High-strength and high-conductivity copper-silver alloy wire rod and preparation method thereof

Abstract

The invention mainly relates to a high-strength and high-conductivity copper-silver alloy wire rod, which comprises the following composition elements and contents meeting the following requirements: the content of Ag is 1-15wt%, the content of Nb is less than or equal to 1wt%, the balance is copper and inevitable impurities, and the total content of the impurities is less than 0.5 wt%. The invention further provides a preparation method of the high-strength and high-conductivity copper-silver alloy wire rod. The preparation method mainly comprises the following steps: preparing materials; performing pre-operation before heating; heating in a protective atmosphere; the Cu-Ag alloy rod blank is sequentially and respectively subjected to solution treatment and aging treatment; the Cu-Ag alloy rod blank is subjected to multi-pass drawing; and annealing heat treatment is conducted on the Cu-Ag alloy rod blank, and finally the high-strength and high-conductivity copper-silver alloy wire rod is prepared. The tensile strength of the finished product of the high-strength and high-conductivity copper-silver alloy wire rod is 800-1100 MPa, and the conductivity reaches 70-95% IACS (International Annealed Copper Standard); the comprehensive performance is excellent. The preparation method of the high-strength and high-conductivity copper-silver alloy wire rod is simple in step and easy to operate, and the cost is lower than that of the similar prior art; the method has excellent application value and good market potential.

Description

Technical Field

[0001] The present invention relates to the field of alloy design and application technology, and in particular to a high-strength and high-conductivity copper-silver alloy wire and a preparation method thereof, which is suitable for various electrical circuit conductors, windings, transmission lines and contact lines. Background Art

[0002] With the advent of the intelligent era, high-end manufacturing and electronics industries have developed rapidly. Copper-silver alloy has the characteristics of high strength and high conductivity and excellent comprehensive properties such as bending, torsion, fatigue resistance, and heat resistance. Therefore, copper-silver alloy wires are widely used in wires and cables, vibration coils, high-speed turbine generator rotor conductors, contact wires for trains, and signal transmission lines for cutting-edge digital communication equipment.

[0003] Traditional copper-silver alloy wires are often prepared by extruding alloy bars, such as CN103572184A, which prepares copper alloy bars with a silver content of 15-20% by vacuum melting, and refines the copper-silver alloy bars by vacuum consumable electrodes, and then hot extrudes, heat treats and draws to obtain the final product. Although the obtained copper-silver alloy material can have high strength and excellent conductivity, however. This method cannot achieve continuous production of long-length copper-silver alloy wires, nor does it mention that it can be drawn into ultra-fine wires while still maintaining high strength.

[0004] In recent years, continuous casting has also been gradually used in the production of copper-silver alloy wires, such as CN202210614091.2, which uses a preparation process of upper cold continuous casting-continuous rolling-continuous drawing-vacuum protective atmosphere annealing to prepare a copper-silver alloy with low strength but excellent electrical conductivity and very low silver content. The upper continuous casting method is used to melt and cast copper-silver alloys with high alloy content, but due to the large furnace area, the conversion is not flexible when adjusting the production of high alloy content copper-silver alloys. On the other hand, since the furnace is generally built with refractory materials, refractory inclusions are prone to occur in the product during the product smelting and casting process, and ultra-fine wires cannot be continuously drawn. CN112501471A discloses a method for preparing alloy copper-silver alloy wires based on horizontal continuous casting rod billets. The copper-silver alloy wire billets are produced by horizontal cold continuous casting technology, and then the copper-silver alloy wires are drawn and formed. The copper-silver alloy wires produced by the horizontal continuous casting method have the characteristics of high oxygen content and unstable production.

[0005] In summary, in order to achieve efficient and large-scale production of high-strength and high-conductivity copper-silver alloys, people are eager to obtain a preparation process method for Cu-Ag alloy wire based on down-draw continuous casting with better technical effects. Summary of the invention

[0006] The purpose of the present invention is to provide a high-strength and high-conductivity copper-silver alloy wire and a preparation method thereof, which can obtain the optimal match of high tensile strength and high conductivity of Cu-Ag alloy on the basis of controlling the Ag content to be low, and reduce the production cost under the premise of ensuring the performance of Cu-Ag alloy. At the same time, the preparation method of a high-strength and high-conductivity copper-silver alloy wire described in the present invention can be used to prepare high-strength and high-conductivity copper-silver alloy wire including but not limited to circular cross-section, rectangular cross-section and other special-shaped cross-sections.

[0007] The technical solution of the present invention is:

[0008] A high-strength and high-conductivity copper-silver alloy wire, the key technology is:

[0009] The constituent elements and contents of the high-strength and high-conductivity copper-silver alloy wire meet the following requirements: Ag content is 1-15wt%, Nb content is ≤1wt%, and the rest is copper and unavoidable impurities, and the overall impurity content is less than 0.5wt%.

[0010] The high-strength and high-conductivity copper-silver alloy wire material of the present invention preferably requires protection of the following technical content: the constituent elements and contents of the high-strength and high-conductivity copper-silver alloy wire material meet the following requirements: Ag content 3-7wt%, Nb content 0-0.1wt%, and the rest are copper and unavoidable impurities, and the overall impurity content is less than 0.1wt%.

[0011] The cross-section of the high-strength and high-conductivity copper-silver alloy wire includes but is not limited to a circular cross-section, a rectangular cross-section, a polygonal cross-section, other axisymmetric or centrally symmetrical cross-sections, and special-shaped cross-sections.

[0012] The present invention also claims a method for preparing the high-strength and high-conductivity copper-silver alloy wire as described above, which is characterized in that the preparation steps and contents thereof sequentially meet the following requirements:

[0013] Step 1, ingredients: raw material single substance Ag, Cu-Nb master alloy and single substance Cu are mixed according to the composition ratio and alloy ratio; wherein: Ag is pure silver, Cu is high-purity cathode copper (99.99%), and the Nb content of the Cu-Nb master alloy is 10wt%;

[0014] Step 2, pre-heating operation: add the raw materials into the vacuum continuous casting furnace, evacuate the furnace chamber to <10 -2 After the furnace pressure reaches 0.01 MPa, argon gas is filled in and the furnace chamber is evacuated to less than 10 -2 Pa;

[0015] Step 3, heating in protective atmosphere: first, heat the raw material to 1000℃±20℃ with a heating rate of not less than 20℃ / min, and inject argon until the pressure in the furnace reaches 0.07-0.08MPa; then continue heating until Cu begins to melt, and inject argon until the pressure in the furnace reaches 0.1MPa; then heat the raw material again to 1250-1300℃ and refine for 10-15 minutes, so as to start the subsequent pulling Cu-Ag alloy rod billet operation;

[0016] Step 4, performing a solution treatment on the Cu-Ag alloy rod blank;

[0017] Step 5, performing aging treatment on the Cu-Ag alloy rod blank;

[0018] Step 6, performing multiple-pass drawing on the Cu-Ag alloy rod blank;

[0019] Step 7, annealing heat treatment is performed on the Cu-Ag alloy rod blank; finally, a high-strength and high-conductivity copper-silver alloy wire is prepared.

[0020] The preparation method of the high-strength and high-conductivity copper-silver alloy wire material, the preparation steps and contents of which sequentially meet one or a combination of the following requirements:

[0021] First, in the raw materials used in the batching described in step 1, the mass percentage of pure Ag and pure high-purity cathode copper is not less than 99.95%.

[0022] Second, in step 2 and step 3, when pulling the Cu-Ag alloy rod billet, the continuous casting pulling speed is 0.5-2 mm / s, the diameter of the crystallizer is 8-12 mm, the crystallizer cooling water temperature is required to be no higher than 30°C, and the flow rate at the crystallizer cooling water inlet is no less than 30 Lpm;

[0023] Third, the requirements for the solution treatment in step 4 are a solution temperature of 720-920°C and a holding time of 0-6h;

[0024] Fourthly, the aging treatment in step 5 requires an aging temperature of 350-500°C and a holding time of 0-20h;

[0025] Fifth, the requirements for multi-pass drawing in step 6 are as follows: the total processing rate of multi-pass drawing of Cu-Ag alloy is greater than 90%, and the processing rate of single-pass drawing does not exceed 30%;

[0026] Sixth, the requirements for the annealing heat treatment in step 7 are an annealing temperature of 250-350°C and a holding time of 0-6h.

[0027] In the further preferred limited content, in step 3, the casting process parameters must meet the following conditions: when the diameter of the selected crystallizer is less than 10mm, the pulling speed must be no higher than 1mm / s; when the diameter of the crystallizer is greater than 10mm and less than 12mm, the pulling speed must be no higher than 2mm / s. This is because the solidification of the ingot is mainly affected by three main parameters: casting temperature, cooling intensity and pulling speed. Only when certain parameters are matched can the single crystal structure of the ingot be obtained, which is conducive to subsequent drawing.

[0028] During the implementation of step 7, the annealing temperature should not be higher than the aging temperature, because it is to prevent the growth and coarsening of the precipitated phase during the annealing process, thereby affecting the performance.

[0029] The high-strength and high-conductivity copper-silver alloy wire material and its preparation method of the present invention adopts downward continuous casting to prepare the rod blank, and a good directional solidification structure can be obtained by adjusting the cooling process parameters. The prepared alloy rod blank has low oxygen content through vacuum melting, which avoids the inclusion of oxides and the like into the alloy matrix, which is beneficial to the stable production of the subsequent cold-drawn wire material and also beneficial to the improvement of conductivity. Solid solution and aging treatment can optimize the microstructure of the alloy, and the dendrite structure in the cast rod blank that is unfavorable to the improvement of strength and conductivity can be eliminated through solid solution, forming a supersaturated solid solution, and in the subsequent aging process, a fine and dispersed single Ag phase is formed. After aging, the Cu-Ag alloy wire material is directly cold drawn to the required specifications, and the fine single Ag phase is elongated to form a fine fiber reinforcement phase, which increases the contact area between the nanophase and the matrix, and greatly improves the precipitation strengthening effect of the precipitation phase. The high-strength and high-conductivity copper-silver alloy wire material of the present invention has a tensile strength of 800-1100 MPa and an electrical conductivity of 70-85% IACS under the above-mentioned preparation process, and has excellent performance.

[0030] The preparation method of the copper-silver alloy wire provided by the present invention has simple production steps, is easy to operate, has large-scale industrial production value, and the production cost is significantly lower than similar existing technologies; it has excellent application value and good market potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the down-draw continuous casting process;

[0032] Figure 2 This is the structure of the Cu-Ag alloy wire in the aged state after cold drawing. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the embodiments and the accompanying drawings, but is not limited thereto.

[0034] Example 1

[0035] The high-strength and high-conductivity copper-silver alloy wire has the following constituent elements and contents: Ag content 1-15wt%, Nb content ≤1wt%, and the rest is copper and unavoidable impurities, with the total impurity content less than 0.5wt%. Its basic performance index is significantly better than similar products in the prior art.

[0036] The cross-section of the high-strength and high-conductivity copper-silver alloy wire includes but is not limited to a circular cross-section, a rectangular cross-section, a polygonal cross-section, other axisymmetric or centrally symmetrical cross-sections, and special-shaped cross-sections.

[0037] Example 2

[0038] The high-strength and high-conductivity copper-silver alloy wire material has the following constituent elements and contents: Ag content 3-7wt%, Nb content 0-0.1wt%, and the rest copper and unavoidable impurities, with the total impurity content being less than 0.1wt%. Its basic performance index is significantly better than the parameter range in Example 1 that is different from that in Example 2, and is better than similar products in the prior art.

[0039] The cross-section of the high-strength and high-conductivity copper-silver alloy wire includes but is not limited to a circular cross-section, a rectangular cross-section, a polygonal cross-section, other axisymmetric or centrally symmetrical cross-sections, and special-shaped cross-sections.

[0040] Example 3

[0041] Preparation method of high-strength and high-conductivity copper-silver alloy wire:

[0042] Step 1: prepare the alloy composition of 6wt.% Ag and the balance of Cu, wherein the purity of Ag and Cu is above 99.95wt.%. Place the above raw materials in a crucible of a downcast continuous casting furnace, place the single Cu at the bottom of the crucible, and place the single Ag above the single Cu. Evacuate the furnace chamber to a temperature of <10 -2 After that, argon gas was filled into the furnace until the pressure inside the furnace reached 0.01 MPa, and the furnace chamber was evacuated again to a pressure of <10 -2 After Pa. Use an induction coil to start heating the raw materials in the crucible, heat the raw materials to 1000℃, flush with argon until the pressure in the furnace reaches 0.08MPa, continue heating until Cu begins to melt, and flush with argon until the pressure in the furnace reaches 0.1MPa. After heating the raw materials to 1250℃, refine for 15 minutes and start pulling the Cu-Ag alloy rod billet. The downward continuous casting pulling speed is 0.8mm / s, the diameter of the crystallizer used is 12mm, the crystallizer cooling water temperature is 26℃, and the flow rate at the crystallizer cooling water inlet is 30Lpm.

[0043] Step 2, the Cu-Ag alloy rod blank obtained in step 1 is kept at 800° C. for 2 hours and water-cooled;

[0044] Step 3, the Cu-Ag alloy rod blank obtained in step 2 is kept at 350° C. for 10 hours and air-cooled;

[0045] Step 4, the Cu-Ag alloy rod blank obtained in step 3 is subjected to continuous multi-pass drawing, with a single-pass deformation amount of 15%, to obtain a wire with a diameter of 4 mm.

[0046] Step 5, the Cu-Ag alloy rod blank obtained in step 4 is kept at 250° C. for 1 hour and air-cooled;

[0047] Step 6, the Cu-Ag alloy rod blank obtained in step 5 is subjected to continuous multi-pass drawing, with a single-pass deformation amount of 15%, to obtain a rectangular flat wire with a cross-section of 2 mm×3 mm.

[0048] After testing, the Ag content in the Cu-Ag alloy rod blank obtained in step 1 is 6.19wt%, the tensile strength of the 1.45mm diameter Cu-Ag alloy wire obtained in step 4 can reach 595MPa, and the conductivity can reach 82.0%IACS. The tensile strength of the 1.45mm diameter Cu-Ag alloy wire obtained in step 6 can reach 895MPa, and the conductivity can reach 73.9%IACS.

[0049] Example 4

[0050] Preparation method of high-strength and high-conductivity copper-silver alloy wire:

[0051] Step 1: Prepare the alloy composition of 5.5wt.% Ag, 0.1wt.% Cu-Nb (Nb content 10wt%) master alloy, and the balance Cu, wherein the purity of Ag and Cu are both above 99.95wt.%. Place the above raw materials in a crucible of a downcast continuous casting furnace, place single Cu at the bottom of the crucible, and place single Ag above single Cu. Evacuate the furnace chamber to a temperature of <10 - 2 After that, argon gas was filled into the furnace until the pressure inside the furnace reached 0.02MPa, and the furnace chamber was evacuated again to a pressure of <10 -2 After Pa. Use an induction coil to start heating the raw materials in the crucible, heat the raw materials to 1000℃, flush with argon until the pressure in the furnace reaches 0.08MPa, continue heating until Cu begins to melt, and flush with argon until the pressure in the furnace reaches 0.1MPa. After heating the raw materials to 1280℃, refine for 20 minutes and start pulling the Cu-Ag-Nb alloy rod billet. The downward continuous casting pulling speed is 1.1mm / s, the diameter of the crystallizer used is 12mm, the crystallizer cooling water temperature is 24℃, and the flow rate at the crystallizer cooling water inlet is 30Lpm.

[0052] Step 2, the Cu-Ag alloy rod blank obtained in step 1 is kept at 780° C. for 2 hours and water-cooled;

[0053] Step 3, the Cu-Ag alloy rod blank obtained in step 2 is kept at 400° C. for 8 hours and air-cooled;

[0054] Step 4, the Cu-Ag alloy rod blank obtained in step 3 is subjected to continuous multi-pass drawing, with a single-pass deformation amount of 15%, to obtain a wire with a diameter of 1.45 mm.

[0055] After testing, the Ag content in the Cu-Ag alloy rod blank obtained in step 1 is 6.05wt%, the Nb content is 0.05wt%, and the 1.45mm diameter Cu-Ag alloy wire obtained in step 4 has a tensile strength of up to 740MPa and a conductivity of up to 84.0%IACS.

[0056] Example 5

[0057] Step 1: prepare the alloy composition of 6wt.% Ag, 0.03wt.% Cu-Nb (Nb content 10wt%) master alloy, and the balance Cu, wherein the purity of Ag and Cu are both above 99.95wt.%. Place the above raw materials in a crucible of a downcast continuous casting furnace, place single Cu at the bottom of the crucible, and place single Ag above single Cu. Evacuate the furnace chamber to a temperature of <10 - 2 After that, argon gas was filled into the furnace until the pressure inside the furnace reached 0.01 MPa, and the furnace chamber was evacuated again to a pressure of <10 -2 After Pa. Use an induction coil to start heating the raw materials in the crucible, heat the raw materials to 950°C, flush with argon until the pressure in the furnace reaches 0.07MPa, continue heating until Cu begins to melt, and flush with argon until the pressure in the furnace reaches 0.1MPa. After heating the raw materials to 1250°C, refine for 20 minutes and start pulling the Cu-Ag alloy rod billet. The downward continuous casting pulling speed is 0.9mm / s, which is increased to 1.3mm / s after 20 minutes of pulling. The diameter of the crystallizer used is 12mm, the crystallizer cooling water temperature is 28°C, and the flow rate at the crystallizer cooling water inlet is 36Lpm.

[0058] Step 2, the Cu-Ag alloy rod blank obtained in step 1 is kept at 830° C. for 2 hours and water-cooled;

[0059] Step 3, the Cu-Ag alloy rod blank obtained in step 2 is kept at 370° C. for 10 hours and air-cooled;

[0060] Step 4, the Cu-Ag alloy rod blank obtained in step 3 is subjected to continuous multi-pass drawing, with a single-pass deformation of 15%. After drawing to 1.45 mm, the single-pass deformation is adjusted to 10%, and a wire with a diameter of 0.8 mm is obtained.

[0061] After testing, the Ag content in the Cu-Ag alloy rod blank obtained in step 1 is 6.18wt%, the Nb content is 0.01wt%, and the 0.8mm diameter Cu-Ag alloy wire obtained in step 4 has a tensile strength of up to 1040MPa and a conductivity of up to 72.7%IACS.

[0062] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, and they should be covered by the protection scope of the present invention.

Claims

1. A high-strength and high-conductivity copper-silver alloy wire, characterized in that: The constituent elements and contents of the high-strength and high-conductivity copper-silver alloy wire meet the following requirements: Ag content is 1-15wt%, Nb content is ≤1wt%, and the rest is copper and unavoidable impurities, and the overall impurity content is less than 0.5wt%.

2. The high-strength and high-conductivity copper-silver alloy wire according to claim 1, characterized in that: The constituent elements and contents of the high-strength and high-conductivity copper-silver alloy wire meet the following requirements: Ag content is 3-7wt%, Nb content is 0-0.1wt%, and the rest is copper and unavoidable impurities, and the overall impurity content is less than 0.1wt%.

3. The high-strength and high-conductivity copper-silver alloy wire according to claim 1 or 2, characterized in that: The cross-section of the high-strength and high-conductivity copper-silver alloy wire includes but is not limited to a circular cross-section, a rectangular cross-section, a polygonal cross-section, other axisymmetric or centrally symmetrical cross-sections, and special-shaped cross-sections.

4. The method for preparing the high-strength and high-conductivity copper-silver alloy wire according to claim 1, characterized in that: The preparation steps and contents shall meet the following requirements in sequence: Step 1, mixing ingredients: mixing the raw materials single substance Ag, Cu-Nb master alloy and single substance Cu according to the composition ratio and the alloy ratio; wherein: Ag is pure silver, Cu is high-purity cathode copper, and the Nb content of the Cu-Nb master alloy is 10wt%; Step 2, pre-heating operation: add the raw materials into the vacuum continuous casting furnace, evacuate the furnace chamber to <10 -2 After the furnace pressure reaches 0.01 MPa, argon gas is filled in and the furnace chamber is evacuated to less than 10 -2 Pa; Step 3, heating in protective atmosphere: first, heat the raw material to 1000°C ± 20°C, with a heating rate of not less than 20°C / min, and inject argon until the pressure in the furnace reaches 0.07-0.08MPa; then continue heating until Cu begins to melt, inject argon until the pressure in the furnace reaches 0.1MPa; then heat the raw material again to 1250°C-1300°C and let it stand for 10-15 minutes, so as to start the subsequent pulling operation of Cu-Ag alloy rod billet; Step 4, performing a solution treatment on the Cu-Ag alloy rod blank; Step 5, performing aging treatment on the Cu-Ag alloy rod blank; Step 6, performing multiple-pass drawing on the Cu-Ag alloy rod blank; Step 7, annealing heat treatment is performed on the Cu-Ag alloy rod blank; finally, a high-strength and high-conductivity copper-silver alloy wire is prepared.

5. The method for preparing the high-strength and high-conductivity copper-silver alloy wire according to claim 4, characterized in that: The preparation steps and contents shall meet one or a combination of the following requirements in sequence: First, the mass percentage of pure Ag and pure high-purity cathode copper in the raw materials used in the ingredients described in step 1 is not less than 99.95%; Second, in step 6 and step 7, when pulling the Cu-Ag alloy rod billet, the continuous casting pulling speed is 0.5-2 mm / s, the diameter of the crystallizer is 8-12 mm, the crystallizer cooling water temperature is required to be no higher than 30°C, and the flow rate at the crystallizer cooling water inlet is no less than 30 Lpm; Third, the requirements for the solution treatment in step 4 are a solution temperature of 720-920°C and a holding time of 0-6h; Fourthly, the aging treatment in step 5 requires an aging temperature of 350-500°C and a holding time of 0-20h; Fifth, the requirements for multi-pass drawing in step 6 are as follows: the total processing rate of multi-pass drawing of Cu-Ag alloy is greater than 90%, and the processing rate of single-pass drawing does not exceed 30%; Sixth, the requirements for the annealing heat treatment in step 7 are an annealing temperature of 250-350°C and a holding time of 0-6h.

6. The method for preparing the high-strength and high-conductivity copper-silver alloy wire according to claim 4 or 5, characterized in that: In step 3, the casting process parameters must meet the following conditions: when the diameter of the crystallizer is less than 10 mm, the pulling speed must be no higher than 1 mm / s; when the diameter of the crystallizer is greater than 10 mm and less than 12 mm, the pulling speed must be no higher than 2 mm / s.

7. The method for preparing the high-strength and high-conductivity copper-silver alloy wire according to claim 4 or 5, characterized in that: During the implementation of step 7, the annealing temperature should not be higher than the aging temperature.

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