JPH06184668A - Copper chromium thin wire and its production - Google Patents

Abstract

PURPOSE:To produce a copper chromium thin wire excellent in mechanical and electrical properties of supersaturated solid solution by cooling/solidifying a molten copper chromium alloy containing a specified amount of Cr by a method of rotation-spinning in liquid and executing age hardening after drawing. CONSTITUTION:A cooling medium liquid layer is formed by centrifugal force in a cylindrical drum rotating at high speed. A molten copper chromium alloy containing 1.2-5.0weight% Cr is jetted from a nozzle into the cooling medium liquid and is cooled and solidified. By this method, a copper chromium thin wire consisting of supersaturated solid solution is obtained. This thin wire, after subjecting to solution treatment as required, is drawn and subjected to age hardening treatment. By this method, the copper chromium thin wire, which is good in cross-sectional roundness and low in variance of a diameter in the longitudinal direction, having high tensile strength, high electric conductivity and high heat resistance, is obtained.

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 copper-chromium alloy thin wire having high strength, high electrical conductivity and heat resistance, which is useful as an electronic material such as a magnet wire.

[0002]

2. Description of the Related Art Fine wires of copper-chromium alloy have high electrical conductivity and thermal conductivity as well as higher mechanical strength and heat resistance than copper, and are applied to magnet wires and the like. Conventionally, after heat-drawing an ingot obtained by melting an alloy containing about 1% by weight or less of chromium in a high frequency melting furnace to a desired diameter, heat treatment for solid solution of chromium in copper. High mechanical strength and heat resistance have been obtained by applying heat treatment to precipitate chromium and chromium. However, recently, magnet wires and the like are required to have higher mechanical strength and heat resistance. For this purpose, it is effective to increase the amount of chromium deposited, but for this purpose, the chromium content in copper must be further increased. But,
In the copper-chromium alloy, the maximum solid solution amount of chromium is limited to 0.73% by weight (at 1350K), so if the content of chromium is not at most about 1% by weight, chromium will form a solid solution in copper. However, there is a drawback that a large amount of chromium is already deposited in the heat treatment, and many wire breaks occur during the wire drawing process.
The heat resistance was not sufficient.

In order to overcome such conventional drawbacks, it is necessary to obtain a so-called supersaturated solid solution ingot having a chromium content of 1% by weight or more and less precipitation of chromium. As a method therefor, there is a method of directly obtaining a thin wire-shaped ingot from molten metal. In this method, since the cooling rate at the time of forming the ingot from the molten metal is extremely fast, precipitation of intermetallic compounds and the like is very small, and a supersaturated solid solution can be easily obtained. There are two main methods: a method of ejecting molten metal into a refrigerant gas to cool and solidify it, and a rotating submerged spinning method of ejecting molten metal to a liquid cooling medium that rotates by centrifugal force to cool and solidify it. The first method can obtain a thin wire having a circular cross section, but has a drawback that the diameter of the thin wire to be produced is small and limited because the cooling rate during solidification is slow. Second
Of the above methods, one of the methods of ejecting into still water makes it difficult to obtain a fine wire of good quality due to the impact when incident in water. On the other hand, the rotating submerged spinning method is described in Japanese Examined Patent Publication No. 60-38228, and the turbulence of the cooling medium can be controlled by matching the centrifugal force and the jet pressure as compared with the method of jetting in stationary water. Further, according to this method, a high cooling rate of the order of -10 ⁵ ° C / sec can be obtained, so that a supersaturated alloy can be manufactured.

[0004]

In order to produce a copper-chromium alloy thin wire having both excellent mechanical and electrical characteristics and heat resistance, copper-chromium containing more chromium than the conventional about 1% by weight is used. An alloy was needed. On the other hand, as a method of obtaining such a supersaturated solid solution, there is a method of directly producing a fine linear ingot from a powerful molten metal. However, the thin wire produced by this method lacks the unevenness of the wire diameter in the length direction and the roundness. Further, since the rapidly solidified thin wire is not processed or heat-treated, when it is used as a spring incorporated in, for example, a magnet wire or precision equipment, the wire diameter of the thin wire is inferior in mechanical strength due to lack of mechanical strength. There is a problem.

The present invention has been made in order to solve the above-mentioned problems, and by producing a copper-chromium alloy fine wire containing high concentration chromium of about 1% by weight or more by a spinning liquid spinning method. , A supersaturated solid solution is obtained, and when the produced thin wire is drawn under specific conditions, the circularity of the cross section,
The thickness unevenness in the length direction is improved. Further, it is an object of the present invention to obtain a method for producing a copper-chromium alloy fine wire having excellent mechanical and electrical characteristics, that is, high tensile strength, high electrical conductivity and high heat resistance, by selecting liquefaction treatment and aging treatment.

[0006]

In the thin copper-chromium alloy wire according to the present invention, a refrigerant liquid layer is formed in a cylindrical drum rotating at a high speed by centrifugal force, and 1.2 to 5% by weight of the refrigerant liquid layer is formed in the refrigerant liquid layer. .
It is obtained by jetting a molten copper-chromium alloy containing 0 chromium from a nozzle to cool and solidify it, wire-drawing the produced copper-chromium alloy thin wire, and then subjecting it to an age hardening treatment.

That is, the thin copper-chromium alloy wire according to the present invention is
It is characterized by comprising a copper-chromium alloy containing 1.2 to 5.0% by weight of chromium, and the copper-chromium alloy being a supersaturated solid solution.

Further, in the method for producing a copper-chromium alloy thin wire according to the present invention, a refrigerant liquid layer is formed in a cylindrical drum rotating at a high speed by centrifugal force, and 1.2 to 5.0% by weight of the refrigerant liquid layer is formed.
The molten copper-chromium alloy containing chromium is ejected from a nozzle to be cooled and solidified, the obtained copper-chromium alloy thin wire is drawn, and then an age hardening treatment is performed.

Further, in the method for producing a copper-chromium alloy thin wire according to the present invention, a refrigerant liquid layer is formed in a cylindrical drum rotating at high speed by centrifugal force, and 1.2 to 5.0% by weight of the refrigerant liquid layer is formed.
The molten copper chromium alloy containing chromium is ejected from a nozzle to be cooled and solidified, and the obtained copper chromium alloy thin wire is subjected to solution treatment, followed by wire drawing and age hardening treatment.

In the above copper-chromium alloy thin wire, the content of chromium is limited to 1.2 to 5.0 by weight%, which is 1.2.
If it is less than 5% by weight, the amount of chromium solid-dissolved in copper is insufficient and the mechanical properties and heat resistance are not improved. If it exceeds 5.0% by weight, a sufficient supersaturated solid solution is formed in relation to the cooling rate. In addition, it is expensive.

Further, the diameter of the copper-chromium alloy thin wire is 30 to
The range of 500 μm is preferable. If it is less than 30 μm, it is difficult to obtain a uniform continuous thin wire, and the linear shape after wire drawing becomes too thin, so that its use is limited,
This is because if it exceeds 500 μm, the cooling ability becomes insufficient and a uniform continuous thin wire cannot be obtained.

In order to minimize the unevenness of the wire diameter in the longitudinal direction and to improve the mechanical properties by making the cross-sectional shape of the fine wire circular, it is necessary to perform wire drawing at a cross-section reduction rate of 40 to 80%. preferable. This is because if it is less than 40%, the unevenness of the wire diameter cannot be completely eliminated, and if it exceeds 80%, disconnection is likely to occur, resulting in an increase in cost.

Furthermore, in order to obtain excellent mechanical and electrical characteristics, the age hardening treatment temperature for precipitating chromium is 4
It is preferably carried out at 00 to 460 ° C., and more preferably 420 to 440 ° C. in the case of use in which mechanical strength is prioritized.

[0014]

With respect to the copper-chromium alloy fine wire containing about 1% by weight or less of chromium, the mechanical and electrical characteristics are improved by precipitating chromium dissolved in copper by age hardening treatment. That is, solution treatment for completely dissolving chromium, which is a solute atom, in copper and maintaining such a state up to room temperature is required before the age hardening treatment. But,
In a copper-chromium alloy containing about 1% by weight or more of chromium,
Even at the conventional solution treatment, chromium cannot be completely dissolved in copper as a matrix at room temperature. In order to form a supersaturated solid solution at room temperature, it is necessary to quench and solidify the molten state at a cooling rate of about 10 ³ to 10 ⁵ ° C / sec.

According to the present invention, a supersaturated solid solution is obtained at room temperature by rapidly solidifying a copper-chromium molten alloy containing about 1.2 to 5% by weight or more of chromium, and in the process of rapid solidification. Since solution treatment is performed, it is possible to omit the conventional solution treatment step, and by selecting the optimum age hardening treatment after wire drawing, it is possible to obtain excellent mechanical and electrical A copper-chromium alloy thin wire having characteristics and heat resistance can be obtained, and the roundness of the cross section and the unevenness of the wire diameter in the length direction are improved. Of course, even if the rapidly solidified copper-chromium alloy thin wire is subjected to solution treatment again, followed by wire drawing and age hardening treatment, it also has excellent mechanical and electrical characteristics and heat resistance. And the roundness of the cross section and the unevenness of the wire diameter in the length direction are improved. These can be confirmed by the examples described later.

[0016]

【Example】

Examples 1 to 2 from a master alloy having a composition of 10% Cr-90% Cu at 2 wt%
% Cr-98% Cu alloy was melted in an argon atmosphere to form a new mother alloy, and a Cr-Cu alloy fine wire was produced by a spinning liquid spinning method. That is, a molten alloy having the above composition was passed through a nozzle having a diameter of 200 μm and an argon gas of 4.5 kg / cm ²
(Gauge pressure), and this is led to a refrigerant liquid layer having a depth of 17 mm formed in a rotating drum having an inner diameter of 370 mmφ at an introduction angle of 45 ° and rapidly cooled and solidified at a cooling rate of 10 ³ to 10 ⁵ ° C./sec. A continuous thin wire having an average diameter of 180 μm was obtained. At this time, the speed of the rotary drum was 9.5 m / sec, and the distance between the nozzle and the cooling liquid surface was kept at about 8 mm.

In order to confirm the formation of the supersaturated solid solution, the cross section of the produced copper-chromium alloy thin wire was surface-analyzed using EPMA to confirm the state of chromium precipitation.

Next, the thin wires of this Cr--Cu alloy were subjected to solution treatment at 950 to 1050 ° C. for 1 hour in an argon atmosphere, and each thin wire in the As cast state was heated at room temperature using a diamond die. Then, wire drawing was performed with a cross-section reduction rate of 80%. After that, an age hardening treatment was performed at 400 to 500 ° C. for 3 hours to measure the roundness, the wire diameter unevenness in the length direction, and the tensile strength and the electrical conductivity.

The tensile strength in the examples is the test length of 35.
A 0 mm sample was measured at a crosshead speed of 10 mm / min using an Instron type tensile tester (JIS300
3). The conductivity (% IACS) was calculated from the resistance value by measuring the resistance value by the double bridge method with a measurement length of 500 mm (JISC3002). The heat resistance was obtained by subjecting a thin wire sample age-hardened at 440 ° C. to heat treatment at 300 to 650 ° C. for 30 minutes and then measuring the hardness using a micro Vickers hardness meter to determine the softening temperature (load load 25 g , Load time 15 seconds).

Further, the wire diameter unevenness in the longitudinal direction is 10 for the sample.
m was sampled, the diameter was measured at random (10 points), the difference between the maximum and minimum diameters was divided by the average diameter, and the value was multiplied by 100 to obtain the difference. The roundness was calculated from the ratio of the maximum axis diameter and the shortest diameter of the same cross section.

FIG. 1 is a result of observing a cross-section of a 2% Cr-Cu alloy thin wire in Example 1 in a rapidly solidified state by EPMA. A supersaturated solid solution is formed from a composition image and an X-ray image of chromium. I understand. The EPMA results of the thin copper-chromium alloy wires obtained in Examples 2 and 3 were also substantially the same as the results of Example 1.

Table 1 shows the results of measurement of tensile strength, conductivity, and wire diameter unevenness. In Table 1, Examples 1 to 3 are quenching fine wires having a 2.0% Cr-98.0% Cu (wt%) alloy composition in the present invention, and Comparative Examples 1 and 2 are commercially available 1.1. % Cr-98.9% Cu (weight%) alloy, which is a thin wire produced by a conventional method. Comparative Example 3 is a thin wire that was produced by spinning in a rotating liquid but was not drawn. Comparative Example 1 is the characteristic value of the heat treatment conditions performed assuming the use in which the tensile strength is prioritized, and Comparative Example 2 is the heat treatment condition that was performed to improve the conductivity.

[0023]

[Table 1]

Examples 1 and 2 are samples obtained by subjecting a rapidly solidified thin wire to wire drawing without liquefaction treatment and then age hardening treatment. These tensile strengths are 60 to 81 kgf / m
Compared to Comparative Example 1 in terms of m ² , it was possible to improve significantly by 15 to 56%. At this time, the conductivity was slightly lowered by the age hardening treatment at 440 ° C., but showed a value almost equal to that of Comparative Example 1 treated at 500 ° C.

Example 3 is a sample in which a rapidly solidified thin wire was subjected to solution treatment, followed by wire drawing and age hardening. The tensile strength of Example 3 was 73 kgf / mm ² , which was improved by 40 to 52% as compared with Comparative Examples 1 and 2. On this occasion,
The electrical conductivity was about 80% IACS and showed almost the same value.

Comparative Example 3 is shown in order to compare the roundness of the thin line with that of the Example. Although the roundness in this case is not good, the thin lines of Examples 1 to 3 shown in Table 1 will eventually occur. The roundness was 100%, and no wire diameter unevenness in the length direction was observed. That is, by performing wire drawing as in the example,
The roundness and the unevenness of the wire diameter in the length direction were improved.

Next, the results of measuring the softening temperature using Example 1 and Comparative Example 1 are shown in FIG. In the case of Example 1, about 5
Hv = 260 was maintained up to 50 ° C., after which the hardness decreased and softening started. On the other hand, in Comparative Example 1, about 5
When it exceeds 00 ° C, softening has started. From the above results, the softening temperature of Example 1 was improved by about 50 ° C., and the hardness equivalent to that of Comparative Example 1 was obtained even by the heat treatment at about 620 ° C.

The composition according to Examples 4 to 6% by weight was obtained by melting a 3% Cr-97% Cu alloy in an argon atmosphere and jetting it with an argon gas of 4.2 kg / cm ² (gauge pressure) from a nozzle having a diameter of 195 μm. , A depth of 17 mm formed in a rotating drum with an inner diameter of 370 mmφ
Led to the refrigerant liquid layer at 45 ° with an inlet angle of 10 ³ to 10 ⁵ ℃ /
It was rapidly solidified at a cooling rate of 2 seconds to obtain a continuous thin wire having an average diameter of 190 μm. The speed of the rotating drum at this time is 9.8 m /
Seconds, and the distance between the nozzle and the cooling liquid surface was maintained at about 8 mm.

Next, this Cr--Cu alloy thin wire was subjected to solution treatment at 950 to 1050 ° C. for 1 hour in an argon atmosphere, and a thin wire in the As cast state was used at room temperature using a diamond die. Wire drawing was performed with a cross-section reduction rate of 80%. Then, an aging treatment was performed at 400 to 500 ° C. for 3 hours to measure the roundness, the wire diameter unevenness in the length direction, and the tensile strength and the conductivity.

The results are shown in Table 2. The thin wires of Examples 4 to 6 shown in Table 2 all had a circularity of 100% and a wire diameter unevenness in the longitudinal direction of 0%. As a result of surface analysis by EPMA, it was confirmed that a supersaturated solid solution was formed. The tensile strength of Examples 4 to 5 was superior to that of the conventional material (Comparative Examples 1 and 2 shown in Table 1) of 48 to 52 kgf / mm ² , and could be greatly improved. Although the conductivity is slightly lower than that of the conventional material, it is effective in the case where the use is prioritized for strength. In addition, the tensile strength of the solution-treated Example 6 was improved by about 54%, and the conductivity was 75% IACS.

[0031]

[Table 2]

Although not shown in the examples, the same results as in the above examples were obtained with Cr-Cu alloys having Cr contents other than 2.0% by weight and 3.0% by weight.

[0033]

As described above, according to the present invention, the refrigerant liquid layer is formed by the centrifugal force in the cylindrical drum rotating at a high speed,
The molten copper-chromium alloy containing 1.2 to 5.0% by weight of chromium is jetted from this nozzle into this refrigerant liquid layer, quenched and solidified, and the produced alloy fine wire is wire-drawn. By subjecting the alloy thin wires produced by quenching and solidification to the solution treatment followed by wire drawing and age hardening, the circularity of the cross section and the unevenness of the wire diameter in the length direction can be obtained. In addition, it is possible to obtain a method for producing a fine wire made of a copper-chromium alloy in the form of a supersaturated solid solution, which has excellent mechanical and electrical properties, that is, high tensile strength, high electrical conductivity, and excellent heat resistance. .

The copper-chromium alloy thin wire of the present invention has extremely excellent mechanical strength, high conductivity, and high heat resistance.
It is easy to apply to high-strength magnet wire, etc. without being softened when the insulation film is baked, and it is expected that the field of application will be greatly expanded.

Further, in the present invention, the spring limit value (kb
Although the value) was not measured, there is a correlation between the tensile strength and the spring limit value, and it is expected to have excellent spring properties. This also makes it possible to apply wire springs for precision equipment, such as balance springs for watches.

[Brief description of drawings]

FIG. 1 is a photograph showing an EPMA analysis result showing a metal structure of a copper-chromium alloy thin wire obtained in Example 1.

FIG. 2 is a graph showing measurement results of softening characteristics of the copper-chromium alloy thin wire obtained in Example 1 and the copper-chromium thin wire of Comparative Example 1.

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Tokushige Yokomatsu 1-2-9 Hachiman-cho, Higashi-Kurume City, Tokyo Metropolitan Co., Ltd. (72) Inventor Mitsuyuki Imaizumi Higashi-Kurume, Tokyo 1-29, Yawata-cho, Ichi, Japan, within the Optec Didy Melco Laboratory Co., Ltd. (72) Inventor, Murakami Shoji 8-1-1, Tsukaguchi Honcho, Amagasaki City Mitsubishi Electric Corporation (72) Inventor Yoshizaki Hachi, 8-1, 1-1 Tsukaguchihonmachi, Amagasaki City Mitsubishi Electric Corporation

Claims (3)

[Claims] 1. A fine copper-chromium alloy wire comprising a copper-chromium alloy containing 1.2 to 5.0% by weight of chromium, the copper-chromium alloy being a supersaturated solid solution. 2. A refrigerant liquid layer is formed by centrifugal force in a cylindrical drum rotating at a high speed, and a molten copper chromium alloy containing 1.2 to 5.0% by weight of chromium is ejected from the nozzle into the refrigerant liquid layer. Then, it is cooled and solidified, and the obtained copper-chromium alloy thin wire is drawn, and then an age hardening treatment is carried out. 3. A refrigerant liquid layer is formed by centrifugal force in a cylindrical drum rotating at a high speed, and a molten copper chromium alloy containing 1.2 to 5.0% by weight of chromium is ejected from a nozzle in this refrigerant liquid layer. Then, it is cooled and solidified, and the obtained copper-chromium alloy thin wire is subjected to solution treatment, followed by wire drawing and age hardening treatment, and a method for producing a copper-chromium alloy thin wire.