JP2014159639A - Aluminum alloy wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy, an aluminum alloy wire, an aluminum alloy stranded wire, a coated wire, and a wire harness having high toughness and high conductivity, and to provide a method of manufacturing the aluminum alloy wire.SOLUTION: An aluminum alloy wire contains Fe of 0.005 mass% to 2.2 mass% and the balance Al with inevitable impurities. Further it can contain total 0.005 mass% to 1.0 mass%, by mass%, of at least one kind of an additive element selected from Mg, Si, Cu, Zn, Ni, Mn, Ag, Cr and Zr. The Al alloy wire has conductivity of 58%IACS or more and elongation of 10% or more. The Al alloy wire is manufactured through processes of casting, rolling, wire drawing and softening treatment. The softening treatment is applied to the alloy wire to provide excellent toughness such as elongation or impact resistance, and consequently, fracture of wires occurring in the vicinity of the terminal parts when a wire harness is installed can be reduced.

Description

  The present invention includes an aluminum alloy wire and an aluminum alloy stranded wire used for a conductor of an electric wire, a covered electric wire using the alloy wire or an alloy stranded wire as a conductor, a wire harness including the covered electric wire, and a method for producing the alloy wire, Further, it relates to an aluminum alloy. In particular, the present invention relates to an aluminum alloy wire having a well-balanced characteristic (strength, toughness, conductivity) suitable for a wire conductor of a wire harness used in a transport device such as an automobile.

  2. Description of the Related Art Conventionally, a form called a wire harness in which a plurality of electric wires having terminals are bundled is used for a wiring structure of a transport device such as an automobile or an airplane, or an industrial device such as a robot. Conventionally, copper-based materials such as copper and copper alloys, which are excellent in electrical conductivity, have been the main constituent material for wire conductors of wire harnesses.

In recent years, the performance and functionality of automobiles have been rapidly increased, and with the increase of various electric devices and control devices mounted on the vehicle, the number of electric wires used for these devices is also increasing. On the other hand, in recent years, improvement of fuel consumption of automobiles, airplanes and the like is desired for environmental protection. When the weight is reduced, fuel consumption can be improved. Therefore, in order to reduce the weight of the electric wire, it has been studied to use aluminum having a specific gravity of about 1/3 of copper as a conductor. For example, there is an example in which pure aluminum is used for a conductor for an electric wire of 10 mm ² or more such as an automobile battery cable. However, pure aluminum has lower strength than copper-based materials and is inferior in fatigue resistance, so it is difficult to apply it to a general electric wire conductor having a conductor cross-sectional area of 1.5 mm ² or less, for example. On the other hand, Patent Document 1 discloses an aluminum alloy wire used for an electric wire conductor of an automobile wire harness made of an aluminum alloy having higher strength than pure aluminum.

JP 2005-336549 A

  However, the conventional aluminum alloy wire does not have sufficient characteristics required for a wire harness deployed in a transport device such as an automobile.

  The electric conductor is desired to have high conductivity. However, the aluminum alloy wire described in Patent Document 1 cannot be said to have a sufficiently high electrical conductivity.

  Further, a high-strength aluminum alloy electric wire as described in Patent Document 1 has insufficient toughness. Conventionally, aluminum alloys constituting conductors for electric wires of automobile wire harnesses have been studied mainly for the purpose of improving strength, and toughness (impact resistance, elongation, etc.) has not been sufficiently studied. When the present inventors examined, when assembling a wire harness using a high-strength aluminum alloy wire as described in Patent Document 1, the conductor breaks in the vicinity of the boundary with the terminal portion in the conductor. I got the knowledge that there is. In other words, the properties of the wire itself have been studied, but the properties of the wire harness including the terminal portion have not been studied, and the development of a wire harness having sufficient toughness required for assembly has been made. Not done.

  The terminal portion is attached so that a desired conduction state can be maintained. However, the conventional aluminum alloy wire rod has a stress that is reduced when it is mounted (it decreases with time), so that the fixing force with the terminal portion is reduced, and the terminal portion may fall out of the electric wire. The knowledge that there is. That is, the electric terminal using the conventional aluminum alloy wire may loosen the attached terminal portion. Therefore, it is desired to develop a wire harness that has a high adhering force between the electric wire and the terminal portion.

  Therefore, one of the objects of the present invention is to provide an aluminum alloy wire suitable for a wire harness electric wire conductor, an aluminum alloy stranded wire, and a coated electric wire suitable for a wire harness. It is to provide. Another object of the present invention is to provide a wire harness including an electric wire having high strength, high toughness and high electrical conductivity. Furthermore, the other object of this invention is to provide the manufacturing method of the said aluminum alloy wire of this invention.

  As a result of studying an aluminum alloy wire suitable for a wire conductor having high conductivity and sufficient characteristics required for a wire harness, in particular, sufficient impact resistance and adhesion to a terminal portion, the present inventors have drawn It was found that it is preferable to use a soft material that has been subjected to a softening treatment later (not immediately after). When the softening treatment is performed, not only the elongation of the wire can be improved, but also the electrical conductivity can be improved by removing strain accompanying plastic processing such as wire drawing. And in addition to performing the softening treatment, the present inventors made an aluminum alloy having a specific composition, specifically, an aluminum alloy containing a specific amount of Fe, so that the impact resistance and the terminal portion It was found that an aluminum alloy wire having excellent strength and strength could be obtained. The present invention is based on these findings.

The manufacturing method of the aluminum alloy wire of the present invention includes the following steps.
1. A step of casting a molten aluminum alloy containing Fe in an amount of 0.005 mass% to 2.2 mass% with the balance being Al to form a cast material.
2. A step of rolling the cast material to form a rolled material.
3. A step of drawing the rolled material to form a drawn material.
4. A step of softening the drawn wire material to form a soft material.
And the manufacturing method of this invention performs a softening process to a wire drawing material so that elongation of the wire after a softening process may be 10% or more. The obtained aluminum alloy wire is used as a conductor.

  The aluminum alloy wire of the present invention is obtained by the above production method. The aluminum alloy wire of the present invention is used for a conductor and contains 0.005 mass% or more and 2.2 mass% or less of Fe, with the balance being Al and impurities. The aluminum alloy wire (hereinafter referred to as Al alloy wire) has a conductivity of 58% IACS or more and an elongation of 10% or more.

  Since the Al alloy wire of the present invention is a soft material subjected to a softening treatment, it is excellent in both conductivity and toughness and has high connection strength with the terminal portion. Moreover, since the Al alloy wire of the present invention has a specific composition, it has high strength. Therefore, the Al alloy wire of the present invention has sufficient conductivity, impact resistance, strength, and connectivity with the terminal portion desired for the wire harness, and can be suitably used as a conductor for the wire of the wire harness. Hereinafter, the present invention will be described in more detail. In addition, content of an element shows the mass%.

[Al alloy wire]
"composition"
The Al alloy of the present invention constituting the Al alloy wire of the present invention is an Al—Fe alloy containing 0.005% or more and 2.2% or less of Fe. By containing 0.005% or more of Fe, an Al alloy wire having excellent strength can be obtained. The higher the Fe content, the higher the strength of the Al alloy. However, the electrical conductivity and toughness are lowered, and wire breakage is likely to occur during wire drawing, so Fe: 2.2% or less. Fe can improve the strength without causing much decrease in electrical conductivity, but if Fe is added excessively, workability such as wire drawing is reduced. A more preferable content of Fe is 0.9% or more and 2.0% or less.

  In addition to Fe, it contains one or more additive elements selected from Mg, Si, Cu, Zn, Ni, Mn, Ag, Cr, and Zr, thereby improving strength, toughness, and impact resistance. be able to. Mn, Ni, Zr, and Cr are elements that have a high effect of improving the strength, although the decrease in conductivity is large. Ag and Zn are less likely to decrease in conductivity and have a certain degree of strength improvement effect. Cu has little decrease in conductivity and can improve strength. Although Mg has a large decrease in electrical conductivity, the effect of improving the strength is high, and in particular, the strength can be further improved by containing it together with Si. These additive elements may be contained alone or in combination of two or more, and the total content is preferably 0.005% by mass or more and 1.0% by mass or less. Preferable contents are Mg: 0.05% to 0.5%, Mn, Ni, Zr, Zn, Cr and Ag: 0.005% to 0.2% in total, Cu: 0.05% to 0.5%, Si: 0.05% to 0.3% More preferably, Mg: 0.05% to 0.4%, especially Mg: 0.1% to 0.4%, Mn, Ni, Zr, Zn, Cr and Ag: 0.005% to 0.15% in total Hereinafter, Cu: 0.05% to 0.4%, Si: 0.05% to 0.2%. If Mg exceeds 0.5%, the total of Mn, Ni, Zr, Zn, Cr and Ag exceeds 0.2% and Cu exceeds 0.5%, the strength of the Al alloy increases, but the conductivity and toughness decrease. Disconnection is likely to occur during wire drawing. When Si is more than 0.3%, the electrical conductivity and toughness are reduced.

In the Al alloy constituting the Al alloy wire of the present invention, the following (1) to (4) may be mentioned as specific compositions when the additive element is contained in addition to Fe.
(1) By mass%, Fe is 0.90% or more and 1.20% or less, Mg is 0.10% or more and 0.25% or less, and the balance is Al and impurities.
(2) By mass%, Fe is 1.01% or more and 2.2% or less, Mg is 0.05% or more and 0.5% or less, and one or more elements selected from Mn, Ni, Zr, Zn, Cr, and Ag in total 0.005 % And 0.2% or less, the balance being Al and impurities.
(3) By mass%, Fe is 1.01% or more and 2.2% or less, Cu is 0.05% or more and 0.5% or less, and the balance is Al and impurities.
(4) At least 1 type of Fe containing 1.01% or more and 2.2% or less, Cu containing 0.05% or more and 0.5% or less, Mg containing 0.1% or more and 0.5% or less, and Si containing 0.05% or more and 0.3% or less. Contains, the balance being Al and impurities.

  Furthermore, when the Al alloy contains at least one of Ti and B, the strength can be further improved. Ti and B have the effect of refining the crystal structure of the Al alloy during casting. If the crystal structure is fine, the strength can be improved. Although it may contain B alone, the effect of refining the crystal structure is further improved by containing Ti alone, particularly both. In order to sufficiently obtain this refinement effect, it is preferable that Ti is contained in a mass ratio of 100 ppm to 500 ppm (0.01% to 0.05%) and B is 10 ppm to 50 ppm (0.001% to 0.005%). If Ti: more than 500 ppm and B: more than 50 ppm, the above-mentioned refinement effect is saturated or the conductivity is lowered.

"Characteristic"
Since the Al alloy wire of the present invention is composed of the Al alloy of the present invention having a specific composition and is a soft material, it is excellent in conductivity and toughness, conductivity: 58% IACS or more, and elongation: 10% or more. Although depending on the kind and amount of additive elements and softening conditions, the Al alloy wire of the present invention can also satisfy electrical conductivity: 59% IACS or more and elongation: 25% or more.

  Further, as a result of examination by the present inventors, it has been found that the electrical conductivity and toughness can be increased and the corrosion resistance can be improved by the softening conditions (method). Specifically, as a softening treatment, when batch processing (brightness processing) described later is performed, conductivity and elongation tend to be high, and when continuous processing described later is performed, corrosion resistance tends to be excellent. When the Al alloy wires subjected to each softening treatment were examined, there was a difference in the presence of precipitates. When continuous softening treatment was performed, there were few very fine precipitates of 100 nm or less, and batch softening treatment was performed. In this case, more precipitates were present than when the continuous softening treatment was performed. That is, the following Al alloy wire was obtained.

(Continuous softening treatment): Al alloy wire used for conductors, containing Fe in an amount of 0.005 mass% to 2.2 mass%, with the balance being Al and impurities. The cross section of the Al alloy wire is 2400 nm x 2600 nm When an observation field is taken, the number of precipitates present in the observation field and having an equivalent circle diameter of 100 nm or less is 10 or less.
(Batch softening treatment): Al alloy wire used for conductors, containing Fe in an amount of 0.005 mass% to 2.2 mass%, with the balance being Al and impurities. The cross section of this Al alloy wire is 2400 nm x 2600 nm When an observation field is taken, the number of precipitates present in the observation field and having an equivalent circle diameter of 100 nm or less is more than ten.
In addition to Fe, the above-mentioned additive elements (Mg, Si, Cu, Zn, Ni, Mn, Ag, Cr, Zr) may be contained within the above-described range, and further, Ti and B may be contained. Also good.

  The reason for the difference in the presence state of the precipitates as described above is considered as follows. In the case of continuous softening treatment, the treatment target tends to become high temperature during the softening treatment, so that the Fe precipitated during casting or rolling after casting is re-dissolved, or the temperature lowering rate (cooling rate) after softening treatment is This is presumably because Fe dissolved in a solid state is difficult to precipitate because it is fast, that is, easily cooled. On the other hand, in the case of batch softening treatment, compared to the case of continuous softening treatment, it is difficult for the treatment target to become high temperature during the softening treatment, so that it is difficult for Fe to re-dissolve or be gradually cooled after the softening treatment. (Because the rate of temperature decrease is slow), this is probably because Fe is more likely to precipitate than in the case of continuous softening treatment.

  In addition, crystal precipitates are mainly generated at the time of casting, and fine precipitates are reduced by performing a continuous softening treatment after wire drawing. Accordingly, when the continuous softening treatment is performed, an Al alloy wire having excellent strength and corrosion resistance can be obtained because Fe is sufficiently dissolved in the base material. On the other hand, when batch softening treatment is performed, more fine precipitates exist than when continuous softening treatment is performed, but the size of each precipitate is 100 nm or less, and the abundance is at most 100 / observation above. It is a field of view. The size and abundance of the fine precipitates can be changed by adjusting the softening conditions. For example, by increasing the heating temperature during the softening treatment and increasing the temperature-decreasing rate (cooling rate), the size of the precipitate can be reduced and the abundance can be reduced. Therefore, depending on the conditions of the batch softening treatment, for example, an Al alloy wire having a precipitate size of 80 nm or less and further 50 nm or less and an abundance of 50 or less and further 20 or less can be obtained. Even when batch softening is performed, the strength is high because Fe is dissolved in the base material, and it has excellent toughness by having a structure in which the fine precipitates are uniformly dispersed. Compared to the case of Al, an Al alloy wire having a high conductivity can be obtained by reducing the amount of Fe dissolved.

  The Al alloy wire of the present invention preferably has a tensile strength of 110 MPa to 200 MPa. The present inventors have obtained the knowledge that a conductor for electric wires that is merely high in strength and inferior in toughness is not suitable for a wire harness. In general, an increase in strength causes a decrease in toughness. When the tensile strength satisfies the above range, both high toughness and high strength can be achieved. The Al alloy wire of the present invention preferably has a 0.2% proof stress of 40 MPa or more. When the tensile strength is the same, the higher the 0.2% proof stress, the higher the fixing force with the terminal portion.

  By appropriately adjusting additive elements (type and content) and production conditions (softening conditions, etc.), an Al alloy wire satisfying the above specific ranges in electrical conductivity, elongation, tensile strength, and 0.2% proof stress can be obtained. Decreasing additive elements or increasing the heating temperature during the softening process and then slowing down the temperature decrease tends to increase the electrical conductivity and toughness. Increasing the additional elements or decreasing the heating temperature during the softening process The strength and the 0.2% proof stress tend to be high. For example, the tensile strength can be 120 MPa or more.

"shape"
The Al alloy wire of the present invention can have various wire diameters (diameters) by appropriately adjusting the degree of processing (cross-sectional reduction rate) during wire drawing. For example, when used as a conductor for an electric wire of an automobile wire harness, the wire diameter is preferably 0.2 mm or more and 1.5 mm or less.

  Further, the Al alloy wire of the present invention can have various cross-sectional shapes depending on the die shape at the time of wire drawing. A cross-sectional circular shape is typical, and other cross-sectional shapes such as an elliptical shape, a polygonal shape such as a rectangle or a hexagon are listed. The shape is not particularly limited.

[Al alloy stranded wire]
The Al alloy wire of the present invention can be a stranded wire obtained by twisting a plurality of wires. Even a thin wire rod can be made into a high strength wire rod (twisted wire) by twisting together. The number of twists is not particularly limited. For example, 7,11,19,37 are mentioned. In addition, when the Al alloy stranded wire of the present invention is a compression wire rod that has been twisted and then compression-molded, the wire diameter can be made smaller than that of the twisted state.

[Coated wire]
The said Al alloy wire of this invention, this invention Al alloy strand wire, and a compression wire can be utilized suitably for the conductor for electric wires. Depending on the application, it can be used as a conductor as it is, or it can be used as a covered electric wire having an insulating coating layer formed of an insulating material on the outer periphery of the conductor. The insulating material can be selected as appropriate. For example, polyvinyl chloride (PVC), a non-halogen resin, a material excellent in flame retardancy, and the like can be given. The thickness of the insulating coating layer can be appropriately selected in consideration of desired insulation strength, and is not particularly limited.

[Wire Harness]
The said covered electric wire can be utilized suitably for a wire harness. At this time, a terminal portion is attached to the end portion of the covered electric wire so that it can be connected to a connection target such as a device. This wire harness may include an electric wire group that shares one terminal portion for a plurality of covered electric wires. Moreover, the several covered electric wire provided in this wire harness is excellent in handling property by bundling together with a binding tool etc. This wire harness can be suitably used in various fields where weight reduction is desired, in particular, automobiles where further weight reduction is desired in order to improve fuel efficiency.

[Production method]
《Casting process》
In the production method of the present invention, first, a cast material made of an Al alloy having the above specific composition is formed. For casting, either continuous casting using a movable mold or a frame-shaped fixed mold or mold casting using a box-shaped fixed mold (hereinafter referred to as billet casting) can be used. In continuous casting, since the molten metal can be rapidly solidified, a cast material having a fine crystal structure can be obtained. In addition, by rapid solidification, the crystal precipitate can be made fine, and a cast material having a structure in which the fine crystal precipitate is uniformly dispersed is obtained. When such a cast material is used as a raw material, it is easy to produce an Al alloy wire having a fine crystal structure, and it is possible to improve strength by making crystals finer and toughness by dispersing fine crystal precipitates. . The cooling rate can be appropriately selected, but is preferably 1 ° C./sec or more, and more preferably 4 ° C./sec or more. Further, it is more preferable that the cooling rate is 20 ° C./sec or more in the solid-liquid coexisting temperature range of the molten metal at 600 to 700 ° C. For example, when a continuous casting machine having a water-cooled copper mold or a forced water cooling mechanism is used, rapid solidification at the cooling rate as described above can be realized. By performing rapid solidification by adjusting the cooling rate in continuous casting, DAS (Dendrite Arm Spacing) of the cast material obtained after casting can be reduced. DAS is preferably 50 μm or less, and more preferably 40 μm or less.

  When adding Ti or B, adding just before pouring the molten metal into the mold is preferable because it suppresses local sedimentation of Ti and the like and can produce a cast material in which Ti and the like are evenly mixed. .

<Rolling process>
Next, the cast material is subjected to (hot) rolling to form a rolled material. In particular, when a billet cast material is used, it is preferable to perform a homogenization treatment after casting.

  When the above casting process and rolling process are carried out continuously, it is possible to easily perform hot rolling using the heat accumulated in the cast material, and it is energy efficient and compared with a batch casting method. In addition, it is excellent in productivity of cast rolled material.

<Wire drawing process>
Next, the above-mentioned rolled material or continuous cast rolled material is subjected to (cold) wire drawing to form a wire drawing material. The degree of wire drawing can be appropriately selected according to a desired wire diameter. As for the obtained wire drawing material, a desired number can be prepared and twisted together to form a stranded wire.

《Softening (final heat treatment) process》
Next, a softening process is performed to the said wire drawing material or a strand wire. The softening treatment is performed under conditions such that the elongation of the wire (single wire or stranded wire) after the softening treatment is 10% or more. Softening treatment may be performed both after drawing and after twisting so that the final elongation of the stranded wire becomes 10% or more. This softening treatment is performed in order to increase the toughness of the wire by softening without extremely reducing the strength of the wire that has been increased by refinement of the crystal structure and work hardening.

As the softening treatment, a continuous treatment or a batch treatment can be used. The atmosphere during the softening treatment is preferably an atmosphere with a low oxygen content, such as an air atmosphere or a non-oxidizing atmosphere, in order to suppress the formation of an oxide film on the surface of the wire due to heat during the treatment. Non-oxidizing atmospheres include, for example, a vacuum atmosphere (reduced pressure atmosphere), an inert gas atmosphere such as nitrogen (N ₂ ) and argon (Ar), a hydrogen-containing gas (for example, hydrogen (H ₂ ) only, N ₂ , Ar, A reducing gas such as a mixed gas of inert gas such as helium (He) and hydrogen (H ₂ ) or a gas containing carbon dioxide (for example, a mixed gas of carbon monoxide (CO) and carbon dioxide (CO ₂ )) The atmosphere can be mentioned.

<Batch processing>
Batch processing (bright softening processing) is a processing method in which a heating target is enclosed in a heating container (atmosphere furnace, for example, a box furnace), and the heating target is limited, but the entire heating target is limited. It is the processing method which is easy to manage the heating state. In batch processing, the elongation of the wire can be increased to 10% or more by setting the heating temperature to 250 ° C. or higher. Preferred conditions are heating temperature: 300 ° C. or more and 500 ° C. or less, and holding time: 0.5 hour or more and 6 hours or less. If the heating temperature is less than 250 ° C., the toughness and conductivity are difficult to improve, and if the heating temperature exceeds 500 ° C. or the holding time exceeds 6 hours, the strength decreases. In batch processing, the cooling rate from the heating temperature, that is, the cooling rate after heating is preferably 50 ° C./sec or less. A relatively large amount of fine precipitates can be precipitated by slowing down the temperature decreasing rate relatively slowly. The temperature-decreasing rate can be achieved, for example, by not leaving the furnace immediately after the heating, but by continuously storing it in the furnace after the heating.

<Continuous processing>
Continuous treatment is a treatment method in which the object to be heated is continuously supplied into the heating container, and the object to be heated is continuously heated. There is an advantage that variation in characteristics in the longitudinal direction of the wire can be suppressed because it can be heated uniformly in the direction. In particular, when a softening treatment is performed on a long wire used for a conductor for electric wires, a continuous treatment can be suitably used. Continuous treatment includes direct energization method that heats the object to be heated by resistance heating (continuous energization softening treatment), indirect energization method that heats the object to be heated by high-frequency electromagnetic induction (high frequency induction heating continuous softening treatment), heating in a heated atmosphere A furnace type in which a heating object is introduced into a container (pipe softening furnace) and heated by heat conduction. In order to obtain a wire having an elongation of 10% or more by continuous treatment, for example, the following is performed. The sample is softened by appropriately changing the control parameters that can participate in the desired properties (elongation in this case), the properties (elongation) of the sample are measured, and the correlation data between the parameter values and the measured data are obtained. Create in advance. Based on this correlation data, parameters are adjusted so that a desired characteristic (elongation) is obtained. The control parameters of the energization method include the supply speed (wire speed) into the container, the size of the object to be heated (wire diameter), the current value, and the like. The furnace-type control parameters include the supply speed (linear speed) into the vessel, the size of the object to be heated (wire diameter), the size of the furnace (diameter of the pipe softening furnace), and the like. When the softening device is disposed on the wire drawing material discharge side in the wire drawing machine, a wire having an elongation of 10% or more can be obtained by setting the drawing speed to several hundred m / min or more, for example, 400 m / min or more. In the continuous treatment, it is preferable that the temperature lowering rate after heating is 50 ° C./sec or more. By making the temperature lowering rate relatively fast, precipitation of fine precipitates can be suppressed and the precipitates can be made relatively small. The temperature lowering rate can be adjusted by adjusting the linear velocity or the like as described above.

<< Other processes >>
The manufacturing method of the present invention further includes a step of forming a stranded wire by twisting a plurality of the above-mentioned wire drawing materials or soft materials, and a step of compression-molding the stranded wire to form a compressed wire material having a predetermined wire diameter. The compressed wire can be manufactured. At this time, the softening treatment may be performed only on the wire drawing material before twisting, may be performed both before and after twisting, or not on the wire drawing material before twisting, and only on the twisted wire and the compression wire. You may give it. When producing a soft material having a predetermined elongation before twisting and forming a compressed wire with this soft material or when forming a compressed wire with a twisted wire (soft material) having a predetermined elongation after twisting, compression It is not necessary to perform the softening process later. A covered electric wire can be manufactured by forming the above-mentioned insulating coating layer on the obtained compressed wire. A wire harness can be manufactured by attaching a terminal part to the end part of the obtained covered electric wire and bundling a plurality of covered electric wires with terminal parts.

  The Al alloy wire of the present invention, the twisted Al alloy wire of the present invention, the coated wire of the present invention, and the Al alloy of the present invention have high strength and high toughness, and also have high electrical conductivity. The wire harness of the present invention has a good balance of strength, toughness and electrical conductivity, and is lightweight. The production method of the present invention can produce the Al alloy wire of the present invention with high productivity.

FIG. 1 is a graph showing the relationship between the temperature during softening treatment, conductivity, and tensile strength in an Al—Fe—Mg— (Mn, Ni, Zr, Ag) alloy wire. FIG. 2 is a graph showing the relationship between the temperature during softening treatment, the electrical conductivity, and the tensile strength of an Al—Fe—Cu alloy wire. FIG. 3 is a micrograph of a cross section of an Al alloy wire, FIG. 3 (1) shows a sample subjected to batch softening treatment, and FIG. 3 (2) shows a sample subjected to continuous softening treatment. FIG. 4 is an explanatory diagram for explaining a test method of an impact resistance test. FIG. 5 is an explanatory diagram for explaining a test method of a terminal adhering force test.

  An Al alloy wire was produced, and further, a covered electric wire was produced using the Al alloy wire, and various characteristics of the Al alloy wire and the covered electric wire were examined. The covered electric wire is produced by a procedure of casting, rolling, wire drawing, stranded wire, compression, softening, and formation of an insulating coating layer.

[Characteristics of Al alloy wire]
First, an Al alloy wire is produced. Prepare pure aluminum (99.7% by mass or more Al) as a base, melt it, and add the additive elements shown in Table 1 to the resulting molten metal (molten aluminum) so as to have the contents shown in Table 1, to obtain an Al alloy. Make molten metal. It is desirable that the Al alloy molten metal whose components have been adjusted is appropriately subjected to a hydrogen gas removal treatment or a foreign matter removal treatment.

Using a belt-wheel type continuous casting and rolling machine, the prepared molten Al alloy is continuously cast and hot-rolled to produce a φ9.5 mm wire rod (continuously cast rolled material). In the continuous casting, the cooling mechanism was adjusted to a cooling rate of 4.5 ° C./sec, and the DAS of the obtained cast material was measured using a structural photograph, and was about 20 μm. Alternatively, the molten aluminum alloy is poured into a predetermined fixed mold and cooled to produce a billet cast material. After homogenizing the cast material, hot rolling is performed to obtain a φ9.5 mm wire. A rod (rolled material) is produced. For the sample containing Ti or Ti and B, Ti grains or TiB ₂ wires are supplied to the molten Al alloy just before casting so that the content shown in Table 1 is obtained.

  The wire rod is subjected to cold wire drawing to produce a wire drawing material having a wire diameter of φ0.3 mm. The obtained wire is subjected to the softening treatment shown in Table 1 to produce a soft material (Al alloy wire). Softening treatment uses a box furnace, batch treatment with the atmosphere and heating temperature shown in Table 1 (softening treatment holding time is 3 hours, cooling rate: 0.02 ° C / sec), or high frequency with atmosphere shown in Table 1 Induction heating type continuous treatment (linear speed: 500 m / min, current value: 200 A, temperature drop rate: 500 ° C./sec) was adopted. Here, sample Nos. 1-2 and 1-3 were subjected to continuous treatment, and samples other than sample Nos. 1-2 and 1-3 and subjected to softening treatment were subjected to batch treatment. In the continuous treatment, the temperature was measured with a non-contact infrared thermometer. As a comparison, untreated materials (sample Nos. 1-102, 1-112) that were not softened after wire drawing were also prepared.

  Tensile strength (MPa), elongation (%), 0.2% proof stress, and electrical conductivity (% IACS) were measured for the obtained soft and untreated materials having a wire diameter of 0.3 mm. The results are shown in Table 2.

  Tensile strength (MPa), elongation (%, elongation at break), and 0.2% proof stress were measured using a general-purpose tensile tester in accordance with JIS Z 2241 (metal material tensile test method, 1998). The conductivity (% IACS) was measured by the bridge method.

  As shown in Table 1, sample Nos. 1-1 to 1-4, 1-11 to 1-16, 1-21 to 1-26 made of an Al-Fe alloy with a specific composition and softened Has an electrical conductivity of 58% IACS or more, an elongation of 10% or more, a 0.2% proof stress of 40 MPa or more, and a tensile strength of 110 MPa or more. That is, Sample Nos. 1-1 to 1-4, 1-11 to 1-16, and 1-21 to 1-26 have not only high conductivity and high toughness but also high strength. In particular, when containing one or more additive elements selected from Mg, Si, Cu, Zn, Ni, Mn, Ag, Cr, and Zr in addition to Fe, the strength tends to increase, and in addition to Mg, When Mn, Ni, Zr, Ag is added, or when both Mg, Si, Mg, and Si are added in addition to Cu, the strength is higher. In addition, when samples having the same composition are compared, a sample subjected to continuous casting and rolling tends to have a higher elongation than a sample subjected to billet casting, and is 25% or more depending on the composition and is excellent in toughness.

  On the other hand, Samples Nos. 1-102 and 1-112 not subjected to softening treatment have high strength, but have very low elongation, poor toughness, and low conductivity. In addition, even if softening is performed, samples with no specific composition, specifically No. 1-101 and 1-111 with a lot of Fe and other additive elements, are high in strength but low in elongation and conductivity. .

[Softening conditions (temperature) and characteristics]
Samples with different softening conditions were prepared, and the electrical conductivity (%) and tensile strength (MPa) of the obtained samples were examined. The results are shown in Figs. Here, a wire drawing material having a composition of sample No. 1-12 (FIG. 1) and sample No. 1-22 (FIG. 2) and having a wire diameter of 0.3 mm was subjected to softening treatment. The softening treatment was a batch treatment using a box furnace (reducing gas atmosphere, temperature drop rate: 0.02 ° C / sec), and the heating temperature (softening temperature) was appropriately selected in the range of 200 to 400 ° C and applied to the wire drawing material. (Retention time: 3 hours).

  As shown in FIGS. 1 and 2, it can be seen that a soft material having a conductivity of 58% IACS or more and a tensile strength of 120 MPa or more can be obtained by applying a softening treatment at a heating temperature of 250 ° C. or more. At 200 ° C., the tensile strength is too high, the elongation becomes small, and it is considered that the toughness is poor.

[Softwood structure]
Fig. 3 is a transmission electron microscope (TEM) photograph (45,000 times) of the cross section of the soft material produced, Fig. 3 (1) is sample No. 1-1 (batch softening treatment), and Fig. 3 (2) is Sample No. 1-2 (continuous softening treatment) is shown. In FIG. 3, dark gray small grains are precipitates, and black relatively large grains (grains having an equivalent circle diameter exceeding 200 nm) are crystallized substances. As shown in FIG. 3 (2), the sample subjected to the continuous softening treatment has few fine precipitates having an equivalent circle diameter of 100 nm or less, and the sample subjected to the batch softening treatment as shown in FIG. 3 (1). It can be seen that the sample has more fine precipitates having an equivalent circle diameter of 100 nm or less than the sample subjected to the continuous softening treatment. For one cross section, three observation fields of 2400 nm × 2600 nm were taken, and the number of precipitates with an equivalent circle diameter of 100 nm or less present in each observation field was measured. The number of precipitates of 100 nm or less (average number in three observation fields) was 3 (10 or less), and 18 samples (over 10 and 20 or less) were subjected to the batch softening treatment. The size of the precipitate (equivalent circle diameter) is the diameter when the micrograph is image-processed and the area of the precipitate is converted into a circle.

[Characteristics of coated wire]
As described above, an Al alloy wire made of an Al—Fe-based alloy having a specific composition and subjected to a softening treatment is expected to be suitably used as a conductor for an electric wire of a wire harness. Then, the covered electric wire was produced and the mechanical characteristic was investigated.

A plurality of wiredrawing materials (composition: see Table 1) having a wire diameter of φ0.3 mm produced as described above are twisted together to produce a stranded wire. Here, after a total of 11 wire drawing materials, 3 inside and 8 outside, are twisted together, compression processing is performed so that the cross-sectional outer shape becomes a circular shape, thereby producing a 0.75 mm ² compressed wire. The obtained compressed wire was softened (batch using a box furnace) under the same conditions as the softening treatment applied to the drawn wire with a wire diameter of φ0.3 mm described above by the atmosphere and heating temperature shown in Table 1. Treatment or high-frequency induction heating type continuous treatment). An insulating coating layer (thickness: 0.2 mm) is formed on the outer periphery of the obtained soft material with an insulating material (here, a halogen-free insulating material) to produce a coated electric wire. As a comparison, untreated materials (Sample Nos. 2-102 and 2-112) in which the compressed wire obtained by twisting and compressing the drawn wires was not softened were also prepared.

  The obtained coated wire was examined for impact resistance (J / m) and terminal fixing force (N). The results are shown in Table 3.

The impact resistance (J / m or (N · m) / m) was evaluated as follows. FIG. 4 is an explanatory diagram for explaining a test method of an impact resistance test. A weight w is attached to the tip of the sample S (inter-score distance L: 1 m) (FIG. 4 (1)), the weight w is lifted upward by 1 m, and then dropped freely (FIG. 4 (2)). Then, measure the weight (kg) of the maximum weight w that the sample S does not break, and divide the product of the weight multiplied by the gravitational acceleration (9.8m / s ² ) and the drop distance 1m by the drop distance. Evaluated as impact resistance (J / m or (N · m) / m).

  The terminal fixing force (N) was evaluated as follows. FIG. 5 is an explanatory diagram for explaining a test method of a terminal adhering force test. The coating layer 2 at both ends of the sample S having the insulating coating layer 2 on the outer periphery of the stranded wire 1 is peeled off to expose the stranded wire 1. A terminal portion 3 is attached to the stranded wire 1 on one end side, and the terminal portion 3 is sandwiched by a terminal chuck 20. The stranded wire 1 on the other end side is clamped by the wire rod chuck 21. Using a general-purpose tensile tester, the maximum load (N) at the time of fracture of the sample S sandwiched at both ends by the chucks 20 and 21 is measured, and this maximum load (N) is evaluated as the terminal fixing force (N).

  As shown in Table 3, sample Nos. 2-1 to 2-4, 2-11 to 2-16, 2-, made of a twisted wire made of an Al-Fe alloy having a specific composition and subjected to a softening treatment It can be seen that the covered electric wires of 21 to 2-26 have excellent impact resistance and high connection strength with the terminal portion.

[Softening conditions (method) and characteristics]
As the softening treatment, an Al alloy wire subjected to batch treatment and an Al alloy wire subjected to continuous treatment were produced, and corrosion resistance and mechanical properties were examined.

The Al alloy wire was produced in the same manner as the above-described φ0.3 mm Al alloy wire. That is, by adding the additive elements shown in Table 4 to the same pure aluminum melt as described above so as to have the content shown in Table 4, a molten Al alloy was prepared, and φ9. A 5mm wire rod is manufactured (cooling rate during casting: 4.5 ° C / sec, DAS of cast material: about 20μm). This wire rod is subjected to cold wire drawing to produce a wire drawing material having a wire diameter of φ0.3 mm, and subjected to softening treatment (batch treatment (bright softening treatment) or continuous treatment) under the conditions shown in Table 4, φ0 Get 3mm softwood (single wire). The batch processing conditions at this time were basically the same as those of Sample No. 1-1 or Sample No. 1-11, and the continuous processing conditions were the same as those of Sample No. 1-2. Further, after twisting 11 obtained wire rods with a wire diameter of φ0.3 mm, a 0.75 mm ² compressed wire was produced, and the obtained compressed wire was softened under the conditions shown in Table 4 (batch treatment or Continuous treatment) to obtain a 0.75 mm ² soft material (compressed wire). The batch processing conditions at this time were basically the same as those of Sample No. 2-1 or Sample No. 2-11, and the continuous processing conditions were the same as those of Sample No. 2-2.

  In the same manner as described above, the obtained soft material was subjected to tensile strength (MPa), 0.2% proof stress, elongation (%, elongation at break), conductivity (% IACS), impact resistance (J / m), terminal fixation. The wearing power (N) was examined. The results are shown in Table 5.

  The softening treatment shown in Table 4 is the same as the softening treatment applied to the φ0.3 mm soft material for the wire diameter φ1.0 mm drawn wire obtained in the course of producing the wire diameter φ0.3 mm described above. The pitting corrosion potential (V) and the protective potential (V) were measured using the soft material as a sample. The results are shown in Table 5.

The pitting potential and the protective potential were measured as follows. First, the sample is immersed in a 5% by mass NaOH aqueous solution (60 ° C.) for a predetermined time (1 minute) to remove the passive film. Next, the sample is immersed in a 50 mass% HNO ₃ aqueous solution for a predetermined time (about 10 seconds), washed and neutralized, and then washed with water. The washed sample is immersed in an electrolytic solution (5 mass% NaCl aqueous solution), and is reduced by applying a constant voltage for a predetermined time (−1.5 V, 5 minutes). Thereafter, the potential is swept, and the pitting corrosion potential and the protective potential are measured. This measurement is performed by configuring a three-electrode electrochemical measurement cell. This cell includes a container into which an electrolytic solution is injected, a reference electrode (RE) that is immersed in the electrolytic solution: Ag / AgCl, a counter electrode (CE): Pt, and a sample to be measured. One end of each of these RE, CE, and sample is connected to a commercially available potentiostat / galvanostat device, and a change in current is measured by applying a constant potential as described above. Here, the pitting potential is the potential at which the current continues to increase after the current reaches 100 μA / cm ^2, and the protective potential is the reverse of the potential when the current reaches 1 mA / cm ² (here Then, the potential is swept in the cathode direction) so that the current becomes zero. It can be said that the smaller the absolute value of the pitting potential and the smaller the absolute value of the protective potential, the smaller the pitting corrosion, that is, the better the corrosion resistance.

  As shown in Table 5, an Al alloy wire made of an Al-Fe alloy with a specific composition and subjected to softening treatment has an electrical conductivity of 58% IACS or more, elongation of 10% or more, 0.2% proof stress of 40 MPa or more, It has a tensile strength of 110 MPa or more, high conductivity, high toughness, high strength, excellent impact resistance, and high connection strength with the terminal. In particular, when comparing samples having the same composition, the sample subjected to the batch softening treatment may tend to have better mechanical properties such as conductivity, elongation, strength, and impact resistance than the sample subjected to the continuous softening treatment. I understand. On the other hand, when comparing samples having the same composition, the samples subjected to the continuous softening treatment tend to have a smaller absolute value of the pitting corrosion potential and the absolute value of the protective potential and superior corrosion resistance than the samples subjected to the batch softening treatment. I understand that. Further, for example, by comparing Sample Nos. 15 and 16 in Table 5, it can be seen that even if the tensile strength is the same, if the 0.2% proof stress is high, the terminal fixing force tends to increase.

  As described above, a coated electric wire using an Al alloy wire made of an Al-Fe-based alloy having a specific composition and subjected to a softening treatment has high conductivity, high toughness, and high strength, and connection strength with a terminal portion. Excellent impact resistance. Therefore, it is expected that this covered electric wire can be suitably used for a wire harness, particularly an automobile wire harness.

  The above-described embodiment can be appropriately changed without departing from the gist of the present invention, and is not limited to the above-described configuration. For example, the contents of Fe, Cu, Mg, Si, Zn, Ni, Mn, Ag, Cr, and Zr may be changed within a specific range. Moreover, you may change the magnitude | size and shape of a strand, and the number of strands.

  The wire harness of the present invention can be suitably used for applications that are lightweight and require high strength, high toughness, and high conductivity, for example, automobile wiring. The coated wire according to the present invention, the aluminum alloy wire according to the present invention, or the aluminum twisted wire according to the present invention can be suitably used for the electric wire of the wire harness or the conductor for the electric wire. Moreover, the manufacturing method of this invention aluminum alloy wire can be utilized suitably for manufacture of the said this invention aluminum alloy wire.

1 Stranded wire 2 Insulation coating layer 3 Terminal area
S Specimen w Weight 20 Terminal chuck 21 Wire material chuck

Claims (23)

An aluminum alloy wire used for a conductor,
Fe is contained 0.005 mass% or more and 2.2 mass% or less, and the balance consists of Al and impurities,
Conductivity is 58% IACS or higher,
An aluminum alloy wire characterized by an elongation of 10% or more.   Furthermore, it contains 0.005% by mass or more and 1.0% by mass or less of one or more additive elements selected from Mg, Si, Cu, Zn, Ni, Mn, Ag, Cr, and Zr. The aluminum alloy wire according to 1. 3. The aluminum alloy wire according to claim 2, wherein the aluminum alloy wire has a composition of any one of the following (1) to (4).
(1) By mass%, Fe is 0.90% or more and 1.20% or less, Mg is 0.10% or more and 0.25% or less, and the balance is Al and impurities.
(2) By mass%, Fe is 1.01% or more and 2.2% or less, Mg is 0.05% or more and 0.5% or less, and one or more elements selected from Mn, Ni, Zr, Zn, Cr, and Ag in total 0.005 % And 0.2% or less, the balance being Al and impurities.
(3) By mass%, Fe is 1.01% or more and 2.2% or less, Cu is 0.05% or more and 0.5% or less, and the balance is Al and impurities.
(4) At least 1 type of Fe containing 1.01% or more and 2.2% or less, Cu containing 0.05% or more and 0.5% or less, Mg containing 0.1% or more and 0.5% or less, and Si containing 0.05% or more and 0.3% or less. Contains, the balance being Al and impurities. Furthermore, containing at least one of Ti and B,
The aluminum alloy wire according to any one of claims 1 to 3, wherein the Ti content is 100 ppm to 500 ppm and the B content is 10 ppm to 50 ppm in terms of mass ratio.   When the observation field of view of 2400 nm × 2600 nm is taken in the cross section of the aluminum alloy wire, the number of precipitates present in the observation field of view and having an equivalent circle diameter of 100 nm or less is 10 or less. The aluminum alloy wire according to any one of claims 1 to 4.   When an observation field of view of 2400 nm × 2600 nm is taken in the cross section of the aluminum alloy wire, the number of precipitates present in the observation field of view and having an equivalent circle diameter of 100 nm or less is more than 10. The aluminum alloy wire according to any one of claims 1 to 4.   The aluminum alloy wire according to any one of claims 1 to 6, wherein a 0.2% proof stress is 40 MPa or more.   The aluminum alloy wire according to any one of claims 1 to 7, wherein the tensile strength is 110 MPa or more and 200 MPa or less.   The aluminum alloy wire according to any one of claims 1 to 8, wherein a wire diameter is 0.2 mm or more and 1.5 mm or less.   A plurality of aluminum alloy wires according to any one of claims 1 to 9, wherein the aluminum alloy strands are twisted together.   The aluminum alloy wire according to any one of claims 1 to 9, an aluminum alloy stranded wire obtained by twisting a plurality of the aluminum alloy wires, and a compressed wire material obtained by compression molding the stranded wire, and a conductor thereof, A covered electric wire comprising an insulating coating layer on an outer periphery.   12. A wire harness comprising: the covered electric wire according to claim 11; and a terminal portion attached to an end portion of the electric wire.   13. The wire harness according to claim 12, which is used for an automobile. A method for producing an aluminum alloy wire used for a conductor,
A step of forming a cast material by casting a molten aluminum alloy containing Fe in an amount of 0.005 mass% to 2.2 mass% with the balance being Al;
Rolling the cast material to form a rolled material;
Applying a wire drawing process to the rolled material to form a wire drawing material;
Comprising a step of softening the wire drawing material to form a soft material,
The method for producing an aluminum alloy wire, wherein the softening treatment is performed on the wire drawing material so that the elongation of the wire material after the softening treatment is 10% or more.   The molten aluminum alloy further contains one or more additive elements selected from Mg, Si, Cu, Zn, Ni, Mn, Ag, Cr, and Zr in total of 0.005% by mass to 1.0% by mass. 15. The method for producing an aluminum alloy wire according to claim 14, wherein:   16. The method for producing an aluminum alloy wire according to claim 14, wherein the softening treatment is continuous softening treatment by energization or continuous softening treatment by high-frequency induction heating, and is performed in an air atmosphere or a non-oxidizing atmosphere. .   17. The method for producing an aluminum alloy wire according to claim 16, wherein in the continuous softening treatment, a temperature lowering rate after heating is 50 ° C./sec or more.   16. The method for producing an aluminum alloy wire according to claim 14, wherein the softening treatment is a batch treatment using an atmosphere furnace, and is performed in a non-oxidizing atmosphere at an atmosphere temperature of 250 ° C. or higher.   19. The method for producing an aluminum alloy wire according to claim 18, wherein, in the batch softening treatment, a temperature lowering rate after heating is 50 ° C./sec or less.   20. The method for producing an aluminum alloy wire according to claim 14, wherein the casting process and the rolling process are continuously performed to form a continuously cast rolled material.   The aluminum alloy wire according to any one of claims 14 to 20, wherein the casting is performed at a cooling rate of 1 ° C / sec or more, and a DAS of a cast material obtained after casting is 50 µm or less. Manufacturing method. A step of twisting a plurality of the wire drawing materials or soft materials to form a stranded wire;
A step of compression-molding the stranded wire to form a compressed wire having a predetermined wire diameter,
The method for producing an aluminum alloy wire according to any one of claims 14 to 21, wherein the compressed wire is subjected to a softening treatment. Fe is contained 0.005 mass% or more and 2.2 mass% or less, and the balance consists of Al and impurities,
Conductivity is 58% IACS or higher,
An aluminum alloy characterized by an elongation of 10% or more.