JP2013044038A - Aluminum alloy conductor - Google Patents

Abstract

An aluminum alloy conductor having sufficient conductivity and tensile strength and excellent in bending fatigue resistance is provided.
SOLUTION: Fe is contained in an amount of 0.01 to 1.5 mass%, Mg is contained in an amount of 0.01 to 1.2 mass%, and Si is contained in an amount of 0.01 to 1.2 mass%. An aluminum alloy wire having an alloy composition made of impurities, having a dispersion density of Mg ₂ Si needle-like precipitates of 10 to 200 / μm ² , a tensile strength of less than 240 MPa, and a tensile breaking elongation of 10% or more.
[Selection figure] None

Description

  The present invention relates to an aluminum alloy conductor used as a conductor of an electric wiring body.

2. Description of the Related Art Conventionally, a member in which a terminal (connector) made of copper or copper alloy (for example, brass) is attached to an electric wire including a copper or copper alloy conductor called a wire harness as an electric wiring body of a moving body such as an automobile, a train, and an aircraft Was used. On the other hand, studies have been made on the use of aluminum or aluminum alloys that are lighter than copper or copper alloys as conductors of electrical wiring bodies in recent years with the reduction in weight of moving bodies.
The specific gravity of aluminum is about 1/3 of copper, and the electrical conductivity of aluminum is about 2/3 of copper (pure aluminum is about 66% IACS when pure copper is used as the standard of 100% IACS). In order to pass the same current as that of a pure copper conductor wire, the cross-sectional area of the pure aluminum conductor wire needs to be about 1.5 times that of the pure copper conductor wire, but the mass is still about half that of copper. Therefore, there is an advantage.
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.

There are some problems in using the aluminum as a conductor of the electric wiring body of the moving body. One of them is improvement of bending fatigue resistance. This is because a wire harness attached to a door or the like is repeatedly subjected to bending stress by opening and closing the door. When a metal material such as aluminum is repeatedly applied and removed as when the door is opened and closed, it breaks at a certain number of repetitions (fatigue failure) even at a low load that does not break at a single load. When the aluminum conductor is used for an opening / closing part, if the bending fatigue resistance is poor, there is a concern that the conductor breaks during use, and durability and reliability are lacking.
Generally, it is said that a material having higher strength has better fatigue characteristics. Therefore, high-strength aluminum wire may be applied, but the wire harness is required to be easy to handle (installation work on the vehicle body) at the time of installation, so generally the elongation is 10% or more. In many cases, a dull material (annealed material) that can be secured is used.

  Therefore, the aluminum conductor used for the electric wiring body of the moving body has excellent bending fatigue resistance in addition to the tensile strength required at the time of handling and mounting, and the conductivity required to flow a large amount of electricity. There is a need for materials.

  For such demanding applications, pure aluminum systems such as power transmission line aluminum alloy wires (JIS A1060 and JIS A1070) cannot sufficiently withstand repeated bending stresses that occur when doors are opened and closed. Moreover, although the material alloyed by adding various additive elements is excellent in strength, it causes a decrease in conductivity due to a solid solution phenomenon of the additive element in aluminum, and forms an excessive intermetallic compound in aluminum. As a result, disconnection due to the intermetallic compound may occur during wire drawing. For this reason, it is essential to limit and select the additive element and not to disconnect, to prevent a decrease in conductivity, and to improve strength and bending fatigue resistance.

  A typical example of an aluminum conductor used for an electric wiring body of a moving body is that described in Patent Document 1. This realizes necessary tensile strength, elongation at break, impact resistance, and the like using a wire conductor formed by twisting a plurality of thin aluminum alloy wires. However, the aluminum conductor of the invention described in Patent Document 1 requires twisting of the strands, the strength is too high, the handling is difficult, and an aluminum alloy conductor that can be handled without applying excessive force It is desired.

JP 2008-112620 A

  An object of the present invention is to provide an aluminum alloy conductor having sufficient electrical conductivity and tensile strength and excellent in bending fatigue resistance.

The inventors have made various studies and controlled Mg ₂ Si needle-like precipitates by controlling production conditions such as component composition and aging heat treatment, and have excellent bending fatigue resistance, strength, and conductivity. The present inventors have found that an aluminum alloy conductor can be manufactured, and have completed the present invention based on this finding.

That is, the said subject was achieved by the following invention.
(1) Fe contains 0.01 to 1.5 mass%, Mg contains 0.01 to 1.2 mass%, and Si contains 0.01 to 1.2 mass%, with the balance being substantially Al and inevitable impurities. An aluminum alloy wire having an alloy composition of Mg ₂ Si needle-like precipitates having a dispersion density of 10 to 200 / μm ² , a tensile strength of less than 240 MPa, and a tensile elongation at break of 10% or more.
(2) The alloy composition contains 0.01 to 1.0 mass% of Cu, and the aluminum alloy wire according to item (1).
(3) The aluminum alloy wire according to any one of (1) and (2), which is produced by subjecting an aluminum alloy material having the above alloy composition to an aging heat treatment at 120 to 250 ° C.
(4) The aging heat treatment is performed after the solution treatment, and the aluminum alloy wire according to (3) (5) used as a battery cable, harness, or motor lead in a moving body The aluminum alloy conductor according to any one of (1) to (4).
(6) The aluminum alloy conductor according to (5), wherein the moving body is an automobile, a train, or an aircraft.
(7) Fe contains 0.01 to 1.5 mass%, Mg contains 0.01 to 1.2 mass%, and Si contains 0.01 to 1.2 mass%, with the balance being substantially Al and inevitable impurities. A wire-drawn processed material having an alloy composition comprising: solution heat treatment, aging heat treatment at 120 to 250 ° C., Mg ₂ Si needle-like precipitates having a dispersion density of 10 to 200 pieces / μm ² , and tensile strength A method for producing an aluminum alloy wire satisfying less than 240 MPa and having a tensile elongation at break of 10% or more.
(8) The method for producing an aluminum alloy wire according to (7), wherein the solution heat treatment is a continuous energization heat treatment and satisfies the following formula.
0.03 ≦ x ≦ 0.73 and 22x ^−0.4 + 500 ≦ y ≦ 18x ^−0.4 +560
(In the formula, x represents the annealing time (seconds), and y represents the wire temperature (° C.).)
(9) The method for producing an aluminum alloy wire according to (7), wherein the solution heat treatment is a continuous running heat treatment and satisfies the following formula.
1.5 ≦ x ≦ 5 and −8.5x + 612 ≦ z ≦ −8.5x + 667
(In the formula, x represents annealing time (seconds), and z represents annealing furnace temperature (° C.).)
(10) The method for producing an aluminum alloy wire according to (7), wherein the solution heat treatment is a batch heat treatment and is performed so as to satisfy a temperature of 500 to 580 ° C. and a time of 30 minutes to 6 hours.
In the present invention, the alloy composition in which the balance is substantially made of Al and inevitable impurities includes an alloy composition in which the balance is made of Al and inevitable impurities and does not contain other additive components.

  The aluminum alloy conductor of the present invention is excellent in strength and electrical conductivity, and is useful as a battery cable, a harness or a motor lead wire mounted on a moving body. It can also be suitably used for doors, trunks, bonnets and the like that require extremely high bending fatigue resistance.

It is explanatory drawing of the test which measures the frequency | count of repeated fracture | rupture performed in the Example.

The conductor of the aluminum alloy wire of the present invention has excellent bending fatigue resistance, strength, elongation, and electrical conductivity by defining the compositional component of the aluminum alloy and the Mg ₂ Si needle precipitate as follows. Can be.

(Alloy composition and properties)
The component constitution of the first preferred embodiment of the present invention is that Al is 0.01 to 1.5 mass% Fe, 0.01 to 1.2 mass% Mg, 0.01 to 1.2 mass Si. %.

  In this embodiment, the Fe content is set to 0.01 to 1.5 mass%. Fe is mainly added in order to use various effects due to the formation of Al—Fe-based intermetallic compounds. Fe dissolves only 0.05 mass% in aluminum at 655 ° C., and is even less at room temperature. The remainder crystallizes or precipitates as an intermetallic compound such as Al-Fe, Al-Fe-Si, Al-Fe-Si-Mg. This crystallized product or precipitate acts as a crystal grain refining material and improves strength and bending fatigue resistance. On the other hand, the strength also increases due to the solid solution of Fe. If the Fe content is too small, these effects are insufficient, and if it is too much, the crystallized material becomes coarse and the wire drawing workability is poor, and the desired bending fatigue resistance cannot be obtained. Moreover, it will be in a supersaturated solid solution state and electrical conductivity will also fall. The content of Fe is preferably 0.15 to 1.2 mass%, more preferably 0.2 to 0.4 mass%.

In this embodiment, the Mg content is 0.01 to 1.2 mass%. Mg is solid-solved and strengthened in the aluminum base material, and a part thereof can form precipitates with Si to improve strength, bending fatigue resistance, and heat resistance. If the content of Mg is too small, the above-described effects are insufficient, and if it is too large, the electrical conductivity is lowered. Moreover, when there is much content of Mg, yield strength will become excess, a moldability and twist property will deteriorate, and workability will worsen. The Mg content is preferably 0.10 to 0.90 mass%, more preferably 0.30 to 0.70 mass%.

  In this embodiment, the Si content is 0.01 to 1.2 mass%. As described above, Si forms a compound with Mg and exhibits a function of improving strength, bending fatigue resistance, and heat resistance. If the Si content is too low, the effect is insufficient, and if it is too high, the conductivity decreases. The Si content is preferably 0.10 to 0.90 mass%, more preferably 0.30 to 0.70 mass%.

In the present invention, the Al alloy composition may contain at least one selected from Cu as an optional component other than the above essential components, and the balance may be substantially composed of Al and inevitable impurities.
A preferred second embodiment of the present invention is one of the above-described embodiments, and a part of Al in the component consisting essentially of Al of the first embodiment is replaced with 0.01 to 1.0 mass% of Cu. It is further included.

In this embodiment, by setting the Cu content to 0.01 to 1.0 mass%, Cu is dissolved in the aluminum base material and strengthened. Thereby, it contributes to the improvement of creep resistance, bending fatigue resistance, and heat resistance. If the Cu content is too low, the effect is insufficient, and if it is too high, the corrosion resistance and the conductivity are lowered. The Cu content is preferably 0.10 to 0.80 mass%, more preferably 0.25 to 0.50 mass%.
The other component compositions and their actions are the same as in the first embodiment.

  Inevitable impurities are contained levels included in the manufacturing process. Inevitable impurities cause a slight decrease in electrical conductivity, but they are included in the manufacturing process, so it is necessary to consider the decrease in electrical conductivity. Inevitable impurities include Mn of 0.02% by mass or less, Ti of 0.02% by mass or less, Zr of 0.01% by mass or less, and the like. For Mn and Ti, JIS H2102 was referred.

In the present invention, the number of Mg ₂ Si needle-like precipitates generated in the aluminum alloy conductor is 10 to 200 / μm ² . The Mg ₂ Si needle-like precipitate is a compound formed by aggregation of additive elements of Mg and Si that were not completely dissolved in the aluminum alloy conductor. The formation of a crystal different from the mother crystal from a uniform crystal is called precipitation, and the compound is called a precipitate. The needle shape represents the shape of the precipitate, and refers to an elongated precipitate having a length of 40 nm to 500 nm, preferably 40 nm to 400 nm, and a maximum lateral width (thickness) of 1 nm to 20 nm. By precipitating Mg ₂ Si needle-like precipitates in the aluminum alloy conductor, it is possible to improve the bending fatigue resistance and strength, and to prevent a decrease in conductivity. When the number of Mg ₂ Si needle-like precipitates is too small, these effects are insufficient. When the number is too large, there is a possibility that elongation is reduced due to excessive precipitation or wire breakage occurs during wire drawing. The number of Mg ₂ Si needle-like precipitates is preferably 15 to 150 / μm ² , and more preferably 25 to 100 / μm ² .

  In the present invention, the tensile strength of the aluminum alloy conductor is less than 240 MPa. If the tensile strength is 240 MPa or more, when handling an aluminum alloy conductor, particularly when handling an aluminum electric wire formed by bundling a plurality of aluminum alloy conductors, a large force is required, and the handling property at the time of installation is poor. Become. The tensile strength of the aluminum alloy conductor in the present invention is preferably less than 220 MPa, and more preferably less than 200 MPa. In addition, 80 MPa or more is preferable so that it may not be cut when handling the electric wire.

  In the present invention, the elongation of the aluminum alloy conductor is 10% or more. Elongation is the tensile breaking elongation. When the elongation is less than 10%, when handling an aluminum alloy conductor, especially when handling an aluminum wire formed by bundling a plurality of aluminum alloy conductors, it can withstand bending and stretching work during wire installation work. I can't. The elongation of the aluminum alloy conductor in the present invention is preferably 12% or more, and more preferably 15% or more. The upper limit of elongation is not particularly limited, but 40% or less is preferable.

An aluminum alloy conductor having such Mg ₂ Si needle-like precipitates can be obtained by controlling the alloy composition as described above and the conditions for aging heat treatment as follows. A preferred production method is described below.

(Method for producing aluminum alloy conductor of the present invention)
The aluminum alloy conductor of the present invention includes [1] melting, [2] casting, [3] hot or cold working (groove roll processing, etc.), [4] wire drawing, [5] heat treatment (intermediate annealing), It can be manufactured through each step of [6] wire drawing, [7] heat treatment, and [8] aging heat treatment. Below, this process is demonstrated.

  Melting is performed in an amount so as to be the concentration of each embodiment of the aluminum alloy composition described above.

  Next, rolling is performed while continuously casting the molten metal in a mold cooled with water using a Properti type continuous casting rolling machine in which a casting wheel and a belt are combined. For example, a rod of about 10 mmφ is used. The casting cooling rate at this time is preferably 1 to 20 ° C./second from the viewpoint of preventing the coarsening of the Fe-based crystallized product and preventing the decrease in conductivity due to the forced solid solution of Fe, but is limited to this. It is not a thing. Casting and hot rolling may be performed by billet casting, extrusion, or the like.

Next, the surface is peeled, and a rod having an appropriate thickness of preferably 7.5 to 12.5 mmφ, for example, about 9.5 mmφ, which is drawn. The degree of processing is preferably 1 or more and 6 or less. Here working ratio eta is a wire sectional area before drawing A _0, when the wire cross-sectional area after drawing and A _1, represented by _{η = ln (A 0 / A} 1). If the degree of work at this time is too small, the recrystallized grains become coarse during the heat treatment in the next step, and the strength and elongation are remarkably lowered, which may cause disconnection. If it is too large, the wire drawing process becomes difficult, and there may be a problem in terms of quality such as disconnection during the wire drawing process. Although the surface is cleaned by carrying out the peeling of the surface, it may not be carried out.

  Intermediate annealing is applied to the cold-drawn workpiece. The intermediate annealing is performed mainly to regain the flexibility of the wire that has been hardened by wire drawing. If the intermediate annealing temperature is too high or too low, the wire is broken in the subsequent wire drawing process, and the wire cannot be obtained. The intermediate annealing temperature is preferably 300 to 450 ° C, more preferably 350 to 450 ° C. The time for the intermediate annealing is 10 minutes or more. If it is less than 10 minutes, the time required for the formation and growth of recrystallized grains is insufficient, and the flexibility of the wire cannot be recovered. Preferably it is 1 to 6 hours. The average cooling rate from the heat treatment temperature during intermediate annealing to 100 ° C. is not particularly specified, but is preferably 0.1 to 10 ° C./min.

  Further, wire drawing is performed. The degree of processing at this time is preferably 1 or more and 6 or less. The degree of work greatly affects the formation and growth of recrystallized grains. If the degree of work is too small, the recrystallized grains become coarse during the heat treatment in the next step, and the strength and elongation are significantly reduced, which may cause disconnection. If it is too large, the wire drawing process becomes difficult, and there may be a problem in terms of quality such as disconnection during the wire drawing process. The degree of processing is more preferably 2 or more and 6 or less.

  Heat treatment is performed so that the cold-drawn workpiece has an elongation of 10%. The heat treatment can be performed by either continuous heat treatment or batch heat treatment. In the continuous heat treatment, either continuous energization heat treatment or continuous feed heat treatment can be performed. The heat treatment is preferably a solution heat treatment. The solution heat treatment is a heat treatment in which a compound crystallized or precipitated in a previous stage in an aluminum alloy conductor is dissolved in the aluminum alloy conductor and the composition concentration distribution in the material is made uniform.

The continuous energization heat treatment is performed by annealing with Joule heat generated from itself by passing an electric current through a wire passing through two electrode wheels. It includes the steps of rapid heating and quenching, and the wire can be annealed by controlling the wire temperature and annealing time. Cooling is performed by passing the wire continuously in water or a nitrogen gas atmosphere after rapid heating. Usually, annealing is performed by setting an appropriate temperature in the range of 0.03 seconds to 0.73 seconds so that an elongation of 10% or more can be obtained. Preferably, in order to form a solution, in continuous energization heat treatment, if the wire temperature is y (° C.) and the annealing time is x (seconds),
0.03 ≦ x ≦ 0.73 and 22x ^−0.4 + 500 ≦ y ≦ 18x ^−0.4 +560
Heat treatment is performed to satisfy
When one or both of the wire temperature and the annealing time are lower than the conditions defined above, the solution formation is incomplete and Mg ₂ Si needle-like precipitates precipitated during the aging heat treatment in the subsequent process are reduced, and the strength, The range of improvement in bending fatigue characteristics and conductivity is reduced. However, if the dispersion density of the Mg ₂ Si needle-like precipitates is within a predetermined range, the present invention is suitable. However, when one or both of the wire temperature and the annealing time are higher than the conditions defined above, partial melting (eutectic melting) of the compound phase in the aluminum alloy conductor occurs, and the strength and elongation are reduced. Disconnection is likely to occur during handling.
The wire temperature y (° C.) represents the temperature immediately before passing through the cooling step, at which the temperature of the wire becomes the highest. y (° C.) is usually in the range of 525 to 633 (° C.).

In the continuous running heat treatment, the wire is continuously passed through an annealing furnace kept at a high temperature and annealed. It includes the steps of rapid heating and rapid cooling, and the wire can be annealed under the control of the annealing furnace temperature and annealing time. Cooling is performed by passing the wire continuously in water or a nitrogen gas atmosphere after rapid heating. Usually, annealing is performed by setting an appropriate temperature in the range of 1.5 to 5.0 seconds so that an elongation of 10% or more can be obtained. In order to preferably form a solution, in continuous running heat treatment, if the annealing furnace temperature is z (° C.) and the annealing time is x (seconds),
1.5 ≦ x ≦ 5 and −8.5x + 612 ≦ z ≦ −8.5x + 667
To meet. z (° C.) is usually in the range of 570 to 654 (° C.).
When one or both of the wire temperature and the annealing time are lower than the conditions defined above, the solution formation is incomplete and Mg ₂ Si needle-like precipitates precipitated during the aging heat treatment in the subsequent process are reduced, and the strength, The range of improvement in bending fatigue characteristics and conductivity is reduced. However, if the dispersion density of the Mg ₂ Si needle-like precipitates is within a predetermined range, the present invention is suitable. However, when one or both of the wire temperature and the annealing time are higher than the conditions defined above, partial melting (eutectic melting) of the compound phase in the aluminum alloy conductor occurs, and the strength and elongation are reduced. Disconnection is likely to occur during handling.
In addition to the above two methods, solution heat treatment may be induction heating in which a wire continuously passes through a magnetic field and is annealed.

In the case of batch heat treatment, an aluminum alloy conductor is wound around a coil or the like and held in an annealing furnace for a certain period of time. It is performed so that the temperature is 500 to 580 ° C. and the time is 30 minutes or more and 6 hours or less.
When one or both of the wire temperature and the annealing time are lower than the solution treatment conditions defined above, the solution formation is incomplete and less Mg ₂ Si needle-like precipitates are precipitated during the aging heat treatment in the subsequent process. Further, the range of improvement in bending fatigue resistance and conductivity is reduced. However, if the dispersion density of the Mg ₂ Si needle-like precipitates is within a predetermined range, the present invention is suitable. However, when one or both of the wire temperature and the annealing time are higher than the solution conditions defined above, partial melting (eutectic melting) of the compound phase in the aluminum alloy conductor occurs, and the strength and elongation decrease. Wire breakage easily occurs when handling conductors.

Next, an aging heat treatment is performed. The aging heat treatment is performed to precipitate Mg ₂ Si needle-like precipitates. The temperature is preferably 120 to 250 ° C. If it is less than 120 ° C., the Mg ₂ Si needle-like precipitates cannot be sufficiently precipitated, and if it exceeds 250 ° C., the shape of the Mg ₂ Si precipitates is not needle-like (becomes spherical). , Mg ₂ Si needle-like precipitates cannot be sufficiently precipitated. In the present invention, at least Mg ₂ Si needle-like precipitates may be deposited at the above-described density even if Mg ₂ Si of another shape coexists. The aging heat treatment temperature is preferably 140 to 230 ° C, more preferably 150 to 200 ° C. The time is not particularly limited because the optimal time varies depending on the temperature, but is preferably 1 to 15 hours, and more preferably 4 to 10 hours. Further, in order to shorten the heat treatment time and improve the productivity, for example, an aging heat treatment at a high temperature and a short time such as 200 ° C. for 1 hour may be performed.

  The wire diameter of the conductor of the aluminum alloy wire of the present invention is not particularly limited and can be appropriately determined according to the application, but is preferably 0.15 to 1.0 mmφ, more preferably 0.20 to 0.8 mmφ. . One of the advantages of the wire rod of the present invention is that it can be used as an aluminum alloy wire after being thinned with a single wire, but it can also be used by bundling a plurality of wires. [8] An aging heat treatment step may be performed.

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.

Example 1 and Comparative Example 1
Rolling is carried out while continuously casting the molten metal in a water-cooled mold using a Properti type continuous casting rolling machine so that Fe, Mg, Si, Cu, and Al are in the amounts (mass%) shown in Table 1. The bar was about 10 mmφ. The casting cooling rate at this time is 1 to 20 ° C./second.
Next, the surface was peeled to about 9.5 mmφ, and this was drawn so as to obtain a predetermined degree of processing. Next, this cold-drawn workpiece is subjected to intermediate annealing at a temperature of 300 to 450 ° C. for 0.5 to 4 hours, and further to any wire diameter of 0.43 mmφ, 0.37 mmφ, and 0.31 mmφ Drawing was performed.

  Next, heat treatment was performed under the conditions shown in Table 1. In the continuous energization heat treatment, the wire temperature y (° C.) immediately before passing through the water where the temperature of the wire becomes the highest was measured with a fiber-type radiation thermometer (manufactured by Japan Sensor). In the continuous running heat treatment, the annealing furnace temperature z (° C.) is described. In the case of batch annealing, immediately after the heat treatment, it was quickly cooled in a bucket containing water.

  Finally, an aging heat treatment was performed under conditions of a temperature of 120 to 250 ° C. and a time of 1 to 15 hours. After the aging heat treatment, the sample was taken out from the furnace and air-cooled.

  Each characteristic was measured with the method described below about the produced wire of each Example and a comparative example. The results are shown in Table 1.

(A) Dispersion density of Mg ₂ Si needle-like precipitates The wire materials of Examples and Comparative Examples were made into thin films by the FIB method, and the electron beam was <001> direction with respect to the aluminum matrix using a transmission electron microscope (TEM). An arbitrary range was observed. As for the Mg ₂ Si needle-like precipitates, the needle-like precipitates having a length of 40 nm or more as defined above from the photographed images were counted. In this way, Al-Fe-based precipitates precipitated in a spherical shape were excluded. In addition, needle-like precipitates deposited perpendicularly to the photographed photographs were not counted. When the precipitate straddled out of the measurement range, if the length of 40 nm or more was included in the measurement range, the number of precipitates was counted. The dispersion density of Mg ₂ Si needle-like precipitates is set within a range in which 40 or more can be counted, and the dispersion density of Mg ₂ Si needle-like precipitates (pieces / μm ² ) = the number of Mg ₂ Si needle-like precipitates ( It calculated using the formula of (piece) / count object range (μm ² ). In some cases, a plurality of photographs were used as the count target range. When there were so few precipitates that it could not count 40 or more, 1 micrometer ² was specified and the dispersion density of the range was computed.
The dispersion density of the Mg ₂ Si needle-like precipitates is calculated with the sample thickness of the thin film as a reference thickness of 0.15 μm. If the sample thickness is different from the reference thickness, the sample thickness is converted into the reference thickness, that is, (reference thickness / sample thickness) is applied to the dispersion density calculated based on the photographed photo, Dispersion density can be calculated. In this example and comparative example, the sample thickness was set to about 0.15 μm for all samples by the FIB method.
(B) Tensile strength (TS) and flexibility (tensile elongation at break)
Three each were tested according to JIS Z 2241 and the average value was determined. The tensile strength was 80 MPa or more and less than 240 MPa. For the flexibility, the tensile elongation at break was 10% or more.
(C) Conductivity (EC)
Three specific resistances were measured using a four-terminal method in a constant temperature bath holding a 300 mm long test piece at 20 ° C. (± 0.5 ° C.), and the average conductivity was calculated. The distance between the terminals was 200 mm. The electrical conductivity is not particularly limited, but is preferably 50% IACS or more, and more preferably 54% or more.
(D) Number of repeated fractures As a reference for bending fatigue resistance, the strain amplitude at room temperature was ± 0.17%. Bending fatigue resistance varies with strain amplitude. When the strain amplitude is large, the fatigue life is shortened, and when the strain amplitude is small, the fatigue life is lengthened. Since the strain amplitude can be determined by the wire diameter of the wire rod 1 and the bending radii of the bending jigs 2 and 3 shown in FIG. 1, the wire diameter of the wire rod 1 and the bending radii of the bending jigs 2 and 3 are arbitrarily set and bent. It is possible to conduct a fatigue test.
The number of repeated ruptures by repeatedly bending using a jig that gives a bending strain of 0.17% using a double-bending fatigue tester manufactured by Fujii Seiki Co., Ltd. (currently Fujii Co., Ltd.) 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. 1, the wire 1 was inserted with a gap 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 1.5 Hz (1.5 reciprocations per second), and when the wire specimen 1 breaks, the weight 4 falls and stops counting. The number of repeated breaks was set to pass 100,000 times or more. Preferably it is 140,000 times or more, More preferably, it is 160,000 times.

From the results in Table 1 above, the following is clear.
Experiment No. 1 of Example 1 1 to 20 is an alloy composition of the present invention, the dispersion density of Mg ₂ Si needle-like precipitates is in the range of 10 to 200 / μm ² , the tensile strength is less than 240 MPa, and the tensile breaking elongation is 10% or more. Met. And this wire showed a very large number of repeated fractures and was excellent in bending fatigue resistance.
On the other hand, in Comparative Example 1, the experiment No. The 1-4 wires had an alloy composition outside the scope of the present invention, and were broken during the wire drawing. Experiment No. In No. 5, the temperature of the continuous energization heat treatment of the cold-drawn work material was too high, and the tensile elongation at break was extremely low. Experiment No. In 6 to 11, the age hardening treatment temperature was too low or too high, and a sufficient number of Mg ₂ Si needle-like precipitates were not generated. Therefore, Experiment No. In 5-11, compared with the thing of Example 1, all had the extremely low frequency | count of the repeated fracture | rupture of a wire.

1 Test piece (wire)
2, 3 Bending jig 4 Weight 5 Holding jig

Claims (10)

An alloy containing 0.01 to 1.5 mass% Fe, 0.01 to 1.2 mass% Mg, and 0.01 to 1.2 mass% Si, with the balance being substantially made of Al and inevitable impurities. An aluminum alloy wire having a composition, a dispersion density of Mg ₂ Si needle-like precipitates of 10 to 200 pieces / μm ² , a tensile strength of less than 240 MPa, and a tensile breaking elongation of 10% or more.   The aluminum alloy wire according to claim 1, wherein the alloy composition contains 0.01 to 1.0 mass% of Cu.   3. The aluminum alloy wire according to claim 1, wherein the aluminum alloy wire is produced by subjecting an aluminum alloy material having the alloy composition to an aging heat treatment at 120 to 250 ° C. 3.   The aluminum alloy wire according to claim 3, wherein the aging heat treatment is performed after the solution treatment.   The aluminum alloy conductor according to any one of claims 1 to 4, wherein the aluminum alloy conductor is used as a battery cable, a harness, or a conductor for a motor in a moving body.   The aluminum alloy conductor according to claim 5, wherein the moving body is an automobile, a train, or an aircraft. An alloy containing 0.01 to 1.5 mass% Fe, 0.01 to 1.2 mass% Mg, and 0.01 to 1.2 mass% Si, with the balance being substantially made of Al and inevitable impurities. The wire-drawn processed material having a composition is subjected to aging heat treatment at 120 to 250 ° C. after solution heat treatment, the dispersion density of the Mg ₂ Si needle-like precipitates is 10 to 200 / μm ² , and the tensile strength is less than 240 MPa. And the manufacturing method of the aluminum alloy wire which satisfy | fills 10% or more of tensile breaking elongation. The method for producing an aluminum alloy wire according to claim 7, wherein the solution heat treatment is a continuous energization heat treatment and satisfies the following formula.
0.03 ≦ x ≦ 0.73 and 22x ^−0.4 + 500 ≦ y ≦ 18x ^−0.4 +560
(In the formula, x represents the annealing time (seconds), and y represents the wire temperature (° C.).) The method for producing an aluminum alloy wire according to claim 7, wherein the solution heat treatment is a continuous running heat treatment and satisfies the following formula.
1.5 ≦ x ≦ 5 and −8.5x + 612 ≦ z ≦ −8.5x + 667
(In the formula, x represents annealing time (seconds), and z represents annealing furnace temperature (° C.).)   The method for producing an aluminum alloy wire according to claim 7, wherein the solution heat treatment is a batch heat treatment, and is performed so as to satisfy a temperature of 500 to 580 ° C and a time of 30 minutes to 6 hours.

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