KR102546527B1 - Manufacturing method of aluminum alloy wire, overhead power transmission line, and aluminum alloy wire - Google Patents

Abstract

Contains 0 mass% or more and 0.03 mass% or less of Si, 0.05 mass% or more and 0.25 mass% or less of Fe, and 0.01 mass% or more and 0.05 mass% or less of Zr, the balance being composed of Al and impurities, and having a wire diameter of more than 1.5 mm A phosphorus aluminum alloy wire is provided.

Description

Manufacturing method of aluminum alloy wire, overhead power transmission line, and aluminum alloy wire

The present invention relates to an aluminum alloy wire, an overhead transmission line, and a method for manufacturing an aluminum alloy wire.

This application claims priority based on Japanese Patent Application No. 2016-193970 filed on September 30, 2016, and uses all the description contents described in the above Japanese application.

Conventionally, in overhead power transmission lines, light aluminum wires for electricity composed of aluminum metal for electricity are twisted together as strands, or stranded aluminum wires are twisted together around the outer periphery of tension members made of steel wires. Steel core aluminum Twisted pair (ACSR) is used. In addition, a steel-core heat-resistant aluminum alloy stranded wire (TACSR) is also used, in which a heat-resistant aluminum alloy wire obtained by adding a small amount of Zr to aluminum earth for electrical use is used as a wire. The heat-resistant aluminum alloy wire has a conductivity of 60% IACS and is called 60 TAl or the like (see Patent Document 1).

Patent Document 1 discloses a heat-resistant aluminum alloy wire for conduction containing Zr, Fe, B, and Be in a specific range, and containing Zr and Fe in a range satisfying a specific relational expression.

Patent Document 1: Japanese Patent Publication No. 63-004621

The aluminum alloy wire of the present disclosure,

0 mass% or more and 0.03 mass% or less of Si,

0.05% by mass or more and 0.25% by mass or less of Fe;

Contains 0.01% by mass or more and 0.05% by mass or less of Zr,

the remainder being composed of Al and impurities,

The wire diameter is greater than 1.5 mm.

The overhead power transmission line of the present disclosure,

A twisted pair formed by combining and twisting a plurality of the aluminum alloy wires is included.

The manufacturing method of the aluminum alloy wire of this disclosure,

An aluminum alloy containing 0% by mass or more and 0.03% by mass or less of Si, 0.05% by mass or more and 0.25% by mass or less of Fe, and 0.01% by mass or more and 0.05% by mass or less of Zr, the balance being Al and impurities, is cast to form a cast material. A casting process for manufacturing;

A processing step of producing a wire rod having a wire diameter of more than 1.5 mm by subjecting the cast material to plastic working including at least one of rolling processing and wire drawing processing;

In the casting process, the cooling rate during casting is set to 5°C/sec or more.

1 is a schematic perspective view showing an example of an overhead power transmission line of an embodiment provided with an aluminum alloy wire of the embodiment.
2 is a graph showing the relationship between (5×Zr+Fe) and heat resistance for each sample prepared in Test Example 1. FIG.
3 is a graph showing the relationship between (5 × Zr + Fe + 2 × Si) and conductivity for each sample prepared in Test Example 1.

[Problems to be solved by the present disclosure]

Considering the recent power situation, further reduction of power transmission loss is required. In order to reduce power transmission loss, it is desirable to lower the electrical resistance of an overhead power transmission line or distribution line. In order to lower the electrical resistance, it is preferable to further increase the conductivity of the conductor provided in the overhead power transmission line, distribution line, or the like. In the conventional heat-resistant aluminum alloy wire for electrical conductivity described above, it cannot be said that the electrical conductivity is sufficiently high, and further improvement in electrical conductivity is required.

On the other hand, aluminum alloy wires used for conductors of overhead power transmission lines such as TACSR are required to have low strength, that is, excellent heat resistance, when the temperature rises due to heat generated during energization. However, when the content of an additive element effective for improving heat resistance, such as Zr, is increased, the conductivity tends to decrease, making it difficult to achieve both high conductivity and excellent heat resistance.

Therefore, one of the objects is to provide an aluminum alloy wire having high conductivity and excellent heat resistance in a well-balanced manner. Another object is to provide an overhead power transmission line having low electrical resistance and excellent heat resistance in a well-balanced manner. Another object is to provide a method for producing an aluminum alloy wire capable of producing an aluminum alloy wire having high conductivity and excellent heat resistance in a well-balanced manner.

[Effect of the present disclosure]

The aluminum alloy wire of the present disclosure has high conductivity and excellent heat resistance in a well-balanced manner. The overhead power transmission line of the present disclosure has low electrical resistance and excellent heat resistance in a well-balanced manner.

The aluminum alloy wire manufacturing method of the present disclosure can produce an aluminum alloy wire having high conductivity and excellent heat resistance in a well-balanced manner.

[Description of Embodiments of the Present Invention]

The inventors of the present invention found that, when Si is contained to a certain extent, concretely, when it is more than 0.03% by mass, and furthermore 0.05% by mass or more, it is easy to increase the strength, but compared with Zr and Fe, Si contributes less to the improvement of heat resistance. . On the other hand, it was found that electrical conductivity can be improved by sufficiently reducing Si. In addition, by reducing Si, it is possible to prevent Si, Zr, or Fe from forming a compound during solidification to crystallize and precipitate, and as a result of Zr and Fe being easily dissolved in Al, which is the parent phase, as a result of their solid solution, In addition to being excellent in heat resistance, the knowledge that strength was also excellent was obtained. In addition, since Zr and Fe can be suitably dissolved, even when the contents of Zr and Fe are smaller, the heat resistance and strength are somewhat higher, and the knowledge that the electrical conductivity can be further increased by reducing Zr and Fe was obtained. . The present invention is based on the above findings.

First, the embodiments of the present invention are listed and described.

(1) The aluminum alloy wire according to one aspect of the present invention,

0 mass% or more and 0.03 mass% or less of Si,

0.05% by mass or more and 0.25% by mass or less of Fe;

Contains 0.01% by mass or more and 0.05% by mass or less of Zr,

the remainder being composed of Al and impurities,

The wire diameter is greater than 1.5 mm.

The aluminum alloy wire (hereinafter sometimes referred to as Al alloy wire) contains Zr and Fe within a specific range, and contains very little Si. Therefore, the effect of improving the heat resistance by the solid solution of Zr and Fe can be obtained satisfactorily, and the heat resistance is excellent. In addition, since the Al alloy wire has a very small content of Si, it is easy to suppress the decrease in conductivity due to the inclusion of Si itself and maintain high conductivity of Al. When the content of at least one of Zr and Fe is less than the above range, the electrical conductivity can be made higher. From these, the Al alloy wire can have a higher conductivity.

Therefore, the Al alloy wire has high conductivity and excellent heat resistance in a well-balanced manner. In addition, the Al alloy wire can also obtain an effect of improving strength due to the solid solution of Fe, and is also excellent in strength. Since this Al alloy wire has a wire diameter of more than 1.5 mm and has a size suitable for conductors of wires such as overhead transmission lines, when used for conductors of wires such as overhead transmission lines, low resistance and excellent heat resistance construction of overhead transmission lines, etc. can do. The Al alloy wire can be suitably used for TACSR wire, which requires heat resistance in particular.

(2) As an example of the aluminum alloy wire,

A form in which the sum of 5 times the content of Zr and the content of Fe (5 x Zr + Fe) is 0.17% by mass or more is exemplified.

Since the above form contains Zr and Fe in a range satisfying the above specific relationship, the effect of improving heat resistance by solid solution can be obtained satisfactorily. Therefore, the above form has a high electrical conductivity and better heat resistance in a well-balanced manner.

(3) As an example of the aluminum alloy wire,

An aspect in which the sum of 5 times the content of Zr, the content of Fe, and 2 times the content of Si (5 x Zr + Fe + 2 x Si) is 0.34% by mass or less is exemplified.

Since the above embodiment contains Zr, Fe, and Si in a range that satisfies the above specific relationship, a decrease in electrical conductivity due to excessive inclusion of these elements can be suppressed, and high electrical conductivity can be obtained. Therefore, the above form has a higher electrical conductivity and excellent heat resistance in a well-balanced manner.

(4) As an example of the aluminum alloy wire,

An embodiment in which the conductivity at room temperature is 61%IACS or higher is exemplified. The room temperature is about 20°C±15°C. Hereinafter, it is the same about room temperature.

This form has a conductivity higher than 60 TAI. Therefore, the above form has a higher electrical conductivity and excellent heat resistance in a well-balanced manner.

(5) As an example of the aluminum alloy wire,

An aspect in which the residual rate of the tensile strength after heating at 230°C for 1 hour is 90% or more is exemplified.

[0025] This form has little decrease in tensile strength even at high temperatures, can maintain high tensile strength, and has excellent heat resistance. Therefore, the above form has a high electrical conductivity and better heat resistance in a well-balanced manner.

(6) As an example of the aluminum alloy wire,

A form in which the tensile strength at room temperature is equal to or higher than the average tensile strength specified for each diameter in the standard specification JEC-3406 of the Electrical Standards Survey Society of the Institute of Electrical Engineers for Heat Resistant Aluminum Alloy Wires is exemplified.

This form has strength equal to or higher than the standard value, and is excellent in strength. Therefore, in addition to having high electrical conductivity and excellent heat resistance in a well-balanced manner, the above form is also excellent in strength.

(7) As an example of the aluminum alloy wire,

An embodiment containing 0.01% by mass or more of Si is exemplified.

Since the shape contains Si within a specific range, the strength is superior to that of the case where Si does not satisfy this specific range. Therefore, in addition to having high electrical conductivity and excellent heat resistance in a well-balanced manner, the above form is also excellent in strength.

(8) An overhead power transmission line according to an aspect of the present invention,

A twisted pair formed by twisting a plurality of aluminum alloy wires according to any one of (1) to (7) above is included.

Since the overhead power transmission line includes a stranded wire portion made of the Al alloy wire having the above-described specific composition and having a high electrical conductivity and excellent heat resistance in a well-balanced manner, the electric resistance is low and the heat resistance is also excellent. Such an overhead power transmission line can be suitably used as a heat-resistant overhead power transmission line.

(9) As an example of the overhead transmission line,

An aspect including a tension member including a steel wire and the twisted pair portion formed by combining and twisting a plurality of the aluminum alloy wires around the outer periphery of the tension member is exemplified.

The above form is provided with a tension member, and can be suitably used as an overhead power transmission line having high strength.

(10) As an example of the overhead power transmission line provided with a tension member,

The tension member may include at least one of an aluminum-coated steel wire and a galvanized steel wire.

In the above configuration, aluminum coating or zinc plating is interposed between the aluminum alloy wire and the steel wire constituting the tension member, and the aluminum alloy wire and the steel wire do not directly contact each other. Therefore, corrosion deterioration of the aluminum alloy wire by galvanic corrosion can be suppressed.

(11) A method for producing an aluminum alloy wire (Al alloy wire) according to one aspect of the present invention,

An aluminum alloy containing 0% by mass or more and 0.03% by mass or less of Si, 0.05% by mass or more and 0.25% by mass or less of Fe, and 0.01% by mass or more and 0.05% by mass or less of Zr, the balance being Al and impurities, is cast to form a cast material. A casting process for manufacturing;

A processing step of producing a wire rod having a wire diameter of more than 1.5 mm by subjecting the cast material to plastic working including at least one of rolling processing and wire drawing processing;

In the casting process, the cooling rate during casting is set to 5°C/sec or more.

The method for manufacturing an Al alloy wire can produce an Al alloy wire having high conductivity and excellent heat resistance in a well-balanced productivity for the following reasons.

(heat resistance)

Since Zr and Fe are contained in a specific range and the cooling rate at the time of casting is quenched to a specific size, both elements can be dissolved satisfactorily. In particular, since the content of Si is made very small, Zr and Fe can be sufficiently dissolved even from the fact that Zr and Fe are easily dissolved in the mother phase. In addition, by not performing heat treatment such as aging treatment, it is easy to obtain an Al alloy wire in which Zr and Fe are dissolved. In addition, it is easy to make a cast material with a fine crystal structure by rapid cooling, and it is easy to finally obtain an Al alloy wire having a fine crystal structure. This is because, qualitatively, such an Al alloy wire has little decrease in strength such as tensile strength at high temperatures and is a wire rod having excellent heat resistance.

(conductivity)

This is because the decrease in conductivity due to the inclusion of Si itself can be suppressed because the content of Si is very small. It is because it is easy to suppress the fall of electrical conductivity, when content of Zr and Fe is further reduced as mentioned above.

(productivity)

This is because the Al alloy wire excellent in heat resistance and conductivity can be manufactured without separately performing heat treatment such as aging treatment.

(12) As an example of the manufacturing method of the aluminum alloy wire,

In the above processing step, cold working is included, and the form in which the wire diameter of the raw material at the start of the cold working is set to 8 mm or more and 15 mm or less is exemplified.

In the above configuration, by making the material subjected to cold working a material having the specific wire diameter, the degree of cold working from this material to the production of a wire rod having a predetermined final wire diameter can be appropriately secured, and work hardening can be performed. It is easy to obtain the strength improvement effect by Therefore, the above form has high conductivity and excellent heat resistance in a well-balanced manner, and a high-strength Al alloy wire can be manufactured.

[Details of the embodiment of the present invention]

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described concretely. Content of an element represents mass % unless otherwise stated.

[Aluminum alloy wire]

(Furtherance)

The aluminum alloy wire (Al alloy wire) of the embodiment is a wire rod suitable for conductors such as electric wires, and is characterized in that it is composed of an aluminum alloy (Al alloy) of a specific composition containing Zr and Fe as essential elements and appropriately containing Si. to be one of The Al alloy is a heat-resistant Al alloy containing 0% or more and 0.03% or less of Si, 0.05% or more and 0.25% or less of Fe, and 0.01% or more and 0.05% or less of Zr, the balance being composed of Al and impurities. The said impurity means an unavoidable thing. First, each additive element is explained in detail.

·Fe

Fe in the Al alloy is mainly dissolved in Al, which is the parent phase, and functions as a solid solution strengthening element. The solid solution of Fe can increase the strength called tensile strength at room temperature. In addition, the solid solution of Fe makes it difficult for the tensile strength to decrease at high temperatures, contributing to the improvement of heat resistance. A part of Fe is allowed to exist as a compound with Al (precipitates such as Al ₃ Fe and Al ₆ Fe). This is because it is thought that the precipitate containing Fe contributes to precipitation strengthening.

When 0.05% or more of Fe is contained, the effect of improving the strength by solid solution and the effect of improving the heat resistance are easily obtained, and an Al alloy wire having high strength and excellent heat resistance can be obtained. The higher the Fe content, the higher the strength and heat resistance tend to be, and when high strength or heat resistance improvement is required, the Fe content can be 0.08% or more, further 0.09% or more, or 0.1% or more.

When Fe is contained in the range of 0.25% or less, it is easy to suppress the decrease in conductivity due to dissolved Fe or a compound containing Fe, and it can be set as an Al alloy wire with high conductivity. When high conductivity or the like is required, the Fe content can be 0.2% or less, and further 0.15% or less.

·Zr

Zr contributes to the improvement of heat resistance in particular. In detail, Zr exists mainly as a solid solution in Al, which is the parent phase, and contributes to maintaining high strength even at high temperatures by suppressing a decrease in strength at high temperatures.

When 0.01% or more of Zr is contained, it contributes favorably to the above-described improvement in heat resistance, and an Al alloy wire having excellent heat resistance can be obtained. The higher the Zr content, the better the heat resistance, and when further improvement of the heat resistance is required, the Zr content can be 0.015% or more, further 0.017% or more, or 0.02% or more.

When Zr is contained in the range of 0.05% or less, a decrease in electrical conductivity due to an increase in the amount of solid solution of Zr can be suppressed, and an Al alloy wire having high electrical conductivity can be obtained. When a high conductivity or the like is required, the content of Zr can be 0.04% or less, and further 0.03% or less.

・Relationship between Zr and Fe

In addition to the content of Zr and Fe satisfying the specific ranges described above, it is preferable because heat resistance is excellent when both elements satisfy a specific relationship. Specifically, when the sum of 5 times the Zr content and the Fe content is (5 × Zr + Fe), it is preferable that this sum (5 × Zr + Fe) satisfies 0.17% or more in terms of mass ratio. do. This sum (5 × Zr + Fe) is based on Patent Document 1.

When the above sum (5 × Zr + Fe) is 0.17% or more, Zr and Fe can be favorably dissolved in the parent phase, and the Al alloy wire has excellent heat resistance, typically Al having a residual rate of tensile strength of 90% or more, which will be described later. It can be done with alloy wire. The larger the sum (5×Zr+Fe) is, the better the heat resistance tends to be. When further improvement in heat resistance or the like is required, the above sum (5 × Zr + Fe) can be set to 0.18% or more, and further to 0.182% or more, 0.19% or more, or 0.20% or more.

·Si

The Al alloy constituting the Al alloy wire of the embodiment has a Si content of 0% from the viewpoint of further improving the electrical conductivity, and can be made in a form that does not contain Si. Compared with Zr and Fe, Si does not have a high effect of improving heat resistance. Conversely, when Si is not included, since Zr and Fe are not consumed to form a compound with Si and can be sufficiently dissolved in the parent Al, the effect of improving strength and improving heat resistance by solid solution of Zr and Fe It is thought that a favorable effect can be obtained. Therefore, the form which does not contain Si can have a high electrical conductivity and excellent heat resistance with a good balance.

On the other hand, removing Si by the current refining technology or the like takes a very long time. Therefore, an increase in cost is also likely to be caused. Considering industrial mass production, those containing Si, that is, the form in which the content of Si exceeds 0% is easy to use. Moreover, when Si is contained, the improvement of strength called tensile strength can be desired.

When 0.01% or more of Si is contained, it is easy to obtain the effect of improving the strength by the solid solution of Si, the content of Si is easy to adjust, and the productivity is excellent. The higher the content of Si, the easier it is to improve the strength and the easier it is to adjust the content. When high strength, good manufacturability, and the like are required, the Si content can be 0.012% or more, further 0.013% or more, or 0.015% or more.

When Si is contained, if the Si content is 0.03% or less, as described above, the decrease in electrical conductivity is suppressed, the consumption of Zr or Fe due to the formation of a compound of Si and Zr or Fe is reduced (Zr or Fe suppression of solid solution inhibition), and it is easy to obtain an Al alloy wire having high conductivity and excellent heat resistance. When high conductivity, high heat resistance, etc. are required, the Si content can be made less than 0.03%, further less than 0.025%, less than 0.024%, less than 0.023%, and more preferably 0.020% or less.

・Relationship between Zr, Fe and Si

When Si is included in the above range (when it exceeds 0%), when the contents of Zr, Fe, and Si satisfy the above-mentioned specific range, and these three elements satisfy the specific relationship, it is easy to have high electrical conductivity. desirable. Specifically, when the sum of five times the Zr content, the Fe content, and twice the Si content is (5 × Zr + Fe + 2 × Si), this sum (5 × Zr + Fe + 2 x Si) preferably satisfies 0.34% or less in terms of mass ratio. The method by which this sum is required will be described later.

When the sum (5 × Zr + Fe + 2 × Si) is 0.34% or less, an increase in the solid solution of Zr and Fe is suppressed, a decrease in conductivity due to the content of Si is suppressed, and an Al alloy wire having high conductivity can be obtained. can When a high conductivity or the like is required, the above sum (5 × Zr + Fe + 2 × Si) can be 0.33% or less, further 0.31% or less, or 0.30% or less.

·group

As the structure of the Al alloy constituting the Al alloy wire of the embodiment, a structure in which Fe and Zr are mainly solid-dissolved is exemplified. Further, as the structure of the Al alloy, a fine crystal structure is exemplified. As will be described later, a cast material having a fine crystal structure is obtained by quenching at a specific rate during casting. By subjecting this cast material to plastic working such as rolling or wire drawing to produce an Al alloy wire, the Al alloy wire tends to have a fine crystal structure. Precipitates containing a part of Fe and Al are allowed to exist in a uniformly dispersed manner.

(characteristic)

·Heat resistance

The Al alloy wire of the embodiment is excellent in heat resistance. Quantitatively, the aspect in which the residual rate of the tensile strength after heating at 230 degreeC for 1 hour is 90% or more is mentioned. The residual ratio is [tensile strength after heating/tensile strength at room temperature] x 100 (%). The higher the residual ratio, the lower the decrease in strength at high temperatures and the better the heat resistance. Therefore, 91% or more, more preferably 92% or more, and 93% or more are more preferable.

·robbery

The Al alloy wire of the embodiment has high strength. Quantitatively, a form in which the tensile strength at room temperature is equal to or higher than the average tensile strength specified for each diameter in the standard JEC-3406 of the Electrical Standards Survey Society of the Institute of Electrical Engineers for Heat Resistant Aluminum Alloy Wires is exemplified. Specifically, the following is mentioned.

When the wire diameter is 2.6 mm or more and less than 3.2 mm; 179 MPa or more

When the wire diameter is 3.2 mm or more and less than 3.7 mm; 172 MPa or more

When the wire diameter is 3.7 mm or more and less than 4.0 mm; 169 MPa or more

When the wire diameter is 4.0 mm or more and 5.0 mm or less; 165 MPa or more

The higher the average tensile strength, the higher the remaining tensile strength is likely to be, even if the strength decreases at high temperatures. When high strength or the like is required, the tensile strength of the Al alloy wire can be set to the above average tensile strength +3 MPa or more and the above average tensile strength +5 MPa or more.

·Conductivity

The Al alloy wire of the embodiment is excellent in conductivity. Quantitatively, a form in which the conductivity at room temperature satisfies 61% IACS or more is exemplified. Since the higher the conductivity is, the easier the electrical resistance is to be lowered and the power transmission loss can be reduced, which is preferable. Therefore, the conductivity can be set to 61.1%IACS or higher, furthermore 61.2%IACS or higher, or 61.3%IACS or higher.

The heat resistance (residual rate of the above-mentioned tensile strength), tensile strength, conductivity, etc. can be adjusted to a predetermined size by adjusting the composition and manufacturing conditions. For example, when the added elements are increased, the heat resistance and tensile strength tend to be high, and the electrical conductivity tends to be low. For example, when the cooling rate at the time of casting is increased (if made quickly), heat resistance and tensile strength tend to increase. For example, when the degree of processing is increased, the tensile strength tends to increase.

(size)

Representatively, the Al alloy wire of the embodiment can be made into various wire diameters by adjusting the working degree such as the wire drawing degree (area reduction ratio) in the manufacturing process. Depending on the application (described later), the wire diameter (cross-sectional area) can be appropriately selected. In particular, by setting the wire diameter of the Al alloy wire of the embodiment to more than 1.5 mm, it is suitable for conductors of heat-resistant overhead power transmission lines such as TACSR. The standard wire diameter of TACSR is, for example, 2.3 mm or more and 5.0 mm or less. In addition, as a representative shape of the Al alloy wire of the embodiment, a round wire having a circular cross-sectional shape is exemplified.

(Usage)

The Al alloy wire of the embodiment can be used for electric wires, particularly bare wires such as overhead power transmission lines and coated wires such as distribution wires. Since the Al alloy wire of the embodiment is excellent in both conductivity and heat resistance as described above, it can be suitably used for electric wires for applications requiring heat resistance, typically for strands of heat-resistant overhead power transmission lines such as TACSR.

[Overhead Transmission Line]

As shown in FIG. 1 , the overhead power transmission line 1 of the embodiment includes a twisted pair portion 2 formed by twisting a plurality of Al alloy wires 12 of the embodiment together. A representative example of the overhead power transmission line 1 is a concentric twisted wire formed by concentric twisting of a plurality of strands (an Al alloy wire 12 in FIG. 1 and a steel wire 13 described later). As an example of the overhead power transmission line 1, a concentric stranded wire in which all of the strands are Al alloy wires 12 is exemplified. As another example of the overhead power transmission line 1, as shown in FIG. 1, a twisted pair formed by providing a tension member 3 in the center and twisting a plurality of Al alloy wires 12 together around the outer circumference of the tension member 3 A concentric twisted pair provided with section 2 is exemplified. The bare wire constituting the tension member 3 includes at least one type of steel wire 13 of a bare steel wire, an aluminum-coated steel wire, and a galvanized steel wire. The wire diameter (exceeding 1.5 mm) and number of strands of the Al alloy wire 12 constituting the stranded wire portion 2, the wire diameter and number of strands of the strands such as the steel wire 13 constituting the tension member 3, etc. are determined conductors It can be appropriately selected to have a cross-sectional area, tensile load, and the like.

When the tension member 3 is not provided, if the outer diameter or cross-sectional area of the electric wire is kept constant, the conductor cross-sectional area can be secured larger than when the tension member 3 is provided. In the case where the tension member 3 is provided, since the tensile load is large compared to the case where the tension member 3 is not provided, the tension at the time of wiring can be increased. By being able to increase the tension at the time of wiring, it is possible to reduce the separation (relaxation) of the electric wire. Since the ear canal can be made small, it is possible to secure a large isolation distance between the electric wire and the ground and any building erected on the ground. When the tension member 3 includes at least one of an aluminum-coated steel wire and a galvanized steel wire, aluminum coating and zinc plating are interposed between the Al alloy wire 12 and the steel wire, so an Al alloy wire by galvanic corrosion Corrosion deterioration of (12) can be suppressed.

The overhead power transmission line 1 of the embodiment can be used for a power transmission line. In particular, since the overhead power transmission line 1 of the embodiment has low electrical resistance and excellent heat resistance as described above, it can be suitably used for an overhead power transmission line that requires excellent heat resistance.

[Main effect]

Since the Al alloy wire of the embodiment is composed of an Al alloy of a specific composition, it can have a heat resistance equal to or higher than that of the prior art while having a higher conductivity than the prior art, and has a high conductivity and excellent heat resistance in a well-balanced manner. This effect is specifically demonstrated in Test Example 1.

Since the overhead power transmission line 1 of the embodiment includes the Al alloy wire 12 having high electrical conductivity and excellent heat resistance in a well-balanced manner, it has low electrical resistance and excellent heat resistance, and has low electrical resistance and excellent heat resistance in a well-balanced manner. do. This effect is specifically demonstrated in Test Example 2.

[Method of manufacturing aluminum alloy wire]

The Al alloy wire of embodiment can be manufactured according to the manufacturing method of the aluminum alloy wire (Al alloy wire) of embodiment including the following casting process and a processing process, for example. An outline of this manufacturing method is given, after casting the Al alloy of the specific composition described above, plastic working is performed on the cast material to form a wire rod. In particular, the cooling rate during casting is quenched within a specific range. In addition, the method for producing the Al alloy wire of the embodiment can produce the Al alloy wire of the embodiment having a high conductivity and excellent heat resistance without separately performing a heat treatment such as aging treatment after casting, and is also excellent in manufacturability .

(Casting step) An aluminum alloy containing 0% or more and 0.03% or less of Si, 0.05% or more and 0.25% or less of Fe, and 0.01% or more and 0.05% or less of Zr, the balance being composed of Al and impurities, is cast to produce a cast material. do.

(Machining Step) A wire rod having a wire diameter of more than 1.5 mm is manufactured by subjecting the cast material to plastic working including at least one of rolling processing and wire drawing processing.

In the casting process, the cooling rate during casting is set to 5°C/sec or more.

Hereinafter, each process is demonstrated.

(casting process)

In this process, raw materials are prepared, molten metal of an Al alloy having a specific composition is produced, and this molten metal is used for casting. In particular, in order to dissolve Zr and Fe in Al during casting to form a supersaturated solid solution, the amount of Si is adjusted and the cooling rate is increased as described above.

The raw material includes, for example, at least one of aluminum ingot for electrical use (hereinafter referred to as Al ingot), a master alloy containing Al and an additive element, and an additive element alone. In particular, when Al braze is used that has a very small amount of impurities and high Al purity, for example, one with an Al content of more than 99.65%, further 99.9% or more, or 99.92% or more, etc., the content of Zr, Fe, or Si can be determined with high precision. Easy to adjust, suitable for mass production. In the case of using Al ingot with a certain degree of low Al purity, the content of each of the above-mentioned additive elements can be adjusted with high precision by appropriately performing refining, but it may be inferior in terms of mass production, such as taking time.

By setting the cooling rate during casting (here, the cooling rate from the hot water temperature to at least about 400° C.) to 5° C./sec or more, the solid solution ratio of the additive element (especially Fe) can be increased. As a result, even if the contents of Zr and Fe are within the above-mentioned range or less than the above-mentioned range, the effect of improving heat resistance and strength due to the solid solution of Zr and Fe can be obtained satisfactorily. The higher (faster) the cooling rate is, the easier it is to maintain a solid solution state. Therefore, the cooling rate is preferably 6°C/sec or higher, more preferably 6.5°C/sec or higher, and 7°C/sec or higher. If the cooling rate is adjusted as described above, the casting method is not particularly limited. In the case of mass production, a continuous casting method can be suitably used. As the continuous casting method, various methods such as a method using a movable mold such as a belt and wheel method and a method using a fixed mold can be used.

In addition, as the cooling rate is higher, a cast material having a finer crystal structure is obtained. When such a cast material is subjected to a processing step, the obtained wire rod also tends to have a fine crystal structure.

(Manufacturing process)

In this step, as described above, plastic working is performed on the cast material in which the additive elements are sufficiently dissolved, to produce a wire rod having a predetermined wire diameter. In particular, in the Al alloy wire manufacturing method of the embodiment, since the aging treatment is not performed at any time before, during, or after this processing, the solid solution state is easily maintained, and the effect of improving the strength by work hardening is easy to obtain. In addition, since the content of the additive element is within a specific range, a decrease in electrical conductivity due to solid solution of the additive element can be suppressed. Therefore, an Al alloy wire having excellent conductivity, heat resistance and strength can be manufactured with good productivity. In addition, by reducing the content of Si and also reducing the content of Zr and Fe, it is difficult to form a coarse compound, it is easy to reduce wire breakage caused by coarse compound particles, and the Al alloy wire can be produced with high productivity. there is.

The plastic working performed in the processing step includes at least one of rolling processing and drawing processing. Further, this plastic working includes at least one of hot working and cold working. In the case of using the continuous casting method, for example, rolling and wire drawing are sequentially performed on the continuous cast material, and the rolling is hot working and the wire drawing is cold working. When hot working is performed continuously after continuous casting, it is easy to maintain a solid solution state by using the heat remaining in the cast material, and reheating equipment is not required, and the manufacturability is excellent. For example, it is possible to use a continuous casting and rolling device in which a rolling mill is attached to a belt-and-wheel type continuous casting machine.

In the case of hot rolling, the higher the rolling temperature, the better the workability. The lower the rolling temperature, the easier it is to maintain the solid solution state, the larger the amount of deformation in processing, and the easier it is to increase the strength. When high heat resistance or high strength is required, for example, setting the rolling start temperature to about 250°C or higher and 550°C or lower is exemplified. In the case of using a casting method other than continuous casting or cold working in processing other than hot working, it is easy to maintain the solid solution state, increase the amount of processing deformation, and increase the strength.

In the case of performing wire drawing, one or more passes of wire drawing are performed until the final wire diameter is determined, such as a cast material or a rolled material subjected to the above-mentioned rolling processing. This wire drawing can be made into cold working. What is necessary is just to select the number of passes, the degree of processing per pass, the degree of total processing, etc. according to the final wire diameter. The wire rod (new wire rod, etc.) having the obtained final wire diameter becomes the Al alloy wire of the above-described embodiment.

The degree of workability (surface reduction rate) in the machining process, particularly in the case of including cold working, the greater the degree of cold working, the greater the amount of machining deformation and the easier it is to increase the strength. On the other hand, as the degree of processing increases, it is easy to cause a decrease in electrical conductivity due to processing deformation and a decrease in heat resistance due to precipitation of solid solution elements. For example, in the case of producing a wire having a predetermined final wire diameter (in this case, more than 1.5 mm) from a material (eg, hot worked material, etc.) subjected to cold working, the wire diameter at the start of cold working is 8 mm or more and 15 mm or less It can be heard that In this case, it is possible to manufacture an Al alloy wire having high conductivity and excellent heat resistance in a well-balanced manner while ensuring the degree of cold working appropriately and obtaining a good strength improvement effect by work hardening. The wire diameter at the start of cold working may be 9 mm or more, further 10 mm or more, or 14 mm or less, or 13 mm or less, depending on the final wire diameter.

The aluminum alloy wire manufacturing method of the embodiment can be used for manufacturing the aluminum alloy wire constituting the conductor of the electric wire described above.

[Test Example 1]

Aluminum alloy wires of various compositions were produced as follows, and their characteristics were investigated.

As raw materials, Al metal (99.9% by mass or more Al) and a master alloy (Zr-containing Al alloy, Fe-containing Al alloy, Si-containing Al alloy) are prepared and melted to produce an Al alloy molten metal. did Table 1 shows the composition of the Al alloy (the balance being Al and unavoidable impurities).

The obtained molten metal was continuously cast to produce a cast material (here, 3600 mm 2 ). Table 1 shows the cooling rate (°C/sec) during continuous casting. Samples No.1-14, No.1-105, and No.1-106 were adjusted to reduce the amount of cooling water compared to the other samples, thereby reducing the cooling rate. In this test, using a belt and wheel type continuous casting and rolling device, the obtained cast material was continuously subjected to rolling processing (including hot rolling) to produce a continuously cast rolled material (here, φ 9.5 mm). The obtained continuously cast rolled material was subjected to wire drawing (cold, area reduction 95.6%, 88.7%, or 72.3%) to obtain a wire having a final wire diameter (2.0 mm, 3.2 mm, or 5.0 mm) shown in Table 1.

About the obtained wire rod, electrical conductivity (%IACS), tensile strength at room temperature (MPa), and heat resistance (%) were investigated. The results are shown in Table 1.

The electrical conductivity was measured by the direct current 4-terminal method. Here, a commercially available electrical resistance measuring device was used. The measurement was carried out at room temperature (about 20°C here), and the gauge length (GL) was set to 500 mm.

Tensile strength was measured using a general-purpose tensile tester in accordance with JIS Z 2241 (Tensile test method for metallic materials, 1998). The measurement was conducted at room temperature (about 20°C here), and the gauge length (GL) was set to 100 mm.

Heat resistance was evaluated by the residual percentage (%) of the following tensile strength.

Here, the wire rod of each sample is heated to 230 ± 1 ° C using an electric furnace (temperature elevation time is within 20 minutes), maintained at 230 ° C for 1 hour, then cooled to room temperature (here, about 20 ° C), , The tensile strength after this heating was measured in the same manner as in the method for measuring the tensile strength at room temperature described above. Then, [tensile strength after heating/tensile strength at room temperature] x 100 (%) was used as the residual ratio. It is excellent in heat resistance, so that this residual ratio is large.

As shown in Table 1, it can be seen that all of Sample Nos. 1-1 to No. 1-14 have high conductivity and excellent heat resistance in a well-balanced manner compared to Samples No. 1-101 and No. 1-102. there is. Quantitatively, sample Nos. 1-1 to No. 1-14 satisfy electrical conductivity of 61% IACS or more and heat resistance of 90% or more. Among sample Nos. 1-1 to No. 1-14, most of the samples had a conductivity of 61% IACS or more and a heat resistance of 90.2% or more, and many samples had 90.5% or more, and moreover 91.5% or more. In addition, it can be seen that all samples No. 1-1 to No. 1-14 are excellent in strength at room temperature. Quantitatively, samples No.1-1 to No.1-14 are all average values specified in the standard JEC-3406 of the Electrical Standards Survey Society of the Institute of Heat-Resistant Aluminum Alloy Wires (e.g., 172 MPa for a sample with a wire diameter of 3.2 mm) ), there are samples with an average value of +5 MPa or more, and samples with an average value of +10 MPa or more.

As one of the reasons why the above results were obtained, samples No. 1-1 to No. 1-14 had Zr and Fe contents in the above-mentioned specific ranges, and Si contents were 0.03 mass% or less, in this case less than 0.025 mass%, and furthermore 0.024 mass % or less, and most samples are less than 0.023 mass %.

In addition, from this test, when the content of Si is 0.03% by mass or less, when Fe and Zr are contained in a range satisfying a specific relationship, it is found that the heat resistance is excellent. Fig. 2 is a graph showing the relationship between the sum (5xZr+Fe) and heat resistance for samples No.1-1 to No.1-11 and samples No.1-101 to No.1-104. The horizontal axis represents the sum of 5 times the Zr content and the Fe content (5 × Zr + Fe) (mass %), and the left vertical axis represents heat resistance (%). Sample No.1-1 to No.1-11 and Sample No.1-101 to No.1-104 are samples having substantially the same cooling rate during casting, the same wire diameter, and substantially the same manufacturing conditions.

As shown in the graph of Fig. 2, the sum of samples No. 1-1 to No. 1-11 (5 x Zr + Fe) is in the range of more than 0.148 mass%, particularly in the range of 0.17 mass% or more as indicated by the broken line. know that it exists. Therefore, in order to have excellent heat resistance (90% or more), it was found that it is preferable that the contents of Zr, Fe, and Si satisfy a specific range, and the sum (5 × Zr + Fe) satisfies 0.17% by mass or more.

In addition, from this test, when the content of Si is 0.03% by mass or less, when Fe, Zr, and Si are contained in a range satisfying a specific relationship, it is found that the conductivity is excellent. 3 is a graph showing the relationship between the sum (5 × Zr + Fe + 2 × Si) and the conductivity for sample No.1-1 to No.1-11 and sample No.1-101 to No.1-104 am. The horizontal axis represents the sum of five times the Zr content, the Fe content, and twice the Si content (5 × Zr + Fe + 2 × Si) (mass %), and the left vertical axis represents the conductivity (% IACS).

The sum (5 × Zr + Fe + 2 × Si) was obtained by substitution method based on the sum (5 × Zr + Fe) shown in FIG. 2 . Specifically, assuming the sum (5 × Zr + Fe + α × Si) when the coefficient of Si is α, and substituting α every 0.5 to find the relationship with the conductivity, a high conductivity (61% IACS or more) is obtained. The obtained value was obtained.

As shown in the graph of Fig. 3, the sum of sample Nos. 1-1 to No. 1-11 (5 x Zr + Fe + 2 x Si) is less than 0.381% by mass, particularly 0.34 mass as indicated by the broken line. It turns out that it exists in the range of % or less. Therefore, in order to have high conductivity (61%IACS or more), it is preferable that the contents of Zr, Fe, and Si satisfy a specific range, and the sum (5 × Zr + Fe + 2 × Si) satisfies 0.34 mass% or less. something appeared

Samples No.1-11 and No.1-14 with the same composition and different cooling rates during casting were compared with Samples No.1-105 and No.1-106. From these comparisons, it can be seen that an aluminum alloy wire having a well-balanced high conductivity and excellent heat resistance as described above can be produced by making the Al alloy the specific composition described above and increasing the cooling rate during casting. . Quantitatively, it can be said that the cooling rate is preferably 5°C/sec or more, and more preferably 7°C/sec or more.

Attention is paid to sample No. 1-11 to No. 1-13 having the same composition and different degrees of processing. From these samples, it can be seen that aluminum alloy wires having high conductivity and excellent heat resistance in a well-balanced manner can be produced even when the degree of cold working (final wire diameter) is made different. Further, from these samples, it can be seen that the higher the degree of wire drawing (the smaller the wire diameter), the better the strength, and the smaller the degree of wire drawing (the larger the wire diameter), the better the heat resistance tends to be.

In addition, from this test, the following can be said about heat resistance.

(1) When 0.019% by mass or more of Zr and 0.11% by mass or more of Fe are included, the heat resistance is 93% or more and the heat resistance is more excellent (Sample No.1-1 to No.1-3, No.1- 6, No.1-10).

(2) When the amount of Zr is in the range of 0.05% by mass or less, the heat resistance is excellent even when the amount of Fe is somewhat small (sample No. 1-7).

(3) When Fe is large in the range of 0.25% by mass or less, heat resistance is excellent even when Zr is small to some extent (sample No. 1-8).

[Test Example 2]

A plurality of Al alloy wires produced in Test Example 1 were combined and twisted to produce a stranded wire, and the characteristics were investigated.

In this test, Al alloy wires (sample No.1-1 to No.1-11, No.1-14, and No.1-101 to No.1-106) with a wire diameter of 3.2 mm were prepared, and the conductor cross-sectional area The following different stranded wires a to c were produced.

Stranded wire a has a conductor cross-sectional area of 300 mm 2 and assumes a heat-resistant aluminum alloy stranded wire (TAl). Stranded wire a is a concentric twisted wire using 37 Al alloy wires with a wire diameter of 3.2 mm and twisted concentrically.

The stranded wire b assumes a TACSR having a conductor cross-sectional area of 240 mm 2 , having a tension member in the center, and having a stranded portion of Al alloy wire on the outer periphery thereof. The tension member is a concentric stranded wire by concentric twist using seven galvanized steel wires with a wire diameter of 3.2 mm. Stranded wire b is formed by twisting together 30 Al alloy wires with a wire diameter of 3.2 mm around the outer circumference of the tension member (see also FIG. 1).

Stranded wire c is an aluminum-coated steel wire made of the wire of the tension member in the twisted wire b.

For the obtained stranded wires a to c, electrical resistance (Ω/km), tensile load at room temperature (kN), and heat resistance (kN) were investigated. The measurement results of twisted wire a to twisted wire c are shown in Tables 2 to 4, respectively.

Electrical resistance (Ω/km) was measured according to the 4-terminal method. The measurement was conducted at room temperature (20°C in this case), and the gauge length (GL) was set to 1 m.

Tensile load (kN) was measured in accordance with the standard JEC-3404 of the Electrical Standards Investigation Society of the Institute of Electrical Engineers for Heat Resistant Aluminum Alloy Wires.

Heat resistance was evaluated by the following tensile load (kN) after heating.

Here, the stranded wires a to c of each sample are carried out in the same way as in Test Example 1, held at 230°C for 1 hour, and then cooled to room temperature (approximately 20°C in this case). After cooling, the tensile load of each sample was measured based on JEC-3404 described above. It is excellent in heat resistance, so that the tensile load after this heating is large.

As shown in Tables 2 to 4, samples No.1-1 to No.1-12, No.1-14, No.2-1 to No.2-12, No.2-14, No.3 -1 to No.3-12, No.3-14 stranded wires (hereinafter referred to as stranded wire a to c sample groups) are samples No.1-101 to No.1-106, No.2-101 to No. Compared with the stranded wires of No.2-106 and No.3-101 to No.3-106, respectively, it is found that low electrical resistance, high tensile load and excellent heat resistance are provided in a well-balanced manner.

Quantitatively, as shown in Table 2, the stranded wire a sample group had an electrical resistance of 0.0968 Ω/km or less, a tensile load at room temperature of 46.7 kN or more, and a tensile load after heating at 230°C for 1 hour of 42.8 kN. More than that. The stranded wire a sample group had a residual ratio of the tensile load after heating to the initial tensile load (tensile load at room temperature) of 90% or more, furthermore 91% or more, and 91.5% or more, indicating excellent heat resistance.

As shown in Table 3, the stranded wire b sample group has an electrical resistance of 0.116 Ω/km or less, a tensile load at room temperature of 104.7 kN or more, and a tensile load after heating at 230°C x 1 h of 101.5 kN or more. The stranded wire b sample group had the aforementioned tensile load residual ratio of 95% or more, furthermore 96% or more, and 96.5% or more, and it was found that the heat resistance was excellent.

As shown in Table 4, the twisted pair c sample group has an electrical resistance of 0.110 Ω/km or less, a tensile load at room temperature of 104.7 kN or more, and a tensile load after heating at 230°C x 1 h of 101.2 kN or more. The stranded wire c sample group had the aforementioned tensile load residual ratio of 95% or more, furthermore 96% or more, and 96.5% or more, and it was found that the heat resistance was excellent.

As a reason for these results, the stranded wire a to c sample groups had high conductivity, high tensile strength at room temperature, and Al of samples No. 1-1 to No. 1-12 and No. 1-14, which were also excellent in heat resistance. It is thought that this is because an alloy wire is provided.

In addition, the following can be found from this test.

(1) Since the conductor cross-sectional area of the stranded wire a sample group is larger than that of the stranded wire b and c sample groups, the electrical resistance is lower.

(2) Since the stranded wire b and c sample groups are equipped with tension members, the tensile load at room temperature and after the aforementioned heating is higher than that of the twisted wire sample group a, and has high strength.

(3) Since the stranded wire c sample group was provided with an aluminum-coated steel wire, the electrical resistance was lower than that of the stranded wire b sample group.

Test Examples 1 and 2 showed that an aluminum alloy wire made of an aluminum alloy of a specific composition containing Si, Fe, and Zn in a specific range was compatible with high conductivity and excellent heat resistance. Moreover, it was shown that the overhead power transmission line using this aluminum alloy wire as a single wire can achieve both low electrical resistance and excellent heat resistance.

This invention is not limited to these examples, it is shown by the claim, and it is intended that all the changes within the meaning and range equivalent to a claim are included.

For example, the composition of the aluminum alloy in Test Example 1, the wire diameter, the manufacturing conditions such as the cooling rate during casting, the composition of the wire used for the stranded wire in Test Example 2, the wire diameter, the number of wires, etc. can be appropriately changed.

1: overhead transmission line
2: twisted pair
3: Tension member
12: aluminum alloy wire (Al alloy wire)
13: steel wire

Claims (12)

0.01% by mass or more and less than 0.03% by mass of Si;
0.05% by mass or more and 0.25% by mass or less of Fe;
Contains 0.01% by mass or more and 0.05% by mass or less of Zr,
the remainder being composed of Al and impurities,
The wire diameter is greater than 1.5 mm,
The sum of 5 times the content of Zr and the content of Fe (5 × Zr + Fe) is 0.17% by mass or more,
The sum of five times the Zr content, the Fe content, and twice the Si content (5 × Zr + Fe + 2 × Si) is 0.34 mass% or less,
The conductivity at room temperature is 61% IACS or more,
An aluminum alloy wire having a residual rate of tensile strength of 90% or more after heating at 230°C for 1 hour. The aluminum alloy wire according to claim 1, wherein the tensile strength at room temperature is greater than or equal to the average tensile strength specified for each diameter according to the standard JEC-3406 of the Electrical Standards Survey Society of the Institute of Heat-Resistant Aluminum Alloy Wires. An overhead transmission line comprising a twisted pair formed by twisting a plurality of the aluminum alloy wires according to claim 1 together. The overhead power transmission line according to claim 3, comprising: a tension member comprising a steel wire; and the twisted pair portion formed by combining and twisting a plurality of the aluminum alloy wires around the outer periphery of the tension member. The overhead power transmission line according to claim 4, wherein the tension member includes at least one of an aluminum-coated steel wire and a galvanized steel wire. It contains 0.01 mass % or more and less than 0.03 mass % of Si, 0.05 mass % or more and 0.25 mass % or less of Fe, and 0.01 mass % or more and 0.05 mass % or less of Zr, the balance being composed of Al and impurities, five times the content of Zr. and the sum of the Fe content (5 × Zr + Fe) is 0.17 mass% or more, the sum of 5 times the Zr content, the Fe content and twice the Si content (5 × Zr + Fe + 2 A casting step of producing a cast material by casting an aluminum alloy in which x Si) is 0.34% by mass or less;
A processing step for producing a wire rod having a wire diameter of more than 1.5 mm and a conductivity of 61% IACS or more at room temperature by subjecting the cast material to plastic working including at least one of rolling processing and wire drawing processing.
Including, in the casting process, the cooling rate during casting is 5 ° C. / sec or more, the manufacturing method of the aluminum alloy wire. The method for producing an aluminum alloy wire according to claim 6, wherein cold working is included in the working step, and the wire diameter of the raw material at the start of the cold working is set to 8 mm or more and 15 mm or less. delete delete delete delete delete

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