JP3333654B2 - High-strength copper alloy for electric conduction excellent in elongation characteristics and bending characteristics, and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper alloy,
For example, the present invention relates to a conductive high-strength copper alloy having flexibility and elongation characteristics suitable for use as a conductor of an automobile electric wire.

[0002]

2. Description of the Related Art Conventionally, annealed copper wire has been mainly used as a conductor of an automobile electric wire of an automobile. However, the on-board equipment such as various instruments has been digitized, and the number of electric and electronic wiring circuits in the automobile has been increased. Has increased significantly, leading to an increase in the space occupied in the automobile by the electric wires for the automobile and an increase in the total weight of the automobile. However, it is desirable that the vehicle body be light in weight in terms of improving fuel efficiency. In order to reduce the weight of the vehicle body, even if the number of wiring circuits in the vehicle increases, the vehicle occupancy of the vehicle wires in the vehicle will be increased. There is an increasing demand for a reduction in the space of the product and a suppression of an increase in the total weight of the electric wires for automobiles. Therefore, hard copper wire was studied as a material that can secure mechanical strength even if the outer diameter of the conductor is reduced in order to reduce the weight of the electric wire for automobiles. Even when the terminals are crimped to each other using a wire, if a mechanical load is applied to the joint by an external force of vibration and shock generated while the automobile is running, the joint may be damaged. When the terminals are crimped together using a hard copper wire in this way, the crimped portion of the terminal becomes a mechanical weak point, which easily causes disconnection due to an external impact, resulting in poor reliability. In addition, reducing the weight of automobile wires can be achieved by reducing the conductor diameter.However, in the case of conventional soft copper wire, reducing the conductor outer diameter decreases the mechanical strength. Would. Therefore,
In recent years, Ni—Si—In—Sn copper alloy (Japanese Patent Publication No. 5-27699) is a copper alloy that can secure mechanical strength even with a small conductor outer diameter and has relatively good repeated bending strength and conductivity. Gazette) has been developed. This Ni-
The Si-In-Sn copper alloy improves tensile strength, elongation, and electrical conductivity by precipitating Ni and Si, which are in solid solution in the Cu matrix, by age hardening. In addition, In, S
n is dissolved in the Cu matrix to further improve the tensile strength.

[0003]

SUMMARY OF THE INVENTION Such a conventional Ni
In the case of -Si-In-Sn copper alloy, a large amount of expensive Ni is used (usually 2 to 3 wt%), and there is a problem that the cost of the material as an electric wire conductor increases. . The high cost of this conductor material affects the price of electric wires, and an increase in the price of electric wires may result in a higher automobile price in the automotive sector, where the usage volume is particularly increasing, and the automotive sector, where price competition is fierce, In such a case, it is required that the price of the vehicle be reduced without lowering the functions of the vehicle. For that purpose, it is necessary to reduce the cost of all parts of the car without deteriorating the performance of each part. is not. In addition, the conventional Ni-Si-In-Sn copper alloy is a solution hardening treatment, and is an age hardening type copper alloy which performs an age hardening treatment. Since equipment is required and processing costs are increased, product costs are significantly increased. In the case of this age hardening type copper alloy, good properties cannot be obtained as a copper alloy unless the temperature control of the heat treatment is performed accurately during the solution treatment and the age hardening treatment. However, it is difficult to accurately control the temperature of the heat treatment when performing the solution treatment and the age hardening treatment, and characteristics tend to vary. An object of the present invention is to eliminate the need for a complicated heat treatment step, improve the flexibility, elongation characteristics, and tensile strength without causing a decrease in electrical conductivity, maintain high strength against mechanical shock, An object of the present invention is to make it possible to manufacture a high-strength copper alloy for conduction with reduced disconnection due to bending at low cost.

[0004]

According to the first aspect of the present invention,
Mg: 0.05-0.25 mass%, Sn: 0.1-
0.6 mass%, P is 0.02 to 0.08 mass
%, 0.02 to 0.2 mass% of In, and 0.02% of Mn.
Containing 5~0.15mass%, the balance being copper and incidental non
It is made of a pure substance, and the ratio of the Mg content to the Sn content is Mg: Sn = (1) :( 1.0 or more).

[0005] According to the second aspect of the present invention, Mg is added to 0.05 to 0.05.
0.25 mass%, Sn is 0.1-0.6 mass
%, P is 0.02 to 0.08 mass%, and In is 0.0
2 to 0.2 mass%, Mn is 0.05 to 0.15 ma
containing ss%, the balance being copper and unavoidable impurities was the ratio between the content and the Sn content of the Mg is, Mg: Continuous copper alloy is Sn = (1) :( 1.0 or higher) The cast rod produced by casting is cold-rolled, continuously annealed at 500 to 600 ° C. after drawing, then drawn at a working rate of 85 to 95%, and subjected to a final heat treatment of 320%.
It is intended to manufacture by continuous annealing at ~ 420 ° C.

[0006]

According to the first aspect of the present invention, Mg is solid-dissolved in a Cu matrix to improve the tensile strength and limit the optimum amount of Mg to minimize deterioration of castability due to Mg. The addition of Sn and Sn significantly improves the bending characteristics, further improves the tensile strength and elongation after annealing, and improves the deterioration of castability due to the addition of Mg. By adding P, the heat resistance is improved and the castability is further improved.
The tensile strength is further improved by adding n, and the elongation and flexibility are further improved by adding Mn.

[0007] It has been conventionally known that when Mg is added to Cu, cast cavities and the like are liable to occur during casting and castability is deteriorated. In particular, casting cracks are liable to occur during continuous casting. The casting split portion became a defective portion of the copper alloy after rolling or wire drawing, causing disconnection. Therefore M
g In the case of copper alloy, wire is drawn after the surface
Disconnection may occur frequently. On the other hand, the addition of Mg has a very large effect of improving the tensile strength, although the decrease in conductivity is small. For this reason, in the invention of claim 1, Mg
Is set to 0.05 to 0.25 mass% ,
The reason for setting the content of Mg to 0.05 to 0.25 mass% is that if the content of Mg is less than 0.05 mass% , the effect of improving the tensile strength is small, and the content of Mg is 0.2%.
Even if it exceeds 5 mass% , the effect of improving the tensile strength is saturated, the conductivity is significantly reduced, and the castability is rapidly deteriorated.

The addition of Sn significantly improves the flexibility, further improves the tensile strength, improves the elongation after annealing, and improves the castability, which is deteriorated by the addition of Mg. In the first aspect of the present invention, the Sn content is set to 0.1 to 0.6 mass% when the Sn content is less than 0.1 mass%. Small, Sn content 0.6 mass%
Even if the ratio exceeds 1, the effect of improving tensile strength and castability is saturated, elongation and flexibility after annealing deteriorate, and the conductivity is significantly reduced.

Further, the addition of P has a very large effect of improving the castability due to the synergistic effect with Sn, and can greatly reduce the deterioration of the castability due to the addition of Mg, and greatly improves the heat resistance. The amount of addition is limited due to the large decrease. Therefore, in the invention of claim 1, P
Is set to 0.02 to 0.08 mass% ,
The reason why the content of P is set to 0.02 to 0.08 mass% is that if the content of P is less than 0.02 mass% , the effect of improving the heat resistance is small and the castability reduced by the addition of Mg. Cannot be completely improved, and the P content is 0.08 mas
If the content exceeds s% , heat resistance and castability are improved, but conductivity is significantly reduced, which is not practical.

Further, the addition of In significantly improves the tensile strength. In the first aspect of the present invention, the content of In is set to 0.02 to 0.2 mass%.
When the content of is less than 0.02 mass% , the effect of improving the tensile strength is small, and the content of In is 0.2 mass %.
% , The effect of improving the tensile strength saturates and the conductivity decreases, and adding a large amount increases the cost of In because it is expensive and is not practical.

Further, the addition of Mn improves the flexibility. The invention according to claim 1, wherein the content of Mn is set to 0.1.
05 to 0.15 were as mass% is the content of Mn is less than 0.05 mass%, the elongation characteristics and the effect of improving flexibility is small, the content of Mn is 0.15 mas
If it exceeds s% , the effect of improving the elongation characteristics and the flexibility is saturated, and the conductivity is reduced.

Here, the addition ratio of Mg for lowering castability and Sn for improving castability is Mg-Sn-P-In-
Since the castability of the Mn copper alloy is greatly affected, it is necessary to set the additive amount of Sn to 1.0 or more with respect to the additive amount of Mg. When the addition ratio of Mg and Sn is Mg> Sn, the castability of the Mg—Sn—P—In—Mn copper alloy cannot be improved.

According to a second aspect of the present invention, Mg produced by continuous casting is 0.05 to 0.25 mass%, Sn is 0.1 to 0.6 mass%, and P is 0.02 to 0.08 m%.
The ratio of the ass%, 0.02~0.2mass% of In, and Mn contained 0.05～0.1Mass%, the balance being copper and unavoidable impurities was content and the Sn content of the Mg However, a cast rod of a copper alloy in which Mg: Sn = (1) :( 1.0 or more) is rolled, and after drawing, is 500 to 600.
C., followed by wire drawing at a working ratio of 85 to 95%, and a final heat treatment by continuous annealing at 320 to 420 ° C. to produce a complicated heat treatment process (solution treatment, age hardening treatment). A copper alloy of a solid solution strengthening type which does not require a metal alloy can be obtained, particularly, an inexpensive copper alloy having excellent elongation characteristics, bending characteristics, wire drawing characteristics, and excellent tensile strength.

[0014] The continuous annealing of a cast rod produced by continuous casting after rolling and drawing is performed in order to recover the work structure in rolling and drawing and to reduce the elongation and flexibility without lowering the tensile strength in the final heat treatment. It is for improving. The reason why the annealing temperature of the continuous annealing is set to 500 to 600 ° C. is that when the annealing temperature is lower than 500 ° C., it is not possible to sufficiently recover the work structure in rolling and wire drawing, so that the elongation is sufficient in the final heat treatment. If the annealing temperature does not increase and the annealing temperature exceeds 600 ° C., the discoloration during the annealing treatment is remarkable, and it becomes difficult to adjust the winding tension as a wire. The reason why the wire is drawn after annealing at 500 to 600 ° C. is to improve the elongation and the flexibility without significantly lowering the tensile strength in the final heat treatment. The reason for setting the working ratio of the drawing to 85 to 95% is that if the working ratio is lower than 85%, sufficient tensile strength cannot be secured after the final heat treatment, and if the working ratio exceeds 95%, the final heat treatment is not performed. This is because elongation and flexibility are not sufficiently improved later. Further, the reason for performing the final heat treatment by continuous annealing is to improve elongation and flexibility.
The reason for setting the annealing temperature of the continuous annealing to 320 to 420 ° C. is that the elongation does not sufficiently improve when the annealing temperature is lower than 320 ° C., and the tensile strength decreases when the annealing temperature exceeds 420 ° C. is there.

[0015]

EXAMPLES Specific examples of the conductive high-strength copper alloy having excellent elongation characteristics and bending characteristics according to the first aspect of the present invention will be described below in comparison with comparative examples and conventional examples. As an embodiment of the invention described in claim 1 of the present application, in a graphite crucible furnace kept in an inert gas atmosphere, an electrolytic copper ingot is melted under a graphite particle coating, and then Mg, Sn, In are converted to pure metal. P and Mn are added in the form of a master alloy to obtain a uniform molten metal. This was subjected to continuous casting to produce a 20 mmφ cast rod having the composition of each Example (No. 1 to No. 11) as shown in Table 1. After cold-rolling these, 3.2mmφ by wire drawing machine
, And continuously annealed at 550 ° C. This was further drawn to 1.0 mmφ by a wire drawing machine, and then continuously annealed at 400 ° C. using an electric furnace in an inert gas atmosphere. afterwards,
The conductivity, tensile strength, elongation, and flexibility were measured.

In the prior art 1, in a graphite crucible furnace kept in an inert gas atmosphere, an electrolytic copper ingot was melted under a coating of graphite particles, and Ni, Sn, and In were converted into pure metals.
Si is added in the form of a mother alloy to obtain a uniform molten metal. This was subjected to continuous casting to produce a 20 mmφ cast rod having the composition shown in Table 1. After cold-rolling this, 3.
After the wire was drawn to 2 mmφ, it was heated and held at 900 ° C. for 1 hour in an inert gas atmosphere furnace, then cooled with water and subjected to a solution treatment. Thereafter, the wire was drawn to 1.0 mmφ, and further subjected to age hardening treatment in an inert gas atmosphere furnace at 470 ° C. for 6 hours. afterwards,
The conductivity, tensile strength, elongation, and flexibility were measured. Hard copper is a normal oxygen-free copper wire. In addition, as for the annealed copper, a normal oxygen-free copper wire was subjected to an annealing treatment at 300 ° C. for 2 hours in an inert gas atmosphere furnace, and then the electrical conductivity, tensile strength, elongation and flexibility were measured. Table 2 shows comparative examples (No. 1 to No. 10), and each comparative example is manufactured by the same manufacturing method as the example. The annealing temperature in each of the continuous annealing machines shown in Tables 1 and 2 is based on the assumption that the thermal efficiency is 90%, the annealing voltage (V), the annealing speed (m / min), and the conductor resistance (Ω) of each copper alloy wire. ). Further, in the bending test for each of the copper alloys shown in Tables 1 and 2, as shown in FIG.
In the state where a tensile load W of 2 kg is applied to the other end, it is repeated as shown in FIG. 1 (A) → (B) → (C) → (D) until one 90 ° bending to the left and right is broken, The repetitive bending strength represented by the number of bendings before breaking was defined as flexibility. The alloys No. 1 to No. 10 of the comparative example have a composition of M
g, Sn, P, In, Mn and alloys No. 1 to No. of the present invention
Although it is composed of the same composition as that of No. 11, the content of each composition of the alloy of the comparative example is different from the content of each composition of the present invention.

[0017]

[Table 1]

[Table 2] The examples (No1 to No11) in Table 1 correspond to the Ni of the conventional example 1.
Although it is slightly inferior in tensile strength as compared with -Si-In-Sn copper alloy, it has good characteristics in electrical conductivity, elongation, and flexibility (repetitive bending strength). Further, the embodiment (No. 1)
No. 11) show that although the conductivity is inferior to that of hard copper, the tensile strength, the elongation and the flexibility are greatly improved.

Further, the embodiments (No1 to No11)
Compared to the annealed copper having excellent flexibility, it is understood that the annealed copper has properties equal to or higher than that of the annealed copper. Thus, Table 1
It can be seen that the Examples (No. 1 to No. 11) generally have better characteristics than the conventional examples as compared with the conventional examples.

The comparative examples (No. 1 to No. 10) in Table 2 are as follows. In Comparative Example 1, the added amount of Mg was equal to or more than the upper limit of the range of the added amount of Mg in the invention described in claim 1 of the present application, and the tensile strength was good, but the electrical conductivity, elongation, and flexibility were reduced. . Further, the ratio of Mg: Sn is 1:
When the ratio is 1.0 or less, the wire drawing workability in the wire drawing machine deteriorates. In Comparative Example 2, since the amount of Mg added was equal to or less than the lower limit of the range of the amount of Mg added in the first aspect of the present invention, the tensile strength, elongation, and flexibility were significantly poor. Comparative Example 3 is based on Sn
Is more than the upper limit of the range of the addition amount of Sn in the invention of claim 1 of the present application, and the tensile strength is good,
Electrical conductivity, elongation and flexibility are extremely poor. Comparative Example 4
Since the amount of Sn added is equal to or lower than the lower limit of the range of the amount of Sn added in the first aspect of the present invention, the conductivity is good, but the tensile strength, elongation, and flexibility are significantly inferior. Also, M
Since the ratio of g: Sn is 1: 1.0 or less, drawability in a wire drawing machine deteriorates. In Comparative Example 5, since the amount of P added was equal to or more than the upper limit of the range of the amount of P added in the first aspect of the present invention, the conductivity was significantly poor. In Comparative Example 6, since the added amount of P is equal to or less than the lower limit of the range of the added amount of P in the first aspect of the present invention, the conductivity is good, but the wire drawing workability in a wire drawing machine is deteriorated. In Comparative Example 7, since the amount of In added was equal to or more than the upper limit of the range of the amount of In added in the first aspect of the present invention, the tensile strength was good, but the conductivity was extremely poor. In Comparative Example 8, the amount of In added was set to claim 1 of the present application.
The tensile strength is inferior because of the lower limit of the range of the added amount of In in the described invention. In Comparative Example 9, since the amount of Mn added was equal to or greater than the upper limit of the range of the amount of Mn added in the first aspect of the present invention, the conductivity was significantly poor. Comparative Example 10 is Mn
Is lower than the lower limit of the range of the amount of Mn in the invention described in claim 1 of the present application, so that the elongation and the flexibility are inferior.

Therefore, according to the embodiment of the conductive high-strength copper alloy having excellent elongation characteristics and bending characteristics according to the present invention, it has characteristics suitable for a conductor of an electric wire for an automobile, and has a small and light outer conductor diameter. Mechanical strength corresponding to the formation of the terminal can be secured, and disconnection due to tension and bending at the crimp terminal portion can be reduced. Further, according to this embodiment, the manufacturing cost can be reduced.

Next, an embodiment of the method for producing a conductive high-strength copper alloy having excellent elongation characteristics and bending characteristics according to the second aspect of the present invention will be described in comparison with comparative examples. Claim 2
The method for producing a high-strength copper alloy for electric conduction having excellent elongation and bending characteristics according to the described invention is described in US Pat.
g: 0.05-0.25 mass%, Sn: 0.1-
0.6 mass%, P is 0.02 to 0.08 mass
%, 0.02 to 0.2 mass% of In, and 0.02% of Mn.
5 to 0.1 mass%, the balance being composed of copper and unavoidable impurities. The ratio of the Mg content to the Sn content is Mg: Sn = (1) :( 1.0 After rolling and drawing a copper alloy casting rod,
C., followed by wire drawing at a working rate of 85 to 95%, and a final heat treatment is performed by continuous annealing at 320 to 420 ° C.

Table 3 shows examples and comparative examples of the conductive high-strength copper alloy produced by the method for producing a conductive high-strength copper alloy having excellent elongation characteristics and bending characteristics. Table 3
(No12) and Comparative Examples (No11-No)
15) means that the composition is the same and the production method is changed.

[0023]

[Table 3] Example 12 has the same composition as Example 11 in Table 1 and was manufactured by the same manufacturing method. That is, in Example 12, in a graphite crucible furnace kept in an inert gas atmosphere, after dissolving electrolytic copper ingot under the coating of graphite particles, Mg, Sn, and In were converted to pure metal in the form of P. , M
n was added in the form of a mother alloy to obtain a uniform molten metal, which was cast into a 20 mmφ cast rod by continuous casting. After cold rolling, the rod was drawn to 3.2 mmφ with a wire drawing machine, and was then drawn at 550 ° C. After continuous annealing, wire drawing to 1.0mmφ by wire drawing machine,
It is manufactured by continuous annealing at 400 ° C. using an electric furnace in an inert gas atmosphere. As a result of performing each property test on the high-strength copper alloy wire for conductivity, the conductivity was 64.8.
% IACS, tensile strength 53.4 kg / mm2, elongation 8.0
%, And the flexibility is 49 times.

In Comparative Example 11, the intermediate annealing temperature was 350 ° C. and the annealing temperature range (500
６００600 ° C.) or lower, and the intermediate annealing temperature is low, so that the intermediate annealing cannot sufficiently recover the work structure in rolling and drawing, and the final annealing performed at 400 ° C. has a tensile strength of 51. 7 kg / mm ² and an elongation of 6.2%, the elongation could not be improved without lowering the tensile strength as in Example 12. In Comparative Example 12, the wire drawing ratio from the intermediate annealing to the final annealing was 75%, which was lower than or equal to the lower limit of the working ratio range (85 to 95%) in the invention described in claim 2 of the present invention. Strength 4
After the final heat treatment of 7.0 kg / mm ² , sufficient improvement in tensile strength by wire drawing cannot be obtained. In Comparative Example 13, the wire drawing rate from the intermediate annealing to the final annealing was 99%, which is more than the upper limit of the working rate range in the invention described in claim 2 of the present application, and the tensile strength was 55% by the final annealing (400 ° C.). .6
kg / mm ² , but the elongation is 6.0
%, And the flexibility has not been improved to 41 times.

In Comparative Example 14, the final annealing temperature was 320 ° C. and the annealing temperature range (320
４２０420 ° C.) or less, and the tensile strength is 54.5.
kg / mm ² , but the annealing effect was not obtained, the elongation was 4.2%, and the flexibility was not improved to 38 times. Comparative Example 15
Has a final annealing temperature of 500 ° C., which is equal to or higher than the upper limit of the annealing temperature range in the invention of claim 2 of the present application. According to Comparative Example 15, the conductivity is 66.3% IACS, and the elongation is 8.2. %, The flexibility is 50 times, which is good, but the tensile strength is greatly reduced to 43.2 kg / mm ² .

As described above, according to the present embodiment, complicated heat treatment steps such as solution treatment and aging treatment can be omitted, and both intermediate annealing for solution treatment and final annealing for aging treatment are performed in the electric wire manufacturing process. It can be carried out in two heat treatments using a normally used continuous annealing machine,
It has a tensile strength higher than that of hard copper, and the electrical conductivity slightly decreases,
It has better flexibility than annealed copper,
Although the tensile strength is lower than that of the n-Sn copper alloy, the elongation, conductivity, and flexibility are excellent, and the additive element is Ni-Si-I.
It is less expensive than n-Sn copper alloy, and the manufacturing process can be simplified.

[0027]

According to the first aspect of the present invention, flexibility, elongation characteristics, and tensile strength are improved without causing a decrease in conductivity, and high strength against mechanical impact is maintained. It is possible to obtain a high-strength copper alloy for electric conduction in which disconnection due to bending is reduced.

According to the second aspect of the present invention, it is a solid solution strengthened type copper alloy that does not require complicated heat treatment steps (solution treatment, age hardening treatment), and is particularly excellent in bending characteristics and wire drawing characteristics. An inexpensive copper alloy excellent in tensile strength and elongation can be manufactured.

[Brief description of the drawings]

FIG. 1 is a diagram showing a bending test method of an example of the present invention, a comparative example, and a conventional example.

[Explanation of symbols]

 1 ……………………………………………………………………………………………………………………………………………………………

──────────────────────────────────────────────────の Continuation of front page (51) Int.Cl. ⁷ identification code FI C22F 1/00 630 C22F 1/00 630G 661 661 661A 691 691B 694 694A (58) Field surveyed (Int. Cl. ⁷ , DB name) C22F 1/00-3/02 C22C 9/00-9/10 H01B 1/02

Claims (2)

(57) [Claims] (1) Mg is contained in an amount of 0.05 to 0.25 mass%,
0.1 to 0.6 mass% of Sn and 0.02 to 0.
08 mass%, In is 0.02 to 0.2 mass%,
The Mn containing 0.05～0.15Mass%, the balance being copper and unavoidable impurities was the ratio between the content and the Sn content of the Mg is, Mg: Sn = (1) :( 1.0 A high-strength copper alloy for conductive use having excellent elongation characteristics and bending characteristics. 2. Mg of 0.05 to 0.25 mass%,
0.1 to 0.6 mass% of Sn and 0.02 to 0.
08 mass%, In is 0.02 to 0.2 mass%,
The Mn containing 0.05～0.15Mass%, the balance being copper and unavoidable impurities was the ratio between the content and the Sn content of the Mg is, Mg: Sn = (1) :( 1.0 A cast rod produced by continuous casting of the above copper alloy is cold-rolled, continuously annealed at 500 to 600 ° C. after drawing, and then drawn at a working rate of 85 to 95%.
A method for producing a conductive high-strength copper alloy having excellent elongation characteristics and bending characteristics, which is produced by continuous annealing at -420 ° C.