Copper alloy wire, copper alloy stranded wire, electric wire, and method for manufacturing copper alloy wire

Abstract

A copper alloy wire formed from a copper alloy containing iron, phosphorus, tin, and auxiliary elements, the remainder comprising copper and unavoidable impurities, the auxiliary elements being two or more elements selected from the group consisting of zinc, nickel, and chromium or being only zinc, the iron content being 0.1-1.0 mass%, and the balance being copper and unavoidable impurities. The content ratio of phosphorus is from 0.1 mass% to 0.6 mass% (inclusive), the content ratio of tin is from 0.1 mass% to 0.4 mass% (inclusive), the content ratio of zinc when zinc is contained is from 0.005 mass% to 1.40 mass% (inclusive), the content ratio of nickel when nickel is contained is from 0.005 mass% to 0.70 mass% (inclusive), the content ratio of chromium when chromium is contained is from 0.005 mass% to 0.20 mass% (inclusive), and the balance of zinc and unavoidable impurities. The mass ratio of the total content of iron, nickel, and chromium to the content of phosphorus is 3.0-7.0.

Description

Technical Field

[0001] This disclosure relates to copper alloy wire, copper alloy stranded wire, electrical wire, and a method for manufacturing copper alloy wire.

[0002] This application claims priority based on Japanese Patent Application No. 2023-158331, filed on September 22, 2023, and incorporates all the contents of the aforementioned Japanese application. Background Technology

[0003] Traditionally, copper alloy wires have been used in electrical wiring harnesses and other applications. Excellent conductivity and strength are required for these copper alloy wires. These copper alloy wires are, for example, formed from copper alloys containing iron, phosphorus, and tin. Patent Documents 1 and 2 disclose copper alloy wires formed from copper alloys containing nickel in addition to iron, phosphorus, and tin.

[0004] Existing technical documents Patent documents Patent Document 1: International Publication No. 2020 / 039712; Patent Document 2: International Publication No. 2020 / 039711. Summary of the Invention

[0005] The copper alloy wire disclosed herein is formed from a copper alloy. The copper alloy contains iron, phosphorus, tin, and secondary elements, with the balance consisting of copper and unavoidable impurities. The secondary elements are two or more elements selected from the group consisting of zinc, nickel, and chromium, or zinc alone. The iron content is 0.1% by mass or more and 1.0% by mass or less. The phosphorus content is 0.1% by mass or more and 0.6% by mass or less. The tin content is 0.1% by mass or more and 0.4% by mass or less. When zinc is included, the zinc content is 0.005% by mass or more and 1.40% by mass or less. When nickel is included, the nickel content is 0.005% by mass or more and 0.70% by mass or less. When chromium is included, the chromium content is 0.005% by mass or more and 0.20% by mass or less. The combined content of iron, nickel, and chromium relative to the phosphorus content is a mass ratio of 3.0 or more and 7.0 or less. Attached Figure Description

[0006] Figure 1 This is a schematic diagram illustrating an example of a copper alloy wire involved in the embodiment.

[0007] Figure 2 This is a schematic diagram illustrating an example of a copper alloy stranded wire and electrical wire involved in the embodiment. Detailed Implementation

[0008] [The problem this disclosure aims to solve] From the perspective of the risk of depletion of metal resources, research is underway to use used wire harness scraps as raw materials to manufacture copper alloy wires. Wire harness scraps contain terminals and other accessories attached to both ends of the wire. If wire harness scraps are mixed into the raw materials, elements such as zinc, nickel, and chromium contained in the accessories will be incorporated into the copper alloy wire. If a certain amount of these elements are present, conductivity and other properties of the copper alloy wire will decrease, thus affecting its characteristics. This results in copper alloy wires that do not meet required properties. The aim is to mitigate the degradation of copper alloy wire properties even when elements such as zinc, nickel, and chromium are present.

[0009] One of the purposes of this disclosure is to provide a copper alloy wire with excellent conductivity and strength.

[0010] [The Effects of This Disclosure] The copper alloy wire disclosed herein has excellent conductivity and strength.

[0011] [Description of embodiments of this disclosure] First, embodiments of this disclosure will be described.

[0012] (1) The copper alloy wire of this disclosure is formed from a copper alloy. The copper alloy contains iron, phosphorus, tin, and secondary elements, with the balance consisting of copper and unavoidable impurities. The secondary elements are two or more elements selected from the group consisting of zinc, nickel, and chromium, or only zinc. The content of iron is 0.1% by mass or more and 1.0% by mass or less. The content of phosphorus is 0.1% by mass or more and 0.6% by mass or less. The content of tin is 0.1% by mass or more and 0.4% by mass or less. When zinc is included, the content of zinc is 0.005% by mass or more and 1.40% by mass or less. When nickel is included, the content of nickel is 0.005% by mass or more and 0.70% by mass or less. When chromium is included, the content of chromium is 0.005% by mass or more and 0.20% by mass or less. The total content of iron, nickel, and chromium relative to the content of phosphorus is 3.0 or more and 7.0 by mass.

[0013] The copper alloy wire disclosed herein exhibits excellent conductivity and strength. This copper alloy wire achieves excellent conductivity and strength by including iron, phosphorus, and tin. Generally, conductivity decreases as the amount of added elements in solid solution increases. By maintaining the aforementioned mass ratio between 3.0 and 7.0, iron, nickel, and chromium readily precipitate together with phosphorus. As a result, the amount of iron, nickel, and chromium dissolved in copper is reduced. Therefore, even if the copper alloy wire sometimes contains secondary elements, as long as the proportions of each element are within a predetermined range, good conductivity can be achieved, balancing strength and conductivity.

[0014] (2) Alternatively, in the copper alloy wire of (1) above, the total content of zinc, nickel and chromium is 0.05% by mass or more.

[0015] Even if the proportion of secondary elements is high, the copper alloy wire described in (2) above can still have good conductivity.

[0016] (3) Alternatively, in the copper alloy wire of (1) or (2) above, the tensile strength of the copper alloy wire is 400 MPa or above.

[0017] The copper alloy wire described in (3) above has high tensile strength and excellent strength.

[0018] (4) Alternatively, in any of the copper alloy wires in (1) to (3) above, the elongation at break of the copper alloy wire is 5% or more.

[0019] The copper alloy wire described above (4) has a high elongation at break and excellent elongation.

[0020] (5) Alternatively, in any of the copper alloy wires in (1) to (4) above, the conductivity of the copper alloy wire is 59% IACS or higher.

[0021] The copper alloy wire described in (5) above has high conductivity and excellent electrical properties. "%IACS" indicates that the conductivity of international annealed copper is set to 100% IACS. The resistivity of international annealed copper is 1.7241 × 10⁻⁶. -8 Ωm.

[0022] (6) Alternatively, in any of the copper alloy wires in (1) to (5) above, the tensile strength of the copper alloy wire is 400 MPa or more, the elongation at break of the copper alloy wire is 5% or more, and the conductivity of the copper alloy wire is 59% IACS or more.

[0023] The copper alloy wire described above (6) has an excellent balance of tensile strength, elongation at break and conductivity, and has excellent strength, elongation and conductivity.

[0024] (7) The copper alloy stranded wire of this disclosure is formed by stranding multiple copper alloy wires of (6) above.

[0025] The copper alloy stranded wire disclosed herein is formed from the copper alloy wire described in (6) above, and therefore has excellent strength, elongation and conductivity.

[0026] (8) The wire of this disclosure has a conductor and an insulating layer covering the conductor. The conductor is the copper alloy stranded wire of (7) above.

[0027] The wire disclosed herein has the copper alloy stranded wire of the disclosed invention, and therefore has excellent strength, elongation and conductivity.

[0028] (9) The method for manufacturing copper alloy wire disclosed herein comprises: a step of preparing a casting material formed of copper alloy; a step of preparing a drawing material by drawing the casting material; and a step of heat-treating the drawing material. The copper alloy comprises iron, phosphorus, tin, and secondary elements, with the balance consisting of copper and unavoidable impurities. The secondary elements are two or more elements selected from the group consisting of zinc, nickel, and chromium, or only zinc. The iron content is 0.1% by mass or more and 1.0% by mass or less. The phosphorus content is 0.1% by mass or more and 0.6% by mass or less. The tin content is 0.1% by mass or more and 0.4% by mass or less. When zinc is included, the zinc content is 0.005% by mass or more and 1.40% by mass or less. When nickel is included, the nickel content is 0.005% by mass or more and 0.70% by mass or less. When chromium is included, the chromium content is 0.005% by mass or more and 0.20% by mass or less. The combined content of iron, nickel, and chromium relative to the content of phosphorus is at a mass ratio of 3.0 or higher and 7.0 or lower.

[0029] The method for manufacturing copper alloy wire disclosed herein enables the production of copper alloy wires with excellent conductivity and strength. The copper alloy wire, by containing iron, phosphorus, and tin, achieves excellent conductivity and strength. By maintaining the aforementioned mass ratio between 3.0 and 7.0, iron, nickel, and chromium readily precipitate along with phosphorus. As a result, the amount of elements such as iron, nickel, and chromium dissolved in copper is reduced. Therefore, even if secondary elements are sometimes present in the copper alloy wire, as long as the content ratio of each element is within a predetermined range, good conductivity can be achieved, balancing strength and conductivity.

[0030] (10) Alternatively, in the copper alloy wire manufacturing method of (9) above, in the heat treatment process of the wire drawing material, the wire drawing material is kept at a temperature of 300°C or higher and 700°C or lower for 4 hours or more and 40 hours or less.

[0031] The copper alloy wire manufacturing method described in (9) above allows for the easy precipitation of iron, nickel, chromium, and phosphorus together through heat treatment under the aforementioned conditions. This precipitation improves the conductivity of the copper alloy wire. Furthermore, the heat treatment under the aforementioned conditions softens the copper alloy wire. This softening improves the elongation of the copper alloy wire.

[0032] [Details of the embodiments disclosed herein] The following describes specific examples of copper alloy wires, copper alloy stranded wires, and electrical wires according to this disclosure. In the figures, the same reference numerals denote objects with the same names. For ease of explanation, parts of the structure are sometimes shown exaggeratedly or simplified in the figures. The dimensional proportions of the parts in the figures may also differ from the actual dimensions.

[0033] <Copper alloy wire> Figure 1 The copper alloy wire 1 of the illustrated embodiment is formed from a copper alloy having a specific composition. The copper alloy contains specific additive elements within a specific range.

[0034] (composition) Copper alloys have the following composition: containing iron (Fe), phosphorus (P), tin (Sn), and auxiliary elements, with the balance being copper (Cu) and unavoidable impurities. The auxiliary elements are two or more elements selected from the group consisting of zinc (Zn), nickel (Ni), and chromium (Cr), or only Zn. Of the aforementioned elements contained in copper alloys, Fe, P, and Sn are essential elements.

[0035] The effects and proportions of each element in the copper alloy are explained below. The proportions of each element are expressed as the mass percentage when the total mass of the copper alloy is set at 100%.

[0036] ·Fe Fe and P form compounds and precipitate out, thereby strengthening the copper alloy.

[0037] The Fe content is 0.1% by mass or more and 1.0% by mass or less. By making the Fe content 0.1% by mass or more, a compound containing Fe and P is formed. The strength of the copper alloy is improved by the precipitation of this compound in Cu. Furthermore, the precipitation of the above-mentioned compound reduces the amount of Fe and P dissolved in Cu, thereby mitigating the decrease in the conductivity of the copper alloy. Therefore, copper alloy wire 1 exhibits excellent conductivity and strength.

[0038] By keeping the Fe content to 1.0% by mass or less, not only is the decrease in conductivity of the copper alloy mitigated, but the coarsening of the aforementioned compounds is also prevented. Therefore, the copper alloy exhibits a microstructure with finely dispersed compounds. Consequently, the copper alloy wire 1 possesses excellent elongation. Furthermore, wire breakage caused by coarse compounds is less likely to occur during the manufacturing process of the copper alloy wire 1, thus the manufacturability of the copper alloy wire 1 is also excellent. The Fe content can be 0.11% by mass or more and 0.9% by mass or less, or 0.12% by mass or more and 0.8% by mass or less.

[0039] ·P P forms compounds with elements such as Fe, Ni, and Cr, which precipitate out and thus strengthen the copper alloy.

[0040] The content of phosphorus (P) is 0.1% by mass or more and 0.6% by mass or less. By making the content of P 0.1% by mass or more, a compound containing P is formed by reacting with elements such as Fe. By precipitating this compound in Cu, as described above, the strength of the copper alloy is improved and the decrease in conductivity of the copper alloy is mitigated. Therefore, copper alloy wire 1 has excellent conductivity and strength. Furthermore, a portion of P acts as a deoxidizer, allowing it to be included in the copper alloy as a phosphorus oxide.

[0041] By keeping the content of P at 0.6% by mass or less, in addition to mitigating the decrease in conductivity of the copper alloy, it is also possible to prevent the coarsening of the aforementioned compounds. Therefore, the copper alloy has a microstructure in which the aforementioned compounds are finely dispersed. Furthermore, during the manufacturing process of the copper alloy wire 1, wire breakage caused by coarse compounds is less likely to occur. The content of P can be 0.11% by mass or more and 0.5% by mass or less, or 0.12% by mass or more and 0.4% by mass or less.

[0042] ·Sn Sn solid solution strengthens copper alloys.

[0043] The Sn content is 0.1% by mass or more and 0.4% by mass or less. By making the Sn content 0.1% by mass or more, an increase in strength due to Sn can be achieved. By making the Sn content 0.4% by mass or less, the decrease in conductivity caused by Sn dissolving in Cu can be mitigated. Therefore, the copper alloy wire 1 has excellent conductivity and strength. If Sn is excessively dissolved in Cu, the workability of the copper alloy decreases. If the Sn content is 0.4% by mass or less, it is easy to obtain the copper alloy wire 1 with excellent elongation, and the wire drawing process is also easy during the manufacturing of the copper alloy wire 1. Therefore, the workability of the copper alloy wire 1 is also excellent. The Sn content can be 0.2% by mass or more and 0.35% by mass or 0.25% by mass or more and 0.35% by mass or less.

[0044] In addition to Fe, P, and Sn, copper alloys also contain secondary elements. These secondary elements are selected from two or more elements in the group consisting of Zn, Ni, and Cr, or are Zn alone. The combinations of secondary elements can be any of the following: Zn, Ni, and Cr; Zn and Ni; Zn and Cr; Ni and Cr; or Zn alone. The proportions of Zn, Ni, and Cr are shown below.

[0045] ·Zn Zn exists in a solid solution form in Cu. The Zn content in copper alloys is 0.005% by mass or more and 1.40% by mass or less. By keeping the Zn content to 1.40% by mass or less, the decrease in conductivity caused by Zn's solid solution in Cu can be mitigated. In the case of Ni and Cr, Zn may be omitted; that is, the Zn content can be zero. If the Zn content is less than 0.005% by mass, Zn is considered to have almost no effect on properties. When the Zn content is less than 0.005% by mass, Zn is considered an unavoidable impurity. The Zn content can be further 0.01% by mass or more, or 0.02% by mass or more. The Zn content can be 0.05% by mass or more and 1.35% by mass or less, or 0.10% by mass or more and 1.30% by mass or less. The Zn content can be further 0.40% by mass or less, 0.35% by mass or less, or 0.30% by mass or less.

[0046] Ni Ni is precipitated in Cu by forming a compound with P. The proportion of Ni in copper alloys is 0.005% by mass or more and 0.70% by mass or less. By keeping the Ni content to 0.70% by mass or less, the decrease in conductivity caused by Ni can be mitigated. Furthermore, the precipitation of compounds containing Ni and P reduces the amount of Ni and P dissolved in Cu, resulting in a less severe decrease in conductivity. In the case of Zn and Cr, or in the case of Zn only, Ni may not be included. That is, the Ni content can be zero. If the Ni content is less than 0.005% by mass, Ni is considered to have almost no effect on the properties. When the Ni content is less than 0.005% by mass, Ni is considered an unavoidable impurity. The Ni content can be further 0.01% by mass or more, or 0.02% by mass or more. The Ni content can be 0.10% by mass or more and 0.60% by mass or less, or 0.20% by mass or more and 0.50% by mass or less.

[0047] ·Cr Cr is precipitated in Cu by forming Cr-containing intermetallic compounds or by forming compounds with P. The Cr content in copper alloys is 0.005% by mass or more and 0.20% by mass or less. By keeping the Cr content to 0.20% by mass or less, the decrease in conductivity caused by Cr can be mitigated. Furthermore, the precipitation of Cr and P-containing compounds reduces the amount of Cr and P dissolved in Cu, resulting in a less severe decrease in conductivity. In the case of Zn and Ni, or in the case of Zn only, Cr may not be included. That is, the Cr content can be zero. If the Cr content is less than 0.005% by mass, Cr is considered to have almost no effect on the properties. When the Cr content is less than 0.005% by mass, Cr is considered an unavoidable impurity. The Cr content can be 0.01% by mass or more and 0.18% by mass or less. The Cr content can be further 0.16% by mass or less, 0.10% by mass or less, or 0.08% by mass or less.

[0048] Other added elements Copper alloys may contain aluminum (Al) or silicon (Si). Al has the effect of reducing the segregation of P towards grain boundaries. The content of Al is, for example, 0.005% by mass or more and 1.0% by mass or less. The content of Al can be further 0.01% by mass or more. Si acts as a deoxidizer for Fe, P, Sn, etc., and has the effect of reducing the oxidation of these elements. The content of Si is, for example, 0.005% by mass or more and 1.0% by mass or less. The content of Si can be further 0.01% by mass or more.

[0049] ·(Fe+Ni+Cr) / P The mass ratio X of the total content of Fe, Ni, and Cr relative to the content of P is 3.0 or more and 7.0 or less. When the mass ratio X is within the above range, Fe, Ni, and Cr readily precipitate together with P. The reduced amount of these elements dissolved in Cu results in an improved strength of the copper alloy and a reduced decrease in its conductivity. Therefore, copper alloy wire 1 exhibits excellent conductivity and strength. The mass ratio X can be 3.2 or more and 6.9 or less, or 3.5 or more and 6.8 or less.

[0050] Copper alloy wire 1, by containing Fe, P, and Sn, exhibits excellent conductivity and strength. However, if, in addition to the basic composition of Fe, P, and Sn, secondary elements selected from Zn, Ni, and Cr are added, the conductivity decreases. If the mass ratio X is 3.0 or higher and 7.0 or lower, Fe, Ni, and Cr readily precipitate along with P. Therefore, when the mass ratio X satisfies 3.0 or higher and 7.0 or lower, even with the occasional inclusion of secondary elements, as long as the proportions of each element are within a predetermined range, good conductivity can be achieved, balancing strength and conductivity.

[0051] <The total percentage of added elements> The total percentage of additive elements in the copper alloy, that is, the total percentage of Fe, P, and Sn with secondary elements, is, for example, 1.00% by mass or more and 3.00% by mass or less. The total percentage of additive elements can be 1.04% by mass or more and 2.90% by mass or less, 1.14% by mass or more and 2.80% by mass or less, or 1.20% by mass or more and 2.70% by mass or less. The total percentage of additive elements can be further 2.50% by mass or less, 2.40% by mass or less, 2.30% by mass or less, or 2.20% by mass or less.

[0052] <Proportion of secondary elements> The content of secondary elements, i.e., the combined content of Zn, Ni, and Cr, is, for example, 0.05% by mass or more. The upper limit for the content of secondary elements is, for example, 1.70% by mass. The content of secondary elements can be further 0.20% by mass or more, or 0.30% by mass or more. The content of secondary elements can be 0.05% by mass or more and 1.70% by mass or less, 0.10% by mass or more and 1.60% by mass or less, 0.15% by mass or more and 1.50% by mass or less, or 0.20% by mass or more and 1.40% by mass or less. The content of secondary elements can be further 1.10% by mass or less, 1.00% by mass or less, or 0.90% by mass or less.

[0053] The composition of the copper alloy wire 1 can be investigated using known analytical methods. These methods include, for example, inductively coupled plasma (ICP) emission spectroscopy or fluorescence X-ray analysis.

[0054] (organize) <Crystal Grain Size> Copper alloys possess a fine crystalline structure. Copper alloy wires with a fine crystalline structure exhibit high strength. The average grain size of copper alloys is, for example, 0.1 μm or more and 10 μm or less. The smaller the grain size, the higher the strength of the copper alloy wire. The average grain size of copper alloys can also be 7 μm or less, or 5 μm or less.

[0055] The average grain size of the copper alloy was determined as follows. A cross-section of the copper alloy wire was observed under a microscope. The cross-section was orthogonal to the length of the copper alloy wire. The microscope could be an optical microscope or a scanning electron microscope (SEM). Based on the observed image, a predetermined observation area was selected, and the area of ​​each grain within the observation area was measured. The diameter of a circle with an area equal to that of each grain was calculated as the grain size, and the average of these circles was taken as the average grain size. This grain size calculation could be performed using a commercially available image processing device. The observation area could be a range containing 50 or more grains, or the entire cross-section. By sufficiently expanding the observation area in this way, errors caused by particles such as precipitates could be significantly reduced.

[0056] <Extract> Furthermore, the copper alloy contains precipitates composed of the aforementioned compounds. These precipitates are finely dispersed within the copper alloy. The smaller the particle size of the precipitates, the less likely they are to become the initiation point for fracture. Therefore, the strength of the copper alloy wire is increased. The average particle size of the precipitates is, for example, 1 nm or more and 2 μm or less.

[0057] The determination of the average particle size of the precipitates described above is performed similarly to the determination of the average crystal particle size of the copper alloy described above, by observing the cross-section of the copper alloy wire using a microscope. In the observed image, the area of ​​all precipitates within the observation range is measured. The diameter of a circle having an area equal to that of each precipitate is calculated as the particle size of the precipitate, and the average of these circles is taken as the average particle size of the precipitate. The particle size can be calculated using a commercially available image processing device. In the determination of the average particle size of the precipitates, the average particle size across three observation ranges is calculated. Each observation range is a rectangular area with a cross-section size of 5 μm × 3 μm. The magnification of the microscope is, for example, 400x or higher and 20,000x or lower.

[0058] Specific examples of the compounds constituting the precipitates are described below. The precipitates are, for example, compounds containing Fe and P. When Ni is included as a secondary element, compounds containing Ni and P, as well as compounds containing Fe, Ni, and P, are sometimes formed as precipitates. When Cr is included as a secondary element, compounds containing Cr and P, as well as compounds containing Fe, Cr, and P, are sometimes formed as precipitates. When Ni and Cr are included as secondary elements, compounds containing Ni, Cr, and P, as well as compounds containing Fe, Ni, Cr, and P, are sometimes formed as precipitates.

[0059] The composition of the compounds constituting the precipitates is described. The proportions of each element in the compounds constituting the precipitates are as follows. The proportions of each element in the compounds shown below are mass percentages when the compound is set to 100% by mass. The composition of the compounds can be analyzed, for example, by energy-dispersive X-ray spectroscopy.

[0060] When a compound contains all of the four elements Fe, Ni, Cr and P, for example, Fe is present in a proportion of 30% or more and 65% or less by mass, Ni is present in a proportion of 2% or more and 40% or less by mass, Cr is present in a proportion of 10% or more and 25% or less by mass, and P is present in a proportion of 15% or more and 25% or less by mass.

[0061] When the compound contains only Fe and P from the four elements mentioned above, for example, the content of Fe is 70% or more and 85% or less by mass, and the content of P is 15% or more and 30% or less by mass.

[0062] When the compound contains Fe, Ni and P from the above four elements, for example, the content of Fe is 40% or more and 80% or less by mass, the content of Ni is 4% or more and 40% or less by mass, and the content of P is 15% or more and 25% or less by mass.

[0063] When the compound contains Fe, Cr and P from the above four elements, for example, the content of Fe is 45% or more and 65% or less by mass, the content of Cr is 15% or more and 45% or less by mass, and the content of P is 5% or more and 30% or less by mass.

[0064] (shape) The cross-sectional shape of the copper alloy wire 1 can be any shape. Figure 1 The copper alloy wire 1 shown is a circular wire with a circular cross-section. The cross-section of the copper alloy wire 1 is orthogonal to its length. The shape of the cross-section of the copper alloy wire 1 can be non-circular. Non-circular shapes include polygons and ovals. Polygons include quadrilaterals and hexagons. Quadrilaterals include rectangles and squares. Oval shapes include ellipses.

[0065] (Wire diameter) The diameter D of the copper alloy wire 1 is, for example, 0.025 mm or more and 0.5 mm or less. When the cross-sectional shape of the copper alloy wire 1 is circular, the diameter D is equal to the diameter of the cross-section. When the cross-sectional shape of the copper alloy wire 1 is non-circular, the diameter D is considered to be the diameter of a circle with an area equal to the area of ​​the cross-section. The smaller the diameter D, the thinner and lighter the copper alloy wire 1. The diameter D of the copper alloy wire 1 can be 0.05 mm or more and 0.35 mm or less, or 0.1 mm or more and 0.3 mm or less.

[0066] (characteristic) The copper alloy wire 1 has at least one of the following characteristics.

[0067] • Tensile strength is above 400MPa.

[0068] • The elongation at break is 5% or more.

[0069] • Conductivity is above 59% IACS.

[0070] Copper alloy wire 1 can possess all three of the above-mentioned properties. Copper alloy wire 1 possessing all three of the above-mentioned properties has an excellent balance of tensile strength, elongation at break, and conductivity, exhibiting excellent strength, elongation, and conductivity.

[0071] <Tensile Strength> Copper alloy wire 1 with a tensile strength of 400 MPa or higher exhibits excellent strength. The tensile strength can be 420 MPa or higher, or 440 MPa or higher. For example, the upper limit of the tensile strength is 640 MPa. There is a tendency for higher tensile strength to result in lower elongation at break and lower conductivity. From the viewpoint of achieving good conductivity while balancing the strength and elongation of the copper alloy wire 1, the tensile strength can be 600 MPa or lower, or 580 MPa or lower. The tensile strength can be 400 MPa or higher and 640 MPa or lower, 420 MPa or higher and 600 MPa or lower, or 440 MPa or higher and 580 MPa or lower.

[0072] <Elongation at break> Copper alloy wire 1 with an elongation at break of 5% or more exhibits excellent elongation. The elongation at break can be 6% or more, or 7% or more. The upper limit of the elongation at break is, for example, 20%. There is a tendency for higher elongation at break to correlate with lower tensile strength. From the perspective of balancing the strength and elongation of copper alloy wire 1, the elongation at break can be 15% or less, or 13% or less. The elongation at break can be 5% or more and 20% or less, 6% or more and 15% or less, or 7% or more and 13% or less. Copper alloy wire 1 with a tensile strength of 400 MPa or more and an elongation at break of 5% or more demonstrates an excellent balance between tensile strength and elongation at break, exhibiting excellent strength and elongation.

[0073] Tensile strength and elongation at break can be determined by tensile testing. Tensile testing is conducted according to "JIS Z 2241:2011 Metallic Materials - Tensile Testing".

[0074] <Conductivity> Copper alloy wire 1 with a conductivity of 59% IACS or higher exhibits excellent conductivity. Conductivity can be 60% IACS or higher, or 61% IACS or higher. The upper limit of conductivity is, for example, 75% IACS. There is a tendency for higher conductivity to result in lower tensile strength. From the viewpoint of balancing the strength and conductivity of copper alloy wire 1, conductivity can be 70% IACS or lower, or 66% IACS or lower. Conductivity can be 59% IACS or higher and 75% IACS or lower, 60% IACS or higher and 70% IACS or lower, or 61% IACS or higher and 66% IACS or lower. Copper alloy wire 1 with a tensile strength of 400 MPa or higher and a conductivity of 59% IACS or higher achieves an excellent balance between tensile strength and conductivity, exhibiting excellent strength and conductivity.

[0075] Conductivity can be measured using the four-terminal method. Specifically, conductivity is calculated by measuring the resistance of a 1m long copper alloy wire 1.

[0076] <Copper alloy stranded wire> Figure 2 The copper alloy stranded wire 2 shown is a stranded wire using the aforementioned copper alloy wire 1 as the conductor, formed by twisting multiple copper alloy wires 1 together. The copper alloy stranded wire 2 can withstand a greater tensile load than a single copper alloy wire 1, and can also carry a large current. The copper alloy stranded wire 2 is easy to bend or twist, exhibiting excellent bending and torsional properties. Figure 2 The example illustrates a copper alloy stranded wire 2 formed by concentrically twisting seven copper alloy wires 1. The number of strands and the twisting method of the copper alloy wires 1 can be changed appropriately.

[0077] The copper alloy stranded wire 2 can also be a compressed stranded wire (not shown) formed by compressing after stranding. The outer diameter of the compressed stranded wire is smaller than that of the simply stranded wire.

[0078] <Wire> Figure 2 The wire 3 shown has a conductor 31 and an insulation layer 32 surrounding the conductor 31. The conductor 31 is the aforementioned copper alloy stranded wire 2. The insulation layer 32 is formed of a known insulating material. The insulating material is a resin such as polyvinyl chloride (PVC) or polypropylene (PP).

[0079] The wire 3 may also be a wire with an attached terminal (not shown) installed at the end of the conductor 31. The terminal is, for example, a crimp terminal. The crimp terminal is installed at the end of the conductor 31 exposed after the insulation layer 32 has been removed.

[0080] <Manufacturing Methods of Copper Alloy Wire> The copper alloy wire 1 of the embodiment can be manufactured by the copper alloy wire manufacturing method of the embodiment. The copper alloy wire manufacturing method of the embodiment includes a first step, a second step, and a third step in sequence. Each step is described below.

[0081] The first step is to produce casting materials made of copper alloy.

[0082] The second process is to draw the casting material to produce wire drawing material.

[0083] The third process is the heat treatment of the wire drawing material.

[0084] (First process) The casting material is produced by casting a molten copper alloy having the above-described composition, containing Fe, P, Sn, and secondary elements. The raw material for the casting material can be used materials such as spent wire harness scrap. In addition to Fe, P, and Sn, the wire harness scrap contains one or more secondary elements selected from Zn, Ni, and Cr. Alternatively, Cu-Fe alloys, Cu-P alloys, Sn, etc., can be mixed into the raw material to adjust the composition of the copper alloy to the range described above.

[0085] Casting materials can be produced using known casting methods. Examples of casting methods include the pulley method, the double-belt method, and the upward casting method. Casting materials can be, for example, circular wires with a circular cross-section. The wire diameter of the casting material can be, for example, 5 mm or more but less than 40 mm. The wire diameter of the casting material is the diameter of a circle having an area equal to the cross-sectional area of ​​the casting material.

[0086] (Second process) By drawing the cast material, a wire-drawn material with a predetermined wire diameter is produced. The drawing process is performed in a cold state. The drawing process can be repeated until the wire-drawn material reaches the predetermined wire diameter. The wire diameter of the wire-drawn material is, for example, 0.025 mm or more and 0.5 mm or less, 0.05 mm or more and 0.35 mm or less, or 0.1 mm or more and 0.3 mm or less.

[0087] Intermediate heat treatment can also be performed midway through the wire drawing process. Intermediate heat treatment improves machinability by removing processing strain. The temperatures for intermediate heat treatment are, for example, 350°C to 1000°C, 380°C to 950°C, or 400°C to 900°C. The durations for intermediate heat treatment are, for example, 10 minutes to 16 hours, 20 minutes to 12 hours, or 30 minutes to 8 hours. The duration of intermediate heat treatment refers to the time spent maintaining the above-mentioned temperatures. Intermediate heat treatment can be performed more than twice.

[0088] (Third process) Copper alloy wire is manufactured by heat-treating the drawn material. This heat treatment precipitates elements such as Fe, P, Ni, and Cr dissolved in the copper alloy and softens the work-hardened material obtained through drawing. Hereinafter, this heat treatment is referred to as aging treatment. The aging treatment temperature is, for example, 300°C or higher and 700°C or lower, or 350°C or higher and 650°C or lower. The aging treatment temperature can be further increased to 400°C or higher, or 420°C or higher. The aging treatment time is, for example, 4 hours or higher and 40 hours or lower, 5 hours or higher and 20 hours or lower, or 6 hours or higher and 10 hours or lower. The aging treatment time refers to the time spent maintaining the above-mentioned temperature.

[0089] The aforementioned elements precipitate through aging treatment, thereby increasing the strength of the copper alloy wire and mitigating the decrease in its conductivity. Furthermore, the aging treatment softens the copper alloy wire, thereby increasing its elongation. The diameter of the copper alloy wire is equal to the diameter of the drawing material.

[0090] [Experimental Example 1] Samples of copper alloy wires with the compositions shown in Table 1 were manufactured. The compositions of samples No. 1-1 to No. 1-22, within the range of compositions in this embodiment, include Fe, P, and Sn, and secondary elements selected from Zn, Ni, and Cr. The compositions of samples No. 1-1 to No. 1-10, No. 1-17 to No. 1-19, No. 1-21, and No. 1-22 include Zn, Ni, and Cr as secondary elements. The compositions of samples No. 1-11 to No. 1-13 include two of Zn, Ni, and Cr as secondary elements. The secondary elements of sample No. 1-11 are Zn and Cr. The secondary elements of sample No. 1-12 are Ni and Cr. The secondary elements of sample No. 1-13 are Zn and Ni. The compositions of samples No. 1-14 to No. 1-16 and No. 1-20 contain only Zn as a secondary element. The mass ratio X in samples No.1-1 to No.1-22 is 3.0 or higher and 7.0 or lower.

[0091] In Table 1, the item "Total Amount of Added Elements" is expressed as the total proportion of added elements, that is, the total proportion of Fe, P, and Sn with the secondary elements, to two decimal places. The item "Zn+Ni+Cr" is expressed as the total proportion of secondary elements, that is, the total proportion of Zn, Ni, and Cr, to two decimal places. The item "(Fe+Ni+Cr) / P" represents the mass ratio X of the total proportion of Fe, Ni, and Cr relative to the proportion of P.

[0092] The compositions of samples No. 1-100 to No. 1-110 and samples No. 1-121 to No. 1-124 are outside the range of compositions in this embodiment. Sample No. 1-100 has a basic composition containing only Fe, P, and Sn, and substantially no secondary elements. Sample No. 1-101 to No. 1-110 contain secondary elements. Sample No. 1-101 to No. 1-108 contain Zn, Ni, and Cr as secondary elements. The mass ratio X in samples No. 1-101 to No. 1-107 is greater than 7.0. Sample No. 1-108 contains an excess of Ni. Sample No. 1-109 contains only Cr as a secondary element, and the mass ratio X is less than 3.0. Sample No. 1-110 contains only Ni as a secondary element, and the mass ratio X is greater than 7.0. The compositions of samples No.1-121 to No.1-124 contain only Ni as an auxiliary element, and the mass ratio X is above 3.0 and below 7.0.

[0093] Casting materials of copper alloys with the compositions shown in Table 1 were prepared. The wire diameters of the casting materials for each sample are shown in Table 2. The prepared casting materials were then drawn to produce wire-drawn materials. The wire diameters of the wire-drawn materials for each sample are shown in Table 2. The produced wire-drawn materials were then subjected to aging treatment. The aging treatment conditions were set to the temperatures and times shown in Table 2.

[0094] [Composition Analysis] The composition of the copper alloy wires in each manufactured sample was investigated by ICP emission spectroscopy. The results are shown in Table 1.

[0095] 〔characteristic〕 The tensile strength, elongation at break, and electrical conductivity of the copper alloy wires for each sample were determined. The results of these properties are shown in Table 2. The methods for determining these properties are as described above. Each property was measured at room temperature.

[0096] [Table 1]

[0097] [Table 2]

[0098] As shown in Table 2, the copper alloy wires of samples No. 1-1 to No. 1-22 have a tensile strength of over 400 MPa, an elongation at break of over 5%, and a conductivity of over 59% IACS. The copper alloy wires of samples No. 1-1 to No. 1-22 exhibit excellent strength, elongation, and conductivity.

[0099] The copper alloy wires of Samples No. 1-1 to No. 1-22 possess properties equal to or better than those of the copper alloy wire of Sample No. 1-100, which has the same basic composition. It is believed that the copper alloy wires of Samples No. 1-1 to No. 1-22, despite containing secondary elements, can possess properties equivalent to those of the copper alloy wire of Sample No. 1-100, as follows: The content of P in the copper alloy wires of Samples No. 1-1 to No. 1-22 was adjusted so that the mass ratio X satisfies 3.0 or more and 7.0 or less. Through the precipitation of Fe, Ni, and Cr along with P, the amount of these elements dissolved in Cu is reduced. It is believed that, as a result, good electrical conductivity is achieved, balancing strength and conductivity.

[0100] The copper alloy wires of samples No. 1-101 to No. 1-110 contain secondary elements. It is believed that the low conductivity of the copper alloy wires of samples No. 1-101 to No. 1-107 and the low conductivity of the copper alloy wire of sample No. 1-110 is due to a mass ratio X greater than 7.0. In samples No. 1-101 to No. 1-107 and No. 1-110, P is insufficient, thus preventing Fe, Ni, and Cr from precipitating along with P. Therefore, it is believed that the copper alloy wires of samples No. 1-101 to No. 1-107 and No. 1-110 exhibit poor conductivity. It is believed that the low conductivity of the copper alloy wire of sample No. 1-108 is due to an excessive amount of Ni. It is believed that the low conductivity of the copper alloy wire of sample No. 1-109 is due to a mass ratio X less than 3.0, resulting in some P remaining unprecipitated and dissolved.

[0101] The copper alloy wires of Specimen No. 1-121 to Specimen No. 1-124 are reference examples containing only Ni as a secondary element. The mass ratio X of the copper alloy wires of Specimen No. 1-121 to Specimen No. 1-124 is 3.0 or more and 7.0 or less, and they have the same characteristics as the copper alloy wire of Specimen No. 1-100.

[0102] Furthermore, the invention is not limited to these examples, as indicated by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0103] Explanation of reference numerals in the attached figures 1: Copper alloy wire 2: Copper alloy stranded wire 3: Electrical wires 31: Conductor 32: Insulation layer D: wire diameter

Claims

1. A copper alloy wire, wherein, The copper alloy wire is formed of copper alloy. The copper alloy contains iron, phosphorus, tin, and secondary elements, with the balance consisting of copper and unavoidable impurities. The secondary element is selected from two or more elements in the group consisting of zinc, nickel, and chromium, or only zinc. The iron content is between 0.1% and 1.0% by mass. The phosphorus content is between 0.1% and 0.6% by mass. The tin content is between 0.1% and 0.4% by mass. When zinc is included, the zinc content is 0.005% by mass or more and 1.40% by mass or less. When nickel is included, the nickel content is 0.005% by mass or more and 0.70% by mass or less. When chromium is included, the chromium content is 0.005% by mass or more and 0.20% by mass or less. The combined content of iron, nickel, and chromium relative to the content of phosphorus is at a mass ratio of 3.0 or higher and 7.0 or lower.

2. The copper alloy wire according to claim 1, wherein, The combined content of zinc, nickel, and chromium is 0.05% by mass or more.

3. The copper alloy wire according to claim 1 or 2, wherein, The tensile strength of the copper alloy wire is above 400 MPa.

4. The copper alloy wire according to any one of claims 1 to 3, wherein, The elongation at break of the copper alloy wire is 5% or more.

5. The copper alloy wire according to any one of claims 1 to 4, wherein, The conductivity of the copper alloy wire is above 59% IACS.

6. The copper alloy wire according to any one of claims 1 to 5, wherein, The tensile strength of the copper alloy wire is above 400 MPa. The copper alloy wire has an elongation at break of 5% or more. The conductivity of the copper alloy wire is above 59% IACS.

7. A copper alloy stranded wire, wherein, The copper alloy stranded wire is formed by stranding multiple copper alloy wires as described in claim 6.

8. An electrical wire, wherein, The wire has a conductor and an insulating layer surrounding the conductor. The conductor is the copper alloy stranded wire as described in claim 7.

9. A method for manufacturing a copper alloy wire, wherein, The method for manufacturing the copper alloy wire includes: The process of making casting materials from copper alloys; The process of producing wire-drawn material by performing wire drawing processing on the casting material; and The process of heat-treating the drawn material, The copper alloy contains iron, phosphorus, tin, and secondary elements, with the balance consisting of copper and unavoidable impurities. The secondary element is selected from two or more elements in the group consisting of zinc, nickel, and chromium, or only zinc. The iron content is between 0.1% and 1.0% by mass. The phosphorus content is between 0.1% and 0.6% by mass. The tin content is between 0.1% and 0.4% by mass. When zinc is included, the zinc content is 0.005% by mass or more and 1.40% by mass or less. When nickel is included, the nickel content is 0.005% by mass or more and 0.70% by mass or less. When chromium is included, the chromium content is 0.005% by mass or more and 0.20% by mass or less. The combined content of iron, nickel, and chromium relative to the content of phosphorus is at a mass ratio of 3.0 or higher and 7.0 or lower.

10. The method for manufacturing copper alloy wire according to claim 9, wherein, In the heat treatment process of the drawing material, the drawing material is kept at a temperature of 300°C or higher and 700°C or lower for 4 hours or more and 40 hours or less.

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