High conductivity medium strength aluminum alloy wire and its preparation method

Abstract

This invention discloses a high-conductivity, medium-strength aluminum alloy wire and its preparation method, belonging to the field of metallurgy. Its chemical composition, by weight percentage, includes the following components: Mg 0.40–0.48 wt%, Si 0.35–0.43 wt%, Cu 0.01–0.05 wt%, Fe 0.10–0.18 wt%, B 0.01–0.02 wt%, Ti 0.01–0.02 wt%, Sc 0.05–0.15 wt%, Y 0.15–0.30 wt%, with the balance being Al and other unavoidable impurities, including Cr, Mn, V, etc., wherein (Cr+Mn+V) ≤ 0.005 wt%; and the aluminum alloy wire undergoes at least two cold drawing treatments and at least two aging treatments. This invention can significantly improve the strength of aluminum alloys by rationally configuring the content of six alloying elements, making the conductivity of medium-strength aluminum alloy wire ≥60.5% IACS, tensile strength ≥245MPa, and elongation ≥4%. It can be used for transmission lines with large spans and large drops, and has significant economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of metallurgy, and in particular to a high conductivity medium-strength aluminum alloy wire and its preparation method. Background Technology

[0002] The most widely used overhead transmission lines are steel-cored aluminum stranded wires. However, with the advancement of technology and the needs of the power industry, aluminum alloy conductors have been increasingly adopted by countries around the world due to their superior technical performance, good operating results, and especially their excellent performance in ultra-high voltage lines and long-span lines.

[0003] Aluminum alloy single wires mainly include medium-strength aluminum alloy wires, high-strength aluminum alloy wires, and heat-resistant aluminum alloy wires. In 2013, major Chinese conductor manufacturers developed an aluminum alloy material called LHA3. This aluminum alloy is an aging aluminum alloy, produced by adding alloying elements such as Fe, Mg, and Si, followed by cold working hardening and aging heat treatment to achieve a single wire conductivity of no less than 58.5% IACS, a single wire tensile strength of no less than 230 MPa, and a single wire elongation of no less than 3.5%. Due to its excellent energy-saving effect and low sag characteristics, this aluminum alloy wire has subsequently been widely used in main grids.

[0004] Using high-conductivity medium-strength aluminum alloy wire not only reduces conductor weight and increases the conductor pull-to-weight ratio, but also increases conductor transmission capacity and reduces line losses. To further reduce transmission losses in medium-strength aluminum alloy wire, domestic research institutes have developed medium-strength aluminum alloy wire with a conductivity ≥59.2% IACS and a strength of 232–249 MPa. Further improving the conductivity of medium-strength aluminum alloy wire requires either increasing the purity of aluminum, which leads to excessively high costs and prohibits commercial applications. Therefore, a special aluminum alloy formula and processing technology are used to obtain high-conductivity medium-strength aluminum alloy wire with both high strength and conductivity, resulting in lower costs and enabling mass production. Summary of the Invention

[0005] To overcome the above-mentioned technical defects, the present invention provides a high conductivity medium-strength aluminum alloy wire and its preparation method to solve the problems involved in the background art.

[0006] This invention provides a high conductivity medium-strength aluminum alloy wire and its preparation method. Its chemical composition, by weight percentage, comprises the following components: Mg 0.40–0.48 wt%, Si 0.35–0.43 wt%, Cu 0.01–0.05 wt%, Fe 0.10–0.18 wt%, B 0.01–0.02 wt%, Ti 0.01–0.02 wt%, Sc 0.05–0.15 wt%, Y 0.15–0.30 wt%, with the balance being Al and other unavoidable impurities, including Cr, Mn, V, etc., wherein (Cr+Mn+V) ≤ 0.005 wt%.

[0007] Furthermore, the aluminum alloy wire undergoes at least two cold drawing processes and at least two aging processes.

[0008] Preferably or optionally, the aluminum alloy wire has a diameter of 2.8 mm to 4.0 mm, a conductivity of ≥60.5% IACS, a tensile strength of ≥245 MPa, and an elongation of ≥4%.

[0009] This invention also provides a method for preparing a high-conductivity, medium-strength aluminum alloy wire, comprising the following steps:

[0010] S1. Smelting: Melting aluminum ingots and pouring them into a holding furnace;

[0011] S2, nucleation regulation: First, add aluminum-titanium master alloy ingots to increase the number of active anisotropic nuclei;

[0012] S3. Boring treatment: Add aluminum-boron master alloy ingots and perform boronizing treatment;

[0013] S4. Composition control: Aluminum alloy liquid is prepared by sequentially adding aluminum-copper master alloy ingots, aluminum-iron master alloy ingots, aluminum-silicon master alloy ingots, aluminum-yttrium master alloy ingots, aluminum-scandium master alloy ingots, and magnesium ingots; and the aluminum alloy liquid is stirred using an electromagnetic automatic stirrer.

[0014] S5. Multi-stage purification: After stirring, add a high-efficiency sodium-free refining agent and a covering agent to the holding furnace.

[0015] S6. Multi-stage degassing: Two-stage degassing is performed on the molten aluminum alloy before casting;

[0016] S7. Grain refinement: Grain refinement is achieved by adding a grain refiner to the molten aluminum alloy.

[0017] S8. Continuous casting: Aluminum alloy ingots are obtained by continuous casting using a horizontal flat surface casting method.

[0018] S9. Solution treatment: Continuous solution treatment of aluminum alloy billets;

[0019] S10, Continuous rolling: Rolling aluminum alloy billets into aluminum alloy rods;

[0020] S11, Quenching: The aluminum alloy rod is subjected to continuous quenching treatment;

[0021] S12, Natural Aging: Place the aluminum alloy rod indoors for natural aging;

[0022] S13. Large deformation cold drawing treatment: The aluminum alloy rod is subjected to large deformation cold drawing treatment to produce a coarse aluminum alloy wire blank;

[0023] S14. First aging treatment: Pre-aging treatment is performed on the crude aluminum alloy wire rod.

[0024] S15. Fine machining: The pre-aged aluminum alloy wire blank is subjected to final cold deformation.

[0025] S16. Second aging treatment: The aluminum alloy wire that has undergone final cooling deformation will undergo final artificial aging treatment.

[0026] Preferably or optionally, in step S2, after adding the aluminum-titanium master alloy ingot, the Ti content in the aluminum alloy liquid is 0.01-0.02 wt%.

[0027] Preferably or optionally, in step S3, after the boronizing treatment, the total content of Cr, Mn, V and Ti in the aluminum alloy liquid does not exceed 0.005 wt%.

[0028] Preferably or optionally, in step S4, the chemical composition of the aluminum alloy liquid comprises the following components by weight percentage: Mg 0.40-0.48wt%, Si 0.35-0.43wt%, Cu 0.01-0.05wt%, Fe 0.10-0.18wt%, Sc 0.05-0.15wt%, Y 0.15-0.30wt%, (Cr+Mn+V+Ti)≤0.005wt%.

[0029] The temperature of the molten aluminum alloy in the heat preservation furnace is 720-730℃.

[0030] Preferably or optionally, in step S5, the multi-stage purification step includes the following method:

[0031] High-efficiency sodium-free refining agent was blown into the molten aluminum alloy in the furnace from left to right and from front to back along with N2. The blowing temperature was 710-735℃ and the refining time was 10-15 minutes.

[0032] After the first stage of refining, the slag on the surface of the molten aluminum alloy is removed. Then, a high-efficiency sodium-free refining agent is blown into the molten aluminum alloy in the furnace from left to right and from front to back with N2. The blowing temperature is 710-735℃ and the refining time is 10-15 minutes.

[0033] After the secondary refining is completed, the slag on the surface of the aluminum alloy liquid is removed, and then a covering agent is evenly sprayed onto the surface of the aluminum alloy liquid in the furnace.

[0034] The highly efficient sodium-free refining agent is selected from MgCl2, KCl, CaF2, KALF4, K2CO3, and MgCO3.

[0035] The weight ratio of the high-efficiency sodium-free refining agent added to the molten aluminum alloy is 2.0:1000.

[0036] The covering agent includes MgCl2, KCl, and CaF2;

[0037] The weight ratio of the covering agent to the molten aluminum alloy is 1.0:1000.

[0038] Preferably or optionally, in step S6, an online impurity removal system is used for degassing and filtration, the online impurity removal system including a degassing device and a filtration device;

[0039] The degassing device uses 99.99% high-purity N2 to blow in, with a flow rate of 40-50 ml / min and a temperature of 750℃;

[0040] The filtration device adopts a double-layer ceramic structure, and the hydrogen content of the aluminum alloy liquid after filtration is no more than 0.100ml / 100g.

[0041] Preferably or optionally, in step S7, 0.2% to 0.25% of 5Ti1B grain refiner is added at the inlet of the online impurity removal system to make the Ti content in the aluminum alloy liquid 0.01 to 0.02 wt% and the B content 0.01 to 0.02 wt%.

[0042] Preferably or optionally, in step S8, the aluminum liquid casting temperature is 690℃~720℃;

[0043] Preferably or optionally, in step S9, an induction heating device is used for heating, and the solution treatment temperature of the aluminum alloy ingot is 530℃~550℃.

[0044] Preferably or optionally, in step S10, continuous rolling employs 4 sets of large deformation rolling mills and 10 sets of hot finishing rolling mills; the concentration of the cooling emulsion used for rolling is 8-12%, and the pH value is 7-9; during rolling, the emulsion temperature is 45-50℃, the emulsion pressure is 200kPa, the obtained aluminum alloy rod size is 9.5±0.1mm, and the resistivity of the aluminum alloy rod is not greater than 0.0320Ω·mm within 4 hours. 2 / m, tensile strength 150-170MPa within 4 hours, elongation 7-15%;

[0045] Preferably or optionally, in step S12, the natural aging process is to place the aluminum alloy rod in an environment with a temperature of 10℃~30℃ for 168h~192h.

[0046] Preferably or optionally, in step S13, the large deformation cold drawing process is to perform a large deformation cold drawing process on the aluminum alloy rod by 60% to 90% to produce a coarse aluminum alloy wire blank with a diameter of 5mm to 6mm.

[0047] Preferably or optionally, in step S14, the parameters for the first aging treatment are: aging temperature of 120℃~140℃ and aging time of 2h~8h.

[0048] Preferably or optionally, in step S15, the coarse aluminum alloy wire blank after the first aging treatment is drawn into fine aluminum alloy wire with a diameter of 2.8 mm to 4.0 mm.

[0049] Preferably or optionally, in step S16, the second aging treatment adopts a two-stage aging method, which involves treating at 120°C for 2 hours and then treating at 150°C for another 6 hours.

[0050] This invention relates to a high-conductivity, medium-strength aluminum alloy wire and its preparation method, which has the following advantages compared to the prior art:

[0051] (1) In the formulation of this invention, Si and Mg form a Mg2Si strengthening phase, which significantly improves the strength of the aluminum alloy through second-phase strengthening. Cu element accelerates the aging response, and the early precipitates are smaller in size and have a higher number density, thus improving strength and thermal stability. Ti forms TiAl3 phase with aluminum, becoming a non-spontaneous nucleus during crystallization, refining the grains and improving the strength of the alloy. After adding a small amount of Fe during aging, Fe affects the precipitation behavior of the Al-Mg-Si alloy, making precipitation easier, with more nuclei and faster precipitation, resulting in significant improvements in strength and conductivity. B element forms dense refractory compounds with transition elements such as V, Ti, Mn, and Cr, which are deposited at the bottom of the molten aluminum and removed, thereby improving the conductivity of the aluminum alloy wire. Reasonable configuration of the content of the six alloying elements can significantly improve the strength of the aluminum alloy, making the conductivity of the medium-strength aluminum alloy wire ≥60.5% IACS, tensile strength ≥245MPa, and elongation ≥4%, which can be used for transmission lines with large spans and large drops, with significant economic benefits.

[0052] (2) The high conductivity medium strength aluminum alloy wire produced by the process of the present invention has the characteristics of high conductivity, high strength, large elongation and good stress corrosion resistance. It can be used for long-span, long-distance high voltage transmission lines with large drop and significant economic benefits.

[0053] (3) In this invention, Ti element is added before preparing aluminum alloy melt. Trace amounts of titanium element are beneficial to further precipitation of trace transition metal elements, thereby achieving efficient boronizing treatment effect.

[0054] (4) The present invention blows in a high-efficiency sodium-free refining agent from multiple directions at high temperature. The high-efficiency sodium-free refining agent has good impurity removal and degassing, which improves the refining degree and effect of aluminum alloy liquid.

[0055] (5) The present invention adopts a horizontal pouring method, which allows the aluminum alloy liquid to enter the T-shaped groove of the crystallizing wheel smoothly, avoiding the oxidation caused by fluctuation of the alloy liquid and the generation of impurities.

[0056] (6) The degassing device of the present invention uses N2 high temperature blowing. N2 has high inertness and good protection for aluminum alloy liquid, making the aluminum alloy liquid less prone to oxidation. The filter device adopts a double-layer ceramic structure. The hydrogen content of the aluminum alloy liquid after filtration is no more than 0.100ml / 100g, which reduces metal oxides and gaseous impurities, prevents the tendency of alloy porosity, improves the processing performance of ultra-high strength aluminum alloy rod and improves the electrical conductivity of aluminum alloy rod.

[0057] (7) This invention uses 0.2% to 0.25% Al5Ti1B refining agent added online. After dissolution, the refining agent is stirred at high speed by a rotor in an online degassing device, so that the refining agent is evenly distributed in the aluminum alloy liquid. This reduces the thermal stress caused by solidification shrinkage, reduces hot cracking, refines the grains of the casting, and prevents the formation of coarse equiaxed crystals, columnar crystals, and feathery crystals.

[0058] (8) In the rolling process of this invention, a short-term solid solution treatment at 530-550℃ is first performed to fully dissolve the phase particles in the alloy, maximizing the number of solute atoms in the Mg and Si matrix. The solute atoms dissolved in the aluminum matrix to form a supersaturated solid solution strengthen the alloy through solid solution. Four sets of large deformation rolling mills and ten sets of finishing rolling mills are used to roll the alloy rod to about 9.50 mm. After rolling, continuous water cooling is used to obtain a metastable supersaturated solid solution, creating the necessary conditions for the precipitation of phases during subsequent natural and artificial aging, so as to obtain high strength and sufficient plasticity during subsequent aging.

[0059] (9) In this invention, before wire drawing, the aluminum alloy rod is subjected to a natural aging process at a temperature of 10℃~30℃ for 168h~192h. Natural aging forms a large number of atomic clusters, which serve as nucleation centers for precipitates. The subsequent precipitates are smaller in size, more uniformly distributed, denser, and more dispersed. This can effectively improve the strength of the aluminum alloy.

[0060] (10) The present invention uses aluminum alloy rods with a large deformation of 60%-90% to cold draw to produce coarse aluminum alloy wire blanks with a diameter of 5mm to 6mm; the grains of the wire blanks after drawing are refined, internal defects increase, dislocation density increases, vacancy concentration increases, and the strength of the material is improved.

[0061] (11) This invention employs a sub-aging process to age aluminum alloy wire rods at 120℃~140℃ for 2h~8h, thereby reducing the supersaturation of solute atoms in the aluminum matrix due to the formation of atomic clusters. This can effectively improve the conductivity of the aluminum alloy.

[0062] (12) The coarse aluminum alloy wire blank after the under-aging treatment is drawn into fine aluminum alloy wire with a diameter of 2.8mm to 3.8mm.

[0063] (13) The present invention adopts a two-stage aging treatment method, the aging process is: 120℃ / 2h + 150℃×6h, so that the alloy precipitates are effectively and uniformly distributed, so that the high conductivity medium strength aluminum alloy wire has good conductivity while maintaining high strength. Detailed Implementation

[0064] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid obscuring the invention.

[0065] This embodiment discloses a high conductivity medium-strength aluminum alloy wire, whose chemical composition by weight percentage includes the following components: Mg 0.40-0.48wt%, Si 0.35-0.43wt%, Cu 0.01-0.05wt%, Fe 0.10-0.18wt%, B 0.01-0.02wt%, Ti 0.01-0.02wt%, Sc 0.05-0.15wt%, Y 0.15-0.30wt%, with the balance being Al and other unavoidable impurities, including Cr, Mn, V, etc., wherein (Cr+Mn+V)≤0.005wt%; and the aluminum alloy wire undergoes at least two cold drawing treatments and at least two aging treatments.

[0066] Among these elements, Si and Mg form the Mg2Si strengthening phase, significantly improving the strength of the aluminum alloy through second-phase strengthening. Cu accelerates the aging response, resulting in smaller and denser early precipitates, thus enhancing strength and thermal stability. Ti forms the TiAl3 phase with aluminum, acting as a non-spontaneous nucleus during crystallization, refining grains and increasing alloy strength. Adding a small amount of Fe during aging affects the precipitation behavior of the Al-Mg-Si alloy, making precipitation easier, resulting in more and faster nucleation of precipitates, significantly improving strength and conductivity. Botanicals (B) form denser refractory compounds with transition elements such as V, Ti, Mn, and Cr, depositing at the bottom of the molten aluminum and being removed, thereby improving the conductivity of the aluminum alloy wire. A reasonable configuration of the six alloying elements can significantly improve the strength of the aluminum alloy, resulting in a medium-strength aluminum alloy wire with a conductivity ≥60.5% IACS, tensile strength ≥245MPa, and elongation ≥4%, suitable for transmission lines with long spans and significant elevation differences, offering significant economic benefits.

[0067] This embodiment discloses a method for preparing a high-conductivity, medium-strength aluminum alloy wire, comprising the following steps:

[0068] S1. Smelting: Smelting aluminum ingots and pouring them into a holding furnace; specifically, using aluminum ingots with an aluminum content of 99.70%, melting them into molten aluminum, and then releasing them into the holding furnace.

[0069] S2. Nucleation Control: First, an aluminum-titanium master alloy ingot is added to increase the number of active anisotropic nuclei; specifically, an aluminum-titanium master alloy ingot is added to make the Ti content in the aluminum alloy melt 0.01-0.02 wt%. This invention adds Ti element before preparing the aluminum alloy melt. Trace amounts of titanium element are beneficial for further precipitation of trace transition metal elements, achieving a highly efficient borosilicated treatment effect.

[0070] S3. Boring treatment: Add aluminum-boron master alloy ingots and perform boronizing treatment; specifically, after boronizing treatment, the total content of Cr, Mn, V and Ti in the aluminum alloy liquid does not exceed 0.005 wt%.

[0071] S4. Composition Control: Aluminum-copper master alloy ingots, aluminum-iron master alloy ingots, aluminum-silicon master alloy ingots, aluminum-yttrium master alloy ingots, aluminum-scandium master alloy ingots, and magnesium ingots are added sequentially to form an aluminum alloy liquid. The aluminum alloy liquid is stirred using an electromagnetic automatic stirrer. Specifically, the chemical composition of the aluminum alloy liquid, by weight percentage, includes the following components: Mg 0.40–0.48 wt%, Si 0.35–0.43 wt%, Cu 0.01–0.05 wt%, Fe 0.10–0.18 wt%, Sc 0.05–0.15 wt%, Y 0.15–0.30 wt%, (Cr+Mn+V+Ti) ≤ 0.005 wt%. The temperature of the aluminum alloy liquid in the holding furnace is 720–730 °C.

[0072] S5. Multi-stage purification: After stirring, add high-efficiency sodium-free refining agent and covering agent to the holding furnace; specifically, the multi-stage purification step includes the following method: blow high-efficiency sodium-free refining agent into the aluminum alloy liquid in the furnace from left to right and from front to back with N2, the blowing temperature is 710-735℃, and the refining time is 10-15min; after the first stage of refining is completed, remove the slag from the surface of the aluminum alloy liquid. A high-efficiency sodium-free refining agent is blown into the molten aluminum alloy in the furnace from left to right and from front to back sequentially along with N2. The blowing temperature is 710–735℃, and the refining time is 10–15 minutes. After the secondary refining is completed, the slag on the surface of the molten aluminum alloy is removed, and then a covering agent is evenly sprayed onto the surface of the molten aluminum alloy in the furnace. The high-efficiency sodium-free refining agent is one of MgCl2, KCl, CaF2, KALF4, K2CO3, and MgCO3. The weight ratio of the high-efficiency sodium-free refining agent to the molten aluminum alloy is 2.0:1000. The covering agent includes MgCl2, KCl, and CaF2. The weight ratio of the covering agent to the molten aluminum alloy is 1.0:1000. This invention blows in the high-efficiency sodium-free refining agent at high temperature from multiple directions. The high-efficiency sodium-free refining agent has good impurity removal and degassing properties, improving the refining degree and effect of the molten aluminum alloy. The degassing device of this invention uses high-temperature N2 blowing. N2 has high inertness and good protection for the aluminum alloy liquid, making it less prone to oxidation. The filtration device adopts a double-layer ceramic structure, and the hydrogen content of the aluminum alloy liquid after filtration is no more than 0.100ml / 100g, which reduces metal oxides and gaseous impurities, prevents the tendency of alloy porosity, improves the processing performance of ultra-high strength aluminum alloy rods, and enhances the electrical conductivity of aluminum alloy rods.

[0073] S6. Multi-stage degassing: The aluminum alloy molten metal before casting undergoes two-stage degassing; specifically, an online impurity removal system is used for degassing and filtration, the online impurity removal system including a degassing device and a filtration device; the degassing device uses 99.99% high-purity N2 to blow in, with a flow rate of 40-50 ml / min and a temperature of 750℃; the filtration device adopts a double-layer ceramic structure, and the hydrogen content of the aluminum alloy molten metal after filtration is no more than 0.100 ml / 100 g.

[0074] S7. Grain Refinement: Grain refinement is achieved by adding a grain refiner to the molten aluminum alloy. Specifically, 0.2%–0.25% of Al5Ti1B grain refiner is added at the inlet of the online impurity removal system, resulting in a Ti content of 0.01–0.02 wt% and a B content of 0.01–0.02 wt% in the molten aluminum alloy. This invention uses the online addition of 0.2%–0.25% Al5Ti1B grain refiner. After dissolution, the refiner is stirred at high speed by a rotor in the online degassing device, ensuring uniform distribution of the refiner throughout the molten aluminum alloy. This reduces thermal stress caused by solidification shrinkage, minimizes hot cracking, refines the grains in the casting, and prevents the formation of coarse equiaxed crystals, columnar crystals, and feathery crystals.

[0075] S8. Continuous casting: Aluminum alloy ingots are obtained by continuous casting using a horizontal flat surface casting method; specifically, the aluminum liquid casting temperature is 690℃~720℃. This invention introduces a high-efficiency sodium-free refining agent at high temperatures from multiple directions. The high-efficiency sodium-free refining agent has good impurity removal and degassing properties, improving the refining degree and effect of the aluminum alloy liquid.

[0076] S9. Solution Treatment: The aluminum alloy ingot is subjected to continuous solution treatment; specifically, an induction heating device is used for heating, and the solution treatment temperature of the aluminum alloy ingot is 530℃~550℃. In the rolling process of this invention, a short-time solution treatment at 530~550℃ is first performed to fully dissolve the phase particles in the alloy, maximizing the number of solute atoms in the Mg and Si element matrix. The solute atoms dissolved in the aluminum matrix to form supersaturated solid solutions exert solid solution strengthening on the alloy.

[0077] S10. Continuous Rolling: The aluminum alloy billet is rolled into an aluminum alloy rod. Specifically, continuous rolling employs four sets of large deformation rolling mills and ten sets of hot finishing rolling mills, rolling the alloy rod to approximately 9.50 mm. After rolling, continuous water cooling is used to obtain a metastable supersaturated solid solution, creating the necessary conditions for subsequent natural and artificial aging phase precipitation, aiming to achieve high strength and sufficient plasticity during subsequent aging. The cooling emulsion used in rolling has a concentration of 8–12% and a pH value of 7–9; during rolling, the emulsion temperature is 45–50℃, and the emulsion pressure is 200 kPa. The obtained aluminum alloy rod has a size of 9.5 ± 0.1 mm, and the resistivity of the aluminum alloy rod is no greater than 0.0320 Ω·mm within 4 hours. 2 / m, tensile strength 150-170MPa within 4 hours, elongation 7-15%.

[0078] S11, Quenching: The aluminum alloy rod is subjected to continuous quenching treatment;

[0079] S12. Natural Aging: The aluminum alloy rod is placed indoors for natural aging. Specifically, the natural aging process involves placing the aluminum alloy rod in an environment with a temperature of 10℃~30℃ for 168h~192h. Natural aging forms a large number of atomic clusters, which serve as nucleation centers for precipitated phases. Subsequent precipitated phases are smaller in size, more uniformly distributed, denser, and more dispersed. This can effectively improve the strength of the aluminum alloy.

[0080] S13. Large Deformation Cold Drawing Treatment: The aluminum alloy rod is subjected to large deformation cold drawing treatment to produce a coarse aluminum alloy wire blank. Specifically, the large deformation cold drawing process involves cold drawing the aluminum alloy rod with a large deformation of 60% to 90% to produce a coarse aluminum alloy wire blank with a diameter of 5mm to 6mm. After the drawing treatment, the grains of the wire blank are refined, the internal defects increase, the dislocation density increases, the vacancy concentration increases, and the strength of the material is improved.

[0081] S14. First Aging Treatment: The rough aluminum alloy wire rod is subjected to pre-aging treatment; specifically, the parameters for the first aging treatment are: aging temperature of 120℃~140℃, and aging time of 2h~8h. The formation of atomic clusters reduces the supersaturation of solute atoms in the aluminum matrix, which can effectively improve the conductivity of the aluminum alloy.

[0082] S15. Fine machining: The coarse aluminum alloy wire blank after pre-aging treatment is subjected to final cold deformation; specifically, the coarse aluminum alloy wire blank after the first aging treatment is drawn into fine aluminum alloy wire with a diameter of 2.8mm to 4.0mm.

[0083] S16. Second Aging Treatment: The final artificial aging treatment is performed on the cooled aluminum alloy wire. Specifically, the second aging treatment adopts a two-stage aging method, treating at 120℃ for 2 hours, and then at 150℃ for 6 hours. This two-stage aging treatment ensures effective and uniform distribution of the alloy precipitates, allowing the high-conductivity, medium-strength aluminum alloy wire to maintain high strength while possessing good electrical conductivity.

[0084] The present invention will be further described below with reference to the embodiments. The examples described are intended to explain the present invention and should not be construed as limiting the present invention.

[0085] Example 1-1

[0086] A method for preparing a high-conductivity, medium-strength aluminum alloy wire includes the following steps:

[0087] S1. After melting aluminum ingots with an aluminum content of 99.70% into molten aluminum, the molten aluminum is discharged into a holding furnace.

[0088] S2. Then add aluminum-titanium intermediate alloy ingots to make the Ti content in the aluminum alloy liquid 0.015wt%.

[0089] S3. Then add aluminum-boron master alloy ingots and perform boronizing treatment. After boronizing treatment, the total content of Cr, Mn, V and Ti in the aluminum alloy liquid does not exceed 0.005 wt%.

[0090] S4. Then, aluminum-copper master alloy ingots, aluminum-iron master alloy ingots, aluminum-silicon master alloy ingots, aluminum-yttrium master alloy ingots, aluminum-scandium master alloy ingots, and magnesium ingots are added in sequence to form an aluminum alloy liquid; and an electromagnetic automatic stirrer is used to stir the aluminum alloy liquid; the temperature of the aluminum alloy liquid in the holding furnace is set to 730℃.

[0091] S5. A high-efficiency sodium-free refining agent (a mixture of 40 wt% MgCl2, 40 wt% KCl, 5 wt% CaF2, 10 wt% KALF4, and 5 wt% K2CO3 or MgCO3) is sequentially blown into the molten aluminum alloy in the furnace from left to right and from front to back with N2. The blowing temperature is 725℃, and the refining time is 12 minutes. After the first stage of refining, the slag on the surface of the molten aluminum alloy is removed. The high-efficiency sodium-free refining agent is then sequentially blown into the molten aluminum alloy in the furnace from left to right and from front to back with N2 again. The blowing temperature is 725℃, and the refining time is 12 minutes. After the second stage of refining, the slag on the surface of the molten aluminum alloy is removed, and then a covering agent (a mixture of 47 wt% MgCl2, 47 wt% KCl, and 6 wt% CaF2) is evenly sprayed onto the surface of the molten aluminum alloy in the furnace.

[0092] S6. An online impurity removal system is used for degassing and filtration. The online impurity removal system includes a degassing device and a filtration device. The degassing device uses 99.99% high-purity N2 to blow in at a flow rate of 45 ml / min and a temperature of 750°C. The filtration device uses a double-layer ceramic structure, and the hydrogen content of the aluminum alloy liquid after filtration is no more than 0.100 ml / 100 g.

[0093] S7. Add 5Ti1B grain refiner at 0.2% to 0.25% of the aluminum alloy liquid at the inlet of the online impurity removal system to refine the grains of the aluminum alloy liquid, so that the Ti content in the aluminum alloy liquid is 0.016wt% and the B content is 0.011wt%.

[0094] S8. Aluminum alloy ingots are obtained by continuous casting at a pouring temperature of 700℃ using a horizontal surface casting method.

[0095] S9. A short-term solution treatment at 540°C is performed using an induction heating device.

[0096] S10. After short-term solution treatment, the alloy rod is continuously rolled using four sets of large deformation rolling mills and ten sets of hot finishing rolling mills. The concentration of the cooling emulsion used in the rolling is 10%, and the pH value is 7-9. During rolling, the emulsion temperature is 58℃ and the emulsion pressure is 200kPa. The alloy rod is rolled to approximately 9.50mm. After rolling, continuous water cooling is used to achieve an aluminum alloy rod size of 9.5±0.1mm. The resistivity of the aluminum alloy rod is no greater than 0.0320Ω·mm within 4 hours. 2 / m, tensile strength 150-170MPa within 4 hours, elongation 7-15%.

[0097] S11. Then the aluminum alloy rod undergoes continuous quenching treatment;

[0098] S12. Place the aluminum alloy rod indoors for natural aging; the natural aging process is as follows: place the aluminum alloy rod in an environment with a temperature of 25℃ for 168 hours.

[0099] S13. The aluminum alloy rod undergoes a large deformation cold drawing process. The aluminum alloy rod is subjected to a large deformation cold drawing process of 60% to 90% to produce a coarse aluminum alloy wire blank with a diameter of 5mm to 6mm.

[0100] S14. Pre-aging treatment is performed on the crude aluminum alloy wire blank; the aging temperature is 130℃ and the aging time is 6h.

[0101] S15. The pre-aged coarse aluminum alloy wire blank is subjected to final cold deformation to produce fine aluminum alloy wire with a diameter of 2.8mm to 4.0mm.

[0102] S16. Finally, the aluminum alloy wire that has undergone final cooling deformation is subjected to final artificial aging treatment at 120°C for 2 hours, and then at 150°C for 6 hours to obtain sample 1-1.

[0103] Examples 1-2 to Examples 1-7

[0104] Examples 1-2 to 1-7 used the same preparation method as in Example 1-1, but with different amounts of feed, resulting in samples 1-2 to 1-7 with different compositions.

[0105] Example 2-1

[0106] The difference between this embodiment and Embodiment 1-1 is that this embodiment only uses one cold drawing process and one aging process. During the maximum deformation cold drawing process, fine aluminum alloy wires with a diameter of 2.8 mm to 4.0 mm are directly produced. Then, an aging treatment is performed at 120°C for 2 hours. Samples 2-1 with different compositions are obtained.

[0107] Example 2-2

[0108] The difference between this embodiment and Embodiment 1-1 is that the second aging treatment is a single-temperature aging treatment, which is performed at 140°C for 8 hours to obtain Sample 2-1.

[0109] Example 3-1

[0110] The difference between this embodiment and Embodiment 1-1 is that step S7 is omitted. Samples 3-1 with different compositions are obtained.

[0111] Example 3-2

[0112] The difference between this embodiment and Embodiment 1-1 is that excess aluminum-titanium master alloy ingots and aluminum-boron master alloy ingots are added in steps S2 and S3 to make the Ti content in the aluminum alloy liquid 0.016wt% and the B content 0.011wt%; and step S7 is omitted. Samples 3-2 with different compositions are obtained.

[0113] Performance testing:

[0114] The conductivity, elongation, and tensile strength of the aluminum alloy wires provided in Examples 1-1 to 1-7, Example 2, and Example 3 were tested, and their chemical composition and test results are shown in the table below.

[0115]

[0116] discuss:

[0117] Comparing Examples 1-1 to 1-7, the aluminum alloy wire in Example 1-1 exhibits the best overall performance. Example 1-2, while maintaining the Mg and Si content and their ratio essentially unchanged, appropriately increased the Fe content, thereby improving the tensile strength and elongation of the aluminum alloy wire, resulting in the best strength performance. Example 1-3, by increasing the Y content and the amount of refining agent, reduced the Ti and Cr+Mn+V content, improving the conductivity of the aluminum alloy wire, resulting in the best conductivity performance. Example 1-4 finely adjusted the Mg and Si content... The incorrect ratio between these parameters actually led to a decrease in the tensile strength, elongation, and conductivity of the aluminum alloy wire, resulting in the worst strength performance. Examples 1-5 showed that increasing the Fe and Sc content improved the tensile strength of the aluminum alloy wire, resulting in the best tensile strength. Examples 1-6 showed that decreasing the Sc content improved the elongation of the aluminum alloy wire, resulting in the best elongation. Examples 1-7 showed that increasing the amount of refining agent and increasing the Y content improved the tensile strength and conductivity of the aluminum alloy wire, resulting in the best tensile strength and conductivity.

[0118] Comparing Examples 1-1, 2-1, and 2-2, Example 1-1 employed multiple cold drawing and aging treatments, Example 2-1 employed only one cold drawing and one aging treatment, and the second aging treatment in Example 2-2 was a single-temperature aging treatment. Comparing the experimental results, it can be seen that although the aluminum alloy wire sacrifices some minor performance after multiple aging and multi-stage aging, it can greatly improve the overall conductivity.

[0119] Comparing Examples 1-1, 31, and 3-2, Example 3-1 omits the step of adding a grain refiner, Example 3-2 omits the step of adding a grain refiner, and ensures that the Ti and B contents are basically the same as those in Example 1-1. The comparative experimental results show that the addition of a grain refiner can improve the elongation and conductivity of aluminum alloy wires.

[0120] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

Claims

1. A method for preparing a high-conductivity, medium-strength aluminum alloy wire, characterized in that, Includes the following steps: S1. Smelting: Melting aluminum ingots and pouring them into a holding furnace; S2, nucleation regulation: First, add aluminum-titanium master alloy ingots to increase the number of active anisotropic nuclei; S3. Boring treatment: Add aluminum-boron master alloy ingots and perform boronizing treatment; S4. Composition Control: Aluminum-copper master alloy ingots, aluminum-iron master alloy ingots, aluminum-silicon master alloy ingots, aluminum-yttrium master alloy ingots, aluminum-scandium master alloy ingots, and magnesium ingots are added sequentially to prepare an aluminum alloy liquid; the aluminum alloy liquid is stirred using an electromagnetic automatic stirrer; the chemical composition of the aluminum alloy liquid, by weight percentage, includes the following components: Mg 0.40–0.48 wt%, Si 0.35~0.43wt%, Cu 0.01~0.05wt%, Fe 0.10~0.18wt%, Sc 0.05~0.15wt%, Y0.15~0.30wt%, (Cr+Mn+V+Ti)≤0.005wt%; S5. Multi-stage purification: After stirring, add high-efficiency sodium-free refining agent and covering agent to the heat preservation furnace; S6. Multi-stage degassing: Two-stage degassing is performed on the molten aluminum alloy before casting; S7. Grain refinement: Grain refinement is achieved by adding a grain refiner to the molten aluminum alloy. S8. Continuous casting: Aluminum alloy ingots are obtained by continuous casting using a horizontal flat surface casting method. S9. Solution treatment: The aluminum alloy billet is subjected to continuous solution treatment; an induction heating device is used for heating, and the solution treatment temperature of the aluminum alloy billet is 530℃~550℃. S10. Continuous Rolling: The aluminum alloy ingot is rolled into an aluminum alloy rod. Continuous rolling employs 4 sets of large deformation rolling mills and 10 sets of hot finishing mills. The concentration of the cooling emulsion used in rolling is 8–12%, and the pH value is 7–9. During rolling, the emulsion temperature is 45–50℃, and the emulsion pressure is 200 kPa. The resulting aluminum alloy rod has a dimension of 9.5 ± 0.1 mm, and its resistivity is no greater than 0.0320 Ω·mm within 4 hours. 2 / m, tensile strength 150-170MPa within 4 hours, elongation 7-15%; S11, Quenching: The aluminum alloy rod is subjected to continuous quenching treatment; S12, Natural Aging: The aluminum alloy rod is placed indoors for natural aging; the natural aging process is as follows: the aluminum alloy rod is placed in an environment with a temperature of 10℃~30℃ for 168h~192h. S13. Large Deformation Cold Drawing Treatment: The aluminum alloy rod is subjected to large deformation cold drawing treatment to produce a coarse aluminum alloy wire blank; the process of large deformation cold drawing treatment is to perform large deformation cold drawing treatment on the aluminum alloy rod by 60% to 90% to produce a coarse aluminum alloy wire blank with a diameter of 5mm to 6mm. S14. First aging treatment: The coarse aluminum alloy wire rod is subjected to pre-aging treatment; the parameters for the first aging treatment are: aging temperature of 120℃~140℃, aging time of 2h~8h; S15. Fine machining: The pre-aged coarse aluminum alloy wire blank is subjected to final cold deformation; the first-aged coarse aluminum alloy wire blank is drawn into fine aluminum alloy wire with a diameter of 2.8mm to 4.0mm. S16. Second aging treatment: The aluminum alloy wire that has undergone final cold deformation will undergo final artificial aging treatment; the second aging treatment adopts a two-stage aging method, which is to treat at 120℃ for 2 hours and then at 150℃ for 6 hours.

2. The method for preparing high conductivity medium-strength aluminum alloy wire according to claim 1, characterized in that, In step S2, after adding the aluminum-titanium master alloy ingot, the Ti content in the aluminum alloy liquid is 0.01-0.02 wt%. In step S3, after boronizing, the total content of Cr, Mn, V, and Ti in the aluminum alloy liquid does not exceed 0.005 wt%.

3. The method for preparing high conductivity medium-strength aluminum alloy wire according to claim 1, characterized in that, In step S4, the temperature of the molten aluminum alloy in the heat preservation furnace is 720-730°C.

4. The method for preparing high conductivity medium-strength aluminum alloy wire according to claim 1, characterized in that, In step S5, the multi-stage purification step includes the following method: High-efficiency sodium-free refining agent was blown into the molten aluminum alloy in the furnace from left to right and from front to back along with N2. The blowing temperature was 710-735℃ and the refining time was 10-15 minutes. After the first stage of refining, the slag on the surface of the aluminum alloy liquid is removed; then, the aluminum alloy liquid in the furnace is blown in with high-efficiency sodium-free refining agent from left to right and from front to back with N2, the blowing temperature is 710-735℃, and the refining time is 10-15 minutes. After the secondary refining is completed, the slag on the surface of the aluminum alloy liquid is removed, and then a covering agent is evenly sprayed onto the surface of the aluminum alloy liquid in the furnace. The highly efficient sodium-free refining agent is one of MgCl2, KCl, CaF2, KALF4, K2CO3, and MgCO3; The weight ratio of the high-efficiency sodium-free refining agent added to the molten aluminum alloy is 2.0:1000. The covering agent includes MgCl2, KCl, and CaF2; The weight ratio of the covering agent to the molten aluminum alloy is 1.0:1000.

5. The method for preparing high conductivity medium-strength aluminum alloy wire according to claim 1, characterized in that, In step S6, an online impurity removal system is used for degassing and filtration, the online impurity removal system including a degassing device and a filtration device; The degassing device uses 99.99% high-purity N2 to blow in at a flow rate of 40-50 mL / min and a temperature of 750℃. The filtration device adopts a double-layer ceramic structure, and the hydrogen content of the aluminum alloy liquid after filtration is no more than 0.100mL / 100g.

6. The method for preparing high conductivity medium-strength aluminum alloy wire according to claim 1, characterized in that, In step S7, 5Ti1B grain refiner is added at the inlet of the online impurity removal system at a rate of 0.2% to 0.25% of the aluminum alloy liquid mass, so that the Ti content in the aluminum alloy liquid is 0.01 to 0.02 wt% and the B content is 0.01 to 0.02 wt%.

7. The method for preparing high conductivity medium-strength aluminum alloy wire according to claim 1, characterized in that, In step S8, the aluminum liquid casting temperature is 690℃~720℃.

8. A high-conductivity, medium-strength aluminum alloy wire obtained by the preparation method according to any one of claims 1 to 7, characterized in that, Its chemical composition, by weight percentage, includes the following components: Mg 0.40–0.48 wt%, Si 0.35–0.43 wt%, Cu 0.01–0.05 wt%, Fe 0.10–0.18 wt%, B 0.01–0.02 wt%, Ti 0.01–0.02 wt%, Sc 0.05–0.15 wt%, Y 0.15–0.30 wt%, with the balance being Al and other unavoidable impurities, including Cr, Mn, and V, wherein (Cr+Mn+V) ≤ 0.005 wt%.

9. The high conductivity medium-strength aluminum alloy wire according to claim 8, characterized in that, The aluminum alloy wire has a diameter of 2.8 mm to 4.0 mm, a conductivity of ≥60.5% IACS, a tensile strength of ≥245 MPa, and an elongation of ≥4%.

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