Preparation method of super-heat-resistant aluminum alloy electrical pole and single wire

Abstract

The invention discloses a preparation method of a super-heat-resistant aluminum alloy electrical pole and a super-heat-resistant aluminum alloy electrical line, which comprises the following steps: controlling the components of an aluminum ingot, heating for melting, preserving heat, adding an AlB intermediate alloy for refining, heating after the components reach the standard, adding composite zirconium salt for treatment, casting at 750-790 DEG C to obtain an aluminum blank, rolling, and carrying out heat treatment at 450-520 DEG C to obtain the super-heat-resistant aluminum alloy electrical pole. And carrying out cold drawing to obtain the super-heat-resistant aluminum alloy single wire. According to the composition formula, the alloy contains 0.85 wt%-1.15 wt% of Zr and 0.10 wt%-0.14 wt% of B, rare earth elements are not contained, through synergistic strengthening of Al3Zr and ZrB2, the product is excellent in heat resistance, electrical conductivity and mechanical property, meets the national standard and is superior to existing products, the process is simple, the cost is low, and large-scale production is facilitated.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy electrical poles and single wires, specifically to a method for preparing a heat-resistant aluminum alloy electrical pole and single wire. Background Technology

[0002] In the field of power transmission, the performance of conductor materials directly affects transmission efficiency, safety and stability, and construction costs. With the continuous advancement of the State Grid construction, higher requirements are being placed on the high-temperature resistance, conductivity, and mechanical strength of conductors. High-temperature resistant aluminum alloys, with their excellent high-temperature mechanical properties, allow conductors to operate stably at 230℃ for extended periods, with an allowable operating temperature of up to 310℃ over 400 hours. Compared to ultra-high-temperature resistant aluminum alloys, which can only operate at 230℃ for extended periods, this significantly increases transmission capacity and reduces transmission losses, demonstrating broad application potential in high-voltage and ultra-high-voltage transmission lines.

[0003] However, the production technology for ultra-heat resistant aluminum alloy materials is currently imperfect, with only a few laboratories and enterprises capable of production. Furthermore, the production process is generally complex, making mass production difficult. According to the national standard GB / T30551-2014 "Heat-resistant Aluminum Alloy Wire for Overhead Stranded Cables," ultra-heat resistant aluminum alloy wire (NRLH4) must meet the following performance requirements: conductivity ≥58.0% IACS, heat resistance ≥90% after holding at 400℃ for 1 hour, and tensile strength ≥159MPa. Existing conventional high-heat resistant aluminum alloy wires still have many shortcomings in terms of production technology and economics: Patent CN119407177A provides a technology for obtaining aluminum rods by static pressing of ultrafine pure aluminum powder followed by sintering and extrusion. This method has a long production process and complex technology, and the weight of a single aluminum rod produced is limited, making continuous production difficult. More importantly, its product conductivity is only 50.3-53.5% IACS, far below the industry's practical requirements; Patent CN118455302A discloses a method for producing high-heat resistant aluminum alloy wires by continuous casting and extrusion. Due to the extrusion roller speed being only 8-15 rpm, the production output is extremely low and cannot meet the needs of large-scale industrial production; Patent CN115595474A uses a continuous casting and rolling process to produce high-heat resistant aluminum alloys, but adds 0.07-0.12% Sc element to the composition. Since Sc element is expensive, and high-heat resistant aluminum alloy wires are widely used in the national power grid infrastructure construction, the large-scale use of expensive rare earth elements will significantly increase production costs, resulting in poor economic efficiency.

[0004] Furthermore, in existing technologies, when zirconium (Zr) and boron (B) are added simultaneously during the batching process in the holding furnace of traditional continuous casting and rolling production, they readily undergo a rapid chemical reaction, forming precipitates that settle and are ultimately removed as waste. This prevents Zr and B from maintaining a uniform distribution in the molten aluminum through subsequent processes such as settling and trough transport, making it difficult for them to be effectively incorporated into the material system as alloying elements. This not only wastes alloying elements but also fails to leverage the synergistic effect of these two elements to improve the heat resistance and electrical conductivity of the aluminum alloy, severely restricting the mass production feasibility of high-heat-resistant aluminum alloy materials in continuous casting and rolling processes.

[0005] In summary, as the product with the highest technical specifications among heat-resistant aluminum alloys, the existing research and production processes of extra-heat-resistant aluminum alloys have several significant limitations: the production process is complex and inefficient, making it difficult to achieve rapid mass production in factories (e.g., some processes have low output and cannot be continuously produced); some technologies suffer from poor economic efficiency due to the addition of expensive elements such as Sc, making them unsuitable for the large-scale infrastructure construction needs of the State Grid; more importantly, in the traditional continuous casting and rolling process, Zr and B elements easily react and precipitate into waste slag, failing to function as effective alloying elements to play a synergistic role, resulting in material performance that is difficult to meet standards, and even the single-wire conductivity of aluminum alloys produced by some processes cannot reach 59% IACS. These problems collectively restrict the promotion and application of extra-heat-resistant aluminum alloys in the power industry. Therefore, developing a production technology for extra-heat-resistant aluminum alloy materials that can achieve low-cost, mass production and meet performance standards using existing mature equipment has become a key issue that urgently needs to be solved in this field. Summary of the Invention

[0006] To address the above technical problems, the purpose of this invention is to provide a method for preparing a high-heat-resistant aluminum alloy electrical pole and single wire. Through process design and composition optimization, this method overcomes the technical bottleneck of the difficulty in the synergistic effect of Zr and B elements in the traditional continuous casting and rolling process, thereby achieving low-cost and large-scale production of high-heat-resistant aluminum alloys.

[0007] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0008] The first aspect of this invention provides a method for preparing a heat-resistant aluminum alloy electrical pole, comprising the following steps:

[0009] S1. Heat the aluminum ingots to melt them into molten aluminum, and hold the temperature at 760-800℃;

[0010] S2. After analyzing the composition of the aluminum melt obtained in S1, add AlB master alloy, and refine it at 720-740℃ by blowing in refining agent with gas. After standing, remove the slag.

[0011] S3: Perform composition analysis on the aluminum melt obtained in S2. If the composition meets the following requirements: Si≤0.05wt%, Fe≤0.12wt%, B:0.10-0.14wt%, Cr+Mn+V+Ti≤0.001wt%, then increase the temperature of the aluminum melt to 780-840℃. Otherwise, repeat S2 until the composition meets the requirements.

[0012] S4. Add composite zirconium salt to the aluminum melt obtained in S3 and stir evenly, then degas and filter; the composite zirconium salt is a potassium fluorozirconate type additive, the main components of which include 88-94wt% KZrF5 and 6-12wt% KCl.

[0013] S5. Perform composition analysis on the aluminum melt obtained in S4. When the composition meets the following conditions: Si≤0.05wt%, Fe≤0.12wt%, Zr:0.85-1.15wt%, B:0.10-0.14wt%, Cr+Mn+V+Ti≤0.001wt%, unavoidable impurities≤0.08wt%, and the remainder is Al, cast the aluminum melt at 750-790℃ to obtain aluminum billet.

[0014] S6. Roll the aluminum billet obtained in S5 to obtain... Aluminum alloy rod;

[0015] S7. The aluminum alloy rod obtained in S6 is heat-treated at 450-520℃ for 30-80 hours to obtain the special heat-resistant aluminum alloy electrical rod.

[0016] This invention provides a compositional formula for a high-heat-resistant aluminum alloy material, comprising: Si ≤ 0.05 wt%, Fe ≤ 0.12 wt%, Zr 0.85-1.15 wt%, B 0.10-0.14 wt%, Cr+Mn+V+Ti ≤ 0.001 wt%, with the remainder being Al and unavoidable impurities (≤ 0.08 wt%). The core innovation of this formula lies in the precise control of the Zr to B ratio, ensuring the effective formation of the ZrB2 phase while avoiding the decrease in conductivity caused by excessive Zr. Simultaneously, it strictly limits the total amount of impurity elements such as Cr and Mn, eliminating their adverse effects on heat resistance and conductivity at the source. This invention achieves the superior performance of high-heat-resistant aluminum alloy materials simply by adding Zr and B, without introducing expensive rare earth elements. This simplifies the operation process, significantly reduces production costs, and facilitates large-scale mass production, providing an economically feasible technical path for the industrial promotion of high-heat-resistant aluminum alloy materials.

[0017] Furthermore, in S1, the aluminum ingot is a remelted aluminum ingot with a concentration of 99% or higher, wherein Si ≤ 0.05 wt% and Fe ≤ 0.12 wt%. Exceeding the specified Si and Fe content will form coarse Al-Si and Al-Fe intermetallic compounds, significantly reducing the conductivity and plasticity of the material. Therefore, strictly controlling the content of both is fundamental to ensuring the final performance.

[0018] In a specific embodiment, in S1, 99.7% remelted aluminum ingots with Si ≤ 0.05 wt% and Fe ≤ 0.12 wt% are used. These ingots are heated and melted in a vertical shaft furnace, and the resulting molten aluminum is then transferred to a holding furnace and held at 760-800°C. This temperature range ensures complete melting of the aluminum ingot while preventing excessively high temperatures from causing accelerated oxidation of the molten aluminum or uncontrolled volatilization of low-melting-point impurities, thus laying a stable foundation for subsequent composition control.

[0019] This invention has significant economic and environmental advantages in raw material selection and process design. The formula contains fewer types of elements and has low requirements for the purity of aluminum ingots. It only requires ordinary 99.7% remelted aluminum ingots with Si≤0.05wt% and Fe≤0.12wt% to meet production requirements, without relying on high-purity aluminum ingots of 99.85% or higher, which greatly reduces raw material costs. At the same time, the raw material adaptability is wider, and even pure aluminum waste (especially 1A60 waste commonly found in the field of electrical round aluminum rods) can be included in the raw material system. This not only improves resource utilization and reduces the environmental burden caused by waste disposal, but also helps to reduce carbon emissions in the production process.

[0020] Furthermore, in S2, the AlB master alloy is an AlB10 master alloy, with 10-20 kg of AlB10 master alloy added to each ton of molten aluminum. Too little addition will result in insufficient B content, preventing the formation of enough ZrB2 phase; too much addition may lead to an excess of B, resulting in an excessive amount of ZrB2 phase and insufficient Al3Zr phase. Furthermore, the formation of brittle AlB2 will conversely impair material properties.

[0021] The amount of AlB master alloy added is dynamically adjusted according to the content of V and Ti in the aluminum melt. This is because V and Ti will preferentially react with B to form high-melting-point VB2 and TiB2, consuming some of the B element. Dynamic adjustment can ensure that the effective content of the B element in the final aluminum melt is stable within the design range.

[0022] Furthermore, in S2, the gas is a mixture of nitrogen and argon, and the volume ratio of nitrogen to argon is 1:1.

[0023] Furthermore, in S2, the refining agent is a semi-granular refining agent. The main components of the semi-granular refining agent include chlorides and fluorides, wherein the chlorides include sodium chloride, potassium chloride, etc., and the fluorides include sodium fluoride, potassium fluoride, calcium fluoride, etc. Chlorides can effectively remove hydrogen from the aluminum melt, while fluorides can form low-melting-point fluoride inclusions with metallic impurities. The two work synergistically to improve the refining effect.

[0024] Furthermore, the semi-granular refining agent is composed of granules and powder, wherein the granules account for 40-60% and have a size of 1-3 mm; the powder accounts for 40-60% and has a size of less than 0.5 mm.

[0025] Furthermore, in S2, the refining time is 20-40 minutes. If the time is too short, the refining will be insufficient; if it is too long, it will increase the heat loss and oxidation risk of the molten aluminum.

[0026] Furthermore, in S2, the settling time is 40-60 minutes.

[0027] In a specific implementation, in step S2, the chemical composition of the aluminum melt obtained in step S1 is analyzed. An AlB10 master alloy is added at a ratio of 10-20 kg per ton of aluminum melt, and this amount is dynamically adjusted based on the V and Ti content in the aluminum melt. A mixture of 50% nitrogen and 50% argon is blown into the aluminum melt using a fully automated refining vehicle, and a semi-granular refining agent is added for refining. The refining time is 20-40 minutes, and the refining temperature is 720-740℃. After refining, the mixture is allowed to stand for 40-60 minutes, and then the aluminum slag is removed.

[0028] The refining temperature is lower than the holding temperature of S1, which can reduce the burn-off of B element in AlB master alloy, and at the same time avoid excessive reaction between refining agent and aluminum melt at high temperature, resulting in too many inclusions.

[0029] S3 raises the temperature to 780-840℃ to create high-temperature conditions for the subsequent dissolution of the composite zirconium salt and the uniform solid solution of Zr, providing temperature assurance for high-temperature casting. Too low a temperature will lead to insufficient dissolution of the composite zirconium salt, while too high a temperature may cause overheating and loss of the aluminum melt.

[0030] Furthermore, in S4, the effective component of Zr element in the composite zirconium salt accounts for 38-42 wt%.

[0031] Furthermore, in S4, the amount of composite zirconium salt added is 1.2-2.4 kg / min, and is dynamically adjusted according to the casting speed.

[0032] Furthermore, in S4, the stirring speed is 50-400 rpm.

[0033] In a specific implementation, in step S4, the holding furnace is raised, and the molten aluminum is poured into the flow channel, flowing sequentially through the mixing box (nitrogen protection), the degassing box, and the ceramic filter plate filter box, where the composite zirconium salt is added online and stirred evenly, and the online degassing and slag removal processes are carried out accordingly.

[0034] This invention employs a special process of online addition of composite zirconium salt, which enables the effective introduction of Zr and B elements simultaneously during the preparation of electrical round aluminum rods. This overcomes the technical limitation of traditional processes where Zr and B tend to react and precipitate prematurely when added in a heat-insulating furnace. The resulting product contains uniformly formed Al3Zr and ZrB2 reinforcing phases. Through the synergistic effect of these two phases, the heat resistance of the material is significantly improved, solving the technical problem that Zr and B tend to react and precipitate in traditional processes, thus failing to exert a synergistic reinforcing effect.

[0035] Furthermore, in S5, the casting speed is 4-5 t / h, and the billet temperature is 480-520℃.

[0036] This invention employs a high-temperature casting process, controlling the casting temperature between 750-790℃. This temperature range effectively reduces the premature formation of precipitates such as Al3Zr and ZrB2 at low temperatures, ensuring that Zr and B elements are fully dissolved in the aluminum matrix. Temperatures below 750℃ lead to premature precipitation of Zr and B elements, forming coarse inclusions, while temperatures above 790℃ may result in excessive overheating and coarse grains in the cast billet. Subsequent high-temperature heat treatment promotes the full precipitation of these elements, significantly improving the heat resistance of the material by forming a uniformly dispersed strengthening phase, thereby achieving precise control over the high-temperature stability of the high-temperature resistant aluminum alloy.

[0037] When the heat treatment temperature in S6 is below 450℃, Zr is difficult to fully precipitate from the aluminum matrix to form the Al3Zr phase, while above 520℃, the precipitated strengthening phase may coarsen.

[0038] The second aspect of the present invention provides a heat-resistant aluminum alloy electrical pole prepared by the preparation method described in the first aspect.

[0039] The third aspect of the present invention provides a method for preparing a heat-resistant aluminum alloy single wire, comprising the following steps: cold drawing the heat-resistant aluminum alloy electrical pole described in the second aspect to obtain the heat-resistant aluminum alloy single wire.

[0040] Furthermore, after 8-16 passes of cold drawing, the desired product is obtained. This is a high-temperature resistant aluminum alloy single-wire. Too few passes will result in excessive deformation per pass, easily causing wire breakage; too many passes will increase processing costs. The size range can meet the diverse needs of different transmission lines for conductor diameter.

[0041] The beneficial effects of this invention are:

[0042] 1. This invention achieves the simultaneous introduction of Zr and B elements into aluminum alloys by adding composite zirconium salts before casting. This allows Al3Zr and ZrB2 phases to form and exist stably within the aluminum alloy matrix simultaneously. The synergistic effect of these two phases significantly improves the heat resistance of the aluminum alloy. The composition design has a clear performance-oriented characteristic. Zr element can inhibit the recrystallization and growth of crystal structures to improve the heat resistance of the material. At the same time, Zr element dissolved in the aluminum matrix has a significant negative impact on resistivity. Therefore, this invention uses a heat treatment process to convert Zr element into precipitated Al3Zr, thereby improving the conductivity of the material. The ZrB2 phase formed by the combination of Zr and B elements has high melting point, high hardness, and good conductivity. As a reinforcing phase dispersed in the aluminum matrix, it can further improve the heat resistance and mechanical properties of the material.

[0043] 2. The aluminum alloy of the present invention has a simple composition, containing only two alloying elements, Zr and B, without the need to add rare earth elements or other components. Therefore, the heat treatment process can meet the performance requirements with a single-stage process, without the need to design a complex multi-stage heat treatment process for multiple elements. This not only reduces energy consumption but also simplifies the operation steps, significantly improves production efficiency, and is more suitable for the needs of large-scale industrial production.

[0044] 3. The heat-resistant aluminum alloy electrical pole prepared by this invention has a tensile strength of 120-150 MPa, an elongation of 14-20%, and a conductivity of 61-63% IACS. Furthermore, its heat resistance is 97.1-104.7% after being kept at 400℃ for 1 hour and 96.6-102.9% after being kept at 310℃ for 400 hours, demonstrating excellent mechanical properties, electrical conductivity, and high-temperature stability.

[0045] 4. The tensile strength of the ultra-heat resistant aluminum alloy single wire prepared by this invention is further improved to 180-220MPa, the elongation is 4-8%, the conductivity is maintained at 59-60.5% IACS, the heat resistance after holding at 400℃ for 1 hour reaches 95.2-99.7%, and the heat resistance after holding at 310℃ for 400 hours reaches 95-98.3%. It not only meets the performance requirements of ultra-heat resistant aluminum alloy wire in the national standard GB / T 30551-2014, but also outperforms existing ordinary ultra-heat resistant aluminum alloy products in key indicators such as strength and heat resistance. It can meet the stringent requirements of high-voltage and ultra-high-voltage transmission lines for the high-temperature mechanical properties and conductivity of materials. Detailed Implementation

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0047] The present invention will be further described below with reference to specific embodiments, so that those skilled in the art can better understand and implement the present invention, but the embodiments are not intended to limit the present invention.

[0048] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are commercially available.

[0049] In the following examples and comparative examples, the main components of the semi-granular refining agent are chlorides (sodium chloride, potassium chloride, etc.) and fluorides (sodium fluoride, potassium fluoride, calcium fluoride, etc.), of which approximately 50% are granules of 1-3 mm and approximately 50% are powders smaller than 0.5 mm. In the following examples and comparative examples, tensile strength and elongation at break were tested according to national standard GB / T 4909.3, resistivity was measured according to national standard GB / T 3048.2, and heat resistance was tested according to national standard GB / T 30551.

[0050] Example 1

[0051] A method for preparing a heat-resistant aluminum alloy electrical pole includes the following steps:

[0052] S1. 99.7% remelted aluminum ingots with Si: 0.04wt% and Fe: 0.11wt% are added to a vertical furnace for heating and melting, and then the molten aluminum is transferred to a holding furnace and held at 780℃.

[0053] S2. The chemical composition of the aluminum melt obtained in S1 was analyzed. AlB10 master alloy was added at a ratio of 12 kg per ton of aluminum melt. Then, a mixture of 50% nitrogen and 50% argon was blown into the aluminum melt using a fully automated refining machine, along with a semi-granular refining agent. The refining process lasted 30 minutes at a temperature of 725℃. After refining, the mixture was allowed to stand for 45 minutes, after which the aluminum slag was removed.

[0054] S3: The composition of the aluminum melt obtained in S2 was analyzed: Si: 0.04wt%, Fe: 0.11wt%, B: 0.12wt%, Cr+Mn+V+Ti: 0.0008wt%. The temperature of the aluminum melt was increased to 800℃.

[0055] S4. Raise the holding furnace and pour the molten aluminum into the flow channel. The molten aluminum flows through the mixing box (nitrogen protection), degassing box and ceramic filter box in sequence. Potassium fluorozirconate additive (main components include 91wt% KZrF5 and 9wt% KCl, with an addition rate of 2kg / min) is added online and stirred evenly. Online degassing and slag removal are also performed.

[0056] S5. The composition of the aluminum melt obtained in S4 was analyzed: Si: 0.04wt%, Fe: 0.11wt%, Zr: 0.99wt%, B: 0.12wt%, Cr+Mn+V+Ti: 0.0008wt%, unavoidable impurities: 0.08wt%, and the remainder being Al. The aluminum melt was continuously cast at 770℃ at a speed of 4.8t / h, and the billet temperature was 495℃ to obtain aluminum billets.

[0057] S6. Roll the aluminum billet obtained in S5 to obtain... Aluminum alloy rod;

[0058] S7. After air cooling the aluminum alloy rod obtained in S6 to room temperature, heat treatment is carried out at 485℃ and held for 50 hours to obtain a heat-resistant aluminum alloy electrical rod.

[0059] The heat-resistant aluminum alloy electrical pole prepared in Example 1 was tested and found to have a tensile strength of 128 MPa, an elongation of 18%, a conductivity of 61.2% IACS, a heat resistance of 98.6% after being kept at 400℃ for 1 hour, and a heat resistance of 97.2% after being kept at 310℃ for 400 hours.

[0060] Example 2

[0061] A method for preparing a high-heat-resistant aluminum alloy single wire includes the following steps:

[0062] The heat-resistant aluminum alloy electrical pole prepared in Example 1 was subjected to cold drawing treatment, and after 12 drawing passes, it was obtained... Highly heat-resistant aluminum alloy single wire.

[0063] The test results showed that the tensile strength of the heat-resistant aluminum alloy single wire prepared in Example 2 was 189 MPa, the elongation was 7%, the conductivity was 59.6% IACS, the heat resistance was 97.1% after holding at 400℃ for 1 h, and the heat resistance was 98.1% after holding at 310℃ for 400 h.

[0064] Example 3

[0065] A method for preparing a heat-resistant aluminum alloy electrical pole includes the following steps:

[0066] S1. 99.7% remelted aluminum ingots with Si: 0.03wt% and Fe: 0.07wt% are added to a vertical furnace for heating and melting, and then the molten aluminum is transferred to a holding furnace and held at 760℃.

[0067] S2. The chemical composition of the aluminum melt obtained in S1 was analyzed. AlB10 master alloy was added at a ratio of 10 kg per ton of aluminum melt. Then, a mixture of 50% nitrogen and 50% argon was blown into the aluminum melt using a fully automated refining machine, along with a semi-granular refining agent. The refining process lasted 20 minutes at a temperature of 720℃. After refining, the mixture was allowed to stand for 40 minutes, after which the aluminum slag was removed.

[0068] S3: The composition of the aluminum melt obtained in S2 was analyzed: Si: 0.03wt%, Fe: 0.07wt%, B: 0.10wt%, Cr+Mn+V+Ti: 0.0007wt%. The temperature of the aluminum melt was increased to 765℃.

[0069] S4. Raise the holding furnace and pour the molten aluminum into the flow channel. The molten aluminum flows through the mixing box (nitrogen protection), degassing box and ceramic filter box in sequence. Potassium fluorozirconate additive (main components include 91wt% KZrF5 and 9wt% KCl, with an addition amount of 1.51kg / min) is added online and stirred evenly. Online degassing and slag removal are also performed.

[0070] S5. The composition of the aluminum melt obtained in S4 was analyzed: Si: 0.03wt%, Fe: 0.07wt%, Zr: 0.85wt%, B: 0.10wt%, Cr+Mn+V+Ti: 0.0007wt%, unavoidable impurities: 0.07wt%, and the remainder being Al. The aluminum melt was continuously cast at 750℃ at a speed of 4t / h, and the billet temperature was 482℃ to obtain aluminum billets.

[0071] S6. Roll the aluminum billet obtained in S5 to obtain... Aluminum alloy rod;

[0072] S7. After air cooling the aluminum alloy rod obtained in S6 to room temperature, heat treatment is carried out at 450℃ and held for 80 hours to obtain a heat-resistant aluminum alloy electrical rod.

[0073] According to the test results, the high heat-resistant aluminum alloy electrician pole prepared in Example 3 has a tensile strength of 144 MPa, an elongation of 15%, a conductivity of 61.8% IACS, a heat resistance of 97.7% after being kept at 400℃ for 1 hour, and a heat resistance of 97.9% after being kept at 310℃ for 400 hours.

[0074] Example 4

[0075] A method for preparing a high-heat-resistant aluminum alloy single wire includes the following steps:

[0076] The heat-resistant aluminum alloy electrical pole prepared in Example 3 was subjected to cold drawing treatment, and obtained after 8 drawing passes. Highly heat-resistant aluminum alloy single wire.

[0077] The test results showed that the tensile strength of the heat-resistant aluminum alloy single wire prepared in Example 4 was 192 MPa, the elongation was 5%, the conductivity was 60.5% IACS, the heat resistance was 96.9% after holding at 400℃ for 1 hour, and the heat resistance was 97.2% after holding at 310℃ for 400 hours.

[0078] Example 5

[0079] A method for preparing a heat-resistant aluminum alloy electrical pole includes the following steps:

[0080] S1. 99.7% remelted aluminum ingots with Si: 0.04wt% and Fe: 0.10wt% and 1A60 scrap aluminum with Si: 0.04wt% and Fe: 0.12wt% are added to a vertical furnace for heating and melting. The molten aluminum is then transferred to a holding furnace and held at 800℃.

[0081] S2. The chemical composition of the aluminum melt obtained in S1 was analyzed. AlB10 master alloy was added at a ratio of 20 kg per ton of aluminum melt. Then, a mixture of 50% nitrogen and 50% argon was blown into the aluminum melt using a fully automated refining vehicle, along with a semi-granular refining agent. The refining process lasted 40 minutes at a temperature of 740℃. After refining, the mixture was allowed to stand for 60 minutes, after which the aluminum slag was removed.

[0082] S3: The composition of the aluminum melt obtained in S2 was analyzed: Si: 0.04wt%, Fe: 0.11wt%, B: 0.14wt%, Cr+Mn+V+Ti: 0.001wt%. The temperature of the aluminum melt was increased to 840℃.

[0083] S4. Raise the holding furnace and pour the molten aluminum into the flow channel. The molten aluminum flows through the mixing box (nitrogen protection), degassing box and ceramic filter box in sequence. Potassium fluorozirconate additive (main components include 91wt% KZrF5 and 9wt% KCl, with an addition rate of 2.13kg / min) is added online and stirred evenly. Online degassing and slag removal are also performed.

[0084] S5. The composition of the aluminum melt obtained in S4 was analyzed: Si: 0.04wt%, Fe: 0.11wt%, Zr: 1.12wt%, B: 0.14wt%, Cr+Mn+V+Ti: 0.001wt%, unavoidable impurities: 0.08wt%, and the remainder was Al. The aluminum melt was continuously cast at 790℃ at a speed of 4.5t / h, and the billet temperature was 513℃ to obtain aluminum billet.

[0085] S6. Roll the aluminum billet obtained in S5 to obtain... Aluminum alloy rod;

[0086] S7. After air cooling the aluminum alloy rod obtained in S6 to room temperature, heat treatment is carried out at 520℃ and held for 40 hours to obtain a heat-resistant aluminum alloy electrical rod.

[0087] According to the test results, the high heat-resistant aluminum alloy electrician pole prepared in Example 5 has a tensile strength of 134 MPa, an elongation of 14%, a conductivity of 61.0% IACS, a heat resistance of 104.7% after being kept at 400℃ for 1 hour, and a heat resistance of 102.9% after being kept at 310℃ for 400 hours.

[0088] Example 6

[0089] A method for preparing a high-heat-resistant aluminum alloy single wire includes the following steps:

[0090] The heat-resistant aluminum alloy electrical pole prepared in Example 5 was subjected to cold drawing treatment, and after 16 drawing passes, it was obtained... Highly heat-resistant aluminum alloy single wire.

[0091] The test results showed that the tensile strength of the heat-resistant aluminum alloy single wire prepared in Example 6 was 220 MPa, the elongation was 4%, the conductivity was 59.5% IACS, the heat resistance was 99.7% after holding at 400℃ for 1 h, and the heat resistance was 97.2% after holding at 310℃ for 400 h.

[0092] Comparative Example 1

[0093] A method for preparing an aluminum alloy single wire is basically the same as that in Example 2, except that potassium fluorozirconate type additives are not added in S4 of the preparation of the heat-resistant aluminum alloy electrician pole in Example 1.

[0094] The aluminum alloy single wire prepared in Comparative Example 1 was tested and found to have a tensile strength of 152 MPa, an elongation of 5.4%, an electrical conductivity of 63.3% IACS, and a heat resistance of 81% after being kept at 400℃ for 1 hour.

[0095] Zr is the core element responsible for the excellent heat resistance of high-temperature resistant aluminum alloy wire materials. Without Zr, the material's heat resistance would significantly deteriorate. Its mechanism lies in the fact that Zr can form the Al3Zr phase in the aluminum matrix. After specific heat treatment, this phase, in a dispersed precipitation form, anchors itself at the grain boundaries, effectively hindering abnormal grain growth and dislocation migration at high temperatures, thereby simultaneously improving the material's heat resistance and tensile strength. The comparative example, where only the ZrB2 phase is formed without the simultaneous formation of the Al3Zr phase, further confirms the necessity of the synergistic effect of the two phases: when only the ZrB2 phase is present, the heat resistance of the aluminum single wire after holding at 400℃ for 1 hour is only 81%, far lower than the over 95% heat resistance index achieved when both Al3Zr and ZrB2 are present in this invention. This is because although the ZrB2 phase alone can improve certain mechanical properties through dispersion strengthening, it cannot effectively pin grain boundaries to inhibit grain growth at high temperatures like the Al3Zr phase. The synergistic effect of Al3Zr and ZrB2 can stabilize the crystal structure with the pinning effect of Al3Zr and improve the overall mechanical properties through the strengthening effect of ZrB2. Both are indispensable and together constitute the core guarantee of the excellent heat resistance of the special heat-resistant aluminum alloy.

[0096] Comparative Example 2

[0097] A method for preparing an aluminum alloy single wire is basically the same as that in Example 2, except that AlB10 intermediate alloy is not added in S2 of the preparation of the heat-resistant aluminum alloy electrician pole in Example 1.

[0098] The aluminum alloy single wire prepared in Comparative Example 2 was tested and found to have a tensile strength of 185 MPa, an elongation of 5.2%, an electrical conductivity of 60.2% IACS, and a heat resistance of 88% after being kept at 400℃ for 1 hour.

[0099] Without the addition of boron (B), the heat resistance of the material would also decrease significantly. The key role of boron is to combine with zirconium (Zr) to form the ZrB2 phase. While this phase is similar to the Al3Zr phase in possessing excellent high-temperature resistance, it is weaker than the Al3Zr phase in inhibiting high-temperature grain growth and dislocation migration. Experimental data show that when only the Al3Zr phase is present without the ZrB2 phase (i.e., no boron is added), the heat resistance of the aluminum single wire after holding at 400℃ for 1 hour is only 88%, lower than the over 95% achieved when both phases coexist in this invention.

[0100] Comparative Example 3

[0101] A method for preparing an aluminum alloy single wire is basically the same as that in Example 2, except that: in the preparation of the heat-resistant aluminum alloy electrical pole in Example 1, AlB10 master alloy and AlZr10 master alloy are added. Zr reacts with B, and after standing, aluminum melt that meets the composition requirements cannot be obtained.

[0102] If Zr and B alloys are added simultaneously in the holding furnace, after refining and settling processes, Zr and B will chemically react with the V element initially present in the aluminum ingot, generating insoluble intermetallic compounds (such as VB2, ZrV2, etc.). These compounds will precipitate as aluminum dross and be removed. This process not only leads to a significant loss of Zr and B elements due to their participation in the reaction, making it impossible to maintain the designed content in the aluminum melt, but also results in a high V content in the aluminum melt due to the difficulty in completely removing V elements. Ultimately, it is impossible to obtain a qualified aluminum melt with extremely low V content and rich in Zr and B elements, which deviates significantly from the composition standard required for production, causing subsequent processes to fail to meet the performance requirements of the special heat-resistant aluminum alloy.

[0103] Comparative Example 4

[0104] A method for preparing an aluminum alloy single wire is basically the same as that in Example 2, except that: in S2 of the preparation of the heat-resistant aluminum alloy electrician pole in Example 1, the AlB10 master alloy is replaced with the AlZr10 master alloy; in S4, the potassium fluorozirconate type additive is replaced with aluminum boron wire.

[0105] The aluminum alloy single wire prepared in Comparative Example 4 was tested and found to have a tensile strength of 198 MPa, an elongation of 4.4%, a conductivity of 57.8% IACS, and a heat resistance of 93% after being kept at 400℃ for 1 hour.

[0106] If the process of "adding only Zr alloy in the holding furnace and adding B alloy online before casting" is adopted, the electrical conductivity of the material will decrease significantly and will fail to meet production requirements. Specifically, without adding B element in the holding furnace, the boronizing treatment step is missing, resulting in a V element content in the aluminum melt ≥0.01wt%, far exceeding the standard of Cr+Mn+V+Ti total content ≤0.001wt% required by this invention. When B alloy is added online before casting, B element will preferentially react with the residual V element in the aluminum melt to form precipitates such as VB2 (forming a large amount of aluminum dross). At the same time, although the remaining B element can react with Zr, it is difficult to form a sufficient amount of ZrB2 phase according to the process design. In this case, not only will the excessive aluminum dross cause production to be unable to proceed continuously, but the insufficient effective strengthening phase (ZrB2) and excessive impurity elements (V) will ultimately cause a significant decrease in the electrical conductivity of the material, making it unable to meet the performance indicators of the special heat-resistant aluminum alloy.

[0107] Comparative Example 5

[0108] A method for preparing an aluminum alloy single wire is basically the same as that in Example 2, except that in S4 of the preparation of the heat-resistant aluminum alloy electrical pole in Example 1, potassium fluorozirconate type additive is directly added to the flow channel, and the aluminum melt and potassium fluorozirconate type additive are not stirred evenly.

[0109] According to the test, the tensile strength of the aluminum alloy single wire prepared in Comparative Example 5 was 121 MPa, the elongation was 2.8%, the conductivity was 56% IACS, and the heat resistance after holding at 400℃ for 1 hour was 85%.

[0110] Adding potassium fluorozirconate-type additives directly to the flow channel results in severely uneven Zr distribution in the aluminum melt, with Zr content fluctuating between 0.4-1.2 wt%, far exceeding the designed standard range of 0.85-1.15 wt%. Furthermore, this method prevents the potassium fluorozirconate additives from fully dissolving and dispersing in the aluminum melt, easily forming unreacted solid particles. This not only affects the purity of the aluminum melt but also causes frequent blockages and rod breaks in subsequent casting and rolling processes, ultimately disrupting continuous and stable production and making it difficult to produce high-heat-resistant aluminum alloy products with uniform performance.

[0111] Comparative Example 6

[0112] A method for preparing an aluminum alloy single wire is basically the same as that in Example 2, except that the casting temperature in S5 of Example 1 for preparing the extra heat-resistant aluminum alloy electrical pole is 720℃.

[0113] The aluminum alloy single wire prepared in Comparative Example 6 was tested and found to have a tensile strength of 175 MPa, an elongation of 4%, an electrical conductivity of 54.2% IACS, and a heat resistance of 82% after being kept at 400℃ for 1 hour.

[0114] If the conventional casting temperature of 720℃ for electrical round aluminum rods is used, it will significantly deviate from the process design requirements of this invention. At this temperature, Zr and B elements in the aluminum melt will precipitate prematurely before casting, forming coarse Al3Zr and ZrB2 phases, resulting in a significant reduction in the Zr and B content dissolved in the aluminum matrix. These prematurely precipitated phases cannot be re-dissolved and dispersed through subsequent heat treatment; instead, their coarse particles will lose their strengthening effect, making it impossible to optimize the microstructure of the material through heat treatment. Ultimately, this will result in key performance indicators such as heat resistance and strength failing to meet design requirements and thus failing to meet the standards for the use of high-heat-resistant aluminum alloys.

[0115] Comparative Example 7

[0116] A method for preparing an aluminum alloy single wire is basically the same as that in Example 2, except that: in S4 of the preparation of the extra heat-resistant aluminum alloy electrical pole in Example 1, the amount of potassium fluorozirconate additive is increased; in S5, the composition of the aluminum melt obtained in S4 is analyzed: Zr: 1.5wt%.

[0117] The aluminum alloy single wire prepared in Comparative Example 7 was tested and found to have a tensile strength of 240 MPa, an elongation of 3%, an electrical conductivity of 57.3% IACS, and a heat resistance of 94% after being kept at 400℃ for 1 hour.

[0118] If the Zr content is too high, exceeding the 0.85-1.15 wt% range designed in this invention, it will have a significant negative impact on the material properties: excessive Zr is difficult to completely transform into the precipitated Al3Zr phase through heat treatment, resulting in a large amount of solid-solution Zr remaining in the aluminum matrix. The adverse effect of solid-solution Zr on electrical conductivity is significant, which severely weakens the effect of heat treatment on improving electrical properties, and the material conductivity can only reach 57.3% IACS.

[0119] Comparative Example 8

[0120] A method for preparing an aluminum alloy single wire is basically the same as that in Example 2, except that: in S2 of the preparation of the extra heat-resistant aluminum alloy electrician rod in Example 1, the amount of AlB10 master alloy added is increased; in S3, the composition of the aluminum melt obtained in S2 is analyzed: B: 0.2wt%.

[0121] According to the test, the tensile strength of the aluminum alloy single wire prepared in Comparative Example 8 was 201 MPa, the elongation was 4%, the conductivity was 58.1% IACS, and the heat resistance after holding at 400℃ for 1 hour was 85%.

[0122] If the boron (B) content is too high, exceeding the designed range of 0.10-0.14 wt%, it will trigger excessive chemical reactions: excess B will preferentially combine with Zr to form a large amount of ZrB2 phase, leading to excessive consumption of Zr elements participating in the formation of Al3Zr phase, resulting in a significant reduction in the precipitation of Al3Zr phase. This change will have a dual negative impact: on the one hand, insufficient Al3Zr phase will weaken its pinning effect on grain boundaries, leading to a significant decrease in the material's heat resistance; on the other hand, the coarsening of the excess ZrB2 phase and residual impurities will increase electron scattering, causing a deterioration in conductivity. Ultimately, the material will lose both its excellent heat resistance and electrical conductivity, failing to meet the core performance requirements of high-heat-resistant aluminum alloys.

[0123] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art should understand that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a high-heat-resistant aluminum alloy electrician pole, characterized in that, Includes the following steps: S1. Heat the aluminum ingots to melt them into molten aluminum, and hold the temperature at 760-800℃; S2. After analyzing the composition of the aluminum melt obtained in S1, add AlB master alloy, and refine it at 720-740℃ by blowing in refining agent with gas. After standing, remove the slag. S3: Perform composition analysis on the aluminum melt obtained in S2. If the composition meets the following requirements: Si≤0.05wt%, Fe≤0.12wt%, B:0.10-0.14wt%, Cr+Mn+V+Ti≤0.001wt%, then increase the temperature of the aluminum melt to 780-840℃. Otherwise, repeat S2 until the composition meets the requirements. S4. Add composite zirconium salt to the aluminum melt obtained in S3 and stir evenly, then degas and filter; the composite zirconium salt is a potassium fluorozirconate type additive, the main components of which include 88-94wt% KZrF5 and 6-12wt% KCl. S5. Perform composition analysis on the aluminum melt obtained in S4. When the composition meets the following conditions: Si≤0.05wt%, Fe≤0.12wt%, Zr:0.85-1.15wt%, B:0.10-0.14wt%, Cr+Mn+V+Ti≤0.001wt%, unavoidable impurities≤0.08wt%, and the remainder is Al, then cast the aluminum melt at 750-790℃ to obtain aluminum billet. S6. Roll the aluminum billet obtained in S5 to obtain an aluminum alloy rod with a diameter of φ7.5mm-φ15mm; S7. The aluminum alloy rod obtained in S6 is heat-treated at 450-520℃ for 30-80 hours to obtain the special heat-resistant aluminum alloy electrical rod.

2. The preparation method according to claim 1, characterized in that, In S2, the AlB master alloy is AlB10 master alloy, and 10-20 kg of AlB10 master alloy is added to each ton of aluminum melt.

3. The preparation method according to claim 1, characterized in that, In S2, the refining agent is a semi-granular refining agent, and the main components of the semi-granular refining agent include chlorides and fluorides.

4. The preparation method according to claim 1, characterized in that, In S2, the refining time is 20-40 minutes.

5. The preparation method according to claim 1, characterized in that, In S2, the settling time is 40-60 minutes.

6. The preparation method according to claim 1, characterized in that, In S4, the amount of the composite zirconium salt added is 1.2-2.4 kg / min.

7. The preparation method according to claim 1, characterized in that, In S5, the casting speed is 4-5 t / h and the billet temperature is 480-520℃.

8. A heat-resistant aluminum alloy electrical pole obtained by the preparation method according to any one of claims 1-7.

9. A method for preparing a high-heat-resistant aluminum alloy single wire, characterized in that, The process includes the following steps: cold drawing the heat-resistant aluminum alloy electrical pole as described in claim 8 to obtain the heat-resistant aluminum alloy single wire.

10. The preparation method according to claim 9, characterized in that, After 8-16 cold drawing processes, a heat-resistant aluminum alloy single wire with a diameter of φ1.0mm-φ5.0mm is obtained.