U.S. patent application number 10/579075 was filed with the patent office on 2007-10-18 for cast aluminium alloy.
This patent application is currently assigned to EADS DEUTSCHLAND GMBH. Invention is credited to Hubert Koch, Blanka Lenczowski.
Application Number | 20070240796 10/579075 |
Document ID | / |
Family ID | 34585030 |
Filed Date | 2007-10-18 |
United States Patent
Application |
20070240796 |
Kind Code |
A1 |
Koch; Hubert ; et
al. |
October 18, 2007 |
Cast Aluminium Alloy
Abstract
Cast aluminium alloys comprising 1.0-8.0% in weight magnesium
(Mg), >1.0-4.0% in weight silicon (Si), 0.01-<0.5% in weight
scandium (Sc), 0.005-0.2% in weight titanium (Ti), 0-0.5% in weight
of at least one element or selected from the group consisting of
zirconium (Zr), hafnium (Hf), molybdenum (Mo), terbium (Tb),
niobium (Nb), gadolinium (Gd), erbium (Er) and vanadium (V), 0-0.8%
in weight manganese (Mn), 0-0.3% in weight chromium (Cr), 0-1.0% in
weight copper (Cu), 0-0.1% in weight zinc (Zn), 0-0.6% in weight
iron (Fe), 0-0.004% in weight beryllium (Be), and the remainder of
aluminium with further impurities to an individual maximum of 0.1%
in weight and totally maximally 0.5% in weight.
Inventors: |
Koch; Hubert; (Rheinfelden,
DE) ; Lenczowski; Blanka; (Neubiberg, DE) |
Correspondence
Address: |
CROWELL & MORING LLP;INTELLECTUAL PROPERTY GROUP
P.O. BOX 14300
WASHINGTON
DC
20044-4300
US
|
Assignee: |
EADS DEUTSCHLAND GMBH
Ottobrunn
DE
85521
ALUMINIUM-RHEINFELDEN GMBH
Rheinfelden
DE
79618
|
Family ID: |
34585030 |
Appl. No.: |
10/579075 |
Filed: |
November 3, 2004 |
PCT Filed: |
November 3, 2004 |
PCT NO: |
PCT/DE04/02425 |
371 Date: |
June 21, 2007 |
Current U.S.
Class: |
148/688 ;
420/544 |
Current CPC
Class: |
C22C 21/08 20130101;
C22F 1/047 20130101 |
Class at
Publication: |
148/688 ;
420/544 |
International
Class: |
C22C 21/08 20060101
C22C021/08 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 11, 2003 |
DE |
103 52 932.2 |
Claims
1.-16. (canceled)
17. A cast aluminium alloy, wherein the alloy comprises 1.0-8.0% by
weight magnesium (Mg), >1.0-4.0% by weight silicon (Si),
0.01-<0.5% by weight scandium (Sc), 0.005-0.2% by weight
titanium (Ti), 0.001-<0.1% by weight zinc (Zn) 0-0.5% by weight
of an element or an element group selected from the group
consisting of zirconium (Zr), hafnium (Hf), molybdenum (Mo),
terbium (Tb), niobium (Nb), gadolinium (Gd), erbium (Er) and
vanadium (V), 0-0.8% by weight manganese (Mn), 0-0.3% by weight
chromium (Cr), 0-1.0% by weight copper (Cu), 0-0.6% by weight iron
(Fe), 0-0.004% by weight beryllium (Be), the remainder being
aluminum, provided that the total amount of impurities is not more
than 0.5% by weight and provided that no single impurity is present
in an amount of more than 0.1% by weight.
18. The cast aluminium alloy of claim 17, wherein the alloy
contains 2.0-7.0% by weight magnesium (Mg).
19. The cast aluminium alloy of claim 17, wherein the alloy
contains 3-6% by weight magnesium (Mg).
20. The cast aluminium alloy of claim 17, wherein the alloy
contains 1.1-4.0% by weight silicon (Si).
21. The cast aluminium alloy of claim 17, wherein the alloy
contains 1.1-3.0% by weight silicon (Si).
22. The cast aluminium alloy of claim 17, wherein the alloy
contains 0.01-0.45% by weight scandium (Sc).
23. The cast aluminium alloy of claim 17, wherein the alloy
contains 0.015-0.4% by weight scandium (Sc).
24. The cast aluminium alloy of claim 17, wherein the alloy
contains 0.01-0.2% by weight titanium (Ti).
25. The cast aluminium alloy of claim 17, wherein the alloy
contains 0.05-0.15% by weight titanium (Ti).
26. The cast aluminium alloy of claim 17, wherein the alloy
contains 0.01-0.3% by weight zirconium (Zr).
27. The cast aluminium alloy of claim 17, wherein the alloy
contains 0.05-0.1% by weight zirconium (Zr).
28. The cast aluminium alloy of claim 17, wherein the alloy
contains at least 0.001% by weight vanadium (V).
29. The cast aluminium alloy of claim 17, wherein the alloy
contains at least 0.008% by weight vanadium (V).
30. The cast aluminium alloy of claim 17, wherein the alloy
contains at least 0.001% by weight gadolinium (Gd).
31. The cast aluminium alloy of claim 17, wherein the alloy
contains 0.001-0.3% by weight chromium (Cr).
32. The cast aluminium alloy of claim 17, wherein the alloy
contains 0.0015-0.2% by weight chromium (Cr).
33. The cast aluminium alloy of claim 17, wherein the alloy
contains 0.001-1.0% by weight copper (Cu).
34. The cast aluminium alloy of claim 17, wherein the alloy
contains 0.5-1.0% by weight copper (Cu).
35. The cast aluminium alloy of claim 17, wherein the alloy
contains 0.001-0.05% by weight zinc (Zn).
36. The cast aluminium alloy according to claim 17, wherein the
alloy contains 0.05-0.6% by weight iron (Fe).
37. The cast aluminium alloy according to claim 17, wherein the
alloy contains 0.05-0.2% by weight iron (Fe).
38. The cast aluminium alloy of claim 17, wherein the alloy
contains maximally 0.15% by weight manganese (Mn).
39. The cast aluminium alloy of claim 17, wherein the alloy
contains 0.4-0.8% by weight manganese (Mn).
40. A method of producing a cast part said method comprising:
casting a part comprising the alloy of claim 17 and heat treating
the part at a temperature of from 250-400.degree. C. to produce a
thermally stressed cast part.
41. The method of claim 40, wherein said casting step involves
diecasting, sand casting, permanent mold casting, thixocasting,
rheocasting or similar casting techniques.
42. The method of claim 40, wherein said part is selected from the
group consisting of cylinder heads, crankcases, heat-resistant
safety components, air conditioner components and structural
airplane components.
43. The method of claim 40, wherein said part is selected from the
group consisting of supersonic aircraft components, engine segments
and pylons.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a 371(c) National Stage of
PCT/DE2004/002425 filed Nov. 3, 2004, which claims priority to
Germany patent application Serial No. 103 52 932.2 filed Nov. 11,
2003, the disclosures of which are incorporated herein in their
entireties.
FIELD OF THE INVENTION
[0002] The present invention relates to a cast aluminium alloy
suitable particularly for thermally highly stressed cast parts. By
using the cast aluminium alloy according to the invention, the
efficiency of cast parts produced therefrom is improved
considerably, their thermal stability being guaranteed up to
temperatures of 400.degree. C.
BACKGROUND OF THE INVENTION
[0003] By means of modern casting methods, such as the diecasting
method, the sand casting method, the permanent-mold casting method
or the thixocasting and rheocasting method, which are very far
developed technically, highly stressable cast parts can currently
be produced from aluminium alloys.
[0004] By means of diecasting, cast parts, for example, can be
produced which meet high demands with respect to quality. However,
the quality of a diecast part depends not only on the machine
adjustment and the selected method but to a great extent also on
the chemical composition and the structure of the used cast alloy.
It is known that the two latter parameters influence the
castability, the feeding behavior, the mechanical characteristics
and, which is particularly important in diecasting, the useful life
of the casting tools.
[0005] The alloy development per se has therefore again become more
important in the automobile and airplane construction in order to
achieve the desired characteristics of the components by means of
special alloy compositions.
[0006] From the state of the art, a plurality of compositions for
cast aluminium alloys are known.
[0007] European Patent Document EP 0 687 742 A1, for example,
discloses a diecast alloy on an aluminium silicon base, which
contain 9.5-11.5% in weight silicon, 0.1-0.5% in weight magnesium,
0.5-0.8% in weight manganese, max. 0.15% in weight iron, max. 0.03%
in weight copper, max. 0.10% in weight zinc, max. 0.15% in weight
titanium as well as a remainder of aluminium and a permanent
finishing with 30 to 300 ppm strontium.
[0008] From European Patent Document EP 0 792 380 A1, an aluminium
alloy is known which consists of 5.4-5.8% in weight magnesium,
1.8-2.5% in weight silicon, 0.5-0.9% in weight manganese, max. 0.2%
in weight titanium, max. 0.15% in weight iron and aluminium as the
remainder with further impurities to an individual max. of 0.02% in
weight and totally maximally 0.2% in weight, which are suitable
particularly for thixocasting or thixoforging.
[0009] Furthermore, from European Patent Document EP 1 229 141 A1,
a cast aluminium alloy is known, which is suitable mainly for
permanent mold casting and sand casting, and contains at least
0.05-0.5% in weight manganese, 0.2-1.0% in weight magnesium, 4-7%
in weight zinc and 0.15-0.45% in weight chromium.
[0010] However, these cast aluminum alloys are conceived mainly for
safety-relevant vehicle components, such as control arms, supports,
frame parts and wheels, in the case of which a high ductile yield
is primarily in the foreground. These alloys are not suitable for
thermal stresses of up to 400.degree. C. The classical cast
aluminium alloys are thermally stable only up to approximately
200.degree. C.
[0011] From the article by Feikus et al. "Optimization of a Cast
AlSi Alloy and Application-Oriented Development of the Casting
Practice for Producing Highly Stressable Engine Blocks", Giesserei
(Foundry) 88 (2001), No. 11, Pages 25-32, an AlSi7MgCuNiFe alloy is
known which is conceived especially for cast engine parts.
[0012] Also, from International Patent Document WO A-96/10099,
aluminium alloys containing scandium are known for increasing the
stability. The high stability is a result of an artificial aging
after a solution heat treatment and quenching with water. It is a
disadvantage that a distortion occurs as a rule during the solution
heat treatment, which distortion has to be corrected by additional
measures or operating steps (measuring and aligning).
SUMMARY OF THE INVENTION
[0013] One object of the present invention is to provide a cast
aluminium alloy which is suitable for thermally highly stressed
cast parts. In this case, the high-temperature stability, that is
the thermal stability, of the mechanical characteristics is to be
ensured up to temperatures of 400.degree. C. Furthermore, the cast
aluminium alloy according to the invention preferable has a good
weldability and should be producible by means of a plurality of
methods while the castability is good.
[0014] These objects are achieved a cast aluminium alloy which
consists at least of (comprises)
[0015] 1.0-8.0% in weight magnesium (Mg),
[0016] >1.0-4.0% in weight silicon (Si),
[0017] 0.01-<0.5% in weight scandium (Sc),
[0018] 0.005-0.2% in weight titanium (Ti),
[0019] 0-0.5% in weight of an element or an element group selected
from the group consisting of zirconium (Zr), hafnium (Hf),
molybdenum (Mo), terbium (Tb), niobium (Nb), gadolinium (Gd),
erbium (Er) and vanadium (V),
[0020] 0-0.8% in weight manganese (Mn),
[0021] 0-0.3% in weight chromium (Cr),
[0022] 0-1.0% in weight copper (Cu),
[0023] 0-0.1% in weight zinc (Zn),
[0024] 0-0.6% in weight iron (Fe),
[0025] 0-0.004% in weight beryllium (Be),
[0026] the remainder of aluminium and further impurities to an
individual maximum of 0.1% in weight and totally maximally 0.5% in
weight. As used herein, the phrase "% in weight" or "% by weight"
refers to the weight percentage based on the total weight of the
composition.
[0027] The magnesium content in this case is preferably between
2-7% in weight, particularly preferably between 3-6% in weight.
[0028] The silicon content is advantageously between 1.1-4.0% in
weight, particularly advantageously between 1.1-3.0% in weight.
[0029] The addition of scandium is essential. In addition to an
intensive particle hardening, the scandium causes a grain refining
of the cast structure and a recrystallization inhibition as a
result of the thermally very stable Al.sub.3Sc particles. Cast
parts produced from the alloy according to the invention, therefore
have the advantage that their mechanical characteristics are stable
up to temperatures of 400.degree. C. The cast alloy according to
the invention is therefore predestined mainly for thermally highly
stressed cast parts. It is also advantageous, that, as a result of
the high thermal stability, a replacement of aluminium materials by
materials of a high density is not required. By the use of the
alloy according to the invention, the component weight is
guaranteed while the conductivity is increased, which component
weight can even be reduced by cast parts which have thinner walls.
It is another advantage that the weldability is also improved by
means of the scandium fraction. The scandium content is preferably
between 0.01-0.45% in weight, particularly preferably between
0.015-0.4% in weight.
[0030] Like scandium, titanium also causes a grain refining and
therefore contributes in a corresponding manner to the improvement
of the thermal stability. In addition, titanium lowers the electric
conductivity. The titanium content preferably amounts to between
0.01-0.2% in weight, particularly between 0.05-0.15% in weight.
[0031] Since zirconium has the same effect as scandium or titanium,
it is also advantageous to additionally admix zirconium to the
alloy. The effect of the scandium of causing an intensive particle
hardening by the thermally very stable Al.sub.3Sc particles, a
grain refining of the structure as well as a recrystallization
inhibition is further increased by the combined effect of scandium
and zirconium. Zirconium substitutes Sc atoms and forms particles
of the ternary compound Al.sub.3(Sc.sub.1-xZr.sub.x) which have
less of a tendency to coagulate at higher temperatures than the
Al.sub.3Sc particles. The scandium and zirconium constituents again
improve the thermal stability of the alloy in comparison to an
alloy which contains only scandium. This permits a further
optimization in the direction of lower scandium contents for
lowering the cost. The zirconium content of preferred embodiments
is between 0.01-0.3% in weight or 0.05-0.1% in weight.
[0032] In addition to the increase of thermal stability by adding
scandium, titanium and possibly zirconium, there is the advantage
that the cast aluminium alloy already has the
thermal-stability-increasing effect as cast. As a result of the
subsequent heat treatment in a temperature range of typically
250-400.degree. C., the mechanical characteristics with the
corresponding thermal stability are finally achieved. By means of
the appropriate selection of the temperature and the time
duration-as known, the time duration depending on the component
size and thickness-the thermal stability can be varied
correspondingly. A solution heat treatment with a subsequent
artificial aging is not required, which is advantageous in that the
problem concerning the distortion will not play any role, which
distortion usually requires a measuring and aligning and, as known,
occurs in the case of classical solution-heat-treated and
artificially aged cast aluminium alloys.
[0033] In addition to the zirconium or instead of the zirconium,
hafnium, molybdenum, terbium, niobium, gadolinium, erbium and/or
vanadium may be added to the alloy. According to an alternative
embodiment, the alloy contains one or more elements selected from
the group consisting of zirconium, hafnium, molybdenum, terbium,
niobium, gadolinium, erbium and vanadium. In this case, the sum of
the selected elements amounts to maximally 0.5% in weight,
preferably, however, 0.01-0.3% in weight.
[0034] However, it is particularly advantageous for the alloy to
contain at least 0.001% in weight, preferably at least 0.008% in
weight vanadium. Vanadium acts as a grain refiner, similarly to
titanium. Furthermore, it improves the weldability and reduces the
scratching tendency of the molten material.
[0035] According to another alternative embodiment, the alloy
contains at least 0.001% in weight gadolinium.
[0036] For the further optional alloy constituents chromium, copper
and zinc, the following content ranges are preferred:
[0037] Chromium: 0.001-0.3% in weight, particularly 0.0015-0.2% in
weight
[0038] copper: 0.001-1.0% in weight, particularly 0.5-1.0% in
weight
[0039] zinc: 0.001-0.1% in weight, particularly 0.001-0.05% in
weight.
[0040] It is known that by adding iron and/or manganese, the
adhesive effect is reduced. Preferably, a manganese content of
maximally 0.01% in weight and an iron content of from 0.05-0.6% in
weight is used. The technical iron content is typically at least
0.12% in weight. However, the addition of iron and/or manganese is
not absolutely necessary for permanent mold casting and sand
casting.
[0041] In contrast, an addition of iron and/or manganese is
required for the diecasting method in order to reduce the adhesive
effect of the diecast part in the mold. In the case of cast
aluminium alloy, the manganese content for the diecasting is
preferably between 0.4-0.8% in weight. In addition, the sum of the
manganese and iron content should amount to at least 0.8% in
weight. However, it is particularly advantageous for the diecast
alloy to contain either only iron or only manganese.
[0042] Certain embodiments of the present invention may be further
understood by reference to the following specific examples. These
examples and the terminology used herein are for the purpose of
describing particular embodiments only and are not intended to be
limiting.
EXAMPLES
[0043] From three different alloys, sample rods for determining the
mechanical characteristics were cast by means of the permanent Diez
rod mold. In addition to scandium and titanium, the first alloy
also contains zirconium. The second alloy has a higher scandium
content than the first alloy but contains no zirconium. The third
alloy is a variant with a higher magnesium and silicon content.
[0044] In addition, a fourth alloy, which also contains copper, was
produced by means of diecasting. This alloy was obtained by melting
in a 200 kg electrically heated crucible furnace. The casting
temperature was 700.degree. C. The casting took place on a 400 t
(tension holding force) diecasting machine. A plate of the
measurements 220.times.60.times.3 mm was used as the sample shape.
Sample rods for tension tests were taken from the plates. The
sample rods were machined only on the narrow sides.
[0045] A reference alloy (alloy 5) containing neither scandium nor
zirconium was used for comparison purposes. This alloy was also
cast by means of a permanent Diez rod mold. The respective alloy
compositions are summarized in Table 1. TABLE-US-00001 TABLE 1
Alloy Compositions Alloy Alloy Compositions (wt.-%) ng Si Cu Fe Mn
Mg Cr Zn Ti V Zr Sc 1 1.11 0 0.065 0.1 3.09 0.001 0.002 0.149 0.036
0.076 0.15 2 1.11 0 0.066 0.103 3.34 0.001 0.005 0.122 0.033 0 0.4
3 2.49 0 0.08 0.06 5.6 0 0 0.118 0.19 0.08 0.15 4 2.35 0.001 0.078
0.69 5.59 0.001 0.001 0.1 0.044 0.06 0.17 5 1.1 0 0.081 0.004 3.036
0.001 0.003 0.129 0.03 0 0 (Ref.)
[0046] The mechanical characteristics of the different alloys
according to the invention cast by means of a permanent Diez rod
mold were measured as cast, after a 3-hour heat treatment at
300.degree. C. and subsequently at different thermal stresses
(200E/500 h, 250.degree. C./500 h, 350.degree. C./500 h and
400.degree. C./500 h), for determining the thermal stability. The
mechanical characteristics of alloy 4 (diecast alloy) were measured
only as cast and after a 1-hour 300.degree. C. heat treatment. The
reference alloy was subjected to a conventional annealing. The
reference alloy was solution treated at 540.degree. C. for 12
hours; was then quenched with water and was then artificially aged
at 165.degree. C. for 6 hours. The measuring results are summarized
in Table 2, Rp0.2 being the yield strength in MPa, Rm being the
tensile strength in MPa, and A5 being the breaking tension in
%.
[0047] The tests show that the alloy according to the invention
already has good mechanical characteristics as cast. By means of a
heat treatment (here, 300.degree. C. for 3 hours or 300.degree. C.
for 1 hour), the mechanical characteristics are further increased,
which is a result of particle hardening by segregation from the
oversaturated solid solution during "artificial aging"; thus the
formation of secondary precipitations Al.sub.3(Sc.sub.1-xZr.sub.x).
In addition, the thermal stability of alloys 1-3 up to temperatures
of 400.degree. C. is easily recognizable. Particularly the values
for the yield strength and the tensile strength are quite high up
to temperatures of 400.degree. C. When comparing the measured
values of the reference alloy at 250.degree. C. with the
corresponding values of the alloy according to the invention, it
can clearly be recognized that very good mechanical characteristics
are retained in the case of the alloy according to the invention.
In contrast, the reference alloy already exhibits a clear reduction
of the yield strength and of the tensile strength at 250.degree.
C.
[0048] In addition to the thermal stability up to temperatures of
400.degree. C., the alloy according to the invention has a very
good weldability. It has an excellent casting behavior and can be
produced by means of conventional casting methods (diecasting, sand
casting, permanent mold casting, thixocasting, rheocasting or
derivatives of these methods).
[0049] The alloy according to the invention is preferably used for
thermally highly stressed cast parts. These are, for example,
cylinder heads, crankcases, components for air conditioners;
structural airplane parts, particularly for supersonic aircraft,
engine segments, pylons, which are highly stressed connection
components between the engine and the wings, and the like.
TABLE-US-00002 TABLE 2 Mechanical Characteristics Mechanical Cast-
Characteristics ing Rp0.2 Rm A5 Alloy Mold Heat Treatment [MPa]
[MPa] [%] 1 Diez as cast 105 229 13.8 1 Diez 300.degree. C./3 h 200
272 8.6 1 Diez 300.degree. C./3 h & 200.degree. C./500 h 196
270 8.4 1 Diez 300.degree. C./3 h & 250.degree. C./500 h 202
279 8.1 1 Diez 300.degree. C./3 h & 350.degree. C./500 h 149
241 11.5 1 Diez 300.degree. C./3 h & 400.degree. C./500 h 105
201 13.5 2 Diez as cast 124 202 3.9 2 Diez 300.degree. C./3 h 274
315 2.7 2 Diez 300.degree. C./3 h & 200.degree. C./500 h 253
295 1.9 2 Diez 300.degree. C./3 h & 250.degree. C./500 h 236
285 3 3 Diez as cast 100 240 8.1 3 Diez 300.degree. C./3 h 207 290
4 3 Diez 300.degree. C./3 h & 200.degree. C./500 h 215 296 3.8
3 Diez 300.degree. C./3 h & 250.degree. C./500 h 212 294 3.6 3
Diez 300.degree. C./3 h & 350.degree. C./500 h 178 278 5.7 3
Diez 300.degree. C./3 h & 400.degree. C./500 h 135 245 11.4 4
die- as cast 194 335 15.8 cast- ing 4 die- 300.degree. C./1 h 247
349 9.9 cast- ing 5(ref- Diez 540.degree. C./12 h/w/165.degree.
C./6 h 184 270 13.8 erence) 5(ref- Diez & 200.degree. C./500 h
161 226 14.1 erence) 5(ref- Diez & 250.degree. C./500 h 87 180
17.7 erence)
[0050] The foregoing description and examples have been set forth
merely to illustrate the invention and are not intended to be
limiting. Since modifications of the described embodiments
incorporating the spirit and substance of the invention may occur
to person skilled in the art, the invention should be construed
broadly to include all variations within the scope of the appended
claims and equivalents thereof
* * * * *