U.S. patent application number 14/071297 was filed with the patent office on 2015-04-16 for method and composition for recycling aluminum containers.
This patent application is currently assigned to Golden Aluminum, Inc.. The applicant listed for this patent is Golden Aluminum, Inc.. Invention is credited to Mark Selepack.
Application Number | 20150101382 14/071297 |
Document ID | / |
Family ID | 50628146 |
Filed Date | 2015-04-16 |
United States Patent
Application |
20150101382 |
Kind Code |
A1 |
Selepack; Mark |
April 16, 2015 |
METHOD AND COMPOSITION FOR RECYCLING ALUMINUM CONTAINERS
Abstract
The present disclosure provides improved processes and
compositions for continuously casting aluminum alloys. The
resulting aluminum alloy sheet is useful for container body
stock.
Inventors: |
Selepack; Mark; (Longmont,
CO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Golden Aluminum, Inc. |
Fort Lupton |
CO |
US |
|
|
Assignee: |
Golden Aluminum, Inc.
Fort Lupton
CO
|
Family ID: |
50628146 |
Appl. No.: |
14/071297 |
Filed: |
November 4, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61721959 |
Nov 2, 2012 |
|
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Current U.S.
Class: |
72/200 ; 420/533;
420/534; 420/542; 420/546; 420/547 |
Current CPC
Class: |
B21B 2003/001 20130101;
C22C 21/00 20130101; B21B 1/463 20130101; C22F 1/047 20130101; C22C
21/08 20130101; C22C 21/06 20130101; B21B 3/00 20130101; B21B 1/46
20130101 |
Class at
Publication: |
72/200 ; 420/542;
420/533; 420/547; 420/546; 420/534 |
International
Class: |
C22F 1/047 20060101
C22F001/047; C22C 21/06 20060101 C22C021/06; B21B 1/46 20060101
B21B001/46; C22C 21/08 20060101 C22C021/08 |
Claims
1. An aluminum alloy composition comprising: a) from about 0.7 wt.
% to about 1.2 wt. % manganese; b) from about 1.5 wt. % to about 2
wt. % magnesium; and c) aluminum.
2. The aluminum alloy of claim 1, comprising from about 0.8 wt. %
to about 0.9 wt. % manganese.
3. The aluminum alloy of claim 1, comprising from about 1.55 wt. %
to about 1.65 wt. % magnesium.
4. The aluminum alloy of claim 1, further comprising from about 0.2
wt. % to about 0.6 wt. % copper.
5. The aluminum alloy of claim 1, further comprising from about
0.25 wt. % to about 0.35 wt. % copper.
6. The aluminum alloy of claim 1, further comprising from about
0.28 wt. % to about 0.45 wt. % iron.
7. The aluminum alloy of claim 1, further comprising from about 0.3
wt. % to about 0.4 wt. % iron.
8. The aluminum alloy of claim 1, further comprising from about 0.1
wt. % to about 0.3 wt. % silicon.
9. The aluminum alloy of claim 1, further comprising from about
0.15 wt. % to about 0.25 wt. % silicon.
10. The aluminum alloy of claim 1, consisting essentially of: a)
manganese in an amount from about 0.7 wt. % to about 1.2 wt. %; b)
magnesium in an amount from about 1.5 wt. % to about 2 wt. %; c)
copper in amount from about 0.20 wt. % to about 0.60 wt. %; d) iron
in an amount from about 0.28 wt. % to about 0.45 wt. %; e) silicon
in an amount from about 0.1 wt. % to about 0.25 wt. %; and the
balance of the alloy composition consisting essentially of aluminum
and incidental additional materials and impurities, wherein the
incidental additional materials and impurities are limited to about
0.05 wt. % each, and the sum total of all incidental additional
materials and impurities does not exceed about 0.15 wt. %.
11. The aluminum alloy of claim 1, consisting essentially of: a)
manganese in an amount from about 0.8 wt. % to about 0.9 wt. %; b)
magnesium in an amount from about 1.55 wt. % to about 1.65 wt. %;
c) copper in an amount from about 0.25 wt. % to about 0.35 wt. %;
d) iron in an amount from about 0.3 wt. % to about 0.4 wt. %; e)
silicon in an amount from about 0.15 wt. % to about 0.25 wt. %; and
the balance of the alloy composition consisting essentially of
aluminum and incidental additional materials and impurities,
wherein the incidental additional materials and impurities are
limited to about 0.05 wt. % each, and the sum total of all
incidental additional materials and impurities does not exceed
about 0.15 wt. %.
12. A process for producing aluminum alloy sheet, comprising: a)
hot rolling continuous cast aluminum alloy comprising from about
0.75 wt. % to about 1.2 wt. % manganese and from about 1.5 wt. % to
about 2 wt. % magnesium; b) hot mill annealing the continuous cast
aluminum alloy; c) intermediate annealing the continuous cast
aluminum alloy; and d) stabilize annealing the continuous cast
aluminum alloy to form aluminum alloy sheet.
13. The process of claim 12, wherein the hot rolling of the
continuous cast aluminum alloy is conducted in the absence of
heating of the continuous cast aluminum alloy.
14. The process of claim 12, further comprising cold rolling the
continuous cast aluminum alloy in one or two passes between the
steps of hot mill annealing and intermediate annealing.
15. The process of claim 12, further comprising cold rolling the
continuous cast aluminum alloy in one or two passes between the
steps of intermediate annealing and stabilize annealing.
16. The process of claim 12, wherein the aluminum alloy sheet has
physical properties useful for container body stock.
17. The process of claim 12, wherein the aluminum alloy comprises
from about 0.8 wt. % to about 0.9 wt. % manganese.
18. The process of claim 12, wherein the aluminum alloy comprises
from about 1.55 wt. % to about 1.65 wt. % magnesium.
19. The process of claim 12, wherein the aluminum alloy comprises
from about 0.2 wt. % to about 0.6 wt. % copper.
20. The process of claim 12, wherein the aluminum alloy comprises
from about 0.25 wt. % to about 0.35 wt. % copper.
21. The process of claim 12, wherein the aluminum alloy comprises
from about 0.28 wt. % to about 0.45 wt. % iron.
22. The process of claim 12, wherein the aluminum alloy comprises
from about 0.3 wt. % to about 0.4 wt. % iron.
23. The process of claim 12, wherein the aluminum alloy comprises
from about 0.1 wt. % to about 0.3 wt. % silicon.
24. The process of claim 12, wherein the aluminum alloy comprises
from about 0.15 wt. % to about 0.25 wt. % silicon.
25. The process of claim 12, wherein the aluminum alloy consists
essentially of: a) manganese in an amount from about 0.7 wt. % to
about 1.2 wt. %; b) magnesium in an amount from about 1.5 wt. % to
about 2 wt. %; c) copper in amount from about 0.20 wt. % to about
0.60 wt. %; d) iron in an amount from about 0.28 wt. % to about
0.45 wt. %; e) silicon in an amount from about 0.1 wt. % to about
0.25 wt. %; and the balance of the alloy composition consisting
essentially of aluminum and incidental additional materials and
impurities, wherein the incidental additional materials and
impurities are limited to about 0.05 wt. % each, and the sum total
of all incidental additional materials and impurities does not
exceed about 0.15 wt. %.
26. The aluminum alloy of claim 1, consisting essentially of: a)
manganese in an amount from about 0.8 wt. % to about 0.9 wt. %; b)
magnesium in an amount from about 1.55 wt. % to about 1.65 wt. %;
c) copper in an amount from about 0.25 wt. % to about 0.35 wt. %;
d) iron in an amount from about 0.3 wt. % to about 0.4 wt. %; e)
silicon in an amount from about 0.15 wt. % to about 0.25 wt. %; and
the balance of the alloy composition consisting essentially of
aluminum and incidental additional materials and impurities,
wherein the incidental additional materials and impurities are
limited to about 0.05 wt. % each, and the sum total of all
incidental additional materials and impurities does not exceed
about 0.15 wt. %.
27. A process for producing aluminum alloy sheet, comprising: a)
hot rolling continuous cast aluminum alloy in the absence of
heating of the continuous cast aluminum alloy, wherein the alloy
comprises manganese in an amount from about 0.7 wt. % to about 1.2
wt. %, magnesium in an amount from about 1.5 wt. % to about 2 wt.
%, copper in amount from about 0.20 wt. % to about 0.60 wt. %, iron
in an amount from about 0.28 wt. % to about 0.45 wt. %, silicon in
an amount from about 0.1 wt. % to about 0.25 wt. %, and the balance
of the alloy composition consisting essentially of aluminum and
incidental additional materials and impurities, wherein the
incidental additional materials and impurities are limited to about
0.05 wt. % each, and the sum total of all incidental additional
materials and impurities does not exceed about 0.15 wt. %; b) hot
mill annealing the continuous cast aluminum alloy; c) cold rolling
the continuous cast aluminum alloy in one or two passes; d)
intermediate annealing the continuous cast aluminum alloy; e) cold
rolling the continuous cast aluminum alloy in one or two passes;
and f) stabilize annealing the continuous cast aluminum alloy to
form aluminum alloy sheet.
Description
FIELD
[0001] The disclosure relates generally to aluminum alloy sheet and
methods for making aluminum alloy sheet. Specifically, the
disclosure relates to methods and compositions for recycling
aluminum alloy containers.
BACKGROUND
[0002] Aluminum beverage and food containers are generally made in
two pieces, one piece forming the container sidewalls and bottom
(referred to herein as a "container body") and a second piece
forming the container top. Container bodies are formed by methods
well known in the art. Generally, the container body is fabricated
by forming a cup from a circular blank of aluminum sheet and then
extending and thinning the sidewalls by passing the cup through a
series of dies having progressively smaller bore size. This process
is referred to as "drawing and ironing" the container body.
[0003] A common aluminum alloy used to produce container bodies is
AA 3004, an alloy registered with the Aluminum Association. The
aluminum alloy composition according to this standard includes the
following constituents: (1) from 0.8 to 1.5 wt. % manganese,; (2)
from 0.8 to 1.3 wt. % magnesium; (3) 0.25 wt. % copper; (4) 0.70
wt. % iron; and (5) about 0.30 wt. % silicon. The balance of the
alloy composition consists essentially of aluminum and incidental
additional materials and impurities. The physical characteristics
of AA 3004 are appropriate for drawing and ironing container bodies
due primarily to the relatively low magnesium (Mg) and manganese
(Mn) content of the alloy. A desirable characteristic of AA 3004 is
that the amount of work hardening imparted to the aluminum sheet
during the can making process is relatively minor.
[0004] A common aluminum alloy used to produce container ends is AA
5782. The aluminum alloy composition according to this standard
includes the following constituents: (1) from 0.2 to 0.5 wt. %
manganese; (2) from 4.0 to 5.0 wt. % magnesium; (3) 0.15 wt. %
copper; (4) 0.35 wt. % iron; and (5) about 0.20 wt. % silicon. The
balance of the alloy composition consists essentially of aluminum
and incidental additional materials and impurities.
[0005] Aluminum alloy sheet is even more commonly produced by an
ingot casting process. In this process, the aluminum alloy material
is initially cast into an ingot, for example having a thickness of
from about 20 to 30 inches. The ingot is then homogenized by
heating to an elevated temperature, which is typically 1075.degree.
F. to 1150.degree. F. (i.e., from about 579 to about 621.degree.
C.), for an extended period of time, such as from about 6 to 24
hours. The homogenized ingot is then hot rolled in a series of
passes to reduce the thickness of the ingot. The hot rolled sheet
is then cold rolled to the desired final gauge.
[0006] Despite the widespread use of ingot casting, there are
numerous advantages to producing aluminum alloy sheet by
continuously casting molten metal. In a continuous casting process,
molten metal is continuously cast directly into a relatively long
thin slab and the cast slab is then hot rolled and cold rolled to
produce a finished product. However, not all alloys can be readily
cast using a continuous casting process into aluminum sheet that is
suitable for forming operations, such as for making drawn and
ironed container bodies.
[0007] Moreover, aluminum can recycling, though desirable, can only
constitute a minority fraction, typically from about 20 to 35 wt.
%, of the melt composition used for body, end and tab stock. The
remainder of the composition must be prime constituents.
[0008] There remains a need for a process which produces an
aluminum alloy sheet having sufficient strength and formability
characteristics to be easily made into drawn and ironed beverage
containers. The sheet stock should have good strength and
elongation, and the resulting container bodies should have low
earing.
[0009] It would be desirable to have a continuous aluminum casting
process in which a majority of the melt composition is derived from
recycled aluminum containers.
SUMMARY
[0010] These and other needs are addressed by the various aspects,
embodiments, and configurations of the present disclosure. The
present disclosure is directed to aluminum alloy compositions for
body stock that can be largely derived from used beverage
containers and methods for making same.
[0011] The disclosed method and compositions can produce containers
having reformed domes, which can allow lower properties for body
stock without substantial changes to container buckle strengths.
Containers generally require greater thickness reductions in can
drawing than in conventional cans. Physical properties are selected
carefully to avoid tear offs and neck wrinkles from can
drawing.
[0012] The present disclosure can provide a number of advantages
depending on the particular configuration. The aluminum alloy
compositions disclosed herein can be derived largely from used
beverage containers, thereby increasing levels of aluminum can
recycle and reducing environmental impact.
[0013] These and other advantages will be apparent from the
disclosure of the aspects, embodiments, and configurations
contained herein.
[0014] As used herein, "at least one", "one or more", and "and/or"
are open-ended expressions that are both conjunctive and
disjunctive in operation. For example, each of the expressions "at
least one of A, B and C", "at least one of A, B, or C", "one or
more of A, B, and C", "one or more of A, B, or C" and "A, B, and/or
C" means A alone, B alone, C alone, A and B together, A and C
together, B and C together, or A, B and C together. When each one
of A, B, and C in the above expressions refers to an element, such
as X, Y, and Z, or class of elements, such as X.sub.1-X.sub.n,
Y.sub.1-Y.sub.m, and Z.sub.1-Z.sub.o, the phrase is intended to
refer to a single element selected from X, Y, and Z, a combination
of elements selected from the same class (e.g., X.sub.1 and
X.sub.2) as well as a combination of elements selected from two or
more classes (e.g., Y.sub.1 and Z.sub.o).
[0015] It is to be noted that the term "a" or "an" entity refers to
one or more of that entity. As such, the terms "a" (or "an"), "one
or more" and "at least one" can be used interchangeably herein. It
is also to be noted that the terms "comprising", "including", and
"having" can be used interchangeably.
[0016] The term "means" as used herein shall be given its broadest
possible interpretation in accordance with 35 U.S.C. Section 112,
Paragraph 6. Accordingly, a claim incorporating die term "means"
shall cover all structures, materials, or acts set forth herein,
and all of the equivalents thereof. Further, the structures,
materials or acts and the equivalents thereof shall include all
those described in the summary, brief description of the drawings,
detailed description, abstract, and, claims themselves.
[0017] Unless otherwise noted, all component or composition levels
are in reference to the active portion of that component or
composition and are exclusive of impurities, for example, residual
solvents or by-products, which may be present in commercially
available sources of such components or compositions.
[0018] All percentages and ratios are calculated by total
composition weight, unless indicated otherwise.
[0019] It should be understood that every maximum numerical
limitation given throughout this disclosure is deemed to include
each and every lower numerical limitation as an alternative, as if
such lower numerical limitations were expressly written herein.
Every minimum numerical limitation given throughout this disclosure
is deemed to include each and every higher numerical limitation as
an alternative, as if such higher numerical limitations were
expressly written herein. Every numerical range given throughout
this disclosure is deemed to include each and every narrower
numerical range that falls within such broader numerical range, as
if such narrower numerical ranges were all expressly written
herein.
[0020] In accordance with an embodiment, an aluminum alloy
composition is provided comprising from about 0.7 wt. % to about
1.2 wt. % manganese; from about 1.5 wt. % to about 2 wt. %
magnesium; and aluminum.
[0021] Commonly, the aluminum alloy comprises from about 0.8 wt. %
to about 0.9 wt. % manganese. Commonly, the aluminum alloy
comprises from about 1.55 wt. % to about 1.65 wt. % magnesium.
[0022] The aluminum alloy can further comprise from about 0.2 wt. %
to about 0.6 wt. % copper, and more commonly from about 0.25 wt. %
to about 0.35 wt. % copper.
[0023] The aluminum alloy can further comprise from about 0.28 wt.
% to about 0.45 wt. % iron, and more commonly from about 0.3 wt. %
to about 0.4 wt. % iron.
[0024] The aluminum alloy can further comprise from about 0.1 wt. %
to about 0.3 wt. % silicon, and more commonly from about 0.15 wt. %
to about 0.25 wt. % silicon.
[0025] In accordance with another embodiment, an aluminum alloy
composition is provided consisting essentially of:
[0026] a) manganese in an amount from about 0.7 wt. % to about 1.2
wt. %;
[0027] b) magnesium in an amount from about 1.5 wt. % to about 2
wt. %;
[0028] c) copper in amount from about 0.20 wt. % to about 0.60 wt.
%;
[0029] d) iron in an amount from about 0.28 wt. % to about 0.45 wt.
%;
[0030] e) silicon in an amount from about 0.1 wt. % to about 0.25
wt. %; and [0031] the balance of the alloy composition consisting
essentially of aluminum and incidental additional materials and
impurities, wherein the incidental additional materials and
impurities are commonly limited to about 0.05 wt. % each, more
commonly limited to about 0.03 wt. % each, and even more commonly
limited to about 0.01 wt. % each and the sum total of all
incidental additional materials and impurities commonly does not
exceed about 0.15 wt. %, more commonly does not exceed about 0.1
wt. %, and even more commonly does not exceed about 0.05 wt. %.
[0032] In accordance with another embodiment, an aluminum alloy
composition is provided consisting essentially of:
[0033] a) manganese in an amount from about 0.8 wt. % to about 0.9
wt. %;
[0034] b) magnesium in an amount from about 1.55 wt. % to about
1.65 wt. %;
[0035] c) copper in an amount from about 0.25 wt. % to about 0.35
wt. %;
[0036] d) iron in an amount from about 0.3 wt. % to about 0.4 wt.
%;
[0037] e) silicon in an amount from about 0.15 wt. % to about 0.25
wt. %; and [0038] the balance of the alloy composition consisting
essentially of aluminum and incidental additional materials and
impurities, wherein the incidental additional materials and
impurities are commonly limited to about 0.05 wt. % each, more
commonly limited to about 0.03 wt. % each, and even more commonly
limited to about 0.01 wt. % each and the sum total of all
incidental additional materials and impurities commonly does not
exceed about 0.15 wt. %, more commonly does not exceed about 0.1
wt. %, and even more commonly does not exceed about 0.05 wt. %.
[0039] The aluminum alloy described above is useful in continuous
casting processes. The resulting aluminum alloy sheet is useful as
body stock for production of containers.
[0040] In accordance with an embodiment, a process for producing
aluminum alloy sheet is provided comprising: [0041] a) hot rolling
continuous cast aluminum alloy comprising from about 0.75 wt. % to
about 1.2 wt. % manganese and from about 1.5 wt. % to about 2 wt. %
magnesium; [0042] b) hot mill annealing the continuous cast
aluminum alloy; [0043] c) intermediate annealing the continuous
cast aluminum alloy; and [0044] d) stabilize annealing the
continuous cast aluminum alloy aluminum alloy sheet. [0045]
Commonly, the hot rolling of the continuous cast aluminum alloy is
conducted in the absence of heating of the continuous cast aluminum
alloy.
[0046] The process can further comprise cold rolling the continuous
cast aluminum alloy in one or two passes between the steps of hot
mill annealing and intermediate annealing.
[0047] The process can further comprise cold rolling the continuous
cast aluminum alloy in one or two passes between the steps of
intermediate annealing and stabilize annealing.
[0048] In the process, the aluminum sheet has physical properties
useful for container body stock.
[0049] The aluminum alloy used in the process can comprise from
about 0.8 wt. % to about 0.9 wt. % manganese.
[0050] The aluminum alloy used in the process can comprise from
about 1.55 wt. % to about 1.65 wt. % magnesium.
[0051] The aluminum alloy used in the process can further comprise
from about 0.2 wt. % to about 0.6 wt. % copper, and more commonly
from about 0.25 wt. % to about 0.35 wt. % copper.
[0052] The aluminum alloy used in the process can further comprise
from about 0.28 wt. % to about 0.45 wt. % iron, and more commonly
from about 0.3 wt. % to about 0.4 wt. % iron.
[0053] The aluminum alloy used in the process can further comprise
from about 0.1 wt. % to about 0.3 wt. % silicon, and more commonly
from about 0.15 wt. % to about 0.25 wt. % silicon.
[0054] The aluminum alloy used in the process can consist
essentially of:
[0055] a) manganese in an amount from about 0.7 wt. % to about 1.2
wt. %;
[0056] b) magnesium in an amount from about 1.5 wt. % to about 2
wt. %;
[0057] c) copper in amount from about 0.20 wt. % to about 0.60 wt.
%;
[0058] d) iron in an amount from about 0.28 wt. % to about 0.45 wt.
%;
[0059] e) silicon in an amount from about 0.1 wt. % to about 0.25
wt. %; and [0060] the balance of the alloy composition consisting
essentially of aluminum and incidental additional materials and
impurities, wherein the incidental additional materials and
impurities are commonly limited to about 0.05 wt. % each, more
commonly limited to about 0.03 wt. % each, and even more commonly
limited to about 0.01 wt. % each and the sum total of all
incidental additional materials and impurities commonly does not
exceed about 0.15 wt. %, more commonly does not exceed about 0.1
wt. %, and even more commonly does not exceed about 0.05 wt. %.
[0061] The aluminum alloy used in the process can consist
essentially of:
[0062] a) manganese in an amount from about 0.8 wt. % to about 0.9
wt. %;
[0063] b) magnesium in an amount from about 1.55 wt. % to about
1.65 wt. %;
[0064] c) copper in an amount from about 0.25 wt. % to about 0.35
wt. %;
[0065] d) iron in an amount from about 0.3 wt. % to about 0.4 wt.
%;
[0066] e) silicon in an amount from about 0.15 wt. % to about 0.25
wt. %; and [0067] the balance of the alloy composition consisting
essentially of aluminum and incidental additional materials and
impurities, wherein the incidental additional materials and
impurities are commonly limited to about 0.05 wt. % each, more
commonly limited to about 0.03 wt. % each, and even more commonly
limited to about 0.01 wt. % each and the sum total of all
incidental additional materials and impurities commonly does not
exceed about 0.15 wt. %, more commonly does not exceed about 0.1
wt. %, and even more commonly does not exceed about 0.05 wt. %.
[0068] In accordance with an embodiment, a process for producing
aluminum alloy sheet is provided comprising: [0069] a) hot rolling
continuous cast aluminum alloy in the absence of heating of the
continuous cast aluminum alloy, wherein the alloy comprises
manganese in an amount from about 0.7 wt. % to about 1.2 wt. %,
magnesium in an amount from about 1.5 wt. % to about 2 wt. %,
copper in amount from about 0.20 wt. % to about 0.60 wt. %, iron in
an amount from about 0.28 wt. % to about 0.45 wt. %, silicon in an
amount from about 0.1 wt. % to about 0.25 wt. %, and the balance of
the alloy composition consisting essentially of aluminum and
incidental additional materials and impurities, wherein the
incidental additional materials and impurities are limited to about
0.05 wt. % each, and the sum total of all incidental additional
materials and impurities does not exceed about 0.15 wt. %; [0070]
b) hot mill annealing the continuous cast aluminum alloy; [0071] c)
cold rolling the continuous cast aluminum alloy in one or two
passes; [0072] d) intermediate annealing the continuous cast
aluminum alloy; [0073] e) cold rolling the continuous cast aluminum
alloy in one or two passes; and [0074] f) stabilize annealing the
continuous cast aluminum alloy to form aluminum alloy sheet.
[0075] The alloy compositions can be formed in part from scrap
metal material, such as plant scrap, container scrap and consumer
scrap. An alloy composition can be formed with at least about 75%,
more commonly at least about 80%, more commonly at least about 85%,
more commonly at least about 90% and more commonly at least about
95% total scrap. Aluminum prime can be added to dilute components
present in excess (e.g., decrease magnesium content by dilution),
and component prime can be added to supplement components (e.g.,
manganese prime can be added to increase manganese content to
desired levels).
[0076] The preceding is a simplified summary of the disclosure to
provide an understanding of some aspects of the disclosure. This
summary is neither an extensive nor exhaustive overview of the
disclosure and its various aspects, embodiments, and
configurations. It is intended neither to identify key or critical
elements of the disclosure nor to delineate the scope of the
disclosure but to present selected concepts of the disclosure in a
simplified form as an introduction to the more detailed description
presented below. As will be appreciated, other aspects,
embodiments, and configurations of the disclosure are possible
utilizing, alone or in combination, one or more of the features set
forth above or described in detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0077] The accompanying drawings are incorporated into and form a
part of the specification to illustrate several examples of the
present disclosure. These drawings, together with the description,
explain the principles of the disclosure. The drawings simply
illustrate common and alternative examples of how the disclosure
can be made and used and are not to be construed as limiting the
disclosure to only the illustrated and described examples. Further
features and advantages will become apparent from the following,
more detailed, description of the various aspects, embodiments, and
configurations of the disclosure, as illustrated by the drawings
referenced below.
[0078] FIG. 1 depicts a first aluminum alloy sheet manufacturing
process according to an embodiment; and
[0079] FIG. 2 depicts a second aluminum alloy sheet manufacturing
process according to an embodiment.
DETAILED DESCRIPTION
[0080] The various continuous casting processes of the present
disclosure can produce aluminum alloy sheet having high strength,
low earing, highly desirable forming properties, and/or an
equiaxed/finer grain structure. As used herein, "continuous
casting" refers to a casting process that produces a continuous
strip as opposed to a process producing a rod or ingot. By way of
example, the continuous casting processes can include optionally
heating the cast strip in front of the last hot mill stand (i.e.,
between the caster and first hot mill stand or between hot mill
stands). The heater can reduce the load on the hot mill stands,
thereby permitting greater reductions of the cast strip in the hot
mill, provide a hot milled strip having an equiaxed grain
structure, and/or facilitate self-annealing (i.e.,
recrystallization) of the unheated strip when the unheated strip is
cooled, thereby obviating, in many cases, the need for a hot mill
anneal. The increased hot mill reductions can eliminate one or more
cold mill passes. Alternatively, one or more hot mill steps can be
conducted in the absence of heating. The processes can further
include continuous intermediate annealing of the cold rolled strip.
The continuous anneal can provide more uniform mechanical
properties for the aluminum alloy sheet, a finer grain size,
controllable mechanical properties using a stabilizing anneal, and
significant savings in operating and alloy costs and improvements
in production capacity. The intermediate anneal is particularly
useful for body stock. Finally, the continuous casting processes
can include stabilization or back annealing of the cold rolled
strip.
[0081] The aluminum alloy sheet produced in accordance with the
various embodiments can maintain sufficient strength and
formability properties while having a relatively thin gauge. This
is especially important when the aluminum alloy sheet is utilized
in body stock for making drawn and ironed containers. The trend in
the can making industry is to use thinner aluminum alloy sheet for
the production of drawn and ironed containers, thereby producing a
container containing less aluminum and having a reduced cost.
However, to use thinner gauge aluminum sheet, the aluminum alloy
sheet must still have the required physical characteristics.
Surprisingly, continuous casting processes have been discovered
which produce an aluminum alloy sheet that can meet industry
standards for body stock, particularly when utilized with the
alloys of the present disclosure.
[0082] The aluminum alloy composition for container bodies commonly
includes the following constituents: [0083] (1) with a minimum of
at least about 0.7 wt. %, more commonly with a minimum of at least
about 0.75 wt. %, more commonly with a minimum of at least about
0.8 wt. %, and even more commonly with a minimum of at least about
0.85 wt. % and with a maximum of at most about 1.2 wt. %, more
commonly with a maximum of at most about 1.1 wt. %, more commonly
with a maximum of at most about 1 wt. %, and even more commonly
with a maximum of at most about 0.9 wt. % manganese; [0084] (2)
with a minimum of at least about 1.5 wt. %, more commonly with a
minimum of at least about 1.51 wt. %, more commonly with a minimum
of at least about 1.52 wt. %, more commonly with a minimum of at
least about 1.53 wt. %, more commonly with a minimum of at least
about 1.54 wt. %, and even more commonly with a minimum of at least
about 1.55 wt. % and with a maximum of at most about 2 wt. %, more
commonly with a maximum of at most about 1.9 wt. %, more commonly
with a maximum of at most about 1.8 wt. %, more commonly with a
maximum of at most about 1.7 wt. %, more commonly with a maximum of
at most about 1.65 wt. %, and even more commonly with a maximum of
at most about 1.6 wt. % magnesium; [0085] (3) with a minimum of at
least about 0.2 wt. %, more commonly with a minimum of at least
about 0.25 wt. % and even more commonly with a minimum of at least
about 0.3 wt. % and with a maximum of at most about 0.6 wt. %, more
commonly with a maximum of at most about 0.5 wt. %, more commonly
with a maximum of at most about 0.4 wt. % and even more commonly
with a maximum of at most about 0.35.% copper; [0086] (4) with a
minimum of at least about 0.28 wt. %, more commonly with a minimum
of at least about 0.30 wt. %, and even more commonly with a minimum
of at least about 0.32 wt. % and with a maximum of at most about
0.45 wt. %, more commonly with a maximum of at most about 0.4 wt. %
and even more commonly with a maximum of at most about 0.35 wt. %
iron; and [0087] (5) with a minimum of at least about 0.1 wt. %,
more commonly with a minimum of at least about 0.15 wt. % and with
a maximum of at most about 0.3 wt. %, more commonly with a maximum
of at most about 0.25 wt. %, and even more commonly with a maximum
of at most about 0.2 wt. % silicon. The balance of the alloy
composition consists essentially of aluminum and incidental
additional materials and impurities. The incidental additional
materials and impurities are commonly limited to about 0.05 wt. %
each, more commonly limited to about 0.03 wt. % each, and even more
commonly limited to about 0.01 wt. % each and the sum total of all
incidental additional materials and impurities commonly does not
exceed about 0.15 wt. %, more commonly does not exceed about 0.1
wt. %, and even more commonly does not exceed about 0.05 wt. %.
[0088] A particularly useful aluminum alloy composition for body
stock includes the following constituents:
[0089] (1) Manganese in an amount from about 0.8 wt. % to about 0.9
wt. %;
[0090] (2) Magnesium in an amount from about 1.55 wt. % to about
1.65 wt. %;
[0091] (3) Copper in an amount from about 0.25 wt. % to about 0.35
wt. %;
[0092] (4) Iron in an amount from about 0.3 wt. % to about 0.4 wt.
%; and
[0093] (5) Silicon in an amount from about 0.15 wt. % to about 0.25
wt. %.
The balance of the alloy composition commonly consists essentially
of aluminum and incidental additional materials and impurities. The
incidental additional materials and impurities are commonly limited
to about 0.05 wt. % each, more commonly limited to about 0.03 wt. %
each, and even more commonly limited to about 0.01 wt. % each and
the sum total of all incidental additional materials and impurities
commonly does not exceed about 0.15 wt. %, more commonly does not
exceed about 0.1 wt. %, and even more commonly does not exceed
about 0.05 wt. %.
[0094] The above compositions result in alloys that can be
effectively formed into container bodies having desirably low tear
offs, while maintaining desired physical qualities such as buckle
strength. Commonly, containers formed from the above alloys have
acceptably low decreases in strength when heated, such as in an
oven to cure decorated containers.
[0095] The above compositions can be derived from a melt of
conventional can bodies or used beverage containers ("UBCs")
including the following constituents: [0096] (1) with a minimum of
at least about 0.45 wt. %, more commonly with a minimum of at least
about 0.50 wt. % and with a maximum of at most about 1.1 wt. %,
more commonly with a maximum of at most about 0.95 wt. %, more
commonly with a maximum of at most about 0.80 wt. %, and even more
commonly with a maximum of at most about 0.70 wt. % manganese;
[0097] (2) with a minimum of at least about 1.2 wt. %, more
commonly with a minimum of at least about 1.25 wt. %, more commonly
with a minimum of at least about 1.3 wt. %, more commonly with a
minimum of at least about 1.35 wt. %, and even more commonly with a
minimum of at least about 1.4 wt. % and with a maximum of at most
about 2 wt. %, more commonly with a maximum of at most about 1.95
wt. %, more commonly with a maximum of at most about 1.9 wt. %,
more commonly with a maximum of at most about 1.85 wt. %, and even
more commonly with a maximum of at most about 1.8 wt. % magnesium;
[0098] (3) with a minimum of at least about 0.05 wt. %, more
commonly with a minimum of at least about 0.1 wt. % and even more
commonly with a minimum of at least about 0.15 wt. % and with a
maximum of at most about 0.5 wt. %, more commonly with a maximum of
at most about 0.4 wt. % and even more commonly with a maximum of at
most about 0.3 wt. % copper; [0099] (4) with a minimum of at least
about 0.2 wt. %, more commonly with a minimum of at least about 0.3
wt. % and with a maximum of at most about 0.7 wt. %, more commonly
with a maximum of at most about 0.6 wt. % and even more commonly
with a maximum of at most about 0.5 wt. % iron; and [0100] (5) with
a minimum of at least about 0.1 wt. %, more commonly with a minimum
of at least about 0.15 wt. % and with a maximum of at most about
0.5 wt. %, more commonly with a maximum of at most about 0.45 wt.
%, and even more commonly with a maximum of at most about 0.35 wt.
% silicon. The balance of the melt composition consists essentially
of aluminum and incidental additional materials and impurities. The
incidental additional materials and impurities are commonly limited
to about 0.05 wt. % each, more commonly limited to about 0.03 wt. %
each, and even more commonly limited to about 0.01 wt. % each and
the sum total of all incidental additional materials and impurities
commonly does not exceed about 0.15 wt. %, more commonly does not
exceed about 0.1 wt. %, and even more commonly does not exceed
about 0.05 wt. %.
[0101] To alter this composition to produce container body stock,
prime is added such that the final melt composition typically is no
more than about 25 wt. %, more typically no more than about 20 wt.
%, more typically no more than about 15 wt. % prime, more typically
no more than about 10 wt. % prime, and even more typically no more
than about 5 wt. % prime, with the balance being the molten
composition from recycled containers or used beverage containers
("UBCs").
[0102] A first embodiment of a continuous casting process is
depicted in FIG. 1. This process is particularly useful for forming
body stock for container manufacture.
[0103] Referring to FIG. 1, a melt of the aluminum alloy
composition is formed and continuously cast 20 to form a cast strip
24. The continuous casting process can employ a variety of
continuous casters, such as a belt caster or a roll caster.
[0104] The alloy composition can be formed in part from scrap metal
material, such as plant scrap, container scrap and consumer scrap.
Commonly, the alloy composition is formed with at least about 75%,
more commonly at least about 80%, more commonly at least about 85%,
more commonly at least about 90% and more commonly at least about
95% total scrap. Aluminum prime is typically added to dilute e.g.,
magnesium content (by dilution), and e.g., manganese prime is added
to increase e.g., manganese content to desired levels.
[0105] To form the melt, the metal is charged into a furnace and
heated to a temperature of about 1385.degree. F. (i.e., about
752.degree. C.) (i.e., above the melting point of the feed
material) until the metal is thoroughly melted. The alloy is
treated to remove materials such as dissolved hydrogen and
non-metallic inclusions which would impair casting of the alloy and
the quality of the finished sheet. The alloy can also be filtered
to further remove non-metallic inclusions from the melt. The melt
is then cast through a nozzle and discharged into the casting
cavity. The nozzle can include a long, narrow tip to constrain the
molten metal as it exits the nozzle. The nozzle tip size commonly
ranges from about 10 to about 25 mm, more commonly from about 12 to
about 22 mm, more commonly from about 16 to about 19 mm, and even
more commonly about 19 mm.
[0106] The melt exits the tip and is received in the casting cavity
which is formed by opposing pairs of rotating chill blocks. The
metal cools and solidifies as it travels through the casting cavity
due to heat transfer to the chill blocks. At the end of the casting
cavity, the chill blocks, which are on a continuous web, separate
from the cast strip 24. The blocks travel to a cooler where the
treated chill blocks are cooled before being reused.
[0107] The cast temperature of the cast strip 24 exiting the block
caster commonly exceeds the recrystallization temperature of the
cast strip. The cast output temperature (i.e., the output
temperature as the cast strip exits the caster) commonly ranges
from about 800 to about 1050.degree. F. (i.e., about 426 to about
565.degree. C.) and more commonly from about 900 to about
1050.degree. F. (i.e., about 482 to about 565.degree. C.).
[0108] The cast strip 24 is hot rolled 160 to form a hot rolled
strip 164. In the hot rolling step 160, the cast strip 24 is
commonly reduced in thickness by an amount of at least about 50%,
more commonly at least about 55%, and even more commonly at least
about 68% but no more than about 85%, more commonly no more than
about 90%, and even more commonly no more than about 95% to a gauge
commonly ranging from about 0.06 to about 0.12 inches, more
commonly from about 0.085 to about 0.110 inches, and even more
commonly from about 0.06 to about 0.09 inches. The lowering of the
gauge of the hot rolled strip to the range of about 0.06 to about
0.09 can provide further reductions in the tested earing of the
sheet 312, improved surface grain size, and increased strength
properties.
[0109] The hot rolled strip 164 is hot mill annealed 300 in a batch
or continuous heater to form a hot mill annealed strip 316. The
continuous heater can be a gas-fired, infrared, or an induction
heater.
[0110] The duration of the anneal depends upon the type of furnace
employed, i.e., on how long it takes to achieve the desired metal
temperature. The strip is commonly intermediate annealed at a
minimum temperature of about 725.degree. F. (i.e., about
385.degree. C.) and more commonly about 775.degree. F. (i.e., about
413.degree. C.), and commonly at a maximum temperature of about
900.degree. F. (i.e., about 482.degree. C.), more commonly of no
more than about 850.degree. F. (i.e., about 454.degree. C.), and
more commonly of no more than about 825.degree. F. (i.e., about
441.degree. C.).
[0111] The hot mill annealed strip 316 is allowed to cool and then
subjected to cold rolling 320 to form a partially cold rolled strip
324. In the cold rolling step 320, the thickness of the strip 316
is commonly reduced by at least about 50%, more commonly at least
about 60%, but no more than about 75% and more commonly no more
than about 65%. Commonly, the reduction to intermediate gauge is
performed in 1 to 2 passes. The minimum gauge of the partially cold
rolled strip 324 is commonly about 0.02 inches and even more
commonly about 0.025 inches, and the maximum gauge is commonly
about 0.04 inches and even more commonly about 0.035 inches. In one
embodiment, the gauge of the partially cold rolled strip 324 is
about 0.03 inches. In one application, the cold rolling reduction
upstream of intermediate annealing is maintained at no more than
73%. This intermediate gauge is based on the desired final
gauge.
[0112] The partially cold rolled strip 324 is intermediate annealed
304 to form an intermediate annealed strip 328. Intermediate
annealing commonly removes tensile and yield strength increases
from hot mill reductions. The minimum temperature of the anneal 304
commonly is about 710.degree. F. (i.e., about 377.degree. C.), more
commonly about 720.degree. F. (i.e., about 382.degree. C.), and
even more commonly about 725.degree. F. (i.e., about 385.degree.
C.). The maximum temperature of the anneal 304 is commonly about
850.degree. F. (i.e., about 454.degree. C.), more commonly about
800.degree. F. (i.e., about 427.degree. C.), and even more commonly
about 750.degree. F. (i.e., about 399.degree. C.).
[0113] The annealed strip 328 can be cooled, such as by quenching,
and/or a nitrogen purge, after annealing.
[0114] After cooling, the annealed strip 328 is subjected to cold
rolling 332 to form cold rolled strip 336. Commonly, the reduction
to final gauge by cold rolling 332 is performed in 1 to 2 passes.
As will be appreciated, a greater degree of reduction upstream of
intermediate annealing can reduce required cold rolling reductions
downstream to maintain desired physical properties and to achieve
the desired final gauge. The common reduction in thickness of the
annealed strip 328 is at least about 30%, more commonly at least
about 40%, more commonly at least about 50%, and even more commonly
at least about 55% but no more than about 90%, more commonly no
more than about 80%, more commonly no more than about 75%, and even
more commonly no more than about 70%, and commonly about 65%
reduction to a gauge ranging from about 0.005 to about 0.013
inches, even more commonly ranging from about 0.009 to about 0.013
inches.
[0115] Intermediate annealing and subsequent cold work help control
final earing.
[0116] The cold rolled strip 336 is optionally subjected to a
stabilize anneal 308 to form aluminum alloy sheet 312 with desired
final mechanical properties. Stabilize annealing can protect a dome
formed in subsequent container-forming processes from orange
peeling and produce desired physical properties. Stabilize
annealing commonly removes or reduces tensile and yield strengths
by approximately 5 ksi. A batch or continuous heater can be
employed in the stabilized anneal 308. The cold rolled strip 336 is
commonly stabilize annealed 308 at a minimum temperature of at
least about 300.degree. F. (i.e., about 146.degree. C.) and more
commonly at least about 325.degree. F. (i.e., about 162.degree.
C.), and commonly at a maximum temperature of no more than about
500.degree. F. (i.e., about 260.degree. C.), more commonly of no
more than about 450.degree. F. (i.e., about 232.degree. C.), and
even more commonly of no more than about 400.degree. F. (i.e.,
about 204.degree. C.). The even more common temperature range is
from about 300 to about 400.degree. F. (i.e., from about 146 to
about 204.degree. C.
[0117] The aluminum alloy sheet 312 has properties that are
particularly useful for body stock. When the aluminum alloy sheet
312 is to be used as body stock, the alloy sheet commonly has a
final yield strength of at least about 32 ksi and more commonly at
least about 34 ksi, and even more commonly at least about 36 ksi
but commonly no more than about 43 ksi, more commonly no more than
about 41 ksi, and even more commonly no more than about 39 ksi. The
final tensile strength commonly is at least about 38 ksi, more
commonly at least about 39 ksi, more commonly at least about 40
ksi, and even more commonly at least about 41 ksi but commonly no
more than about 46 ksi, more commonly no more than about 45 ksi,
more commonly no more than about 44 ksi, and even more commonly no
more than about 43 ksi. The aluminum alloy sheet 312 should have a
final elongation of at least about 3% and more commonly at least
about 4%. In an embodiment, the aluminum alloy sheet 312 should
have a final elongation of no more than about 7% and more commonly
no more than about 6%.
[0118] To produce acceptable drawn and ironed container bodies,
aluminum alloy sheet 312 used as body stock should have a low
earing percentage. Commonly, the aluminum alloy sheet 312,
according to the present disclosure, has a tested earing of no more
than about 1.5% and more commonly no more than about 1% and most
commonly no more than about 0.75%, based on testing of a 55 mm
drawn cup using a Tinius Olsen Ductomatic.
[0119] Container bodies fabricated from the aluminum alloy sheet
312 of the embodiment of the present disclosure have relatively
high strengths. The container bodies have a minimum dome reversal
strength of at least about 90 psi, commonly at least about 93 psi
and more commonly at least about 96 psi at current commercial
thicknesses. The column strength of the container bodies commonly
is at least about 230 psi and more commonly at least about 250
psi.
[0120] In accordance with yet another embodiment of the present
disclosure, a method is provided for fabricating an aluminum alloy
sheet in which the initial cold rolling step is performed in the
absence of an annealing step after hot rolling and before the first
cold rolling step and/or in which the reductions in strip thickness
between intermediate anneals and after the last intermediate anneal
are maintained at or below a specified level to avoid full hard
conditions. The first intermediate annealing step is commonly
performed after the first cold rolling step, and the second
intermediate annealing step is performed after the subsequent cold
rolling step. The method generally includes the steps of: (i)
forming an aluminum alloy melt; (ii) continuously casting the alloy
melt to form a cast strip; (iii) optionally heating the cast strip
before hot rolling; (iv) hot rolling the cast strip to form a hot
rolled strip (typically having a gauge ranging from about 0.06 to
about 0.090 inches); (v) cooling the hot rolled strip to a
temperature below the recrystallization temperature of the hot
rolled strip; (vi) cold rolling the hot rolled strip to form a
partially cold rolled strip (typically having a gauge ranging from
about 0.025 to about 0.035 inches); (vii) annealing, commonly in a
batch anneal, the partially cold rolled strip to form a first
intermediate annealed strip; and (viii) further cold rolling the
first intermediate cold mill strip to form a further cold rolled
strip; (ix) optionally further annealing, either in a continuous or
a batch anneal, the further cold rolled strip to form a second
intermediate annealed strip; and (x) forming the second
intermediate annealed strip into the aluminum alloy sheet. As
desired, after annealing step (ix) the second intermediate annealed
strip can be further cold rolled and/or stabilize annealed to form
the aluminum alloy sheet.
[0121] The elimination of the annealing step directly after the hot
rolling step and the performance of two separate annealing steps
only after cold rolling steps offer a number of advantages,
particularly when the resulting sheet is employed in the
fabrication of containers such as cans. The containers produced
from the aluminum alloy sheet can have a reduced degree of earing
and a reduction in the occurrence of split flanges and sidewalls in
containers produced from the sheet. The container dimensions can be
within an acceptable tolerance of the specified container
dimensions. Containers produced from the sheet can have a
significantly reduced incidence of bulging in the container
necked/flange sidewalls compared to containers produced from
aluminum alloy sheet having different compositions and/or produced
by other processes. It is believed that the alloy sheet of the
present disclosure typically experiences less work hardening during
fabrication of containers from the sheet than other continuously
cast alloys and comparable to direct chill or ingot cast sheet. For
instance, work hardening can occur when cans come off the canmaker
and are heated to elevated temperatures to dry the paint on the
can. As noted, the reductions in strip thickness between the two
intermediate annealing steps and after the final intermediate
annealing step are each maintained below the level required for the
strip to realize a full hard state. The annealing of a thinner
gauge of sheet (i.e., annealing which is performed only after cold
rolling steps) compared to annealing in previous embodiments (i.e.,
which is performed after casting and before hot rolling and again
after cold rolling) increases the amount of reduction which can be
satisfactorily achieved with each cold roll pass and thus can
eliminate one or more cold rolling passes relative to previous
embodiments. Finally, the physical properties of the sheet of this
embodiment can experience significantly less reduction during
fabrication relative to the reduction in physical properties of
other alloy sheets during fabrication. In canmaking applications,
for example, existing continuously cast alloy sheets can suffer a
reduction in physical properties of as much as 4 lbs or more in
buckle strength and 20 lbs or more in column strength, after
heating the sheet in deco/IBO ovens.
[0122] The aluminum alloy sheet produced by the above-described
method can have a number of desirable properties, including those
mentioned above.
[0123] With continuing reference to FIG. 2, in the process the
continuously cast strip 24 is produced in a casting cavity having a
common tip diameter ranging from about 17 to about 19 mm and
subjected to hot rolling as described previously to form the hot
rolled strip 40. The hot mill commonly reduces the thickness of the
cast strip in one or more passes by at least about 70% and more
commonly by at least about 80%. The gauge of the cast strip
commonly ranges from about 0.50 inches to about 0.95 inches while
the gauge of the hot rolled strip ranges from about 0.060 to about
0.140 inches. The hot rolled strip commonly exits the hot mill at a
temperature ranging from about 500 to about 750.degree. F. (i.e.,
from about 260 to about 399.degree. C.). It is common that the
total reduction of the cast strip be realized in two to three
passes with two passes being even more common.
[0124] As an optional step, the continuously cast strip 24 can be
heated 28 as described above to form a heated strip 32. The heated
strip 32 is then hot rolled 36 to form the hot rolled strip 40.
[0125] The hot rolled strip 40 passes directly to a cooling step
400 before the first cold rolling step to form a cooled strip 404.
The hot rolled strip 40 is allowed to cool before cold rolling to a
temperature less than the recrystallization temperature of the hot
rolled strip. Commonly, the hot rolled strip 40 is allowed to cool
for a sufficient period of time to produce a hot rolled sheet
having a temperature ranging from about 75 to about 140.degree. F.
(i.e., from about 24 to about 60.degree. C.). Generally, the hot
rolled strip 40 is cooled for about 48 hours. The strip is commonly
not quenched or otherwise solution heat treated.
[0126] In the first cold rolling step 408, the cooled strip 404 is
passed between cold rollers, as necessary, to form a cold rolled
strip 412 at an intermediate gauge. Commonly, the intermediate
gauge ranges from about 0.020 to about 0.055 inches, more commonly
from about 0.025 to about 0.045 and more commonly from about 0.030
to about 0.035 inches. The total reduction commonly is less than
about 65% and more commonly ranges from about 20% to about 45% and
more commonly from about 25 to about 40% through the cold rollers.
It is common that the total sheet reduction be realized in two
passes or less, with a single pass being even more common.
[0127] When the desired intermediate anneal gauge is reached
following the first cold rolling step 408, the cold rolled strip
412 is breakdown or first intermediate annealed 416 in a batch
anneal oven to form a first intermediate annealed strip 420 and
reduce the residual cold work and lower the earing of the aluminum
sheet. The first intermediate anneal 416 is commonly a heat soak
anneal. Commonly, the strip 412 is intermediate annealed at a
minimum temperature of at least about 500.degree. F. (i.e., about
260.degree. C.), more commonly of at least about 600.degree. F.
(i.e., about 316.degree. C.), and more commonly at a minimum of at
least about 650.degree. F. (i.e., about 343.degree. C.), and at a
maximum temperature commonly of no more than about 850.degree. F.
(i.e., about 454.degree. C.), more commonly of no more than about
800.degree. F. (i.e., about 427.degree. C.), and even more commonly
of no more than about 775.degree. F. (i.e., about 413.degree. C.).
The even more common annealing temperature is about 725.degree. F.
(i.e., about 385.degree. C.). The annealing soak time is commonly a
minimum of at least about 0.5 hours and is more commonly a minimum
of at least about 1 hour with about 3 hours being even more
common.
[0128] Commonly, the first intermediate annealed strip 420 is
allowed to cool to a temperature less than the recrystallization
temperature of the strip prior to additional cold rolling steps.
The common temperature for cold rolling ranges from about 75 to
about 140.degree. F. (i.e., from about 24 to about 60.degree. C.).
The cooling time typically is 48 hours. As will be appreciated, the
strip can be force cooled in a significantly shorter time by
injecting nitrogen gas into the batch anneal oven to reduce the
sheet temperatures to about 250.degree. F. (i.e., about 121.degree.
C.). However, the strip is commonly not subjected to solution heat
treatment.
[0129] After the strip 420 has cooled to ambient temperature, a
further cold rolling step 424 is used, as necessary, to form a
further cold rolled strip 428 having a smaller intermediate gauge.
Commonly, the intermediate gauge ranges from about 0.015 to about
0.040 inches and more commonly from about 0.030 to about 0.035
inches. It is common that the thickness of the strip be reduced in
total by less than 73%, more commonly by no more than about 71%,
and more commonly by no more than about 70%. It is common that the
total reduction be realized in two passes or less, with a single
pass being common.
[0130] By maintaining all reductions between anneal points below
the level necessary to realize full hard conditions (i.e., about
73% or higher), the earing can be maintained at relatively low
levels. As will be appreciated, the earing of a strip is directly
related to the amount of cold work the strip experiences. The
reduction in the final cold rolling step is selected to realize the
desired strength properties in the final aluminum alloy sheet.
[0131] The further cold rolled strip 428 is annealed a second time
or second intermediate annealed 432, commonly in a continuous or
batch anneal oven, to form a second intermediate annealed strip
436. The anneal can be a heat soak anneal or a continuous anneal,
such as in an induction heater. Commonly, the annealing temperature
for a batch heater ranges from about 600 to about 900.degree. F.
(i.e., from about 316 to about 482.degree. C.), more commonly from
about 650 to about 750.degree. F. (i.e., from about 343 to about
399.degree. C.). The even more common temperature is about
705.degree. F. (i.e., about 374.degree. C.). The annealing or soak
time commonly is at least about 0.5 hrs and more commonly about 2
hrs, with about 3 hrs being even more common. Commonly the
annealing temperature for a continuous heater ranges from about 700
to about 1050.degree. F. (i.e., from about 371 to about 566.degree.
C.), with about 700.degree. F. (i.e., about 371.degree. C.) being
more common. The annealing or soak time commonly ranges from about
2 seconds to about 2.5 minutes and more commonly from about 3 to
about 10 seconds.
[0132] Commonly, the second intermediate annealed strip 436 is
allowed to cool to a temperature less than the recrystallization
temperature of the strip prior to a final cold rolling step 440.
The common temperature for cold rolling ranges from about 75 to
about 140.degree. F. (i.e., from about 24 to about 60.degree. C.).
The cooling time typically is about 48 hours. As will be
appreciated, the strip can be force cooled in a significantly
shorter time by injecting the nitrogen gas into the batch annealing
oven to reduce the sheet temperatures to about 250.degree. F.
(i.e., about 121.degree. C.). However, the strip is commonly not
subjected to solution heat treatment.
[0133] Finally, a final cold rolling step 440 is used to impart the
final properties to a final cold rolled strip 444. Generally, the
final gauge is specified and therefore the desired percent
reduction for the final cold rolling step 440 is determined. The
percent reductions in the other cold rolling steps and the hot
rolling step are back calculated based upon the final desired
gauge. As noted, the back calculation is performed such that the
total cold mill reductions before the first intermediate annealing
step 416, between the first and second intermediate annealing steps
416 and 432, and after the second intermediate annealing step 432
are each less than the level required to realize full hard
conditions.
[0134] In a common embodiment, the total reduction to final gauge
is from about 40% to 70%, more commonly from about 50% to about 60%
and even more commonly from about 55% to about 65% in the step.
Commonly, the reduction is realized through a single pass. When the
strip is fabricated for drawn and ironed container bodies, the
final gauge can be, for example, from about 0.010 to about 0.014
inches. The final cold rolling step is commonly conducted at a
temperature ranging from about 75 to about 120.degree. F. (i.e.,
from about 24 to about 49.degree. C.) (incoming strip
temperature).
[0135] The process can optionally include a stabilizing anneal step
452 to impart desired properties to the aluminum alloy sheet 448.
The stabilizing anneal step 452 can be performed in either a batch
or continuous heater. As noted above, the continuous heater can
include an induction heater. The temperature for the stabilizing
anneal commonly ranges from about 248 to about 401.degree. F.
(i.e., from about 120 to about 205.degree. C.) and more commonly
from about 293 to about 347.degree. F. (i.e., from about 145 to
about 175.degree. C.) (for a batch heater) and commonly ranges from
about 293 to about 500.degree. F. (i.e., from about 145 to about
260.degree. C.) and more commonly from about from about 392 to
about 455.degree. F. (i.e., 200 to about 235.degree. C.) (for a
continuous heater).
[0136] The aluminum alloy sheet 448 produced from the above-noted
alloy by this process is especially useful for drawn and ironed
container bodies. When the aluminum alloy sheet is to be fabricated
into drawn and ironed container bodies, the alloy sheet commonly
has an as-rolled yield strength of at least about 32.5 ksi, more
commonly at least about 33.5 ksi, and even more commonly at least
about 34 ksi. The maximum as-rolled yield strength is commonly no
more than about 38.5 ksi, more commonly no more than about 37.5
ksi, and even more commonly no more than about 37 ksi. Commonly,
the after-bake yield strength is at least about 32.5 ksi, more
commonly at least about 33.5 ksi, and even more commonly is at
least about 34.0 ksi, and commonly not greater than about 38.5 ksi,
more commonly than about 37.5 ksi, and even more commonly than
about 37 ksi. The aluminum alloy sheet commonly has an as-rolled
ultimate tensile strength of at least about 36 ksi, more commonly
at least about 37 ksi and even more commonly at least about 38 ksi
and commonly no more than about 44 ksi, more commonly no more than
about 43 ksi, and even more commonly no more than about 42 ksi. The
after-bake ultimate tensile strength is commonly at least about 36
ksi, more commonly at least about 37 ksi and even more commonly at
least about 38 ksi and commonly no more than about 44 ksi, more
commonly no more than about 43 ksi, and even more commonly no more
than about 42 ksi. The sheet commonly has an after-bake elongation
of more than about 2%, more commonly at least about 2.5%, more
commonly at least about 3%, more commonly at least about 3.5%, and
even more commonly at least about 4% but commonly not more than
about 7% and even more commonly not more than about 6%. The
elongation typically ranges from about 4% to about 6%. Further,
container bodies fabricated from the alloy of the present
disclosure have a minimum dome reversal strength of at least about
90 psi and more commonly at least about 95 psi at current
commercial thickness.
[0137] A number of variations and modifications of the disclosure
can be used. It would be possible to provide for some features of
the disclosure without providing others.
[0138] The present disclosure, in various aspects, embodiments, and
configurations, includes components, methods, processes, systems
and/or apparatus substantially as depicted and described herein,
including various aspects, embodiments, configurations,
subcombinations, and subsets thereof. Those of skill in the art
will understand how to make and use the various aspects, aspects,
embodiments, and configurations, after understanding the present
disclosure. The present disclosure, in various aspects,
embodiments, and configurations, includes providing devices and
processes in the absence of items not depicted and/or described
herein or in various aspects, embodiments, and configurations
hereof, including in the absence of such items as may have been
used in previous devices or processes, e.g., for improving
performance, achieving ease and\or reducing cost of
implementation.
[0139] The foregoing discussion of the disclosure has been
presented for purposes of illustration and description. The
foregoing is not intended to limit the disclosure to the form or
forms disclosed herein. In the foregoing Detailed Description for
example, various features of the disclosure are grouped together in
one or more, aspects, embodiments, and configurations for the
purpose of streamlining the disclosure. The features of the
aspects, embodiments, and configurations of the disclosure may be
combined in alternate aspects, embodiments, and configurations
other than those discussed above. This method of disclosure is not
to be interpreted as reflecting an intention that the claimed
disclosure requires more features than are expressly recited in
each claim. Rather, as the following claims reflect, inventive
aspects lie in less than all features of a single foregoing
disclosed aspects, embodiments, and configurations. Thus, the
following claims are hereby incorporated into this Detailed
Description, with each claim standing on its own as a separate
common embodiment of the disclosure. Moreover, though the
description of the disclosure has included description of one or
more aspects, embodiments, or configurations and certain variations
and modifications, other variations, combinations, and
modifications are within the scope of the disclosure, e.g., as may
be within the skill and knowledge of those in the art, after
understanding the present disclosure. It is intended to obtain
rights which include alternative aspects, embodiments, and
configurations to the extent permitted, including alternate,
interchangeable and/or equivalent structures, functions, ranges or
steps to those claimed, whether or not such alternate,
interchangeable and/or equivalent structures, functions, ranges or
steps are disclosed herein, and without intending to publicly
dedicate any patentable subject matter.
* * * * *