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

Abstract

The copper alloy wire is formed from a copper alloy containing iron, phosphorus, tin, aluminum, and minor elements, with the remainder being copper and unavoidable impurities. The minor elements consist of two or more elements selected from the group of elements consisting of zinc, nickel, and chromium, or zinc alone. In mass%, the iron content is 0.1 to 1.0%, the phosphorus content is 0.1 to 0.6%, the tin content is 0.1 to 0.4%, and the aluminum content is 0.03 to 0.25%. In mass%, the zinc content is 0.005 to 1.40%, the nickel content is 0.005 to 0.70%, and the chromium content is 0.005 to 0.20%. The conductivity of the copper alloy wire is 50% IACS or higher, the tensile strength is 400 MPa or higher, and the elongation at break is 5% or higher. The product of the tensile strength and the elongation at break is 60 MPa or higher.

Description

Technical Field

[0001] The present disclosure relates to a copper alloy wire, a copper alloy stranded wire, an electric wire, and a method for manufacturing a copper alloy wire.

Background Art

[0002] Conventionally, copper alloy wires have been used for electric wires such as automotive wire harnesses. Copper alloy wires are required to have excellent conductivity and strength. This copper alloy wire is formed of, for example, a copper alloy to which iron, phosphorus, and tin are added. Patent Documents 1 to 3 disclose copper alloy wires formed of a copper alloy containing nickel in addition to iron, phosphorus, and tin.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

[0004] The copper alloy wire of the present disclosure is formed of a copper alloy, the copper alloy contains iron, phosphorus, tin, aluminum, and a sub-element, and the balance consists of copper and unavoidable impurities. The sub-element is two or more elements selected from the group consisting of zinc, nickel, and chromium, or only zinc. The content ratio of each element in the copper alloy wire of the present disclosure and the physical properties of the copper alloy wire of the present disclosure are as follows. The content ratio of iron is 0.1% by mass or more and 1.0% by mass or less. The content ratio of phosphorus is 0.1% by mass or more and 0.6% by mass or less. The content ratio of tin is 0.1% by mass or more and 0.4% by mass or less. The aluminum content is between 0.03% by mass and 0.25% by mass. If zinc is present, the zinc content is between 0.005% by mass and 1.40% by mass. If nickel is present, the nickel content is between 0.005% by mass and 0.70% by mass. If chromium is present, the chromium content is between 0.005% by mass and 0.20% by mass. The conductivity is 50% IACS or higher. The tensile strength is 400 MPa or more. The elongation at break is 5% or more. The product of the tensile strength and the elongation at break is 60 MPa or more. [Brief explanation of the drawing]

[0005] [Figure 1] Figure 1 is a schematic diagram showing an example of a copper alloy wire according to the embodiment. [Figure 2] Figure 2 is a schematic diagram showing an example of copper alloy stranded wire and electric wire according to the embodiment. [Figure 3] Figure 3 is a graph showing the relationship between the Al content and conductivity in the copper alloy wire shown in the test example. [Figure 4] Figure 4 is a graph showing the relationship between the Al content and tensile strength in the copper alloy wire shown in the test example. [Figure 5] Figure 5 is a graph showing the relationship between the Al content and the elongation at break in the copper alloy wire shown in the test example. [Figure 6] Figure 6 is a graph showing the relationship between the Al content ratio in the copper alloy wire shown in the test example and the product of tensile strength and elongation at break. [Modes for carrying out the invention]

[0006] From the perspective of the risk of depletion of metal resources, the manufacture of copper alloy wire using used wire harness scraps as raw materials is being considered. Wire harness scraps have attachments such as terminals attached to both ends of the wire. When wire harness scraps are mixed with raw materials, by-elements such as zinc, nickel, and chromium contained in the attachments become mixed into the copper alloy wire. If the copper alloy wire contains a certain amount of by-elements, it will affect the physical properties of the copper alloy wire, such as reducing its conductivity. Therefore, copper alloy wire containing by-elements may not meet the properties required for the copper alloy wire depending on its application.

[0007] One of the objectives of this disclosure is to provide a copper alloy wire with excellent conductivity and strength.

[0008] The inventors have discovered that by incorporating trace amounts of iron, phosphorus, tin, and aluminum into a copper alloy wire, a copper alloy wire with excellent conductivity and strength can be obtained, even if the copper alloy wire contains elements such as zinc, nickel, and chromium. Furthermore, the inventors have found that, in particular, if the aluminum content is within a predetermined range, a copper alloy wire with an excellent balance between tensile strength and elongation at break, which are indicators of strength, can be obtained. Generally, there is a trade-off relationship between tensile strength and elongation at break; for example, if the tensile strength is high, the elongation at break tends to be low. The inventors propose defining a multiplicative value of tensile strength and elongation at break as an indicator for evaluating the balance between tensile strength and elongation at break. Based on these findings, embodiments of this disclosure are listed and described below.

[0009] <1> The copper alloy wire of this disclosure is formed from a copper alloy, which contains iron, phosphorus, tin, aluminum, and minor elements, with the remainder being copper and unavoidable impurities. The minor elements are two or more elements selected from the group of elements consisting of zinc, nickel, and chromium, or zinc alone. The content ratio of each element in the copper alloy wire of this disclosure and the physical properties of the copper alloy wire of this disclosure are as follows. The iron content is between 0.1% by mass and 1.0% by mass. The phosphorus content is between 0.1% by mass and 0.6% by mass. The content ratio of tin is 0.1% by mass or more and 0.4% by mass or less. The content ratio of aluminum is 0.03% by mass or more and 0.25% by mass or less. When zinc is contained, the content ratio of zinc is 0.005% by mass or more and 1.40% by mass or less. When nickel is contained, the content ratio of nickel is 0.005% by mass or more and 0.70% by mass or less. When chromium is contained, the content ratio of chromium is 0.005% by mass or more and 0.20% by mass or less. The conductivity is 50% IACS or more. The tensile strength is 400 MPa or more. The elongation at break is 5% or more. The multiplication value of the tensile strength and the elongation at break is 60 MPa or more.

[0010] Here, the 'content ratio' in this specification is the mass ratio when the entire copper alloy is 100% by mass. Also, the above '%IACS' is the conductivity with the conductivity of international annealed copper standard being 100% IACS. The resistivity of international annealed copper standard is 1.7241×10 -8 Ω·m.

[0011] Generally, as the solid solution amount of the additive element increases, the strength of the copper alloy improves, but the conductivity decreases. The copper alloy wire of the present disclosure can have excellent conductivity, tensile strength, and elongation at break by including iron, phosphorus, tin, and aluminum in the copper alloy forming the copper alloy wire.

[0012] In the copper alloy wire of the present disclosure, iron, nickel, and chromium are likely to precipitate together with phosphorus. As a result, the amounts of elements such as iron, nickel, and chromium dissolved in copper decrease. Therefore, even if the copper alloy wire contains trace elements, the copper alloy wire of the present disclosure is excellent in conductivity.

[0013] In the copper alloy wire of the present disclosure, a trace amount of aluminum is contained, and as shown in the test examples described later, a copper alloy wire excellent in the balance between tensile strength and elongation at break can be obtained.

[0014] <2>In the copper alloy wire according to <1> above, the content ratio of aluminum may be 0.03% by mass or more and 0.10% by mass or less.

[0015] Generally, when aluminum is contained in a copper alloy wire, the conductivity of the copper alloy wire tends to decrease. If the content ratio of aluminum in the copper alloy wire is 0.03% by mass or more and 0.10% by mass or less, the conductivity of the copper alloy wire is unlikely to decrease.

[0016] <3>In the copper alloy wire according to <1> or <2> above, the multiplication value may be 62 MPa or more.

[0017] A copper alloy wire having a multiplication value of 62 MPa or more has both high tensile strength and elongation at break and can be used for various applications.

[0018] <4>In the copper alloy wire according to any one of <1> to <3> above, the total content ratio of zinc, nickel, and chromium may exceed 0.10% by mass.

[0019] A copper alloy wire produced using at least a part of wire harness scraps as raw materials tends to have a total content ratio of secondary elements exceeding 0.10% by mass. The copper alloy wire of the present disclosure has excellent conductivity and strength even when the content ratio of the secondary element rigidity exceeds 0.10% by mass.

[0020] <5>In the copper alloy wire according to any one of <1> to <4> above, the tensile strength may be 450 MPa or more.

[0021] The copper alloy wire of <5> above is excellent in tensile strength.

[0022] <6>In the copper alloy wire according to any one of <1> to <5> above, the elongation at break may be 10% or more.

[0023] the above <6> This copper alloy wire has excellent elongation at break.

[0024] <7> the above <1> from <6> In the copper alloy wire described in any of the above, the conductivity may be 60% IACS or higher.

[0025] the above <7> This copper alloy wire has excellent conductivity.

[0026] <8> The copper alloy stranded wire of this disclosure is as described above. <1> from <7> It is made by twisting together multiple copper alloy wires as described in any of the above.

[0027] The copper alloy stranded wire of this disclosure is formed from the copper alloy wire of this disclosure and therefore has excellent conductivity and strength.

[0028] <9> The electric wire of this disclosure comprises a conductor and an insulating layer covering the conductor. The conductor is as described above <8> This is the copper alloy stranded wire described in [reference].

[0029] The electric wire of this disclosure has excellent conductivity and strength because it comprises the copper alloy stranded wire of this disclosure.

[0030] <10> The method for manufacturing copper alloy wire according to this disclosure comprises a first step of producing a cast material formed from a copper alloy, a second step of producing a drawn wire by drawing the cast material, and a third step of producing a copper alloy wire by heat-treating the drawn wire. The copper alloy contains iron, phosphorus, tin, aluminum, and minor elements, with the remainder being copper and unavoidable impurities. The minor elements are two or more elements selected from the group of elements consisting of zinc, nickel, and chromium, or zinc alone. The content ratio of each element in the copper alloy is as follows. The iron content is between 0.1% by mass and 1.0% by mass. The phosphorus content is between 0.1% by mass and 0.6% by mass. The tin content is between 0.1% by mass and 0.4% by mass. The aluminum content is between 0.03% by mass and 0.25% by mass. If zinc is present, the zinc content is between 0.005% by mass and 1.40% by mass. If nickel is present, the nickel content is between 0.005% by mass and 0.70% by mass. If chromium is present, the chromium content is between 0.005% by mass and 0.20% by mass.

[0031] The method for manufacturing copper alloy wires according to this disclosure can produce copper alloy wires with excellent conductivity and strength.

[0032] <11> In the third step of the method for manufacturing copper alloy wire according to the present disclosure, the drawn wire material may be held at a temperature of 300°C to 700°C for 4 hours to 40 hours.

[0033] The heat treatment under the above conditions facilitates the deposition of iron, nickel, and chromium along with phosphorus. This deposition can increase the conductivity of the copper alloy wire. Furthermore, the heat treatment under the above conditions can soften the copper alloy wire. This softening can improve the elongation at break of the copper alloy wire.

[0034] Specific examples of copper alloy wires, copper alloy stranded wires, and electric wires of this disclosure are described below. In the figures, the same reference numerals indicate the same parts. In the drawings, some parts of the structure may be exaggerated or simplified for ease of explanation. The dimensional ratios of parts in the drawings may also differ from those of the actual parts. It should be noted that the present invention is not limited to these examples, but is indicated by the claims, and all modifications within the meaning and scope of equivalence to the claims are intended to be included. It should be understood that at least one structure or feature described in each embodiment and example can be combined with other embodiments and examples, or modified in various ways.

[0035] <Copper alloy wire> The copper alloy wire 1 in the embodiment shown in Figure 1 is formed from a copper alloy having a specific composition. The copper alloy contains specific additive elements within a specific range.

[0036] ≪Composition≫ Copper alloys have a composition consisting of iron (Fe), phosphorus (P), tin (Sn), aluminum (Al), and minor elements, with the remainder being copper (Cu) and unavoidable impurities. The minor elements are two or more elements selected from the group consisting of zinc (Zn), nickel (Ni), and chromium (Cr), or Zn alone. Of the elements listed above in copper alloys, Fe, P, Sn, and Al are essential elements. The effects and proportions of each element in copper alloys are explained below.

[0037] Fe strengthens copper alloys by forming compounds with P and precipitating them. The Fe content is between 0.1% by mass and 1.0% by mass. A Fe content of 0.1% by mass or more forms a compound containing Fe and P. The deposition of this compound on Cu improves the strength of the copper alloy. Furthermore, the deposition of the above compound reduces the amount of Fe and P dissolved in Cu, thereby mitigating the decrease in the electrical conductivity of the copper alloy. Therefore, copper alloy wire 1 possesses excellent electrical conductivity and strength.

[0038] By having an Fe content of 1.0 mass% or less, the decrease in conductivity of the copper alloy is reduced, and the coarsening of the above-mentioned compounds is less likely to occur. As a result, the copper alloy has a structure in which the above-mentioned compounds are finely dispersed. Therefore, copper alloy wire 1 has excellent elongation. In addition, since wire breakage caused by coarse compounds is less likely to occur during the manufacturing process of copper alloy wire 1, copper alloy wire 1 also has excellent manufacturability. The Fe content may be 0.11 mass% to 0.9 mass%, or 0.12 mass% to 0.8 mass%.

[0039] P strengthens copper alloys by forming compounds and precipitating with elements such as Fe, Ni, and Cr. The P content is between 0.1% by mass and 0.6% by mass. A P content of 0.1% by mass or more allows for the formation of P-containing compounds through reaction with elements such as Fe. The deposition of these compounds on Cu results in the aforementioned improvements in the strength of the copper alloy and a reduction in the decrease in its electrical conductivity. Therefore, copper alloy wire 1 possesses excellent electrical conductivity and strength. Furthermore, a portion of the P acts as a deoxidizing agent, and its inclusion as phosphorus oxide in the copper alloy is permitted.

[0040] By limiting the P content to 0.6% by mass or less, the decrease in the conductivity of the copper alloy is reduced, and the coarsening of the above-mentioned compound is less likely to occur. As a result, the copper alloy has a structure in which the above-mentioned compound is finely dispersed. Furthermore, wire breakage caused by coarse compounds is less likely to occur during the manufacturing process of copper alloy wire 1. The P content may also be 0.11% by mass or more and 0.5% by mass or 0.12% by mass or more and 0.4% by mass or less.

[0041] Sn strengthens copper alloys by forming a solid solution. The Sn content is 0.1% by mass or more and 0.4% by mass or less. A Sn content of 0.1% by mass or more provides the strength-enhancing effect of Sn. A Sn content of 0.4% by mass or less reduces the decrease in conductivity caused by Sn solid solution in Cu. Therefore, copper alloy wire 1 has excellent conductivity and strength. Excessive solid solution of Sn in Cu reduces the workability of the copper alloy. A Sn content of 0.4% by mass or less makes it easier to obtain copper alloy wire 1 with excellent elongation, and also facilitates wire drawing during the manufacturing process. Therefore, copper alloy wire 1 also has excellent manufacturability. The Sn content may also 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.

[0042] Al, when present in trace amounts in copper alloys, improves both the tensile strength and elongation at break of the copper alloy. The Al content is between 0.03% by mass and 0.25% by mass. An Al content of 0.03% by mass or more improves the tensile strength and elongation at break of the copper alloy. An Al content of 0.25% by mass or less prevents a decrease in the conductivity of the copper alloy wire. Furthermore, an Al content of 0.25% by mass or less makes it easier to maintain both the tensile strength and elongation at break of the copper alloy at a high level. The lower limit of the Al content may be 0.04% by mass. The upper limit of the Al content may be 0.22% by mass, 0.13% by mass, or 0.09% by mass. The range of the Al content may be, for example, 0.04% by mass or more and 0.22% by mass, 0.03% by mass or more and 0.10% by mass, or 0.04% by mass or more and 0.09% by mass.

[0043] Copper alloys contain minor elements in addition to Fe, P, Sn, and Al. These minor elements consist of two or more elements selected from the group of elements comprising Zn, Ni, and Cr, or Zn alone. The combinations of minor elements are Zn, Ni, and Cr; Zn and Ni; Zn and Cr; Ni and Cr; or Zn alone. The respective content percentages of Zn, Ni, and Cr are shown below.

[0044] Zn is mainly in a solid solution state in Cu. When copper alloys contain Zn, the Zn content is between 0.005 mass% and 1.40 mass%. By keeping the Zn content below 1.40 mass%, the decrease in conductivity due to Zn solid solution in Cu can be mitigated. When Ni and Cr are included, Zn does not need to be included. That is, the Zn content may be zero. If the Zn content is less than 0.005 mass%, the effect of Zn on the properties is considered to be almost negligible. When the Zn content is less than 0.005 mass%, Zn is considered an unavoidable impurity. The Zn content may also be 0.01 mass% or more, or 0.02 mass% or more. The Zn content may also be between 0.05 mass% and 1.35 mass%, or between 0.10 mass% and 1.30 mass%. The Zn content may be further reduced to 0.40% by mass or less, 0.35% by mass or less, or 0.30% by mass or less.

[0045] Ni primarily exists as a compound with P, precipitated on Cu. When copper alloys contain Ni, the Ni content is between 0.005% by mass and 0.70% by mass. A Ni content of 0.70% by mass or less mitigates the decrease in conductivity caused by Ni. Furthermore, the precipitation of compounds containing Ni and P reduces the amount of Ni and P dissolved in Cu, thus mitigating the decrease in conductivity. When Zn and Cr are present, or when only Zn is present, Ni is not required. In other words, the Ni content may be zero. If the Ni content is less than 0.005% by mass, the effect of Ni on the properties is considered to be negligible. When the Ni content is less than 0.005% by mass, Ni is considered an unavoidable impurity. The Ni content may also be 0.01% by mass or more, or 0.02% by mass or more. The Ni content may 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.

[0046] Cr primarily precipitates on Cu by forming intermetallic compounds containing Cr or by forming compounds with P. When copper alloys contain Cr, the Cr content is between 0.005% by mass and 0.20% by mass. A Cr content of 0.20% by mass or less can mitigate the decrease in conductivity caused by Cr. Furthermore, the precipitation of compounds containing Cr and P reduces the amount of Cr and P dissolved in Cu, thus mitigating the decrease in conductivity. When Zn and Ni are present, or when only Zn is present, Cr may not be present. That is, the Cr content may be zero. If the Cr content is less than 0.005% by mass, the effect of Cr on the properties is considered to be negligible. When the Cr content is less than 0.005% by mass, Cr is considered an unavoidable impurity. The Cr content may be between 0.01% by mass and 0.18% by mass. The Cr content may be further reduced to 0.16% by mass or less, 0.10% by mass or less, or 0.08% by mass or less.

[0047] Considering the role of P in the copper alloy described above, the mass ratio X of the total content of Fe, Ni, and Cr to the content of P, i.e., (Fe+Ni+Cr) / P, is, for example, between 3.0 and 7.0. When the above mass ratio X is within the above range, Fe, Ni, and Cr tend to precipitate together with P. As a result of reducing the amount of these elements dissolved in Cu, the strength of the copper alloy is improved and the decrease in the conductivity of the copper alloy is mitigated. Therefore, copper alloy wire 1 has excellent conductivity and strength. The above mass ratio X may also be between 3.2 and 6.9, or between 3.5 and 6.8.

[0048] Copper alloy wire 1 has excellent conductivity and strength due to the presence of Fe, P, Sn, and Al. However, if a sub-element selected from Zn, Ni, and Cr is added in addition to the basic composition containing only Fe, P, Sn, and Al, the conductivity decreases. If the mass ratio X is between 3.0 and 7.0, Fe, Ni, and Cr precipitate sufficiently together with P. Therefore, if the mass ratio X satisfies the condition of being between 3.0 and 7.0, a copper alloy with excellent conductivity and strength can be obtained even if a sub-element is included in the copper alloy.

[0049] The total content of additive elements in the copper alloy, that is, the total content of Fe, P, Sn, Al, and minor elements, is, for example, 1.00 mass% or more and 3.00 mass% or less. The total content of additive elements may also be 1.04 mass% or more and 2.90 mass% or less, 1.14 mass% or more and 2.80 mass% or less, or 1.20 mass% or more and 2.70 mass% or less. Furthermore, the total content of additive elements may be 2.50 mass% or less, 2.40 mass% or less, 2.30 mass% or less, or 2.20 mass% or less.

[0050] The content of minor elements, i.e., the total content of Zn, Ni, and Cr, is, for example, greater than 0.10 mass%. The upper limit of the content of minor elements is, for example, 1.70 mass%. The content of minor elements may be 0.20 mass% or more, or 0.30 mass% or more. The content of minor elements may be greater than 0.10 mass% and 1.70 mass% or less, greater than 0.10 mass% and 1.60 mass% or less, 0.15 mass% or more and 1.50 mass% or less, or 0.20 mass% or more and 1.40 mass% or less. The content of minor elements may be further 1.10 mass% or less, 1.00 mass% or less, or 0.90 mass% or less.

[0051] The composition of copper alloy wire 1, i.e., the composition of the copper alloy, can be determined by known analytical methods. These analytical methods include, for example, inductively coupled plasma (ICP) emission spectroscopy or X-ray fluorescence spectroscopy.

[0052] ≪Shape≫ The cross-sectional shape of the copper alloy wire 1 may be any shape. The copper alloy wire 1 shown in Figure 1 is a round wire with a circular cross-section. The cross-section of the copper alloy wire 1 is a cross-section perpendicular to the length of the copper alloy wire 1. The cross-sectional shape of the copper alloy wire 1 may also be non-circular. Non-circular shapes include, for example, polygons and ovals. Polygons include, for example, quadrilaterals and hexagons. Quadrilaterals include rectangles and squares. Oval shapes include ellipses.

[0053] Linear The diameter D of the copper alloy wire 1 is, for example, 0.025 mm or more and 0.5 mm or less. If the cross-sectional shape of the copper alloy wire 1 is circular, the diameter D is equal to the diameter of the cross-section. If the cross-sectional shape of the copper alloy wire 1 is not circular, the diameter D is considered to be the diameter of a circle having an area equal to the area of ​​the cross-section. The smaller the diameter D, the thinner and lighter the copper alloy wire 1 is. The diameter D of the copper alloy wire 1 may also be 0.05 mm or more and 0.3 mm or less, or 0.1 mm or more and 0.3 mm or less.

[0054] ≪Characteristics≫ The copper alloy wire 1 has the following characteristics: • Conductivity is 50% IACS or higher. • The tensile strength is 400 MPa or higher. • The elongation at break is 5% or more. • The product of tensile strength and elongation at break is 60 MPa or higher. Copper alloy wire 1, which satisfies all four of the above characteristics, has an excellent balance of conductivity, tensile strength, and elongation at break.

[0055] A copper alloy wire 1 with an conductivity of 50% IACS or higher has excellent conductivity. The conductivity may also be 53% IACS or higher, 56% IACS or higher, 60% IACS or higher, or 62% IACS or higher. Conductivity can be measured by the four-terminal method. Specifically, conductivity is calculated by measuring the resistance of a copper alloy wire 1 with a length of 1 m.

[0056] A copper alloy wire 1 with a tensile strength of 400 MPa or more has excellent strength. The tensile strength may be 420 MPa or more, 450 MPa or more, 480 MPa or more, or 500 MPa or more. On the other hand, a copper alloy wire 1 with an elongation at break of 5% or more has excellent elongation. The elongation at break may be 7% or more, 10% or more, 12% or more, or 18% or more.

[0057] Tensile strength and elongation at break can be measured by tensile testing. Tensile testing shall be performed in accordance with "JIS Z 2241:2011 Method for tensile testing of metallic materials".

[0058] Tensile strength and elongation at break have a trade-off relationship. For example, as tensile strength increases, elongation at break tends to decrease. Conversely, as elongation at break increases, tensile strength tends to decrease. In this example, a multiplicative value of tensile strength and elongation at break is defined as an index for evaluating the balance between tensile strength and elongation at break. For example, if the tensile strength is 400 MPa and the elongation at break is 10%, the multiplicative value is 40 MPa.

[0059] In this example, the multiplication value for copper alloy wire 1 is 60 MPa or higher. Copper alloy wire 1 with a multiplication value of 60 MPa or higher has an excellent balance between tensile strength and elongation at break, and can be said to possess strength suitable for various applications. The multiplication value may be, for example, 62 MPa or higher, 64 MPa or higher, 66 MPa or higher, 70 MPa or higher, or 74 MPa or higher. The multiplication value increases as the tensile strength or elongation at break increases. As mentioned above, there is a trade-off relationship between tensile strength and elongation at break, so for example, if the elongation at break becomes too large, the tensile strength may fall below the lower limit of 400 MPa. Therefore, a higher multiplication value does not necessarily mean that copper alloy wire 1 is superior. Due to the constraints of the lower limit of tensile strength or the lower limit of elongation at break, there is an upper limit to the multiplication value. The upper limit of the multiplication value is, for example, around 76 MPa.

[0060] <Copper alloy stranded wire> The copper alloy stranded wire 2 shown in Figure 2 is a stranded wire using the aforementioned copper alloy wire 1 as the core wire, and is formed by twisting together multiple copper alloy wires 1. The copper alloy stranded wire 2 can withstand a larger 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 and twist, and has excellent flexibility and torsional properties. Figure 2 illustrates a copper alloy stranded wire 2 in which seven copper alloy wires 1 are concentrically twisted. The number of strands and the twisting method of the copper alloy wires 1 can be changed as appropriate.

[0061] The copper alloy stranded wire 2 may also be a compressed stranded wire (not shown) that has been compressed and then twisted together. The compressed stranded wire has a smaller outer diameter than a simply twisted stranded wire.

[0062] <Electric wire> The electric wire 3 shown in Figure 2 comprises a conductor 31 and an insulating layer 32 covering the conductor 31. The conductor 31 is the copper alloy stranded wire 2 described above. The insulating layer 32 is formed of a known insulating material. The insulating material is a resin such as polyvinyl chloride (PVC) or polypropylene (PP).

[0063] The electric wire 3 may be a terminal-equipped electric wire having a terminal (not shown) attached to the end of the conductor 31. The terminal is, for example, a crimp terminal. The crimp terminal is attached to the end of the conductor 31 that is exposed after the insulating layer 32 has been removed.

[0064] <Manufacturing method for copper alloy wire> The copper alloy wire 1 of the embodiment can be manufactured by the method for manufacturing the copper alloy wire of the embodiment. The method for manufacturing the copper alloy wire of the embodiment comprises, in order, a first step, a second step, and a third step. Each step is as follows:

[0065] The first step is the process of producing a cast material made of a copper alloy. The second step is to draw the cast material to produce drawn wire. The third step is to heat-treat the drawn wire.

[0066] ≪1st process≫ The cast material is produced by casting molten copper alloy having the above-described composition, which includes Fe, P, Sn, and Al, along with sub-elements. Used wire harness scraps can be used as raw materials for the cast material. In addition to Fe, P, Sn, and Al, wire harness scraps contain one or more sub-elements selected from Zn, Ni, and Cr. Cu-Fe alloy, Cu-P alloy, Sn, and Al may be mixed into the raw materials to adjust the composition of the copper alloy to fall within the above-described range.

[0067] Casting materials can be produced by known casting methods. Examples of casting methods include the belt-and-wheel method, the double-belt method, and the upcast method. The casting material is, for example, a round wire with a circular cross-section. The wire diameter of the casting material is, for example, between 5 mm and 40 mm. The wire diameter of the casting material is the diameter of a circle having the same area as the cross-sectional area of ​​the casting material.

[0068] ≪Second process≫ By drawing a cast material, a drawn wire with a predetermined wire diameter is produced. The drawing process is performed cold. The drawing process may be repeated until the drawn wire reaches the predetermined wire diameter. The wire diameters of the drawn wire are, for example, 0.025 mm to 0.5 mm, 0.05 mm to 0.35 mm, and 0.1 mm to 0.3 mm.

[0069] Intermediate heat treatment may be performed during the wire drawing process. Intermediate heat treatment is a heat treatment that improves workability by removing processing distortion. The temperature for intermediate heat treatment is, for example, 350°C to 1000°C, 380°C to 950°C, or 400°C to 900°C. The duration of intermediate heat treatment is, 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 the material is held at the above temperature. Intermediate heat treatment may be performed two or more times.

[0070] ≪3rd process≫ Copper alloy wire 1 is manufactured by heat treatment of drawn wire. This heat treatment precipitates elements such as Fe, P, Ni, and Cr that are dissolved in the copper alloy, and also softens the drawn wire that has been work-hardened by the wire drawing process. Hereinafter, this heat treatment will be referred to as aging treatment. The temperature of the aging treatment is, for example, 300°C to 700°C, or 350°C to 650°C. The temperature of the aging treatment may also be 400°C or higher, or 420°C or higher. The duration of the aging treatment is, for example, 4 hours to 40 hours, 5 hours to 20 hours, or 6 hours to 10 hours. The duration of the aging treatment refers to the time during which the material is held at the above temperatures.

[0071] The aging process causes the above elements to precipitate, improving the strength of the copper alloy wire and reducing the decrease in its conductivity. Furthermore, the aging process softens the copper alloy wire, improving its elongation. The diameter of the copper alloy wire is equal to the diameter of the drawn wire.

[0072] <Example Test> Copper alloy wire samples having the compositions shown in Table 1 were prepared. The compositions of samples No. 1 to No. 10 are within the range of compositions in this embodiment. Copper alloy wires No. 1 to No. 6 contain Fe, P, Sn, and Al as essential elements, and Zn, Ni, and Cr as minor elements. Copper alloy wires No. 7 and No. 8 contain Zn and Ni as minor elements. Copper alloy wire No. 9 contains only Zn as a minor element. Copper alloy wire No. 10 contains Zn and Cr as minor elements.

[0073] The compositions of samples No. 101 to No. 111 are within the range of the composition in this embodiment, except for Al. Specifically, the Al content in samples No. 101 to No. 106 is greater than 0.25% by mass, and the Al content in samples No. 107 to No. 111 is less than 0.03% by mass.

[0074] In Table 1, the column 'Zn+Ni+Cr' shows the content ratio of the secondary elements, i.e., the total content ratio of Zn, Ni, and Cr, expressed to two decimal places. The column '(Fe+Ni+Cr) / P' shows the mass ratio X of the total content ratio of Fe, Ni, and Cr to the content ratio of P.

[0075] Cast copper alloys having the compositions shown in Table 1 were prepared. Each cast material was a rod-shaped body with a circular cross-section. The diameter of each rod-shaped body was 30 mm. In the test example, the cast material was drawn to produce a drawn wire with a diameter of 0.18 mm. Finally, the prepared drawn wire was subjected to aging treatment to produce copper alloy wire. The aging treatment conditions were either 450°C for 8 hours or 500°C for 8 hours, as shown in Table 2.

[0076] ≪Composition analysis≫ The composition of the copper alloy wires of each manufactured sample was investigated by ICP emission spectrometry. The results show the composition of the copper alloy wires of each sample as shown in Table 1.

[0077] ≪Characteristics≫ The conductivity, tensile strength, and elongation at break of each copper alloy wire sample were measured. The results for these properties are shown in Table 2. The measurement methods for these properties are as described above. Each property was measured at room temperature. Furthermore, the product of tensile strength and elongation at break was calculated. The results for this product are also shown in Table 2.

[0078] [Table 1]

[0079] [Table 2]

[0080] As shown in Table 2, copper alloy wires No. 1 to No. 10, with an Al content of 0.03 mass% to 0.25 mass%, exhibited conductivity of 50% IACS or higher, tensile strength of 400 MPa or higher, elongation at break of 5% or higher, and a multiplicative value of 60 MPa or higher. These results indicate that copper alloy wires No. 1 to No. 10 possess excellent conductivity and a good balance between tensile strength and elongation at break. A comparison of samples No. 1 to No. 6, which have nearly the same content of the minor elements Zn, Ni, and Cr, and a comparison of samples No. 7 and No. 8, which have the same Zn and Ni content but no Cr, revealed that copper alloy wires with particularly excellent properties can be obtained when the Al content is between 0.03 mass% and 0.10 mass%. Specifically, the copper alloy wires of Sample No. 4, Sample No. 5, Sample No. 6, and Sample No. 7, which had an Al content of 0.03% by mass or more and 0.10% by mass or less, had an electrical conductivity of 60% IACS or higher and a multiplicative value of 64 MPa or higher.

[0081] The copper alloy wires from samples No. 101 to No. 106, which have an Al content of more than 0.25 mass%, do not meet the specified properties of the embodiment in terms of conductivity, tensile strength, and multiplicative value. By comparing the measurement results of the properties of samples No. 101 to No. 106, it was found that as the Al content increases, the multiplicative value tends to increase, while the conductivity tends to decrease.

[0082] Copper alloy wires No. 107 to No. 111, which have an Al content of less than 0.03 mass%, exhibit excellent conductivity, but their multiplicative values ​​do not meet the requirements of the embodiment. The applications of such copper alloy wires are limited. Caution is required when using such copper alloy wires, for example, as copper alloy wires for wire harnesses that are easily pulled during use.

[0083] Next, to clarify the effect of the Al content on the properties of copper alloy wire, the measurement results of the properties of the test examples are shown graphically in Figures 3 to 6. The horizontal axis in Figures 3 to 6 represents the Al content. The vertical axis in Figure 3 represents conductivity, the vertical axis in Figure 4 represents tensile strength, and the vertical axis in Figure 5 represents elongation at break. The vertical axis in Figure 6 is the product of tensile strength and elongation at break.

[0084] Regarding the conductivity of copper alloy wires, as shown in Figure 3, it can be observed that the conductivity of the copper alloy wire tends to decrease as the Al content in the copper alloy wire increases.

[0085] Regarding the tensile strength of copper alloy wire, as shown in Figure 4, a tendency for the tensile strength to be higher can be observed when the Al content is in the range of 0.03% to 0.25% by mass. In particular, a more pronounced tendency for the tensile strength to be higher can be observed when the Al content is in the range of 0.03% to 0.10% by mass.

[0086] Regarding the elongation at break of copper alloy wire, as shown in Figure 5, a tendency for the elongation at break to be higher can be observed when the Al content is in the range of 0.03 mass% to 0.25 mass%.

[0087] As shown in Figures 4 and 5, when the Al content is in the range of 0.03 mass% to 0.25 mass%, both the tensile strength and the elongation at break tend to be high. Therefore, as shown in Figure 6, within that range of Al content, the product of the tensile strength and the elongation at break also tends to be high.

[0088] As explained above, it has become clear that by adding a minute amount of Al to copper alloy wire, the decrease in conductivity of the copper alloy wire is reduced while maintaining both high tensile strength and elongation at break. [Explanation of symbols]

[0089] 1. Copper alloy wire 2 Copper alloy stranded wire 3 electric wire 31 Conductor 32 Insulating layer D wire diameter

Claims

1. It is made of a copper alloy, The aforementioned copper alloy contains iron, phosphorus, tin, aluminum, and minor elements, with the remainder being copper and unavoidable impurities. The aforementioned sub-elements are two or more elements selected from the group of elements consisting of zinc, nickel, and chromium, or zinc alone. The iron content is between 0.1% by mass and 1.0% by mass. 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. The aluminum content is between 0.03% by mass and 0.25% by mass. If zinc is included, the zinc content is between 0.005% by mass and 1.40% by mass. If nickel is included, the nickel content is 0.005% by mass or more and 0.70% by mass or less. If chromium is present, the chromium content is between 0.005% by mass and 0.20% by mass. The conductivity is 50% IACS or higher. The tensile strength is 400 MPa or more. The elongation at break is 5% or more. The product of the tensile strength and the elongation at break is 60 MPa or more. Copper alloy wire.

2. The copper alloy wire according to claim 1, wherein the aluminum content is 0.03% by mass or more and 0.10% by mass or less.

3. The copper alloy wire according to claim 1 or claim 2, wherein the multiplication value is 62 MPa or more.

4. The copper alloy wire according to claim 1 or claim 2, wherein the total content of zinc, nickel, and chromium is greater than 0.10% by mass.

5. The copper alloy wire according to claim 1 or claim 2, wherein the tensile strength is 450 MPa or more.

6. The copper alloy wire according to claim 1 or claim 2, wherein the elongation at break is 10% or more.

7. The copper alloy wire according to claim 1 or claim 2, wherein the conductivity is 60% IACS or higher.

8. A plurality of copper alloy wires according to claim 1 or claim 2 are twisted together, Copper alloy stranded wire.

9. It comprises a conductor and an insulating layer covering the conductor, The conductor is the copper alloy stranded wire described in claim 8. Electric wire.

10. The first step is to produce a cast material made of a copper alloy, A second step involves drawing the aforementioned cast material to produce a drawn wire, The process includes a third step of heat-treating the drawn wire material to produce a copper alloy wire, The aforementioned copper alloy contains iron, phosphorus, tin, aluminum, and minor elements, with the remainder being copper and unavoidable impurities. The aforementioned sub-elements are two or more elements selected from the group of elements consisting of zinc, nickel, and chromium, or zinc alone. The iron content is between 0.1% by mass and 1.0% by mass. 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. The aluminum content is between 0.03% by mass and 0.25% by mass. If zinc is included, the zinc content is between 0.005% by mass and 1.40% by mass. If nickel is included, the nickel content is 0.005% by mass or more and 0.70% by mass or less. If chromium is present, the chromium content is between 0.005% by mass and 0.20% by mass. The copper alloy wire has an electrical conductivity of 50% IACS or higher, a tensile strength of 400 MPa or higher, and an elongation at break of 5% or higher. The product of the tensile strength and the elongation at break is 60 MPa or more. A method for manufacturing copper alloy wire.

11. The method for manufacturing a copper alloy wire according to claim 10, wherein in the third step, the drawn wire is held at a temperature of 300°C to 700°C for 4 hours to 40 hours.

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