A method for preparing a high-conductivity, easy-cutting, and highly weather-resistant copper alloy material

Abstract

The present invention provides a method for preparing a high-conductivity, easy-cutting, and highly weather-resistant copper alloy material, comprising the following steps: (1) preparing a copper-zirconium (CuZr) alloy and a copper-tellurium (CuTe) alloy; (2) smelting: heating and melting cathode copper; adding lithium copper deoxidation-tellurium copper alloy-copper-zirconium alloy. Method: using a graphite bell jar. Heating to 1300±10°C and holding for 15-30 minutes; adjusting the furnace temperature to 1200-1240°C, and casting into an ingot by water cooling; (3) hot extrusion molding; (4) pickling and hydraulic drawing; and (5) straightening and sizing. The desired copper alloy material is obtained, wherein the mass fractions of the elements are: Te = 0.05%-0.20%, Li = 0.0040%-0.0120%, Zr = 0.15%-0.30%, and Cu is the remainder. (1) At room temperature, the electrical conductivity is ≥90% IACS, the machinability is higher than 85% of HPb63‑3 materials under the same conditions, and the strength at 40% deformation is >350 MPa; (2) At 30°C and humidity >85%, the surface of the material does not undergo obvious discoloration or oxidation within 90 days; (3) At 800°C and treated in a 30% hydrogen atmosphere at normal pressure for 1 hour, the hardness is ≥50 HV, and no obvious hydrogen embrittlement cracks appear on the surface.

Description

Technical Field

[0001] The present invention belongs to the technical field of alloy material preparation, and in particular relates to a method for preparing a high-conductivity, easy-cutting and high-weather-resistant copper alloy material. Background Art

[0002] With the continuous advancement of science and technology, the market demand for copper alloy materials has also increased. This is especially true for copper alloy materials with high conductivity, easy cutting, and high weather resistance. Currently, researchers have studied this copper alloy material, and the main strengthening methods are alloying and composite materials. The alloying method sacrifices conductivity to a certain extent to improve mechanical properties, thereby improving machinability, and cannot truly achieve the result of taking both into account. The conductivity of copper alloys prepared by the alloying method generally does not exceed 80% IACS, and it requires the addition of expensive Cr and Ni metals. The process is complex, and industrial application and production are difficult. The composite material method has a very cumbersome processing process and high production costs. It is still in the experimental research stage.

[0003] Therefore, whether it is possible to provide a preparation method for a high-conductivity, easy-to-cut, and high-weather-resistant copper alloy material that can improve conductivity while also having good machinability and atmospheric corrosion resistance to achieve the expansion of its application has become a technical problem that urgently needs to be solved. Summary of the Invention

[0004] The purpose of the present invention is to solve the above technical problems and provide a method for preparing a high-conductivity, easy-to-cut and high-weather-resistant copper alloy material, which can meet the requirements of high conductivity, easy cutting and high weather resistance.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a high-conductivity, easy-cutting, and high-weather-resistant copper alloy material comprises the following steps:

[0007] (1) Preparation of copper-zirconium (CuZr) master alloy: In order to achieve the purpose of introducing Zr element into the high-conductivity, free-cutting, high-temperature resistant copper alloy material, the CuZr master alloy must be prepared first. Taking the mass of the prepared CuZr master alloy as 100%, 81% to 85% by mass of grade A cathode copper and 21% to 25% by mass of sponge zirconium with a purity higher than 99.99% are weighed, and the burnout amount is calculated to be 3%. The weighed grade A cathode copper and sponge zirconium are placed in a crucible of a 25L vacuum intermediate frequency furnace, and 50mm thick flake graphite powder with a purity of 99.99% is added as a covering agent. The vacuum pump of the vacuum intermediate frequency furnace is turned on to evacuate the furnace chamber to a vacuum degree of not less than -0.1MPa. The heating mechanism of the vacuum intermediate frequency furnace is turned on to heat the crucible containing the contents to 1230-1250°C, and the crucible is kept warm for 30 minutes after the material in the crucible is melted. After the holding period is completed, the crucible is tilted in the vacuum chamber while maintaining the vacuum, and the CuZr alloy liquid is poured into a water-cooled steel mold for cooling, thereby obtaining a CuZr master alloy, wherein the Zr content in the master alloy is ≥15% and the balance is Cu.

[0008] (2) Preparation of CuTe intermediate alloy: Taking the mass of the prepared CuTe intermediate alloy as 100%, weigh 81%~85% by mass of grade A cathode copper and 21~25% by mass of tellurium ingot with a purity higher than 99.99%, and calculate 1% of the mass as the burn-out amount; place the weighed grade A cathode copper and sponge zirconium in a 25L vacuum medium frequency furnace crucible, and add 50mm thick 99.99% pure flake graphite powder as a covering agent; turn on the vacuum pump of the vacuum medium frequency furnace to make the furnace chamber vacuum, and the vacuum degree is not less than -0.1MPa; turn on the heating mechanism of the vacuum medium frequency furnace to heat the crucible containing the contents, raise the temperature to 1230~1250℃, wait for the material in the crucible to melt and keep it warm for 30min; after the insulation is completed, tilt the crucible in the vacuum chamber while maintaining the vacuum, and pour the CuTe alloy liquid into a water-cooled steel mold for cooling, so as to obtain a CuTe intermediate alloy, in which Te% ≥ 20% and the balance is Cu.

[0009] (3) Melting: After the CuTe and CuZr master alloys are prepared, the high-conductivity, free-cutting, and high-temperature resistant copper alloy ingots are prepared using Grade A cathode copper, CuTe master alloy, CuZr master alloy, and 99.99% pure lithium as the main raw materials. The master alloys, lithium, and Grade A cathode copper are weighed according to the element mass fractions of Zr = 0.15-0.30%, Te = 0.05-0.20%, Li = 0.0040%-0.0120%, and Cu as the balance. A 750kg power frequency furnace is used for melting, and a screw-type semi-continuous caster is used for casting. Refined charcoal and 99.99% pure flake graphite powder are used as covering agents. The power frequency furnace is used to melt Grade A cathode copper, with a covering agent at least 50mm thick covering the furnace to isolate it from air during the melting process. Once the Grade A cathode copper in the furnace is completely melted, the temperature is raised to 1250±10°C. 50% of the lithium metal is added, followed by a CuTe master alloy, then a CuZr master alloy, and finally the remaining 50% of the lithium metal, with 10-minute intervals between each addition. After the alloy and master alloy are added, the temperature is raised to 1300±10°C, held for 15-30 minutes, and then cooled to 1200-1240°C. Continuous casting is then performed using the screw-type semi-continuous caster. The molten alloy is then cast into ingots with diameters of 100-120 mm and lengths of 6000-8000 mm, as needed.

[0010] (4) Extrusion: Place the copper alloy ingot obtained in step (3) into an induction heating furnace and heat it to 800±25°C; keep it warm for 30-45 minutes, and then perform extrusion deformation processing;

[0011] (5) Pickling and hydraulic drawing: Pickling the blank obtained in step (4) to remove surface oxides, and then hydraulically drawing it;

[0012] (6) Straighten, size and polish the profile after drawing and deformation in (5). Remember;

[0013] The element composition of the copper alloy material is calculated by weight percentage:

[0014] Zr 0.15~0.30%;

[0015] Te 0.05~0.20%;

[0016] Li 0.0040%~0.0120%;

[0017] Cu residue;

[0018] The present invention prepares copper-chromium (CuZr) master alloy and copper-tellurium (CuTe) master alloy and designs a preparation process suitable for the copper alloy materials. The preparation process not only satisfies industrial production applications, but also significantly improves the electrical conductivity, machinability and weather resistance of the obtained copper alloy materials.

[0019] Furthermore, the covering agent in steps (1), (2) and (3) is one of charcoal, graphite flakes or graphite powder.

[0020] Furthermore, the zirconium content Zr% of the zirconium-copper master alloy is ≥15%.

[0021] Furthermore, the tellurium content of the tellurium-copper master alloy is Te%≥20%.

[0022] Furthermore, the tellurium:lithium content of the lithium-copper master alloy is Li%≥20%.

[0023] Furthermore, the extrusion deformation process is carried out on an 800 horizontal extruder, the equipment specification of which is 8.0MN.

[0024] Furthermore, the extrusion is performed in a reverse extrusion mode, and the extrusion temperature is 800±25° C. Water-sealed extrusion.

[0025] Furthermore, the pickling is performed by placing the billet obtained after extrusion in a sulfuric acid tank with a concentration of 15% to 20% for pickling.

[0026] Furthermore, the hydraulic drawing is carried out on a hydraulic drawing machine, and the equipment specification is 0.6MN.

[0027] Furthermore, the specification of the hydraulic drawing die is φ5~φ55, and the material is: alloy drawing die or diamond coating drawing die.

[0028] Since the present invention adopts the above-mentioned preparation method, the following beneficial effects are achieved:

[0029] (1) The electrical conductivity of the copper alloy material obtained by the method of the present invention is higher than 90%;

[0030] (2) The machinability of the copper alloy material obtained by the method of the present invention is 85% higher than that of HPb63~3 material under the same conditions, and the strength is greater than 350 MPa at 40% deformation;

[0031] (3) The copper alloy material obtained by the method of the present invention does not undergo obvious surface discoloration or oxidation within 90 days at 30°C and a humidity higher than 85%.

[0032] (4) The copper alloy material obtained by the method of the present invention has a hardness of not less than HV50 and no obvious hydrogen embrittlement cracks on the surface after being treated at 800°C and 30% hydrogen atmosphere at normal pressure for 1 hour. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and key points of the present invention more clearly understood, the present invention is described in detail below with reference to the following embodiments. It is necessary to point out that the following embodiments are merely intended to explain and illustrate the present invention and are not intended to limit the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above invention content still fall within the scope of protection of the present invention.

[0034] Example 1

[0035] A high-conductivity, free-cutting, and high-weather-resistant copper alloy material, the element composition of which is calculated by weight percentage:

[0036] Zr 0.2%; Te 0.1% Li 0.0070%; Cu balance;

[0037] The preparation method of the copper alloy material comprises the following steps:

[0038] (1) Melting: Weigh the master alloys, metallic lithium, and Class A cathode copper according to the element mass fractions of Zr% = 0.15~0.30%, Te% = 0.05~0.20%, Li = 0.0040%~0.0120%, and Cu as the balance. Use a 750kg power frequency furnace as the melting equipment and a screw-type semi-continuous caster as the casting equipment; use refined charcoal and 99.99% purity flake graphite powder as covering agents; start the power frequency furnace to melt the Class A cathode copper, and cover the furnace with a covering agent at least 50mm thick to isolate the air during the melting process; when the Class A cathode copper in the furnace is completely melted, heat it to 1250±10℃, add 50% metallic lithium to the furnace, then add the CuTe master alloy, then add the CuZr master alloy, and then add the remaining 50% metallic lithium, with an interval of 10 minutes between each addition. After the addition of alloy and master alloy is completed, the temperature is raised to 1300±10℃, and after keeping warm for 15~30min, the furnace temperature is adjusted to 1200℃~1240℃. After baking the furnace head several times, a screw-type semi-continuous casting machine is used for continuous casting. The alloy liquid is cast into ingots with a diameter of φ100~φ120mm and a length of 6000~8000mm as needed.

[0039] (2) Extrusion: The copper alloy ingot obtained in step (1) was placed in an induction furnace, heated to 800°C, and kept warm for 30 minutes to uniformly refine the grains, and then subjected to extrusion deformation processing; the extrusion deformation processing was carried out on an 800 horizontal extruder with an equipment specification of 8.0MN. The extrusion method adopted was reverse extrusion, and the extrusion die was made of inlaid ceramics. The extrusion die size was: outer diameter φ38.5*22.5, inner hole φ20, and the extrusion temperature was 800°C.

[0040] (3) Pickling and hydraulic drawing: The billet (φ19.5) obtained in step (3) is pickled. The billet obtained after extrusion is placed in a 15% sulfuric acid tank for pickling to remove surface oxides, and then hydraulic drawing is performed; hydraulic drawing is performed on a hydraulic drawing machine with a specification of 0.6MN. The alloy drawing die specification is φ15 (process: φ19.5 - hydraulic drawing φ15).

[0041] (4) Straighten, polish and cut the bars after the above drawing deformation.

[0042] The performance of the copper alloy material obtained was checked, and ten samples were taken from each batch and the average value was taken. The tensile test of metal materials was carried out in accordance with the standard GB / T228, the bending test of metal materials was carried out in accordance with the standard GB / T232, and the conductivity test method was carried out in accordance with the provisions of the metal material resistivity measurement method GB / T351. The mechanical properties of the copper alloy material obtained by the test are as follows: tensile strength R m =370MPa, machinability = 85%, elongation = 15%, electrical conductivity = 92%IACS.

[0043] Under the experimental conditions of temperature 30°C, humidity 90%, and time 90 days, the surface of the above materials did not change color or oxidize.

[0044] Under the experimental conditions of 800°C, 30% hydrogen atmosphere at normal pressure, and 1 hour, no hydrogen embrittlement cracks appeared on the surface of the material.

[0045] Example 2

[0046] A high-conductivity, free-cutting, and high-weather-resistant copper alloy material, the element composition of which is calculated by weight percentage:

[0047] Zr 0.25%; Te 0.15% Li 0.0070%; Cu balance;

[0048] The preparation method of the copper alloy material comprises the following steps:

[0049] (1) Melting: Weigh the master alloys, metallic lithium, and Class A cathode copper according to the element mass fractions of Zr% = 0.15~0.30%, Te% = 0.05~0.20%, Li = 0.0040%~0.0120%, and Cu as the balance. Use a 750kg power frequency furnace as the melting equipment and a screw-type semi-continuous caster as the casting equipment; use refined charcoal and 99.99% purity flake graphite powder as covering agents; start the power frequency furnace to melt the Class A cathode copper, and cover the furnace with a covering agent at least 50mm thick to isolate the air during the melting process; when the Class A cathode copper in the furnace is completely melted, heat it to 1250±10℃, add 50% metallic lithium to the furnace, then add the CuTe master alloy, then add the CuZr master alloy, and then add the remaining 50% metallic lithium, with an interval of 10 minutes between each addition. After the addition of alloy and master alloy is completed, the temperature is raised to 1300±10℃, and after keeping warm for 15~30min, the furnace temperature is adjusted to 1200℃~1240℃. After baking the furnace head several times, a screw-type semi-continuous casting machine is used for continuous casting. The alloy liquid is cast into ingots with a diameter of φ100~φ120mm and a length of 6000~8000mm as needed.

[0050] (2) Extrusion: The copper alloy ingot obtained in step (1) is placed in an induction furnace, heated to 820°C, and kept warm for 30 minutes to make the grains uniformly refined, and then subjected to extrusion deformation processing; the extrusion deformation processing is carried out on an 820 horizontal extruder with a specification of 8.0MN. The extrusion adopts a reverse extrusion method, and the extrusion die adopts an inlaid ceramic. The size of the extrusion die is: outer circle φ38.5*22.5, inner hole φ20, and the extrusion temperature is 820°C.

[0051] (3) Pickling and hydraulic drawing: The billet (φ19.5) obtained in step (3) is pickled, and the billet obtained after extrusion is placed in a 15% sulfuric acid tank for pickling to wash away the surface oxides, and then hydraulic drawing is performed; the hydraulic drawing is performed on a hydraulic drawing machine, the equipment specification of which is 0.6MN, and the alloy drawing die specification is φ15 (process: φ19.5-hydraulic drawing φ15).

[0052] (4) Straighten, polish and cut the bars after the above drawing deformation.

[0053] The performance of the copper alloy material obtained was checked, and ten samples were taken from each batch and the average value was taken. The tensile test of metal materials was carried out in accordance with the standard GB / T228, the bending test of metal materials was carried out in accordance with the standard GB / T232, and the conductivity test method was carried out in accordance with the provisions of the metal material resistivity measurement method GB / T351. The mechanical properties of the copper alloy material obtained by the test are as follows: tensile strength R m =375MPa, machinability = 87%, elongation = 14%, electrical conductivity = 93%IACS.

[0054] Under the experimental conditions of temperature 30°C, humidity 90%, and time 90 days, the surface of the above materials will change color and oxidize.

[0055] Under the experimental conditions of 800°C, 30% hydrogen atmosphere at normal pressure, and 1 hour, no hydrogen embrittlement cracks appeared on the surface of the material.

[0056] Example 3

[0057] A high-conductivity, free-cutting, and high-weather-resistant copper alloy material, the element composition of which is calculated by weight percentage:

[0058] Zr 0.20%; Te 0.15% Li 0.0070%; Cu balance;

[0059] The preparation method of the copper alloy material comprises the following steps:

[0060] (1) Melting: Weigh the master alloys, metallic lithium, and Class A cathode copper according to the element mass fractions of Zr% = 0.15~0.30%, Te% = 0.05~0.20%, Li = 0.0040%~0.0120%, and Cu as the balance. Use a 750kg power frequency furnace as the melting equipment and a screw-type semi-continuous caster as the casting equipment; use refined charcoal and 99.99% purity flake graphite powder as covering agents; start the power frequency furnace to melt the Class A cathode copper, and cover the furnace with a covering agent at least 50mm thick to isolate the air during the melting process; when the Class A cathode copper in the furnace is completely melted, heat it to 1250±10℃, add 50% metallic lithium to the furnace, then add the CuTe master alloy, then add the CuZr master alloy, and then add the remaining 50% metallic lithium, with an interval of 10 minutes between each addition. After the addition of alloy and master alloy is completed, the temperature is raised to 1300±10℃, and after keeping warm for 15~30min, the furnace temperature is adjusted to 1200℃~1240℃. After baking the furnace head several times, a screw-type semi-continuous casting machine is used for continuous casting. The alloy liquid is cast into ingots with a diameter of φ100~φ120mm and a length of 6000~8000mm as needed.

[0061] (2) Extrusion: The copper alloy ingot obtained in step (1) is placed in an induction furnace, heated to 810°C, and kept warm for 30 minutes to make the grains uniformly refined, and then subjected to extrusion deformation processing; the extrusion deformation processing is carried out on an 810 horizontal extruder, the equipment specification of which is 8.0MN, the extrusion adopts a reverse extrusion method, the extrusion die adopts an inlaid ceramic, the size of the extrusion die is: outer circle φ38.5*22.5, inner hole φ20, and the extrusion temperature is 810°C.

[0062] (3) Pickling and hydraulic drawing: The billet (φ19.5) obtained in step (3) is pickled, and the billet obtained after extrusion is placed in a 15% sulfuric acid tank for pickling to wash away the surface oxides, and then hydraulic drawing is performed; the hydraulic drawing is performed in a hydraulic drawing machine, the equipment specification of which is 0.6MN, and the alloy drawing die specification is φ15 (process: φ19.5-hydraulic drawing φ15).

[0063] (4) Straighten, polish and cut the bars after the above drawing deformation.

[0064] The performance of the copper alloy material obtained was checked, and ten samples were taken from each batch and the average value was taken. The tensile test of metal materials was carried out in accordance with the standard GB / T228, the bending test of metal materials was carried out in accordance with the standard GB / T232, and the conductivity test method was carried out in accordance with the provisions of the metal material resistivity measurement method GB / T351. The mechanical properties of the copper alloy material obtained by the test are as follows: tensile strength R m =378MPa, machinability = 88%, elongation = 13%, electrical conductivity = 92%IACS.

[0065] Under the experimental conditions of temperature 30°C, humidity 90%, and time 90 days, the surface of the above materials did not change color or oxidize.

[0066] Under the experimental conditions of 800°C, 30% hydrogen atmosphere at normal pressure, and 1 hour, no hydrogen embrittlement cracks appeared on the surface of the material.

Claims

1. A method for preparing a high-conductivity, easy-cutting, and highly weather-resistant copper alloy material, characterized in that: The following steps are involved: (1) Preparation of CuZr master alloy; Taking the mass of the prepared CuZr master alloy as 100%, weigh 81%~85% by mass of grade A cathode copper and 21~25% by mass of sponge zirconium with a purity higher than 99.99%, and calculate the burnout amount as 3%; place the weighed grade A cathode copper and sponge zirconium in a 25L vacuum medium frequency furnace crucible, and add 50mm thick 99.99% purity flake graphite powder as a covering agent; turn on the vacuum pump of the vacuum medium frequency furnace to make the furnace chamber vacuum, and the vacuum degree is not less than -0.1MPa; turn on the heating mechanism of the vacuum medium frequency furnace to heat the crucible containing the contents to 1230~1250℃, wait for the material in the crucible to melt and keep it warm for 30min; after the end of the insulation, dump the crucible in the vacuum chamber while maintaining the vacuum. Pour the CuZr alloy liquid into a water-cooled steel mold and cool it to obtain a CuZr master alloy, wherein the Zr% in the master alloy is ≥15% and the balance is Cu; (2) Preparation of CuTe intermediate alloy: Taking the mass of the prepared CuTe intermediate alloy as 100%, weigh 81%~85% by mass of Grade A cathode copper and 21~25% by mass of tellurium ingot with a purity higher than 99.99%, and calculate 1% of the mass as the burn-out amount; place the weighed Grade A cathode copper and sponge zirconium in a crucible of a 25L vacuum medium frequency furnace, and add 50mm thick flake graphite powder with a purity of 99.99% as a covering agent; turn on the vacuum pump of the vacuum medium frequency furnace to make the furnace chamber vacuum, and the vacuum degree is not less than -0.1MPa; turn on the heating mechanism of the vacuum medium frequency furnace to heat the crucible containing the contents, raise the temperature to 1230~1250℃, and keep the temperature for 30min after the material in the crucible is melted; after the insulation is completed, tilt the crucible in the vacuum chamber while maintaining the vacuum, and pour the CuTe alloy liquid into a water-cooled steel mold for cooling, so as to obtain a CuTe intermediate alloy, in which Te% ≥ 20% and the balance is Cu; (3) Melting: Add cathode copper with a purity of more than 99.99% into the melting furnace according to the corresponding weight percentage, and heat and melt it under the protection of the covering agent; after the cathode copper is completely melted, add 50% lithium-copper intermediate alloy for deoxidation according to the proportion of lithium, control the furnace temperature to 1150℃, keep it warm and let it stand, then add CuTe intermediate alloy, control the furnace temperature to 1250℃, keep it warm and let it stand, then add CuZr intermediate alloy, after it is completely melted, stir the molten pool, and finally add 50% lithium-copper intermediate alloy, the time interval between each addition is 10min; heat to 1300±10℃, keep it warm for 15~30min, adjust the furnace temperature to 1200℃~1240℃, bake the furnace head several times, and then cast it into ingots with water cooling, and cast the alloy liquid into ingots with a diameter of 100~120mm and a length of 6000~8000mm; (4) Extrusion; placing the copper alloy ingot obtained in step (3) into an induction heating furnace, heating it to 800°C, keeping it warm for 30 minutes, and then performing water seal extrusion deformation processing; (5) Pickling and hydraulic drawing: the extruded billet obtained in step (4) is pickled to remove surface oxides, and then hydraulically drawn. The drawing die for the hydraulic drawing is a diamond-coated cold drawing die; the alloy drawing die specification is φ15; (6) The rod after the drawing deformation is straightened, polished and sized, so that the element composition of the high-conductivity, easy-cutting and high-weather-resistant copper alloy material is as follows: Te=0.10%~0.15%, Li=0.0070%, Zr=0.20%~0.25%, and Cu is the balance.

2. The method for preparing the copper alloy material according to claim 1, characterized in that: The lithium content of the lithium-copper master alloy is Li≥10%.

3. The method for preparing the copper alloy material according to claim 1, characterized in that: The extrusion deformation process is carried out on an 800-level horizontal extruder, and the equipment specification is 8.0MN.

4. The method for preparing the copper alloy material according to claim 1, characterized in that: The extrusion adopts a reverse extrusion method, and the extrusion temperature is 800±25℃.

5. The method for preparing the copper alloy material according to claim 1, characterized in that: The die material used for the extrusion is inlaid ceramic, and the extrusion ratio is 20-150.

6. The method for preparing the copper alloy material according to claim 1, characterized in that: The pickling is carried out by placing the billet obtained after extrusion in a sulfuric acid tank with a concentration of 15% to 20% for pickling.

7. The method for preparing the copper alloy material according to claim 1, characterized in that: The hydraulic drawing is carried out in a hydraulic drawing machine, the specification of which is 0.6MN.