JPH06336632A - High strength copper alloy for electric conduction - Google Patents

Abstract

PURPOSE:To obtain a copper alloy exhibiting excellent wire drawing characteristics only by easy annealing after continuous casting and excellent in electric conductivity, tensile strength, elongation and bending strength by incorporating each a specified amt. of MMg, Ni, Sn, Li and Te into copper. CONSTITUTION:This copper alloy consists of, by weight, 0.1-0.5% Mg, 0.1-0.5% Ni, 0.1-0.5% Sn, 0.02-0.2% Li, 0.02-0.2% Te and the balance Cu. Since this copper alloy has satisfactory castability, a cast rod obtd. by continuously casting this alloy is almost free from defects, has satisfactory wire drawing performance and has stably such caracteristics as high tensile strength, bending strength and electric conductivity.

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 a high-strength electric wire, and more particularly to a copper alloy suitable for producing a conductor for a conductive wire having a small diameter and sufficient mechanical strength.

[0002]

2. Description of the Related Art Conventionally, an annealed copper wire has been widely used as an electric wire for an internal wiring of an automobile, but in recent years, the number of wiring circuits in the automobile has increased with the progress of computerization of various in-vehicle devices. The occupying space of electric wires and the weight thereof have been remarkably increased. Further, among such electric wires for automobiles, it is necessary to make the diameter of the conductor larger than an electrically necessary diameter in order to secure mechanical strength among electric wires used for a minute current circuit.

Recently, it has been desired to reduce the weight of automobiles from the viewpoint of energy saving, and thinning of conductors has been studied in order to reduce the weight of electric wires for automobiles. Therefore, if a hard copper wire that can secure the mechanical strength even if the conductor diameter is reduced is used, the elongation is remarkably small, and the crimping point of the terminal becomes a mechanical weak point, which easily causes disconnection and lacks reliability. There's a problem. Therefore, for example, magnesium copper alloys, iron-phosphorus-nickel-silicon copper alloys, etc. can be used as copper alloys that can secure sufficient mechanical strength even if the diameter is further reduced, can withstand repeated bending, and have good conductivity. Being developed.

However, the magnesium-copper alloy improves the tensile strength by dissolving magnesium in copper as a solid solution. However, the tensile strength of magnesium-copper alloy varies due to melting or oxidation during casting. However, there is a drawback that the characteristics such as elongation and conductivity are not stable and easily vary. In addition, there is a problem in that the castability is difficult, casting cracks are likely to occur during continuous casting, and many wire breakages occur during wire drawing, resulting in poor wire drawing workability.

Iron-phosphorus-nickel-silicon-copper alloys improve the tensile strength, elongation, conductivity, etc. by finely depositing these minor components, but they are usually age hardening alloys. In addition to the electric wire manufacturing process described above, heat treatment such as solution treatment and age hardening treatment is required. If the temperature control during this heat treatment is not accurate, good characteristics will not be obtained and variations will occur easily, and further processing equipment and There is also a problem that the process work increases and the cost increases significantly.

[0006]

Under such circumstances, the present invention exhibits excellent wire drawing properties without requiring a complicated heat treatment step, only performing simple annealing after performing continuous casting. At the same time, not only the conductive properties but also the tensile strength,
The object is to provide a copper alloy having excellent elongation and flexural strength.

[0007]

The object of the present invention is as follows.
0.1-0.5% by weight of magnesium, and 0.1-0.
5 wt% nickel, 0.1-0.5 wt% tin,
0.02 to 0.2 wt% lithium and 0.02 to 0.
Achieved by a high-strength copper alloy for conduction, characterized in that it contains 2% by weight of tellurium, the balance being copper.

Magnesium contained in the copper alloy of the present invention is an element which has a large effect of improving the tensile strength of the copper alloy although the decrease in conductivity is small. However, if it is less than 0.1% by weight, a sufficient effect does not appear, and if it exceeds 0.5% by weight, not only the effect of improving the tensile strength is saturated, but also the conductivity is remarkably lowered, and further during casting, Porosity is apt to occur, and in particular, during continuous casting, casting cracks that cause wire breakage are likely to occur during wire drawing.

Further, nickel is not only effective in greatly improving the castability of the copper alloy, but also effective in improving the tensile strength and the elongation rate after annealing. However, if the content is less than 0.1% by weight, it is not possible to compensate for the decrease in castability due to the addition of magnesium. On the other hand, if it exceeds 0.5% by weight, the effects such as the improvement in castability become remarkable, but the conductivity decreases. Is large, which is not preferable. Therefore, the ratio of nickel to magnesium is preferably 0.8 or more from the viewpoint of castability, and is preferably 1.0 or less from the viewpoint of conductivity.

The addition of tin has the effect of not only greatly improving the elongation rate and bending strength after annealing but also improving the tensile strength and castability. However, if the content is less than 0.1% by weight, the effect is small. On the contrary, if the content is more than 0.5% by weight, not only the above-mentioned effects of improving the physical properties and castability are saturated, but also the conductivity is remarkably lowered. So undesirable.

Further, lithium is effective in preventing changes in properties due to oxidation during melting and casting of a copper alloy, and also contributes to improvement in tensile strength. The characteristic stabilizing effect is 0.0
Although it appears when the amount is 2% by weight or more, the effect is saturated even when the amount exceeds 0.2% by weight, the cost is increased and the conductivity is lowered, which is not preferable.

Tellurium also has the effect of significantly increasing the electrical conductivity of the copper alloy, the effect of which is 0.02% by weight.
If it is less than 0.2% by weight, it is not so clear. If it exceeds 0.2% by weight, it is saturated, and if it is more than 0.2% by weight, the conductivity is lowered, and the castability is drastically lowered.

[0013]

The high-strength copper alloy for electroconductivity of the present invention as described above has good castability, so that the cast rod obtained by continuous casting has few defects and has good wire drawing performance, and stable tensile strength. It has the characteristics of high bending strength and high conductivity and high electrical conductivity.

[0014]

[Examples] Copper was melted in a melting furnace having a graphite particle coating layer under an inert gas atmosphere, and magnesium, nickel, tin, and lithium were added in the form of pure metals, and tellurium was used in the form of a copper master alloy. In order to obtain the composition shown in Table 1, a uniform molten metal was prepared. Among these alloys, 1 to 10 are copper alloys of the present invention, 11 to 27 are control copper alloys outside the scope of the present invention, and 28 to 36 are conventionally known copper alloys, of which 35 are Corresponds to an ordinary hard copper wire.

[0015]

[Table 1]

Next, these molten metals were continuously cast to obtain cast rods each having a diameter of 20 mm, further cold-rolled, drawn to a diameter of 1 mm, and then annealed in an electric resistance type annealing furnace to produce electric wires. The alloy 36 was obtained by adding iron, phosphorus, manganese, and silicon in the form of a mother alloy. In the wire forming, a cast rod having a diameter of 20 mm was obtained in the same manner as above, and then cold rolled. After that, wire drawing was performed to obtain a wire having a diameter of 3.2 mm, which was further heat-treated at 900 ° C. for 1 hour in an inert gas atmosphere furnace and then water-cooled for solution treatment. After that, the wire was drawn to a diameter of 1 mm and subjected to an aging treatment at 470 ° C. for 6 hours in an inert gas atmosphere furnace to manufacture an electric wire.

For these electric wires, the electric conductivity (% IAC
S), tensile strength (kg / mm ² ), elongation (%), and repeated bending strength were measured, and the results are shown in Table 2. The repeated bending strength was measured by the following method. That is, as shown in FIG. 1, the wire 1 is clamped by a jig 1 having a corner curvature R of 4 mm, and a tensile load W of 2 kg is applied, and the wire is bent 90 ° left and right in the order of A → B → C → D. This was repeated, and the number of times this was repeated until the electric wire was broken was counted to obtain the repeated bending strength.

As a parameter for evaluating the castability of the copper alloy, that is, the degree of occurrence of defects during casting, the number of breaks during wire drawing while obtaining an electric wire of 50 kg was taken up. That is, a casting rod with a diameter of 20 mm obtained by continuous casting from a uniform molten alloy of copper alloy was first cold-rolled into a wire with a diameter of 9.5 mm. Next, this was drawn to a diameter of 2.6 mm by a large continuous wire drawing machine, and the number of wire breaks during this period was counted and recorded as the number of wire breaks of the large machine. Next, this wire was drawn to a diameter of 0.6 mm by a small continuous wire drawing machine, and the number of wire breaks during this time was counted and recorded as the number of wire breaks in the small machine. Further, this was drawn by a fine wire machine to a diameter of 0.08 mm, and the number of wire breakages during this time was counted and recorded as the number of wire breakages of the fine wire machine. The number of breaks thus obtained is also shown in Table 2.

[0019]

[Table 2]

From these results, alloys 1-10 of the present invention
Compared with the control alloys 19, 20, 24, 26 and 27, the conductivity is significantly improved by the addition of an appropriate amount of tellurium, but excessive addition may rather reduce the conductivity and lead to an increase in the number of wire breakages. Recognize. Compared with the control alloys 11 to 27, the tensile strength, the elongation, and the flexural strength cannot be improved when the addition of magnesium, nickel, tin, and lithium is small, and the conductivity is reduced when the content is too large. I understand.

Further, the alloys of the present invention are known alloys 28 to 36.
Compared with, the conductivity, tensile strength, elongation, and repeated bending strength all have the same or higher performance, not only the balance of performance is excellent, but there is no problem in wire drawing. It can also be seen that it has excellent castability.

[0022]

EFFECTS OF THE INVENTION The high-strength copper alloy for electroconductivity of the present invention is excellent not only in electrical conductivity but also in tensile strength, elongation, and repetitive bending strength, and moreover, it has good castability. It is possible to easily manufacture an excellent thin wire with stable characteristics without

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an apparatus used to measure the repeated bending strength of an electric wire.

[Explanation of symbols] 1 jig 2 electric wire W tensile load

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuhito Taki 2771 Ooka, Numazu City, Shizuoka Prefecture Yazaki Electric Cable Co., Ltd.

Claims (1)

[Claims] 1. 0.1 to 0.5% by weight of magnesium, 0.1 to 0.5% by weight of nickel, 0.1 to 0.
High-strength copper for electrical conduction, containing 5 wt% tin, 0.02 to 0.2 wt% lithium, and 0.02 to 0.2 wt% tellurium, with the balance being copper. alloy.