CN113637875B - High-conductivity corrosion-resistant aluminum alloy monofilament for overhead conductor and preparation method thereof - Google Patents
High-conductivity corrosion-resistant aluminum alloy monofilament for overhead conductor and preparation method thereof Download PDFInfo
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C1/02—Making non-ferrous alloys by melting
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/02—Making non-ferrous alloys by melting
- C22C1/03—Making non-ferrous alloys by melting using master alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
Abstract
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, less than or equal to 0.007 percent of (V+Ti+Cr+Mn), and the balance of aluminum and unavoidable impurities. According to the invention, al with purity of 99.85% is adopted 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 boride treatment, so that the duralumin monofilament with high conductivity, corrosion resistance, low cost and small power transmission loss can be prepared, the power transmission efficiency and safe operation level of an overhead power transmission line are improved, and the power transmission line loss and operation and maintenance cost are reduced.
Description
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 transmission lines in the power industry.
Background
The novel power system taking new energy as a main body is constructed, the power-assisted double-carbon target is realized, the requirements of energy conservation, emission reduction, quality improvement and synergy of the power grid are urgent, and the development of a more energy-saving and economical power transmission technology is required to improve the transmission capacity of a power transmission line and reduce the power transmission loss. The annual line loss rate in 2020 was found to be 5.62%, with annual line loss power equivalent to 3.7 times annual power production (1118 million kwh) of a three gorges utility. By 2030, the total installed capacity of wind power and solar power generation of a national grid company through a barrage reaches more than 10 hundred million kilowatts, the installed capacity of the water-electricity installation reaches 2.8 hundred million kilowatts, and the installed capacity of the nuclear power installation reaches 8000 ten thousand kilowatts. By 2025, the power transmission capacity of the national network company is up to 3.0 hundred million kilowatts across the provinces and the clean energy transmission rate is up to 50%. With the large-scale network access of clean energy in the future, the method fully utilizes the existing line corridor and line facilities, and is a major concern in the power grid industry, namely, delivering as much electricity as possible, reducing line loss and improving power transmission efficiency.
The common steel-cored aluminum strand (ACSR) is used internationally for over a hundred years as a transmission wire, and at present, the wire for overhead transmission lines in China is mainly the common steel-cored aluminum strand, and the application ratio is about 80%. The common steel-cored aluminum strand transmits current by means of hard aluminum wires on the outer layer of the steel core, the conductivity of the hard aluminum wires is 61% IACS (20 ℃), the power transmission line loss is relatively high, and when the common steel-cored aluminum strand is used in heavy-industrial pollution areas, coastal areas and other heavy-corrosion areas, the corrosion resistance is insufficient, so that great hidden trouble is brought to safe and reliable operation. If the conductivity of the duralumin monofilament can be further improved on the premise of ensuring the strength, the corrosion resistance of the duralumin monofilament can be synchronously improved, the loss of the power transmission line can be effectively reduced, the energy conservation of the power transmission line and the running cost of the line are realized, and meanwhile, the safe and reliable running level of the overhead power transmission line in a corrosion environment is improved. The theoretical conductivity of high-purity aluminum (99.99% Al) can reach 64.94% IACS, but the tensile strength and the surface hardness are low, the tensile strength is lower than 100 MPa, the capability of resisting corrosive media such as chloride ions, acid rain and the like is low, and the high-purity aluminum can not be used in coastal, saline-alkali and industrial atmosphere and other environments with strong corrosivity.
At present, the conductivity of the duralumin monofilament in the international standard is unified to 61% IACS, and the current national standard GB/T17048-2017 for duralumin wires for overhead stranded wires in China divides the conductivity of the duralumin monofilament into 4 grades, namely 61% IACS, 61.5% IACS, 62% IACS and 62.5% IACS. The preparation technology of 63% IACS high-conductivity duralumin monofilament at home and abroad is still immature, and is mainly prepared by taking high-cost 99.9% high-purity aluminum as a raw material through strict production process control, so that the product qualification rate is relatively low, the manufacturing cost of the wire is 20% -30% higher than that of the existing common steel-cored aluminum stranded wire, and the technical development and large-scale popularization and application of the high-conductivity duralumin wire are severely restricted. Therefore, research and development and application of the hard aluminum monofilaments with high conductivity, corrosion resistance and low cost are of great significance for upgrading and reforming the power grid in China, improving the electric energy transmission efficiency and 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, high power transmission loss and weak corrosion resistance of an existing 61% IACS steel core aluminum stranded wire.
In order to achieve the above purpose, the invention is realized by adopting the following technical scheme:
in one aspect, 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, less than or equal to 0.007 percent of (V+Ti+Cr+Mn), and the balance of aluminum and unavoidable impurities.
Preferably, B:0.01 to 0.03 percent of Mg:0.02% -0.08%, sc:0.01 to 0.05 percent of Gd:0.01 to 0.05 percent.
Preferably, the components in percentage by mass are: b:0.026%, mg:0.078%, sc:0.038%, gd:0.02%, si: less than or equal to 0.062 percent, fe: less than or equal to 0.09 percent, less than or equal to 0.007 percent of (V+Ti+Cr+Mn), and the balance of aluminum and unavoidable impurities.
On the other hand, the invention provides a preparation method of the aluminum alloy monofilament, which comprises the following steps:
selecting aluminum for smelting, adding an Al-B intermediate alloy after the aluminum is completely melted, carrying out boronizing treatment, standing, sequentially adding the Al-Mg intermediate alloy, the Al-Sc intermediate alloy and the Al-Gd intermediate alloy for smelting, and stirring and mixing after the intermediate alloy is completely melted to obtain an aluminum alloy liquid;
introducing a purifying gas into the aluminum alloy liquid, adding a covering agent for standing treatment, removing slag and removing impurities to obtain an impurity-removed aluminum alloy liquid;
casting the impurity-removed aluminum alloy liquid into a mould to prepare an aluminum alloy ingot;
rolling an aluminum alloy ingot into an aluminum alloy round rod;
and carrying out repeated drawing deformation on the aluminum alloy round rod 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 the B is 8%;
and/or the Al-Mg intermediate alloy is formed by smelting and casting Al and Mg, and the mass content of the Mg is 10%;
and/or, smelting and casting Al and Sc to form the Al-Sc intermediate alloy, wherein the mass content of the Sc is 2%;
and/or the Al-Gd intermediate alloy is formed by smelting and casting Al and Gd, and the mass content of the Gd is 2%.
Preferably, aluminum is selected for smelting, the smelting temperature is kept at 730 ℃ to 750 ℃, and Al-B intermediate alloy is added at 740 ℃ to 750 ℃ for boride treatment; al-Mg intermediate alloy, al-Sc intermediate alloy and Al-Gd intermediate alloy are sequentially added at 740-750 ℃ for smelting. The aluminum feedstock of the present application employs low cost, commercially pure aluminum of 99.85% al purity.
Preferably, the purified gas introduced into the aluminum alloy liquid is nitrogen, the flow rate of the nitrogen is 20L/min-30L/min, and the ventilation time is not less than 15min.
Preferably, the impurity-removed aluminum alloy liquid is cast into a mold to prepare an aluminum alloy ingot, comprising: casting the impurity-removed aluminum alloy liquid into a red copper mold, and performing demolding treatment, wherein the demolding treatment temperature is less than or equal to 50 ℃.
Preferably, in the drawing deformation treatment process, a wire drawing die with a nano diamond composite coating is adopted to draw the aluminum alloy round rod for 10 times, so that the aluminum alloy round monofilament is prepared.
Preferably, the aluminum alloy round bar is subjected to drawing deformation treatment on a wire drawing machine at a speed of 13 m/s-15 m/s, wherein the temperature of the drawing deformation treatment is 40-50 ℃, and the deformation amount is 10-15%.
Preferably, the covering agent is rare earth flux, and is prepared from the following raw materials in percentage by mass: naF: naCl: KCl: na (Na) 2 SiF 6 =30%: 50%:10%:10%; further, the addition amount of the covering agent is 0.02% -0.04% of the aluminum alloy liquid.
Compared with the prior art, the invention has the beneficial effects that:
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, less than or equal to 0.007 percent of (V+Ti+Cr+Mn), and the balance of aluminum and unavoidable other trace impurity elements. By adding proper amounts of B, mg, sc and Gd alloying elements into 99.85% of industrial pure aluminum, the hard aluminum monofilament with high conductivity, corrosion resistance and low cost can be prepared, the electric energy transmission efficiency and safe operation level of an overhead transmission line can be improved, and the loss of the transmission line and the operation and maintenance cost can be reduced.
2. The invention provides a preparation method of aluminum alloy monofilaments, which comprises the following steps: selecting an aluminum ingot for smelting, adding an Al-B intermediate alloy for boride treatment, sequentially adding the Al-Mg intermediate alloy, the Al-Sc intermediate alloy and the Al-Gd intermediate alloy for smelting, and stirring and mixing after the intermediate alloy is completely melted to obtain an aluminum alloy liquid; introducing a purifying gas into the aluminum alloy liquid, adding a covering agent for standing treatment, removing slag and removing impurities to obtain an impurity-removed aluminum alloy liquid; casting the impurity-removed aluminum alloy liquid into a mould to prepare an aluminum alloy ingot. Rolling an aluminum alloy ingot into an aluminum alloy round rod; the aluminum alloy round rod is subjected to repeated drawing deformation, the prepared duralumin monofilament material does not need subsequent heat treatment, the preparation process of the high-conductivity duralumin monofilament material is simplified, meanwhile, the low-cost industrial pure aluminum with the purity of 99.85 percent 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 of the duralumin monofilament material is more than or equal to 63.0 percent IACS (20 ℃), the tensile strength of the duralumin monofilament material is more than or equal to 175 MPa, the elongation of the duralumin monofilament material is more than or equal to 2.0 percent, and the corrosion resistance of the duralumin monofilament material is 2 times that of the conventional duralumin monofilament in service, so that the conductive duralumin conductor can be popularized and applied on a large scale.
3. The preparation method provided by the invention is characterized in that industrial pure aluminum with the purity of 99.85% is adopted as a raw material, and trace amounts of 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 boride treatment. Solid solution of Mg element and second phase Mg 2 The formation of the Si intermetallic compound is helpful for improving the corrosion resistance of the duralumin alloy; the addition of Gd element can form a disperse phase to block dislocation and grain boundary movement, improve the recrystallization resistance of the alloy, ensure that a matrix retains more fine sub-crystal structures, and is beneficial to improving the corrosion resistance of the duralumin alloy; the addition of Sc element can reduce impurity content, has the functions of grain refinement and crystallization temperature improvement, and ensures that the hard aluminum alloy has high conductivity and good mechanical properties.
4. The smelting process adopts the blowing of high-purity N 2 The invention adopts the diamond wire drawing die to carry out 10 times of drawing on the hard aluminum alloy round bar with the diameter of 9.5mm, has better smoothness, temperature resistance and wear resistance than the hard aluminum alloy steel die, and simultaneously controls the wire drawing speed, the wire drawing temperature and the deformation by optimizing,the hard aluminum monofilament manufactured by drawing has good electric conduction, mechanical and corrosion resistance.
Detailed Description
The present invention will be further described below. The following examples are only for more clearly illustrating the technical aspects of the present invention, and are not intended to limit the scope of the present invention. All embodiments use industrially well-established smelting, rolling and 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 unavoidable impurities balance.
The preparation method comprises the following steps:
step 1, adding various alloy elements into industrial pure aluminum with the purity of 99.85 percent, so that the final content of the alloy elements is shown as above, adding the alloy elements into a frequency induction furnace in the form of Al-B, al-Mg, al-Sc and Al-Gd intermediate alloy, smelting at the smelting temperature of 730 ℃, adding the Al-B intermediate alloy at the temperature of 740 ℃ after the aluminum ingot is completely melted, and carrying out boride treatment; and (3) after standing for at least 30min, sequentially adding an Al-Mg intermediate alloy, an Al-Sc intermediate alloy and an Al-Gd intermediate alloy at 740 ℃, and carrying out electromagnetic stirring on the aluminum alloy liquid after the intermediate alloy is completely melted, wherein the stirring is carried out for 15min each time and 3 times each time for 10min, so as to obtain the aluminum alloy solution.
And 2, controlling the temperature of the aluminum alloy solution within a range of 740 ℃, introducing high-purity nitrogen (99.99%) for 15min, controlling the flow rate of the nitrogen introduced into the aluminum alloy solution at 20L/min, adding a covering agent with the addition amount of about 0.02% 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 720 ℃, and demolding at the demolding temperature of 42+/-2 ℃ to prepare aluminum alloy ingots with the dimensions of 30mm multiplied by 450 mm.
And 4, after the aluminum alloy ingot is kept at 490 ℃ for 1.5 hours, rolling the aluminum alloy ingot into a hard aluminum alloy round rod with the diameter of 9.5mm on a three-roller mill.
And 5, drawing a hard aluminum alloy round rod with the diameter of 9.5mm on a wire drawing machine at the speed of 13m/s, wherein the wire drawing temperature is controlled at 40 ℃, the deformation is controlled at 15%, the wire drawing die is a wire drawing die with a nano diamond composite coating, and the diamond wire drawing die is adopted to carry out wire drawing for 10 times, so that the aluminum alloy round monofilament with the diameter of 3.05mm is finally prepared.
Through detection, the conductivity of the duralumin monofilament prepared by the method is 63.18 percent IACS, the tensile strength is 175.2MPa, the elongation is 2.10 percent, 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 unavoidable impurities balance.
The preparation method comprises the following steps:
step 1, adding various alloy elements into industrial pure aluminum with the purity of 99.85 percent, so that the final content of the alloy elements is shown as above, adding the alloy elements into a frequency induction furnace in the form of Al-B, al-Mg, al-Sc and Al-Gd intermediate alloy, smelting at the smelting temperature of 740 ℃, adding the Al-B intermediate alloy at the temperature of 745 ℃ after the aluminum ingot is completely melted, and carrying out boride treatment; and (3) after standing for at least 30min, sequentially adding an Al-Mg intermediate alloy, an Al-Sc intermediate alloy and an Al-Gd intermediate alloy at 740 ℃, and carrying out electromagnetic stirring on the aluminum alloy liquid after the intermediate alloy is completely melted, wherein the stirring is carried out for 20min each time and 3 times each time for 15min, so as to obtain the aluminum alloy solution.
And 2, controlling the temperature of the aluminum alloy solution within the range of 730 ℃, introducing high-purity nitrogen (99.99%) for 15min, controlling the flow rate of the nitrogen introduced into the aluminum alloy solution at 25L/min, adding a covering agent with the addition amount of about 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 the demolding temperature of 45+/-2 ℃ to prepare aluminum alloy ingots with the dimensions of 30mm multiplied by 450 mm.
And 4, after the aluminum alloy ingot is kept at the temperature of 500 ℃ for 1.5 hours, rolling the aluminum alloy ingot into a hard aluminum alloy round rod with the diameter of 9.5mm on a three-roller mill.
And 5, drawing a hard aluminum alloy round rod with the diameter of 9.5mm on a wire drawing machine at the speed of 15 m/s, wherein the wire drawing temperature is controlled at 40 ℃, the deformation is controlled at 10%, the wire drawing die is a wire drawing die with a nano diamond composite coating, and the diamond wire drawing die is adopted to carry out wire drawing for 10 times, so that the aluminum alloy round monofilament with the diameter of 3.05mm is finally prepared.
Through detection, the conductivity of the duralumin monofilament prepared by the method is 63.25 percent IACS, the tensile strength is 176.3MPa, the elongation is 2.08 percent, 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 unavoidable impurities balance.
The preparation method comprises the following steps:
step 1, adding various alloy elements into industrial pure aluminum with the purity of 99.85 percent, so that the final content of the alloy elements is shown as above, adding the alloy elements into a frequency induction furnace in the form of Al-B, al-Mg, al-Sc and Al-Gd intermediate alloy, smelting at the smelting temperature of 740 ℃, adding the Al-B intermediate alloy at the temperature of 750 ℃ after the aluminum ingot is completely melted, and carrying out boride treatment; and (3) after standing for at least 30min, sequentially adding an Al-Mg intermediate alloy, an Al-Sc intermediate alloy and an Al-Gd intermediate alloy at 740 ℃, and carrying out electromagnetic stirring on the aluminum alloy liquid after the intermediate alloy is completely melted, wherein the stirring is carried out for 20min each time and 3 times each time for 10min, so as to obtain the aluminum alloy solution.
And 2, controlling the temperature of the aluminum alloy solution within a range of 740 ℃, introducing 20min of high-purity nitrogen (99.99%), controlling the flow rate of the nitrogen introduced into the aluminum alloy solution at 25L/min, adding a covering agent with the addition amount of about 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 the demolding temperature of 45+/-2 ℃ to prepare aluminum alloy ingots with the dimensions of 30mm multiplied by 450 mm.
And 4, after the aluminum alloy ingot is kept at the temperature of 500 ℃ for 1.5 hours, rolling the aluminum alloy ingot into a hard aluminum alloy round rod with the diameter of 9.5mm on a three-roller mill.
And 5, drawing a hard aluminum alloy round rod with the diameter of 9.5mm on a wire drawing machine at the speed of 13m/s, wherein the wire drawing temperature is controlled at 45 ℃, the deformation is controlled at 12%, the wire drawing die is a wire drawing die with a nano diamond composite coating, and the diamond wire drawing die is adopted to carry out wire drawing for 10 times, so that the aluminum alloy round monofilament with the diameter of 3.05mm is finally prepared.
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 unavoidable impurities balance.
The preparation method comprises the following steps:
step 1, adding various alloy elements into industrial pure aluminum with the purity of 99.85 percent, so that the final content of the alloy elements is shown as above, adding the alloy elements into a frequency induction furnace in the form of Al-B, al-Mg, al-Sc and Al-Gd intermediate alloy, smelting at the smelting temperature of 740 ℃, adding the Al-B intermediate alloy at the temperature of 750 ℃ after the aluminum ingot is completely melted, and carrying out boride treatment; and (3) after standing for at least 30min, sequentially adding an Al-Mg intermediate alloy, an Al-Sc intermediate alloy and an Al-Gd intermediate alloy at 740 ℃, and carrying out electromagnetic stirring on the aluminum alloy liquid after the intermediate alloy is completely melted, wherein the stirring is carried out for 20min each time and 3 times each time for 10min, so as to obtain the aluminum alloy solution.
And 2, controlling the temperature of the aluminum alloy solution within a range of 740 ℃, introducing 20min of high-purity nitrogen (99.99%), controlling the flow rate of the nitrogen introduced into the aluminum alloy solution at 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 the demolding temperature of 42+/-2 ℃ to prepare aluminum alloy ingots with the dimensions of 30mm multiplied by 450 mm.
And 4, after the aluminum alloy ingot is kept at 495 ℃ for 1.5 hours, rolling the aluminum alloy ingot into a hard aluminum alloy round rod with the diameter of 9.5mm on a three-roller mill.
And 5, drawing a hard aluminum alloy round rod with the diameter of 9.5mm on a wire drawing machine at the speed of 15 m/s, wherein the wire drawing temperature is controlled at 40 ℃, the deformation is controlled at 15%, the wire drawing die is a wire drawing die with a nano diamond composite coating, and the diamond wire drawing die is adopted to carry out wire drawing for 10 times, so that the aluminum alloy round monofilament with the diameter of 3.05mm is finally prepared.
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 unavoidable impurities balance.
The preparation method comprises the following steps:
step 1, adding various alloy elements into an industrial pure aluminum ingot with the purity of 99.85 percent, so that the final content of the alloy elements is shown as above, adding the alloy elements in a mode of Al-B, al-Mg, al-Sc and Al-Gd intermediate alloy into a frequency induction furnace for smelting, keeping the smelting temperature at 750 ℃, adding the Al-B intermediate alloy at 740 ℃ after the aluminum ingot is completely melted, and carrying out boride treatment; and (3) after standing for at least 30min, sequentially adding an Al-Mg intermediate alloy, an Al-Sc intermediate alloy and an Al-Gd intermediate alloy at 740 ℃, and carrying out electromagnetic stirring on the aluminum alloy liquid after the intermediate alloy is completely melted, wherein the stirring is carried out for 15min each time and 3 times each time for 15min, so as to obtain the aluminum alloy solution.
And 2, controlling the temperature of the aluminum alloy solution within a range of 740 ℃, introducing high-purity nitrogen (99.99%) for 15min, controlling the flow rate of the nitrogen introduced into the aluminum alloy solution at 30L/min, adding a covering agent with the addition amount of about 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 the demolding temperature of 45+/-2 ℃ to prepare aluminum alloy ingots with the dimensions of 30mm multiplied by 450 mm.
And 4, after the aluminum alloy ingot is kept at the temperature of 500 ℃ for 1.5 hours, rolling the aluminum alloy ingot into a hard aluminum alloy round rod with the diameter of 9.5mm on a three-roller mill.
And 5, drawing a hard aluminum alloy round rod with the diameter of 9.5mm on a wire drawing machine at the speed of 15 m/s, wherein the wire drawing temperature is controlled at 40 ℃, the deformation is controlled at 14%, the wire drawing die is a wire drawing die with a nano diamond composite coating, and the diamond wire drawing die is adopted to carry out wire drawing for 10 times, so that the aluminum alloy round monofilament with the diameter of 3.05mm is finally prepared.
Through detection, the conductivity of the duralumin monofilament prepared by the method is 63.28 percent IACS, the tensile strength is 175.8MPa, the elongation is 2.12 percent, 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): the Sc element can obviously improve the strength of the aluminum alloy, reduce dendrite segregation of the aluminum alloy and refine the grain structure of the aluminum alloy. Sc element can form primary Al in melt 3 Sc particles can be used as heterogeneous nucleation cores during crystallization nucleation, so that the grain structure is obviously refined; sc can also react with part of impurity elements in the aluminum alloy to change the impurity elements from an atomic state to a precipitation state, so that the conductivity of the aluminum alloy is improved.
Gd (gadolinium): the aluminum alloy is added with a proper amount of Gd element, so that a disperse phase can be formed to strongly block dislocation and grain boundary movement, the recrystallization resistance of the alloy is improved, and more fine sub-crystal structures of the matrix are reserved. Compared with a large-angle grain boundary, the corrosion potential difference between the subgrain boundary and the inside of the grain is smaller, the corrosion driving force is weakened, and the corrosion resistance of the aluminum alloy is improved.
Mg (magnesium): 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 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 element forms intermetallic compound Mg in the aluminum alloy 2 Si，Mg 2 Si has a lower electrode potential than pure aluminum, so in a corrosive environment, mg 2 Si is typically etched first, while the aluminum matrix is etched later. Therefore, the aluminum alloy has better corrosion resistance by optimally controlling the Mg content, but the conductivity of the aluminum alloy is reduced when the aluminum alloy is excessively added.
B (boron): if the impurity element in the aluminum alloy exists in a solid solution state, the conductivity can be reduced, and the boron element is used for carrying out the boronization treatment, so that the impurity content can be effectively reduced, namely, after a certain amount of B element is added in the smelting process of the electrical pure aluminum material, the boron element can react with impurity elements such as transition group element Cr, mn, V, ti and the like, so that the impurity element is converted into a compound state from the solid solution state and is deposited at the bottom of a melt, thereby purifying the aluminum conductor, and improving the conductivity of the aluminum alloy.
Cr (chromium), mn (manganese), V (vanadium), ti (titanium): the four elements are all impurity elements in the electrical pure aluminum. When the Cr, mn, V, ti impurity element in the aluminum material exists in a solid solution state, free electrons in the material are easily absorbed to fill the incomplete electron layers, and the reduction of the number of free electrons playing a conductive role leads to the increase of the resistivity of the aluminum material. Studies have shown that every 1% (Cr+Mn+V+Ti) impurity element has a 5-fold detrimental effect on the conductivity of aluminum conductors compared to every 1% Si element. It can be seen from this that the strict control of the content of the impurity element Cr, mn, V, ti plays an important role in ensuring the conductivity of the aluminum conductor.
The composition table of the produced duralumin alloy 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, less than or equal to 0.007 percent of (V+Ti+Cr+Mn), and the balance of aluminum and unavoidable other trace impurity elements.
Table 1 shows the composition (wt%) of the duralumin alloy prepared in the examples
The duralumin alloy monofilaments prepared in examples 1 to 5 and the common duralumin monofilaments of comparative examples were subjected to test experiments for diameter, conductivity, tensile strength, elongation and corrosion resistance.
The diameter test of the invention adopts a digital display outside micrometer with the model number of 0-25;
the conductivity test of the invention adopts a model TEGAM1750 microohm meter;
the tensile strength of the invention adopts an electro-hydraulic servo material tester with the model of MTS 810.25;
the extensibility of the invention adopts an electro-hydraulic servo material tester with the model of MTS 810.25;
the corrosion resistance performance of the invention adopts a salt spray box with the model of CCT10, and the adopted testing method is GB/T10125-2012 salt spray test for artificial atmosphere corrosion test.
The results of the diameter, conductivity, tensile strength, elongation and corrosion resistance test of the duralumin alloy prepared in examples 1 to 5 and comparative example and the general duralumin monofilament prepared in comparative example are shown in table 2.
Table 2 results of Performance test of duralumin monofilament materials prepared in examples and existing common duralumin monofilaments
As can be seen from Table 2, the high conductivity corrosion-resistant aluminum alloy monofilament material prepared by the method of the invention has obvious advantages in comprehensive performance, and research shows that the high conductivity corrosion-resistant aluminum alloy monofilament material is prepared by adding (0.005% -0.03%) by mass percent into an industrial pure aluminum ingot: (0.005% -0.10%): (. 005% -0.05%): compared with the existing common duralumin monofilament, the aluminum alloy monofilament prepared from B, mg, sc and Gd (0.005-0.05) has obviously improved conductivity, tensile strength, elongation and corrosion resistance, and particularly, under room temperature (20 ℃), the conductivity of the aluminum alloy monofilament prepared by the method is more than or equal to 63.0 percent IACS (20 ℃), the tensile strength is more than or equal to 175 MPa, the elongation is more than or equal to 2.0 percent, the corrosion resistance is more than or equal to 2.0 times that of the conventional duralumin monofilament, and the high-conductivity corrosion-resistant aluminum alloy monofilament material prepared by the method has higher stability as shown by a plurality of groups of experimental data. Meanwhile, the hard aluminum monofilament manufactured by drawing can have good electric conduction, mechanical and corrosion resistance by optimally controlling the drawing speed, the drawing temperature and the deformation. Therefore, by adding proper amounts of B, mg, sc and Gd alloying elements into an industrial pure aluminum ingot, the hard aluminum 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 can be reduced.
In summary, the invention provides the high-conductivity corrosion-resistant aluminum alloy monofilament for the overhead conductor and the preparation method thereof, 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-purity 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 of the duralumin monofilament material is more than or equal to 63.0% IACS (20 ℃), the tensile strength of the duralumin monofilament material is more than or equal to 175 MPa, the elongation of the duralumin monofilament material is more than or equal to 2.0%, and the corrosion resistance of the duralumin monofilament material is 2 times that of the conventional duralumin monofilament in service, so that the high-conductivity duralumin conductor can be popularized and applied on a large scale.
The foregoing is merely a preferred embodiment of the present invention, and it should be noted that modifications and variations could be made by those skilled in the art without departing from the technical principles of the present invention, and such modifications and variations should also be regarded as being within the scope of the invention.
Claims (5)
1. The preparation method of the aluminum alloy monofilament is characterized by comprising the following components in percentage by mass: b:0.005% -0.028%, mg:0.005% -0.10%, sc:0.005% -0.05%, gd:0.005% -0.036%, si: less than or equal to 0.07 percent, fe: less than or equal to 0.10 percent, less than or equal to 0.007 percent of (V+Ti+Cr+Mn), and the balance of aluminum and unavoidable impurities;
the preparation method comprises the following steps:
aluminum is selected for smelting, the smelting temperature is kept at 730 ℃ to 750 ℃, and after the aluminum is completely melted, al-B intermediate alloy is added at 740 ℃ to 750 ℃ for boride treatment; after standing, sequentially adding Al-Mg intermediate alloy, al-Sc intermediate alloy and Al-Gd intermediate alloy at 740-750 ℃ for smelting; stirring and mixing after the intermediate alloy is completely melted to obtain aluminum alloy liquid;
introducing a purifying gas into the aluminum alloy liquid, adding a covering agent for standing treatment, removing slag and removing impurities to obtain an impurity-removed aluminum alloy liquid; the purifying gas is nitrogen, the flow rate of the nitrogen is 20L/min-30L/min, and the ventilation time is not less than 15min;
casting the impurity-removed aluminum alloy liquid into a mould to prepare an aluminum alloy ingot;
rolling an aluminum alloy ingot into an aluminum alloy round rod;
carrying out repeated drawing deformation on the aluminum alloy round rod to obtain aluminum alloy round monofilaments;
carrying out drawing deformation treatment on the aluminum alloy round rod on a wire drawing machine at a speed of 13 m/s-15 m/s, wherein the temperature of the drawing deformation treatment is 40-50 ℃ and the deformation is 10-15%;
the covering agent is rare earth flux, and is prepared from the following raw materials in percentage by mass: naF: naCl: KCl: na (Na) 2 SiF 6 =30%: 50%:10%:10%; the addition amount of the covering agent is 0.02% -0.04% of the aluminum alloy liquid.
2. The method of producing aluminum alloy monofilaments of claim 1, wherein B:0.01 to 0.028 percent, mg:0.02% -0.08%, sc:0.01 to 0.05 percent of Gd:0.01 to 0.036 percent.
3. The method for preparing aluminum alloy monofilaments of claim 1, wherein the mass percentages are as follows: b:0.026%, mg:0.078%, sc:0.038%, gd:0.02%, si: less than or equal to 0.062 percent, fe: less than or equal to 0.09 percent, less than or equal to 0.007 percent of (V+Ti+Cr+Mn), and the balance of aluminum and unavoidable impurities.
4. The method for producing aluminum alloy monofilaments of claim 1, wherein the Al-B master 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, and the mass content of the Mg is 10%;
and/or, smelting and casting Al and Sc to form the Al-Sc intermediate alloy, wherein the mass content of the Sc is 2%;
and/or the Al-Gd intermediate alloy is formed by smelting and casting Al and Gd, and the mass content of the Gd is 2%.
5. The method of producing aluminum alloy monofilaments according to claim 1, wherein the casting of the impurity-removed aluminum alloy liquid into a mold to produce an aluminum alloy ingot comprises: casting the impurity-removed aluminum alloy liquid into a red copper mold, and performing demolding treatment, wherein the demolding treatment temperature is less than or equal to 50 ℃.
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