U.S. patent application number 13/033381 was filed with the patent office on 2011-09-29 for aluminum alloy.
This patent application is currently assigned to MAZDA MOTOR CORPORATION. Invention is credited to Takahiro KIMURA, Nobuyuki ODA, Yukihiro SUGIMOTO.
Application Number | 20110236253 13/033381 |
Document ID | / |
Family ID | 44586227 |
Filed Date | 2011-09-29 |
United States Patent
Application |
20110236253 |
Kind Code |
A1 |
KIMURA; Takahiro ; et
al. |
September 29, 2011 |
ALUMINUM ALLOY
Abstract
The present disclosure relates to aluminum alloy including about
1.4% by mass to about 1.6% by mass Mn; about 0.75% by mass to about
2.1% by mass Cu; about 0.4% by mass to about 0.7% by mass Fe; about
0.2% by mass to about 0.5% by mass Mg; about 0.1% by mass to about
0.2% by mass Ti; about 0.03% by mass to about 0.07% by mass Si; and
the balance aluminum and incidental impurities. In the aluminum
alloy, Al--Mg--Cu compounds are dispersed in a matrix.
Inventors: |
KIMURA; Takahiro;
(Hiroshima-shi, JP) ; ODA; Nobuyuki;
(Hiroshima-shi, JP) ; SUGIMOTO; Yukihiro;
(Higashi-Hiroshima-shi, JP) |
Assignee: |
MAZDA MOTOR CORPORATION
Hiroshima
JP
|
Family ID: |
44586227 |
Appl. No.: |
13/033381 |
Filed: |
February 23, 2011 |
Current U.S.
Class: |
420/535 |
Current CPC
Class: |
C22C 21/16 20130101;
C22C 1/06 20130101; C22C 1/00 20130101; C22C 21/12 20130101 |
Class at
Publication: |
420/535 |
International
Class: |
C22C 21/16 20060101
C22C021/16 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 29, 2010 |
JP |
2010-074228 |
Claims
1. Aluminum alloy, comprising: about 1.4% by mass to about 1.6% by
mass Mn; about 0.75% by mass to about 2.1% by mass Cu; about 0.4%
by mass to about 0.7% by mass Fe; about 0.2% by mass to about 0.5%
by mass Mg; about 0.1% by mass to about 0.2% by mass Ti; about
0.03% by mass to about 0.07% by mass Si; and the balance aluminum
and incidental impurities, wherein Al--Mg--Cu compounds are
dispersed in a matrix.
2. The aluminum alloy of claim 1, further comprising: about 1.0% by
mass to about 2.1% by mass Cu.
3. The aluminum alloy of claim 1, wherein a secondary phase is
dispersed in the matrix; and Al--Fe--Mn compounds are dispersed in
the secondary phase.
4. The aluminum alloy of claim 2, wherein a secondary phase is
dispersed in the matrix; and Al--Fe--Mn compounds are dispersed in
the secondary phase.
5. The aluminum alloy of claim 1, wherein the aluminum alloy is
casting aluminum alloy.
6. The aluminum alloy of claim 2, wherein the aluminum alloy is
casting aluminum alloy.
7. The aluminum alloy of claim 3, wherein the aluminum alloy is
casting aluminum alloy.
8. The aluminum alloy of claim 4, wherein the aluminum alloy is
casting aluminum alloy.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to Japanese Patent
Application No. 2010-074228 filed on Mar. 29, 2010, the disclosure
of which including the specification, the drawings, and the claims
is hereby incorporated by reference in its entirety.
BACKGROUND
[0002] The present disclosure relates to aluminum alloy, and
particularly relates to aluminum alloy which can be preferably used
for, e.g., automobile body components, and which has high tensile
strength, high 0.2% proof stress, and high elongation.
[0003] Conventionally, aluminum alloy has been used in, e.g.,
cylinder heads and cylinder blocks of engines, and gearbox casings
for automobiles. Aluminum alloy having various compositions has
been proposed in order to improve mechanical properties such as
hardness and strength and chemical properties such as a heat
resisting property while taking advantage of excellent properties
of aluminum, such as a property in which aluminum is light-weight
with good workability.
[0004] Meanwhile, an approach for realizing improvement of fuel
efficiency of vehicles is recently being introduced more than ever.
Specifically, technology for using light-weight aluminum alloy in
panel components such as roof panels, door panels, and bonnets is
being developed. In addition, it has been known that an extruded
product made of aluminum alloy is used in frame components such as
bumper reinforcements and crash cans, for which energy absorbency
is required.
[0005] When using aluminum alloy for the vehicle body components,
an extruded product or a plate-like member which has high ductility
as compared to castings is often used for components for which high
tensile strength and high elongation are required. However, a cost
of the extruded product or the plate-like member is high, and,
e.g., secondary processing and joining are often required. Thus,
the use of the extruded product or the plate-like member tends to
increase an overall cost. For the foregoing reason, it is required
that a component having higher tensile strength and higher
elongation is manufactured by a casting method by which a plurality
of components can be integrally formed at low cost.
[0006] For example, Japanese Patent Publication No. H09-268340
discloses high-ductility aluminum alloy containing Mn of about
0.5-2.5 percent by mass (% by mass); Fe of about 0.1-1.5% by mass;
Mg of about 0.01-1.2% by mass; and the balance aluminum and
incidental impurities. According to the high-ductility aluminum
alloy, in so-called "Al-1.5% Mn alloy," high tensile strength is
ensured while improving both of castability and elongation.
SUMMARY
[0007] However, as described in a first example of Japanese Patent
Publication No. H09-268340, there is aluminum alloy having low
tensile strength (162 (MPa)), and therefore there is a problem in
which it is difficult to stably manufacture castings made of
aluminum alloy having high tensile strength and high elongation. In
order to use such castings having the insufficient tensile strength
for vehicle body components, an additional reinforcement member is
required, and therefore there is a possibility that the number of
manufacturing processes and cost are increased.
[0008] The present disclosure has been made in view of the
foregoing, and it is an object of the present disclosure to provide
a technique for manufacturing aluminum alloy which can be
preferably used for, e.g., complex vehicle body components, and
which has high tensile strength, high 0.2% proof stress, and high
elongation.
[0009] In order to solve the foregoing problem, the inventors of
the present disclosure have conducted various studies and
experiments, and the results show the following finding (a):
[0010] (a) So-called "Al-1.5% Mn alloy" contains Cu, and a Cu
content is properly adjusted (specifically, the Cu content is
adjusted to a range of greater than or equal to about 0.75% by mass
and less than or equal to about 2.1% by mass). Thus, Al--Mg--Cu
compounds having higher strength can be dispersed in a matrix
(primary alpha phase). Consequently, the Al--Mg--Cu compound can
improve tensile strength, 0.2% proof stress, and elongation of the
Al-1.5% Mn alloy as compared to those of conventional alloy.
[0011] Further, in order to ensure ductility of the Al-1.5% Mn
alloy, the inventors have studied Al--Fe--Mn compounds which
improve the ductility by forming a preferable distribution state of
a precipitated phase during casting, and which significantly
degrade the ductility if such compounds are formed as coarse
crystals. The results show the following finding (b):
[0012] (b) The Al-1.5% Mn alloy contains Cu, and a Cu content is
properly adjusted. Thus, a secondary phase can be dispersed in
clumps in a matrix (primary alpha phase), and the Al--Fe--Mn
compounds can be dispersed in the secondary phase in a state in
which the Al--Fe--Mn compounds are mixed with Al--Fe--Mn--Cu
compounds. In the following description, the primary alpha phase
may be simply referred to as a "matrix."
[0013] The aluminum alloy of the present disclosure has been made
based on the foregoing findings.
[0014] The present disclosure is intended for aluminum alloy of the
following (1)-(4):
[0015] (1) aluminum alloy including about 1.4% by mass to about
1.6% by mass Mn, about 0.75% by mass to about 2.1% by mass Cu,
about 0.4% by mass to about 0.7% by mass Fe, about 0.2% by mass to
about 0.5% by mass Mg, about 0.1% by mass to about 0.2% by mass Ti,
about 0.03% by mass to about 0.07% by mass Si, and the balance
aluminum and incidental impurities; in which Al--Mg--Cu compounds
are dispersed in a matrix;
[0016] (2) the aluminum alloy of (1), including about 1.0% by mass
to about 2.1% by mass Cu;
[0017] (3) the aluminum alloy of (1) or (2), in which a secondary
phase is dispersed in the matrix; and Al--Fe--Mn compounds are
dispersed in the secondary phase; and
[0018] (4) the aluminum alloy of any one of (1)-(3), which is
casting aluminum alloy.
[0019] Note that the "matrix (primary alpha phase)" in the present
disclosure means a structural phase having the maximum area ratio
in a crystal structural phase forming a metal structure containing
aluminum as a base. In addition, the "secondary phase" means a
crystal structural phase having the maximum area ratio in the
remaining phase (various precipitated phases) other than the matrix
(primary alpha phase).
[0020] According to the aluminum alloy of the present disclosure,
in the Al-1.5% Mn alloy, the Cu content is adjusted to the range of
greater than or equal to about 0.75% by mass and less than or equal
to about 2.1% by mass. Thus, the Al--Mg--Cu compounds are dispersed
in the matrix, and therefore mechanical properties of the Al-1.5%
Mn alloy can be stably improved as compared to those of the
conventional alloy. This allows manufacturing of aluminum alloy
which can be preferably used for, e.g., complex vehicle body
components, and which has high tensile strength, high 0.2% proof
stress, and high elongation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a graph illustrating a relationship of alloy types
with tensile strength, 0.2% proof stress, and elongation.
[0022] FIG. 2 is an EPMA compound mapping picture showing an
internal state of a test piece used for a test number 4 of examples
of the present disclosure.
[0023] FIG. 3 is an enlarged optical micrograph showing a matrix of
the test piece used for the test number 4 of the examples of the
present disclosure.
[0024] FIG. 4 is an enlarged optical micrograph showing a matrix of
a test piece used for a test number 7 of comparative examples.
[0025] FIG. 5 is an enlarged optical micrograph showing a matrix of
a test piece used for a test number 8 of the comparative
examples.
[0026] FIG. 6A is a side view of a product manufactured by casting
aluminum alloy into a mold of JIS H5202.
[0027] FIG. 6B is an end view of the product manufacture by casting
aluminum alloy into the mold of JIS H5202.
DETAILED DESCRIPTION
[0028] As described above, aluminum alloy of the present disclosure
includes about 1.4% by mass to about 1.6% by mass Mn; about 0.75%
by mass to about 2.1% by mass Cu; about 0.4% by mass to about 0.7%
by mass Fe; about 0.2% by mass to about 0.5% by mass Mg; about 0.1%
by mass to about 0.2% by mass Ti; about 0.03% by mass to about
0.07% by mass Si; and the balance aluminum and incidental
impurities. In the aluminum alloy of the present disclosure,
Al--Mg--Cu compounds are dispersed in a matrix (primary alpha
phase). Reasons why the present disclosure is specified as
described above, and preferable ranges will be described below. In
the description below, unless otherwise noted, "%" representing a
content of a chemical composition means a "% by mass."
[0029] (1) Chemical Compositions
[0030] Mn (Manganese): about 1.4% to about 1.6% (Greater than or
Equal to about 1.4% and Less than or Equal to about 1.6%)
[0031] Mn is an element contributing to reduction or prevention of
sticking of molten metal to a mold. In addition, Mn forms an
Al--Fe--Mn compound, and improves ductility depending on a fair
distribution of the Al--Fe--Mn compounds. In order to ensure such
advantages, it is required that the aluminum alloy of the present
disclosure contains Mn of greater than or equal to about 1.4%.
However, if a Mn content exceeds 1.6%, coarse crystals are
generated during casting, thereby reducing elongation. Thus, the Mn
content is within the range of greater than or equal to about 1.4%
and less than or equal to about 1.6%.
[0032] Cu (Copper): about 0.75% to about 2.1% (Greater than or
Equal to about 0.75% and Less than or Equal to about 2.1%)
[0033] Cu is an essential element for improving tensile strength,
0.2% proof stress, and the elongation of the aluminum alloy of the
present disclosure. In order to achieve such an advantage, it is
required that the aluminum alloy of the present disclosure contains
Cu of greater than or equal to about 0.75%. If the aluminum alloy
of the present disclosure contains Cu of greater than or equal to
about 1.0%, a further enhanced advantage can be achieved. However,
if the aluminum alloy of the present disclosure contains Cu
exceeding about 2.1%, the ductility is reduced. Thus, a Cu content
is within the range of greater than or equal to about 0.75% and
less than or equal to about 2.1%. More preferably, the Cu content
is within a range of greater than or equal to about 1.0% and less
than or equal to about 2.1%.
[0034] Fe (Iron): about 0.4% to about 0.7% (Greater than or Equal
to about 0.4% and Less than or Equal to about 0.7%)
[0035] Fe has an advantage that the sticking of molten metal to the
mold is reduced or prevented when casting. If an Fe content is
below about 0.4%, the sticking to the mold is easily caused;
whereas, if the Fe content is above 0.7%, coarse crystals are
easily generated as in Mn, and the elongation is reduced as
compared to conventional alloy. Thus, the Fe content is within the
range of greater than or equal to about 0.4% and less than or equal
to about 0.7%.
[0036] Mg (Magnesium): about 0.2% to about 0.5% (Greater than or
Equal to about 0.2% and Less than or Equal to about 0.5%)
[0037] Mg coexists with Si, and is precipitated as Mg.sub.2Si by
thermal processing. Thus, mechanical strength such as the tensile
strength and the proof stress are improved. However, if a Mg
content is below about 0.2%, it is less likely to achieve such an
advantage; whereas, if the Mg content exceeds about 0.5%, the
ductility is reduced. Thus, the Mg content is within the range of
greater than or equal to about 0.2% and less than or equal to about
0.5%.
[0038] Ti (Titanium): about 0.1% to about 0.2% (Greater than or
Equal to about 0.1% and Less than or Equal to about 0.2%)
[0039] Ti refines the grain size of cast metal, thereby improving
cast metal properties, and reducing or preventing hot tearing.
However, if a Ti content is below about 0.1%, it is less likely to
achieve such an advantage, and therefore it is difficult to
substantially reduce or prevent the hot tearing. On the other hand,
if the Ti content is above about 0.2%, coarse compounds are
generated, thereby reducing the elongation and molten metal
fluidity. Thus, the Ti content is within the range of greater than
or equal to about 0.1% and less than or equal to about 0.2%.
[0040] Si (Silicon): about 0.03% to about 0.07% (Greater than or
Equal to about 0.03% and Less than or Equal to about 0.07%)
[0041] Si acts to increase the strength, but it is less likely to
achieve such an advantage if a Si content is less than about 0.03%.
On the other hand, if the Si content exceeds about 0.07%, Si and Fe
together form kinds of intermetallic compounds, i.e., Al--Fe--Si
compounds, thereby degrading the ductility. Thus, the lower limit
of the Si content is about 0.03%, and the upper limit of the Si
content is about 0.07%.
[0042] Al (Aluminum) is an element contributing to a reduction in
weight of, e.g., automobile components, and therefore Al, the
impurities, and other required alloy elements together form the
remaining portion.
[0043] (2) Al--Mg--Cu Compound
[0044] The Al--Mg--Cu compound acts to increase the strength. Thus,
the aluminum alloy of the present disclosure contains Cu of greater
than or equal to about 0.75%, and therefore the Al--Mg--Cu
compounds are actively generated and dispersed in the matrix
(primary alpha phase). However, addition of a large amount of Cu
may result in reduction in hot tearing. Thus, the Cu content is
limited as described above.
[0045] (3) Al--Fe--Mn Compound
[0046] By controlling the size of the Al--Fe--Mn compound to about
6-15 .mu.m, the Al--Fe--Mn compound improves the ductility.
However, if the coarse Al--Fe--Mn compounds having a size of
greater than or equal to about 50 .mu.m are formed, the ductility
is significantly degraded. In particular, if the total content of
Mn and Fe exceeds about 1.3%, the coarse crystals are formed during
casting, thereby reducing the ductility. Thus, in the present
disclosure, the total content of Mn and Fe is adjusted so that the
Al--Fe--Mn compounds are finely dispersed not in the matrix but in
a secondary phase. Further, the Cu content is properly adjusted,
and therefore the Al--Fe--Mn compounds are dispersed in the
secondary phase in a state in which the Al--Fe--Mn compounds are
mixed with Al--Fe--Mn--Cu compounds.
[0047] In the aluminum alloy of the present disclosure, which is
designed as described above, the Cu content is adjusted to the
range of greater than or equal to about 0.75% by mass and less than
or equal to about 2.1% by mass. Thus, the cast metal having the
high tensile strength, the high 0.2% proof stress, and the high
elongation can be manufactured by a known casting method such as
gravity casting, low-pressure die casting, high-pressure die
casting, and squeeze casting.
[0048] The present disclosure will be described below in detail
with reference to examples, but is not limited to such
examples.
EXAMPLES
[0049] Various aluminum alloys 1-8 having chemical compositions
shown in Table 1 were molten by an electric furnace, and then each
aluminum alloy was casted into a mold according to the Japanese
Industrial Standard (JIS) H5202 at a molten metal temperature of
740.degree. C. and a mold temperature of 200.degree. C. by a
typical mold gravity casting (see FIGS. 6A and 6B).
[0050] A tensile test piece according to JIS 14A was cut out from
the center of a casted product 1 obtained by the foregoing
technique. Then, a tensile test was implemented at a testing rate
of 3 mm/min and a room temperature by using an Autograph
manufactured by Shimadzu Corporation, and mechanical properties
such as tensile strength (MPa), 0.2% proof stress (MPa), and
elongation (%) were measured. The results are shown in Table 2 and
FIG. 1. The alloys 1-5 in Table 1 are aluminum alloys having
chemical compositions falling within the ranges specified in the
present disclosure. On the other hand, the alloys 6-8 are aluminum
alloys having chemical compositions which do not satisfy the
conditions specified in the present disclosure.
TABLE-US-00001 TABLE 1 Chemical Composition (% by mass) Alloy
Balance Aluminum and Impurities Class Number Mn Si Mg Cu Fe Ti
Examples of 1 1.43 0.05 0.24 0.75 0.56 0.15 the Present 2 1.42 0.05
0.24 1.00 0.56 0.15 Disclosure 3 1.41 0.05 0.24 1.26 0.57 0.15 4
1.41 0.05 0.24 1.70 0.55 0.15 5 1.41 0.05 0.24 2.10 0.55 0.15
Comparative 6 1.60 0.05 0.24 *0.00 0.60 0.20 Examples 7 1.45 0.05
0.24 *0.42 0.56 0.15 8 1.40 0.05 0.24 *2.50 0.55 0.15 *A Cu content
does not satisfy the conditions specified in the present
disclosure.
TABLE-US-00002 TABLE 2 0.2% Tensile Proof Test Alloy Strength
Stress Elongation Class Number Number (MPa) (MPa) (%) Examples of 1
1 182 90 11.0 the Present 2 2 201 100 12.0 Disclosure 3 3 213 115
12.7 4 4 209 112 14.3 5 5 199 114 10.5 Comparative 6 *6 123 73 11.0
Examples 7 *7 150 85 7.0 8 *8 240 207 6.3 *Alloy does not satisfy
conditions specified in the present disclosure.
[0051] As will be seen from Table 2, in any of the test numbers 1-5
of the examples of the present disclosure, which use the alloys 1-5
satisfying the conditions specified in the present disclosure, it
has been confirmed that the tensile strength is greater than or
equal to about 182 (MPa), the 0.2% proof stress is greater than or
equal to about 90 (MPa), and the elongation is greater than or
equal to about 10.5(%); and therefore the alloys 1-5 have the high
mechanical properties. Thus, the tests provide a supportive
evidence showing that the aluminum alloy of the present disclosure
has sufficient capability of achieving at least the three
mechanical properties in practical use.
[0052] When observing the alloy 4 used for the test number 4 of the
examples of the present disclosure by an EPMA (electron probe
microanalyzer) analysis, it has been confirmed that, as illustrated
in FIG. 2, a secondary phase is dispersed so as to form in clumps
in a matrix, and Al--Fe--Mn compounds and Al--Fe--Mn--Cu compounds
are dispersed in the secondary phase in a state in which the
Al--Fe--Mn compounds and the Al--Fe--Mn--Cu compounds are mixed
with each other. Further, as illustrated in FIG. 3, it has been
clearly confirmed that the Al--Mg--Cu compounds are dispersed in
the matrix.
[0053] On the other hand, in the test numbers 6-8 of the
comparative examples using the alloys 6-8 having the Cu content
which does not satisfy the conditions specified in the present
disclosure, it has been confirmed that, in any of the alloys having
the Cu content less than the Cu content specified in the present
disclosure (test numbers 6 and 7), and the alloy having the Cu
content greater than the Cu content specified in the present
disclosure (test number 8), at least one of the mechanical
properties, i.e., the tensile strength, the 0.2% proof stress, and
the elongation is significantly degraded as compared to those of
the examples of the present disclosure.
[0054] Specifically, it has been confirmed that, in the test number
6 of the comparative example using the alloy 6 which does not
contain Cu, the alloy has the elongation equal or approximately
equal to those of the examples of the present disclosure, but the
tensile strength and the 0.2% proof stress are significantly
degraded as compared to those of the examples of the present
disclosure. In addition, it has been confirmed that, in the test
number 7 of the comparative example using the alloy 7 having the Cu
content less than the Cu content specified in the present
disclosure, all of the tensile strength, the 0.2% proof stress, and
the elongation are degraded as compared to those of the examples of
the present disclosure.
[0055] Further, it has been confirmed that, in the test number 8 of
the comparative example using the alloy 8 having the Cu content
exceeding the Cu content specified in the present disclosure, the
tensile strength and the 0.2% proof stress are improved as compared
to those of the examples of the present disclosure, but the
elongation is significantly degraded as compared to those of the
examples of the present disclosure (less than 50% of the values of
the test numbers 3 and 4 of the examples of the present
disclosure).
[0056] When observing the alloy 7 used for the test number 7 of the
comparative example by the optical microscope as in the examples of
the present disclosure, it has been confirmed that the Al--Mg--Cu
compounds are not dispersed in the matrix as illustrated in the
enlarged view of FIG. 4.
[0057] In addition, when observing the alloy 8 used for the test
number 8 of the comparative example by the EPMA analysis as in the
examples of the present disclosure, it has been confirmed that, as
illustrated in the enlarged view of FIG. 5, the Al--Mg--Cu
compounds are not dispersed in the matrix, and coarse spherical Cu
containing compounds which are different from the Al--Mg--Cu
compound are dispersed. Such spherical Cu containing compounds are
not dispersed in the alloy 7, and therefore significantly degrade
the elongation (ductility) in the test number 8 of the comparative
example. When observing the alloy 6 used for the test number 6 of
the comparative example by the optical microscope, it has been
confirmed that the Al--Mg--Cu compounds form a most part of the
secondary phase.
[0058] As described above, even if Al-1.5% Mn alloy is used, which
is the same as the alloy of the present disclosure except for the
Cu content, the alloys of the comparative examples, the Cu content
of which does not satisfy the conditions specified in the present
disclosure cannot be used due to problems of reliability relating
to, e.g., durability.
[0059] As illustrated in FIG. 1, the mechanical properties (in
particular, the tensile strength and the elongation) are
significantly improved within the Cu content range of greater than
or equal to about 0.75% and less than or equal to about 2.1%, and
the elongation is significantly improved within the Cu content
range of greater than or equal to about 1.0% and less than or equal
to about 2.1%. This shows technical values of the claimed ranges of
the present disclosure.
[0060] As described above, the present disclosure is useful for,
e.g., aluminum alloy used for vehicle body and chassis components
such as suspension members, pillars, joint members, suspension
towers, and crush cans.
* * * * *