JPH09227970A - Production of high tensile conductive copper alloy and conductor for electric wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a high tensile conductive copper alloy capable of obtaining a conductor for an electric wire having high strength and high elongation and excellent in bending resistance while expensive nickel and complicated solution treatment are eliminated. SOLUTION: This copper alloy has a compsn. contg., by weight, 0.05 to 0.25% magnesium, 0.1 to 0.6% tin, 0.02 to 0.08% phosphorus, 0.02 to 0.2% indium, 0.05 to 0.1% tellurium, and the balance copper, and in which the ratio of the tin content to the total content of magnesium and tellurium is regulated to >=1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a conductor for an electric wire which is excellent in tensile strength, elongation and bending resistance, and a high-strength copper alloy for conduction.

[0002]

2. Description of the Related Art In the fields of automobiles and airplanes, the electric wires used are also required to be lightweight. In particular, in automobiles, the on-board devices have been remarkably computerized recently, and the number of wiring circuits inside the vehicle has increased accordingly, which causes a problem that the occupied space and weight of these electric wires increase. Among electric wires for automobiles, an electric wire used for a minute current circuit uses a conductor (soft copper wire) thicker than an electrically required diameter in order to secure mechanical strength. Here, a hard copper wire has been studied as one that can secure mechanical strength even if the conductor diameter is reduced in order to reduce the weight of the electric wire. However, this hard copper wire has a drawback that it is inferior in reliability because breakage is apt to occur at the terminal crimping portion because the elongation is extremely small.

On the other hand, the present inventors have found that a nickel-silicon-indium-tin-copper alloy (hereinafter referred to as "Ni-Si-
In-Sn copper alloy ") (Japanese Patent Laid-Open No. 3-6873).
No. 4). In this product, nickel and silicon which are solid-dissolved in the copper matrix are finely precipitated by the aging treatment, and as a result, the tensile strength, the elongation and the electrical conductivity are excellent. However, since expensive nickel is used in an amount of 2 to 4% by weight, the material cost is high to actually use it as a conductor of an electric wire. Further, since it is an aging effect type alloy, equipment for solution treatment is required in addition to ordinary electric wire production equipment. Further, it has a drawback that it is sensitive to the heat treatment temperature and its characteristics are likely to vary, and in order to prevent this, sophisticated and expensive temperature control management equipment is required.

[0004]

DISCLOSURE OF THE INVENTION The present invention has the above-mentioned problems of the prior art, that is, high strength, high elongation, and excellent bending resistance without requiring expensive nickel and complicated solution treatment. An object of the present invention is to provide a high-strength copper alloy for electric conduction, which can obtain a conductor for electric wires.

[0005]

In order to solve the above-mentioned problems, the high-strength copper alloy for electroconductivity according to the present invention comprises, as set forth in claim 1, 0.05% by weight or more and 0.25% by weight of magnesium.
Below, 0.1% by weight or more and 0.6% by weight or less of tin, 0.02% by weight or more and 0.08% by weight or less of phosphorus, 0.02% by weight or more and 0.2% by weight or less of indium, and 0 of tellurium. .0
The content is 5 wt% or more and 0.1 wt% or less, the balance is copper, and the ratio of the tin content to the sum of the magnesium content and the tellurium content is 1 or more. The above-mentioned configuration of the high-strength copper alloy for electroconductivity of the present invention is as follows.・ By adding tin, the flex resistance is greatly improved, the tensile strength and the elongation after annealing are improved, and the deterioration of the castability due to the addition of magnesium is improved. To improve heat resistance and castability, and to further improve tensile strength by adding indium, and further improve elongation and flex resistance by adding tellurium. This is obtained by optimizing the respective addition amounts.

That is, in the conductive high-strength copper alloy of the present invention, it is necessary that the magnesium content is 0.05% by weight or more and 0.25% by weight or less. Magnesium significantly improves the tensile strength, but if the content is less than 0.05% by weight, a sufficient effect cannot be obtained. On the other hand, the content is 0.
If it exceeds 25% by weight, the effect of improving the tensile strength will be saturated, the conductivity will be significantly lowered, and the castability will be deteriorated to increase the occurrence of defects such as cavities. 0.2 like this
In the range of more than 5% by weight, casting cracks are likely to occur especially during continuous casting, and wire breakage frequently occurs during wire drawing. At this time, although it is possible to prevent it to some extent by cutting the surface of the skin and then performing wire drawing, the productivity is still significantly reduced.

The tin content must be 0.1% by weight or more and 0.6% by weight or less. That is, by adding tin, it is possible to reduce the decrease in castability that has occurred as a result of the addition of magnesium, and also to obtain the effect of significantly improving the elongation after annealing. However, 0.1
Addition of less than wt% does not give a sufficient effect, on the other hand, 0.
Even if added in excess of 6% by weight, the effect of improving the tensile strength and castability is saturated, conversely the elongation and flex resistance after annealing are deteriorated, and the decrease in conductivity becomes large, making it impractical.

Further, the amount of phosphorus added is 0.02% by weight or more and 0.1.
It is necessary to be 08% by weight or less. When the amount of phosphorus added is 0.02% by weight or more, the castability is remarkably improved due to the synergistic effect with tin, and the decrease in castability resulting from the addition of magnesium can be almost eliminated. The heat resistance is greatly improved. However, when the addition amount of phosphorus exceeds 0.08% by weight, the conductivity is greatly reduced, and it cannot be used as a practical conductive material.

The indium content must be 0.02% by weight or more and 0.2% by weight or less. When the content of indium is 0.02% by weight or more, the tensile strength is significantly improved, but when it is less than 0.02% by weight, a sufficient effect cannot be obtained. On the other hand, even if it is added in an amount of more than 0.2% by weight, the tensile strength is saturated and no further improvement effect can be obtained, and the conductivity is remarkably lowered. It should be noted that adding a large amount of expensive indium causes an increase in cost and makes it unsuitable as a practical conductive material.

The content of tellurium must be 0.05% by weight or more and 0.1% by weight or less. Tellurium improves elongation and flex resistance by a synergistic effect with tin, but if the addition amount is less than 0.05% by weight, sufficient effect cannot be obtained, and if 0.1% by weight or more, castability is obtained. Significantly worsens.

The amount of magnesium, tellurium and tin added has a great effect on the castability. If the addition amount of both magnesium and tellurium increases, the castability deteriorates significantly. On the other hand, tin has the effect of improving castability. In order to ensure good castability, it is necessary that the ratio of the tin content to the sum of the magnesium content and the tellurium content is 1 or more.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION By using the high-strength copper alloy for electric conduction according to the present invention, a conductor for electric wire having high strength, high elongation and excellent bending resistance can be obtained as follows. . That is, a cast product made of a high-strength copper alloy for electroconductivity according to the present invention is drawn after cold rolling (hereinafter referred to as “first wire drawing step”), and then annealed at 500 ° C. or higher and 600 ° C. or lower, "First annealing step"), and then wire drawing at a working rate of 85% or more and 95% or less (hereinafter referred to as "second wire drawing step"), 35
Annealing is performed at 0 ° C. or higher and 450 ° C. or lower (hereinafter referred to as “second annealing step”).

The first annealing step restores the worked structure in the cold rolling and wire drawing treatment of the first wire drawing step, and
This is to prevent a decrease in tensile strength in the annealing process and to improve elongation and flex resistance. This step is performed in a non-oxidizing atmosphere such as water vapor, but if the annealing temperature (hereinafter referred to as “first annealing temperature”) is less than 500 ° C., sufficient recovery cannot be performed, so that elongation is improved in the second annealing step. No, meanwhile 600
If the temperature exceeds ℃, it will be oxidized by a small amount of oxygen mixed into the non-oxidizing atmosphere from the atmosphere, causing discoloration and lowering the appearance evaluation. At the same time, the range of the optimum tension range will be narrowed and the winding tension of the wire will be adjusted. Becomes difficult.

On the other hand, the working rate (reduction rate of cross section) in the second wire drawing step must be 85% or more and 95% or less. This second wire drawing step is carried out to prevent a decrease in tensile strength in the second annealing step and to improve elongation and flex resistance, but when the working ratio is less than 85%, the second annealing step is performed. The decrease in tensile strength was large, and the processing rate was 9
If it exceeds 5%, the elongation and bending resistance cannot be sufficiently improved in the second annealing step. The temperature of the second annealing step (hereinafter referred to as "second annealing temperature") is 350 ° C or higher and 450 or higher.
It is necessary to carry out at a temperature of ℃ or below. Note that this step is also performed in a non-oxidizing atmosphere such as steam. As described above, this step is performed to improve the elongation and the flex resistance, but if the treatment temperature is lower than 350 ° C., the effect of sufficiently improving these performances cannot be obtained, while if it is higher than 450 ° C. The tensile strength is significantly reduced.

[0015]

EXAMPLE A graphite crucible was used in an inert gas atmosphere, and electrolytic copper ingots were melted while coating with graphite particles to obtain the compositions shown in Examples 1 to 11 in Table 1, respectively. Magnesium (Mg), tin (Sn)
And indium (In) are added in the form of pure metals, and phosphorus (P) and tellurium (Te) are added in the form of a master alloy to obtain a uniform molten metal, and these are continuously cast, respectively. A cast rod having a diameter of 20 mm was obtained (in Table 1 and Table 2, the composition of copper (Cu) is indicated by "remainder") except for these additives (and inevitable impurities). Will be). Each of these cast rods was cold-rolled, drawn to have a diameter of 3.2 mm, and then continuously annealed at 550 ° C. (first annealing temperature). Furthermore, wire drawing is performed so that the diameter becomes 1 mm (working rate: 90%), and then 3
Continuous annealing at 90 ° C. (second annealing temperature), Examples 1 to 11
A conductor for electric wire according to The annealing temperature in the present invention is a value calculated from the annealing voltage, the annealing speed, and the conductor resistance of each copper alloy wire, assuming that the thermal efficiency is 90%.

As a comparative example of the prior art, a conductor for electric wire made of a Ni--Si--In--Sn copper alloy obtained as described below was examined. That is, using a graphite crucible under an inert gas atmosphere, and after melting the electrolytic copper ingot while covering with graphite particles, indium, nickel (Ni) and tin in the form of pure metal, and silicon ( Si) in the form of a master alloy, 0.16% by weight, 2.6% by weight, 0.23% by weight and 0.55% by weight, respectively.
To obtain a uniform molten metal, which was continuously cast into a casting rod having a diameter of 20 mm. After this was cold drawn and drawn to have a diameter of 3.2 mm, it was heated and held at 900 ° C. for 1 hour in an inert gas atmosphere, and then cooled with water to undergo solution treatment. After that, wire drawing was performed so that the diameter was 1 mm, and further aging treatment was performed at 470 ° C. for 6 hours in an inert gas atmosphere (Comparative Example 1).

Similarly, as a comparative example related to the prior art, a conductor for electric wire having a diameter of 1 mm (comparative example 2) made of hard copper which is an ordinary oxygen-free copper was prepared. Further, as Comparative Example 3, a conductor for electric wire having a diameter of 1 mm obtained by annealing oxygen-free copper in an inert gas atmosphere at 300 ° C. for 2 hours was prepared.

Further, in order to show that the composition of the high-strength copper alloy for electric conduction according to the present invention is optimized, Example 1 is shown.
No. 11 to No. 11, except that the compositions shown in Table 2 were used to prepare conductors for electric wires of Comparative Examples 4 to 13. Furthermore, as Comparative Examples 14 to 18, casting rods having the same composition as that used in Example 11 were used, except that the first annealing temperature, the working rate, or the second annealing temperature was changed as shown in Table 2. A conductor for electric wire having a diameter of 1 mm was produced under various conditions.

Examples 1 to 11 and Comparative Examples 1 to 18
The electric conductor for electric wire was evaluated for tensile strength, elongation, conductivity, bending resistance and stretchability. Table 1 shows the results
And shown in Table 2. In Tables 1 and 2, “Sn
Shown as "/ (Mg + Te)" is the ratio of the tin content to the sum of the magnesium content and the tellurium content.

The tensile strength and elongation are JIS C30.
In accordance with No. 02, the tensile speed was measured at 50 mm / min.
Similarly, the conductivity is a value measured according to JIS C3002. The flex resistance was evaluated as follows. Sample 2 on jig 1 as shown in FIG.
(A) → (b) → (c) → while holding one end of (electric wire conductor) and applying a tensile load W of 2 kgf to the other end.
As shown in (d), bending was performed 90 ° to the left and right, and a series of operations was performed once, and this operation was repeated until breaking, and the number of times was taken as the flex resistance. The stretchability was judged by the presence or absence of burrs. That is, in a sample having poor stretchability, the defective portion generated during casting remains without being eliminated during rolling, and as a result, minute cracks (burrs) occur on the surface of the sample after wire drawing. This burr was detected visually and by touching with a fingertip.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3]

As is apparent from Table 1, electric wire conductors made of the high-strength copper alloy for electric conduction according to the present invention (Examples 1 to 11)
Is extremely superior in conductivity, elongation and flex resistance as compared with the Ni-Si-In-Sn copper alloy according to the prior art (Comparative Example 1). The tensile strength of this product is N
Although it is slightly lower than the i-Si-In-Sn copper alloy (Comparative Example 1), it is at a level comparable to that of hard copper wire, which is a sufficient value. It should be noted here that the bending resistance is very high, which is a value better than that of annealed copper. In addition, Comparative Example 4 to Table 2
It can be seen from 18 that the effect of the present invention cannot be obtained if any one of the constitutional requirements (composition and processing conditions) of the present invention is not satisfied.

[0025]

The conductor for electric wire made of the high-strength copper alloy for electroconductivity of the present invention has the same level of tensile strength as hard copper and is excellent in electrical conductivity, elongation and bending resistance. The electric wire can have a small space and weight. Further, this conductor for electric wire has a low raw material cost, and furthermore, the temperature is easy to control because the temperature is relatively low in both the first annealing step and the second annealing step. Moreover, an expensive furnace is not required, and ordinary electric wire production is not required. Since it can be carried out by the continuous annealing machine used in the process, it can be produced at low cost. The electric wire conductor made of the conductive high-strength copper alloy of the present invention has the advantages as described above,
By using an electric wire that uses this conductor,
Not only in the field where lightness is especially required for aircraft, but also when applied to general electronic equipment, excellent weight reduction effect is obtained, and when used for moving parts, high reliability is obtained due to its bending resistance. It is what is done.

[Brief description of drawings]

FIG. 1 is a diagram showing a state of a bending resistance test of the present invention.

[Explanation of symbols]

 1 jig 2 sample

Claims (2)

[Claims] 1. Magnesium in an amount of 0.05 wt.
25% by weight or less, 0.1% by weight or more of tin and 0.6% by weight
Below, 0.02 wt% to 0.08 wt% phosphorus, 0.02 wt% to 0.2 wt% indium, 0.05 wt% to 0.1 wt% tellurium, the balance Is a copper, and the ratio of the content of tin to the sum of the content of magnesium and the content of tellurium is 1 or more. 2. Magnesium in an amount of 0.05% by weight or more.
25% by weight or less, 0.1% by weight or more of tin and 0.6% by weight
Below, 0.02 wt% to 0.08 wt% phosphorus, 0.02 wt% to 0.2 wt% indium, 0.05 wt% to 0.1 wt% tellurium, the balance Is made of copper, and the ratio of the tin content to the sum of the magnesium content and the tellurium content is 1 or more.
Manufacture of a conductor for electric wire made of a high-strength copper alloy for electric conduction, characterized by annealing at ℃ or less, then drawing at a working rate of 85% or more and 95% or less, and then annealing at 350 ° C or more and 450 ° C or less. Method.