Composite low sag type aluminum clad steel core high conductivity aluminum stranded conductor

Abstract

The present application relates to the technical field of aluminum-clad steel core aluminum stranded wire, and proposes a composite low sag type aluminum-clad steel core high-conductivity aluminum stranded wire, which is obtained by twisting the aluminum-clad steel stranded wire arranged at the core and the aluminum wire arranged at the outer periphery of the core, and a preparation method of the aluminum-clad steel stranded wire, which comprises the following steps: S1, removing the carbon steel oxide skin and then performing cold drawing treatment to obtain a steel wire; S2, quenching the steel wire to obtain a pretreated steel wire; S3, extruding aluminum outside the pretreated steel wire to form an aluminum-clad steel wire; S4, stretching the aluminum-clad steel wire to obtain a stretched aluminum-clad steel wire; and S5, twisting the stretched aluminum-clad steel wire according to the specifications to obtain the aluminum-clad steel stranded wire; in step S2, the quenching treatment is first quenching at 550-600 DEG C for 25-35 s, and then quenching at 450-500 DEG C for 5-10 s. Through the above technical scheme, the problems of low conductivity and high sag in the related art are solved.

Description

Technical Field

[0001] This invention relates to the field of aluminum-clad steel core aluminum stranded wire technology, specifically to a composite low-sag aluminum-clad steel core high-conductivity aluminum stranded wire. Background Technology

[0002] Ultra-high voltage (UHV) power transmission and new energy grid connection are developing towards longer distances, larger spans, and higher capacities, thus placing increasingly stringent requirements on transmission line materials. Aluminum-clad steel-cored aluminum stranded wire, due to its combination of good conductivity and mechanical strength, is suitable for complex environments and has become a core material for high-voltage power transmission. Low sag is a key indicator for ensuring line safety, improving efficiency, and reducing costs.

[0003] However, the methods used to achieve low sag, such as reducing the cross-section, optimizing the pitch, and lightweight design, will significantly reduce the mechanical properties of aluminum-clad steel core aluminum stranded wire, making it prone to deformation, strand breakage, and fracture. High-conductivity aluminum material itself is mechanically weak, and the combination with lightweight design further exacerbates the mechanical deficiencies, forming a vicious cycle that makes it impossible to simultaneously achieve low sag, high conductivity, and high mechanical properties.

[0004] Therefore, it is necessary to propose a composite low-sag aluminum-clad steel core high-conductivity aluminum stranded wire. Summary of the Invention

[0005] This invention proposes a composite low-sag aluminum-clad steel core high-conductivity aluminum stranded wire, which solves the problems of low conductivity and high sag in related technologies.

[0006] The technical solution of the present invention is as follows: This invention proposes a composite low-sag aluminum-clad steel core high-conductivity aluminum stranded wire, which is obtained by stranding aluminum-clad steel stranded wire in the core and aluminum wire in the outer periphery of the core. The preparation method of the aluminum-clad steel stranded wire includes the following steps: S1. After removing the oxide scale from the carbon steel, it is cold-drawn to obtain steel wire; S2. The steel wire is quenched to obtain pretreated steel wire; S3. Extruding aluminum over the pretreated steel wire to form aluminum-clad steel wire; S4. Stretch the aluminum-clad steel wire to obtain the stretched aluminum-clad steel wire. S5. After stretching, the aluminum-clad steel wires are twisted together according to specifications to obtain aluminum-clad steel stranded wire; In step S2, the quenching process involves first quenching at 550~600℃ for 25~35s, then cooling to 450~500℃ for 5~10s, and finally cooling to room temperature.

[0007] As a further technical solution, in step S2, the temperature is first quenched at 550~600℃ for 25~35s, then cooled to 450~500℃ for 5~10s at a rate of 4~8℃ / s, and then cooled to room temperature.

[0008] As a further technical solution, in step S1, the drawing speed of the cold drawing process is 1~2m / s.

[0009] As a further technical solution, in step S1, the pass compression rate of the cold drawing process is 15%~20%, and the wire temperature is less than 140℃.

[0010] As a further technical solution, in step S4, the stretching is a multi-pass stretching, and the total compression rate of the stretching is 68%~72%.

[0011] As a further technical solution, the stretching is performed in 5 passes, the stretching rate is 4~6m / s, and the compression ratio of the first and second passes is higher than that of the third and fourth passes, while the compression ratio of the third and fourth passes is higher than that of the fifth pass.

[0012] As a further technical solution, the compression ratio of the first pass is greater than or equal to the compression ratio of the second pass, and the compression ratio of the third pass is greater than or equal to the compression ratio of the fourth pass.

[0013] As a further technical solution, the compression ratio of the first, second, third, fourth and fifth passes is 14.8:14.8:14.4:14:14.

[0014] The controlled reduction in compression ratio across multiple passes, as defined in this invention, avoids the following: excessive reduction in compression ratio leads to internal defects in the stretched aluminum-clad steel wire, disrupting the interfacial bond between the aluminum layer and the steel wire, resulting in decreased tensile strength. Conversely, insufficient reduction in compression ratio leads to inadequate work hardening, also causing a decrease in tensile strength. Therefore, this invention, by gradually reducing the compression ratio over five passes, avoids excessive deformation that could cause microcracks and interfacial defects, further ensuring uniform deformation and the bonding between the aluminum layer and the steel wire, thereby improving the tensile strength of the stretched aluminum-clad steel wire.

[0015] As a further technical solution, step S5 specifically involves: after aluminum-clad steel wires are stranded according to specifications, they undergo aging treatment to obtain aluminum-clad steel stranded wire.

[0016] As a further technical solution, the aging treatment is to first age at 120~140℃ for 0.5~1.5h, then age at 170~190℃ for 1~1.5h, and finally age at 200~230℃ for 0.5~1.5h, and then cool to room temperature.

[0017] This invention employs a three-stage stepped aging treatment: first low temperature, then medium temperature, and finally high temperature. This process can gradually eliminate residual stress and lattice distortion generated during the stretching process of aluminum-clad steel wire, reduce crystal defects, and improve the electrical conductivity of the aluminum-clad steel wire. If the process conditions of the aging treatment are changed, the internal stress will not be sufficiently eliminated, and the electrical conductivity will not be improved significantly.

[0018] As a further technical solution, the oxide scale is treated by belt sanding.

[0019] The working principle and beneficial effects of this invention are as follows: This invention improves the tensile strength of aluminum-clad steel strands through two-stage quenching. Specifically, the strands are first quenched at 550-600℃ for 25-35 seconds, then cooled to 450-500℃ for 5-10 seconds. The first stage of high-temperature quenching strengthens the microstructure, while the second stage of medium-temperature quenching refines the grains, resulting in a more uniform and dense microstructure. This improves the tensile strength of the steel wire after stretching, thereby enhancing the tensile strength of the aluminum-clad steel strands. Consequently, the aluminum-clad steel core aluminum strands obtained by stranding aluminum wires exhibit higher tensile strength, better meeting the requirements for low sag. Furthermore, comparative experiments showed that the tensile strength of the stretched aluminum-clad steel wires prepared using a single-stage quenching process was lower. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1 A composite low-sag aluminum-clad steel core high-conductivity aluminum stranded wire is obtained by stranding aluminum-clad steel stranded wire in the core and aluminum wire in the outer periphery of the core. The preparation method of aluminum-clad steel strand includes the following steps: S1. After removing the oxide scale from the carbon steel (Q235) by sanding with a belt, it is cold-drawn at a speed of 1m / s. The temperature of the steel wire is controlled at 135℃ during the process, and the compression rate of the cold drawing pass is 15% to obtain the steel wire. S2. The steel wire is first quenched at 550℃ for 35s, then cooled to 450℃ for 10s at a rate of 4℃ / s, and then cooled to room temperature to obtain pretreated steel wire. S3. Extruding aluminum over the pretreated steel wire to form aluminum-clad steel wire; S4. The aluminum-clad steel wire is stretched at a stretching rate of 4 m / s, and the total compression rate of the stretching is 68%. Five stretching passes are performed. The compression rates of the first, second, third, fourth and fifth passes are 14.2%, 14%, 13.5%, 13.3% and 13%, respectively, to obtain the stretched aluminum-clad steel wire. S5. After stretching, the aluminum-clad steel wires are twisted together according to specifications to obtain aluminum-clad steel strands.

[0022] Example 2 A composite low-sag aluminum-clad steel core high-conductivity aluminum stranded wire is obtained by stranding aluminum-clad steel stranded wire in the core and aluminum wire in the outer periphery of the core. The preparation method of aluminum-clad steel strand includes the following steps: S1. After removing the oxide scale from the carbon steel (Q235) by sanding with a belt, it is cold-drawn at a speed of 2m / s. The temperature of the steel wire is controlled at 135℃ during the process, and the compression rate of the cold drawing pass is 20% to obtain the steel wire. S2. The steel wire is first quenched at 600℃ for 25s, then cooled to 500℃ for 5s at a rate of 4℃ / s, and then cooled to room temperature to obtain pretreated steel wire. S3. Extruding aluminum over the pretreated steel wire to form aluminum-clad steel wire; S4. The aluminum-clad steel wire is stretched at a stretching rate of 6 m / s, with a total compression rate of 72%, for 5 passes. The compression rates of the first, second, third, fourth, and fifth passes are 15.5%, 15%, 14.5%, 14%, and 13%, respectively, to obtain the stretched aluminum-clad steel wire. S5. After stretching, the aluminum-clad steel wires are twisted together according to specifications to obtain aluminum-clad steel strands.

[0023] Example 3 Compared with Example 2, the only difference in this example is that in step S2, the steel wire is first quenched at 600°C for 25 seconds, then cooled to 500°C for 5 seconds at a rate of 8°C / s, and then cooled to room temperature to obtain pretreated steel wire.

[0024] Example 4 Compared with Example 2, the only difference in this example is that in step S2, the steel wire is first quenched at 600°C for 25 seconds, then cooled to 500°C for 5 seconds at a rate of 2°C / s, and then cooled to room temperature to obtain pretreated steel wire.

[0025] Example 5 Compared with Example 2, the only difference in this example is that in step S2, the steel wire is first quenched at 600°C for 25 seconds, then cooled to 500°C for 5 seconds at a rate of 10°C / s, and then cooled to room temperature to obtain pretreated steel wire.

[0026] Example 6 Compared with Example 2, the only difference in this example is that the compression rates of steps S4, the first pass, the second pass, the third pass, the fourth pass, and the fifth pass are 14.8%, 14.8%, 14.4%, 14%, and 14%, respectively.

[0027] Example 7 Compared with Example 2, the only difference in this example is that the compression rates of step S4, the first pass, the second pass, the third pass, the fourth pass, and the fifth pass are 14.8%, 14.4%, 14.4%, 14.2%, and 14.2%, respectively.

[0028] Example 8 Compared with Example 2, the only difference in this example is that, in S5, after the stretched aluminum-clad steel wires are stranded according to specifications, they are subjected to aging treatment to obtain aluminum-clad steel strands; wherein the aging treatment is first aging at 120°C for 1.5 hours, then aging at 170°C for 1.5 hours, and finally aging at 200°C for 1.5 hours, and then cooling to room temperature.

[0029] Example 9 Compared with Example 2, the only difference in this example is that, in S5, after the stretched aluminum-clad steel wires are stranded according to specifications, they are subjected to aging treatment to obtain aluminum-clad steel strands; wherein the aging treatment is first aging at 140℃ for 0.5h, then aging at 190℃ for 1h, and finally aging at 230℃ for 0.5h, and then cooling to room temperature.

[0030] Example 10 Compared with Example 2, the only difference in this example is that, in S5, after the stretched aluminum-clad steel wires are stranded according to specifications, they are subjected to aging treatment to obtain aluminum-clad steel strands; wherein the aging treatment is first aging at 140℃ for 0.5h, then aging at 190℃ for 1.5h, and then cooling to room temperature.

[0031] Example 11 Compared with Example 2, the only difference in this example is that, in S5, after stretching, the aluminum-clad steel wires are stranded according to specifications and then subjected to aging treatment to obtain aluminum-clad steel strands; wherein the aging treatment is first aging at 140℃ for 0.5h, then aging at 230℃ for 1.5h, and then cooling to room temperature.

[0032] Comparative Example 1 Compared with Example 2, the only difference in this comparative example is that in step S2, the steel wire is quenched at 600°C for 30 seconds and then cooled to room temperature to obtain pretreated steel wire.

[0033] Comparative Example 2 Compared with Example 2, the only difference in this comparative example is that in step S2, the steel wire is quenched at 500°C for 30 seconds and then cooled to room temperature to obtain pretreated steel wire.

[0034] Experimental Example 1 According to ASTM E8 / 8M The 2013 test method used a universal testing machine to test the tensile strength of the aluminum-clad steel wires in Examples 1-7 and Comparative Examples 1-2 after stretching. Tensile strength = maximum load at break of the aluminum-clad steel wire (N) / cross-sectional area of ​​the stretched aluminum-clad steel wire (mm²). 2 The measurement results are shown in Table 1 below: Table 1. Tensile strength test results of aluminum-clad steel wires after stretching in Examples 1-7 and Comparative Examples 1-2.

[0035] Compared with Example 2, Comparative Examples 1 and 2 changed the quenching process. As a result, the tensile strength of the aluminum-clad steel wire after stretching in Example 2 was higher than that in Comparative Examples 1 and 2, indicating that the limitation of the quenching process in this invention can improve the tensile strength of the aluminum-clad steel wire after stretching and reduce the sag during use.

[0036] Compared with Examples 2 and 3, Examples 4 and 5 changed the cooling rate. As a result, the tensile strength of the aluminum-clad steel wire after stretching in Examples 2 and 3 was higher than that in Examples 4 and 5, indicating that a cooling rate of 4 to 8°C / s can better improve the tensile strength and reduce sag during use.

[0037] Compared to Example 2, Examples 6 and 7 changed the compression ratio of the multi-pass stretching. As a result, the tensile strength of Example 6 was higher than that of Example 7 and Example 2, indicating that the multi-pass compression ratio specified in Example 6 can further improve the tensile strength and reduce the sag during use.

[0038] Experiment Example 2 After measuring the resistance of the stretched aluminum-clad steel wire in Examples 2 and 8-11 using a digital DC bridge, the conductivity was calculated, and the calculation results are shown in Table 2 below. Table 2. Conductivity Measurement Results of Aluminum-Clad Steel Wires After Stretching in Examples 2 and 8-11

[0039] Compared with Example 2, Examples 8-11 added an aging treatment. As a result, the electrical conductivity of the aluminum-clad steel wire in Examples 8-11 was higher than that in Example 2, indicating that adding an aging treatment can improve the electrical conductivity of the stretched aluminum-clad steel wire.

[0040] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A composite low-sag aluminum-clad steel core high-conductivity aluminum stranded wire, characterized in that, The aluminum-clad steel stranded wire is obtained by stranding aluminum-clad steel strands located on the core and aluminum wires located on the outer periphery of the core. The preparation method of the aluminum-clad steel stranded wire includes the following steps: S1. After removing the oxide scale from the carbon steel, it is cold-drawn to obtain steel wire; S2. The steel wire is quenched to obtain pretreated steel wire; S3. Extruding aluminum over the pretreated steel wire to form aluminum-clad steel wire; S4. Stretch the aluminum-clad steel wire to obtain the stretched aluminum-clad steel wire. S5. After stretching, the aluminum-clad steel wires are twisted together according to specifications to obtain aluminum-clad steel stranded wire; In step S2, the quenching process involves first quenching at 550~600℃ for 25~35s, then cooling to 450~500℃ for 5~10s, and finally cooling to room temperature.

2. The composite low-sag aluminum-clad steel core high-conductivity aluminum stranded wire according to claim 1, characterized in that, In step S2, the temperature is first quenched at 550~600℃ for 25~35s, then cooled to 450~500℃ for 5~10s at a rate of 4~8℃ / s, and then cooled to room temperature.

3. The composite low-sag aluminum-clad steel core high-conductivity aluminum stranded wire according to claim 1, characterized in that, In step S1, the drawing speed of the cold drawing process is 1~2m / s.

4. The composite low-sag aluminum-clad steel core high-conductivity aluminum stranded wire according to claim 1, characterized in that, In step S1, the compression rate of the cold drawing process is 15%~20%, and the wire temperature is less than 140℃.

5. The composite low-sag aluminum-clad steel core high-conductivity aluminum stranded wire according to claim 1, characterized in that, In step S4, the stretching is a multi-pass stretching, and the total compression rate of the stretching is 68%~72%.

6. The composite low-sag aluminum-clad steel core high-conductivity aluminum stranded wire according to claim 5, characterized in that, The stretching is performed in 5 passes at a rate of 4-6 m / s. The compression ratios of the first and second passes are higher than those of the third and fourth passes, and the compression ratios of the third and fourth passes are higher than those of the fifth pass.

7. The composite low-sag aluminum-clad steel core high-conductivity aluminum stranded wire according to claim 6, characterized in that, The compression ratio of the first pass is greater than or equal to the compression ratio of the second pass, and the compression ratio of the third pass is greater than or equal to the compression ratio of the fourth pass.

8. The composite low-sag aluminum-clad steel core high-conductivity aluminum stranded wire according to claim 1, characterized in that, Step S5 specifically involves: after aluminum-clad steel wires are stranded according to specifications, they undergo aging treatment to obtain aluminum-clad steel stranded wire.

9. A composite low-sag aluminum-clad steel core high-conductivity aluminum stranded wire according to claim 8, characterized in that, The aging process involves first aging at 120-140℃ for 0.5-1.5 hours, then aging at 170-190℃ for 1-1.5 hours, and finally aging at 200-230℃ for 0.5-1.5 hours, followed by cooling to room temperature.

10. A composite low-sag aluminum-clad steel core high-conductivity aluminum stranded wire according to claim 1, characterized in that, The oxide scale is treated by belt sanding.

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