JPS5827949A - Electrically conductive heat-resistant aluminum alloy wire - Google Patents

Abstract

PURPOSE:To obtain the titled Al alloy wire having >=60% IACS electric conductivity and equal to a hard Al wire in strength by continuously casting and rolling a molten Al-Zr alloy having a specified composition and by carrying out cold rolling at a prescribed draft, aging and cold rolling at a different draft from said draft. CONSTITUTION:A molten alloy consisting of 0.15-0.35% Zr, 0.05-0.5% Fe, 0.03-0.25% Si and the balance essentially Al is continuously cast and rolled with a casting machine combined continuously with a hot rolling mill. The preferred solidification conditions during the casting include cooling for regulating the starting temp. of the hot rolling to >=530 deg.C after the casting at 5.0-7.0t/hr rate with the casting machine provided with a rotating casting wheel having 3,600mm.<2> cross-sectional area of the mold. The rolled alloy is cold-rolled at >=50% draft, aged at 300-500 deg.C for 5-200hr, and cold rolled at >=35% draft. Thus, an electrically conductive heat-resistant alloy having said characteristics and maintaining >=300 deg.C 10% softening temp. under heating for 1hr is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a conductive heat-resistant aluminum alloy wire (hereinafter abbreviated as aluminum alloy wire) having excellent heat resistance and conductivity.

Conventionally, as heat-resistant aluminum alloys for conductive use, aluminum alloy wires with excellent heat resistance and conductivity have been obtained by adding a small amount of Zr to Al and incorporating Zr as a solid solution during the manufacturing process (for example, Patent No. 1842110, No. 842
No. 111).

Such conductive heat-resistant aluminum alloy wire is known as 60% heat-resistant aluminum alloy wire (6oTAA), and its conductivity is 60%.
%lAC3 or higher, and the heat resistance is such that the continuous use temperature is 150°C.

In recent years, we have further improved the heat resistance of conductive heat-resistant aluminum alloy wire,
There is a strong desire to 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 steps, the present invention has a conductivity of 60%, which is the same as 60TAz.
~0.35%, FeO, 05~0.5%, 5iO1
After continuous casting and rolling, the molten alloy is subjected to cold working with an area reduction of 50% or more, and then heated at 300 to 500°.
A conductivity of 60% can be achieved by aging at C for 5 to 200 hours and then cold working with an area reduction of 35% or more.
lAC3 or higher, has strength equivalent to hard aluminum wire,
The heat-resistant aluminum alloy wire for electrical conduction is characterized in that the wire has a softening temperature of 10% or higher than a o o 'c after being heated for one hour.

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 of Zr increases, the heat resistance deteriorates and the cost also increases.

Also, the amount of Fe was specified as 0.05% to 0.5%.
If it is less than 5%, the strength of the drawn wire will be low, and it will not be effective in shortening the aging time (because if it exceeds 0.5%, the electrical conductivity and heat resistance will decrease).

Moreover, the reason why the amount of Si was specified as 0.03 to 0.25% was because
If it is less than 0.03%, not only will the cost of the base metal increase, but it will also be ineffective in shortening the aging time, and if it exceeds 0.025%, casting cracks will be noticeable and the heat resistance will also decrease.

Next, in the present invention, the continuous casting and rolling of the molten alloy is carried out by continuous hot rolling 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 casting machine such as the Hezlett method or the 3C method. A combination of rolling mills is used.

According to such a continuous casting and rolling method, the Zr that is forcibly dissolved during casting is brought to the hot rolling process without being precipitated, so that the A I B Z
It precipitates uniformly and finely as r, and can significantly improve heat resistance.

The solidification conditions during casting are, for example, 5.0 -
7. By casting within the Otorybr range 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 molten metal temperature (casting temperature) immediately before the casting machine is preferably 700'C or higher.

The reason for this is that when the Zr concentration is high as in the present invention, Zr is formed in the form of AIBZr when the casting temperature is less than 700°C.
This is because r crystallizes in the form of coarse particles, and the amount of added Zr that can exert an effect on heat resistance decreases, and at the same time, the crystallized coarse particles reduce heat resistance.

In addition, the temperature of the ingot immediately before the hot rolling mill (rolling start temperature) is 5.
The temperature is preferably 30'C or more, and if this temperature is less than 530'C, the heat resistance will deteriorate. 530 depending on outside temperature, casting conditions, etc.
If the temperature is below 'C, the ingot is heated after leaving the caster and before entering the rolling mill.

51 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 to obtain heat resistance (10% softening temperature) of 300°C or more. It is 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 setting appropriate aging conditions, the heat resistance can be as high as 358°C at a 10% softening temperature.
In cold working with an area reduction rate of less than 50%, a 10% softening temperature of 300° C. or higher cannot be obtained no matter what kind of aging treatment is performed thereafter.

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 electrical conductivity can be expected, but no effective improvement can be expected.

Since heat resistance and electrical conductivity must be satisfied at the same time, in the present invention, the area reduction rate of the above-mentioned cold working is reduced to 50%.
The above is stipulated.

Next, in the present invention, the aging treatment conditions after cold working are specified to be 5 to 200 hours at 300 to 500"C.
Through this heat treatment, Zr is uniformly and finely precipitated as A7'3Zr to improve electrical conductivity, and dispersion strengthening by finely precipitated klBZr improves heat resistance. This is because the temperature becomes long, which impedes productivity, and when the temperature exceeds 500°C, the precipitates become coarse and the heat resistance deteriorates.

Temperature and time in aging treatment are correlated as optimal conditions; the higher the temperature, the shorter the time.
Aging conditions of 50 to 80 hours at 90°C are optimal, and the 10% softening temperature after heating for 1 hour can be 330°C or higher.

In addition, cold working with an area reduction of 35% or more is performed after the final aging treatment because cold working with an area reduction of 35% or more is required in order to have the same strength as a hard aluminum wire. This is because if it is less than %, the desired strength cannot be obtained. Note that the aging treatment here may be divided into several times, and surface reduction processing may be included in between. However, from the point of view of industrial production, one aging treatment is desirable.

Further, it is desirable that the impurities contained in the aluminum ingot used as a raw material in the present invention be suppressed to as little as possible.

By configuring the present invention as described above, the heat resistance can be increased to a 10% softening temperature of 300°C or more after heating for one hour, which means that the continuous use temperature is 210°C and the short-time use temperature is 260°C. It has high heat resistance of about C, conductivity of 60% AC3 or more, strength equivalent to hard aluminum wire, and has a wide temperature and time range for aging treatment.
It has the effect of being stable and easy to manufacture.

The present invention will be explained below with reference to Examples.

Example 1: Electrical aluminum ingot containing ordinary impurities (JISH211
0) was added with the amounts of Zr, Fa, and Si shown in Table 1 and subjected to degassing treatment, and then continuously cast using a rotary wheel type casting machine with a mold cross section of 3200 m and 2 to obtain a cast bar.
Subsequently, hot rolling was performed continuously to obtain a rough wire of 11.7 mO. In this case, the molten metal temperature just before the casting machine (casting temperature)
was 720 to 750°C, and the temperature of the cast rod immediately before the rolling mill (rolling start temperature) was 550 to 570°C.

Next, the rough drawn wires were subjected to cold working (referred to as working ■), aging treatment (referred to as treatment), and cold working (referred to as working ■) under the conditions shown in Table 1.

The tensile strength, electrical conductivity, and 10% softening temperature of the obtained aluminum alloy wire are as shown in Table 1.

From Table 1, the tensile strength of Al-10 according to the present invention is equivalent to that of hard aluminum wire (A1.l), and the electrical conductivity is 60%l.
It can be seen that it has an AC of 3 or higher and a 10% softening temperature of 800°C or higher. On the other hand, in comparative examples outside the composition range of the present invention, A15, A1 containing a large amount of Si.
6, casting cracks occur and continuous casting is impossible;
And other things! No. 12 to 14, 17, and 18 did not satisfy all of the tensile strength, electrical conductivity, and heat resistance.

Example 2: An aluminum alloy having the same composition as A8 shown in Table 1 was continuously cast and rolled in the same manner as in Example 1 to obtain a rough drawing line of IL'7mxpf. However, the casting temperature was 710 to 740°C, and the rolling start temperature was 540 to 580°C.

Next, the rough drawn wire was subjected to processing (1), treatment and processing (2) shown in Example 1 under the conditions shown in Tables 2 and 3, respectively.

The 10% softening temperature or tensile strength of the obtained aluminum alloy wire is as shown in Tables 2 and 3.

-11= 10- Table 2゜Table 3゜The effect of the area reduction rate of processing (■) shown in Table 2 on the 10% softening temperature is 300 °
C or higher, but in comparative examples with an area reduction rate of less than 50%, 300
Does not reach °C.

The effect of the area reduction rate of processing (■) on the tensile strength shown in Table 3 is based on the present invention! 1'7 Ky/myr2 for 28-33
Although the above can be obtained, it is clear that the comparison example with an area reduction rate of less than 85% does not reach 17/ax2.

As described above, the aluminum alloy wire of the present invention is made of ZrO,1
5~OJ5%, FeO,05-0,5%, Si0.
Since the molten alloy is continuously cast and rolled, Zr, which is forcibly dissolved in solid solution during casting, is dissolved in solid solution without precipitation, and after continuous casting and rolling. , cold working with an area reduction rate of 50% or more is performed, and then aging treatment is performed at 300 to 500°C for 5 to 200 hours, so the above cold working is combined with aging treatment to improve electrical conductivity and heat resistance. is obtained at the same time, Zr is uniformly and finely precipitated and dispersed as AJaZr by the above heat treatment, and the heat resistance is improved.Furthermore, after the aging treatment, cold working with an area reduction rate of 35% or more is performed to obtain the desired strength. Therefore, it has the advantage of having an electrical conductivity of 60% lAC3 or higher, a strength equivalent to that of a hard aluminum wire, and excellent heat resistance with a lO% softening temperature of 300° C. or higher when heated for one hour.

Furthermore, since the aging treatment has a wide range of temperature and time, it has the advantage that stable heat resistance performance can be easily produced.

Claims (3)

[Claims] (1) ZrO, 15-0.35%, FeO,
05 to 0.5%, SiO, 03 to 0.25%, and the remainder consists of Al and normal impurities, and after continuous casting and rolling of the molten alloy, cold working with an area reduction of 50% or more is performed. ,
Next, it is aged at 300-500°C for 5-200 hours, and then cold-worked with an area reduction of 35% or more, resulting in a wire with a conductivity of 60% lAC3 or more and strength equivalent to hard aluminum wire. and heated to 300°C for one hour.
A conductive heat-resistant aluminum alloy wire characterized by having a softening temperature of 10% or more. (2) The conductive heat-resistant aluminum alloy wire according to claim (1), which is cast at a casting temperature of 700'C or higher. (3) The conductive heat-resistant aluminum alloy wire according to claim (1) or (2), wherein the rolling is performed at a rolling start temperature of 530°C or higher.