High-conductivity and high-strength aluminum alloy material as well as heat treatment method, preparation method and application thereof

Abstract

The invention belongs to the technical field of aluminum alloy, and particularly discloses a high-conductivity and high-strength aluminum alloy material and a heat treatment method, a preparation method and application thereof. The heat treatment method comprises solid solution quenching treatment, high-temperature short-time aging treatment, pre-aging treatment and aging treatment. The preparation method comprises the steps of smelting, casting and heat treatment, and the heat treatment comprises the heat treatment method. The high-conductivity and high-strength aluminum alloy material is prepared by the preparation method. The high-conductivity and high-strength aluminum alloy material is applied to preparation of wires and cables. Through process improvement, the aluminum alloy material with high conductivity and tensile strength can be prepared.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy technology, specifically a high-conductivity and high-strength aluminum alloy material, its heat treatment method, preparation method, and application. Background Technology

[0002] While current mainstream steel-cored aluminum stranded wires can meet basic requirements, their line loss rate (approximately 6%–8%) and mechanical properties are insufficient for ultra-high voltage and ultra-long-distance power transmission scenarios. The next generation of aluminum alloy conductor materials needs to simultaneously achieve breakthroughs in key technical indicators such as conductivity (≥62% IACS), tensile strength (≥110MPa), and elongation (≥10%). This requires achieving a 15%–20% reduction in line loss compared to traditional materials, while also meeting the mechanical requirements of large spans in complex terrain (such as spans exceeding 2000 meters across the Yangtze and Yellow Rivers) and extreme climates (wind pressure reaching 1.5kN / m² in coastal typhoon zones).

[0003] Currently, the industry has developed a series of products, including medium-strength (58% IACS / 160MPa), high-strength (60% IACS / 230MPa) and heat-resistant (strength retention rate >90% at 150℃). However, the conductivity is relatively low, resulting in a large amount of energy loss during use. There is an urgent need in industry for aluminum alloy wires that combine high conductivity and high strength.

[0004] Chinese patent CN120425282A discloses a heat treatment method for high-strength, high-conductivity magnesium-aluminum alloys, including surface cleaning, preheating, rapid heating to solution temperature, solution holding, quenching and cooling, post-quenching cold treatment, two-stage aging treatment, and slow cooling after aging. The first stage of the two-stage aging treatment has an aging temperature of 150℃–180℃ and a holding time of 3–5 hours; the second stage has an aging temperature of 200℃–230℃ and a holding time of 8–12 hours. This patent has the following drawbacks: 1. The solution treatment time is too long, resulting in high industrial costs; 2. The two-stage aging process is difficult to operate, and the second stage aging time is long, with a total aging time of 11–17 hours; 3. Chemical cleaning agents may cause potential industrial pollution. Summary of the Invention

[0005] The purpose of this invention is to provide a heat treatment method for high-conductivity and high-strength aluminum alloy materials. Through process improvement, this method solves the technical problem of the lack of existing processes for preparing aluminum alloy materials with both high conductivity and tensile strength. The aging process of this invention is simple, energy-efficient, and the final product is a wire, which meets the needs of practical production and industry.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A heat treatment method for a high-conductivity, high-strength aluminum alloy material includes:

[0008] (a) Solution treatment;

[0009] (b) High-temperature short-time aging treatment: keep at 450-600℃ for 5-10 minutes;

[0010] (c) Pre-aging treatment: keep at 200-400℃ for 6-12 hours;

[0011] (d) Time-sensitive processing.

[0012] Preferably, in step (a), the solution treatment includes: maintaining the temperature at 540–560°C for 2–6 hours.

[0013] Preferably, in step (c), the pre-aging treatment is followed by cold working.

[0014] Preferably, the cold working process includes cold rolling and cold drawing, and the finished product is a wire with a diameter of 2 to 3 mm and a total deformation of 93.75% to 97.22%.

[0015] Preferably, in step (d), the aging treatment includes: keeping warm at 240-280°C for 8-12 hours.

[0016] The second objective of this invention is to provide a method for preparing a high-conductivity, high-strength aluminum alloy material, comprising the following steps:

[0017] S1: Smelting;

[0018] S2: Casting;

[0019] S3: Heat treatment: The heat treatment method described above shall be adopted.

[0020] Preferably, in step S1, the smelting includes: heating the aluminum ingot to complete melting, then sequentially adding Al-Mg, Al-Si, Al-B master alloys and rare earth RE for smelting to obtain an aluminum alloy liquid.

[0021] Preferably, in step S1, the melting temperature is 720–750°C.

[0022] Preferably, in step S1, each intermediate alloy is stirred for 5-10 minutes and then left to stand for 5-10 minutes.

[0023] Preferably, the process also includes refining, which includes: adding a refining agent to the molten aluminum alloy obtained by smelting, stirring for 5 to 10 minutes, and then removing slag to obtain a high-purity molten aluminum alloy.

[0024] Preferably, the refining agent is hexachloroethane.

[0025] Preferably, the amount of the refining agent added is 0.5% to 1% of the melt weight.

[0026] Preferably, the obtained high-purity aluminum alloy liquid is kept at 720-750°C for 20-60 minutes.

[0027] Preferably, in step S2, the casting includes: pouring high-purity aluminum alloy liquid into a mold that has been preheated to 200-300°C, and then naturally cooling it to room temperature to form an aluminum alloy electrical rod.

[0028] The third objective of this invention is to provide a high-conductivity, high-strength aluminum alloy material, wherein, by weight percentage, its raw material composition includes: Mg 0.6–0.8 wt%, Si 0.4–0.6 wt%, B 0.1–0.2 wt%, rare earth RE 0.1–0.2 wt%, Cr, Mn, V, and Ti totaling 0–0.0005 wt%, with the balance being Al and other unavoidable impurities; wherein the rare earth RE comprises at least one of La, Ce, Y, Sm, and Er.

[0029] The fourth objective of this invention is to provide the application of the aforementioned high-conductivity and high-strength aluminum alloy material in the preparation of wire and cable conductors.

[0030] The synergistic enhancement of the electrical and mechanical properties of aluminum alloy wire by the clusters and nascent cells in this invention is achieved through the following dual-mechanism linkage effect:

[0031] Firstly, there is the effect of secondary phase refinement and interface strengthening. During the high-temperature short-time aging plus pre-aging process, Mg and Si atoms in the supersaturated solid solution diffuse and aggregate, preferentially precipitating nanoscale β" phase (Mg5Si6) and a small amount of Mg2Si primary phase. These secondary phases, due to lattice mismatch, induce lattice distortion between the α-Al matrix and the secondary phase, forming a significant shear strain gradient. The precipitation strengthening effect induced by high-temperature short-time aging plus pre-aging further drives the increase of relative shear strain between the secondary phase and the matrix, prompting the secondary phase to be refined through mechanisms such as dislocation movement or grain boundary migration, and increasing the phase boundary density. The refined secondary phase not only improves the uniformity of the precipitated phase distribution, but also strengthens the matrix through the hindering effect of phase boundaries on dislocations, forming a composite strengthening mechanism of "fine grain strengthening + phase boundary strengthening".

[0032] Secondly, the matrix structure regulation and work hardening enhancement effect. High-temperature short-time aging plus pre-aging treatment significantly refines the matrix grain size by suppressing initial recrystallization and promoting competitive grain growth, while retaining the high-density dislocation structure. The refined matrix grains limit the space for dislocation climb, and high-density dislocations are difficult to eliminate through dynamic recovery mechanisms in subsequent rolling processes. Instead, the refined matrix grains provide more dislocation slip channels, making them more easily activated and participating in dislocation multiplication and interaction, thus significantly enhancing the work hardening effect.

[0033] Under the synergistic effect of high-temperature short-time aging and pre-aging, the alloy achieves a significant breakthrough in strength while maintaining high electrical conductivity. This is achieved by both hindering dislocation movement through refined secondary phases (precipitation strengthening) and enhancing deformation resistance through high-density dislocation structure (work hardening).

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] In the existing technology, after solution quenching, high-temperature short-time aging is not performed, and pre-aging is performed directly. During the pre-aging process, there are relatively few clusters and GP regions, the precipitation effect is weak, there are fewer stable phases β(Mg2Si), the interaction with dislocations is reduced in subsequent processing, the work hardening effect is weakened, and the conductivity is also low.

[0036] This invention employs high-temperature short-time aging after solution quenching. Within seconds, most of the excess vacancies after quenching are rapidly localized by clusters formed during the high-temperature short-time aging process, reducing point defects and facilitating rapid cluster nucleation. The β" phase, while exhibiting low scattering of free electrons, effectively hinders dislocation movement, making it crucial for the comprehensive improvement of material properties. Following high-temperature short-time aging, this invention allows for the formation of densely distributed Mg-rich nanoclusters in the subsequent pre-aging stage. Due to their similar chemical composition, these clusters readily transform into the β" phase. Subsequent pre-aging, machining, and aging treatments result in a fine and dispersed β" phase within the matrix, thereby comprehensively improving material properties and producing aluminum alloy materials with both high electrical conductivity and tensile strength. Attached Figure Description

[0037] Figure 1 This is a schematic flowchart illustrating the method for preparing aluminum alloy wires that combine high conductivity and tensile strength, as provided by the present invention.

[0038] Figure 2 This is a schematic diagram of the processing technology of the aluminum alloy wire of the present invention.

[0039] Figure 3 These are scanning electron microscope images of processing 1-3 in Embodiment 1 of the present invention.

[0040] Figure 4 This is a scanning electron microscope image of Comparative Example 1 of the present invention. Detailed Implementation

[0041] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0042] In the following examples / comparative examples of the present invention, all raw materials used were commercially available.

[0043] Example 1

[0044] A high-conductivity, high-strength aluminum alloy material, by weight percentage, comprises: Mg 0.6–0.8 wt%, Si 0.4–0.6 wt%, B 0.1–0.2 wt%, rare earth RE 0.1–0.2 wt%, Cr, Mn, V and Ti totaling 0–0.0005 wt%, with the balance being Al and other unavoidable impurities; wherein the rare earth RE contains at least one of La, Ce, Y, Sm and Er.

[0045] A heat treatment method for a high-conductivity, high-strength aluminum alloy material includes the following steps:

[0046] (a) Solution treatment: Keep at 540-560℃ for 2-6 hours;

[0047] (b) High-temperature short-time aging treatment: hold at 450-600℃ for 5-10 minutes;

[0048] (c) Pre-aging treatment: keep at 200-400℃ for 6-12 hours;

[0049] (d) Cold working: cold rolling and cold drawing, the finished product is a wire with a diameter of 2-3 mm, and the total deformation is 93.75%-97.22%;

[0050] (e) Aging treatment: Keep warm at 240-280℃ for 8-12 hours.

[0051] A method for preparing a high-conductivity, high-strength aluminum alloy material includes the following steps:

[0052] S1: Ingredients: Prepare the ingredients according to the above formula;

[0053] S2: Smelting: The aluminum ingot is heated to complete melting, and Al-Mg, Al-Si, Al-B master alloys and rare earth RE are added sequentially for smelting. Each time a master alloy is added, the mixture is stirred for 5-10 minutes and then allowed to stand for 5-10 minutes to obtain an aluminum alloy liquid. The smelting temperature is 720-750℃.

[0054] S3: Refining: Add hexachloroethane refining agent to the molten aluminum alloy obtained by smelting, stir for 5-10 minutes, and then remove slag to obtain high-purity aluminum alloy liquid. The high-purity aluminum alloy liquid is then kept at 720-750℃ for 20-60 minutes. The amount of refining agent added is 0.5%-1% of the weight of the molten alloy.

[0055] S4: Casting: High-purity aluminum alloy liquid is poured into a mold that has been preheated to 200-300°C, and then allowed to cool naturally to room temperature to form an aluminum alloy electrical rod.

[0056] S5: Heat treatment: The aluminum alloy electrical round rod is heat treated using the heat treatment method described above.

[0057] Application of a high-conductivity, high-strength aluminum alloy material in the preparation of wire and cable conductors.

[0058] Referring to the heat treatment method, preparation method and raw material formula provided above, different treatment groups were set up with the specific treatment processes of high temperature short-time aging and pre-aging as variables, as shown in Table 1, to investigate the influence of this variable on the properties of the prepared high conductivity and high strength aluminum alloy material.

[0059] Table 1

[0060]

[0061] Example 2

[0062] Referring to the raw material formulation, heat treatment method, preparation method, and settings of treatments 1-3 provided in Example 1, different treatment groups were set up with whether or not B and La were added as variables, as shown in Table 2, to investigate the effect of these variables on the properties of the prepared high-conductivity and high-strength aluminum alloy material.

[0063] Table 2

[0064]

[0065] Note: If B and / or La are lacking in the raw materials, the preparation process should be adjusted accordingly.

[0066] Comparative Example 1

[0067] The heat treatment process of "solution water quenching - machining - aging" is as follows: hold at 560℃ for 2 hours, immediately water quench, machine into Φ2mm wire with a deformation of 97.22%, and then isothermally age at 260℃ for 12 hours.

[0068] Comparative Example 2

[0069] Commercially available industrial pure aluminum conductor, purchased from Chenghang Cable Co., Ltd., model BLV.

[0070] Comparative Example 3

[0071] The commercially available 8-series aluminum alloy conductor was purchased from Jiangsu Shangshang Cable Group Co., Ltd., model number ZC-TC90.

[0072] Comparative Example 4

[0073] The commercially available 6-series aluminum alloy wire was purchased from Hebei Hualun Cable Co., Ltd., model LHA2.

[0074] Performance testing experiment

[0075] 1. The test items and testing standards are shown in Table 3:

[0076] Table 3

[0077]

[0078] 2. The test results are shown in Table 4.

[0079] Table 4

[0080]

[0081] In Example 1, the high-temperature short-time aging treatment and pre-aging treatment temperatures and times for treatments 1-1 to 1-5 are all within the range defined by this invention, and the various indicators of the prepared materials can basically meet the standard requirements, or even exceed the standard requirements.

[0082] As the high-temperature short-time aging temperature increases, the size of the secondary phase increases, and the strengthening effect weakens. At 500℃, it exhibits good strength and conductivity, along with acceptable elongation. With increasing pre-aging temperature, the conductor strength shows a typical peak-aged alloy pattern: initially increasing and then decreasing. This is because the increased temperature during pre-aging leads to greater grain recrystallization, coarsening of the grains and secondary phase, and a shift in the precipitation strengthening mechanism from dislocations bypassing secondary phase particles to dislocations cutting through them, resulting in a weakened strengthening effect. Except for treatment 1-1, EC values ​​are all above 62 IACS%, falling into the high conductivity category. After the pre-aging temperature exceeds 250℃, conductivity shows a slow upward trend with increasing temperature, indicating that there is an upper limit to the extent that precipitation strengthening, by precipitating solid solution elements to reduce lattice distortion and electron scattering, can improve conductivity.

[0083] Treatment 1-6 lowers the high-temperature short-time aging temperature compared to Treatment 1-1. The excessively low temperature of the high-temperature short-time aging leads to a reduction in the number of solute clusters and GP regions, a reduction in the strengthening phase during the pre-aging process, and ultimately a decrease in mechanical properties.

[0084] Treatments 1-7 increased the high-temperature short-time aging temperature compared to treatments 1-5. However, the excessively high temperature of the high-temperature short-time aging process resulted in coarsening of the precipitated phase and a weakening of the strengthening effect.

[0085] Treatments 1-8 shorten the high-temperature short-time aging time compared to treatments 1-5. The insufficient high-temperature short-time aging time results in solute atoms not having enough time to diffuse and precipitate, reducing the number of GP regions and clusters, ultimately leading to a weakening of the strengthening effect.

[0086] Treatment 1-9 extends the high-temperature short-time aging time based on treatment 1-1. If the high-temperature short-time aging time is too long, it will have the same effect as excessive temperature, namely, a decrease in mechanical properties, which is also related to the coarsening of the precipitated phase.

[0087] Treatment 1-10 lowers the pre-aging temperature compared to Treatment 1-1. The reduction in pre-aging temperature results in insufficient precipitation of solute atoms in the matrix, with a large number of atoms remaining dissolved in the matrix. This weakens the interaction between the atoms and dislocations during machining, reduces the work hardening effect, and leads to a decrease in mechanical properties.

[0088] Treatment 1-11 increases the pre-aging temperature compared to treatment 1-5. If the pre-aging temperature is too high, it will cause severe coarsening of the precipitated phase in the matrix, the Orowan strengthening effect will disappear, and the mechanical properties will be severely reduced.

[0089] Treatment 1-12 shortens the pre-aging time compared to treatment 1-5. Insufficient pre-aging time, similar to the principle of lower pre-aging temperature, leads to the failure of solute atoms to precipitate in time, resulting in weakened work hardening effect and decreased mechanical properties. It is worth noting that the tensile strength of treatment 1-12 is better than that of treatment 1-10, indicating that the time has less impact on performance reduction than that of excessively low temperature.

[0090] Treatment 1-13 extends the pre-aging time compared to Treatment 1-1. The excessively long pre-aging time leads to coarsening of the precipitated phase and increased costs, which is not conducive to performance improvement and actual production.

[0091] Treatment 1-14, based on Treatment 1-3, eliminates the high-temperature short-time aging process. Excess vacancies after quenching facilitate rapid cluster nucleation during the high-temperature short-time aging process. The alloy treated with this process can form densely distributed Mg-rich nanoclusters in the subsequent pre-aging stage. After machining and during aging, these clusters, due to their similar chemical composition, are more prone to transforming into the β" phase. This is due to the integration of vacancies into atomic-scale clusters and the pre-modulation of the crystal structure induced by the GP region. These fine and dispersed β" phases are considered the reason for the overall improvement in aluminum alloy conductors. They reduce the scattering effect of lattice distortion on electrons, increasing conductivity; the dislocation multiplication caused during machining greatly increases the effect of work strengthening; and the effective inhibition of dislocation movement and matrix recrystallization during the final aging process improves mechanical properties.

[0092] Treatment 1-15, based on treatment 1-3, eliminates pre-aging. The GP region and solute clusters cannot be transformed into the β" phase, resulting in a weak ability to multiply dislocations and a decline in mechanical properties.

[0093] Comparative Example 1 illustrates the traditional process under optimal composition: "solution water quenching—machining—aging," highlighting the improved product performance of the novel process combination proposed in this invention compared to traditional processes. Comparative Examples 2-4 demonstrate that the aluminum alloy wires provided by this invention exhibit high strength and high conductivity compared to commercially available products.

[0094] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A heat treatment method for a high-conductivity, high-strength aluminum alloy material, characterized in that, include: (a) Solution quenching treatment; (b) High-temperature short-time aging treatment: keep at 450-600℃ for 5-10 minutes; (c) Pre-aging treatment: keep at 200-400℃ for 6-12 hours; (d) Time-sensitive processing.

2. The heat treatment method for high-conductivity and high-strength aluminum alloy materials as described in claim 1, characterized in that: In step (a), the solution quenching treatment includes: holding at 540-560℃ for 2-6 hours.

3. The heat treatment method for high-conductivity and high-strength aluminum alloy materials as described in claim 1, characterized in that: In step (c), cold working is performed after pre-aging treatment.

4. The heat treatment method for high-conductivity and high-strength aluminum alloy materials as described in claim 1, characterized in that: In step (d), the aging treatment includes: keeping the temperature at 240-280℃ for 8-12 hours.

5. A method for preparing a high-conductivity, high-strength aluminum alloy material, characterized in that, Includes the following steps: S1: Smelting; S2: Casting; S3: Heat treatment: The heat treatment method described in any one of claims 1 to 4 is employed.

6. The method for preparing the high-conductivity, high-strength aluminum alloy material as described in claim 5, characterized in that: In step S1, the smelting includes: heating the aluminum ingot to complete melting, then sequentially adding Al-Mg, Al-Si, Al-B master alloys and rare earth RE for smelting to obtain aluminum alloy liquid.

7. The method for preparing the high-conductivity, high-strength aluminum alloy material as described in claim 5, characterized in that: It also includes refining, which includes adding a refining agent to the molten aluminum alloy obtained by smelting, stirring and then removing slag to obtain a high-purity molten aluminum alloy.

8. The method for preparing the high-conductivity, high-strength aluminum alloy material as described in claim 5, characterized in that: In step S2, the casting includes: pouring molten aluminum alloy into a mold preheated to 200-300°C, and then allowing it to cool naturally to room temperature.

9. The aluminum alloy material prepared by the method for preparing high-conductivity and high-strength aluminum alloy material according to any one of claims 5-8, characterized in that, By weight percentage, its raw material composition includes: Mg 0.6-0.8wt%, Si 0.4-0.6wt%, B 0.1-0.2wt%, rare earth RE 0.1-0.2wt%, Cr, Mn, V and Ti summed to 0-0.0005wt%, with the balance being Al and other unavoidable impurities; wherein, the rare earth RE contains at least one of La, Ce, Y, Sm and Er.

10. The application of the high-conductivity, high-strength aluminum alloy material as described in claim 9 in the preparation of wire and cable conductors.

Images