JPH0113170B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention significantly improves the heat resistance of a conductive heat-resistant aluminum alloy stranded wire, particularly a stranded wire made of a plurality of wires made of Al-Zr heat-resistant aluminum alloy twisted together in multiple layers, without significantly reducing the strength and conductivity. The present invention relates to a manufacturing method for obtaining. In recent years, with the increase in power transmission capacity, steel-core heat-resistant aluminum alloy stranded wires and all-heat-resistant aluminum alloy stranded wires have been used for overhead power transmission lines, but under special power transmission conditions, in order to further increase power transmission capacity, more heat-resistant wires are used. A stranded wire with excellent properties is desired. For this reason, various heat-resistant aluminum alloys for electrical conductivity have been researched, but the ones that are currently in practical use are Al-Zr heat-resistant aluminum alloys containing Zr as an active ingredient by continuous or semi-continuous casting and rolling methods. These are steel-core heat-resistant aluminum alloy stranded wires or fully heat-resistant aluminum alloy strands, which are steel-core heat-resistant aluminum alloy stranded wires made by forming rough drawn wires by wire drawing or extrusion methods, and twisting a plurality of strands into multiple layers.
Although the heat resistance of this stranded wire improves depending on the Zr content of the Al--Zr heat-resistant aluminum alloy forming the wire, the electrical conductivity decreases. Therefore, if the amount of Zr is increased in order to improve heat resistance, the electrical conductivity will drop significantly, making it unsuitable for practical use. In view of this, as a result of various studies, the present invention has developed a method for producing conductive heat-resistant aluminum alloy stranded wires that can significantly improve heat resistance without significantly reducing the strength and conductivity of the stranded wires.
Zr0.01~0.80%, Fe0.07~0.80%, Si0.03~0.30
%, the balance is Al and normal impurities, and the aluminum alloy rough drawn wire is continuously drawn with an area reduction rate of 60% or more to form a strand, and multiple strands of the strand are reduced in area for each strand. It is characterized by twisting the wire into multiple layers while applying a wire drawing process with a wire drawing ratio of 5% or more in one pass. That is, the present invention produces a rough drawn wire from an Al-Zr heat-resistant aluminum alloy having the above composition by a conventional method such as a continuous casting and rolling method, a semi-continuous casting and rolling method, a spreading method, an extrusion method, etc. When forming a line,
Added surface reduction processing of more than 60% through continuous wire drawing processing,
When twisting the obtained wires into multiple layers, each wire is drawn with an area reduction of 5% or more in one pass, which reduces the strength and conductivity of the twisted wires. It was possible to significantly improve heat resistance without degrading it. The reason why the alloy composition is limited as described above in the present invention is as follows. Zr is added to improve heat resistance, but if it is less than 0.01%, sufficient heat resistance cannot be obtained, and if it exceeds 0.80%, the conductivity decreases significantly, making it unusable for conductive stranded wires. It's for a reason. Fe
is added to improve strength, but if it is less than 0.07%, the effect is small, and if it exceeds 0.80%, the electrical conductivity decreases significantly, and the intermetallic compound FeAl ₃ tends to crystallize during casting, and this coarse Na
This is because FeAl ₃ is harmful to heat resistance. In addition, Si is added to further improve heat resistance and strength, but if it is less than 0.03%, the effect is small;
This is because if the temperature exceeds 100%, the conductivity will drop significantly, and the precipitates will tend to grow coarsely when heated, and the grown coarse precipitates will be harmful to heat resistance. The alloy with such a composition is made into a rough wire by continuous or semi-continuous casting and rolling, rolling, extrusion, etc., and then it is made into a wire by continuous wire drawing with an area reduction of 60% or more. This is to increase the strength of the stranded wire by imparting sufficient strength to the wire, and this is because work hardening is small and sufficient strength cannot be obtained if the area is reduced by less than 60%. Using the strands obtained in this way, when twisting a plurality of strands into a multilayer, the wire was drawn while drawing with a reduction in area of 5% or more for each strand in one pass. This is to recover the loss of heat resistance caused by the temperature of the wire being processed during wire drawing rising to a considerable level due to the accumulation of processing heat. If the area reduction rate is less than 5%, recovery of heat resistance is small. In addition, if the wire drawing process with an area reduction rate of 5% or more is applied in one pass, the same effect can be seen even if the number of passes is increased, but a larger effect cannot be obtained. Passes are limited. In addition, even if wires are heat-treated before and after the continuous wire drawing process, the heat resistance will be the same if the wire is drawn with an area reduction of 5% or more for each strand in one pass when twisted together. improvement was observed. The present invention will be described below with reference to Examples. Melt Al base metal with a purity of 99.8% and add Al-5 to it.
%Zr, Al-5%Fe, Al-20%Si master alloy,
Al-
A Zr--Fe--Si alloy is melted, and an ingot with a cross-sectional area of 2000 ^mm2 is continuously cast using a belt-and-wheel type continuous casting machine. A drawing line was formed. This roughly drawn wire was drawn by more than 60% using a continuous wire drawing machine to form a heat-resistant aluminum alloy conductor. Using 6 to 84 of these conductors, each conductor is passed through a die and drawn on the steel core by 5% or more in one pass.
A steel-core heat-resistant aluminum alloy stranded wire was manufactured by twisting the wire into ~4 layers. For comparison, a heat-resistant aluminum alloy stranded wire with a steel core was manufactured by twisting the same conductor without wire drawing. The manufacturing conditions are also listed in Table 1. The stranded wires thus produced were cut into 1 m lengths, disassembled, straightened, and measured for tensile strength, electrical conductivity, and heat resistance. The results are shown in Table 2 as average values. The tensile strength was measured using an Amsler type tester, and the electrical conductivity was determined by measuring electrical resistance using a Kelvin double bridge. In addition, the heat resistance of each sample
After heating at 260°C for 1000 hours, the tensile strength was measured and expressed as a percentage of the tensile strength before heating.

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[Table] As is clear from Tables 1 and 2, the stranded wires produced by the methods No. 1 to No. 12 of the present invention have a conductivity of 49.99% IACS or higher and a tensile strength of 17.7 Kg/mm. ² or higher, and has a heat resistance of 97.8% or higher, which is the conventional method No.
It can be seen that the conductivity and tensile strength are almost the same and the heat resistance is significantly superior compared to the stranded wires manufactured by No. 21 to No. 32. On the other hand, it can be seen that the stranded wires produced by Comparative Methods No. 13 to No. 18, which differ from the alloy composition specified by the method of the present invention, are inferior in electrical conductivity, tensile strength, or heat resistance. That is, comparative method No. 13 using an alloy with a low Zr content had low heat resistance, and comparative method No. 14 using an alloy with a high Zr content had low conductivity.
Comparative method No. 15 using an alloy with low Fe content has low tensile strength and heat resistance, and comparative method No. 16 using an alloy with high Fe content has low heat resistance and low Si content. Comparative method No. 17 using an alloy has low tensile strength and heat resistance, and comparative method No. 18 using an alloy with a high Si content has low heat resistance. Furthermore, even when using an alloy having the composition specified by the method of the present invention, Comparative Method No. 19, in which the wire drawing rate was less than 60%, and Comparative Method No. 20, in which the wire drawing rate during twisting was less than 5%, both failed. It can be seen that the heat resistance is low. As described above, according to the method of the present invention, the heat resistance of the stranded wire can be significantly improved without substantially lowering the conductivity and strength of the stranded wire, and the method has an industrially significant effect.

Claims (1)

[Claims] 1 Zr0.01~0.80%, Fe0.07~0.80%, Si0.03~
0.3%, the balance Al and normal impurities, the rough drawn aluminum alloy wire is continuously drawn with an area reduction rate of 60% or more to form a wire, and multiple wires are reduced for each wire. A method for manufacturing a heat-resistant aluminum alloy stranded wire for conductive use, characterized by twisting it into multiple layers while applying wire drawing processing with an area ratio of 5% or more in one pass.