High-conductivity high-strength heat-resistant aluminum alloy and preparation method thereof

Abstract

This invention discloses a high-conductivity, high-strength, and heat-resistant aluminum alloy and its preparation method, belonging to the technical field of overhead power transmission conductor materials. The chemical composition (wt.%) of the alloy is: Zr 0.08-0.15, Sc 0.03-0.08, Ti 0.02-0.05, Mg 0.50-0.70, Si 0.25-0.35, with the balance being Al and unavoidable impurities. By precisely controlling the Zr to Sc mass ratio to be 1.6-5.0, the Mg to Si mass ratio to be 1.5-4.0, and the total content ≥0.80%, a dual-phase synergistic strengthening structure of core-shell and shell phases is formed in the alloy matrix. The preparation process includes: vacuum melting, continuous casting and electromagnetic stirring homogenization, homogenization treatment, hot extrusion and cold working, medium-temperature short-time aging strengthening, and finished stranded wire; wherein, electromagnetic stirring inhibits elemental segregation, and medium-temperature short-time aging (holding at 380-400℃ for 8-12h) promotes the synergistic precipitation of nanoscale dual phases. The resulting alloy has a tensile strength ≥260MPa, electrical conductivity ≥58%IACS, recrystallization temperature ≥480℃, and a strength retention rate ≥90% after annealing at 230℃×1h. It also has low Sc content and low cost, making it suitable for continuous casting and rolling production.

Description

Technical Field

[0001] This invention relates to the field of overhead power transmission conductor materials, and in particular to a high-conductivity, high-strength, heat-resistant aluminum alloy and its preparation method. Background Technology

[0002] With the increasing demand for ultra-high voltage power grid construction and transmission line capacity expansion in my country, stringent technical requirements have been placed on heat-resistant aluminum alloy materials for overhead transmission conductors, demanding high strength (≥260MPa), high conductivity (≥58%IACS), high heat resistance (recrystallization temperature ≥480℃), and long service life (≥30 years). Especially under harsh conditions such as long-span crossings, heavy ice areas, and marine corrosion environments, conductors must maintain stable mechanical and electrical properties at long-term operating temperatures of 150-180℃, while also meeting the requirements of long-distance (single reel weight of several tons) and continuous industrial production.

[0003] Currently, the heat-resistant aluminum alloys used for overhead conductors both domestically and internationally are mainly based on the Al-Zr binary alloy system, which forms an L12 structure. Precipitated phases pin grain boundaries and inhibit dynamic recrystallization, achieving high-temperature creep resistance strengthening. However, the following technical bottlenecks exist in actual industrial production and engineering applications: 1. The diffusion rate of Zr in the α-Al matrix is ​​extremely low (only a fraction at 400℃). ),lead to The precipitation incubation period is as long as 50 hours or more. Traditional high-temperature long-time aging (above 450℃, more than 24 hours) or "offline intermittent" heat treatment processes are difficult to adapt to the continuous large-scale production mode of "continuous casting and rolling - high-speed wire drawing" in the wire industry. Moreover, the long cycle heat treatment leads to coarsening of the precipitated phase and low quantity density. However, this has limited effect on improving efficiency.

[0004] 2. During the rapid solidification process of horizontal continuous casting, Zr elements tend to segregate between dendrites, forming a "precipitate depletion zone (PFZ)" with a width of 10-20 μm. This macroscopic inhomogeneity can easily induce local stress concentration and microcracks during subsequent multi-pass drawing (total deformation rate 70-80%), significantly reducing the room temperature tensile properties and high-temperature creep and recrystallization resistance of the conductor, thus affecting the safe operation of long-distance transmission lines.

[0005] 3. Solid-solution Zr has a significant negative impact on the electrical conductivity of the aluminum matrix (each 0.01 at% Zr increases resistivity). The single Al-Zr strengthening system is difficult to overcome the inverted relationship between strength and conductivity. The tensile strength of traditional Al-Zr conductors is usually <220MPa and the conductivity is <56%IACS, which cannot meet the dual requirements of high current carrying capacity (reducing line loss) and high sag stability of UHV high-capacity power transmission conductors.

[0006] 4. Although the Al-Zr-Sc ternary system can utilize Core-shell structures improve thermal stability, but current technologies mostly use medium to high content ratios of Sc (≥0.1 wt%). Sc, as a rare earth element, is expensive (approximately 20-30 times that of Zr), resulting in raw material costs increasing by more than 50% compared to ordinary Al-Zr alloys. This severely restricts the large-scale application of high-performance heat-resistant aluminum alloy conductors in power grid projects.

[0007] 5. Existing technologies mostly rely on a single [technology / method / technology]. Mutually( or Heat resistance strengthening was carried out, but the potential of Mg-Si alloys was not fully utilized. The dispersion strengthening potential of the phase at grain boundaries / dislocations is limited. However, the lack of synergistic optimization of the Zr / Sc ratio, Mg / Si ratio, and aging regime makes it difficult to achieve this. Core-shell phase and The controlled synergistic precipitation of two phases limits the improvement of the alloy's overall properties (strength, electrical conductivity, heat resistance).

[0008] Therefore, there is an urgent need to develop a high-strength aluminum alloy material suitable for pre-twisted wires to overcome the defects mentioned above. Summary of the Invention

[0009] To overcome the above-mentioned technical defects, the present invention provides a high-conductivity, high-strength, heat-resistant aluminum alloy and its preparation method to solve the problems involved in the background art.

[0010] On one hand, the present invention provides a high-conductivity, high-strength, and heat-resistant aluminum alloy, comprising, by weight percentage: By weight percentage, it includes: Zr 0.08-0.15%, Sc 0.03-0.08%, Ti 0.02-0.05%, Mg 0.50-0.70%, Si 0.25-0.35%, Fe ≤0.15%, Cu ≤0.05%, other single impurities ≤0.03%, total impurities ≤0.1%, and the remainder is Al and unavoidable impurities; wherein, the mass ratio of Zr to Sc is 1.6-5.0, the mass ratio of Mg to Si is 1.5-4.0, and the total content of Mg and Si is ≥0.80%.

[0011] Preferably or optionally, by weight percentage, it includes: Zr 0.10-0.13%, Sc 0.04-0.06%, Ti 0.02-0.05%, Mg 0.55-0.65%, Si 0.28-0.32%, Fe ≤0.15%, Cu ≤0.05%, other single impurities ≤0.03%, total impurities ≤0.1%, and the balance being Al and unavoidable impurities.

[0012] Preferably or optionally, the alloy matrix contains dispersed distributions of... Composite phase and Phase, the described The composite phase has a core-shell structure, with Sc enriched in the core and Zr enriched in the shell. The phase is distributed at grain boundaries and dislocations.

[0013] Preferably or optionally, the The composite phase has a particle size of 12-15 nm and a number density of 12-15 nm. The Phase particle size ≤50nm, number density .

[0014] Preferably or optionally, the Zr content is 0.10-0.13% and the Sc content is 0.04-0.06% by mass percentage.

[0015] Preferably or optionally, the mass ratio of Zr to Sc is 2.0-3.0, the mass ratio of Mg to Si is 1.8-2.5, and the total content of Mg and Si is 0.85%-0.95%.

[0016] On the other hand, the present invention also provides a method for preparing a high-conductivity, high-strength, heat-resistant aluminum alloy, comprising: S1. Raw material preparation; S2, Vacuum Melting: S3. Continuous casting and electromagnetic stirring for homogenization: S4. Homogenization treatment; S5. Hot extrusion and cold working: Extruded into φ18mm aluminum rods at 400-450℃ with an extrusion ratio of 15-20:1; cold-worked in multiple passes to φ9.5mm, with a total deformation rate of 70-80%, during which intermediate annealing at 300℃×1h is performed. S6. Medium-temperature short-time aging enhancement: Heat to 380-400℃ at a heating rate of 5-10℃ / min, hold for 8-12 hours, and air cool to room temperature; S7. Finished stranded wire.

[0017] Preferably or optionally, the surface oxide layer of high-purity aluminum ingots, Al-Zr alloys, Al-Sc alloys, Al-Ti alloys, industrial pure Mg, and industrial pure Si is removed by dilute hydrofluoric acid, wherein the Zr content in the Al-Zr alloy is 10wt%, the Sc content in the Al-Sc alloy is 2wt%, and the Ti content in the Al-Ti alloy is 5wt%.

[0018] Preferably or optionally, high-purity aluminum ingots are placed in a vacuum induction melting furnace, vacuumed and heated to melting point; Al-Zr alloy, Al-Sc alloy, and Al-Ti alloy are added sequentially, stirred, and then Mg and Si raw materials are added, and stirring is continued; the furnace is allowed to stand to degas, and the oxygen content in the furnace is controlled to be ≤0.0015%, and the slag is removed. Preferably or optionally, in S3, a horizontal continuous casting machine is used, the casting temperature is 710-730℃, the cooling rate is 15-20℃ / s, the billet diameter is φ80mm, the electromagnetic stirring is turned on, the electromagnetic stirring frequency is 50Hz, the current intensity is 200-300A, and the billet grain size is ≤200μm. Preferably or optionally, in S4, the billet is heated to 480-520°C, held for 8-12 hours, cooled in the furnace to 300°C, and then air-cooled.

[0019] Preferably or optionally, in S7, the aged aluminum alloy wire is stranded with a galvanized steel core at a pitch ratio of 12-16 times to form a finished steel-cored aluminum stranded wire.

[0020] This invention relates to a high-conductivity, high-strength, and heat-resistant aluminum alloy and its preparation method, which has the following advantages compared to the prior art: 1. This invention utilizes " Core-shell structure heat-resistant phase + The dual-phase synergy of "dispersed strengthening phase" and the supplementation of Ti grain refinement and Mg-Si ratio control (Mg+Si≥0.8%) result in an alloy with tensile strength ≥260MPa, yield strength ≥240MPa, elongation ≥12%, electrical conductivity ≥58%IACS (20℃), recrystallization temperature ≥480℃, and strength retention rate ≥90% after annealing at 230℃×1h. This solves the problem of difficulty in achieving strength, electrical conductivity, and heat resistance in existing technologies.

[0021] 2. This invention controls the amount of Sc added to 0.03-0.08% and uses a precise Zr / Sc mass ratio of 1.6-5.0, utilizing Zr in... Enrichment of the shell reduces the demand for Sc cores while ensuring the number density of precipitated phases. Furthermore, raw material costs are kept within an acceptable range. Compared to high-Sc alloys such as Al-0.1Sc-0.1Zr(at.%), costs are reduced by more than 40%.

[0022] 3. This invention controls the amount of Sc added to 0.03-0.08%, allowing low-content Sc (0.03-0.08%) to precipitate preferentially. The phase acts as a heterogeneous nucleation core, making The precipitation incubation period was shortened from 50 hours to less than 5 hours, and the number density of the precipitated phase was increased to [missing information]. (The comparison ratio was increased by more than 2 times), the size was controlled at 12-15nm, the width of the precipitated phase depletion region was reduced from 10-20μm to 6-12μm, and the tissue uniformity was significantly improved.

[0023] 4. This invention ensures that the total Mg+Si content is ≥0.8% and the Mg / Si mass ratio is 1.5-4.0 by controlling the total Mg+Si content to be ≥0.8%. The phase-compensated analysis eliminates the harmful free Si content, thus improving conductivity, while avoiding the reduction in heat resistance caused by excess Mg, achieving a synergistic optimization of strength and conductivity. When the total Mg+Si content is in the range of 0.80%-0.85%, a conductivity ≥59% IACS can be obtained; when the total Mg+Si content is in the range of 0.90%-0.95%, the conductivity decreases slightly (57-58% IACS), but the strength is higher.

[0024] 5. The production process of this invention is compatible with existing continuous casting and rolling equipment, requiring no large-scale modification; the medium-temperature aging process (380-400℃) has low energy consumption, short production cycle, and is easy to implement industrially.

[0025] 6. This invention provides a high-conductivity, high-strength, heat-resistant aluminum alloy and its preparation process, solving the problems of insufficient strength (<260MPa), low electrical conductivity (<58%IACS), slow precipitation kinetics, and high cost of existing heat-resistant aluminum alloys. It yields a high-performance product with tensile strength ≥260MPa, electrical conductivity ≥58%IACS, recrystallization temperature ≥480℃, and a strength retention rate ≥90% after annealing at 230℃×1h. Furthermore, the raw material cost is controllable, making it suitable for industrial-scale mass production. Attached Figure Description Figure 1 This is a flowchart illustrating the preparation process of the high conductivity, high strength, and heat-resistant aluminum alloy of this invention.

[0026] Figure 2 For the present invention Core-shell phase and Schematic diagram of the dual-phase synergistic enhancement mechanism.

[0027] Figure 3 This is a bar chart comparing the mechanical properties of the embodiments and comparative examples in this invention.

[0028] Figure 4 This is a curve showing the effect of the Zr / Sc mass ratio on the overall properties of the alloy in this invention. (The fitting curve of the properties and the Zr / Sc mass ratio in this figure is obtained by fitting based on measured experimental data. It is used to intuitively present the variation law of properties with composition, delineate the optimal composition range, and verify the effect of the invention.)

[0029] Figure 5This is a curve showing the effect of aging temperature on alloy properties in this invention (the fitting curves of aging temperature and various properties in this figure are obtained by fitting based on measured experimental data, and are used to intuitively present the change law of properties with composition, delineate the optimal composition range, and verify the effect of the invention).

[0030] Figure 6 This is a schematic diagram of the steel-cored aluminum stranded wire product structure in this invention. Detailed Implementation

[0031] 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.

[0032] Application Overview: In one aspect, the present invention provides a high-conductivity, high-strength, and heat-resistant aluminum alloy, comprising, by weight percentage: Zr 0.08-0.15% (preferably 0.10-0.13%), Sc 0.03-0.08% (preferably 0.04-0.06%), Ti 0.02-0.05%, Mg 0.50-0.70% (preferably 0.55-0.65%), Si 0.25-0.35% (preferably 0.28-0.32%), Fe ≤0.15%, Cu ≤0.05%, other single impurities ≤0.03%, total impurities ≤0.1%, and the balance being Al and unavoidable impurities.

[0033] The mass ratio of Zr to Sc is 1.6-5.0, preferably 2.0-3.0; under this ratio, Zr and Sc form In a core-shell structure, they work synergistically, with Sc preferentially precipitating. As a heterogeneous nucleation core, the phase accelerates The precipitation of Zr, while Zr in Enriching the shell reduces the demand for Sc cores, ensuring the number density of precipitated phases while reducing costs.

[0034] The mass ratio of Mg to Si is 1.5-4.0, preferably 1.8-2.5; this ratio ensures The phase-filled analysis reveals that free Si does not impair conductivity, while avoiding excess Mg which reduces heat resistance, thus achieving synergistic optimization of strength and conductivity.

[0035] The total content of Mg and Si is ≥0.80%, preferably 0.85%-0.95%; sufficient Mg and Si content ensures The phase strengthening effect varies, and different content ranges have different emphase effects on alloy properties. For example, a total Mg+Si content of 0.80%-0.85% can achieve higher electrical conductivity, while a content of 0.90%-0.95% results in higher strength.

[0036] The alloy was characterized by field emission transmission electron microscopy (FETEM, 200 kV) and energy dispersive spectroscopy (EDS). The matrix showed a uniform equiaxed crystal structure with an average grain size of 35–50 μm. (See attached document.) Figure 2 The alloy matrix contains dispersed distributions of Composite phase and Phase, the described The composite phase has a clear core-shell structure, with Sc enriched in the core and Sc atoms accounting for ≥65 at%, and Zr enriched in the shell and Zr atoms accounting for ≥70 at%. The phase is distributed at grain boundaries and dislocations. The two work together to strengthen the structure. The core-shell phase inhibits recrystallization by pinning grain boundaries. The phases disperse and strengthen at grain boundaries and dislocations, jointly improving the alloy's strength, heat resistance, and electrical conductivity.

[0037] The The composite phase has a particle size of 12-15 nm, an average particle size of 13.2 nm, and a number density of [missing information]. The width of the precipitated phase depletion zone (PFZ) is 6–10 μm; The phase has a particle size of 20–50 nm, an average particle size of 32 nm, and a number density of 20–50 nm. No free Si and Massive phase.

[0038] On the other hand, see appendix Figure 1 The present invention also provides a method for preparing aluminum alloy single wire, comprising the following steps: Step 1: Raw Material Preparation. 99.80% pure industrial aluminum ingots are selected. Zr is added as an Al-10%Zr master alloy, Sc as an Al-2%Sc master alloy, and Ti as an Al-5%Ti master alloy. Mg and Si are industrial-grade raw materials (purity ≥99.8%). Before use, the raw materials are soaked in a 5% (v / v) dilute hydrofluoric acid solution for 30 seconds to remove the surface oxide layer, rinsed with deionized water, and then dried. This treatment effectively removes the oxide film on the surface of the raw materials, preventing it from adversely affecting the alloy composition and properties, and ensuring alloy quality.

[0039] Step 2: Vacuum Melting. Place the high-purity aluminum ingot into a vacuum induction melting furnace and evacuate it until... Heat the aluminum ingot to 740-760℃. After the aluminum ingot is completely melted, add Al-10%Zr, Al-2%Sc, and Al-5%Ti master alloys sequentially, and mechanically stir for 3-5 minutes (40-50 r / min) to fully dissolve Zr, Sc, and Ti. Then add industrial-grade pure Mg and Si raw materials and continue stirring for 2-3 minutes. Let it stand for 8-10 minutes to degas, during which time the oxygen content in the furnace is controlled to be ≤0.0015% (volume fraction). Remove the surface slag to obtain a homogeneous aluminum-magnesium-silicon-zirconium-scandium alloy liquid with a Zr / Sc mass ratio precisely controlled within the range of 1.6-5.0. Adding the raw materials in this order, first fully melting the refractory master alloy, and then adding Mg and Si, helps to ensure the uniform distribution of each element and improve the uniformity of the alloy composition.

[0040] Step 3: Continuous Casting and Electromagnetic Stirring for Homogenization. The molten alloy obtained in Step 2 is introduced into a horizontal continuous casting machine for casting. The casting temperature is controlled at 710-730℃, and a graphite mold is used to control the cooling rate at 15-20℃ / s. The billet diameter is φ80mm. During the casting process, electromagnetic stirring (frequency 50Hz, current intensity 200-300A) is activated simultaneously. The rotating magnetic field forces convection to suppress the dendritic segregation of Zr and Sc elements, ensuring that the billet grain size is ≤200μm and free of porosity and inclusions. Electromagnetic stirring generates a rotating magnetic field that forces convection in the molten liquid, disrupting the segregation of Zr and Sc elements between dendrites, thereby obtaining a billet with a uniform microstructure, laying the foundation for subsequent performance improvement.

[0041] Step 4: Homogenization Treatment. The billet obtained in Step 3 is directly transferred to a heat treatment furnace, heated to 480-520℃ and held for 8-12 hours. It is then cooled in the furnace to 300℃ and air-cooled. This process eliminates casting stress and promotes the homogenization of solute elements, forming a supersaturated solid solution, which lays the microstructural foundation for subsequent two-phase synergistic precipitation. Homogenization treatment further homogenizes the internal structure and composition of the billet, eliminating stress and compositional segregation during casting, which is beneficial for the uniform precipitation of the two phases during subsequent heat treatment.

[0042] Step 5: Hot Extrusion and Cold Working. The homogenized billet from Step 4 is heated to 400-450℃ by electromagnetic induction heating and extruded into φ18mm aluminum rods at an extrusion specific heat ratio of 15-20:1, with an extrusion speed of 1-2m / min. A fine-grained structure with a grain size ≤50μm is obtained through dynamic recrystallization. Immediately afterwards, it undergoes multi-pass continuous wire drawing cold working, with the total deformation rate controlled at 70-80% (single-pass deformation rate 8-12%). An intermediate annealing (300℃×1h) is inserted during this period to eliminate work hardening, ultimately obtaining φ9.5mm aluminum wire while retaining the dislocation density. Metastable deformed microstructure. Hot extrusion refines grains through dynamic recrystallization, improving material strength and plasticity. Cold working further increases dislocation density, enhancing alloy strength. Intermediate annealing eliminates work hardening, ensuring smooth cold working.

[0043] Step 6: Medium-temperature short-time aging strengthening. The cold-worked aluminum wire obtained in Step 5 is placed in an aging furnace and subjected to a "metastable medium-temperature short-time aging" process: heated to 380-400℃ at a heating rate of 5-10℃ / min (lower than the aging temperature of over 450℃ for traditional Al-Zr-Sc alloys), held at this temperature for 8-12 hours, and then air-cooled to room temperature; this specific process window is used to achieve... Core-shell phase (particle size 12-15 nm, number density) )and Synergistic precipitation of phases (particle size ≤ 50 nm), in which Sc is enriched in The core and Zr are concentrated in the outer shell. The two phases are distributed at grain boundaries and dislocations, and the two phases work together to pin the grain boundaries and inhibit recrystallization, while avoiding coarsening of the precipitated phases. Medium-temperature short-time aging achieves synergistic precipitation of the two phases at a lower temperature, avoiding the coarsening of the precipitated phases caused by high-temperature long-time aging, and effectively improving the overall performance of the alloy.

[0044] Step 7: Refer to Appendix Figure 6 The finished stranded wire is produced by concentrically stranding the heat-resistant aluminum alloy wire (after aging and strengthening in step 6) with a galvanized steel core, with a stranding pitch ratio controlled at 12-16 times. During the stranding process, a constant tension wire feeding device and an online lubrication and protection system are used to precisely control surface damage to the aluminum wire, preventing the formation of fatigue crack initiation, ultimately yielding a finished steel-cored aluminum stranded wire suitable for ultra-high voltage transmission lines. The use of a constant tension wire feeding device and an online lubrication and protection system reduces damage to the aluminum wire during stranding, improving the quality and service life of the finished steel-cored aluminum stranded wire.

[0045] The present invention will be further described below with reference to the embodiments. These embodiments are intended to explain the invention and should not be construed as limiting it. Where specific techniques and reaction conditions are not specified in the embodiments, they can be performed according to the techniques or conditions described in the literature or product instructions in the art. All reagents, instruments, or equipment without a specified manufacturer are commercially available.

[0046] Example 1: The preparation method of high conductivity, high strength and heat resistance aluminum alloy in this example includes the following steps: vacuum melting, continuous casting and electromagnetic stirring homogenization, hot extrusion and cold working, medium temperature short time aging, and finished stranded wire.

[0047] Step 1: Vacuum melting. Place industrial-grade pure aluminum ingots with a purity of 99.80% into a vacuum induction melting furnace and evacuate to a vacuum level. a. Heat to 750℃; after all aluminum ingots have melted, add Al-10%Zr, Al-2%Sc, and Al-5%Ti master alloys (containing impurities such as Fe and Cu) sequentially, and mechanically stir for 4 minutes (45 r / min). Then add industrial pure Mg and Si raw materials and continue stirring for 2 minutes; let stand for 9 minutes to degas, controlling the oxygen content in the furnace to ≤0.0012%, remove the slag, and obtain molten aluminum-zirconium-scandium-titanium-magnesium-silicon alloy liquid. The composition measured by sampling is as follows (wt.%): Zr 0.12, Sc 0.05, Ti 0.03, Mg 0.55, Si 0.30, Fe 0.10, Cu 0.03, Zr / Sc mass ratio 2.4, Mg / Si mass ratio 1.83, total Mg+Si content 0.85%, Al balance.

[0048] Step 2: Continuous casting and electromagnetic stirring for homogenization. The molten alloy liquid obtained in Step 1 is introduced into a horizontal continuous casting machine for casting. The casting temperature is controlled at 720℃, and a graphite mold is used to control the cooling rate at 18℃ / s to obtain a billet with a diameter of φ80mm. During the casting process, electromagnetic stirring (frequency 50Hz, current intensity 250A) is turned on simultaneously. Then the billet is directly transported to a heat treatment furnace for homogenization treatment. The temperature is raised to 500℃ and held for 10 hours. After cooling in the furnace to 300℃, it is air-cooled.

[0049] Step 3: Hot extrusion and cold working. The billet after homogenization in Step 2 is heated to 420℃ by electromagnetic induction and extruded into φ18mm aluminum rods at an extrusion ratio of 18:1 and an extrusion speed of 1.5m / min. Then, it immediately enters a multi-pass continuous wire drawing cold working process with a total deformation rate of 75% (single-pass deformation rate of 10%). During this process, an intermediate annealing is inserted once (300℃×1h) to finally obtain φ9.5mm aluminum wire.

[0050] Step 4: Medium-temperature short-time aging strengthening. The cold-worked aluminum wire obtained in Step 3 is placed into an aging furnace, heated to 390°C, held for 10 hours, and then air-cooled to room temperature.

[0051] Step 5: Finished stranded wire. The high conductivity, high strength and heat-resistant aluminum alloy wire after aging and strengthening in Step 4 is concentrically stranded with a galvanized steel core, and the stranding pitch ratio is controlled at 14 times.

[0052] The high conductivity, high strength, and heat-resistant aluminum alloy wire obtained in step 4 was subjected to performance testing, and the results are as follows: Table 1 Performance test values ​​of Example 1 Example 2: The preparation method of high conductivity, high strength and heat resistance aluminum alloy in this example includes the following steps: vacuum melting, continuous casting and electromagnetic stirring homogenization, hot extrusion and cold working, medium temperature short time aging, and finished stranded wire.

[0053] The difference between this embodiment and Embodiment 1 is that the elemental composition is different (Zr 0.13%, Sc 0.06%, Ti 0.04%, Mg 0.60%, Si 0.25%, Zr / Sc mass ratio 2.17, Mg / Si mass ratio 2.4, total Mg+Si content 0.85%), and the aging temperature and holding time in step 4 are different (the intermediate aging temperature is 400℃, and the holding time is 8 hours).

[0054] Step 1: Vacuum melting. Place industrial-grade pure aluminum ingots with a purity of 99.80% into a vacuum induction melting furnace and evacuate to a vacuum level. The temperature was raised to 750℃. After the aluminum ingots were completely melted, Al-10%Zr, Al-2%Sc, and Al-5%Ti master alloys were added sequentially, and mechanically stirred for 4 minutes (45 r / min). Then, industrial-grade pure Mg and Si raw materials were added, and stirring was continued for 2 minutes. The mixture was allowed to stand for 9 minutes to degas, and the oxygen content in the furnace was controlled to be ≤0.0012%. The slag was removed to obtain molten aluminum-zirconium-scandium-titanium-magnesium-silicon alloy liquid. The composition of the sample was measured as follows (wt.%): Zr 0.13%, Sc 0.06%, Ti 0.04%, Mg 0.60%, Si 0.25%, Zr / Sc mass ratio 2.17, Mg / Si mass ratio 2.4, total Mg+Si content 0.85%, and Al balance.

[0055] Step 2: Continuous casting and electromagnetic stirring for homogenization. The molten alloy liquid obtained in Step 1 is introduced into a horizontal continuous casting machine for casting. The casting temperature is controlled at 720℃, and a graphite mold is used to control the cooling rate at 18℃ / s to obtain a billet with a diameter of φ80mm. During the casting process, electromagnetic stirring (frequency 50Hz, current intensity 250A) is turned on simultaneously. Then the billet is directly transported to a heat treatment furnace for homogenization treatment. The temperature is raised to 500℃ and held for 10 hours. After cooling in the furnace to 300℃, it is air-cooled.

[0056] Step 3: Hot extrusion and cold working. The billet after homogenization in Step 2 is heated to 420℃ by electromagnetic induction and extruded into φ18mm aluminum rods at an extrusion ratio of 18:1 and an extrusion speed of 1.5m / min. Then, it immediately enters a multi-pass continuous wire drawing cold working process with a total deformation rate of 75% (single-pass deformation rate of 10%). During this process, an intermediate annealing is inserted once (300℃×1h) to finally obtain φ9.5mm aluminum wire.

[0057] Step 4: Medium-temperature short-time aging strengthening. The cold-worked aluminum wire obtained in Step 3 is placed into an aging furnace, heated to 400℃, held for 8 hours, and then air-cooled to room temperature.

[0058] Step 5: Finished stranded wire. The high conductivity, high strength and heat-resistant aluminum alloy wire after aging and strengthening in Step 4 is concentrically stranded with a galvanized steel core, and the stranding pitch ratio is controlled at 14 times.

[0059] The high conductivity, high strength, and heat-resistant aluminum alloy wire obtained in step 4 was subjected to performance testing, and the results are as follows: Table 2 Performance test values ​​of Example 2 Example 3: The preparation method of high conductivity, high strength and heat resistance aluminum alloy in this example includes the following steps: vacuum melting, continuous casting and electromagnetic stirring homogenization, hot extrusion and cold working, medium temperature short time aging, and finished stranded wire.

[0060] The difference between this embodiment and Embodiment 1 is that the elemental composition is different (Zr 0.08%, Sc 0.03%, Ti 0.02%, Mg 0.65%, Si 0.30%, Zr / Sc mass ratio 2.67, Mg / Si mass ratio 2.17, total Mg+Si content 0.95%), and the aging temperature and holding time in step 4 are different (aging temperature is 380℃, holding time is 12 hours).

[0061] Step 1: Vacuum melting. Place industrial-grade pure aluminum ingots with a purity of 99.80% into a vacuum induction melting furnace and evacuate to a vacuum level. The temperature was raised to 750℃. After the aluminum ingots were completely melted, Al-10%Zr, Al-2%Sc, and Al-5%Ti master alloys were added sequentially, and mechanically stirred for 4 minutes (45 r / min). Then, industrial-grade pure Mg and Si raw materials were added, and stirring was continued for 2 minutes. The mixture was allowed to stand for 9 minutes to degas, and the oxygen content in the furnace was controlled to be ≤0.0012%. The slag was removed to obtain molten aluminum-zirconium-scandium-titanium-magnesium-silicon alloy liquid. The composition of the sample was measured as follows (wt.%): Zr 0.08%, Sc 0.03%, Ti 0.02%, Mg 0.65%, Si 0.30%, Zr / Sc mass ratio 2.67, Mg / Si mass ratio 2.17, total Mg+Si content 0.95%, and Al balance.

[0062] Step 2: Continuous casting and electromagnetic stirring for homogenization. The molten alloy liquid obtained in Step 1 is introduced into a horizontal continuous casting machine for casting. The casting temperature is controlled at 720℃, and a graphite mold is used to control the cooling rate at 18℃ / s to obtain a billet with a diameter of φ80mm. During the casting process, electromagnetic stirring (frequency 50Hz, current intensity 250A) is turned on simultaneously. Then the billet is directly transported to a heat treatment furnace for homogenization treatment. The temperature is raised to 500℃ and held for 10 hours. After cooling in the furnace to 300℃, it is air-cooled.

[0063] Step 3: Hot extrusion and cold working. The billet after homogenization in Step 2 is heated to 420℃ by electromagnetic induction and extruded into φ18mm aluminum rods at an extrusion ratio of 18:1 and an extrusion speed of 1.5m / min. Then, it immediately enters a multi-pass continuous wire drawing cold working process with a total deformation rate of 75% (single-pass deformation rate of 10%). During this process, an intermediate annealing is inserted once (300℃×1h) to finally obtain φ9.5mm aluminum wire.

[0064] Step 4: Medium-temperature short-time aging strengthening. The cold-worked aluminum wire obtained in Step 3 is placed into an aging furnace, heated to 380°C, held for 12 hours, and then air-cooled to room temperature.

[0065] Step 5: Finished stranded wire. The high conductivity, high strength and heat-resistant aluminum alloy wire after aging and strengthening in Step 4 is concentrically stranded with a galvanized steel core, and the stranding pitch ratio is controlled at 14 times.

[0066] The high conductivity, high strength, and heat-resistant aluminum alloy wire obtained in step 4 was subjected to performance testing, and the results are as follows: Table 3 Performance test values ​​of Example 3 Example 4: The preparation method of high conductivity, high strength and heat resistance aluminum alloy in this example includes the following steps: vacuum melting, continuous casting and electromagnetic stirring homogenization, hot extrusion and cold working, medium temperature short time aging, and finished stranded wire.

[0067] The difference between this embodiment and Embodiment 1 is that the elemental composition is different (Zr 0.10%, Sc 0.04%, Ti 0.05%, Mg 0.50%, Si 0.30%, Zr / Sc mass ratio 2.5, Mg / Si mass ratio 1.67, total Mg+Si content 0.80%), and the aging temperature and holding time in step 4 are different (aging temperature is 385℃, holding time is 11 hours).

[0068] Step 1: Vacuum melting. Place industrial-grade pure aluminum ingots with a purity of 99.80% into a vacuum induction melting furnace and evacuate to a vacuum level. The temperature was raised to 750℃. After the aluminum ingots were completely melted, Al-10%Zr, Al-2%Sc, and Al-5%Ti master alloys were added sequentially, and mechanically stirred for 4 minutes (45 r / min). Then, industrial-grade pure Mg and Si raw materials were added, and stirring was continued for 2 minutes. The mixture was allowed to stand for 9 minutes to degas, and the oxygen content in the furnace was controlled to be ≤0.0012%. The slag was removed to obtain molten aluminum-zirconium-scandium-titanium-magnesium-silicon alloy liquid. The composition of the sample was measured as follows (wt.%): Zr 0.10%, Sc 0.04%, Ti 0.05%, Mg 0.50%, Si 0.30%, Zr / Sc mass ratio 2.5, Mg / Si mass ratio 1.67, total Mg+Si content 0.80%, and Al balance.

[0069] Step 2: Continuous casting and electromagnetic stirring for homogenization. The molten alloy liquid obtained in Step 1 is introduced into a horizontal continuous casting machine for casting. The casting temperature is controlled at 720℃, and a graphite mold is used to control the cooling rate at 18℃ / s to obtain a billet with a diameter of φ80mm. During the casting process, electromagnetic stirring (frequency 50Hz, current intensity 250A) is turned on simultaneously. Then the billet is directly transported to a heat treatment furnace for homogenization treatment. The temperature is raised to 500℃ and held for 10 hours. After cooling in the furnace to 300℃, it is air-cooled.

[0070] Step 3: Hot extrusion and cold working. The billet after homogenization in Step 2 is heated to 420℃ by electromagnetic induction and extruded into φ18mm aluminum rods at an extrusion ratio of 18:1 and an extrusion speed of 1.5m / min. Then, it immediately enters a multi-pass continuous wire drawing cold working process with a total deformation rate of 75% (single-pass deformation rate of 10%). During this process, an intermediate annealing is inserted once (300℃×1h) to finally obtain φ9.5mm aluminum wire.

[0071] Step 4: Medium-temperature short-time aging strengthening. The cold-worked aluminum wire obtained in Step 3 is placed into an aging furnace, heated to 385°C, held for 11 hours, and then air-cooled to room temperature.

[0072] Step 5: Finished stranded wire. The high conductivity, high strength and heat-resistant aluminum alloy wire after aging and strengthening in Step 4 is concentrically stranded with a galvanized steel core, and the stranding pitch ratio is controlled at 14 times.

[0073] The high conductivity, high strength, and heat-resistant aluminum alloy wire obtained in step 4 was subjected to performance testing, and the results are as follows: Table 4 Performance test values ​​of Example 4 Comparative Example 1 (Traditional Al-Zr binary alloy, without Sc / Mg / Si): This comparative example uses the traditional Al-Zr binary alloy preparation method, including the following steps: vacuum melting, continuous casting, homogenization treatment, hot extrusion and cold working, and aging treatment.

[0074] The difference between this comparative example and Example 1 is that the elemental composition is different (Zr 0.12%, Fe 0.10%, Cu 0.03%, without the addition of Sc, Ti, Mg, and Si elements, the remainder being Al and unavoidable impurities), and electromagnetic stirring is not turned on in step 2.

[0075] Step 1: Vacuum melting. Place industrial-grade pure aluminum ingots with a purity of 99.80% into a vacuum induction melting furnace and evacuate to a vacuum level. The temperature was raised to 750℃; after the aluminum ingots were completely melted, Al-10%Zr master alloy was added, and the mixture was mechanically stirred for 4 minutes (45 r / min). It was then allowed to stand for 9 minutes to degas, controlling the oxygen content in the furnace to ≤0.0012%. The slag was removed to obtain molten aluminum-zirconium-scandium-titanium-magnesium-silicon alloy. The composition (wt.%) of the sample was as follows: Zr 0.12%, Fe 0.10%, Cu 0.03%, with no added Sc, Ti, Mg, or Si elements; the remainder was Al and unavoidable impurities.

[0076] Step 2: Continuous casting. The molten alloy liquid obtained in Step 1 is introduced into a horizontal continuous casting machine for casting. The casting temperature is controlled at 720℃, and a graphite mold is used to control the cooling rate at 18℃ / s to obtain a billet with a diameter of φ80mm.

[0077] Step 3: Homogenization treatment. The billet is then directly transported to a heat treatment furnace for homogenization treatment. The temperature is raised to 500℃ and held for 10 hours. After cooling in the furnace to 300℃, it is air-cooled.

[0078] Step 4: Hot extrusion and cold working. The billet after homogenization in step 3 is heated to 420℃ by electromagnetic induction and extruded into φ18mm aluminum rods at an extrusion ratio of 18:1 and an extrusion speed of 1.5m / min. Then, it immediately enters a multi-pass continuous wire drawing cold working process with a total deformation rate of 75% (single-pass deformation rate of 10%). During this process, an intermediate annealing is inserted once (300℃×1h) to finally obtain φ9.5mm aluminum wire.

[0079] Step 5: Aging treatment. Place the cold-worked aluminum wire obtained in Step 3 into an aging furnace, heat it to 390℃, hold it at that temperature for 10 hours, and then air cool it to room temperature.

[0080] The performance of the Al-Zr binary alloy wire obtained in step 5 was tested, and the results are as follows: Table 5 Performance test values ​​for Comparative Example 1 Materials Science Analysis: Single Enhancement, lack of Sc accelerated precipitation leads to low number density ( ), and none Synergistic strengthening (lacking the strengthening contribution of Mg+Si≥0.8%), the strength is only 185MPa, far below the target of 260MPa; Uneven distribution of precipitated phase results in a recrystallization temperature of only 360℃ and poor heat resistance.

[0081] Comparative Example 2 (Al-Zr-Sc ternary alloy, without Mg-Si synergy): This comparative example prepared an Al-Zr-Sc-Ti alloy (without Mg or Si), including the following steps: vacuum melting, continuous casting and electromagnetic stirring homogenization, hot extrusion and cold working, and medium-temperature short-time aging.

[0082] The difference between this comparative example and Example 1 is that the elemental composition is different (Zr 0.12%, Sc 0.05%, Ti 0.03%, Fe 0.10%, Cu 0.03%, without the addition of Mg and Si elements (total Mg+Si content ≈ 0), the rest is Al and unavoidable impurities).

[0083] Step 1: Vacuum melting. Place industrial-grade pure aluminum ingots with a purity of 99.80% into a vacuum induction melting furnace and evacuate to a vacuum level. The temperature was raised to 750℃. After the aluminum ingots were completely melted, Al-10%Zr, Al-2%Sc, and Al-5%Ti master alloys were added sequentially, and mechanically stirred for 4 minutes (45 r / min). Then, industrial-grade pure Mg and Si raw materials were added, and stirring was continued for 2 minutes. The mixture was allowed to stand for 9 minutes to degas, and the oxygen content in the furnace was controlled to be ≤0.0012%. The slag was removed to obtain molten aluminum-zirconium-scandium-titanium-magnesium-silicon alloy liquid. The composition of the sample was measured as follows (wt.%): Zr 0.12%, Sc 0.05%, Ti 0.03%, Fe 0.10%, Cu 0.03%, with no added Mg or Si elements (total Mg+Si content ≈ 0), and the remainder being Al and unavoidable impurities.

[0084] Step 2: Continuous casting and electromagnetic stirring for homogenization. The molten alloy liquid obtained in Step 1 is introduced into a horizontal continuous casting machine for casting. The casting temperature is controlled at 720℃, and a graphite mold is used to control the cooling rate at 18℃ / s to obtain a billet with a diameter of φ80mm. During the casting process, electromagnetic stirring (frequency 50Hz, current intensity 250A) is turned on simultaneously. Then the billet is directly transported to a heat treatment furnace for homogenization treatment. The temperature is raised to 500℃ and held for 10 hours. After cooling in the furnace to 300℃, it is air-cooled.

[0085] Step 3: Hot extrusion and cold working. The billet after homogenization in Step 2 is heated to 420℃ by electromagnetic induction and extruded into φ18mm aluminum rods at an extrusion ratio of 18:1 and an extrusion speed of 1.5m / min. Then, it immediately enters a multi-pass continuous wire drawing cold working process with a total deformation rate of 75% (single-pass deformation rate of 10%). During this process, an intermediate annealing is inserted once (300℃×1h) to finally obtain φ9.5mm aluminum wire.

[0086] Step 4: Medium-temperature short-time aging strengthening. The cold-worked aluminum wire obtained in Step 3 is placed into an aging furnace, heated to 390°C, held for 10 hours, and then air-cooled to room temperature.

[0087] The alloy wire obtained in step 4 was subjected to performance testing, and the results are as follows: Table 6 Performance test values ​​for Comparative Example 2 Materials analysis: Although the addition of Sc improved... Precipitation kinetics (residual rate 91%, good heat resistance), but lacks Mg+Si≥0.8% precipitation kinetics. The phase reinforcement contribution is only 225 MPa, which cannot reach the target of 260 MPa; proving that the present invention " "The necessity of dual-phase synergistic enhancement is that only when the total Mg+Si content is ≥0.8% and the Mg / Si ratio is in the range of 1.5-4.0 can the synergistic optimization of strength ≥260MPa and conductivity ≥58%IACS be achieved."

[0088] 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 high-conductivity, high-strength, heat-resistant aluminum alloy, characterized in that, By weight percentage, it includes: Zr 0.08-0.15%, Sc 0.03-0.08%, Ti 0.02-0.05%, Mg 0.50-0.70%, Si 0.25-0.35%, Fe ≤0.15%, Cu ≤0.05%, other single impurities ≤0.03%, total impurities ≤0.1%, and the remainder is Al and unavoidable impurities; wherein, the mass ratio of Zr to Sc is 1.6-5.0, the mass ratio of Mg to Si is 1.5-4.0, and the total content of Mg and Si is ≥0.80%.

2. The high conductivity, high strength, and heat-resistant aluminum alloy according to claim 1, characterized in that, By weight percentage, it includes: Zr 0.10-0.13%, Sc 0.04-0.06%, Ti 0.02-0.05%, Mg 0.55-0.65%, Si 0.28-0.32%, Fe ≤0.15%, Cu ≤0.05%, other single impurities ≤0.03%, total impurities ≤0.1%, and the balance being Al and unavoidable impurities.

3. The high conductivity, high strength, and heat-resistant aluminum alloy according to claim 1, characterized in that, The alloy matrix contains dispersed distributions of Composite phase and Phase, the described The composite phase has a core-shell structure, with Sc enriched in the core and Zr enriched in the shell. The phase is distributed at grain boundaries and dislocations.

4. The high conductivity, high strength, and heat-resistant aluminum alloy according to claim 3, characterized in that, The The composite phase has a particle size of 12-15 nm and a number density of 12-15 nm. The Phase particle size ≤50nm, number density .

5. The high conductivity, high strength, and heat-resistant aluminum alloy according to claim 1, characterized in that, The Zr content is 0.10-0.13% and the Sc content is 0.04-0.06% by mass percentage.

6. The high conductivity, high strength, and heat-resistant aluminum alloy according to claim 1, characterized in that, The mass ratio of Zr to Sc is 2.0-3.0, the mass ratio of Mg to Si is 1.8-2.5, and the total content of Mg and Si is 0.85%-0.95%.

7. A method for preparing a high-conductivity, high-strength, heat-resistant aluminum alloy according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Raw material preparation; S2, Vacuum Melting: S3. Continuous casting and electromagnetic stirring for homogenization: S4. Homogenization treatment; S5. Hot extrusion and cold working: Extruded into φ18mm aluminum rods at 400-450℃ with an extrusion ratio of 15-20:1; cold-worked in multiple passes to φ9.5mm, with a total deformation rate of 70-80%, during which intermediate annealing at 300℃×1h is performed. S6. Medium-temperature short-time aging enhancement: Heat to 380-400℃ at a heating rate of 5-10℃ / min, hold for 8-12 hours, and air cool to room temperature; S7. Finished stranded wire.

8. The method for preparing a high-conductivity, high-strength, heat-resistant aluminum alloy according to claim 7, characterized in that, In S1, high-purity aluminum ingots, Al-Zr alloys, Al-Sc alloys, Al-Ti alloys, industrial-pure Mg, and industrial-pure Si have their surface oxide layers removed by dilute hydrofluoric acid. Among them, the Zr content in the Al-Zr alloy is 10wt%, the Sc content in the Al-Sc alloy is 2wt%, and the Ti content in the Al-Ti alloy is 5wt%.

9. The method for preparing a high-conductivity, high-strength, heat-resistant aluminum alloy according to claim 7, characterized in that, In S2, high-purity aluminum ingots are placed in a vacuum induction melting furnace, vacuumed and heated to melting point; Al-Zr alloy, Al-Sc alloy, and Al-Ti alloy are added in sequence and stirred, then Mg and Si raw materials are added and stirred again; the furnace is allowed to stand to degas, and the oxygen content in the furnace is controlled to be ≤0.0015%, and the slag is removed.

10. The method for preparing a high-conductivity, high-strength, heat-resistant aluminum alloy according to claim 6, characterized in that, In S3, a horizontal continuous casting machine is used, with a casting temperature of 710-730℃, a cooling rate of 15-20℃ / s, a billet diameter of φ80mm, electromagnetic stirring is turned on, the electromagnetic stirring frequency is 50Hz, the current intensity is 200-300A, and the billet grain size is ≤200μm. In S4, the billet is heated to 480-520℃, held for 8-12 hours, cooled to 300℃ in the furnace, and then air-cooled. In S7, aged aluminum alloy wire is stranded with galvanized steel core at a pitch ratio of 12-16 times to form finished steel-cored aluminum stranded wire.

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