JP2016108612A - Aluminum alloy wire rod, aluminum alloy twisted wire, covered cable, wire harness, and method for producing aluminum alloy wire rod - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy wire rod combining high tensile strength and excellent vibration resistance in addition to bending fatigue resistance or the like.SOLUTION: Provided is an aluminum alloy wire rod having a composition containing, by mass, 0.10 to 1.00% Mg, 0.10 to 1.00% Si, 0.01 to 1.40% Fe, 0 to 0.100% Ti, 0 to 0.030% B, 0 to 1.00% Cu, 0 to 0.50% Ag, 0 to 0.50% Au, 0 to 1.00% Mn, 0 to 1.00% Cr, 0 to 0.50% Zr, 0 to 0.50% Hf, 0 to 0.50% V, 0 to 0.50% Sc, 0 to 0.50% Sn, 0 to 0.50% Co and 0 to 0.50% Ni, and the balance Al with inevitable impurities, and in which the area ratio of the region in which the angle 13 between the longitudinal direction 11 of the aluminum alloy wire rod 15 and the<111>direction 12 of the crystals 14 is within 20° being above 65%.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an aluminum alloy wire, an aluminum alloy twisted wire, a covered electric wire and a wire harness used as a wire of an electric wiring body, and a method for producing an aluminum alloy wire.

  Conventionally, as an electric wiring body of a moving body such as an automobile, a train, and an aircraft, or an electric wiring body of an industrial robot, a terminal made of copper or a copper alloy (for example, brass) is used for an electric wire including a copper or copper alloy wire ( A so-called wire harness member equipped with a connector has been used. In recent years, the performance and functionality of automobiles have been rapidly advanced, and as a result, the number of various electric devices and control devices mounted on the vehicle has increased, and these devices are used in these devices. There is also a tendency for the number of electric wiring bodies to increase. On the other hand, in order to improve the fuel efficiency of a moving body such as an automobile for environmental reasons, it is strongly desired to reduce the weight of the moving body.

As one of means for achieving the weight reduction of such a moving body, for example, it is considered to replace the wire material of the electric wiring body with a lighter aluminum or aluminum alloy instead of the conventionally used copper or copper alloy. It is being advanced. The specific gravity of aluminum is about 1/3 of the specific gravity of copper, and the electrical conductivity of aluminum is about 2/3 of the electrical conductivity of copper (pure aluminum is about 66% IACS when pure copper is used as a standard of 100% IACS). In order to allow the same current to flow through the aluminum conductor as the copper conductor, the cross-sectional area of the aluminum conductor needs to be about 1.5 times the cross-sectional area of the copper conductor. Even if an aluminum conductor having a large thickness is used, the mass of the aluminum conductor is about half of the mass of the pure copper conductor, and therefore the use of the aluminum conductor is advantageous from the viewpoint of weight reduction. In addition, said% IACS expresses the electrical conductivity when the resistivity 1.7241 × 10 ⁻⁸ Ωm of universal standard annealed copper (International Annealed Copper Standard) is 100% IACS.

However, pure aluminum wires represented by aluminum alloy wires for power transmission lines (A1060 and A1070 according to JIS standards) are generally known to have poor bending characteristics. Therefore, for example, it cannot withstand repeated stress applied at a bent portion such as a door portion. As a technique for solving such a problem, Patent Document 1 proposed by the present applicant has disclosed the technique. However, in recent years, the weight of the moving body has been reduced in order to improve the fuel efficiency of the moving body such as an automobile for environmental reasons. There is a demand for details, and it is desired to apply an aluminum wire to a thin wire having a smaller diameter, for example, a cross-sectional area of 0.5 mm ² (corresponding to 0.5 sq) or less. Even in a small-diameter electric wire, for example, it is required not to break even when an operator pulls the electric wire unexpectedly in the work of assembling a wire harness or the like to the vehicle body, so a higher-strength electric wire is desired. . Conventional levels of conductivity are also required.

  In order to have such characteristics, it is one solution to add various additive elements to form an alloy, but at the same time, it causes a decrease in conductivity due to a solid solution phenomenon of the additive elements in aluminum. Therefore, it is necessary to limit or select an additive element. As a typical example, for example, there is a 6000 series aluminum alloy (Al-Mg-Si series alloy) wire disclosed in Patent Document 2 or Patent Document 3 proposed by the present applicant, and subjected to solution treatment and aging treatment. As a result, the strength can be increased.

Japanese Patent No. 5193375 Japanese Patent No. 5607854 Japanese Patent No. 5607855

  However, at the forefront of development, it has become more demanded to develop an aluminum electric wire that can be applied even under severe use environments such as the vicinity of the engine section. Until now, aluminum wires have not been used in the vicinity of the engine section because they cannot withstand fatigue caused by vibrations applied near the engine section and may break. Therefore, in addition to satisfying conventionally required electrical conductivity and bending fatigue resistance properties, it is required to develop an aluminum electric wire having higher tensile strength and excellent vibration resistance.

  On the other hand, the conventional aluminum alloy wires described in Patent Documents 1 to 3 cannot sufficiently meet the more severe requirements as described above.

  An object of the present invention is to provide an aluminum alloy wire, an aluminum alloy twisted wire used as a wire of an electric wiring body, which has high tensile strength and excellent vibration resistance in addition to the conventionally required bending fatigue resistance. It is providing the manufacturing method of a covered electric wire and a wire harness, and an aluminum alloy wire.

  The present inventors have made various studies and controlled the heat treatment conditions when manufacturing the aluminum alloy wire, and controlled the crystal orientation and the precipitation structure, thereby maintaining high bending fatigue resistance and high strength and excellent resistance. It has been found that an aluminum alloy wire having vibration properties can be produced, and the present invention has been completed based on this finding.

  More specifically, according to the study by the present inventors, Patent Document 2 has a high intermediate heat treatment temperature of 300 to 480 ° C., and the solution heat treatment is a heat treatment in which an additive element is dissolved in aluminum. In such a case, crystal grain growth proceeds, and it is difficult to obtain a large number of regions in which the angle between the longitudinal direction of the aluminum alloy wire and the <111> direction of the crystal is within 20 °. I understood that. Further, in Patent Document 3, since the intermediate heat treatment temperature is 480 to 620 ° C. in the solution temperature range, the region where the angle between the longitudinal direction of the wire and the <111> direction of the crystal is within 20 ° in the intermediate heat treatment is remarkable. As a result, the region where the angle between the longitudinal direction of the wire after the second heat treatment and the <111> direction of the crystal is within 20 ° has also decreased. Therefore, it has been found that the problem is that the vibration resistance is lowered and the vibration cannot be used in a severe use environment such as the vicinity of the engine section. Therefore, the present inventors have further studied based on these new findings and have completed the present invention.

That is, the gist configuration of the present invention is as follows.
(1) Aluminum alloy wire, Mg: 0.10 to 1.00 mass%, Si: 0.10 to 1.00 mass%, Fe: 0.01 to 1.40 mass%, Ti: 0 to 0.100 mass%, B: 0 to 0.030 mass%, Cu: 0 to 1.00 mass%, Ag: 0 to 0.50 mass%, Au: 0 to 0.50 mass%, Mn: 0 to 0 1.00% by mass, Cr: 0 to 1.00% by mass, Zr: 0 to 0.50% by mass, Hf: 0 to 0.50% by mass, V: 0 to 0.50% by mass, Sc: 0 to 0% 0.50% by mass, Sn: 0-0.50% by mass, Co: 0-0.50% by mass, Ni: 0-0.50% by mass, balance: Al and inevitable impurities, The area ratio of the region in which the angle formed by the longitudinal direction of the aluminum alloy wire and the <111> direction of the crystal is within 20 ° is more than 65%, and the aluminum Present in um alloy wire, aluminum, characterized in that the dispersion density of Mg-Si-based compound in diameter 0.5~5.0μm in circle equivalent diameter in terms is 3 × ^{10 -3} cells / [mu] m ² or less Alloy wire. In addition, among the elements whose content ranges are listed in the chemical composition, any of the elements whose lower limit value of the content range is described as “0% by mass” are optionally added as necessary. Means. That is, when the predetermined additive element is “0 mass%”, it means that the additive element is not included.

(2) The above chemical composition containing one or two selected from the group consisting of Ti: 0.001 to 0.100 mass% and B: 0.001 to 0.030 mass% (1) Aluminum alloy wire described in the above.

(3) The chemical composition is Cu: 0.01 to 1.00% by mass, Ag: 0.01 to 0.50% by mass, Au: 0.01 to 0.50% by mass, Mn: 0.01 to 1.00 mass%, Cr: 0.01-1.00 mass%, Zr: 0.01-0.50 mass%, Hf: 0.01-0.50 mass%, V: 0.01-0. 50% by mass, Sc: 0.01 to 0.50% by mass, Sn: 0.01 to 0.50% by mass, Co: 0.01 to 0.50% by mass and Ni: 0.01 to 0.50% by mass The aluminum alloy wire according to (1) or (2) above, containing one or more selected from the group consisting of%.

(4) The aluminum alloy according to the above (1), (2) or (3), wherein the number of repeated fractures when performing a double flexural fatigue test with a strain amplitude of ± 0.09% is 2 million times or more wire.

(5) The aluminum alloy wire according to any one of (1) to (4), wherein the thickness of the oxide layer present in the surface layer is 100 nm or less.

(6) The aluminum alloy wire according to any one of (1) to (5), wherein the diameter is 0.10 to 0.50 mm.

(7) An aluminum alloy twisted wire obtained by twisting a plurality of the aluminum alloy wires according to any one of (1) to (6) above.

(8) A coated electric wire having a coating layer on the outer periphery of the aluminum alloy wire according to any one of (1) to (6) or the aluminum alloy stranded wire according to (7).

(9) A wire harness comprising the covered electric wire according to (8) and a terminal attached to an end of the covered electric wire from which the covering layer is removed.

(10) After melting and casting, a rough drawn wire is formed through hot working, and thereafter, at least one crystal orientation forming treatment is performed during wire drawing, and then each step of solution treatment and aging heat treatment Any one of the above (1) to (6), wherein the crystal orientation forming treatment is performed to a predetermined temperature within a range of 150 ° C. or higher and lower than 250 ° C. The manufacturing method of the aluminum alloy wire described in the item.

  According to the present invention, with the above configuration, an aluminum alloy wire, an aluminum alloy twisted wire, which can be used for a thin wire with high strength, can be used for engine vibration that is constantly generated, and is used as an electric wiring body that is difficult to break. It becomes possible to provide the manufacturing method of a covered electric wire and a wire harness, and an aluminum alloy wire. The present invention is particularly useful as a battery cable mounted on a moving body, a harness or a conductor for a motor, and a wiring body for an industrial robot. Furthermore, since the aluminum alloy wire of the present invention has excellent bending fatigue resistance, which has been conventionally required, it can also be used in bent parts such as doors and has higher tensile strength. The diameter can also be reduced, and it can also be suitably used in the vicinity of an engine portion that requires a high level of vibration resistance.

It is a schematic diagram for demonstrating the angle | corner which the longitudinal direction of the aluminum alloy wire which concerns on embodiment of this invention makes, and the <111> direction of a crystal | crystallization. It is explanatory drawing of the test which measures the frequency | count of repeated fracture | rupture performed in the Example.

An aluminum alloy wire of an embodiment of the present invention (hereinafter simply referred to as “this embodiment”) has Mg: 0.10 to 1.00 mass%, Si: 0.10 to 1.00 mass%, Fe: 0 0.01 to 1.40 mass%, Ti: 0 to 0.100 mass%, B: 0 to 0.030 mass%, Cu: 0 to 1.00 mass%, Ag: 0 to 0.50 mass%, Au : 0 to 0.50 mass%, Mn: 0 to 1.00 mass%, Cr: 0 to 1.00 mass%, Zr: 0 to 0.50 mass%, Hf: 0 to 0.50 mass%, V : 0 to 0.50 mass%, Sc: 0 to 0.50 mass%, Sn: 0 to 0.50 mass%, Co: 0 to 0.50 mass%, Ni: 0 to 0.50 mass%, the balance : Al and an inevitable impurity composition. Further, in the aluminum alloy wire of the present embodiment, the area ratio of the region where the angle formed by the longitudinal direction and the <111> direction of the crystal is within 20 ° is more than 65%, and the circle is present in the aluminum alloy wire. The dispersion density of the Mg—Si compound having a diameter of 0.5 to 5 μm in terms of equivalent diameter is 3 × 10 ⁻³ pieces / μm ² or less.

  The reasons for limiting the chemical composition, crystal orientation, precipitation structure, and the like of the aluminum alloy wire of the present embodiment are shown below.

(1) Chemical composition <Mg: 0.10 to 1.00% by mass>
Mg (magnesium) is an element having a function of strengthening by solid solution in an aluminum base material, and a part of which is combined with Si to form a precipitate to improve tensile strength. However, when the Mg content is less than 0.10% by mass, the above-described effects are insufficient, and when the Mg content exceeds 1.00% by mass, the electrical conductivity decreases. Therefore, the Mg content is 0.10 to 1.00% by mass. The Mg content is preferably 0.50 to 1.00% by mass when high strength is important, and 0.10 to 0.50% by mass when electrical conductivity is important. From such a viewpoint, it is preferably 0.30 to 0.70% by mass.

<Si: 0.10 to 1.00% by mass>
Si (silicon) is an element having an effect of improving the tensile strength by combining with Mg to form a precipitate. When the Si content is less than 0.10% by mass, the above-described effects are insufficient, and when the Si content exceeds 1.00% by mass, the electrical conductivity decreases. Therefore, the Si content is 0.10 to 1.00% by mass. The Si content is preferably 0.50 to 1.00% by mass when importance is placed on high strength, and 0.10 to 0.50% by mass when conductivity is important. From such a viewpoint, it is preferably 0.30 to 0.70% by mass.

<Fe: 0.01 to 1.40% by mass>
Fe (iron) is an element that contributes to refinement of crystal grains and mainly improves tensile strength by forming an Al—Fe-based intermetallic compound. Fe can only be dissolved at 0.05% by mass at 655 ° C. in Al and is still less at room temperature. Therefore, the remaining Fe that cannot be dissolved in Al is Al—Fe, Al—Fe—Si, Al—Fe. -Crystallizes or precipitates as an intermetallic compound such as Si-Mg. This intermetallic compound contributes to the refinement of crystal grains and improves the tensile strength. Moreover, Fe has the effect | action which improves a tensile strength also by Fe dissolved in Al. If the Fe content is less than 0.01% by mass, these effects are insufficient, and if the Fe content exceeds 1.40% by mass, the wire is drawn due to coarsening of crystallized matter or precipitates. Workability deteriorates and conductivity decreases. Therefore, the Fe content is 0.01 to 1.40% by mass, preferably 0.10 to 0.70% by mass, and more preferably 0.10 to 0.45% by mass.

  The aluminum alloy wire of the present embodiment contains Mg, Si and Fe as essential components, but if necessary, one or two selected from the group consisting of Ti and B, Cu, Ag, One or more of Au, Mn, Cr, Zr, Hf, V, Sc, Sn, Co and Ni can be contained.

<Ti: 0.001 to 0.100 mass%>
Ti (titanium) is an element having an effect of refining the structure of the ingot at the time of melt casting. If the structure of the ingot is coarse, the ingot cracking in the casting or disconnection occurs in the wire processing step, which is not industrially desirable. If the Ti content is less than 0.001% by mass, the above-mentioned effects cannot be fully exhibited, and if the Ti content exceeds 0.100% by mass, the conductivity tends to decrease. It is. Therefore, the Ti content is 0.001 to 0.100 mass%, preferably 0.005 to 0.050 mass%, more preferably 0.005 to 0.030 mass%.

<B: 0.001 to 0.030 mass%>
B (boron) is an element having an effect of refining the structure of the ingot at the time of melt casting, like Ti. A coarse ingot structure is not industrially desirable because it tends to cause ingot cracking and disconnection in the wire processing step during casting. When the B content is less than 0.001% by mass, the above-described effects cannot be sufficiently exhibited, and when the B content exceeds 0.030% by mass, the conductivity tends to decrease. Therefore, the B content is 0.001 to 0.030 mass%, preferably 0.001 to 0.020 mass%, more preferably 0.001 to 0.010 mass%.

<Cu: 0.01 to 1.00% by mass>, <Ag: 0.01 to 0.50% by mass>, <Au: 0.01 to 0.50% by mass>, <Mn: 0.01 to 1 0.00 mass%, <Cr: 0.01 to 1.00 mass%> and <Zr: 0.01 to 0.50 mass%>, <Hf: 0.01 to 0.50 mass%>, <V : 0.01 to 0.50 mass%, <Sc: 0.01 to 0.50 mass%>, <Sn: 0.01 to 0.50 mass%>, <Co: 0.01 to 0.50 1% or more of <% by mass> and <Ni: 0.01 to 0.50% by mass> Cu (copper), Ag (silver), Au (gold), Mn (manganese), Cr ( Chromium), Zr (zirconium), Hf (hafnium), V (vanadium), Sc (scandium), Sn (tin), Co (cobalt) and Ni (ni) Neckel) is an element that has the effect of refining crystal grains, and Cu, Ag, and Au are elements that also have the effect of increasing the grain boundary strength by precipitating at the grain boundaries. If at least one element is contained in an amount of 0.01% by mass or more, the above-described effects can be obtained, and the tensile strength and elongation can be improved. On the other hand, if any of the contents of Cu, Ag, Au, Mn, Cr, Zr, Hf, V, Sc, Sn, Co and Ni exceeds the above upper limit, the compound containing the element is coarse. Since wire drawing workability is deteriorated, disconnection is likely to occur, and the conductivity tends to decrease. Therefore, the ranges of the contents of Cu, Ag, Au, Mn, Cr, Zr, Hf, V, Sc, Sn, Co, and Ni are set to the above ranges, respectively.

  In addition, Fe, Ti, B, Cu, Ag, Au, Mn, Cr, Zr, Hf, V, Sc, Sn, Co, and Ni tend to decrease in electrical conductivity and wire drawing workability as the content increases. Tend to. Therefore, the total content of these elements is preferably 2.00% by mass or less. Since Fe is an essential element in the aluminum alloy wire of the present invention, the total content of Fe, Ti, B, Cu, Ag, Au, Mn, Cr, Zr, Hf, V, Sc, Sn, Co and Ni is 0. 01-2.0 mass%. The content of these elements is more preferably 0.05 to 1.0% by mass. However, when these elements are added alone, the larger the content, the more the compound containing the elements tends to become coarser, which deteriorates the wire drawing workability and easily causes disconnection. The element content is within the range specified above.

<Balance: Al and inevitable impurities>
The balance other than the components described above is Al (aluminum) and inevitable impurities. The inevitable impurities referred to here mean impurities in a content level that can be unavoidably included in the manufacturing process. Depending on the content of the inevitable impurities, it may be a factor for reducing the electrical conductivity. Therefore, it is preferable to suppress the content of the inevitable impurities to some extent in consideration of the decrease in the electrical conductivity. Examples of components listed as inevitable impurities include Ga (gallium), Zn (zinc), Bi (bismuth), and Pb (lead).

(2) Crystal orientation of aluminum alloy wire In addition to having the above-mentioned chemical composition, the present invention provides an area ratio of a region in which the angle between the longitudinal direction of the aluminum alloy wire and the <111> direction of the crystal is within 20 ° Must be greater than 65%.

  In the present embodiment, the crystal orientation is defined using the longitudinal direction of the aluminum alloy wire as the sample axis. Here, the “crystal orientation” represents in which direction the crystal axis is oriented with respect to the sample axis. In the aluminum alloy wire of this embodiment, the area ratio of the region where the angle formed by the longitudinal direction of the wire and the <111> direction of the crystal is within 20 ° is more than 65%. By using such a recrystallized texture, high tensile strength and excellent vibration resistance can be realized. In the study by the present inventors, the ease of cross-sliding has an influence on the vibration resistance, and the angle between the longitudinal direction of the wire and the <111> direction of the crystal, which is difficult to cross-slip, is within 20 °. It has been found that it is better to have many areas that are. Here, “intersection slip” refers to a slip that changes from one slip surface to another. Here, when the area ratio of the region where the angle formed by the longitudinal direction of the wire and the <111> direction of the crystal is within 20 ° is 65% or less, the tensile strength is lowered and the vibration resistance is also inferior.

  FIG. 1 is a schematic diagram for explaining an angle formed by a longitudinal direction of an aluminum alloy wire and a <111> direction of a crystal. As shown in FIG. 1, the angle 13 formed by the longitudinal direction 11 of the aluminum alloy wire 15 and the <111> direction 12 of the crystal 14 is the angle formed by the longitudinal direction of the wire and the <111> direction of the crystal in this embodiment. It is. In addition, since the wire rod of this embodiment is an alloy mainly composed of aluminum whose crystal structure is a face-centered cubic structure, a cubic crystal was considered.

  Further, the region where the angle formed by the longitudinal direction of the wire and the <111> direction of the crystal is within 20 ° is expressed in a specific crystal direction, in addition to the <111> direction, the <121> direction, <122 > Includes a crystal whose direction is oriented in the longitudinal direction.

(3) Precipitation structure in aluminum alloy wire In addition to the limitations on the chemical composition and the crystal orientation, the present invention further includes Mg—having a diameter of 0.5 to 5 μm in terms of equivalent circle diameter, which is present in the aluminum alloy wire. The dispersion density of the Si-based compound needs to be 3 × 10 ⁻³ pieces / μm ² or less. When Mg-Si compound having a diameter of 0.5 to 5 μm in terms of equivalent circle diameter is present in the aluminum alloy wire more than the dispersion density of 3 × 10 ⁻³ / μm ² , Mg or Si dissolves in the aluminum. In addition to not being able to fully exhibit the effect of solid solution strengthening strengthened by aging, an aggregate or precipitation of Mg, Si, etc. of a size effective for precipitation strengthening cannot be obtained sufficiently by subsequent aging heat treatment, and tensile strength and resistance Reduces vibration. Therefore, the dispersion density of the Mg—Si compound having a diameter of 0.5 to 5 μm in terms of equivalent circle diameter present in the aluminum alloy wire is 3 × 10 ⁻³ pieces / μm ² or less, preferably 1.5 × 10. ⁻³ / μm ² or less. The “diameter in terms of equivalent circle diameter” means the diameter of the perfect circle when a perfect circle having the same area as the actual area of the target Mg—Si compound is considered.

  Moreover, in this embodiment, it is preferable that the thickness of the oxide layer which exists in the surface layer of an aluminum wire is 100 nm or less. The oxide layer is mainly formed of an Mg oxide layer. If the thickness of the oxide layer exceeds 100 nm, the amount of Mg solid solution dissolved in aluminum tends to decrease, and the tensile strength tends to decrease. In addition, the oxide layer present in the surface layer becomes the starting point of breakage, and the tensile strength tends to decrease similarly. Therefore, the thickness of the oxide layer present in the surface layer of the aluminum alloy wire is preferably 100 nm or less, more preferably 80 nm or less.

  Obtaining such an aluminum alloy wire can be realized by controlling the manufacturing conditions of the aluminum alloy wire as follows. Hereinafter, the suitable manufacturing method of the aluminum alloy wire of this embodiment is demonstrated.

(Production method of actual aluminum alloy wire)
The aluminum alloy wire of the present invention forms a rough drawn wire through hot working after melting and casting, and then performs at least one crystal orientation forming treatment during wire drawing, then solution treatment and A method for producing an aluminum alloy wire comprising sequentially performing each step of an aging heat treatment, wherein the crystal orientation forming treatment is produced by a production method performed by heating to a predetermined temperature within a range of 150 ° C. or more and less than 250 ° C. be able to.

  Specific examples of the method for producing an aluminum alloy wire of the present embodiment include [1] melting, [2] casting, [3] hot working (groove roll machining, etc.), [4] first wire drawing. , [5] First heat treatment (crystal orientation formation treatment), [6] Second wire drawing, [7] Second heat treatment (solution heat treatment), and [8] Third heat treatment (aging heat treatment). The manufacturing method including performing sequentially is mentioned. Note that a step of forming a stranded wire or a step of coating a wire with a resin may be provided before or after solution heat treatment or after aging heat treatment. Hereinafter, the steps [1] to [8] will be described.

[1] Melting Melting is performed by adjusting the amount of each component so that the above-described aluminum alloy composition is obtained.

[2] Casting and [3] Hot working (groove roll processing, etc.)
Next, using a Properti-type continuous casting and rolling machine in which a cast wheel and a belt are combined, the molten metal is cast with a water-cooled mold and continuously rolled. For example, a rod having an appropriate thickness of 5 to 13 mmφ in diameter and To do. The cooling rate during casting at this time is preferably 1 to 20 ° C./s from the viewpoint of preventing coarsening of the Fe-based crystallized product and preventing decrease in conductivity due to forced dissolution of Fe. It is not limited. Casting and hot rolling may be performed by billet casting or extrusion.

[4] First wire drawing Next, for example, a rod having an appropriate thickness of 5 to 12.5 mmφ in diameter is used, and this is cold drawn. The surface may be peeled before the wire drawing process to clean the surface, but this need not be done.

[5] First heat treatment (crystal orientation forming process)
A crystal orientation forming process is applied to the cold-drawn workpiece. Conventionally, the intermediate heat treatment described above has been performed at this stage, but this is an intermediate process of wire drawing as a heat treatment for recrystallization and softening in order to regain the flexibility of the work material hardened by wire drawing. It was to be implemented. On the other hand, the crystal orientation forming process of the present invention is performed based on a completely different concept from the conventional intermediate heat treatment, and means a process for forming a desired crystal orientation. Area ratio of the region where the angle between the longitudinal direction of the aluminum alloy wire and the <111> direction of the crystal is less than 20 °, which is often obtained by wire drawing when the cold drawn wire is subjected to intermediate heat treatment And the tendency is maintained in the subsequent solution heat treatment step, and the area ratio of the region where the angle between the longitudinal direction of the wire and the <111> direction of the crystal is within 20 ° is reduced. , Vibration resistance tends to be low. However, also in the present invention, it is necessary to remove strain so as not to cause disconnection due to the processing limit in the subsequent wire drawing, and by using the recovery phenomenon, a condition was found in which the wire is not disconnected in the subsequent wire drawing process. . Specifically, the crystal orientation forming treatment is a heat treatment for heating to a predetermined temperature within a range of 150 ° C. or higher and lower than 250 ° C. When the predetermined temperature at the time of heating in the crystal orientation forming process is 250 ° C. or higher, recrystallization proceeds in the same manner as in the conventional heat treatment, and the angle formed between the longitudinal direction of the wire and the <111> direction of the crystal is within 20 °. If the area ratio of a certain region is reduced, vibration resistance is lowered, and if the predetermined temperature is lower than 150 ° C., there is a possibility that disconnection may occur in the subsequent wire drawing process without recovery. When the heating temperature is lower than 300 ° C., the compound particles do not grow so much and the suppression of crystal grain growth tends to be insufficient in the solution heat treatment. In the present invention, the solution heat treatment is performed at 500 ° C. If carried out in the temperature range of less than 580 ° C., coarse crystal grain growth can be suppressed, and both high tensile strength and excellent vibration resistance can be satisfied.

  As a method for performing the crystal orientation forming treatment, for example, batch heat treatment or continuous heat treatment such as high-frequency heating, energization heating, or running heat may be used.

  When high-frequency heating or current heating is used, the wire temperature usually rises with the passage of time because the current is normally kept flowing through the wire. For this reason, if the current is kept flowing, the wire may be melted. Therefore, it is necessary to perform heat treatment in an appropriate time range. Even when running heating is used, since the annealing is performed for a short time, the temperature of the running annealing furnace is usually set higher than the wire temperature. Since heat treatment for a long time may cause the wire to melt, it is necessary to perform the heat treatment in an appropriate time range. Hereinafter, heat treatment by each method will be described.

  The continuous heat treatment by high-frequency heating is a heat treatment by Joule heat generated from the wire itself by an induced current as the wire continuously passes through a magnetic field by high frequency. It includes a rapid heating and rapid cooling process, and the wire can be heat-treated under control of the wire temperature and heat treatment time. Cooling is performed by passing the wire continuously in water or in a nitrogen gas atmosphere after rapid heating. The heat treatment time is preferably 0.01 to 2 s, more preferably 0.05 to 1 s, and even more preferably 0.05 to 0.5 s.

  The continuous energization heat treatment is a heat treatment by Joule heat generated from the wire itself by passing an electric current through the wire passing continuously through the two electrode wheels. It includes a rapid heating and rapid cooling process, and the wire can be heat-treated under control of the wire temperature and heat treatment time. Cooling is performed by passing the wire continuously through water, air, or a nitrogen gas atmosphere after rapid heating. The heat treatment time is preferably 0.01 to 2 s, more preferably 0.05 to 1 s, and even more preferably 0.05 to 0.5 s.

  The continuous running heat treatment is a heat treatment in which a wire continuously passes through a heat treatment furnace maintained at a high temperature. Heat treatment can be performed by controlling the temperature in the heat treatment furnace and the heat treatment time, including rapid heating and rapid cooling processes. Cooling is performed by passing the wire continuously through water, air, or a nitrogen gas atmosphere after rapid heating. This heat treatment time is preferably 0.5 to 120 s, more preferably 0.5 to 60 s, and even more preferably 0.5 to 20 s.

  The batch heat treatment is a method in which a wire is put into an annealing furnace and heat treated at a predetermined set temperature and set time. The wire itself may be heated for several tens of seconds at a predetermined temperature. However, since a large amount of wire is used for industrial use, the wire is kept at the predetermined temperature for 10 minutes or more to suppress heat treatment unevenness of the wire. It is preferable to hold it. The heat treatment time is preferably 5 hours or less, more preferably 3 hours or less from the viewpoint of productivity.

  When one or both of the wire temperature and the heat treatment time are lower than the conditions defined above, there is a possibility that disconnection may occur in the subsequent wire drawing step. When the wire temperature is higher than the conditions defined above, recrystallization proceeds in the same manner as in the conventional heat treatment, and the area of the region where the angle between the longitudinal direction of the wire and the <111> direction of the crystal is within 20 ° The rate decreases and the vibration resistance decreases. For this reason, heating in the crystal orientation forming process is performed within a range of 150 ° C. or higher and lower than 250 ° C.

[6] Second wire drawing After the crystal orientation forming process, the wire drawing is further performed cold.

[7] Second heat treatment (solution heat treatment)
Solution heat treatment is performed on the cold-drawn workpiece. The solution heat treatment is a step in which compounds such as Mg and Si are dissolved in aluminum. The solution heat treatment may be performed by batch annealing as in the crystal orientation forming process, or may be performed by continuous annealing such as high-frequency heating, energization heating, and running heat. However, heat treatment within 1 hour is preferable so that oxidation on the surface of the aluminum wire does not proceed so much.

The heating temperature of the solution heat treatment is preferably 500 ° C. or higher and lower than 580 ° C. When the heating temperature of the solution heat treatment is less than 500 ° C., solutionization is incomplete and the dispersion density of the Mg—Si compound having a diameter of 0.5 to 5 μm in terms of equivalent circle diameter existing in the aluminum wire is 3 × 10. ⁻³ pieces / μm ² or less, and not only can not sufficiently exhibit the effect of solid solution strengthening, but a sufficient amount of aggregates or precipitates of Mg, Si, etc. of a size effective for precipitation strengthening can be obtained in the subsequent aging heat treatment. The tensile strength and vibration resistance are reduced. Moreover, when the heating temperature is 580 ° C. or more, coarse crystal grains are formed, and the tensile strength and vibration resistance are inferior. Furthermore, the heating temperature of the solution heat treatment is more preferably 500 to 560 ° C.

The cooling in the solution heat treatment is preferably performed at an average cooling rate of 10 ° C./s or more up to a temperature of at least 200 ° C. When the average cooling rate is less than 10 ° C./s, precipitates such as Mg ₂ Si such as Mg ₂ Si are generated during cooling, and the effect of improving the tensile strength in the subsequent aging heat treatment step is limited. This is because sufficient tensile strength tends not to be obtained. In addition, the said average cooling rate becomes like this. More preferably, it is 15 degrees C / s or more, More preferably, it is 20 degrees C / s or more.

  Further, when cooling in solution heat treatment is performed at an average cooling rate of 10 ° C./s or higher up to a temperature of at least 250 ° C., the effect of improving tensile strength in the subsequent aging heat treatment step by suppressing precipitation of Mg and Si is exhibited. Preferred above. Since the peak of the precipitation temperature zone of Mg and Si is located at 250 to 400 ° C., in order to suppress the precipitation of Mg and Si during cooling, it is preferable to increase the cooling rate at least at the temperature.

  The temperature increase rate from room temperature (20 ° C.) to 500 ° C. in the solution heat treatment is preferably 500 ° C./second or less. When the rate of temperature rise exceeds 500 ° C./second, the area ratio of the region where the angle formed by the longitudinal direction of the wire and the <111> direction of the crystal is within 20 ° decreases, and the bending fatigue resistance and vibration resistance are reduced. It tends to decrease. The temperature increase rate is preferably 100 ° C./hour or more in order to maintain high productivity.

[8] Third heat treatment (aging heat treatment)
Next, an aging heat treatment is performed. The aging heat treatment is performed in order to make an aggregate or precipitate of Mg and Si appear. The heating temperature in the aging heat treatment is preferably 100 to 250 ° C. If the heating temperature is less than 100 ° C., Mg and Si aggregates or precipitates cannot sufficiently appear, and the tensile strength and conductivity tend to be insufficient. Further, when the heating temperature is higher than 250 ° C., the size of Mg and Si precipitates increases, so that the Mg—Si system having a diameter of 0.5 to 5 μm in terms of equivalent circle diameter existing in the aluminum alloy wire Although the dispersion density of the compound is higher than 3 × 10 ⁻³ / μm ² and aggregates or precipitates such as Mg and Si effective for precipitation strengthening cannot be obtained sufficiently, the conductivity increases. Tensile strength and vibration resistance tend to decrease. For this reason, the heating temperature in the aging heat treatment is preferably 100 to 250 ° C, more preferably 100 to 200 ° C. The heating time varies depending on the temperature. Heating at a low temperature for a long time and heating at a high temperature for a short time is preferable for improving the tensile strength. Considering productivity, the short time is good, preferably 15 hours or shorter, more preferably 10 hours or shorter. The cooling in the aging heat treatment is preferably as fast as possible in order to prevent variations in characteristics. However, when cooling cannot be performed quickly in the manufacturing process, the aging conditions can be appropriately set taking into consideration that the amount of Mg and Si precipitates changes during cooling.

  In the aluminum alloy wire of this embodiment, the wire diameter is not particularly limited and can be appropriately determined according to the application, but in the case of a thin wire, 0.10 to 0.50 mmφ, in the case of a medium thin wire 0.50 to 1.5 mmφ is preferable. The aluminum alloy wire of this embodiment is one of the advantages that it can be used as an aluminum alloy wire by thinning it with a single wire, but it can also be used as an aluminum alloy twisted wire obtained by bundling a plurality of wires, Among the steps [1] to [8] constituting the manufacturing method of the present embodiment described above, a plurality of aluminum alloy wires obtained by sequentially performing the steps [1] to [6] are bundled and twisted together. Later, [7] second heat treatment (solution heat treatment) and [8] third heat treatment (aging heat treatment) may be performed.

  Moreover, in this embodiment, it is also possible to perform the homogenization heat processing which is performed by the conventional method after continuous casting rolling as an additional process. The homogenization heat treatment can uniformly disperse the precipitates of the additive elements (mainly Mg-Si compounds), so that it becomes easier to obtain a uniform crystal structure in the subsequent crystal orientation formation treatment, resulting in a tensile strength. The bendability can be obtained more stably. The homogenization heat treatment is preferably performed at a heating temperature of 450 ° C. to 600 ° C. and a heating time of 1 to 10 hours, and more preferably 500 to 600 ° C. Moreover, it is preferable that the cooling in the homogenization heat treatment is performed gradually at an average cooling rate of 0.1 to 10 ° C./min in that a uniform compound can be easily obtained.

  The aluminum alloy wire of the present embodiment can be used as an aluminum alloy wire or an aluminum alloy stranded wire obtained by twisting a plurality of aluminum alloy wires, and further an aluminum alloy wire or an aluminum alloy stranded wire. It can also be used as a covered electric wire having a coating layer on the outer periphery, and in addition, it is used as a wire harness (assembled electric wire) comprising a covered electric wire and a terminal attached to the end of the covered electric wire from which the coating layer has been removed. It is also possible to do. In addition, the aluminum alloy wire according to the present embodiment is preferably configured such that the number of repeated fractures when performing a double-bending bending fatigue test with a strain amplitude of ± 0.09% is 2 million times or more.

  The present invention will be described in detail based on the following examples. In addition, this invention is not limited to the Example shown below.

(Examples and comparative examples)
Content shown in Table 1 for Mg, Si, Fe and Al, and Ti, B, Cu, Ag, Au, Mn, Cr, Zr, Hf, V, Sc, Sn, Co, and Ni that are selectively added ( The molten metal was prepared using a Properti-type continuous casting and rolling machine so that the mass was (mass%), and rolled while continuously casting with a water-cooled mold to obtain a bar of about 9.5 mmφ. The cooling rate during casting at this time was about 15 ° C./s. Next, the first wire drawing was performed, the first heat treatment (crystal orientation forming treatment) was performed under the conditions shown in Table 2, and the second wire drawing was further performed to a wire diameter of 0.31 mmφ. Next, a second heat treatment (solution heat treatment) was performed under the conditions shown in Table 2. In both the first heat treatment and the second heat treatment, the wire temperature was measured by winding a thermocouple around the wire in the batch heat treatment. In continuous energization heat treatment, it is difficult to measure at the part where the temperature of the wire becomes the highest, so the fiber type radiation thermometer (manufactured by Japan Sensor Co., Ltd.) is in front of the part where the temperature of the wire becomes the highest. The temperature was measured, and the maximum temperature reached was calculated in consideration of Joule heat and heat dissipation. In the high frequency heating and continuous running heat treatment, the wire temperature near the exit of the heat treatment section was measured. After the solution heat treatment, a third heat treatment (aging heat treatment) was performed under the conditions shown in Table 2 to produce an aluminum alloy wire.

  Each characteristic was measured and evaluated by the method shown below about the produced aluminum alloy wire of each Example and a comparative example.

(A) Measurement of area ratio of region where angle formed between longitudinal direction of wire and <111> direction of crystal is within 20 ° For analysis of crystal orientation in this example, electron beam backscatter diffraction (EBSD) method Was used. In the cross section perpendicular to the longitudinal direction of the wire, the crystal orientation was observed mainly for the sample area with a diameter of about 310 μm. The scan step was set to about 1/10 of the average crystal grain size of the sample. The area ratio (%) of the region where the angle between the longitudinal direction of the wire and the <111> direction of the crystal is within 20 ° is (the angle between the longitudinal direction of the wire and the <111> direction of the crystal is within 20 °. Area / sample measurement area) × 100.

(B) Measurement of dispersion density of Mg-Si compound The arbitrary range was observed for the wire of the Example and the comparative example using the transmission electron microscope (TEM). The Mg—Si compound was subjected to composition analysis by EDX (Energy dispersive X-ray spectrometry) to identify the compound species. As the analyzer, JEM-3010 (manufactured by JEOL Ltd.) and JED-2300 (T) (manufactured by JEOL Ltd.) were used. The cross-sectional area of the observed Mg—Si compound was determined and converted into an equivalent circle diameter, and an Mg—Si compound having a diameter of 0.5 to 5 μm was observed. The dispersion density of the Mg—Si compound is set within a range where 10 or more can be counted, and the dispersion density of the Mg—Si compound (pieces / μm ² ) = the number of Mg—Si compounds (pieces) / the target range of counting. It calculated using the formula of (micrometer < ² >). In some cases, a plurality of photographs were used as the count target range. When the number of compounds was so small that 10 or more could not be counted, 1000 μm ² was specified and the dispersion density in that range was calculated.

(C) Measurement of tensile strength (TS) A tensile test was performed on three specimens (aluminum alloy wires) in accordance with JIS Z 2241, and the average value was obtained. As in the past, high tensile strength is required in order to enable use without breaking even when applied to a thin wire having a small cross-sectional area.

(D) Evaluation of bending fatigue resistance (number of repeated fractures) As a standard for bending fatigue resistance, the strain amplitude at room temperature was set to ± 0.17%. Bending fatigue resistance varies with strain amplitude. In general, the greater the strain amplitude, the shorter the fatigue life, and the smaller the strain amplitude, the longer the fatigue life. Since the strain amplitude can be determined by the wire diameter of the wire 1 shown in FIG. 2 and the curvature radii of the bending jigs 2 and 3, the wire diameter of the wire 1 and the curvature radii of the bending jigs 2 and 3 are arbitrarily set. It is possible to conduct a bending fatigue test. In this example, by using a double-bending bending fatigue testing machine manufactured by Fujii Seiki Co., Ltd. (currently Fujii Co., Ltd.) and using a jig that gives a bending strain of 0.17%, The number of repeated breaks was measured. The number of repeated ruptures was measured four by four and the average value was determined. As shown in the explanatory view of FIG. 2, the wire 1 was inserted with a space of 1 mm between the bending jigs 2 and 3, and repeatedly moved in such a manner as to be along the jigs 2 and 3. One end of the wire was fixed to a holding jig 5 so that it could be bent repeatedly, and a weight 4 of about 10 g was hung from the other end. Since the holding jig 5 moves during the test, the wire 1 fixed to the holding jig 5 also moves and can be bent repeatedly. The repetition is performed under the condition of 100 times per minute, and when the wire specimen 1 breaks, the weight 4 falls and stops counting. The number of repeated breaks was 200,000 times or more. Preferably it is 400,000 times or more, More preferably, it is 800,000 times or more.

(E) Evaluation of vibration resistance As in the case of (D) above, using the double-bend bending fatigue tester shown in FIG. The test was conducted at 0.09%. For those in which the number of repetitions until the aluminum wire broke was 2 million times or more, it was described as “◯” in Table 3 and passed. About what was disconnected when the number of repetitions was less than 2 million times, it was described as “x” in Table 3 and was rejected. Since the test took a relatively long time, the test was terminated at any point exceeding 2 million times.

(F) Measurement of thickness of oxide layer present on surface layer of aluminum alloy wire The thickness measurement of the oxide layer present on the surface layer of the aluminum wire was performed using an Auger electron spectrometer. Specifically, elemental analysis was performed while irradiating a surface layer of 25 μm × 25 μm of the prepared aluminum alloy wire with argon ions. Elemental analysis in the depth direction is possible, and the point in time when the oxygen concentration became half of the peak time was calculated as the thickness of the oxide layer from the obtained element concentration profile. (SiO ₂ conversion value) Measurement was carried out with n = 2, and the average thickness of the oxide layer with n = 2 was defined as the thickness of the oxide layer present on the surface layer of the aluminum alloy wire.

  Table 3 shows the results of measurement and evaluation of the examples and comparative examples by the above methods.

  From the results of Table 3, in the aluminum alloy wires of Examples 1 to 12, the area ratio of the region where the angle formed by the longitudinal direction of the wire and the <111> direction of the crystal is within 20 ° is within the range of the present invention. Therefore, it was excellent in both tensile strength and vibration resistance. On the other hand, in Comparative Examples 1 to 10 (excluding Comparative Example 2), the area ratio of the region where the angle formed by the longitudinal direction of the wire and the <111> direction of the crystal is within 20 ° is outside the scope of the present invention. Therefore, the vibration resistance is inferior, and among these comparative examples, Comparative Examples 1, 3 to 5 and 9 have low tensile strength, and Comparative Examples 1 to 3 have inferior bending fatigue resistance. . In Comparative Example 2, since the dispersion density of the Mg—Si compound was outside the range of the present invention, the tensile strength was low, and the bending fatigue resistance and vibration resistance were inferior.

  According to the present invention, with the above configuration, an aluminum alloy wire, an aluminum alloy twisted wire, which can be used for a thin wire with high strength, can be used for engine vibration that is constantly generated, and is used as an electric wiring body that is difficult to break. It becomes possible to provide the manufacturing method of a covered electric wire and a wire harness, and an aluminum alloy wire. The present invention is particularly useful as a battery cable mounted on a moving body, a harness or a conductor for a motor, and a wiring body for an industrial robot. Furthermore, since the aluminum alloy wire of the present invention has excellent bending fatigue resistance, which has been conventionally required, it can also be used in bent parts such as doors and has higher tensile strength. The diameter can also be reduced, and it can also be suitably used in the vicinity of an engine portion where high vibration resistance is required.

1 Test piece (wire)
2, 3 Bending jig 4 Weight 5 Holding jig 11 Longitudinal direction of wire 12 <111> direction of crystal 13 Angle formed by longitudinal direction of wire and <111> direction of crystal 14 Crystal 15 Aluminum alloy wire

Claims (10)

An aluminum alloy wire,
Mg: 0.10 to 1.00 mass%, Si: 0.10 to 1.00 mass%, Fe: 0.01 to 1.40 mass%, Ti: 0 to 0.100 mass%, B: 0 to 0.030 mass%, Cu: 0 to 1.00 mass%, Ag: 0 to 0.50 mass%, Au: 0 to 0.50 mass%, Mn: 0 to 1.00 mass%, Cr: 0 to 0 1.00 mass%, Zr: 0 to 0.50 mass%, Hf: 0 to 0.50 mass%, V: 0 to 0.50 mass%, Sc: 0 to 0.50 mass%, Sn: 0 to 0 0.50% by mass, Co: 0 to 0.50% by mass, Ni: 0 to 0.50% by mass, balance: Al and inevitable impurities,
The area ratio of the region where the angle formed by the longitudinal direction of the aluminum alloy wire and the <111> direction of the crystal is within 20 ° is more than 65%, and is present in the aluminum alloy wire in terms of equivalent circle diameter. An aluminum alloy wire, wherein a dispersion density of Mg-Si compounds having a diameter of 0.5 to 5.0 μm is 3 × 10 ⁻³ pieces / μm ² or less.   The said chemical composition contains 1 type or 2 types selected from the group which consists of Ti: 0.001-0.100 mass% and B: 0.001-0.030 mass%. Aluminum alloy wire.   The chemical composition is Cu: 0.01 to 1.00% by mass, Ag: 0.01 to 0.50% by mass, Au: 0.01 to 0.50% by mass, Mn: 0.01 to 1.00. % By mass, Cr: 0.01 to 1.00% by mass, Zr: 0.01 to 0.50% by mass, Hf: 0.01 to 0.50% by mass, V: 0.01 to 0.50% by mass , Sc: 0.01 to 0.50 mass%, Sn: 0.01 to 0.50 mass%, Co: 0.01 to 0.50 mass% and Ni: 0.01 to 0.50 mass% The aluminum alloy wire according to claim 1 or 2, comprising one or more selected from the group.   The aluminum alloy wire according to claim 1, 2, or 3, wherein the number of repeated fractures when the double-bending fatigue test is performed with a strain amplitude of ± 0.09% is 2 million times or more.   The aluminum alloy wire according to any one of claims 1 to 4, wherein the thickness of the oxide layer present in the surface layer is 100 nm or less.   The aluminum alloy wire according to any one of claims 1 to 5, wherein the diameter is 0.10 to 0.50 mm.   An aluminum alloy twisted wire obtained by twisting a plurality of the aluminum alloy wires according to any one of claims 1 to 6.   The covered electric wire which has a coating layer in the outer periphery of the aluminum alloy wire of any one of Claims 1-6, or the aluminum alloy twisted wire of Claim 7.   A wire harness comprising: the covered electric wire according to claim 8; and a terminal attached to an end of the covered electric wire from which the covering layer is removed.   After melting and casting, a rough drawn wire is formed through hot working, and then at least one crystal orientation forming treatment is performed while drawing, and then each step of solution treatment and aging heat treatment is sequentially performed. The aluminum alloy wire according to any one of claims 1 to 6, wherein the crystal orientation forming treatment is heated to a predetermined temperature within a range of 150 ° C or higher and lower than 250 ° C. A manufacturing method of a wire.

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