U.S. patent application number 11/029130 was filed with the patent office on 2005-08-11 for casting of an aluminium alloy.
Invention is credited to Franke, Rudiger, Koch, Hubert.
Application Number | 20050173032 11/029130 |
Document ID | / |
Family ID | 34683119 |
Filed Date | 2005-08-11 |
United States Patent
Application |
20050173032 |
Kind Code |
A1 |
Koch, Hubert ; et
al. |
August 11, 2005 |
Casting of an aluminium alloy
Abstract
A casting with good heat resistance comprises an alloy with 2 to
4 w. % magnesium 0.9 to 1.5 w. % silicon 0.1 to 0.4 w. % manganese
0.1 to 0.4 w. % chromium max. 0.2 w. % iron max. 0.1 w. % copper
max. 0.2 w. % zinc max. 0.2 w. % titanium max. 0.3 w. % zirconium
max. 0.008 w. % beryllium max. 0.5 w. % vanadium with aluminium as
the remainder, with further elements and production-induced
contaminants individually max. 0.02 w. %, total max. 0.2 w. %.
Inventors: |
Koch, Hubert; (Rheinfelden,
DE) ; Franke, Rudiger; (Lorrach, DE) |
Correspondence
Address: |
BACHMAN & LAPOINTE, P.C.
900 CHAPEL STREET
SUITE 1201
NEW HAVEN
CT
06510
US
|
Family ID: |
34683119 |
Appl. No.: |
11/029130 |
Filed: |
January 4, 2005 |
Current U.S.
Class: |
148/549 ;
420/546 |
Current CPC
Class: |
C22C 21/08 20130101 |
Class at
Publication: |
148/549 ;
420/546 |
International
Class: |
C22C 021/08 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 11, 2004 |
CH |
00195/04 |
Claims
1: A casting process for producing a cast product comprising: (a)
providing an aluminum alloy comprising: 2 to 4 w. % magnesium 0.9
to 1.5 w. % silicon 0.1 to 0.4 w. % manganese 0.1 to 0.4 w. %
chromium max. 0.2 w. % iron max. 0.1 w. % copper max. 0.2 w. % zinc
max. 0.2 w. % titanium max. 0.3 w. % zirconium max. 0.008 w. %
beryllium max. 0.5 w. % vanadium with aluminium as the remainder,
with further elements and production-induced contaminants
individually max. 0.02 w. %, total max. 0.2 w. %; and (b) casting
the aluminum alloy to produce a cast product.
2: A process according to claim 1, wherein the alloy contains 2.5
to 3.5 w. % Mg.
3: A process according to claim 1, wherein the alloy contains 0.9
to 1.3 w. % Si.
4: A process according to claim 1, wherein the alloy contains 0.15
to 0.3 w. % Mn.
5: A process according to claim 1, wherein the alloy contains 0.15
to 0.3 w. % Cr.
6: A process according to claim 1, wherein the alloy contains 0.05
to 0.15 w. % Ti.
7: A process according to claim 1, wherein the alloy contains max.
0.15 w. % Fe.
8: A process according to claim 1, wherein the alloy contains max.
0.05 w. % Cu.
9: A process according to claim 1, wherein the alloy contains 0.002
to 0.005 w. % Be.
10: A process according to claim 1, wherein the alloy contains 0.01
to 0.1 w. % V.
11: A process according to claim 1, wherein the alloy contains 0.1
to 0.2 w. % Zr.
12: A process according to claim 1, wherein the alloy is sandcast
or chilled casting process.
13: A process according to claim 11 wherein the alloy is chillcast
or chilled casting process.
14: An aluminium alloy with good heat resistance comprising: 2 to 4
w. % magnesium 0.9 to 1.5 w. % silicon 0.1 to 0.4 w. % manganese
0.1 to 0.4 w. % chromium max. 0.2 w. % iron max. 0.1 w. % copper
max. 0.2 w. % zinc max. 0.2 w. % titanium max. 0.3 w. % zirconium
max. 0.008 w. % beryllium max. 0.5 w. % vanadium with aluminium as
the remainder, with further elements and production-induced
contaminants individually max. 0.02 w. %, total max. 0.2 w. %.
15: The alloy of claim 14, wherein the alloy contains 2.7 to 3.3 w.
% Mg.
16: The alloy of claim 14, wherein the alloy contains 0.05 to 0.15
w. % Ti.
17: The alloy of claim 14, wherein the alloy contains max. 0.15 w.
% Fe.
18: The alloy of claim 14, wherein the alloy contains max. 0.05 w.
% Cu.
19: The alloy of claim 14, wherein the alloy contains 0.002 to
0.005 w. % Be.
20: The alloy of claim 14, wherein the alloy contains 0.01 to 0.1
w. % V.
Description
[0001] The invention concerns a casting of an aluminium alloy with
good heat resistance.
[0002] For thermally stressed components today normally AlSi alloys
are used, where the heat resistance is achieved by the addition of
Cu to the alloy. Copper, however, also increases the heat crack
tendency and has a negative effect on the castability. Applications
in which particular heat resistance is required normally occur in
the field of cylinder heads in automobile construction, see e.g. F.
J. Feikus, "Optimisation of Aluminium Silicon Casting Alloys for
Cylinder Heads", Giesserei-Praxis 1999, Vol. 2, pages 50-57.
[0003] WO-A-0043560 discloses an aluminium alloy with 2.5-7.0 w. %
Mg, 1.0-3.0 w. % Si, 0.3-0.49 w. % Mn, 0.1-0.3 w. % Cr, max. 0.15
w. % Ti, max. 0.15 w. % Fe, max. 0.00005 w. % Ca, max. 0.00005 w. %
Na, max. 0.0002 w. % P, other contaminants individually max. 0.02
w. % and aluminium as the remainder, for the production of safety
components in diecasting, squeeze casting, thixoforming and
thixoforging processes.
[0004] The invention is based on the object of preparing an
aluminium alloy with good heat resistance suitable for the
production of thermally stressed components. The alloy is
particularly suitable for gravity diecasting, low pressure chilled
casting and sand casting.
[0005] Components cast from the alloy should have a high strength
in connection with high ductility. The desired mechanical
properties of the component are defined as follows:
1 Yield strength Rp0.2 > 170 MPa Tensile strength Rm > 230
MPa Elongation at fracture A5 > 6%
[0006] Because of the applications, the corrosion tendency of the
alloys should be kept as low as possible and the alloy must have a
correspondingly good fatigue strength. The castability of the alloy
should be better than that of the AlSiCu casting alloys which are
currently used, and the alloy should have no tendency to heat
cracks.
[0007] The term "casting" includes, as well as the pure components
produced solely by casting, those cast as a premould and
subsequently formed to the final dimensions by hot or cold
shaping.
[0008] Examples of pure castings are those which are produced
exclusively by sand casting, gravity diecasting, low pressure
chilled casting, diecasting, thixocasting or squeeze casting.
[0009] Forming operations performed on a cast premould by shaping
are for example forging and thixoforging.
[0010] The object according to the invention is achieved by an
aluminium alloy with
[0011] 2 to 4 w. % magnesium
[0012] 0.9 to 1.5 w. % silicon
[0013] 0.1 to 0.4 w. % manganese
[0014] 0.1 to 0.4 w. % chromium
[0015] max. 0.2 w. % iron
[0016] max. 0.1 w. % copper
[0017] max. 0.2 w. % zinc
[0018] max. 0.2 w. % titanium
[0019] max. 0.3 w. % zirconium
[0020] max. 0.008 w. % beryllium
[0021] max. 0.5 w. % vanadium
[0022] with aluminium as the remainder, with further elements and
production-induced contaminants individually max. 0.02 w. %, total
max. 0.2 w. %.
[0023] The following content ranges are preferred for the
individual alloy elements:
2 Mg 2.5 to 3.5 w. %, in particular 2.7 to 3.3 w. % Si 0.9 to 1.3
w. % Mn 0.15 to 0.3 w. % Cr 0.15 to 0.3 w. % Ti 0.05 to 0.15 w. %
Fe max. 0.15 w. % Cu max. 0.05 w. % Be 0.002 to 0.005 w. % V 0.01
to 0.1 w. % Zr 0.1 to 0.2 w. %
[0024] The effect of the alloy elements can be characterised
approximately as follows:
[0025] Silicon in conjunction with magnesium leads to a
corresponding hardening where in particular thermal hardening is of
interest. Preferred is heat treatment to a state T6 e.g. solution
annealing at 550.degree. C. for 12 hours with subsequent artificial
ageing at 160-170.degree. C. for 8 to 10 hours.
[0026] The combination of manganese and chromium leads to good heat
resistance at a sustained temperature of up to 180.degree. C.
[0027] Titanium and zirconium are used for grain refining. Good
grain refining makes a substantial contribution to an improvement
in casting properties.
[0028] Beryllium in conjunction with vanadium reduces the dross
formation.
[0029] A preferred area of application of the castings according to
the invention is thermally stressed components, in particular
pressure vessels, compressor housings and engine components such as
cylinder heads in automobile construction. The components are
preferably produced in the sand casting or chilled casting
process.
[0030] Further advantages, features and details of the invention
arise from the description below of preferred embodiment examples
and the drawing which shows:
[0031] FIGS. 1-3 tensile strength, yield strength and elongation at
fracture as a function of temperature after 500 hours sustained
temperature load for an alloy according to the invention and a
comparison alloy according to the prior art.
[0032] An alloy according to the invention reference AlMg3SilMnCr
and a comparison alloy reference AlSi7MgCu1 by F. J. Feikus,
"Optimisation of Aluminium Silicon Casting Alloys for Cylinder
Heads", Giesserei-Praxis 1999, Vol. 2, pages 50-57, with the
compositions given in table 1, were compared with regard to
long-term behaviour under sustained temperature load.
3TABLE 1 Chemical Composition of Alloys (in w. %) Alloy Si Fe Cu Mn
Mg Cr Zn Ti Be V Zr AlSi7MgCu1 6.97 0.11 0.94 0.005 0.38 0.008 0.03
AlMg3Si1MnCr 1.10 0.07 0.001 0.20 3.2 0.21 0.002 0.12 0.003 0.03
0.0005
[0033] The alloy according to the invention was cast in a trial rod
mould according to Diez for round rods 16 mm diameter. The
mechanical properties of yield strength (Rp0.2), tensile strength
(Rm) and elongation at fracture (A5) were determined on the trial
rods in state T6 (165.degree. C./6 hours) after a sustained
temperature load of 500 hours at various temperatures. The
corresponding values for the comparison alloy were taken from the
above article by F. J. Feikus. The results are shown in FIG. 1 in
diagram form.
[0034] The alloy AlMg3Si1MnCr according to the invention admittedly
does not reach the peak values of the comparison alloy AlSi7MgCu1
with regard to yield strength and tensile strength, but in its
temperature behaviour is "less changeable". This changeability has
a disruptive effect in operation insofar as slight changes in
temperature can cause great changes in mechanical properties. The
yield strength of the alloy according to the invention remains at
around the same level up to around 180.degree. C., gradually falls
away up to 200.degree. C., and only above around 200.degree. C.
begins to decrease continuously. The continuous decrease takes
place with a lesser gradient than the alloy AlSi7MgCu1.
[0035] With regard to the elongation at fracture, the alloy
according to the invention is characterised by an almost constant
value up to 180.degree. C. High elongation values give a favourable
fracture/failure behaviour. A visible deformation precedes the
break of the component. Above 180.degree. C. the elongation rises
continuously. In the comparison alloy AlSi7MgCu1, the clear
hardening effect can be seen. Low elongation values cause an
unfavourable failure behaviour i.e. the component only deforms
slightly or not at all. Under load peaks the component breaks
without warning.
* * * * *