Note: Descriptions are shown in the official language in which they were submitted.
HIGH-STRENGTH, CORROSION RESISTANT ALUMINUM ALLOYS
FOR USE AS FIN STOCK AND METHODS OF MAKING THE SAME
FIELD
This disclosure relates to the fields of material science, material chemistry,
metallurgy,
aluminum alloys, aluminum fabrication, and related fields. More specifically,
the disclosure
provides novel aluminum alloys that can be used in a variety of applications,
including, for
example, as a fin stock for a heat exchanger.
BACKGROUND
Heat exchangers are widely used in various applications, including, but not
limited to,
heating and cooling systems in various industrial and chemical processes. Many
of these
configurations utilize fins in thermally conductive contact with the outside
of tubes to provide
increased surface area across which heat can be transferred between the
fluids. In addition, fins
are used to regulate flow of fluids through the heat exchanger. However,
aluminum alloy heat
exchangers have a relatively high susceptibility to corrosion. Corrosion
eventually leads to loss
of refrigerant from the tubes and failure of the heating or cooling system.
High strength,
corrosion resistant alloys are desirable for improved product performance.
However, identifying
alloy compositions and processing conditions that will provide such an alloy
that addresses these
failures has proven to be a challenge.
Heat exchanger tubes can be made from copper or an aluminum alloy and heat
exchanger
fins can be made from a different aluminum alloy (e.g., AA1100 or AA7072). The
fins can be
fitted over copper or aluminum tubes and mechanically assembled. Larger
heating, ventilation,
air conditioning and refrigeration (HVAC&R) units can require longer fins and
it is important
they have sufficient strength for downstream processing (e.g., handling and/or
forming into
coils). One method to maintain strength of the fins is to provide thicker
gauge fins; however,
this can increase cost and add weight.
SUMMARY
Covered embodiments of the invention are defined by the claims, not this
summary. This
summary is a high-level overview of various aspects of the invention and
introduces some of the
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concepts that are further described in the Detailed Description section below.
This summary is
not intended to identify key or essential features of the claimed subject
matter, nor is it intended
to be used in isolation to determine the scope of the claimed subject matter.
The subject matter
should be understood by reference to appropriate portions of the entire
specification, any or all
drawings and each claim.
Provided herein are novel aluminum alloys that exhibit high strength and
corrosion
resistance. The aluminum alloys described herein comprise about 0.7 -3.0 wt. %
Zn, about 0.15
-0.35 wt. % Si, about 0.25 -0.65 wt. % Fe, about 0.05 -0.20 wt. % Cu, about
0.75 - 1.50 wt. %
Mn, about 0.50- 1.50 wt. % Mg, up to about 0.05 wt. % Cr, up to about 0.05 wt.
% Ti, and up to
about 0.15 wt. % of impurities, with the remainder as Al. In some examples,
the aluminum alloy
comprises about 1.0 -2.5 wt. % Zn, about 0.2 -0.35 wt. % Si, about 0.35 -0.60
wt. % Fe, about
0.10 - 0.20 wt. % Cu, about 0.75 - 1.25 wt. % Mn, about 0.90- 1.30 wt. % Mg,
up to about 0.05
wt. % Cr, up to about 0.05 wt. % Ti, and up to about 0.15 wt. % of impurities,
with the
remainder as Al. In some examples, the aluminum alloy comprises about 1.5 -2.5
wt. % Zn,
about 0.17 - 0.33 wt. % Si, about 0.30 - 0.55 wt. % Fe, about 0.15 -0.20 wt. %
Cu, about 0.80 -
1.00 wt. % Mn, about 1.00- 1.25 wt. % Mg, up to about 0.05 wt. % Cr, up to
about 0.05 wt. %
Ti, and up to about 0.15 wt. % of impurities, with the remainder as Al.
Optionally, the aluminum
alloy comprises about 0.9 -2.6 wt. % Zn, about 0.2 - 0.33 wt. % Si, about 0.49
-0.6 wt. % Fe,
about 0.15 -0.19 wt. % Cu, about 0.79 -0.94 wt. % Mn, about 1.13 - 1.27 wt. %
Mg, up to
about 0.05 wt. % Cr, up to about 0.05 wt. % Ti, and up to about 0.15 wt. % of
impurities, with
the remainder as Al. Optionally, the aluminum alloy comprises about 1.4 - 1.6
wt. % Zn, about
0.2 - 0.33 wt. % Si, about 0.49 -0.6 wt. % Fe, about 0.15 -0.19 wt. % Cu,
about 0.79 - 0.94 wt.
% Mn, about 1.13 - 1.27 wt. % Mg, up to about 0.05 wt. % Cr, up to about 0.05
wt. % Ti, and up
to about 0.15 wt. % of impurities, with the remainder as Al. The alloy can be
produced by
casting (e.g., direct chill casting or continuous casting), homogenization,
hot rolling, cold rolling,
and/or annealing. The alloy can be in an H temper or an 0 temper.
The yield strength of the alloy is at least about 70 MPa. The ultimate tensile
strength of
the alloy can be at least about 170 MPa. The aluminum alloy can comprise an
electrical
conductivity above about 37% based on the international annealed copper
standard (IACS).
Optionally, the aluminum alloy comprises a corrosion potential of from about -
740 mV to -850
mV.
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Also provided herein are products comprising the aluminum alloy as described
herein.
The products can include a fin stock. Optionally, the gauge of the fin stock
is 1.0 mm or less
(e.g., 0.15 mm or less). Further provided herein are articles comprising a
tube and a fin, wherein
the fin comprises the fin stock as described herein.
Further provided herein are methods of producing a metal product. The methods
include
the steps of casting an aluminum alloy as described herein to form a cast
aluminum alloy,
homogenizing the cast aluminum alloy, hot rolling the cast aluminum alloy to
produce a rolled
product, and cold rolling the rolled product to a final gauge product.
Optionally, the methods
further include a step of annealing the final gauge product. Products (e.g.,
heat exchanger fins)
obtained according to the methods are also provided herein.
Further aspects, objects, and advantages will become apparent upon
consideration of the
detailed description of non-limiting examples that follow.
BRIEF DESCRIPTION OF THE FIGURES
Figure 1 contains digital images of exemplary alloys described herein coupled
with a
comparative alloy described herein and subjected to corrosion testing for
various time periods.
Figure 2 contains digital images of exemplary alloys described herein coupled
with a
comparative alloy described herein and subjected to corrosion testing for
various time periods.
DETAILED DESCRIPTION
Described herein are high-strength, corrosion resistant aluminum alloys and
methods of
making and processing the same. The aluminum alloys described herein exhibit
improved
mechanical strength, corrosion resistance, and/or formability. The alloys
provided herein include
a zinc constituent and can be especially useful as a sacrificial alloy (e.g.,
as fin stock material for
use in combination with copper or aluminum alloy tubes in heat exchangers).
The disclosed
alloy composition provides a material having mechanical strength as well as
sacrificial alloy
characteristics. The alloy material can be formed as fin stock and attached
mechanically to
copper or aluminum alloy tubing. The fin stock can sacrificially corrode, thus
protecting the
copper or aluminum alloy tubing from corrosion. Additionally, the aluminum
alloy fin stock
described herein has excellent mechanical strength providing thinner gauge
aluminum alloy fin
stock. The alloys can be used as fin stock in industrial applications,
including in heat
exchangers, or in other applications. In a heat exchanger, the alloys serve as
a sacrificial
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component, ensuring the protection of other components of the heat exchanger
(e.g., a tube to
which the alloy is attached).
Definitions and Descriptions:
The terms "invention," "the invention," "this invention," and "the present
invention" used
herein are intended to refer broadly to all of the subject matter of this
patent application and the
claims below. Statements containing these terms should be understood not to
limit the subject
matter described herein or to limit the meaning or scope of the patent claims
below.
In this description, reference is made to alloys identified by aluminum
industry
designations, such as "series" or "lxxx." For an understanding of the number
designation
system most commonly used in naming and identifying aluminum and its alloys,
see
"International Alloy Designations and Chemical Composition Limits for Wrought
Aluminum
and Wrought Aluminum Alloys" or "Registration Record of Aluminum Association
Alloy
Designations and Chemical Compositions Limits for Aluminum Alloys in the Form
of Castings
and Ingot," both published by The Aluminum Association.
As used herein, the meaning of "a," "an," or "the" includes singular and
plural references
unless the context clearly dictates otherwise.
As used herein, a plate generally has a thickness of greater than about 15 mm.
For
example, a plate may refer to an aluminum product having a thickness of
greater than about 15
mm, greater than about 20 mm, greater than about 25 mm, greater than about 30
mm, greater
than about 35 mm, greater than about 40 mm, greater than about 45 mm, greater
than about 50
mm, or greater than about 100 mm.
As used herein, a shate (also referred to as a sheet plate) generally has a
thickness of
from about 4 mm to about 15 mm. For example, a shate may have a thickness of
about 4 mm,
about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 10 mm, about
11 mm,
about 12 mm, about 13 mm, about 14 mm, or about 15 mm.
As used herein, a sheet generally refers to an aluminum product having a
thickness of less
than about 4 mm. For example, a sheet may have a thickness of less than about
4 mm, less than
about 3 mm, less than about 2 mm, less than about 1 mm, less than about 0.5
mm, less than about
0.3 mm, or less than about 0.1 mm.
Reference is made in this application to alloy temper or condition. For an
understanding
of the alloy temper descriptions most commonly used, see "American National
Standards
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CA 2990212 2018-01-26
(ANSI) H35 on Alloy and Temper Designation Systems." An F condition or temper
refers to an
aluminum alloy as fabricated. An 0 condition or temper refers to an aluminum
alloy after
annealing. An Hxx condition or temper, also referred to herein as an H temper,
refers to an
aluminum alloy after cold rolling with or without thermal treatment (e.g.,
annealing). Suitable H
tempers include HX1, HX2, HX3 HX4, 11X5,11X6, HX7, HX8, or HX9 tempers. For
example,
the aluminum alloy can be cold rolled only to result in a possible H19 temper.
In a further
example, the aluminum alloy can be cold rolled and annealed to result in a
possible 1123 temper.
The following aluminum alloys are described in terms of their elemental
composition in
weight percentage (wt. %) based on the total weight of the alloy. In certain
examples of each
alloy, the remainder is aluminum, with a maximum wt. % of 0.15 % for the sum
of the
impurities.
As used herein, "electrochemical potential" refers to a material's amenability
to a redox
reaction. Electrochemical potential can be employed to evaluate resistance to
corrosion of
aluminum alloys described herein. A negative value can describe a material
that is easier to
oxidize (e.g., lose electrons or increase in oxidation state) when compared to
a material with a
positive electrochemical potential. A positive value can describe a material
that is easier to
reduce (e.g., gain electrons or decrease in oxidation state) when compared to
a material with a
negative electrochemical potential. Electrochemical potential, as used herein,
is a vector
quantity expressing magnitude and direction.
As used herein, the meaning of "room temperature" can include a temperature of
from
about 15 C to about 30 C, for example about 15 C, about 16 C, about 17 C,
about 18 C,
about 19 C, about 20 C, about 21 C, about 22 C, about 23 C, about 24 C,
about 25 C,
about 26 C, about 27 C, about 28 C, about 29 C, or about 30 C. All ranges
disclosed herein
are to be understood to encompass any and all subranges subsumed therein. For
example, a
stated range of "1 to 10" should be considered to include any and all
subranges between (and
inclusive of) the minimum value of 1 and the maximum value of 10; that is, all
subranges
beginning with a minimum value of 1 or more, e.g., 1 to 6.1, and ending with a
maximum value
of 10 or less, e.g., 5.5 to 10.
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Alloy Compositions
Described below are novel aluminum alloys. In certain aspects, the alloys
exhibit high
strength, corrosion resistance, and/or high formability. The properties of the
alloys are achieved
due to the elemental compositions of the alloys as well as the methods of
processing the alloys to
produce the described sheets, plates, and shates. Specifically, increased zinc
(Zn) content
provides alloys that preferentially corrode when attached to copper or other
aluminum alloy
tubes, thus providing cathodic protection to the tubes. Surprisingly, Zn
addition has exhibited
additional solute strengthening in addition to the strengthening effect of
increased magnesium
(Mg) content. Additionally, an optimum Zn content has been observed. In some
exampl es,
additions of Zn of greater than about 2.0 wt. % are not desirable, as such
amounts can have a
detrimental effect on conductivity and self-corrosion rates. However, in some
examples, it may
be desirable to sacrifice those conductivity and corrosive properties to allow
for sufficient
cathodic protection of the tube. To this end, a maximum Zn content of up to
about 3.0 wt. % can
be used to provide the desired corrosion, conductivity, and strength
properties.
The alloys and methods described herein can be used in industrial applications
including
sacrificial parts, heat dissipation, packaging, and building materials. The
alloys described herein
can be employed as industrial fin stock for heat exchangers. The industrial
fin stock can be
provided such that it is more resistant to corrosion than currently employed
industrial fin stock
alloys (e.g., AA7072 and AA1100) and will still preferentially corrode,
protecting other metal
parts incorporated in a heat exchanger.
In some examples, the alloys can have the following elemental composition as
provided
in Table 1.
Table 1
Element Weight Percentage (wt. %)
Zn 0.7 ¨3.0
Si 0.15 ¨ 0.35
Fe 0.25 ¨ 0.65
Cu 0.05 ¨ 0.20
Mn 0.75 ¨ 1.50
Mg 0.50 ¨ 1.50
Cr 0.00 ¨ 0.10
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Ti 0.00 - 0.10
0 - 0.05 (each)
Others
0 - 0.15 (total)
Al Remainder
In some examples, the alloys can have the following elemental composition as
provided
in Table 2.
Table 2
Element Weight Percentage (wt. %)
Zn 1.0 - 2.5
Si 0.2 - 0.35
Fe 0.35 -0.60
Cu 0.10 - 0.20
Mn 0.75 - 1.25
Mg 0.90- 1.30
Cr 0.00 -0.05
Ti 0.00 -0.05
0 -0.05 (each)
Others
0 - 0.15 (total)
Al Remainder
In some examples, the alloys can have the following elemental composition as
provided
in Table 3.
Table 3
Element Weight Percentage (wt. %)
Zn 1.5 - 2.5
Si 0.17 - 0.33
Fe 0.30 -0,55
Cu 0.15 - 0.20
Mn 0.80- 1.00
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Mg 1.00 - 1.25
Cr 0.00 - 0.05
Ti 0.00 -0.05
0- 0.05 (each)
Others
0 - 0.15 (total)
Al Remainder
In some examples, the alloys can have the following elemental composilion as
provided
in Table 4.
Table 4
Element Weight Percentage (wt. %)
Zn 0.9 - 2.6
Si 0.2 - 0.33
Fe 0.49 - 0.6
Cu 0.15 - 0.19
Mn 0.79 -0.94
Mg 1.13 - 1.27
Cr 0.00 - 0.05
Ti 0.00 - 0.05
0 - 0.05 (each)
Others
0 - 0.15 (total)
Al Remainder
In some examples, the alloy includes zinc (Zn) in an amount from about 0.7 %
to about
3.0 % (e.g., from about 1.0 % to about 2.5 %, from about 1.5 % to about 3.0 %,
from about 0.9
% to about 2.6 %, or from about 1.4 % to about 1.6 %) based on the total
weight of the alloy.
For example, the alloy can include about 0.7 %, about 0.71 %, about 0.72 %,
about 0.73 %,
about 0.74 %, about 0.75 %, about 0.76 %, about 0.77 %, about 0.78 %, about
0.79 To, about 0.8
%, about 0.81 %, about 0.82 %, about 0.83 %, about 0.84 %, about 0.85 %, about
0.86 %, about
0.87 %, about 0.88 %, about 0.89 %, about 0.9 %, about 0.91 %, about 0.92 %,
about 0.93 %,
about 0.94 %, about 0.95 %, about 0.96 %, about 0.97 %, about 0.98 %, about
0.99 %, about 1.0
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CA 2990212 2018-01-26
%, about 1.01 %, about 1.02 %, about 1.03 %, about 1.04 %, about 1.05 %, about
1.06 %, about
1.07 %, about 1.08 %, about 1.09 %, about 1.1 %, about 1.11 %, about 1.12 %,
about 1.13 %,
about 1.14 %, about 1.15 %, about 1.16 %, about 1.17 %, about 1.18 %, about
1.19 %, about 1.2
%, about 1.21 %, about 1.22 %, about 1.23 %, about 1.24 %, about 1.25 %, about
1.26 %, about
1.27 %, about 1.28 %, about 1.29 %, about 1.3 %, about 1.31 %, about 1.32 %,
about 1.33 %,
about 1.34 %, about 1.35 %, about 1.36 %, about 1.37 %, about 1.38 %, about
1.39 %, about 1.4
%, about 1.41 %, about 1.42 %, about 1.43 %, about 1.44 %, about 1.45 %, about
1.46 %, about
1.47 %, about 1.48 %, about 1.49 %, about 1.5 %, about 1.51 %, about 1.52 %,
about 1.53 %,
about 1.54 %, about 1.55 %, about 1.56 %, about 1.57 %, about 1.58 %, about
1.59 %, about 1.6
%, about 1.61 %, about 1.62 %, about 1.63 %, about 1.64 %, about 1.65 %, about
1.66 %, about
1.67 %, about 1.68 %, about 1.69 %, about 1.7 %, about 1.71 %, about 1.72 %,
about 1.73 %,
about 1.74 %, about 1.75 %, about 1.76 %, about 1.77 %, about 1.78 %, about
1.79 %, about 1.8
%, about 1.81 %, about 1.82 %, about 1.83 %, about 1.84 %, about 1.85 %, about
1.86 %, about
1.87 %, about 1.88 %, about 1.89 %, about 1.9 %, about 1.91 %, about 1.92 %,
about 1.93 %,
about 1.94 %, about 1.95 %, about 1.96 %, about 1.97 %, about 1.98 %, about
1.99 %, about 2.0
%, about 2.01 %, about 2.02 %, about 2.03 7o, about 2.04 %, about 2.05 %,
about 2.06 %, about
2.07 %, about 2.08 %, about 2.09 %, about 2.1 %, about 2.11 %, about 2.12 %,
about 2.13 %,
about 2.14 %, about 2.15 %, about 2.16 %, about 2.17 %, about 2.18 %, about
2.19 %, about 2.2
%, about 2.21 %, about 2.22 %, about 2.23 %, about 2.24 %, about 2.25 %, about
2.26 %, about
2.27 %, about 2.28 %, about 2.29 %, about 2.3 %, about 2.31 %, about 2.32 %,
about 2.33 %,
about 2.34 %, about 2.35 %, about 2.36 %, about 2.37 %, about 2.38 %, about
2.39 %, about 2.4
%, about 2.41 %, about 2.42 %, about 2.43 %, about 2.44 %, about 2.45 %, about
2.46 %, about
2.47 %, about 2.48 %, about 2.49 %, about 2.5 %, 2.51 %, about 2.52 %, about
2.53 %, about
2.54 %, about 2.55 %, about 2.56 %, about 2.57 %, about 2.58 %, about 2.59 %,
about 2.6 %,
about 2.61 %, about 2.62 %, about 2.63 %, about 2.64 %, about 2.65 %, about
2.66 %, about
2.67 %, about 2.68 %, about 2.69 %, about 2.7 %, about 2.71 %, about 2.72 %,
about 2.73%,
about 2.74 %, about 2.75 %, about 2.76 %, about 2.77 %, about 2.78 %, about
2.79 %, about 2.8
%, about 2.81 %, about 2.82 %, about 2.83 %, about 2.84 %, about 2.85 %, about
2.86 %, about
2.87 %, about 2.88 %, about 2.89 %, about 2.9 %, about 2.91 %, about 2.92 %,
about 2.93 %,
about 2.94 %, about 2.95 %, about 2.96 %, about 2.97 %, about 2.98 %, about
2.99 %, or about
3.0 % Zn. All percentages are expressed in wt. %. The zinc content can improve
the corrosion
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CA 2990212 2018-01-26
resistance of the aluminum alloys described herein. Specifically, when zinc is
incorporated at a
level as described herein, such as from 1.0 % to 2.6 %, the alloys exhibit
enhanced corrosion
resistance as compared to fin stock typically used in industrial processes
(e.g., lxxx series and
7xxx series alloys). In some further examples, Zn can decrease resistance to
corrosion when
incorporated at weight percentages exceeding those described herein. In still
further examples,
Zn can be incorporated in an aluminum alloy in an optimal amount, as described
herein, to
provide an alloy suitable for use as an industrial fin. For example, at Zn
levels higher than those
described herein, the alloys for use as fins can corrode more rapidly than for
fins containing the
described amount of Zn, resulting in perforations in the fin. As a result, the
mechanical integrity
and thermal performance of the heat exchanger can be compromised, thus
affecting the service
life of the heat exchanger.
In some examples, the disclosed alloy includes silicon (Si) in an amount from
about 0.15
% to about 0.35 % (e.g., from about 0.20 % to about 0.35 %, from about 0.17 %
to about 0.33 %,
or from about 0.20 % to about 0.33 %) based on the total weight of the alloy.
Fr example, the
alloy can include about 0.15 %, about 0.16 %, about 0.17 %, about 0.18 %,
about 0.19 %, about
0.2 %, about 0.21 %, about 0.22 %, about 0.23 %, about 0.24 %, about 0.25 %,
about 0.26 %,
about 0.27 %, about 0.28 %, about 0.29 %, about 0.30 %, about 0.31 %, about
0.32 %, about
0.33 %, about 0.34 %, or about 0.35 % Si. All percentages are expressed in wt.
%.
In some examples, the alloy also includes iron (Fe) in an amount from about
0.25 % to
about 0.65 % (e.g., from 0.35 % to about 0.60 %, from 0.30 % to 0.55 %, or
from 0.49 % to 0.6
%) based on the total weight of the alloy. For example, the alloy can include
about 0.25 %,
about 0.26 %, about 0.27 %, about 0.28 %, about 0.29 %, about 0.3 %, about
0.31 %, about 0.32
%, about 0.33 %, about 0.34 %, about 0.35 %, about 0.36 %, about 0.37 %, about
0.38 %, about
0.39 %, about 0.4 %, about 0.41 %, about 0.42 %, about 0.43 %, about 0.44 %,
about 0.45 %,
about 0.46 %, about 0.47 %, about 0.48 %, about 0.49 %, about 0.5 %, about
0.51 %, about 0.52
%, about 0.53 %, about 0.54 %, about 0.55 %, about 0.56 %, about 0.57 %, about
0.58 %, about
0.59 %, about 0.6 %, about 0.61 %, about 0.62 %, about 0.63 %, about 0.64 %,
or about 0.65 %
Fe. All percentages are expressed in wt. %.
In some examples, the disclosed alloy includes copper (Cu) in an amount from
about 0.05
% to about 0.20 % (e.g., from about 0.10 % to about 0.20 %, from about 0.15 %
to about 0.20 %,
or from about 0.15 % to about 0.19%) based on the total weight of the alloy.
For example, the
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CA 2990212 2018-01-26
alloy can include about 0.05 %, about 0.06 %, about 0.07 %, about 0.08 %,
about 0.09 %, about
0.1 %, about 0.11 %, about 0.12 %, about 0.13 %, about 0.14 %, about 0.15 %,
about 0.16 %,
about 0.17 %, about 0.18 %, about 0.19 %, or about 0.2 % Cu. All percentages
are expressed in
wt. %.
In some examples, the alloy can include manganese (Mn) in an amount from about
0.75
% to about 1.5 % (e.g., from about 0.75 % to about 1.25 %, from about 0.80 %
to about 1.00 %,
or from about 0.79 % to about 0.94 %) based on the total weight of the alloy.
For example, the
alloy can include about 0.75 %, about 0.76 %, about 0.77 %, about 0.78 %,
about 0.79 %, about
0.8 %, about 0.81 %, about 0.82 %, about 0.83 %, about 0.84 %, about 0.85 %,
about 0.86 %,
about 0.87 %, about 0.88 %, about 0.89 %, about 0.9 %, about 0.91 %, about
0.92 %, about 0.93
%, about 0.94 %, about 0.95 %, about 0.96 %, about 0.97 %, about 0.98 %, about
0.99 %, about
1.0 %, about 1.01 %, about 1.02 %, about 1.03 %, about 1.04 %, about 1.05 %,
about 1.06 %,
about 1.07 %, about 1.08%, about 1.09 %, about 1.1 %, about 1.11 %, about
1.12%, about 1.13
%, about 1.14%, about 1.15 %, about 1.16%, about 1.17 %, about !..18 %, about
1.19 %, about
1.2 %, about 1.21 %, about 1.22 %, about 1.23 %, about 1.24 %, about 1.25 %,
about 1.26 %,
about 1.27 %, about 1.28 %, about 1.29 %, about 1.3 %, about 1.31 %, about
1.32 %, about 1.33
%, about 1.34 %, about 1.35 %, about 1.36 %, about 1.37 %, about 1.38 %, about
1.39 %, about
1.4 %, about 1.41 %, about 1.42 %, about 1.43 %, about 1.44 %, about 1.45 %,
about 1.46 %,
about 1.47 %, about 1.48 %, about 1.49 %, or 1.5 % Mn. All percentages are
expressed in wt. %.
In some examples, the alloy can include magnesium (Mg) in an amount from about
0.50
% to about 1.50 % (e.g., from about 0.90 % to about 1.30 %, from about 1.00 %
to about 1.25 %,
or from about 1.13 % to about 1.27 %) based on the total weight of the alloy.
For example, the
alloy can include about 0.5 %, about 0.51 %, about 0.52 %, about 0.53 %, about
0.54 %, about
0.55 %, about 0.56 %, about 0.57 %, about 0.58 %, about 0.59 %, about 0.6 %,
about 0.61 %,
about 0.62 %, about 0.63 %, about 0.64 %, about 0.65 %, about 0.66 %, about
0.67 %, about
0.68 %, about 0.69 %, about 0.7 %, about 0.71 %, about 0.72 %, about 0.73 %,
about 0.74 %,
about 0.75 %, about 0.76 %, about 0.77 %, about 0.78 %, about 0.79 %, about
0.8 %, about 0.81
%, about 0.82 %, about 0.83 %, about 0.84 %, about 0.85 %, about 0.86 %, about
0.87 %, about
0.88 %, about 0.89 %, about 0.9 %, about 0.91 %, about 0.92 %, about 0.93 %,
about 0.94 %,
about 0.95 %, about 0.96 %, about 0.97 %, about 0.98 %, about 0.99 %, about
1.0 %, about 1.01
%, about 1.02 %, about 1.03 %, about 1.04 %, about 1.05 %, about 1.06 %, about
1.07 %, about
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1.08 %, about 1.09 %, about 1.1 %, about 1.11 %, about 1.12 %, about 1.13 %,
about 1.14 %,
about 1.15 %, about 1.16 %, about 1.17 %, about 1.18 %, about 1.19 %, about
1.2 %, about 1.21
%, about 1.22 %, about 1.23 %, about 1.24 %, about 1.25 %, about 1.26 %, about
1.27 %, about
1.28 %, about 1.29 %, about 1.3 %, about 1.31 %, about 1.32 %, about 1.33 %,
about 1.34 %,
about 1.35 %, about 1.36 %, about 1.37 %, about 1.38 %, about 1.39 %, about
1.4 %, about 1.41
%, about 1.42 %, about 1.43 %, about 1.44 %, about 1.45 %, about 1.46 %, about
1.47 %, about
1.48 %, about 1.49 %, or 1.5 % Mg. All percentages are expressed in wt. %.
In some examples, the alloy includes chromium (Cr) in an amount up to about
0.10 %
(e.g., from 0 % to about 0.05 %, from about 0.001 % to about 0.04 %, or from
about 0.01 % to
about 0.03 %) based on the total weight of the alloy. For example, the alloy
can include about
0.001 %, about 0.002 %, about 0.003 %, about 0.004 %, about 0.005 %, about
0.006 %, about
0.007 %, about 0.008 %, about 0.009 %, about 0.01 %, about 0.02 %, about 0.03
%, about 0.04
%, about 0.05 %, about 0.06 %, about 0.07 %, about 0.08 %, about 0.09 %, or
about 0.1 % Cr.
In some cases, Cr is not present in the alloy (i.e., 0 %). AU percentages are
expressed in wt. %.
In some examples, the alloy includes titanium (Ti) in an amount up to about
0.10 % (e.g.,
from 0 % to about 0.05 %, from about 0.001 % to about 0.04 %, or from about
0.01 % to about
0.03 %) based on the total weight of the alloy. For example, the alloy can
include about 0.001
%, about 0.002 %, about 0.003 %, about 0.004 %, about 0.005 %, about 0.006 %,
about 0.007 %,
about 0.008 %, about 0.009 %, about 0.01 %, about 0.02 %, about 0.03 %, about
0.04 %, about
0.05 %, about 0.06 %, about 0.07 %, about 0.08 %, about 0.09 %, or about 0.1 %
Ti. In some
cases, Ti is not present in the alloy (i.e., 0 %). All percentages are
expressed in wt. %.
Optionally, the alloy compositions can further include other minor elements,
sometimes
referred to as impurities, in amounts of about 0.05 % or below, 0.04 % or
below, 0.03 % or
below, 0.02 % or below, or 0.01 % or below each. These impurities may include,
but arc not
limited to, Ga, V, Ni, Sc, Ag, B, Bi, Zr, Li, Pb, Sn, Ca, Hf, Sr, or
combinations thereof.
Accordingly, Ga, V, Ni, Sc, Ag, B, Bi, Zr, Li, Pb, Sn, Ca, Hf, or Sr may be
present in an alloy in
amounts of 0.05 % or below, 0.04 % or below, 0.03 % or below, 0.02 % or below,
or 0.01 % or
below. In certain aspects, the sum of all impurities does not exceed 0.15 %
(e.g., 0.1 %). All
percentages are expressed in wt. %. In certain aspects, the remaining
percentage of the alloy is
aluminum.
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Optionally, exemplary aluminum alloys as described herein can include about
0.9 - 2.6 %
Zn (e.g., about 1.4 - 1.6 % Zn), about 0.2 - 0.33 % Si, about 0.49- 0.6 % Fe,
about 0.15 -0.19
% Cu, about 0.79 -0.94 % Mn, about 1.13 -1.27 % Mg, up to about 0.05 % Cr, up
to about 0.05
% Ti, and up to about 0.15 % of impurities, with the remainder as Al. For
example, an
exemplary alloy includes 1.53 % Zn, 0.3 % Si, 0.51 % Fe, 0.17 % Cu, 0.87 % Mn,
1.21 % Mg,
0.001 % Cr, 0.016 % Ti, and up to 0.15 % total impurities, with the remainder
as Al. In some
examples, an exemplary alloy includes 1.00 % Zn, 0.29 % Si, 0.51 % Fe, 0.16 %
Cu, 0.86 % Mn,
1.2 % Mg, 0.001 % Cr, 0.011 % Ti, and up to 0.15 % total impurities, with the
remainder as Al.
In some examples, an exemplary alloy includes 2.04 % Zn, 0.29 % Si, 0.51 % Fe,
0.17 % Cu,
0.87 % Mn, 1.21 % Mg, 0.001 % Cr, 0.015 % Ti, and up to 0.15 % total
impurities, with the
remainder as Al. In some examples, an exemplary alloy includes 2.54 % Zn, 0.29
% Si, 0.51 %
Fe, 0.17 % Cu, 0.88 % Mn, 1.23 % Mg, 0.001 % Cr, 0.012 % Ti, and up to 0.15 %
total
impurities, with the remainder as Al.
Alloy Properties
The mechanical properties of the aluminum alloy can be controlled by various
processing
conditions depending on the desired use. The alloy can be produced (or
provided) in an H
temper (e.g., 1-1X1, HX2, HX3 HX4, HX5, HX6, HX7, HX8, or HX9 tempers). As one
example, the alloy can be produced (or provided) in the H19 temper. H19 temper
refers to
products that are cold rolled. As another example, the alloy can be produced
(or provided) in the
H23 temper. H23 temper refers to products that are cold rolled and partially
annealed. As a
further example, the alloy can be produced (or provided) in the 0 temper. 0
temper refers to
products that are cold rolled and fully annealed.
In some non-limiting examples, the disclosed alloys have high strength in the
H tempers
(e.g., 1119 temper and 1-123 temper) and high formability (i.e., bendability)
in the 0 temper. In
some non-limiting examples, the disclosed alloys have good corrosion
resistance in the 11
tempers (e.g., H19 temper and H23 temper), and 0 temper compared to
conventional 7xxx and
1 xxx series aluminum alloys employed as industrial fin stock.
In certain aspects, the aluminum alloys can have a yield strength (YS) of at
least about 70
MPa. In non-limiting examples, the yield strength is at least about 70 MPa, at
least about 80
MPa, at least about 90 MPa, at least about 100 MPa, at least about 110 MPa, at
least about 120
MPa, at least about 130 MPa, at least about 140 MPa, at least about 150 MPa,
at least about 160
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MPa, at least about 170 MPa, at least about 180 MPa, at least about 190 MPa,
at least about 200
MPa, at least about 210 MPa, at least about 220 MPa, at least about 230 MPa,
at least about 240
MPa, at least about 250 MPa, at least about 260 MPa, at least about 270 MPa,
at least about 280
MPa, at least about 290 MPa, at least about 300 MPa, at least about 310 MPa,
at least about 320
MPa, at least about 330 MPa, at least about 340 MPa, at least about 350 MPa,
or anywhere in
between. In some cases, the yield strength is from about 70 MPa to about 350
MPa. For
example, the yield strength can be from about 80 MPa to about 340 MPa, from
about 90 MPa to
about 320 MPa, from about 100 MPa to about 300 MPa, from about 180 MPa to
about 300 MPa,
or from about 200 MPa to about 300 MPa.
The yield strength will vary based on the tempers of the alloys. In some
examples, the
alloys described herein provided in an 0 temper can have a yield strength of
from at least about
70 MPa to about 200 MPa. In non-limiting examples, the yield strength of the
alloys in 0
temper is at least about 70 MPa, at least about 80 MPa, at least about 90 MPa,
at least about 100
MPa, at least about 110 MPa, at lea ;t about 120 MPa, at least about 130 MPa,
at least about 140
MPa, at least about 150 MPa, at least about 160 MPa, at least about 170 MPa,
at least about 180
MPa, at least about 190 MPa, at least about 200 MPa, or anywhere in between.
In some further examples, the alloys described herein in an H temper can have
a yield
strength of at least about 200 MPa, at least about 210 MPa, at least about 220
MPa, at least about
230 MPa, at least about 240 MPa, at least about 250 MPa, at least about 260
MPa, at least about
270 MPa, at least about 280 MPa, at least about 290 MPa, at least about 300
MPa, at least about
310 MPa, at least about 320 MPa, at least about 330 MPa, at least about 340
MPa, at least about
350 MPa, or anywhere in between.
In certain aspects, the aluminum alloys can have an ultimate tensile strength
(UTS) of at
least about 170 MPa. In non-limiting examples, the UTS is at least about 170
MPa, at least
about 180 MPa, at least about 190 MPa, at least about 200 MPa, at least about
210 MPa, at least
about 220 MPa, at least about 230 MPa, at least about 240 MPa, at least about
250 MPa, at least
about 260 MPa, at least about 270 MPa, at least about 280 MPa, at least about
290 MPa, at least
about 300 MPa, at least about 310 MPa, at least about 320 MPa, at least about
330 MPa, at least
about 340 MPa, at least about 350 MPa, or anywhere in between. In some cases,
the UTS is
from about 200 MPa to about 320 MPa. For example, the UTS can be from about
200 MPa to
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about 320 MPa, from about 190 MPa to about 290 MPa, from about 300 MPa to
about 350 MPa,
from about 180 MPa to about 340 MPa, or from about 175 MPa to about 325 MPa.
In some examples, the alloys described herein provided in an 0 temper can have
an UTS
of from at least about 170 MPa to about 250 MPa. In non-limiting examples, the
UTS of the
alloys in 0 temper is at least about 170 MPa, at least about 180 MPa, at least
about 190 MPa, at
least about 200 MPa, at least about 210 MPa, at least about 220 MPa, at least
about 230 MPa, at
least about 240 MPa, at least about 250 MPa, or anywhere in between.
In some further examples, the alloys described herein in an H temper can have
an UTS of
at least about 200 MPa, at least about 210 MPa, at least about 220 MPa, at
least about 230 MPa,
at least about 240 MPa, at least about 250 MPa, at least about 260 MPa, at
least about 270 MPa,
at least about 280 MPa, at least about 290 MPa, at least about 300 MPa, at
least about 310 MPa,
at least about 320 MPa, at least about 330 MPa, at least about 340 MPa, at
least about 350 MPa,
or anywhere in between.
In certain aspects, the alloy encompasses any yield strength that has
sufficient
formability to meet an elongation of about 9.75 % or greater in the 0 temper
(e.g., about 10.0 %
or greater). In certain examples, the elongation can be about 9.75 % or
greater, about 10.0 % or
greater, about 10.25 % or greater, about 10.5 % or greater, about 10.75 % or
greater, about 11.0
% or greater, about 11.25 % or greater, about 11.5 % or greater, about 11.75 %
or greater, about
12.0 % or greater, about 12.25 % or greater, about 12.5 % or greater, about
12.75 % or greater,
about 13.0 % or greater, about 13.25 % or greater, about 13.5 % or greater,
about 13.75 % or
greater, about 14.0 % or greater, about 14.25 % or greater, about 14.5 % or
greater, about 14.75
% or greater, about 15.0 % or greater, about 15.25 % or greater, about 15.5 %
or greater, about
15.75 % or greater, about 16.0 % or greater, about 16.25 % or greater, about
16.5 % or greater,
or anywhere in between.
In certain aspects, the alloy can have a corrosion resistance that provides a
negative
corrosion potential or electrochemical potential (Ecorr) of about -700 mV or
less when tested
according to the ASTM G69 standard. In certain cases, an open corrosion
potential value vs.
Standard Calomel Electrode (SCE) can be about -700 mV or less, about -710 mV
or less, about -
720 mV or less, about -730 mV or less, about -740 mV or less, about -750 mV or
less, about -
760 mV or less, about -770 mV or less, about -780 mV or less, about -790 mV or
less, about -
800 mV or less, about -810 mV or less, about -820 mV or less, about -830 mV or
less, about -
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840 mV or less, about -850 mV or less, or anywhere in between. For example,
the aluminum
alloy can have an open corrosion potential of from about -740 mV to about -850
mV (e.g., from
about -750 mV to about -840 mV or from about -770 mV to about -830 mV).
In some examples, the alloy can have an average conductivity value of above
about 36
% based on the international annealed copper standard (IACS) (e.g., from about
37 % IACS to
about 44 % IACS). For example, the alloy can have an average conductivity
value of about
37%, about 38%, about 39%, about 40%, about 41%, about 42%, about 43%, about
44 %, or
anywhere in between. All values in % IACS.
Methods of Preparing and Processing
In certain aspects, the disclosed alloy composition is a product of a
disclosed method.
Without intending to limit the disclosure, aluminum alloy properties are
partially determined by
the formation of microstructures during the alloy's preparation. In certain
aspects, the method of
preparation for an alloy composition may influence or even determine whether
the alloy will
have properties adequate for a desired application.
Casting
The alloy described herein can be cast using a casting method as known to
those of skill
in the art. For example, the casting process can include a Direct Chill (DC)
casting process. The
DC casting process is performed according to standards commonly used in the
aluminum
industry as known to one of skill in the art. The DC process can provide an
ingot. Optionally,
the ingot can be scalped before downstream processing. Optionally, the casting
process can
include a continuous casting (CC) process.
The cast aluminum alloy can then be subjected to further processing steps. For
example,
the processing methods as described herein can include the steps of
homogenization, hot rolling,
cold rolling, and/or annealing.
Homogenization
The homogenization step can include heating a cast aluminum alloy as described
herein
to attain a homogenization temperature of about, or at least about, 570 C
(e.g., at least about 570
C, at least about 580 C, at least about 590 C, at least about 600 C, at
least about 610 C, or
anywhere in between). For example, the cast aluminum alloy can be heated to a
temperature of
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from about 570 C to about 620 C, from about 575 C to about 615 C, from
about 585 C to
about 610 C, or from about 590 C to about 605 C. In some cases, the heating
rate to the
homogenization temperature can be about 100 C/hour or less, about 75 C/hour
or less, about 50
C/hour or less, about 40 C/hour or less, about 30 C/hour or less, about 25
C/hour or less,
about 20 C/hour or less, about 15 C/hour or less, or about 10 C/hour or
less. In other cases,
the heating rate to the homogenization temperature can be from about 10 C/min
to about 100
C/min (e.g., about 10 C/min to about 90 C/min, about 10 C/min to about 70
C/min, about 10
C/min to about 60 C/min, from about 20 C/min to about 90 C/min, from about
30 C/min to
about 80 C/min, from about 40 C/min to about 70 C/min, or from about 50
C/min to about 60
C/min).
The cast aluminum alloy is then allowed to soak (i.e., held at the indicated
temperature)
for a period of time. According to one non-limiting example, the cast aluminum
alloy is allowed
to soak for up to about 5 hours (e.g., from about 10 minutes to about 5 hours,
inclusively). For
example, the cast aluminum alloy can be soaked at a temperature of at least
570 C for 10
minutes, 20 minutes, 30 minutes, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours,
or anywhere in
between.
The cast aluminum alloy can be cooled from the first temperature to a second
temperature
that is lower than the first temperature. In some examples, the second
temperature is greater than
about 555 C (e.g., greater than about 560 C, greater than about 565 C,
greater than about 570
C, or greater than about 575 C). For example, the cast aluminum alloy can be
cooled to a
second temperature of from about 555 C to about 590 C, from about 560 C to
about 575 C,
from about 565 C to about 580 C, from about 570 C to about 585 C, from
about 565 C to
about 570 C, from about 570 C to about 590 C, or from about 575 C to about
585 C. The
cooling rate to the second temperature can be from about 10 C/min to about
100 C/min (e.g.,
from about 20 C/min to about 90 C/min, from about 30 C/min to about 80
C/min, from about
10 C/min to about 90 C/min, from about 10 C/min to about 70 C/min, from
about 10 C/min
to about 60 C/min, from about 40 C/min to about 70 C/min, or from about 50
C/min to about
60 C/min).
The cast aluminum alloy can then be allowed to soak at the second temperature
for a
period of time. In certain cases, the ingot is allowed to soak for up to about
5 hours (e.g., from
10 minutes to 5 hours, inclusively). For example, the ingot can be soaked at a
temperature of
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from about 560 C to about 590 C for 10 minutes, 20 minutes, 30 minutes, 1
hour, 2 hours, 3
hours, 4 hours, 5 hours, or anywhere in between.
Hot Rolling
Following the homogenization step, a hot rolling step can be performed. In
certain cases,
the cast aluminum alloys are hot-rolled with a hot mill entry temperature
range of about 560 'V
to about 600 C. For example, the entry temperature can be about 560 C, about
565 C, about
570 C, about 575 C, about 580 C, about 585 C, about 590 C, about 595 C,
or about 600 C.
In certain cases, the hot roll exit temperature can range from about 290 C to
about 350 C (e.g.,
from about 310 C to about 340 C). For example, the hot roll exit temperature
can be about 290
C, about 295 C, about 300 C, about 305 C, about 310 C, about 315 C, about
320 C, about
325 C, about 330 C, about 335 C, about 340 C, about 345 C, about 350 C,
or anywhere in
between.
In certain cases, the cast aluminum alloy can be hot rolled to an about 2 mm
to about 15
mm thick gauge (e.g., from about 2.5 mm to about 12 mm thick gauge). For
example, the cast
aluminum alloy can be hot rolled to an about 2 mm thick gauge, about 2.5 mm
thick gauge,
about 3 mm thick gauge, about 3.5 mm thick gauge, about 4 mm thick gauge,
about 5 mm thick
gauge, about 6 mm thick gauge, about 7 mm thick gauge, about 8 mm thick gauge,
about 9 mm
thick gauge, about 10 mm thick gauge, about 11 mm thick gauge, about 12 mm
thick gauge,
about 13 mm thick gauge, about 14 mm thick gauge, or about 15 mm thick gauge.
In certain
cases, the cast aluminum alloy can be hot rolled to a gauge greater than 15 mm
(i.e., a plate). In
other cases, the cast aluminum alloy can be hot rolled to a gauge less than 4
mm (i.e., a sheet).
Cold Rolling
A cold rolling step can be performed following the hot rolling step. In
certain aspects,
the rolled product from the hot rolling step can be cold rolled to a sheet
(e.g., below
approximately 4.0 mm). In certain aspects, the rolled product is cold rolled
to a thickness of
about 0.4 mm to about 1.0 mm, about 1.0 mm to about 3.0 mm, or about 3.0 mm to
less than
about 4.0 mm. In certain aspects, the alloy is cold rolled to about 3.5 mm or
less, about 3 mm or
less, about 2.5 mm or less, about 2 mm or less, about 1.5 mm or less, about 1
mm or less, about
0.5 mm or less, about 0.4 mm or less, about 0.3 mm or less, about 0.2 mm or
less, or about 0.1
mm or less. For example, the rolled product can be cold rolled to about 0.1
mm, about 0.2 mm,
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CA 2990212 2018-01-26
about 0.3 mm, about 0.4 mm, about 0.5 mm, about 0.6 mm, about 0.7 mm, about
0.8 mm, about
0.9 mm, about 1.0 mm, about 1.1 mm, about 1.2 mm, about 1.3 mm, about 1.4 mm,
about 1.5
mm, about 1.6 mm, about 1.7 mm, about 1.8 mm, about 1.9 mm, about 2.0 mm,
about 2.1 mm,
about 2.2 mm, about 2.3 mm, about 2.4 mm, about 2.5 mm, about 2.6 mm, about
2.7 mm, about
2.8 mm, about 2.9 mm, about 3.0 mm, about 3.1 mm, about 3.2 mm, about 3.3 mm,
about 3.4
mm, about 3.5 mm, about 3.6 mm, about 3.7 mm, about 3.8 mm, about 3.9 mm,
about 4.0 mm,
or anywhere in between.
In one case, the method for processing the aluminum alloys as described herein
can
include the following steps. A homogenization step can be performed by heating
a cast
aluminum alloy as described herein to attain a homogenization temperature of
about 590 C over
a time period of about 12 hours, wherein the cast aluminum alloys are allowed
to soak at a
temperature of about 590 C for about 2 hours. The cast aluminum alloys can
then be cooled to
about 580 C and allowed to soak for about 2 hours at 580 C. The cast
aluminum alloys can
then be hot rolled to a gauge of about 2.5 mm thick. The cast aluminum alloys
can then be cold
rolled to a gauge of less than about 1.0 mm thick (e.g., about 1.0 mm or less
or about 0.15 mm or
less), providing an aluminum alloy sheet.
Annealing
Optionally, the aluminum alloy sheet can be annealed by heating the sheet from
room
temperature to an annealing temperature of from about 200 C to about 400 C
(e.g., from about
210 C to about 375 C, from about 220 C to about 350 C, from about 225 C
to about 345 C,
or from about 250 C to about 320 C). In some cases, the heating rate to the
annealing
temperature can be about 100 C/hour or less, about 75 C/hour or less, about
50 C/hour or less,
about 40 C/hour or less, about 30 C/hour or less, about 25 C/hour or less,
about 20 C/hour or
less, about 15 C/hour or less, or about 10 C/hour or less. The sheet can
soak at the temperature
for a period of time. In certain aspects, the sheet is allowed to soak for up
to approximately 6
hours (e.g., from about 10 seconds to about 6 hours, inclusively). For
example, the sheet can be
soaked at the temperature of from about 230 C to about 370 C for about 20
seconds, about 25
seconds, about 30 seconds, about 35 seconds, about 40 seconds, about 45
seconds, about 50
seconds, about 55 seconds, about 60 seconds, about 65 seconds, about 70
seconds, about 75
seconds, about 80 seconds, about 85 seconds, about 90 seconds, about 95
seconds, about 100
seconds, about 105 seconds, about 110 seconds, about 115 seconds, about 120
seconds, about
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125 seconds, about 130 seconds, about 135 seconds, about 140 seconds, about
145 seconds,
about 150 seconds, about 5 minutes, about 10 minutes, about 15 minutes, about
20 minutes,
about 25 minutes, about 30 minutes, about 35 minutes, about 40 minutes, about
45 minutes,
about 50 minutes, about 55 minutes, about 60 minutes, about 65 minutes, about
70 minutes,
about 75 minutes, about 80 minutes, about 85 minutes, about 90 minutes, about
95 minutes,
about 100 minutes, about 105 minutes, about 110 minutes, about 115 minutes,
about 120
minutes, about 2.5 hours, about 3 hours, about 3.5 hours, about 4 hours, about
4.5 hours, about 5
hours, about 5.5 hours, about 6 hours, or anywhere in between. In some
examples, the sheet is
not annealed.
In some examples, the sheet is heated to an annealing temperature of about 200
C to
about 400 C at a constant rate of about 40 C/hour to about 50 C/hour. In
some aspects, the
sheet is allowed to soak at the annealing temperature for about 3 hours to
about 5 hours (e.g., for
about 4 hours). In some cases, the sheet is cooled from the annealing
temperature at a constant
rate of about 40 C/hour to about 50 C/hour. In some examples, the sheet is
not annealed.
Methods of Using
The alloys and methods described herein can be used in industrial applications
including
sacrificial parts, heat dissipation, packaging, and building materials. The
alloys described herein
can be employed as industrial fin stock for heat exchangers. The industrial
fin stock can be
provided such that it is more resistant to corrosion than currently employed
industrial fin stock
alloys (e.g., AA7072 and AA1100) and will still preferentially corrode
protecting other metal
parts incorporated in a heat exchanger. The aluminum alloys disclosed herein
are suitable
substitutes for metals conventionally used in indoor and outdoor HVAC units.
As used herein,
the meaning of "indoor" refers to a placement contained within any structure
produced by
humans with controlled environmental conditions. As used herein, the meaning
of "outdoor"
refers to a placement not fully contained within any structure produced by
humans and exposed
to geological and meteorological environmental conditions comprising air,
solar radiation, wind,
rain, sleet, snow, freezing rain, ice, hail, dust storms, humidity, aridity,
smoke (e.g., tobacco
smoke, house fire smoke, industrial incinerator smoke and wild fire smoke),
smog, fossil fuel
exhaust, bio-fuel exhaust, salts (e.g., high salt content air in regions near
a body of salt water),
radioactivity, electromagnetic waves, corrosive gases, corrosive liquids,
galvanic metals,
galvanic alloys, corrosive solids, plasma, fire, electrostatic discharge
(e.g., lightning), biological
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materials (e.g., animal waste, saliva, excreted oils, vegetation), wind-blown
particulates,
barometric pressure change, and diurnal temperature change. The aluminum
alloys described
herein provide better corrosion performance and higher strength as compared to
alloys currently
employed.
The following examples will serve to further illustrate the present invention
without,
however, constituting any limitation thereof. On the contrary, it is to be
clearly understood that
resort may be had to various embodiments, modifications and equivalents
thereof which, after
reading the description herein, may suggest themselves to those skilled in the
art without
departing from the spirit of the invention. During the studies described in
the following
examples, conventional procedures were followed, unless otherwise stated. Some
of the
procedures are described below for illustrative purposes.
EXAMPLES
Example 1: Mechanical Properties
Exemplary and comparative alloys, as shown in Table 5, were prepared according
to the
methods described herein. Alloys 1, 2, 3, and 4 are exemplary alloys created
according to
methods described herein. Alloy 5 is a comparative alloy prepared according to
methods
described herein. Alloy A is AA7072, which is currently employed as an
industrial fin stock in
commercial applications. Alloy B is AA1100, which is currently employed as an
industrial fin
stock in commercial applications.
Table 5
Alloy Zn Si Fe Cu Mn Mg Cr Ti
1 1.00 0.29 0.51 0.16 0.86 1.2 0.001
0.011
2 1.53 0.3 0.51 0.17 0.87 1.21 0.001
0.016
3 2.04 0.29 0.51 0.17 0.87 1.21 0.001
0.015
4 2.54 0.29 0.51 0.17 0.88 1.23 0.001
0.012
5 0.15 0.22 0.31 0.07 1.00 1.02 0.001
0.16
Comp. A 1.3 0.07 0.37 0.01 0.03 0.03 0.02 0.03
Comp. B 0.1 0.165 0.55 0.075 0.02 0.01 0.02 0.03
All expressed as wt. %.
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The mechanical properties of the exemplary alloys and comparative alloys were
determined according to ASTM B557. Specifically, the alloys were subjected to
tensile,
elongation, and conductivity tests. The yield strength (YS), ultimate tensile
strength (UTS),
percent elongation (El), and percent of the International Annealed Copper
Standard (% IACS)
were determined. The test results are summarized in Table 6.
Table 6
YS UTS El YS UTS El YS UTS El
Gauge %IACS %IACS %IACS
Alloy (MPa)(MPa)(%) (MPa)(MPa)(%) (MPa)(MPa) (%)
(mm)
H19 H23 0
1 0.155 289 296 1.77 39.6 210 241 6.94 41.6 67 171 16.38
42.0
2 0.161 299 307 2.37 42.6 207 239 7.09 41.7 109 183 12.93 43.6
3 0.156 300 308 2.18 40.8 206 236 6.99 41.7 78 190 13.63
39.2
4 0.160 309 318 2.14 40.7 212 240 6.46 41.7 85 205 14.31
43.8
5 0.152 289 297 1.98 36.0 204 230 5.58 36.6 160 206 9.78 39.1
Comp.
0.178 196 213 5.1 59 - - - - - - - -
A
Comp.
B* 0.102 - - - - 108 122.0 20.4 60.3 - -
- -
*Comp. B temper was in H22 temper during testing.
Evident in the tensile test results is the excellent strength of the exemplary
alloys
compared to alloys currently employed as industrial fin stock. The exemplary
alloys exhibited
an average conductivity of about 37 -44 % IACS. As shown above in Table 6, the
exemplary
alloys described herein display exceptional mechanical properties as compared
to the
comparative alloys and can be excellent commercial alloys employed in
industrial fin stock
applications.
Example 2: Corrosion Properties
The corrosion properties of exemplary alloys described herein and comparative
alloys
described herein, elemental compositions of which are provided in Table 5,
were determined. In
addition, the corrosion properties of two additional comparative tube alloys
were determined.
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Comp. Alloy C is an aluminum tube alloy containing 0.15 wt. % Zn and Comp.
Alloy D is an
AA1235 aluminum alloy commonly used in heat exchangers. The open circuit
potential
corrosion values were measured according to ASTM G69. Corrosion test results
are
summarized in Table 7. The aluminum tube alloys Comp. Alloy C and Comp. Alloy
D had an
average open corrosion potential value vs. SCE of -741mV.
Table 7
Alloy Zn Ecorr(mV) vs. SCE
(wt. %) H19 H23 0
1 1.00 -747 -749 -739
2 1.53 -778 -759 -779
3 2.04 -792 -761 -794
4 2.54 -809 -766 -821
5 0.15 -731 -730 -730
Comp. A 1.30 -886 -
Comp. B* 0.10 - -731 -
= Comp. C -741
Comp. D -742
*Alloy AA1100 temper was in H22 temper during testing.
The differences in corrosion resistance values between Alloys 1-5 and Comp.
Alloy C are
shown below in Table 8.
Table 8
Alloy Zn AEcorr(mV)
(wt. %) 1119 H23 0
1 1.00 6 8 -2
2 1.53 37 18 38
3 2.04 51 20 53
4 2.54 68 25 80
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0.15 -10 -11 -11
The differences in corrosion resistance values between Alloys 1-5 and Comp.
Alloy D are
shown below in Table 9.
Table 9
Alloy Zn 6.Ecorr(mV)
(wt. %) H19 H23 0
1 1.00 5 7 -3
2 1.53 36 17 37
3 2.04 50 19 52
4 2.54 67 24 79
5 0.15 -11 -12 -12
5
The exemplary alloys in all tempers (e.g., 1119, H23, and 0) exhibited
electrochemical
potential values comparable to the comparative alloys. The differences between
Alloys 1-5 and
Comp. Alloy C and between Alloys 1-5 and Comp. Alloy D ranged from 15-80 mV.
The data
show that Alloys 2, 3, 4 and 5 are acceptable to prepare fins that act as
sacrificial anodes.
Exemplary alloys with varying Zn subjected to electrochemical corrosion
testing also
exhibited a nearly linear correlation between Zn content and electrochemical
potential. On
average, an increase of 0.1 wt. % Zn provided an increase of about 9 mV in
electrochemical
potential. Exemplary alloys with a Zn content of about 2.5 wt. % or greater
exhibited more
negative corrosion potential, indicating that incorporating Zn greater than
about 2.5 wt. % may
not be desirable for achieving certain properties. Zn can be added optimally
to be sufficiently
resistant to corrosion to serve as a sacrificial alloy in a heat exchanger yet
still preferentially
corrode ahead of any primary functional metal parts of a heat exchanger,
further suggesting the
exemplary alloys described herein are excellent replacements for currently
employed alloys used
in industrial fin stock.
The corrosion properties of the exemplary alloys described herein and the
comparative
alloys described herein according to ASTM 071 were also determined.
Specifically, the
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corrosion properties were measured using zero resistance ammetry (ZRA). The
ZRA galvanic
compatibility was measured where the exemplary alloys were used as fin stock
and Comp. Alloy
C and Comp. Alloy D were used as tubestock. The results shown in Tables 10 and
11 represent
the average current for the last four hours of the cycle as performed
according to the test method.
Table 10 shows the ZRA results for Alloys 1-5 galvanically coupled to Comp.
Alloy C.
Table 10
Alloy Zn Average Current ( A/cm2)
(wt. %) 1119 H23
1.00 26 35
2 1.53 29 24
3 2.04 30 37
4 2.54 27 26
5 0.15 -23 -15
As shown in Table 10, Alloys 1, 2, 3, and 4, containing from 1 to 2.5 wt. %
Zn, displayed
a positive corrosion current indicating that the exemplary fin alloys provided
sacrificial
protection to the tube alloys.
Table 11 shows the ZRA results for Alloys 1-5 galvanically coupled to Comp.
Alloy D.
Table 11
Alloy Zn Average Current ( A/em2)
(wt. %) H19 H23
1 1.00 -30 12.8
2 1.53 10 15
3 2.04 13 4.5
4 2.54 25 9.1
5 0.15 -25 -29
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As shown in Table 11, Alloys 1, 2, 3, and 4, containing from 1 to 2.5 wt. %
Zn, displayed
lower corrosion currents than exemplary alloys coupled with Comp. Alloy C, but
still provided
sacrificial protection to the tube alloy. All the exemplary fin alloys showed
that a protective
current was being provided to the Comp. Alloy C and Comp. Alloy D tubes
throughout the test
period.
The compatibilities of exemplary fin alloys attached to comparative tube
alloys Comp.
Alloy C and Comp. Alloy D were also evaluated according to ASTM G85 Annex 3.
Synthetic
sea water, acidified to 2.8-3.0 pH, was used. The exemplary fin samples were
mechanically
assembled to the tube alloys and subjected to corrosion testing for an
exposure of 4 weeks. As
shown in Figures 1 and 2, the samples displayed progressively more corrosion
on the exemplary
alloys as the zinc content increased from 2 % to 2.5 %. This is particularly
true for the
exemplary alloys coupled to Comp. Alloy D. Based on these data, Zn levels less
than 2 wt. %
are preferred in some instances, but can be optimized depending on tube
composition.
The aluminum alloys described herein provide sacrificial corrosion
characteristics and
mechanical characteristics which enable the manufacture of aluminum alloy fin
stock of reduced
metal thickness. The fin stock of reduced metal thickness maintains
sacrificial protection for the
copper or aluminum alloy tubes in contact with the fins. The aluminum alloys
described herein
can also be used in other situations where mechanical strength in combination
with sacrificial
characteristics are desired.
Various embodiments of the invention have been described in fulfillment of the
various
objectives of the invention. It should be recognized that these embodiments
are merely
illustrative of the principles of the present invention. Numerous
modifications and adaptions
thereof will be readily apparent to those skilled in the art without departing
from the spirit and
scope of the present invention as defined in the following claims.
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