JPH0754110A - Production of high heat resistance aluminum alloy conductive wire - Google Patents

Abstract

PURPOSE:To produce a high heat resistant aluminum alloy conductive wire by furthermore specifying the producing process in an Al alloy whose chemical components are specified. CONSTITUTION:An alloy contg., by weight 0.25-0.45% Zr, 0.01-0.05% Ti, 0.03-0.3% Si and 0.08-0.3% Fe, and the balance Al with ordinary impurities is subjected to continuous casting into a wire rod, which is subjected to heat treatment at 250-450 deg.C for 1 to 50hr, is thereafter subjected to cold working of >=65% reduction of area and is moreover subjected to heat treatment at 310-450 deg.C for 1 to 20hr. Thus, the aluminum alloy wire having high heat resistance of >=230 deg.C continuous using maximum temp. and >=310 deg.C short time using maximum temp. and >=58% electric conductivity can be produced.

Description

Detailed Description of the Invention

[0001]

The present invention has a high degree of heat resistance,
The present invention also relates to a method for manufacturing an aluminum alloy wire having excellent conductivity.

[0002]

2. Description of the Related Art With the recent increase in demand for electric power, the need for increasing the capacity of cable power transmission is increasing more and more, and it is desired to develop an aluminum alloy wire having a high allowable temperature for power transmission and high conductivity.

Japanese Patent Application Laid-Open No. 5-126462 relates to a heat-resistant aluminum alloy wire which has a maximum allowable temperature of continuous use of 210 ° C. and a maximum allowable temperature of short-term use of 240 ° C. By the way, when the power demand is concentrated in a certain period of time, the aluminum alloy wire becomes considerably hot, or, for example, when a part of the aluminum alloy wire is cut off due to a lightning strike,
There is a case where another healthy aluminum alloy line laid in parallel with the accident line receives a load corresponding to the transmission capacity of the accident line, and the aluminum alloy line of the healthy line temporarily becomes high temperature. . Considering this point, it cannot be said that the heat resistant aluminum alloy wire having the above-mentioned allowable power transmission temperature has sufficient heat resistance.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a method for producing an aluminum alloy wire which has a high continuous heat resistance of 230 ° C. or higher and a short-time use temperature of 310 ° C. or higher and is highly conductive and excellent in conductivity. The purpose is to provide.

[0005]

[Means for Solving the Problems] The above-mentioned problems are caused by Zr0.2.
5 to 0.45% by weight, Ti 0.01 to 0.05% by weight,
An alloy consisting of 0.03 to 0.3% by weight of Si, 0.08 to 0.3% by weight of Fe, the balance of Al and ordinary impurities was formed into a wire rod by continuous casting, which was 250 to 45%.
After heat treatment at a temperature of 0 ° C. for 1 to 50 hours, cold working with a cross-sectional area reduction rate of 65% or less is added, and further 310 to 4
This is solved by a method for producing a highly heat-resistant aluminum alloy wire for electrical conduction, which is characterized by performing heat treatment at a temperature of 50 ° C. for 1 to 20 hours.

[0006]

Function: Zr 0.25 to 0.45% by weight, Ti 0.01
~ 0.05 wt%, Si0.03-0.3 wt%, Fe
0.08 to 0.3 wt%, the alloy system of a specific composition consisting of the balance Al and ordinary impurities into a wire rod by continuous casting, by heat treatment in a specific temperature range, without impairing the conductivity, Heat resistance is greatly improved. The detailed mechanism as to why the heat resistance is significantly improved without impairing the conductivity is unknown, but Zr
Is heat-treated for 1 to 50 hours at a temperature of 250 to 450 ° C. in a state of supersaturated solid solution of aluminum in an aluminum matrix, Al ₃ Zr particles are finely precipitated in the aluminum matrix, and this is cold worked. After that, by heat treatment at a high temperature of 310 to 450 ° C. for 1 to 20 hours, fine particles of Al ₃ Zr are further precipitated on the work structure, and the work structure in the alloy is stabilized, resulting in heat resistance. It is speculated that the sex has improved significantly.

In the alloy system used in the present invention, Zr
0.25 to 0.45% by weight (hereinafter, simply referred to as%) means that if the electrical conductivity is less than 0.25%, mechanical strength and heat resistance are insufficient when the electrical conductivity is increased to 58% or more. 0.45
When it is more than%, defects are likely to occur in continuous casting, and it becomes difficult to manufacture the wire rod.
The preferable addition amount of Zr is 0.28 to 0.42%, particularly preferably 0.30 to 0.40%.

The reason why Ti is 0.01 to 0.05% is that
If it is less than 0.01%, defects such as rolling cracks occur in continuous casting, making it difficult to manufacture wire rods.
This is because if it is more than 05%, the conductivity will be reduced. Ti
Is preferably 0.01 to 0.04%, particularly preferably 0.02 to 0.03%. When Ti is added by an Al-Ti-B mother alloy, Ti is added to the Al alloy.
Since the B2 phase is precipitated and the crystal grains are made finer, it is preferable in terms of workability and conductivity.

The reason why Si is 0.03 to 0.3% is that S is
If the addition amount of i is less than 0.03%, the effect of promoting the precipitation of Al ₃ Zr is not sufficient, so that the heat resistance and the conductivity decrease,
On the other hand, if it is more than 0.3%, defects will occur in continuous casting, making it difficult to manufacture the wire rod. The preferable addition amount of Si is 0.05 to 0.2%, and particularly preferably 0.08 to 0.15%.

The Fe content of 0.08 to 0.3 is 0.
This is because if it is less than 08%, the work hardening during wire drawing becomes insufficient, and if it is more than 0.3%, the heat resistance and the electrical conductivity decrease. The preferable addition amount of Fe is 0.1 to 0.25.
%, Particularly preferably 0.12 to 0.20%.

In the present invention, ordinary aluminum aluminum ingots for electric use can be used, and it is acceptable to contain impurities normally contained in Al at a normal level, but ingots containing few elements such as V that lower the conductivity. Is preferred. For example, V is preferably set to about 0.003% or less.

In the present invention, a wire rod is obtained by continuous casting of the above aluminum alloy material. As the continuous casting method, the Propelti method, the Hesley method,
Any known method such as the SCR method may be used. For example, a wire rod having a diameter of 8 to 13 mm is obtained by the continuous casting method,
At that time, it is preferable that the melting temperature at the start of casting is 750 to 850 ° C., and the obtained casting bar is rolled at a surface reduction rate of 80% or more, particularly 90% or more while the temperature is 200 ° C. or less.

The wire rod obtained as described above is
Then, heat treatment is performed at a temperature of 250 to 450 ° C. for 5 to 50 hours. By this treatment, Zr was forced to form a solid solution during casting.
Can be precipitated as fine Al ₃ Zr. As a result, the heat-treated wire rod age-hardens and has a good strength, and prepares a good substrate for forming a heat-resistant structure by the heat treatment after the cold working described later. It should be noted that at a heat treatment temperature of less than 250 ° C, the precipitation rate is slow, while at a temperature higher than 450 ° C, the heat resistance decreases due to the coarsening of the precipitated particles. If the treatment time is less than 1 hour, the desired heat resistance cannot be obtained because the precipitation of Zr is not sufficient. On the other hand, if the treatment time is longer than 50 hours, coarsening of the precipitate occurs and the mechanical strength is lowered. is there. Heat treatment is 28
2 to 30 hours at a temperature of 0 to 420 ° C., especially 300 to 40
Preference is given to a temperature of 0 ° C. for 4 to 20 hours.

The heat-treated wire rod is then subjected to cold working so that the cross-sectional area reduction rate becomes 65% or more. If the cross-sectional area reduction rate at this time is less than 65%, not only is work hardening insufficient, but high heat resistance cannot be obtained by subsequent heat treatment. On the other hand, excessive cold working tends to cause problems such as reduction in conductivity and heat resistance. Preferably, cold working is performed so that the cross-sectional area reduction rate is in the range of 70 to 99%, particularly preferably 70 to 98%.

The cold worked alloy wire is then 310-310.
Heat treatment is performed at a high temperature of 450 ° C. for 1 to 20 hours. By this heat treatment, fine particles of Al ₃ Zr are further precipitated on the work structure, the work structure introduced by cold working is stabilized, and high heat resistance is obtained. If the treatment temperature is lower than 310 ° C or less than 1 hour, this effect is not sufficient.
If the treatment is performed at a temperature longer than 50 ° C., coarsening of precipitates and recovery of the processed structure occur, and the mechanical strength decreases. Heat treatment is 32
2 to 10 hours at a temperature of 0 to 400 ° C., especially 330 to 38
Preference is given to a temperature of 0 ° C. for 2 to 10 hours.

(Examples 1 to 10, Comparative Examples 1 to 10) Table 1
The alloys of Examples and Comparative Examples having the composition shown in (the balance is aluminum: aluminum ingot for electric use (JIS H2102-1968)) were continuously cast and rolled by the Propelti method to obtain a wire rod having an outer diameter of 9.5 mm. After subjecting the wire rod to a predetermined heat treatment, the cross-sectional area reduction rate is 84%
Cold working was performed to obtain a strand having an outer diameter of 3.8 mm. The wire thus obtained was finally subjected to a predetermined heat treatment to obtain a target aluminum alloy for electroconductivity. In addition, Ti is Al-
The Ti-B mother alloy (Ti / B molar ratio: 1/1) was added.

The electrical conductivity, tensile strength and heat resistance of the alloy wires obtained in each of the examples and comparative examples were evaluated. Heat resistance is 90% of the value before heating when the tensile strength is 4 hours
The temperature at which the heat resistance was reached was taken as the heat resistance temperature. Table 1 shows the alloy composition, the pouring temperature during continuous casting, and the rolling start and end temperatures in the rolling process for obtaining the wire rod. Further, Table 2 shows the temperature and time of the wire rod (WR) heat treatment, the temperature and time of the wire heat treatment, and the characteristics of the aluminum alloy wire for conduction.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

According to the present invention, the maximum continuous use temperature 23
It is possible to provide an aluminum alloy wire having a high heat resistance of 0 ° C. or higher, a short-time use maximum temperature of 310 ° C. or higher and a conductivity of 58% or more, and good mechanical strength, and at a high yield, the aluminum alloy wire. Can be manufactured.
Therefore, it is possible to sufficiently cope with the increase in the cable transmission capacity accompanying the increase in power demand, and also to sufficiently cope with the temporary overheating of the aluminum alloy wire due to a lightning accident or the like.

Claims (2)

[Claims] 1. Zr 0.25 to 0.45% by weight, Ti
An alloy consisting of 0.01 to 0.05% by weight, Si 0.03 to 0.3% by weight, Fe 0.08 to 0.3% by weight, the balance Al and usual impurities was made into a wire rod by continuous casting, and this was set to 250 After heat treatment at a temperature of ~ 450 ° C for 1 to 50 hours, cold working with a cross-sectional area reduction rate of 65% or more is added, and further heat treatment is performed at a temperature of 310 to 450 ° C for 1 to 20 hours. A method for producing a high heat resistant aluminum alloy wire for electrical conduction. 2. The method for producing a high heat-resistant aluminum alloy wire for electrical conduction according to claim 1, wherein said Ti is added in an Al-Ti-B mother alloy.