Title of Invention	HIGH TEMPERATURE ALUMINIUM ALLOY
Abstract	In an aluminium alloy of type AlMgSi with good creep strength at elevated temperatures for the production of castings subject to high thermal and mechanical stresses the contents of the alloying elements magnesium and silicon in % w/w in a Cartesian coordinate system are limited by a polygon A with the coordinates [Mg; Si] [8.5; 2,7] [8.5; 4,7] [6.3; 2,7] [6.3; 3.4] and that the alloy also contains 0.1 to 1% w/w manganese max. 1% w/w iron max. 3% w/w copper max. 2% w/w nickel max. 0.5% w/w chromium max. 0.6% w/w cobalt max. 0.2% w/w zinc max. 0.2% w/w titanium max. 0.5% w/w zirconium max. 0.008% w/w beryllium max. 0.5% w/w vanadium as well as aluminium remainder rest with further elements and manufacturing-related impurities of individually max. 0.05% w/w and max. 0.2% w/w in total. The alloy is suitable in particular for the production of cylinder crankcases by the pressure die casting method.

Title of Invention

HIGH TEMPERATURE ALUMINIUM ALLOY

Abstract

In an aluminium alloy of type AlMgSi with good creep strength at elevated temperatures for the production of castings subject to high thermal and mechanical stresses the contents of the alloying elements magnesium and silicon in % w/w in a Cartesian coordinate system are limited by a polygon A with the coordinates [Mg; Si] [8.5; 2,7] [8.5; 4,7] [6.3; 2,7] [6.3; 3.4] and that the alloy also contains 0.1 to 1% w/w manganese max. 1% w/w iron max. 3% w/w copper max. 2% w/w nickel max. 0.5% w/w chromium max. 0.6% w/w cobalt max. 0.2% w/w zinc max. 0.2% w/w titanium max. 0.5% w/w zirconium max. 0.008% w/w beryllium max. 0.5% w/w vanadium as well as aluminium remainder rest with further elements and manufacturing-related impurities of individually max. 0.05% w/w and max. 0.2% w/w in total. The alloy is suitable in particular for the production of cylinder crankcases by the pressure die casting method.

Full Text	The invention relates to an aluminium alloy of type AlMgSi with good creep strength at elevated tempera- tures for the production of castings subject to high thermal and mechanical stresses. The further development of diesel engines with the aim of achieving an improved combustion of the diesel fuel and a higher specific output leads inter alia to a higher explosion pressure and in consequence to a pulsating mechanical load acting on the cylinder crank- case that makes very high demands on the material. Apart from a high fatigue strength, a good endurance strength at high temperatures of the material is a further precondition for its use in the production of cylinder crankcases. AlSi alloys are generally used today for components subject to high thermal stresses, this high-temperature strength being achieved by the addition of Cu to the alloy. Copper does, however, also increase the hot shortness and has a negative effect on the castability. Applications in which in particular high-temperature strength is demanded are primarily found in the area of the cylinder heads of automotive engines, see e.g. F.J. Feikus, "Optimierung von Aluminium-Silicium- Guss legierungen fur Zylinderkdpfe" [Optimization of Aluminium-Silicon Casting Alloys for Cylinder Heads], Giesserei-Praxis, 1999, Volume 2, pp. 50-57. A high-temperature AlMgSi alloy for the production of cylinder heads is known from US-A-3 868 250. The alloy contains, apart from the normal additives, 0.6 to 4.5% w/w Si, 2.5 to 11% w/w Mg, of which 1 to 4.5% w/w free Mg, and 0.6 to 1.8% w/w Mn. WO-A-96 "15281 describes an aluminium alloy with 3.0 to 6.0% w/w Mg, 1.4 to 3.5% w/w Si, 0.5 to 2.0% w/w Mn, max. 0.1 5% w/w Fe, max. 0.2% w/w Ti and aluminium as remainder with further impurities of individual].y max. 0.02% w/w, and max. 0.2% w/w in total. The alloy is suitable for the production of components where high demands are made on the mechanical properties. Process- ing of the alloy is preferably by pressure die casting, thixocasting or thixoforging. A similar aluminium alloy for the production of safety components by pressure die casting, squeeze casting, thixoforming or thixoforging is known from WO-A- 0043560. The alloy contains 2.5 . - 7.0% w/w Mg, 1.0 - 3.0% w/w Si, 0.3 - 0.49% w/w Mn, 0.1 - 0.3% w/w Cr, max. 0.15% w/w Ti, max. 0.15% w/w Ti, max. 0.15% w/w Fe, max. 0.00005% w/w Ca, max. 0.00005% w/w Na, max. 0.0002% w/w P, further impurities of individually max. 0.02% w/w and aluminium as remainder. A casting alloy of type AlMgSi known from EP-A- 1 234 393 contains 3.0 to 7.0% w/w Mg, 1.7 to 3.0% w/w Si, 0.2 to 0.48% w/w Mn, 0.15 to 0.35% w/w Fe, max. 0.2% w/w Ti, optionally also 0.1 to 0.4% w/w Ni and Al as remainder and manufacturing-related impurities of individually max. 0.02% w/w and max. 0.2% w/w in total, with the further condition that magnesium and silicon in the alloy essentially exist in a ratio Mg : Si of 1.7 : 1 by weight, corresponding to the composition of the quasi-binary eutectic with the solid phases Al and Mg2Si. The alloy is suitable for the production of safety components in motor vehicles by pressure die casting, rheocasting and thixocasting. The object of the invention is to provide an aluminium alloy with good creep strength at elevated temperatures for the production of components subject to high thermal and mechanical stresses. The alloy should be suitable in particular for pressure die casting, but also for Gravity die casting, low-pressure die casting and sand casting. A specific object of the invention is the provision of an aluminium alloy for cylinder crankcases of internal combust: ion engines, in particular of diesel engines, produced by pressure die casting. The components cast from the alloy should exhibit high strength together with high ductility. The intended mechanical properties in the component are defined as follows: Proof strength RpO.2 > 170 MPa Tensile strength Rm > 230 MPa Elongation at break A5 > 6% The castability of the alloy should be comparable with the castability of the AlSiCu casting alloys currently used, and the alloy should not show any tendency to hot shortness. The object is achieved with the solution according to the invention in that the contents of the alloying elements magnesium and silicon in % w/w in a Cartesian coordinate system are limited by a polygon A with the coordinates [Mg; Si] [8.5; 2,7] [8.5; 4,7] [6.3; 2,7] [6.3; 3.4] and that the alloy also contains 0.1 to 1% w/w manganese max. 1% w/w iron max. 3% w/w copper max. 2% w/w nickel max. 0.5% w/w chromium max. 0.6% w/w cobalt max. 0.2% w/w zinc max. 0.2% w/w titanium max. 0.5% w/w zirconium max. 0.008% w/w beryllium max: 0.5% w/w vanadium as we I 1 as aluminium as remainder with further elements and manufacturing-related impurities of individually max. 0.0b% w/w and max. 0.2% w/w in total. The following content ranges are preferred for the main alloying elements, Mg and Si: Mg 6.9 to 7.9% w/w, in particular 7.1 to 7.7% w/w Si 3.0 to 3.7% w/w, in particular 3.1 to 3.6% w/w Particularly preferred are alloys whose contents of the alloying elements magnesium and silicon in % w/w in a Cartesian coordinate system are limited by a polygon B with the coordinates [Mg; Si] [7.9; 3,0] [7.9; 3,7] [6.9; 3,0] [6.9; 3,7], in particular by a polygon C with the coordinates [Mg; Si] [7.7; 3.1] [7.7; 3,6] [7.1; 3,1] [7.1; 3,6]. . The alloying elements Mn and Fe allow sticking of the castings to the mould to be avoided. A higher iron content results in a higher high-temperature strength at the expense of reduced elongation. Mn contributes also significantly to red hardness. Depending on the field of application, the alloying elements Fe and Mn are therefore preferably balanced with one another as follows: With a content of 0.4 to 1% w/w Fe, in particular 0.5 to 0.7% w/w Fe, a content of 0.1 to 0.5% w/w Mn, in particular 0.3 to 0.5% w/w Mn, is set. With a content of max. 0.2% w/w Fe, in particular max. 0.15% w/w Fe, a content of 0.5 to 1% w/w Mn, in particular 0.5 to 0.8% w/w Mn, is set. The following content ranges are preferred for the further alloying elements: Cu 0.2 to 1.2% w/w, preferably 0.3 to 0.8% w/w, in particular 0.4 to 0.6% w/w Ni 0.8 to 1.2% w/w Cr max. 0.2% w/w, preferably max. 0.05% w/w Co 0.3 to 0.6% w/w Ti 0.0b to 0.15% w/w Fe max. 0.15% w/w Zr 0.1 to 0.4% w/w Copper results in an additional increase in strength, but with increasing contents leads to a deterioration in the corrosion behaviour of the alloy. The addition of cobalt allows the demoulding behaviour of the alloy to be further improved. Titanium and zirconium improve the grain refinement. A good gram refinement contributes significantly to an improvement in the casting properties and mechanical properties. Beryllium in combination with vanadium reduces the formation of dross. With an addition of 0.02 to 0.15% w/w V, preferably 0.02 to 0.08% w/w V, in particular 0.02 to 0.05% w/w V, less than 60 ppm Be are sufficient. A preferred field of application of the aluminium alloy according to the invention is the production of components subject to high thermal and mechanical stresses by pressure die casting, mould casting or sand casting, in particular for cylinder crankcases for automotive engines produced by the pressure die casting method. The alloy according to the invention also satisfies the mechanical properties demanded for structural compo- nents in automotive construction after a single-stage heat treatment without separate solution annealing. Further advantage, features and properties of the invention can be seen from the following description of preferred exemplary embodiments and from the drawing that shows in Fig. 1 a diagram with the content limits for the alloying elements Mg and Si The polygon A shown in Fig. 1 defines the content range for the alloying elements Mg and Si, the polygons B and C refer to preferred ranges. The straight line E corresponds to the composition of the quasi-binary eutectic Al-Mg2Si. The alloy compositions according to the invention thus lie on the side with an excess of magnesium. The alloy according to the invention was cast into pressure die cast plates with different wall thicknesses. Tensile strength test specimens were manufactured from the pressure die cast plates. The mechanical properties proof strength (Rp0.2), tensile strength (Rm) and elongation at break (A) were determined on the tensile strength test specimens in the conditions F As cast iater/F As cast, quenched in water after demoulding F> 24 h As cast, > 24 h storage at room temperature Water/F > 24 As cast, quenched in water after demoulding, > 24 h storage at room temperature and after various single-stage heat treatment processes at temperatures in the range from 250°C to 380°C and after long-term storage at temperatures in the range from l50°C to 250°C. The al ioys examined are summarized in Table ] . The letter: A indicates alloys with copper additive, the letter B alloys without copper additive. Table 2 shows the results of the mechanical properties determined on tensile strength test specimens of the alloys in Table 1. An alloy not included in Tables 1 and 2 with good creep strength at elevated temperatures exhibited the following composition (in % w/w): 3.4 Si, 0.6 Fe, 0.42 Cu, 0.32 Mn, 7.4 Mg, 0.07 Ti, 0.9 Ni, 0.024 V and 0.004 Be The results of the long-term tests underline the good creep strength at elevated temperatures of the alloy according to the invention. The mechanical properties after a single-stage heat treatment at 350°C and 380°C for 90 minutes indicate furthermore that the alloy according to the invention also satisfies the demands made for structural components in automotive construction. WE CLAIM: 1. Aluminium alloy of type AlMgSi with good creep strength at elevated temperatures for the production of castings subject to high thermal and mechanical stresses, characterized in that the contents of the alloying elements magnesium and silicon in % w/w in a Cartesian coordinate system are limited by a polygon A with the coordinates [Mg; Si] [8.5; 2,7] [8.5; 4,7] [6.3; 2,7] [6.3;3.4] and that the alloy also contains 0.1 to 1% w/w manganese max. 1% w/w iron max. 3% w/w copper max. 2% w/w nickel max. 0.5% w/w chromium max. 0.6% w/w cobalt max. 0.2% w/w zinc max. 0.2% w/w titanium max. 0.5% w/w zirconium max. 0.008% w/w beryllium max. 0.5% w/w vanadium as well as aluminium as remainder with further elements and manufacturing-related impurities of individually max. 0.05% w/w and max. 0.2% w/w in total. 2. Aluminium alloy as claimed in Claim 1, wherein 6.9 to 7.9% w/w Mg, preferably 7,1 to 7,7% w/w Mg. 3. Aluminium alloy as claimed in Claim 1 or 2, wherein 3.0 to 3.7% w/w Si, preferably 3.1 to 3.6% w/w Si. 4. Aluminium alloy as claimed in Claim 1, wherein the contents of the alloying elements magnesium and silicon in % w/w in a Cartesian coordinate system are limited by a polygon B with the coordinates [Mg; Si] [7.9; 3,0][7.9; 3,7] [6.9; 3,0] [6.9;3,7]. 5.Aluminium alloy as claimed in Claim 4, wherein the contents of the alloying elements magnesium and silicon in % w/w in a Cartesian coordinate system are limited by a polygon C with the coordinates [Mg; Si] [7.7; 3.1] [7.7;3,6] [7.1; 3,1] [7.1; 3,6]. 6.Aluminium alloy as claimed in one of Claims 1 to 5, wherein 0.4 to 1% w/w Fe, preferably 0.5 to 0.7% w/w Fe, and 0.1 to 0.5% w/w Mn, preferably 0.3 to 0.5% w/w Mn. 7. Aluminium alloy as claimed in one of Claims 1 to 5, wherein max. 0.20% w/w Fe, preferably max. 0.15% w/w Fe, and 0.5 to 1% w/w Mn, preferably 0.5 to 0.8% w/w Mn. 8. Aluminium alloy as claimed in one of Claims 1 to 7, wherein 0.2 to 1.2% w/w Cu, preferably 0.3 to 0.8% w/w Cu, in particular 0.4 to 0.6% w/w Cu. 9.Aluminium alloy as claimed in one of Claims 1 to 8, wherein 0.8 to 1.2% w/w Ni. lO.Aluminium alloy as claimed in one of Claims 1 to 9, wherein max. 0.2% w/w Cr, preferably max. 0.05% w/w Cr. 11.Aluminium alloy as claimed in one of Claims 1 to 10, wherein 0.3 to 0.6% w/w Co. 12.Aluminium alloy as claimed in one of Claims 1 to 11, wherein 0.05 to 0.15% w/w Ti. 13.Aluminium alloy as claimed in one of Claims 1 to 12, wherein 0.1 to 0.4% w/w Zr. 14.Aluminium alloy as claimed in one of Claims 1 to 13, wherein 0.02 to 0.15% w/w V, preferably 0.02 to 0.08% w/w V, in particular 0.02 to 0.05% w/w V, and less than 60 ppm Be. 15. Aluminium alloy as claimed in one of Claims 1 to 14 for components subject to high thermal and mechanical stresses produced by pressure die casting, mould casting or sand casting. 16. Aluminium alloy as claimed in Claim 15 for cylinder crank-cases produced by the pressure die casting method in automotive engine construction. 17. Aluminium alloy as claimed in one of Claims 1 to 14 for safety components produced by the pressure die casting method in automotive construction. Abstract In an aluminium alloy of type AlMgSi with good creep strength at elevated temperatures for the production of castings subject to high thermal and mechanical stresses the contents of the alloying elements magnesium and silicon in % w/w in a Cartesian coordinate system are limited by a polygon A with the coordinates [Mg; Si] [8.5; 2,7] [8.5; 4,7] [6.3; 2,7] [6.3; 3.4] and that the alloy also contains 0.1 to 1% w/w manganese max. 1% w/w iron max. 3% w/w copper max. 2% w/w nickel max. 0.5% w/w chromium max. 0.6% w/w cobalt max. 0.2% w/w zinc max. 0.2% w/w titanium max. 0.5% w/w zirconium max. 0.008% w/w beryllium max. 0.5% w/w vanadium as well as aluminium remainder rest with further elements and manufacturing-related impurities of individually max. 0.05% w/w and max. 0.2% w/w in total. The alloy is suitable in particular for the production of cylinder crankcases by the pressure die casting method.

Full Text

The invention relates to an aluminium alloy of type
AlMgSi with good creep strength at elevated tempera-
tures for the production of castings subject to high
thermal and mechanical stresses.
The further development of diesel engines with the aim
of achieving an improved combustion of the diesel fuel
and a higher specific output leads inter alia to a
higher explosion pressure and in consequence to a
pulsating mechanical load acting on the cylinder crank-
case that makes very high demands on the material.
Apart from a high fatigue strength, a good endurance
strength at high temperatures of the material is a
further precondition for its use in the production of
cylinder crankcases.
AlSi alloys are generally used today for components
subject to high thermal stresses, this high-temperature
strength being achieved by the addition of Cu to the
alloy. Copper does, however, also increase the hot
shortness and has a negative effect on the castability.
Applications in which in particular high-temperature
strength is demanded are primarily found in the area of
the cylinder heads of automotive engines, see e.g. F.J.
Feikus, "Optimierung von Aluminium-Silicium-
Guss legierungen fur Zylinderkdpfe" [Optimization of
Aluminium-Silicon Casting Alloys for Cylinder Heads],
Giesserei-Praxis, 1999, Volume 2, pp. 50-57.
A high-temperature AlMgSi alloy for the production of
cylinder heads is known from US-A-3 868 250. The alloy
contains, apart from the normal additives, 0.6 to 4.5%
w/w Si, 2.5 to 11% w/w Mg, of which 1 to 4.5% w/w free
Mg, and 0.6 to 1.8% w/w Mn.

WO-A-96 "15281 describes an aluminium alloy with 3.0 to
6.0% w/w Mg, 1.4 to 3.5% w/w Si, 0.5 to 2.0% w/w Mn,
max. 0.1 5% w/w Fe, max. 0.2% w/w Ti and aluminium as
remainder with further impurities of individual].y max.
0.02% w/w, and max. 0.2% w/w in total. The alloy is
suitable for the production of components where high
demands are made on the mechanical properties. Process-
ing of the alloy is preferably by pressure die casting,
thixocasting or thixoforging.
A similar aluminium alloy for the production of safety
components by pressure die casting, squeeze casting,
thixoforming or thixoforging is known from WO-A-
0043560. The alloy contains 2.5 . - 7.0% w/w Mg, 1.0 -
3.0% w/w Si, 0.3 - 0.49% w/w Mn, 0.1 - 0.3% w/w Cr,
max. 0.15% w/w Ti, max. 0.15% w/w Ti, max. 0.15% w/w
Fe, max. 0.00005% w/w Ca, max. 0.00005% w/w Na, max.
0.0002% w/w P, further impurities of individually max.
0.02% w/w and aluminium as remainder.
A casting alloy of type AlMgSi known from EP-A-
1 234 393 contains 3.0 to 7.0% w/w Mg, 1.7 to 3.0% w/w
Si, 0.2 to 0.48% w/w Mn, 0.15 to 0.35% w/w Fe, max.
0.2% w/w Ti, optionally also 0.1 to 0.4% w/w Ni and Al
as remainder and manufacturing-related impurities of
individually max. 0.02% w/w and max. 0.2% w/w in total,
with the further condition that magnesium and silicon
in the alloy essentially exist in a ratio Mg : Si of
1.7 : 1 by weight, corresponding to the composition of
the quasi-binary eutectic with the solid phases Al and
Mg2Si. The alloy is suitable for the production of
safety components in motor vehicles by pressure die
casting, rheocasting and thixocasting.
The object of the invention is to provide an aluminium
alloy with good creep strength at elevated temperatures
for the production of components subject to high
thermal and mechanical stresses. The alloy should be
suitable in particular for pressure die casting, but

also for Gravity die casting, low-pressure die casting
and sand casting.
A specific object of the invention is the provision of
an aluminium alloy for cylinder crankcases of internal
combust: ion engines, in particular of diesel engines,
produced by pressure die casting.
The components cast from the alloy should exhibit high
strength together with high ductility. The intended
mechanical properties in the component are defined as
follows:
Proof strength RpO.2 > 170 MPa
Tensile strength Rm > 230 MPa
Elongation at break A5 > 6%
The castability of the alloy should be comparable with
the castability of the AlSiCu casting alloys currently
used, and the alloy should not show any tendency to hot
shortness.
The object is achieved with the solution according to
the invention in that the contents of the alloying
elements magnesium and silicon in % w/w in a Cartesian
coordinate system are limited by a polygon A with the
coordinates [Mg; Si] [8.5; 2,7] [8.5; 4,7] [6.3; 2,7]
[6.3; 3.4] and that the alloy also contains
0.1 to 1% w/w manganese
max. 1% w/w iron
max. 3% w/w copper
max. 2% w/w nickel
max. 0.5% w/w chromium
max. 0.6% w/w cobalt
max. 0.2% w/w zinc
max. 0.2% w/w titanium
max. 0.5% w/w zirconium
max. 0.008% w/w beryllium
max: 0.5% w/w vanadium

as we I 1 as aluminium as remainder with further elements
and manufacturing-related impurities of individually
max. 0.0b% w/w and max. 0.2% w/w in total.
The following content ranges are preferred for the main
alloying elements, Mg and Si:
Mg 6.9 to 7.9% w/w, in particular 7.1 to 7.7% w/w
Si 3.0 to 3.7% w/w, in particular 3.1 to 3.6% w/w
Particularly preferred are alloys whose contents of the
alloying elements magnesium and silicon in % w/w in a
Cartesian coordinate system are limited by a polygon B
with the coordinates [Mg; Si] [7.9; 3,0] [7.9; 3,7]
[6.9; 3,0] [6.9; 3,7], in particular by a polygon C
with the coordinates [Mg; Si] [7.7; 3.1] [7.7; 3,6]
[7.1; 3,1] [7.1; 3,6]. .
The alloying elements Mn and Fe allow sticking of the
castings to the mould to be avoided. A higher iron
content results in a higher high-temperature strength
at the expense of reduced elongation. Mn contributes
also significantly to red hardness. Depending on the
field of application, the alloying elements Fe and Mn
are therefore preferably balanced with one another as
follows:
With a content of 0.4 to 1% w/w Fe, in particular 0.5
to 0.7% w/w Fe, a content of 0.1 to 0.5% w/w Mn, in
particular 0.3 to 0.5% w/w Mn, is set.
With a content of max. 0.2% w/w Fe, in particular max.
0.15% w/w Fe, a content of 0.5 to 1% w/w Mn, in
particular 0.5 to 0.8% w/w Mn, is set.
The following content ranges are preferred for the
further alloying elements:

Cu 0.2 to 1.2% w/w, preferably 0.3 to 0.8% w/w, in
particular 0.4 to 0.6% w/w
Ni 0.8 to 1.2% w/w
Cr max. 0.2% w/w, preferably max. 0.05% w/w
Co 0.3 to 0.6% w/w
Ti 0.0b to 0.15% w/w
Fe max. 0.15% w/w
Zr 0.1 to 0.4% w/w
Copper results in an additional increase in strength,
but with increasing contents leads to a deterioration
in the corrosion behaviour of the alloy.
The addition of cobalt allows the demoulding behaviour
of the alloy to be further improved.
Titanium and zirconium improve the grain refinement. A
good gram refinement contributes significantly to an
improvement in the casting properties and mechanical
properties.
Beryllium in combination with vanadium reduces the
formation of dross. With an addition of 0.02 to 0.15%
w/w V, preferably 0.02 to 0.08% w/w V, in particular
0.02 to 0.05% w/w V, less than 60 ppm Be are
sufficient.
A preferred field of application of the aluminium alloy
according to the invention is the production of
components subject to high thermal and mechanical
stresses by pressure die casting, mould casting or sand
casting, in particular for cylinder crankcases for
automotive engines produced by the pressure die casting
method.
The alloy according to the invention also satisfies the
mechanical properties demanded for structural compo-
nents in automotive construction after a single-stage
heat treatment without separate solution annealing.

Further advantage, features and properties of the
invention can be seen from the following description of
preferred exemplary embodiments and from the drawing
that shows in
Fig. 1 a diagram with the content limits for the
alloying elements Mg and Si
The polygon A shown in Fig. 1 defines the content range
for the alloying elements Mg and Si, the polygons B and
C refer to preferred ranges. The straight line E
corresponds to the composition of the quasi-binary
eutectic Al-Mg2Si. The alloy compositions according to
the invention thus lie on the side with an excess of
magnesium.
The alloy according to the invention was cast into
pressure die cast plates with different wall
thicknesses. Tensile strength test specimens were
manufactured from the pressure die cast plates. The
mechanical properties proof strength (Rp0.2), tensile
strength (Rm) and elongation at break (A) were
determined on the tensile strength test specimens in
the conditions
F As cast
iater/F As cast, quenched in water after demoulding
F> 24 h As cast, > 24 h storage at room temperature
Water/F > 24 As cast, quenched in water after
demoulding, > 24 h storage at room temperature
and after various single-stage heat treatment processes
at temperatures in the range from 250°C to 380°C and
after long-term storage at temperatures in the range
from l50°C to 250°C.

The al ioys examined are summarized in Table ] . The
letter: A indicates alloys with copper additive, the
letter B alloys without copper additive.
Table 2 shows the results of the mechanical properties
determined on tensile strength test specimens of the
alloys in Table 1.
An alloy not included in Tables 1 and 2 with good creep
strength at elevated temperatures exhibited the
following composition (in % w/w):
3.4 Si, 0.6 Fe, 0.42 Cu, 0.32 Mn, 7.4 Mg, 0.07 Ti, 0.9
Ni, 0.024 V and 0.004 Be
The results of the long-term tests underline the good
creep strength at elevated temperatures of the alloy
according to the invention. The mechanical properties
after a single-stage heat treatment at 350°C and 380°C
for 90 minutes indicate furthermore that the alloy
according to the invention also satisfies the demands
made for structural components in automotive
construction.

WE CLAIM:
1. Aluminium alloy of type AlMgSi with good creep strength at elevated
temperatures for the production of castings subject to high thermal and
mechanical stresses,
characterized in that
the contents of the alloying elements magnesium and silicon in % w/w in
a Cartesian coordinate system are limited by a polygon A with the
coordinates [Mg; Si] [8.5; 2,7] [8.5; 4,7] [6.3; 2,7] [6.3;3.4] and that the
alloy also contains
0.1 to 1% w/w manganese
max. 1% w/w iron
max. 3% w/w copper
max. 2% w/w nickel
max. 0.5% w/w chromium
max. 0.6% w/w cobalt
max. 0.2% w/w zinc
max. 0.2% w/w titanium
max. 0.5% w/w zirconium
max. 0.008% w/w beryllium
max. 0.5% w/w vanadium
as well as aluminium as remainder with further elements and
manufacturing-related impurities of individually max. 0.05% w/w and
max. 0.2% w/w in total.
2. Aluminium alloy as claimed in Claim 1, wherein 6.9 to 7.9% w/w Mg,
preferably 7,1 to 7,7% w/w Mg.
3. Aluminium alloy as claimed in Claim 1 or 2, wherein 3.0 to 3.7% w/w
Si, preferably 3.1 to 3.6% w/w Si.

4. Aluminium alloy as claimed in Claim 1, wherein the contents of the
alloying elements magnesium and silicon in % w/w in a Cartesian
coordinate system are limited by a polygon B with the coordinates [Mg;
Si] [7.9; 3,0][7.9; 3,7] [6.9; 3,0] [6.9;3,7].
5.Aluminium alloy as claimed in Claim 4, wherein the contents of the
alloying elements magnesium and silicon in % w/w in a Cartesian
coordinate system are limited by a polygon C with the coordinates [Mg;
Si] [7.7; 3.1] [7.7;3,6] [7.1; 3,1] [7.1; 3,6].
6.Aluminium alloy as claimed in one of Claims 1 to 5, wherein 0.4 to 1%
w/w Fe, preferably 0.5 to 0.7% w/w Fe, and 0.1 to 0.5% w/w Mn,
preferably 0.3 to 0.5% w/w Mn.
7. Aluminium alloy as claimed in one of Claims 1 to 5, wherein max.
0.20% w/w Fe, preferably max. 0.15% w/w Fe, and 0.5 to 1% w/w Mn,
preferably 0.5 to 0.8% w/w Mn.
8. Aluminium alloy as claimed in one of Claims 1 to 7, wherein 0.2 to
1.2% w/w Cu, preferably 0.3 to 0.8% w/w Cu, in particular 0.4 to 0.6%
w/w Cu.
9.Aluminium alloy as claimed in one of Claims 1 to 8, wherein 0.8 to
1.2% w/w Ni.
lO.Aluminium alloy as claimed in one of Claims 1 to 9, wherein max.
0.2% w/w Cr, preferably max. 0.05% w/w Cr.

11.Aluminium alloy as claimed in one of Claims 1 to 10, wherein 0.3 to
0.6% w/w Co.
12.Aluminium alloy as claimed in one of Claims 1 to 11, wherein 0.05 to
0.15% w/w Ti.
13.Aluminium alloy as claimed in one of Claims 1 to 12, wherein 0.1 to
0.4% w/w Zr.
14.Aluminium alloy as claimed in one of Claims 1 to 13, wherein 0.02 to
0.15% w/w V, preferably 0.02 to 0.08% w/w V, in particular 0.02 to
0.05% w/w V, and less than 60 ppm Be.
15. Aluminium alloy as claimed in one of Claims 1 to 14 for components
subject to high thermal and mechanical stresses produced by pressure
die casting, mould casting or sand casting.
16. Aluminium alloy as claimed in Claim 15 for cylinder crank-cases
produced by the pressure die casting method in automotive engine
construction.
17. Aluminium alloy as claimed in one of Claims 1 to 14 for safety
components produced by the pressure die casting method in automotive
construction.

Abstract

In an aluminium alloy of type AlMgSi with good creep
strength at elevated temperatures for the production of
castings subject to high thermal and mechanical
stresses the contents of the alloying elements
magnesium and silicon in % w/w in a Cartesian
coordinate system are limited by a polygon A with the
coordinates [Mg; Si] [8.5; 2,7] [8.5; 4,7] [6.3; 2,7]
[6.3; 3.4] and that the alloy also contains
0.1 to 1% w/w manganese
max. 1% w/w iron
max. 3% w/w copper
max. 2% w/w nickel
max. 0.5% w/w chromium
max. 0.6% w/w cobalt
max. 0.2% w/w zinc
max. 0.2% w/w titanium
max. 0.5% w/w zirconium
max. 0.008% w/w beryllium
max. 0.5% w/w vanadium
as well as aluminium remainder rest with further
elements and manufacturing-related impurities of
individually max. 0.05% w/w and max. 0.2% w/w in total.
The alloy is suitable in particular for the production
of cylinder crankcases by the pressure die casting
method.

HIGH TEMPERATURE ALUMINIUM ALLOY

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