NON-AGE-HARDENING ALUMINUM ALLOY AS A SEMIFINISHED MATERIAL FOR STRUCTURES

ALLIAGE D'ALUMINIUM A DURCISSEMENT NON VIEILLISSANT COMME MATERIAU SEMI-FINI POUR STRUCTURES

English Abstract

The present invention relates to the chemical composition
of alloys, in particular naturally hard semifinished-material
alloys, which are intended to be used in this form
as material for semifinished materials.
Proposed is a naturally hard aluminum alloy for
semifinished materials which, in addition to magnesium,
titanium, beryllium, zirconium, scandium, and cerium, is
also made of manganese, copper, zinc, and an element group
containing iron and silicon, the ratio of iron to silicon
being in the range of 1 to 5.

French Abstract

La présente invention concerne des compositions chimiques d'alliages, notamment d'alliages de demi-produits à dureté naturelle, lesdits alliages entrant dans la composition de demi-produits sous cette forme. La présente invention concerne en particulier un alliage d'aluminium à dureté naturelle destiné à des structures de demi-produits. Ledit alliage d'aluminium contient en % en poids: magnésium (5,0-5,6) ; titane (0,01-0,05); béryllium (0,0001-0,005); zircon (0,05-0,15); scandium (0,18-0,30); cérium (0,001-0,004); manganèse (0,05-0,18); cuivre (0,05-0,18); zinc (0,05-0,15); un groupe d'éléments contenant fer et silicium (0,04-0,24), le rapport entre fer et silicium étant de 1 à 5 ; et, un reste d'aluminium.

Claims

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. A naturally hard aluminum alloy as a semifinished
material for a structure, comprising:
magnesium from 5.0 to 5.6 weight percent;
titanium from 0.01 to 0.05 weight percent;
beryllium from 0.0001 to 0.005 weight percent;
zirconium from 0.05 to 0.15 weight percent;
scandium from 0.18 to 0.30 weight percent;
cerium from 0.001 to 0.004 weight percent;
manganese from 0.05 to 0.18 weight percent;
copper from 0.05 to 0.15 weight percent;
zinc from 0.05 to 0.15 weight percent;
0.04 to 0.24 weight percent total iron and silicon,
wherein the ratio of iron to silicon is in a range of 1 to
5;
a balance of aluminum.
8

Description

CA 02398667 2009-08-25
NON-AGE-HARDENING ALUMINUM ALLOY AS A SEMIFINISHED MATERIAL
FOR STRUCTURES
The present invention relates to the composition of alloys, in
particular naturally hard semifinished-material alloys, which
are intended to be used in this form as material for
structures.
Naturally hard aluminum alloys are used in metallurgy as
semifinished materials for structures (see GOST standard
4784-74), but primarily in the form of AMg6 alloy, which
contains the following (in % by weight):
magnesium 5.8 - 6.8
manganese 0.5 - 0.8
titanium 0.02 - 0.1
beryllium 0.0002 - 0.005
aluminum balance
However, such an alloy does not have adequate physical
properties, in particular a low 0.2% yield strength in the
case of cold-formed and hot-formed semifinished materials.
A naturally hard aluminum alloy, which is used as a
semifinished material for structures (see the patent RU No.
2085607, IPC class C22 C 21/06), also belongs to the related
art as a prototype having the following chemical composition
(% by weight):
magnesium 3.9 - 4.9
titanium 0.01 -0.1
beryllium 0.0001 - 0.005
zirconium 0.05 - 0.15
scandium 0.20 - 0.50
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CA 02398667 2009-08-25
cerium 0.001 - 0.004
aluminum balance
This known alloy does not have sufficient static and dynamic
strength, while having high processibility during the
manufacturing process, high corrosion resistance, good
weldability, and a high readiness for operation under
low-temperature conditions.
The subject matter of the present invention is a new,
naturally hard aluminum alloy for semifinished materials
which, in addition,to magnesium, titanium, beryllium,
zirconium, scandium, and cerium, is also made of manganese,
copper, zinc, and an element group containing iron and
silicon, in the following composition of the components
(weight%), the ratio of iron to silicon being in the range of
1 to 5:
magnesium 5.0 - 5.6
titanium 0.01 - 0.05
beryllium 0.0001 - 0.005
zirconium 0.05 - 0.15
scandium 0.18 - 0.30
cerium 0.001 - 0.004
manganese 0.05 - 0.18
copper 0.05 - 0.15
zinc 0.05 - 0.15
element group including
iron and silicon 0.04 - 0.24
aluminum balance
The alloy of the present invention is distinguished from the
conventional one by its addition of manganese, copper, zinc,
and an element [chemical] group containing iron and silicon,
the components having the following proportions (weighto), and
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CA 02398667 2009-08-25
the ratio of iron to silicon having to be between 1 and 5:
magnesium 5.0 - 5.6
titanium 0.01 - 0.05
beryllium 0.0001 - 0.005
zirconium 0.05 - 0.15
scandium 0.18 - 0.30
cerium 0.001 - 0.004
manganese 0.05 - 0.18
copper 0.05 - 0.15
zinc 0.05 - 0.15
element group including
iron and silicon 0.04 - 0.24
aluminum balance
The technical effect.consists in the improvement of the static
and dynamic physical properties of the alloy, which means that
the service life, operational reliability, and weight value of
the structures subjected to static and dynamic loads improve,
in particular those of the structures of various aircraft and
spacecraft, including craft that burn cryogenic fuel.
Due to the present invention's proportions between the
chemical levels and the chemical constituents, the alloy has a
rather ductile matrix, which is made up of a mixed crystal of
dissolved magnesium, manganese, copper, and zinc in aluminum.
The particularly high readiness of the alloy for operation
under cyclical dynamic loads is due to the high ductility of
the matrix. Secondary precipitation of finely distributed
intermetallic particles, which contain aluminum, scandium,
zirconium, titanium, and other transition metals occurring in
the alloy, provides for both the high static strength of the
alloy and a high resistance to crack propagation during
cyclical loading. The setpoint value of the ratio of iron to
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CA 02398667 2009-08-25
silicon optimizes the morphology of the primary intermetallic
compounds, which result from the solidification, are
principally made of aluminum, iron, and silicon, and provide
for an improvement in the static strength of the alloy, while
its dynamic strength and plasticity are maintained.
Example
Using A85 aluminum, MG90 magnesium, copper MO, zinc TsO,
binary key alloys such as aluminum-titanium,
aluminum-beryllium, aluminum-zirconium, aluminum-scandium,
aluminum-cerium, aluminum-manganese, aluminum-iron, and
silumin as an additive, the melt was prepared in an electric
oven, on which 165 x 550 mm flat ingots of the alloy according
to the present invention were cast with the aid of
semicontinuous casting techniques (Table 1); the ingots having
a minimum (composition 1), optimum (composition 2), and
maximum (composition 3) proportion of constituents, including
proportions of the constituents going beyond the present
limitations (compositions 4 and 5), as well as the
conventional alloy (composition 6) (see Table 1).
If the alloy is prepared under metallurgical production
conditions, then scrap metal made of aluminum-magnesium alloys
may be used as an additive.
The ingots were homogenized and machined to a thickness of 140
mm. They were subsequently hot-rolled to a thickness of 7 mm
at a temperature of 400 C and then cold-rolled to a thickness
of 4 mm. The cold-rolled sheets were heat-treated in an
electric oven. The heat-treated sheets were used as test
material.
Standard transverse specimens taken out [Standard specimens
cross-cut out] of the sheets were used to determine the static
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CA 02398667 2009-08-25
tensile strength (R,,,, R.po,2, A) and the dynamic strength:
- number of cycles to failure (N) in determining the
short-term strength (LCF), for which specimens having a
notch factor of Kt = 2.5 and a maximum stress amaX = 160
MPa are used;
- crack-propagation speed da/dN in a range of the stress
intensity factor AK = 31.2 MPamo.s;
- critical stress intensity factor Kc in the state of planar
[two-dimensional] stress, the width (B) of the specimen
being 160 mm.
All tests were conducted at room temperature.
The test results are listed in Table 2.
Table 2 verifies that the alloy of the present invention has a
higher static and dynamic strength than the conventional
alloy. This allows one to reduce the weight of the structures
made of the alloy according to the present invention by 10 to
15%, in order to reduce operating costs, which is particularly
important to the aircraft industry. The high readiness of the
alloy according to the present invention to operate under
static and dynamic conditions, as well as the fact that the
alloy according to the present invention is a naturally hard
alloy having a high corrosion resistance and good weldability,
allows one to use it for the construction of completely new
aircraft and spacecraft, sea-going vessels, land-bound
vehicles, and other vehicles whose structural elements are
joined by welding. The alloy according to the present
invention may be used as base material in welded structures,
and as a welding additive for welded connections.
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CA 02398667 2009-08-25
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