JPS5983752A - Preparation of heat resistant aluminum alloy conductor - Google Patents

Abstract

PURPOSE:To enhance the heat resistance of an alloy, by applying casting, mechanical and heat processings to an alloy containing Zr, Fe, Si and Al in predetermined ratios under a predetermined condition. CONSTITUTION:An alloy comprising, on a wt. basis, 0.1-0.5% Zr, 0.05-0.5% Fe, 0.05-0.5% Si and the remainder Fe is prepared by a melting method. Subsequently, this molten alloy is semi-continuously or continuously cast at 740 deg.C or more at a speed of 10mm./sec or more to form a cast ingot which is, in turn, subjected to hot rolling while the rolled alloy is converted to a roughly drawn wire while surface reducing processing of 70% or more is applied. In this case, heat treatment is applied to the roughly drawn wire or on the way of wire drawing processing at 300-500 deg.C for 5-1,000hr and surface reducing processing of 10-75% is further applied to obtain a predetermined wire diameter. By this method, an electric conductor excellent in heat resistance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a heat-resistant aluminum alloy conductor, and in particular, to obtain a conductor that has strength and conductivity equivalent to that of a heat-resistant aluminum alloy conductor, and exhibits far superior heat resistance. belongs to.

Traditionally, overhead power transmission lines use copper-core aluminum alloy stranded wire (AC8R), which has A4 conductors twisted around a copper core.
Under special power transmission conditions, a heat-resistant aluminum alloy stranded wire with a heat-resistant At alloy conductor twisted around a copper core is used.

The heat-resistant At alloy conductor contains Zri as an active ingredient) L-7
, r alloy is used, but this alloy is a solid solution 7. The heat resistance is improved by r, and although the heat resistance increases according to the amount of zr added, on the other hand, the electrical conductivity decreases. Therefore, in the heat-resistant At alloy conductors that have been put into practical use, the amount of Zr added is determined from the viewpoint of electrical conductivity, and there is a limit to the heat resistance.

With the recent increase in power demand, conductors with even better conductivity, strength, and heat resistance are required.
A heat-resistant AA alloy conductor has been developed that has completely improved heat resistance and strength by adding PE, Si, etc. to the r alloy. This conductor is made by adding intermediate annealing and cold drawing to a rough drawn wire formed by a continuous or semi-continuous casting and rolling method, a rolling method, an extrusion method, etc. 1
-Electrical conductivity 57-61% lAC3, tensile strength 1
7.0~17.5 K9/mA, heat resistance 240 to 27
Only about 5° C. could be obtained, and further improvement in heat resistance was desired.

In view of this, as a result of various studies, the present invention found that conventional manufacturing methods inevitably cause Zr precipitation, which causes a decrease in heat resistance.As a result of further research,
It has the same strength as the conventional one and has a conductivity of 58% IACS.
We have developed a method for manufacturing a heat-resistant At alloy conductor that exhibits far superior heat resistance without lowering the heat resistance.
O, 1 to Q, 5 wt% (hereinafter wt is simply abbreviated as ke),
F e O, 05-0.5%, Si 0.05-0
．． 5φ, 7A part An aluminum alloy consisting of At and normal impurities was heated for 10ml sec at a temperature of 740°C or higher.
Continuous or semi-continuous casting is performed at the above speed, and the resulting ingot is continuously hot-rolled without reheating to reduce the area by 70% or more to make a rough drawn wire, which is then rolled to a predetermined wire diameter. For wire drawing processing, 300~
It is characterized in that it is heat treated at a temperature of 500°C for 5 to 10,000 hours, and then subjected to an area reduction process of 10 to 75% before final wire drawing to form a predetermined wire.

That is, the present invention limits the composition of the heat-resistant At alloy, limits the continuous or semi-continuous casting conditions (casting temperature, casting speed), increases the amount of solid solution Zr, and then increases the amount of Zr in solid solution by subsequent hot rolling and heat treatment. Ats'7. The heat resistance is improved by forming all the fine precipitates of r, without reducing the conductivity at all, and the predetermined strength is imparted by work hardening without reducing the heat resistance by the final wire drawing process.

However, in the present invention, the composition of the heat-resistant At alloy is limited as described above because Zr improves heat resistance, but if it is less than 0.1%, the effect cannot be expected, and if it exceeds 0.5%, the electrical conductivity decreases. In addition, although Fe and 5ili further improve heat resistance and strength, the effect cannot be expected when Fe is less than 0.5%, and when Fe exceeds 0.5%, the conductivity decreases significantly, and Si exceeds 0.5%, A t s
This is because the heat treatment to precipitate Zr significantly reduces the strength.

In continuous or semi-continuous casting of the heat-resistant AA gold alloy with the above composition, -゛ The casting temperature is limited to 740°C or higher and the casting speed is 10 mm/see or higher in order to sufficiently dissolve Zr as a solid solution, and the casting temperature is lower than 740°C. However, this is because Zr precipitates even when the casting speed is less than 10 mm/see, and the heat resistance deteriorates no matter how the subsequent processing conditions are adjusted. In addition, the obtained ingot was subjected to continuous hot rolling to reduce the area by 70% or more without reheating, which prevents Zr precipitation due to reheating and improves strength through work hardening. This is because if the area is reduced by less than 70%, sufficient heat resistance and strength cannot be obtained no matter how the subsequent processing conditions are adjusted.

In the middle of the rough wire or wire drawing process obtained in this way, 30
The reason why the heat treatment is carried out at a temperature of 0 to 500°C for 5 to 1000 hours is to completely form the fine precipitates of A and Zr as described above and improve the heat resistance without reducing the electrical conductivity. If the temperature is less than 3oooC, the improvement in conductivity will be small; if it exceeds 5001:'e, it will reach 1 in time, and the strength and heat resistance will decrease; if the heating time is less than 5 hours, the improvement in conductivity will be small; if the heating time is less than 5 hours, the improvement in conductivity will be small; if the heating time is less than 5 hours, the improvement in conductivity will be small; It becomes over-aged and heat resistance decreases. In addition, the reason why this is subjected to the final wire drawing process is to reduce the area by 10 to 75 inches to reach the predetermined wire diameter in order to increase the strength through work hardening. This is because strength cannot be obtained, and when the area is reduced beyond 70 inches, the heat resistance decreases even though the strength improves.

Next, the present invention will be explained with reference to examples.

Conductive At base metal with a purity of 99.6% and At-5% Zr, A
Using each master alloy of L-6%Fe and AA-20%Si, alloys having the compositions shown in Table 1 were melted. This molten metal is cast into a belt-and-wheel type continuous casting machine with a cross-sectional area of 200++cm.
Continuously cast into an ingot of j, without reheating the ingot, and then hot-roll it into a rough drawing wire in a continuous rolling mill, and then cold-stretch the rough drawing wire or the rough drawing wire. A heat-resistant AL conductor was manufactured by performing heat treatment during wire processing and then wire drawing.

The manufacturing conditions are shown in Table 2.

The tensile strength, electrical conductivity, and heat resistance of the heat-resistant At conductor thus produced were measured. The results are shown in Table 3.

The tensile strength was measured using an Amsler type tensile tester, and the electrical conductivity was calculated by measuring electrical resistance using a Kelvin double bridge. Heat resistance is measured by measuring the tensile strength after heating at each temperature for 1 hour, and is 10% higher than the tensile strength before heat treatment.
Expressed by decreasing temperature.

Table 3 As is clear from Tables 1 to 3, the heat-resistant At alloy conductors manufactured by the method of the present invention all have a conductivity of 58.4 tile.
AC3 or higher, tensile strength 17.4Kg/- or higher, heat resistance 3
It exhibits all the characteristics above 72℃, and has almost the same conductivity and tensile strength as heat-resistant At conductors (Ii 23 to N124) manufactured by conventional methods, and exhibits far superior heat resistance. I understand.

On the other hand, in the comparative method using an alloy that deviates from the composition specified by the method of the present invention, even if casting, hot rolling, heat treatment, and wire drawing are performed under the conditions specified by the method of the present invention, the conductivity and tensile strength It can be seen that either strength or heat resistance is inferior. In other words, the comparative method with a low Zr content: for frame 8, the heat resistance was 7.
．． Comparative method Nα9 and method N (L 12
The tensile strength and heat resistance of Comparative Method No. 13, which had a high Si content, decreased.

In addition, even with the alloy composition specified by the method of the present invention, in a comparative method in which any of the casting conditions, hot rolling conditions, heating conditions, and wire drawing conditions are different, any of the electrical conductivity, tensile strength, and heat resistance will be affected. I can see that it has improved and is strong. That is, method 14 with a low casting temperature, method Nα15 with a slow casting speed, method 20 with a long heat treatment time, and method N022 with a high wire drawing processing rate did not improve heat resistance, and the processing rate in hot rolling increased. Small method number 16, method with high heat treatment temperature N118
However, the tensile strength and heat resistance were not improved in Method 1 @ 17, which had a low heat treatment temperature, and Method t (α1), which had a short heat treatment time.
9, the conductivity is not improved and method N has a small wire drawing rate.
Tensile strength is not improved with α21, and heat resistance is not improved with method Nα22, which has a high wire drawing rate.

As described above, according to the present invention, by specifying the alloy composition, casting conditions and other manufacturing conditions, the conventional heat-resistant At
This has the remarkable effect of producing a heat-resistant At alloy conductor that has conductivity and tensile strength equivalent to those of the alloy conductor and exhibits far superior heat resistance.

Claims (1)

[Claims] ZrO, 1~0.5wt%, FeO, 05~0.5w
An aluminum alloy consisting of t%, sio, 05 to 0.5 wt%, the balance At and normal impurities is continuously or semi-continuously cast at a temperature of 740°C or higher at a rate of 10 wn/8ec or higher, and the resulting cast In order to reduce the area of 70 inches or more by continuously hot rolling the lump without reheating it to make a rough wire, and then draw it to a predetermined wire diameter, it is necessary to use a rough wire or an intermediate wire drawing process. 5-1 at a temperature of 300-500℃
1. A method for producing a heat-resistant aluminum alloy conductor, which comprises heat-treating the conductor for 1,000 hours and reducing the area by 10 to 75% before final wire drawing to obtain a predetermined wire diameter.