JPH0152468B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is a conductive heat-resistant aluminum alloy (hereinafter abbreviated as aluminum alloy) that has excellent heat resistance and conductivity.
This invention relates to a method for manufacturing wire. Traditionally, Al has been used as a heat-resistant aluminum alloy for conductive use.
By adding a small amount of Zr and using a manufacturing method in which Zr is dissolved as a solid solution during the manufacturing process, an aluminum alloy wire with excellent heat resistance and conductivity has been obtained (for example, the patent
842110, 842111). This kind of heat-resistant aluminum alloy for conductive use is known as 60% heat-resistant aluminum alloy (60TAl), and its conductivity is
60% IACS or higher, and heat resistance is characterized by a continuous use temperature of 150℃. In recent years, there has been a strong desire to further improve the heat resistance of conductive heat-resistant aluminum alloys and increase the current carrying capacity of wires of the same size. The present invention was obtained as a result of studies conducted by the present inventors on various alloys and manufacturing methods in order to further improve the above-mentioned heat resistance.
-By applying special processing and heat treatment to Zr-based alloy, the conductivity is 60%, same as 60TAl.
The purpose is to provide a heat-resistant aluminum alloy wire for conductive use that has significantly superior heat resistance and is better than IACS. The present invention contains Zr0.15-0.35%, Fe0.05-0.5%,
When continuously casting and rolling a molten alloy containing 0.03 to 0.25% Si and the balance Al and normal impurities, the casting temperature is 710 to 750℃, and the rolling start temperature is 540 to 580℃. cold working with an area reduction rate of 50% or more, then 300~500
After applying aging treatment at ℃ for 5 to 200 hours, and then cold working with an area reduction rate of 35% or more,
By applying heat treatment at ~300℃ for 0.5 to 20 hours, it has an electrical conductivity of 60% IACS or higher, strength equivalent to hard aluminum wire, and a 10% softening temperature of 300℃ or higher when heated for 1 hour. A method of manufacturing a heat-resistant aluminum alloy wire for conductive use is characterized by the following. Here, the 10% softening temperature means the lowest heating temperature at which the tensile strength decreases by 10% after heating for 1 hour. In the present invention, the Zr content is specified as 0.15 to 0.35% because if it is less than 0.15%, the heat resistance is insufficient, and if it exceeds 0.35%, coarsening of precipitates will occur.
This is because as the amount increases, the heat resistance deteriorates and the cost also increases. In addition, the reason why the amount of Fe is specified as 0.05 to 0.5% is that if it is less than 0.05%, the strength of the drawn wire will be low and it will not be effective in shortening the aging time, and if it exceeds 0.5%, the electrical conductivity and heat resistance will decrease. It is from. Also, the amount of Si was specified as 0.03% to 0.25%, which is 0.03%.
If it is less than 0.25%, not only will the cost of the metal increase increase, but it will not be effective in shortening the aging time, and if it exceeds 0.25%, casting cracks will be noticeable and the heat resistance will also decrease. Next, in the present invention, continuous casting and rolling of the molten alloy can be carried out using a casting machine consisting of an endless belt and a rotary casting wheel, such as the Propelch method or the SCR method, or a Hezlett method.
A combination of a casting machine such as the 3C method and a rolling mill that performs continuous hot rolling is used. According to such a continuous casting and rolling method, the Zr that is forcibly dissolved in the solid solution during casting is brought to the hot rolling process without being precipitated, so that it precipitates uniformly and finely as Al ₃ Zr during the subsequent aging treatment. , can significantly improve heat resistance. For example, ^the solidification conditions during casting are as follows:
By casting within the range of 5.0 to 7.0 ton/hr and using cooling conditions that allow the hot rolling start temperature to be 530°C or higher, an alloy with the desired performance can be obtained. Next, in the present invention, the temperature of the molten metal immediately before the casting machine (casting temperature) is preferably 700°C or higher. The reason for this is that when the Zr concentration is high as in the present invention, when the casting temperature is lower than 700℃, Zr crystallizes in the form of coarse particles in the form of Al ₃ Zr, and the heat resistance becomes poor in the added Zr. This is because not only the effective amount decreases, but also the crystallized coarse particles lower the heat resistance. In addition, the temperature of the ingot immediately before the hot rolling mill (rolling start temperature) is preferably 530°C or higher;
If it is less than that, heat resistance will deteriorate. If the temperature is less than 530°C due to outside temperature, casting conditions, etc., heating is performed before the rolling mill. In the present invention, cold working with an area reduction rate of 50% or more after continuous casting and rolling is performed in combination with subsequent aging treatment and heat treatment to achieve heat resistance of 300°C or more (10% softening temperature). It is for the purpose of obtaining
Furthermore, it is also intended to improve electrical conductivity.
This cold working has a very large effect on improving heat resistance. In cold working, the larger the area reduction rate, the better the heat resistance. For example, by giving an area reduction rate of about 69% and then selecting appropriate aging and heat treatment conditions, the heat resistance will be extremely high at 10% softening temperature of 360°C, but if the area reduction rate is less than 50%. With cold working, a 10% softening temperature of 300°C or higher cannot be achieved no matter what kind of aging treatment or heat treatment is performed afterwards. At the same time, the cold working with an area reduction of 50% or more also produces good results on the electrical conductivity of the wire, and the higher the area reduction, the better the electrical conductivity. Even if the area reduction rate is less than 50%, a slight improvement in conductivity can be expected, but no effective improvement can be expected. Since heat resistance and electrical conductivity must be satisfied at the same time, the present invention specifies the area reduction rate of the cold working as 50% or more. Next, in the present invention, the aging treatment conditions after the cold working are specified as 300° to 500°C for 5 to 200 hours, because this heat treatment allows Zr to precipitate uniformly and finely as Al ₃ Zr, and increases the electrical conductivity. This is to improve heat resistance through dispersion strengthening by finely precipitated Al ₃ Zr. At temperatures below 300°C, the heat treatment time becomes longer and productivity is hindered.
This is because if it exceeds this, the precipitates will become coarser and the heat resistance will deteriorate. Temperature and time in aging treatment are correlated as optimal conditions; the higher the temperature, the shorter the time. Aging conditions of 80 hours are optimal. In addition, cold working with an area reduction rate of 35% or more is performed after aging treatment because cold working with an area reduction rate of 35% or more is required in order to have the same strength as hard aluminum wire. This is because if it is less than that, the desired strength cannot be obtained. The reason why we specified the subsequent heat treatment at 220 to 300℃ for 0.5 to 20 hours is because this makes it possible to significantly improve the heat resistance characteristics, and this heat treatment allows us to change the aging treatment temperature and time range. This makes it possible to expand the electrical conductivity and further improve the electrical conductivity, which is very advantageous in industrial production. If the temperature is less than 220°C, the heat treatment time becomes longer and productivity is hindered, and if it exceeds 300°C, no improvement in heat resistance can be expected. Temperature and time in heat treatment are correlated as optimal conditions, and the higher the temperature, the shorter the time.
Heat treatment conditions of ~5 hours are optimal. Further, the aluminum ingot used as a raw material in the present invention may be an ordinary electric aluminum ingot, but impurities contained in the aluminum ingot should be kept as small as possible in order to prevent deterioration of heat resistance. This is desirable. By configuring the present invention as described above,
Heat resistance can be increased to 10% softening temperature of 300℃ or higher by heating for 1 hour. This has a continuous use temperature of 210℃ and a short time use temperature of 240℃.
It corresponds to ℃. Here, the continuous use temperature is the highest temperature at which the tensile strength does not decrease to less than 90% of the initial value even if used at that temperature for 36 years.
Further, the short-time use temperature is the highest temperature at which the tensile strength does not decrease to less than 90% of the initial value even if used at that temperature for 400 hours. Heat resistance and electrical conductivity of 60 or more
%IACS or higher, which is equivalent to a hard aluminum wire, and the heat treatment can be performed over a wide temperature and time range, making it stable and easy to manufacture. The present invention will be explained below with reference to Examples. Example 1: Electrical aluminum ingot (JIS
H2110) was added with the amounts of Zr, Fe, and Si shown in Table 1, degassed, and then continuously cast using a rotating wheel type casting machine with a mold cross-sectional area of 3200 ^mm2 to obtain a cast bar. Then, hot rolling and warm rolling were performed to obtain a rough drawn wire of 11.7 mmφ. In this case, the temperature of the molten metal just before the casting machine (casting temperature) is 720 to 750°C, and the temperature of the cast rod just before the rolling machine (rolling start temperature) is 540 to 750°C.
The temperature was set to 590℃. Next, the rough drawing line is cold worked (referred to as processing),
Heat treatment for aging (referred to as treatment), further cold working (referred to as processing), and finally heat treatment (referred to as treatment) were performed under the conditions shown in Table 1. Tensile strength and conductivity of the obtained aluminum alloy wire, 10
The % softening temperatures are shown in Table 1.

【table】

[Table] From Table 1, Nos. 1 to 12 according to the present invention have a tensile strength equal to or higher than the hard aluminum wire (No. 13), a conductivity of 60% IACS or higher, and a temperature of 300℃ or higher. Ten%
It can be seen that it has a softening temperature. On the other hand, Comparative Examples Nos. 14 to 20 did not satisfy either the electrical conductivity or the 10% softening temperature, and those containing a large amount of Si suffered from casting cracks. Example 2: An aluminum alloy having the same composition as No. 8 shown in Table 1 was continuously cast and rolled in the same manner as in Example 1 to obtain a rough wire of 11.7 mmφ. However, the casting temperature was 710 to 740°C, and the rolling start temperature was 540 to 580°C. Next, the rough drawn wires were subjected to the processing and treatments shown in Example 1 under the conditions shown in Tables 2 to 4, respectively. The 10% softening temperature or tensile strength of the obtained aluminum alloy wires are shown in Tables 2 to 4.

【table】

【table】

[Table] Regarding the influence of the area reduction rate of processing shown in Table 2, the present invention Nos. 21 to 26 with a reduction rate of 50% or more can obtain a 10% softening temperature of 300℃ or higher, but the comparative examples with a reduction rate of less than 50% can achieve a softening temperature of 300℃ or higher. The following is true. Regarding the influence of the area reduction rate during processing shown in Table 3, the tensile strength of Invention Nos. 30 to 35 with a reduction rate of 35% or more is higher than that of the comparative example with a reduction rate of less than 35%. In addition, regarding the influence of the presence or absence of treatment shown in Table 4, Invention Nos. 39 to 45 with treatment had a 10% higher effect than comparative examples without treatment.
The softening temperature has been obtained. As described above, the aluminum alloy wire produced by the manufacturing method of the present invention contains Zr0.15-0.35%, Fe0.05-0.5%,
Containing 0.03 to 0.25% Si, the balance consists of Al and normal impurities, and the molten alloy is continuously cast and rolled.
The Zr that was forced into solid solution during casting is dissolved without precipitation, and after continuous casting and rolling, it is cold worked with an area reduction rate of 50% or more, and then aged at 300° to 500°C for 5 to 200 hours. Therefore, the combination of the cold working and _aging treatment described above improves electrical conductivity and heat resistance at the same time. After treatment, we perform cold working with an area reduction rate of 35% or more.
After the desired strength is obtained, further heating is performed at 220° to 300°C.
Since heat treatment is performed for 0.5 to 20 hours, the heat resistance properties can be greatly improved, and the electrical conductivity can also be improved. It has the advantage of having excellent heat resistance, with a 10% softening temperature of 300°C or higher when heated for hours. Further, since the heat treatment has a wide range of temperature and time, there is an advantage that stable heat resistance can be obtained easily.

Claims (1)

[Claims] 1 Zr0.15~0.35%, Fe0.05~0.5%, Si0.03~
When continuous casting and rolling is performed from a molten alloy containing 0.25% Al and the balance Al and normal impurities, the casting temperature is set to 710 to 750℃, and the rolling start temperature is
Conducted at 540-580℃, and then reduced area by 50
% or more cold working, then 500°C at 300~500°C.
After ~200 hours of aging treatment, the area reduction rate is 35.
% or more, then further heated to 220~300℃
By applying heat treatment for 0.5 to 20 hours, it has an electrical conductivity of 60% IACS or higher, strength equivalent to hard aluminum wire, and a 10% softening temperature of 300℃ or higher after 1 hour of heating. A method of manufacturing a conductive heat-resistant aluminum alloy wire.