High-strength high-torsion-resistance high-conductivity copper alloy conductor for special cable and preparation method of high-strength high-torsion-resistance high-conductivity copper alloy conductor

Abstract

The invention discloses a high-strength, high-torsion-resistance and high-conductivity copper alloy conductor for a special cable and a preparation method and application of the high-strength, high-torsion-resistance and high-conductivity copper alloy conductor. The copper alloy conductor comprises the following raw material components in percentage by mass: 0.05 to 0.2 percent of Ag, 0.02 to 0.08 percent of Cr, 0.02 to 0.08 percent of Nb, 0.01 to 0.05 percent of Ce, 0.01 to 0.05 percent of Dy, 0.01 to 0.05 percent of Tb and the balance of Cu. The preparation method of the copper alloy conductor comprises the following steps: 1) adding each metal into a vacuum down-drawing furnace according to a formula, and carrying out vacuum melting to obtain a down-drawing rod material; (2) carrying out multi-pass high-temperature continuous stretching on the down-drawing rod material; (3) the rod material is subjected to multi-pass low-temperature continuous stretching; (4) carrying out low-temperature heat treatment on the rod material; and 5) finally, cleaning the surface of the rod material, and then electroplating a tin layer to obtain the copper alloy conductor. The copper matrix is microalloyed, the structure of the rod material is regulated and controlled through thermomechanical treatment, the tensile strength, the torsion resistance and the high-temperature aging resistance of the rod material are improved, the rod material can meet the conductor requirement of a special cable, the comprehensive performance of the cable is improved, the service life of the cable is prolonged, and the quality problem in the service process is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of conductors for special cables, and in particular relates to a high-strength, high-torsion-resistant and high-conductivity copper alloy conductor for special cables, and a preparation method and application thereof. Background Art

[0002] Special cables are in high-frequency torsion, high-temperature environment, and high-load working environment for a long time. During service, the copper conductor core is prone to breakage, which affects its service life. At present, pure copper wire is used as the conductor of special cables. Although it has excellent conductivity, its strength and torsion resistance are relatively low. The broken core of the conductor will not only affect the transmission of electricity, but also leave a greater safety hazard. Therefore, it is necessary to develop a high-strength, high-torsion-resistant, and high-conductivity copper alloy conductor to improve the mechanical properties of the conductor core, thereby increasing its service life.

[0003] As an excellent metal conductor, copper has two main ways to improve its mechanical properties: processing deformation and microalloying. However, while enhancing the mechanical properties, the electrical conductivity of copper will be reduced. The deformation amount, deformation temperature, deformation pass number, and type and addition amount of microalloying elements play an important role in regulating the performance.

[0004] Currently, pure copper wire is used as the conductor of special cables. When the prepared cables are subjected to high-frequency torsion, high-temperature environment, and high-load operation, the copper conductor core is prone to breakage, which causes the equipment to be unable to work continuously and has a short service life. The replacement cycle of special cables is long and difficult, resulting in high cost of use. Summary of the invention

[0005] The purpose of the present invention is to provide a high-strength, high-torsion-resistant and high-conductivity copper alloy conductor for special cables and a preparation method and application thereof in view of the problems existing in the prior art.

[0006] In order to achieve the above technical objectives, the present invention provides the following technical solutions:

[0007] The high-strength, high-torsion-resistant and high-conductivity copper alloy conductor for special cables provided by the present invention comprises the following raw material components in percentage by mass: Ag 0.05-0.2%, Cr 0.02-0.08%, Nb 0.02-0.08%, Ce 0.01-0.05%, Dy 0.01-0.05%, Tb 0.01-0.05%, and the balance is Cu.

[0008] Ag has higher electrical conductivity than Cu. With Cu-Ag alloy as the matrix, by adding a small amount of Cr, Nb and rare earth elements such as Ce, Dy, Tb, etc., the purity and mechanical properties of the alloy matrix can be improved through melt purification, grain refinement, second phase strengthening, etc. The added Cr, Nb, Ce, Dy, Tb elements have very low solid solubility in the copper matrix, and are uniformly precipitated during processing deformation and heat treatment, reducing their influence on conductivity.

[0009] The present invention also provides a method for preparing the high-strength, high-torsion-resistant and high-conductivity copper alloy conductor for the special cable, comprising the following steps:

[0010] 1) adding each metal into a vacuum down-drawing furnace according to the formula for vacuum melting to obtain down-drawing rods;

[0011] 2) performing multiple high-temperature continuous stretching on the lower lead rod obtained in step 1);

[0012] 3) Then the rod is subjected to multiple passes of low-temperature continuous stretching;

[0013] 4) Then the rod material is subjected to low temperature heat treatment;

[0014] 5) Finally, the rod material is surface cleaned and then electroplated with a tin layer to obtain a high-strength, high-torsion-resistant, and high-conductivity copper alloy conductor for the special cable.

[0015] Preferably, in step 1), the process conditions of vacuum smelting are: smelting temperature is 1250°C-1300°C, smelting time is 0.5-2h, lowering speed is 0.8-1.2m / min, and wire rod diameter is 9-11mm.

[0016] Preferably, in step 2), the process parameters involved in the multi-pass high-temperature continuous stretching are: temperature of 500° C.-700° C., stretching speed of 2-3 m / min, and total deformation of 80-95%.

[0017] Preferably, in step 3), the process parameters involved in the multi-pass low-temperature continuous stretching are: temperature of -30°C to -10°C, stretching speed of 8-12 m / min, and total deformation of 85-95%.

[0018] Preferably, in step 4), the temperature of the low temperature heat treatment is 200°C-300°C, and the time is 4-8h.

[0019] Preferably, in step 5), the thickness of the electroplated tin layer is 3-5 microns.

[0020] Beneficial effects of the present invention:

[0021] The present invention microalloys the copper matrix and adjusts the structure of the rod material through thermomechanical treatment to improve the tensile strength, torsion resistance and high temperature aging resistance of the rod material, so that it can meet the conductor requirements of special cables, improve the comprehensive performance and service life of the cable, and reduce quality problems during service. Specifically:

[0022] 1. The development of high-strength, high-torsion-resistant and high-conductivity copper alloy conductors can not only enhance the strength of cable conductors, but also improve the cable's resistance to high-temperature softening. It is the first choice as a special cable conductor material.

[0023] 2. Copper alloy rods are prepared by microalloying the copper matrix and adding Ag, Cr, Nb, Ce, Dy, Tb and other elements. The rods are pre-stretched at high temperature so that the alloy elements are precipitated separately under the action of high temperature deformation, reducing the solid solution of the alloy elements and forming a copper-R (alloy element) separation structure to ensure that the electrical conductivity of the alloy will not be significantly reduced. The copper-R (alloy element) separation structure is cold deformed at -30℃ to -10℃ to form a copper-R layered fiber deformation structure, which improves the strength of the alloy wire and enhances the axial toughness of the wire.

[0024] 3. The deformed structure is subjected to low temperature heat treatment at 200℃-300℃, which can not only eliminate the participating stress generated during the deformation process, but also maintain the fiber deformation structure, further improving the comprehensive performance of the alloy rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the metallographic diagram of the copper alloy rod after continuous stretching at high temperature;

[0026] Figure 2 It is the metallographic diagram of copper alloy wire after continuous stretching at low temperature;

[0027] Figure 3 is the tensile stress-strain curve of Example 1. DETAILED DESCRIPTION

[0028] Example 1

[0029] The metals Ag, Cr, Nb, Ce, Dy and Tb are weighed, and the weights are Ag (100g), Cr (60g), Nb (60g), Ce (30g), Dy (30g), Tb (30g), and the rest is Cu, totaling 100Kg, of which Ce, Dy and Tb are wrapped with 0.1mm thick copper. The well-proportioned raw materials are placed in a vacuum lower furnace for vacuum melting, the melting temperature is 1260℃, the melting time is 1h, the lowering speed is 1.0m / min, and the wire rod diameter is 10mm. The copper rod is hot-drawn by high-temperature continuous stretching, the temperature is 600℃, the stretching speed is 2.5m / min, the total deformation is 90%, the deformation pass is 40%-20%-20%-10%, and a copper wire with a wire diameter of 1.0mm is obtained. The copper wire is cold drawn by low-temperature continuous drawing, with a temperature of -20°C, a drawing speed of 10m / min, a total deformation of 90%, and a deformation pass of 30%-20%-20%-10%-10%, to obtain a copper wire with a wire diameter of 0.1mm. The copper wire is subjected to a low-temperature heat treatment at a temperature of 250°C for 6 hours to remove the residual deformation stress, and then a 4-micron tin protective layer is formed on the surface by an electroplating tin process to obtain the final high-strength, high-torsion-resistant, and high-conductivity copper alloy conductor.

[0030] Example 2

[0031] The metals Ag, Cr, Nb, Ce, Dy and Tb are weighed, and the weights are Ag (100g), Cr (40g), Nb (40g), Ce (20g), Dy (20g), Tb (20g), and the rest is Cu, totaling 100Kg, of which Ce, Dy and Tb are wrapped with 0.1mm thick copper. The well-proportioned raw materials are placed in a vacuum down-drawing furnace for vacuum melting, the melting temperature is 1270℃, the melting time is 1h, the down-drawing speed is 1.0m / min, and the wire rod diameter is 10mm. The copper rod is hot-drawn by high-temperature continuous stretching, the temperature is 600℃, the stretching speed is 3.0m / min, the total deformation is 90%, the deformation pass is 40%-20%-20%-10%, and a copper wire with a wire diameter of 1.0mm is obtained. The copper wire is cold drawn by low-temperature continuous drawing, with a temperature of -20°C, a drawing speed of 10m / min, a total deformation of 90%, and a deformation pass of 30%-20%-20%-10%-10%, to obtain a copper wire with a wire diameter of 0.1mm. The copper wire is subjected to a low-temperature heat treatment at a temperature of 250°C for 6 hours to remove the residual deformation stress, and then a 4-micron tin protective layer is formed on the surface by an electroplating tin process to obtain the final high-strength, high-torsion-resistant, and high-conductivity copper alloy conductor.

[0032] Example 3

[0033] The metals Ag, Cr, Nb, Ce, Dy and Tb are weighed, and the weights are Ag (100g), Cr (20g), Nb (20g), Ce (10g), Dy (10g), Tb (10g), and the rest is Cu, totaling 100Kg, of which Ce, Dy and Tb are wrapped with 0.1mm thick copper. The well-proportioned raw materials are placed in a vacuum down-drawing furnace for vacuum melting, the melting temperature is 1280℃, the melting time is 1h, the down-drawing speed is 1.0m / min, and the wire rod diameter is 10mm. The copper rod is hot-drawn by high-temperature continuous stretching, the temperature is 600℃, the stretching speed is 3.0m / min, the total deformation is 90%, the deformation pass is 40%-20%-20%-10%, and a copper wire with a wire diameter of 1.0mm is obtained. The copper wire is cold drawn by low-temperature continuous drawing, with a temperature of -20°C, a drawing speed of 10m / min, a total deformation of 90%, and a deformation pass of 30%-20%-20%-10%-10%, to obtain a copper wire with a wire diameter of 0.1mm. The copper wire is subjected to a low-temperature heat treatment at a temperature of 250°C for 6 hours to remove the residual deformation stress, and then a 4-micron tin protective layer is formed on the surface by an electroplating tin process to obtain the final high-strength, high-torsion-resistant, and high-conductivity copper alloy conductor.

[0034] Example 4

[0035] The metals Ag, Cr, Nb, Ce, Dy and Tb are weighed, and the weights are Ag (100g), Cr (80g), Nb (80g), Ce (50g), Dy (50g), Tb (50g), and the rest is Cu, totaling 100Kg, of which Ce, Dy and Tb are wrapped with 0.1mm thick copper. The well-proportioned raw materials are placed in a vacuum lower furnace for vacuum melting, the melting temperature is 1280℃, the melting time is 1h, the lowering speed is 1.0m / min, and the wire rod diameter is 10mm. The copper rod is hot-drawn by high-temperature continuous stretching, the temperature is 600℃, the stretching speed is 3.0m / min, the total deformation is 90%, the deformation pass is 40%-20%-20%-10%, and a copper wire with a wire diameter of 1.0mm is obtained. The copper wire is cold drawn by low-temperature continuous drawing, with a temperature of -20°C, a drawing speed of 10m / min, a total deformation of 90%, and a deformation pass of 30%-20%-20%-10%-10%, to obtain a copper wire with a wire diameter of 0.1mm. The copper wire is subjected to a low-temperature heat treatment at a temperature of 250°C for 6 hours to remove the residual deformation stress, and then a 4-micron tin protective layer is formed on the surface by an electroplating tin process to obtain the final high-strength, high-torsion-resistant, and high-conductivity copper alloy conductor.

[0036] Example 5

[0037] Compared with Example 1, the difference is that the weight of the added Ag element is 50 g, and the other steps are exactly the same.

[0038] Example 6

[0039] Compared with Example 1, the difference is that the weight of the added Ag element is 200 g, and the other steps are exactly the same.

[0040] Example 7

[0041] Compared with Example 1, the differences are Cr (80 g), Nb (80 g), Ce (10 g), Dy (10 g), and Tb (10 g), and the other steps are exactly the same.

[0042] Example 7

[0043] Compared with Example 1, the differences are Cr (20 g), Nb (20 g), Ce (50 g), Dy (50 g), and Tb (50 g), and the other steps are exactly the same.

[0044] Comparative Example 1

[0045] Compared with Example 1, the difference is that no alloy elements Ag, Cr, Nb, Ce, Dy, and Tb are added, pure copper is used for preparation, and the other steps are exactly the same.

[0046] Comparative Example 2

[0047] Compared with Example 1, the difference is that Ag, Cr, Nb, Ce, Dy, and Tb alloy elements are not added and normal continuous stretching is adopted at room temperature, and the other steps are exactly the same.

[0048] Comparative Example 3

[0049] Compared with Example 1, the difference is that Cr and Nb alloy elements are not added, and the other steps are exactly the same.

[0050] Comparative Example 4

[0051] Compared with Example 1, the difference is that the alloy elements Ce, Dy and Tb are not added, and the other steps are exactly the same.

[0052] Comparative Example 5

[0053] Compared with Example 1, the difference is that high-temperature continuous stretching and low-temperature continuous stretching are not used, and normal continuous stretching at room temperature is used, and the other steps are exactly the same.

[0054] Comparative Example 6

[0055] Compared with Example 1, the difference is that high-temperature continuous stretching is not used, and normal continuous stretching at room temperature is used to stretch the copper rod from 10 mm to 1 mm, and the other steps are exactly the same.

[0056] Comparative Example 7

[0057] Compared with Example 1, the difference is that low-temperature continuous stretching is not used, and normal continuous stretching at room temperature is used to stretch the copper rod from 1 mm to 0.1 mm, and the other steps are exactly the same.

[0058] Table 1 shows the added element content and processing deformation mode of each embodiment

[0059] serial number Ag Cr Nb Ce Dy Tb High temperature stretching Low temperature stretching Example 1 100g 60g 60g 30g 30g 30g 600℃ -20℃ Example 2 100g 40g 40g 20g 20g 20g 600℃ -20℃ Example 3 100g 20g 20g 10g 10g 10g 600℃ -20℃ Example 4 100g 80g 80g 50g 50g 50g 600℃ -20℃ Example 5 50g 60g 60g 30g 30g 30g 600℃ -20℃ Example 6 200g 60g 60g 30g 30g 30g 600℃ -20℃ Example 7 100g 80g 80g 10g 10g 10g 600℃ -20℃ Example 8 100g 20g 20g 50g 50g 50g 600℃ -20℃ Comparative Example 1 0g 0g 0g 0g 0g 0g 600℃ -20℃ Comparative Example 2 0g 0g 0g 0g 0g 0g 20℃ 20℃ Comparative Example 3 100g 0g 0g 30g 30g 30g 600℃ -20℃ Comparative Example 4 100g 60g 60g 0g 0g 0g 600℃ -20℃ Comparative Example 5 100g 60g 60g 30g 30g 30g 20℃ 20℃ Comparative Example 6 100g 60g 60g 30g 30g 30g 20℃ -20℃ Comparative Example 7 100g 60g 60g 30g 30g 30g 600℃ 20℃

[0060] Table 2 shows the properties of the copper wires prepared in various embodiments.

[0061] serial number Tensile strength(Mpa) <![CDATA[Resistivity (Ω.mm 2 / m)]]> Electrical conductivity (IACS%) Elongation(%) Reciprocating twist (times) Example 1 318 0.001858 92.8 32 15447 Example 2 301 0.001850 93.2 33 13894 Example 3 288 0.001844 93.5 34 12745 Example 4 332 0.001916 90.1 28 15847 Example 5 303 0.001838 93.8 34 13948 Example 6 345 0.001950 88.4 27 16248 Example 7 314 0.001854 93.0 32 15211 Example 8 315 0.001852 93.1 32 15289 Comparative Example 1 238 0.001706 101.06 41 8567 Comparative Example 2 229 0.001703 101.23 41 7823 Comparative Example 3 292 0.001846 93.4 34 12956 Comparative Example 4 295 0.001848 93.3 34 13051 Comparative Example 5 298 0.001852 93.1 32 13385 Comparative Example 6 307 0.001858 92.8 32 14151 Comparative Example 7 309 0.001856 92.9 32 14205

[0062] As can be seen from Table 2, the performance of copper alloy wire is closely related to the type, content and processing deformation of the added alloying elements. As the type and content of the alloying elements increase, the conductivity gradually decreases and the mechanical strength gradually increases, thereby improving its resistance to reciprocating torsion. The main reason is that the alloying elements exist in the copper matrix in the form of a second phase or solid solution, and the tensile strength of the matrix is ​​enhanced through the second phase strengthening and solid solution strengthening mechanism. At the same time, some elements are solid-dissolved in the matrix, resulting in a decrease in electrical properties and an increase in resistivity. The use of high-temperature continuous stretching and low-temperature continuous stretching methods will also enhance the strength of copper alloy wires. The main reason is that high-temperature continuous stretching eliminates pores, loose structures and other structures generated during the casting process, and the density of the copper wire is improved. At the same time, high-temperature continuous stretching allows the alloying elements to precipitate separately under the action of high-temperature deformation, reducing the solid solution amount of the alloying elements, forming a copper-R (alloying element) separation structure, and ensuring that the conductivity of the alloy will not be significantly reduced. Low-temperature continuous stretching increases the deformation difficulty of the copper wire, forming a copper-R layered fiber deformation structure, improving the strength of the alloy wire, and enhancing the axial toughness of the wire. By comparing the performance of Examples 1-8, it can be seen that when the amount of alloying elements added is small, the tensile strength increases significantly and the electrical properties decrease insignificantly, but when the amount of alloying elements added gradually increases, the electrical properties decrease significantly. Therefore, it is necessary to select an appropriate amount of alloying elements added in combination with the actual required performance to ensure that the cost of the alloy wire is reasonable. By comparing the performance of Example 1 and Comparative Examples 1-7, it can be seen that the addition of alloying elements and the use of high temperature / low temperature combined stretching increase the tensile strength by 38.86%, the number of reciprocating torsions increases by 97.45%, and the electrical conductivity only decreases by 8.3%, indicating that the performance of the copper alloy wire is greatly improved and can meet the working conditions of special cables.

Claims

1. A high-strength, high-torsion-resistance, high-conductivity copper alloy conductor for special cables, characterized in that: The copper alloy conductor comprises the following raw material components in mass percentage: Ag 0.05-0.2%, Cr 0.02-0.08%, Nb 0.02-0.08%, Ce 0.01-0.05%, Dy 0.01-0.05%, Tb 0.01-0.05%, and the balance is Cu.

2. A method for preparing the high-strength, high-torsion-resistant and high-conductivity copper alloy conductor for special cables as claimed in claim 1, comprising the following steps: 1) adding each metal into a vacuum down-drawing furnace according to the formula of claim 1 for vacuum melting to obtain down-drawing rods; 2) performing multiple high-temperature continuous stretching on the lower lead rod obtained in step 1); 3) Then the rod is subjected to multiple passes of low-temperature continuous stretching; 4) Then the rod material is subjected to low temperature heat treatment; 5) Finally, the rod material is surface cleaned and then electroplated with a tin layer to obtain a high-strength, high-torsion-resistant, and high-conductivity copper alloy conductor for the special cable.

3. The preparation method according to claim 2, characterized in that: In step 1), the process conditions of vacuum smelting are: smelting temperature is 1250° C.-1300° C., smelting time is 0.5-2 h, lowering speed is 0.8-1.2 m / min, and wire rod diameter is 9-11 mm.

4. The preparation method according to claim 2, characterized in that: In step 2), the process parameters involved in the multi-pass high-temperature continuous stretching are: temperature of 500° C.-700° C., stretching speed of 2-3 m / min, and total deformation of 80-95%.

5. The preparation method according to claim 2, characterized in that: In step 3), the process parameters involved in the multi-pass low-temperature continuous stretching are: temperature of -30°C to -10°C, stretching speed of 8-12 m / min, and total deformation of 85-95%.

6. The preparation method according to claim 2, characterized in that: In step 4), the temperature of the low temperature heat treatment is 200° C.-300° C., and the time is 4-8 hours.

7. The preparation method according to claim 2, characterized in that: In step 5), the thickness of the electroplated tin layer is 3-5 microns.

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