JPH03180439A - Heat-resistant conductive aluminum alloy - Google Patents

Abstract

PURPOSE:To improve the heat resistance in the aluminum alloy without nearly deteriorating its electric conductivity by incorporating specified amounts of Ni, Fe and Be into Al. CONSTITUTION:The compsn. of an alloy is formed of, by weight, >1.5 to 5.7% Ni, 0.1 to 2.0% Fe, 0.03 to 1.0% Be and the balance Al with ordinary impurities. The alloy having the above compsn. is used for an overhead power transmission wire or the like by executing casting by continuous or semi-continuous casting, subjecting the obtd. ingot to hot rolling into a rough drawing wire, subjecting the wire to cold wire drawing and thereafter executing heat treatment or the like. In this way, its transmission capacity can be increased.

Description

[Detailed description of the invention] The present invention relates to a heat-resistant aluminum alloy for conductive use,
In particular, it has a strength equivalent to that of conventional heat-resistant aluminum alloys for conductivity (At-Zi alloys), and has significantly improved heat resistance without significantly reducing conductivity.

Conventionally, copper-core aluminum stranded wires with conductors made of electrical AI have been used for overhead power transmission lines, and for transmission lines that require particularly high heat resistance, heat-resistant machines made of solid solution Zr of AI-Zr alloy have been used. A core-aligned heat-resistant aluminum alloy stranded wire using a conductor made of a solid solution type heat-resistant aluminum alloy is used. In recent years, there has been a demand for improved heat resistance due to the increase in power demand, and in response to this demand, heat-resistant aluminum alloys for conductive use with an increased amount of solid solute Zr and the heat resistance mechanism of precipitated Zt replaced the heat resistant mechanism of solid solute Zr. A heat-resistant aluminum alloy for electrical conduction using this mechanism has been developed.

However, an increase in the amount of solid solution Zr leads to a decrease in electrical conductivity, and in order to utilize the heat resistance mechanism of precipitation 2,
Since it requires heat treatment at a temperature of 450° C. for a long time, it has the disadvantage of high cost. Furthermore, the temperature and humidity that can be used with these alloys when energized is about 300° C., and further improvement in heat resistance is strongly desired.

In view of this, the present invention has been developed as a result of various researches, and has been developed as a heat-resistant conductive aluminum alloy that has strength equivalent to that of conventional conductive heat-resistant aluminum alloys (Aj-Zt alloys) and has significantly improved heat resistance without significantly reducing conductivity. This is an aluminum alloy developed.

That is, the alloy of the present invention has Ni exceeding 1.5w1% and 5.1v1
% or less, FeO, 1-2. Ov1%, BeO,0
3-1. It is characterized by containing Ov1%, with the remainder consisting of AI and normal impurities.

However, the reason why the alloy composition is limited as described above in the present invention is as follows.

Ni content exceeds 1.5v1% to 57v1% (hereinafter W
(% is simply abbreviated as %) The reason for limiting it to the following is to improve strength and heat resistance as a eutectic structure in which NiAJ is dispersed in the AI matrix by adding Ni.
If the content is less than 1.5%, the strength and heat resistance will be insufficient, and if it exceeds 5.7%, primary crystals N1AJ, N1AJ, etc. will be present in the metal structure.
This is because the dendrite phase of the steel crystallizes out, which not only impairs workability but also reduces ductility.

The reason for limiting the Fe content to 0.1 to 2.0% is that even if only Ni is added, the strength and heat resistance will improve due to the dispersion of N1AJ3, but since the AI matrix is pure AI, the strength will be insufficient. In order to achieve high strength, it is necessary to increase the Ni content, so Fe is added to strengthen the AI matrix so that the same strength can be obtained even if the Ni content is decreased. This is because when the Fe content is less than 0.1%, the effect is insufficient, and when it exceeds 2.0%, the conductivity decreases significantly.

In addition, the Be content was limited to 0.03 to 1.0%.
The corrosion resistance was improved by adding 0.
This is because if it is less than 0.03%, the effect is small, and if it exceeds 1.0%, the conductivity will decrease significantly.

The other impurities are contained in ordinary electrical AI metals, and impurities of this level do not impair the properties of the alloy in any way.

The alloy of the present invention has the above-mentioned composition, but the preferred manufacturing process is to cast it by conventional continuous or semi-continuous casting, hot-roll the resulting ingot into a rough drawn wire, and then cold-stretch it. After wire processing, 0.
It is produced by heat treatment for 5 to 10 hours.

The reason why the wire is heat-treated at a temperature of 200-500°C for 0.5-10 hours after cold wire drawing is to adjust the strength and conductivity as well as impart heat resistance, and the treatment temperature is 200°C. Even if the treatment time is less than 0.5 hours, the conductivity will not be recovered, and especially if the treatment time is short, the heat resistance will not be improved. Also, even if the processing temperature exceeds 500℃, the processing time is 1
Even after 0 hours, the strength decreases significantly.

The present invention will be described in detail below with reference to Examples.

Electrical AI ingot with 99.8% purity and A16%Fe 5A
Using each mother alloy of l-10%Ni and AJ-5%Be, alloys having the compositions shown in Table 1 were blended and melted. This was cast using a belt-and-wheel type continuous casting machine, and the obtained ingot was subsequently hot-rolled into a rough drawn wire having a diameter of 9.5+ om.

This roughly drawn wire was cold-drawn into a wire with a diameter of 4.5 mm, which was then heat-treated at various temperatures to produce conductors.

The electrical conductivity, tensile strength, heat resistance, and corrosion resistance of this conductor were measured. These results are also listed in Table 1 in comparison with a conventional conductive heat-resistant aluminum alloy (AI-Zr alloy).

The conductivity was calculated by measuring resistance using a Kelvin double bridge, and the strength was measured using an Amsler type tester.

Heat resistance was expressed as the temperature at which the strength decreased by 10% after 1 hour of heat treatment. Corrosion resistance was measured by performing a 5% NIC1 spray test for 100 days and expressing the weight loss rate.

As is clear from Table 1, all conductors made of magnets 1 to 4 made of the alloy of the present invention have a conductivity of 58.2% IAC8 or higher, a tensile strength of 17.2 kg/- or higher, and a 10% softening temperature of 50 (1°C). The above shows a weight reduction rate of 0.72% or less, and Al-Z
It can be seen that the heat resistance is significantly superior to the conventional alloy Na 11 using an r-based alloy, and other properties are almost unchanged.

On the other hand, as can be seen from the comparative alloys Na5 to 10, those outside the composition range of the present alloy are inferior in electrical conductivity, tensile strength, heat resistance, and corrosion resistance.

That is, the heat resistance was not improved in the comparative alloy Na5 with a low Ni content, and the electrical conductivity decreased in the comparative alloy Nl16 with a high Ni content, the comparative alloy Na8 with a high Fe content, and the comparative alloy Na1O with a high Be content. The strength of the comparative alloy Na7, which has a low Fe content, is not improved, and the corrosion resistance of the comparative alloy M9, which has a low Be content, is not improved.

As described above, the present invention has strength equivalent to that of conventional heat-resistant aluminum alloys for conductivity (Aj-Zr alloys), and can significantly improve heat resistance without substantially reducing conductivity. It is used in conductors such as core heat-resistant aluminum alloy stranded wires, and has a remarkable effect of increasing power transmission capacity.

Claims (1)

[Claims] (1) Ni exceeding 1.5wt% and 5.7wt% or less, F
e0.1-2.0wt%, Be0.03-1.0wt%
A heat-resistant aluminum alloy for conductive use, with the remainder being Al and normal impurities.