阅读说明：本技术 一种架空导线用高导电率耐腐蚀铝合金单丝及其制备方法 (High-conductivity corrosion-resistant aluminum alloy monofilament for overhead conductor and preparation method thereof ) 是由 徐鑫乾 刘建军 夏睿 杨立恒 徐铼 陈大兵 袁光宇 郭东亮 李鸿泽 高超 于 2021-07-19 设计创作，主要内容包括：本发明公开了一种架空导线用高导电率耐腐蚀铝合金单丝及其制备方法,按质量百分比计,包括如下组分：B：0.005%～0.03%,Mg：0.005%～0.10%,Sc：0.005%～0.05%,Gd：0.005%～0.05%,Si：≤0.07%,Fe：≤0.10%,(V+Ti+Cr+Mn)≤0.007%,余量为铝和不可避免的杂质。本发明采用纯度为99.85%的Al为原料,在通过添加适量B元素硼化处理对杂质元素进行严格净化控制的基础上,再添加微量Mg、Sc和Gd合金化元素,能够制得具有高导电率、耐腐蚀、低成本、输电损耗小的硬铝单丝,从而提高架空输电线路的电能输送效率和安全运行水平,减少输电线路损耗及运行维护成本。(The invention discloses a high-conductivity corrosion-resistant aluminum alloy monofilament for an overhead conductor and a preparation method thereof, wherein the high-conductivity corrosion-resistant aluminum alloy monofilament comprises the following components in percentage by mass: b: 0.005-0.03%, Mg: 0.005% -0.10%, Sc: 0.005-0.05%, Gd: 0.005% -0.05%, Si: less than or equal to 0.07 percent, Fe: less than or equal to 0.10 percent, (V + Ti + Cr + Mn) less than or equal to 0.007 percent, and the balance of aluminum and inevitable impurities. According to the invention, Al with the purity of 99.85% is used as a raw material, and trace Mg, Sc and Gd alloying elements are added on the basis of strictly purifying and controlling impurity elements by adding a proper amount of B element for boronization treatment, so that the duralumin monofilament with high conductivity, corrosion resistance, low cost and small power transmission loss can be prepared, the electric energy transmission efficiency and the safe operation level of the overhead power transmission line are improved, and the loss of the power transmission line and the operation and maintenance cost are reduced.)

1. The aluminum alloy monofilament is characterized by comprising the following components in percentage by mass: b: 0.005-0.03%, Mg: 0.005% -0.10%, Sc: 0.005-0.05%, Gd: 0.005% -0.05%, Si: less than or equal to 0.07 percent, Fe: less than or equal to 0.10 percent, (V + Ti + Cr + Mn) less than or equal to 0.007 percent, and the balance of aluminum and inevitable impurities.

2. The aluminum alloy monofilament as claimed in claim 1, wherein B: 0.01-0.03%, Mg: 0.02% -0.08%, Sc: 0.01-0.05%, Gd: 0.01 to 0.05 percent.

3. The aluminum alloy monofilament as claimed in claim 1, wherein the aluminum alloy monofilament comprises, in mass percent: b: 0.026%, Mg: 0.078%, Sc: 0.038%, Gd: 0.02%, Si: less than or equal to 0.062%, Fe: less than or equal to 0.09 percent, (V + Ti + Cr + Mn) less than or equal to 0.007 percent, and the balance of aluminum and inevitable impurities.

4. A method for producing an aluminum alloy monofilament as claimed in any one of claims 1 to 3, comprising:

selecting aluminum to be smelted, adding Al-B intermediate alloy after the aluminum is completely smelted, carrying out boronization treatment, standing, sequentially adding Al-Mg intermediate alloy, Al-Sc intermediate alloy and Al-Gd intermediate alloy to be smelted, and stirring and mixing after the intermediate alloy is completely smelted to prepare aluminum alloy liquid;

introducing purified gas into the aluminum alloy liquid, adding a covering agent for standing treatment, and removing slag and impurities to prepare an impurity-removed aluminum alloy liquid;

casting the impurity-removed aluminum alloy liquid into a mold to prepare an aluminum alloy ingot;

rolling the aluminum alloy ingot into an aluminum alloy round rod;

and drawing and deforming the aluminum alloy round rod for many times to obtain the aluminum alloy round monofilament.

5. The method for preparing the aluminum alloy monofilament as claimed in claim 4, wherein the Al-B intermediate alloy is formed by smelting and casting Al and B, and the mass content of B is 8%;

and/or the Al-Mg intermediate alloy is formed by smelting and casting Al and Mg, wherein the mass content of the Mg is 10%;

and/or the Al-Sc master alloy is formed by smelting and casting Al and Sc, wherein the mass content of Sc is 2%;

and/or the Al-Gd intermediate alloy is formed by smelting and casting Al and Gd, wherein the mass content of Gd is 2%.

6. The method for preparing the aluminum alloy monofilament as claimed in claim 4, wherein aluminum is selected for smelting, the smelting temperature is kept at 730 ℃ -750 ℃, and Al-B intermediate alloy is added at 740 ℃ -750 ℃ for boronization; and adding Al-Mg intermediate alloy, Al-Sc intermediate alloy and Al-Gd intermediate alloy in sequence at 740-750 ℃ for smelting.

7. The method for preparing aluminum alloy monofilament as claimed in claim 4, wherein the purge gas introduced into the aluminum alloy liquid is nitrogen, the flow rate of nitrogen is 20L/min to 30L/min, and the time of introduction is not less than 15 min.

8. The method for preparing the aluminum alloy monofilament according to claim 4, wherein the step of casting the impurity-removed aluminum alloy liquid into a mold to obtain an aluminum alloy ingot comprises the steps of: and casting the impurity-removed aluminum alloy liquid into a red copper material mould, and performing demoulding treatment at the temperature of less than or equal to 50 ℃.

9. The method for preparing the aluminum alloy monofilament as claimed in claim 4, wherein the aluminum alloy round bar is subjected to the drawing deformation treatment on the drawing machine at a speed of 13-15 m/s, the drawing deformation treatment temperature is 40-50 ℃, and the deformation amount is 10-15%.

10. The method for preparing the aluminum alloy monofilament as claimed in claim 4, wherein the covering agent is a rare earth flux and is prepared from the following raw materials in percentage by mass: NaF: NaCl: KCl: na (Na)₂SiF₆= 30%: 50%: 10%: 10 percent; and/or the addition amount of the covering agent is 0.02-0.04% of the aluminum alloy liquid.

Technical Field

The invention relates to a high-conductivity corrosion-resistant aluminum alloy monofilament for an overhead conductor and a preparation method thereof, and belongs to the technical field of overhead conductors of power transmission lines in the power industry.

Background

A novel power system taking new energy as a main body is constructed, a power-assisted double-carbon target is realized, the requirements of energy conservation, emission reduction, quality improvement and efficiency improvement of a power grid are more urgent, and a more energy-saving and economic power transmission technology is required to be developed to improve the transmission capacity of a power transmission line and reduce the power transmission loss. According to statistics, the national line loss rate is 5.62% in 2020, and the annual line loss electric quantity is 3.7 times of the annual electric quantity (1118 billion kilowatt hours) of the three gorges power station. By 2030, the total installed capacity of wind power and solar power generation in the national grid company's business district reaches more than 10 hundred million kilowatts, the installed capacity of water power reaches 2.8 hundred million kilowatts, and the installed capacity of nuclear power reaches 8000 ten thousand kilowatts. By 2025, the trans-provincial and trans-regional power transmission capacity of the national grid company's business district reaches 3.0 hundred million kilowatts, and the clean energy transmission capacity reaches 50%. With the large-scale network access of future clean energy, the existing line corridors and line facilities are fully utilized, so that the problems of transmitting electric quantity as much as possible, reducing line loss and improving transmission efficiency are the key concerns of the power grid industry.

Common Aluminum Conductor Steel Reinforced (ACSR) has been used internationally for more than one hundred years as a transmission conductor, and at present, the conductor for overhead transmission lines in China is mainly the common aluminum conductor steel reinforced, and the application percentage is about 80%. The common steel-cored aluminum strand relies on a hard aluminum wire on the outer layer of a steel core to transmit current, the conductivity of the hard aluminum wire is 61% IACS (20 ℃), the loss of a transmission line is relatively high, and when the steel-cored aluminum strand is used in heavy corrosion areas such as heavy industrial pollution areas and coastal areas, the corrosion resistance of the steel-cored aluminum strand is insufficient, so that great hidden dangers are brought to safe and reliable operation. If the conductivity of the duralumin monofilament can be further improved on the premise of ensuring the strength, and the corrosion resistance of the duralumin monofilament is synchronously improved, the loss of the power transmission line can be effectively reduced, the energy conservation of the power transmission line and the reduction of the operation cost of the line are realized, and the safe and reliable operation level of the overhead power transmission line in a corrosive environment is improved. The theoretical conductivity of high-purity aluminum (99.99% Al) can reach 64.94% IACS, but the high-purity aluminum has low tensile strength and surface hardness, the tensile strength is lower than 100 MPa, the high-purity aluminum has low capacity of resisting corrosive media such as chloride ions, acid rain and the like, and the high-purity aluminum cannot be used in environments with strong corrosivity such as coastal environments, saline-alkali environments, industrial atmosphere and the like.

At present, the electric conductivity of the duralumin monofilaments in international standards is unified to 61% IACS, and the electric conductivity of the duralumin monofilaments is divided into 4 grades according to the current national standard GB/T17048 and 2017 "duralumin wires for overhead stranded wires", wherein the electric conductivity of the duralumin monofilaments is 61% IACS, 61.5% IACS, 62% IACS and 62.5% IACS respectively. The preparation technology of 63% IACS high-conductivity duralumin monofilament is immature at home and abroad, high-cost 99.9% high-purity aluminum is mainly adopted as a raw material and is prepared by strict production process control, the product percent of pass is relatively low, the total manufacturing cost of the conductor is 20% -30% higher than that of the existing common steel-cored aluminum strand, and the technical development and large-scale popularization and application of the high-conductivity duralumin conductor are severely restricted. Therefore, the research and development and the application of the duralumin monofilaments with high conductivity, corrosion resistance and low cost have important significance for upgrading and transforming the power grid in China, improving the electric energy transmission efficiency and the safe operation level of the overhead transmission line, and reducing the loss of the transmission line and the operation and maintenance cost.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, provides a high-conductivity corrosion-resistant aluminum alloy monofilament for an overhead conductor and a preparation method thereof, and solves the technical problems of low conductivity, large transmission loss and poor corrosion resistance of an existing 61% IACS steel-cored aluminum strand.

In order to achieve the purpose, the invention is realized by adopting the following technical scheme:

on one hand, the invention provides an aluminum alloy monofilament, which comprises the following components in percentage by mass: b: 0.005-0.03%, Mg: 0.005% -0.10%, Sc: 0.005-0.05%, Gd: 0.005% -0.05%, Si: less than or equal to 0.07 percent, Fe: less than or equal to 0.10 percent, (V + Ti + Cr + Mn) less than or equal to 0.007 percent, and the balance of aluminum and inevitable impurities.

Preferably, B: 0.01-0.03%, Mg: 0.02% -0.08%, Sc: 0.01-0.05%, Gd: 0.01 to 0.05 percent.

Preferably, the components by mass percentage are as follows: b: 0.026%, Mg: 0.078%, Sc: 0.038%, Gd: 0.02%, Si: less than or equal to 0.062%, Fe: less than or equal to 0.09 percent, (V + Ti + Cr + Mn) less than or equal to 0.007 percent, and the balance of aluminum and inevitable impurities.

On the other hand, the invention provides a preparation method of the aluminum alloy monofilament, which comprises the following steps:

selecting aluminum to be smelted, adding Al-B intermediate alloy after the aluminum is completely smelted, carrying out boronization treatment, standing, sequentially adding Al-Mg intermediate alloy, Al-Sc intermediate alloy and Al-Gd intermediate alloy to be smelted, and stirring and mixing after the intermediate alloy is completely smelted to prepare aluminum alloy liquid;

introducing purified gas into the aluminum alloy liquid, adding a covering agent for standing treatment, and removing slag and impurities to prepare an impurity-removed aluminum alloy liquid;

casting the impurity-removed aluminum alloy liquid into a mold to prepare an aluminum alloy ingot;

rolling the aluminum alloy ingot into an aluminum alloy round rod;

and drawing and deforming the aluminum alloy round rod for many times to obtain the aluminum alloy round monofilament.

Preferably, the Al-B intermediate alloy is formed by smelting and casting Al and B, and the mass content of B is 8%;

and/or the Al-Mg intermediate alloy is formed by smelting and casting Al and Mg, wherein the mass content of the Mg is 10%;

and/or the Al-Sc master alloy is formed by smelting and casting Al and Sc, wherein the mass content of Sc is 2%;

and/or the Al-Gd intermediate alloy is formed by smelting and casting Al and Gd, wherein the mass content of Gd is 2%.

Preferably, aluminum is selected for smelting, the smelting temperature is kept at 730-750 ℃, and Al-B intermediate alloy is added at 740-750 ℃ for boronization; and adding Al-Mg intermediate alloy, Al-Sc intermediate alloy and Al-Gd intermediate alloy in sequence at 740-750 ℃ for smelting. The aluminum raw material of the application adopts industrial pure aluminum with low cost and 99.85% of Al purity.

Preferably, the purge gas introduced into the aluminum alloy liquid is nitrogen, the flow rate of the nitrogen is 20L/min to 30L/min, and the time of introducing the nitrogen is not less than 15 min.

Preferably, the method of casting the impurity-removed aluminum alloy liquid into a mold to produce an aluminum alloy ingot includes: and casting the impurity-removed aluminum alloy liquid into a red copper material mould, and performing demoulding treatment at the temperature of less than or equal to 50 ℃.

Preferably, in the drawing deformation treatment process, a drawing die with a nano diamond composite coating is adopted to draw the aluminum alloy round rod for 10 times so as to prepare the aluminum alloy round monofilament.

Preferably, the aluminum alloy round rod is subjected to drawing deformation treatment on a wire drawing machine at the speed of 13-15 m/s, wherein the drawing deformation treatment temperature is 40-50 ℃, and the deformation amount is 10-15%.

Preferably, the covering agent is a rare earth flux and is prepared from the following raw materials in percentage by mass: NaF: NaCl: KCl: na (Na)₂SiF₆= 30%: 50%: 10%: 10 percent; further, the adding amount of the covering agent is 0.02-0.04% of the aluminum alloy liquid.

Compared with the prior art, the invention has the following beneficial effects:

1. the invention provides an aluminum alloy monofilament which comprises the following components in percentage by mass: b: 0.005-0.03%, Mg: 0.005% -0.10%, Sc: 0.005-0.05%, Gd: 0.005% -0.05%, Si: less than or equal to 0.07 percent, Fe: less than or equal to 0.10 percent, (V + Ti + Cr + Mn) less than or equal to 0.007 percent, and the balance of aluminum and inevitable other trace impurity elements. By adding a proper amount of B, Mg, Sc and Gd alloying elements into 99.85 percent of industrial pure aluminum, the duralumin monofilament with high conductivity, corrosion resistance and low cost can be prepared, the electric energy transmission efficiency and the safe operation level of the overhead transmission line can be improved, and the loss of the transmission line and the operation and maintenance cost are reduced.

2. The invention provides a preparation method of an aluminum alloy monofilament, which comprises the following steps: selecting an aluminum ingot to be smelted, adding an Al-B intermediate alloy, carrying out boronization treatment, sequentially adding an Al-Mg intermediate alloy, an Al-Sc intermediate alloy and an Al-Gd intermediate alloy, smelting, and stirring and mixing after the intermediate alloy is completely melted to prepare an aluminum alloy liquid; introducing purified gas into the aluminum alloy liquid, adding a covering agent for standing treatment, and removing slag and impurities to prepare an impurity-removed aluminum alloy liquid; and casting the aluminum alloy liquid without impurities into a mould to obtain the aluminum alloy ingot. Rolling the aluminum alloy ingot into an aluminum alloy round rod; the duralumin monofilament material prepared by the method does not need subsequent heat treatment, the preparation process of the duralumin monofilament material with high conductivity is simplified, simultaneously, industrial pure aluminum with low cost and 99.85% of Al purity is adopted as a raw material, and the manufacturing cost is reduced, so that the duralumin monofilament material for the overhead conductor prepared by the method has excellent comprehensive performance, the conductivity is more than or equal to 63.0% IACS (20 ℃), the tensile strength is more than or equal to 175 MPa, the elongation is more than or equal to 2.0%, the corrosion resistance is 2 times that of the existing conventional duralumin monofilament, and the duralumin conductor with the conductivity can be popularized and applied in a large scale.

3. The preparation method provided by the invention is characterized in that industrial pure aluminum with the purity of 99.85 percent of Al is used as a raw material, and trace Mg, Sc and Gd alloying elements are added on the basis of strictly purifying and controlling impurity elements by adding a proper amount of B element for boronizing treatment. Solid solution of Mg element and second phase Mg₂The formation of Si intermetallic compound is helpful for improving the corrosion resistance of the hard aluminum alloy(ii) a The Gd element can form a dispersed phase to block dislocation and grain boundary movement, improve the recrystallization resistance of the alloy, ensure that more fine subgrain tissues are reserved in a matrix, and contribute to improving the corrosion resistance of the hard aluminum alloy; the addition of Sc element can reduce the impurity content, and has the functions of grain refinement and crystallization temperature increase, so that the hard aluminum alloy has high conductivity and good mechanical properties.

4. The invention adopts the blowing of high-purity N in the smelting process₂The invention adopts the diamond wire drawing die to draw the duralumin alloy round rod with the phi of 9.5mm for 10 times, because the diamond die has better finish, temperature resistance and wear resistance than the duralumin alloy die, and simultaneously, the duralumin monofilament prepared by drawing has good electric conduction, mechanics and corrosion resistance by optimally controlling the wire drawing speed, the wire drawing temperature and the deformation.

Detailed Description

The present invention will be further described below. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby. All embodiments employ industrially well-established smelting, rolling and wire drawing equipment.

Example 1

An aluminum alloy monofilament material comprises the following components in percentage by mass:

B 0.020%

Mg 0.056%

Sc 0.025%

Gd 0.050%

Cr+Mn+V+Ti 0.007%

Fe 0.010%

Si 0.070%

al and the balance of inevitable impurities.

The preparation method comprises the following steps:

step 1, selecting industrial pure aluminum with the purity of 99.85 percent, adding various alloy elements into the industrial pure aluminum to enable the final content of the alloy elements to be as shown above, adding the alloy elements into a frequency induction furnace in the form of Al-B, Al-Mg, Al-Sc and Al-Gd intermediate alloys for smelting, keeping the smelting temperature at 730 ℃, adding the Al-B intermediate alloys into the furnace at 740 ℃ after aluminum ingots are completely molten, and carrying out boronization treatment; and (3) after standing for not less than 30min, sequentially adding Al-Mg intermediate alloy, Al-Sc intermediate alloy and Al-Gd intermediate alloy at 740 ℃, and after the intermediate alloy is completely melted, electromagnetically stirring the aluminum alloy liquid for 15min each time and 3 times every 10min to prepare the aluminum alloy solution.

And 2, controlling the temperature of the aluminum alloy solution within the range of 740 ℃, introducing 15min of high-purity nitrogen (99.99%), controlling the flow of the nitrogen introduced into the aluminum alloy solution to be 20L/min, adding a covering agent accounting for 0.02% of the total amount of the aluminum alloy solution, standing for 15min, and removing slag and impurities to prepare the impurity-removed aluminum alloy solution.

And 3, casting the impurity-removed aluminum alloy solution into a red copper mold at 720 ℃, and demolding at 42 +/-2 ℃ to prepare an aluminum alloy ingot with the size of 30mm multiplied by 450 mm.

And 4, keeping the temperature of 490 ℃ for 1.5h, and then rolling the aluminum alloy ingot on a three-roller rolling mill to form a hard aluminum alloy round rod with the diameter of 9.5 mm.

And 5, drawing the hard aluminum alloy round rod with the diameter of 9.5mm on a drawing machine at the speed of 13m/s, controlling the drawing temperature at 40 ℃ and the deformation at 15%, wherein the drawing die is a drawing die with a nano diamond composite coating, and drawing for 10 times by adopting the diamond drawing die to finally prepare the aluminum alloy round monofilament with the diameter of 3.05 mm.

Through detection, the conductivity of the duralumin monofilament prepared by the method is 63.18% IACS, the tensile strength is 175.2MPa, the elongation is 2.10%, and the corrosion resistance is 2.2 times that of the conventional duralumin monofilament in service.

Example 2

An aluminum alloy monofilament material comprises the following components in percentage by mass:

B 0.023%

Mg 0.065%

Sc 0.032%

Gd 0.036%

Cr+Mn+V+Ti 0.007%

Fe 0.095%

Si 0.068%

al and the balance of inevitable impurities.

The preparation method comprises the following steps:

step 1, selecting industrial pure aluminum with the purity of 99.85 percent, adding various alloy elements into the industrial pure aluminum, and enabling the final content of the alloy elements to be as shown above, wherein the alloy elements are added in a mode of Al-B, Al-Mg, Al-Sc and Al-Gd intermediate alloys and placed in a frequency induction furnace for smelting, the smelting temperature is kept at 740 ℃, and after an aluminum ingot is completely molten, adding Al-B intermediate alloys into the aluminum ingot at 745 ℃ for boronization; and (3) after standing for not less than 30min, sequentially adding Al-Mg intermediate alloy, Al-Sc intermediate alloy and Al-Gd intermediate alloy at 740 ℃, and after the intermediate alloy is completely melted, electromagnetically stirring the aluminum alloy liquid for 20min each time and once every 15min for 3 times to prepare the aluminum alloy solution.

And 2, controlling the temperature of the aluminum alloy solution within the range of 730 ℃, introducing 15min of high-purity nitrogen (99.99%), controlling the flow of the nitrogen introduced into the aluminum alloy solution to be 25L/min, adding a covering agent accounting for 0.025% of the total amount of the aluminum alloy solution, standing for 15min, and removing slag and impurities to obtain the impurity-removed aluminum alloy solution.

And 3, casting the impurity-removed aluminum alloy solution into a red copper mold at 730 ℃, and demolding at 45 +/-2 ℃ to prepare an aluminum alloy ingot with the size of 30mm multiplied by 450 mm.

And 4, rolling the aluminum alloy ingot into a hard aluminum alloy round rod with the diameter of 9.5mm on a three-roller rolling mill after the aluminum alloy ingot is kept at the temperature of 500 ℃ for 1.5 h.

And 5, drawing the hard aluminum alloy round rod with the diameter of 9.5mm on a drawing machine at the speed of 15 m/s, controlling the drawing temperature at 40 ℃ and the deformation at 10 percent, wherein the drawing die is a drawing die with a nano diamond composite coating, and drawing for 10 times by adopting the diamond drawing die to finally prepare the aluminum alloy round monofilament with the diameter of 3.05 mm.

Through detection, the conductivity of the duralumin monofilament prepared by the method is 63.25% IACS, the tensile strength is 176.3MPa, the elongation is 2.08%, and the corrosion resistance is 2.3 times that of the conventional duralumin monofilament in service.

Example 3

An aluminum alloy monofilament material comprises the following components in percentage by mass:

B 0.026%

Mg 0.078%

Sc 0.038%

Gd 0.020%

Cr+Mn+V+Ti 0.006%

Fe 0.009%

Si 0.062%

al and the balance of inevitable impurities.

The preparation method comprises the following steps:

step 1, selecting industrial pure aluminum with the purity of 99.85 percent, adding various alloy elements into the industrial pure aluminum, and enabling the final content of the alloy elements to be as shown above, wherein the alloy elements are added in a mode of Al-B, Al-Mg, Al-Sc and Al-Gd intermediate alloys and placed in a frequency induction furnace for smelting, the smelting temperature is kept at 740 ℃, and after an aluminum ingot is completely molten, adding Al-B intermediate alloys into the aluminum ingot at 750 ℃ for boronization; and (3) after standing for not less than 30min, sequentially adding Al-Mg intermediate alloy, Al-Sc intermediate alloy and Al-Gd intermediate alloy at 740 ℃, and after the intermediate alloy is completely melted, electromagnetically stirring the aluminum alloy liquid for 20min every time and for 3 times every 10min to prepare the aluminum alloy solution.

And 2, controlling the temperature of the aluminum alloy solution within the range of 740 ℃, introducing 20min of high-purity nitrogen (99.99%), controlling the flow of the nitrogen introduced into the aluminum alloy solution to be 25L/min, adding a covering agent accounting for 0.030% of the total amount of the aluminum alloy solution, standing for 15min, and removing slag and impurities to obtain the impurity-removed aluminum alloy solution.

And 3, casting the impurity-removed aluminum alloy solution into a red copper mold at 730 ℃, and demolding at 45 +/-2 ℃ to prepare an aluminum alloy ingot with the size of 30mm multiplied by 450 mm.

And 4, rolling the aluminum alloy ingot into a hard aluminum alloy round rod with the diameter of 9.5mm on a three-roller rolling mill after the aluminum alloy ingot is kept at the temperature of 500 ℃ for 1.5 h.

And 5, drawing the hard aluminum alloy round rod with the diameter of 9.5mm on a drawing machine at the speed of 13m/s, controlling the drawing temperature at 45 ℃ and the deformation at 12%, wherein the drawing die is a drawing die with a nano diamond composite coating, and drawing for 10 times by adopting the diamond drawing die to finally prepare the aluminum alloy round monofilament with the diameter of 3.05 mm.

Through detection, the conductivity of the duralumin monofilament prepared by the method is 63.51 percent IACS, the tensile strength is 177.2MPa, the elongation is 2.07 percent, and the corrosion resistance is 2.5 times that of the conventional duralumin monofilament in service.

Example 4

An aluminum alloy monofilament material comprises the following components in percentage by mass:

B 0.028%

Mg 0.073%

Sc 0.042%

Gd 0.020%

Cr+Mn+V+Ti 0.007%

Fe 0.088%

Si 0.060%

al and the balance of inevitable impurities.

The preparation method comprises the following steps:

step 1, selecting industrial pure aluminum with the purity of 99.85 percent, adding various alloy elements into the industrial pure aluminum, and enabling the final content of the alloy elements to be as shown above, wherein the alloy elements are added in a mode of Al-B, Al-Mg, Al-Sc and Al-Gd intermediate alloys and placed in a frequency induction furnace for smelting, the smelting temperature is kept at 740 ℃, and after an aluminum ingot is completely molten, adding Al-B intermediate alloys into the aluminum ingot at 750 ℃ for boronization; and (3) after standing for not less than 30min, sequentially adding Al-Mg intermediate alloy, Al-Sc intermediate alloy and Al-Gd intermediate alloy at 740 ℃, and after the intermediate alloy is completely melted, electromagnetically stirring the aluminum alloy liquid for 20min every time and for 3 times every 10min to prepare the aluminum alloy solution.

And 2, controlling the temperature of the aluminum alloy solution within the range of 740 ℃, introducing 20min of high-purity nitrogen (99.99%), controlling the flow of the nitrogen introduced into the aluminum alloy solution to be 25L/min, adding a covering agent with the addition amount of about 0.040% of the total amount of the aluminum alloy solution, standing for 10min, and removing slag and impurities to obtain the impurity-removed aluminum alloy solution.

And 3, casting the impurity-removed aluminum alloy solution into a red copper mold at 720 ℃, and demolding at 42 +/-2 ℃ to prepare an aluminum alloy ingot with the size of 30mm multiplied by 450 mm.

And 4, keeping the temperature of the aluminum alloy ingot at 495 ℃ for 1.5h, and then rolling the aluminum alloy ingot on a three-roller rolling mill to form a hard aluminum alloy round rod with the diameter of 9.5 mm.

And 5, drawing the hard aluminum alloy round rod with the diameter of 9.5mm on a drawing machine at the speed of 15 m/s, controlling the drawing temperature at 40 ℃ and the deformation at 15%, wherein the drawing die is a drawing die with a nano diamond composite coating, and drawing for 10 times by adopting the diamond drawing die to finally prepare the aluminum alloy round monofilament with the diameter of 3.05 mm.

Through detection, the conductivity of the duralumin monofilament prepared by the method is 63.36 percent IACS, the tensile strength is 176.1MPa, the elongation is 2.09 percent, and the corrosion resistance is 2.4 times that of the conventional duralumin monofilament in service.

Example 5

An aluminum alloy monofilament material comprises the following components in percentage by mass:

B 0.030%

Mg 0.080%

Sc 0.050%

Gd 0.010%

Cr+Mn+V+Ti 0.006%

Fe 0.086%

Si 0.059%

al and the balance of inevitable impurities.

The preparation method comprises the following steps:

step 1, selecting an industrial pure aluminum ingot with the purity of 99.85 percent Al, adding alloy elements into the ingot to enable the final content of the alloy elements to be as shown above, adding the alloy elements into a frequency induction furnace in the form of Al-B, Al-Mg, Al-Sc and Al-Gd intermediate alloys for smelting, keeping the smelting temperature at 750 ℃, adding Al-B intermediate alloys into the ingot at 740 ℃ after the aluminum ingot is completely molten, and carrying out boronization treatment; and (3) after standing for not less than 30min, sequentially adding Al-Mg intermediate alloy, Al-Sc intermediate alloy and Al-Gd intermediate alloy at 740 ℃, and after the intermediate alloy is completely melted, electromagnetically stirring the aluminum alloy liquid for 15min each time and once every 15min for 3 times to prepare the aluminum alloy solution.

And 2, controlling the temperature of the aluminum alloy solution within the range of 740 ℃, introducing 15min of high-purity nitrogen (99.99%), controlling the flow of the nitrogen introduced into the aluminum alloy solution to be 30L/min, adding a covering agent accounting for 0.030% of the total amount of the aluminum alloy solution, standing for 15min, and removing slag and impurities to prepare the impurity-removed aluminum alloy solution.

And 3, casting the impurity-removed aluminum alloy solution into a red copper mold at 730 ℃, and demolding at 45 +/-2 ℃ to prepare an aluminum alloy ingot with the size of 30mm multiplied by 450 mm.

And 4, rolling the aluminum alloy ingot into a hard aluminum alloy round rod with the diameter of 9.5mm on a three-roller rolling mill after the aluminum alloy ingot is kept at the temperature of 500 ℃ for 1.5 h.

And 5, drawing the hard aluminum alloy round rod with the diameter of 9.5mm on a drawing machine at the speed of 15 m/s, controlling the drawing temperature at 40 ℃ and the deformation at 14 percent, wherein the drawing die is a drawing die with a nano diamond composite coating, and drawing for 10 times by adopting a diamond drawing die to finally prepare the aluminum alloy round monofilament with the diameter of 3.05 mm.

Through detection, the conductivity of the duralumin monofilament prepared by the method is 63.28% IACS, the tensile strength is 175.8MPa, the elongation is 2.12%, and the corrosion resistance is 2.1 times that of the conventional duralumin monofilament in service.

The action and mechanism of each alloy element adopted by the invention are as follows:

sc (scandium): sc can obviously improve the strength of the aluminum alloy, reduce dendritic segregation of the aluminum alloy and refine the grain structure of the aluminum alloy. Sc element can form primary Al in melt₃Sc particles can be used as heterogeneous nucleation cores during crystallization nucleation, so that the grain structure is obviously refined; sc can also react with partial impurity elements in the aluminum alloy to convert the impurity elements from an atomic state to a precipitation state, so that the conductivity of the aluminum alloy is improved.

Gd (gadolinium): the proper amount of Gd element is added into the aluminum alloy, so that dispersed phases can be formed to strongly hinder dislocation and grain boundary movement, the recrystallization resistance of the alloy is improved, and more fine subgrain structures are reserved on a matrix. Compared with a large-angle crystal boundary, the corrosion potential difference between the sub-crystal boundary and the crystal interior is smaller, the corrosion driving force is weakened, and the corrosion resistance of the aluminum alloy is favorably improved.

Mg (magnesium): a proper amount of Mg alloying elements are added into the aluminum alloy, and a part of Mg elements are dissolved in the matrix in a solid solution manner, so that the electrode potential of the matrix can be improved, and the corrosion resistance of the aluminum alloy is improved; another part of Mg forms an intermetallic compound Mg in the aluminum alloy₂Si，Mg₂Si has a lower electrode potential than pure aluminum, so in corrosive environments, Mg₂Si is typically etched first, while the aluminum matrix is etched later. Therefore, the optimal control of the Mg content can lead to better corrosion resistance of the aluminum alloy, but when the Mg content is excessively added, the conductivity of the aluminum alloy is reduced.

B (boron): if the impurity elements in the aluminum alloy exist in a solid solution state, the conductivity can be reduced, and the boron element is used for carrying out boronization treatment, so that the impurity content can be effectively reduced, namely after a certain amount of B element is added in the smelting of an electrical pure aluminum material, the B element can react with the impurity elements of transition group elements such as Cr, Mn, V, Ti and the like, and the B element is converted from the solid solution state to the compound state and is deposited at the bottom of a melt, so that an aluminum conductor is purified, and the conductivity of the aluminum alloy is improved.

Cr (chromium), Mn (manganese), V (vanadium), Ti (titanium): the four elements are all impurity elements in electrician pure aluminum. When Cr, Mn, V and Ti impurity elements in the aluminum material exist in a solid solution state, free electrons in the material are easily absorbed to fill incomplete electron layers of the impurity elements, and the reduction of the number of the free electrons playing a role in electric conduction can cause the increase of the resistivity of the aluminum material. Research shows that 1 percent (Cr + Mn + V + Ti) of impurity elements has 5 times of the harmful effect on the conductivity of the aluminum conductor compared with 1 percent of Si. Therefore, the strict control of the contents of Cr, Mn, V and Ti impurity elements has an important effect on ensuring the conductivity of the aluminum conductor.

The composition table of the produced duralumin alloys obtained in examples 1 to 5 is shown in table 1. Specifically, the aluminum alloy monofilament comprises the following components in percentage by mass: b: 0.005-0.03%, Mg: 0.005% -0.10%, Sc: 0.005-0.05%, Gd: 0.005% -0.05%, Si: less than or equal to 0.07 percent, Fe: less than or equal to 0.10 percent, (V + Ti + Cr + Mn) less than or equal to 0.007 percent, and the balance of aluminum and inevitable other trace impurity elements.

TABLE 1 composition table (wt%) of the duralumin alloy prepared in example

Tests on the diameter, conductivity, tensile strength, elongation and corrosion resistance of the duralumin alloy monofilaments prepared in examples 1 to 5 and the common duralumin monofilaments of the comparative examples were carried out.

The diameter test of the invention adopts a numerical display outside micrometer with the model number of 0-25;

the conductivity test of the invention adopts a TEGAM1750 micro-ohm meter;

the tensile strength of the invention is determined by adopting an MTS 810.25 model electrohydraulic servo material tester;

the elongation rate of the invention adopts an electro-hydraulic servo material testing machine with the model number of MTS 810.25;

the corrosion resistance of the invention adopts a salt fog box with a model number of CCT10, and the adopted test method is GB/T10125-2012 salt fog test for artificial atmosphere corrosion test.

The results of the tests on the diameter, conductivity, tensile strength, elongation, and corrosion resistance of the duralumin alloys prepared in examples 1 to 5 and comparative example and the ordinary duralumin monofilament prepared in comparative example are shown in table 2.

Table 2 performance test results of duralumin monofilament material prepared in example and conventional duralumin monofilament

As can be seen from Table 2, the high-conductivity corrosion-resistant aluminum alloy monofilament material prepared by the method has obvious advantages in comprehensive performance, and researches show that the high-conductivity corrosion-resistant aluminum alloy monofilament material is prepared by adding the high-conductivity corrosion-resistant aluminum alloy monofilament material into an industrial pure aluminum ingot by mass percent (0.005-0.03%): (0.005% -0.10%): (. 005-0.05%): compared with the existing common duralumin monofilament, the aluminum alloy monofilament prepared from (0.005-0.05) B, Mg, Sc and Gd has obviously improved conductivity, tensile strength, elongation and corrosion resistance, specifically, at room temperature (20 ℃), the aluminum alloy monofilament prepared by the method has the conductivity of more than or equal to 63.0% IACS (20 ℃), the tensile strength of more than or equal to 175 MPa, the elongation of more than or equal to 2.0%, and the corrosion resistance of more than 2.0 times that of the conventional duralumin monofilament, and multiple groups of experimental data show that the high-conductivity corrosion-resistant aluminum alloy monofilament material prepared by the method has higher stability. Meanwhile, the drawing speed, the drawing temperature and the deformation are optimally controlled, so that the hard aluminum monofilament obtained by drawing has good conductivity, mechanics and corrosion resistance. Therefore, by adding a proper amount of B, Mg, Sc and Gd alloying elements into the industrial pure aluminum ingot, the duralumin monofilament with high conductivity, corrosion resistance and low cost can be prepared, the electric energy transmission efficiency and the safe operation level of the overhead transmission line can be improved, and the loss of the transmission line and the operation and maintenance cost are reduced.

In conclusion, the invention provides the high-conductivity corrosion-resistant aluminum alloy monofilament for the overhead conductor and the preparation method thereof, the subsequent heat treatment is not needed, the preparation process of the high-conductivity duralumin monofilament material is simplified, meanwhile, the low-cost 99.85% Al pure industrial pure aluminum is adopted as the raw material, and the manufacturing cost is reduced, so that the prepared duralumin monofilament material for the overhead conductor has excellent comprehensive performance, the conductivity is more than or equal to 63.0% IACS (20 ℃), the tensile strength is more than or equal to 175 MPa, the elongation is more than or equal to 2.0%, the corrosion resistance is 2 times that of the existing conventional duralumin monofilament, and the high-conductivity duralumin conductor can be popularized and applied in a large scale.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.