Aluminum alloy wire and electric wire

Abstract

To achieve both conductivity and heat resistance.SOLUTION: The aluminum alloy wire contains 0.020 mass% or more and 0.200 mass% or less of Fe, 0.005 mass% or more and 0.070 mass% or less of Si, 0.001 mass% or more and 0.020 mass% or less of Ti, and 0.002 mass% or more and 0.100 mass% or less of B, the balance being Al and inevitable impurities, and the aluminum alloy wire has an electrical conductivity of 64.5% IACS or more, and the tensile strength of the aluminum alloy wire after being subjected to a heat treatment at 140°C for 400 hours is 84% or more of the tensile strength before the heat treatment.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to aluminum alloy wires and electric wires. [Background technology]

[0002] Aluminum alloy wires are used, for example, as conductors for electric wires (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 189002 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present disclosure is to achieve both electrical conductivity and heat resistance. [Means for solving the problem]

[0005] According to one embodiment of the present disclosure, there is provided an aluminum alloy wire containing 0.020% by mass or more and 0.200% by mass or less of Fe, 0.005% by mass or more and 0.070% by mass or less of Si, 0.001% by mass or more and 0.020% by mass or less of Ti, 0.002% by mass or more and 0.100% by mass or less of B, with the balance being Al and inevitable impurities, wherein the aluminum alloy wire has an electrical conductivity of 62.5% IACS or more, and a tensile strength after heat treatment at 140°C for 400 hours is 84% ​​or more of the tensile strength before the heat treatment. [Effects of the Invention]

[0006] According to the present disclosure, both electrical conductivity and heat resistance can be achieved. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing the radial structure function obtained by X-ray absorption fine structure measurement at the K absorption edge of Fe in an aluminum alloy wire. [Figure 2] Figure 2 shows the X-ray absorption fine structure spectrum at the Ti K-edge in the aluminum alloy wire. [Figure 3] FIG. 3 is a schematic cross-sectional view perpendicular to the axial direction of an electric wire according to an embodiment of the present disclosure. [Figure 4] FIG. 4 is a flowchart illustrating a method for manufacturing an electric wire according to an embodiment of the present disclosure. [Figure 5] FIG. 5 is a graph showing the dependency of the tensile strength of an aluminum alloy wire after heat treatment on the Fe precipitation index. [Figure 6] FIG. 6 is a graph showing the dependence of the electrical conductivity of an aluminum alloy wire on the precipitation index of Ti. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Description of the embodiments of the present disclosure] <Insights gained by the inventor> First, the findings of the inventors will be explained.

[0009] As an aluminum (Al) alloy wire having a predetermined electrical conductivity and heat resistance, an Al alloy wire containing iron (Fe), silicon (Si) and titanium (Ti) has been developed.

[0010] As a result of the inventors' investigation into Al alloy wires containing the above-mentioned alloying elements, it was found that the following new problems arise in the previously known configurations based on the states of Fe and Ti in the Al alloy wires.

[0011] (Conventional aluminum alloy wire: JISC3108:2016 "Hard aluminum wire for electrical use") In conventional aluminum alloy wires, iron is dissolved in the aluminum matrix, improving the strength and heat resistance of the aluminum alloy wire. However, the dissolved iron reduces the electrical conductivity of the aluminum alloy wire.

[0012] Furthermore, in conventional Al alloy wires, a wire containing a Ti-boron (B) compound (e.g., TiB2) is introduced into the molten metal immediately before the casting process to refine the solidification structure of the Al and suppress the occurrence of defects during casting. However, the TiB wire described above contains not only Ti-B compounds but also excess Ti. Therefore, the excess Ti incorporated into the Al alloy is dissolved in the Al matrix. As a result, the electrical conductivity of the Al alloy wire is reduced due to the solid solution of the Ti.

[0013] (Al alloy wire in Patent Document 1) In order to improve the electrical conductivity of the Al alloy wire compared to that of the conventional Al alloy wires described above, in Patent Document 1, not only Ti but also B was actively added to Al. Furthermore, in Patent Document 1, an intermediate heat treatment step was performed at a temperature of 300°C or higher for 1 hour or more between the rolling step and the wiredrawing step.

[0014] In Patent Document 1, Fe is precipitated by the intermediate heat treatment process described above, thereby reducing the amount of Fe dissolved in the Al alloy wire, and as a result, improving the electrical conductivity of the Al alloy wire.

[0015] In Patent Document 1, the active addition of B causes the excess Ti in the TiB wire to react with B, resulting in the precipitation of Ti-B compound crystals. This reduces the amount of excess Ti present in the Al alloy wire, and reduces the amount of Ti in solid solution in the Al alloy wire. As a result, the decrease in electrical conductivity of the Al alloy wire caused by the Ti in solid solution is suppressed.

[0016] However, although Patent Document 1 was able to improve the electrical conductivity of the Al alloy wire, the amount of Fe dissolved in the Al alloy wire was reduced, resulting in a decrease in the heat resistance of the Al alloy wire.

[0017] As described above, it has been difficult for the conventional Al alloy wires and the Al alloy wire of Patent Document 1 to achieve both electrical conductivity and heat resistance.

[0018] Therefore, the inventors further studied the composition of the Al alloy wire and the manufacturing method of the Al alloy wire, and as a result, succeeded in obtaining an Al alloy wire that has both electrical conductivity and heat resistance.

[0019] The present disclosure below is based on the above-mentioned new problem discovered by the inventors.

[0020] <Embodiments of the present disclosure> Next, embodiments of the present disclosure will be listed and described.

[0021] [1] An aluminum alloy wire according to one embodiment of the present disclosure comprises: Fe is 0.020 mass% or more and 0.200 mass% or less, Si is 0.005 mass% or more and 0.070 mass% or less, Ti is 0.001 mass% or more and 0.020 mass% or less, B is 0.002 mass% or more and 0.100 mass% or less, Contains the balance being Al and unavoidable impurities, The electrical conductivity of the aluminum alloy wire is 62.5% IACS or more, The tensile strength of the aluminum alloy wire after heat treatment at 140° C. for 400 hours is 84% ​​or more of the tensile strength before the heat treatment. This configuration makes it possible to achieve both electrical conductivity and heat resistance.

[0022] [2] In the aluminum alloy wire according to the above [1], The aluminum alloy wire satisfies formula (1) and formula (2). IFe1 / IFe0≦0.70 (1) xTi1 / xTi2≧1.03 (2) where: IFe1 is the height of a peak occurring within a radius range of 0.15 nm or more and 0.25 nm or less in a radial structure function obtained from X-ray absorption fine structure measurement at the K absorption edge of Fe in the aluminum alloy wire, IFe0 is the height of a peak occurring within a radius range of 0.15 nm or more and 0.25 nm or less in the radial structure function of Fe in a rolled iron material having a purity of 99.99% and a thickness of 0.005 mm as a standard sample, which is obtained under the same conditions as those under which the radial structure function of Fe in the aluminum alloy wire was obtained, xTi1 and xTi2 are the height of a first peak occurring within an incident X-ray energy range of 4978 eV or more and 4984 eV or less, and the height of a second peak occurring within an incident X-ray energy range of 4986 eV or more and 4994 eV or less, respectively, in an X-ray absorption fine structure spectrum normalized by the absorbance difference before and after the Ti K-absorption edge in the aluminum alloy wire. This configuration makes it possible to achieve both electrical conductivity and heat resistance.

[0023] [3] An aluminum alloy wire according to another aspect of the present disclosure includes: Fe is 0.020 mass% or more and 0.200 mass% or less, Si is 0.005 mass% or more and 0.070 mass% or less, Ti is 0.001 mass% or more and 0.020 mass% or less, B is 0.002 mass% or more and 0.100 mass% or less, Contains the balance being Al and unavoidable impurities, The aluminum alloy wire satisfies formula (1) and formula (2). IFe1 / IFe0≦0.70 (1) xTi1 / xTi2≧1.03 (2) where: IFe1 is the height of a peak occurring within a radius range of 0.15 nm or more and 0.25 nm or less in a radial structure function obtained from X-ray absorption fine structure measurement at the K absorption edge of Fe in the aluminum alloy wire, IFe0 is the height of a peak occurring within a radius range of 0.15 nm or more and 0.25 nm or less in the radial structure function of Fe in a rolled iron material having a purity of 99.99% and a thickness of 0.005 mm as a standard sample, which is obtained under the same conditions as those under which the radial structure function of Fe in the aluminum alloy wire was obtained, xTi1 and xTi2 are the height of a first peak occurring within an incident X-ray energy range of 4978 eV or more and 4984 eV or less, and the height of a second peak occurring within an incident X-ray energy range of 4986 eV or more and 4994 eV or less, respectively, in an X-ray absorption fine structure spectrum normalized by the absorbance difference before and after the Ti K-absorption edge in the aluminum alloy wire. This configuration makes it possible to achieve both electrical conductivity and heat resistance.

[0024] [4] The aluminum alloy wire according to any one of [1] to [3] above, The ratio of the Ti content to the B content in the aluminum alloy wire is 2.5 or less. According to this configuration, the decrease in the electrical conductivity of the Al alloy wire can be stably suppressed. [5] An electric wire according to yet another aspect of the present disclosure includes: The wire has a stranded portion formed by stranding together a plurality of aluminum alloy wires according to any one of [1] to [4] above. This configuration makes it possible to achieve both electrical conductivity and heat resistance.

[0025] [Details of the embodiments of the present disclosure] Next, one embodiment of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0026] <One embodiment of the present disclosure> (1) Aluminum alloy wire The Al alloy wire of this embodiment (hereinafter also referred to as "Al alloy wire 210" in accordance with the contents described later) contains, for example, Fe, Si, Ti, and B, with the balance being Al and inevitable impurities.

[0027] Hereinafter, the content of each element in the Al alloy wire 210 is the content when the entire Al alloy wire 210 is taken as 100 mass %.

[0028] (Fe) As described above, in an Al alloy wire, Fe dissolved in the Al matrix and Fe precipitated in the Al matrix can exist in a predetermined ratio.

[0029] In the case of conventional Al alloy wires in which a relatively large proportion of Fe is dissolved in the Al matrix, the dissolved Fe can improve the strength (tensile strength) and heat resistance of the Al alloy wire. However, the dissolved Fe tends to reduce the electrical conductivity of the Al alloy wire.

[0030] On the other hand, when Fe is precipitated (including crystallized) in the Al matrix, as in the Al alloy wire of Patent Document 1, the amount of Fe dissolved in the wire is reduced, thereby improving the electrical conductivity of the Al alloy wire. However, the heat resistance of the Al alloy wire tends to decrease due to the precipitation of Fe.

[0031] In contrast to this, in the present embodiment, the content of Fe in the Al alloy wire 210 is optimized and a manufacturing method described later is applied to increase the solid solution ratio of Fe in the Al alloy wire 210. This makes it possible to improve the heat resistance of the Al alloy wire 210 while suppressing a decrease in the electrical conductivity of the Al alloy wire 210.

[0032] Specifically, the Fe content in the Al alloy wire 210 of this embodiment is, for example, 0.020 mass % or more and 0.200 mass % or less.

[0033] When the Fe content is less than 0.020% by mass, the solid solution ratio of Fe in the Al alloy wire 210 increases, but the absolute amount of Fe dissolved in the Al matrix decreases. This may result in a decrease in the heat resistance of the Al alloy wire 210. In contrast, in this embodiment, by setting the Fe content to 0.020% by mass or more, it is possible to increase the solid solution ratio of Fe in the Al alloy wire 210 and dissolve Fe in a sufficient absolute amount in the Al matrix. This can improve the heat resistance of the Al alloy wire 210.

[0034] On the other hand, if the Fe content exceeds 0.200 mass%, the conductivity of the Al alloy wire 210 decreases due to excessive Fe solid solution. In contrast, in this embodiment, the Fe content is set to 0.200 mass% or less, so that excessive Fe solid solution can be suppressed. As a result, the decrease in the conductivity of the Al alloy wire 210 can be suppressed.

[0035] In the Al alloy wire 210 of this embodiment, the state in which the proportion of Fe in solid solution is high can be confirmed by X-ray absorption fine structure measurement, which will be described in detail later.

[0036] (Si) In this embodiment, Si is mainly dissolved in the Al matrix. This allows the Al alloy wire 210 to be solid-solution strengthened by Si. This allows the strength (tensile strength) of the Al alloy wire 210 to be improved. However, the solid solution of Si does not significantly improve the heat resistance.

[0037] The Si content in the Al alloy wire 210 of this embodiment is, for example, 0.005 mass % or more and 0.070 mass % or less.

[0038] If the Si content is less than 0.005% by mass, the aluminum alloy contains Si as an inevitable impurity, so the purity of the aluminum alloy needs to be increased. This increases the refining cost. In contrast, in this embodiment, the Si content is set to 0.005% by mass or more, so that the purity of the aluminum alloy does not need to be excessively increased, and the increase in refining cost can be suppressed. Furthermore, by setting the Si content to 0.005% by mass or more, Si can be sufficiently dissolved in the aluminum matrix. This allows the strength (tensile strength) of the aluminum alloy wire 210 to be stably improved.

[0039] On the other hand, if the Si content exceeds 0.070 mass%, the conductivity of the Al alloy wire 210 decreases due to excessive solid solution of Si. In contrast, in this embodiment, the Si content is set to 0.070 mass% or less, so that the excessive solid solution of Si can be suppressed. As a result, the decrease in the conductivity of the Al alloy wire 210 can be suppressed.

[0040] (Ti) When Ti dissolves in the Al matrix as in the conventional Al alloy wire described above, the electrical conductivity of the Al alloy is significantly reduced.

[0041] In contrast to this, in the present embodiment, as will be described later, B is actively added to the Al alloy wire 210, and a long-term molten metal holding step S120 is performed, whereby Ti is precipitated as a Ti-B compound in the Al alloy. Specifically, crystals of the Ti-B compound (e.g., TiB2) are precipitated in a finely dispersed state in the Al alloy.

[0042] The precipitation of Ti—B compounds can reduce the amount of Ti in solid solution, thereby preventing the decrease in the electrical conductivity of the Al alloy wire 210.

[0043] By finely dispersing the Ti-B compound crystals in the Al alloy, Al solidifies using the dispersed Ti-B compound crystals as nuclei. This allows the Al crystal grains to be refined. As a result, the workability of the Al alloy wire 210 can be improved.

[0044] The Ti content in the Al alloy wire 210 of this embodiment is, for example, 0.001 mass % or more and 0.020 mass % or less.

[0045] If the Ti content is less than 0.001 mass%, the crystals of Ti-B compounds are not sufficiently precipitated, and it is difficult to refine the Al crystal grains. As a result, the workability of the Al alloy wire 210 may be reduced. In contrast, in this embodiment, by setting the Ti content to 0.001 mass% or more, the crystals of Ti-B compounds are sufficiently precipitated, and the Al crystal grains can be refined. As a result, the workability of the Al alloy wire 210 can be improved.

[0046] On the other hand, if the Ti content exceeds 0.020 mass%, there is a possibility that Ti will be excessively dissolved in the Al matrix depending on the B content. This may result in a decrease in the electrical conductivity of the Al alloy wire 210. In contrast, in this embodiment, by setting the Ti content to 0.020 mass% or less, it is possible to suppress the saturation of precipitation of Ti-B compounds and to suppress excessive dissolution of Ti. This makes it possible to suppress a decrease in the electrical conductivity of the Al alloy wire 210.

[0047] In the Al alloy wire 210 of this embodiment, the precipitation state of the Ti—B compound can be confirmed by X-ray absorption fine structure measurement, which will be described in detail later.

[0048] (B) In this embodiment, as described above, B is intentionally added to the Al alloy wire 210.

[0049] Specifically, the B content in the Al alloy wire 210 of this embodiment is, for example, 0.002 mass % or more and 0.100 mass % or less.

[0050] If the B content is less than 0.002 mass%, Ti cannot be sufficiently precipitated as a B compound in the Al matrix. Therefore, it is difficult to reduce the amount of Ti dissolved in solid solution. As a result, the conductivity of the Al alloy wire 210 may decrease. In contrast, in this embodiment, by setting the B content to 0.002 mass% or more, Ti can be precipitated as a B compound in the Al matrix. This makes it possible to reduce the amount of Ti dissolved in solid solution. As a result, it is possible to suppress a decrease in the conductivity of the Al alloy wire 210.

[0051] On the other hand, even if the content of B increases, B is less likely to reduce the electrical conductivity than Ti and Fe. However, adding excessive B has an adverse effect on the electrical conductivity. Therefore, in this embodiment, by setting the content of B to 0.100 mass% or less, the high electrical conductivity of the Al alloy wire 210 can be stably maintained.

[0052] Furthermore, in this embodiment, the ratio of the Ti content to the B content in the Al alloy wire 210 (hereinafter also referred to as "Ti / B") may be, for example, 2.5 or less.

[0053] If Ti / B>2.5, i.e., if there is an excess of Ti relative to B, the crystals of Ti-B compounds do not precipitate sufficiently, and the amount of Ti in solid solution increases, which may result in a decrease in the electrical conductivity of the Al alloy wire 210.

[0054] On the other hand, in the present embodiment, by setting Ti / B≦2.5, the crystals of Ti-B compound are sufficiently precipitated, and the amount of Ti in solid solution can be stably reduced. As a result, the decrease in the electrical conductivity of the Al alloy wire 210 can be stably suppressed.

[0055] The lower limit of Ti / B is not particularly limited, but based on the above-mentioned lower limit of the Ti content and the upper limit of the B content, Ti / B may be 0.01 or more.

[0056] (unavoidable impurities) In this embodiment, zirconium (Zr) is not intentionally added to the Al alloy wire 210. Specifically, the content of Zr, which is one of the inevitable impurities in the Al alloy wire of this embodiment, is, for example, less than 0.010 mass%. By making the Al alloy wire 210 free of Zr or reducing the Zr content in the Al alloy wire 210 in this way, the electrical conductivity can be easily improved. In addition, there is no need to set the molten metal temperature excessively high. This can shorten the temperature rise time of the molten metal. In addition, it can reduce thermal stress during solidification and reduce the risk of scratches. Furthermore, it can suppress damage to the melting furnace and extend the life of the melting furnace.

[0057] In this embodiment, strontium (Sr) is not intentionally added to the Al alloy wire 210. Specifically, the content of Sr, which is one of the inevitable impurities in the Al alloy wire, is, for example, less than 0.005 mass%. In this way, by making the Al alloy wire 210 free of Sr or reducing the Sr content in the Al alloy wire 210, promotion of Fe precipitation caused by Sr can be suppressed.

[0058] In the present embodiment, the total content of unavoidable impurities in the Al alloy wire 210 may be, for example, less than 0.010 mass %, or less than 0.005 mass %.

[0059] (2) State of Fe and Ti in Al alloy wire Next, the state of Fe and Ti in the Al alloy wire 210 will be described with reference to FIGS.

[0060] In X-ray absorption fine structure (XAFS) measurements, a material is irradiated with X-rays and the intensity of the transmitted or fluorescent X-rays from the material is measured to obtain an XAFS spectrum derived from a specific target element in the material. The low-energy region of the XAFS spectrum reflects the chemical state of the element (e.g., elemental or compound species). Furthermore, the radial structure function of the target element can be obtained by Fourier transforming the extended X-ray absorption fine structure (EXAFS) oscillations that occur in the high-energy region of the XAFS spectrum. By analyzing the XAFS spectrum or radial structure function, the local structure around the target element (interatomic distance, coordination number, valence, coordination structure), etc. can be evaluated.

[0061] The inventors evaluated the state of solid solution or precipitation of each element in the Al alloy wire 210 by performing XAFS measurement of each element contained in the Al alloy wire 210 of this embodiment.

[0062] As a result, in this embodiment, the inventors have found that by increasing the solid solution ratio of Fe and precipitating Ti-B compounds by the manufacturing method described later, the Al alloy wire 210 satisfies the requirements described later regarding the XAFS measurement results of Fe and Ti.

[0063] (Fe precipitation index) Figure 1 shows the radial structure functions obtained by X-ray absorption fine structure measurements at the Fe K absorption edge in the Al alloy wires of this embodiment and the comparative example. In Figure 1, the horizontal axis represents the radial distance (unit: nm), and the vertical axis represents the normalized radial structure function |X(R)| (arbitrary unit) at each radial distance.

[0064] The radial structure function X(R) of Fe can be obtained by carrying out the following steps (a) to (d). (a) Measure the X-ray absorption fine structure spectrum μ(E) at the K absorption edge of Fe. (b) Based on the X-ray absorption fine structure spectrum μ(E), the extended X-ray absorption fine structure vibration χ(k) is obtained using equation (A). χ(k)={μ(E)-μs(E)} / μ0 ···(A) where: where k is the wave number, E is the energy, μs(E) is the component obtained by approximating the center of the vibration component of μ(E) using a spline function, and μ0 is the absorbance difference before and after the absorption edge in μ(E). (c) The extended X-ray absorption fine structure vibration χ(k) is expressed as k 2 Weighting processing is performed using (d) k obtained by (c) 2 χ(k) is the 30 nm wavelength of wave number k. -1 Over 80nm -1 The region within the following range is Fourier transformed:

[0065] "IFe1" in FIG. 1 is the height of a peak occurring within a radius range of 0.15 nm to 0.25 nm in the radial structure function X(R) obtained from XAFS measurement of the K absorption edge of Fe in the Al alloy wire 210. "IFe0" is the height of a peak occurring within a radius range of 0.15 nm to 0.25 nm in the radial structure function of Fe in a standard sample of rolled iron (body-centered cubic (bcc) structure) with a purity of 99.99% and a thickness of 0.005 mm, obtained under the same conditions as those for obtaining the radial structure function of Fe in the Al alloy wire 210. Note that the radial position of the IFe1 peak and the radial position of the IFe0 peak may be slightly different within a radius range of 0.15 nm to 0.25 nm.

[0066] The vertical axis in Figure 1 above shows the value of the radial structure function X(R) normalized by IFe0. For this reason, in Figure 1, peaks occurring within a radius range of 0.15 nm to 0.25 nm are labeled "IFe1 / IFe0."

[0067] The ratio “IFe1 / IFe0” is hereinafter also referred to as “Fe precipitation index.” The Fe precipitation index IFe1 / IFe0 is an index that reflects the Fe precipitation ratio in the Al alloy wire.

[0068] The radial structure function of the comparative example shown in FIG. 1 is, for example, the radial structure function of Fe in the Al alloy wire of Sample 40B in the example described later. In the comparative example, the Fe precipitation index IFe1 / IFe0 is greater than 0.70. This is because the Fe precipitation ratio of the Fe in the Al alloy wire is high in the comparative example. In the comparative example showing such a tendency, the solid solution ratio of Fe is low, and therefore the heat resistance of the Al alloy wire is reduced.

[0069] In contrast, the radial structure function of this embodiment shown in Fig. 1 is, for example, the radial structure function of Fe in the Al alloy wire of Sample 5A in the example described later. In this embodiment, the Fe precipitation index IFe1 / IFe0 is lower than that of the comparative example.

[0070] Specifically, the Al alloy wire 210 of this embodiment satisfies, for example, the following formula (1). IFe1 / IFe0≦0.70 (1)

[0071] In this embodiment, the Al alloy wire 210 satisfies the formula (1) regarding the Fe precipitation index, and thus the proportion of Fe in the Al alloy wire 210 that is in solid solution is increased. This allows the heat resistance of the Al alloy wire 210 to be improved.

[0072] The lower limit of the Fe precipitation index IFe1 / IFe0 is not particularly limited, but may be IFe1 / IFe0≧0.45.

[0073] (Ti precipitation index) Fig. 2 shows the XAFS spectrum of the Ti K absorption edge in each of the Al alloy wires of this embodiment and the comparative example, normalized by the absorbance difference before and after the absorption edge. In Fig. 2, the horizontal axis represents the energy (unit: eV) of the incident X-rays, and the vertical axis represents the absorbance (arbitrary unit) normalized by the absorbance difference before and after the absorption edge.

[0074] "xTi1" and "xTi2" shown in FIG. 2 are the heights of the first peak occurring within the incident X-ray energy range of 4978 eV to 4984 eV and the second peak occurring within the incident X-ray energy range of 4986 eV to 4994 eV, respectively, in the XAFS spectrum at the Ti K absorption edge in each Al alloy wire.

[0075] The ratio “xTi1 / xTi2” is hereinafter also referred to as “Ti precipitation index.” The Ti precipitation index xTi1 / xTi2 is an index that reflects the precipitation ratio of Ti—B compounds in the Al alloy wire.

[0076] The XAFS spectrum of the comparative example shown in FIG. 2 is, for example, the XAFS spectrum of Ti in the Al alloy wire of Sample 26B in the example described later. In the comparative example, the height xTi1 of the first peak and the height xTi2 of the second peak are close to each other, and the Ti precipitation index xTi1 / xTi2 is less than 1.03. This is because most of the Ti in the Al alloy wire is solid-dissolved in the comparative example. In the comparative example showing such a tendency, the conductivity of the Al alloy wire decreases due to the solid solution of Ti.

[0077] 2 is an XAFS spectrum of Ti in the Al alloy wire of Sample 5A in the examples described later. In this embodiment, the height xTi1 of the first peak is higher than the height xTi2 of the second peak.

[0078] Specifically, the Al alloy wire 210 of this embodiment satisfies, for example, the following formula (2). xTi1 / xTi2≧1.03 (2)

[0079] In this embodiment, the Al alloy wire 210 satisfies the formula (2) regarding the Ti precipitation index, so that Ti-B compound crystals are sufficiently precipitated in the Al alloy wire 210. This can reduce the amount of Ti dissolved in the wire. As a result, the decrease in the electrical conductivity of the Al alloy wire 210 can be suppressed.

[0080] The upper limit of the Ti precipitation index xTi1 / xTi2 is not particularly limited, but may be xTi1 / xTi2≦1.12.

[0081] (3) Characteristics of Al alloy wire The Al alloy wire 210 of this embodiment has the following properties.

[0082] (conductivity) The electrical conductivity of the Al alloy wire 210 of this embodiment at 20° C. is, for example, 62.5% IACS or more.

[0083] The unit of conductivity "%IACS" used here is the ratio of conductivity when the conductivity of International Annealed Copper Standard is taken as 100%.

[0084] The upper limit of the electrical conductivity of the Al alloy wire 210 of this embodiment is not limited. However, since the solid solution ratio of Fe in the Al alloy wire 210 is high, the electrical conductivity of the Al alloy wire 210 of this embodiment at 20°C may be, for example, 64% IACS or less (the electrical conductivity of 99.99% Al or less).

[0085] (tensile strength) The Al alloy wire 210 of this embodiment exhibits high tensile strength due to solid solution strengthening of Fe and Si.

[0086] Specifically, the tensile strength of the Al alloy wire 210 of this embodiment at 20°C is equal to or greater than the minimum tensile strength of an electrical hard aluminum wire having a diameter equal to the diameter of the Al alloy wire 210 of this embodiment, as specified in, for example, JIS C3108:2016.

[0087] More specifically, the tensile strength of the Al alloy wire 210 of this embodiment at 20° C. may be, for example, 150 MPa or more, or 159 MPa or more.

[0088] The upper limit of the tensile strength of the Al alloy wire 210 of this embodiment is not limited. However, the tensile strength of the Al alloy wire 210 of this embodiment at 20°C may be, for example, 250 MPa or less. This can prevent elements that increase strength (such as dislocations) from becoming electron scattering sites. As a result, a decrease in electrical conductivity can be prevented.

[0089] (tensile survival rate) The Al alloy wire 210 of this embodiment exhibits a high tensile strength even after being subjected to a long-term heat treatment.

[0090] The "tensile strength retention rate after heat treatment" referred to here is the ratio (%) calculated by (tensile strength after heat treatment) / (tensile strength before heat treatment) × 100. The temperature when measuring the tensile strength before and after heat treatment is 20°C.

[0091] The tensile strength of the Al alloy wire 210 of this embodiment after heat treatment at 120° C. for 400 hours is, for example, 90% or more of the tensile strength before the heat treatment.

[0092] Here, even the Al alloy wire of Patent Document 1 may obtain the above-mentioned tensile strength after heat treatment at 120°C for 400 hours. However, since Fe is precipitated in the Al alloy wire of Patent Document 1, the heat resistance is lower than that of the Al alloy wire 210 of the present embodiment. Therefore, the Al alloy wire of Patent Document 1 has a lower tensile strength after heat treatment at a temperature (e.g., 140°C) higher than the above-mentioned specified temperature.

[0093] In contrast, the Al alloy wire 210 of this embodiment has a high solid solution ratio of Fe as described above, which allows a high tensile strength to be obtained even after heat treatment at 140°C.

[0094] Specifically, the tensile strength of the Al alloy wire 210 of this embodiment after heat treatment at 140° C. for 400 hours is, for example, 84% or more of the tensile strength before the heat treatment.

[0095] As described above, the Al alloy wire 210 of the present embodiment can obtain high heat resistance that cannot be obtained by the Al alloy wire of Patent Document 1. That is, even when the Al alloy wire 210 is exposed to a high-temperature environment for a long period of time, the Al alloy wire 210 can maintain high strength.

[0096] The upper limit of the tensile strength after heat treatment of the Al alloy wire 210 of this embodiment is not limited, and the higher the upper limit, the better. That is, in the Al alloy wire 210 of this embodiment, the tensile strength after heat treatment at 120°C for 400 hours and the tensile strength after heat treatment at 140°C for 400 hours may be close to 100%, for example.

[0097] (4)Electric wire Next, the electric wire 10 of this embodiment will be described with reference to FIG.

[0098] The electric wire 10 of this embodiment has, for example, a central portion (steel core portion) 100 and a stranded wire portion 200.

[0099] The central portion 100 is provided at the center of the electric wire 10. The central portion 100 is configured to function as a tension member that bears the tension of the electric wire 10 when the electric wire 10 is strung.

[0100] The core 100 has, for example, a plurality of core wires 110 twisted together in a spiral shape. The core 100 has, for example, a first core layer 100a and a second core layer 100b in this order from the central axis of the electric wire 10 toward the outside in the radial direction. The first core layer 100a and the second core layer 100b have, for example, one core wire 110 and six core wires 110, respectively.

[0101] Each core wire 110 has a wire portion 112 and a covering portion 114 provided to cover the outer periphery of the wire portion 112. Examples of the core wire 110 include aluminum-clad steel wire, galvanized steel wire, aluminum-clad Invar wire, and galvanized Invar wire.

[0102] The twisted wire portion 200 is provided so as to cover the outer periphery of the central portion 100. The twisted wire portion 200 is configured to function as a conductor that mainly carries current during power transmission.

[0103] The stranded wire portion 200 includes a plurality of the Al alloy wires 210 of the present embodiment described above. In the stranded wire portion 200, the plurality of Al alloy wires 210 are twisted together in a spiral shape. The diameter of the Al alloy wire 210 is, for example, 0.1 mm or more and 15 mm or less, and may be 2.3 mm or more and 5.0 mm or less.

[0104] The stranded wire portion 200 has, for example, a first stranded wire layer 200a and a second stranded wire layer 200b in this order from a region close to the central axis of the electric wire 10 toward the radially outer side. The first stranded wire layer 200a and the second stranded wire layer 200b have, for example, 12 Al alloy wires 210 and 18 Al alloy wires 210, respectively.

[0105] (5) Wire manufacturing method A method for manufacturing the electric wire 10 of this embodiment will be described with reference to FIG.

[0106] The method for manufacturing the electric wire 10 of this embodiment includes, for example, an aluminum alloy wire forming step S100, a central portion forming step S200, and a stranded portion forming step S300.

[0107] (S100: Aluminum alloy wire forming process) The aluminum alloy wire forming step S100 includes a method for manufacturing the Al alloy wire 210 of this embodiment. Specifically, the aluminum alloy wire forming step S100 includes, for example, a molten metal preparing step S110, a molten metal holding step S120, a casting step S130, a rolling step S140, and a wire drawing step S150.

[0108] (S110: Molten metal preparation process) First, an Al ingot as a raw material is melted in a melting furnace. After the Al ingot is melted, each alloy element is introduced into the molten metal in an adjusting furnace while stirring the molten metal, thereby preparing a molten metal satisfying the composition of the Al alloy wire 210 of this embodiment.

[0109] Specifically, a molten metal is prepared that contains, for example, 0.020 to 0.200 mass% Fe, 0.005 to 0.070 mass% Si, 0.001 to 0.020 mass% Ti, 0.002 to 0.100 mass% B, and the balance being Al and unavoidable impurities. The temperature of the molten metal is set to be equal to the temperature in the molten metal holding step S120, which will be described later.

[0110] At this time, the entire amount of added Fe is dissolved in the molten metal.

[0111] Furthermore, at this time, B is actively added to the molten metal. Specifically, not only the TiB wire described above but also B in the bulk metal is added to the molten metal. Alternatively, a commercially available Al-B master alloy may be added to the molten metal instead of B in the bulk metal. This allows the B content in the molten metal to be higher than when only TiB wire is introduced. As a result, for example, Ti / B≦2.5 can be stably achieved.

[0112] (S120: Molten metal holding process) Once the molten metal is prepared, it is stirred in a conditioning furnace and held at a temperature of 700°C or higher for 7 hours or more.

[0113] At this time, by raising the molten metal temperature to 700°C or higher, Ti can react with B and precipitate crystals of Ti-B compounds. By raising the molten metal temperature to 700°C or higher, all of the Fe can be maintained in a dissolved state in the molten metal.

[0114] On the other hand, there is no upper limit to the molten metal temperature. However, the higher the temperature at which the molten metal is maintained, the more energy is consumed to heat the molten metal, and the shorter the life of the furnace insulation. Therefore, the molten metal temperature may be set to, for example, 800°C or less.

[0115] In this case, by keeping the molten metal for 7 hours or more, crystals of the Ti-B compound can be stably precipitated.

[0116] On the other hand, the molten metal holding time may be, for example, 20 hours or less, which can save energy and extend the life of the furnace insulation.

[0117] (S130: Casting process) After the molten metal holding step S120, the molten metal is solidified and continuously cast. In this embodiment, Fe is supersaturated in the Al alloy during solidification. The term "supersaturated" refers to a state in which a predetermined element is dissolved in a solid solution in an amount greater than the amount dissolved in a chemical equilibrium state. A cast material is formed through these steps.

[0118] (S140: Rolling process) After the casting step S130, the cast material is rolled (hot rolled) to form a rolled material (wire rod).

[0119] (S150: Wire drawing process) After the rolling step S140, the rolled material is wiredrawn (cold wiredrawn), whereby the diameter of the rolled material is reduced to the desired diameter of the Al alloy wire 210.

[0120] In this embodiment, an intermediate heat treatment step of heating the rolled material at a temperature of 300°C or higher is not performed after the rolling step S140 and before the wiredrawing step S150. That is, the rolled material is maintained at a temperature of less than 300°C after the rolling step S140 and before the wiredrawing step S150. This makes it possible to maintain a supersaturated solid solution state of Fe until the Al alloy wire 210 is obtained, that is, to suppress the precipitation of Fe. Meanwhile, the crystals of Ti-B compounds in the Al alloy wire 210 are maintained in a precipitated state.

[0121] In this manner, the Al alloy wire 210 of this embodiment is obtained.

[0122] (S200: Center forming process) After obtaining the Al alloy wire 210, the central portion 100 is formed including a plurality of core wires 110. Specifically, while one core wire 110 that will become the first core layer 100a is fed out from a feed machine, six core wires 110 are twisted together using a twisting machine so as to cover the outer periphery of the first core layer 100a, thereby forming the second core layer 100b.

[0123] (S300: Twisted wire part forming process) After the central portion 100 is formed, the stranded wire portion 200 including the Al alloy wires 210 of this embodiment is formed. Specifically, a stranding machine is used to strand 12 Al alloy wires 210 so as to cover the outer periphery of the central portion 100, thereby forming the first stranded wire layer 200a. Next, the stranding machine is used to strand 18 Al alloy wires 210 so as to cover the outer periphery of the first stranded wire layer 200a, thereby forming the second stranded wire layer 200b.

[0124] In this manner, the electric wire 10 of the present embodiment is manufactured.

[0125] (6) Summary of this embodiment According to this embodiment, one or more of the following effects are achieved.

[0126] (a) In this embodiment, by optimizing the content of Fe in the Al alloy wire 210 and applying the above-mentioned manufacturing method, it is possible to increase the solid solution ratio of Fe in the Al alloy wire 210. As a result, it is possible to improve the heat resistance of the Al alloy wire 210 while suppressing a decrease in the electrical conductivity of the Al alloy wire 210.

[0127] Furthermore, in this embodiment, by actively adding B to the Al alloy wire 210 and applying the molten metal holding step S120 for a long time, Ti can be precipitated in the Al alloy as a Ti-B compound (e.g., TiB2). This makes it possible to reduce the amount of Ti in solid solution, which significantly reduces the conductivity of the Al alloy. In other words, it is possible to render Ti harmless. As a result, it is possible to suppress the decrease in the conductivity of the Al alloy wire 210.

[0128] Specifically, the Al alloy wire 210 of this embodiment can have an electrical conductivity of 62.5% IACS or more. Furthermore, the Al alloy wire 210 of this embodiment can have a tensile strength after heat treatment at 140°C for 400 hours that is 84% ​​or more of the tensile strength before the heat treatment.

[0129] In this manner, in this embodiment, it is possible to obtain the Al alloy wire 210 that has both electrical conductivity and heat resistance.

[0130] (b) The Al alloy wire 210 of this embodiment satisfies the above-mentioned formula (1): IFe1 / IFe0≦0.70 with respect to the Fe precipitation index in the radial structure function of Fe in the Al alloy wire 210. When the Al alloy wire 210 satisfies formula (1), the proportion of Fe in the solid solution of Fe in the Al alloy wire 210 is increased. This can improve the heat resistance of the Al alloy wire 210.

[0131] The Al alloy wire 210 of this embodiment satisfies the formula (2): xTi1 / xTi2≧1.03 with respect to the Ti precipitation index in the XAFS spectrum of Ti in the Al alloy wire 210. When the Al alloy wire 210 satisfies the formula (2), Ti-B compound crystals are sufficiently precipitated in the Al alloy wire 210. This makes it possible to reduce the amount of Ti in solid solution. As a result, it is possible to suppress a decrease in the electrical conductivity of the Al alloy wire 210.

[0132] (c) In this embodiment, in the molten metal holding step S120, the molten metal satisfying the composition of the Al alloy wire 210 is held at a temperature of 700°C or higher for 7 hours or more. This allows the actively added B to be uniformly dispersed in the molten metal and the B to react sufficiently with Ti. This allows fine Ti-B compound crystals to be precipitated throughout the molten metal. By precipitating the Ti-B compound crystals in this way, the amount of Ti in solid solution can be reduced. As a result, the decrease in the electrical conductivity of the Al alloy wire 210 can be suppressed.

[0133] (d) In this embodiment, the intermediate heat treatment step of heating the rolled material at a temperature of 300° C. or higher is not performed after the rolling step S140 and before the wire drawing step S150.

[0134] In Patent Document 1, an intermediate heat treatment process is performed after the rolling process and before the wiredrawing process, in which the rolled material is heated at a temperature of 300°C or higher for 1 hour or more. Therefore, in the rolled material after the rolling process, Fe transitions from a supersaturated solid solution state to an equilibrium state, and the Fe precipitates. As a result, the heat resistance of the Al alloy wire is reduced due to the precipitation of Fe.

[0135] In contrast, in the present embodiment, the above-mentioned intermediate heat treatment step is not performed, so that the supersaturated solid solution state of Fe can be maintained until the Al alloy wire 210 is obtained. That is, the transition of Fe to the equilibrium state can be suppressed, and the precipitation of Fe can be suppressed. As a result, the heat resistance of the finally obtained Al alloy wire 210 can be improved.

[0136] <Other Embodiments of the Present Disclosure> Although the embodiments of the present disclosure have been specifically described above, the present disclosure is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit of the present disclosure.

[0137] In the above-described embodiment, the configuration shown in Fig. 3 has been described as an example of the electric wire 10, but the present disclosure is not limited to this case. For example, the number and arrangement of the core wires 110 in the central portion 100, the number of layers in the central portion 100, the number and arrangement of the Al alloy wires 210 in the stranded portion 200, and the number of layers in the stranded portion 200 may be changed. Alternatively, the electric wire 10 may have only the stranded portion 200 without having the central portion 100. [Example]

[0138] Next, examples according to the present disclosure will be described. These examples are examples of the present disclosure, and the present disclosure is not limited to these examples.

[0139] (1) Preparation of aluminum alloy wire Al alloy wires of Samples 1B to 41B were produced under the following conditions.

[0140] (Samples 1B to 10B) First, after melting an Al ingot, a molten metal having the composition of an Al alloy wire shown in Table 1 below was prepared in an adjustment furnace. At this time, not only TiB wire but also a commercially available Al-4%B master alloy was added to the molten metal to adjust the B content. Note that Zr and Sr were not added.

[0141] After the molten metal preparation step, the molten metal was held at a temperature of 700°C for 10 hours in a conditioning furnace while being stirred.

[0142] After the molten metal holding step, the molten metal was continuously cast to form a cast material. The cast material was then rolled to form a rolled material. The rolled material was then drawn to a diameter of 3.2 mm.

[0143] In Samples 1B to 10B, the intermediate heat treatment step of heating the rolled material was not performed after the rolling step and before the wiredrawing step.The rolled material was maintained at a temperature of less than 300°C after the rolling step and before the wiredrawing step.

[0144] Through the above steps, Al alloy wires of samples 1B to 10B were obtained.

[0145] (Samples 11A-18B) The Al alloy wires of Samples 11A to 18B were produced in the same manner as Sample 5A, except that the Si content was set within the range shown in Table 1 and was different from that of Sample 5A.

[0146] (Sample 19B~24B) The Al alloy wires of Samples 19B to 24B were produced in the same manner as Sample 5A, except that the Ti content was set within the range shown in Table 2 and was different from that of Sample 5A.

[0147] (Samples 25B~32A) The Al alloy wires of Samples 25B to 32A were produced in the same manner as Sample 5A, except that the B content was different from that of Sample 5A within the range shown in Table 1.

[0148] (Samples 33B~36A) The Al alloy wires of Samples 33B to 36A were produced in the same manner as Sample 5A, except that the molten metal holding time was set within the range shown in Table 1 and was different from that of Sample 5A.

[0149] (Sample 37B~41B) The Al alloy wires of Samples 37B to 41B were produced in the same manner as Sample 5A, except that intermediate heat treatment was carried out under the conditions shown in Table 2.

[0150] (2) Evaluation Samples 1B to 41B were evaluated as follows.

[0151] (2-1) XAFS measurement XAFS measurements were carried out on the Al alloy wires of each sample.

[0152] (Fe precipitation index) XAFS measurements were carried out at the K-absorption edge of Fe in each Al alloy wire under the following conditions. Measurements were carried out using BL16 at the Kyushu Synchrotron Light Research Center in Saga Prefecture. Measurements were carried out by the fluorescence method using X-rays monochromated by a Si(111) double crystal monochromator.

[0153] The XAFS spectrum at the Fe K absorption edge obtained by the above measurement was analyzed using the free software Athena. Note that an instrument such as Rigaku Corporation's REX2000 can also be used.

[0154] The XAFS spectrum μ(E) was then extrapolated to the region above the absorption edge using two reference points between 6979 eV and 7079 eV. The background curve was then extracted from the XAFS spectrum μ(E). Next, the center of the oscillation component of the XAFS spectrum μ(E) was approximated with a spline function to obtain μs(E), which is the component μ(E) that approximates the center of the oscillation component in the region up to 7453 eV after the absorption edge. The EXAFS oscillation χ(k) was then obtained by dividing μ(E) - μs(E) by the absorbance difference μ0 between before and after the absorption edge. The "absorbance difference between before and after the absorption edge" refers to the absorbance at 7250 eV and 7400 eV after the absorption edge, when the background absorbance is set to zero.

[0155] For the EXAFS vibration χ(k) obtained as described above, the square of the wave number k (k 2 ) and weighting was performed. 2 χ(k) is the wave number k at 30 nm -1 Over 80nm -1 The radial structure function X(R) was obtained by Fourier transforming the region within the following range.

[0156] In the radial structure function X(R) of Fe in the Al alloy wire obtained as described above, the height IFe1 of the peak occurring within a radius range of 0.15 nm or more and 0.25 nm or less was determined.

[0157] Furthermore, XAFS measurements were performed at the K-absorption edge of Fe in a 0.005 mm thick rolled iron material with a purity of 99.99% as a standard sample under the same conditions as those for the XAFS measurements of Fe in the Al alloy wire described above. From the XAFS spectrum of the standard sample obtained by the above measurement, the radial structure function of Fe in the standard sample was obtained under the same conditions as those for the radial structure function of Fe in the Al alloy wire described above. The height IFe0 of the peak occurring within a radius range of 0.15 nm to 0.25 nm in the radial structure function X(R) of Fe in the obtained standard sample was calculated.

[0158] Based on the IFe1 and IFe0 determined as above, the ratio IFe1 / IFe0 (arbitrary unit) was determined as the Fe precipitation index.

[0159] (Ti precipitation index) XAFS measurements were carried out at the Ti K-absorption edge in each Al alloy wire under the following conditions. Prior to the measurements, the surface of the Al alloy wire was mechanically polished to a depth of 10 μm or more to remove the effects of surface oxidation, thereby preparing the measurement samples. Measurements were carried out using BL16 at the Kyushu Synchrotron Light Research Center in Saga Prefecture. Measurements were carried out using the fluorescence method, using X-rays monochromated by a Si(111) double crystal monochromator. The horizontal axis, which represents the energy of the incident X-rays during measurement, was calibrated so that the pre-edge peak of the titanium (Ti) metal foil was 4964.0 eV.

[0160] The XAFS spectrum of the Ti K-edge obtained by the above measurements was analyzed using the free software Athena. Two points in the region before the absorption edge, between 4870 eV and 4950 eV, were used as reference points. A curve extrapolated to the region above the absorption edge was set as the background, and the background was removed from the XAFS spectrum. Furthermore, the absorbance at 5030 eV and 5100 eV after the absorption edge was normalized to 1 when the background absorbance was set to 0.

[0161] In the normalized XAFS spectrum of the Ti K-absorption edge obtained as described above, the height xTi1 of the first peak occurring within the incident X-ray energy range of 4978 eV to 4984 eV and the height xTi2 of the second peak occurring within the incident X-ray energy range of 4986 eV to 4994 eV were calculated. Furthermore, the ratio xTi1 / xTi2 (arbitrary unit) was calculated as the Ti precipitation index.

[0162] (2-2) Tensile strength The tensile strength of each Al alloy wire was measured in accordance with JIS C3002:1992 at a temperature of 20°C.

[0163] (2-3) Conductivity The electrical conductivity of each Al alloy wire was measured in accordance with JIS C3002:1992 at a temperature of 20°C.

[0164] (2-4) Heat resistance (tensile strength) The tensile strength after heat treatment was measured under the following two temperature conditions. As described above, the "tensile strength after heat treatment" is the ratio (%) calculated by {(tensile strength after heat treatment) / (tensile strength before heat treatment)} × 100. The tensile strength before and after heat treatment was measured in accordance with JIS C3002:1992, and the temperature during measurement was 20°C.

[0165] As the "tensile strength remaining rate after 400 hours at 120°C" in Tables 1 and 2, the ratio (%) of the tensile strength after heat treatment at 120°C for 400 hours to the tensile strength before heat treatment was calculated.

[0166] Furthermore, as the "tensile strength remaining rate after 400 hours at 140°C" in Tables 1 and 2, the ratio (%) of the tensile strength after heat treatment at 140°C for 400 hours to the tensile strength before heat treatment was calculated.

[0167] (3) Results The results of evaluation of each sample are described below with reference to Tables 1 and 2.

[0168] In the following description, the ranges of the contents of the alloying elements below are also referred to as "appropriate ranges." Fe content: 0.020 mass% or more and 0.200 mass% or less, Si content: 0.005 mass% or more and 0.070 mass% or less, Ti content: 0.001 mass% or more and 0.020 mass% or less, B content: 0.002 mass% or more and 0.100 mass% or less.

[0169] In the following description, the following manufacturing conditions are also referred to as "appropriate conditions." During the molten metal holding process, the molten metal is held at a temperature of 700°C or higher for at least 7 hours. Between the rolled material forming process and the wire drawing process, no intermediate heat treatment process is performed in which the rolled material is heated to a temperature of 300°C or higher.

[0170] [Table 1]

[0171] [Table 2]

[0172] (3-1)Fe content dependence The Fe content dependency will be explained with reference to the results of Samples 1B to 10B. As described above, in Samples 1B to 10B, except for the difference in the Fe content, the contents of the other alloying elements were within the appropriate ranges, and the manufacturing conditions were appropriate.

[0173] (Sample 1B) In Sample 1B, the Fe content was set to less than 0.020 mass %, which resulted in a tensile retention rate of less than 90% after 400 hours at 120°C and less than 84% after 400 hours at 140°C.

[0174] (Sample 10B) In Sample 10B, the Fe content was set to more than 0.200 mass %, and therefore the electrical conductivity of the Al alloy wire was less than 62.5% IACS.

[0175] (Samples 2A to 9A) In contrast, in Samples 2A to 9A, the Fe content was set to 0.020 mass% or more and 0.200 mass% or less. As a result, the tensile survival rate after 400 hours at 120°C was 90% or more, and the tensile survival rate after 400 hours at 140°C was 84% ​​or more. Furthermore, the electrical conductivity of the Al alloy wire was 62.5% IACS or more.

[0176] In Samples 2A to 9A, by setting the Fe content to 0.020 mass or more, it was possible to dissolve Fe in the Al matrix in a sufficient absolute amount, and it was confirmed that the heat resistance of the Al alloy wires in Samples 2A to 9A could be improved.

[0177] In Samples 2A to 9A, the Fe content was set to 0.200 mass% or less, which allowed for the suppression of excessive Fe solid solution, and it was confirmed that the decrease in the electrical conductivity of the Al alloy wires was thereby suppressed in Samples 2A to 9A.

[0178] (3-2)Si content dependence The Si content dependency will be explained with reference to the results of Samples 11A to 18B. As described above, Samples 11A to 18B were manufactured under appropriate conditions, with the exception of the Si content, which was varied, and the contents of other alloying elements were within appropriate ranges.

[0179] (Sample 18B) In Sample 18B, the Si content was set to more than 0.070 mass %, and therefore the electrical conductivity of the Al alloy wire was less than 62.5% IACS.

[0180] (Samples 11A-17A) In contrast, in Samples 11A to 17A, the Si content was set to 0.005 mass % or more and 0.070 mass % or less, and as a result, the electrical conductivity of the Al alloy wire was 62.5% IACS or more.

[0181] In Samples 11A to 17A, the Si content was set to 0.070 mass% or less, which prevented excessive solid dissolution of Si. As a result, it was confirmed that the decrease in the electrical conductivity of the Al alloy wires was prevented in Samples 11A to 17A.

[0182] (3-3)Ti content dependence The Ti content dependency will be explained with reference to the results of Samples 19B to 24B. As described above, in Samples 19B to 24B, except for the Ti content being different, the contents of the other alloying elements were within the appropriate ranges, and the manufacturing conditions were appropriate.

[0183] (Sample 19B) In Sample 19B, the Ti content was set to less than 0.001 mass %, so that it was not possible to process the Al alloy wire in Sample 19B.

[0184] (Sample 24B) In Sample 24B, the Ti content was set to more than 0.020 mass%. In addition, in Sample 24B, the Ti / B ratio was more than 2.5. Therefore, the Ti precipitation index was less than 1.03. As a result, in Sample 24B, the electrical conductivity of the Al alloy wire was less than 62.5%IACS.

[0185] (Samples 20A~23A) In contrast, in Samples 20A to 23A, the Ti content was set to 0.001 mass% or more and 0.020 mass% or less. As a result, in Samples 20A to 23A, the Al alloy wires could be stably processed. Furthermore, in Samples 20A to 23A, the Ti / B was 2.5 or less. As a result, the Ti precipitation index was 1.03 or more. As a result, in Samples 20A to 23A, the conductivity of the Al alloy wires was 62.5%IACS or more.

[0186] In Samples 20A to 23A, by setting the Ti content to 0.001 mass% or more, it was possible to sufficiently precipitate Ti-B compound crystals and refine the Al crystal grains, thereby confirming that Samples 20A to 23A were able to improve the workability of the Al alloy wire.

[0187] In Samples 20A to 23A, the Ti content was set to 0.020 mass% or less and Ti / B≦2.5, which prevented excessive dissolution of Ti. As a result, it was confirmed that Samples 20A to 23A were able to prevent the decrease in electrical conductivity of the Al alloy wire.

[0188] (3-4) B content dependence The dependency on the B content will be explained with reference to the results of Samples 25B to 32A. As described above, Samples 25B to 32A were manufactured under appropriate conditions, with the exception of the different B contents, in which the contents of other alloying elements were within appropriate ranges.

[0189] (Samples 25B and 26B) In Samples 25B and 26B, the B content was less than 0.002 mass%. In Samples 25B and 26B, the Ti / B ratio was greater than 2.5. Therefore, the Ti precipitation index was less than 1.03. As a result, in Samples 25B and 26B, the electrical conductivity of the Al alloy wire was less than 62.5% IACS.

[0190] (Samples 27A-32A) In contrast, in Samples 27A to 32A, the B content was 0.002 mass% or more and 0.100 mass% or less. Also, Ti / B was 2.5 or less. As a result, the Ti precipitation index was 1.03 or more. As a result, in Samples 27A to 32A, the electrical conductivity of the Al alloy wire was 62.5%IACS or more.

[0191] In Samples 27A to 32A, by setting the B content to 0.002 mass% or more, Ti could be precipitated as a Ti-B compound in the Al matrix. This reduced the amount of Ti in solid solution. As a result, it was confirmed that Samples 27A to 32A could suppress the decrease in the electrical conductivity of the Al alloy wire.

[0192] (3-5) Dependence on molten metal retention time The dependence of the molten metal holding time will be explained with reference to the results of Samples 33B to 36A. As described above, in Samples 33B to 36A, the contents of each alloy element were set within the appropriate range, and the manufacturing conditions were all appropriate except for the fact that the molten metal holding time was different.

[0193] (Samples 33B and 34B) In Samples 33B and 34B, the molten metal holding time was set to less than 7 hours. Therefore, the Ti precipitation index was less than 1.03. As a result, in Samples 33B and 34B, the electrical conductivity of the Al alloy wire was less than 62.5%IACS.

[0194] (Samples 35A and 36A) In contrast, in Samples 35A and 36A, the molten metal holding time was set to 7 hours or more. As a result, the Ti precipitation index was 1.03 or more. As a result, in Samples 35A and 36A, the electrical conductivity of the Al alloy wire was 62.5%IACS or more.

[0195] In Samples 35A and 36A, the molten metal holding time was set to 7 hours or more, which allowed stable precipitation of Ti-B compound crystals. This allowed the amount of Ti in solid solution to be reduced. As a result, it was confirmed that Samples 35A and 36A were able to suppress the decrease in the electrical conductivity of the Al alloy wire.

[0196] (3-6) Dependence on intermediate heat treatment The dependency on intermediate heat treatment will be explained with reference to the results of Samples 5A, and 37B to 41B. As described above, in Samples 5A, 37B to 41B, the content of each alloy element was set within the appropriate range, except that the manufacturing conditions were different.

[0197] (Sample 37B~41B) For Samples 37B to 41B, an intermediate heat treatment step was performed in which the rolled material was heated at a temperature of 300°C or higher for 0.5 hours or longer. As a result, the Fe precipitation index exceeded 0.70. As a result, for Samples 37B to 41B, the tensile strength after 400 hours at 120°C was 90% or higher, but the tensile strength after 400 hours at 140°C was less than 84%.

[0198] (Sample 5A) In contrast, Sample 5A did not undergo the intermediate heat treatment step of heating the rolled material at a temperature of 300°C or higher for 0.5 hours or more. As a result, the Fe precipitation index was 0.70 or less. As a result, Sample 5A had a tensile retention rate of 90% or more after 400 hours at 120°C and a tensile retention rate of 84% or more after 400 hours at 140°C.

[0199] In Sample 5A, the above-mentioned intermediate heat treatment step was not performed, and thus the supersaturated solid solution state of Fe could be maintained until the Al alloy wire was obtained. As a result, it was confirmed that the heat resistance of Sample 5A could be improved.

[0200] (3-7)Fe precipitation index dependence Figure 5 is a plot of the tensile survival rate after 400 hours at 140°C versus the Fe precipitation index for several samples with an Fe content of 0.8 mass%. As shown in Figure 5, the lower the Fe precipitation index, i.e., the more Fe was dissolved, the higher the tensile survival rate after 400 hours at 140°C. Figure 5 confirms that by setting the Fe precipitation index to 0.70 or less, the tensile survival rate after 400 hours at 140°C could be made 84% or more.

[0201] (3-8) Ti precipitation index dependence Figure 6 is a plot of the electrical conductivity of Al alloy wires against the Ti precipitation index for multiple samples with the same Fe, Si, and Ti contents and the same Fe precipitation index. As shown in Figure 6, the higher the Ti precipitation index, i.e., the more Ti precipitated as Ti-B compounds, the higher the electrical conductivity of the Al alloy wire. From Figure 6, it was confirmed that by setting the Ti precipitation index to 1.03 or more, the electrical conductivity of the Al alloy wire could be made 62.5%IACS or more.

[0202] <Additional Notes> The following additionally describes aspects of the present disclosure.

[0203] [6] The radial structure function of Fe is (a) measuring an X-ray absorption fine structure spectrum μ(E) at the K absorption edge of Fe; (b) obtaining the extended X-ray absorption fine structure oscillation χ(k) based on the X-ray absorption fine structure spectrum μ(E) using formula (A); χ(k)={μ(E)-μs(E)} / μ0 ···(A) where: k is the wave number, E is the energy, μs(E) is the component obtained by approximating the center of the vibration component of μ(E) using a spline function, and μ0 is the absorbance difference before and after the absorption edge in μ(E), (c) dividing the extended X-ray absorption fine structure oscillation χ(k) by k 2 a step of performing weighting processing by (d) k obtained by (c) 2 χ(k) is the 30 nm wavelength of wave number k. -1 Over 80nm -1 Fourier transforming a region within This can be achieved by implementing [2] or [3]. The aluminum alloy wire according to [2] or [3].

[0204] [7] preparing a molten metal containing 0.020% by mass or more and 0.200% by mass or less of Fe, 0.005% by mass or more and 0.070% by mass or less of Si, 0.001% by mass or more and 0.020% by mass or less of Ti, 0.002% by mass or more and 0.100% by mass or less of B, with the balance being Al and unavoidable impurities; a step of holding the molten metal at a temperature of 700°C or higher for 7 hours or more; continuously casting the molten metal to form a casting material; rolling the cast material to form a rolled material; a step of wiredrawing the rolled material; Equipped with After the step of forming the rolled material and before the step of wiredrawing the rolled material, No intermediate heat treatment process is performed in which the rolled material is heated to a temperature of 300°C or higher. A method for manufacturing aluminum alloy wire. [Explanation of symbols]

[0205] 10 Electric wire 100 center 100a 1st central layer 100b 2nd central layer 110 Core Wire 112 Wire section 114 Covering part 200 twisted wire section 200a 1st strand layer 200b 2nd strand layer 210 Al alloy wire

Claims

1. An aluminum alloy wire, Fe is 0.020 mass% or more and 0.200 mass% or less, Si is 0.005 mass% or more and 0.070 mass% or less, Ti is 0.001 mass% or more and 0.020 mass% or less, B is 0.002 mass% or more and 0.100 mass% or less, Contains the balance being Al and unavoidable impurities; The electrical conductivity of the aluminum alloy wire is 62.5% IACS or more, The tensile strength of the aluminum alloy wire after heat treatment at 140°C for 400 hours is 84% ​​or more of the tensile strength before the heat treatment. Aluminum alloy wire.

2. The aluminum alloy wire satisfies formula (1) and formula (2). IFe1 / IFe0≦0.70...(1) xTi1 / xTi2≧1.03...(2) where: IFe1 is the height of a peak occurring within a radius range of 0.15 nm or more and 0.25 nm or less in a radial structure function obtained from X-ray absorption fine structure measurement at the K absorption edge of Fe in the aluminum alloy wire, IFe0 is the height of a peak occurring within a radius range of 0.15 nm or more and 0.25 nm or less in the radial structure function of Fe in a rolled iron material having a purity of 99.99% and a thickness of 0.005 mm as a standard sample, which is obtained under the same conditions as those under which the radial structure function of Fe in the aluminum alloy wire was obtained, xTi1 and xTi2 are the height of a first peak occurring within an incident X-ray energy range of 4978 eV to 4984 eV and the height of a second peak occurring within an incident X-ray energy range of 4986 eV to 4994 eV, respectively, in an X-ray absorption fine structure spectrum normalized by the absorbance difference before and after the Ti K-absorption edge in the aluminum alloy wire. The aluminum alloy wire according to claim 1 .

3. An aluminum alloy wire, Fe is 0.020 mass% or more and 0.200 mass% or less, Si is 0.005 mass% or more and 0.070 mass% or less, Ti is 0.001 mass% or more and 0.020 mass% or less, B is 0.002 mass% or more and 0.100 mass% or less, Contains the balance being Al and unavoidable impurities; The aluminum alloy wire satisfies formula (1) and formula (2). IFe1 / IFe0≦0.70...(1) xTi1 / xTi2≧1.03...(2) where: IFe1 is the height of a peak occurring within a radius range of 0.15 nm or more and 0.25 nm or less in a radial structure function obtained from X-ray absorption fine structure measurement at the K absorption edge of Fe in the aluminum alloy wire, IFe0 is the height of a peak occurring within a radius range of 0.15 nm or more and 0.25 nm or less in the radial structure function of Fe in a rolled iron material having a purity of 99.99% and a thickness of 0.005 mm as a standard sample, which is obtained under the same conditions as those under which the radial structure function of Fe in the aluminum alloy wire was obtained, xTi1 and xTi2 are the height of a first peak occurring within an incident X-ray energy range of 4978 eV to 4984 eV and the height of a second peak occurring within an incident X-ray energy range of 4986 eV to 4994 eV, respectively, in an X-ray absorption fine structure spectrum normalized by the absorbance difference before and after the Ti K-absorption edge in the aluminum alloy wire. Aluminum alloy wire.

4. The ratio of the Ti content to the B content in the aluminum alloy wire is 2.5 or less. The aluminum alloy wire according to any one of claims 1 to 3.

5. A stranded wire portion formed by stranding a plurality of aluminum alloy wires according to any one of claims 1 to 3. Electric wire.

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