A heat-resistant aluminum alloy, aluminum alloy wire and preparation method thereof

Abstract

The present invention belongs to the technical field of manufacturing nonferrous metals or alloys, and specifically discloses a heat-resistant conductive aluminum alloy, an aluminum alloy wire prepared therefrom, and a method for preparing the aluminum alloy and the wire. The alloy composition and mass percentage are: Nb 0.15-1.0%, Zr 0.1-0.5%, B 0.05-0.2%, Er≤0.3%, Y≤0.3%, and the balance is Al and unavoidable impurities, and the total amount of impurities is ≤0.1%. The manufacturing method includes material preparation, smelting and preparing aluminum alloy liquid, furnace refining, degassing and deslagging treatment, continuous casting and rolling, solid solution and aging treatment, drawing into wire, and annealing treatment. The heat-resistant aluminum alloy wire described in the present invention has the characteristics of high strength, good plasticity, high conductivity and excellent heat resistance, and is suitable for manufacturing aluminum alloy cables for urban power grid capacity expansion and long-distance large-capacity power transmission engineering construction, and has broad market application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of manufacturing nonferrous metals or alloys, and in particular relates to the processing and preparation of aluminum alloys, and specifically relates to a heat-resistant conductive aluminum alloy, an aluminum alloy wire and a preparation method thereof. Background Art

[0002] Aluminum is widely used in packaging, construction, transportation, electrical materials and many other fields due to its abundant resources, light weight, good mechanical properties, excellent corrosion resistance and electrical conductivity. Heat-resistant aluminum alloy wire refers to a conductor material that still has high mechanical properties at high temperatures and can be used within a certain temperature range. The heat resistance of the wire is mainly measured by the strength residual rate. The material is kept at a high temperature for a period of time, then cooled to room temperature for stretching. The ratio of its tensile strength to the tensile strength before insulation is the strength residual rate at this temperature. The highest temperature corresponding to the strength residual rate of 90% is used as an evaluation index for the heat resistance of aluminum alloy wires. With the rapid development of my country's economy, residential and industrial electricity consumption has increased dramatically, and the substantial increase in wire load has made the wire have strong thermal stability. At present, the tensile strength of the NRLH3 super heat-resistant aluminum alloy wire widely used in my country is 160MPa, which can be used for a long time at 210℃, but the conductivity is only 60%IACS, which makes it difficult to achieve a good match between conductivity and heat resistance. With the expansion and transformation of urban power grids in my country and the construction of long-distance and large-capacity transmission projects, there is an urgent need to develop new aluminum alloy conductors with high strength, high conductivity and high heat resistance. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides an aluminum alloy wire with high strength, good plasticity, high conductivity and excellent heat resistance and a preparation method thereof.

[0004] To achieve the above object, the complete technical solution of the present invention includes:

[0005] The heat-resistant aluminum alloy wire of the present invention is composed of the following components in mass percentage: Nb: 0.15-1.0%, Zr: 0.1-0.5%, B: 0.05-0.2%, Er≤0.3%, Y≤0.3%, the remainder is Al and inevitable impurities, and the total amount of impurities is ≤0.1%.

[0006] Preferably, the heat-resistant aluminum alloy wire of the present invention is composed of the following components in mass percentage: Nb: 0.20-0.60%, Zr: 0.20-0.40%, B: 0.05-0.15%, and the remainder is Al and unavoidable impurities, and the total amount of impurities is ≤0.1%.

[0007] Preferably, the heat-resistant aluminum alloy wire of the present invention is composed of the following components in mass percentage: Nb: 0.15-0.40%, Zr: 0.15-0.30%, B: 0.05-0.15%, Er: 0.10-0.25%, Y: 0.05-0.15%, and the balance is Al and unavoidable impurities, and the total amount of impurities is ≤0.1%.

[0008] The method for preparing the heat-resistant aluminum alloy wire of the present invention comprises the following steps:

[0009] (1) Industrial pure aluminum ingots, Al-5Nb alloy, Al-5Zr alloy, Al-3B alloy, Al-5Er alloy, and Al-5Y alloy are selected as raw materials and the ingredients are prepared according to the designed composition;

[0010] (2) heating industrial pure aluminum to melt at 700° C. to 750° C., and sequentially adding the above master alloys, and stirring the melted aluminum alloy sufficiently to make the composition of the aluminum alloy liquid uniform;

[0011] (3) subjecting the aluminum alloy liquid to a furnace refining, degassing and impurity removal treatment, and then continuously casting and rolling at 700° C. to 720° C. into aluminum alloy round rods;

[0012] (4) solution treating the aluminum alloy round rod at 580°C to 620°C for 20 to 35 hours, and then aging at 350°C to 450°C for 30 to 65 hours;

[0013] (5) The aluminum alloy round rod is drawn into an aluminum alloy wire, and finally annealed at 150° C. to 250° C. for 1 to 10 h to obtain a heat-resistant aluminum alloy conductor.

[0014] The beneficial effects of the present invention compared with the prior art are:

[0015] (1) Nb, which has a small diffusion coefficient in Al, is used as an important alloying element. After the preparation process is regulated, it forms particles with high thermal stability with other alloying elements, so that the wire can be used continuously at a higher temperature and the heat resistance of the aluminum alloy wire is improved. In order to ensure that the wire has sufficient strength, conductivity and heat resistance.

[0016] (2) Selecting an appropriate amount of Zr element to hinder grain boundary migration and dislocation movement, improve the stability of the substructure in the deformed structure, inhibit the rearrangement of dislocations at high temperatures to form large-angle grain boundaries, and cause the process of recrystallization nucleation and grain growth, so that the wire has good heat resistance. However, due to the large difference in atomic radius between Zr and Al, serious lattice distortion will occur during solid solution, which seriously reduces the conductivity of the aluminum alloy wire. Therefore, the present invention selects a suitable Zr element to improve the heat resistance without affecting the conductivity.

[0017] (3) Selecting rare earth elements Er and Y to promote the precipitation of solute atoms, reduce lattice distortion, and improve conductivity. Although Er and Y elements have been used in other reported heat-resistant conductive aluminum alloys, the present invention has found through a large number of comparative studies that the composite effect of Er, Y and Nb and Zr can promote the formation of Al3 (Nb, Zr) high thermal stability particles, reduce the coarsening rate of particles, and produce unexpected effects on the conductivity and heat resistance of aluminum alloys.

[0018] The room temperature tensile strength of the heat-resistant aluminum alloy conductor of the present invention is greater than 160 MPa, the conductivity is greater than 61% IACS, and the strength residual rate after being kept at 280° C. for 1 hour is greater than 90%. It has the characteristics of high strength, high conductivity and excellent heat resistance, is suitable for manufacturing aluminum alloy cables for capacity expansion of urban power grids and long-distance large-capacity power transmission engineering construction, and has broad market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a SEM image of the aluminum alloy wire in Example 1 of the present invention, wherein: Figure 1 (a) is the drawing annealing state, Figure 1 (b) is a heat resistance test at 280℃ / 1h, Figure 1 (c) is an enlarged view of the box in Figure a. Figure 1 (d) is the EDS element distribution diagram of Figure c.

[0020] Figure 2 1-4 are tensile curves of the heat-resistant aluminum alloy wires of Examples 1-4 of the present invention.

[0021] Figure 3 This is the IPF diagram of the aluminum alloy wire of Example 3 of the present invention: Figure 3 (a) is the drawing annealing state, Figure 3 (b) is a heat resistance test at 280°C / 1h. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only for illustration and are not intended to limit this application.

[0023] The heat-resistant aluminum alloy wire of the present invention is composed of the following components in mass percentage: Nb: 0.15-1.0%, Zr: 0.1-0.5%, B: 0.05-0.2%, Er≤0.3%, Y≤0.3%, the remainder is Al and inevitable impurities, and the total amount of impurities is ≤0.1%.

[0024] One of the components and its mass percentage is: Nb: 0.20-0.60%, Zr: 0.20-0.40%, B: 0.05-0.15%, the balance is Al and unavoidable impurities, and the total amount of impurities is ≤0.1%.

[0025] Among the above alloy components, the present invention first selects Nb with a small diffusion coefficient in Al and Zr elements used to hinder grain boundary migration and dislocation movement, and considers the synergistic effect of the two elements to improve the strength, conductivity and heat resistance of the aluminum alloy wire. Among them, the content of the two elements Nb and Zr relative to the overall alloy, and the proportional relationship between them are particularly important. Studies have found that Nb, as an important alloying element, forms particles with high thermal stability with other alloying elements after preparation process regulation, so that the wire can be used continuously at a higher temperature, thereby improving the heat resistance of the aluminum alloy wire. The Zr element can hinder grain boundary migration and dislocation movement, improve the stability of the substructure in the deformed organization, inhibit the rearrangement of dislocations at high temperatures to form large-angle grain boundaries, and cause the process of recrystallization nucleation and grain growth, so that the wire has good heat resistance. However, due to the large difference in atomic radius between Zr and Al, severe lattice distortion will occur during solid solution, which seriously reduces the conductivity of the aluminum alloy wire. Based on the above situation, after design and experimental verification, it is more preferred to make the ratio between the two W t(Nb) =(0.3~~2.4)W t(Zr) , where W t(Nb) is the mass percentage of Nb, W t(Zr) It is the mass percentage of Zr. It ensures that the wire has sufficient strength, conductivity and heat resistance.

[0026] Another component and its mass percentage are: Nb: 0.15-0.40%, Zr: 0.15-0.30%, B: 0.05-0.15%, Er: 0.10-0.25%, Y: 0.05-0.15%, and the balance is Al and unavoidable impurities, and the total amount of impurities is ≤0.1%.

[0027] In addition, the present invention selects rare earth elements Er and Y to promote the precipitation of solute atoms to reduce lattice distortion and improve electrical conductivity. Although Er and Y elements are used in other reported heat-resistant conductive aluminum alloys, the present invention finds through a large number of comparative studies that the composite effect of Er, Y and Nb and Zr can promote the formation of Al3 (Nb, Zr) high thermal stability particles, reduce the coarsening rate of particles, and produce unexpected effects on the electrical conductivity and heat resistance of aluminum alloys. In terms of component selection, W is preferably used. t(Nb) =(0.5~1.2)W t(Zr) In the case of W t(Er+Y) =(0.62~0.65)W t(Nb+Zr) , where Wt(Er+Y) is the mass percentage of Er and Y, W t(Nb+Zr) is the sum of the mass percentages of Nb and Zr. t(Er) =(1.5~1.6)W t(Y) , where W t(Er) is the mass percentage of Er, W t(Y) is the mass percentage of Y.

[0028] From the results, a large number of second phase particles were formed in the organization. Elemental analysis showed that the particles contained Al, Nb, and Zr elements. EDS quantitative analysis determined that they were Al3 (Nb, Zr) phases. The average size of the phase was It is 1.03-1.28μm. It can hinder the rearrangement of dislocations during heating, inhibit the movement of dislocations to form subgrain boundaries and then develop into large-angle grain boundaries, effectively increase the recrystallization temperature of the alloy, and enable the wire to work continuously at a higher temperature.

[0029] The present invention also provides a method for preparing the heat-resistant aluminum alloy wire, which specifically comprises the following steps:

[0030] (1) industrial pure aluminum ingots, Al-5Nb alloy, Al-5Zr alloy, Al-3B alloy, Al-5Er alloy, and Al-5Y alloy are selected as raw materials and proportioned according to predetermined target components;

[0031] (2) heating industrial pure aluminum to melt at 700° C. to 750° C., and sequentially adding the above master alloys, and stirring the melted aluminum alloy sufficiently to make the composition of the aluminum alloy liquid uniform;

[0032] (3) subjecting the aluminum alloy liquid to a furnace refining, degassing and impurity removal treatment, and then continuously casting and rolling at 700° C. to 720° C. into aluminum alloy round rods;

[0033] (4) solution treating the aluminum alloy round rod at 580°C to 620°C for 20 to 35 hours, and then aging at 350°C to 450°C for 30 to 65 hours;

[0034] (5) The aluminum alloy round rod is drawn into an aluminum alloy wire, and finally annealed at 150° C. to 250° C. for 1 to 10 h to obtain a heat-resistant aluminum alloy conductor.

[0035] In order to describe the preparation method of the heat-resistant aluminum alloy wire in the present invention in more detail, further explanation is given through the following examples.

[0036] Embodiment 1:

[0037] The heat-resistant aluminum alloy wire of the present invention is composed of the following components and mass percentages: Nb: 0.51%, Zr: 0.22%, B: 0.1%, the remainder being Al and unavoidable impurities, and the total amount of impurities is ≤ 0.1%. The preparation method of the heat-resistant aluminum alloy wire is as follows:

[0038] (1) Industrial pure aluminum ingots, Al-5Nb alloy, Al-5Zr alloy, and Al-3B alloy are selected as raw materials, and the ingredients are prepared according to Nb: 0.51%, Zr: 0.22%, B: 0.1%, and the balance is Al and unavoidable impurities;

[0039] (2) melting industrial pure aluminum at 750° C., and sequentially adding the above master alloys, and stirring the melted aluminum alloy sufficiently to make the composition of the aluminum alloy liquid uniform;

[0040] (3) subjecting the aluminum alloy liquid to furnace refining, degassing and impurity removal treatment, and then continuously casting and rolling at 720° C. into aluminum alloy round rods;

[0041] (4) The aluminum alloy round rod was solution treated at 580°C for 28 h and then aged at 350°C for 36 h;

[0042] (5) The aluminum alloy round rod is drawn into an aluminum alloy wire, and finally annealed at 200°C for 5h to obtain a heat-resistant aluminum alloy conductor.

[0043] The SEM structure of the aluminum alloy wire in this embodiment is as follows Figure 1 As shown in a, a large number of second phase particles are formed in the organization, and elemental analysis shows (such as Figure 1 c. Figure 1 d) The particles contain Al, Nb, and Zr elements. EDS quantitative analysis determined that they are Al3 (Nb, Zr) phases. The average size of this phase is 1.28 μm, which can hinder the rearrangement of dislocations during heating, inhibit the movement of dislocations to form subgrain boundaries and then develop into large-angle grain boundaries, effectively increase the recrystallization temperature of the alloy, and enable the wire to work continuously at higher temperatures. After the 280℃ / 1h heat resistance test, the second phase particles showed high thermal stability, and no obvious growth was observed, such as Figure 1 As shown in b. Figure 2 a is a typical tensile curve of the heat-resistant aluminum alloy wire of Example 1, and also shows the tensile curve after the 280℃ / 1h heat resistance test. Table 1 lists the specific data of tensile properties, conductivity and strength retention rate. It can be seen that the aluminum alloy wire of the present invention has a conductivity of up to 61.4% IACS, and can still maintain a strength retention rate of 90.5% under the 280℃ / 1h heat resistance test.

[0044] Embodiment 2:

[0045] The heat-resistant aluminum alloy wire of the present invention is composed of the following components and mass percentages: Nb: 0.35%, Zr: 0.25%, B: 0.1%, and the balance is Al and inevitable impurities, and the total amount of impurities is ≤ 0.1%. The preparation method of the heat-resistant aluminum alloy wire is as follows:

[0046] (1) Industrial pure aluminum ingots, Al-5Nb alloy, Al-5Zr alloy, and Al-3B alloy are selected as raw materials, and the ingredients are prepared according to Nb: 0.35%, Zr: 0.25%, B: 0.1%, and the balance is Al and unavoidable impurities;

[0047] (2) melting industrial pure aluminum at 700° C., and sequentially adding the above master alloys, and stirring the melted aluminum alloy sufficiently to make the composition of the aluminum alloy liquid uniform;

[0048] (3) subjecting the aluminum alloy liquid to furnace refining, degassing and impurity removal treatment, and then continuously casting and rolling at 700° C. into aluminum alloy round rods;

[0049] (4) The aluminum alloy round rod was solution treated at 600°C for 24 h and then aged at 375°C for 48 h;

[0050] (5) The aluminum alloy round rod is drawn into an aluminum alloy wire, and finally annealed at 150° C. for 3 h to obtain a heat-resistant aluminum alloy conductor.

[0051] The typical tensile curve of the heat-resistant aluminum alloy wire in this embodiment is as follows: Figure 2 b, and the specific performance data are shown in Table 1. The tensile strength, conductivity and 280℃ / 1h strength retention rate of the wire reached 166MPa, 61.2%IACS and 90.4% respectively.

[0052] Embodiment 3:

[0053] The heat-resistant aluminum alloy wire of the present invention is composed of the following components and mass percentages: Nb: 0.25%, Zr: 0.24%, B: 0.15%, Er0.19%, Y0.12%, the remainder being Al and unavoidable impurities, and the total amount of impurities is ≤0.1%. The preparation method of the heat-resistant aluminum alloy wire is as follows:

[0054] (1) Industrial pure aluminum ingots, Al-5Nb alloy, Al-5Zr alloy, Al-3B alloy, Al-5Er alloy, and Al-5Y alloy are selected as raw materials, and the ingredients are prepared according to Nb: 0.25%, Zr: 0.24%, B: 0.15%, Er: 0.19%, Y: 0.12%, and the balance is Al and unavoidable impurities;

[0055] (2) heating industrial pure aluminum to melt at 740° C., and sequentially adding the above master alloys, and stirring the melted aluminum alloy sufficiently to make the composition of the aluminum alloy liquid uniform;

[0056] (3) subjecting the aluminum alloy liquid to furnace refining, degassing and impurity removal treatment, and then continuously casting and rolling at 710° C. into aluminum alloy round rods;

[0057] (4) The aluminum alloy round rod was solution treated at 600°C for 28 h and then aged at 400°C for 42 h;

[0058] (5) The aluminum alloy round rod is drawn into an aluminum alloy wire, and finally annealed at 175° C. for 5 h to obtain a heat-resistant aluminum alloy conductor.

[0059] The second phase particles in the heat-resistant aluminum alloy wire structure of this embodiment mainly contain Al, Nb, Zr and a small amount of Er and Y elements. Analysis confirms that it is Al3 (Nb, Zr) phase and contains Er and Y elements in solid solution. Figure 3 Aluminum alloy wire drawing annealing state ( Figure 3 a) and after 280℃ / 1h heat resistance test ( Figure 3 b) shows that after the heat resistance test at 280℃ for 1h, the grains did not coarsen significantly. This is because the Al3(Nb,Zr) second phase can pin dislocations and grain boundaries, hindering the movement of dislocations during heating to form subgrain boundaries, while inhibiting the merging of subgrains and the growth of grains, thus improving the thermal stability of the conductor. Typical tensile curves of heat-resistant aluminum alloy conductors are shown in Figure 1. Figure 2 c, and the specific performance data are shown in Table 1. The tensile strength, electrical conductivity and 280°C / 1h strength retention rate thereof are 162MPa, 61.5%IACS and 91.4% respectively.

[0060] Embodiment 4:

[0061] The heat-resistant aluminum alloy wire of the present invention is composed of the following components and mass percentages: Nb: 0.32%, Zr: 0.27%, B: 0.15%, Er0.23%, Y0.15%, the remainder being Al and unavoidable impurities, and the total amount of impurities is ≤0.1%. The preparation method of the heat-resistant aluminum alloy wire is as follows:

[0062] (1) Industrial pure aluminum ingots, Al-5Nb alloy, Al-5Zr alloy, Al-3B alloy, Al-5Er alloy, and Al-5Y alloy are selected as raw materials, and the ingredients are prepared according to Nb: 0.32%, Zr: 0.27%, B: 0.15%, Er: 0.23%, Y: 0.15%, and the balance is Al and unavoidable impurities;

[0063] (2) heating industrial pure aluminum to melt at 740° C., and sequentially adding the above master alloys, and stirring the melted aluminum alloy sufficiently to make the composition of the aluminum alloy liquid uniform;

[0064] (3) subjecting the aluminum alloy liquid to furnace refining, degassing and impurity removal treatment, and then continuously casting and rolling at 710° C. into aluminum alloy round rods;

[0065] (4) The aluminum alloy round rod was solution treated at 600°C for 28 h and then aged at 400°C for 42 h;

[0066] (5) The aluminum alloy round rod is drawn into an aluminum alloy wire, and finally annealed at 175° C. for 5 h to obtain a heat-resistant aluminum alloy conductor.

[0067] The typical tensile curve of the heat-resistant aluminum alloy wire in this embodiment is as follows: Figure 2 d, the specific performance data are shown in Table 1, the tensile strength, electrical conductivity and 280℃ / 1h strength retention rate thereof are 167MPa, 61.6%IACS and 91.6% respectively.

[0068] Table 1 Room temperature tensile mechanical properties, conductivity and strength retention rate of heat-resistant aluminum alloy wires of Examples 1-4

[0069]

[0070] The above applications are only some implementation methods of the present application. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present application, and these all belong to the protection scope of the present application.

Claims

1. A heat-resistant conductive aluminum alloy, characterized in that: The heat-resistant conductive aluminum alloy has the following components and mass percentages: Nb 0.15-1.0%, Zr 0.1-0.5%, B 0.05-0.2%, Er ≤0.3%, Y ≤0.3%, the remainder being Al and unavoidable impurities, with a total impurity amount of ≤0.1%. In the structure of the heat-resistant conductive aluminum alloy, a second phase exists in the aluminum matrix, and the second phase is an Al3 (Nb, Zr) phase with high thermal stability.

2. The heat-resistant conductive aluminum alloy according to claim 1, characterized in that: The heat-resistant aluminum alloy wire is composed of the following components in mass percentage: Nb: 0.20-0.60%, Zr: 0.20-0.40%, B: 0.05-0.15%, and the remainder is Al and unavoidable impurities, and the total amount of impurities is ≤0.1%.

3. The heat-resistant conductive aluminum alloy according to claim 1, characterized in that: The heat-resistant aluminum alloy wire is composed of the following components in mass percentage: Nb: 0.15-0.40%, Zr: 0.15-0.30%, B: 0.05-0.15%, Er: 0.10-0.25%, Y: 0.05-0.15%, the balance is Al and unavoidable impurities, and the total amount of impurities is ≤0.1%. In the structure of the heat-resistant conductive aluminum alloy, a second phase exists in the aluminum matrix, and the second phase is a high thermal stability Al3 (Nb, Zr) phase, and the Al3 (Nb, Zr) phase also contains Er and Y elements.

4. The heat-resistant conductive aluminum alloy according to any one of claims 1 to 3, characterized in that: The heat-resistant aluminum alloy wire has a conductivity of ≥61% IACS, and a strength retention rate of ≥90% after being kept at 280° C. for 1 hour.

5. A heat-resistant conductive aluminum alloy wire, characterized in that: The conductor is made of the heat-resistant conductive aluminum alloy described in any one of claims 1 to 4.

6. The method for preparing the heat-resistant conductive aluminum alloy wire according to claim 5, characterized in that: The steps include: (1) Prepare raw materials according to alloy composition; (2) Melt the aluminum at 700°C~750°C, add alloying elements in sequence, and stir thoroughly after melting to make the composition of the aluminum alloy liquid uniform; (3) The aluminum alloy liquid is subjected to furnace refining, degassing and impurity removal treatment, and then continuously cast and rolled into aluminum alloy round rods at 700°C to 720°C; (4) Solution treatment of the aluminum alloy round rod at 580°C~620°C for 20~35 h, followed by aging at 350°C~450°C for 30~65 h; (5) The aluminum alloy round rod is drawn into an aluminum alloy wire, and finally annealed at 150℃~250℃ for 1~10 h to obtain a heat-resistant aluminum alloy conductor.

7. The method for preparing a heat-resistant conductive aluminum alloy wire according to claim 6, characterized in that: In step (1), industrial pure aluminum ingots, Al-5Nb, Al-5Zr, Al-3B, Al-5Er and Al-5Y master alloys are selected as raw materials.

8. The method for preparing a heat-resistant conductive aluminum alloy wire according to claim 7, characterized in that: In step (2), the alloying elements are added in the form of Al-5Nb, Al-5Zr, Al-3B, Al-5Er and Al-5Y master alloys.

Images