A high conductivity steel-cored aluminum stranded wire and its preparation method

Abstract

This invention relates to the field of steel-cored aluminum stranded wire technology, and proposes a high-conductivity steel-cored aluminum stranded wire and its preparation method. A high-conductivity steel-cored aluminum stranded wire comprises a galvanized steel core and aluminum wire stranded on the surface of the galvanized steel core. The aluminum wire is composed of the following components by weight percentage: Fe 0.09%~0.10%, B 0.015%~0.045%, Si 0.03%~0.05%, La 0.015%~0.020%, with the balance being Al and unavoidable impurities, wherein the relationship (Fe+Si) / La = 7.5~8 is satisfied. This technical solution solves the problem of low conductivity in steel-cored aluminum stranded wires in related technologies.

Description

Technical Field

[0001] This invention relates to the field of steel-cored aluminum stranded wire technology, specifically to a high-conductivity steel-cored aluminum stranded wire and its preparation method. Background Technology

[0002] Steel-cored aluminum stranded wire is the most commonly used conductor in overhead power transmission lines. Its structure mainly consists of an internal steel core that bears the mechanical load and external layers of aluminum stranded wire that carry the electrical energy. It is widely used in high-voltage and ultra-high-voltage overhead transmission lines and is the core carrier for long-distance power transmission in power grids.

[0003] In practical engineering applications, conductivity is a key indicator for measuring the power transmission capacity of conventional steel-cored aluminum stranded wires. However, existing steel-cored aluminum stranded wires still have shortcomings in conductivity performance. When the conductor conductivity is too low, Joule losses increase significantly during energized operation, resulting in a large amount of electrical energy being lost as heat, reducing power grid transmission efficiency, and increasing line operating energy costs. Simultaneously, increased conductor heating raises the conductor's operating temperature, causing thermal expansion and elongation, increasing line sag, and making it prone to discharges to ground or intersecting objects, leading to safety hazards such as short circuits and tripping. Furthermore, long-term high-temperature service accelerates the oxidation and corrosion of the aluminum strands and steel core, reducing the conductor's mechanical strength and shortening its overall service life.

[0004] Therefore, it is very necessary to develop a high conductivity steel-cored aluminum stranded wire. Summary of the Invention

[0005] This invention proposes a high conductivity steel-cored aluminum stranded wire and its preparation method to solve or alleviate the above-mentioned problems.

[0006] The technical solution of the present invention is as follows: This invention proposes a high conductivity steel-cored aluminum stranded wire, comprising a galvanized steel core and aluminum wire stranded on the surface of the galvanized steel core. The aluminum wire is composed of the following components by weight percentage: Fe 0.09%~0.10%, B 0.015%~0.045%, Si 0.03%~0.05%, La 0.015%~0.020%, with the balance being Al and unavoidable impurities, wherein the relationship (Fe+Si) / La = 7.5~8 is satisfied.

[0007] Preferably, the Fe / Si ratio is 2~3.

[0008] Preferably, the method for preparing the aluminum wire includes the following steps: distributing materials according to the target composition, melting, refining, casting, rolling, and drawing to obtain the aluminum wire.

[0009] Preferably, the method for preparing the galvanized steel core includes the following steps: the steel wire is surface treated and then subjected to fluxing treatment, hot-dip galvanized and cooled to obtain the galvanized steel core.

[0010] Preferably, the surface treatment includes sequential alkaline washing, a first water wash, acid washing, and a second water wash, wherein the alkaline washing solution is an aqueous sodium hydroxide solution, and the acid washing solution is an aqueous hydrochloric acid solution.

[0011] Preferably, the flux solution for the fluxing treatment comprises the following components by weight: 100-120 parts zinc chloride, 150-170 parts ammonium chloride, and 900-1000 parts water.

[0012] Preferably, the hot-dip galvanizing solution is liquid zinc, the hot-dip galvanizing temperature is 440~450℃, and the hot-dip galvanizing time is 30~90s.

[0013] Preferably, the cooling includes the following steps: after the steel wire is hot-dip galvanized, it is first cooled to 340~360℃ at a first cooling rate, then cooled to 180~200℃ at a second cooling rate, and finally cooled to room temperature at a third cooling rate; the first cooling rate > the second cooling rate > the third cooling rate.

[0014] Preferably, the first cooling rate is 18~20℃ / s, the second cooling rate is 8~10℃ / s, and the third cooling rate is 2~3℃ / s.

[0015] The present invention also proposes a method for preparing a high conductivity steel-cored aluminum stranded wire, comprising the following steps: stranding the aluminum wire onto the surface of the galvanized steel core to obtain the high conductivity steel-cored aluminum stranded wire.

[0016] The working principle and beneficial effects of this invention are as follows: In this invention, by limiting the content of Fe, Si, B, and La elements in the aluminum wire matrix and controlling (Fe+Si) / La=7.5~8, the synergistic effect of rare earth elements La and B is utilized to suppress the formation of high resistivity aluminum-iron and aluminum-silicon hard harmful phases, promote the transformation of impurity phases into small-sized dispersed phases with less negative impact on conductivity, reduce the scattering effect of impurity elements on free electrons in the aluminum matrix, lower the resistivity of the aluminum wire matrix, and effectively improve the overall conductivity of steel-cored aluminum stranded wire. Detailed Implementation

[0017] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0018] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will be described through embodiments.

[0019] A specific embodiment of the first aspect of the present invention provides a high conductivity steel-cored aluminum stranded wire, comprising a galvanized steel core and aluminum wire stranded on the surface of the galvanized steel core. The aluminum wire is composed of the following components by weight percentage: Fe 0.09%~0.10%, B 0.015%~0.045%, Si 0.03%~0.05%, La 0.015%~0.020%, with the balance being Al and unavoidable impurities, wherein the relationship (Fe+Si) / La = 7.5~8 is satisfied.

[0020] In this invention, Fe and Si are inherent impurity elements in industrial aluminum that are difficult to completely remove. They easily form coarse aluminum-iron and aluminum-silicon phases in the aluminum matrix, causing lattice distortion in the aluminum matrix, increasing the scattering of free electrons, and thus reducing the conductivity of the aluminum conductor. If the Fe and Si content is too high, it will directly cause the resistivity of the wire to increase and the transmission loss to increase. However, under actual industrial production conditions, it is difficult to reduce Fe and Si indefinitely, which would significantly increase the smelting and purification cost. In this solution, B and La are introduced. B can play a role in grain refinement and grain boundary purification, reducing impurity segregation at grain boundaries and reducing the scattering of electrons by grain boundaries. Rare earth La can interact with Fe and Si in the aluminum melt, modify the Fe and Si impurity phases, inhibit the formation of coarse high-resistivity intermetallic compounds, and promote the transformation of impurities into fine and dispersed composite phases, thereby reducing the deterioration effect of impurities on conductivity.

[0021] In this invention, the ratio (Fe+Si) / La is further defined as 7.5~8. When the ratio is greater than 8, it means that the total content of Fe and Si in the system is relatively excessive compared to La. La cannot fully dissolve the coarse and harmful impurity phases, and the effect of improving conductivity is not obvious. When the ratio is less than 7.5, La is relatively abundant. Excessive rare earth elements are prone to segregation in the aluminum matrix, precipitating new high-resistivity inclusion phases, which will cause a decrease in conductivity. At the same time, it will also reduce the plastic processing performance of aluminum wire, which is not conducive to subsequent drawing and stranding processes.

[0022] In one embodiment of the present invention, Fe / Si = 2~3.

[0023] In this invention, when Fe / Si = 2~3, the generation of high aspect ratio coarse and harmful phases such as needle-like and plate-like structures is suppressed. This can synergize with the effects of B and La, which is beneficial for La to fully combine with Fe and Si elements in the system, reduce the high-resistivity coarse phases remaining in the matrix, further reduce the scattering effect of impurities on free electrons, and consolidate the high conductivity of aluminum wire.

[0024] In one embodiment of the present invention, the method for preparing aluminum wire includes the following steps: distributing materials according to the target composition, melting, refining, casting, rolling, and drawing to obtain aluminum wire.

[0025] In one embodiment of the present invention, the method for preparing a galvanized steel core includes the following steps: the steel wire is surface treated and then subjected to fluxing treatment, hot-dip galvanized and cooled to obtain a galvanized steel core.

[0026] In one embodiment of the present invention, the surface treatment includes sequential alkaline washing, a first water washing, acid washing, and a second water washing, wherein the alkaline washing solution is an aqueous sodium hydroxide solution and the acid washing solution is an aqueous hydrochloric acid solution.

[0027] In this invention, the steel wire surface contains rolling oil stains, iron oxide scale, and rust layers. If the surface treatment is not thorough, it will cause defects such as poor adhesion of the subsequent galvanized layer, incomplete plating, and blistering and peeling of the plating layer, reducing the tensile strength of the galvanized steel core and affecting the overall service life of the steel-cored aluminum stranded wire. Alkali washing is used to remove rolling grease, lubricating oil, and other organic contaminants from the steel wire surface. The alkali washing uses an aqueous sodium hydroxide solution with a concentration of 8wt%~12wt%, preferably 10wt%. The alkali washing temperature is 50~65℃, preferably 60℃, and the alkali washing immersion time is 8~15min, preferably 12min. Slight stirring can be used during the alkali washing process to improve the degreasing effect. If the alkali washing temperature is too low or the time is too short, the degreasing will be incomplete. If the temperature is too high or the time is too long, the alkali solution will evaporate excessively, increasing the risk of over-corrosion of the steel wire surface. After alkaline washing, a water wash is performed, using room temperature water spray or immersion for 2-5 minutes, preferably 3 minutes. The purpose is to rinse off the residual alkaline solution adhering to the surface of the steel wire, prevent the alkaline solution from being carried into the pickling process, dilute and neutralize the pickling hydrochloric acid solution, and reduce the pickling efficiency.

[0028] In this invention, the pickling solution is an aqueous hydrochloric acid solution with a concentration of 15wt%~22wt%, preferably 20wt%. The pickling temperature is 20~35℃, preferably 25℃, and the pickling soaking time is 5~12 minutes, preferably 8 minutes. Pickling is used to remove iron oxide scale and rust oxide layer from the surface of the steel wire. If the hydrochloric acid concentration is too low or the soaking time is insufficient, the oxide scale will not be completely removed. If the concentration is too high or the soaking time is too long, it will easily cause over-corrosion of the steel wire substrate, resulting in pitting and corrosion on the surface of the steel wire, which will reduce the mechanical strength of the steel wire and generate excessive acid mist, which is not conducive to production operations. After pickling, a second water wash is performed using room temperature clean water for 2~4 minutes, preferably 3 minutes, to rinse away the residual acid and reactive salts adhering to the surface of the steel wire. If residual acid is carried into the subsequent fluxing process, it will damage the fluxing film and cause coating defects during hot-dip galvanizing.

[0029] In one embodiment of the present invention, the fluxing solution for the fluxing treatment comprises the following components in parts by weight: 100-120 parts zinc chloride, 150-170 parts ammonium chloride, and 900-1000 parts water.

[0030] In this invention, the fluxing agent is an aqueous solution of zinc chloride-ammonium chloride double salt fluxing agent, the fluxing temperature is 60~75℃, preferably 70℃, and the fluxing time is 1~3min, preferably 2min. After fluxing treatment, a uniform and complete fluxing salt film is formed on the surface of the steel wire, which isolates the air and prevents the steel wire from oxidizing again. At the same time, it enhances the wetting ability of the zinc liquid on the steel wire substrate and ensures uniform adhesion of the hot-dip galvanized coating.

[0031] In one embodiment of the present invention, the zinc plating solution for hot-dip galvanizing is zinc liquid, the hot-dip galvanizing temperature is 440~450℃, preferably 450℃, and the hot-dip galvanizing time is 30~90s, preferably 40s.

[0032] In one embodiment of the present invention, the cooling includes the following steps: after the steel wire is hot-dip galvanized, it is first cooled to 340~360°C at a first cooling rate, then cooled to 180~200°C at a second cooling rate, and finally cooled to room temperature at a third cooling rate; the first cooling rate > the second cooling rate > the third cooling rate.

[0033] In one embodiment of the present invention, the first cooling rate is 18~20℃ / s, the second cooling rate is 8~10℃ / s, and the third cooling rate is 2~3℃ / s.

[0034] In this invention, a segmented gradient cooling process is employed. After hot-dip galvanizing, the temperature is first rapidly cooled to 340-360°C at a first cooling rate of 18-20°C / s. This rapid cooling effectively inhibits the continuous interdiffusion between zinc and iron atoms, preventing brittle Zn. After the Fe alloy layer grows excessively, reducing the proportion of brittle phases, and reaching 340~360℃, the temperature is switched to a second cooling rate of 8~10℃ / s to cool down to 180~200℃. The cooling rate is appropriately slowed down to alleviate the thermal stress release rate between the coating and the steel wire substrate, avoid microcracks in the coating due to sudden temperature changes, ensure the uniform and dense structure of the zinc layer, and prevent cracking defects in the coating. When the temperature drops to 180~200℃, the cooling rate is further reduced to a third cooling rate of 2~3℃ / s to slowly cool down to room temperature, so that the steel wire substrate and the galvanized coating can complete thermal shrinkage simultaneously, gradually release residual internal stress, and reduce residual stress at the interface between the coating and the substrate.

[0035] In this invention, a gradient cooling mode with a first cooling rate > a second cooling rate > a third cooling rate is used to suppress the formation of excessively thick brittle alloy phases, while reducing microcracks inside the coating and residual stress at the interface, thereby improving the bonding strength between the galvanized layer and the steel wire substrate, and thus improving the strength of the steel-cored aluminum stranded wire.

[0036] A specific embodiment of the second aspect of the present invention provides a method for preparing a high conductivity steel-cored aluminum stranded wire, comprising the following steps: stranding aluminum wire onto the surface of a galvanized steel core to obtain a high conductivity steel-cored aluminum stranded wire.

[0037] Example 1 The aluminum wire is composed of the following components by weight percentage: Fe 0.09%, B 0.015%, Si 0.03%, La 0.015%, with the balance being Al and unavoidable impurities; A method for preparing a high-conductivity steel-cored aluminum stranded wire includes the following steps: S1. After dispensing according to the target composition, the aluminum wire is obtained through melting, refining, casting, rolling, and drawing. S2. The steel wire is first alkaline washed with a 10wt% sodium hydroxide aqueous solution at 60℃ for 12 minutes, then rinsed with room temperature water for 3 minutes, and then acid-washed with a 20wt% hydrochloric acid aqueous solution at 25℃ for 8 minutes. After acid washing, it is rinsed with room temperature water for 3 minutes. After the surface treatment is completed, a fluxing treatment is performed. The fluxing solution consists of the following raw materials by weight: 100 parts zinc chloride, 150 parts ammonium chloride, and 900 parts water. After immersion in the fluxing solution at 70℃ for 2 minutes, hot-dip galvanizing is performed. Hot-dip galvanizing is done in zinc liquid at 450℃ for 40 seconds. After cooling, a galvanized steel core is obtained. The cooling process includes the following steps: first, rapidly cooling to 340°C at a cooling rate of 18°C / s, then cooling to 180°C at a cooling rate of 8°C / s, and finally slowly cooling to room temperature at a cooling rate of 2°C / s. S3. Twist 26 aluminum wires in layers onto the surface of a galvanized steel core to obtain a high-conductivity steel-core aluminum stranded wire.

[0038] Example 2 The aluminum wire is composed of the following components by weight percentage: Fe 0.10%, B 0.03%, Si 0.04%, La 0.018%, with the balance being Al and unavoidable impurities; A method for preparing a high-conductivity steel-cored aluminum stranded wire includes the following steps: S1. After dispensing according to the target composition, the aluminum wire is obtained through melting, refining, casting, rolling, and drawing. S2. The steel wire is first alkaline washed with a 10wt% sodium hydroxide aqueous solution at 60℃ for 12 minutes, then rinsed with room temperature water for 3 minutes, and then acid-washed with a 20wt% hydrochloric acid aqueous solution at 25℃ for 8 minutes. After acid washing, it is rinsed with room temperature water for 3 minutes. After the surface treatment is completed, a fluxing treatment is performed. The fluxing solution consists of the following raw materials by weight: 110 parts zinc chloride, 160 parts ammonium chloride, and 950 parts water. After immersion in the fluxing solution at 70℃ for 2 minutes, hot-dip galvanizing is performed. Hot-dip galvanizing is done in zinc liquid at 450℃ for 40 seconds. After cooling, a galvanized steel core is obtained. The cooling process includes the following steps: first, rapidly cooling to 350°C at a cooling rate of 19°C / s, then cooling to 190°C at a cooling rate of 9°C / s, and finally slowly cooling to room temperature at a cooling rate of 3°C / s. S3. Twist 26 aluminum wires in layers onto the surface of a galvanized steel core to obtain a high-conductivity steel-core aluminum stranded wire.

[0039] Example 3 The aluminum wire is composed of the following components by weight percentage: Fe 0.10%, B 0.045%, Si 0.05%, La 0.020%, with the balance being Al and unavoidable impurities; A method for preparing a high-conductivity steel-cored aluminum stranded wire includes the following steps: S1. After dispensing according to the target composition, the aluminum wire is obtained through melting, refining, casting, rolling, and drawing. S2. The steel wire is first alkaline washed with a 10wt% sodium hydroxide aqueous solution at 60℃ for 12 minutes, then rinsed with room temperature water for 3 minutes, and then acid-washed with a 20wt% hydrochloric acid aqueous solution at 25℃ for 8 minutes. After acid washing, it is rinsed with room temperature water for 3 minutes. After the surface treatment is completed, a fluxing treatment is performed. The fluxing solution consists of the following raw materials by weight: 120 parts zinc chloride, 170 parts ammonium chloride, and 1000 parts water. After immersion in the fluxing solution at 70℃ for 2 minutes, hot-dip galvanizing is performed. Hot-dip galvanizing is done in zinc liquid at 450℃ for 40 seconds. After cooling, a galvanized steel core is obtained. The cooling process includes the following steps: first, rapidly cooling to 360°C at a cooling rate of 20°C / s, then cooling to 200°C at a cooling rate of 10°C / s, and finally slowly cooling to room temperature at a cooling rate of 3°C / s. S3. Twist 26 aluminum wires in layers onto the surface of a galvanized steel core to obtain a high-conductivity steel-core aluminum stranded wire.

[0040] Example 4 Compared with Example 2, Example 4 differs in that the aluminum wire is composed of the following components by weight percentage: Fe 0.10%, B 0.03%, Si 0.04%, La 0.0175%, with the balance being Al and unavoidable impurities.

[0041] Example 5 Compared with Example 2, Example 5 differs in that the aluminum wire is composed of the following components by weight percentage: Fe 0.10%, B 0.03%, Si 0.05%, La 0.02%, with the balance being Al and unavoidable impurities.

[0042] Example 6 Compared with Example 2, Example 6 differs in that the cooling includes the following steps: first, rapidly cooling to 350°C at a cooling rate of 15°C / s, then cooling to 190°C at a cooling rate of 5°C / s, and finally slowly cooling to room temperature at a cooling rate of 1°C / s.

[0043] Example 7 Compared with Example 2, Example 7 differs in that the cooling includes the following steps: first, rapidly cooling to 350°C at a cooling rate of 25°C / s, then cooling to 190°C at a cooling rate of 15°C / s, and finally slowly cooling to room temperature at a cooling rate of 5°C / s.

[0044] Example 8 Compared with Example 2, Example 8 differs in that the cooling includes the following steps: first, rapidly cooling to 350°C at a cooling rate of 19°C / s, then cooling to 190°C at a cooling rate of 3°C / s, and finally slowly cooling to room temperature at a cooling rate of 9°C / s.

[0045] Example 9 Compared with Example 2, Example 9 differs in that the cooling includes the following steps: first, rapidly cooling to 190°C at a cooling rate of 19°C / s, and finally slowly cooling to room temperature at a cooling rate of 3°C / s.

[0046] Example 10 Compared with Example 2, Example 10 differs in that the cooling includes the following steps: rapidly cooling to room temperature at a cooling rate of 19°C / s.

[0047] Comparative Example 1 Compared with Example 2, Comparative Example 1 differs in that the aluminum wire is composed of the following components by weight percentage: Fe 0.10%, B 0.03%, Si 0.04%, La 0.014%, with the balance being Al and unavoidable impurities.

[0048] Comparative Example 2 Compared with Example 2, Comparative Example 2 differs in that the aluminum wire is composed of the following components by weight percentage: Fe 0.10%, B 0.03%, Si 0.04%, La 0.022%, with the balance being Al and unavoidable impurities.

[0049] Experimental Example 1 The conductivity of the aluminum wires in the steel-cored aluminum stranded wires prepared in Examples 1-5 and Comparative Examples 1-2 was tested according to the test method specified in GB / T 12966-2022 "Eddy Current Test Method for Conductivity of Aluminum and Aluminum Alloys".

[0050] The test results are shown in Table 1: Table 1 Performance test results of Examples 1-5 and Comparative Examples 1-2

[0051] As shown in Table 1, when the aluminum wire composition in the steel-cored aluminum stranded wire satisfies the relationship (Fe+Si) / La=7.5~8, the conductivity of the aluminum wire can be improved.

[0052] Experiment Example 2 The high conductivity steel-cored aluminum stranded wires prepared in Examples 2 and 6-10 were tested for tensile strength according to the test methods specified in GB / T 228.1-2021 "Metallic materials - Tensile testing - Part 1: Test method at room temperature", wherein the separation speed of the tensile testing machine clamp was 50 mm / min.

[0053] The test results are shown in Table 2: Table 2 Performance test results of Examples 2 and 6-10

[0054] As shown in Table 2, when a gradient cooling method is adopted during the preparation of galvanized steel core, with the first cooling rate being 18~20℃ / s, the second cooling rate being 8~10℃ / s, and the third cooling rate being 2~3℃ / s, the strength of high conductivity steel core aluminum stranded wire can be improved.

[0055] 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 high conductivity steel-cored aluminum stranded wire, characterized in that, The device comprises a galvanized steel core and aluminum wire stranded on the surface of the galvanized steel core. The aluminum wire is composed of the following components by weight percentage: Fe 0.09%~0.10%, B 0.015%~0.045%, Si 0.03%~0.05%, La 0.015%~0.020%, with the balance being Al and unavoidable impurities, wherein the relationship (Fe+Si) / La = 7.5~8 is satisfied.

2. The high conductivity steel-cored aluminum stranded wire according to claim 1, characterized in that, The Fe / Si ratio is 2~3.

3. The high conductivity steel-cored aluminum stranded wire according to claim 1, characterized in that, The method for preparing the aluminum wire includes the following steps: distributing materials according to the target composition, melting, refining, casting, rolling, and drawing to obtain the aluminum wire.

4. The high conductivity steel-cored aluminum stranded wire according to claim 1, characterized in that, The method for preparing the galvanized steel core includes the following steps: the steel wire is surface treated and then subjected to fluxing treatment, hot-dip galvanized and cooled to obtain the galvanized steel core.

5. The high conductivity steel-cored aluminum stranded wire according to claim 4, characterized in that, The surface treatment includes sequential alkaline washing, a first water wash, acid washing, and a second water wash. The alkaline washing solution is an aqueous sodium hydroxide solution, and the acid washing solution is an aqueous hydrochloric acid solution.

6. The high conductivity steel-cored aluminum stranded wire according to claim 4, characterized in that, The fluxing solution for the fluxing treatment comprises the following raw materials in parts by weight: 100-120 parts zinc chloride, 150-170 parts ammonium chloride, and 900-1000 parts water.

7. A high conductivity steel-cored aluminum stranded wire according to claim 4, characterized in that, The hot-dip galvanizing solution is zinc liquid, the hot-dip galvanizing temperature is 440~450℃, and the hot-dip galvanizing time is 30~90s.

8. A high conductivity steel-cored aluminum stranded wire according to claim 4, characterized in that, The cooling process includes the following steps: after the steel wire is hot-dip galvanized, it is first cooled to 340~360℃ at a first cooling rate, then cooled to 180~200℃ at a second cooling rate, and finally cooled to room temperature at a third cooling rate; the first cooling rate > the second cooling rate > the third cooling rate.

9. A high conductivity steel-cored aluminum stranded wire according to claim 8, characterized in that, The first cooling rate is 18~20℃ / s, the second cooling rate is 8~10℃ / s, and the third cooling rate is 2~3℃ / s.

10. A method for preparing a high conductivity steel-cored aluminum stranded wire, used to prepare the high conductivity steel-cored aluminum stranded wire according to any one of claims 1 to 9, characterized in that, Includes the following steps: The aluminum wire is stranded onto the surface of the galvanized steel core to obtain the high conductivity steel core aluminum stranded wire.

Images