Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 03121042 2021-05-25
WO 2020/117748 PCT/US2019/064148
6XXX ALUMINUM ALLOYS
BACKGROUND
[001] Aluminum alloys are useful in a variety of applications. However,
improving one
property of an aluminum alloy without degrading another property often proves
elusive. For
example, it is difficult to increase the strength of an alloy without
decreasing its corrosion
resistance. Other properties of interest for aluminum alloys include
formability and critical
fracture strain, to name two.
SUMMARY OF THE DISCLOSURE
[002] Broadly, the present disclosure relates to new 6xxx aluminum alloys
having an
improved combination of properties, such as an improved combination of
strength, formability,
bending, and/or corrosion resistance, among others.
i. Composition
[003] Generally, the new 6xxx aluminum alloys comprise (and in some
instances consist
essentially of or consist of) from 0.65 to 0.85 wt. % Si, from 0.40 to 0.59
wt. % Mg wherein
the ratio of wt. % Mg to wt. % Si is from 0.47:1 to 0.90:1 (Mg:Si), from 0.05
to 0.35 wt. % Fe,
from 0.04 to 0.13 wt. % Mn, from 0 to 0.20 wt. % Cu, from 0 to 0.15 wt. % Cr,
from 0 to 0.15
wt. % Zr, from 0 to 0.10 wt. % Ti, from 0 to 0.05 wt. % V, from 0 to 0.05 wt.
% Zn, the balance
being aluminum and impurities.
[004] The amount of magnesium (Mg) and silicon (Si) in the new 6xxx
aluminum alloys
may relate to the improved combination of properties (e.g., strength,
formability). Generally,
the new 6xxx aluminum alloy includes from 0.40 to 0.59 wt. % Mg. In one
embodiment, a
new 6xxx aluminum alloy includes at least 0.425 wt. % Mg. In another
embodiment, a new
6xxx aluminum alloy includes at least 0.45 wt. % Mg. In yet another
embodiment, a new 6xxx
aluminum alloy includes at least 0.475 wt. % Mg. In another embodiment, a new
6xxx
aluminum alloy includes at least 0.50 wt. % Mg. In one embodiment, a new 6xxx
aluminum
alloy includes not greater than 0.57 wt. % Mg. In one embodiment, a new 6xxx
aluminum
alloy includes from 0.49 to 0.59 wt. % Mg.
[005] Generally, the new 6xxx aluminum alloy includes from 0.65 to 0.85 wt.
% Si. In
one embodiment, a new 6xxx aluminum alloy includes at least 0.675 wt. % Si. In
another
embodiment, a new 6xxx aluminum alloy includes at least 0.70 wt. % Si. In one
embodiment,
a new 6xxx aluminum alloy includes not greater than 0.825 wt. % Si. In another
embodiment,
1
CA 03121042 2021-05-25
WO 2020/117748 PCT/US2019/064148
a new 6xxx aluminum alloy includes not greater than 0.80 wt. % Si. In one
embodiment, a
new 6xxx aluminum alloy includes from 0.70 to 0.80 wt. % Si.
[006] Generally, the new 6xxx aluminum alloy includes silicon and magnesium
such that
the weight ratio of magnesium-to-silicon of from 0.47:1 to 0.90:1, i.e., the
ratio of wt. % Mg
to wt. % Si is from 0.47:1 to 0.90:1 (Mg:Si). In one embodiment, the ratio of
wt. % Mg to wt.
% Si is at least 0.50:1(Mg:Si). In another embodiment, the ratio of wt. % Mg
to wt. % Si is at
least 0.52:1(Mg:Si). In yet another embodiment, the ratio of wt. % Mg to wt. %
Si is at least
0.54:1(Mg:Si). In another embodiment, the ratio of wt. % Mg to wt. % Si is at
least
0.56: l(Mg:Si). In yet another embodiment, the ratio of wt. % Mg to wt. % Si
is at least
0.58:1(Mg:Si). In another embodiment, the ratio of wt. % Mg to wt. % Si is at
least
0.60: l(Mg:Si). In one embodiment, the ratio of wt. % Mg to wt. % Si is not
greater than
0.88:1(Mg:Si). In another embodiment, the ratio of wt. % Mg to wt. % Si is not
greater than
0.86: l(Mg:Si). In yet another embodiment, the ratio of wt. % Mg to wt. % Si
is not greater
than 0.84:1(Mg:Si). In another embodiment, the ratio of wt. % Mg to wt. % Si
is not greater
than 0.82:1(Mg:Si). In one embodiment, the ratio of wt. % Mg to wt. % Si is
from 0.61:1 to
0.84:1 (Mg: Si).
[007] Iron (Fe) is generally included in the new 6xxx aluminum alloy, and
in the range of
from 0.05 to 0.35 wt. % Fe. In one embodiment, a new 6xxx aluminum alloy
includes at least
0.08 wt. % Fe. In another one embodiment, a new 6xxx aluminum alloy includes
at least 0.10
wt. % Fe. In yet another embodiment, a new 6xxx aluminum alloy includes at
least 0.12 wt.
% Fe. In another embodiment, a new 6xxx aluminum alloy includes at least 0.15
wt. %. In one
embodiment, a new 6xxx aluminum alloy includes not greater than 0.32 wt. % Fe.
In another
embodiment, a new 6xxx aluminum alloy includes not greater than 0.30 wt. % Fe.
In yet
another embodiment, a new 6xxx aluminum alloy includes not greater than 0.28
wt. % Fe. In
one embodiment, a new 6xxx aluminum alloy includes from 0.09 to 0.26 wt. % Fe.
[008] The amount of manganese (Mn) in the new 6xxx aluminum alloys may
relate to the
improved combination of properties (e.g., formability). Generally, the new
6xxx aluminum
alloy includes from 0.04 to 0.13 wt. % Mn. In one embodiment, a new 6xxx
aluminum alloy
includes at least 0.05 wt. % Mn. In another embodiment, a new 6xxx aluminum
alloy includes
at least 0.06 wt. % Mn. In one embodiment, a new 6xxx aluminum alloy includes
not greater
than 0.12 wt. % Mn. In another embodiment, a new 6xxx aluminum alloy includes
not greater
than 0.11 wt. % Mn. In another embodiment, a new 6xxx aluminum alloy includes
not greater
than 0.10 wt. % Mn. In one embodiment, a new 6xxx aluminum alloy includes from
0.06 to
0.10 wt. % Mn.
2
CA 03121042 2021-05-25
WO 2020/117748 PCT/US2019/064148
[009] The new 6xxx aluminum alloy may optionally include copper (Cu) and in
an
amount of up to 0.20 wt. % Cu (e.g., for strengthening purposes). In one
embodiment, a new
6xxx aluminum alloy includes at least 0.02 wt. % Cu. In another embodiment, a
new 6xxx
aluminum alloy includes at least 0.04 wt. % Cu. In yet another embodiment, a
new 6xxx
aluminum alloy includes at least 0.06 wt. % Cu. In another embodiment, a new
6xxx aluminum
alloy includes at least 0.07 wt. % Cu. In yet another embodiment, a new 6xxx
aluminum alloy
includes at least 0.08 wt. % Cu. In another embodiment, a new 6xxx aluminum
alloy includes
at least 0.09 wt. % Cu. In one embodiment, a new 6xxx aluminum alloy includes
not greater
than 0.19 wt. % Cu. In another embodiment, a new 6xxx aluminum alloy includes
not greater
than 0.18 wt. % Cu. In yet another embodiment, a new 6xxx aluminum alloy
includes not
greater than 0.17 wt. % Cu. In one embodiment, a new 6xxx aluminum alloy
includes from
0.09 to 0.17 wt. % Cu.
[0010] The new 6xxx aluminum alloy may optionally include chromium (Cr) and
in an
amount of up to 0.15 wt. % Cr (e.g., for grain structure control). In one
embodiment, a new
6xxx aluminum alloy includes at least 0.01 wt. % Cr. In another embodiment, a
new 6xxx
aluminum alloy includes at least 0.02 wt. % Cr. In one embodiment, a new 6xxx
aluminum
alloy incudes not greater than 0.10 wt. % Cr. In another embodiment, a new a
new 6xxx
aluminum alloy incudes not greater than 0.08 wt. % Cr. In yet another
embodiment, a new a
new 6xxx aluminum alloy incudes not greater than 0.06 wt. % Cr. In another
embodiment, a
new a new 6xxx aluminum alloy incudes not greater than 0.05 wt. % Cr. In one
embodiment,
a new 6xxx aluminum alloy includes from 0.01 to 0.05 wt. % Cr.
[0011] The new 6xxx aluminum alloy may optionally include zirconium (Zr)
and in an
amount of up to 0.15 wt. % Zr (e.g., for grain structure control). In one
embodiment, a new
6xxx aluminum alloy incudes not greater than 0.10 wt. % Zr. In another
embodiment, a new a
new 6xxx aluminum alloy incudes not greater than 0.05 wt. % Zr. In yet another
embodiment,
a new a new 6xxx aluminum alloy incudes not greater than 0.03 wt. % Zr. In
another
embodiment, a new a new 6xxx aluminum alloy incudes not greater than 0.01 wt.
% Zr.
[0012] The new 6xxx aluminum alloy may include up to 0.15 wt. % Ti.
Titanium (Ti) may
optionally be present in the new 6xxx aluminum alloy, such as for grain
refining purposes. In
one embodiment, a new 6xxx aluminum alloy includes at least 0.005 wt. % Ti. In
another
embodiment, a new 6xxx aluminum alloy includes at least 0.010 wt. % Ti. In yet
another
embodiment, a new 6xxx aluminum alloy includes at least 0.0125 wt. % Ti. In
one
embodiment, a new 6xxx aluminum alloy includes not greater than 0.10 wt. % Ti.
In another
embodiment, a new 6xxx aluminum alloy includes not greater than 0.08 wt. % Ti.
In yet
3
CA 03121042 2021-05-25
WO 2020/117748 PCT/US2019/064148
another embodiment, a new 6xxx aluminum alloy includes not greater than 0.05
wt. % Ti. In
one embodiment, a target amount of titanium in a new 6xxx aluminum alloy is
0.03 wt. % Ti.
In one embodiment, a new 6xxx aluminum alloy includes from 0.01 to 0.05 wt. %
Ti.
[0013] Zinc (Zn) may optionally be present in the new 6xxx aluminum alloy,
and in an
amount up to 0.10 wt. % Zn. In one embodiment, a new alloy includes not
greater than 0.05
wt. % Zn. In another embodiment, a new alloy includes not greater than 0.03
wt. % Zn. In
another embodiment, a new alloy includes not greater than 0.01 wt. % Zn.
[0014] Vanadium (V) may optionally be present in the new 6xxx aluminum
alloy, and in
an amount of up to 0.05 wt. % V. In one embodiment, a new 6xxx aluminum alloy
includes
not greater than 0.03 wt. % V. In another embodiment, a new 6xxx aluminum
alloy includes
not greater than 0.01 wt. % V.
[0015] As noted above, the balance of the new aluminum alloy is generally
aluminum and
impurities. In one embodiment, a new 6xxx aluminum alloy includes not greater
than 0.15 wt.
%, in total, of the impurities, and wherein the 6xxx aluminum alloy includes
not greater than
0.05 wt. % of each of the impurities. In another embodiment, a new 6xxx
aluminum alloy
includes not greater than 0.10 wt. %, in total, of the impurities, and wherein
the 6xxx aluminum
alloy includes not greater than 0.03 wt. % of each of the impurities.
[0016] Except where stated otherwise, the expression "up to" when referring
to the amount
of an element means that that elemental composition is optional and includes a
zero amount of
that particular compositional component. Unless stated otherwise, all
compositional
percentages are in weight percent (wt. %).
ii. Processing and Product Forms
[0017] The new 6xxx alloys may be useful in a variety of product forms,
including ingot
or billet, wrought product forms (sheet, plate, forgings and extrusions),
shape castings,
additively manufactured products, and powder metallurgy products. In one
embodiment, a
new 6xxx aluminum alloy is a rolled product. For example, the new 6xxx
aluminum alloys
may be produced in sheet form. In one embodiment, a sheet made from the new
6xxx
aluminum alloy has a thickness of from 1.5 mm to 4.0 mm.
[0018] In one embodiment, the new 6xxx aluminum alloys are produced using
ingot casting
and hot rolling. In one embodiment, a method includes the steps of casting an
ingot of the new
6xxx aluminum alloy, homogenizing the ingot, rolling the ingot into a rolled
product having a
final gauge (via hot rolling and/or cold rolling), solution heat treating the
rolled product,
wherein the solution heat treating comprises heating the rolled product to a
temperature and for
4
CA 03121042 2021-05-25
WO 2020/117748 PCT/US2019/064148
a time such that some or substantially all of Mg2Si of the rolled product is
dissolved into solid
solution, and after the solution heat treating, quenching the rolled product
(e.g., water or air
quenching). After the quenching, the rolled product may be artificially aged.
In some
embodiments, one or more anneal steps may be completed before or after a
rolling step (e.g.,
hot rolling to a first gauge, annealing, cold rolling to the final gauge). The
artificially aged
product can be painted (e.g., for an automobile part), and may thus be
subjected to a paint-bake
cycle. In one embodiment, the rolled aluminum alloy products produced from the
new alloy
may be incorporated in an automobile.
[0019] In one embodiment, the new 6xxx aluminum alloys products are cast
via continuous
casting. Downstream of the continuous casting, the product can be (a) rolled
(hot and/or cold),
(b) optionally annealed (e.g., after hot rolling and prior to any cold rolling
steps), (c) solution
heat treated and quenched, (d) optionally cold worked (post-solution heat
treatment), and (e)
artificially aged, and all steps (a) - (e) may occur in-line or off-line
relative to the continuous
casting step. Some methods for producing the new 6xxx aluminum alloys products
using
continuous casting and associated downstream steps are described in, for
example, U.S. Patent
No. 7,182,825, U.S. Patent Application Publication No. 2014/0000768, and U.S.
Patent
Application Publication No. 2014/036998, each of which is incorporated herein
by reference
in its entirety. The artificially aged product can be painted (e.g., for an
automobile part), and
may thus be subjected to a paint-bake cycle.
[0020] In one embodiment, the hot rolling comprises hot rolling to an
intermediate gauge
product, wherein the intermediate gauge product exits the hot rolling
apparatus at a temperature
of not greater than 290 C. After the hot rolling, an optional anneal may be
completed. After
the hot rolling and any anneal, the intermediate gauge product may be cold
rolled to final gauge.
[0021] In another embodiment, the hot rolling comprises rolling to an
intermediate gauge
product, wherein the intermediate gauge product exits the hot rolling
apparatus at a temperature
of from 400-480 C. After the hot rolling, the intermediate gauge product may
then be cold
rolled to final gauge, i.e., no anneal is required after the hot rolling and
prior to cold rolling in
this embodiment.
[0022] When cold rolling is completed, the cold rolling generally comprises
reducing the
thickness of the intermediate gauge thickness to the final gauge thickness. In
one embodiment,
the cold rolling comprises cold rolling by at least 50%. In another
embodiment, the cold rolling
comprises cold rolling by at least 60%. In yet another embodiment, the cold
rolling comprises
cold rolling by at least 65%. In one embodiment, the cold rolling is not
greater than 85%.
CA 03121042 2021-05-25
WO 2020/117748 PCT/US2019/064148
[0023] As known to those skilled in the art, "cold rolled XX %" and the
like means XXcR%,
where XXcR% is the amount of thickness reduction achieved when the aluminum
alloy body
is reduced from a first thickness of Ti to a second thickness of T2, where Ti
is the intermediate
gauge thickness and wherein T2 is the thickness. In other words, XXcR% is
equal to:
XXcR%=(1-T2/T i)* 100%
For example, when an aluminum alloy body is cold rolled from a first thickness
(Ti) of 15.0
mm to a second thickness of 3.0 mm (T2), XXcR% is 80%. Phrases such as "cold
rolling 80%"
and "cold rolled 80%" are equivalent to the expression XXcR%=80%
[0024] In one embodiment, the peak metal temperature during solution heat
treatment is in
the range of from 504 C to 593 C. The peak metal temperature is the highest
temperature
realized by an alloy product during solution heat treatment.
[0025] In one embodiment, the new 6xxx aluminum alloy products are
processed to a T4
temper as defined by ANSI H35.1 (2009), i.e., the new 6xxx are solution heat
treated and then
quenched and then naturally aged to a substantially stable condition. In one
embodiment, the
natural aging amount is 30 days and the T4 properties of the new 6xxx aluminum
alloy are
measured at 30 days of natural aging.
[0026] In one embodiment, the new 6xxx aluminum alloys are processed to a
T6 temper as
defined by ANSI H35.1 (2009), i.e., the new 6xxx are solution heat treated and
then quenched
and then artificially aged. In one embodiment, the artificial aging comprises
paint baking. In
one embodiment, the artificial aging consist of paint baking. In one
embodiment, paint baking
comprises heating the new 6xxx aluminum alloy product to 180 C and then
holding for 20
minutes.
[0027] In one embodiment, the new 6xxx aluminum alloys are processed to a
T8 temper as
defined by ANSI H35.1 (2009), i.e., the new 6xxx are solution heat treated and
then quenched
and then cold worked (e.g., stretched), and then artificially aged. In one
embodiment, the
artificial aging comprises paint baking. In one embodiment, the artificial
aging consist of paint
baking. In one embodiment, paint baking comprises heating the new 6xxx
aluminum alloy
product to 180 C and then holding for 20 minutes.
iii. Microstructure
A. Recrystallization
[0028] The processing of the new 6xxx aluminum alloy steps may be
accomplished such
that a new aluminum alloy body product realizes a predominately recrystallized
microstructure.
A predominately recrystallized microstructure means that the aluminum alloy
body contains at
least 51% recrystallized grains (by volume fraction). The degree of
recrystallization of a new
6
CA 03121042 2021-05-25
WO 2020/117748 PCT/US2019/064148
6xxx aluminum alloy product may be determined using appropriate metallographic
samples of
the material analyzed with EBSD by an appropriate SEM and computer software to
determine
intergranular misorientation. In one embodiment, a new 6xxx aluminum alloy
product is at
least 60% recrystallized. In another embodiment, a new 6xxx aluminum alloy
product is at
least 70% recrystallized. In yet another embodiment, a new 6xxx aluminum alloy
product is
at least 80% recrystallized. In another embodiment, a new 6xxx aluminum alloy
product is at
least 90% recrystallized. In yet another embodiment, a new 6xxx aluminum alloy
product is
at least 95% recrystallized. In another embodiment, a new 6xxx aluminum alloy
product is at
least 98% recrystallized, or more.
B. Grain Size and Texture
[0029] A new 6xxx aluminum alloy product may realize a fine grain size. In
one
embodiment, a new 6xxx aluminum alloy product realizes an area weighted
average grain size
of not greater than 45 micrometers. In another embodiment, a new 6xxx aluminum
alloy
product realizes an area weighted average grain size of not greater than 40
micrometers. In
one embodiment, a new 6xxx aluminum alloy product realizes an area weighted
average grain
size of at least 20 micrometers. In another embodiment, a new 6xxx aluminum
alloy product
realizes an area weighted average grain size of at least 25 micrometers. In
yet another
embodiment, a new 6xxx aluminum alloy product realizes an area weighted
average grain size
of at least 30 micrometers.
[0030] A new 6xxx aluminum alloy product may realize a unique texture.
Texture means
a preferred orientation of at least some of the grains of a crystalline
structure. Using
matchsticks as an analogy, consider a material composed of matchsticks. That
material has a
random texture if the matchsticks are included within the material in a
completely random
manner. However, if the heads of at least some of those matchsticks are
aligned in that they
point the same direction, like a compass pointing north, then the material
would have at least
some texture due to the aligned matchsticks. The same principles apply with
grains of a
crystalline material.
[0031] Texture components resulting from production of aluminum alloy
products may
include one or more of copper, S texture, brass, cube, and Goss texture, to
name a few. Each
of these texture components is defined in Table 1, below.
7
CA 03121042 2021-05-25
WO 2020/117748 PCT/US2019/064148
Table 1
Texture component Miller Indices Bunge (91, 41), 92) Kocks CP, 0,
(F)
copper {112}(111) 90, 35, 45 0, 35, 45
{123}(634) 59, 37, 63 149, 37, 27
brass {110}(112) 35, 45, 0 55, 45, 0
Cube {1 0 0} <001> 0, 0, 0 0, 0, 0
Goss {110}(001) 0, 45, 0 0, 45, 0
[0032] The below table is a non-limiting example of texture components and
ranges that
may be realized by the new 6xxx aluminum alloys disclosed herein.
Texture Type Min (%) (Max (%)
Cube 10 25
Goss 0 2.0
Brass 0 1.5
0 3.0
Copper 0 2.5
[0033] For purposes of the present patent application grain size and
texture are to be
measured and normalized as follows:
= A Phillips XL-30 FESEM or equivalent is to be used.
= Electron backscatter diffraction (EBSD) patterns are to be collected
using an EDAX
EBSD Digiview 5 detection system, or equivalent. The EBSD acquisition is to be
performed using EDAX TSL EBSD Data Collection (01M)TM software, version 7,
or equivalent.
= Samples are to be cross-sectioned and polished for analysis of the
longitudinal (L)
x short transverse (ST) plane, and prepared for standard metallographic
analysis,
e.g., by grinding the cross-sectioned and mounted sample flat and polishing
with
successively finer grits to 0.05 p.m colloidal silica (5i02). The final step
is vibratory
polishing for 45 minutes.
= After metallographic preparation, the samples are to be ion milled for 15
minutes
using an appropriate broad beam argon ion milling system (e.g., an Hitachi
8
CA 03121042 2021-05-25
WO 2020/117748 PCT/US2019/064148
IM4000Plus) operated at 3kV and glancing angle incidence (10 degrees) on the
sample surface, while the sample is rotated at 25 rotations per minute.
= Data acquisition parameters are to include an electron beam energy of
20kV, a spot
size 5 with a sample tilt angle of 70 degrees; a 0.8 micrometer step size and
square
grid scan type are to be used.
= EBSD patterns are to be collected using 8x8 binning and enhanced image
processing, including background subtraction and a normalized intensity
histogram.
Map dimensions are to be full thickness in the short transverse (ST) direction
by
800 micrometers in the longitudinal (L) direction (i.e., the rolling direction
for sheet
products).
= The software used to analyze the acquired data should be an EDAX TSL
0IMTm 8
data analysis package or similar. Data analysis included a 2-step clean-up
procedure. The first step is a Neighbor Orientation Correlation level 2 clean
up
applied to data with a minimum confidence index (CI) of 0.1 and grain
tolerance
angle of 5 degrees. The second step is a Grain Dilation using a grain
tolerance angle
of 5 degrees and a minimum of 5 points per grain for a single iteration.
= Grains are defined to have a minimum of 5 points per grain with a grain
tolerance
angle of 5 degrees. In one embodiment, the software determines grain size
(average
grain diameter) via the Heyn linear intercept method, generally as per ASTM
E112-
12, 13.
= In another embodiment, individual grain sizes are determined by counting
the
number of points within each grain and multiplying by the area of each point
(step
size squared).
= The following equation may be used to calculate grain size (i.e.,
equivalent circular
diameter):
vi = square root (-4Ai)
Pi
where Ai is the area of each individual grain as measured per above. "vi" is
the
calculated individual grain size assuming the grain is a circle. The number
average
grain size, v-bar n, is the arithmetic mean of vi.
v-bar n = ( E i=1 vi)/n
= The "area weighted average grain size" may be calculated using the
following
equation:
9
CA 03121042 2021-05-25
WO 2020/117748 PCT/US2019/064148
iv-bar a = ( n. A vi)/( EriLl Ai)
t=i
where Ai is the area of each individual grain, as per above, and where vi is
the
calculated individual grain size, as per above. "v-bar a" is the area weighted
average grain size.
= The quantification of texture components present (Cube%, Goss%, Brass%,
S%,
Copper%) is to be determined as the number fraction of measured points
assigned
to a specific texture component. Points are assigned to a texture component if
the
misorientation angle deviates from the ideal orientation by less than 13.74
degrees.
This number fraction is multiplied by 100 to find the percentage of each
texture
component in the sample.
iv. Properties
[0034] As noted above, the new 6xxx aluminum alloys disclosed herein may
realize an
improved combination of properties. In one embodiment, a new 6xxx aluminum
alloy realizes
a T4 tensile yield strength in the LT (long transverse) direction of from 90
to 110 MPa. In one
embodiment, a new 6xxx aluminum alloy realizes a T4 uniform elongation in the
LT (long
transverse) direction of at least 21%. In one embodiment, a new 6xxx aluminum
alloy realizes
a T4 n value (10-20%) in the LT (long transverse) direction of at least 0.245.
For purposes of
this paragraph, T4 properties are to be measured after 30 days of natural
aging.
[0035] For purposes of this patent application, tensile yield strength and
uniform
elongation are to be measured in accordance with ASTM E8 and B557. For
purposes of this
patent application, "n value (10-20%)" is to be measured in accordance with
ASTM E646 using
10-20% strain.
[0036] In one embodiment, a new 6xxx aluminum alloy realizes a T6 (0% pre-
strain/stretch) tensile yield strength of at least 160 MPa when artificially
aged by paint baking
at 180 C for 20 minutes. In another embodiment, a new 6xxx aluminum alloy
realizes a T6,
(0% pre-strain/stretch) tensile yield strength of at least 170 NiPa when
artificially aged by paint
baking at 180 C for 20 minutes. In yet another embodiment, a new 6xxx aluminum
alloy
realizes a T6 (0% pre-strain/stretch) tensile yield strength of at least 180
MPa when artificially
aged by paint baking at 180 C for 20 minutes.
[0037] In one embodiment, a new 6xxx aluminum alloy realizes a T8 tensile
yield strength
of at least 215 MPa when post-SHT stretched 1-3 % and then artificially aged
by paint baking
at 180 C for 20 minutes.
CA 03121042 2021-05-25
WO 2020/117748 PCT/US2019/064148
[0038] In one embodiment, a new 6xxx aluminum alloy realizes a Hem rating
of 2 or better.
Hem rating is defined in the below Examples. In another embodiment, a new 6xxx
aluminum
alloy realizes a Hem rating of 1.
[0039] In one embodiment, a new 6xxx aluminum alloy realizes a VDA bend
angle of at
least 125 . VDA testing is to be tested by natural aging the product for 30
days, and then
stretching the product 10% in the L (longitudinal) direction, and then
conducting the VDA
bend test in accordance with the VDA 238-100 bend test specification.
(https ://www.vda. de/en/servi ce s/Publi cati on s/vda-238-100-pl ate-b
ending-te st-for-metalli c-
materials.html). In another embodiment, a new 6xxx aluminum alloy realizes a
VDA bend
angle of at least 130 . In yet another embodiment, a new 6xxx aluminum alloy
realizes a VDA
bend angle of at least 135 . In another embodiment, a new 6xxx aluminum alloy
realizes a
VDA bend angle of at least 140 . In yet another embodiment, a new 6xxx
aluminum alloy
realizes a VDA bend angle of at least 143 .
[0040] In one embodiment, a new 6xxx aluminum alloy is absent of Ludering.
Ludering
is to be tested by naturally aging the product for 8 days, and then stretching
the product 10%
in the L (longitudinal) direction. If Luder lines are visible to the naked
eye, the product is not
absent of Ludering. If Luder lines are invisible to the naked eye, the product
is absent of
Ludering.
[0041] In one embodiment, a new 6xxx aluminum alloy realizes a combination
of
properties shown in the "Preferred Property Box" of FIG. 1. In some of these
embodiments, a
new 6xxx aluminum alloy realizes a VDA bend angle of at least 140 . Others of
the above-
identified properties may also be realized.
[0042] In one embodiment, a new 6xxx aluminum alloy realizes a combination
of
properties shown in the "Preferred Property Box" of FIG. 2. In some of these
embodiments, a
new 6xxx aluminum alloy realizes a VDA bend angle of at least 140 . Others of
the above-
identified properties may also be realized.
[0043] In one embodiment, a new 6xxx aluminum alloy realizes a combination
of
properties shown in the "Preferred Property Box" of FIG. 3. In some of these
embodiments, a
new 6xxx aluminum alloy realizes a VDA bend angle of at least 140 . Others of
the above-
identified properties may also be realized.
[0044] In one embodiment, a new 6xxx aluminum alloy realizes a combination
of
properties shown in the "Preferred Property Box" of FIG. 4. In some of these
embodiments, a
new 6xxx aluminum alloy realizes a VDA bend angle of at least 140 . Others of
the above-
identified properties may also be realized.
11
CA 03121042 2021-05-25
WO 2020/117748 PCT/US2019/064148
[0045] The figures constitute a part of this specification and include
illustrative
embodiments of the present invention and illustrate various objects and
features thereof. In
addition, any measurements, specifications and the like shown in the figures
are intended to be
illustrative, and not restrictive. Therefore, specific structural and
functional details disclosed
herein are not to be interpreted as limiting, but merely as a representative
basis for teaching
one skilled in the art to variously employ the present invention.
[0046] The various embodiments to the present disclosure will be further
explained with
reference to the attached drawings, wherein like structures are referred to by
like numerals
throughout the several views. The drawings shown are not necessarily to scale,
with emphasis
instead generally being placed upon illustrating the principles of the present
invention. Further,
some features may be exaggerated to show details of particular components.
[0047] Among those benefits and improvements that have been disclosed,
other objects
and advantages of this invention will become apparent from the following
description taken in
conjunction with the accompanying figures. Detailed embodiments of the present
invention
are disclosed herein; however, it is to be understood that the disclosed
embodiments are merely
illustrative of the invention that may be embodied in various forms. In
addition, each of the
examples given in connection with the various embodiments of the invention is
intended to be
illustrative, and not restrictive.
[0048] Throughout the specification and claims, the following terms take
the meanings
explicitly associated herein, unless the context clearly dictates otherwise.
The phrases "in one
embodiment" and "in some embodiments" as used herein do not necessarily refer
to the same
embodiment(s), though they may. Furthermore, the phrases "in another
embodiment" and "in
some other embodiments" as used herein do not necessarily refer to a different
embodiment,
although they may. Thus, as described below, various embodiments of the
invention may be
readily combined, without departing from the scope or spirit of the invention.
[0049] In addition, as used herein, the term "or" is an inclusive "or"
operator, and is
equivalent to the term "and/or," unless the context clearly dictates
otherwise. The term "based
on" is not exclusive and allows for being based on additional factors not
described, unless the
context clearly dictates otherwise. In addition, throughout the specification,
the meaning of
"a," "an," and "the" include plural references, unless the context clearly
dictates
otherwise. The meaning of "in" includes "in" and "on", unless the context
clearly dictates
otherwise.
BRIEF DESCRIPTION OF THE DRAWINGS
[0050] FIG. 1 is an image of the grain structure of alloy A1-1.
12
CA 03121042 2021-05-25
WO 2020/117748 PCT/US2019/064148
[0051] FIG. 2 is an image of the grain structure of alloy A1-10.
[0052] FIG. 3 is an image of the grain structure of alloy A1-19.
[0053] FIG. 4 is an image of the grain structure of alloy A1-22.
[0054] FIG. 5 is a graph illustrating the tensile yield strength (after
paint bake, no pre-
strain, i.e., T6) versus n value (10-20%) in the as is (T4) temper for various
example alloys.
[0055] FIG. 6 is a graph illustrating the tensile yield strength (after
paint bake, no pre-
strain, i.e., T6) versus uniform elongation in the as is (T4) temper for
various example alloys.
[0056] FIG. 7 is a graph illustrating the tensile yield strength (after
paint bake, 2% pre-
strain, i.e., T8) versus n value (10-20%) in the as is (T4) temper for various
example alloys.
[0057] FIG. 8 is a graph illustrating the tensile yield strength (after
paint bake, 2% pre-
strain, i.e., T8) versus uniform elongation in the as is (T4) temper for
various example alloys.
DETAILED DESCRIPTION
[0058] The following examples are intended to illustrate the invention and
should not be
construed as limiting the invention in any way.
Example 1: Alloy Composition
[0059] Aluminum alloys having the compositions shown in Table 1, below,
were cast as
ingots.
Table 1: Compositions of Example 1 Alloys (wt. %)
Sample Si Fe Cu
Mn Mg Cr Ti Zn Bal.
Al +
Alloy Al (inv.) 0.74 0.18 0.13 0.07 0.52 0.03
0.03 0.005 Imp.
Al +
Alloy A2 (inv.) 0.76 0.14 0.13 0.07 0.54 0.03
0.03 0.007 Imp.
Alloy Bl (non- Al +
inv.) 0.63
0.21 0.13 0.07 0.60 0.03 0.02 0.004 Imp.
[0060] The ingots were then homogenized and then hot rolled to an
intermediate gauge
with an exit temperature of not greater than 290 C. The alloys were then cold
rolled to a final
gauge of 0.95 or 1.2 mm. The cold rolling amounts (reduction from the
intermediate gauge to
the final gauge) are provided in Table 2, below. The final gauge products were
then solution
heat treated by heating to various peak metal temperatures (shown in Table 2),
after which the
alloys were immediately air quenched. After quenching, some alloys were then
stretched while
others were not, as shown in Table 2. All alloys were then naturally aged for
30 days, after
which some alloys were then stretched, and after which some alloys (both
stretched and non-
13
CA 03121042 2021-05-25
WO 2020/117748
PCT/US2019/064148
stretched) were artificially aged by heating to 180 C and then holding at this
temperature for
20 minutes, and then cooling to room temperature. The 2% stretching (pre-
strain) was
completed in the lab and simulates a typical forming operation.
[0061] Mechanical properties of the alloys in various tempers (T4, T6, T8)
were then
measured, the results of which are provided in Table 3, below. Mechanical
properties were
tested according to ASTM E8, ASTM B557. All reported mechanical property
values are for
the LT (long-transverse) direction, and based on the average of 6 specimens,
unless otherwise
indicated. The "n value" was measured in accordance ASTM E646 using 10-20%
strain.
Table 2: Processing of Example 1 Alloys
Artificial
Peak Metal Aging
Alloy Cold Work (% Final Gauge Temperature Stretch (min at
Number reduction) (mm) ( C) (%) 185 C)
A1-1 82% 0.95 552 0% 0
A1-2 82% 0.95 539 0% 0
A1-3 82% 0.95 533 0% 0
A1-4 82% 0.95 552 0% 20
A1-5 82% 0.95 539 0% 20
A1-6 82% 0.95 533 0% 20
A1-7 82% 0.95 552 2% 20
A1-8 82% 0.95 539 2% 20
A1-9 82% 0.95 533 2% 20
A1-10 81% 1.20 552 0% 0
A1-11 81% 1.20 539 0% 0
A1-12 81% 1.20 533 0% 0
A1-13 81% 1.20 552 0% 20
A1-14 81% 1.20 539 0% 20
A1-15 81% 1.20 533 0% 20
A1-16 81% 1.20 552 2% 20
A1-17 81% 1.20 539 2% 20
A1-18 81% 1.20 533 2% 20
A1-19 72% 0.95 552 0% 0
A1-20 72% 0.95 539 0% 0
A1-21 72% 0.95 533 0% 0
A1-22 65% 1.20 552 0% 0
A1-23 65% 1.20 539 0% 0
A1-24 65% 1.20 533 0% 0
A2-1 82% 0.95 552 0% 0
A2-2 82% 0.95 539 0% 0
A2-3 82% 0.95 533 0% 0
14
CA 03121042 2021-05-25
WO 2020/117748
PCT/US2019/064148
Artificial
Peak Metal Aging
Alloy Cold Work (% Final Gauge Temperature Stretch (min at
Number reduction) (mm) ( C) (%) 185 C)
A2-4 82% 0.95 552 0% 20
A2-5 82% 0.95 539 0% 20
A2-6 82% 0.95 533 0% 20
A2-7 82% 0.95 552 2% 20
A2-8 82% 0.95 539 2% 20
A2-9 82% 0.95 533 2% 20
A2-10 81% 1.20 552 0% 0
A2-11 81% 1.20 539 0% 0
A2-12 81% 1.20 533 0% 0
A2-13 81% 1.20 552 0% 20
A2-14 81% 1.20 539 0% 20
A2-15 81% 1.20 533 0% 20
A2-16 81% 1.20 552 2% 20
A2-17 81% 1.20 539 2% 20
A2-18 81% 1.20 533 2% 20
A2-19 72% 0.95 552 0% 0
A2-20 72% 0.95 539 0% 0
A2-21 72% 0.95 533 0% 0
A2-22 65% 1.20 552 0% 0
A2-23 65% 1.20 539 0% 0
A2-24 65% 1.20 533 0% 0
B1-1 82% 0.95 552 0% 0
B1-2 82% 0.95 539 0% 0
B1-3 82% 0.95 533 0% 0
B1-4 82% 0.95 552 0% 20
B1-5 82% 0.95 539 0% 20
B1-6 82% 0.95 533 0% 20
B1-7 82% 0.95 552 2% 20
B1-8 82% 0.95 539 2% 20
B1-9 82% 0.95 533 2% 20
B1-10 81% 1.20 552 0% 0
B1-11 81% 1.20 539 0% 0
B1-12 81% 1.20 533 0% 0
B1-13 81% 1.20 552 0% 20
B1-14 81% 1.20 539 0% 20
B1-15 81% 1.20 533 0% 20
B1-16 81% 1.20 552 2% 20
B1-17 81% 1.20 539 2% 20
B1-18 81% 1.20 533 2% 20
CA 03121042 2021-05-25
WO 2020/117748
PCT/US2019/064148
Table 3: Tensile Properties of Various Example 2 Alloys
Tensile Ultimate
Yield Tensile Ultimate Tensile
Alloy Strength Strength Elongation Elongation n Value
Number (MPa) (MPa) (%) (%) (10-
20%)
A1-1 108 218 22.1 26.3 0.25
A1-2 105 213 20.7 23.9 0.244
A1-3 101 208 21.3 25.5 0.24
A1-4 187 274 18.1 22.7 0.185
A1-5 178 264 17.8 22 0.182
A1-6 173 258 17.7 22.6 0.178
A1-7 220 286 16.3 20.3 0.164
A1-8 216 278 15.3 19 0.155
A1-9 208 271 15.1 19.1 0.154
A1-10 110 217 21.7 26.3 0.245
A1-11 104 210 21 25.4 0.239
A1-12 98 201 19.6 22.7 0.238
A1-13 189 273 17.9 23.3 0.179
A1-14 182 265 17.1 21.7 0.174
A1-15 168 251 15.9 20.7 0.175
A1-16 222 285 15.9 20.1 0.157
A1-17 212 275 15.4 19.3 0.156
A1-18 201 263 14 17.5 0.152
A1-19 106 216 22.4 26 0.258
A1-20 103 211 22 25.4 0.252
A1-21 100 207 21.2 25.4 0.249
A1-22 108 216 22.3 26.5 0.253
A1-23 103 207 20.3 26.3 0.248
A1-24 96 200 21.2 24.8 0.245
A2-1 113 225 22.4 27.0 0.255
A2-2 110 219 21.6 25.7 0.248
A2-3 105 212 20.5 22.0 0.244
A2-4 194 280 18.6 23.3 0.186
A2-5 192 276 17.9 22.5 0.181
A2-6 188 272 17.2 22.0 0.174
A2-7 227 292 16.4 20.8 0.165
A2-8 221 285 15.5 19.8 0.161
A2-9 220 281 14.3 17.0 0.153
A2-10 114 223 21.2 25.5 0.247
A2-11 107 214 21.0 25.2 0.241
A2-12 101 205 20.4 24.3 0.239
A2-13 196 279 17.6 22.3 0.179
A2-14 186 268 17.0 21.6 0.175
16
CA 03121042 2021-05-25
WO 2020/117748
PCT/US2019/064148
Tensile Ultimate
Yield Tensile Ultimate Tensile
Alloy Strength Strength Elongation Elongation n
Value
Number (MPa) (MPa) (%) (%) (10-20%)
A2-15 173 255 16.3 20.5 0.173
A2-16 226 289 15.9 20.3 0.160
A2-17 214 277 15.5 18.7 0.159
A2-18 201 264 14.9 18.9 0.155
A2-19 112 223 23.1 27.0 0.264
A2-20 109 218 22.4 26.2 0.257
A2-21 104 212 22.3 26.2 0.253
A2-22 113 225 22.4 27.0 0.255
A2-23 110 219 21.6 25.7 0.248
A2-24 105 212 20.5 22.0 0.244
B1-1 107 215 20.7 25 0.242
B1-2 101 207 20.8 25 0.236
B1-3 93 196 19.9 23.3 0.233
B1-4 176 264 18.1 22.6 0.187
B1-5 171 256 16.9 21.3 0.178
B1-6 156 242 16.6 20.2 0.179
B1-7 211 278 15.6 20.3 0.162
B1-8 202 267 15.6 20.1 0.157
B1-9 189 254 14.8 18.1 0.155
B1-10 107 213 20.8 24.3 0.239
B1-11 98 201 20.7 24.6 0.234
B1-12 88 188 20.4 24.9 0.23
B1-13 177 262 17.5 22.3 0.181
B1-14 163 249 16.7 20.3 0.18
B1-15 141 226 14.7 17.4 0.183
B1-16 210 273 15.4 20.1 0.158
B1-17 195 259 14.6 17.9 0.157
B1-18 172 235 13.1 16.2 0.155
[0062] For all processing conditions, the invention alloys achieved higher
tensile yield
strengths (TYS) and ultimate yield strengths (UTS) than non-invention alloys.
Further, the
invention alloys showed less strength loss at lower peak metal temperatures.
The invention
alloys also generally had higher elongation and higher n values over non-
invention alloys at
most processing conditions, indicating improved formability.
17
CA 03121042 2021-05-25
WO 2020/117748 PCT/US2019/064148
Example 2: Hem Performance Testing
[0063] Select Example 1 alloys were tested for hemming performance by
stretching them
15% in the L direction after which a flat hem test was performed. The
stretching was completed
on alloys that had been naturally aged for 30 days and without subsequent
artificial aging, i.e.,
the alloys were in a T4 temper prior to the 15% stretching. Four hems were
completed for each
processing condition. The hem ratings were then evaluated per the below scale.
Hem Rating Scale
1 or 2 Mild (1) to moderate (2) orange peel with
no cracking visible at 3x magnification
3 Crack(s) visible with 3x magnification
4 Cracks visible with naked eye
Table 4, below, shows the achieved hem ratings for Al and A2 alloys.
Table 4: Hem Ratings of Select Example 2 Alloys
Hem Hem
Alloy rating Alloy rating
Number (1-4) Number (1-4)
A1-1 2 A2-1 2
A1-2 2 A2-2 2
A1-3 2 A2-3 2
A1-10 2 A2-10 2
A1-11 2 A2-11 2
A1-12 2 A2-12 2
A1-19 2 A2-19 2
A1-20 2 A2-20 2
A1-21 2 A2-21 2
A1-22 2 A2-22 3
A1-23 2 A2-23 3
A1-24 2 A2-24 3
[0064] Al alloys have more iron than A2 alloys. Those in industry have
associated higher
iron content to poorer hemming performance. However, the Al alloys
demonstrated better
hemming performance than the A2 alloys. Further, higher iron content improved
hemming
performance in samples with lower levels of cold working (e.g. alloys A1-22,
A1-23 and Al-
24 had 65% cold work and demonstrated the same hemming performance as alloys
A1-10, Al-
11 and A1-12, which were the same gauge but only 81% cold work).
18
CA 03121042 2021-05-25
WO 2020/117748 PCT/US2019/064148
Example 3: VDA Bend Performance Testing
[0065]
Select Example 1 were stretched 10% in the L direction and tested per the VDA
238-100 bend test specification. (https ://www.vda.
de/en/services/Publications/vda-23 8-100-
plate-bending-test-for-metallic-materials html) VDA stands for
"Verband der
Automobilindustrie". The stretching was completed on alloys that has been
naturally aged for
30 days and without subsequent artificial aging, i.e., the alloys were in a T4
temper prior to the
10% stretching. Table 5, below, shows the VDA bend test results for select
Example 2 alloys.
Table 5: VDA Bend Test Results of select Example 2 Alloys
VDA VDA
Alloy Bend Alloy Bend
Number Angle ( ) Number Angle ( )
A1-10 140 A2-10 140
A1-11 142 A2-11 141
A1-12 143 A2-12 143
A1-22 129 A2-22 127
A1-23 133 A2-23 127
A1-24 137 A2-24 129
[0066] At
65% cold work the Al alloys demonstrated improved bending over the A2
alloys. It is believed that at least the difference in iron content
contributed to this difference in
properties. (A difference of 2 is a material difference at these levels of
achieved bend angle.)
Example 4: Ludering
[0067]
Select samples of Example 1 alloys were naturally aged 8 days and then
stretched
10% in the LT direction, after which a coating of paint was applied. After
painting, the alloys
were examined to determine if Luder bands were present. Table 6, below, shows
the tensile
yield strength and Luder band results for select Example 2 alloys.
Table 6: Ludering Results of Select Example 1 Alloys
Alloy TYS Ludering
Number (MPa) Present
A1-1 108 No
A1-2 105 No
A1-3 101 No
A1-10 108 No
A1-11 103 No
A1-12 96 No
19
CA 03121042 2021-05-25
WO 2020/117748 PCT/US2019/064148
Alloy TYS Ludering
Number (MPa) Present
A1-13 106 No
A1-14 103 No
A1-15 100 No
A1-19 110 No
A1-20 104 No
A1-21 98 No
B1-1 107 No
B1-2 98 No
B1-3 88 Yes
B1-10 107 No
B1-11 101 Yes
B1-12 93 Yes
[0068] As shown in Table 6, only non-invention alloys showed the presence
of Luder
bands. For a range of alloy processing, invention alloys did not have any
Luder bands present.
Example 5: Texture and grain size
[0069] Grain size and texture measurements of select Al samples from
Example 2 were
obtained via electron backscattering detection in a scanning electron
microscope. The results
of the grain size and texture measurements are shown in Table 7, below.
Further, grain
structure images obtained via SEM are shown in FIGS. 1-4.
Table 7: Grain Size and Texture Values for select Example 2 alloys
Alloy Number A1-10 A1-22
Gauge (mm) 1.2 1.2
Cold Work (%) 81 65
Grain Size Via
Intercept Method
(pun) 18.6 23.2
Grain Grain Size
Size Number Ave. (pm) 20.6 25
Grain Size Area
Ave. (weighted)
(lm) 32.1 40.9
Cube % 21.8 14.97
Goss % 1.99 1.8
Texture Brass % 0.98 0.81
S % 2.26 2.78
Copper % 1.98 2.27
CA 03121042 2021-05-25
WO 2020/117748 PCT/US2019/064148
[0070] Table 7 show that with higher levels of cold working, the Al alloys
have finer
(smaller) grain structure and higher levels of Cube texture. FIGS. 1-4 show
the grain structure
images obtained via SEM for alloys A1-1, A1-10, A1-19, and A1-22. The weighted
average
grain sizes obtained from these images for alloys A1-1, A1-10, A1-19, and A1-
22 were 32 um,
32 pm, 34 um, and 41 um, respectively. Again, with higher levels of cold
working, the Al
alloy have finer (smaller) grain structure. When invention and non-invention
alloys of the same
processing were compared for grain size measurements, alloy A1-1 had a coarser
grain
structure than alloy B1-1.
[0071] Thus, in some embodiments, the new alloys disclosed herein may have
grain size
area weighted average of from 20 micrometers to 45 micrometers. In one
embodiment, the
new alloys have a grain size of from 30 to 40 micrometers.
[0072] In some embodiments, the new alloys disclosed herein may be in sheet
form and
have the following texture characteristics:
Texture Type Min (%) (Max (%)
Cube 10 25
Goss 0 2.0
Brass 0 1.5
0 3.0
Copper 0 2.5
[0073] While various embodiments of the present disclosure have been
described in detail,
it is apparent that modifications and adaptations of those embodiments will
occur to those
skilled in the art. However, it is to be expressly understood that such
modifications and
adaptations are within the spirit and scope of the present disclosure.
21
