U.S. patent application number 12/848859 was filed with the patent office on 2010-11-25 for aluminum alloy for casting having high rigidity and low linear expansion coefficient.
This patent application is currently assigned to NIPPON LIGHT METAL COMPANY, LTD.. Invention is credited to Kazuhiro ODA, Masahiko Shioda.
Application Number | 20100296964 12/848859 |
Document ID | / |
Family ID | 34994430 |
Filed Date | 2010-11-25 |
United States Patent
Application |
20100296964 |
Kind Code |
A1 |
ODA; Kazuhiro ; et
al. |
November 25, 2010 |
ALUMINUM ALLOY FOR CASTING HAVING HIGH RIGIDITY AND LOW LINEAR
EXPANSION COEFFICIENT
Abstract
[Objectives] An aluminum alloy for casting with excellent
rigidity and having a low coefficient of linear expansion, and at
the same time, does not have a high cost, and has a few
restrictions at the time of recycling. [Means for Achieving
Objectives] An aluminum alloy for casting with excellent rigidity
and having a low coefficient of linear expansion containing 13-25%
by mass of silicon, 2-8% by mass of copper, 0.5-3% by mass of iron,
0.3-3% by mass of manganese, 0.001-0.02% by mass of phosphorus, and
the remainder comprising aluminum and inevitable impurities,
wherein the total amount of iron and manganese is 3.0% by mass or
greater. Said alloy may further contain 0.5-6% by mass of nickel,
and the total amount of iron, manganese, and nickel may be 3.0% by
mass or greater. Further, said alloy may further contain one or
more of 0.1-1.0% by mass of chromium, 0.05-1.5% by mass of
magnesium, 0.01-1.0% by mass of titanium, 0.0001-1.0% by mass of
boron, 0.1-1.0% by mass of zirconium, 0.1-1.0% by mass of vanadium,
or 0.01-1.0% by mass of molybdenum.
Inventors: |
ODA; Kazuhiro; (Ihara-gun,
JP) ; Shioda; Masahiko; (Shinagawa-ku, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, L.L.P.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
NIPPON LIGHT METAL COMPANY,
LTD.
Shinagawa-ku
JP
|
Family ID: |
34994430 |
Appl. No.: |
12/848859 |
Filed: |
August 2, 2010 |
Current U.S.
Class: |
420/535 ;
420/534; 420/537 |
Current CPC
Class: |
C22C 21/02 20130101;
B22D 11/0605 20130101; C22F 1/05 20130101; B22D 11/124
20130101 |
Class at
Publication: |
420/535 ;
420/534; 420/537 |
International
Class: |
C22C 21/02 20060101
C22C021/02; C22C 21/08 20060101 C22C021/08; C22C 21/16 20060101
C22C021/16; C22C 21/14 20060101 C22C021/14 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 23, 2004 |
JP |
2004-084256 |
Claims
1. An aluminum alloy consisting of 13-25% by mass of silicon, 2-8%
by mass of copper, 0.5-3% by mass of iron, 0.3-3.5% by mass of
manganese, 0.001-0.02% by mass of phosphorus, and one or more of
0.1-1.0% by mass of Cr or 0.05-1.5% by mass of Mg, and the
remainder, which consists of aluminum and inevitable impurities,
wherein the total amount of iron and manganese is 3.0% by mass or
greater, said aluminum alloy having a Young's modulus of 90 GPa or
more and a coefficient of linear thermal expansion of
18.times.10.sup.-6/.degree. C. or less.
2. An aluminum alloy consisting of 13-25% by mass of silicon, 2-8%
by mass of copper, 0.5-3% by mass of iron, 0.3-3.5% by mass of
manganese, 0.001-0.02% by mass of phosphorus, and one or more of
0.01-1.0% by mass of titanium, 0.0001-1.0% by mass of boron,
0.1-1.0% by mass of zirconium, 0.1-1.0 by mass of vanadium, and
0.01-1.0% by mass of molybdenum, and the remainder, which consists
of aluminum and inevitable impurities, wherein the total amount of
iron and manganese is 3.0% by mass or greater, said aluminum alloy
having a Young's modulus of 90 GPa or more and a coefficient of
linear thermal expansion of 18.times.10.sup.-6/.degree. C. or
less.
3. An aluminum alloy consisting of 13-25% by mass of silicon, 2-8%
by mass of copper, 0.5-3% by mass of iron, 0.3-3.5% by mass of
manganese, 0.5-6% by mass of nickel, 0.001-0.02% by mass of
phosphorus, and one or more of 0.1-1.0% by mass of Cr or 0.05-1.5%
by mass of Mg, and the remainder, which consists of aluminum and
inevitable impurities, wherein the total amount of iron and
manganese is 3.0% by mass or greater, said aluminum alloy having a
Young's modulus of 90 GPa or more and a coefficient of linear
thermal expansion of 18.times.10.sup.-6/ .degree. C. or less.
4. An aluminum alloy consisting of 13.sup.-25% by mass of silicon,
2-8% by mass of copper, 0.5-3% by mass of iron, 0.3-3.5% by mass of
manganese, 0.5-6% by mass of nickel, 0.001-0.02% by mass of
phosphorus, and one or more of 0.01-1.0% by mass of titanium,
0.0001-1.0% by mass of boron, 0.1-1.0% by mass of zirconium,
0.1-1.0 by mass of vanadium, and 0.01-1.0% by mass of molybdenum,
and the remainder, which consists of aluminum and inevitable
impurities, wherein the total amount of iron and manganese is 3.0%
by mass or greater, said aluminum alloy having a Young's modulus of
90 GPa or more and a coefficient of linear thermal expansion of
18.times.10.sup.-6/.degree. C. or less.
5. The aluminum alloy according to claim 1, wherein the amount of
manganese is 1-3% by mass.
6. The aluminum alloy according to claim 2, wherein the amount of
manganese is 1-3% by mass.
7. The aluminum alloy according to claim 3, wherein the amount of
manganese is 1-3% by mass.
8. The aluminum alloy according to claim 4, wherein the amount of
manganese is 1-3% by mass.
9. The aluminum alloy according to claim 3, wherein the total
amount of iron, manganese and nickel is 3.0% by mass or
greater.
10. The aluminum alloy according to claim 4, wherein the total
amount of iron, manganese and nickel is 3.0% by mass or
greater.
11. The aluminum alloy according to claim 3, wherein the amount of
nickel is 1-6% by mass.
12. The aluminum alloy according to claim 4, wherein the amount of
nickel is 1-6% by mass.
13. The aluminum alloy according to claim 3, wherein the amount of
nickel is 1-3% by mass.
14. The aluminum alloy according to claim 4, wherein the amount of
nickel is 1-3% by mass.
Description
TECHNICAL FIELD
[0001] The present invention concerns an aluminum alloy for
casting, and particularly concerns an aluminum alloy for casting
that may be used optimally for the casting of members for which
high rigidity and a low linear thermal expansion coefficient are
particularly required, such as ladder frames, perimeter frames, and
cases for various types of vehicles such as automobiles.
BACKGROUND ART
[0002] Conventionally, cast iron was used for members such as
automobile frames that require particularly high rigidity, but in
recent years, from the standpoint of energy conservation, the need
for weight reduction of automobiles has increased, and attention
has been paid to aluminum alloy as a material that can meet these
needs.
DISCLOSURE OF THE INVENTION
Problem to be Solved by the Invention
[0003] As aluminum alloys having high rigidity, aluminum alloy
composites compounding Al.sub.2O.sub.3, SiC, and the like as
reinforcing materials are known, but these composites have the
problem that the manufacturing processes thereof are complex and
the cost becomes high. Additionally, there are problems such as the
fact that since Al.sub.2O.sub.3, SiC, and the like are contained,
there are many restrictions at the time of recycling.
[0004] Japanese Unexamined Patent Publication No. H01-180938
discloses an aluminum alloy with improved wear resistance, but the
aluminum alloy disclosed therein has the problem that when
substituted for cast iron products being used for automobile frames
and the like, its rigidity is low, and its linear expansion
coefficient is too high. Additionally, Japanese Unexamined Patent
Publication No. H03-199336 also similarly discloses an aluminum
alloy with improved wear resistance, but the aluminum alloy
disclosed therein also has the problem that when substituted for
cast iron products being used for automobile frames and the like,
its rigidity is low, and its linear expansion coefficient is too
high, and further, sticking to the die occurs easily.
[0005] [Patent Document 1] Japanese Unexamined Patent Publication
No. H01-180938
[0006] [Patent Document 2] Japanese Unexamined Patent Publication
No. H03-199336
Means for Solving the Problem
[0007] In order to solve the abovementioned problems of
conventional aluminum alloys, the present invention offers an
aluminum alloy for casting having excellent rigidity and a low
linear expansion coefficient, containing 13-25% by mass of silicon,
2-8% by mass of copper, 0.5-3% by mass of iron, 0.3-3% by mass of
manganese, 0.001-0.02% by mass of phosphorus, and the remainder
comprising aluminum and inevitable impurities, wherein the total
amount of iron and manganese is 3.0% by mass or greater.
[0008] Further, 0.5-6% by mass of nickel may be added to make the
total amount of iron, manganese, and nickel 3.0% by mass or
greater.
[0009] Further, in place of the abovementioned nickel, or in
addition to the nickel, one or more of 0.1-1.0% by mass of
chromium, 0.05-1.5% by mass of magnesium, 0.01-1.0% by mass of
titanium, 0.0001-1.0% by mass of boron, 0.1-1.0% by mass of
zirconium, 0.1-1.0% by mass of vanadium, or 0.01-1.0% by mass of
molybdenum may be contained.
[0010] It is desirable for the alloy of the present invention to be
cast at a cooling rate of 30 degrees C. per second or greater, and
in order to cast at a high cooling rate, it is desirable to do the
casting by the die casting method.
[0011] The inventors of the present invention, as a result of keen
research regarding aluminum alloy, discovered that there is a
correlation between the area ratio of crystallized products and the
rigidity and linear expansion coefficient of aluminum alloys, and
as a result of further research, discovered that by the alloy
composition described above, it was possible to disperse minute
crystallized particles of Al--Ni, Nl-Ni--Cu, Al--Cu, Al--Fe--Si,
Al--Fe--Mn, or Al--Si--Mn compounds, and the necessary high
rigidity and low linear expansion coefficient was realizable.
Herebelow, the effects of each component in said aluminum alloy
shall be described.
Effects of the Invention
Silicon: 13-25% by Mass
[0012] Silicon crystallizes as eutectic silicon, primary silicon,
and as Al--Fe--Si compounds, and has the effect of improving
rigidity. This effect becomes marked at greater than 13% by mass,
but at greater than 25% by mass, primary silicon becomes coarse,
and the rigidity improving effect is reduced. Additionally, it is
necessary to improve the casting temperature. Further,
machinability becomes markedly worse due to coarse silicon. Silicon
also has the effects of decreasing the linear expansion
coefficient, and improving wear resistance. A more desirable range
for silicon is 13-17% by mass.
Copper: 2-8% by Mass
[0013] Copper crystallizes as Al--Cu and Al--Ni--Cu compounds, and
contributes to the improvement of rigidity. This effect becomes
marked at 4% by mass or greater, but at greater than 8% by mass,
the compounds become coarse and elongation is reduced, and further,
corrosion resistance is also reduced. A more desirable range for Cu
is 3-6 wt %.
Iron+Manganese (+Nickel): 3.0% by Mass or Greater
[0014] Iron, manganese, and nickel crystallize as Al--Fe--Mn,
Al--Fe--Si, Al--Ni, Al--Ni--Cu, Al--Ni--Fe--Mn, and Al--Si--Fe--Mn
compounds, contribute to the improvement of rigidity, and have the
effect of reducing the linear expansion coefficient. Additionally,
they have the effect of improving heat resistance. This effect
becomes marked when iron+manganese (+nickel) is 3% by mass or
greater, but since at greater than 12% by mass, the crystallized
products become coarse, and the rigidity improving effect is
lessened, it is desirable to keep the total amount of
iron+manganese (+nickel) at 12% by mass or less.
Phosophorus: 0.001-0.02% by Mass
[0015] Phosphorus has the effect of miniaturizing and dispersing
uniformly the primary silicon. This effect is marked at 0.001% by
mass or greater, but at greater than 0.02% by mass, the viscosity
of the molten metal increases, and castability becomes worse.
Magnesium: 0.05-1.5% by Mass
[0016] Mg dissolves in solid solution in the matrix and contributes
to the improvement of rigidity. This effect is marked at 0.05% by
mass or greater, but at greater than 1.5% by mass, elongation is
reduced, and castability markedly worsens. More desirably magnesium
should be 0.4% by mass or less.
Chromium: 0.1-1.0% by Mass
[0017] Chromium crystallizes as Al--Si--Fe--Mn--Cr compounds, and
contributes to the improvement of rigidity. Additionally, it has
the effect of dispersing primary silicon minutely and uniformly.
Said effect is marked for 0.1% by mass or greater of chromium, but
at greater than 1.0% by mass, coarse compounds are formed, and
elongation is reduced.
Titanium: 0.01-1.0% by Mass
[0018] Titanium miniaturizes the alpha phase, and contributes to
the improvement of castability, and also has the effect of
preventing the coarsening of Al--Ni compounds. Such effects become
marked at 0.01% by mass or greater of titanium, but at greater than
1.0% by mass, coarse compounds are formed, and elongation is
reduced.
Boron: 0.0001-1.0% by Mass, Vanadium: 0.1-1.0% by Mass, Zirconium:
0.1-1.0% by Mass, Molybdenum: 0.01-1.0% by Mass
[0019] Boron, vanadium, zirconium, and molybdenum form highly rigid
crystallized products, and contribute to the improvement of
rigidity. For any of these elements, if greater than the upper
limit is added, coarse crystallized products are formed, and
elongation is reduced.
BEST MODES FOR EMBODYING THE INVENTION
[0020] The inventors of the invention of the present application
manufactured the aluminum alloys according to the present
invention, and confirmed experimentally the relationship between
composition and crystalline structure, rigidity and linear
expansion coefficient, and the results shall be described
herebelow.
[0021] The composition of the aluminum alloys used in the
experiment is shown in table 1. The aluminum alloy used in the
experiment, after being cast in a 200.times.200.times.10 mm planar
form at a casting temperature of 720 degrees C., was aged by
maintaining at 200 degrees C. for 4 hours, and then the rigidity
(Young's modulus) and the linear expansion coefficient (thermal
expansion coefficient) were measured. Alloys No. 1-17 are aluminum
alloys according to the present invention, and alloys No. 18-24 are
comparative examples that do not satisfy at least one of the
conditions for the range of the compositions described above.
Compositions that do not satisfy the conditions are shown
underlined.
TABLE-US-00001 TABLE 1 Characteristics Composition (wt %) E .alpha.
No. Si Cu Ni Fe Mn Mg Cr Ti B V Zr Mo P (GPa)
(.times.10.sup.-6/.degree. C.) 1 Compositions 13 5 3 2 1 0.5 0.4
0.4 0.4 0.4 0.4 0.4 0.01 96 17.8 2 According 24 5 3 2 1 0.5 0.4 0.4
0.4 0.4 0.4 0.4 0.01 103 14.6 3 to the 16 3 3 2 1 0.5 0.4 0.4 0.4
0.4 0.4 0.4 0.01 96 17.2 4 Present 16 7 3 2 1 0.5 0.4 0.4 0.4 0.4
0.4 0.4 0.01 100 16.7 5 Invention 16 5 1 1 1 0.5 0.4 0.4 0.4 0.4
0.4 0.4 0.01 93 17.5 6 16 5 3 2 2 0.5 0.4 0.4 0.4 0.4 0.4 0.4 0.01
98 17.0 7 16 5 6 2 3.5 0.5 0.4 0.4 0.4 0.4 0.4 0.4 0.01 106 16.4 8
16 5 1 1 1 1.5 1.0 1.0 1.0 1.0 1.0 1.0 0.01 98 16.9 9 16 5 -- 2 2
-- 0.4 -- -- -- -- -- 0.01 92 17.8 10 16 5 -- 2 2 0.5 0.4 -- -- --
-- -- 0.01 92 17.8 11 16 5 -- 2 2 -- 0.4 -- 0.4 -- -- -- 0.01 94
17.7 12 16 5 -- 2 2 -- 0.4 0.4 -- -- -- -- 0.01 93 17.7 13 16 5 --
2 2 -- 0.4 -- -- 0.4 -- -- 0.01 93 17.7 14 16 5 -- 2 2 -- 0.4 -- --
-- 0.4 -- 0.01 94 17.7 15 16 5 -- 2 2 -- 0.4 -- -- -- -- 0.4 0.01
94 17.7 16 14 4 2 2.5 1.2 -- 0.5 0.5 -- 0.5 -- -- 0.01 94 17.6 17
16 5 -- 2 2 0.5 -- -- -- -- -- -- 0.01 90 17.9 18 Comparative 12 1
1 1 0.5 1 -- -- -- -- -- -- -- 80 20.0 19 Examples 11 2.5 -- 0.8
0.2 0.2 -- -- -- -- -- -- -- 78 21.0 20 16 5 0.5 1 0.5 0.5 0.4 --
-- -- -- -- 0.01 87 17.9 21 16 5 2 -- 2 -- 0.4 -- -- -- -- -- 0.01
91 17.8 22 16 5 2 2 -- -- 0.4 -- -- -- -- -- 0.01 -- 17.4 23 16 1
-- 2 2 -- 0.4 -- -- -- -- -- 0.01 86 18.5 24 12 5 -- 2 2 -- 0.4 --
-- -- -- -- 0.01 88 18.9
[0022] The abovementioned measurement results are shown in Table 1
along with compositions.
[0023] Here, regarding Young's modulus, the criterial value is
taken to be 90 GPa, and any composition with a value above this is
judged to satisfy the criterion, and regarding the coefficient of
linear thermal expansion, the criterial value is taken to be
18.times.10.sup.-6/.degree. C., and any composition with a value
lower than this is judged to satisfy the criterion.
[0024] As shown in table 1, Alloy No. 18 has a Young's modulus of
80 GPa so has a lower value than the criterial value (90 GPa), and
at the same time, its coefficient of linear thermal expansion is
20.0.times.10.sup.-6/.degree. C., higher than the criterial value
(18.times.10.sup.-6/.degree. C.), and neither value satisfies the
criteria. The cause is thought to be the fact that the contained
amount of any of silicon, copper, and nickel+iron+manganese is
insufficient, and therefore is below the range described above.
[0025] Alloy No. 19, similarly with Alloy No. 18, satisfies the
criteria neither for the Young's modulus nor the coefficient of
linear thermal expansion. The cause is thought to be the fact that,
although the content of copper is within the range described above,
the contained amount of both silicon and nickel+iron+manganese is
insufficient (below the range described above).
[0026] Alloy No. 20 has a Young's modulus lower than the criterial
value, and the cause is thought to be the fact that the total
contained amount of nickel+iron+manganese is 2.0% by mass, and this
is below the condition described above of a total
nickel+iron+manganese content of 3.0% by mass.
[0027] Alloy No. 21 satisfies the criteria for Young's modulus and
coefficient of linear thermal expansion, but caused sticking to the
die. The cause is thought to be the fact that iron was not
substantially added, and this did not satisfy the conditions
described above.
[0028] Alloy No. 22 had insufficient elongation, and since the test
piece broke within the elastic deformation region, the Young's
modulus was not measurable. This is thought to be because manganese
was not substantially added, and the conditions described above
regarding the composition were not satisfied.
[0029] Alloy No. 23 does not satisfy the criteria for either
Young's modulus or coefficient of linear thermal expansion. The
cause is thought to be the fact that the copper content is
insufficient at 1% by mass (is below the range described
above).
[0030] Alloy No. 24 also does not satisfy the criteria for either
Young's modulus or coefficient of linear thermal expansion. The
cause is thought to be the fact that the silicon content is
insufficient at 12% by mass (is below the range described
above).
[0031] In contrast, aluminum alloys No. 1-17 of the present
invention, satisfying the range of composition described above, as
shown in table 1, have Young's moduli and coefficients of linear
thermal expansion that satisfy the criteria.
INDUSTRIAL APPLICABILITY
[0032] The aluminum alloy for casting of the present invention may
be used optimally for the casting of members particularly requiring
a high rigidity and low linear expansion coefficient.
* * * * *