U.S. patent number 3,811,846 [Application Number 05/259,722] was granted by the patent office on 1974-05-21 for aluminum alloy electrical conductor.
This patent grant is currently assigned to Southwire Company. Invention is credited to Enrique C. Chia, Roger J. Schoerner.
United States Patent |
3,811,846 |
Schoerner , et al. |
May 21, 1974 |
ALUMINUM ALLOY ELECTRICAL CONDUCTOR
Abstract
Aluminum alloy electrical conductors are produced from aluminum
base alloys containing from about 0.20 to about 1.60 weight percent
cobalt, from about 0.30 to about 1.30 weight percent iron, up to
about 0.40 weight percent magnesium, up to about 0.40 weight
percent copper, from about 99.50 to about 97.00 weight percent
aluminum and up to about 0.45 weight percent each of additional
alloying elements, the total weight percent of additional alloying
elements not exceeding about 0.70 percent; the total weight percent
of magnesium and copper not exceeding about 0.40 percent and the
total weight percent of additional alloying elements not exceeding
about 0.40 percent when the total weight percent of cobalt and iron
exceeds about 1,80 percent. The alloy conductors have an electrical
conductivity of at least 57 percent, based on the International
Annealed Copper Standard (IACS), and improved properties of
increased thermal stability, tensile strength, percent ultimate
elongation, ductility, fatigue resistance and yield strength as
compared to conventional aluminum alloys of similar electrical
properties.
Inventors: |
Schoerner; Roger J.
(Carrollton, GA), Chia; Enrique C. (Carrollton, GA) |
Assignee: |
Southwire Company (Carrollton,
GA)
|
Family
ID: |
26788594 |
Appl.
No.: |
05/259,722 |
Filed: |
June 5, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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94193 |
Dec 1, 1970 |
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54563 |
Jul 13, 1970 |
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Current U.S.
Class: |
420/535;
29/527.7; 148/439 |
Current CPC
Class: |
H01B
1/023 (20130101); C22C 21/00 (20130101); Y10T
29/49991 (20150115) |
Current International
Class: |
H01B
1/02 (20060101); C22C 21/00 (20060101); B21c
001/00 (); C22f 001/04 () |
Field of
Search: |
;29/183,183.5,193,527.7
;75/138-148 ;148/2,3,11.5A,32 ;164/76 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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498,227 |
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Jan 1939 |
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GB |
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706,721 |
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Jun 1931 |
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FR |
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Other References
Kruptokin et al., The Mechanical Properties of AVOOO Aluminum with
Small Additions of Different Elements, Metals Abstract, December,
1969, 31 2,291. .
Kruptokin, Influence of Small Additions of Iron, Nickel and Cobalt
on Mechanical Properties and Conductivity of Aluminum, Slavic
Library, November 30, 1965, Battell Memorial Institute..
|
Primary Examiner: Dean; Richard O.
Attorney, Agent or Firm: Hanegan; Herbert M. Wilks; Van
C.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of our copending
application, Ser. No. 94,193, filed Dec. 1, 1970, now abandoned,
which in turn is a continuation-in-part of our copending
application, Ser. No. 54,563, filed July 13, 1970, now abandoned.
Claims
1. Aluminum alloy electrical conductor having a minimum
conductivity of 58 percent IACS consisting essentially of from
about 0.20 to about 1.60 weight percent cobalt, from about 0.30 to
about 1.30 weight percent iron, the remainder being aluminum with
associated trace elements, said aluminum alloy electrical conductor
having the following properties when measured as a No. 10 A.W.G.
fully annealed wire:
Tensile strength: 12,000 - 24,000 psi
Elongation: 12 - 30 percent
2. The aluminum alloy electrical conductor according to claim 1
further including an additional alloying element selected from the
group consisting of magnesium, copper, silicon and mixtures
thereof; the combined weight percentage of magnesium and copper not
to exceed about 0.8 percent, and the silicon weight percentage not
to exceed about 0.45
3. The aluminum alloy electrical conductor according to claim 2
wherein the combined weight percentage of magnesium, copper and
silicon not to exceed about 0.8 percent when the combined weight
percentage of cobalt and iron
4. The aluminum alloy electrical conductor according to claim 2
wherein the combined weight percentage of magnesium and copper does
not exceed about 0.20 percent, the combined weight percentage of
additional alloying elements does not exceed about 0.10 percent,
and the combined weight
5. The aluminum alloy electrical conductor according to claim 2
wherein the additional alloying element is magnesium in an amount
up to about 0.40
6. The aluminum alloy electrical conductor according to claim 2
wherein the additional alloying element is copper in an amount up
to about 0.40 weight
7. The aluminum alloy electrical conductor according to claim 2
wherein the additional alloying element is silicon in an amount up
to about 0.45
8. The aluminum alloy electrical conductor according to claim 2
wherein cobalt is present in a weight percentage of from about 0.20
to about 1.0 percent and iron is present in a weight percentage of
from about 0.3
9. The aluminum alloy electrical conductor according to claim 2
wherein cobalt is present in a weight percentage of from about 0.30
percent to
10. The aluminum alloy electrical conductor according to claim 1
wherein the weight percentages of the constitutents are as follows:
Cobalt 0.80% Iron 0.50% Misch Metal 0.40%
11. The aluminum alloy electrical conductor according to claim 1
wherein the weight percentages of the constituents are as
follows:
12. The aluminum alloy electrical conductor according to claim 2
wherein the weight percentages of the constituents are as
follows:
13. The aluminum alloy electrical conductor according to claim 1
wherein the weight percentages of the constituents are as
follows:
14. The aluminum alloy electrical conductor according to claim 1
wherein
15. The aluminum alloy electrical conductor according to claim 1
wherein
16. Aluminum alloy electrical conductor having a minimum
conductivity of 58 percent IACS consisting essentially of from
about 0.20 to about 1.60 weight percent cobalt, from about 0.30 to
about 1.30 weight percent iron, the remainder being aluminum with
associated trace elements, said aluminum alloy electrical conductor
having the following properties when measured as a fully annealed
wire:
Tensile strength: at least 12,000 psi
17. The aluminum alloy electrical conductor according to claim 16
further including an additional alloying element selected from the
group consisting of magnesium, copper, silicon and mixtures
thereof; the combined weight percentage of the magnesium and copper
not to exceed about 0.8 percent, and the silicon weight percentage
not to exceed about 0.45
18. Method of preparing an aluminum alloy conductor having a
minimum conductivity of at least 58 percent IACS comprising the
steps of:
A. alloying from about 0.20 to about 1.60 weight percent cobalt
with about 0.30 to about 1.30 weight percent iron, the remainder
being aluminum with associated trace elements;
B. casting the alloy in a moving mold formed between a groove in
the periphery of a rotating casting wheel and a metal belt lying
adjacent said groove for a portion of its length;
C. hot rolling the cast alloy substantially immediately after
casting while the cast alloy is in substantially that condition as
cast to form a continuous rod;
said aluminum alloy conductor having the following properties as a
fully annealed wire:
Tensile strength: at least 12,000 psi
19. Method of preparing an aluminum alloy conductor in accordance
with claim 18 including the further step of drawing said conductor
through wire-drawing dies, without annealing the conductor between
drawing dies,
20. The method according to claim 18 wherein the alloying step also
includes the addition of alloying elements selected from the group
consisting of magnesium, copper, silicon and mixtures thereof, in
amounts sufficient to yield said alloy wherein the combined weight
percentage of magnesium and copper does not exceed about 0.8
percent, and the silicon
21. The method according to claim 18 wherein the alloying step
includes the addition of magnesium, copper and silicon in amounts
sufficient to yield said alloy wherein the combined weight
percentage does not exceed about 0.8 percent when the combined
weight percentage of cobalt and iron is 1.8
22. The method according to claim 18 wherein the alloying step
includes the addition of magnesium and copper in amounts sufficient
to yield said alloy wherein the combined weight percentage does not
exceed about 0.20 percent and the combined weight percentage of
cobalt and iron is about 2.90
23. The method according to claim 18 wherein the additional
alloying element added is magnesium in an amount sufficient to
yield up to about
24. The method according to claim 18 wherein the additional
alloying element added is copper in an amount sufficient to yield
up to about 0.40
25. The method according to claim 18 wherein the additional
alloying element added is silicon in an amount sufficient to yield
up to about 0.45
26. The method according to claim 18 wherein cobalt is added in an
amount sufficient to yield a weight percentage of from about 0.20
percent to about 1.0 percent cobalt and iron is added in an amount
sufficient to yield a weight percentage of from about 0.3 percent
to about 1.0 percent
27. The method according to claim 18 wherein cobalt is added in an
amount sufficient to yield a weight percentage of from about 0.30
percent to about 0.80 percent cobalt and iron is added in an amount
sufficient to yield a weight percentage of from about 0.40 percent
to about 0.70% iron.
28. The method according to claim 18 wherein cobalt, iron and misch
metal are added in amounts sufficient to yield an alloy having the
following weight percentages:
29. The method according to claim 18 wherein cobalt, iron, niobium
and tantalum are added in amounts sufficient to yield an alloy
having the following weight percentages:
30. The method according to claim 18 wherein cobalt, iron, copper
and silicon are added in amounts sufficient to yield an alloy
having the following weight percentages:
31. The method according to claim 18 wherein cobalt, iron, and
zirconium are added in an amount sufficient to yield an alloy
having the following weight percentages:
32. The method according to claim 18 wherein said alloy conductor
is formed into a wire having the following properties when measured
as a No. 10 A.W.G. fully annealed wire:
Tensile strength: 12,000 - 24,000 psi
Elongation: 12 - 30 percent
Yield strength: 8,000 - 18,000 psi.
Description
The present invention concerns an aluminum base alloy especially
suited for producing high strength light-weight electrical
conductors including wire, rod and other such articles of
manufacture. The present alloy is particularly well suited for use
as a wire, rod, cable, bus bar, tube connector, termination,
receptacle plug or electrical contact device for conducting
electricity.
Aluminum base alloys are finding wider acceptance in the
marketplace of today because of their light weight and low cost.
One area where aluminum alloys have found increasing acceptance is
in the replacement of copper in the manufacture of electrically
conductive wire. Conventional electrically conductive aluminum
alloy wire (referred to as EC) contains a substantial amount of
pure aluminum and trace amounts of impurities such as silicon,
vanadium, iron, copper, manganese, magnesium, zinc, boron, and
titanium.
Even though desirable in terms of weight and cost, aluminum alloys
have received far less than complete acceptance in the electrical
conductor marketplace. One of the chief reasons for the lack of
complete acceptance is the range of physical properties available
with conventional EC aluminum alloy conductors. If the physical
properties, such as thermal stability, tensile strength, percent
elongation, ductility and yield strength, could be improved
significantly without substantially lessening the electrical
conductivity of the finished product, a very desirable improvement
would be achieved. It is accepted, however, that addition of
alloying elements, as in other aluminum alloys, reduces
conductivity while improving the physical properties. Consequently,
only those additions of elements which improve physical properties
without substantially lessening conductivity will yield an
acceptable and useful product.
It is an object of the present invention, therefore, to provide a
new aluminum alloy electrical conductor which combines improved
physical properties with acceptable electrical conductivity. These
and other objects, features and advantages of the present invention
will be apparent from a consideration of the following detailed
description of an embodiment of the invention.
In accordance with the invention, the present aluminum base alloy
is prepared by mixing cobalt, iron and optionally other alloying
elements with aluminum in a furnace to obtain a melt having
requisite percentages of elements. It has been found that suitable
results are obtained with cobalt present in a weight percentage of
from about 0.20 percent to about 1.60 percent. Superior results are
achieved when cobalt is present in a weight percentage of from
about 0.20 percent to about 1.00 percent and particularly superior
and preferred results are obtained when cobalt is present in a
percentage by weight of from about 0.30 percent to about 0.80
percent.
Suitable results are obtained with iron present in a weight
percentage of from about 0.30 percent to about 1.30 percent.
Superior results are achieved when iron is present in a weight
percentage of from about 0.30 percent to about 1.00 percent and
particularly superior and preferred results are obtained when iron
is present in a percentage by weight of from about 0.40 percent to
about 0.70 percent.
The aluminum content of the present alloy may vary from about 97.00
percent to about 99.50 percent by weight with superior results
being obtained when the aluminum content varies between about 97.90
percent and about 99.50 percent by weight particularly superior and
preferred results are obtained when aluminum is present in a
percentage by weight of from about 98.40 percent to about 99.30
percent. Since the percentages for maximum and minimum aluminum do
not correspond with the maximums and minimums for alloying
elements, it should be apparent that suitable results are not
obtained if the maximum percentages for all alloying elements are
employed. If commercial aluminum is employed in preparing the
present melt, it is preferred that the aluminum, prior to adding to
the melt in the furnace, contain no more than 0.10 percent total of
trace impurities.
Copper and magnesium have a high solubility in aluminum at room
temperature, consequently the electrical conductivity is decreased
due to the known effect of atoms in solid solution on the
electrical conductivity of aluminum. The present alloy may contain
up to about 0.40 weight percent copper and up to about 0.40 weight
percent magnesium.
The present alloy may contain up to about 0.45 percent by weight
each of additional alloying elements, the total weight percent of
additional alloying elements not exceeding about 0.70 percent.
Superior results are obtained when the concentration of individual
optional alloying elements is about 0.30 percent by weight or less
and the total additional alloying elements not exceeding about 0.60
weight percent. Particularly superior and preferred results are
obtained when the concentration of individual optional alloying
elements is about 0.20 percent by weight or less and the total
additional alloying elements not exceeding about 0.40 weight
percent.
Additional alloying elements include the following:
ADDITIONAL ALLOYING ELEMENTS ______________________________________
Nickel Scandium Dysprosium Silicon Thorium Terbium Zirconium Tin
Erbium Cerium Molybdenum Neodymium Niobium Zinc Indium Hafnium
Tungsten Boron Lanthanum Thallium Rubidium Tantalum Bismuth
Titanium Cesium Antimony Carbon Yttrium Rhenium
______________________________________
Superior results are obtained with the following additional
alloying elements in the percentages, by weight, as shown:
PREFERRED ADDITIONAL ALLOYING ELEMENTS
______________________________________ Nickel 0.0005% to 0.45%
Silicon 0.001% to 0.45% Zirconium 0.001% to 0.45% Niobium 0.001% to
0.45% Tantalum 0.001% to 0.45% Yttrium 0.001% to 0.45% Scandium
0.001% to 0.45% Thorium 0.001% to 0.45% Rare Earth Metals 0.001% to
0.45% Carbon 0.001% to 0.45% Mixtures of two or more of the above
0.001% to 0.70 ______________________________________
Particularly superior and preferred results are obtained with the
use of silicon in a percentage range of from about 0.001 to about
0.45 percent by weight, additional alloying elements in a
percentage range of from about 0.0005 to about 0.25 percent by
weight, and nickel or magnesium as additional alloying elements.
Suitable results are obtained with magnesium or nickel in a
percentage range of from about 0.0005 to about 0.40 percent by
weight. Superior results are obtained with from about 0.025 to
about 0.30 percent by weight magnesium or nickel, silicon in a
percentage range of from about 0.001 to about 0.30 percent by
weight, and from about 0.0005 to about 0.25 percent by weight
additional alloying elements. Particularly superior and preferred
results are obtained when from about 0.03 to about 0.10 percent by
weight of magnesium or nickel is employed with from about 0.001 to
about 0.20 percent by weight silicon and from about 0.0005 to about
0.20 weight percent additional alloying elements.
Superior and preferred results are also obtained with the use of
cobalt and iron in the percentage ranges previously specified with
additional alloying elements and optionally with silicon as the
major additional alloying elements.
Suitable results are obtained with the use of silicon as the major
additional alloying element in a percentage range of from about
0.001 to about 0.45 percent by weight and from about 0.0005 to
about 0.25 weight percent additional alloying elements with
superior results being obtained with from about 0.001 to about 0.30
weight percent silicon and from about 0.0005 to about 0.25 weight
percent additional alloying elements. Particular superior and
preferred results are obtained with from about 0.001 to about 0.20
weight percent silicon and from about 0.0005 to about 0.10 weight
percent additional alloying elements.
When silicon is not the major additional alloying element suitable
results are obtained with the use of cobalt and iron in the
percentage ranges previously specified and from about 0.0005 to
about 0.70 weight percent additional alloying elements. Superior
results are obtained with from about 0.0005 to 0.60 weight percent
additional alloying elements with particular superior and preferred
results obtained with from about 0.0005 to about 0.40 weight
percent additional alloying elements.
The rare earth metals may be present either individually within the
percentage range stated or as a partial or total group, the total
percentage of the group being within the percentage range stated
previously.
It should be understood that the additional alloying elements may
be present either individually or as a group of two or more of the
elements. It should be understood, however, that if two or more of
the additional alloying elements are employed, the total
concentration of additional alloying elements should not exceed
about 0.70 percent by weight.
When the total weight percent of cobalt and iron exceeds about 1.80
percent the total weight percent of magnesium and copper should not
exceed about 0.40 percent and the total weight percent of
additional alloying elements should not exceed about 0.40 percent
in order to maintain the desired electrical conductivity and
physical properties.
If the total weight percent cobalt and iron is about 2.90 percent
the total weight percent of magnesium and copper should not exceed
about 0.20 percent and the total weight percent of additional
alloying elements should not exceed about 0.10 percent.
After preparing the melt, the aluminum alloy is preferably
continuously cast into a continuous bar by a continuous casting
machine and then substantially immediately thereafter, hot-worked
in a rolling mill to yield a continuous aluminum alloy rod.
One example of a continuous casting and rolling operation capable
of producing continuous rod as specified in this application is
contained in the following paragraphs. It should be understood that
other methods of preparation may be employed to obtain suitable
results but that preferable results are obtained with continuous
processing. Such other methods include conventional extrusion and
hydrostatic extrusion to obtain rod or wire directly, sintering an
aluminum alloy powder to obtain rod or wire directly, casting rod
or wire directly from a molten aluminum alloy, and conventional
casting of aluminum alloy billets which are subsequently hot-worked
to rod and drawn with intermediate anneals into wire.
CONTINUOUS CASTING AND ROLLING OPERATION
A continuous casting machine serves as a means for solidifying the
molten aluminum alloy metal to provide a cast bar that is conveyed
in substantially the condition in which it solidified from the
continuous casting machine to the rolling mill, which serves as a
means for hot-forming the cast bar into rod or another hot-formed
product in a manner which imparts substantial movement to the cast
bar along a plurality of angularly disposed axes.
The continuous casting machine is of conventional casting wheel
type having a casting wheel with a casting groove in its periphery
which is partially closed by an endless belt supported by the
casting wheel and an idler pulley. The casting wheel and the
endless belt cooperate to provide a mold into one end of which the
cast bar is emitted in substantially that condition in which it
solidified.
The rolling mill is of conventional type having a plurality of roll
stands arranged to hot-form the cast bar by a series of
deformations. The continuous casting machine and the rolling mill
are positioned relative to each other so that the cast bar enters
the rolling mill substantially immediately after solidification and
in substantially that condition in which it solidified. In this
condition, the cast bar is at a hot-forming temperature within the
range of temperatures for hot-forming the cast bar at the
initiation of hot-forming without heating between the casting
machine and the rolling mill. In the event that it is desired to
closely control the hot-forming temperature of the cast bar within
the conventional range of hot-forming temperatures, means for
adjusting the temperature of the cast bar may be placed between the
continuous casting machine and the rolling mill without departing
from the inventive concept disclosed herein.
The roll stands each include a plurality of rolls which engage the
cast bar. The rolls of each roll stand may be two or more in number
and arranged diametrically opposite from one another or arranged at
equally spaced positions about the axis of movement of the cast bar
through the rolling mill. The rolls of each roll stand of the
rolling mill are rotated at a predetermined speed by a power means
such as one or more electric motors and the casting wheel is
rotated at a speed generally determined by its operating
characteristics. The rolling mill serves to hot-form the cast bar
into a rod of a cross-sectional area substantially less than that
of the cast bar as it enters the rolling mill.
The peripheral surfaces of the rolls of adjacent roll stands in the
rolling mill change in configuration; that is, the cast bar is
engaged by the rolls of successive roll stands with surfaces of
varying configuration, and from different directions. This varying
surface engagement of the cast bar in the roll stands functions to
knead or shape the metal in the cast bar in such a manner that it
is worked at each roll stand and also to simultaneously reduce and
change the cross-sectional area of the cast bar into that of the
rod.
As each roll stand engages the cast bar, it is desirable that the
cast bar be received with sufficient volume per unit of time at the
roll stand for the cast bar to generally fill the space defined by
the rolls of the roll stand so that the rolls will be effective to
work the metal in the cast bar. However, it is also desirable that
the space defined by the rolls of each roll stand not be overfilled
so that the cast bar will not be forced into the gaps between the
rolls. Thus, it is desirable that the rod be fed toward each roll
stand at a volume per unit of time which is sufficient to fill, but
not over fill, the space defined by the rolls of the roll
stand.
As the cast bar is received from the continuous casting machine, it
usually has one large flat surface corresponding to the surface of
the endless band and inwardly tapered side surfaces corresponding
to the shape of the groove in the casting wheel. As the cast bar is
compressed by the rolls of the roll stands, the cast bar is
deformed so that it generally takes the cross-sectional shape
defined by the adjacent peripheries of the rolls of each roll
stand.
Thus, it will be understood that with this apparatus, cast aluminum
alloy rod of an infinite number of different lengths is prepared by
simultaneous casting of the molten aluminum alloy and hot-forming
or rolling the cast aluminum bar. The continuous rod has a minimum
electrical conductivity of 57 percent IACS and may be used in
conducting electricity or it may be drawn to wire of a smaller
cross-sectional diameter.
To produce wire of various gauge, the continuous rod produced by
the casting and rolling operation is processed in a reduction
operation. The unannealed rod (i.e., as rolled to f temper) is
cold-drawn through a series of progressively constricted dies,
without intermediate anneals, to form a continuous wire of desired
diameter. It has been found that the elimination of intermediate
anneals is preferable during the processing of the rod and improves
the physical properties of the wire. Processing with intermediate
anneals is acceptable when the requirements for physical properties
of the wire permit reduced values. The conductivity of the
hard-drawn wire is at least 58 percent IACS. If greater
conductivity or increased elongation is desired, the wire may be
annealed or partially annealed after the desired wire size is
obtained and cooled. Fully annealed wire has a conductivity of at
least 59 percent IACS. At the conclusion of the drawing operation
and optional annealing operation, it is found that the alloy wire
has the properties of improved tensile strength and yield strength
together with improved thermal stability, percent ultimate
elongation and increased ductility and fatigue resistance as
specified previously in this application. The annealing operation
may be continuous as in resistance annealing, induction annealing,
convection annealing by continuous furnaces or radiation annealing
by continuous furnaces, or, preferably, may be batch annealed in a
batch furnace. When continuously annealing, temperatures of about
450.degree.F to about 1,200.degree.F may be employed with annealing
times of about 5 minutes to about 1/10,000 of a minute. Generally,
however, continuous annealing temperatures and times may be
adjusted to meet the requirements of the particular overall
processing operation so long as the desired physical properties are
achieved. In a batch annealing operation, a temperature of
approximately 400.degree.F to about 750.degree.F is employed with
residence times of about 30 minutes to about 24 hours. As mentioned
with respect to continuous annealing, in batch annealing the times
and temperatures may be varied to suit the overall process so long
as the desired physical properties are obtained.
It has been found that the properties of a Number 10 gauge
(American wire gauge) fully annealed soft wire of the present alloy
vary between the following figures:
Tensile % Yield Conductivity Strength, psi. Elongation Strength,
psi. ______________________________________ 59%-63+% 12,000-24,000
12%-30% 8,000-18,000 ______________________________________
A more complete understanding of the invention will be obtained
from the following examples.
EXAMPLE NO. 1
Various melts are prepared by adding the required amount of
alloying elements to 1,816 grams of molten aluminum, containing
less that 0.1 percent trace element impurities, to achieve a
percentage concentration of elements as shown in the accompanying
table; the remainder being aluminum. Graphite crucibles are used
except in those cases where the alloying elements are known carbide
formers, in which cases aluminum oxide crucibles are used. The
melts are held for sufficient times and at sufficient temperatures
to allow complete solubility of the alloying elements with the base
aluminum. An argon atmosphere is provided over the melt to prevent
oxidation. Each melt is continuously cast on a continuous casting
machine and immediately hot-rolled through a rolling mill to 3/8
inch continuous rod. Wire is then drawn from the rod in both the
as-rolled condition (hard rod) and after being annealed for 5 hours
at 650.degree.F (soft rod). The final wire diameter obtained is
0.107 inches, 10 gauge AWG. Wire from each type rod is tested in
both the as-drawn condition (hard wire) and after being annealed
for 5 hours at 650.degree.F (soft wire).
The types of alloys employed and the results of the tests performed
thereon are as follows:
TABLE I
__________________________________________________________________________
Co Fe Mg Ni HR SR HW-HR HW-SR SW-HR SW-SR Properties
__________________________________________________________________________
.80 .80 .08 2.1 25.5 2.0 2.5 17.8 24.5 % Elong. 31,450 19,400
38,040 34,045 19,790 18,978 UTS 58.38 59.63 58.03 58.79 59.76 59.98
% IACS .80 .80 4.3 22.0 3.0 3.0 21.0 22.0 % Elong. 27,800 18,340
31,700 27,450 17,590 15,750 UTS 59.01 61.42 58.37 59.88 60.48 60.63
% IACS 1.0 .80 3.3 20.1 4.2 2.3 25.0 27.7 % Elong. 28,150 17,875
32,135 26,685 17,200 16,275 UTS 58.38 59.90 58.37 59.29 59.86 60.06
% IACS .80 .80 .10 1.1 14.5 3.4 2.0 20.5 24.5 % Elong. 34,395
19,650 40,360 36,700 20,280 19,240 UTS 57.56 59.38 56.80 58.07
59.02 59.33 % IACS .40 .80 .10 .40 2.8 20.0 2.0 2.5 22.9 24.5 %
Elong. 30,340 17,110 37,935 32,500 18,350 17,245 UTS 59.19 60.65
58.64 59.66 60.65 60.72 %
__________________________________________________________________________
IACS HR = Hard Rod SR = Soft Rod HW-HR = Hard Wire drawn from Hard
Rod HW-SR = Hard Wire drawn from Soft Rod SW-HR = Soft Wire drawn
from Hard Rod SW-SR = Soft Wire drawn from Soft Rod % Elong. =
Percent ultimate elongation UTS = Ultimate Tensile Strength % IACS
= Conductivity in Percentage IACS Soft wire and soft rod are the
fully annealed forms of the products.
EXAMPLE NO. 2
An additional alloy melt is prepared according to Example No. 1 so
that the composition is as follows in weight percent:
Cobalt 0.60% Iron 0.90% Magnesium 0.15% Aluminum Remainder
The melt is processed to a No. 10 gauge soft wire from hard rod.
The physical properties of the wire are as follows:
Ultimate Tensile Strength 20,040 psi Percent Ultimate Elongation
18.50% Conductivity 59.05% IACS
EXAMPLE NO. 3
An additional alloy melt is prepared according to Example No. 1 so
that the composition is as follows in weight percent:
Cobalt 0.80% Iron 0.50% Misch Metal 0.40% Aluminum Remainder
Misch metal is a commercial designation for a blend of rare earth
metals and Thorium obtained during the processing of Thorium
metal.
The melt is processed to a No. 10 gauge soft wire from hard rod.
The physical properties of the wire are as follows:
Ultimate Tensile Strength 18,500 psi Percent Ultimate Elongation
19% Conductivity 59.2% IACS
EXAMPLE NO. 4
An additional alloy melt is prepared according to Example No. 1 so
that the composition is as follows in weight percent:
Cobalt 0.80% Iron 0.40% Niobium 0.20% Tantalum 0.20% Aluminum
Remainder
The melt is processed to a No. 10 gauge soft wire from hard rod.
The physical properties of the wire are as follows:
Ultimate Tensile Strength 19,380 psi Percent Ultimate Elongation
19.5% Conductivity 59.1% IACS
EXAMPLE NO. 5
An additional alloy melt is prepared according to Example No. 1 so
that the composition is as follows in weight percent:
Cobalt 0.80% Iron 0.35% Copper 0.40% Silicon 0.30% Aluminum
Remainder
The melt is processed to a No. 10 gauge soft wire from hard rod.
The physical properties of the wire are as follows:
Ultimate Tensile Strength 17,000 psi Percent Ultimate Elongation
19.5% Conductivity 59.7% IACS
EXAMPLE NO. 6
An additional alloy melt is prepared according to Example No. 1 so
that the composition is as follows in weight percent:
Cobalt 0.80% Iron 0.45% Zirconium 0.30% Aluminum Remainder
The melt is processed to a No. 10 gauge soft wire from hard rod.
The physical properties of the wire are as follows:
Ultimate Tensile Strength 18,600 psi Percent Ultimate Elongation
18.5% Conductivity 59.3% IACS
ADDITIONAL EXAMPLES
Additional alloy melts are prepared according to Example No. 1. The
composition and the physical properties of a No. 10 gauge soft wire
from hard rod of the alloy melts are as follows:
TABLE 2
__________________________________________________________________________
Example UTS % % IACS No. Co Fe Mg in psi Elongation Conductivity
__________________________________________________________________________
1176 .8 .5 -- 17,430 24.7 60.68 1177 .8 .5 .1 17,410 24.8 60.43
1183 .8 .3 -- 17,785 26.6 61.65 1184 .8 .5 -- 17,700 28.0 61.54
1185 .6 .9 -- 18,485 23.7 60.76 1186 .8 .9 -- 17,930 26.5 59.97
1187 .4 1.1 -- 19,355 19.8 60.19 1188 .6 1.1 -- 20,400 17.5 59.87
1196 .2 1.1 -- 18,515 20.5 60.41 1197 .4 .9 -- 17,495 22.4 60.40
1198 .4 1.1 -- 18,695 21.5 60.02 1199 .6 .9 -- 18,975 20.3 60.99
1200 .2 .7 .1 17,775 22.8 60.83 1216 .8 Graphite .05 17,635 27.3
61.84 .01 1219 .8 .53 -- 17,180 29.2 61.62 1220 .8 .4 -- 17,480
29.0 61.31 1221 .8 .5 .051 18,965 26.4 61.28 1227 .8 .5 .05 18,785
17.1 60.72 1228 .8 .5 .2 17,140 27.2 60.56 1237 .7 .5 -- 17,030
24.5 61.49 1238 .8 .7 -- 17,295 26.4 60.96 1239 .6 .5 .05 17,975
22.7 61.29 1201 .6 .9 .1 20,898 20.7 59.15 1240 .8 .3 .05 17,630
23.3 61.25 1293 1.40 .49 -- 17,120 24.5 59.52 1313 .20 1.10 .12
17,400 24.2 60.01 1316 .22 .96 .15 17,425 22.0 59.92 1317 .23 1.20
.14 18,333 23.7 59.47 1321 .43 .70 .054 17,200 26.5 61.12 1322 .40
1.05 .05 17,830 22.0 60.12 1325 .40 .68 .10 17,792 25.5 60.44 1327
.38 1.10 .11 19,004 25.2 59.52 1328 .42 .35 .15 17,000 24.0 60.88
1329 .41 .50 .16 17,000 24.0 60.47 1330 .44 .70 .16 18,100 25.0
59.80 1331 .42 .91 .16 18,690 22.0 60.51 1343 .33 .95 Ni.54 20,874
16.4 49.90 1.0HF 1355 .62 1.10 .15 20,990 12.5 58.05
__________________________________________________________________________
Through testing and analysis of an alloy containing 0.80 weight
percent cobalt, 0.30 weight percent iron, and the remainder
aluminum, it has been found that the present aluminum base alloy
after cold working includes intermetallic compound precipitates.
One of the compounds is identified as cobalt aluminate (Co.sub.2
Al.sub.9) and the other is identified as iron aluminate
(FeAl.sub.3). The cobalt intermetallic compound is found to be very
stable and especially so at high temperatures. The cobalt compound
also has a low tendency to coalesce during annealing of products
formed from the alloy and the compound is generally incoherent with
the aluminum matrix. The mechanism of strengthening for this alloy
is in part due to the dispersion of the cobalt intermetallic
compound as a precipitate throughout the aluminum matrix. The
precipitate tends to pin dislocation sites which are created during
cold working of the wire formed from the alloy. Upon examination of
the cobalt intermetallic compound precipitate in a cold drawn wire,
it is found that the precipitates are oriented in the direction of
drawing. In addition, it is found that the precipitates are
rod-like or plate-like in configuration and a majority are less
than 2 microns in length and less than one-half micron in
width.
The iron aluminate intermetallic compound also contributes to the
pinning of dislocation sites during cold working of the wire. Upon
examination of the iron intermetallic compound precipitate in a
cold drawn wire, it is found that the precipitates are
substantially evenly distributed through the alloy and have a
particle size of less than 1 micron. If the wire is drawn without
any intermediate anneals, the particle size of the iron
intermetallic compounds is less than 2,000 angstroms.
A characteristic of high conductivity aluminum alloy wires which is
not indicated by the historical tests for tensile strength, percent
elongation and electrical conductivity is the possible change in
properties as a result of increases, decreases or fluctuations of
the temperature of the strands. It is apparent that the maximum
operating temperature of a strand or series of strands will be
affected by this temperature characteristic. The characteristic is
also quite significant from a manufacturing viewpoint since many
insulation processes require high temperature thermal cures.
It has been found that the aluminum alloy wire of the present
invention has a characteristic of thermal stability which exceeds
the thermal stability of other aluminum alloy wires. In order to
demonstrate this feature a group of wires is prepared for testing
decrease in tensile and yield strength in response to ageing at
established temperatures and times. The samples have compositions
and are processed as shown in the following table:
TABLE III
__________________________________________________________________________
Sample Co Fe Si Al Processing
__________________________________________________________________________
No. 1 -- 0.60 0.05 Remainder Continuous casting and immediate hot
rolling; drawing to flat mag- - net wire with no intermediate
anneals and then partially annealed No. 2 -- 0.47 0.045 Remainder
Billet casting; homogenization and rolling; drawing with
intermediate anneals to flat magnet wire and then partially
annealed. No. 3 -- 0.60 0.045 Remainder Billet casting;
homogenization and rolling; drawing with inter- mediate anneals to
form flat mag- net wire and then partially annealed. No. 4 0.80
0.60 -- Remainder Continuous casting and immediate hot rolling;
drawing to flat mag- net wire with no intermediate anneals and then
partially annealed
__________________________________________________________________________
The results of the test are reproduced in the following table:
TABLE IV
__________________________________________________________________________
160.degree.C-AGEING TEMP. 190-200.degree.C AGEING TEMP. DECREASE
DECREASE DECREASE DECREASE SAMPLE TIME IN YS IN UTS TIME IN YS IN
UTS
__________________________________________________________________________
No. 1 100 hrs. 0 0 100 hrs. 600 psi 1200 psi 500 hrs. 1,800 psi 0
670 hrs. 4,200 psi 1200 psi No. 2 100 hrs. 0 0 100 hrs. 2,700 psi
2300 psi 500 hrs. 1,800 psi 0 550 hrs. 9,300 psi 5000 psi No. 3 100
hrs. 1,400 psi 0 480 hrs. 2,800 psi 0 NO TEST No. 4 100 hrs. 0 0
500 hrs. 0 0 550 hrs. 0 0
__________________________________________________________________________
YS -- Yield Strength UTS -- Ultimate Tensile Strength
A significant aspect shown by the results of these tests is the
lack of thermal stability obtainable with several aluminum alloys.
The test sample wires identified as No. 2 and 3 show a significant
decrease in thermal stability in the yield and tensile strength
tests and alloy No. 2 has almost completely softened after a 550
hour soak period at 190-200.degree.C. On the other hand, the wire
fabricated from the present alloy demonstrates a high degree of
thermal stability by exhibiting zero decreases in yield and tensile
strength.
For the purpose of clarity, the following terminology used in this
application is explained as follows:
Aluminum alloy rod -- A solid product that is long in relation to
its cross-section. Rod normally has a cross-section of between
three inches and 0.375 inches.
Aluminum alloy wire -- A solid wrought product that is long in
relation to its cross-section, which is square or rectangular with
sharp or rounded corners or edges, or is round, a regular hexagon
or a regular octagon, and whose diameter or greatest perpendicular
distance between parallel faces is between 0.374 inches and 0.0031
inches.
While this invention has been described in detail with particular
reference to preferred embodiments thereof, it will be understood
that variations and modifications can be effected within the spirit
and scope of the invention as described hereinbefore and as defined
in the appended claims.
* * * * *