Aluminum alloy wire, electrical wire, and wire harness

Abstract

Provided are: an aluminum alloy wire which has high tensile strength, high electrical conductivity, and excellent elongation properties and hence has an excellent balance among these properties and which has low unevenness in tensile strength and elongation property along the longitudinal direction; and an electrical wire and a wire harness. The aluminum alloy wire has an alloy composition containing 0.30-0.70 mass% Mg and 0.30-1.00 mass% Si, the remainder consisting of Al and unavoidable impurities. In crystal orientation analysis by an electron backscatter diffraction (EBSD) method performed in a observed area in a cross-section perpendicular to the longitudinal direction, the presence proportion of measurement points having differences in crystal orientation between each pair of adjacent measurement points of 5° or less, with respect to all the measurement points, is 85% or less.

Description

Aluminum alloy wire rods, electric wires and wiring harnesses

[0001] The present invention relates to an aluminum alloy wire rod, an electric wire, and a wiring harness.

[0002] In recent years, the use of wire harnesses to transmit electrical signals has increased in line with the increasing use of electrical equipment in automobiles. As a result, the weight of the electrical wires that make up the wire harnesses has increased, posing a problem of the total weight of wire harnesses per automobile reaching several tens of kilograms.

[0003] In order to reduce the weight of wiring harnesses, efforts have been made to reduce the diameter of the wires, but the effect of reducing the weight of the wiring harness has been insufficient.On the other hand, as one way to reduce the weight of wiring harnesses, the replacement of copper wires with aluminum wires has been progressing, mainly for large diameter wires, and in recent years in particular, there has been a growing trend to replace copper wires with high-strength aluminum alloy wires even for small diameter wires.

[0004] As a material for such high strength aluminum alloy wire, 6000 series aluminum alloys are often selected.

[0005] For example, Patent Document 1 describes an aluminum alloy wire used as a conductor, which contains, by mass%, 0.2% to 1.5% Mg, 0.1% to 2.0% Si, 0.1% to 1.0% Fe, or a total of 0.1% to 1.0% Fe and at least one element selected from Cu, Cr, Mn, and Zr, 0.08% or less Ti, and 0.016% or less B, with the balance being Al and impurities, and which has a conductivity of 40% IACS or more, a tensile strength of 150 MPa or more, an elongation of 5% or more, a wire diameter of 0.5 mm or less, and a maximum crystal grain size of 50 μm or less.

[0006] Patent Document 2 also describes a wire rod containing 0.01 to 0.4 mass% of Fe, 0.01 mass% or more but less than 0.3 mass% of Mg, 0.01 mass% or more but less than 0.3 mass% of Si, 0.01 mass% or more but less than 0.3 mass% of Cu, and the balance consisting of Al and unavoidable impurities, which is tilted at an angle of 25° or more with respect to the normal direction from the (111) plane located parallel to the cross section perpendicular to the wiredrawing direction of the wire rod, within the range of a standard triangle in a stereographic projection. The area ratio of crystal grains having a plane tilted at an angle of 0° or more and less than 25° from the (111) plane parallel to a cross section perpendicular to the wire-drawing direction of the wire is 50% or more within a circle of radius (3 / 10)R from the center of the wire, where R is the radius of the wire, and the area ratio of crystal grains having a plane tilted at an angle of 0° or more and less than 25° from the normal direction to the (111) plane parallel to the cross section perpendicular to the wire-drawing direction of the wire is 50% or more within a range of the entire wire excluding the area within a circle of radius (7 / 10)R from the center of the wire.

[0007] Furthermore, in Patent Document 3, Mg: 0.1 to 1.0 mass%, Si: 0.1 to 1.0 mass%, Fe: 0.01 to 1.40 mass%, Ti: 0.000 to 0.100 mass%, B: 0.000 to 0.030 mass%, Cu: 0.00 to 1.00 mass%, Ag: 0 .00 to 0.50 mass%, Au: 0.00 to 0.50 mass%, Mn: 0.00 to 1.00 mass%, Cr: 0.00 to 1.00 mass%, Zr: 0.00 to 0.50 mass%, Hf: 0.00 to 0.50 mass%, V: 0.00 to 0.50 mass%, Sc: The aluminum alloy wire rod has a composition containing 0.00 to 0.50 mass% of Sn, 0.00 to 0.50 mass% of Sn, 0.00 to 0.50 mass% of Co, and 0.01 to 0.50 mass% of Ni, with the total content of Fe, Ti, B, Cu, Ag, Au, Mn, Cr, Zr, Hf, V, Sc, Sn, Co, and Ni being 2.00 mass% or less, and the balance being Al and unavoidable impurities, and the area ratio of the region where the angle between the longitudinal direction and the <111> direction of the crystal is 20° or less is 20% or more and 65% or less.

[0008] Patent No. 5155464 Patent No. 5846360 Patent No. 6499190

[0009] Patent Document 1 describes an aluminum electric wire in which Mg, Si, etc. are added to an aluminum alloy and the maximum crystal grain size is controlled. In Patent Documents 2 and 3, the crystal plane and crystal direction of the aluminum alloy wire are structurally controlled, and the wire has characteristics such as high tensile strength and electrical conductivity, excellent elongation, as well as fracture resistance against repeated movement, high yield strength, and excellent elongation.

[0010] These alloys share at least the common feature of having high tensile strength and high electrical conductivity while also having excellent elongation properties, but there is room for further improvement in terms of reducing the variation in tensile strength and elongation properties along the length.

[0011] An object of the present invention is to provide an aluminum alloy wire rod, an electric wire, and a wiring harness that have high tensile strength and high electrical conductivity while also having excellent elongation properties, thereby achieving an excellent balance of these properties and exhibiting small variations in tensile strength and elongation properties along the length.

[0012] As a result of intensive research and development into the above-mentioned conventional problems, the present inventors have found that it is possible to provide an aluminum alloy wire, electric wire, and wiring harness with improved tensile strength, electrical conductivity, and elongation in a balanced manner by controlling the composition of the aluminum alloy wire within a specified range and further controlling the temperature and time in the heat treatment step when manufacturing the aluminum alloy wire, thereby controlling the crystal orientation difference between adjacent measurement points when performing crystal orientation analysis. The present invention was completed based on this finding.

[0013] In order to achieve the above object, the present invention provides the following essential configuration: (1) An aluminum alloy wire having an alloy composition containing 0.30% by mass or more and 0.70% by mass or less of Mg and 0.30% by mass or more and 1.00% by mass or less of Si, with the balance being Al and unavoidable impurities, wherein, in a crystal orientation analysis performed by electron backscatter diffraction (EBSD) on an observation region of a cross section perpendicular to the longitudinal direction of the aluminum alloy wire, the proportion of measurement points having a crystal orientation difference of 5° or less with adjacent measurement points is 85% or less. (2) An aluminum alloy wire having an alloy composition containing 0.30% by mass or more and 0.70% by mass or less of Mg and 0.30% by mass or more and 1.00% by mass or less of Si, and further containing one or more components selected from the group consisting of Mn, Fe, Ni, Ti, Cr, and Zr in a total amount of 0.001% by mass or more and 0.55% by mass or less, with the remainder being Al and unavoidable impurities, wherein, in a crystal orientation analysis by electron backscatter diffraction (EBSD) method performed on an observation region of a cross section perpendicular to the longitudinal direction of the aluminum alloy wire, the proportion of measurement points having a crystal orientation difference of 5° or less with respect to adjacent measurement points is 85% or less out of all measurement points. (3) The aluminum alloy wire according to (1) or (2) above, wherein, in the crystal orientation analysis performed in the observation area, when crystal orientations within ±5° of the <100> orientation are defined as a <100> orientation group, crystal orientations within ±5° of the <110> orientation are defined as a <110> orientation group, and crystal orientations within ±5° of the <111> orientation are defined as a <111> orientation group, the ratio of the number of crystal grains having the <111> orientation group to the total number of crystal grains having the <100> orientation group and the <110> orientation group (<111> orientation group / (<100> orientation group + <110> orientation group)) is in the range of 5 to 30. (4) The aluminum alloy wire according to any one of (1) to (3) above, wherein the average crystal grain size of the crystal grains obtained from the crystal orientation analysis performed in the observation area is in the range of 5 μm to 9 μm. (5) An electric wire having the aluminum alloy wire material according to any one of (1) to (4) above. (6) A wire harness having the electric wire according to (5) above.

[0014] According to the present invention, it is possible to provide an aluminum alloy wire rod, an electric wire, and a wiring harness that have high tensile strength and high electrical conductivity while also having excellent elongation properties, thereby having an excellent balance of these properties and having small variations in tensile strength and elongation properties along the length.

[0015] Hereinafter, preferred embodiments of the aluminum alloy wire rod, electric wire, and wiring harness of the present invention will be described in detail. In the component composition of the alloy of the present invention, "mass %" may be simply represented as "%."

[0016] The aluminum alloy wire of the present invention has an alloy composition containing 0.30% by mass or more and 0.70% by mass or less of Mg and 0.30% by mass or more and 1.00% by mass or less of Si, with the remainder being Al and unavoidable impurities, and in a crystal orientation analysis by electron backscatter diffraction (EBSD) method performed on an observation region of a cross section perpendicular to the longitudinal direction, the proportion of measurement points having a crystal orientation difference of 5° or less with respect to adjacent measurement points is 85% or less out of all measurement points.

[0017] In the aluminum alloy wire according to the present invention, the alloy composition is set within a specified range, and the temperature and time of the heat treatment process during production of the aluminum alloy wire are controlled to control the crystal orientation difference between adjacent measurement points, thereby enabling balanced improvements in tensile strength, electrical conductivity, and elongation. More specifically, the tensile strength of the aluminum alloy wire can be improved by having an alloy composition containing 0.30 mass% or more of Mg and 0.30 mass% or more of Si, and the proportion of measurement points with a crystal orientation difference between adjacent measurement points of 5° or less is 85% or less of all measurement points. On the other hand, the electrical conductivity and elongation of the aluminum alloy wire can be improved by having an alloy composition with an Mg content of 0.70 mass% or less and an Si content of 1.00 mass% or less, and the proportion of measurement points with a crystal orientation difference between adjacent measurement points of 5° or less is 85% or less of all measurement points.

[0018] Therefore, the aluminum alloy wire of the present invention can provide an aluminum alloy wire, an electric wire, and a wiring harness that have high tensile strength and high electrical conductivity while also having excellent elongation properties, and that are well-balanced among these properties and have small variations in tensile strength and elongation properties along the length.

[0019] [1] Alloy composition of aluminum alloy wire rod <Essential components> The alloy composition of the aluminum alloy wire rod of the present invention contains, as essential components, 0.30 mass % to 0.70 mass % of Mg and 0.30 mass % to 1.00 mass % of Si.

[0020] (Mg: 0.30% by mass or more and 0.70% by mass or less) Magnesium (Mg) is an element that, together with other additive elements such as Si, finely precipitates in an aluminum alloy, thereby increasing the tensile strength and electrical conductivity of the aluminum alloy. To achieve these effects, the Mg content is 0.30% by mass or more. If the Mg content is less than 0.30% by mass, most of the Mg remains in a solid solution state, making it difficult to precipitate Mg in the aluminum alloy. Furthermore, if the Mg content exceeds 0.70% by mass, the amount of Mg present in the form of coarse compounds far exceeding the solid solubility limit not only fails to contribute to improving tensile strength and electrical conductivity, but also causes wire drawing breakage, adversely affecting elongation characteristics. For this reason, the Mg content is 0.70% by mass or less. Therefore, the Mg content is in the range of 0.30% by mass or more and 0.70% by mass or less.

[0021] (Si: 0.30% by mass or more to 1.00% by mass) Si (silicon) is an element that, together with other additive elements, finely precipitates in an aluminum alloy, thereby increasing the tensile strength and electrical conductivity of the aluminum alloy. To achieve these effects, the Si content is 0.30% by mass or more. Here, if the Si content is less than 0.30% by mass, most of the Si remains in a solid solution state, making it difficult to precipitate Si in the aluminum alloy. Furthermore, if the Si content exceeds 1.00% by mass, the amount of Si far exceeding the solid solubility limit will exist as coarse compounds, which will not only fail to contribute to improving tensile strength and electrical conductivity, but will also cause wire drawing breakage, adversely affecting elongation characteristics. For this reason, the Si content is 1.00% by mass or less. Therefore, the Si content is in the range of 0.30% by mass or more to 1.00% by mass.

[0022] <Optionally Added Components> The alloy composition of the aluminum alloy wire rod of the present invention may further contain, as optional added components, one or more components selected from the group consisting of Mn, Fe, Ni, Ti, Cr, and Zr in a range of 0.001 mass % or more and 0.55 mass % or less in total.

[0023] (Mn: 0.001% by mass or more and 0.50% by mass or less) Mn (manganese) is a component that contributes to further refinement of crystal grains, further increasing the strength of the aluminum alloy wire rod, and also makes it difficult for grain growth to occur in a heat treatment process involving recrystallization, thereby preventing wire breakage. To exert this effect, it is preferable to contain 0.001% by mass or more of Mn. On the other hand, if the Mn content is too high, the effect will saturate and no longer change, or precipitation will be promoted, resulting in a relative decrease in the amount of precipitated MgSi-based compounds, which are particularly effective in the present invention. Furthermore, since there is a risk of disadvantages such as a decrease in electrical conductivity and adverse effects on manufacturability, it is preferable to keep the Mn content at 0.50% by mass or less.

[0024] (Fe: 0.001% by mass or more and 0.50% by mass or less) Fe (iron) is a component that contributes to further increasing the strength of aluminum alloy wire rods. To exert this effect, it is preferable to contain 0.001% by mass or more of Ti. On the other hand, if the Fe content is too high, the effect will saturate and no change will occur, and there is a risk of disadvantages such as a decrease in electrical conductivity and adverse effects on manufacturability. Therefore, it is preferable to keep the Fe content at 0.50% by mass or less.

[0025] (Ni: 0.001% by mass or more and 0.50% by mass or less) Ni (nickel) is a component that has the effect of improving the impact resistance properties of an aluminum alloy wire. To exert this effect, it is preferable to contain 0.001% by mass or more of Ni. On the other hand, if the Ni content is too high, the effect will saturate and no change will occur, and there is also the risk of disadvantages such as a decrease in electrical conductivity and adverse effects on manufacturability. Therefore, it is preferable to keep the Ni content at 0.50% by mass or less.

[0026] (Ti: 0.001% by mass or more and 0.50% by mass or less) When added as TiB, Ti (titanium) has the effect of refining the solidification structure during casting, and is a component that contributes to improving manufacturability in the rolling process after casting. To exert this effect, it is preferable to contain 0.001% by mass or more of Ti. On the other hand, the Ti content may cause disadvantages such as a decrease in electrical conductivity and an adverse effect on manufacturability, so it is preferable to keep it at 0.50% by mass or less.

[0027] (Cr: 0.001% by mass or more and 0.50% by mass or less) Cr (chromium), like Mn, is a component that has the effect of refining crystal grains and of making grain growth at high temperatures less likely to occur, thereby making wire breakage less likely. To achieve this effect, it is preferable to contain 0.001% by mass or more of Cr. On the other hand, if the Cr content is too high, the effect will saturate and no change will occur, and precipitation may be promoted, resulting in a relative decrease in the amount of precipitated MgSi-based compounds. Furthermore, since there is a risk of disadvantages such as a decrease in electrical conductivity and adverse effects on manufacturability, it is preferable to keep the Cr content at 0.50% by mass or less.

[0028] (Zr: 0.001% by mass or more and 0.50% by mass or less) Zr (zirconium) is a component that can improve the heat resistance of an aluminum alloy wire rod. To achieve this effect, it is preferable to contain 0.001% by mass or more of Zr. On the other hand, if the Zr content is too high, the effect will saturate and no change will occur, and there is a risk of disadvantages such as a decrease in electrical conductivity and adverse effects on manufacturability. Therefore, it is preferable to keep the Zr content at 0.50% by mass or less.

[0029] (Total Amount of Optionally Added Components: 0.001% by Mass or More and 0.55% by Mass or Less) The optionally added components, which are one or more components selected from the group consisting of Mn, Fe, Ni, Ti, Cr, and Zr, are preferably contained in a total amount of 0.001% by mass or more in order to obtain the effects of these optionally added components. These optional added components can also be in the form of solid solution or precipitate in the aluminum alloy wire rod. Increasing their content can result in solid solution strengthening, strengthening due to refinement of crystal grains in the matrix, and precipitation strengthening due to promotion of the reaction of the optional added components. On the other hand, if the content of these optional added components is too high, the effects will saturate and no longer change, and there is a risk of disadvantages such as a decrease in electrical conductivity and adverse effects on manufacturability. Therefore, the total amount of these optional added components is preferably 0.55% by mass or less.

[0030] <Remainder: Al and Inevitable Impurities> The alloy composition of the aluminum alloy wire of the present invention is such that the remainder, other than the above-mentioned elements, consists of Al and inevitable impurities. Note that the term "inevitable impurities" as used herein generally refers to impurities present in raw materials or unavoidably mixed in during the manufacturing process of aluminum alloy wire. These impurities are essentially unnecessary but are tolerated in trace amounts because they do not affect the properties of the aluminum alloy wire. Examples of components that can be cited as inevitable impurities include nonmetallic elements such as sulfur (S), carbon (C), and oxygen (O), and metallic elements such as vanadium (V), gallium (Ga), and antimony (Sb). The upper limit of the content of these components is preferably low because they can reduce electrical conductivity and tensile strength. This upper limit can be 0.05% by mass for each component, or 0.05% by mass for the total amount of the components. More preferably, the upper limit is 0.01% by mass for each component, or 0.01% by mass for the total amount of the components.

[0031] [2] Metallographic Structure of Aluminum Alloy Wire Rod Next, the metallographic structure of the aluminum alloy wire rod will be described.

[0032] In the aluminum alloy wire of the present invention, crystal orientation analysis by electron backscatter diffraction (EBSD) performed on an observation region of a cross section perpendicular to the longitudinal direction shows that the proportion of measurement points with a crystal orientation difference of 5° or less from adjacent measurement points is 85% or less. Such low-angle crystal orientation differences of 5° or less are often formed by dislocation defects, and if the proportion exceeds 85%, it is believed that plastic processing strain applied during the manufacturing process of the aluminum alloy wire has not been sufficiently removed. One possible cause of this is insufficient heating in the third heat treatment step (solution heat treatment step) described below, where insufficient heating prevents sufficient recrystallization and allows strain to remain. Furthermore, insufficient heating in the third heat treatment step (solution heat treatment step) does not sufficiently increase the solid solubility of Mg and Si, resulting in insufficient recovery of elongation properties and precipitation strengthening during the subsequent aging treatment step. In other words, by setting the proportion of measurement points having a crystal orientation difference of 5° or less with respect to adjacent measurement points to 85% or less of all measurement points in the measurement area, plastic processing strain is sufficiently removed, and elongation properties are restored and precipitation strengthening is achieved, thereby making it possible to improve the tensile strength and elongation properties of the aluminum alloy wire. Note that the longitudinal direction of the aluminum alloy wire means the wire-drawing direction of the wire in the manufacturing process.

[0033] Here, crystal orientation analysis using the electron backscatter diffraction (EBSD) method can be performed by, for example, continuously measuring the crystal orientation using an EBSD detector (TSL, OIM5.0 HIKARI) attached to a high-resolution scanning analytical electron microscope JSM-7001FA (manufactured by JEOL Ltd.), and calculating (processing) the crystal orientation data obtained by the measurement using analysis software (TSL Solutions, OIM-Analysis) to obtain crystal orientation analysis data. "EBSD" stands for Electron Backscatter Diffraction, and is a crystal orientation analysis technique that utilizes Kikuchi lines that are generated when an electron beam is irradiated on an aluminum alloy wire, which is a measurement sample, in a scanning electron microscope (SEM). The measurement target is a cross section perpendicular to the longitudinal direction of a single aluminum alloy wire, the surface of which has been polished to a mirror finish in advance. The cross section can be polished using a Cross-Section Polisher (registered trademark) device, as well as wet polishing, FIB, microtome, or other means capable of achieving a mirror finish; the specific means are not critical. The measurement area can be the area cut out from a single aluminum alloy wire, and can be, for example, 50 μm to 300 μm square. The crystal orientation measurement for obtaining crystal orientation data can be performed with a step size of, for example, 0.5 μm to 2 μm. In particular, by using analysis software to analyze the crystal orientation data, it is possible to easily determine whether the crystal orientation difference between adjacent measurement points is within an allowable range when a specific angle range is allowed for the crystal orientation difference between adjacent measurement points.

[0034] In the aluminum alloy wire of the present invention, when crystal orientation analysis is performed by electron backscatter diffraction (EBSD) in an observation area of ​​a cross section perpendicular to the longitudinal direction, where crystal orientations within ±5° of the <100> orientation are defined as the <100> orientation group, crystal orientations within ±5° of the <110> orientation are defined as the <110> orientation group, and crystal orientations within ±5° of the <111> orientation are defined as the <111> orientation group, it is preferable that the ratio of the number of crystal grains having the <111> orientation group to the total number of crystal grains having the <100> orientation group and the <110> orientation group (<111> orientation group / (<100> orientation group + <110> orientation group)) is in the range of 5 to 30.

[0035] Here, crystal grains having a <111> orientation group contribute to improving the tensile strength of an aluminum alloy wire rod, but have the property of degrading elongation characteristics. Furthermore, crystal grains having a <111> orientation group may exist as a deformation texture when recrystallization does not progress sufficiently. In such cases, in addition to degrading elongation characteristics, they may also cause insufficient precipitation strengthening due to insufficient solid solution of Mg and Si. Thus, crystal grains having a <111> orientation group have the disadvantage of degrading the tensile strength and elongation characteristics of an aluminum alloy wire rod, and when the proportion of such crystal grains is high, this disadvantage tends to be more pronounced.

[0036] Furthermore, although crystal grains having a <100> orientation group and a <110> orientation group do not contribute as much to improving tensile strength as crystal grains having a <111> orientation group, they can improve elongation characteristics. Furthermore, crystal grains having a <100> orientation group and a <110> orientation group accumulate when recrystallization has progressed sufficiently, so if the proportion of crystal grains having these orientation groups is high, the solid solubility of Mg and Si increases, thereby increasing the tensile strength of the aluminum alloy wire. In particular, increasing both the recrystallization rate and solid solubility of the aluminum alloy wire has the advantage of stably obtaining high tensile strength and elongation characteristics, so it is desirable to increase their proportions.

[0037] In particular, when the ratio of (<111> orientation group / (<100> orientation group + <110> orientation group)) is 1 or less, the proportion of crystal grains having the <111> orientation group decreases, resulting in a decrease in the tensile strength of the aluminum alloy wire. On the other hand, when the ratio of (<111> orientation group / (<100> orientation group + <110> orientation group)) is 100 or more, the proportion of (<100> orientation group + <110> orientation group) decreases, resulting in poor elongation characteristics of the aluminum alloy wire. In particular, when the solid solution or recrystallization of Mg and Si is not sufficiently advanced, it becomes difficult to stably obtain high tensile strength. Therefore, it is preferable that the ratio of (<111> orientation group / (<100> orientation group + <110> orientation group)) is in the range of 5 to 30.

[0038] The proportion of crystal grains having the <100> orientation group, the <110> orientation group, and the <111> orientation group can be determined by analyzing the crystal orientation data obtained in a cross section using an EBSD detector as described above, defining the boundary where the orientation difference between adjacent measurement points is 15° or more as the interface (grain boundary) of the crystal grain, and defining the set of consecutive measurement points in the area surrounded by the grain boundary as a crystal grain, and calculating the proportion of the number of crystal grains having the <100> orientation group, the <110> orientation group, and the <111> orientation group out of the total number of crystal grains in the measurement area.

[0039] In the aluminum alloy wire of the present invention, the average crystal grain size obtained by crystal orientation analysis using electron backscatter diffraction (EBSD) performed on an observation region of a cross section perpendicular to the longitudinal direction may be, for example, in the range of 5 μm to 20 μm, but is preferably in the range of 5 μm to 9 μm. In particular, by setting the average crystal grain size of the crystals contained in the metallographic structure of the aluminum alloy wire to be in the range of 5 μm to 9 μm, the average value and standard deviation of one or both of the tensile strength and elongation properties of the aluminum alloy wire can be further improved. On the other hand, if the average crystal grain size is smaller than 5 μm, the solid solution of Mg and Si does not progress sufficiently, resulting in insufficient precipitation strengthening. Furthermore, insufficient heating for crystallization leaves plastic working strain imparted during the manufacturing process of the aluminum alloy wire, which tends to deteriorate the elongation properties. On the other hand, if the average crystal grain size is larger than 9 μm, particularly larger than 20 μm, the wire is more likely to break when recrystallized by running annealing.

[0040] Here, the average grain size of the crystal grains of the aluminum alloy wire rod can be the average diameter of the crystal grains equivalent to a circle when the cross-sectional area of ​​the crystal grain is calculated using the number of consecutive measurement points in the area surrounded by the grain boundary and the above-mentioned step size, when the boundary at which the orientation difference with adjacent measurement points is 15° or more is defined as the interface (grain boundary) of the crystal grain in the analysis of crystal orientation data by the above-mentioned electron backscatter diffraction (EBSD) method.

[0041] The aluminum alloy wire rod of the present invention has high tensile strength and high elongation properties, and therefore can provide high toughness even when the wire diameter (diameter) is small, in the range of 0.1 mm to 0.5 mm. Here, toughness is a property that is increased when both tensile strength and elongation properties are high, and the aluminum alloy wire rod having high toughness can easily maintain its original shape without breaking even when a force is applied in the tensile direction.

[0042] The aluminum alloy wire of the present invention can also be twisted together to form an aluminum alloy twisted wire, and in this case, high electrical conductivity and improved tensile strength and elongation characteristics can be achieved. Here, the number of twisted wires and the total cross-sectional area of ​​the twisted wire are not limited, but by twisting together aluminum alloy wires having the above-mentioned wire diameters in a number ranging from 5 to 16, a cross-sectional area of ​​0.1 mm or less can be achieved. ２ More than 3.0 mm ２ It is also possible to construct a small diameter aluminum alloy stranded wire within the following range.

[0043] Furthermore, the aluminum alloy wire of the present invention is preferably used for an electric wire, and it is preferable to configure an electric wire having the above-mentioned aluminum alloy wire. More specifically, an electric wire can be configured having the above-mentioned aluminum alloy wire or aluminum alloy stranded wire and an insulating coating layer covering the outer periphery of the aluminum alloy wire or aluminum alloy stranded wire. Such an electric wire can improve tensile strength, electrical conductivity, and elongation characteristics in a balanced manner, thereby reducing the weight of particularly small-diameter electric wires and reducing the weight of wire harnesses. In other words, it is also preferable to configure a wire harness using an electric wire having the above-mentioned aluminum alloy wire.

[0044] [3] Example of a manufacturing method for aluminum alloy wire The above-mentioned aluminum alloy wire can be realized by controlling a combination of alloy composition and manufacturing process, and the manufacturing process is not particularly limited. Among them, the following method can be cited as an example of a manufacturing process that can obtain the above-mentioned aluminum alloy wire.

[0045] An example of the method for producing an aluminum alloy wire rod of the present invention includes a method in which an aluminum alloy material having substantially the same alloy composition as the alloy composition of the above-mentioned aluminum alloy wire rod is subjected to at least a continuous casting and rolling step, a first heat treatment step, a first wiredrawing step, a second heat treatment step, a second wiredrawing step, and a third heat treatment step, in that order.

[0046] [Continuous Casting and Rolling Step] In the method for producing an aluminum alloy wire rod of the present invention, first, a continuous casting and rolling step is carried out in which an aluminum raw material and additive elements are selected so as to have a desired chemical composition, and then the raw material is cast and rolled to obtain an aluminum wire rod. The casting method in the continuous casting and rolling step is not limited, but from the viewpoint of production efficiency, it is preferable to use a Properti-type continuous casting and rolling mill that combines a casting wheel and a belt, which can continuously cast molten aluminum into a ring-shaped groove die and then continuously roll it to obtain a wire rod.

[0047] In the continuous casting and rolling process, for example, a continuous casting and rolling machine is used, and after casting, the material is rolled using two-way or three-way rolls to obtain a rolled material having a cross-sectional area equivalent to a wire diameter of 9 mm or more and 10 mm or less.

[0048] This rolled material is subjected to continuous wiredrawing until the wire diameter reaches a range of 0.1 mm to 0.5 mm. Because the heat treatment performed during wiredrawing affects the crystal orientation distribution of the aluminum alloy wire, it is important to perform the heat treatment under appropriate conditions. Furthermore, increasing the total drawing rate without heat treatment increases the deformation resistance, making the aluminum alloy wire more susceptible to breakage and increasing the wear damage of the dies used in the wiredrawing. Therefore, performing heat treatment at an appropriate time to soften the material is useful not only for improving mechanical properties but also for enhancing mass productivity. More specifically, it is preferable to perform two or more heat treatment steps, excluding the heat treatment performed after the second wiredrawing step (the third heat treatment step) described below. The heat treatment conditions are preferably a temperature range of 300°C to 400°C for 1 hour to 8 hours.

[0049] In the following explanation, an embodiment will be described in which a first wiredrawing step and a second wiredrawing step are performed as wiredrawing processes after a continuous casting and rolling step, and a first heat treatment step and a second heat treatment step are performed before these wiredrawing steps, respectively, but the present invention is not limited to this embodiment. In this way, by performing the first heat treatment step, the first wiredrawing step, the second heat treatment step, and the second wiredrawing step in this order after a continuous casting and rolling step, it is possible to perform a heat treatment on the aluminum wire rod at the timing when cold wiredrawing is performed at a processing rate of at least a certain level, and it is possible to easily perform the wiredrawing step and the heat treatment step when using continuous processing equipment.

[0050] [First Heat Treatment Step] The first heat treatment step is a step of heat treating an aluminum wirerod, which is a rolled material and has a cross-sectional area equivalent to a wire diameter of 9 mm or more and 10 mm or less, in a temperature range of 300° C. to 400° C. for 1 hour to 8 hours. The first heat treatment step is a step carried out to soften the aluminum wirerod and intentionally precipitate pinning particles that prevent crystal coarsening.

[0051] Because the crystal orientation during the first heat treatment step also affects the crystal orientation after the third heat treatment step described below, the first heat treatment step needs to be performed at a temperature range of 300°C to 400°C for 1 hour to 8 hours. Here, if the heat treatment temperature is less than 300°C or the heat treatment time is less than 1 hour, the aluminum wire rod cannot be sufficiently softened, making it difficult to perform the first and second wiredrawing steps described below. Furthermore, if the heat treatment temperature exceeds 400°C or the heat treatment time exceeds 8 hours, the metal structure becomes coarse, which tends to change the crystal orientation distribution of the resulting aluminum alloy wire. Furthermore, if the size of precipitates generated during the heat treatment increases, they will no longer be able to perform the role of grain boundary pinning in the third heat treatment step described below. As a result, the crystal grain size of the resulting aluminum alloy wire becomes coarse, which makes the aluminum alloy wire more susceptible to breakage and causes a decrease in tensile strength and elongation.

[0052] The first heat treatment step can be carried out using a known method such as a bell furnace.

[0053] [First Wiredrawing Step] The first wiredrawing step is a step of cold drawing the aluminum wire rod after the first heat treatment step, thereby preferably obtaining a rolled material having a cross-sectional area equivalent to a wire diameter of 1 mm or more and 3 mm or less.

[0054] The first wiredrawing step can be performed by a known method such as wiredrawing using a die. More specifically, the wiredrawing conditions, such as the die material and dimensions, wiredrawing oil, and pass reduction, can be those generally used in mass production of aluminum wire. The first wiredrawing step can be performed in one pass, or multiple passes until the desired wire diameter is obtained.

[0055] [Second Heat Treatment Step] The second heat treatment step is a step of heat treating the aluminum wire rod after the first wiredrawing step in a temperature range of 300° C. to 400° C. for 1 hour to 8 hours. Similar to the first heat treatment step, the second heat treatment step is also a step performed to soften the aluminum wire rod and intentionally precipitate pinning particles that prevent crystal coarsening.

[0056] For the same reasons as in the first heat treatment step, the second heat treatment step must be performed at a temperature in the range of 300° C. to 400° C. for 1 hour to 8 hours.

[0057] The second heat treatment step can be carried out using a known method such as a bell furnace, as in the first heat treatment step.

[0058] [Second Wiredrawing Step] The second wiredrawing step is a step of cold drawing the aluminum wire rod after the first heat treatment step. This allows an aluminum wire rod having a desired cross-sectional area to be obtained. Here, the cross-sectional area of ​​the aluminum wire rod after the second wiredrawing step is not particularly limited, but can be, for example, a cross-sectional area equivalent to a wire diameter of 0.1 mm or more and 0.5 mm or less.

[0059] The second wiredrawing step can be carried out by a known method such as wire drawing using a die, similar to the first wiredrawing step. The second wiredrawing step may be carried out in one pass, or may be carried out in multiple passes until the desired wire diameter is obtained.

[0060] [Third Heat Treatment Step] The third heat treatment step is a solution heat treatment, in which the aluminum wire rod after the second wiredrawing step is heat-treated at a temperature range of 500°C to 580°C for 3 seconds to 60 seconds. This allows precipitated elements to dissolve and determines the crystal orientation of the aluminum alloy wire rod that will precipitate by recrystallization. Here, when the heat treatment temperature is less than 500°C or the heat treatment time is less than 3 seconds, the proportion of measurement points with a crystal orientation difference of 5° or less between adjacent measurement points exceeds 85% in the crystal orientation analysis by the electron backscatter diffraction (EBSD) method described above. Furthermore, when the heat treatment temperature exceeds 580°C or the heat treatment time exceeds 60 seconds, grain growth occurs in the metal structure of the resulting aluminum alloy wire rod, which causes a decrease in tensile strength and elongation properties and makes the aluminum alloy wire rod more susceptible to breakage.

[0061] In addition, the heat treatment conditions of the third heat treatment step can also affect the ratio of the number of crystal grains having the <111> orientation group to the total number of crystal grains having the <100> orientation group and the <110> orientation group. When the heat treatment temperature is low or the heat treatment time is short, the number of crystal grains having the <111> orientation group increases, and the ratio of the number of (<111> orientation group / (<100> orientation group + <110> orientation group)) also tends to increase. In this case, solid solution does not progress sufficiently, and therefore the generation of crystal grains having the desired crystal orientation by recrystallization does not progress sufficiently, which may cause a decrease in the tensile strength and elongation properties of the aluminum alloy wire. When the heat treatment temperature is high or the heat treatment time is long, the number of crystal grains having the <100> orientation group and the <110> orientation group increases, and the tensile strength of the aluminum alloy wire tends to decrease. In these cases, the crystal grains become coarse, which causes a decrease in tensile strength and elongation characteristics, and also makes the aluminum alloy wire more susceptible to breakage.

[0062] The third heat treatment step can be performed using a known method such as a tube furnace, but since the heating time is short, it is preferable to heat the aluminum wire rod rapidly while checking the temperature reached by the aluminum wire rod. Furthermore, it is preferable to rapidly cool the aluminum wire rod after the third heat treatment step by water cooling or the like.

[0063] Here, before or after the third heat treatment step, a twisting step of twisting a plurality of aluminum wires together using a twisting machine and a compression step of compressing the twisted strand may be performed, whereby an aluminum alloy stranded wire can be produced by twisting a plurality of aluminum alloy wires together, with the twisting step and compression step having almost no effect on the metal structure.

[0064] [Aging Treatment Step] The aging treatment step is a step of holding or heat-treating the aluminum wire rod after the third heat treatment step at a temperature lower than that of the third heat treatment step. This allows crystal grains to be precipitated in the metal structure of the aluminum wire rod by recrystallization with a desired balance of crystal orientations, thereby making it possible to obtain an aluminum alloy wire rod or an aluminum alloy stranded wire that has high tensile strength and high electrical conductivity while also having excellent elongation properties, and that has an excellent balance of these properties and small variations in tensile strength and elongation properties along the length.

[0065] In the aging treatment step, at least an artificial aging treatment is performed to heat the aluminum wire rod, but natural aging treatment may be performed before the artificial aging treatment by holding the aluminum wire rod at a temperature close to room temperature. Here, the heat treatment in the artificial aging treatment can be performed at a temperature range of 100°C to 200°C for 2 hours to 10 hours. Furthermore, the natural aging treatment can be performed by holding the aluminum wire rod at a temperature range of 20°C to 50°C for 24 hours or more.

[0066] An electric wire can be manufactured by carrying out a covering extrusion step of covering the aluminum alloy wire or aluminum alloy stranded wire obtained above with an insulating covering by extruding the covering around the outer periphery of the aluminum alloy stranded wire.

[0067] Although the embodiments have been described above, the present invention is not limited to the above embodiments, but includes all aspects encompassed by the concept and scope of the claims of the present disclosure, and can be modified in various ways within the scope of the present disclosure.

[0068] Next, examples of the present invention and comparative examples will be described, but the present invention is not limited to these examples of the present invention.

[0069] The aluminum raw material and additive elements were selected so as to have the chemical composition shown in Table 1, and a continuous casting and rolling process was carried out using a continuous casting and rolling mill (manufactured by Properti Co., Ltd.) to produce a rolled aluminum wirerod having a cross section perpendicular to the longitudinal direction corresponding to a circle with a diameter of 9.5 mm. This aluminum wirerod was subjected to a first heat treatment process under the temperature and time conditions shown in Table 1, followed by a first wiredrawing process to reduce the cross section to a size corresponding to a circle with a diameter of 2.6 mm. This was then subjected to a second heat treatment process under the temperature and time conditions shown in Table 1, followed by a second wiredrawing process to reduce the cross section to a size corresponding to a circle with a diameter of 0.3 mm. The first and second heat treatment processes were carried out in an inert gas environment in a bell-type furnace.

[0070] The aluminum wire rod after the second wiredrawing step was subjected to a third heat treatment step, which was a solution heat treatment, under the temperature and time conditions shown in Table 1, and then promptly cooled by water cooling. Here, the third heat treatment step was performed by heating the aluminum wire rod in a protective tube in a ring furnace while checking the target temperature reached with a thermocouple.

[0071] After the third heat treatment step, the aluminum wire was subjected to a natural aging treatment in which the aluminum wire was held at a temperature range of 25° C. to 40° C. for 24 hours or more, and an artificial aging treatment in which the aluminum wire was heat-treated at a temperature range of 120° C. to 170° C. for 5 hours in the atmosphere, thereby obtaining the aluminum alloy wires of the present invention and comparative examples. Note that in actual manufacturing processes for aluminum electric wires, a twisting step and a compression step may be performed after these aging treatments, but these steps were omitted in the present invention and comparative examples because their effect on the properties is very small.

[0072] [Various Measurement and Evaluation Methods] The aluminum alloy wires obtained in the above-mentioned invention examples and comparative examples were used to carry out the following property evaluations. The evaluation conditions for each property were as follows.

[0073] [1] Measurement of the proportion of measurement points with a crystal orientation difference of 5° or less from adjacent measurement points relative to all measurement points The proportion of measurement points with a crystal orientation difference of 5° or less relative to all measurement points was determined from crystal orientation analysis data calculated using electron backscatter diffraction (EBSD). Here, the crystal orientation analysis data calculated using the electron backscatter diffraction (EBSD) method was obtained by continuously measuring the crystal orientation using an EBSD detector (TSL, OIM5.0 HIKARI) attached to a high-resolution scanning analytical electron microscope JSM-7001FA (manufactured by JEOL Ltd.), and calculating (processing) the crystal orientation data obtained by the measurement using analysis software (TSL Solutions, OIM-Analysis) to determine the proportion of all measurement points within the measurement area. The measurement object was a cross section perpendicular to the longitudinal direction of a single aluminum alloy wire, the surface of which had been polished to a mirror finish in advance. A Cross Section Polisher (registered trademark) device was used to polish the cross section. The measurement area was the area cut out from one aluminum alloy wire, more specifically, the area corresponding to a circle with a diameter of 0.3 mm. The crystal orientation measurement for obtaining crystal orientation data was performed with a step size of 0.5 μm. At this time, the measurement results of the orientation difference between adjacent measurement points were expressed in 1° increments. Furthermore, when determining whether the crystal orientation difference between adjacent measurement points was 5° or less, the measurement results of the crystal orientation difference were also expressed in 1° increments, and when the measurement result was in the range of 1° to 5°, the crystal orientation difference between adjacent measurement points was considered to be 5° or less. The results are shown in Table 2.

[0074] [2] Measurement of the ratio of the number of crystal grains having the <111> orientation group to the total number of crystal grains having the <100> orientation group and the <110> orientation group The proportion of the number of crystal grains having the <100> orientation group, the <110> orientation group, and the <111> orientation group was determined by analyzing the crystal orientation data obtained in the cross section using the EBSD detector as described above, where the boundary where the orientation difference between adjacent measurement points is 15° or more is defined as the interface (grain boundary) of the crystal grain, and the set of consecutive measurement points in the area surrounded by the grain boundary is defined as a crystal grain.The proportion of the number of crystal grains having the <100> orientation group, which has a crystal orientation within ±5° of the <100> orientation, the <110> orientation group, which has a crystal orientation within ±5° of the <110> orientation, and the <111> orientation group, which has a crystal orientation within ±5° of the <111> orientation, was calculated out of the total number of crystal grains in the measurement area, and the proportion of (<111> orientation group / (<100> orientation group + <110> orientation group)) was calculated from the number of crystal grains having these orientation groups. The results are shown in Table 2.

[0075] [3] Measurement of average grain size of crystal grains The average grain size of the crystal grains of the aluminum alloy wire rod was determined by calculating the cross-sectional area of ​​the crystal grain using the number of consecutive measurement points in the area surrounded by the grain boundary and the above-mentioned step size, when the boundary where the misorientation between adjacent measurement points is 15° or more in the analysis of crystal orientation data by the above-mentioned electron backscatter diffraction (EBSD) method was defined as the interface (grain boundary) of the crystal grain, and the average diameter of the crystal grain equivalent to the circle obtained from this was defined as the average grain size of the crystal grain. The results are shown in Table 2.

[0076] [4] Measurement and evaluation of tensile strength The tensile strength of the aluminum alloy wire rod was measured by cutting out test pieces having a length of 200 mm from a 2000 m long aluminum alloy wire rod, the test pieces including positions 0 m, 500 m, 1000 m, 1500 m, and 2000 m from one end, and measuring the tensile strength Rm of each test piece in accordance with JIS Z2241. The average value and standard deviation of the tensile strength Rm at these five positions were defined as the average value [MPa] and standard deviation [MPa] of the tensile strength, respectively.

[0077] Regarding the average tensile strength obtained, when the average tensile strength was 250 MPa or more, the average tensile strength value was sufficiently large and excellent in that it could be used alone without being mounted in a connector, and was evaluated as "Excellent (◎)". Furthermore, when the average tensile strength was in the range of 230 MPa or more but less than 250 MPa, the average tensile strength was large and good in that it could be used in a state housed in a general connector, and was evaluated as "Good (◯)". On the other hand, when the average tensile strength was less than 230 MPa, the average tensile strength was small and the aluminum alloy wire rod could break even when housed in a connector, and was evaluated as "Poor (×)". In the present invention examples and comparative examples, "◎" and "○" were evaluated as pass levels. The results are shown in Table 2.

[0078] In addition, when the standard deviation of the obtained tensile strength was 5.00 MPa or less, the standard deviation of the tensile strength was sufficiently small, and the tensile strength of the aluminum alloy wire rod was particularly stably obtained, and the result was evaluated as "Excellent". In addition, when the standard deviation of the tensile strength was in the range of more than 5.00 MPa and 10.00 MPa or less, the standard deviation of the tensile strength was small, and the tensile strength of the aluminum alloy wire rod was stably obtained, and the result was evaluated as "Good". On the other hand, when the standard deviation of the tensile strength exceeded 10.00 MPa, the tensile strength of the aluminum alloy wire rod was not stably obtained, and the result was evaluated as "Poor". In the present invention examples and comparative examples, "Excellent" and "Good" were evaluated as pass levels. The results are shown in Table 2.

[0079] [5] Measurement and evaluation of elongation characteristics The elongation characteristics of the aluminum alloy wire rod were measured by cutting out test pieces having a length of 200 mm from a 2000 m long aluminum alloy wire rod, the test pieces including positions 0 m, 500 m, 1000 m, 1500 m, and 2000 m from one end, and determining the fracture elongation A of each test piece based on JIS Z2241. The average value and standard deviation of the fracture elongation A at these five positions were defined as the average value [%] and standard deviation [%] of the elongation characteristics, respectively.

[0080] Regarding the average elongation characteristics obtained, when the average value of the elongation characteristics was 14.0% or more, the average value of the elongation characteristics was sufficiently large and excellent in that it could be used alone without being mounted in a connector, and was evaluated as "Excellent (◎)". When the average value of the elongation characteristics was in the range of 12.0% or more but less than 14.0%, the average value of the elongation characteristics was large and good in that it could be used in a state housed in a general connector, and was evaluated as "Good (○)". On the other hand, when the average value of the elongation characteristics was less than 12.0%, the average value of the elongation characteristics was small and the aluminum alloy wire rod could break even when housed in a connector, and was evaluated as "Poor (×)". In the present invention examples and comparative examples, "Excellent" and "Good" were evaluated as pass levels. The results are shown in Table 2.

[0081] In addition, when the standard deviation of the obtained elongation characteristics was 0.30% or less, the standard deviation of the elongation characteristics was sufficiently small, and the aluminum alloy wire rod was evaluated as "Excellent" because the standard deviation of the elongation characteristics was particularly stable. In addition, when the standard deviation of the tensile strength was in the range of more than 0.30% and 0.80% or less, the standard deviation of the elongation characteristics was small, and the aluminum alloy wire rod was evaluated as "Good" because the elongation characteristics were stable equivalent to the evaluation of "Good". On the other hand, when the standard deviation of the elongation characteristics exceeded 0.80%, the aluminum alloy wire rod was evaluated as "Poor" because the elongation characteristics were not stable. In the present invention examples and comparative examples, "Excellent" and "Good" were evaluated as pass levels. The results are shown in Table 2.

[0082] [6] Measurement and Evaluation of Electrical Conductivity The electrical conductivity of the aluminum alloy wire was measured twice in accordance with JIS H0505 (-1975), and the average value of the electrical conductivity obtained by the two measurements was taken as the measured value of electrical conductivity [% IACS].

[0083] Regarding the obtained measured conductivity, when the value exceeded 50.0% IACS, the aluminum alloy wire had a sufficiently high conductivity value and was evaluated as "Excellent" because it was an excellent wire that could be used as an electric wire that could be further reduced in diameter in the future. Furthermore, when the measured conductivity was in the range of 48.0% IACS or more and 50.0% IACS or less, the value was evaluated as "Good" because the conductivity value was high and the wire was suitable for use as an aluminum alloy wire for a currently thinned electric wire. On the other hand, when the measured conductivity was less than 48.0% IACS, the value was evaluated as "Poor" because the conductivity value was low and the wire was unsuitable for use as an aluminum alloy wire for a thinned electric wire. In the present invention examples and comparative examples, "Excellent" and "Good" were evaluated as acceptable levels. The results are shown in Table 2.

[0084] The above "% IACS" refers to the resistivity of International Annealed Copper Standard, 1.7241 x 10 －８ It is a unit of conductivity when Ωm is 100% IACS.

[0085] [7] Overall Evaluation Among these evaluation results, for the five evaluation results regarding the average tensile strength, the standard deviation of tensile strength, the average elongation, the standard deviation of elongation, and the electrical conductivity, if all five were rated as "◎", it was evaluated as "◎", indicating that the specimen had high tensile strength and high electrical conductivity, excellent elongation, and small longitudinal variation in tensile strength and elongation. Furthermore, if all five of these evaluation results were rated as "◎" or "○" (excluding cases where all five were rated as "◎"), it was evaluated as "○", indicating that the specimen had high tensile strength and high electrical conductivity, excellent elongation, and small longitudinal variation in tensile strength and elongation. On the other hand, if at least one of these five evaluation results was rated as "×", it was evaluated as "×", indicating that the specimen failed in at least one of the tensile strength, electrical conductivity, and elongation, or failed due to large longitudinal variation in tensile strength and elongation. The results are shown in Table 2.

[0086]

[0087]

[0088] As shown in Tables 1 and 2, in Examples 1 to 22 of the present invention, aluminum alloy wires having a predetermined alloy composition were obtained by controlling the first, second, and third heat treatment steps of the manufacturing process under predetermined conditions. As a result, in a crystal orientation analysis of the cross section of the aluminum alloy wire by electron backscatter diffraction (EBSD) method, the proportion of measurement points with a crystal orientation difference of 5° or less with respect to all measurement points was 85% or less. As a result of the evaluation, it was confirmed that all of Examples 1 to 22 of the present invention had high tensile strength and high electrical conductivity while also having excellent elongation properties, and thus had an excellent balance of these properties and small variation in tensile strength and elongation properties along the length.

[0089] On the other hand, for Comparative Example 1, where the Mg and Si contents in the alloy composition were both low and outside the appropriate range, the average tensile strength was poor and did not meet the acceptable level. For Comparative Example 2, where the Mg and Si contents in the alloy composition were both high and outside the appropriate range, the average elongation and electrical conductivity were both poor and did not meet the acceptable level. For Comparative Examples 3 to 14, where the proportion of measurement points with a crystal orientation difference of 5° or less exceeded 85% of all measurement points, at least the average tensile strength and the average and standard deviation of elongation were poor and did not meet the acceptable level.

Claims

1. An aluminum alloy wire having an alloy composition containing 0.30 mass% or more and 0.70 mass% or less of Mg and 0.30 mass% or more and 1.00 mass% or less of Si, with the remainder being Al and unavoidable impurities, wherein, in a crystal orientation analysis performed by electron backscatter diffraction (EBSD) method in an observation region of a cross section perpendicular to the longitudinal direction of the aluminum alloy wire, the proportion of measurement points having a crystal orientation difference of 5° or less between adjacent measurement points is 85% or less out of all measurement points.

2. An aluminum alloy wire containing 0.30% by mass or more and 0.70% by mass or less of Mg and 0.30% by mass or more and 1.00% by mass or less of Si, and further containing one or more components selected from the group consisting of Mn, Fe, Ni, Ti, Cr and Zr in a total range of 0.001% by mass or more and 0.55% by mass or less, with the remainder being Al and unavoidable impurities, wherein, in a crystal orientation analysis performed by electron backscatter diffraction (EBSD) method in an observation region of a cross section perpendicular to the longitudinal direction of the aluminum alloy wire, the proportion of measurement points having a crystal orientation difference between adjacent measurement points of 5° or less is 85% or less out of all measurement points.

3. The aluminum alloy wire according to claim 1 or 2, wherein, in the crystal orientation analysis performed in the observation area, when crystal orientations within ±5° of the <100> orientation are defined as a <100> orientation group, crystal orientations within ±5° of the <110> orientation are defined as a <110> orientation group, and crystal orientations within ±5° of the <111> orientation are defined as a <111> orientation group, the ratio of the number of crystal grains having the <111> orientation group to the total number of crystal grains having the <100> orientation group and the <110> orientation group (<111> orientation group / (<100> orientation group+<110> orientation group)) is in the range of 5 or more and 30 or less.

4. An aluminum alloy wire according to claim 1 or 2, wherein the average crystal grain size of the crystal grains obtained from the crystal orientation analysis performed in the observation region is in the range of 5 μm or more and 9 μm or less.

5. An electric wire comprising the aluminum alloy wire according to claim 1 or 2.

6. A wire harness comprising the electric wire according to claim 5.

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