JPH1192897A - Manufacture of heat resistant aluminum alloy lead wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacture of a heat resistant aluminum alloy lead wire having heat resistance and electric conductivity equal to those of the conventional heat resistant aluminum alloy and also having strength improved to a value equal to or higher than that of a high strength aluminum alloy. SOLUTION: An aluminum alloy, having a composition consisting of, by weight, 0.29-1.0% Zr. 0.03-0.4% Si, 0.08-0.8% Fe, 0.005-0.05% Be, 0.001-0.1% Ti, and the balance Al with inevitable impurities, is melted and cast at >=5 deg.C/sec cooling rate. Working is applied, while performing cooling from 450-580 deg.C at >=5 deg.C/sec cooling rate, at >=70% reduction of area until <=200 deg.C finishing temp. is reached. Subsequently, heat treatment is performed at 300-500 deg.C for 6-250 hr and then cold working is applied at >=60% draft. By this method, the heat resistant aluminum alloy lead wire can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a heat-resistant aluminum alloy wire having excellent conductivity, heat resistance and mechanical strength.

[0002]

2. Description of the Related Art A heat-resistant aluminum alloy obtained by adding a small amount of zirconium (Zr) to electric aluminum (Al) has been put to practical use in order to increase the power transmission capacity due to an increase in power demand. When the power transmission capacity increases, the temperature of the electric wire increases, and thus such a heat-resistant aluminum alloy conductor is required.

[0003]

However, the conventional heat-resistant aluminum alloy has heat resistance, but the tensile strength is equivalent to that of ordinary aluminum for electric use. Can not be overhead line. On the other hand, the present applicant has previously proposed a method for manufacturing a heat-resistant aluminum alloy wire whose strength has been improved to be equal to or higher than that of a high-strength aluminum alloy (Japanese Patent Laid-Open No. 64-65).
246).

[0004] This invention has the same heat resistance and conductivity as conventional heat-resistant aluminum alloys, and has a strength equal to or higher than that of a high-strength aluminum alloy by changing the composition and heat treatment conditions from the prior invention. It is an object of the present invention to provide a method for manufacturing an improved heat-resistant aluminum alloy conductor.

[0005]

According to the present invention, there is provided a method for manufacturing a heat-resistant aluminum alloy wire, comprising: 0.29 to 1.0% by weight of Zr; 0.03 to 0.4% by weight of Si;
0.8 wt% Fe, 0.005-0.05 wt% B
e, an aluminum alloy containing 0.001 to 0.1% by weight of Ti and the balance being Al and unavoidable impurities is melted, and then cast while cooling at a cooling rate of 5 ° C./sec or more; While cooling at a cooling rate of 5 ° C./sec or more from a temperature of 580 ° C. or more, a process of reducing the area by 70% or more is performed until a finishing temperature of 200 ° C. or less is obtained.
After heat treatment at 00-500 ° C for 6-250 hours, 60%
It is characterized in that cold working is performed at the above working ratio. The present invention further provides a method for manufacturing a semiconductor device, comprising:
The heat treatment is performed at 50 ° C. for 1 to 100 hours.

The reasons for adding each component and the reasons for limiting the composition in the present invention are as follows. In the following description, the percentage by weight of the composition is simply expressed as%. Zr Zr is a component that improves the heat resistance of the Al alloy. A
The solid solubility limit of Zr in the l-Zr alloy is 0.28%, and Zr exceeding this solid solubility limit is added to forcibly form a solid solution of Zr, and a compound of Al and Zr is finely precipitated in the form of Al ₃ Zr. By doing so, the heat resistance can be increased and the strength can be improved at the same time. If the Zr content is less than 0.29%, a precipitate that secures sufficient strength and heat resistance cannot be obtained even if the heat treatment described below is performed. On the other hand, if the Zr content exceeds 1.0%, the temperature of the molten metal becomes too high, which makes casting difficult, and also lowers the electrical conductivity of the wire.

Si Si (silicon) is a component that serves as a nucleus for the precipitation of Zr and promotes the precipitation of Zr and also increases the strength of the wire.
If the Si content is less than 0.03%, nuclei for Zr precipitation are insufficient, and the effect of Zr precipitation cannot be obtained. If the Si content exceeds 0.4%, embrittlement occurs and processing becomes difficult, and the conductivity of the wire also decreases.

[0008] Fe Fe (iron) is added to improve the strength and heat resistance of the Al alloy. If the Fe content is less than 0.08%, desired strength and heat resistance cannot be obtained.
After the heating, the Al alloy is embrittled and the electrical conductivity is lowered.

[0009] BeBe (beryllium) combines with various unavoidable impurities in the matrix and precipitates, and acts to increase the electrical conductivity by cleaning the inside of the matrix. When the content of Be is less than 0.005%, the effect of improving the conductivity cannot be obtained. When the content of Be exceeds 0.5%, the effect of improving the conductivity is not only saturated but also excessively added. Then, Be dissolves in the matrix to lower the conductivity.

[0010] When Ti (titanium) is added during Al smelting, it combines with unavoidable impurities to become a crystal nucleus and has an effect of refining the cast structure. More specifically, it has the effect of improving the uniformity of the structure and the surface properties at the time of casting, and has the effect of reducing disconnection during rolling or wire drawing in a subsequent process due to surface defects and the like, thereby improving productivity. . However, the content of Ti is 0.001%
If the amount is smaller than the above, the above-mentioned effect of miniaturization cannot be obtained. If the amount exceeds 0.1%, the solid solution in the matrix Al decreases the electric conductivity.

Next, conditions for producing a conductor from an Al alloy having the above-described composition will be described. First, the cooling rate during casting was set to 5 ° C./sec or more in order to forcibly dissolve Zr added beyond the solid solubility limit. If the cooling rate is less than this, Zr in a portion exceeding the solid solubility limit will precipitate during casting.

At the time of rolling, while cooling at a cooling rate of 5 ° C./sec, processing is started from a temperature of 450 to 580 ° C., and the Al alloy is reduced at a rate of 70% or more until the temperature becomes 200 ° C. or less. Process. If the rolling start temperature is lower than 450 ° C., the ingot is hard and difficult to process, and cracks may occur.
If the rolling start temperature exceeds 580 ° C., hot cracking is likely to occur. When the rolling end temperature is higher than 200 ° C., the effect of cooling is weak, so that the forced solid solution of Zr is not sufficiently performed. On the other hand, if the reduction in area in rolling is less than 70%, the strength of the final wire rod will be insufficient.

Thereafter, the rolled wire is heat-treated at a temperature of 300 to 500 ° C. for 6 to 250 hours, whereby Zr is dispersed and precipitated as fine Al ₃ Zr, thereby improving the strength, heat resistance and conductivity of the Al alloy. I do. Heat treatment temperature is 30
If the temperature is lower than 0 ° C., the precipitation of Zr is not sufficient, and the desired strength, electrical conductivity and heat resistance cannot be obtained.
When the temperature exceeds ℃, recrystallization starts and the precipitate becomes coarse, the strength is reduced, and expensive Zr is wasted. Even in the above heat treatment temperature range, if the heat treatment time is less than 6 hours, Zr
Is not sufficiently carried out, and when the time exceeds 250 hours, the strength is greatly reduced. More preferred conditions for this heat treatment are:
30-50 hours at a temperature of 400-500 ° C. After this heat treatment, cold working with a surface reduction of 60% or more is performed. This is to increase the strength of the Al alloy. If the surface reduction is less than 60%, work hardening is insufficient and sufficient strength is obtained. Can not be obtained.

By the above cold drawing, characteristics satisfying the desired performance can be obtained as a finished wire. However, after the cold drawing, a heat treatment at 200 to 450 ° C. for 1 to 100 hours is applied to the wire. Thus, a conductive wire having further improved conductivity and heat resistance can be obtained. In this case, if the heat treatment temperature is lower than 200 ° C., no improvement in characteristics is observed. Heat treatment temperature is 450
When the temperature exceeds ℃, there is a disadvantage that the softening becomes remarkable. Even in the above temperature range, if the treatment time is less than 1 hour, no sufficient improvement in properties is observed, and if it exceeds 100 hours, softening cannot be ignored. More preferable conditions of this heat treatment are a temperature of 350 to 400 ° C. for 5 to 10 hours.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, characteristic data of an Al alloy wire of an example manufactured under various conditions by the method of the present invention will be described together with a comparative example. The following experimental data are all based on the continuous casting and rolling method, but similar characteristics can be obtained by the method of rolling the rod.

Each element (Zr, Si, Fe, Be, Ti)
Relationship between the Addition Amount and the Properties An alloy having the composition shown in Table 1 below was melted and cast at a cooling rate of 15 ° C./sec. When the temperature of the ingot reached 520 ° C., cooling was performed at 15 ° C./sec. Rolling was started at a speed, and a rough wire having a diameter of 9.5 mm was produced under the conditions of a working ratio of 90% and a finishing temperature of 170 ° C. After the obtained rough drawn wire was heat-treated at 380 ° C. for 48 hours, it was cold-worked by a continuous wire drawing machine to obtain a 2.8 mm diameter wire rod. Table 1 shows the characteristics of the wire rod of each sample.

[0017]

[Table 1]

In Table 1, the heat resistance of the obtained wire was 420
The tensile strength after heating at 1 ° C. for 1 hour is represented by a ratio (residual%) to that before heating. Example Al
The alloy is superior in all of the tensile strength, electrical conductivity and heat resistance as compared with those of the comparative example. Comparative Examples 22 to 2
Alloy No. 4 was difficult to cast and the casting was stopped. Therefore, no characteristics are required. The alloy of Comparative Example 25 was barely castable.

Relationship between Cooling Rate and Properties During Casting and Rolling The data in Table 1 are based on the case where the cooling rate during casting was fixed at 15 ° C./sec in any composition system. No. Table 2 below shows the properties when the 16 Al alloys were cast and rolled at various cooling rates.

[0020]

[Table 2]

As shown in Table 2, if the cooling rate during casting and rolling is less than 5 ° C./sec, the strength and heat resistance are not sufficient. This is because the amount of Zr forcibly dissolved is small.

Relationship between Rolling End Temperature and Properties Sample No. 1 in Table 1 Cooling rate of Al alloy of composition 16
Casting and rolling were performed at a rate of ° C./sec, and a rough drawn wire having a diameter of 9.5 mm was prototyped by varying the rolling end temperature. The rolling end temperature was adjusted by the amount of the cooling liquid. 38
After a heat treatment at 0 ° C. for 48 hours, a diameter of 3.
A 5 mm wire was used. Table 3 shows the properties of the obtained wire.

[0023]

[Table 3]

From the results shown in Table 3, when the rolling end temperature (finish temperature) exceeds 200 ° C., the strength and heat resistance become insufficient. This is also a result of the reduced amount of Zr forcibly forming a solid solution.

The reduction in area during rolling up to the rough drawn wire diameter and the characteristics
Sexual relationship Table 1 sample No. The Al alloy No. 16 was cast and rolled at a cooling rate of 15 ° C./sec while variously reducing the area reduction during rolling, and the rolling end temperature was 170 ° C., and the diameter was 9.5 m.
A prototype of a rough drawing line of m was produced. Further, the rough wire was drawn at 380 ° C for 4 hours.
After the heat treatment for 8 hours, the wire was cold drawn by a continuous wire drawing machine to obtain a wire rod having a diameter of 3.5 mm. The properties of the wire are shown in Table 4 below.
Shown in

[0026]

[Table 4]

From Table 4, it can be seen that when the area reduction rate during rolling is less than 70%, the strength and heat resistance are low. This is because when the area reduction rate is low, dislocations are less likely to occur during rolling, and as a result, Al ₃ Zr cannot be finely dispersed and precipitated.

Relationship between heat treatment conditions and characteristics of rough drawn wire Sample No. 1 in Table 1 The Al alloy No. 16 was cast and rolled at a cooling rate of 15 ° C./sec, and a rolling finish temperature of 170 ° C. was used to produce a rough drawn wire having a diameter of 9.5 mm. The obtained rough drawn wire was heat-treated at various temperatures and times, and then cold drawn by a continuous drawing machine to obtain a wire having a diameter of 3.5 mm. Table 5 below shows the characteristics of the wire.

[0029]

[Table 5]

As shown in Table 5, the heat treatment temperature was 300 ° C.
If it is lower than 260 ° C., precipitation of Zr is insufficient, and tensile strength, electric conductivity and heat resistance are low. Heat treatment temperature is 500
If the temperature exceeds 530 ° C. (530 ° C.), recrystallization starts and a decrease in strength is observed. Even in the temperature range of 300 to 500 ° C., when the heat treatment time is less than 6 hours (3 hours), the tensile strength,
When the electric conductivity and the heat resistance are not sufficient, and when the time exceeds 250 hours (270 hours), a decrease in strength is also observed. In particular, when the heat treatment temperature was high, many coarse precipitates were observed, and it was confirmed that softening was remarkable.

Table 5 shows the relationship between heat treatment conditions and characteristics in the wire drawing step.
The sample which was heat-treated at 12 ° C. for 12 hours (indicated by an asterisk in Table 5) was further heat-treated under various conditions in a cold-worked wire stage having a diameter of 2.8 mm. The properties obtained as a result are shown in Table 6 below.

[0032]

[Table 6]

From Table 6, it can be seen that effects such as improvement in conductivity and heat resistance are obtained at a heat treatment temperature of 200 to 450 ° C. However, even in the above temperature range, if the heat treatment time is less than 1 hour, the effect is not sufficient, and if it exceeds 100 hours, the strength is reduced.

[0034]

As described above, according to the present invention, by optimizing the composition and the conditions during casting and rolling, a high-strength heat-resistant aluminum having high strength, high conductivity and excellent heat resistance is obtained.
An alloy conductor can be obtained. By using such a high-strength heat-resistant Al alloy wire, it is possible to increase the power transmission capacity, and the present invention has great benefits in responding to an increase in power demand.

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Claims (2)

[Claims] 1. A method according to claim 1, wherein said Zr is present in an amount of from 0.29 to 1.0% by weight.
3 to 0.4% by weight of Si, 0.08 to 0.8% by weight of F
e, 0.005 to 0.05% by weight of Be, 0.001 to
After melting an aluminum alloy containing 0.1% by weight of Ti and the balance being Al and inevitable impurities, 5 ° C /
casting while cooling at a cooling rate of at least
While cooling from a temperature of 580 ° C. at a cooling rate of 5 ° C./sec or more, 70% until a finished temperature of 200 ° C. or less is obtained.
A method for producing a heat-resistant aluminum alloy wire, comprising: applying a process of the above-described area reduction, heat-treating at 300 to 500 ° C. for 6 to 250 hours, and then performing cold working at a process rate of 60% or more. 2. After the cold working is performed, 200 to 200
The method for producing a heat-resistant aluminum alloy conductor according to claim 1, wherein heat treatment is performed at 450 ° C for 1 to 100 hours.