CA1041797A - Aluminum alloy for electric conductors and its method of manufacture - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

An aluminum alloy for electric conductors having a conductivity of not less than 59% IACS, which is further highly strong and ductile yet eligible for conventional high-speed tandem manufacturing using a continuous annealing treatment.
The aluminum alloy consists essentially of 0.01 - 1.5 Wt-%
nickel, and one or more elements selected from the group of 0.1 - 1.0 weight-% iron, 0.05 - 0.35 weight-% magnesium and 0.001 - 0.1 weight-% beryllium, and a balance of aluminum.

Description

BAC~GF~OUND OF THE I~ENTION `
This invention relates generally to aluminum alloys and -.
more particularly to aluminum alloy conductors. ~
Heretofore copper wires have been used as the electro- .
magnetic conductors in transformers, motors, etc.~ conductors for communication cables and conductors for building wires exclusively.
In more recent times, however, the rise and fluctuations of the :~
price of copper throughout.the world has ac.celerated the desire ~ .
for the substi.tution of copper with aluminum as a material for conductors. This substitution is made even more desirous with the increase in need to make electric machines and appliances, ~
cables, etc. lighter. For these reasons, trends toward the use ~-of aluminum and aluminum alloy wires as such conductors have suddenly become remarkable. It has thus become the case that the aluminum alloy wires used for these purposes are required to possess properties similar to those of the copper wires used in the past. The properties required of such aluminum alloy wires used as conductors for magnetic wires, conductors for communication cables and conductors for building wires, etc .~ .
are as follows: -(l) As conductors, they are required to have a high ` :
electric conductivity, which must not:be lower than 59% IACS.

(2) As for mechanical properties, they must possess qualities of flexibility suitable for electric wires, ductility and flexibility sufficient to withstand the bending at the time of manufacture and use, and some degree of strength which will .
withstand the required tension applied thereto at.the time of manufacture and use, As a result of a study from these various angles, the inventors have found that for these purposes a conductor having :~
a tensile strength of about 13.5 - 15 kg/mm2 and elongation of about 3.5 - 4~5% is at least required.
.. .
-- 2 -- ~, LD/

7~7

(3) The wire for the conductors, especially conductors of communication cables, is usually manufactured by a high speed tandem operation of drawing, annealing and insulation coating. ~ - -Consequently, the manufacturing processes must not be interrupted 5 by a heat treatment step or the like. The heat treatment made to the conductor to obtain satisfactory properties must therefore be one which does not call for such complicated treatments as ~;
quenching, tempering, etc~, and the annealing must be such that it can be done by a continuous process. ;
For power transmission lines and power distribution lines, aluminum alloys for electrical purposes, such as Al-Mg alloys ~
which are called alloys of the work-hardened type (for example, ~ ~ -Alloy 5005), Al-Mg-Si alloys which are called alloys of the heat-treatable type (for example, "Aldray" Aluminum Alloy, Alloy 6201), etc. have heretofore been used in the form of an "aluminum conductor steel reinforced" (known as ACSR), an "all aluminum ~
conductor" (AAC), an "all aluminum alloy conductor" (AAAC), an -~-"aluminum conductor aluminum alloy reinforced" (ACAR), etc. All ~ ;
of these are put to use after cold working or after heat treatment such as quenching, tempering, etc. and they have a high tensile -strength. However, they do not have sufficient ductility for `
magnet wires, communication conductors and building wires. Further-more, they have a very low electric conductivity (electric con-.. . .
ductivity of 52 - 55% IACS) with the exception of electric conductor grade aluminum.
-; . ,..,, . .,., .. ~
To obtain such a medium tensile strength as already mentioned i;
(13.5--15.0 kg/mm ), the present inventors tried the two methods heretofore usually employed in the manufacture of half-hard aluminum wires - namely, a method in which continuous annealing to half- -hardness is done at the final size, and a method in which cold work-ing of 30~-or less is done after complete annealing at a size near ~-the final size to finish the wire to its final size. However, the tensile strength was unsatisfactory (about 11 kg/mm2) in the case -/

7~17 of electric conductor grade aluminum, while in the case of aluminum alloys the electric conductivity was very low, i.e. 57% or less, even though the tensile strength and elongation were satisfactory.
There is on the other hand, an aluminum alloy for electrical purposes, that is a soft material which is an Al-Fe~Mg-Si alloy developed for use as rotors in rotary machines and is commonly ~`
called Cond-aluminum alloy. It is recommended as having an excellent resistance to creep. (See for example, U~S. Patent No. 2,572,562) As its ~g2Si precipitation-phase is made a strengthening factor, this alloy is of the age-hardening type.
It contains 0.2-1.1 wt-~ Fe, 0.2-0.5 wt-% Mg and 0.05 - 0.15 Wt-~ Si. A conductor which is comparatively excellent in strength, electric conductivity and ductility is obtained by adding comparatively large quantities of Mg, Fe and Si~ and -applying heat treatment for a long time at a high temperature of 400C - 450C, and then cold-working the alloy to an extent of about 10%. For the afore-mentioned uses, especially for communication cables, however, the necessity of long time heat treatment at a high temperature is a fatal disadvantage in their manufacture. That is to say, there is the problem of sticking caused by long time annealing at a high tempera-ture if the conductors are of a small diameter, and the batch annealing method does not apply for the afore-mentioned high speed tandem manufacturing line. As described in detail later in an Example, the inventors tried on this alloy, the low temperature short-time batch annealing treatment and a continu~
ous annealing treatment omitting the batch annealing process, and also reduced its Fe and Mg contents to obtain a high electric -~
conductivity. However, sufficient properties could not be obtained with this alloy~

- LD/

. . " . , , . ~

797 ~: ~
This invention provides an alluminum alloy electric wire conductor consisting essentially of 0.01 - 1.5 wt-~ nickel and 0.001 - 0.1 wt-% beryllium, and one or two elements selected from the group consisting of 0.1 - 1.0 wt-% iron and 0.05 - 0.35 ;;
wt-% magnesium, and a balance of aluminum, the wire conductor be-ing characterized by having the properties of electric conductiv-ity, ductility, s~rength and flexibility, which when taken in com- ;~
bined form are greater after continuous annealing treatment of the wire conductor following cold drawing than the same wire com- `~ `~
10 position which is devoil of or contains the prescribed elements `
other than in the manner and ranges specified. This invention provides an aluminum alloy for electric-conductors which is capable ;~
of being finished into conductors by melting, casting, hot working, -cold working, heat treatment, etc. for uses similar to those of ~
ordinary aluminum alloy conductors~ ` -The aluminum alloy of the present invention further satis-~ fies the requirements of electric conductivity of not less than ;~
59% IACS, and is further excellent with respect to strength and ductility, after a continuous annealing process as may be carried -~
. ;; ,: i, .,:,,, .,~ " ,~
out on a high speed tandem manufacturing line for electric wires `;
and cables.
In its method aspect the invention relates to method of manufacturing an aluminum alloy electric wire conductor comprising the steps of mixing approximately 0.01 - 1.5 wt-% nickel and 0.001 - 0.1 wt-% beryllium, and one or two elements selected from the group consisting-of 0.1 - 1.0 wt-% iron and 0.05 ~0.35 `
wt-% magnesium, and a balance of aluminum, melting the mixture, casting the melted mixture, hot rolling the material casting into a rod, cold drawing the rolled rod into a wire, and applying a continuous annealing treatment to the cold drawn wire.
~,:
`'., ` ..
;.

rw/ .; ~ i 3,7 ~:
DETAILED DESCRIPTION OF THE INVENTION
.__ ., . . ~ .
This invention provides an aluminum alloy which can satisfy the most important requirements of such magnet wires and con~
ductors for communication cables and building wires and which ~
5 consist of approximately 0.01 - 1.5 weight-~ nickel, and one or -more element selected from the group of 0.01 - 1 0 weight-%
iron, 0.05 - 0.35 weight-% magnesium and 0.001 - 0.1 weight-%
beryllium, and a balance of aluminum.
There have been several reports on the results of an investigation made on the recrystallization behavior, work hardening property, crystal grain size, electric conductivity, etc. of aluminum to which one or more element selected from the group consisting of nickel/ magnesium, iron and beryllium, etc~
has been added singly or in combination. Most of them, however, deal with work hardened materials or cast materials, and none of them discuss the overall properties of electric conductivity, ductility and strength of soft materials or materials of half- --' -hard. A material suitable for conductors as magnet wires, com-munication cables, and building wires, like the material of this invention, has not been mentioned.
The object of this invention is to eliminate the afore- `
mentioned disadvantages of conventional aluminum alloys and to provide an aluminum alloy for electric conductors for magnet wires, communication use and building wires which are excellent with respect to electric conductivity, ductility and strength as an annealed material or a half-hard material, and which are eligible for continuous annealing which is indispensable in a high speed continuous manufacture line.
This invention pertainsto analuminum alloy which essentially LD/

contains approximately 0.01 - 1.5 weight-% nickel and one or more element selected from the group consisting of 0.1 - 1.0 weight-% iron, 0.05 - 0.35 weight-% magnesium and 0.001 - 0.1 weight-% beryllium, and is characterized in that a conductor excellent in electric conductivity, ductility and strength is obtained by the latest high speed manufacture tandem line methods including continuous annealing.
The reason why the nickel content is here limited to 0.01 -1.5 weight-% is that if the content is 0.009 weight-% or less, it makes almost no contribution to the increase of the strength of the annealed material, while if it is 1.6 weight-% or more, it causes marked decrease in the electric conductivity and also becomes problematical from the viewpoint of cost.
The reason why the iron content is specified to be 0.1 15 weight-% - 1.0 weight-% is that if it is 0.09 weight-% or s less, it is little effective to improve strength and ductility, while if it is 1.1 weight-% or more, it causes a marked decrease in electric conductivity and -the alloy b~comes difficult to cast.
;,x i ~, .
The reason why the magnesium content is specified to be 0.05 weight-% - 0.35 weight-% is that if it is 0.04 weight-%
or less, it is scarcely effective in improving strength, while if it is 0.35 weight-% or more, it causes a marked decrease in electric conductivi-ty The reason why beryllium content is specified to be 0.001 weight-% - 0.1 weight-% is that if it is 0.0009 wei~ht-% or less, -it is scarcely effective in improving ductility and electric conductivity, while if it is 0.11 weight-% or more, it not only ~ -~
causes a decrease in electric conductivity but also has little advantage from the viewpoint of cost.
., .

' ~'.' , , ~ ~ LD/

It is quite permissible if the afore-mentioned aluminum alloy contains such impurities as B, Ti, Mn, Cu, Si, etc. which are usually contained in ordinary eIectric conductor grade aluminum For the purpose of getting a higher electric con-ductive alloy, the alloy must be treated with a small quantityof boron before casting. Furthermore, it is also quite permissible if the alloy is caused to contain a very small quantity of Sb, which is widely known as an element to improve the corrosion-resistance of aluminum alloys, for the purpose of improving the corrosion-resistance of the alloy.
The alloy of this invention will now be explained in detail, with reference to examples of experiment.
Example 1:
Alloys of various compositions were manufactured by the usual melt casting method, adding nickel to boron treated aluminum for electrical purposes as a single element and magnesium,~iron and beryllium in the form of mother alloys of Al - 10 wt-% Mgr Al - 50 wt-~ Fe and Al - 5 wt-% Be. The casting temperature was about 710C and the size of the ingot `
20 was 150 mm square. After making wire rods of a diameter of 12 mm by hot rolling at 400C, they were cold-drawn to a diameter of a . 51 mm without giving them any intermediate heat treatment.
These wires 0.51 mm in diameter were given an electric resistance continuous annealing treatment at a line speed of about 1,000 meters/minute, the voltage and current being adjusted so as to obtain an elongation of 3.5~ - 4.5%, the target value for ductility. Although the optimum conditions for this purpose vary with the alloys, they were found to be about 30 -50 V of voltage and 30 - 70 A of current for a charge span of 30 1,500 mm. The alloys of prior art shown in Table 1 are alloys of the constitutions of Cond-aluminum Alloy, LD/

~179~
Alloy 5005, etc.
Some of the results are shown in Table 1, Table 1 ~;~

Elements (Analysis value, Properties No. ~ei~ ~t-~) ¦ , Ni Mg Fe Be Electric Elonga- Tensile Conduct- tion Strength i~ity(~0)* (Kg/mm2) (% IACS) . . . `' ' ' 1 0.07 _ 0.15 _ 62.34.0 11.4 2 0.5 _ 0.14 _ 61.54.0 13.6 3 0.5 0.1 0.14 _ 60.94.0 14.1

4 0.5 0.1 0.140.01 61.14.5 14.2 g 5 0.6 _ 0.6 _ 61.24.0 13.4 R 6 0.6 _ 0.60.005 61.34.5 13.4 ~ 7 1.1 _ 0.13 _ 60.54.0 14.3 0 8 1.0 0.1 0.12 _ 59.84.0 14.6 9 0.3 0.1 0.14 _ 61.64.0 13.6 0.3 0.2 0.14 _ 60.64.5 14.2 11 0.3 0.3 0.15 _ 59.1 4.5 1 14.6 12 0.3 0.3 0.140.0~ 59.4 4.0 14.6 13 0.3 0.~ 0.130.08 59.2 4.0 14.5 14 0.5 0.1 0.6 _ 60.5 4.0 14.1 0.5 0.1 0.70.01 60.7 4.0 14.3 16 _ _ 0.13 _ 62.4 4.0 10.9 h 17 _ 0.1 0.14 _ 61.3 4.0 12.1 h 18 _ 0.2 0.5 _ 60.2 4.0 12.8 ~ 19 _ 0.3 0.5 _ 59.1 4.0 13.1 _ 20 _ 0.4 0.5 _ 58.0 4.0 13.5 * G~uge 1ength: 250 ~m 7~7 As can be clearly seen from Table 1, this invention provides aluminum alloy for electric conductors which has excellent combined properties of electric conductivity, ductility and strength. It can be seen that compared with the alloys of prior art, it is equal in electric conductivity and ductility and is superior in strength. As regards the reason for this, it is considered that nickel added in a very small quantity increases the strength and ductility of the soft material without detriment-ally affecting the electric conductivity almost at all.
Example 2:
By manufacturing processes similar to those of Bxample 1, various aluminum alloys were hot-rolled and cold-drawn, and then a similar continuous annealing treatment was given at a diameter of 0.51 mm and, after that, gi~en a cold-drawing of 15~. The conditions for this continuous annealing preceding the drawing were adjusted so as to make the elongation after drawing 3.5% -4.5%. This method is commonly employed when manufacturing the ordinary half-hard material. It is a method usually employed in case a stabilized manufacture of half-hard material is not possible by continuous annealing only. Some of the results obtained are shown in Table 2.
Table 2 . ........... . , ..... _ _ Elements (Analysis value, Properties weight No. Ni Mg Fe Be Electric Elonga- Tensile Conduct- tion Strength i(%iIAYCS) (~)* (Kg/mm2) . .
~o 21 0.6 _ 0.6 _ 61.3 3.5 13.2 P 22 0.6 _ 0.60.005 61.5 4.0 13.2 23 o.3 0.1 0.14 _ 61.8 4.0 13.3 24 0.3 0.3 0.15 _ 59.4 4.0 14.0 -3 0-3 0.140.01 59.6 4.0 14.1 * Gauge length: 250 mm ~ ~4~797 ~
As can clearly be seen from Table 2, a tendency that electric conductivity is somewhat higher and elongation and strength are somewhat lower as compared with Table 1 was observed. It is evident, however, that an optimum continuous annealing condition can be obtained in a comparatively broad range in Example 2. It is considered tha-t Example 2 is of a greater stability for industrial production.
Example 3:
~, , By manufacturing processes similar to those of Example 1, various aluminum alloys were hot-rolled and then cold-drawn to a wire rod of 2.0 mm diameter.
They were annealed at 2.0 mm diameter for a short time at a comparatively low temperature of 230C x 1 hr and then cold-drawn to a diameter of 0.51 mm and given electric resistance continuous annealing. Drawing conditions and continuous annealing conditions are about equal to those of Example 1. Some of the results obtained are shown in Table 3. The alloy of prior art has a constitution equal to that of Cond-aluminum Alloy.

Table 3 _ . _ , . . . :
Elements (Analysis value, .
wei ,ht-~) Propert No. Electric Elonga- Tensile Ni Mg Fe Be ivity t on S(tg/mm2t)h (% IACS) ~
~ 26 0.6 _ 0.6 _ 61.3 4.0 13.0 ~o 27 0.6 _ 0.6 0.005 61.6 4.0 13.0 P~ 2~ 0.3 0.1 0.14 _ 61.9 4.0 13.2 ~ 29 0.3 0.3 0.15 _ 60.3 4.5 14.0 H 30 0.3 0.3 0.140.01 60 5 4 0 14 2 ~ ' .
h ~ 31 _ 0.4 0.5 _ 59.1 13.8 .

* Gauge length: 250 mm "

L7~
As can be seen clearly from Table 3, the alloy of the present invention shows a marked improvement in electric conductivity as a result of an intermediate annealing at a comparatively low temperature for a comparatively short time.
For instance, No~ 12 of Example 1 and No. 30 of this Example are compared with each other. It is noted that where magnesium which is comparatively liahle to affect electric conductivity detrimentally is contained in a quantity of about 0.3 weight-%, electric conductivity can be improved by intermediate low temperature annealing at a suitable size, it being made possible to obtain the target conductivity of 59% IACS or more. The Al-Fe-Mg alloy No. 31 of the prior-art cannot recover sufficient electric conductivity as a result of an intermediate annealing at a temperature of about 250C, possibly because its recrystal-lization temperature is high, and it is evident that the alloy of this invention has better properties.
When the alloy was made a s~oft material by the continuous annealing of this Example and then given cold-drawing of a draft not exceeding 30%, properties similar to those of the alloy of ~
this invention shown in Table 3 were obtained. ;
Example 4:
By processes about similar to those of Example 1, wire rods of a diameter of 3.0 mm were obtained, then manufactured into a soft rod (elongation: 15 - 20%, gauge length = 250 mm) by annealing at 150C - 300C for 1 hour, and their strength and electric conductivity were measured. Some of the results obtained are shown in Table 4.
The alloy No. 37 of the prior art has the constitution of Cond-aluminum alloy~

LD/
~ ' ' ': '' . :

Table 4 , :
Elements (Analysis value, ~
weight-%) Propertles No. Electric Elonga- Tensile Condition Ni Mg Fe Be ivity t~o)on* (tg/mm2)h annealing (~ IACS) treatment . _ . , . . , ~32 0.6 _ 0.6 _ 61.5 16 12.6 260Cxl hr o33 0.6 _ 0.6 0.005 61 7 17 12.6 250Cxl hr 34 0.3 0.1 0.14 _ 61.9 16 12.4 260Cxl hr ~35 0.3 0~3 0.15 _ 60.4 17 12.6 320Cxl hr ~36 0 3 0 3 0.14 0.01 60.6 17 12.7 310Cxl hr .
37 _ 0.4 0.5 _ 59.3 16 12.4 350~Yl hr * Gauge length: 250 mm As can be seen clearly from Table 4, the alloy of this `
invention can be given excellent electric conductivity, ductility and streng-th even by the ordinary annealing method and the fact that a comparatively low temperature and short time are good enough as conditions for its annealing offers great advantage in preventing the stickir.g together of wires at the time of nnnealing ;
and Rlso from the view-point of cost.
As has been mentioned in detail with reference to the Examples, this invention provides aluminum alloy for electric conductors which sssentinlly contains 0.01 - 1.5 weight-% nickel and one or more of 0.1 - 1.0 weigh-t-~o iron, 0.05 - 0.35 weight-~o magnesium and 0.001 - 0.1 weight-% beryllium, the balance aluminum, and which is a material having excellent overall properties of electric conductivity, ductility and strength optimum for use for conductors of magnet wires, conductors of communication cables and conductors of building wires etc. Furthermore, the alloy of this invention can be given optimum properties as a soft material 7~7 or half-hard material by a manufacturing process of continuous annealing at the final size or of continuous annealing-cold drawing or of intermediate annealing-cold drawing-continuous annealing, so that it is feasible for a modernized high speed tandem manufacturing line and its value for industrial utilization is extremely great.

.... . .. . . . . .. .. . ... .. . ... .. . . .

Claims (5)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An aluminum alloy electric wire conductor consisting essentially of 0.01 - 1.5 wt-% nickel and 0.001 - 0.1 wt-% beryl-lium, and one or two elements selected from the group consisting of 0.1 - 1.0 wt-% iron and 0.05 - 0.35 wt-% magnesium, and a bal-ance of aluminum, said wire conductor being characterized by hav-ing the properties of electric conductivity, ductility, strength and flexibility, which when taken in combined form are greater after continuous annealing treatment of the wire conductor follow-ing cold drawing than the same wire composition which is devoid of or contains the prescribed elements other than in the manner and ranges specified.

2. The method of manufacturing an aluminum alloy electric wire conductor comprising the steps of mixing approximately 0.01 -1.5 wt-% nickel and 0.001 - 0.1 wt-% beryllium, and one or two elements selected from the group consisting of 0.1 - 1.0 wt-%
iron and 0.05 - 0.35 wt-% magnesium, and a balance of aluminum, melting the mixture, casting the melted mixture, hot rolling the metal casting into a rod, cold drawing the rolled rod into a wire, and applying a continuous annealing treatment to the cold drawn wire.

3. The method of manufacturing an aluminum alloy electric wire conductor comprising the steps of mixing approximately 0.01 -1.5 wt-% nickel and 0.001 - 0.1 wt-% beryllium, and one or two elements selected from the group consisting of 0.1 - 1.0 wt-% iron and 0.05 - 0.35 wt-% magnesium, and a balance of aluminum, melting the mixture, casting the melted mixture, hot rolling the metal casting into a rod, cold drawing the rolled rod into a cold. drawn wire of an intermediate size, applying a continuous annealing treat-ment to the cold drawn wire, and cold drawing the continuously annealed wire into a half-hard conductor of a draft of 30% or less.

4. The method of manufacturing an aluminum alloy elec-tric wire conductor comprising the step of mixing approximately 0.01 - 1.5 wt-% nickel and 0.001 - 0.1 wt-% beryllium, and one or two elements selected from the group consisting of 0.1 - 1.0 wt-% iron and 0.05 - 0.35 wt-% magnesium, and a balance of alum-inum, melting the mixture, casting the melted mixture, hot rolling the metal casting into a rod, cold drawing the rolled rod into a cold drawn wire of an intermediate size, applying an annealing treatment at 200° to 300°C cold drawing the annealed wire into a cold drawn conductor of a final size, and applying a continuous annealing treatment to the cold drawn conductor.

5. The method of manufacturing an aluminum alloy electric wire conductor comprising the step of mixing approximately 0.01 - 1.5 wt-% nickel and 0.001 - 0.1 wt-% beryllium, and one or two elements selected from the group consisting of 0.1 - 1.0 wt-% iron and 0.05 - 0.35 wt-% magnesium, and a balance of alumin-um, melting the mixture casting the melted mixture, hot rolling the metal casting into a rod, cold drawing the rolling rod into a cold drawn wire of an intermediate size, supplying an annealing treatment at 200° to 300°C, cold drawing the annealed wire into a cold drawn wire of an intermediate size, applying a continuous annealing treatment to the cold drawn wire and cold drawing the continuously annealed wire into a half-hard conductor of a draft of 30% or less.