A chromium-zirconium-copper flat prism and its preparation method

Abstract

This invention discloses a method for preparing chromium-zirconium copper flat sheets. The process flow is as follows: batching → continuous casting → first cold working (drawing / skinning) → solution treatment → second cold working → rolling → third cold working → aging annealing → finished product drawing. The batching, smelting, and continuous casting are performed according to the mass percentages of the components of the chromium-zirconium copper flat sheet. The mass percentage composition of the chromium-zirconium copper flat sheet is Cr: 0.6-0.9, Zr: 0.03-0.06, with the balance being Cu and unavoidable impurities. The processing amount of the second cold working is 1%-2.5%. Using this method, the key process parameters can be quickly obtained by substituting the desired dimensions of the chromium-zirconium copper flat sheet into empirical formulas, saving trial and error costs. This invention enables the production of chromium-zirconium copper flat sheets with high aspect ratios and high mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of copper alloy technology, specifically relating to a chromium-zirconium copper flat prism and its preparation method. Background Technology

[0002] With the rapid development of high-voltage power transmission in China, the voltage in transmission lines is constantly increasing, the circuits are subjected to higher voltages, and the resulting electric arcs are larger. As a crucial component of circuit switching, high-voltage switches must withstand the high temperatures generated by the electric arcs and the impact of high voltage. Therefore, high-voltage power transmission places higher demands on the strength and high-temperature stability of the materials used in high-voltage switches.

[0003] Chromium-zirconium-copper alloy, as an age-hardening alloy, strengthens the alloy while largely preserving the conductivity of copper. The dispersed distribution of solute elements in the matrix effectively inhibits grain growth at high temperatures, resulting in excellent high-temperature stability. Therefore, chromium-zirconium-copper flat alloys are widely used in the production of high-voltage switches.

[0004] Currently, there are two main processes for preparing chromium-zirconium-copper flat bars: one process involves ingot casting, extrusion, multiple drawing, annealing, and drawing. For example, Chinese patent CN116574929A discloses a manufacturing process for chromium bronze contact finger profiles for high-voltage switches, including S1, preparing an upward-drawing chromium bronze rod; S1-1, weighing 0.6-1.2% Cr and the remainder Cu by weight percentage for batching; S1-2, adding the batching from S1-1 to a graphite crucible in an upward-drawing continuous casting furnace for melting, maintaining the solution temperature at 1150°C. ~1350℃; S1-3, The solution obtained in step S1-2 is continuously cast upwards using a vertical continuous casting machine to obtain an upward-cast chromium bronze rod. Then, the upward-cast chromium bronze rod is coiled using a coiling machine to obtain a coiled chromium bronze rod; S2, continuous extrusion; S3, cold drawing; S4, cut to length; S5, aging heat treatment; S6, post-treatment for later use. Because the extrusion is carried out at high temperature, the oxygen content of the ingot is too high, which will cause blistering in the extruded blank. As a result, the ingot needs to be prepared by vacuum melting, which reduces the production yield and increases the production cost.

[0005] Another process for preparing chromium-zirconium-copper flat sheets is: upward drawing of blank - continuous extrusion - solution treatment - (multiple) drawing - annealing - drawing. This process is generally only suitable for the production of flat sheets with a width-to-thickness ratio of <2. Producing flat sheets with a larger width-to-thickness ratio will significantly increase the number of drawing operations and even the solution treatment process, which will lead to an increase in processing costs to a certain extent.

[0006] Therefore, in view of the limitations of the existing process for chromium-zirconium-copper flat sheets, there is an urgent need to design a controllable method for preparing chromium-zirconium-copper flat sheets that can easily obtain key process parameters based on the required dimensions of the chromium-zirconium-copper flat sheets, reasonably control trial and error costs, and obtain chromium-zirconium-copper flat sheets with a high aspect ratio and high mechanical properties. Summary of the Invention

[0007] This invention provides a method for preparing chromium-zirconium-copper flat sheets. By substituting the dimensions of the desired chromium-zirconium-copper flat sheets into empirical formulas using this method, key process parameters can be obtained quickly, saving trial and error costs. Furthermore, it can produce chromium-zirconium-copper flat sheets with high aspect ratio and high mechanical properties.

[0008] This invention provides a method for preparing chromium zirconium copper flats. The process flow of this method is as follows: batching → continuous casting → first cold working (drawing / skinning) → solution treatment → second cold working → rolling → third cold working → aging annealing → finished product drawing.

[0009] The process involves batching, smelting, and continuous casting of the chromium-zirconium-copper flatbread according to the mass percentages of each component. The mass percentage composition of the chromium-zirconium-copper flatbread is Cr: 0.6-0.9, Zr: 0.03-0.06, with the balance being Cu and unavoidable impurities.

[0010] The amount of processing in the second cold working is 1%-2.5%.

[0011] The appropriate amount of Cr and Zr elements provided by this invention have stable solid solubility in the copper matrix at the solid solution temperature. When the content of Cr and Zr elements is high, there will still be a certain amount of undissolved Cr and Zr particles in the material after solid solution, which will greatly hinder the plastic deformation of the material. The undissolved Cr and Zr particles cannot be completely uniformly distributed, which will cause uncontrollable widening of the material during the rolling process and affect the subsequent production process.

[0012] The present invention provides that there is an interaction between Cr and Zr. During the aging process, an appropriate amount of Zr precipitates around Cr, thereby inhibiting the growth of the Cr precipitate phase, making the Cr precipitate phase more dispersed, and improving the strength and high-temperature softening resistance of the material.

[0013] The Cr and Zr elements provided by this invention precipitate as a second phase during the aging process of chromium-zirconium copper (CrZC), thereby achieving age strengthening, reducing lattice distortion in CrZC, and giving CrZC a higher conductivity. However, adding too much Cr and Zr does not significantly improve the age strengthening effect; on the contrary, it significantly reduces the conductivity of CrZC. Therefore, in summary, the Cr content provided by this invention is 0.6-0.9%, and the Zr content is 0.03-0.06%.

[0014] In this specific embodiment of the invention, a second cold working is performed on the solution-treated blank before rolling, with a cold working amount of 1%-2.5%. Since the blank after solution treatment mainly consists of cube recrystallized structure, if rolling is performed directly, uneven lateral deformation during the rolling process will cause a "earing" phenomenon at the edges, resulting in uneven and irregular width expansion of the rolled blank. This specific embodiment of the invention performs a small amount of cold deformation on the solution-treated blank. Under the combined effect of appropriate alloy composition, a goss texture in a certain direction can be formed at a depth of 0-0.15mm from the blank surface, thereby allowing the metal to preferentially flow along the rolling direction during the rolling process and eliminating the "earing" phenomenon at the edges. If the Cr and Zr contents are too high, a large number of hard spots are easily formed. Due to the presence of many hard spots, it is not easy to form a goss texture in a certain direction under low-amount cold working.

[0015] Using the alloy composition and its mass percentage provided by this invention, and the preparation process, empirical formulas for rolling width, rolling thickness, and blank size after solution treatment can be obtained. Furthermore, once the desired dimensions of the flattened material are obtained, process parameters such as rolling thickness, rolling width, and blank size after solution treatment can be quickly derived, avoiding extensive trial and error and saving trial and error costs. Based on the width and thickness of the obtained chromium-zirconium-copper flattened material, the rolling width L after rolling and the blank size D after solution treatment are obtained as follows:

[0016] L=A*(Dd)+D

[0017] D = (1.1a + 2b + 7.1) / 3.11

[0018] Where A is a constant, with a value of 0.5-0.55, a is the thickness of the obtained chromium-zirconium copper flat sheet, b is the width of the obtained chromium-zirconium copper flat sheet, and d is the rolling thickness.

[0019] Furthermore, 350mm rolls are used for rolling, and the roll roughness is controlled at Ra1-2 to ensure the surface quality of the rolled blank. The rolling speed is controlled at 10-20m / min.

[0020] Furthermore, the rolling thickness is the thickness of the chromium-zirconium copper flat sheet + (1.2-1.5 mm), and the rolling width is the width of the chromium-zirconium copper flat sheet + (2-3 mm). If the rolling thickness is too thick or the rolling width is too wide, it can easily lead to cracking during cold working of the flat sheet. If the rolling thickness is too thin, and the difference between the rolling dimensions and the width of the chromium-zirconium copper flat sheet is small, the flat sheet will not be able to fill the die cavity during the drawing process, and the required edge angle cannot be formed.

[0021] Furthermore, after the third cold working, the thickness of the blank is the thickness of the chromium-zirconium copper flattened sheet plus (0.45-0.55 mm), and the width is the width of the chromium-zirconium copper flattened sheet plus (0.18-0.25 mm). The rolled blank is drawn to the allowable size (third cold working), and the width-direction compression / thickness-direction compression must be greater than 0.3. Otherwise, a concave shape in the center after drawing will occur, affecting the finished product's forming. Additionally, considering that excessive allowance will lead to the formation of a large amount of goss texture, it is detrimental to the bending properties of the flattened sheet parallel to the rolling direction.

[0022] Furthermore, in the microstructure at a depth of 0-0.15 mm from the surface of the blank after the second cold working, the area ratio of Cube texture and Goss texture is more than 60%.

[0023] Furthermore, the ratio of the solid solution texture cube area to the processing texture goss area is 1:1-0.5, and the processing texture includes both cube texture and goss texture. An appropriate amount of solid solution cube texture at the edges facilitates dislocation movement and allows the material to unfold easily during rolling.

[0024] Because the surface of the upward-drawing blank has obvious crystal lines, these need to be removed to avoid affecting the surface quality of the product. However, the upward-drawing blank is in a solution-treated state with low hardness, and directly removing the crystal lines can easily damage the blank surface. Therefore, the blank needs to be work-hardened, i.e., subjected to the first cold working. At the same time, a large amount of cold working is beneficial to providing driving force for subsequent grain recrystallization. Large cold deformation is beneficial to providing driving force for recrystallization, while increasing the recrystallization nucleation sites, which has a grain refinement effect. The equiaxed crystals generated by recrystallization are beneficial to the plastic deformation of the blank during the rolling process. Therefore, the processing amount of the first cold working after upward continuous casting provided by this invention is ≥35%.

[0025] Furthermore, the solution temperature is 930-950℃, and the furnace charge is <2 tons. Too low a solution temperature is detrimental to the solute element's solubility, affecting the solution effect. Simultaneously, undissolved solute increases rolling deformation resistance. Too high a solution temperature makes it difficult to control grain size during the solution process and easily leads to grain growth at the edges of the solution-treated billet, resulting in orange peel texture or even cracking at the edges during rolling. The grain size after solution treatment is 0.02-0.04 mm. Excessively large grains easily lead to increased impurity content within the grain boundaries, and the concentration of stress at the edges during rolling easily causes cracking at grain boundaries with higher defect content. However, too small grains increase the resistance of grain boundaries to dislocation slip, thereby increasing the deformation resistance during rolling.

[0026] Furthermore, the aging annealing temperature is 450-470℃, and the aging time is 4-7h.

[0027] This invention also provides a method for preparing chromium-zirconium-copper flat sheets using the aforementioned method, wherein the grain size of the chromium-zirconium-copper flat sheet structure is ≤0.005 mm. Fine grains can effectively improve the strength and ductility of the chromium-zirconium-copper flat sheet, and the fine grains also mean an increased number of grain boundaries, increasing the number of subsequent second-phase nucleation sites.

[0028] Furthermore, the second phase in the chromium-zirconium-copper flattened structure is composed of Cr and Zr phases, and the distribution quantity of the second phase in the chromium-zirconium-copper flattened structure is 50,000 / mm. 2 The dispersed, fine secondary phase and abundant grain boundaries can effectively suppress dislocation movement, thereby improving the material's strength and resistance to high-temperature softening.

[0029] Furthermore, the thickness of the chromium zirconium copper flat sheet is >2mm, the width is >15mm, and the width-to-thickness ratio is 2-8.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] By controlling the Cr and Zr content and the solution treatment process, the amount of undissolved Cr and Zr particles remaining in the matrix can be minimized while controlling the grain size, thus reducing rolling resistance and the risk of uncontrollable rolling width. Before rolling, a small amount of cold working is performed to form a certain depth of texture, controlling the rolling width. By controlling these two points, the relationship between the dimensions of the rolled product and the solution-treated billet, as well as the relationship between rolling width and rolling thickness, can be determined. This provides a reference for the preparation of flat squares with a width-to-thickness ratio > 2, enabling rapid acquisition of key process parameters and saving trial-and-error costs.

[0032] Simultaneously, the high-volume rolling process significantly improves processing efficiency while simultaneously breaking down the grains, further increasing the nucleation sites for the Cr / Zr second phase during annealing. This results in highly dispersed and fine-grained strengthened products, enabling the flat square products to achieve a tensile strength exceeding 500 MPa, a hardness exceeding 145 HB, and an elongation (A100%) exceeding 15%. This meets the requirements for subsequent cold working of the flat square products, while also giving the processed high-voltage switches higher strength and hardness. Attached Figure Description

[0033] Figure 1 The metallographic structure of the chromium-zirconium copper flat prism prepared in Example 1 is shown in Figure 1.

[0034] Figure 2 This is a second phase distribution diagram of the chromium-zirconium-copper flattened prism obtained in Example 2;

[0035] Figure 3 The image shows the cold working cracking pattern of the chromium-zirconium copper flat prism prepared in Example 1. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Modifications or equivalent substitutions made by those skilled in the art based on their understanding of the technical solutions of this invention, without departing from the spirit and scope of the invention, should be covered within the protection scope of this invention.

[0037] The specific embodiments of the present invention provide a method for preparing chromium-zirconium copper flats by controlling the composition of the upper blank and using a cold rolling process to shorten the production process of chromium-zirconium copper flats with a large width-to-thickness ratio, thereby obtaining the relationship between the finished product size and the rolling size, as well as the rolling thickness and width, and thus solidifying a short-process flow method for preparing chromium-zirconium copper flats.

[0038] The present invention provides 6 embodiments and 4 comparative examples, and the specific components are shown in Table 1.

[0039] The specific embodiment of the present invention provides a process flow of the preparation method as follows: raw material preparation → continuous casting → first cold working (drawing / peeling) → solution treatment → pickling → second cold working → rolling → third cold working → aging annealing → finished product drawing. The raw materials are: oxygen-free copper rod, copper-chromium cored wire, and copper-zirconium cored wire; wherein the copper-chromium cored wire is prepared by wrapping pure chromium with T2 copper, and the copper-zirconium cored wire is prepared by combining T2 copper with a copper-zirconium alloy.

[0040] Example 1: The chromium-zirconium-copper flat prism provided in this embodiment, based on a mass percentage of 100%, includes the following components: Cr: 0.6%, Zr: 0.04%, with the remainder being copper and unavoidable impurities. The finished product size is 4mm*20mm.

[0041] The specific steps of the preparation method provided in this embodiment are as follows:

[0042] S1. Melting: The materials are prepared according to the mass percentage of the chromium-zirconium copper flats. An appropriate amount of oxygen-free copper rod is added to the upward drawing furnace. Argon gas is introduced and the furnace is heated until the oxygen-free rod is completely melted. Then, the automatic feeding of the oxygen-free rod is started, and the feeding speed is controlled at 220 kg / h. The feeding of the oxygen-free rod is stopped when the copper liquid is 20 cm away from the edge of the crucible. The copper-chromium alloy and copper-zirconium alloy prepared in proportion are added. The final temperature is maintained at 1250℃ and held for 20 minutes. After the composition is tested and found to be qualified, the Φ28mm upward drawing blank is produced. During the subsequent drawing process, the oxygen-free copper rod, copper-chromium, and zirconium cored wire are automatically fed according to the predetermined design composition. The composition of the furnace liquid is tested every 30 minutes to ensure that the composition of the upward drawing blank is qualified. The cooling water pressure is 0.3 MPa and the drawing speed is 0.77 mm / s to obtain a Φ28mm diameter upward drawing chromium-zirconium copper blank.

[0043] S2. First cold working: Roll the 28mm blank to 23mm. The subsequent drawing process is carried out with a diameter reduction of 1-2mm per pass, drawing to 19mm. Finally, peel off the skin to 17.5mm to ensure that the surface crystal texture is completely removed, and then draw to 16.5mm.

[0044] S3. Solution treatment: The 16.5mm blank is solution treated at a temperature of 930℃. The conductivity of the blank after solution treatment is controlled at 35-45% IACS, and the hardness HV5 after solution treatment is 50-70.

[0045] S4. Pickling: The above-mentioned solution-treated blanks are pickled. After pickling, the surface of the blanks is free from oxidation, dents, sand holes and other defects.

[0046] S5. Second cold working: The above 16.5mm blank is drawn to 16.4mm, with a drawing rate of 1.2%.

[0047] S6. Rolling: The above-mentioned drawn blank is rolled to a thickness of 5.5mm. The roll roughness during the rolling process is Ra1-2, and the rolling speed is 15m / min.

[0048] S7. Third cold working: The above blank is drawn using a polycrystalline die of 4.5mm*20.2mm. The flared angle of the die is 10° (a smaller flared angle will cause the blank to scrape against the edge of the die during the drawing process). The length of the sizing strip is controlled at 5-7mm (if the sizing strip is too long, it will increase friction; if the sizing strip is too small, it will be difficult to guarantee the finished product size).

[0049] S8. Aging Annealing: The 4.5*20.2mm blank is annealed in a horizontal bright annealing furnace at a temperature of 450℃ for 5 hours.

[0050] S9. Finished Product Drawing: A combined drawing machine is used, employing 4*20 polycrystalline dies to draw the finished product. To ensure product dimensions and straightness: the sizing band length of the drawing die is controlled at 5-7mm, the radius (R) deviation is controlled at ±0.02mm, and the drawing nozzle angle is 6°. The resulting finished product is as follows: Figure 3 As shown, the metallographic structure is as follows Figure 1 As shown, the grains are relatively fine.

[0051] Example 2: The chromium-zirconium copper flat prism provided in this example, based on a mass percentage of 100%, includes the following components: Cr: 0.7%, Zr: 0.045%, with the remainder being copper and unavoidable impurities. The finished product size is 3mm*20mm.

[0052] The preparation method provided in this embodiment includes the following steps:

[0053] S1. Smelting: Prepare the materials according to the required composition. Add an appropriate amount of oxygen-free copper rod to the upward drawing furnace, introduce argon gas and heat until the oxygen-free rod is completely melted. Then, start the automatic feeding of oxygen-free rod, and control the feeding speed at 220Kg / h. Stop feeding oxygen-free rod when the copper liquid is 20cm away from the edge of the crucible. Add copper-chromium alloy and copper-zirconium alloy according to the specified ratio. Finally, maintain the temperature at 1250℃ and hold for 20min. After the composition is tested and found to be qualified, produce Φ28mm upward drawing blank. During the subsequent drawing process, oxygen-free copper rod, copper-chromium, and zirconium cored wire are automatically fed according to the predetermined design composition. The composition of the furnace liquid is tested every 30min to ensure that the composition of the upward drawing blank is qualified. The cooling water pressure is 0.3MPa and the drawing speed is 0.77mm / s to obtain a Φ28mm diameter upward drawing chromium-zirconium copper blank.

[0054] S2. First cold working: Roll the 28mm blank to 23mm. The subsequent drawing process is carried out with a diameter reduction of 1-2mm per pass, drawing to 19mm. Finally, peel off the skin to 17.5mm to ensure that the surface crystal texture is completely removed, and then draw to 16.2mm.

[0055] S3. Solution treatment: The 16.2mm blank is solution treated at a temperature of 950℃. The conductivity of the blank after solution treatment is controlled at 35-45% IACS, and the hardness HV5 after solution treatment is 50-70.

[0056] S4. Pickling: The above-mentioned solution-treated blanks are pickled. After pickling, the surface of the blanks is free from oxidation, dents, sand holes and other defects.

[0057] S5. Second cold working: The 16.2mm blank is drawn to 16.1mm, with a drawing rate of 1.2%.

[0058] S6. Rolling: The above-mentioned drawn blank is rolled to a thickness of 4.5mm. The roll roughness during the rolling process is Ra1-2, and the rolling speed is 15m / min.

[0059] S7. Third cold working: The above blank is drawn using a polycrystalline die of 3.5mm*20.2mm. The die opening angle is 10° (a smaller drawing opening angle will cause the blank to scrape against the edge of the die during the drawing process). The length of the sizing strip is controlled at 5-7mm (if the sizing strip is too long, it will increase friction; if the sizing strip is too small, it will be difficult to guarantee the finished product size).

[0060] S8. Aging Annealing: The 3.5*20.2mm blank is annealed in a horizontal bright annealing furnace at a temperature of 470℃ for 5 hours.

[0061] S9. Finished Product Drawing: A combined drawing machine is used, employing 3*20 polycrystalline dies to draw the finished product. To ensure product dimensions and straightness: the sizing band length of the drawing die is controlled at 5-7mm, the radius (R) deviation is controlled at ±0.02mm, and the drawing nozzle angle is 6°. Figure 2 As shown, the second phase of the prepared product is uniformly distributed in the matrix.

[0062] Example 3: The chromium-zirconium copper flat prism provided in this example, based on a mass percentage of 100%, includes the following components: Cr: 0.8%, Zr: 0.05%, with the remainder being copper and unavoidable impurities. The finished product size is 5mm*18mm.

[0063] The preparation method provided in this embodiment includes the following steps:

[0064] S1. Smelting: Prepare the materials according to the required composition. Add an appropriate amount of oxygen-free copper rod to the upward drawing furnace, introduce argon gas and heat until the oxygen-free rod is completely melted. Then, start the automatic feeding of oxygen-free rod, and control the feeding speed at 220Kg / h. Stop feeding oxygen-free rod when the copper liquid is 20cm away from the edge of the crucible. Add copper-chromium alloy and copper-zirconium alloy according to the specified ratio. Finally, maintain the temperature at 1250℃ and hold for 20min. After the composition is tested and found to be qualified, produce Φ28mm upward drawing blank. During the subsequent drawing process, oxygen-free copper rod, copper-chromium, and zirconium cored wire are automatically fed according to the predetermined design composition. The composition of the furnace liquid is tested every 30min to ensure that the composition of the upward drawing blank is qualified. The cooling water pressure is 0.3MPa and the drawing speed is 0.77mm / s to obtain a Φ28mm diameter upward drawing chromium-zirconium copper blank.

[0065] S2. First cold working: Roll the 28mm blank to 23mm. The subsequent drawing process is carried out with a diameter reduction of 1-2mm per pass, drawing to 18mm. Finally, peel off the skin to 16.5mm to ensure that the surface crystal texture is completely removed, and then draw to 15.6mm.

[0066] S3. Solution treatment: The 15.6mm blank is solution treated at a temperature of 940℃. The conductivity of the blank after solution treatment is controlled at 35-45% IACS, and the hardness HV5 after solution treatment is 50-70.

[0067] S4. Pickling: The above-mentioned solution-treated blanks are pickled. After pickling, the surface of the blanks is free from oxidation, dents, sand holes and other defects.

[0068] S5. Second cold working: The 15.6mm blank is drawn to 15.45mm, with a drawing rate of 1.9%.

[0069] S6. Rolling: The above-mentioned drawn blank is rolled to a thickness of 6.5mm. The roll roughness during the rolling process is Ra1-2, and the rolling speed is 15m / min.

[0070] S7. Third cold working: The above blank is drawn using a polycrystalline die with a diameter of 5.5mm*18.2mm. The angle of the die opening is 10° (a smaller opening angle will cause the blank to scrape against the edge of the die during the drawing process). The length of the sizing strip is controlled at 5-7mm (if the sizing strip is too long, it will increase friction; if the sizing strip is too small, it will be difficult to guarantee the finished product size).

[0071] S8. Aging Annealing: The 5.5*18.2mm blank is annealed in a horizontal bright annealing furnace at a temperature of 450℃ for 5 hours.

[0072] S9. Finished Product Drawing: A combined drawing machine is used to draw the finished product using a 5*18 polycrystalline die. To ensure product dimensions and straightness, the length of the sizing band of the drawing die is controlled at 5-7mm, the R-angle deviation is controlled at ±0.02mm, and the drawing opening angle is 6°.

[0073] Example 4: The chromium-zirconium copper flat prism provided in this example, based on a mass percentage of 100%, includes the following components: Cr: 0.9%, Zr: 0.06%, with the remainder being copper and unavoidable impurities. The finished product size is 7mm*16mm.

[0074] The preparation method provided in this embodiment includes the following steps:

[0075] S1. Melting: Prepare the materials according to the required composition. Add an appropriate amount of oxygen-free copper rod to the upward drawing furnace, introduce argon gas and heat until the oxygen-free rod is completely melted. Then, start the automatic feeding of oxygen-free rod, controlling the feeding rate at 220 kg / h. Stop feeding oxygen-free rod when the copper liquid is 20 cm from the edge of the crucible. Add the copper-chromium alloy and copper-zirconium alloy according to the specified ratio. Finally, maintain the temperature at 1250℃ and hold for 20 minutes. After the composition is tested and found to be qualified, proceed with the production of Φ28mm upward drawing blanks. During the subsequent drawing process, oxygen-free copper rods, copper-chromium, and zirconium cored wires are automatically fed according to the predetermined design composition. The composition of the furnace liquid is tested every 30 minutes to ensure that the composition of the upward drawing blank is qualified. The cooling water pressure is 0.3 MPa and the drawing speed is 0.77 mm / s to obtain a Φ28mm diameter upward drawing chromium-zirconium copper blank.

[0076] S2. First cold working: Roll the 28mm blank to 23mm. The subsequent drawing process is carried out with a diameter reduction of 1-2mm per pass, drawing to 17.5mm. Finally, peel off the skin to 16mm to ensure that the surface crystal texture is completely removed, and then draw to 15.05mm.

[0077] S3. Solution treatment: The 15.05mm blank is solution treated at a temperature of 940℃. The conductivity of the blank after solution treatment is controlled at 35-45% IACS, and the hardness HV5 after solution treatment is 50-70.

[0078] S4. Pickling: The above-mentioned solution-treated blanks are pickled. After pickling, the surface of the blanks is free from oxidation, dents, sand holes and other defects.

[0079] S5. Second cold working: The 15.05mm blank is drawn to 14.9mm, with a drawing rate of 2.0%.

[0080] S6. Rolling: The above-mentioned drawn blank is rolled to a thickness of 8.5mm. The roll roughness during the rolling process is Ra1-2, and the rolling speed is 15m / min.

[0081] S7. Third cold working: The above blank is drawn using a polycrystalline die with a diameter of 7.5mm*16.2mm. The angle of the die opening is 10° (a smaller opening angle will cause the blank to scrape against the edge of the die during the drawing process). The length of the sizing strip is controlled at 5-7mm (if the sizing strip is too long, it will increase friction; if the sizing strip is too small, it will be difficult to guarantee the finished product size).

[0082] S8. Aging Annealing: The 7.5*16.2mm blank is annealed in a horizontal bright annealing furnace at a temperature of 450℃ for 5 hours.

[0083] S9. Finished Product Drawing: A combined drawing machine is used to draw the finished product using a 7*16 polycrystalline die. To ensure product dimensions and straightness, the length of the sizing band of the drawing die is controlled at 5-7mm, the R-angle deviation is controlled at ±0.02mm, and the drawing opening angle is 6°.

[0084] Example 5: The chromium-zirconium copper flat prism provided in this example, based on a mass percentage of 100%, includes the following components: Cr: 0.6%, Zr: 0.06%, with the remainder being copper and unavoidable impurities. The finished product size is 4.8mm*22mm.

[0085] The preparation method provided in this embodiment includes the following steps:

[0086] S1. Smelting: Prepare the materials according to the required composition. Add an appropriate amount of oxygen-free copper rod to the upward drawing furnace, introduce argon gas and heat until the oxygen-free rod is completely melted. Then, start the automatic feeding of oxygen-free rod, and control the feeding speed at 220Kg / h. Stop feeding oxygen-free rod when the copper liquid is 20cm away from the edge of the crucible. Add copper-chromium alloy and copper-zirconium alloy according to the specified ratio. Finally, maintain the temperature at 1250℃ and hold for 20min. After the composition is tested and found to be qualified, produce Φ28mm upward drawing blank. During the subsequent drawing process, oxygen-free copper rod, copper-chromium, and zirconium cored wire are automatically fed according to the predetermined design composition. The composition of the furnace liquid is tested every 30min to ensure that the composition of the upward drawing blank is qualified. The cooling water pressure is 0.3MPa and the drawing speed is 0.77mm / s to obtain a Φ28mm diameter upward drawing chromium-zirconium copper blank.

[0087] S2. First cold working: Roll the 28mm blank to 23mm. The subsequent drawing process is carried out with a diameter reduction of 1-2mm per pass, drawing to 20.5mm. Finally, peel off the skin to 19mm to ensure that the surface crystal texture is completely removed, and then draw to 18.1mm.

[0088] S3. Solution treatment: The 18.1mm blank is solution treated at a temperature of 950℃. The conductivity of the blank after solution treatment is controlled at 35-45% IACS, and the hardness HV5 after solution treatment is 50-70.

[0089] S4. Pickling: The above-mentioned solution-treated blanks are pickled. After pickling, the surface of the blanks is free from oxidation, dents, sand holes and other defects.

[0090] S5. Second cold working: The above 18.1mm blank is drawn to 18.0mm, with a drawing rate of 1.1%.

[0091] S6. Rolling: The above-mentioned drawn blank is rolled to a thickness of 6.3mm. The roll roughness during the rolling process is Ra1-2, and the rolling speed is 15m / min.

[0092] S7. Third cold working: The above blank is drawn using a polycrystalline die with a diameter of 5.3mm*22.2mm. The angle of the die opening is 10° (a smaller opening angle will cause the blank to scrape against the edge of the die during the drawing process). The length of the sizing strip is controlled at 5-7mm (if the sizing strip is too long, it will increase friction; if the sizing strip is too small, it will be difficult to guarantee the finished product size).

[0093] S8. Aging Annealing: The 5.3*22.2mm blank is annealed in a horizontal bright annealing furnace at a temperature of 450℃ for 5 hours.

[0094] S9. Finished Product Drawing: A combined drawing machine is used to draw the finished product using a 4.8*22 polycrystalline die. To ensure product size and straightness, the length of the sizing strip of the drawing die is controlled at 5-7mm, the R-angle deviation is controlled at ±0.02mm, and the drawing opening angle is 6°.

[0095] Example 6: The chromium-zirconium copper flat prism provided in this example, based on a mass percentage of 100%, includes the following components: Cr: 0.9%, Zr: 0.03%, with the remainder being copper and unavoidable impurities. The finished product size is 6mm*21mm.

[0096] The preparation method provided in this embodiment includes the following steps:

[0097] S1. Melting: Prepare the materials according to the required composition. Add an appropriate amount of oxygen-free copper rod to the upward drawing furnace, introduce argon gas and heat until the oxygen-free rod is completely melted. Then, start the automatic feeding of oxygen-free rod, controlling the feeding rate at 220 kg / h. Stop feeding oxygen-free rod when the copper liquid is 20 cm from the edge of the crucible. Add the copper-chromium alloy and copper-zirconium alloy according to the specified ratio. Finally, maintain the temperature at 1250℃ and hold for 20 minutes. After the composition is tested and found to be qualified, proceed with the production of Φ28mm upward drawing blanks. During the subsequent drawing process, oxygen-free copper rods, copper-chromium, and zirconium cored wires are automatically fed according to the predetermined design composition. The composition of the furnace liquid is tested every 30 minutes to ensure that the composition of the upward drawing blank is qualified. The cooling water pressure is 0.3 MPa and the drawing speed is 0.77 mm / s to obtain a Φ28mm diameter upward drawing chromium-zirconium copper blank.

[0098] S2. First cold working: Roll the 28mm blank to 23mm. The subsequent drawing process is carried out with a diameter reduction of 1-2mm per pass, drawing to 20.5mm. Finally, peel off the skin to 19mm to ensure that the surface crystal texture is completely removed, and then draw to 17.9mm.

[0099] S3. Solution treatment: The 17.9mm blank is solution treated at a temperature of 940℃. The conductivity of the blank after solution treatment is controlled at 35-45% IACS, and the hardness HV5 after solution treatment is 50-70.

[0100] S4. Pickling: The above-mentioned solution-treated blanks are pickled. After pickling, the surface of the blanks is free from oxidation, dents, sand holes and other defects.

[0101] S5. Second cold working: The 17.9mm blank is drawn to 17.75mm, with a drawing rate of 1.7%.

[0102] S6. Rolling: The above-mentioned drawn blank is rolled to a thickness of 7.5mm. The roll roughness during the rolling process is Ra1-2, and the rolling speed is 15m / min.

[0103] S7. Third cold working: The above blank is drawn using a polycrystalline die of 6.5mm*21.2mm. The flared angle of the die is 10° (a smaller flared angle will cause the blank to scrape against the edge of the die during the drawing process). The length of the sizing strip is controlled at 5-7mm (if the sizing strip is too long, it will increase friction; if the sizing strip is too small, it will be difficult to guarantee the finished product size).

[0104] S8. Aging Annealing: The 6.5*21.2mm blank is annealed in a horizontal bright annealing furnace at a temperature of 450℃ for 5 hours.

[0105] S9. Finished Product Drawing: A combined drawing machine is used to draw the finished product using a 6*21 polycrystalline die. To ensure product size and straightness, the length of the sizing band of the drawing die is controlled at 5-7mm, the R-angle deviation is controlled at ±0.02mm, and the drawing opening angle is 6°.

[0106] Comparative Example 1: Chromium-zirconium-copper flat wafer, based on 100% by mass, includes the following components: Cr: 1.2%, Zr: 0.08%, with the remainder being copper and unavoidable impurities. The finished product size is 4mm*20mm. The preparation process is the same as in Example 1.

[0107] Comparative Example 2: The preparation process is the same as in Example 2, the main difference being that after solution treatment, no secondary cold working was performed before direct rolling.

[0108] Comparative Example 3: The preparation process was the same as in Example 3, with the main difference being the secondary cold working in S5: the 15.6mm blank was drawn to 15.3mm, with a drawing rate of 3.8%;

[0109] Comparative Example 4: The composition and smelting process are the same as in Example 4, the main difference being that the finished product is directly drawn after the blank has been solution-treated. The subsequent specific steps are as follows:

[0110] S2 First cold working: Roll the 28mm blank to 23mm, and then draw it to 21.5mm with a diameter reduction of 1-2mm per pass. Finally, peel it to 20mm to ensure that the surface crystal texture is completely removed, and then draw it to 19mm.

[0111] S3 Solution Treatment: The 19mm blank is solution treated at a temperature of 940℃. The conductivity of the blank after solution treatment is controlled at 35-45% IACS, and the hardness HV5 after solution treatment is 50-70.

[0112] S4 pickling: The above-mentioned solution-treated blanks are pickled. After pickling, the surface of the blanks is free from oxidation, dents, sand holes and other defects.

[0113] S5 Second Cold Working: The above-mentioned 19mm solution-treated blank is directly drawn through a die, with the thickness reduced by 2mm and the width reduced by 0.4-0.5mm in each drawing pass (the specific drawing process is: 19-17*18.5-15*18-13*17.6-11*17.2-9*16.8), and drawn to 9*16.8.

[0114] S6 Third cold working: The above 9*16.8 blank is drawn using a polycrystalline die with a diameter of 7.5mm*16.2mm. The flared angle of the die is 10° (a smaller flared angle will cause the blank to scrape against the edge of the die during the drawing process). The length of the sizing strip is controlled at 5-7mm (if the sizing strip is too long, it will increase friction; if the sizing strip is too small, it will be difficult to guarantee the finished product size).

[0115] S7 Aging Annealing: The 7.5*16.2mm blank was annealed in a horizontal bright annealing furnace at a temperature of 450℃ for 5 hours.

[0116] S8 Finished Product Drawing: A combined drawing machine is used to draw the finished product using a 7*16 polycrystalline die. To ensure product size and straightness, the length of the sizing band of the drawing die is controlled at 5-7mm, the R-angle deviation is controlled at ±0.02mm, and the drawing opening angle is 6°.

[0117] Performance Analysis: The chemical compositions of the examples and comparative examples are summarized in Table 1; the theoretical and measured results of the rolling thickness and width of the examples and comparative examples are summarized in Table 2; the feasibility of the empirical formula is verified by summarizing the texture type and texture area after secondary cold working of the examples and comparative examples in Table 3; the product qualification rates of the comparative examples and examples are shown in Table 4; the copper alloys prepared in the examples and comparative examples are tested for properties such as grain size, tensile strength, electrical conductivity, and hardness, and the results are shown in Table 5. The specific test methods are as follows:

[0118] Grain size detection: Grain size and phase ratio testing shall be conducted in accordance with GB / T 6394-2017 Method for determination of average grain size of metals, wherein the grain size testing method is the intercept method and the phase ratio testing method is the area method.

[0119] The detection of second-phase precipitation and texture: The size of the second phase was determined by observing the microstructure of the sample under scanning electron microscopy and transmission electron microscopy. Based on the observation results, the average grain size and quantity of the second phase precipitated in the alloy were calculated, and its number density and the area ratio of the precipitated phase were calculated respectively. Texture testing was performed using EBSD on electropolished chromium-zirconium-copper samples. The texture type and area quantity were inferred from the Kikuchi pattern obtained by reflection.

[0120] Tensile strength and yield strength: tested in accordance with GB / T228.1-2021 "Metallic materials - Tensile testing - Part 1: Test at room temperature";

[0121] Conductivity: Tested according to GB / T32791-2016 "Eddy Current Test Method for Conductivity of Copper and Copper Alloys".

[0122] Hardness: The testing standard is GB / T4340.1-2009 Metals Vickers Hardness Test - Part 1: Test Method.

[0123] Dimensional tolerances: The inspection standard is GB / T5584.1-2009 Electrical flat wires of copper, aluminum and their alloys - Part 1: General requirements.

[0124] Pass rate:

[0125] According to customer and standard requirements: product elongation > 10%, tensile strength > 500MPa, hardness HB > 145, conductivity > 85%IACS; product dimensional tolerances meet standard requirements.

[0126] Table 1. Comparison of chemical composition between the embodiments of the present invention and the comparative examples.

[0127]

[0128] Table 2 Verification of the empirical formulas for solution treatment dimensions and width spread during the rolling process of this invention

[0129]

[0130] Table 3. Goss texture as a percentage of surface depth and the proportion of Goss and Cube textures within that depth after the second cold working.

[0131]

[0132] Table 4. Product qualification rate of the examples and comparative examples

[0133]

[0134] Table 5. Comparison of various performance characteristics between the embodiments of the present invention and the comparative examples.

[0135]

[0136] As can be seen from the data above, i.e., Tables 1 to 5, the actual width difference between the theoretical width and the actual width in Examples 1-6 is small. Therefore, the empirical formulas for solution size and finished product, as well as the empirical formulas for rolling width and rolling thickness, are feasible. However, as can be seen from Comparative Examples 1, 2, and 3, changes in composition and a small amount of secondary cold deformation can cause the width to deviate from the empirical formula, resulting in the uncontrollability of rolling width and the inability to solidify the process. At the same time, the two rolling deformations can sufficiently refine the grains, which is beneficial to the fine and dispersed distribution of the second term in the aging process. Without rolling, as can be seen from Comparative Example 4, the proportion of fine grains is significantly reduced, which is not conducive to subsequent aging strengthening. Therefore, the product qualification rate can be seen from the product qualification rate. In the examples, the product qualification rate can be controlled above 90%. However, in Comparative Example 1, due to the change in composition, the rolling width could not meet the requirements. At the same time, the increased Cr content led to a decrease in product plasticity, resulting in product cracking during processing. In Comparative Example 2, the lack of secondary cold working resulted in uneven rolling blank width, causing most of the finished products to be scrapped due to poor tolerances. In Comparative Example 3, the excessive secondary cold working resulted in the rolling width not meeting the requirements for subsequent finished product drawing, causing all products to be scrapped. In Comparative Example 4, the insufficient grain refinement in the process route resulted in the finished products failing to meet the requirements for tensile strength and elongation, leading to all products being scrapped.

Claims

1. A method of producing a chromium zirconium copper tabular ingot, characterized by, The process flow of the preparation method is as follows: batching → upward continuous casting → first cold working → solution treatment → second cold working → rolling → third cold working → aging annealing → finished product drawing; The process involves batching, smelting, and continuous casting of the chromium-zirconium-copper flatbread according to the mass percentages of each component. The mass percentage composition of the chromium-zirconium-copper flatbread is Cr: 0.6-0.9 wt%, Zr: 0.03-0.06 wt%, with the balance being Cu and unavoidable impurities. The amount of material processed in the second cold working is 1%-2.5%; Based on the width and thickness of the chromium-zirconium copper flattened sheet, the rolling width L after rolling and the blank size D after solution treatment are obtained as follows: L=A*(Dd)+D D = (1.1a + 2b + 7.1) / 3.11 Where A is a constant, with a value of 0.5-0.55, a is the thickness of the chromium-zirconium-copper flat sheet, b is the width of the chromium-zirconium-copper flat sheet, d is the rolling thickness, and D is the blank size after solution treatment.

2. The method of claim 1, wherein the chromium zirconium copper tabular crystal is prepared by the steps of: The rolling thickness is the thickness of the chromium-zirconium copper flat strip + (1.2-1.5 mm), and the rolling width is the width of the chromium-zirconium copper flat strip + (2-3 mm).

3. The method of claim 1, wherein the chromium zirconium copper tabular crystal is prepared by the steps of: After the third cold working, the thickness of the blank is the thickness of the chromium zirconium copper flat square plus (0.45-0.55mm), and the width is the width of the chromium zirconium copper flat square plus (0.18-0.25mm).

4. The method for preparing chromium-zirconium-copper flat prisms according to claim 1, characterized in that, In the microstructure at a depth of 0-0.15 mm from the surface of the blank after the second cold working, the area ratio of Cube texture and Goss texture is more than 60%.

5. The method for preparing chromium-zirconium-copper flat prisms according to claim 1, characterized in that, The initial cold working process involves a processing volume of ≥35%.

6. The method for preparing chromium-zirconium-copper flat prisms according to claim 1, characterized in that, The solution temperature is 930-950℃, and the grain size after solution treatment is 0.02-0.04mm.

7. The method for preparing chromium-zirconium-copper flat prisms according to claim 1, characterized in that, The aging annealing temperature is 450-470℃, and the aging time is 4-7 hours.

8. A chromium-zirconium-copper flat prism, characterized in that, The chromium-zirconium-copper tabular grain is prepared by the method according to any one of claims 1-7, wherein the second phase in the chromium-zirconium-copper tabular grain structure is a Cr and Zr phase, and the number of the second phase distributed in the chromium-zirconium-copper tabular grain structure is 50000 / mm 2 .

9. The chromium-zirconium-copper flat prism according to claim 8, characterized in that, The thickness of the chromium-zirconium copper flat sheet is >2mm, the width is >15mm, and the width-to-thickness ratio is 2-8.

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