High-strength and high-conductivity Al-Mg-Si alloy and preparation method and application thereof

Abstract

The invention discloses a high-strength and high-conductivity Al-Mg-Si alloy and a preparation method and application thereof, and relates to the technical field of aluminum alloy wire manufacturing, the alloy comprises the following components in percentage by mass: 0.2-0.9 wt% of Mg, 0.2-0.9 wt% of Si, 0.9-1.5 wt% of Mg + Si, 0.2-0.6 wt% of an Al-5Ti-0.2 B refiner, and other elements: less than or equal to 0.12 wt% of Fe, less than or equal to 0.01 wt% of Cu, less than or equal to 0.02 wt% of Mn, less than or equal to 0.02 wt% of Zn, 0.04-0.07 wt% of B, and the balance of Al; wherein Ti / B = 0.15-0.25, and (Ti + B) / (Mg + Si) = 0.04-0.06, the manufacturing method comprises the following steps of smelting, homogenization treatment, hot extrusion and short-process deformation aging treatment.The Al 5Ti-0.2 B refiner is added before pouring to introduce particles, in the hot extrusion-aging-cold deformation process, the concentration of harmful solid solution atoms can be reduced, the strength and conductivity of the material are improved, and the strength and conductivity of the material are improved. The short-process deformation aging preparation method is provided, the performance of the material can be improved to the maximum extent, the prepared aluminum alloy has excellent mechanical performance while keeping high conductivity, and meanwhile the preparation process is simple and low in cost.

Description

Technical Field

[0001] This application relates to the field of aluminum alloy wire manufacturing technology, and in particular to a high-strength, high-conductivity Al-Mg-Si alloy, its preparation method, and its application. Background Technology

[0002] To meet the development needs of high-voltage, high-capacity transmission lines in my country, there is an urgent need to replace traditional steel-cored aluminum stranded wires with high losses. Al-Mg-Si aluminum alloys possess excellent heat-treatable strengthening properties, but there is a trade-off between their strength and conductivity: increasing strength requires increasing crystal defects (such as precipitates, dislocations, and grain boundaries), but this exacerbates electron scattering and reduces conductivity. Currently known heat treatment processes (such as T6, T3, and T8) cannot simultaneously meet the requirements of high strength and high conductivity. Crucially, solid solution atoms have the greatest impact on conductivity, while precipitates contribute the most significantly to strength, and dislocations contribute significantly to strength but have little effect on conductivity. Therefore, it is necessary to develop a new, short-process technology aimed at reducing the concentration of solid solution atoms, preventing coarsening of precipitates, and introducing high-density dislocations to improve the overall performance of Al-Mg-Si alloy conductors.

[0003] Prior art document 1 (CN115821129A) discloses a high-strength, high-conductivity aluminum alloy energy-saving wire and its preparation method, wherein: the mass percentage of Mg is 0.43%-0.95%, the mass percentage of Si is 0.29%-0.91%, the mass ratio of Mg / Si is 1.04-1.52, the mass percentage of Cu is 0.03%-0.10%, the mass percentage of Sc is 0.01%-0.05%, the mass percentage of B is 0.01%-0.04%, the mass percentage of Fe is 0.02%-0.07%, the mass percentage of (Cr+Ti) is less than or equal to 0.004%, and the balance is aluminum and unavoidable trace impurities. However, after being melted into ingots, it is directly subjected to deformation treatment without homogenization of the ingots. The ingots have severe compositional segregation and many defects. The as-cast structure after solidification deviates from the equilibrium state. There are non-equilibrium compositional segregation, eutectic structures or intermetallic compounds between grain boundaries and dendrite arms. These structures usually lead to poor processing performance and are not conducive to subsequent deformation processing. Moreover, adding precious metals such as Sc and Zr to the alloy increases the cost.

[0004] Prior art document 2 (CN112522553A) discloses a high-performance Al-Mg-Si alloy and its preparation method. The alloy preparation method is a short-process sub-rapid solidification casting and rolling method, comprising five steps: alloy melting, water-cooled copper roll casting and rolling, multi-pass cold rolling, solution heat treatment, and artificial aging. However, the alloy is not homogenized before multi-pass cold rolling; the alloy melt is simply guided into the gap of the water-cooled copper rolls for casting and rolling to obtain a sub-rapid solidification alloy cast billet. Although the ingot obtained by this method has fewer defects, due to water cooling, it suffers from severe compositional segregation. Non-equilibrium compositional segregation, eutectic structures, or intermetallic compounds exist between grain boundaries and dendrite arms. These structures typically lead to poor machinability and are detrimental to subsequent deformation processing. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a high-strength, high-conductivity Al-Mg-Si alloy for overhead conductors and a short-process deformation aging preparation method thereof, which simultaneously improves the material's conductivity and strength for the preparation of high-strength, high-conductivity conductors.

[0006] The present invention adopts the following technical solution.

[0007] The first aspect of the present invention discloses a high-strength and high-conductivity Al-Mg-Si alloy comprising the following components by mass percentage: Mg: 0.2-0.9 wt%, Si: 0.2-0.9 wt%, Mg+Si: 0.9-1.5 wt%, Al-5Ti-0.2B refining agent: 0.2-0.6 wt%, other elements: Fe: ≤0.12 wt.%, Cu: ≤0.01 wt.%, Mn: ≤0.02 wt.%, Zn: ≤0.02 wt.%, B: 0.04-0.07 wt%, with the balance being Al; wherein Ti / B = 0.15-0.25, (Ti+B) / (Mg+Si) = 0.04-0.06.

[0008] Preferably, the mass ratio of Mg / Si is 1 to 1.05, and the mass ratio of B / Fe is 0.5 to 0.6.

[0009] A second aspect of the present invention discloses a method for preparing a high-strength, high-conductivity Al-Mg-Si alloy according to the first aspect, comprising the following steps: Step 1: Add industrial pure aluminum, Al-3%B master alloy, Al-10%Mg master alloy and Al-12%Si master alloy to a reaction vessel for melting to obtain a melt. Add Al-5Ti-0.2B refining agent to the melt and pour it into a steel mold to obtain an aluminum alloy ingot. Step 2: Anneal the aluminum alloy ingot obtained in Step 1 at a set temperature; Step 3: The aluminum alloy ingot after annealing and cooling in Step 2 is extruded using a hot extrusion press to obtain aluminum rods; Step 4: The aluminum rod obtained in Step 3 is subjected to solution treatment, first-stage artificial aging treatment, wire drawing and second-stage artificial aging treatment in sequence to obtain the high-strength and high-conductivity Al-Mg-Si alloy.

[0010] Preferably, in step 1, the order of adding raw materials is as follows: Al 3%B master alloy and industrial pure aluminum are heated simultaneously, then Al 12%Si master alloy and Al 10%Mg master alloy are added, and finally Al 5Ti-0.2B refining agent is added before casting.

[0011] Preferably, in step 2, the set temperature is 540-570℃, and the homogenization annealing is carried out by holding the temperature for 12-24 hours. After the holding period, the furnace is cooled down to 250-300℃, and then the furnace is taken out and air-cooled.

[0012] Preferably, in step 3, the aluminum alloy ingot after homogenization and annealing is preheated to 350-400°C and then extruded using a hot extrusion press with an extrusion ratio of 36 and an extrusion speed of 2-10 min / s.

[0013] Preferably, in step 4, the solution treatment involves heating the hot extrusion rod to 550–570°C for solution treatment, holding it at that temperature for 30–60 minutes, and then water quenching it at room temperature.

[0014] Preferably, in step 4, the first-level artificial aging treatment involves sending the rod material to an aging furnace for artificial aging treatment, with an artificial aging temperature of 150–190°C and an artificial aging time of 0.5–12 hours.

[0015] Preferably, in step 4, the secondary artificial aging treatment is to perform either artificial aging treatment or natural aging treatment on the drawn wire, with the artificial aging temperature being 150-190℃ and the artificial aging time being 0.5-12 hours, and the natural aging time being 5-7 days, and the natural aging temperature being room temperature.

[0016] The third aspect of the present invention discloses the application of a high-strength, high-conductivity Al-Mg-Si alloy described in the first aspect in power transmission conductors.

[0017] Compared with the prior art, the beneficial effects of the present invention include at least the following: 1. This invention uses Al-5Ti-0.2B as a refining agent. The dominant refining phase of Al-5Ti-0.2B is TiAl3 + a small amount of TiB2. The TiAl3 phase in Al-5Ti-0.2B (content > 4wt%) provides a large number of heterogeneous nucleation cores, directly matching the peritectic solidification path of low-alloy aluminum alloys. The TiAl3 phase can also avoid the poisoning effect of high alloying elements. Furthermore, by limiting the ratio of Ti / B and (Ti+B) / (Mg+Si), this invention solves the problem that after the impurity elements are borated, there is no excess B element reacting with the Al3Ti particles in Al-5Ti-0.2B, thus ensuring that the refining agent effect of Al-5Ti-0.2B is not affected, further improving the strength and electrical conductivity of the alloy material. 2. The present invention proposes a short-process deformation aging preparation method based on the addition of a refining agent, namely a two-stage aging process of aging + deformation + aging. This method can maximize the improvement of material performance. On the basis of the first-stage artificial aging and desolvation, the deformation process introduces a large number of dislocations to improve strength. In the second-stage aging process, the high-density dislocations can fully desolvate solid solution atoms with the extension of aging time, reducing their damage to conductivity. Moreover, the desolvation efficiency of solid solution atoms by artificial aging is significantly higher than that of natural aging.

[0018] 3. The high-strength and high-conductivity Al-Mg-Si alloy of this invention is closely integrated with the traditional aluminum alloy preparation process, is easy to promote, and has low cost, and can be mass-produced. The prepared aluminum alloy has excellent mechanical properties while maintaining high electrical conductivity. The material can maintain a tensile strength of over 360MPa and an electrical conductivity of over 54%IACS, and can be used to prepare high-strength and high-conductivity transmission conductors. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the tensile strength under different (Ti+B) / (Mg+Si) ratios in this invention; Figure 2 This is a schematic diagram showing the conductivity at different (Ti+B) / (Mg+Si) ratios in this invention; Figure 3 These are engineering stress-strain curves for different (Ti+B) / (Mg+Si) ratios in this invention. Figure 4 The image shows the engineering stress-strain curves of the high-strength, high-conductivity Al-Mg-Si alloys of Comparative Example 1 and Examples 13-15 in this invention. Figure 5 This is a comparison diagram of the tensile strength of Comparative Example 1 and Examples 13-15 in this invention; Figure 6 This is a comparison chart of the conductivity of Comparative Example 1 and Examples 13-15 in this invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0021] An embodiment of the present invention discloses a high-strength, high-conductivity Al-Mg-Si alloy, composed of the following mass percentages: Mg: 0.2–0.9 wt%, Si: 0.2–0.9 wt%, Mg+Si: 0.9–1.5 wt%, Al-5Ti-0.2B refining agent: 0.2–0.6 wt%, other elements: Fe: ≤0.12 wt.%, Cu: ≤0.01 wt.%, Mn: ≤0.02 wt.%, Zn: ≤0.02 wt.%, B: 0.04–0.07 wt%, balance Al; Among them, Ti / B = 0.15~0.25, (Ti+B) / (Mg+Si) = 0.04~0.06.

[0022] It is worth noting that before specifying (Ti+B) / (Mg+Si), Ti / B needs to be specified as 0.15 to 0.25, because the refining agent added to the alloy described in this invention is Al-5Ti-0.2B, whose main refining particles are Al3Ti and TiB2. In contrast, the refining agent used in general high-alloyed aluminum alloys or recycled aluminum is Al-3Ti-1B, which uses TiB2 directly as the nucleation substrate.

[0023] Because the solidification process of low-alloy aluminum alloys relies on peritectic reactions, the TiAl3 phase (content > 4 wt%) in Al-5Ti-0.2B provides a large number of heterogeneous nucleation sites, directly matching the peritectic solidification path of this type of alloy. Furthermore, the TiAl3 phase can also avoid the poisoning effect of high-alloying elements. In low-alloy aluminum alloys, the Al-5Ti-0.2B refining agent can play a better role at lower casting temperatures. In addition, the Al-5Ti-0.2B refining agent enables the material to have good cold and hot working capabilities in subsequent deformation treatments. During hot pressing, the Al3Ti and TiB2 particles contained in Al-5Ti-0.2B can effectively pin dislocations and subgrain boundaries, inhibit recrystallization grain coarsening, prevent abnormal grain growth during processing, and improve the material's homogeneous plastic deformation capability. After cold deformation and aging, the Al3Ti and TiB2 particles can hinder dislocation recovery, keeping the material in a high-density dislocation state, thus improving the material's strength and electrical conductivity.

[0024] However, when using Al-5Ti-0.2B as a refining agent, Al3Ti particles readily react with boron to form TiB2 in the presence of excess boron. Although TiB2 particles can also exert a good refining effect, in Al-Mg-Si alloys, Al3Ti generally exhibits the optimal refining ability and improves the material's processing and forming capabilities. Therefore, in this invention, the Ti / B ratio is limited to 0.15–0.25. At this Ti / B ratio, after the impurity elements are borated, there is no excess B element reacting with the Al3Ti particles in Al-5Ti-0.2B, thus ensuring that the effect of the Al-5Ti-0.2B refining agent remains unaffected.

[0025] Example 1 Al-Mg-Si alloy, wherein the alloy comprises the following components by mass percentage: Mg: 0.2-0.9 wt%, Si: 0.2-0.9 wt%, Mg+Si=1.0 wt%, Al-5Ti-0.2B refining agent: 0.2-0.6 wt%, other elements: Fe: ≤0.12 wt.%, Cu: ≤0.031 wt.%, Mn: ≤0.02 wt.%, Zn: ≤0.02 wt.%, B: 0.04-0.07 wt%, balance Al.

[0026] Ti / B=0.15~0.25, (Ti+B) / (Mg+Si) = 0.01.

[0027] Example 2 Al-Mg-Si alloy, wherein the alloy comprises the following components by mass percentage: Mg: 0.2-0.9 wt%, Si: 0.2-0.9 wt%, Mg+Si=1.0 wt%, Al-5Ti-0.2B refining agent: 0.2-0.6 wt%, other elements: Fe: ≤0.12 wt.%, Cu: ≤0.031 wt.%, Mn: ≤0.02 wt.%, Zn: ≤0.02 wt.%, B: 0.04-0.07 wt%, balance Al.

[0028] Ti / B=0.15~0.25, (Ti+B) / (Mg+Si) = 0.03.

[0029] Example 3 Al-Mg-Si alloy, wherein the alloy comprises the following components by mass percentage: Mg: 0.2~0.9wt%, Si: 0.2~0.9wt%, Mg+Si=1.0wt%, Al-5Ti-0.2B refining agent: 0.2~0.6wt%, other elements: Fe: ≤0.12wt.%, Cu: ≤0.031wt.%, Mn: ≤0.02wt.%, Zn: ≤0.02wt.%, B: 0.04~0.07wt%, balance Al.

[0030] Ti / B=0.15~0.25, (Ti+B) / (Mg+Si) = 0.04.

[0031] Example 4 Al-Mg-Si alloy, wherein the alloy comprises the following components by mass percentage: Mg: 0.2~0.9wt%, Si: 0.2~0.9wt%, Mg+Si=1.0wt%, Al-5Ti-0.2B refining agent: 0.2~0.6wt%, other elements: Fe: ≤0.12wt.%, Cu: ≤0.031wt.%, Mn: ≤0.02wt.%, Zn: ≤0.02wt.%, B: 0.04~0.07wt%, balance Al.

[0032] Ti / B=0.15~0.25, (Ti+B) / (Mg+Si) = 0.043.

[0033] Example 5 Al-Mg-Si alloy, wherein the alloy comprises the following components by mass percentage: Mg: 0.2~0.9wt%, Si: 0.2~0.9wt%, Mg+Si=1.0wt%, Al-5Ti-0.2B refining agent: 0.2~0.6wt%, other elements: Fe: ≤0.12wt.%, Cu: ≤0.031wt.%, Mn: ≤0.02wt.%, Zn: ≤0.02wt.%, B: 0.04~0.07wt%, balance Al.

[0034] Ti / B=0.15~0.25, (Ti+B) / (Mg+Si) = 0.047.

[0035] Example 6 Al-Mg-Si alloy, wherein the alloy comprises the following components by mass percentage: Mg: 0.2~0.9wt%, Si: 0.2~0.9wt%, Mg+Si=1.0wt%, Al-5Ti-0.2B refining agent: 0.2~0.6wt%, other elements: Fe: ≤0.12wt.%, Cu: ≤0.031wt.%, Mn: ≤0.02wt.%, Zn: ≤0.02wt.%, B: 0.04~0.07wt%, balance Al.

[0036] Ti / B=0.15~0.25, (Ti+B) / (Mg+Si) = 0.05.

[0037] Example 7 Al-Mg-Si alloy, wherein the alloy comprises the following components by mass percentage: Mg: 0.2~0.9wt%, Si: 0.2~0.9wt%, Mg+Si=1.0wt%, Al-5Ti-0.2B refining agent: 0.2~0.6wt%, other elements: Fe: ≤0.12wt.%, Cu: ≤0.031wt.%, Mn: ≤0.02wt.%, Zn: ≤0.02wt.%, B: 0.04~0.07wt%, balance Al.

[0038] Ti / B=0.15~0.25, (Ti+B) / (Mg+Si) = 0.052.

[0039] Example 8 Al-Mg-Si alloy, wherein the alloy comprises the following components by mass percentage: Mg: 0.2~0.9wt%, Si: 0.2~0.9wt%, Mg+Si=1.0wt%, Al-5Ti-0.2B refining agent: 0.2~0.6wt%, other elements: Fe: ≤0.12wt.%, Cu: ≤0.031wt.%, Mn: ≤0.02wt.%, Zn: ≤0.02wt.%, B: 0.04~0.07wt%, balance Al.

[0040] Ti / B=0.15~0.25, (Ti+B) / (Mg+Si) = 0.055.

[0041] Example 9 Al-Mg-Si alloy, wherein the alloy comprises the following components by mass percentage: Mg: 0.2~0.9wt%, Si: 0.2~0.9wt%, Mg+Si=1.0wt%, Al-5Ti-0.2B refining agent: 0.2~0.6wt%, other elements: Fe: ≤0.12wt.%, Cu: ≤0.031wt.%, Mn: ≤0.02wt.%, Zn: ≤0.02wt.%, B: 0.04~0.07wt%, balance Al.

[0042] Ti / B=0.15~0.25, (Ti+B) / (Mg+Si) = 0.057.

[0043] Example 10 Al-Mg-Si alloy, wherein the alloy comprises the following components by mass percentage: Mg: 0.2~0.9wt%, Si: 0.2~0.9wt%, Mg+Si=1.0wt%, Al-5Ti-0.2B refining agent: 0.2~0.6wt%, other elements: Fe: ≤0.12wt.%, Cu: ≤0.031wt.%, Mn: ≤0.02wt.%, Zn: ≤0.02wt.%, B: 0.04~0.07wt%, balance Al.

[0044] Ti / B=0.15~0.25, (Ti+B) / (Mg+Si) = 0.06.

[0045] Example 11 Al-Mg-Si alloy, wherein the alloy comprises the following components by mass percentage: Mg: 0.2-0.9 wt%, Si: 0.2-0.9 wt%, Mg+Si=1.0 wt%, Al-5Ti-0.2B refining agent: 0.2-0.6 wt%, other elements: Fe: ≤0.12 wt.%, Cu: ≤0.031 wt.%, Mn: ≤0.02 wt.%, Zn: ≤0.02 wt.%, B: 0.04-0.07 wt%, balance Al.

[0046] Ti / B=0.15~0.25, (Ti+B) / (Mg+Si) = 0.07.

[0047] Example 12 Al-Mg-Si alloy, wherein the alloy comprises the following components by mass percentage: Mg: 0.2-0.9 wt%, Si: 0.2-0.9 wt%, Mg+Si=1.0 wt%, Al-5Ti-0.2B refining agent: 0.2-0.6 wt%, other elements: Fe: ≤0.12 wt.%, Cu: ≤0.031 wt.%, Mn: ≤0.02 wt.%, Zn: ≤0.02 wt.%, B: 0.04-0.07 wt%, balance Al.

[0048] Ti / B=0.15~0.25, (Ti+B) / (Mg+Si) = 0.09.

[0049] like Figure 1 , 3 As shown, the (Ti+B) / (Mg+Si) ratio, with a fixed (Mg+Si) content, exhibits completely different performance characteristics depending on the amount of (Ti+B). Tensile strength initially increases and then decreases with increasing (Ti+B) / (Mg+Si) ratio. This is because when the (Ti+B) / (Mg+Si) ratio is small, the content of Al3Ti and TiB2 in the material is low. During cold drawing, high-density dislocations form around the particles, thus increasing the tensile strength. However, with low particle content, the internal dislocation density is low, resulting in lower tensile strength. When the ratio is slightly higher, the excess (Ti+B) reacts with Si in the alloy, consuming the internal strengthening element Si, leading to a decrease in the amount of the strengthening phase Mg2Si, and a slight decrease in material strength. Since the (Ti+B) content is relatively small compared to (Mg+Si), although it affects the material strength, the fluctuation in strength is not significant.

[0050] However, the (Ti+B) / (Mg+Si) ratio has a significant impact on the material's electrical conductivity. In this alloy system, if the (Ti+B) / (Mg+Si) ratio is small, the particle content is too low during melting and solidification, the refining effect of the refining agent is weakened, the material's forming performance deteriorates, and defects are prone to occur during drawing. Furthermore, the internal impurity atoms are not completely consumed by B. During aging, these impurity elements not only hinder the formation of the precipitated Mg2Si phase but also increase the electron scattering rate by remaining free in the matrix. Therefore, when the (Ti+B) / (Mg+Si) ratio is small, the material's electrical conductivity decreases significantly. Figure 2 As shown, when the (Ti+B) / (Mg+Si) ratio is greater than 0.5, the material's electrical conductivity is significantly improved and relatively stable. Therefore, considering both the strength and electrical conductivity requirements of the material, it is believed that the material with (Ti+B) / (Mg+Si) = 0.04 to 0.06 has the best performance.

[0051] In a preferred but non-limiting embodiment of the present invention, the Mg / Si mass ratio is 1 to 1.05. The present invention controls the Mg / Si ratio to be around 1. Currently, in the synthesis of wrought aluminum alloys, to optimize material performance and increase the precipitate formation rate, the Mg / Si ratio is relatively large, aiming to generate Mg2Si precipitates as much as possible. However, because Si atoms have low solid solubility in materials, increasing the Si content, while improving material strength, severely impairs electrical conductivity as Si atoms cannot fully precipitate. Therefore, the Mg / Si ratio in electrical aluminum rods is generally around 1.3. The Mg / Si ratio described in this invention, achieved through a secondary aging process, can achieve high-density dislocations, promoting precipitate formation and allowing for complete desolvation of solid-solution atoms. Therefore, under this process, appropriately increasing the Si atom ratio allows the material to maintain high strength without compromising electrical conductivity, thus improving the overall material performance.

[0052] In a preferred but non-limiting embodiment of the present invention, the B / Fe mass ratio is 0.5 to 0.6. B can form borides with transition metal impurities, and borination treatment reduces the harmful effects of impurities, thereby improving the electrical conductivity of the material. Since Fe easily forms coarse needle-like AlFeSi phases in aluminum alloys, these phases can disrupt the matrix, leading to decreased conductivity and stress concentration. However, when B / Fe > 0.43, B combines with Fe to form fine and dispersed Fe2B phases, which are uniformly distributed in the matrix. Furthermore, to eliminate other transition elements such as Mn, V, and Cr, the B / Fe ratio needs to be controlled at 0.5 to 0.6.

[0053] Another embodiment of the present invention discloses a short-process deformation aging method for preparing a high-strength and high-conductivity Al-Mg-Si alloy, comprising the following steps: Step 1, Smelting: Industrial pure aluminum, Al-3%B master alloy, Al-10%Mg master alloy and Al-12%Si master alloy are added to a reaction vessel for smelting to obtain a melt. After adding Al-5Ti-0.2B refining agent to the melt, it is cast into a steel mold to obtain an aluminum alloy ingot. In a preferred but non-limiting embodiment of the present invention, step 1 specifically includes: Step 1.1: Place industrial pure aluminum and Al-3%B master alloy into a graphite clay crucible in the proportion specified in the composition design, heat to 720-750℃ in a pit-type crucible melting furnace to melt, and stir to mix them thoroughly. Preferably, the alkali metal content in the Al-3%B master alloy is less than 0.1%, the mass fraction of Al-3%B master alloy added is 1 to 1.65%, and the composition of the industrial pure aluminum is 99.85%.

[0054] Step 1.2: Continue to add Al-10%Mg master alloy and Al-12%Si master alloy to alloy it, and hold it at the temperature for 20-30 minutes to allow it to react fully; Preferably, the mass fractions of the Al-10%Mg master alloy and the Al-12%Si master alloy added are 3.5-4.5% and 4-5%, respectively.

[0055] Step 1.3: Add Al-5Ti-0.2B refining agent before pouring and stir for 1 minute. When the melt temperature is 720-750℃, pour it into the steel mold. The refining agent described in this invention can better exert its effect when added before casting. Adding the refining agent within a very short time before casting (usually within a few minutes) minimizes the time the effective particles of the refining agent are exposed to the high-temperature melt, significantly reducing the possibility of dissolution, aggregation, floating / sinking, and adverse reactions with the melt / environment. With sufficient stirring to ensure uniform distribution throughout the melt (usually requiring short, thorough stirring after addition), a large number of uniformly distributed effective nucleation sites are guaranteed in the melt at the beginning of solidification, ensuring sufficient dispersion. It can then effectively exert its effect immediately upon cooling the melt to the nucleation temperature.

[0056] It is worth noting that all raw materials in step 1 must be dried in a drying oven for 30-60 minutes before smelting. The order of addition of the raw materials is as follows: Al-3%B master alloy and industrial pure aluminum are heated simultaneously for borination and impurity removal in the early stage of smelting; then Al-12%Si master alloy and Al-10%Mg master alloy are added simultaneously; and Al-5Ti-0.2B refining agent is added before final casting to eliminate the influence of alloying elements on the reaction. The difference in thermal expansion between the refining agent particles and the matrix (thermal mismatch) induces the generation of a large number of dislocations. These dislocations can serve as rapid diffusion channels for solid solution atoms, accelerating their diffusion and precipitation, thereby reducing the concentration of harmful solid solution atoms.

[0057] Step 2, Homogenization Annealing: Place the aluminum alloy ingot obtained in Step 1 in a muffle furnace and anneal it at a set temperature; In a preferred but non-limiting embodiment of the present invention, the set temperature is 540-570°C, and the homogenization annealing is carried out by holding the temperature for 12-24 hours. After the holding temperature is completed, the furnace is cooled. When the temperature drops to 250-300°C, the furnace is taken out and air-cooled to prevent the coarsening of the precipitated phase. Step 3, Hot Extrusion: The cooled aluminum alloy ingot from Step 2 is extruded using a hot extrusion press to obtain aluminum rods; In a preferred but non-limiting embodiment of the present invention, the aluminum alloy ingot after homogenization and annealing is preheated to 350-400°C and then extruded using a hot extrusion press with an extrusion ratio of 36 and an extrusion speed of 2-10 min / s.

[0058] Step 4, Short-process deformation aging preparation: The aluminum rod obtained in Step 3 is subjected to solution treatment, first-stage artificial aging treatment, wire drawing and second-stage artificial aging treatment to obtain the high-strength and high-conductivity Al-Mg-Si alloy.

[0059] In a preferred but non-limiting embodiment of the present invention, step 4 specifically includes: Step 4.1 Solution treatment: Heat the hot extrusion rod to 550-570℃ for solution treatment, hold for 30-60 minutes, and then quench in water at room temperature; It is worth noting that during solution treatment, the solution temperature and solution time must be strictly controlled to prevent recrystallization and coarsening of the hot-rolled structure.

[0060] Step 4.2, Level 1 Artificial Aging: After solution treatment, the bar material is quickly sent to an aging furnace for artificial aging treatment at a temperature of 150-190℃ for 0.5-12 hours. Step 4.3, Wire pulling: Pull the wire of the extrusion bar after the first stage of artificial aging to the specified size (equipment capacity: 10mm->0.9mm, pull to 2.9mm). Specifically, the 10mm rod is first pressed to a thickness of 3.7mm under conditions of 1-2% deformation and 5-10 m / s speed, and then pulled to a thickness of 2.9mm under conditions of 1-2% deformation and 5-10 m / s speed.

[0061] Step 4.4, Secondary artificial aging: Artificial aging is performed on the 2.9mm wire after drawing. The artificial aging temperature is 150-190℃ and the time is 0.5-12h. In a preferred but non-limiting embodiment of the present invention, the secondary artificial aging period can be replaced by a natural aging period, wherein the natural aging period is one week.

[0062] The first-stage artificial aging process desolves solid solution atoms to form a large number of precipitates. Then, large deformation introduces texture and numerous dislocations to enhance strength. Finally, a second-stage artificial aging process restores the dislocations and promotes further precipitation of solid solution atoms, thus improving the material's electrical conductivity while maintaining its high strength. This approach prevents coarsening of the precipitates to maintain their contribution to strength, while also utilizing the dislocation network itself to enhance material strength. The ultimate goal is to achieve a synergistic effect in simultaneously improving strength and electrical conductivity, enabling Al-Mg-Si alloy conductors to meet the performance requirements of all-aluminum alloy stranded wires for long-distance, long-span transmission lines.

[0063] It is known that high-density dislocations can effectively improve the strength of materials with minimal impact on conductivity. Solid-solution atoms contribute little to strength but severely impair conductivity, while precipitation contributes significantly to relative strength but also damages conductivity. Therefore, the design of aluminum conductor materials must grasp this key point. By optimizing the fabrication process and controlling the distribution density of various defects in the conductor material, we can maximize the number of defects that contribute to strength enhancement and minimize defects that severely impair conductivity, ultimately obtaining a conductor material with both superior strength and conductivity.

[0064] In the first-stage artificial aging matrix, pre-existing dispersed precipitates (such as β) more effectively hinder dislocation movement, inducing higher density and more uniformly distributed dislocations (geometrically necessary dislocations) during room temperature deformation. In the second-stage artificial aging, these high-density dislocations act as rapid diffusion channels and potential nucleation sites, significantly accelerating the removal of Mg, Si, and other solid solution atoms remaining in the matrix after the first-stage artificial aging. This process preserves high-density dislocations while allowing for complete removal of solid solution atoms, thereby improving the material's strength and electrical conductivity.

[0065] Embodiments of the present invention also disclose the application of a high-strength, high-conductivity Al-Mg-Si alloy in power transmission lines.

[0066] Comparative Example 1 Comparative Example 1 discloses a method for preparing an Al-Mg-Si alloy based on T6 heat treatment, comprising the following steps: The composition by mass percentage is as follows: Mg: 0.2–0.9 wt%, Si: 0.2–0.9 wt%, Mg+Si: 0.9–1.5 wt%, Al-5Ti-0.2B refining agent: 0.2–0.6 wt%, other elements: Fe: ≤0.12 wt.%, Cu: ≤0.01 wt.%, Mn: ≤0.02 wt.%, Zn: ≤0.02 wt.%, B: 0.04–0.07 wt%, with the balance being Al.

[0067] Step (1) Melting: a. Place industrial pure aluminum and Al-3%B master alloy in a graphite clay crucible in the proportion specified in the composition design, heat to 750℃ in a pit-type crucible melting furnace and stir to mix them thoroughly; b. Alloy it with Al-10%Mg master alloy and Al-12%Si master alloy; c. Hold for 30 minutes to allow it to react fully; d. Add Al-5Ti-0.2B refining agent before casting and stir for 1 minute; e. Cast it into a steel mold when the melt temperature is 720℃. Step (2) Solution treatment: Heat the hot extrusion rod to 560°C for solution treatment, hold for 30 minutes, and then quench in water at room temperature; Step (3) Pre-deformation: The deformation amount is 10%.

[0068] Step (4) Artificial aging: After pre-deformation, the material is quickly sent to an aging furnace for artificial aging treatment at a temperature of 170°C for 3 hours.

[0069] Example 13 This embodiment 13 discloses a high-strength, high-conductivity Al-Mg-Si alloy and its short-process deformation aging preparation method. The alloy comprises the following components by weight proportions: The composition by mass percentage is as follows: Mg: 0.2–0.9 wt%, Si: 0.2–0.9 wt%, Mg+Si: 0.9–1.5 wt%, Al-5Ti-0.2B refining agent: 0.2–0.6 wt%, other elements: Fe: ≤0.12 wt.%, Cu: ≤0.01 wt.%, Mn: ≤0.02 wt.%, Zn: ≤0.02 wt.%, B: 0.04–0.07 wt%, with the balance being Al.

[0070] Step (1) Melting: a. Place industrial pure aluminum and Al-3%B master alloy in a graphite clay crucible in the proportion specified in the composition design, heat to 750℃ in a pit-type crucible melting furnace and stir to mix them thoroughly; b. Alloy it with Al-10%Mg master alloy and Al-12%Si master alloy; c. Hold for 30 minutes to allow it to react fully; d. Add Al-5Ti-0.2B refining agent before casting and stir for 1 minute; e. Cast it into a steel mold when the melt temperature is 720℃. Step (2) Homogenization annealing: The ingot is held at 570℃ for 14 hours in a muffle furnace for homogenization annealing. After the holding period, it is cooled with the furnace. When the temperature drops to 250℃, it is taken out and air-cooled to prevent coarsening of the precipitates. Step (3) Hot extrusion: After homogenization and annealing, the ingot is preheated to 380°C and then extruded using a hot extrusion press. The extrusion ratio is 36 and the extrusion speed is 5 min / s. Step (4) Solution treatment: Heat the hot extruded rod to 560℃ for solution treatment, hold for 30 minutes, and then quench in water at room temperature; Level 1 artificial aging: After solution treatment, quickly send the rod to an aging furnace for artificial aging treatment at 170℃ for 6 hours; Wire drawing: Wire drawing of the artificially aged extruded rod to the specified size (equipment capacity: 10mm->0.9mm, drawing to 2.9mm); Natural aging: Natural aging of the 2.9mm wire after drawing for one week at room temperature.

[0071] Example 14 This embodiment 14 discloses a high-strength, high-conductivity Al-Mg-Si alloy and its short-process deformation aging preparation method. The alloy comprises the following components by weight proportions: The composition by mass percentage is as follows: Mg: 0.2–0.9 wt%, Si: 0.2–0.9 wt%, Mg+Si: 0.9–1.5 wt%, Al-5Ti-0.2B refining agent: 0.2–0.6 wt%, other elements: Fe: ≤0.12 wt.%, Cu: ≤0.01 wt.%, Mn: ≤0.02 wt.%, Zn: ≤0.02 wt.%, B: 0.04–0.07 wt%, with the balance being Al.

[0072] Step (1) Melting: a. Place industrial pure aluminum and Al-3%B master alloy in a graphite clay crucible in the proportion specified in the composition design, heat to 750℃ in a pit-type crucible melting furnace and stir to mix them thoroughly; b. Alloy it with Al-10%Mg master alloy and Al-12%Si master alloy; c. Hold for 30 minutes to allow it to react fully; d. Add Al-5Ti-0.2B refining agent before casting and stir for 1 minute; e. Cast it into a steel mold when the melt temperature is 720℃. Step (2) Homogenization annealing: The ingot is held at 570℃ for 14 hours in a muffle furnace for homogenization annealing. After the holding period, it is cooled with the furnace. When the temperature drops to 250℃, it is taken out and air-cooled to prevent coarsening of the precipitates. Step (3) Hot extrusion: After homogenization and annealing, the ingot is preheated to 380°C and then extruded using a hot extrusion press. The extrusion ratio is 36 and the extrusion speed is 5 min / s. Step (4) Solution treatment: Heat the hot extruded rod to 560℃ for solution treatment, hold for 30 minutes, and then quench in water at room temperature; First-level artificial aging: After solution treatment, quickly send the rod to an aging furnace for artificial aging treatment at 170℃ for 6 hours; Wire drawing: Wire draw the artificially aged extruded rod to the specified size (equipment capacity: 10mm->0.9mm, drawing to 2.9mm); Second-level artificial aging: Artificially age the 2.9mm wire at 170℃ for 2 hours.

[0073] Example 15 This embodiment 15 discloses a high-strength, high-conductivity Al-Mg-Si alloy and its short-process deformation aging preparation method. The alloy comprises the following components by weight proportions: The composition by mass percentage is as follows: Mg: 0.2–0.9 wt%, Si: 0.2–0.9 wt%, Mg+Si: 0.9–1.5 wt%, Al-5Ti-0.2B refining agent: 0.2–0.6 wt%, other elements: Fe: ≤0.12 wt.%, Cu: ≤0.01 wt.%, Mn: ≤0.02 wt.%, Zn: ≤0.02 wt.%, B: 0.04–0.07 wt%, with the balance being Al.

[0074] Step (1) Melting: a. Place industrial pure aluminum and Al-3%B master alloy in a graphite clay crucible in the proportion specified in the composition design, heat to 750℃ in a pit-type crucible melting furnace and stir to mix them thoroughly; b. Alloy it with Al-10%Mg master alloy and Al-12%Si master alloy; c. Hold for 30 minutes to allow it to react fully; d. Add Al-5Ti-0.2B refining agent before casting and stir for 1 minute; e. Cast it into a steel mold when the melt temperature is 720℃. Step (2) Homogenization annealing: The ingot is held at 570℃ for 14 hours in a muffle furnace for homogenization annealing. After the holding period, it is cooled with the furnace. When the temperature drops to 250℃, it is taken out and air-cooled to prevent coarsening of the precipitates. Step (3) Hot extrusion: After homogenization and annealing, the ingot is preheated to 380°C and then extruded using a hot extrusion press. The extrusion ratio is 36 and the extrusion speed is 5 min / s. Step (4) Solution treatment: Heat the hot extruded rod to 560℃ for solution treatment, hold for 30 minutes, and then quench in water at room temperature; First-level artificial aging: After solution treatment, quickly send the rod to an aging furnace for artificial aging treatment at 170℃ for 6 hours; Wire drawing: Wire draw the artificially aged extruded rod to the specified size (equipment capacity: 10mm->0.9mm, drawing to 2.9mm); Second-level artificial aging: Artificially age the 2.9mm wire at 170℃ for 4 hours.

[0075] In summary, Comparative Example 1 uses the T6 heat treatment process; Example 13 uses the short-process deformation aging treatment described in this invention, with natural aging used for the secondary artificial aging; and Examples 14 and 15 use different artificial aging times for the secondary artificial aging process. Figure 4-5 As shown, compared with Comparative Example 1, it can be seen that the process described in this embodiment of the invention significantly improves the strength of the material from the T6 state, increasing the tensile strength of the material from 249.3 MPa in the T6 state to 300-370 MPa. According to Figure 6 As shown, compared with Comparative Example 1, it can be seen that the short-process preparation technology described in Examples 13-15 of this invention significantly improves the conductivity of the material, providing a new approach for preparing high-conductivity and high-strength Al-Mg-Si alloys.

[0076] Compared with the prior art, the beneficial effects of the present invention include at least the following: 1. This invention uses Al-5Ti-0.2B as a refining agent. The dominant refining phase of Al-5Ti-0.2B is TiAl3 + a small amount of TiB2. The TiAl3 phase (content > 4wt%) in Al-5Ti-0.2B provides a large number of heterogeneous nucleation cores, directly matching the peritectic solidification path of low-alloy aluminum alloys. Furthermore, the TiAl3 phase can avoid the poisoning effect of high-alloy elements. In addition, by limiting the ratio of Ti / B and (Ti+B) / (Mg+Si), this invention solves the problem that after the impurity elements are borated, there is no excess B element reacting with the Al3Ti particles in Al-5Ti-0.2B, thus ensuring that the refining agent effect of Al-5Ti-0.2B is not affected, and further improving the strength and electrical conductivity of the alloy material. 2. The present invention proposes a short-process deformation aging preparation method based on the addition of a refining agent, namely a two-stage aging process of aging + deformation + aging. This method can maximize the improvement of material performance. On the basis of the first-stage artificial aging and desolvation, the deformation process introduces a large number of dislocations to improve strength. In the second-stage aging process, the high-density dislocations can fully desolvate solid solution atoms with the extension of aging time, reducing their damage to conductivity. Moreover, the desolvation efficiency of solid solution atoms by artificial aging is significantly higher than that of natural aging.

[0077] 3. The high-strength and high-conductivity Al-Mg-Si alloy of this invention is closely integrated with the traditional aluminum alloy preparation process, is easy to promote, and has low cost, and can be mass-produced. The prepared aluminum alloy has excellent mechanical properties while maintaining high electrical conductivity. The material can maintain a tensile strength of over 360MPa and an electrical conductivity of over 54%IACS, and can be used to prepare high-strength and high-conductivity transmission conductors.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A high-strength, high-conductivity Al-Mg-Si alloy, characterized in that, The composition includes the following components by mass percentage: Mg: 0.2–0.9 wt%, Si: 0.2–0.9 wt%, Mg+Si: 0.9–1.5 wt%, Al-5Ti-0.2B refining agent: 0.2–0.6 wt%, other elements: Fe: ≤0.12 wt.%, Cu: ≤0.01 wt.%, Mn: ≤0.02 wt.%, Zn: ≤0.02 wt.%, B: 0.04–0.07 wt%, with the balance being Al; the Ti / B ratio is 0.15–0.25, and the (Ti+B) / (Mg+Si) ratio is 0.04–0.

06.

2. The high-strength, high-conductivity Al-Mg-Si alloy according to claim 1, characterized in that: The mass ratio of Mg to Si is 1 to 1.05, and the mass ratio of B to Fe is 0.5 to 0.

6.

3. A method for preparing a high-strength, high-conductivity Al-Mg-Si alloy according to any one of claims 1-2, characterized in that, Includes the following steps: Step 1: Add industrial pure aluminum, Al-3%B master alloy, Al-10%Mg master alloy and Al-12%Si master alloy to a reaction vessel for melting to obtain a melt. Add Al-5Ti-0.2B refining agent to the melt and pour it into a steel mold to obtain an aluminum alloy ingot. Step 2: Anneal the aluminum alloy ingot obtained in Step 1 at a set temperature; Step 3: The aluminum alloy ingot after annealing and cooling in Step 2 is extruded using a hot extrusion press to obtain aluminum rods; Step 4: The aluminum rod obtained in Step 3 is subjected to solution treatment, first-stage artificial aging treatment, wire drawing and second-stage artificial aging treatment in sequence to obtain the high-strength and high-conductivity Al-Mg-Si alloy.

4. The method for preparing the high-strength, high-conductivity Al-Mg-Si alloy according to claim 3, characterized in that, In step 1, the order of adding raw materials is as follows: Al-3%B master alloy and industrial pure aluminum are heated simultaneously, then Al-12%Si master alloy and Al-10%Mg master alloy are added, and finally Al-5Ti-0.2B refining agent is added before casting.

5. The method for preparing the high-strength, high-conductivity Al-Mg-Si alloy according to claim 3, characterized in that, In step 2, the set temperature is 540-570℃, and the temperature is held for 12-24 hours for homogenization annealing. After the holding period, the furnace is cooled down to 250-300℃, and then the furnace is taken out and air-cooled.

6. The method for preparing the high-strength, high-conductivity Al-Mg-Si alloy according to claim 3, characterized in that, In step 3, the aluminum alloy ingot after homogenization and annealing is preheated to 350-400℃ and then extruded using a hot extrusion press with an extrusion ratio of 36 and an extrusion speed of 2-10 min / s.

7. The method for preparing the high-strength, high-conductivity Al-Mg-Si alloy according to claim 3, characterized in that, In step 4, the solution treatment involves heating the hot extrusion rod to 550–570°C for solution treatment, holding it at that temperature for 30–60 minutes, and then water quenching it at room temperature.

8. The method for preparing the high-strength, high-conductivity Al-Mg-Si alloy according to claim 3, characterized in that, In step 4, the first-level artificial aging treatment involves sending the rod material to an aging furnace for artificial aging treatment. The artificial aging temperature is 150-190℃, and the artificial aging time is 0.5-12 hours.

9. The method for preparing the high-strength, high-conductivity Al-Mg-Si alloy according to claim 3, characterized in that, In step 4, the secondary artificial aging treatment is to perform either artificial aging treatment or natural aging treatment on the drawn wire. The artificial aging temperature is 150-190℃, the artificial aging time is 0.5-12h, the natural aging time is 5-7 days, and the natural aging temperature is room temperature.

10. The application of a high-strength, high-conductivity Al-Mg-Si alloy according to any one of claims 1-2 in power transmission conductors.

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