A high-performance copper-chromium-zirconium alloy cast rod and wire and its preparation method

Abstract

This invention discloses a high-performance copper-chromium-zirconium alloy cast rod and wire, and their preparation method, relating to the field of metal material processing. The alloy cast rod comprises Cr, Zr, and R, with the balance being copper and unavoidable impurities, wherein R is Mg and / or Zn, etc. After completely melting cathode copper, copper-chromium master alloy, copper-zirconium master alloy, copper-magnesium master alloy, and / or copper-zinc master alloy, and holding it at a heat treatment, it is then subjected to vacuum downward continuous casting, using a "pull + stop + retraction" method to obtain the cast rod. This application achieves high-quality and industrialized production of cast rods through vacuum downward continuous casting. The addition of elements such as Mg or Zn effectively improves the viscosity of the copper melt, reducing the resistance of copper alloy downward continuous casting. Simultaneously, the "pull + stop + retraction" method prevents the cast rod from breaking or thermally cracking during downward traction. The final cast rod has a uniform microstructure and small grain size, achieving good mechanical properties and machinability, meeting application performance requirements.

Description

Technical Field

[0001] This invention relates to the field of metal material processing, and in particular to a high-performance copper-chromium-zirconium alloy cast rod and wire and its preparation method. Background Technology

[0002] Cu-Cr-Zr alloy is a typical structural-functional integrated material, a precipitation-strengthened alloy containing a large amount of metastable Cr-rich precipitates. Due to its high strength and good electrical and thermal conductivity, it is often used in electronics, power, aircraft carriers, aerospace, machinery, transportation, and defense fields, such as electrified railway contact lines, lead frames for large-scale integrated circuits, conductive devices for aircraft carriers and spacecraft, as well as military communication cables and aviation cables. However, because Cr and Zr have a high affinity for oxygen, the alloy is prone to burn-off during smelting, making large-scale continuous production impossible and resulting in unstable performance. Industrial production often uses non-vacuum continuous casting to prepare copper-chromium-zirconium alloy rods. Even with strict control of process parameters, it is difficult to guarantee a uniform microstructure and excellent surface quality in rods prepared by this method.

[0003] Vacuum melting can effectively solve these problems. Vacuum melting mainly includes vacuum induction melting, vacuum downward casting, vacuum horizontal casting, and directional solidification. While vacuum induction melting is simple and easy to operate, it is only suitable for small-batch casting experiments and is difficult to implement in industrial production. Directional solidification technology is also unsuitable for industrial production. Downward casting and horizontal casting can both be used for industrial production. Relatively speaking, downward casting produces higher quality cast rods, which is more conducive to the preparation of fine wires.

[0004] Given the current performance requirements of Cu-Cr-Zr alloy microwires after tubular annealing (tensile strength ≥480MPa, conductivity ≥78% IACS, elongation after annealing ≥8%), it is necessary to achieve a hard-state tensile strength ≥700MPa and conductivity ≥70% IACS when drawn to a wire diameter of 0.16mm, while also ensuring a service length ≥1500m. However, the presence of Zr in the Cu-Cr-Zr alloy significantly increases the viscosity of the copper solution, which increases the resistance to vacuum continuous casting of the copper alloy, easily leading to traction failure. Therefore, there is an urgent need to develop a semi-continuous production technology for Cu-Cr-Zr alloy casting rods with high quality to meet production demands. Summary of the Invention

[0005] This invention provides a high-performance copper-chromium-zirconium alloy cast rod and wire, and a method for preparing the same, for producing Cu-Cr-Zr alloys that are prone to oxidation and segregation, thus solving the problems of traction failure or insufficient quality of cast rods in the current industrial production of Cu-Cr-Zr alloys.

[0006] To address the aforementioned technical problems, one objective of this invention is to provide a method for preparing a high-performance copper-chromium-zirconium alloy cast rod. The alloy cast rod comprises 0.2wt%-1.5wt% Cr, 0.02wt%-0.15wt% Zr, and 0.01wt%-0.05wt% R, with the balance being copper and unavoidable impurities, wherein R is Mg and / or Zn. The preparation method includes the following steps:

[0007] (1) Under an inert gas atmosphere, after melting the cathode copper, copper-chromium master alloy and copper-zirconium master alloy, copper-magnesium master alloy and / or copper-zinc master alloy are added. After complete melting, electromagnetic stirring is performed, a covering agent is added, and the copper liquid is kept warm.

[0008] (2) Perform vacuum casting, turn on the cooling water and air cooling device at the outlet of the traction pipe, turn on the traction system and take-up device. The whole process is carried out in the "traction + stop + retraction" mode. The stop time is 0.1-0.2s, the ratio of stop to pull time is 3:1 or more, and the ratio of stop to retraction time is 5:1 or more. In the initial stage, the traction is carried out at a speed of 3mm / s for 50-200mm, and then the speed is increased to 5-7mm / s. The retraction speed is kept constant at 2mm / s. The copper liquid solidifies into a solid in the crystallizer. The traction is stabilized until the traction is completed and the casting rod is obtained.

[0009] By adopting the above scheme, this application enables the industrial production of cast rods through vacuum downward casting. The vacuum oxygen-free environment avoids the oxidation reaction between Cr and Zr elements in the copper-chromium-zirconium alloy and oxygen, which would affect the purity and performance of the alloy. At the same time, vacuum downward casting produces cast rods with higher quality compared to vacuum horizontal casting. Since the presence of Zr in the alloy significantly increases the viscosity of the copper solution, this application effectively improves the viscosity of the copper solution by adding elements such as Mg or Zn to the copper-chromium-zirconium alloy, reducing the resistance of the copper alloy downward casting. In addition, the "traction + stop + retraction" traction method can prevent the cast rod from breaking or developing thermal cracks during the downward traction process. Furthermore, trace amounts of Mg and Zn elements have minimal impact on the mechanical and electrical properties of the alloy. The final cast rod has a uniform microstructure and small grains, exhibiting high tensile strength and electrical conductivity, and achieving good mechanical properties and machinability, thus meeting application performance requirements.

[0010] As a preferred embodiment, in step (1), under an inert gas atmosphere, cathode copper is added and melted at a temperature above 1050°C, then an inert gas is introduced for protection, then a copper-chromium master alloy is added, the temperature is raised to 1150-1250°C, then a copper-zirconium master alloy is added, the temperature is raised to 1250-1350°C, then a copper-magnesium master alloy and / or a copper-zinc master alloy are added, and after complete melting, electromagnetic stirring is performed, a covering agent is added, and the temperature is maintained at 1200-1300°C for 10-30 minutes.

[0011] By adopting the above scheme, the present invention uses a method of adding different intermediate alloys sequentially, and melting the different intermediate alloys at a specific temperature while performing electromagnetic stirring, which can effectively prevent component segregation, make the cast rod structure more uniform, and refine the grains.

[0012] As a preferred embodiment, in step (1), the covering agent is cryolite.

[0013] As a preferred embodiment, in step (2), the crucible and crystallizer used for vacuum casting are independent and are internally coated with boron nitride, and nested with 5-10mm of boron nitride or 5-10mm of high-purity molybdenum-titanium alloy.

[0014] By adopting the above scheme, the present invention treats the crucible and crystallizer with boron nitride, which not only ensures good heat conduction, but also effectively prevents Cr and Zr from reacting with graphite to form intermetallic compounds, thus avoiding uneven composition. It also reduces the friction of the molten metal when entering the crystallizer, which is beneficial to the implementation of the traction process and reduces the occurrence of rough surface and easy breakage of the casting rod.

[0015] As a preferred option, in step (2), the pressure of vacuum casting is less than 0.1 Pa.

[0016] As a preferred option, in step (2), the diameter of the graphite crystallizer is 12.5-16 mm.

[0017] As a preferred option, in step (2), the cooling device has a water flow rate of 500-4000 L / h and a circulating water temperature of 25-30℃.

[0018] To address the aforementioned technical problems, a second objective of this invention is to provide a high-performance copper-chromium-zirconium alloy cast rod.

[0019] To address the aforementioned technical problems, a third objective of this invention is to provide a method for preparing high-performance copper-chromium-zirconium alloy wire, comprising the following steps:

[0020] (1) The cast rod is continuously extruded to 6-10 mm at an extrusion temperature of 600-800℃, and then the extruded rod is continuously drawn to 2-4 mm at a drawing rate of 17-34 m / min to obtain a wire blank.

[0021] (2) Heat treatment is performed on the wire blank at a temperature of 450-600℃. After cooling, a second continuous drawing process is performed to 0.1-0.2mm at a speed of 300-500m / min to obtain the wire.

[0022] As a preferred embodiment, in step (1), continuous extrusion is performed using a preheated pure copper rod as the extruder. The preheating temperature of the pure copper extrusion extruder is 350-500℃, the extrusion temperature is 600-800℃, the extrusion roller speed is 6-10 revolutions / minute, and the gap between the extrusion roller and the die cavity is controlled to be 0.3-0.6.

[0023] To address the aforementioned technical problems, the fourth objective of this invention is to provide a high-performance copper-chromium-zirconium alloy wire.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. This application produces cast rods using vacuum downward casting, which enables high-quality and industrialized production. Vacuum oxygen isolation prevents oxidation reactions of Cr and Zr elements, thus avoiding their impact on the purity and performance of the alloy. Adding elements such as Mg or Zn can effectively improve the viscosity of the molten copper and reduce the resistance of the copper alloy downward casting. At the same time, the "traction + stop + retraction" traction method prevents the cast rod from breaking or developing thermal cracks during the downward traction process. The final cast rod has a uniform microstructure and small grains, achieving good mechanical properties and machinability, which can meet the application performance requirements.

[0026] 2. The present invention adopts the method of adding different intermediate alloys one after another, and the different intermediate alloys need to be melted at a specific temperature while being electromagnetically stirred. This can effectively prevent component segregation, make the structure of the cast rod more uniform, and refine the grains.

[0027] 3. The present invention employs boron nitride treatment on the crucible and crystallizer, which not only ensures good heat conduction, but also effectively prevents Cr and Zr from reacting with graphite to form intermetallic compounds. It also reduces the friction of the molten metal when entering the crystallizer, which is beneficial to the implementation of the traction process and reduces the occurrence of rough surface and easy breakage of the casting rod. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the graphite crucible used in this invention.

[0029] Figure 2 This is a schematic diagram of the structure of the graphite crystallizer used in this invention;

[0030] Figure 3 : This refers to the crystal images of the cast rod obtained in step (2) of the preparation method of Embodiment 1 and Comparative Example 1 of the present invention, and the traction situation of the cast rod prepared in Comparative Examples 1-2 (Note: a- Crystal image of the cast rod of Embodiment 1; b- Crystal image of the cast rod of Comparative Example 1; c- Cast rod of Comparative Example 2 that has thermal cracks due to traction; d- Cast rod of Embodiment 1 that has been successfully tractioned without thermal cracks). Detailed Implementation

[0031] 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.

[0032] This application describes a vacuum bottom-casting system for copper-chromium-zirconium alloys, comprising a melting vacuum system, a molten metal holding system, a bottom-casting system, and other auxiliary systems. The bottom-casting system includes a graphite crucible, a vacuum induction heating device, a circulating water cooling system, a graphite crystallizer, and a traction device containing a traction rod. The graphite crucible has the following structure: Figure 1 As shown, selecting a crucible with a nested boron nitride layer of 0.5 mm can effectively prevent the reaction of Cr and Zr with graphite to form intermetallic compounds, thus avoiding compositional inhomogeneity. It also prevents increased friction when the molten metal enters the crystallizer, which would hinder the traction process. The structure of the graphite crystallizer is as follows: Figure 2 As shown, the graphite crystallizer uses an internally sprayed boron nitride coating for traction, with a diameter of 12.5-16mm, which ensures good heat conduction, reduces traction resistance, and reduces the occurrence of problems such as rough surface of the cast rod and easy breakage.

[0033] Example 1

[0034] A high-performance copper-chromium-zirconium alloy wire, comprising 0.5 wt% Cr, 0.05 wt% Zr, 0.05 wt% Mg, with the balance being copper, has a wire diameter of 0.16 mm. Its preparation method includes the following steps:

[0035] (1) The cathode copper (99.99% purity), Cu10Cr master alloy (10wt% Cr, impurity content ≤0.1%), Cu40Zr (40wt% Cr, impurity content ≤0.1%), and Cu5Mg (5wt% Mg, impurity content ≤0.1%) master alloys were mixed according to their alloy composition. Cr and Zr were added at a 25% burn-off ratio, Mg was added at a 40% burn-off ratio, and the burn-off ratio of the cathode copper was calculated as 3%. The vacuum was then evacuated to 4×10⁻⁶. -2 The process involves heating the furnace to approximately 1080℃ to melt the cathode copper, then introducing a suitable amount of argon gas for protection, followed by the addition of Cu10Cr master alloy. Argon gas is then introduced until the furnace pressure is equivalent to atmospheric pressure. The furnace is then heated to 1200℃ and Cu40Zr master alloy is added. The furnace is then heated to 1300℃ and Cu5Mg master alloy is added. After the master alloy has completely melted, the furnace is electromagnetically stirred, cryolite is added as a covering agent, and the furnace is held at 1280℃ for 20 minutes to allow the solution to fully diffuse.

[0036] (2) Vacuum casting is carried out with a pressure of less than 0.1 Pa. Molten steel is injected vertically downward into the crystallizer placed below. The casting rod moves downward. The cooling water and air cooling device at the outlet of the traction pipe are turned on with a flow rate of 800 L / h. The water tank temperature is maintained at 28±2℃. The traction system and take-up device are turned on. The whole process is carried out in the manner of "traction + stop + retraction". The stop time is 0.1 s, the ratio of stop to pull time is 3:1, and the ratio of stop to retraction time is 5:1. In the initial stage, the traction is carried out at a speed of 3 mm / s for 100 mm. Then the traction speed is increased to 5 mm / s, and the retraction speed is kept constant at 2 mm / s. The copper liquid solidifies into a solid in the graphite crystallizer. The traction is stabilized until the traction is completed, and a high-quality casting rod with a wire diameter of 16 mm is obtained without thermal cracking or breakage.

[0037] (3) The obtained 16mm cast rod is continuously extruded. The extrusion is carried out with a preheated pure copper rod as the extrusion head. The pure copper extrusion head is preheated at 400℃ for 3 hours. The extrusion temperature is 700℃ and the extrusion wheel speed is 7 revolutions / minute. The gap between the extrusion wheel and the die cavity is controlled at 0.5mm. The cast rod is extruded from 16mm wire diameter to 8mm. Then, the extrusion rod is pulled to 2.6mm wire diameter through continuous drawing technology. As the wire diameter decreases, the drawing speed gradually increases from 17m / min to 34m / min.

[0038] (4) The 2.6 mm diameter wire blank is placed in an air quenching furnace for heat treatment. The heat treatment process is to keep it at 500℃ for 6 hours and then cool it with the furnace. The resulting semi-soft wire blank is then continuously drawn at a drawing speed of 400 m / min to obtain 0.16 mm wire.

[0039] Example 2

[0040] A high-performance copper-chromium-zirconium alloy wire, comprising 1 wt% Cr, 0.2 wt% Zr, 0.05 wt% Zn, with the balance being copper, has a wire diameter of 0.16 mm. Its preparation method includes the following steps:

[0041] (1) The cathode copper (99.99% purity), Cu10Cr master alloy (10wt% Cr, impurity content ≤0.1%), Cu40Zr (40wt% Cr, impurity content ≤0.1%), and Cu10Zn (10wt% Zn, impurity content ≤0.1%) master alloy were mixed according to their alloy composition. Cr and Zr were added at a 25% burn-off ratio, Zn was added at a 30% burn-off ratio, and the burn-off ratio of the cathode copper was calculated as 3%. The vacuum was then evacuated to 4×10⁻⁶. -2The process involves heating the furnace to above 1080℃ to melt the cathode copper, then introducing a suitable amount of argon gas for protection, followed by the addition of Cu10Cr master alloy. Argon gas is then introduced until the furnace pressure is equivalent to atmospheric pressure. The furnace is then heated to 1150℃ and Cu40Zr master alloy is added. The furnace is then heated to 1250℃ and Cu10Zn master alloy is added. After the master alloy has completely melted, the furnace is electromagnetically stirred, cryolite is added as a covering agent, and the furnace is held at 1250℃ for 30 minutes to allow the solution to fully diffuse.

[0042] (2) Vacuum casting is carried out with a pressure of less than 0.1 Pa. The cooling water and air cooling device at the outlet of the traction pipe are turned on, with a flow rate of 2000 L / h. The water tank temperature is maintained at 28±2℃. The traction system and take-up device are turned on. The whole process is carried out in the manner of "traction + stop + retraction". The stop time is 0.1 s, the ratio of stop to pull time is 4:1, and the ratio of stop to retraction time is 5:1. In the initial stage, 100 mm is pulled at a speed of 3 mm / s. Then the traction speed is increased to 7 mm / s, and the retraction speed is kept constant at 2 mm / s. The copper liquid solidifies into a solid in the graphite crystallizer. The traction is stabilized until the traction is completed, and a high-quality cast rod with a wire diameter of 16 mm is obtained without thermal cracking or breakage.

[0043] (3) The obtained 16mm cast rod is continuously extruded. The extrusion is carried out with a preheated pure copper rod as the extrusion head. The pure copper extrusion head is preheated at 380℃ for 4 hours. The extrusion temperature is 600℃ and the extrusion wheel speed is 6 revolutions / minute. The gap between the extrusion wheel and the die cavity is controlled at 0.5mm. The cast rod is extruded from 16mm wire diameter to 8mm. Then, the extrusion rod is pulled to 2.6mm wire diameter through continuous drawing technology. As the wire diameter decreases, the drawing speed gradually increases from 17m / min to 34m / min.

[0044] (4) The 2.6 mm diameter wire blank is placed in an air quenching furnace for heat treatment. The heat treatment process is to keep it at 550℃ for 5 hours and then cool it with the furnace. The resulting semi-soft wire blank is then continuously drawn at a drawing speed of 400 m / min to obtain 0.16 mm wire.

[0045] Example 3

[0046] A high-performance copper-chromium-zirconium alloy wire, comprising 0.8 wt% Cr, 0.1 wt% Zr, 0.03 wt% Mg, with the balance being copper, has a wire diameter of 0.16 mm. Its preparation method includes the following steps:

[0047] (1) The cathode copper (99.99% purity), Cu10Cr master alloy (10wt% Cr, impurity content ≤0.1%), Cu40Zr (40wt% Cr, impurity content ≤0.1%), and Cu5Mg (5wt% Mg, impurity content ≤0.1%) master alloys were mixed according to their alloy composition. Cr and Zr were added at a 25% burn-off ratio, Mg was added at a 40% burn-off ratio, and the burn-off ratio of the cathode copper was calculated as 3%. The vacuum was then evacuated to 4×10⁻⁶. -2 The process involves heating the furnace to approximately 1080℃ to melt the cathode copper, then introducing a suitable amount of argon gas for protection, followed by the addition of Cu10Cr master alloy. Argon gas is then introduced until the furnace pressure is equivalent to atmospheric pressure. The furnace is then heated to 1200℃ and Cu40Zr master alloy is added. The furnace is then heated to 1250℃ and Cu5Mg master alloy is added. After the master alloy has completely melted, the furnace is electromagnetically stirred, cryolite is added as a covering agent, and the furnace is held at 1250℃ for 20 minutes to allow the solution to fully diffuse.

[0048] (2) Vacuum casting is carried out with a pressure of less than 0.1 Pa. The cooling water and air cooling device at the outlet of the traction pipe are turned on, with a flow rate of 3000 L / h. The water tank temperature is maintained at 28±2℃. The traction system and take-up device are turned on. The whole process is carried out in the manner of "traction + stop + retraction". The stop time is 0.2 s, the ratio of stop to pull time is 3:1, and the ratio of stop to retraction time is 5:1. In the initial stage, 100 mm is pulled at a speed of 3 mm / s. Then the traction speed is increased to 6 mm / s, and the retraction speed is kept constant at 2 mm / s. The copper liquid solidifies into a solid in the graphite crystallizer. The traction is stable until the traction is completed, and a high-quality cast rod with a wire diameter of 12.5 mm is obtained. No hot cracking or breakage occurs.

[0049] (3) The obtained 12.5mm cast rod is continuously extruded. The extrusion is carried out with a preheated pure copper rod as the extrusion head. The pure copper extrusion head is preheated at 450℃ for 10 hours. The extrusion temperature is 800℃ and the extrusion wheel speed is 7 revolutions / minute. The gap between the extrusion wheel and the die cavity is controlled at 0.5mm. The cast rod is extruded from 12.5mm wire diameter to 8mm. Then, the extrusion rod is pulled to 2.6mm wire diameter through continuous drawing technology. As the wire diameter decreases, the drawing speed gradually increases from 17m / min to 34m / min.

[0050] (4) The 2.6 mm diameter wire blank is placed in an air quenching furnace for heat treatment. The heat treatment process is to keep it at 500℃ for 6 hours and then cool it with the furnace. The resulting semi-soft wire blank is then continuously drawn at a drawing speed of 400 m / min to obtain 0.16 mm wire.

[0051] Comparative Example 1

[0052] A copper-chromium-zirconium alloy cast rod wire, comprising 0.5wt% Cr, 0.05wt% Zr, and the balance being copper, with a wire diameter of 16mm, is prepared using the same reagents and process parameters as in Example 1. The difference lies in the fact that a Cu5Mg intermediate alloy is not added in step (1), and the final traction in step (2) is performed using a "traction + stop + retraction" method, such as Figure 3 As shown in Figure c, the cast rod exhibits signs of fracture.

[0053] Comparative Example 2

[0054] A copper-chromium-zirconium alloy casting rod, comprising 0.5wt% Cr, 0.05wt% Zr, 0.05wt% Mg, with the balance being copper, has a wire diameter of 16mm. The reagents and process parameters used in its preparation method are the same as those in steps (1) and (2) of Example 1. The difference is that in step (2), vacuum casting is performed under pressure less than 0.1Pa. The cooling water and air cooling device at the outlet of the traction pipe are turned on, with a flow rate of 800L / h and the water tank temperature is maintained at 28±2℃. The traction system and take-up device are turned on. The entire process is carried out in a "traction + retraction" manner, with a traction-retraction time ratio of 5:3. In the initial stage of traction, 100mm is tractioned at a speed of 3mm / s, and then the traction speed is increased to 5mm / s. The retraction speed is kept constant at 2mm / s. The copper liquid solidifies into a solid in the graphite crystallizer. Thermal cracking occurs during traction, leading to traction failure.

[0055] Comparative Example 3

[0056] A copper-chromium-zirconium alloy wire, comprising 0.5wt% Cr, 0.05wt% Zr, 0.05wt% Mg, with the balance being copper, has a wire diameter of 0.16mm. The reagents and process parameters used in its preparation method are the same as those in Example 1. The difference is that in step (2), vacuum casting is performed under pressure less than 0.1Pa. The cooling water and air cooling device at the outlet of the traction pipe are turned on, with a flow rate of 800L / h and the water tank temperature is maintained at 28±2℃. The traction system and take-up device are turned on. The entire process is carried out in the manner of "traction + stop + retraction". The stop time is 0.1s. The ratio of stop time to pull time is controlled at 1:1 and the ratio of stop time to retraction time is 2:1. In the initial stage of traction, 100mm is pulled at a speed of 5mm / s. Then the traction speed is increased to 9mm / s, and the retraction speed is kept constant at 2mm / s. The copper liquid solidifies into a solid in the graphite crystallizer. The traction is stabilized until the traction is completed, and a 16mm diameter cast rod is obtained without thermal cracking or breakage.

[0057] Performance testing

[0058] 1. The cast rod that fractured under traction in step (2) of Comparative Example 1 was tested with the alloy cast rod obtained in step (2) of Example 1. Figure 3As shown in Figures ab, the comparison revealed that the addition of trace amounts of Mg in Example 1 reduced the grain size of the cast rod, resulting in a more uniform microstructure and a microstructure with a relatively uniform distribution and an average grain size of nearly 6 mm.

[0059] 2. The tensile strength and elongation of the wires prepared in the examples and comparative examples were tested according to the national standard GB / T 34505-2017 "Tension Test Method for Copper and Copper Alloys at Room Temperature". The tensile test was conducted using an RGM-6005 microcomputer-controlled electronic universal testing machine with a tensile rate of 10 mm / min. The wire drawing condition was verified using an LW-100-26YD wire drawing machine. According to actual production needs, wires that could be drawn more than 1500m without breaking were considered to be qualified and could be further processed. The test results are shown in Table 1 below.

[0060] 3. Conductivity tests were conducted on the wires prepared in the examples and comparative examples according to the requirements of the national standard GB / T 351-2019 "Methods for Measurement of Resistivity of Metallic Materials". The conductivity was tested using a TXJ-300 intelligent metallic conductor conductivity meter. The test results are shown in Table 1 below.

[0061] 4. Average grain size: The grain size of the cast rods prepared in step (2) of the examples and comparative examples was tested according to the requirements of the national standard GB / T 3488.2-2018 "Metallographic determination of microstructure of cemented carbide". The test results are shown in Table 1 below.

[0062] Table 1 - Performance test results of alloy wires prepared in the embodiments and comparative examples of this application

[0063]

[0064] like Figure 3 As shown in the diagram, the cast rod prepared by the copper-chromium-zirconium alloy in Example 1 has a low grain size and a uniform microstructure. The addition of Cu5Mg master alloy to the molten copper helps improve viscosity and reduce resistance during continuous casting. Combined with the "pull + stop + retract" method, the molten copper solidifies in the graphite crystallizer without thermal cracking or fracture. The cast rod exhibits good mechanical properties and machinability, and is less prone to breakage during subsequent wire drawing. The resulting wire has high tensile strength, elongation, and conductivity. In contrast, the cast rod in Comparative Example 1 lacks the Cu5Mg master alloy, resulting in higher viscosity and greater resistance in the molten copper, leading to rod breakage during the traction process and affecting subsequent processing. Furthermore, the grain size of the cast rod is significantly increased. The cast rod prepared in Comparative Example 2, due to the "pull + retract" method, exhibits significant thermal cracking on its surface, affecting subsequent traction.

[0065] As shown in Table 1, in the "traction + stop + retraction" traction process of the cast rod in Embodiment 1 of this application, controlling the speed and time ratio of traction, retraction and stopping can avoid fracture and reduce thermal cracking. The grain size formed during the cooling process of the cast rod is small, the mechanical properties of the cast rod are high, and the tensile strength and elongation of the wire after drawing are both high, which is beneficial to improving the performance of the wire.

[0066] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A method for preparing a high-performance copper-chromium-zirconium alloy cast rod, characterized in that, The alloy casting rod comprises 0.2wt%-1.5wt% Cr, 0.02wt%-0.15wt% Zr, and 0.01wt%-0.05wt% R, with the balance being copper and unavoidable impurities, where R is Mg and / or Zn. Its preparation method includes the following steps: (1) Under an inert gas atmosphere, after melting the cathode copper, copper-chromium master alloy and copper-zirconium master alloy, copper-magnesium master alloy and / or copper-zinc master alloy are added. After complete melting, electromagnetic stirring is performed, a covering agent is added, and the copper liquid is kept warm. (2) Perform vacuum casting, turn on the cooling water and air cooling device at the outlet of the traction pipe, turn on the traction system and take-up device. The whole process is carried out in the "traction + stop + retraction" mode. The stop time is 0.1-0.2 s, the ratio of stop to pull time is 3:1 or more, and the ratio of stop to retraction time is 5:1 or more. In the initial stage, the traction is carried out at a speed of 3 mm / s for 50-200 mm, and then the speed is increased to 5-7 mm / s. The retraction speed is kept constant at 2 mm / s. The copper liquid solidifies into a solid in the crystallizer. The traction is stabilized until the traction is completed and the casting rod is obtained.

2. The method for preparing a high-performance copper-chromium-zirconium alloy cast rod as described in claim 1, characterized in that, In step (1), under an inert gas atmosphere, cathode copper is added and melted at above 1050°C. Then, an inert gas is introduced for protection. Then, copper-chromium master alloy is added and the temperature is raised to 1150-1250°C. Then, copper-zirconium master alloy is added and the temperature is raised to 1250-1350°C. Then, copper-magnesium master alloy and / or copper-zinc master alloy are added. After complete melting, electromagnetic stirring is performed, a covering agent is added, and the temperature is maintained at 1200-1300°C for 10-30 minutes.

3. The method for preparing a high-performance copper-chromium-zirconium alloy cast rod as described in claim 1, characterized in that, In step (1), the covering agent is cryolite.

4. The method for preparing a high-performance copper-chromium-zirconium alloy cast rod as described in claim 1, characterized in that, In step (2), the crucible and crystallizer used for vacuum casting are independent and are internally coated with boron nitride, and nested with 5-10 mm of boron nitride or 5-10 mm of high-purity molybdenum titanium alloy.

5. The method for preparing a high-performance copper-chromium-zirconium alloy cast rod as described in claim 1, characterized in that, In step (2), the diameter of the graphite crystallizer is 12.5-16 mm.

6. The method for preparing a high-performance copper-chromium-zirconium alloy cast rod as described in claim 1, characterized in that, In step (2), the cooling device has a water flow rate of 500-4000 L / h and a circulating water temperature of 25-30℃.

7. A high-performance copper-chromium-zirconium alloy cast rod prepared by the method described in any one of claims 1-6.

8. A method for preparing high-performance copper-chromium-zirconium alloy wire, characterized in that, The high-performance copper-chromium-zirconium alloy casting rod as described in claim 7 includes the following steps: (1) The cast rod is continuously extruded to 6-10 mm at an extrusion temperature of 600-800℃, and then the extruded rod is continuously drawn to 2-4 mm at a drawing rate of 17-34 m / min to obtain a wire blank. (2) Heat treatment is performed on the wire blank at a temperature of 450-600℃. After cooling, a second continuous drawing process is performed to obtain wire with a drawing speed of 300-500m / min.

9. The method for preparing a high-performance copper-chromium-zirconium alloy wire as described in claim 8, characterized in that, In step (1), continuous extrusion is performed using a preheated pure copper rod as the extruder. The preheating temperature of the pure copper extrusion extruder is 350-500℃, the extrusion temperature is 600-800℃, the extrusion wheel speed is 6-10 revolutions / minute, and the gap between the extrusion wheel and the die cavity is controlled to be 0.3-0.6mm.

10. A high-performance copper-chromium-zirconium alloy wire prepared by the method for preparing high-performance copper-chromium-zirconium alloy wire as described in claim 8 or 9.

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