Aluminum-iron-boron microalloying high-conductivity aluminum alloy single wire and preparation method thereof

Abstract

The invention discloses an aluminum-iron-boron microalloyed high-conductivity aluminum alloy single wire and a preparation method thereof.The aluminum-iron-boron microalloyed high-conductivity aluminum alloy single wire is prepared from, by mass, 0.3%-0.8% of Fe, 0.06%-0.25% of B, smaller than or equal to 0.05% of RE, 0.02%-0.05% of Si, 0.02%-0.06% of Ti and the balance Al and inevitable impurities, according to the preparation method, step-by-step smelting sequential control is conducted, Ti is melted to form an Al3Ti transition phase, then B of a preset formula is added, Al3Ti is converted into a high-density TiB2 phase, the high-density TiB2 phase is subjected to heat treatment, and the aluminum-iron-boron microalloyed high-conductivity aluminum alloy single wire is obtained. Al-Fe-B phase fixed free Fe atoms are promoted to be formed, and through multi-stage continuous hot rolling and stepped annealing, the prepared aluminum alloy single wire achieves high conductivity and excellent creep resistance.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy single-wire manufacturing technology, and in particular to an aluminum-iron-boron microalloyed high-conductivity aluminum alloy single wire and its preparation method. Background Technology

[0002] With the rapid development of ultra-high voltage power transmission and new energy grid connection technologies, power cable conductors face higher requirements for lightweight design, high conductivity (≥62% IACS), and high-temperature creep resistance. Traditional aluminum alloy conductor technology suffers from the following bottlenecks: For example, Chinese invention patent CN101525709B discloses a high-elongation aluminum alloy material for cables, namely an Al-Fe-RE alloy containing rare earth elements (RE). The rare earth phase refines the microstructure. However, rare earth elements in aluminum alloys may react with elements such as oxygen and sulfur to form inclusions. For instance, inclusions formed by the reaction of rare earth cerium (Ce) with oxygen (such as Ce₂O₃) can affect the purity of the aluminum alloy, thereby reducing conductivity and increasing brittleness.

[0003] Traditional high-conductivity aluminum alloys rely on rare earth modification (RE) treatment of eutectic silicon. However, for low-silicon alloys (Si < 0.1%), the modification effect on eutectic silicon is not significant due to the low silicon content. Therefore, rare earth modification treatment does not achieve the desired effect in such alloys. Nevertheless, these low-silicon alloys are widely used in power cable conductors, thus the limitations of this process restrict its application in this field.

[0004] Furthermore, rare earth elements, as scarce resources, are relatively limited in supply due to their sparse distribution and high extraction difficulty, further increasing the cost of aluminum alloy manufacturing. The industry has long considered rare earth elements (RE) as essential for performance enhancement, overemphasizing their role in regulating performance. However, this has resulted in difficulties in synergistically optimizing the conductivity, high-temperature creep resistance, and cost-effectiveness of aluminum alloys. Therefore, there is an urgent need to develop a new type of aluminum alloy conductor that combines engineering practicality, reduces reliance on rare earth functions to adapt to continuous industrial production, and achieves a synergistic improvement in strength, conductivity, and creep resistance. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing an aluminum-iron-boron microalloyed high-conductivity aluminum alloy single wire and its preparation method, thereby reducing dependence on rare earth elements while achieving high conductivity, excellent tensile strength, and creep resistance of low-silicon aluminum alloys.

[0006] The technical solution to achieve the objective of this invention is: A microalloyed aluminum-iron-boron high-conductivity aluminum alloy single wire, wherein the composition of the aluminum alloy single wire by mass percentage is: Fe 0.3%~0.8%, B 0.06%~0.25%, RE≤0.05%, Si 0.02%~0.05%, Ti 0.02%~0.06%, with the balance being Al and unavoidable impurities.

[0007] Furthermore, the RE component in the aluminum alloy single wire is composed of La and Ce, and the Ce content is <0.02% by mass percentage of the aluminum alloy single wire.

[0008] Furthermore, the mass ratio of Fe / Si in the composition of the aluminum alloy single wire is 8~15, and the mass ratio of B / Ti is 3~4.

[0009] A method for preparing a microalloyed aluminum-iron-boron high-conductivity aluminum alloy single wire includes the following steps: Step S1: Melting, melt the remelted aluminum ingot into aluminum liquid, add aluminum iron, silicon, titanium and boron intermediate alloy ingots in sequence according to the preset formula, stir evenly to obtain mixed alloy liquid; Step S2: Refining and purification. The mixed alloy liquid is transferred to a holding furnace and refined using a refining agent. After refining and settling, the composition is analyzed and adjusted to obtain a mixed alloy liquid that meets the above-mentioned formula composition of aluminum alloy single line. The mixed alloy liquid is then discharged from the holding furnace and sequentially processed by an online impurity removal and degassing system, grain refinement treatment, and precision filtration treatment to obtain aluminum alloy liquid. Step S3: Continuous casting: The molten aluminum alloy is introduced into the casting machine and continuously cast using the horizontal casting method, and then solution-treated online to obtain aluminum alloy ingots. Step S4: Continuous rolling and drawing to obtain aluminum alloy single wire. The aluminum alloy billet is fed into an induction heater for heating and is continuously rolled in multiple stages to obtain aluminum alloy rods. The rolled aluminum alloy rods are then subjected to quenching and temperature control treatment, and the quenched aluminum alloy rods are coiled up. The coiled aluminum alloy rods are then subjected to pre-annealing treatment, and the pre-annealed aluminum alloy rods are then subjected to high-speed drawing to obtain aluminum alloy single wires. Step S5: Single-wire heat treatment, the aluminum alloy single wire is heat treated to obtain aluminum-iron-boron microalloyed high-conductivity aluminum alloy single wire.

[0010] Further, in step S1, aluminum-iron alloy, aluminum-silicon alloy and aluminum-titanium alloy are first added to the aluminum liquid in sequence to melt and obtain a low-silicon aluminum-iron-titanium alloy liquid. Then, 30-60% boron-aluminum alloy of the preset formula is added to it and kept at 750-780°C for 25-35 minutes. Then, the remaining boron-aluminum alloy of the preset formula is added to it and kept at the same temperature for the same time to obtain the mixed alloy liquid.

[0011] Furthermore, when the melting temperature of the molten aluminum reaches 750~780℃, aluminum-titanium alloy is added and the mixture is kept at that temperature for at least 15 minutes.

[0012] Furthermore, in step S1, before adding the boron-aluminum alloy, an aluminum-rare earth alloy with a preset formula is first added to the low-silicon aluminum-iron-titanium alloy liquid.

[0013] Furthermore, in step S2, the refining agent is a sodium-free, high-efficiency refining agent, and the refining agent is slowly blown in from the bottom of the mixed alloy liquid.

[0014] Further, after refining, a covering agent is evenly sprayed onto the surface of the mixed alloy liquid, and the mixture is kept at a set temperature of 720~760℃ for a period of not less than 30 minutes.

[0015] Furthermore, in step S4, the total deformation of the multi-segment continuous rolling is >90%, the final rolling temperature is 300~350℃, and the cooling rate between segments is ≥50℃ / s.

[0016] Furthermore, in step S4, the pre-annealing treatment adopts stepped annealing, wherein the annealing temperature of the first stage is 370~390℃ and the holding time is 1~1.5h, and the annealing temperature of the second stage is 410~430℃ and the holding time is 1.5~2.5h.

[0017] Furthermore, the pre-annealing treatment also includes an intermediate stage located between the first stage and the second stage, wherein the annealing temperature of the intermediate stage is 390~410℃ and the holding time is 1~1.5h, in order to further stabilize the microstructure of the alloy.

[0018] By adopting the above technical solution, the present invention has the following beneficial effects: (1) The silicon content in the aluminum alloy single wire formulation of the present invention is only 0.02%~0.05% Si, which belongs to low silicon aluminum alloy. The tensile strength and creep resistance of low silicon aluminum alloy are improved by an appropriate amount of iron element. By reducing the addition of rare earth elements in the formulation, the material cost of aluminum alloy single wire is significantly reduced. Since rare earth elements have a significant effect on refinement and purification, in order to make up for the defects caused by reducing rare earth elements, the present invention increases the content of boron element in the formulation. On the one hand, boron element forms TiB2 with titanium element, forming non-spontaneous crystal nuclei, increasing the number of effective nuclei, thereby refining the alloy structure. On the other hand, boron element forms AlFeB phase with aluminum element and iron element, thereby fixing free Fe, reducing the precipitation of harmful phases, and thus improving the conductivity and heat resistance of the alloy. This allows aluminum-iron-boron microalloyed aluminum alloy single wire with low rare earth addition or even no rare earth addition to still have high conductivity and excellent tensile strength and creep resistance.

[0019] (2) The rare earth elements of the present invention are La (lanthanum) and Ce, and the Ce content is controlled to be <0.02%, further reducing the inclusions (such as Ce2O3) generated by the reaction of rare earth cerium Ce with oxygen, thus reducing the impact on the purity of aluminum alloy.

[0020] (3) By controlling the Fe / Si mass ratio to 8~15, this invention can effectively promote the combination of Fe and B to form a stable AlFeB phase. If the Fe / Si mass ratio is too small, the Si content is excessive, and Fe preferentially combines with Si to form a harmful β-AlFeSi phase. If the Fe / Si mass ratio is too large, Fe is excessive and may form other Fe-enriched phases, thereby increasing the brittleness of the aluminum alloy conductor and deteriorating its conductivity. Since the ideal stoichiometric mass ratio of TiB2 is about Ti:B = 2.21:1, by controlling the B / Ti mass ratio to 3~4, it is ensured that boron and titanium will form TiB2, and there is enough remaining boron to form the AlB2 phase with aluminum, ensuring a certain AlB2 phase, taking into account refinement, purification and conductivity. If the B / Ti mass ratio is too small, the above effects cannot be achieved. If it is too large, other borides or free B are easily formed, which remain in the matrix in the form of particles or agglomerates, affecting the conductivity and plasticity of the aluminum alloy single wire.

[0021] (4) In the preparation method of the present invention, by introducing the dispersed heterogeneous nucleation particles Al3Ti and TiB2 formed by Ti and B, the grains can be significantly refined and the strength, ductility and conductivity of the material can be improved. By controlling the step-by-step melting sequence, Ti is first melted and kept at a temperature of ≥15min to form the Al3Ti transition phase. Then, 30~60% of the total B amount is added in batches and kept at a temperature to transform Al3Ti into a high-density TiB2 phase (density 4.52 g / cm³). The density difference of the TiB2 phase is used to enable the TiB2 phase to carry and adsorb impurities with a particle size <10μm to settle to the bottom of the melt, thereby replacing rare earth elements to achieve the purpose of purification. Then, the remaining B elements are added to promote the formation of Al-Fe-B phase to fix free Fe atoms, reduce the precipitation of harmful phases, and thus improve the conductivity and heat resistance of the alloy.

[0022] (5) In the preparation method of the present invention, by reasonably controlling the melting temperature of Ti, it is ensured that the intermediate alloy can be fully melted, and the high temperature is avoided to cause the segregation of titanium elements or the coarsening of local reaction products, which would affect the refinement. At the same time, the holding time is reasonably controlled. On the one hand, the aluminum-titanium intermediate alloy needs a certain amount of time to be fully melted and evenly distributed in the aluminum liquid. On the other hand, it helps the Ti compound particles to be fully dispersed, avoids local aggregation or settling, and stabilizes the melt state, which is convenient for subsequent refining / modification treatment.

[0023] (6) By adding an appropriate amount of aluminum rare earth alloy, the present invention plays an auxiliary purification role, while avoiding the formation of inclusions (such as Ce2O3) by excessive rare earth alloy reacting with oxygen, which would affect the purity of aluminum alloy and further improve the performance of aluminum alloy single wire.

[0024] (7) The refining agent of the present invention is a sodium-free high-efficiency refining agent to avoid the introduction of sodium elements and prevent it from causing "sodium embrittlement" in Al-Si alloys with low silicon content, which affects the material properties. At the same time, the refining agent uses an inert gas (such as argon Ar or nitrogen N2) as a carrier and is blown in from the bottom of the melt and slowly blown in from the bottom of the mixed alloy liquid. On the one hand, it prolongs the contact time between the refining agent and the melt and improves the refining effect. On the other hand, the bubbles drive the melt to circulate during the rising process, which enhances the degassing and slag removal effect. At the same time, it can reduce surface disturbance and reduce the risk of secondary gas absorption.

[0025] (8) The present invention avoids the alloy liquid from being exposed to the air and reacting with oxygen to form aluminum oxide and inclusions by spraying a covering agent, and at the same time plays a role in heat preservation.

[0026] (9) The present invention adopts a multi-stage continuous rolling process to achieve a uniform and dispersed distribution of TiB2; by controlling the large deformation amount (>90%), the coarse structure of the cast structure is broken, the grains are refined, and the recrystallization and uniform distribution of precipitates are promoted; by adopting segmented rolling and rapid cooling, the aggregation of TiB2 particles is suppressed and its fine and dispersed state is maintained. On the one hand, by strictly controlling the final rolling temperature, the work hardening or crack tendency caused by excessively low temperature is avoided, and the element diffusion during subsequent solution treatment is also facilitated. On the other hand, rapid cooling prevents the coarsening of TiB2 particles and retains the dislocation structure formed during the rolling process, providing nucleation sites for subsequent precipitation.

[0027] (10) The present invention sets up a stepped annealing process, releases residual stress in the first stage to start the precipitation process, and promotes the dispersion precipitation of TiB2 particles in the second stage and stabilizes their size to maintain it at 80~120 nm. By segmented heating, it is beneficial to the orderly precipitation and uniform distribution of the precipitated phase, avoids coarsening or agglomeration, and finally forms a nanoscale TiB2 dispersion-strengthened structure, improving the balance between the strength and conductivity of the material. Attached Figure Description

[0028] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein: Figure 1 This is a key process flow diagram of the present invention; Figure 2 This is a flowchart of the preparation method of the present invention. Detailed Implementation

[0029] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0030] Example 1 provides a microalloyed high-conductivity aluminum alloy single wire with strong high-temperature creep resistance, high conductivity, high elongation, and high tensile strength. This not only has wide applicability but also significant economic benefits, providing strong support for the upgrading and optimization of power infrastructure. The aluminum alloy single wire, by mass percentage, comprises: Fe 0.3%~0.8%, B 0.06%~0.25%, RE≤0.05%, Si 0.02%~0.05%, Ti 0.02%~0.06%, with the balance being Al and unavoidable impurities.

[0031] The Fe / Si mass ratio is 8-15, which effectively promotes the combination of Fe and B to form a stable AlFeB phase. If the Fe / Si mass ratio is too small, the Si content is excessive, and Fe preferentially combines with Si to form the harmful β-AlFeSi phase. If the Fe / Si mass ratio is too large, the Fe content is excessive, and other Fe-enriched phases may form, leading to increased brittleness and deterioration of conductivity in the aluminum alloy conductor. Since the ideal stoichiometric mass ratio of TiB2 is approximately Ti:B = 2.21:1, by controlling the B / Ti mass ratio to 3-4, it is ensured that boron and titanium will form TiB2, while there is sufficient residual boron to form the AlB2 phase with aluminum. This ensures a certain AlB2 phase, balancing refinement, purification, and conductivity. If the B / Ti mass ratio is too small, the above effects cannot be achieved. If it is too large, other borides or free B are easily formed, remaining in the matrix in the form of particles or agglomerates, affecting the conductivity and ductility of the aluminum alloy wire.

[0032] In addition, the RE component in the aluminum alloy single wire is composed of La and Ce, and the Ce content is <0.02% by mass percentage of the aluminum alloy single wire, which further reduces the inclusions (such as Ce2O3) generated by the reaction of rare earth cerium Ce with oxygen, thus reducing the impact on the purity of the aluminum alloy.

[0033] The aluminum alloy single wire in this embodiment is a low-silicon aluminum alloy. The appropriate amount of iron element improves the tensile strength and creep resistance of the low-silicon aluminum alloy. By reducing the addition of rare earth elements in the formula, the material cost of the aluminum alloy single wire is significantly reduced. Since rare earth elements have a significant effect on refining and purifying, in order to compensate for the defects caused by reducing rare earth elements, the content of boron element is increased in the formula. On the one hand, boron element forms TiB2 with titanium element, forming non-spontaneous crystal nuclei, increasing the number of effective nuclei, thereby refining the alloy structure. On the other hand, boron element forms AlFeB phase with aluminum and iron elements, thereby fixing free Fe, reducing the precipitation of harmful phases, and improving the conductivity and heat resistance of the alloy. This allows the aluminum-iron-boron microalloyed aluminum alloy single wire with low or even no rare earth addition to still have high conductivity and excellent tensile strength and creep resistance.

[0034] refer to Figure 1 and Figure 2 The method for preparing aluminum-iron-boron microalloyed high-conductivity aluminum alloy single wire in this embodiment includes the following steps: Step S1: Melting, melt the remelted aluminum ingot into aluminum liquid, add aluminum iron, silicon, titanium and boron intermediate alloy ingots in sequence according to the preset formula, stir evenly to obtain mixed alloy liquid; First, add the aluminum-iron alloy. When the melting temperature of the aluminum liquid reaches 750~780℃, add the aluminum-titanium alloy and hold it at that temperature for at least 15 minutes. This ensures that the intermediate alloy can be fully melted and avoids excessive temperature, which could lead to segregation of titanium or coarsening of local reaction products, thus affecting the refining process. At the same time, the holding time should be reasonably controlled. On the one hand, the aluminum-titanium intermediate alloy needs a certain amount of time to completely melt and be evenly distributed in the aluminum liquid. On the other hand, it helps the Ti compound particles to be fully dispersed, avoiding local aggregation or settling at the bottom. It also stabilizes the melt state, which is convenient for subsequent refining / modification treatment. Then, aluminum-silicon alloy and aluminum-titanium alloy are added to the aluminum liquid in sequence and melted to obtain a low-silicon aluminum-iron-titanium alloy liquid. Then, according to the formula requirements, a suitable aluminum rare earth alloy is added to the low-silicon aluminum-iron-titanium alloy liquid to play an auxiliary purification role. At the same time, it avoids the formation of inclusions (such as Ce2O3) due to excessive rare earth alloy reaction with oxygen, which would affect the purity of the aluminum alloy and further improve the performance of the aluminum alloy single wire. Subsequently, a step-by-step melting sequence control was adopted. First, 30-60% boron-aluminum alloy of the preset formula was added and held at 750-780℃ for 25-35 minutes. Then, the remaining boron-aluminum alloy of the preset formula was added and held for the same amount of time to obtain a mixed alloy liquid. In this embodiment, the first boron addition ratio was 40%, the second boron addition ratio was 60%, and the holding time was 30 minutes. Through step-by-step melting sequence control, Ti was first melted to form the Al3Ti transition phase. By adding B in batches, the first addition of B transformed Al3Ti into a high-density TiB2 phase (density 4.52 g / cm³). The density difference of the TiB2 phase was used to allow the TiB2 phase to carry and adsorb impurities with a particle size <10μm to settle to the bottom of the melt, thereby replacing the purpose of purification using rare earth elements in the traditional process. The remaining B element added later promoted the formation of Al-Fe-B phase to fix free Fe atoms, reducing the precipitation of harmful phases, thereby improving the conductivity and heat resistance of the alloy.

[0035] Step S2: Refining and purification. The mixed alloy liquid is transferred to a holding furnace and refined using a sodium-free, high-efficiency refining agent to avoid introducing sodium elements and prevent "sodium embrittlement" in Al-Si alloys with low silicon content, which would affect material properties. The refining agent is carried by an inert gas and slowly blown into the mixed alloy liquid from the bottom. This prolongs the contact time between the refining agent and the melt, improving the refining effect. On the other hand, the rising bubbles drive the melt circulation, enhancing the degassing and slag removal effects, while reducing surface disturbance and lowering the risk of secondary gas absorption.

[0036] After refining, a covering agent is evenly sprayed onto the surface of the mixed alloy liquid to prevent it from being exposed to air and reacting with oxygen to form aluminum oxide and inclusions. This also serves as thermal insulation. The liquid is then kept at a set temperature of 720-760℃ for at least 30 minutes. After refining and settling, component analysis and adjustment are performed to obtain a mixed alloy liquid that meets the formulation requirements of the aforementioned aluminum alloy single wire. In this embodiment, the mixed alloy liquid contains 0.3% Fe, 0.10% B, 0.03% RE, 0.03% Si, and 0.03% Ti, with the remainder being unavoidable impurities in aluminum alloys.

[0037] The mixed alloy liquid then flows out of the holding furnace and is successively processed by an online impurity and degassing system, grain refinement treatment and precision filtration treatment to obtain aluminum alloy liquid; Step S3: Continuous casting: The molten aluminum alloy is introduced into the casting machine and continuously cast using the horizontal casting method. The aluminum alloy ingot is obtained by online solution treatment at a temperature of 515~525℃. Step S4: Continuous rolling and drawing to obtain aluminum alloy single wire. The aluminum alloy billet is fed into an induction heater for heating, while undergoing multi-stage continuous rolling to achieve a uniform and dispersed distribution of TiB2. The total deformation of the multi-stage continuous rolling is controlled to be >90%, breaking the coarse structure of the as-cast microstructure, refining the grains, and promoting recrystallization and uniform distribution of precipitates. The final rolling temperature is controlled at 300~350℃ to avoid excessive work hardening or cracking due to excessively low temperatures, and also to facilitate element diffusion during subsequent solution treatment. The inter-stage cooling rate is controlled to be ≥50℃ / s. Rapid cooling prevents coarsening of TiB2 particles and preserves the dislocation structure formed during rolling, providing nucleation sites for subsequent precipitation, ultimately obtaining the aluminum alloy rod. The rolled aluminum alloy rod is subjected to quenching and temperature control treatment, and then coiled. The coiled aluminum alloy rod undergoes pre-annealing treatment, which employs stepped annealing. The first stage annealing temperature is 370~390℃, with a holding time of 1~1.5h; the intermediate stage annealing temperature is 390~410℃, with a holding time of 1~1.5h, to further stabilize the alloy's microstructure; the second stage annealing temperature is 410~430℃, with a holding time of 1.5~2.5h. The pre-annealed aluminum alloy rod is then subjected to high-speed wire drawing to obtain aluminum alloy single wire. In this embodiment, the first stage annealing temperature is 380℃, and the second stage annealing temperature is 420℃. The first stage releases residual stress and initiates the precipitation process. The second stage promotes the dispersed precipitation of TiB2 particles and stabilizes their size, maintaining them at 80~120 nm. The segmented heating facilitates the orderly precipitation and uniform distribution of the precipitated phase, avoiding coarsening or agglomeration, and ultimately forming a nanoscale TiB2 dispersed reinforced structure, improving the balance between the material's strength and conductivity. Step S5: Single-wire heat treatment. The aluminum alloy single wire is heat treated using existing processes to obtain aluminum-iron-boron microalloyed high-conductivity aluminum alloy single wire.

[0038] Example 2: The preparation method of the aluminum alloy single wire in this example is similar to that in Example 1, except that the composition of this example is Fe 0.35%, B 0.06%, RE 0.01%, Si 0.04%, Ti 0.015%, with the remainder being unavoidable impurities in aluminum alloy. The boron addition ratio is 30% and 70% respectively, the holding temperature is 30 min, the first stage temperature in the stepped annealing process is 370℃, and the second stage temperature is 410℃.

[0039] Example 3: The method for preparing the aluminum alloy single wire in this example is similar to that in Example 1, except that the composition of this example is Fe 0.75%, B 0.15%, RE 0.05%, Si 0.05%, Ti 0.04%, with the remainder being unavoidable impurities in aluminum alloy. The boron addition ratio is 50% and 50% respectively, the holding temperature is 35 min, and the first stage temperature in the stepped annealing process is 390℃, and the second stage temperature is 430℃.

[0040] Example 4: The preparation method of the aluminum alloy single wire in this example is similar to that in Example 1, except that the composition of this example does not contain rare earth elements. Specifically, the composition is as follows: Fe 0.6%, B 0.23%, Si 0.05%, Ti 0.06%, with the remainder being unavoidable impurities in aluminum alloy. The boron addition ratio is 45% and 55% respectively, the holding temperature is 30 min, the first stage temperature in the stepped annealing process is 380℃, and the second stage temperature is 420℃.

[0041] Example 5: The preparation method of the aluminum alloy single wire in this example is similar to that in Example 1, except that the composition of this example is Fe 0.4%, B 0.12%, RE 0.02%, Si 0.03%, Ti 0.04%, with the remainder being unavoidable impurities in aluminum alloy. The boron addition ratio is 40% and 60% respectively, the holding temperature is 28 min, the first stage temperature in the stepped annealing process is 375℃, and the second stage temperature is 415℃.

[0042] Comparative Example 1: The preparation method of the aluminum alloy single wire in Comparative Example 1 is similar to that in Example 1, except that the composition of Comparative Example 1 is Fe 0.5%, B 0.1%, RE 0.3%, Si 0.03%, Ti 0.03%, with the remainder being unavoidable impurities in aluminum alloys. Boron was added twice, at 40% and 60% respectively, with a holding temperature of 30 min. The first stage temperature in the stepped annealing process was 380℃, and the second stage temperature was 420℃. The RE content was excessive.

[0043] Comparative Example 2: The preparation method of the aluminum alloy single wire in Comparative Example 2 is similar to that in Example 1, except that the composition of Comparative Example 2 is Fe 0.35%, B 0.01%, RE 0.01%, Si 0.04%, Ti 0.01%, with the remainder being unavoidable impurities in aluminum alloys. The boron addition ratio was 30% and 70% respectively, the holding temperature was 25 min, and the first stage temperature in the stepped annealing process was 370℃, and the second stage temperature was 410℃. The B / Ti mass ratio was 1, indicating that the B content was too low.

[0044] Comparative Example 3: The preparation method of the aluminum alloy single wire in Comparative Example 3 is similar to that in Example 1, except that the composition of Comparative Example 3 is Fe 0.5%, B 0.2%, RE 0.02%, Si 0.03%, Ti 0.02%, with the remainder being unavoidable impurities in aluminum alloys. The boron addition ratio was 40% and 60% respectively, the holding temperature was 30 min, and the first stage temperature in the stepped annealing process was 380℃, and the second stage temperature was 420℃. The mass ratio of B to Ti was 10.

[0045] Comparative Example 4: The preparation method of the aluminum alloy single wire in Comparative Example 4 is similar to that in Example 1, except that the composition of Comparative Example 4 is Fe 0.75%, B 0.2%, RE 0.05%, Si 0.05%, Ti 0.05%, with the remainder being unavoidable impurities in aluminum alloys. All boron-aluminum master alloys were added at once, and the holding temperature was 30 min. The first stage temperature in the stepped annealing process was 390°C, and the second stage temperature was 430°C.

[0046] Comparative Example 5: The preparation method of the aluminum alloy single wire in Comparative Example 5 is similar to that in Example 1, except that the composition of Comparative Example 5 is Fe 0.6%, B 0.15%, Si 0.1%, Ti 0.04%, with the remainder being unavoidable impurities in aluminum alloys. The boron addition ratio was 45% and 55% respectively, the holding temperature was 30 min, and the first stage temperature in the stepped annealing process was 380℃, and the second stage temperature was 420℃. The Fe / Si mass ratio was 6.

[0047] Comparative Example 6: The preparation method of the aluminum alloy single wire in Comparative Example 6 is similar to that in Example 1, except that the composition of Comparative Example 6 is Fe 0.6%, B 0.08%, Si 0.03%, Ti 0.02%, with the remainder being unavoidable impurities in aluminum alloys. The boron addition ratio was 45% and 55% respectively, the holding temperature was 30 min, and the first stage temperature in the stepped annealing process was 380℃, and the second stage temperature was 420℃. The Fe / Si mass ratio was 20.

[0048] The aluminum alloy single wires prepared in the above embodiments and comparative examples were subjected to relevant performance tests. The composition and key processes of Examples 1-5 are shown in Table 1, the composition and key processes of Comparative Examples 1-6 are shown in Table 2, and the performance test results are shown in Table 3. ; ;

[0049] According to the performance test data in Table 3: This invention, under the premise of low rare earth element or no rare earth element-assisted purification, obtains a uniformly distributed TiB2 phase microstructure of 80-120 nm by controlling the Fe / Si mass ratio of 8-15, the B / Ti mass ratio of 3-4, and the step-by-step melting sequence, and finally by multi-stage continuous hot rolling and stepped annealing. The resulting aluminum alloy fully meets the single-wire properties standards, achieving a conductivity ≥62.5% IACS and a steady-state creep rate of ≤5.0×10 at 120℃ / 80MPa. -10 s -1 The low-silicon aluminum alloy single wires from Examples 1-5 were subjected to further long-term creep tests (300 hours), and the creep rate remained ≤6.0×10⁻⁶. -10 s -1 It demonstrates good long-term stability.

[0050] This invention is applied to low-silicon aluminum alloy conductors. By increasing the amount of boron (B) added and strictly controlling the Fe / Si and B / Ti mass ratios, dispersed heterogeneous nucleation particles Al3Ti and TiB2 formed by Ti and B are introduced, which significantly refines the grains and improves the material's strength, ductility, and conductivity. Through stepwise melting sequence control, Ti is first melted and held at a temperature ≥15 min to form the Al3Ti transition phase. Then, 30-60% of the total B is added in batches and held at a temperature to transform Al3Ti into a high-density TiB2 phase (density 4.52 g / cm³). 3 The TiB2 phase utilizes its density difference to allow impurities with adsorption particle sizes <10μm to settle to the bottom of the melt, thereby replacing rare earth elements to achieve purification. Subsequently, the remaining B element is added to promote the formation of an Al-Fe-B phase to fix free Fe atoms, reducing the precipitation of harmful phases and thus improving the alloy's conductivity and heat resistance.

[0051] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A micro-alloyed aluminum-iron-boron high-conductivity aluminum alloy single wire, characterized in that: The composition of the aluminum alloy single wire, by mass percentage, is: Fe 0.3%~0.8%, B 0.06%~0.25%, RE≤0.05%, Si 0.02%~0.05%, Ti 0.02%~0.06%, with the balance being Al and unavoidable impurities.

2. The aluminum-iron-boron microalloyed high-conductivity aluminum alloy single wire according to claim 1, characterized in that: The RE component in the aluminum alloy single wire is composed of La and Ce, and the Ce content is <0.02% by mass percentage of the aluminum alloy single wire.

3. The aluminum-iron-boron microalloyed high-conductivity aluminum alloy single wire according to claim 2, characterized in that: The composition of the aluminum alloy single wire has an Fe / Si mass ratio of 8~15 and a B / Ti mass ratio of 3~4.

4. A method for preparing a microalloyed aluminum-iron-boron high-conductivity aluminum alloy single wire, characterized in that, Includes the following steps: Step S1: Melting, melt the remelted aluminum ingot into aluminum liquid, add aluminum iron, silicon, titanium and boron intermediate alloy ingots in sequence according to the preset formula, stir evenly to obtain mixed alloy liquid; Step S2: Refining and purification. The mixed alloy liquid is transferred to a holding furnace and refined using a refining agent. After refining and settling, the composition is analyzed and adjusted to obtain a mixed alloy liquid that meets the formulation composition of the aluminum alloy single wire according to any one of claims 1 to 3. The mixed alloy liquid is then discharged from the holding furnace and sequentially processed by an online impurity removal and degassing system, grain refinement treatment, and precision filtration treatment to obtain aluminum alloy liquid. Step S3: Continuous casting: The molten aluminum alloy is introduced into the casting machine and continuously cast using the horizontal casting method, and then solution-treated online to obtain aluminum alloy ingots. Step S4: Continuous rolling and drawing to obtain aluminum alloy single wire. The aluminum alloy billet is fed into an induction heater for heating and is continuously rolled in multiple stages to obtain aluminum alloy rods. The rolled aluminum alloy rods are then subjected to quenching and temperature control treatment, and the quenched aluminum alloy rods are coiled up. The coiled aluminum alloy rods are then subjected to pre-annealing treatment, and the pre-annealed aluminum alloy rods are then subjected to high-speed drawing to obtain aluminum alloy single wires. Step S5: Single-wire heat treatment, the aluminum alloy single wire is heat treated to obtain aluminum-iron-boron microalloyed high-conductivity aluminum alloy single wire.

5. The method for preparing an aluminum-iron-boron microalloyed high-conductivity aluminum alloy single wire according to claim 4, characterized in that: In step S1, aluminum-iron alloy, aluminum-silicon alloy, and aluminum-titanium alloy are first added to the molten aluminum in sequence to melt and obtain a low-silicon aluminum-iron-titanium alloy liquid. Then, 30-60% boron-aluminum alloy of the preset formula is added to it and kept at 750-780°C for 25-35 minutes. Then, the remaining boron-aluminum alloy of the preset formula is added to it and kept at the same temperature for the same time to obtain the mixed alloy liquid.

6. The method for preparing an aluminum-iron-boron microalloyed high-conductivity aluminum alloy single wire according to claim 5, characterized in that: When the melting temperature of the aluminum liquid reaches 750~780℃, aluminum-titanium alloy is added and the mixture is kept at that temperature for at least 15 minutes.

7. The method for preparing an aluminum-iron-boron microalloyed high-conductivity aluminum alloy single wire according to claim 4, characterized in that: In step S2, the refining agent is a sodium-free, high-efficiency refining agent, and the refining agent is blown in from the bottom of the mixed alloy liquid.

8. The method for preparing an aluminum-iron-boron microalloyed high-conductivity aluminum alloy single wire according to claim 7, characterized in that: After refining, a covering agent is evenly sprayed onto the surface of the mixed alloy liquid, and the mixture is kept at a set temperature of 720~760℃ for a period of not less than 30 minutes.

9. The method for preparing a microalloyed high-conductivity aluminum alloy single wire according to claim 4, characterized in that: In step S4, the total deformation of the multi-segment continuous rolling is >90%, the final rolling temperature is 300~350℃, and the cooling rate between segments is ≥50℃ / s.

10. The method for preparing an aluminum-iron-boron microalloyed high-conductivity aluminum alloy single wire according to claim 4, characterized in that: In step S4, the pre-annealing process adopts stepped annealing, wherein the annealing temperature of the first stage is 370~390℃ and the holding time is 1~1.5h, and the annealing temperature of the second stage is 410~430℃ and the holding time is 1.5~2.5h.

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