U.S. patent application number 15/336443 was filed with the patent office on 2017-05-04 for wrought 7xxx aluminum alloys, and methods for making the same.
The applicant listed for this patent is ALCOA INC.. Invention is credited to James Daniel Bryant, Jen C. Lin, Eider Simielli, Xinyan Yan, Wenping Zhang.
Application Number | 20170121795 15/336443 |
Document ID | / |
Family ID | 58631907 |
Filed Date | 2017-05-04 |
United States Patent
Application |
20170121795 |
Kind Code |
A1 |
Yan; Xinyan ; et
al. |
May 4, 2017 |
WROUGHT 7XXX ALUMINUM ALLOYS, AND METHODS FOR MAKING THE SAME
Abstract
New wrought 7xxx aluminum alloys are disclosed. The new wrought
7xxx aluminum alloys generally include from 3.75 to 8.0 wt. % Zn,
from 1.25 to 3.0 wt. % Mg, where the wt. % Zn exceeds the wt. % Mg,
from 0.35 to 1.35 wt. % Cu, from 0.04 to 0.20 wt. % V, from 0.06 to
0.20 wt. % Zr, where V+Zr.ltoreq.0.23 wt. %, from 0.01 to 0.25 wt.
% Ti, up to 0.50 wt. % Mn, up to 0.40 wt. % Cr, up to 0.35 wt. %
Fe, and up to 0.25 wt. % Si, the balance being aluminum and
impurities, wherein the wrought 7xxx aluminum alloy include not
greater than 0.10 wt. % each of any one impurity, and wherein the
wrought 7xxx aluminum alloy includes not greater than 0.35 wt. % in
total of the impurities.
Inventors: |
Yan; Xinyan; (Murrysville,
PA) ; Bryant; James Daniel; (Murrysville, PA)
; Lin; Jen C.; (Export, PA) ; Zhang; Wenping;
(Murrysville, PA) ; Simielli; Eider; (Monroeville,
PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ALCOA INC. |
Pittsburgh |
PA |
US |
|
|
Family ID: |
58631907 |
Appl. No.: |
15/336443 |
Filed: |
October 27, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62248165 |
Oct 29, 2015 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C22C 21/10 20130101;
C22F 1/053 20130101 |
International
Class: |
C22C 21/10 20060101
C22C021/10 |
Claims
1. A wrought 7xxx aluminum alloy consisting of: (a) from 3.75 to
8.0 wt. % Zn; (b) from 1.25 to 3.0 wt. % Mg; (c) from 0.35 to 1.35
wt. % Cu; (d) from 0.04 to 0.20 wt. % V; (e) from 0.06 to 0.20 wt.
% Zr; wherein V+Zr.ltoreq.0.23 wt. %; (f) from 0.01 to 0.25 wt. %
Ti; (g) up to 0.50 wt. % Mn; (h) up to 0.40 wt. % Cr; (i) up to
0.35 wt. % Fe; and (j) up to 0.25 wt. % Si; (k) the balance being
aluminum and impurities, wherein the wrought 7xxx aluminum alloy
wrought 7xxx aluminum alloy includes not greater than 0.10 wt. %
each of any one impurity, and wherein the wrought 7xxx aluminum
alloy includes not greater than 0.35 wt. % in total of the
impurities.
2. The wrought 7xxx aluminum alloy of claim 1, wherein the wrought
7xxx aluminum alloy is a forged wheel product.
3. The wrought 7xxx aluminum alloy of claim 1, wherein the wrought
7xxx aluminum alloy is a forged wheel product in the T5 temper.
4. The wrought 7xxx aluminum alloy of claim 1, wherein the wrought
7xxx aluminum alloy is a forged wheel product in the T5 temper, and
wherein the wrought 7xxx aluminum alloy realizes a quench
insensitivity of not greater than 7 ksi.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This patent application claims priority to Prov. U.S. Pat.
App. Ser. No. 62/248,165, filed Oct. 29, 2015 and entitled "WROUGHT
7XXX ALUMINUM ALLOYS, AND METHODS FOR MAKING THE SAME," the entire
disclosure of which is hereby incorporated herein by reference.
[0002] This patent application is related to commonly-owned U.S.
patent application Ser. No. 14/694,109, filed Apr. 23, 2015,
entitled "IMPROVED 7XX ALUMINUM CASTING ALLOYS, AND METHODS FOR
MAKING THE SAME".
BACKGROUND
[0003] Aluminum alloys are useful in a variety of applications.
However, improving one property of an aluminum alloy without
degrading another property is elusive. For example, it is difficult
to increase the strength or corrosion resistance of a wrought 7xxx
aluminum alloy without affecting other properties.
SUMMARY OF THE DISCLOSURE
[0004] Broadly, the present patent application relates to improved
wrought 7xxx aluminum alloys, and methods for producing the same.
The new wrought 7xxx aluminum alloys may realize, for instance, an
improved combination of at least two of strength, corrosion
resistance, fatigue failure resistance, and quench insensitivity,
among other properties.
[0005] The new wrought 7xxx aluminum alloys generally comprise (and
in some instance consist essentially of, or consist of), zinc (Zn),
magnesium (Mg), copper (Cu), vanadium (V), zirconium (Zr), and
titanium (Ti), as primary alloying elements, optionally with
manganese (Mn) and/or chromium (Cr), the balance being aluminum
(Al), iron (Fe), silicon (Si), and unavoidable impurities, as
defined below. Some embodiments of new wrought 7xxx aluminum alloy
compositions are shown in FIG. 1.
[0006] Regarding zinc, the new wrought 7xxx aluminum alloys
generally include from 3.75 to 8.0 wt. % Zn. In one embodiment, a
new wrought 7xxx aluminum alloy includes not greater than 7.5 wt. %
Zn. In another embodiment, a new wrought 7xxx aluminum alloy
includes not greater than 7.0 wt. % Zn. In yet another embodiment,
a new wrought 7xxx aluminum alloy includes not greater than 6.5 wt.
% Zn. In another embodiment, a new wrought 7xxx aluminum alloy
includes not greater than 6.0 wt. % Zn. In yet another embodiment,
a new wrought 7xxx aluminum alloy includes not greater than 5.5 wt.
% Zn. In another embodiment, a new wrought 7xxx aluminum alloy
includes not greater than 5.0 wt. % Zn. In another embodiment, a
new wrought 7xxx aluminum alloy includes not greater than 4.75 wt.
% Zn. In one embodiment, a new wrought 7xxx aluminum alloy includes
at least 4.0 wt. % Zn. In another embodiment, a new wrought 7xxx
aluminum alloy includes at least 4.25 wt. % Zn. In yet another
embodiment, a new wrought 7xxx aluminum alloy includes at least
4.35 wt. % Zn.
[0007] The new wrought 7xxx aluminum alloys generally include
magnesium in the range of from 1.25 to 3.0 wt. % Mg. In one
embodiment, a new wrought 7xxx aluminum alloy includes not greater
than 2.75 wt. % Mg. In another embodiment, a new wrought 7xxx
aluminum alloy includes not greater than 2.5 wt. % Mg. In yet
another embodiment, a new wrought 7xxx aluminum alloy includes not
greater than 2.25 wt. % Mg. In another embodiment, a new wrought
7xxx aluminum alloy includes not greater than 2.0 wt. % Mg. In yet
another embodiment, a new wrought 7xxx aluminum alloy includes not
greater than 1.8 wt. % Mg. In one embodiment, a new wrought 7xxx
aluminum alloy includes at least 1.35 wt. % Mg. In another
embodiment, a new wrought 7xxx aluminum alloy includes at least
1.40 wt. % Mg. In yet another embodiment, a new wrought 7xxx
aluminum alloy includes at least 1.45 wt. % Mg. In another
embodiment, a new wrought 7xxx aluminum alloy includes at least
1.50 wt. % Mg.
[0008] In some embodiments, the amount of zinc and magnesium may be
limited (e.g., to improve corrosion resistance). Thus, in one
embodiment, the combined amount of zinc and magnesium in a new
wrought 7xxx aluminum alloy may be not greater than 7.0 wt. %
(i.e., wt. % Zn+wt. % Mg.ltoreq.7.0 wt. %). In another embodiment,
the combined amount of zinc and magnesium in a new wrought 7xxx
aluminum alloy is not greater than 6.75 wt. % (i.e., wt. % Zn+wt. %
Mg.ltoreq.6.75 wt. %). In yet another embodiment, the combined
amount of zinc and magnesium in a new wrought 7xxx aluminum alloy
is not greater than 6.50 wt. % (i.e., wt. % Zn+wt. % Mg.ltoreq.6.50
wt. %). In another embodiment, the combined amount of zinc and
magnesium in a new wrought 7xxx aluminum alloy is not greater than
6.25 wt. % (i.e., wt. % Zn+wt. % Mg.ltoreq.6.25 wt. %). In yet
another embodiment, the combined amount of zinc and magnesium in a
new wrought 7xxx aluminum alloy is not greater than 6.00 wt. %
(i.e., wt. % Zn+wt. % Mg.ltoreq.6.00 wt. %).
[0009] The new wrought 7xxx aluminum alloys generally include
copper and in the range of from 0.35 to 1.35 wt. % Cu, and where
the amount of magnesium exceeds the amount of copper. As shown
below, copper may facilitate, for example, improved corrosion
resistance (e.g., improved SCC resistance) and/or strength. In one
embodiment, a new wrought 7xxx aluminum alloy includes not greater
than 1.15 wt. % Cu. In another embodiment, a new wrought 7xxx
aluminum alloy includes not greater than 1.00 wt. % Cu. In yet
another embodiment, a new wrought 7xxx aluminum alloy includes not
greater than 0.95 wt. % Cu. In another embodiment, a new wrought
7xxx aluminum alloy includes not greater than 0.90 wt. % Cu. In yet
another embodiment, a new wrought 7xxx aluminum alloy includes not
greater than 0.85 wt. % Cu. In another embodiment, a new wrought
7xxx aluminum alloy includes not greater than 0.80 wt. % Cu. In one
embodiment, a new wrought 7xxx aluminum alloy includes at least
0.40 wt. % Cu. In another embodiment, a new wrought 7xxx aluminum
alloy includes at least 0.45 wt. % Cu. In yet another embodiment, a
new wrought 7xxx aluminum alloy includes at least 0.50 wt. % Cu. In
another embodiment, a new wrought 7xxx aluminum alloy includes at
least 0.55 wt. % Cu. In yet another embodiment, a new wrought 7xxx
aluminum alloy includes at least 0.60 wt. % Cu.
[0010] The new wrought 7xxx aluminum alloys generally include from
0.04 to 0.20 wt. % V. As shown below, vanadium may facilitate, for
example, improved corrosion resistance and/or quench insensitivity.
In one embodiment, a new wrought 7xxx aluminum alloy includes not
greater than 0.18 wt. % V. In another embodiment, a new wrought
7xxx aluminum alloy includes not greater than 0.16 wt. % V. In yet
another embodiment, a new wrought 7xxx aluminum alloy includes not
greater than 0.15 wt. % V. In another embodiment, a new wrought
7xxx aluminum alloy includes not greater than 0.14 wt. % V. In yet
another embodiment, a new wrought 7xxx aluminum alloy includes not
greater than 0.13 wt. % V. In another embodiment, a new wrought
7xxx aluminum alloy includes not greater than 0.12 wt. % V. In yet
another embodiment, a new wrought 7xxx aluminum alloy includes not
greater than 0.11 wt. % V. In one embodiment, a new wrought 7xxx
aluminum alloy includes at least 0.05 wt. % V. In another
embodiment, a new wrought 7xxx aluminum alloy includes at least
0.06 wt. % V. In yet another embodiment, a new wrought 7xxx
aluminum alloy includes at least 0.07 wt. % V. In another
embodiment, a new wrought 7xxx aluminum alloy includes at least
0.08 wt. % V.
[0011] The new wrought 7xxx aluminum alloys generally include from
0.06 to 0.20 wt. % Zr. As shown by the below data, the combination
of vanadium and zirconium may facilitate, for instance, improved
fatigue failure resistance properties. In one embodiment, a new
wrought 7xxx aluminum alloy includes not greater than 0.18 wt. %
Zr. In another embodiment, a new wrought 7xxx aluminum alloy
includes not greater than 0.16 wt. % Zr. In yet another embodiment,
a new wrought 7xxx aluminum alloy includes not greater than 0.15
wt. % Zr. In another embodiment, a new wrought 7xxx aluminum alloy
includes not greater than 0.14 wt. % Zr. In yet another embodiment,
a new wrought 7xxx aluminum alloy includes not greater than 0.13
wt. % Zr. In one embodiment, a new wrought 7xxx aluminum alloy
includes at least 0.07 wt. % Zr. In another embodiment, a new
wrought 7xxx aluminum alloy includes at least 0.08 wt. % Zr.
[0012] The total amount of vanadium plus zirconium should be
controlled to restrict formation of a high volume fraction of
constituent particles (e.g., a high volume fraction of Al.sub.3Zr,
Al.sub.23V.sub.4, Al.sub.7V and/or Al.sub.10V constituent
particles). In one embodiment, the total amount of vanadium plus
zirconium does not exceed 0.23 wt. % V+Zr. In another embodiment,
the total amount of vanadium plus zirconium does not exceed 0.22
wt. % V+Zr. In yet another embodiment, the total amount of vanadium
plus zirconium does not exceed 0.21 wt. % V+Zr. In another
embodiment, the total amount of vanadium plus zirconium does not
exceed 0.20 wt. % V+Zr. In one embodiment, the total volume
fraction of Al.sub.3Zr, Al.sub.23V.sub.4, Al.sub.7V and Al.sub.10V
constituent particles does not exceed 0.07%. The total volume
fraction of these constituent particles may be determined, for
instance, by Pandat.TM. software and the PanAluminum thermodynamic
database (CompuTherm LLC, 437 S. Yellowstone Dr. Suite 217,
Madison, Wis., USA). In one embodiment, the total volume fraction
of Al.sub.3Zr, Al.sub.23V.sub.4, Al.sub.7V and Al.sub.10V
constituent particles does not exceed 0.06%. In another embodiment,
the total volume fraction of Al.sub.3Zr, Al.sub.23V.sub.4,
Al.sub.7V and Al.sub.10V constituent particles does not exceed
0.05%. In yet another embodiment, the total volume fraction of
Al.sub.3Zr, Al.sub.23V.sub.4, Al.sub.7V and Al.sub.10V constituent
particles does not exceed 0.04%. In another embodiment, the total
volume fraction of Al.sub.3Zr, Al.sub.23V.sub.4, Al.sub.7V and
Al.sub.10V constituent particles does not exceed 0.03%. In yet
another embodiment, the total volume fraction of Al.sub.3Zr,
Al.sub.23V.sub.4, Al.sub.7V and Al.sub.10V constituent particles
does not exceed 0.02%. In another embodiment, the total volume
fraction of Al.sub.3Zr, Al.sub.23V.sub.4, Al.sub.7V and Al.sub.10V
constituent particles does not exceed 0.01%. In yet another
embodiment, the total volume fraction of Al.sub.3Zr,
Al.sub.23V.sub.4, Al.sub.7V and Al.sub.10V constituent particles
does not exceed 0.005%.
[0013] The new wrought 7xxx aluminum alloys generally include from
0.01 to 0.25 wt. % Ti. In one embodiment, a new wrought 7xxx
aluminum alloy includes from 0.01 to 0.15 wt. % Ti. In another
embodiment, a new wrought 7xxx aluminum alloy includes from 0.01 to
0.10 wt. % Ti. In yet another embodiment, a new wrought 7xxx
aluminum alloy includes from 0.01 to 0.08 wt. % Ti. In another
embodiment, a new wrought 7xxx aluminum alloy includes from 0.02 to
0.05 wt. % Ti. The titanium may be present (e.g., at least
partially present) in the form of TiB.sub.2 or TiC.
[0014] In some embodiments, the new wrought 7xxx aluminum alloys
may include up to 0.50 wt. % Mn. In embodiments where manganese is
utilized, the new wrought 7xxx aluminum alloys generally include
from 0.10 to 0.50 wt. % Mn. In one embodiment, a new wrought 7xxx
aluminum alloy includes from 0.10 to 0.25 wt. % Mn. In some
embodiments, the new wrought 7xxx aluminum alloys are substantially
free of manganese, and, in these embodiments, contain less than
0.10 wt. %. Mn (i.e., .ltoreq.0.09 wt. % Mn), such as .ltoreq.0.05
wt. % Mn, or .ltoreq.0.04 wt. % Mn, or .ltoreq.0.03 wt. % Mn.
[0015] In some embodiments, the new wrought 7xxx aluminum alloys
may include up to 0.40 wt. % Cr. In embodiments where chromium is
utilized, the new wrought 7xxx aluminum alloys generally include
from 0.10 to 0.40 wt. % Cr. In one embodiment, a new wrought 7xxx
aluminum alloy includes from 0.10 to 0.35 wt. % Cr. In another
embodiment, a new wrought 7xxx aluminum alloy includes from 0.10 to
0.25 wt. % Cr. In some embodiments, the new wrought 7xxx aluminum
alloys are substantially free of chromium, and, in these
embodiments, contain less than 0.10 wt. %. Cr (i.e., .ltoreq.0.09
wt. % Cr), such as .ltoreq.0.05 wt. % Cr, or .ltoreq.0.04 wt. % Cr,
or .ltoreq.0.03 wt. % Cr.
[0016] The new wrought 7xxx aluminum alloys may include iron, up to
0.35 wt. % Fe. In one embodiment, a new wrought 7xxx aluminum alloy
includes not greater than 0.25 wt. % Fe. In another embodiment, a
new wrought 7xxx aluminum alloy includes not greater than 0.20 wt.
% Fe. In yet another embodiment, a new wrought 7xxx aluminum alloy
includes not greater than 0.15 wt. % Fe. In another embodiment, a
new wrought 7xxx aluminum alloy includes not greater than 0.12 wt.
% Fe. In yet another embodiment, a new wrought 7xxx aluminum alloy
includes not greater than 0.10 wt. % Fe. In yet another embodiment,
a new wrought 7xxx aluminum alloy includes not greater than 0.08
wt. % Fe. In one embodiment, a new wrought 7xxx aluminum alloy
includes at least 0.01 wt. % Fe.
[0017] The new wrought 7xxx aluminum alloys may include silicon, up
to 0.25 wt. % Si. In one embodiment, a new wrought 7xxx aluminum
alloy includes not greater than 0.20 wt. % Si. In another
embodiment, a new wrought 7xxx aluminum alloy includes not greater
than 0.15 wt. % Si. In yet another embodiment, a new wrought 7xxx
aluminum alloy includes not greater than 0.10 wt. % Si. In yet
another embodiment, a new wrought 7xxx aluminum alloy includes not
greater than 0.08 wt. % Si. In another embodiment, a new wrought
7xxx aluminum alloy includes not greater than 0.05 wt. % Si. In one
embodiment, a new wrought 7xxx aluminum alloy includes at least
0.01 wt. % Si.
[0018] The balance of the new wrought 7xxx aluminum alloy is
generally aluminum and unavoidable impurities. In one embodiment,
the new wrought 7xxx aluminum alloys contain not more than 0.10 wt.
% each of any one impurity (measured on an elemental basis), with
the total combined amount of these impurities not exceeding 0.35
wt. % in the new wrought 7xxx aluminum alloy (i.e., .ltoreq.0.10
wt. % each of any one impurity, and with the total impurities being
.ltoreq.0.35 wt. %). In another embodiment, each one of the
impurities, individually, does not exceed 0.05 wt. % in the new
wrought 7xxx aluminum alloy, and the total combined amount of the
impurities does not exceed 0.15 wt. % in the new wrought 7xxx
aluminum alloy (i.e., .ltoreq.0.05 wt. % each of any one impurity,
and with the total impurities being .ltoreq.0.15 wt. %). In another
embodiment, each one of these impurities, individually, does not
exceed 0.03 wt. % in the new wrought 7xxx aluminum alloy, and the
total combined amount of these impurities does not exceed 0.10 wt.
% in the new wrought 7xxx aluminum alloys (i.e., .ltoreq.0.03 wt. %
each of any one impurity, and with the total impurities being
.ltoreq.0.10 wt. %).
[0019] The new wrought 7xxx aluminum alloys described herein may be
cast (e.g., as ingot or billet), then homogenized, and then hot
worked to an intermediate or final form (e.g., cold working after
the hot working when the hot working produces an intermediate
form). In one embodiment, the hot working is forging. In one
embodiment, the forging produces a shaped product, such as a wheel
product. In another embodiment, the hot working is rolling or
extruding. After the hot working (and any optional cold working),
the new alloy may be tempered, such as by solution heat treating,
and then quenching, and then natural aging, followed by artificial
aging. Suitable tempers include the T4, T5, T6, and T7 tempers, for
instance, as defined in ANSI H35.1 (2009). In one embodiment, the
new alloy compositions described herein are processed into a forged
wheel product per the processes described in commonly-owned U.S.
Patent Application Publication No. 2006/0000094, which is
incorporated herein by reference in its entirety. In one
embodiment, the new wrought 7xxx aluminum alloys described herein
are processed to a T5 temper (e.g., a T53 temper), which may
include press quenching the new wrought 7xxx aluminum alloys (e.g.,
in the form of a forged wheel) after solution heat treatment.
[0020] As mentioned above, the new wrought 7xxx aluminum alloys may
realize improved quench insensitivity. Quench insensitivity relates
to an aluminum alloy's sensitivity to the quench conditions used
after solution heat treatment. One indicator of quench sensitivity
is a significant drop in strength with low quench rates as compared
to high quench rates. As shown by the below examples, the new
wrought 7xxx aluminum alloys described herein may be relatively
quench insensitive. For purposes of this application, quench
insensitivity is measured by conventionally producing a new wrought
7xxx aluminum alloy as a rolled plate having a final gauge of 1.0
inch (2.54 mm), after which two identical pieces of this plate are
solution heat treated, after which one piece is cold water quenched
in 77.degree. F. (25.degree. C.) water and the other piece is
boiling water quenched, both for a period of 10 minutes, after
which the pieces are allowed to air dry. The two pieces are then
both naturally aged for 24 hours and then both two-step
artificially aged with a first step of 250.degree. F. for 3 hours
(with a 2-hour heat up from ambient to 250.degree. F.) and a second
step of 340.degree. F. for 8 hours. The longitudinal (L) tensile
yield strengths of these two pieces are then measured at T/2 in
accordance with ASTM B557 and E8, using at least duplicate
specimens, after which the measured strengths are averaged for each
piece. The average TYS(L) of the cold water quenched ("CWQ") piece
is then compared to the average TYS(L) of the boiling water
quenched (BWQ'') TYS. The difference between the two average TYS
values (i.e., CWQ(TYS)-BWQ(TYS)) is the quench insensitivity of the
alloy.
[0021] In one embodiment, a new wrought 7xxx aluminum alloy
realizes a quench insensitivity (as defined above) of not greater
than 7 ksi (i.e., CWQ(TYS)-BWQ(TYS).ltoreq.7 ksi). In another
embodiment, a new wrought 7xxx aluminum alloy realizes a quench
insensitivity of not greater than 6 ksi. In yet another embodiment,
a new wrought 7xxx aluminum alloy realizes a quench insensitivity
of not greater than 5 ksi. In another embodiment, a new wrought
7xxx aluminum alloy realizes a quench insensitivity of not greater
than 4 ksi. In yet another embodiment, a new wrought 7xxx aluminum
alloy realizes a quench insensitivity of not greater than 3 ksi. In
another embodiment, a new wrought 7xxx aluminum alloy realizes a
quench insensitivity of not greater than 2 ksi. In yet another
embodiment, a new wrought 7xxx aluminum alloy realizes a quench
insensitivity of not greater than 1 ksi. In another embodiment, a
new wrought 7xxx aluminum alloy realizes a quench insensitivity of
not greater than 0 ksi, meaning the boiling water quenched alloy
realizes at least equivalent strength to the cold water quenched
alloy. In yet another embodiment, a new wrought 7xxx aluminum alloy
realizes a quench insensitivity of not greater than -1 ksi, meaning
the boiling water quenched alloy realizes higher strength than the
cold water quenched alloy. In another embodiment, a new wrought
7xxx aluminum alloy realizes a quench insensitivity of not greater
than -2 ksi. In another embodiment, a new wrought 7xxx aluminum
alloy realizes a quench insensitivity of not greater than -3 ksi.
In another embodiment, a new wrought 7xxx aluminum alloy realizes a
quench insensitivity of not greater than -4 ksi. In another
embodiment, a new wrought 7xxx aluminum alloy realizes a quench
insensitivity of not greater than -5 ksi. In another embodiment, a
new wrought 7xxx aluminum alloy realizes a quench insensitivity of
not greater than -6 ksi. In another embodiment, a new wrought 7xxx
aluminum alloy realizes a quench insensitivity of not greater than
-7 ksi. In another embodiment, a new wrought 7xxx aluminum alloy
realizes a quench insensitivity of not greater than -8 ksi. In
another embodiment, a new wrought 7xxx aluminum alloy realizes a
quench insensitivity of not greater than -9 ksi, or more.
[0022] The quench insensitivity of the new wrought 7xxx aluminum
alloys may facilitate improved strength. Likewise, when using a hot
quench media, a new wrought 7xxx aluminum alloy may realize less
distortion.
[0023] The new wrought 7xxx aluminum alloys may be post-solution
heat treatment quenched with any applicable fluid or media. In one
embodiment, a new wrought 7xxx aluminum alloy is water quenched
(cold water quenched, hot water quenched, or boiling water
quenched). In one embodiment, the new wrought 7xxx aluminum alloy
is hot or boiling water quenched. A hot water quench is a quenching
using water having a temperature of from 150.degree. F. to boiling
(212.degree. F. at standard temperature and pressure). A boiling
water quench uses boiling water. A boiling water quench is a
species of the hot water quench genus. As shown by the below data,
use of a hot water quench (including a boiling water quench) may
facilitate improved SCC resistance. In another embodiment, a new
wrought 7xxx aluminum alloy is air quenched (e.g., via a forced air
quench). In yet another embodiment, a new wrought 7xxx aluminum
alloy is press-quenched. In one embodiment, the quenching step
results in an average cooling rate of from 1.degree. F. to
25.degree. F. per second as measured during the first 60 seconds of
the quench. In another embodiment, the quenching step results in an
average cooling rate of not greater than 22.5.degree. F. per second
as measured during the first 60 seconds of the quench. In yet
another embodiment, the quenching step results in an average
cooling rate of not greater than 20.degree. F. per second as
measured during the first 60 seconds of the quench. In another
embodiment, the quenching step results in an average cooling rate
of not greater than 17.5.degree. F. per second as measured during
the first 60 seconds of the quench. In yet another embodiment, the
quenching step results in an average cooling rate of not greater
than 15.degree. F. per second as measured during the first 60
seconds of the quench. In another embodiment, the quenching step
results in an average cooling rate of not greater than 12.5.degree.
F. per second as measured during the first 60 seconds of the
quench. In yet another embodiment, the quenching step results in an
average cooling rate of not greater than 10.degree. F. per second
as measured during the first 60 seconds of the quench. In another
embodiment, the quenching step results in an average cooling rate
of not greater than 9.0.degree. F. per second as measured during
the first 60 seconds of the quench. In yet another embodiment, the
quenching step results in an average cooling rate of not greater
than 8.0.degree. F. per second as measured during the first 60
seconds of the quench. In another embodiment, the quenching step
results in an average cooling rate of not greater than 7.0.degree.
F. per second as measured during the first 60 seconds of the
quench. In yet another embodiment, the quenching step results in an
average cooling rate of not greater than 6.0.degree. F. per second
as measured during the first 60 seconds of the quench.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a table illustrating various embodiments of new
7xxx wrought aluminum alloy compositions.
DETAILED DESCRIPTION
Example 1
[0025] Several 7xxx aluminum alloys having the compositions shown
in Table 1, below, were cast as lab-scale, 2.5 inch (6.35 cm) thick
ingots (nominal). The ingots were then scalped, homogenized, and
hot rolled to a final gauge of 1.25 inch (3.175 cm). After hot
rolling, the plates were metallographically inspected. The
inspection revealed that plates 2, 14, 15, 17 and 18 contained a
high volume fraction of constituent particles due to excess V+Zr+Ti
content relative to the amount of Zn+Mg+Cu content of those
alloys.
[0026] The hot rolled plates were then solution heat treated, cold
water quenched, and then allowed to naturally age for about
24-hours. After natural aging, the plates were then two-step
artificially aged at 250.degree. F. for 3 hours and then
340.degree. F. for 8 hours. Several of the alloy samples in the
naturally aged condition were also artificially aged at 250.degree.
F. for 3 hours and then 340.degree. F. for 16 hours. The
longitudinal (L) mechanical properties of the artificially aged
plates were then measured at T/2 and in accordance with ASTM B557
and E8, the results of which are shown in Table 2, below (average
of duplicate specimens).
TABLE-US-00001 TABLE 1 Composition of the Example 1 Alloys (all
values in weight percent)* Alloy # Si Fe Zn Mg Cu V Zr V + Zr 1**
0.056 0.087 4.25 1.59 0.57 0.079 0.10 0.179 2 0.059 0.094 4.83 1.67
0.65 0.120 0.19 0.310 3** 0.057 0.095 5.20 1.60 0.64 0.082 0.10
0.182 4** 0.056 0.094 6.02 1.57 0.64 0.086 0.10 0.186 5 0.057 0.085
3.65 1.66 0.62 0.080 0.11 0.190 6 0.059 0.092 2.83 1.61 0.60 0.080
0.10 0.180 7** 0.064 0.093 4.39 1.99 0.62 0.088 0.10 0.188 8**
0.057 0.092 4.38 2.37 0.61 0.089 0.10 0.189 9 0.052 0.072 4.53 1.20
0.55 0.083 0.10 0.183 10 0.050 0.080 4.40 0.85 0.60 0.080 0.10
0.180 11** 0.058 0.084 4.41 1.63 0.88 0.084 0.10 0.184 12** 0.054
0.088 4.38 1.64 1.26 0.083 0.10 0.183 13** 0.055 0.088 4.35 1.63
0.42 0.082 0.12 0.202 14 0.059 0.092 4.44 1.67 0.61 0.200 0.10
0.300 15 0.059 0.086 4.46 1.62 0.61 0.160 0.11 0.270 16** 0.058
0.100 4.41 1.55 0.64 0.056 0.10 0.156 17 0.057 0.089 4.39 1.65 0.61
0.088 0.15 0.238 18 0.059 0.092 4.44 1.61 0.62 0.086 0.19 0.276
19** 0.054 0.084 4.36 1.62 0.59 0.086 0.06 0.146 20 0.056 0.088
4.31 1.6 0.61 0.078 0 0.078 *The balance of the alloys was Ti, Al
and impurities; all alloys contained 0.02-0.03 wt. % Ti, except
alloy 2 which contained 0.055 wt. % Ti; all alloys contained
.ltoreq.0.03 wt. % of any one impurity and .ltoreq.0.10 wt. % in
total of all impurities; impurities included Mn and Cr in this
example. **invention alloy
TABLE-US-00002 TABLE 2 Measured Mechanical Properties of the
Example 1 Alloys Alloy Artificial Aging TYS UTS Elong. # Practice
(MPa) (MPa) (% 1 250 F./3 hrs + 332.5 395.3 17.0 340 F./8 hrs 1 250
F./3 hrs + 323.8 389.3 16.0 340 F./16 hrs 3 250 F./3 hrs + 399.0
447.5 17.0 340 F./8 hrs 3 250 F./3 hrs + 371.3 428.3 18.0 340 F./16
hrs 4 250 F./3 hrs + 416.3 459.0 16.5 340 F./16 hrs 5 250 F./3 hrs
+ 285.8 365.3 17.5 340 F./8 hrs 5 250 F./3 hrs + 299.0 378.5 18.0
340 F./16 hrs 6 250 F./3 hrs + 224.5 317.0 21.5 340 F./16 hrs 7 250
F./3 hrs + 383.3 440.3 16.0 340 F./8 hrs 7 250 F./3 hrs + 383.8
444.0 15.5 340 F./16 hrs 8 250 F./3 hrs + 399.8 455.3 13.5 340
F./16 hrs 9 250 F./3 hrs + 304.5 360.5 15.0 340 F./8 hrs 9 250 F./3
hrs + 275.0 340.0 15.0 340 F./16 hrs 10 250 F./3 hrs + 231.0 298.0
19.5 340 F./16 hrs 11 250 F./3 hrs + 344.3 411.0 15.5 340 F./8 hrs
11 250 F./3 hrs + 358.3 424.8 16.0 340 F./16 hrs 12 250 F./3 hrs +
357.5 433.0 15.0 340 F./16 hrs 13 250 F./3 hrs + 332.8 391.3 17.0
340 F./8 hrs 13 250 F./3 hrs + 333.3 397.3 17.0 340 F./16 hrs 16
250 F./3 hrs + 368.8 424.8 16.5 340 F./8 hrs 16 250 F./3 hrs +
325.8 392.0 14.5 340 F./16 hrs 19 250 F./3 hrs + 336.5 393.8 17.0
340 F./8 hrs 19 250 F./3 hrs + 326.5 389.0 16.0 340 F./16 hrs 20
250 F./3 hrs + 345.3 399.8 16.0 340 F./8 hrs 20 250 F./3 hrs +
337.0 396.5 13.0 340 F./16 hrs
[0027] As shown, alloys 5-6 and 9-10 with low zinc (alloys 5-6) or
low magnesium (9-10) have low strength, not achieving a tensile
yield strength (TYS) of at least 320 MPa in combination with an
elongation of at least 12%.
[0028] Rotating beam fatigue testing in accordance with ISO 1143
was also conducted on alloy plates 1, 13, 16 and 20, the results of
which are shown in Table 3, below. The stress level for the test
was 15 ksi, with R=-1 and with the RPM being 10,000. Three test
specimens per alloy were used, and the number of cycles to failure
was measured for each specimen. The test run-out was 10,000,000
cycles.
TABLE-US-00003 TABLE 3 Measured Fatigue Life of Alloys 1, 13, 16
and 20 Alloy Artificial Aging Cycles to Failure** # Practice
Specimen 1 Specimen 2 Specimen 3 1 250 F./3 hrs + 10,000,000
10,000,000 10,000,000 340 F./8 hrs 13 250 F./3 hrs + 10,000,000
1,174,446 10,000,000 340 F./8 hrs 16 250 F./3 hrs + 10,000,000
10,000,000 10,000,000 340 F./8 hrs 20 250 F./3 hrs + 2,281,864
2,664,481 1,562,425 340 F./8 hrs
[0029] As shown, alloy 20 with no zirconium realizes worse fatigue
properties relative to alloys 1, 13 and 16.
Example 2
[0030] Three 7xxx aluminum alloys having the compositions shown in
Table 4, below, were cast as industrial-scale billet. From these
billets, 3''.times.7.75''.times.7.75'' samples were obtained from
D/2 by machining. The samples were then hot rolled to a final gauge
of about 1.0 inch (2.54 cm). The hot rolled plates were then
solution heat treated, and then either cold water (CW) or boiling
water (BW) quenched, and then allowed to naturally age for about
24-hours. Cold water quenched means the use of ambient temperature
water. Boiling-water quench means the use of boiling water. After
natural aging, the plates were then two-step artificially aged with
a first step of 250.degree. F. for 3 hours (with a 2-hour heat up
from ambient to 250.degree. F.) and a second step of 340.degree. F.
for 8 hours. The longitudinal (L) mechanical properties of the
plates were then measured at T/2 and in accordance with ASTM B557
and E8, the results of which are shown in Table 5, below (average
of duplicate specimens). SCC results were also measured in
accordance with ASTM G103-97(2011), the "Standard Practice for
Evaluating Stress-Corrosion Cracking Resistance of Low Copper 7XXX
Series Al--Zn--Mg--Cu Alloys in Boiling 6% Sodium Chloride
Solution," at 25 ksi and 35 ksi stress levels, the results of which
are shown in Table 6, below.
TABLE-US-00004 TABLE 4 Composition of the Example 2 Alloys (all
values in weight percent)* Alloy # Si Fe Zn Mg Cu V Zr A 0.062
0.065 4.38 1.54 0.63 0.06 0.08 B 0.078 0.061 4.60 1.72 0.61 0.01
0.11 C 0.060 0.068 4.43 1.71 0.89 0.01 0.10 *The balance of the
alloys was Ti, Al and impurities; all alloys contained 0.02-0.03
wt. % Ti; all alloys contained .ltoreq.0.03 wt. % of any one
impurity and .ltoreq.0.10 wt. % in total of all impurities;
impurities included Mn and Cr in this example.
TABLE-US-00005 TABLE 5 Measured Mechanical Properties of the
Example 2 Alloys Alloy TYS UTS Elong. # Quench (MPa) (MPa) (% A CW
362.8 417.5 17.0 A BW 370.5 423.0 16.5 B CW 391.0 441.8 16.0 B BW
400.8 448.3 15.8 C CW 390.5 446.0 16.0 C BW 401.3 450.5 16.3
TABLE-US-00006 TABLE 6 SCC Properties of the Example 2 Alloys Alloy
Stress (ST) Days to Failure # (ksi) Quench Specimen 1 Specimen 2
Specimen 3 A 25 CW 2.12 OK7 OK7 35 6.06 3.01 2.12 A 25 BW OK7 OK7
OK7 35 OK7 OK7 OK7 B 25 CW 0.65 1.07 0.65 35 0.65 0.65 0.65 B 25 BW
5.08 OK7 OK7 35 0.65 1.7 1.07 C 25 CW OK7 OK7 7.0 35 3.01 0.65 2.12
C 25 BW 3.01 OK7 5.08 35 2.67 2.12 OK7 OK7 = Passed the SCC test
for the full 7 days 7.0 = failed on the 7.sup.th day
[0031] As shown, Alloy A realizes a superior combination of
strength, elongation and SCC resistance properties. As shown, Alloy
A is generally quench insensitive, realizing about 8 ksi higher
tensile yield strength when boiling water quenched.
[0032] 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.
* * * * *