JPH0125383B2 - - Google Patents

Description

[Detailed description of the invention]

(Technical Field) The present invention relates to a method for manufacturing a heat-resistant aluminum alloy for electrical conduction that has excellent heat resistance and electrical conductivity. (Background technology) In recent years, heat-resistant steel core aluminum alloy stranded wires (hereinafter referred to as
(referred to as TACSR) is used. 60 for this
% conductivity heat-resistant aluminum alloy (hereinafter referred to as 60TAl)
has been adopted as 60TACSR in Japan's main power transmission lines. Conventionally, the heat-resistant aluminum alloy for conductive use is known as the above-mentioned 60TAl, which is made by adding a small amount of Zr of about 0.04% to Al and performing a treatment to dissolve Zr as a solid solution during the manufacturing process to impart heat resistance. It has a continuous operating temperature of 150°C, and in recent years there has been a desire to further improve heat resistance and increase power transmission capacity. However, if you just want to increase heat resistance, Zr
It is conceivable to increase the amount of Zr added, but in this case, the electrical conductivity decreases as the amount of Zr added increases, so there has been a desire to develop a conductor with high both electrical conductivity and heat resistance. (Disclosure of the Invention) The present invention was obtained as a result of studies conducted by the present inventors on various alloys and manufacturing methods in order to solve the above-mentioned problems. The present invention aims to provide a method for manufacturing a conductive heat-resistant aluminum alloy having high conductivity and high heat resistance by combining a manufacturing method and a specific heat treatment. The present invention has Zr0.15~0.35%, Fe0.08~0.5%,
After casting an aluminum alloy containing 0.04 to 0.15% Si and the balance Al and normal impurities from a temperature of 700°C or higher at a cooling rate of 5°C/second or higher and subsequently hot working. , a method for producing a heat-resistant aluminum alloy for conductive use, characterized by heating at a temperature increase rate of 100° C./hour or less, and performing an aging treatment in a temperature range of 300 to 480° C. for 10 to 300 hours. In the present invention, the amount of Zr in the aluminum alloy is 0.15~
The reason for specifying 0.35% is that if it is less than 0.15%, the heat resistance and strength will be low, and if it exceeds 0.35%, the heat resistance will be saturated, and at the same time, it will not form a solid solution during casting unless the temperature of the molten metal is raised, and Al ₃ This is because Zr crystallizes as coarse particles, which in turn reduces heat resistance. In addition, Fe is a solid solution part in aluminum alloy and Al ₃ Fe,
The finely precipitated portion as Al ₆ Fe improves strength and heat resistance, and the reason why the Fe amount is specified as 0.08 to 0.5% is that if it is less than 0.08%, heat resistance and strength will be low, and if 0.5% This is because if it exceeds 100%, the heat resistance will decrease and the electrical conductivity will also decrease. Also, Si is a crystallized product of Al-Fe-Si system, Al-Zr-Si system,
It is finely dispersed as a precipitate and improves strength, heat resistance, and conductivity.The reason why the amount of Si is specified as 0.04 to 0.15% is that if it is less than 0.04%, the strength will be low, but it will have high conductivity and high heat resistance. This is because the aging time required for obtaining
This is because if it exceeds 0.15%, heat resistance will deteriorate and casting cracks will be significant. Next, in the present invention, continuous casting and subsequent hot processing are carried out by, for example, the Propelch method, the SCR method, the Sesim method, etc., which use a continuous casting machine consisting of a rotating mold and an endless belt, and a subsequent hot rolling mill.
Continuous casting and rolling methods such as the Hesley method and the Hunter method, which use a continuous casting machine such as the twin roll method and the caterpillar method followed by a hot rolling mill, can be used, but the casting conditions are as follows: There is no particular restriction as long as it can be cast at a cooling rate of seconds or more. In the present invention, the casting temperature is specified as 700°C or higher because if it is lower than 700°C, coarse particles will form in the molten metal stage.
This is because Al ₃ Zr particles crystallize, resulting in a significant decrease in heat resistance. In addition, the cooling rate was specified as 5°C/second or more because the crystallized substances of Al ₃ Fe and Al ₆ Fe were finely dispersed during casting.
This is to increase the strength and heat resistance and to prevent the precipitation of Zr, which was forcibly dissolved during casting, and if the speed is less than 5° C./sec, the heat resistance will decrease. Further, the hot working in the present invention may be normal hot working, but it is preferable to hot work the above-mentioned cast material from a starting temperature of 480°C or higher in terms of heat resistance. If the temperature is less than 1, it may be heated using a gas burner, induction heating, infrared heating, or the like. After being hot-worked in this way, the material is preferably wound at a temperature below 150°C.
For example, according to recent winding machines, in the case of wire rods, 2 to 3
When a large coil of 1,000 tons is wound and wound at a high temperature of about 300℃, the center of the coil remains at a high temperature due to the temperature of the wire itself, resulting in large variations in characteristics inside and outside the coil, which reduces the yield of the product. becomes extremely bad. In the present invention, after hot working or, if necessary, further cold working such as cold wire drawing, heating is performed at a temperature increase rate of 100°C/hour or less,
It is aged at a temperature range of 480℃ for 10 to 300 hours. In addition, when applying the above-mentioned cold working, it is especially important to keep the coiling temperature of the hot worked material below 150℃, to eliminate variations in properties and to improve cold workability. is also necessary. On the other hand, when the coil is wound at high temperatures, the lubricant during hot working changes its quality at the center of the coil and adheres strongly, causing seizure and flaking during cold working, and in severe cases, even breakage. . In the aging treatment of the present invention, it is important to control the aging temperature and aging time as well as the rate of temperature increase to reach the aging temperature.By controlling this to 100℃/hour or less, the strength and heat resistance of the material after that It is possible to improve both properties and conductivity. Such improvements in properties can only be obtained by combining the above-mentioned casting and hot working conditions. The mechanism by which strength, heat resistance, and conductivity are improved by controlling the temperature increase rate to 100° C./hour or less is not clear, but it is thought to be as follows. That is, by this, the hot-worked structure and the cold-worked structure are subjected to the primary precipitation treatment of fine AlFeSi, Al ₃ Fe, Al ₃ Zr, Zr ₅ Si _3, etc., and then subjected to aging treatment at 300 to 480°C. In this process, a fine secondary precipitation treatment of a large amount of Al ₃ Zr, Al ₃ Fe, Zr ₅ Si ₃ , etc. is applied to the structure with an increased number of precipitation sites, resulting in a material with excellent strength, heat resistance, and electrical conductivity. is obtained. The aging treatment conditions are 10 to 300℃ in the temperature range of 300 to 480℃.
300 hours is specified because if it is less than 300 hours, the conductivity, heat resistance, and strength will not improve, and if it exceeds 480℃, the heat resistance and strength will deteriorate, and if it is less than 10 hours, the conductivity,
This is because neither the heat resistance nor the strength is improved, and the effect not only becomes saturated after 300 hours, but also, especially in the case of aging at high temperatures, overaging occurs, leading to deterioration of the strength and heat resistance. Regarding the aging time, generally speaking, the higher the aging temperature, the shorter the time, which is a better relationship, but it is possible to adjust the temperature and time in order to obtain the target characteristics. Next, in the present invention, the material subjected to the above-mentioned aging treatment is usually further subjected to cold working such as cold wire drawing to be finished into a desired final size. The aluminum alloy according to the present invention manufactured by the above method has an electrical conductivity of 60% IACS or more, a strength equivalent to that of hard aluminum wire, and can have heat resistance of 300° C. or more. Here, heat resistance refers to the lowest heating temperature at which the tensile strength decreases by 10% after heating for 1 hour. (Example) After melting an aluminum alloy with the composition shown in Table 1 and degassing it, it was transferred to a continuous casting machine consisting of a copper alloy rotary mold with a mold cross-sectional area of 2800 mm ² and a steel belt at a temperature of 720 to 740. Feeding at ℃, cooling rate 8-12
Casting was performed while controlling the cooling conditions at ℃/second. After the temperature of this cast material reached 520 to 550°C, hot rolling was continued, and after hot rolling to a rough wire of 9.5 mm, it was coiled at a temperature of 70 to 90°C.

[Table] These rough wires were subjected to cold working and aging treatment before and after aging under the conditions shown in Table 2, and the tensile strength, electrical conductivity, and heat resistance were investigated. The results are shown in Table 3.

【table】

【table】

【table】

[Table] From Table 3, samples No. 1, 2, 5 ~ according to the present invention
12, 14, 16, 18, 20, and 21 have superior strength, electrical conductivity, and heat resistance compared to other comparative examples with the same composition and aging conditions, and have approximately the same strength as hard aluminum wire, 60% High conductivity over IACS and 300
It can be seen that it has heat resistance of ℃ or higher. In particular, the temperature increase rate during aging treatment has a large influence. (Effects of the Invention) The method for manufacturing a conductive heat-resistant aluminum alloy of the present invention configured as described above has the following effects. Aluminum alloy contains Zr0.15~0.35%, Fe0.08~0.5%,
Since it contains 0.04 to 0.15% Si, Zr improves heat resistance and strength, and Fe and Si improve strength and heat resistance without reducing conductivity.
Continuous casting is performed at a cooling rate of 5°C/sec or higher from a casting temperature of 10°C or higher, followed by hot working, so the Zr that was forced into solid solution during casting is dissolved without precipitation, and then during aging treatment. Because it is heated at a temperature increase rate of 100℃/hour or less, the primary precipitation of fine compound particles as described above occurs, and further, an aging treatment is performed at a temperature range of 300 to 480℃ for 10 to 300 hours. As mentioned above, secondary precipitation of fine compound particles occurs, resulting in an aluminum alloy with excellent strength, heat resistance, and electrical conductivity, with electrical conductivity of 60% IACS or higher and strength equivalent to hard aluminum wire. It can also have heat resistance of 300°C or higher. In particular, the ability to obtain a wire with high conductivity can significantly reduce the resistance loss of the wire, which has a great effect.

Claims (1)

[Claims] 1 Zr0.15~0.35%, Fe0.08~0.5%, Si0.04~
An aluminum alloy containing 0.15% Al with the balance being Al and normal impurities is heated at a casting temperature of 700°C or higher for 5
Continuous casting at a cooling rate of ℃/second or more, followed by hot working, followed by heating at a temperature increase rate of 100℃/hour or less, and aging treatment for 10 to 300 hours in a temperature range of 300 to 480℃. A method for manufacturing a heat-resistant aluminum alloy for conductive use, characterized by subjecting it to. 2. The method for producing a conductive heat-resistant aluminum alloy according to claim 1, wherein the hot working is performed at a processing start temperature of 480°C or higher and a coiling temperature of 150°C or lower.