U.S. patent application number 16/168146 was filed with the patent office on 2019-04-25 for high-strength, highly formable aluminum alloys and methods of making the same.
This patent application is currently assigned to Novelis Inc.. The applicant listed for this patent is Novelis Inc.. Invention is credited to Sazol Kumar Das, Aude Celine Despois, Rajeev G. Kamat.
Application Number | 20190119799 16/168146 |
Document ID | / |
Family ID | 64110304 |
Filed Date | 2019-04-25 |
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United States Patent
Application |
20190119799 |
Kind Code |
A1 |
Das; Sazol Kumar ; et
al. |
April 25, 2019 |
HIGH-STRENGTH, HIGHLY FORMABLE ALUMINUM ALLOYS AND METHODS OF
MAKING THE SAME
Abstract
Described herein are high-strength, highly formable aluminum
alloys and methods of making and processing such alloys. The
aluminum alloys described herein contain transition metal alloying
elements to provide high strength and high formability. The
processing method includes multi-stage homogenization, hot and cold
rolling, and solutionization steps. Also described are methods of
using the aluminum alloys.
Inventors: |
Das; Sazol Kumar; (Acworth,
GA) ; Despois; Aude Celine; (Grone, CH) ;
Kamat; Rajeev G.; (Marietta, GA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Novelis Inc. |
Atlanta |
GA |
US |
|
|
Assignee: |
Novelis Inc.
Atlanta
GA
|
Family ID: |
64110304 |
Appl. No.: |
16/168146 |
Filed: |
October 23, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62575573 |
Oct 23, 2017 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C22C 21/08 20130101;
C22F 1/043 20130101; C22F 1/05 20130101; C22C 21/02 20130101; C22C
21/04 20130101 |
International
Class: |
C22F 1/043 20060101
C22F001/043; C22C 21/04 20060101 C22C021/04 |
Claims
1. An aluminum alloy, comprising 0.8-1.5 wt. % Si, 0.1-0.5 wt. %
Fe, 0.5-1.0 wt. % Cu, 0.5-0.9 wt. % Mg, up to 0.1 wt. % Ti, up to
0.5 wt. % Mn, up to 0.5 wt. % Cr, up to 0.5 wt. % Zr, up to 0.5 wt.
% V, up to 0.15 wt. % impurities, and Al.
2. The aluminum alloy of claim 1, comprising 0.9-1.4 wt. % Si,
0.1-0.35 wt. % Fe, 0.6-0.9 wt. % Cu, 0.6-0.9 wt. % Mg, 0.01-0.09
wt. % Ti, up to 0.3 wt. % Mn, up to 0.3 wt. % Cr, up to 0.3 wt. %
Zr, up to 0.3 wt. % V, up to 0.15 wt. % impurities, and Al.
3. The aluminum alloy of claim 1, comprising 1.0-1.3 wt. % Si,
0.1-0.25 wt. % Fe, 0.7-0.9 wt. % Cu, 0.6-0.8 wt. % Mg, 0.01-0.05
wt. % Ti, up to 0.2 wt. % Mn, up to 0.2 wt. % Cr, up to 0.2 wt. %
Zr, up to 0.2 wt. % V, up to 0.15 wt. % impurities, and Al.
4. The aluminum alloy of claim 1, wherein the aluminum alloy
comprises at least one of Mn, Cr, Zr, and V.
5. The aluminum alloy of claim 4, wherein a combined content of Mn,
Cr, Zr, and/or V is at least 0.14 wt. %.
6. The aluminum alloy of claim 5, wherein the combined content of
Mn, Cr, Zr, and/or V is from 0.14 wt. %-0.4 wt. %.
7. The aluminum alloy of claim 6, wherein the combined content of
Mn, Cr, Zr, and/or V is from 0.15 wt. %-0.25 wt. %.
8. The aluminum alloy of claim 1, wherein the aluminum alloy
comprises 0.01-0.3 wt. % V.
9. The aluminum alloy of claim 1, wherein the aluminum alloy
comprises excess Si and wherein an excess Si content is from
0.01-1.0.
10. An aluminum alloy product, comprising 0.8-1.5 wt. % Si, 0.1-0.5
wt. % Fe, 0.5-1.0 wt. % Cu, 0.5-0.9 wt. % Mg, up to 0.1 wt. % Ti,
up to 0.5 wt. % Mn, up to 0.5 wt. % Cr, up to 0.5 wt. % Zr, up to
0.5 wt. % V, up to 0.15 wt. % impurities, and Al.
11. The aluminum alloy product of claim 10, wherein the aluminum
alloy product comprises a rotated cube crystallographic texture at
a volume percent of at least 5%.
12. The aluminum alloy product of claim 10, wherein the aluminum
alloy product comprises dispersoids in an amount of at least
1,500,000 dispersoids per mm.sup.2.
13. The aluminum alloy product of claim 12, wherein the dispersoids
occupy an area ranging from 0.5% to 5% of the aluminum alloy
product.
14. The aluminum alloy product of claim 10, wherein the aluminum
alloy product comprises Fe-constituents.
15. The aluminum alloy product of claim 14, wherein the
Fe-constituents comprise Al(Fe,X)Si phase particles.
16. The aluminum alloy product of claim 14, wherein an average
particle size of the Fe-constituents is up to 4 .mu.m.
17. The aluminum alloy product of claim 10, wherein the aluminum
alloy product comprises a yield strength of at least 300 MPa when
in a T6 temper.
18. The aluminum alloy product of claim 10, wherein the aluminum
alloy product comprises a uniform elongation of at least 20% and a
minimum bend angle of at least 120.degree. when in a T4 temper.
19. A method of producing an aluminum alloy product, comprising:
casting an aluminum alloy comprising 0.8-1.5 wt. % Si, 0.1-0.5 wt.
% Fe, 0.5-1.0 wt. % Cu, 0.5-0.9 wt. % Mg, up to 0.1 wt. % Ti, up to
0.5 wt. % Mn, up to 0.5 wt. % Cr, up to 0.5 wt. % Zr, up to 0.5 wt.
% V, up to 0.15 wt. % impurities, and Al to provide a cast article;
homogenizing the cast article in a two-stage homogenization
process, wherein the two-stage homogenization process comprises
heating the cast article to a first stage homogenization
temperature and holding the cast article at the first stage
homogenization temperature for a period of time and further heating
the cast article to a second stage homogenization temperature and
holding the cast article at the second stage homogenization
temperature for a period of time; hot rolling and cold rolling to
provide a final gauge aluminum alloy product; solution heat
treating the final gauge aluminum alloy product; and pre-aging the
final gauge aluminum alloy product.
20. The method of claim 19, wherein the first stage homogenization
temperature is from 470.degree. C. to 530.degree. C. and the second
stage homogenization temperature is from 525.degree. C. to
575.degree. C., and wherein the second stage homogenization
temperature is higher than the first stage homogenization
temperature.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Application No. 62/575,573, filed Oct. 23, 2017, which is
incorporated herein by reference in its entirety.
FIELD
[0002] The present disclosure relates to the fields of material
science, materials chemistry, metal manufacturing, aluminum alloys,
and aluminum manufacturing. In particular, the present disclosure
relates to high-strength and highly formable aluminum alloys and
methods of making and processing the same.
BACKGROUND
[0003] Aluminum alloys can exhibit high strength due, in part, to
the elemental content of the alloys. For example, high strength
6xxx series aluminum alloys can be prepared by including high
concentrations of certain elements, such as magnesium (Mg), silicon
(Si), and/or copper (Cu). However, such aluminum alloys containing
high concentrations of these elements display poor formability
properties. In particular, precipitates can form along grain
boundaries in an aluminum matrix. Precipitate formation along grain
boundaries can increase strength in the alloy but negatively affect
alloy deformation (e.g., reduce bendability, formability, or any
suitable desired deformation). In addition, the alloys can exhibit
reduced yield strength after artificial aging.
SUMMARY
[0004] 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
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.
[0005] Described herein are aluminum alloys comprising about
0.8-1.5 wt. % Si, 0.1-0.5 wt. % Fe, 0.5-1.0 wt. % Cu, 0.5-0.9 wt. %
Mg, up to 0.1 wt. % Ti, up to 0.5 wt. % Mn, up to 0.5 wt. % Cr, up
to 0.5 wt. % Zr, up to 0.5 wt. % V, up to 0.15 wt. % impurities,
and Al. In some cases, the aluminum alloys can comprise about
0.9-1.4 wt. % Si, 0.1-0.35 wt. % Fe, 0.6-0.9 wt. % Cu, 0.6-0.9 wt.
% Mg, 0.01-0.09 wt. % Ti, up to 0.3 wt. % Mn, up to 0.3 wt. % Cr,
up to 0.3 wt. % Zr, up to 0.3 wt. % V, up to 0.15 wt. % impurities,
and Al. In some cases, the aluminum alloys can comprise about
1.0-1.3 wt. % Si, 0.1-0.25 wt. % Fe, 0.7-0.9 wt. % Cu, 0.6-0.8 wt.
% Mg, 0.01-0.05 wt. % Ti, up to 0.2 wt. % Mn, up to 0.2 wt. % Cr,
up to 0.2 wt. % Zr, up to 0.2 wt. % V, up to 0.15 wt. % impurities,
and Al. Optionally, the aluminum alloy comprises at least one of
Mn, Cr, Zr, and V. In some examples, a combined content of Mn, Cr,
Zr, and/or V is at least about 0.14 wt. % (e.g., from about 0.14
wt. % to about 0.4 wt. % or from about 0.15 wt. % to about 0.25 wt.
%). Optionally, the aluminum alloy comprises about 0.01-0.3 wt. %
V. In some examples, the aluminum alloy comprises excess Si and the
excess Si content is from about 0.01 to about 1.0.
[0006] Also described herein are aluminum alloy products comprising
the aluminum alloy as described herein. Optionally, the aluminum
alloy products comprise a rotated cube crystallographic texture at
a volume percent of at least about 5%. The aluminum alloy products
can comprise dispersoids. Optionally, the dispersoids are present
in the aluminum alloy in an amount of at least about 1,500,000
dispersoids per mm.sup.2. Optionally, the dispersoids occupy an
area ranging from about 0.5% to about 5% of the aluminum alloy
products. In some cases, the aluminum alloy products comprises
Fe-constituents. The Fe-constituents can comprise Al(Fe,X)Si phase
particles. Optionally, the average particle size of the
Fe-constituents is up to about 4 .mu.m. The aluminum alloy products
can exhibit a yield strength of at least about 300 MPa when in a T6
temper and/or a uniform elongation of at least about 20% and a
minimum bend angle of at least about 120.degree. when in a T4
temper.
[0007] Further described herein are methods of producing an
aluminum alloy product. The methods comprise casting an aluminum
alloy as described herein to provide a cast article, homogenizing
the cast article in a two-stage homogenization process, hot rolling
and cold rolling the cast article to provide a final gauge aluminum
alloy product, solution heat treating the final gauge aluminum
alloy product, and pre-aging the final gauge aluminum alloy
product. The two-stage homogenization process can comprise heating
the cast article to a first stage homogenization temperature and
holding the cast article at the first stage homogenization
temperature for a period of time and further heating the cast
article to a second stage homogenization temperature and holding
the cast article at the second stage homogenization temperature for
a period of time. Optionally, the first stage homogenization
temperature is from about 470.degree. C. to about 530.degree. C.
and the second stage homogenization temperature is from about
525.degree. C. to about 575.degree. C. In some examples, the second
stage homogenization temperature is higher than the first stage
homogenization temperature.
[0008] Further aspects, objects, and advantages will become
apparent upon consideration of the detailed description and figures
that follow.
BRIEF DESCRIPTION OF THE FIGURES
[0009] FIG. 1 is a graph showing tensile properties of aluminum
alloys according to certain aspects of the present disclosure.
[0010] FIG. 2 is a micrograph showing the grain structure of
aluminum alloys according to certain aspects of the present
disclosure.
[0011] FIG. 3 is a graph showing mechanical properties of aluminum
alloys according to certain aspects of the present disclosure.
[0012] FIG. 4 is a graph showing mechanical properties of aluminum
alloys according to certain aspects of the present disclosure.
[0013] FIG. 5 is a graph showing mechanical properties of aluminum
alloys according to certain aspects of the present disclosure.
[0014] FIG. 6 is a graph showing the distribution of
recrystallization textures of aluminum alloys according to certain
aspects of the present disclosure.
[0015] FIG. 7 is a series of micrographs of aluminum alloys
according to certain aspects of the present disclosure.
[0016] FIG. 8 is a graph showing dispersoid number density and
dispersoid area fraction of aluminum alloys according to certain
aspects of the present disclosure.
[0017] FIG. 9 is a series of micrographs of aluminum alloys
according to certain aspects of the present disclosure.
[0018] FIG. 10 is a graph showing size distribution of
Fe-constituents of aluminum alloys according to certain aspects of
the present disclosure.
[0019] FIG. 11 is a series of micrographs of aluminum alloys
according to certain aspects of the present disclosure.
DETAILED DESCRIPTION
[0020] Described herein are novel aluminum alloys and products and
methods of preparing the same. The alloys exhibit high strength and
high formability. As further described herein, solute elements,
including Cu, Mg, and Si, are combined with transition elements
(e.g., Mn, Cr, Zn, and V) for a synergistic effect of increasing
both the strength and formability of the alloys. The transition
elements aid in preventing precipitate formation along grain
boundaries in the aluminum alloys, as further described below. In
addition, the processing methods used to prepare the alloys and
products contribute to the high strength and formability exhibited
by the alloys and products.
Definitions and Descriptions
[0021] 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.
[0022] In this description, reference is made to alloys identified
by aluminum industry designations, such as "series" or "AA6xxx."
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.
[0023] As used herein, the meaning of "a," "an," or "the" includes
singular and plural references unless the context clearly dictates
otherwise.
[0024] As used herein, the meaning of "room temperature" can
include a temperature of from about 15.degree. C. to about
30.degree. C., for example about 15.degree. C., about 16.degree.
C., about 17.degree. C., about 18.degree. C., about 19.degree. C.,
about 20.degree. C., about 21.degree. C., about 22.degree. C.,
about 23.degree. C., about 24.degree. C., about 25.degree. C.,
about 26.degree. C., about 27.degree. C., about 28.degree. C.,
about 29.degree. C., or about 30.degree. C.
[0025] 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 15 mm, greater than 20
mm, greater than 25 mm, greater than 30 mm, greater than 35 mm,
greater than 40 mm, greater than 45 mm, greater than 50 mm, or
greater than 100 mm.
[0026] 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 4 mm, 5 mm, 6 mm, 7 mm, 8
mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, or 15 mm.
[0027] As used herein, a sheet generally refers to an aluminum
alloy product having a thickness of less than about 4 mm. For
example, a sheet may have a thickness of less than 4 mm, less than
3 mm, less than 2 mm, less than 1 mm, less than 0.5 mm, less than
0.3 mm, or less than 0.1 mm.
[0028] As used herein, terms such as "cast metal article," "cast
article," "cast aluminum alloy," and the like are interchangeable
and refer to a product produced by direct chill casting (including
direct chill co-casting) or semi-continuous casting, continuous
casting (including, for example, by use of a twin belt caster, a
twin roll caster, a block caster, or any other continuous caster),
electromagnetic casting, hot top casting, or any other casting
method.
[0029] Reference is made in this application to alloy condition or
temper. For an understanding of the alloy temper descriptions most
commonly used, see "American National Standards (ANSI) H35 on Alloy
and Temper Designation Systems." An F condition or temper refers to
an aluminum alloy as fabricated. An O condition or temper refers to
an aluminum alloy after annealing. A T1 condition or temper refers
to an aluminum alloy cooled from hot working and naturally aged
(e.g., at room temperature). A T2 condition or temper refers to an
aluminum alloy cooled from hot working, cold worked and naturally
aged. A T3 condition or temper refers to an aluminum alloy solution
heat treated, cold worked, and naturally aged. A T4 condition or
temper refers to an aluminum alloy solution heat treated and
naturally aged. A T5 condition or temper refers to an aluminum
alloy cooled from hot working and artificially aged (at elevated
temperatures). A T6 condition or temper refers to an aluminum alloy
solution heat treated and artificially aged. A T7 condition or
temper refers to an aluminum alloy solution heat treated and
artificially overaged. A T8x condition or temper refers to an
aluminum alloy solution heat treated, cold worked, and artificially
aged. A T9 condition or temper refers to an aluminum alloy solution
heat treated, artificially aged, and cold worked.
[0030] 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.
Alloy Compositions
[0031] Described herein are novel aluminum alloys. The alloys
exhibit high strength and high formability. In some cases, the
properties of the alloys can be achieved due to the elemental
composition of the alloys. The aluminum alloys can be precipitation
hardened or precipitation hardenable alloys. Optionally, the
aluminum alloys can be aluminum alloys classified as 2xxx series
aluminum alloys (e.g., wherein copper is a predominant alloying
element), 6xxx series aluminum alloys (e.g., wherein magnesium and
silicon are predominant alloying elements), or 7xxx series aluminum
alloys (e.g., wherein zinc is a predominant alloying element). In
some cases, the aluminum alloys can be modified 2xxx series, 6xxx
series, or 7xxx series aluminum alloys. As used herein, the term
"modified" as related to a series of aluminum alloys refers to an
alloy composition that would typically be classified within a
particular series, but the modification of one or more elements
(types or amounts) results in a different predominant alloying
element. For example, a modified 6xxx series aluminum alloy can
refer to an aluminum alloy in which copper and silicon are the
predominant alloying elements rather than magnesium and
silicon.
[0032] In some cases, an aluminum alloy can have the following
elemental composition as provided in Table 1:
TABLE-US-00001 TABLE 1 Element Weight Percentage (wt. %) Si 0.8-1.5
Fe 0.1-0.5 Cu 0.5-1.0 Mg 0.5-0.9 Ti 0-0.1 Mn 0-0.5 Cr 0-0.5 Zr
0-0.5 V 0-0.5 Others 0-0.05 (each) 0-0.15 (total) Al
[0033] In other examples, the alloy can have the following
elemental composition as provided in Table 2.
TABLE-US-00002 TABLE 2 Element Weight Percentage (wt. %) Si 0.9-1.4
Fe 0.1-0.3 Cu 0.6-0.9 Mg 0.6-0.9 Ti 0.01-0.09 Mn 0.01-0.3 Cr
0.01-0.3 Zr 0.01-0.3 V 0.01-0.3 Others 0-0.05 (each) 0-0.15 (total)
Al
[0034] In one example, the alloy can have the following elemental
composition as provided in Table 3.
TABLE-US-00003 TABLE 3 Element Weight Percentage (wt. %) Si 1.0-1.3
Fe 0.1-0.25 Cu 0.7-0.9 Mg 0.6-0.8 Ti 0.01-0.05 Mn 0.05-0.2 Cr
0.05-0.2 Zr 0.05-0.2 V 0.05-0.2 Others 0-0.05 (each) 0-0.15 (total)
Al
[0035] In certain examples, the alloy described herein includes
silicon (Si) in an amount from about 0.8% to about 1.5% (e.g., from
about 0.9% to about 1.45%, from about 0.9% to about 1.4%, from
about 0.9% to about 1.35%, from about 0.9% to about 1.3%, from
about 0.9% to about 1.25%, from about 0.9% to about 1.2%, from
about 0.95% to about 1.5%, from about 0.95% to about 1.45%, from
about 0.95% to about 1.4%, from about 0.95% to about 1.35%, from
about 0.95% to about 1.3%, from about 0.95% to about 1.25%, from
about 0.95% to about 1.2%, from about 1.0% to about 1.5%, from
about 1.0% to about 1.45%, from about 1.0% to about 1.4%, from
about 1.0% to about 1.35%, from about 1.0% to about 1.3%, from
about 1.0% to about 1.25%, or from about 1.0% to about 1.2%) based
on the total weight of the alloy. For example, the alloy can
include 0.8%, 0.81%, 0.82%, 0.83%, 0.84%, 0.85%, 0.86%, 0.87%,
0.88%, 0.89%, 0.9%, 0.91%, 0.92%, 0.93%, 0.94%, 0.95%, 0.96%,
0.97%, 0.98%, 0.99%, 1.0%, 1.01%, 1.02%, 1.03%, 1.04%, 1.05%,
1.06%, 1.07%, 1.08%, 1.09%, 1.1%, 1.11%, 1.12%, 1.13%, 1.14%,
1.15%, 1.16%, 1.17%, 1.18%, 1.19%, 1.2%, 1.21%, 1.22%, 1.23%,
1.24%, 1.25%, 1.26%, 1.27%, 1.28%, 1.29%, 1.3%, 1.31%, 1.32%,
1.33%, 1.34%, 1.35%, 1.36%, 1.37%, 1.38%, 1.39%, 1.4%, 1.41%,
1.42%, 1.43%, 1.44%, 1.45%, 1.46%, 1.47%, 1.48%, 1.49%, or 1.5% Si.
All expressed in wt. %.
[0036] In certain aspects, the alloy described herein includes iron
(Fe) in an amount from about 0.1% to about 0.5% (e.g., from about
0.1% to about 0.45%, from about 0.1% to about 0.4%, from about 0.1%
to about 0.35%, from about 0.1% to about 0.3%, from about 0.1% to
about 0.25%, from about 0.1% to about 0.2%, from about 0.15% to
about 0.45%, from about 0.15% to about 0.4%, from about 0.15% to
about 0.35%, from about 0.15% to about 0.3%, from about 0.15% to
about 0.25%, from about 0.15% to about 0.2%, from about 0.2% to
about 0.45%, from about 0.2% to about 0.4%, from about 0.2% to
about 0.35%, from about 0.2% to about 0.3%, from about 0.2% to
about 0.25%, from about 0.25% to about 0.45%, from about 0.25% to
about 0.4%, from about 0.25% to about 0.35%, from about 0.25% to
about 0.3%, from about 0.3% to about 0.45%, from about 0.3% to
about 0.4%, or from about 0.3% to about 0.35%) based on the total
weight of the alloy. For example, the alloy can include 0.1%,
0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%,
0.2%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%,
0.29%, 0.3%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%,
0.38%, 0.39%, 0.4%, 0.41%, 0.42%, 0.43%, 0.44%, 0.45%, 0.46%,
0.47%, 0.48%, 0.49%, or 0.5% Fe. All expressed in wt. %.
[0037] In certain examples, the alloy described herein includes
copper (Cu) in an amount from about 0.5% to about 1.0% (e.g., from
about 0.55% to about 1.0%, from about 0.6% to about 1.0%, from
about 0.65% to about 1.0%, from about 0.7% to about 1.0%, from
about 0.75% to about 1.0%, from about 0.8% to about 1.0%, from
about 0.5% to about 0.95%, from about 0.55% to about 0.95%, from
about 0.6% to about 0.95%, from about 0.65% to about 0.95%, from
about 0.7% to about 0.95%, from about 0.75% to about 0.95%, from
about 0.8% to about 0.95%, from about 0.5% to about 0.9%, from
about 0.55% to about 0.9%, from about 0.6% to about 0.9%, from
about 0.65% to about 0.9%, from about 0.7% to about 0.9%, from
about 0.75% to about 0.9%, from about 0.8% to about 0.9%, from
about 0.5% to about 0.85%, from about 0.55% to about 0.85%, from
about 0.6% to about 0.85%, from about 0.65% to about 0.85%, from
about 0.7% to about 0.85%, from about 0.75% to about 0.85%, from
about 0.8% to about 0.85%, from about 0.5% to about 0.8%, from
about 0.55% to about 0.8%, from about 0.6% to about 0.8%, from
about 0.65% to about 0.8%, from about 0.7% to about 0.8%, or from
about 0.75% to about 0.8%) based on the total weight of the alloy.
For example, the alloy can include 0.5%, 0.51%, 0.52%, 0.53%,
0.54%, 0.55%, 0.56%, 0.57%, 0.58%, 0.59%, 0.6%, 0.61%, 0.62%,
0.63%, 0.64%, 0.65%, 0.66%, 0.67%, 0.68%, 0.69%, 0.7%, 0.71%,
0.72%, 0.73%, 0.74%, 0.75%, 0.76%, 0.77%, 0.78%, 0.79%, 0.8%,
0.81%, 0.82%, 0.83%, 0.84%, 0.85%, 0.86%, 0.87%, 0.88%, 0.89%,
0.9%, 0.91%, 0.92%, 0.93%, 0.94%, 0.95%, 0.96%, 0.97%, 0.98%,
0.99%, or 1.0% Cu. All expressed in wt. %.
[0038] In certain examples, the alloy described herein includes
magnesium (Mg) in an amount from about 0.5% to about 0.9% (e.g.,
from about 0.55% to about 0.9%, from about 0.6% to about 0.9%, from
about 0.65% to about 0.9%, from about 0.7% to about 0.9%, from
about 0.75% to about 0.9%, from about 0.8% to about 0.9%, from
about 0.5% to about 0.85%, from about 0.55% to about 0.85%, from
about 0.6% to about 0.85%, from about 0.65% to about 0.85%, from
about 0.7% to about 0.85%, from about 0.75% to about 0.85%, from
about 0.8% to about 0.85%, from about 0.5% to about 0.8%, from
about 0.55% to about 0.8%, from about 0.6% to about 0.8%, from
about 0.65% to about 0.8%, from about 0.7% to about 0.8%, or from
about 0.75% to about 0.8%) based on the total weight of the alloy.
For example, the alloy can include 0.5%, 0.51%, 0.52%, 0.53%,
0.54%, 0.55%, 0.56%, 0.57%, 0.58%, 0.59%, 0.6%, 0.61%, 0.62%,
0.63%, 0.64%, 0.65%, 0.66%, 0.67%, 0.68%, 0.69%, 0.7%, 0.71%,
0.72%, 0.73%, 0.74%, 0.75%, 0.76%, 0.77%, 0.78%, 0.79%, 0.8%,
0.81%, 0.82%, 0.83%, 0.84%, 0.85%, 0.86%, 0.87%, 0.88%, 0.89%, or
0.9% Mg. All expressed in wt. %.
[0039] In certain aspects, the alloy described herein includes
titanium (Ti) in an amount up to about 0.1% (e.g., from about 0.01%
to about 0.09%, from about 0.02% to about 0.09%, from about 0.03%
to about 0.09%, from about 0.04% to about 0.09%, from about 0.05%
to about 0.09%, from about 0.01% to about 0.08%, from about 0.02%
to about 0.08%, from about 0.03% to about 0.08%, from about 0.04%
to about 0.08%, from about 0.05% to about 0.08%, from about 0.01%
to about 0.07%, from about 0.02% to about 0.07%, from about 0.03%
to about 0.07%, from about 0.04% to about 0.07%, from about 0.05%
to about 0.07%, from about 0.01% to about 0.06%, from about 0.02%
to about 0.06%, from about 0.03% to about 0.06%, from about 0.04%
to about 0.06%, from about 0.05% to about 0.06%, from about 0.01%
to about 0.05%, from about 0.02% to about 0.05%, from about 0.03%
to about 0.05%, or from about 0.04% to about 0.05%) based on the
total weight of the alloy. For example, the alloy can include
0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or
0.1% Ti. In some examples, Ti is not present in the alloy (i.e., 0%
Ti). All expressed in wt. %.
[0040] In certain examples, the alloy described herein includes
manganese (Mn) in an amount up to about 0.5% (e.g., from about
0.01% to about 0.5%, from about 0.01% to about 0.4%, from about
0.01% to about 0.3%, from about 0.01% to about 0.2%, from about
0.01% to about 0.1%, from about 0.06% to about 0.5%, from about
0.06% to about 0.4%, from about 0.06% to about 0.3%, from about
0.06% to about 0.2%, from about 0.06% to about 0.1%, from about
0.1% to about 0.5%, from about 0.1% to about 0.4%, from about 0.1%
to about 0.3%, or from about 0.1% to about 0.2%) based on the total
weight of the alloy. For example, the alloy can include 0.01%,
0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%,
0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%,
0.2%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%,
0.29%, 0.3%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%,
0.38%, 0.39%, 0.4%, 0.41%, 0.42%, 0.43%, 0.44%, 0.45%, 0.46%,
0.47%, 0.48%, 0.49%, or 0.5% Mn. In some examples, Mn is not
present in the alloy (i.e., 0% Mn). All expressed in wt. %.
[0041] In certain aspects, the alloy described herein includes
chromium (Cr) in an amount up to about 0.5% (e.g., from about 0.01%
to about 0.5%, from about 0.01% to about 0.4%, from about 0.01% to
about 0.3%, from about 0.01% to about 0.2%, from about 0.01% to
about 0.1%, from about 0.06% to about 0.5%, from about 0.06% to
about 0.4%, from about 0.06% to about 0.3%, from about 0.06% to
about 0.2%, from about 0.06% to about 0.1%, from about 0.1% to
about 0.5%, from about 0.1% to about 0.4%, from about 0.1% to about
0.3%, or from about 0.1% to about 0.2%) based on the total weight
of the alloy. For example, the alloy can include 0.01%, 0.02%,
0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%,
0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%,
0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%,
0.3%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%,
0.39%, 0.4%, 0.41%, 0.42%, 0.43%, 0.44%, 0.45%, 0.46%, 0.47%,
0.48%, 0.49%, or 0.5% Cr. In some examples, Cr is not present in
the alloy (i.e., 0% Cr). All expressed in wt. %.
[0042] In certain aspects, the alloy described herein includes
zirconium (Zr) in an amount up to about 0.5% (e.g., from about
0.01% to about 0.5%, from about 0.01% to about 0.4%, from about
0.01% to about 0.3%, from about 0.01% to about 0.2%, from about
0.01% to about 0.1%, from about 0.06% to about 0.5%, from about
0.06% to about 0.4%, from about 0.06% to about 0.3%, from about
0.06% to about 0.2%, from about 0.06% to about 0.1%, from about
0.1% to about 0.5%, from about 0.1% to about 0.4%, from about 0.1%
to about 0.3%, or from about 0.1% to about 0.2%) based on the total
weight of the alloy. For example, the alloy can include 0.01%,
0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%,
0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%,
0.2%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%,
0.29%, 0.3%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%,
0.38%, 0.39%, 0.4%, 0.41%, 0.42%, 0.43%, 0.44%, 0.45%, 0.46%,
0.47%, 0.48%, 0.49%, or 0.5% Zr. In certain aspects, Zr is not
present in the alloy (i.e., 0%). All expressed in wt. %.
[0043] In certain aspects, the alloy described herein includes
vanadium (V) in an amount up to about 0.5% (e.g., from about 0.01%
to about 0.5%, from about 0.01% to about 0.4%, from about 0.01% to
about 0.3%, from about 0.01% to about 0.2%, from about 0.01% to
about 0.1%, from about 0.06% to about 0.5%, from about 0.06% to
about 0.4%, from about 0.06% to about 0.3%, from about 0.06% to
about 0.2%, from about 0.06% to about 0.1%, from about 0.1% to
about 0.5%, from about 0.1% to about 0.4%, from about 0.1% to about
0.3%, or from about 0.1% to about 0.2%) based on the total weight
of the alloy. For example, the alloy can include 0.01%, 0.02%,
0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%,
0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%,
0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%,
0.3%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%,
0.39%, 0.4%, 0.41%, 0.42%, 0.43%, 0.44%, 0.45%, 0.46%, 0.47%,
0.48%, 0.49%, or 0.5% V. In certain aspects, V is not present in
the alloy (i.e., 0% V). All expressed in wt. %.
[0044] 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
are not limited to, Ni, Sc, Sn, Ga, Ca, Hf, Sr, or combinations
thereof. Accordingly, Ni, Sc, Sn, Ga, 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
expressed in wt. %. The alloy composition also includes aluminum.
In certain aspects, the remaining percentage of the alloy is
aluminum.
[0045] One non-limiting example of a suitable alloy includes 1.20%
Si, 0.18% Fe, 0.80% Cu, 0.70% Mg, 0.02% Ti, 0.13% Mn, 0.07% Cr, and
up to 0.15% total impurities, with the remainder Al. In some cases,
another non-limiting example of a suitable alloy includes 1.20% Si,
0.18% Fe, 0.80% Cu, 0.70% Mg, 0.02% Ti, 0.14% Cr, and up to 0.15%
total impurities, with the remainder Al. In some cases, another
non-limiting example of a suitable alloy includes 1.20% Si, 0.18%
Fe, 0.80% Cu, 0.70% Mg, 0.02% Ti, 0.07% Cr, 0.11% Zr, and up to
0.15% total impurities, with the remainder Al. In some cases,
another non-limiting example of a suitable alloy includes 1.20 Si,
0.18% Fe, 0.80% Cu, 0.70% Mg, 0.02% Ti, 0.08% Cr, 0.11% V, and up
to 0.15% total impurities, with the remainder Al. In some cases,
another non-limiting example of a suitable alloy includes 1.20% Si,
0.18% Fe, 0.80% Cu, 0.70% Mg, 0.02% Ti, 0.09% Zr, 0.10% V, and up
to 0.15% total impurities, with the remainder Al. In some cases,
another non-limiting example of a suitable alloy includes 1.20% Si,
0.18% Fe, 0.80% Cu, 0.70% Mg, 0.02% Ti, 0.09% Mn, 0.10% V, and up
to 0.15% total impurities, with the remainder Al.
Alloy Microstructure and Properties
[0046] In certain aspects, the Si, Mg, and Cu content and ratios
are controlled to enhance strength and formability. Optionally, the
transition element (e.g., Mn, Cr, Zr, and/or V) content is
controlled to enhance strength and formability.
[0047] In some cases, the alloy described herein includes excess
Si. Optionally, the Si and Mg content are controlled such that
excess Si is present in the alloy as described herein. Excess Si
content can be calculated according to the method described in U.S.
Pat. No. 4,614,552, col. 4, lines 49-52, which is incorporated
herein by reference. Briefly, Mg and Si combine as Mg.sub.2Si,
imparting a considerable strength improvement after age-hardening.
In addition, Si-containing constituents, such as Al(FeMn)Si, can
form. Excess Si is present when the Si content is above the
stoichiometric ratio of Mg.sub.2Si and above the amount included in
Al(FeMn)Si constituents. The excess Si content can be calculated by
subtracting from the total Si content the Si needed for Mg.sub.2Si
(Mg/1.73) and the Fe-containing phase (Fe/3). The excess Si content
can be 1.0 or less (e.g., from about 0.01 to about 1.0, from about
0.1 to about 0.9, or from about 0.5 to 0.8). For example, the
excess Si content can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07,
0.08, 0.09, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50,
0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.0, or
anywhere in between.
[0048] In some aspects, the alloys described herein include at
least one transition element (e.g., at least one of Mn, Cr, Zr,
and/or V). Optionally, the combined content of the transition
elements in the alloys described herein is at least about 0.14 wt.
%. For example, the combined content of Mn, Cr, Zr, and/or V can be
from about 0.14 wt. % to about 0.40 wt. % (e.g., from about 0.15
wt. % to about 0.35 wt. % or from about 0.25 wt. % to about 0.30
wt. %). In some cases, the combined content of Mn, Cr, Zr, and/or V
is about 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%, 0.21%,
0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.3%,
0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, or
0.4%. In some cases, one or more of the transition elements may not
be present, as long as the total weight percentage of the present
transition elements is at least 0.14 wt. %.
[0049] The presence of one or more of the transition elements, such
as Mn, Cr, Zr, and/or V, can advantageously form dispersoids during
the processing methods described herein, such as during the
homogenization step. The dispersoids can function as heterogeneous
nucleation sites for precipitates during processing steps, such as
during the solution heat treatment step. In certain aspects, grain
boundary (GB) precipitation occurs due to GB misorientation that is
favorable for precipitate nucleation. The dispersoids reduce or
eliminate GB precipitates and also reduce strain localization, thus
diffusing strain distribution during deformation. The reduced or
eliminated GB precipitates and/or the diffused strain distribution
during deformation result in an improved bendability of the
resulting alloys and alloy products.
[0050] In some non-limiting examples, the dispersoids described
herein can contain Al and one or more of the alloying elements
found in the alloy composition as described above. In some
examples, the dispersoids can have a composition according to one
or more of the following formulae: AlX, AlXX, AlXSi, Al(Fe,X),
Al(Fe,X)Si, or the like, wherein each X is selected from the group
consisting of Fe, Si, Mn, Cr, V, or Zr.
[0051] The dispersoid average size and distribution are important
factors that result in the desirable strength and formability
properties displayed by the alloys and alloy products described
herein. The size and distribution are influenced by the presence of
transition elements, as described above, and also by the methods of
processing the alloys, as further described below. In some
examples, the dispersoids can be present in the aluminum alloy in
an average amount of at least about 1,500,000 dispersoids per
square millimeter (mm.sup.2). For example, the dispersoids can be
present in an amount of at least about 1,600,000 dispersoids per
mm.sup.2, at least about 1,700,000 dispersoids per mm.sup.2, at
least about 1,800,000 dispersoids per mm.sup.2, at least about
1,900,000 dispersoids per mm.sup.2, at least about 2,000,000
dispersoids per mm.sup.2, at least about 2,100,000 dispersoids per
mm.sup.2, at least about 2,200,000 dispersoids per mm.sup.2, at
least about 2,300,000 dispersoids per mm.sup.2, at least about
2,400,000 dispersoids per mm.sup.2, at least about 2,500,000
dispersoids per mm.sup.2, at least about 2,600,000 dispersoids per
mm.sup.2, at least about 2,700,000 dispersoids per mm.sup.2, at
least about 2,800,000 dispersoids per mm.sup.2, at least about
2,900,000 dispersoids per mm.sup.2, or at least about 3,000,000
dispersoids per mm.sup.2. In some examples, the average number of
dispersoids present in the aluminum alloy can be from about
1,500,000 dispersoids per mm.sup.2 to about 5,000,000 dispersoids
per mm.sup.2 (e.g., from about 1,750,000 dispersoids per mm.sup.2
to about 4,750,000 dispersoids per mm.sup.2 or from about 2,000,000
dispersoids per mm.sup.2 to about 4,500,000 dispersoids per
mm.sup.2). The dispersoids in the aluminum alloy can occupy an area
ranging from about 0.5% to about 5% of the alloy (e.g., from about
1% to about 4% or from about 1.5% to about 2.5% of the alloy).
[0052] Optionally, the dispersoids can have an average diameter of
from about 10 nm to about 600 nm (e.g., from about 50 nm to about
500 nm, from about 100 nm to about 450 nm, from about 200 nm to
about 400 nm, from about 10 nm to about 200 nm, or from about 500
nm to about 600 nm). For example, the dispersoids can have a
diameter of about 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm,
80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160
nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm,
250 nm, 260 nm, 270 nm, 280 nm, 290 nm, 300 nm, 310 nm, 320 nm, 330
nm, 340 nm, 350 nm, 360 nm, 370 nm, 380 nm, 390 nm, 400 nm, 410 nm,
420 nm, 430 nm, 440 nm, 450 nm, 460 nm, 470 nm, 480 nm, 490 nm, 500
nm, 510 nm, 520 nm, 530 nm, 540 nm, 550 nm, 560 nm, 570 nm, 580 nm,
590 nm, 600 nm, or anywhere in between.
[0053] The alloys described herein also include Fe-constituents,
which are also referred to herein as Fe-containing particles.
Optionally, in addition to Fe, the Fe-constituents can include one
or more of Al, Mn, Si, Cu, Ti, Zr, Cr, and/or Mg. In some examples,
the Fe-constituents can be Al(Fe,X)Si phase particles, wherein X
can be Mn, Cr, Zr, and/or V, and/or AlFeSi phase particles. For
example, the Fe-constituents can include one or more of Al.sub.3Fe,
Al.sub.x(Fe,Mn), Al.sub.3Fe, Al.sub.12(Fe,Mn).sub.3Si,
Al.sub.7Cu.sub.2Fe, Al(Fe,Mn).sub.2Si.sub.3, Al.sub.x(Mn,Fe), and
Al.sub.12(Mn,Fe).sub.3Si. The presence of the transition elements
described herein results in the transformation of AlFeSi particles
into Al(Fe,X)Si particles. In some examples, the number of
Al(Fe,X)Si phase particles, which are spheroid particles, is
greater than the number of AlFeSi phase particles, which are flake
or needle type particles. Optionally, at least 50% of the
Fe-constituents are present as Al(Fe,X)Si particles (e.g., at least
55%, at least 60%, at least 65%, at least 70%, at least 75%, at
least 80%, at least 85%, at least 90%, or at least 95% of the
Fe-constituents are present as Al(Fe,X)Si particles). The
Fe-constituents can have an average particle size of up to about 4
.mu.m. For example, the Fe-constituents, on average, can range in
size from about 0.1 .mu.m to about 4 .mu.m (e.g., from about 0.5
.mu.m to about 3.5 .mu.m or from about 1 .mu.m to about 3
.mu.m).
[0054] Optionally, the Cr, Mn, Zr, and/or V content and ratios are
controlled to form the desired size, type, and distribution of
dispersoids, which leads to improved formability and strength. In
some non-limiting examples, a ratio of Cr to Mn (also referred to
herein as the Cr/Mn ratio) can be from about 0.15:1 to about 0.7:1
(e.g., from about 0.3:1 to about 0.6:1 or from about 0.4:1 to about
0.55:1). For example, the Cr/Mn ratio can be about 0.15:1, 0.16:1,
0.17:1, 0.18:1, 0.19:1, 0.20:1, 0.21:1, 0.22:1, 0.23:1, 0.24:1,
0.25:1, 0.26:1, 0.27:1, 0.28:1, 0.29:1, 0.30:1, 0.31:1, 0.32:1,
0.33:1, 0.34:1, 0.35:1, 0.36:1, 0.37:1, 0.38:1, 0.39:1, 0.40:1,
0.41:1, 0.42:1, 0.43:1, 0.44:1, 0.45:1, 0.46:1, 0.47:1, 0.48:1,
0.49:1, 0.50:1, 0.51:1, 0.52:1, 0.53:1, 0.54:1, 0.55:1, 0.56:1,
0.57:1, 0.58:1, 0.59:1, 0.60:1, 0.61:1, 0.62:1, 0.63:1, 0.64:1,
0.65:1, 0.66:1, 0.67:1, 0.68:1, 0.69:1, or 0.70:1.
[0055] In some non-limiting examples, a ratio of Cr to V (also
referred to herein as the Cr/V ratio) can be from about 0.5:1 to
about 1.5:1 (e.g., from about 0.6:1 to about 1.4:1 or from about
0.7:1 to about 1.3:1). For example, the Cr/V ratio can be about
0.50:1, 0.51:1, 0.52:1, 0.53:1, 0.54:1, 0.55:1, 0.56:1, 0.57:1,
0.58:1, 0.59:1, 0.60:1, 0.61:1, 0.62:1, 0.63:1, 0.64:1, 0.65:1,
0.66:1, 0.67:1, 0.68:1, 0.69:1, 0.70:1, 0.71:1, 0.72:1, 0.73:1,
0.74:1, 0.75:1, 0.76:1, 0.77:1, 0.78:1, 0.79:1, 0.80:1, 0.81:1,
0.82:1, 0.83:1, 0.84:1, 0.85:1, 0.86:1, 0.87:1, 0.88:1, 0.89:1,
0.90:1, 0.91:1, 0.92:1, 0.93:1, 0.94:1, 0.95:1, 0.96:1, 0.97:1,
0.98:1, 0.99:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, or 1.5:1.
[0056] In some non-limiting examples, a ratio of Cr to Zr (also
referred to herein as the Cr/Zr ratio) can be from about 0.5:1 to
about 1.5:1 (e.g., from about 0.6:1 to about 1.4:1 or from about
0.7:1 to about 1.3:1). For example, the Cr/Zr ratio can be about
0.50:1, 0.51:1, 0.52:1, 0.53:1, 0.54:1, 0.55:1, 0.56:1, 0.57:1,
0.58:1, 0.59:1, 0.60:1, 0.61:1, 0.62:1, 0.63:1, 0.64:1, 0.65:1,
0.66:1, 0.67:1, 0.68:1, 0.69:1, 0.70:1, 0.71:1, 0.72:1, 0.73:1,
0.74:1, 0.75:1, 0.76:1, 0.77:1, 0.78:1, 0.79:1, 0.80:1, 0.81:1,
0.82:1, 0.83:1, 0.84:1, 0.85:1, 0.86:1, 0.87:1, 0.88:1, 0.89:1,
0.90:1, 0.91:1, 0.92:1, 0.93:1, 0.94:1, 0.95:1, 0.96:1, 0.97:1,
0.98:1, 0.99:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, or 1.5:1.
[0057] In some non-limiting examples, a ratio of V to Mn (also
referred to herein as the V/Mn ratio) can be from about 0.8:1 to
about 1.4:1 (e.g., from about 0.9:1 to about 1.3:1 or from about
0.9:1 to about 1.2:1). For example, the V/Mn ratio can be about
0.80:1, 0.81:1, 0.82:1, 0.83:1, 0.84:1, 0.85:1, 0.86:1, 0.87:1,
0.88:1, 0.89:1, 0.90:1, 0.91:1, 0.92:1, 0.93:1, 0.94:1, 0.95:1,
0.96:1, 0.97:1, 0.98:1, 0.99:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, or
1.4:1.
[0058] In some non-limiting examples, a ratio of V to Zr (also
referred to herein as the V/Zr ratio) can be from about 0.8:1 to
about 1.4:1 (e.g., from about 0.9:1 to about 1.3:1 or from about
0.9:1 to about 1.2:1). For example, the V/Zr ratio can be about
0.80:1, 0.81:1, 0.82:1, 0.83:1, 0.84:1, 0.85:1, 0.86:1, 0.87:1,
0.88:1, 0.89:1, 0.90:1, 0.91:1, 0.92:1, 0.93:1, 0.94:1, 0.95:1,
0.96:1, 0.97:1, 0.98:1, 0.99:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, or
1.4:1.
[0059] In some non-limiting examples, a ratio of V to Cr (also
referred to herein as the V/Cr ratio) can be from about 0.8:1 to
about 1.4:1 (e.g., from about 0.9:1 to about 1.3:1 or from about
0.9:1 to about 1.2:1). For example, the V/Cr ratio can be about
0.80:1, 0.81:1, 0.82:1, 0.83:1, 0.84:1, 0.85:1, 0.86:1, 0.87:1,
0.88:1, 0.89:1, 0.90:1, 0.91:1, 0.92:1, 0.93:1, 0.94:1, 0.95:1,
0.96:1, 0.97:1, 0.98:1, 0.99:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, or
1.4:1.
[0060] The mechanical properties of the aluminum alloy can be
controlled by various aging conditions depending on the desired
use. As one example, the alloy can be produced (or provided) in a
T4 temper or a T6 temper. In some non-limiting examples, the
proposed alloy has very high formability and bendability in the T4
temper and very high strength in the T6 temper. In certain aspects,
the aluminum alloy may have a T4 yield strength ranging from about
150 MPa to about 250 MPa (e.g., about 150 MPa, about 160 MPa, about
170 MPa, about 180 MPa, about 190 MPa, about 200 MPa, about 210
MPa, about 220 MPa, about 230 MPa, about 240 MPa, or about 250
MPa). In some cases, the yield strength is from about 185 MPa to
about 195 MPa.
[0061] In certain aspects, the alloy in the T4 temper provides a
uniform elongation of at least about 20% (e.g., from about 20% to
about 30% or from about 22% to about 26%). For example, the uniform
elongation can be about 20%, about 21%, about 22%, about 23%, about
24%, about 25%, about 26%, about 27%, about 28%, about 29%, or
about 30%. Optionally, the uniform elongation is measured in the
longitudinal (L) direction.
[0062] Optionally, the alloy in the T4 temper provides a bend
angle, as tested according to VDA 238-100, of at least 120.degree..
For example, the bend angle can be from about 120.degree. to about
140.degree. (e.g., 120.degree., 121.degree., 122.degree.,
123.degree., 124.degree., 125.degree., 126.degree., 127.degree.,
128.degree., 129.degree., 130.degree., 131.degree., 132.degree.,
133.degree., 134.degree., 135.degree., 136.degree., 137.degree.,
138.degree., 139.degree., or 140.degree.). In some non-limiting
examples, including V can improve the formability of the alloys.
For example, alloys that include V exhibit an increase in bend
angle of up to 10.degree. (e.g., showing an improvement of at least
about 5.degree., at least about 6.degree., at least about
7.degree., at least about 8.degree., at least about 9.degree., at
least about 10.degree., or anywhere in between) as compared to
alloys that do not contain V.
[0063] In certain aspects, the aluminum alloy may have a T6 yield
strength of at least about 200 MPa. In non-limiting examples, the
yield strength is 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, or 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, at least about 360 MPa, at least about 370 MPa, or at
least about 375 MPa. In some cases, the yield strength is from
about 200 MPa to about 400 MPa (e.g., about 200 MPa, about 210 MPa,
about 220 MPa, about 230 MPa, about 240 MPa, about 250 MPa, about
260 MPa, about 270 MPa, about 280 MPa, about 290 MPa, about 300
MPa, about 310 MPa, about 320 MPa, about 330 MPa, about 340 MPa,
about 350 MPa, about 360 MPa, about 370 MPa, or about 375 MPa).
[0064] In certain aspects, the alloy in the T6 temper provides a
uniform elongation of at least about 5% (e.g., from about 5% to
about 10% or from about 6% to about 9%). For example, the uniform
elongation can be about 5%, about 6%, about 7%, about 8%, about 9%,
or about 10%. Optionally, the uniform elongation is measured in the
longitudinal (L) direction.
[0065] The alloy products also include recrystallization texture
components at a surface of the alloy products. For example, the
alloy products include one or more of the following
recrystallization texture components: cube, goss, brass, S, Cu, and
rotated cube (referred to as "RC"). Optionally, at least about 5
volume % of the rotated cube texture component is present in the
alloy product (e.g., from about 5 vol. % to about 20 vol. %, from
about 6 vol. % to about 18 vol. %, from about 8 vol. % to about 15
vol. %, from about 10 vol. % to about 13 vol. %, or from about 5
vol. % to about 6 vol. %). Such a rotated cube texture component
can result in desirable bending in the alloy product.
Methods of Preparing the Aluminum Alloys
[0066] Without intending to limit the invention, 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
[0067] The alloy described herein can be cast into a cast article
using any suitable casting method. For example, the casting process
can include a direct chill (DC) casting process. Optionally, the
casting process can include a continuous casting (CC) process. The
cast article can then be subjected to further processing steps. For
example, the processing methods as described herein can include the
steps of homogenizing, hot rolling, cold rolling, and
solutionizing. In some cases, the processing methods can also
include a pre-aging step and/or an artificial aging step.
Homogenization
[0068] The homogenization step can include a two-stage heating
process. In a first stage of the homogenization process, a cast
article prepared from an alloy composition described herein can be
heated to a first stage homogenization temperature (e.g., the
dispersoid nucleation temperature). The first stage homogenization
temperature can be from about 470.degree. C. to about 530.degree.
C. (e.g., about 470.degree. C., about 480.degree. C., about
490.degree. C., about 500.degree. C., about 510.degree. C., about
520.degree. C., about 530.degree. C., or anywhere in between). In
some cases, a heating rate to the first stage homogenization
temperature can be about 100.degree. C./hour or less, about
75.degree. C./hour or less, about 50.degree. C./hour or less, about
40.degree. C./hour or less, about 30.degree. C./hour or less, about
25.degree. C./hour or less, about 20.degree. C./hour or less, or
about 15.degree. C./hour or less. In other cases, the heating rate
to the first stage homogenization temperature can be from about
10.degree. C./min to about 100.degree. C./min (e.g., from about
15.degree. C./min to about 90.degree. C./min, from about 20.degree.
C./min to about 80.degree. C./min, from about 30.degree. C./min to
about 80.degree. C./min, from about 40.degree. C./min to about
70.degree. C./min, or from about 45.degree. C./min to about
65.degree. C./min).
[0069] The cast article 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 article is allowed to soak for up to
about 6 hours (e.g., from about 30 minutes to about 6 hours,
inclusively). For example, the cast article can be soaked at a
temperature of from about 470.degree. C. to about 530.degree. C.
for 30 minutes, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6
hours, or anywhere in between.
[0070] In the second stage of the homogenization process, the
temperature of the cast article is increased to a temperature
higher than the temperature used for the first stage of the
homogenization process. The cast article temperature can be
increased, for example, to a temperature at least 5.degree. C.
higher than the aluminum alloy cast article temperature during the
first stage of the homogenization process. For example, the cast
article can be further heated to a second stage homogenization
temperature (e.g., a dispersoid coarsening temperature) of from
about 525.degree. C. to about 575.degree. C. (e.g., from about
530.degree. C. to about 570.degree. C. or from about 535.degree. C.
to about 565.degree. C.). In some examples, the second stage
homogenization temperature can be about 525.degree. C., about
530.degree. C., about 535.degree. C., about 540.degree. C., about
545.degree. C., about 550.degree. C., about 555.degree. C., about
560.degree. C., about 565.degree. C., about 570.degree. C., about
575.degree. C., or anywhere in between) in a second homogenization
step. In some cases, a heating rate to the second stage
homogenization temperature can be about 50.degree. C./hour or less,
30.degree. C./hour or less, or 25.degree. C./hour or less.
[0071] The cast article is then allowed to soak for a period of
time during the second stage. According to one non-limiting
example, the cast article is allowed to soak for up to about 5
hours (e.g., from about 20 minutes to about 5 hours, inclusively).
For example, the cast article can be soaked at a temperature of
from about 525.degree. C. to about 575.degree. C. for about 15
minutes, about 20 minutes, about 30 minutes, about 45 minutes,
about 1 hour, about 1.5 hours, about 2 hours, about 3 hours, about
4 hours, about 5 hours, or anywhere in between.
Hot Rolling
[0072] Following the homogenization step, a hot rolling step can be
performed. In certain cases, the cast articles are laid down and
hot-rolled with an entry temperature range of about 500.degree. C.
to 560.degree. C. (e.g., from about 510.degree. C. to about
550.degree. C. or from about 520.degree. C. to about 540.degree.
C.). The entry temperature can be, for example, about 505.degree.
C., 510.degree. C., 515.degree. C., 520.degree. C., 525.degree. C.,
530.degree. C., 535.degree. C., 540.degree. C., 545.degree. C.,
550.degree. C., 555.degree. C., 560.degree. C., or anywhere in
between. In certain cases, the hot roll exit temperature can range
from about 250.degree. C. to about 380.degree. C. (e.g., from about
275.degree. C. to about 370.degree. C. or from about 300.degree. C.
to about 360.degree. C.). For example, the hot roll exit
temperature can be about 255.degree. C., 260.degree. C.,
265.degree. C., 270.degree. C., 275.degree. C., 280.degree. C.,
285.degree. C., 290.degree. C., 295.degree. C., 300.degree. C.,
305.degree. C., 310.degree. C., 315.degree. C., 320.degree. C.,
325.degree. C., 330.degree. C., 335.degree. C., 340.degree. C.,
345.degree. C., 350.degree. C., 355.degree. C., 360.degree. C.,
365.degree. C., 370.degree. C., 375.degree. C., or 380.degree.
C.
[0073] In certain cases, the cast article is hot rolled to an about
4 mm to about 15 mm gauge (e.g., from about 5 mm to about 12 mm
gauge), which is referred to as a hot band. For example, the cast
article can be hot rolled to a 15 mm gauge, a 14 mm gauge, a 13 mm
gauge, a 12 mm gauge, an 11 mm gauge, a 10 mm gauge, a 9 mm gauge,
an 8 mm gauge, a 7 mm gauge, a 6 mm gauge, a 5 mm gauge, or a 4 mm
gauge. The temper of the as-rolled hot band is referred to as
F-temper.
Cold Rolling
[0074] A cold rolling step can optionally be performed before the
solutionizing step. In certain aspects, the hot band is cold rolled
to a final gauge aluminum alloy sheet. In some examples, the final
gauge aluminum alloy sheet has a thickness of 4 mm or less, 3 mm or
less, 2 mm or less, 1 mm or less, 0.9 mm or less, 0.8 mm or less,
0.7 mm or less, 0.6 mm or less, 0.5 mm or less, 0.4 mm or less, 0.3
mm or less, 0.2 mm or less, or 0.1 mm.
Solutionizing
[0075] The solutionizing step can include heating the aluminum
alloy sheet or other rolled article from room temperature to a peak
metal temperature. Optionally, the peak metal temperature can be
from about 520.degree. C. to about 590.degree. C. (e.g., from about
520.degree. C. to about 580.degree. C., from about 530.degree. C.
to about 570.degree. C., from about 545.degree. C. to about
575.degree. C., from about 550.degree. C. to about 570.degree. C.,
from about 555.degree. C. to about 565.degree. C., from about
540.degree. C. to about 560.degree. C., from about 560.degree. C.
to about 580.degree. C., or from about 550.degree. C. to about
575.degree. C.). The aluminum alloy sheet can soak at the peak
metal temperature for a period of time. In certain aspects, the
aluminum alloy sheet is allowed to soak for up to approximately 2
minutes (e.g., from about 10 seconds to about 120 seconds
inclusively). For example, the sheet can be soaked at the
temperature of from about 520.degree. C. to about 590.degree. C.
for 10 seconds, 15 seconds, 20 seconds, 25 seconds, 30 seconds, 35
seconds, 40 seconds, 45 seconds, 50 seconds, 55 seconds, 60
seconds, 65 seconds, 70 seconds, 75 seconds, 80 seconds, 85
seconds, 90 seconds, 95 seconds, 100 seconds, 105 seconds, 110
seconds, 115 seconds, 120 seconds, or anywhere in between.
Aging
[0076] The aluminum alloy sheet can optionally undergo a pre-aging
heat treatment. In some examples, pre-aging can include heating the
aluminum alloy sheet to a temperature of from about 80.degree. C.
to about 120.degree. C. (e.g., about 80.degree. C., about
85.degree. C., about 90.degree. C., about 95.degree. C., about
100.degree. C., about 105.degree. C., about 110.degree. C., about
115.degree. C., about 120.degree. C., or anywhere in between) and
coiling the aluminum alloy sheet. The coiled aluminum alloy sheet
can be cooled (i.e., coil cooling is performed) for a period of up
to about 24 hours (e.g., about 1 hour, about 2 hours, about 6
hours, about 12 hours, about 18 hours, about 24 hours, or anywhere
in between).
[0077] The aluminum alloy sheet can then be naturally aged and/or
artificially aged. In some examples, the aluminum alloy sheet can
be naturally aged for a period of time to result in a T4 temper.
For example, the aluminum alloy sheet can be naturally aged for 1
week or more, 2 weeks or more, 3 weeks or more, or 4 weeks or
more.
[0078] In certain aspects, the aluminum alloy sheet in the T4
temper can be artificially aged at a temperature of from about
180.degree. C. to about 225.degree. C. (e.g., 185.degree. C.,
190.degree. C., 195.degree. C., 200.degree. C., 205.degree. C.,
210.degree. C., 215.degree. C., 220.degree. C., or 225.degree. C.)
for a period of time to result in a T6 temper. For example, the
aluminum alloy sheet can be artificially aged for a period from
about 15 minutes to about 3 hours (e.g., 15 minutes, 30 minutes, 60
minutes, 90 minutes, 105 minutes, 2 hours, 2.5 hours, 3 hours, or
anywhere in between) to result in a T6 temper.
METHODS OF USING
[0079] The alloys, products, and methods described herein can be
used in automotive, electronics, and transportation applications,
such as commercial vehicle, aircraft, or railway applications. For
example, the alloys can be used for chassis, cross-member, and
intra-chassis components (encompassing, but not limited to, all
components between the two C channels in a commercial vehicle
chassis) to gain strength, serving as a full or partial replacement
of high-strength steels. In certain embodiments, the alloys can be
used in F, T4, T6, or T8x tempers. In certain aspects, the alloys
are used with a stiffener to provide additional strength. In
certain aspects, the alloys are useful in applications where the
processing and operating temperature is approximately 150.degree.
C. or lower.
[0080] In certain aspects, the alloys and methods can be used to
prepare motor vehicle body part products. For example, the
disclosed alloys and methods can be used to prepare automobile body
parts, such as bumpers, side beams, roof beams, cross beams, pillar
reinforcements (e.g., A-pillars, B-pillars, and C-pillars), inner
panels, side panels, floor panels, tunnels, structure panels,
reinforcement panels, inner hoods, or trunk lid panels. The
disclosed aluminum alloys and methods can also be used in aircraft
or railway vehicle applications, to prepare, for example, external
and internal panels.
[0081] The described alloys and methods can also be used to prepare
housings for electronic devices, including mobile phones and tablet
computers. For example, the alloy can be used to prepare housings
for the outer casing of mobile phones (e.g., smart phones) and
tablet bottom chassis, with or without anodizing. Exemplary
consumer electronic products include mobile phones, audio devices,
video devices, cameras, laptop computers, desktop computers, tablet
computers, televisions, displays, household appliances, video
playback and recording devices, and the like. Exemplary consumer
electronic product parts include outer housings (e.g., facades) and
inner pieces for the consumer electronic products.
Illustrations
[0082] Illustration 1 is an aluminum alloy, comprising about
0.8-1.5 wt. % Si, 0.1-0.5 wt. % Fe, 0.5-1.0 wt. % Cu, 0.5-0.9 wt. %
Mg, up to 0.1 wt. % Ti, up to 0.5 wt. % Mn, up to 0.5 wt. % Cr, up
to 0.5 wt. % Zr, up to 0.5 wt. % V, up to 0.15 wt. % impurities,
and Al.
[0083] Illustration 2 is the aluminum alloy of any preceding or
subsequent illustration, comprising about 0.9-1.4 wt. % Si,
0.1-0.35 wt. % Fe, 0.6-0.9 wt. % Cu, 0.6-0.9 wt. % Mg, 0.01-0.09
wt. % Ti, up to 0.3 wt. % Mn, up to 0.3 wt. % Cr, up to 0.3 wt. %
Zr, up to 0.3 wt. % V, up to 0.15 wt. % impurities, and Al.
[0084] Illustration 3 is the aluminum alloy of any preceding or
subsequent illustration, comprising about 1.0-1.3 wt. % Si,
0.1-0.25 wt. % Fe, 0.7-0.9 wt. % Cu, 0.6-0.8 wt. % Mg, 0.01-0.05
wt. % Ti, up to 0.2 wt. % Mn, up to 0.2 wt. % Cr, up to 0.2 wt. %
Zr, up to 0.2 wt. % V, up to 0.15 wt. % impurities, and Al.
[0085] Illustration 4 is the aluminum alloy of any preceding or
subsequent illustration, wherein the aluminum alloy comprises at
least one of Mn, Cr, Zr, and V.
[0086] Illustration 5 is the aluminum alloy of any preceding or
subsequent illustration, wherein a combined content of Mn, Cr, Zr,
and/or V is at least about 0.14 wt. %.
[0087] Illustration 6 is the aluminum alloy of any preceding or
subsequent illustration, wherein the combined content of Mn, Cr,
Zr, and/or V is from about 0.14 wt. % to about 0.4 wt. %.
[0088] Illustration 7 is the aluminum alloy of any preceding or
subsequent illustration, wherein the combined content of Mn, Cr,
Zr, and/or V is from about 0.15 wt. % to about 0.25 wt. %.
[0089] Illustration 8 is the aluminum alloy of any preceding or
subsequent illustration, wherein the aluminum alloy comprises about
0.01-0.3 wt. % V.
[0090] Illustration 9 is the aluminum alloy of any preceding or
subsequent illustration, wherein the aluminum alloy comprises
excess Si and wherein an excess Si content is from about 0.01 to
about 1.0.
[0091] Illustration 10 is an aluminum alloy product, comprising the
aluminum alloy of any preceding or subsequent illustration.
[0092] Illustration 11 is the aluminum alloy product of any
preceding or subsequent illustration, wherein the aluminum alloy
product comprises a rotated cube crystallographic texture at a
volume percent of at least about 5%.
[0093] Illustration 12 is the aluminum alloy product of any
preceding or subsequent illustration, wherein the aluminum alloy
product comprises dispersoids in an amount of at least about
1,500,000 dispersoids per mm.sup.2.
[0094] Illustration 13 is the aluminum alloy product of any
preceding or subsequent illustration, wherein the dispersoids
occupy an area ranging from about 0.5% to about 5% of the aluminum
alloy.
[0095] Illustration 14 is the aluminum alloy product of any
preceding or subsequent illustration, wherein the aluminum alloy
product comprises Fe-constituents.
[0096] Illustration 15 is the aluminum alloy product of any
preceding or subsequent illustration, wherein the Fe-constituents
comprise Al(Fe,X)Si phase particles.
[0097] Illustration 16 is the aluminum alloy product of any
preceding or subsequent illustration, wherein an average particle
size of the Fe-constituents is up to about 4 .mu.m.
[0098] Illustration 17 is the aluminum alloy product of any
preceding or subsequent illustration, wherein the aluminum alloy
product comprises a yield strength of at least about 300 MPa when
in a T6 temper.
[0099] Illustration 18 is the aluminum alloy product of any
preceding or subsequent illustration, wherein the aluminum alloy
product comprises a uniform elongation of at least about 20% and a
minimum bend angle of at least about 120.degree. when in a T4
temper.
[0100] Illustration 19 is a method producing an aluminum alloy
product according to any preceding or subsequent illustration,
comprising: casting an aluminum alloy according to Illustration 1
to provide a cast article; homogenizing the cast article in a
two-stage homogenization process, wherein the two-stage
homogenization process comprises heating the cast article to a
first stage homogenization temperature and holding the cast article
at the first stage homogenization temperature for a period of time
and further heating the cast article to a second stage
homogenization temperature and holding the cast article at the
second stage homogenization temperature for a period of time; hot
rolling and cold rolling to provide a final gauge aluminum alloy
product; solution heat treating the final gauge aluminum alloy
product; and pre-aging the final gauge aluminum alloy product.
[0101] Illustration 20 is the method of any preceding illustration,
wherein the first stage homogenization temperature is from about
470.degree. C. to about 530.degree. C. and the second stage
homogenization temperature is from about 525.degree. C. to about
575.degree. C., and wherein the second stage homogenization
temperature is higher than the first stage homogenization
temperature.
[0102] 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: Aluminum Alloy Properties
[0103] Alloys were prepared for strength and formability testing.
The compositions for these alloys are provided in Table 4 below. In
each of the alloy compositions in Table 4, the remainder is Al.
TABLE-US-00004 TABLE 4 Alloy No. Si Fe Cu Mg Ti Mn Cr Zr V Excess
Si* D1 1.20 0.18 0.80 0.70 0.02 0.13 0.07 -- -- 0.73 D2 1.20 0.18
0.80 0.70 0.02 -- 0.14 -- -- 0.74 D3 1.20 0.18 0.80 0.70 0.02 --
0.07 0.11 -- 0.75 D4 1.20 0.18 0.80 0.70 0.02 -- 0.08 -- 0.11 0.75
D5 1.20 0.18 0.80 0.70 0.02 -- -- 0.09 0.10 0.77 D6 1.20 0.18 0.80
0.70 0.02 0.09 -- -- 0.10 0.75 Elemental values in wt. %. *Excess
Si values obtained according to calculation methods described
herein.
[0104] The alloys were prepared by DC casting the components into
ingots and homogenizing the ingots in a two-step homogenization
step as described herein. The first step provided nucleation of a
maximum amount of fine dispersoids (e.g., dispersoids having a
diameter of less than about 10 nm). The second step coarsened the
fine dispersoids. The homogenized ingots were then laid down and
hot rolled according to the methods as described herein to a 10 mm
gauge. The hot band was coiled and cooled and was then cold rolled
to a 2 mm gauge. A solution heat treatment step was then performed
at 560.degree. C. for 35 seconds. A pre-aging step was performed by
heating the sheet to 100.degree. C. and soaking for 1 hour (e.g.,
to simulate coil cooling as described above), followed by natural
aging to achieve the T4 temper. The T6 temper was then achieved by
aging the T4 alloys at 200.degree. C. for 30 minutes.
[0105] The properties of the D1-D6 alloys in T4 temper, including
the yield strength, uniform elongation, and bend angle, were
determined. Tensile testing was performed according to ASTM B557 in
three directions relative to a rolling direction of the alloy
sheets to evaluate anisotropic properties that can occur during
recrystallization. Yield strength (referred to as "YS" and
indicated by histograms) and uniform elongation (referred to as
"UE" and indicated by points) are shown in FIG. 1 for a
longitudinal direction along the rolling direction (referred to as
"L" and indicated by vertical stripes), a transverse direction
90.degree. to the rolling direction (referred to as "T" and
indicated by horizontal stripes), and a diagonal direction
45.degree. to the rolling direction (referred to as "D" and
indicated by cross-hatching). Evident in the graph based on the
yield strength and uniform elongation, the alloys exhibited
isotropic behavior in all three directions subjected to tensile
testing even with elongated recrystallized grain structures as
observed in FIG. 2. The uniform elongation values ranged from 24%
to 26% and the yield strengths were from 185 MPa to 195 MPa.
[0106] FIG. 3 shows the yield strengths and uniform elongations for
alloys D1-D6 in T4 and T6 tempers. For alloys D1-D6 in T4 temper,
the composition had a negligible effect on yield strength and
uniform elongation. For alloys D1-D6 in T6 temper, the composition
had a negligible effect on uniform elongation and a decrease in
yield strength of about 10 MPa for alloys including V in the
composition. The decrease in yield strength can be attributed to
solute loss (e.g., Si, Mg, and/or Cu) during solutionizing by
heterogeneous nucleation of solute precipitates on V-containing
dispersoids.
[0107] FIG. 4 is a graph showing bend angle test results for alloys
D1-D6 in a T4 temper. Addition of Cr and V produced a large number
of fine dispersoids which improves bending by diffusing strain
distribution during deformation (e.g., bending, forming, stamping,
or any suitable deformation process). In some cases, Mn combined
with Fe and Si to form and spheroidize Fe-constituents, rather than
forming dispersoids, due to the high diffusivity of Mn as compared
to Zr, Cr, and/or V. Spheroidization of the Fe-constituents
improved bending by eliminating elongated (i.e., needle-like)
particulates that can initiate cracking during deformation.
Additionally, V-containing alloys (e.g., alloys D4-D6) exhibited
improved bending compared to V-free variants due to Fe-constituent
spheroidization. FIG. 5 compares yield strength (YS) and bend angle
(VDA) for alloys D1-D6 in T4 and T6 tempers.
Example 2: Aluminum Alloy Microstructure
[0108] FIG. 6 shows recrystallization texture components for alloys
D1-D6, including cube, goss, brass, S, Cu, and rotated cube
(referred to as "RC"). Each alloy D1-D6 exhibited a similar
distribution of texture components, and composition had a
negligible effect on recrystallization texture. Surprisingly, each
alloy exhibited a relatively high amount of rotated cube texture,
resulting in the significantly improved bending angles shown in
FIG. 4 and FIG. 5.
[0109] FIG. 7 shows transmission electron microscopy (TEM) images
of alloys D1-D6 in T4 temper. Evident in the TEM images is
dispersoid formation (shown as bright white particulates) in each
alloy. Alloy D4 (including Cr and V) exhibited a higher dispersoid
amount due to the relatively low diffusivities of Cr and V.
Likewise, alloys D5 and D6 exhibited a lower number of dispersoids
due to the relatively higher diffusivities of Mn and Zr.
Accordingly, alloy D6 exhibited a lesser amount of dispersoids
attributed to an affinity of Mn to be incorporated in
Fe-constituents and to not solely form Mn dispersoids. FIG. 8 shows
dispersoid number density (histograms) and area fraction (open
circles) for alloys D1-D6 in T4 temper. Alloys not containing V
(alloys D1-D3) exhibited similar dispersoid number density. Alloy
D2 (incorporating only Cr as a transition metal alloying element)
exhibited a higher dispersoid area fraction compared to alloys D1
and D3 (incorporating Mn and Cr (D1) and Zr and Cr (D3)). Alloy D4
(incorporating Cr and V) exhibited the highest dispersoid number
density and the highest dispersoid area fraction.
[0110] FIG. 9 shows scanning electron microscopy (SEM) images of
alloys D1-D6 in a T4 temper. Evident in the SEM images is
Fe-constituent formation (shown as bright white elongated
particulates). Each of the alloys D1-D6 exhibited similar amounts
of Fe-constituent formation, and similar Fe-constituent particle
size distribution as shown in FIG. 10. As described above,
employing transition metal alloying elements reduced the formation
of Fe-constituents (e.g., AlFeSi) by replacing a portion of the Fe,
thus forming spherical Al(Fe,X)Si constituents. Each alloy
continued to exhibit AlFeSi (elongated particulates) due to the
presence of excess Si and processing at a low homogenization
temperature (e.g., about 500.degree. C.), with a reduced size and
size distribution in alloys not employing the transition metal
alloying elements. In some aspects, the AlFeSi constituents in
alloys not containing the transition metal alloying elements
exhibited a larger size than the AlFeSi constituents observed in
the alloys containing the transition metal alloying elements.
Fe-constituent size and size distribution was evaluated at a depth
of about 0.5 mm from a surface of the aluminum alloy sheet
(referred to as quarter thickness, indicated "QT" in the
graph).
[0111] FIG. 11 shows optical microscopy (referred to as "OM") and
SEM images of alloy D 1. Alloy D1 was subjected to a one-step
homogenization after casting, including a thermal ramp of
50.degree. C. per hour to 560.degree. C., soaked for 2 hours, and
subsequently hot rolled, cold rolled, solutionized, pre-aged, and
naturally aged as described above. Evident in the OM images is
incipient and/or eutectic melting of Mg.sub.2Si in alloy D1 (shown
as dark areas). SEM images show the dark areas are voids that
formed in the alloy during homogenization. Energy dispersive X-ray
spectroscopy (EDXS) showed Fe-constituents present in the voids
(shown as bright particulates). Employing the exemplary two-step
homogenization as described herein can eliminate the incipient
and/or eutectic melting when transition metal alloying elements are
incorporated in the aluminum alloy compositions.
[0112] All patents, publications, and abstracts cited above are
incorporated herein by reference in their entireties. 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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