentioned composition is used.

[0042] Example 1

[0043] This embodiment presents a low-cost process for preparing highly homogeneous titanium cathode rollers. In this embodiment, industrial pure titanium is subjected to friction stir welding at a stirring head speed of 100 r / min and a forward speed of 100 mm / min, followed by a combined heat treatment of "cyclic heat treatment + annealing" to prepare titanium material with uniform grain size at the weld and base material. The specific steps are as follows:

[0044] Step 1: Select two 150mm×70mm×3mm industrial pure titanium TA1 plates for friction stir welding. The stirring head speed is 100 r / min and the forward speed is 100mm / min. Argon protective gas is introduced during welding.

[0045] Step 2: Place the welded titanium material in a tube furnace for circulating heat treatment. Figure 1 The heat preservation temperature is 910℃, the heat preservation time is 3 minutes / cycle, the number of cycles is 3, and the cooling method is air cooling.

[0046] Step 3: Set the temperature of the tube furnace to 595℃, place the titanium material processed in Step 2 into the tube furnace, hold it at that temperature for 10 minutes, and cool it by air cooling.

[0047] The successful implementation of this embodiment prepared welded titanium material with uniform equiaxed grains. As shown in Figures 2(a) to 2(c), the base material, heat-affected zone, and stirred zone all exhibit uniform equiaxed grains with similar grain sizes. The average grain sizes of the base material, heat-affected zone, and stirred zone are 40.7µm, 43.3µm, and 38.3µm, respectively. This is because the base material lacks the driving force for recrystallization, thus its grain size remains almost unchanged through phase transformation. However, due to the presence of stress and the small grain size at the weld, recrystallization and grain growth occur at the weld after three cycles, eventually approaching the grain size of the base material.

[0048] Comparative Example 1

[0049] This comparative example uses a stirring head with a rotation speed of 100 r / min and a forward speed of 100 mm / min to perform friction stir welding on industrial pure titanium, followed by a combined heat treatment of "cyclic heat treatment + annealing". The specific steps are as follows:

[0050] Step 1: Select two 150mm×70mm×3mm industrial pure titanium TA1 plates for friction stir welding. The stirring head speed is 100 r / min and the forward speed is 100mm / min. Argon protective gas is introduced during welding.

[0051] Step 2: Place the welded titanium material in a tube furnace for circulating heat treatment. The holding temperature is 930℃, the holding time is 3 minutes / cycle, the number of cycles is 3, and the cooling method is air cooling.

[0052] Step 3: Set the temperature of the tube furnace to 595℃, place the titanium material processed in Step 2 into the tube furnace, hold it at that temperature for 10 minutes, and cool it by air cooling.

[0053] Due to the excessively high holding temperature during cyclic heat treatment, the grains grow further after the phase transformation. The grain growth is obvious in the stirring zone, the base material, and the heat-affected zone, and an α-lamellar structure is produced. This is mainly caused by the excessively fast cooling rate during the β→α transformation, as shown in Figures 3(a) to 3(c). It is impossible to achieve equiaxed uniformity of the overall microstructure.

[0054] Comparative Example 2

[0055] This comparative example uses a stirring head with a rotation speed of 100 r / min and a forward speed of 100 mm / min to perform friction stir welding on industrial pure titanium, followed by a combined heat treatment of "cyclic heat treatment + annealing". The specific steps are as follows:

[0056] Step 1: Select two 150mm×70mm×3mm industrial pure titanium TA1 plates for friction stir welding. The stirring head speed is 100 r / min and the forward speed is 100mm / min. Argon protective gas is introduced during welding.

[0057] Step 2: Place the welded titanium material in a tube furnace for circulating heat treatment. The holding temperature is 910℃, the holding time is 3 minutes / cycle, the number of cycles is 1, and the cooling method is air cooling.

[0058] Step 3: Set the temperature of the tube furnace to 595℃, place the titanium material in the tube furnace, hold it at that temperature for 10 minutes, and cool it by air cooling.

[0059] When the number of cycles is 1, as shown in Figures 4(a) to 4(c), recrystallization and grain growth occur at the weld, but the grains are still relatively small. A few lamellar structures appear in the base material and heat-affected zone, and the overall structure cannot achieve uniform equiaxedness.

[0060] Comparative Example 3

[0061] This comparative example uses a stirring head with a rotation speed of 100 r / min and a forward speed of 100 mm / min to perform friction stir welding on industrial pure titanium, followed by a combined heat treatment of "cyclic heat treatment + annealing". The specific steps are as follows:

[0062] Step 1: Select two 150mm×70mm×3mm industrial pure titanium TA1 plates for friction stir welding. The stirring head speed is 100 r / min and the forward speed is 100mm / min. Argon protective gas is introduced during welding.

[0063] Step 2: Place the welded titanium material in a tube furnace for circulating heat treatment. The holding temperature is 890℃, the holding time is 3 minutes / cycle, the number of cycles is 3, and the cooling method is air cooling.

[0064] Step 3: Set the temperature of the tube furnace to 595℃, place the titanium material processed in Step 2 into the tube furnace, hold it at that temperature for 10 minutes, and cool it by air cooling.

[0065] Since the holding temperature of the cyclic heat treatment is at the phase transformation point, only a few grains undergo phase transformation, while the rest of the grains recrystallize and grow, resulting in a large difference in grain size between the base material and the weld area, making it impossible to achieve overall equiaxed uniformity of the microstructure.

[0066] Comparative Example 4

[0067] This comparative example uses a stirring head with a rotation speed of 600 r / min and a forward speed of 50 mm / min to perform friction stir welding on industrial pure titanium, followed by a combined heat treatment of "cyclic heat treatment + annealing". The specific steps are as follows:

[0068] Step 1: Select two 150mm×70mm×3mm industrial pure titanium TA1 plates for friction stir welding. The stirring head speed is 100 r / min and the forward speed is 100mm / min. Argon protective gas is introduced during welding.

[0069] Step 2: Place the welded titanium material in a tube furnace for circulating heat treatment. The holding temperature is 910℃, the holding time is 3 minutes / cycle, the number of cycles is 3, and the cooling method is air cooling.

[0070] Step 3: Set the temperature of the tube furnace to 595℃, place the titanium material in the tube furnace, hold it at that temperature for 10 minutes, and cool it by air cooling.

[0071] Under the process parameters of 600 r / min stirring head rotation speed and 50 mm / min forward speed, the macroscopic morphology of the welded surface is poor. Furthermore, due to the increase in heat input, the grain size of the microstructure at the weld increases, and the grain size is large after heat treatment, making it impossible to achieve a uniform and equiaxed microstructure.

[0072] Example 2

[0073] This embodiment presents a low-cost process for preparing highly homogeneous titanium cathode rollers. In this embodiment, industrial pure titanium is subjected to friction stir welding at a stirring head speed of 150 r / min and a forward speed of 80 mm / min, followed by a combined heat treatment of "cyclic heat treatment + annealing" to prepare titanium material with uniform grain size at the weld and base material. The specific steps are as follows:

[0074] Step 1: Select two 150mm×70mm×3mm industrial pure titanium TA1 plates for friction stir welding. The stirring head speed is 150 r / min and the forward speed is 80mm / min. Argon protective gas is introduced during welding.

[0075] Step 2: Place the welded titanium material in a tube furnace for circulating heat treatment. The holding temperature is 905℃, the holding time is 5 minutes / cycle, the number of cycles is 3, and the cooling method is air cooling.

[0076] Step 3: Set the temperature of the tube furnace to 600℃, place the titanium material in the tube furnace, hold it at that temperature for 10 minutes, and cool it by air cooling.

[0077] The successful implementation of this embodiment prepared weldable titanium material with equiaxed and uniformly distributed grains. It can be seen that the base material, heat-affected zone and stirring zone are uniform equiaxed crystals with an average grain size of 39.5µm.

[0078] Example 3

[0079] This embodiment presents a low-cost process for preparing highly homogeneous titanium cathode rollers. In this embodiment, industrial pure titanium is subjected to friction stir welding at a stirring head speed of 200 r / min and a forward speed of 150 mm / min, followed by a combined heat treatment of "cyclic heat treatment + annealing" to prepare titanium material with uniform grain size at the weld and base material. The specific steps are as follows:

[0080] Step 1: Select two 150mm×70mm×3mm industrial pure titanium TA1 plates for friction stir welding. The stirring head speed is 200 r / min and the forward speed is 150mm / min. Argon protective gas is introduced during welding.

[0081] Step 2: Place the welded titanium material in a tube furnace for circulating heat treatment. The holding temperature is 915℃, the holding time is 3 minutes / cycle, the number of cycles is 4, and the cooling method is air cooling.

[0082] Step 3: Set the temperature of the tube furnace to 605℃, place the titanium material in the tube furnace, hold it at that temperature for 8 minutes, and cool it by air cooling.

[0083] The successful implementation of this embodiment prepared weldable titanium material with equiaxed and uniformly distributed grains. It can be seen that the base material, heat-affected zone and stirring zone are uniform equiaxed crystals with an average grain size of 41.7µm.

[0084] The method of the present invention uses friction stir welding process with low heat input, low residual stress and high welding efficiency. It can avoid the influence of impurities introduced by traditional fusion welding on electrolytic copper foil, improve the efficiency and accuracy of cathode roller titanium cylinder processing and forming, and is beneficial for welding large-size cathode rollers.

[0085] The above descriptions are merely embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made using the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A low-cost process for preparing highly uniform titanium cathode rollers, characterized in that, The process includes the following: Welding process: Titanium material is subjected to friction stir welding to obtain welded titanium material; First heat treatment process: The welded titanium material is placed at 905~915℃ and held for 3~5 minutes, then cooled to room temperature; Repeat the first heat treatment process 3 to 4 times to obtain the first heat-treated titanium material; Second heat treatment process: The titanium material that was first heat treated is placed at 595~605℃ and held for 8~10 minutes, and then cooled to room temperature.

2. The process for preparing a high-uniformity titanium cathode roller at low cost according to claim 1, characterized in that, During the first heat treatment process, air cooling was used.

3. The process for preparing a high-uniformity titanium cathode roller at low cost according to claim 1, characterized in that, The first heat treatment process is carried out in a protective atmosphere.

4. The process for preparing a high-uniformity titanium cathode roller at low cost according to claim 1, characterized in that, During the second heat treatment process, air cooling was used.

5. The process for preparing a high-uniformity titanium cathode roller at low cost according to claim 1, characterized in that, The second heat treatment process is carried out in a protective atmosphere.

6. The process for preparing a high-uniformity titanium cathode roller at low cost according to claim 1, characterized in that, When performing friction stir welding on titanium materials, the stirring head is made of W-Re alloy, the stirring head rotation speed is 80~200 r / min, and the forward speed is 80~150 mm / min.

7. The process for preparing a high-uniformity titanium cathode roller at low cost according to claim 1, characterized in that, The friction stir welding process of titanium materials is carried out in a protective atmosphere.

8. The process for preparing a high-uniformity titanium cathode roller at low cost according to claim 1, characterized in that, The composition and content of impurity elements in the titanium material, by mass percentage, are as follows: Fe≤0.05%, C≤0.03%, N≤0.03%, O≤0.06%, H≤0.002%.

9. A cathode roller, characterized in that, The cathode roller manufacturing process includes the low-cost manufacturing process for highly homogenized titanium cathode rollers as described in any one of claims 1-8.

10. A cathode roller according to claim 9, characterized in that, After friction stir welding, the base material, heat-affected zone, and stirring zone of the titanium material are all homogeneous equiaxed crystals.

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