FIELD OF THE INVENTION
[0001] The invention relates to an Al-Cu-Li wrought alloy product, more in particular an
Al-Cu-Li-Mg-Mn-Zn type alloy product for structural members. Products made from this
aluminium alloy product are very suitable for aerospace applications, but not limited
to that. The alloy can be processed to various product forms, e.g. sheet, thin plate,
thick plate, extruded or forged products.
BACKGROUND TO THE INVENTION
[0002] It is generally known in the aerospace industry that one of the most effective ways
to reduce the weight of an aircraft is to reduce the density of aluminium alloys used
in the aircraft construction. This desire led to the addition of lithium, the lowest
density metal element, to aluminium alloys. Aluminium Association alloys, such as
AA2090 and AA2091 contain about 2.0% lithium, which translates into about a 7% weight
savings over alloys containing no lithium. Aluminium alloys AA2094 and AA2095 contain
about 1.2% lithium. Another aluminium alloy, AA8090 contains about 2.5% lithium, which
translates into an almost 10% weight savings over alloys without lithium.
[0003] However, casting of such conventional alloys containing relatively high amounts of
lithium is difficult. Furthermore, the combined strength and fracture toughness of
such alloys is not optimal. A trade-off exists with conventional aluminium-lithium
alloys in which fracture toughness decreases with increasing strength. Another important
characteristic of aerospace aluminium alloys is fatigue crack growth resistance. For
example, in damage tolerant applications in aircraft, increased fatigue crack growth
resistance is desirable. Better fatigue crack growth resistance means that cracks
will grow slower, thus making airplanes much safer because small cracks can be detected
before they achieve critical size for catastrophic propagation. Furthermore, slower
crack growth can have an economic benefit due to the fact that longer inspection intervals
can be utilized.
[0004] Patent document
US-2004/0071586 discloses a broad range for an aluminium alloy comprising, 3 to 5% of Cu, 0.5% to
2% of Mg, and 0.01% to 0.9% of Li. It is disclosed that the Li content should remain
at a low level in combination with having controlled amounts of Cu and Mg to provide
the desired levels of fracture toughness and strength. Preferably the Cu and Mg are
present in the alloy in a total amount below a solubility limit of the alloy. It is
known in the art that this patent document covers the AA2060 alloy being registered
with in Aluminium Association in 2011 and having a registered alloy composition of:
Cu |
3.4 - 4.5 |
Li |
0.6 - 0.9 |
Mg |
0.6 - 1.1 |
Ag |
0.05 - 0.50 |
Zn |
0.30 0.50 |
Mn |
0.10 - 0.50 |
Zr |
0.05 - 0.15 |
[0005] Patent document
WO-2004/106570 discloses an Al-Cu-Li-Mg-Ag-Mn-Zr alloy for use as a structural member. The alloy
has 2.5% to 5.5% Cu, 0.1% to 2.5% Li, 0.2% to 1% Mg, 0.2% to 0.8% Ag, 0.2% to 0.8%
Mn, and up to 0.3% Zr, balance aluminium. It is known in the art that this patent
document covers the AA2050 alloy being registered with in Aluminium Association in
2004 and having a registered alloy composition of:
Cu |
3.2 - 3.9 |
Li |
0.7 - 1.3 |
Mg |
0.20 - 0.6 |
Ag |
0.20 - 0.7 |
Mn |
0.20 - 0.50 |
Zr |
0.06 - 0.14 |
[0006] Patent document
US-2007/0181229 discloses an aluminium alloy having 2.1% to 2.8% Cu, 1.1% to 1.7% Li, 0.1% to 0.8%
Ag, 0.2% to 0.6% Mg, 0.2% to 0.6% Mn, a content of Fe and Si less or equal to 0.1%
each, balance impurities and aluminium, and wherein the alloy is substantially zirconium
free. The low Zr content is reported to increase the toughness.
[0007] Patent document
WO-2009/036953 discloses an Al-Cu-Li-Mg-Ag-Zn-Mn-Zr alloy for use as an aircraft structural member.
The alloy has Cu 3.4% to 5.0%, Li 0.9% to 1.7%, Mg 0.2% to 0.8%, Ag 0.1% to 0.8%,
Mn 0.1% to 0.9%, Zn max. 1.5%, one or more elements selected from the group (Zr, Cr,
Ti, Sc, Hf).
[0008] Patent document
WO-2009/073794 discloses an Al-Cu-Li-Mg-Ag-Zn-Mn-Zr alloy for use as an aircraft structural member.
The alloy has Cu 3.4% to 4.2%, Li 0.9% to 1.4%, Ag 0.3% to 0.7%, Mg 0.1% to 0.6%,
Zn 0.2% to 0.8%, Mn 0.1% to 0.6%, and 0.01% to 0.6% of a grain structure control element.
It is known in the art that this patent document covers the AA2050 alloy being registered
with in Aluminium Association in 2012 and having a registered alloy composition of:
Cu |
3.2 - 4.2 |
Li |
1.0 - 1.3 |
Mg |
0.20 - 0.6 |
Zn |
0.30 - 0.7 |
Ag |
0.20 - 0.7 |
Mn |
0.10 - 0.50 |
Zr |
0.05 - 0.15 |
[0009] Patent document
WO2015/082779 discloses an Al-Ci-Li alloy product is the form of an rolled or forged product having
a thickness of 14 to 100 mm, and wherein the alloy has 1.8% to 2.6% Cu, 1.3% to 1.8%
Li, 0.1% to 0.5% Mg, 0.1% to 0.5% Mn with Zr <0.05%, or <0.05% Mn with 0.10% to 0.16%
Zr, 0 to 0.5% Ag, <0.20% Zn, 0.01% to 0.15% Ti, <0.1% Fe, <0.1% Si. The material is
in particular suitable for manufacturing airplane underwing elements.
[0010] A need exists for an aluminium alloy that is useful in aircraft application which
has an improved thermal stability while providing a good balance in strength and fracture
toughness.
DESCRIPTION OF THE INVENTION
[0011] As will be appreciated herein below, except as otherwise indicated, alloy designations
and temper designations refer to the Aluminium Association designations in Aluminium
Standards and Data and the Registration Records, as published by the Aluminium Association
in 2015 and known to the skilled person.
[0012] For any description of alloy compositions or preferred alloy compositions, all references
to percentages are by weight percent unless otherwise indicated.
[0013] As used herein, the term "about" when used to describe a compositional range or amount
of an alloying addition means that the actual amount of the alloying addition may
vary from the nominal intended amount due to factors such as standard processing variations
as understood by those skilled in the art.
[0014] The term "up to" and "up to about", as employed herein, explicitly includes, but
is not limited to, the possibility of zero weight-percent of the particular alloying
component to which it refers. For example, up to 0.07% Fe may include an alloy having
no Fe.
[0015] It is an object of the present invention to provide an improved AlCuLi-type alloy
wrought product, or at least an alternative product, ideally for structural members,
having a good balance of high strength and fracture toughness and providing an increased
thermal stability.
[0016] These and other objects and further advantages are met or exceeded by the present
invention in which there is provided an aluminium alloy wrought product for structural
members having a chemical composition consisting of, in wt.%: Cu 3.2% to 4.4%, Li
0.8% to 1.4%, Mg 0.20% to 0.90%, Mn 0.10% to 0.8%, Zn 0.20% to 0.80%, one or more
elements selected from the group consisting of: (Zr 0.05% to 0.25%, Cr 0.05% to 0.30%,
Ti 0.01% to 0.25%, Sc 0.05% to 0.4%, Hf 0.05% to 0.4%), Ag <0.05%, Fe <0.15%, Si <0.15%,
unavoidable impurities and balance aluminium.
[0017] The alloy wrought product may contain normal and inevitable impurities, typically
each <0.05% and the total <0.15%, and the balance is made by aluminium.
[0018] In accordance with the invention it has been found that this compositional range,
and with preferred narrower ranges, offers a good balance of strength, fracture toughness
and corrosion resistance meeting the requirements for commercial delivery and also
offering a very good thermal stability after being long term aged or exposed for 1000
hours at 85°C. These advantages are achieved at least in a T8 condition and by selecting
the alloying elements within the defined ranges and wherein it is an important aspect
that the subject alloy has a very low silver content.
[0019] Copper is one of the main alloying elements in the alloy product and is added to
increase the strength of the alloy product. Care must be taken, however, to not add
too much copper since the corrosion resistance can be reduced. Also, copper additions
beyond maximum solubility will lead to low fracture toughness and low damage tolerance.
The upper-limit for the Cu-content is for that reason 4.4%, and preferably about 4.2%,
and more preferably about 4.10%. A preferred lower-limit is about 3.6%, and more preferably
about 3.75%, and most preferably about 3.85%.
[0020] Magnesium is another main alloying element in the alloy product and is added to increase
strength and reduce density. Care should be taken, however, to not add too much magnesium
in combination with copper since additions beyond maximum solubility will lead to
low fracture toughness and low damage tolerance. A more preferred lower-limit for
the Mg addition is about 0.35%, more preferably 0.38%. A more preferred upper-limit
is about 0.65%, and more preferably 0.55%. It has been found that at a level of above
0.8% the further addition of Mg may result in a decrease in toughness of the alloy
product.
[0021] Lithium is another important alloying element in the wrought product of this invention
and added together with the copper and magnesium to obtain an improved combination
of fracture toughness and strength. A preferred lower-limit for the Li addition is
0.9%, and more preferably 1.0%. A preferred upper-limit for the Li addition is less
than 1.30%. A too high Li content has adverse effect on the damage tolerance properties
of the alloy product in particular with the relatively high Cu levels in the alloy
product of this invention.
[0022] The zinc is purposively added to improve strength and the corrosion resistance and
in addition it has a small effect on the damage tolerance properties of the alloy
product. In the alloy product the zinc is typically present in a range of 0.2% to
0.80%. A preferred lower-limit for the Zn-content is 0.25%. A preferred upper-limit
for the Zn-content is about 0.70%, and more preferably about 0.65%.
[0023] It is an important aspect of the invention that the silver content is less than 0.05%.
In an embodiment the silver content is less than about 0.02%, such that the aluminium
alloy is substantially free from Ag. With "substantially free" or "essentially free"
is meant that no purposeful addition was made to the chemical composition but that
due to impurities and/or leaking from contact with manufacturing equipment, trace
quantities of Ag may nevertheless find their way into the alloy product. For example,
less than 0.01% is an example of a trace quantity. That the alloy product has a very
low Ag content makes the alloy product more cost effective in comparison to the many
Al-Cu-Li alloy known in the art having a purposive addition of Ag, while still offering
a good balance of engineering properties in combination with a very good thermal stability.
[0024] The manganese addition is to control the grain structure by providing a more uniform
distribution of the main precipitating phases, a reduced grain size and thereby further
increases strength in particular. The Mn addition should not exceed about 0.8% and
should be at least about 0.10%. A preferred lower-limit for the manganese addition
is at least about 0.20%, and more preferably at least 0.30%. A preferred upper-limit
for the Mn addition is about 0.6%, and more preferably about 0.55%. A too high Mn
content results in a decrease in both the yield strength and fracture toughness.
[0025] In addition the alloy product of the present invention contains at least one element
selected from the defined group of Zr, Cr, Ti, Sc, and Hf.
[0026] It is preferred to add zirconium to the alloy product in a range of 0.05% to 0.25%,
and preferably in a range of 0.05% to 0.15%. A too low Zr addition has an adverse
on the unit propagation energy of the alloy wrought product.
[0027] Ti can be added to the alloy product amongst others for grain refiner purposes during
casting of the alloy stock, e.g. ingots or billets. The addition of Ti should not
exceed 0.25%. A preferred lower limit for the Ti addition is about 0.01%. Ti can be
added as a sole element or with either boron or carbon serving as a casting aid, for
grain size control.
[0028] The Si content in the alloy product is present as an impurity element of less than
0.15%, and should be present at the lower-end of this range, e.g. less than about
0.10%, and more preferably less than 0.07%, to maintain fracture toughness properties
at desired levels.
[0029] The Fe content in the alloy product should be less than 0.15%. When the alloy product
is used for aerospace application the lower-end of this range is preferred, e.g. less
than about 0.1%, and more preferably less than about 0.07% to maintain in particular
the toughness at a sufficiently high level. Where the alloy product is used for non-aerospace
applications, such as tooling plate, a higher Fe content can be tolerated.
[0030] In an embodiment of the alloy product the product is in the form of a rolled, extruded
or forged product, and more preferably the product is in the form of a sheet, plate,
forging or extrusion as part of an aircraft structural part.
[0031] In a preferred embodiment the alloy product is provided in the form of an extruded
product.
[0032] In a preferred embodiment the alloy product is provided in the form of a plate product,
preferably having a thickness of 12.0 to 175 mm, and preferably of at least 75 mm.
The plate product provides a good balance in engineering properties, in particular
strength and has shown reduced quench sensitivity.
[0033] When used as part of an aircraft structural part the part can be for example a fuselage
sheet, upper wing plate, lower wing plate, thick plate for machined parts, forging
or thin sheet for stringers.
[0034] Resistance to intergranular corrosion of the alloy products of the present invention
is generally high, for example, typically only pitting is detected when the metal
is submitted to corrosion testing according to MASTMAASIS (ASTM-69 A2-85). However,
the sheet and light gauge plate may also be clad, with preferred cladding thickness
of from about 1% to about 8% of the thickness of the sheet or plate. The cladding
is typically a low composition aluminium alloy.
[0035] In a further aspect of the invention it relates to a method of manufacturing a wrought
aluminium alloy product of an Al-Cu-Li alloy, the method comprising the steps of:
- a. casting stock of an ingot of an AlCuLi-alloy according to this invention,
- b. preheating and/or homogenizing the cast stock;
- c. hot working the stock by one or more methods selected from the group consisting
of rolling, extrusion, and forging;
- d. optionally cold working the hot worked stock;
- e. solution heat treating ("SHT") of the hot worked and/or optionally cold worked
stock, the SHT is carried out at a temperature and time sufficient to place into solid
solution the soluble constituents in the aluminium alloy;
- f. cooling the SHT stock, preferably by one of spray quenching or immersion quenching
in water or other quenching media;
- g. optionally stretching or compressing the cooled SHT stock or otherwise cold working
the cooled SHT stock to relieve stresses, for example levelling or drawing or cold
rolling of the cooled SHT stock; and
- h. ageing, preferably artificial ageing, of the cooled and optionally stretched or
compressed or otherwise cold worked SHT stock to achieve a desired temper.
[0036] The aluminium alloy can be provided as an ingot or slab or billet for fabrication
into a suitable wrought product by casting techniques regular in the art for cast
products, e.g. DC-casting, EMC-casting, EMS-casting. Slabs resulting from continuous
casting, e.g. belt casters or roll casters, also may be used, which in particular
may be advantageous when producing thinner gauge end products. Grain refiners such
as those containing titanium and boron, or titanium and carbon, may also be used as
is known in the art. After casting the alloy stock, the ingot is commonly scalped
to remove segregation zones near the cast surface of the ingot.
[0037] Homogenisation treatment is typically carried out in one or multiple steps, each
step having a temperature in the range of about 475°C to 535°C. The pre-heat temperature
involves heating the hot working stock to the hot-working entry temperature, which
is typically in a temperature range of about 440°C to 490°C.
[0038] Following the preheat and/or homogenisation practice the stock can be hot worked
by one or more methods selected from the group consisting of rolling, extrusion, and
forging, preferably using regular industry practice. The method of hot rolling is
preferred for the present invention.
[0039] The hot working, and hot rolling in particular, may be performed to a final gauge,
e.g. 3 mm or less or alternatively thick gauge products. Alternatively, the hot working
step can be performed to provide stock at intermediate gauge, typical sheet or thin
plate. Thereafter, this stock at intermediate gauge can be cold worked, e.g. by means
of rolling, to a final gauge. Depending on the alloy composition and the amount of
cold work an intermediate anneal may be used before or during the cold working operation.
[0040] Solution heat-treatment ("SHT") is typically carried out within the same temperature
range as used for homogenisation, although the soaking times that are chosen can be
somewhat shorter. A typical SHT is carried out at a temperature of 480°C to 525°C
for 15 min to about 5 hours. Lower SHT temperatures generally favour high fracture
toughness. Following the SHT the stock is rapidly cooled or quenched, preferably by
one of spray quenching or immersion quenching in water or other quenching media.
[0041] The SHT and quenched stock may be further cold worked, for example, by stretching
in the range of about 0.5% to 15% of its original length to relieve residual stresses
therein and to improve the flatness of the product. Preferably the stretching is in
the range of about 0.5% to 6%, more preferably of about 0.5% to 4%.
[0042] After cooling the stock is aged, typically at ambient temperatures, and/or alternatively
the stock can be artificially aged.
[0043] The alloy product according to this invention is preferably provided in a slightly
under-aged T8 condition, in particular a T84 condition, to provide the best balance
in strength and damage tolerance properties.
[0044] A desired structural shape is then machined from these heat treated plate sections,
more often generally after artificial ageing, for example, an integral wing spar.
SHT, quench, optional stress relief operations and artificial ageing are also followed
in the manufacture of thick sections made by extrusion and/or forged processing steps.
[0045] In one embodiment of the present invention comprising a welding step, the ageing
step can be divided into two steps: a pre-ageing step prior to a welding operation,
and a final heat treatment to form a welded structural member.
[0046] The AlCuLi-alloy product according to this invention can be used amongst others as
in the thickness range of at most 0.5 inch (12.5 mm) the properties will be excellent
for fuselage sheet. In the thin plate thickness range of 0.7 to 3 inch (17.7 to 76
mm) the properties will be excellent for wing plate, e.g. lower wing plate. The thin
plate thickness range can be used also for stringers or to form an integral wing panel
and stringer for use in an aircraft wing structure. When processed to thicker gauges
of more than 3 inch (75 mm) to about 11 inch (280 mm) excellent properties have been
obtained for integral part machined from plates, or to form an integral spar for use
in an aircraft wing structure, or in the form of a rib for use in an aircraft wing
structure. The alloy products according to the invention can also be provided in the
form of a stepped extrusion or extruded spar or extruded stiffeners for use in an
aircraft structure, or in the form of a forged spar for use in an aircraft wing structure.
[0047] When applied in the form of a sheet product the yield strength or proof strength
of the product should be at least 460 MPa in the L-direction, and preferably at least
480 MPa. When applied in the form of an extruded product, e.g. as a stringer, or in
the form of a plate product the yield strength or proof strength of the product should
be at least 470 MPa in the L-direction, and more preferably at least 480 MPa. These
strength levels can be obtained by a selecting the alloy composition within the claimed
ranges, and preferably within the preferred narrower ranges, in combination with the
artificial ageing practice to a T8 condition.
[0048] In the following, the invention will be explained by the following non-limitative
example.
Example.
[0049] On a laboratory scale 2 alloys have been cast and machined into rolling blocks of
260x200x80 mm. The alloy compositions are given in Table 1. These were homogenised
for 5h@500°C followed by 10h@510°C. After pre-heating to 480°C the rolling blocks
were hot rolled from 80 mm to a gauge of 30 mm. Then solution heat-treated for 30min@500°C
followed by a cold water quench and within 30 minutes thereafter stretched by 2%.
Table 1. Alloy composition (in wt.%) of the alloys processed. Balance is made by aluminium
and unavoidable impurities and with 0.03% Fe and 0.02% Si.
Alloy |
Alloying element |
Cu |
Li |
Mg |
Mn |
Zn |
Zr |
Ti |
Ag |
A |
3.9 |
1.1 |
0.4 |
0.4 |
0.4 |
0.11 |
0.02 |
0.35 |
B |
3.9 |
1.1 |
0.4 |
0.4 |
0.4 |
0.11 |
0.02 |
0.0 |
[0050] In order to bring the alloy to a T84 temper the Ag-free alloy was aged for 16h@150°C
and the Ag containing alloy for 10.5h@150°C. The difference in ageing time to arrive
at the T84 temper is due to the difference in silver-content which has an effect on
the ageing response.
[0051] In order to test the thermal stability the samples in T84 were subsequently sensitized
or aged for 1,000h@85°C.
[0052] The materials in the T84 condition and after 1000h@85°C were tested for the tensile
yield strength (TYS) in the L-direction in accordance with ASTM B557M and for the
fracture toughness (K
IC) in the L-T direction in accordance with ASTM E399. The results are listed in Table
2 below. The results of Table 2 are also plotted in Fig. 1.
[0053] In addition the samples aged after 1000h@85°C were tested for their corrosion resistance
in accordance with MASTMAASIS and SCC(ST). All ST-SCC specimens tested at 310 MPa
survived without failure for 30 days.
[0054] From the results of Table 2 and Fig. 1 it can be seen that the Ag-free alloy B compared
to alloy A provides a significantly lower drop in fracture toughness after being sensitized
while maintaining a high tensile yield strength in combination with a good corrosion
resistance. This suggests that alloy B provides an improved thermal stability than
the similar alloy containing also a purposive addition of silver.
Table 2. Mechanical properties in T84 condition and after sensitization for 1,000h@85°C.
Alloy |
Condition |
TYS (L) [MPa] |
KIC [MPa.Vm] |
A |
T84 |
537 |
43.0 |
A |
sensitized |
591 |
35.5 |
B |
T84 |
491 |
41.1 |
B |
sensitized |
531 |
40.2 |
[0055] Having now fully described the invention, it will be apparent to one of ordinary
skill in the art that many changes and modifications can be made without departing
from the spirit or scope of the invention as herein described.
1. An aluminium alloy wrought product for structural members having a chemical composition
consisting of, in wt.%:
Cu |
3.2 to 4.4 |
Li |
0.8 to 1.4 |
Mg |
0.20 to 0.90 |
Mn |
0.10 to 0.8 |
Zn |
0.20 to 0.80, |
one or more elements selected from the group consisting of:
Zr |
0.05 to 0.25, |
Cr |
0.05 to 0.30, |
Ti |
0.01 to 0.25, |
Sc |
0.05 to 0.4, |
Hf |
0.05 to 0.4, |
Ag |
< 0.05 |
Fe |
< 0.15 |
Si |
< 0.15, |
unavoidable impurities and balance aluminium.
2. An aluminium alloy wrought product according to claim 1, wherein the Cu content is
in a range of 3.6% to 4.4%, preferably in a range of 3.75% to 4.20%.
3. An aluminium alloy wrought product according to claim 1 or 2, wherein the Li content
is in a range of 0.90% to 1.4%, and preferably in a range of 1.0% to 1.30%.
4. An aluminium alloy wrought product according to any one of claims 1 to 3, wherein
the product contains Zr in a range of 0.05% to 0.15%.
5. An aluminium alloy wrought product according to any one of claims, 1 to 4, wherein
the Zn-content is maximum 0.70%, preferably maximum 0.65%.
6. An aluminium alloy wrought product according to any one of claims 1 to 5, wherein
the Ag content is less than 0.02%, and more preferably the alloy product is substantially
Ag-free.
7. An aluminium alloy wrought product according to any one of claims 1 to 6, wherein
the product contains Mn in a range of 0.20% to 0.6%, and preferably 0.20% to 0.55%.
8. An aluminium alloy wrought product according to any one of claims 1 to 7, wherein
the product contains Mg in a range of 0.20% to 0.8%, and preferably 0.20% to 0.65%,
and more preferably 0.35% to 0.65%.
9. An aluminium alloy wrought product according to any one of claims 1 to 8, wherein
the product is in the form of a rolled, extruded or forged product.
10. An aluminium alloy wrought product according to claim 9, wherein the wrought product
is in the form of an extruded product.
11. An aluminium alloy wrought product according to any one of claims 1 to 9, wherein
the wrought product is in the form of a plate product having a thickness of 12.0 mm
to 175 mm, and preferably of at least 75 mm.
12. An aluminium alloy wrought product according to any one of claims 1 to 11, wherein
the product is in an under-aged T8 condition, and preferably in an T84 condition.
13. Method of manufacturing an aluminium alloy wrought product according to any of claims
1 to 12, comprising the steps of:
a. casting stock of an ingot of an AlCuLi-alloy according to any one of claims 1 to
8,
b. preheating and/or homogenizing the cast stock;
c. hot working the stock by one or more methods selected from the group consisting
of rolling, extrusion, and forging;
d. optionally cold working the hot worked stock;
e. solution heat treating (SHT) of the hot worked and/or optionally cold worked stock,
the SHT is carried out at a temperature and time sufficient to place into solid solution
the soluble constituents in the aluminium alloy;
f. cooling the SHT stock;
g. optionally stretching or compressing the cooled SHT stock or otherwise cold working
the cooled SHT stock to relieve stresses, for example levelling or drawing or cold
rolling of the cooled SHT stock; and
h. ageing, preferably artificial ageing, of the cooled and optionally stretched or
compressed or otherwise cold worked SHT stock to achieve a desired temper.
14. Method according to claim 13, wherein homogenisation is performed at a temperature
in a range of 475°C to 535°C.
15. Method according to claim 13 or 14, wherein the hot-working is by rolling and the
hot-working entry temperature is at a temperature in the range of 440°C to 490°C.
16. Method according to any one of claims 13 to 15, wherein the solution heat treatment
is performed at a temperature in a range of 480°C to 525°C.
17. Method according to any one of claims 13 to 16, wherein the stretching is performed
in a range of 0.5% to 6%, and preferably in a range of 0.5% to 4%.
18. Method according to any one of claims 13 to 17, wherein the product has been aged
to an under-aged T8 condition.
19. Method according to any one of claims 13 to 18, wherein the wrought product is rolled
to a plate product having a thickness of at least 12.0 mm, and preferably of at least
75 mm.
1. Knetprodukt aus Aluminiumlegierung für Strukturelemente, das eine chemische Zusammensetzung
hat, die in Gew.-% besteht aus:
Cu |
3,2 bis 4,4 |
Li |
0,8 bis 1,4 |
Mg |
0,20 bis 0,90 |
Mn |
0,10 bis 0,8 |
Zn |
0,20 bis 0,80, |
einem oder mehreren Elementen ausgewählt aus der Gruppe, die besteht aus:
Zr |
0,05 bis 0,25, |
Cr |
0,05 bis 0,30, |
Ti |
0,01 bis 0,25 |
Sc |
0,05 bis 0,4, |
Hf |
0,05 bis 0,4, |
Ag |
< 0,05 |
Fe |
< 0,15 |
Si |
< 0,15, |
unvermeidliche Verunreinigungen und Rest Aluminium.
2. Knetprodukt aus Aluminiumlegierung nach Anspruch 1, wobei der Cu-Gehalt in einem Bereich
von 3,6% bis 4,4%, vorzugsweise in einem Bereich von 3,75% bis 4,20% liegt.
3. Knetprodukt aus Aluminiumlegierung nach Anspruch 1 oder 2, wobei der Li-Gehalt in
einem Bereich von 0,90% bis 1,4%, und vorzugsweise in einem Bereich von 1,0% bis 1,30%
liegt.
4. Knetprodukt aus Aluminiumlegierung nach einem der Ansprüche 1 bis 3, wobei das Produkt
Zr in einem Bereich von 0,05% bis 0,15% enthält.
5. Knetprodukt aus Aluminiumlegierung nach einem der Ansprüche 1 bis 4, wobei der Zn-Gehalt
maximal 0,70%, vorzugsweise maximal 0,65% ist.
6. Knetprodukt aus Aluminiumlegierung nach einem der Ansprüche 1 bis 5, wobei der Ag-Gehalt
weniger als 0,02% ist, und noch bevorzugter das Legierungsprodukt im Wesentlichen
frei von Ag ist.
7. Knetprodukt aus Aluminiumlegierung nach einem der Ansprüche 1 bis 6, wobei das Produkt
Mn in einem Bereich von 0,20% bis 0,6%, und vorzugsweise 0,20% bis 0,55% enthält.
8. Knetprodukt aus Aluminiumlegierung nach einem der Ansprüche 1 bis 7, wobei das Produkt
Mg in einem Bereich von 0,20% bis 0,8%, und vorzugsweise 0,20% bis 0,65%, und noch
bevorzugter 0,35% bis 0,65% enthält.
9. Knetprodukt aus Aluminiumlegierung nach einem der Ansprüche 1 bis 8, wobei das Produkt
in Form eines gewalzten, stranggepressten oder geschmiedeten Produkts vorliegt.
10. Knetprodukt aus Aluminiumlegierung nach Anspruch 9, wobei das Knetprodukt in Form
eines stranggepressten Produkts vorliegt.
11. Knetprodukt aus Aluminiumlegierung nach einem der Ansprüche 1 bis 9, wobei das Knetprodukt
in Form eines Plattenprodukts vorliegt, das eine Dicke von 12,0 mm bis 175 mm, und
vorzugsweise von mindestens 75 mm hat.
12. Knetprodukt aus Aluminiumlegierung nach einem der Ansprüche 1 bis 11, wobei das Produkt
in einem unterhärteten T8-Zustand und vorzugsweise in einem T84-Zustand ist.
13. Verfahren zur Herstellung eines Knetprodukts aus Aluminiumlegierung nach einem der
Ansprüche 1 bis 12, das die folgenden Schritte umfasst:
a. Gießen eines Werkstoffs aus einem Block einer AlCuLi-Legierung nach einem der Ansprüche
1 bis 8,
b. Vorwärmen und/oder Homogenisieren des gegossenen Werkstoffs;
c. Warmbearbeiten des Werkstoffs durch eines oder mehrere Verfahren, die aus der Gruppe
ausgewählt werden, die aus Walzen, Stranggießen und Schmieden besteht;
d. optional Kaltbearbeiten des warmbearbeiteten Werkstoffs;
e. Lösungsglühen (SHT) des warmbearbeiteten und/oder optional kaltbearbeiteten Werkstoffs,
wobei das SHT bei einer Temperatur und für eine Zeitdauer ausgeführt wird, die ausreicht,
um die löslichen Bestandteile in der Aluminiumlegierung in eine stabile Lösung zu
bringen;
f. Kühlen des SHT-Werkstoffs;
g. optional Recken oder Komprimieren des gekühlten SHT-Werkstoffs oder sonstiges Kaltbearbeiten
des gekühlten SHT-Werkstoffs um Spannungen abzubauen, zum Beispiel Richten oder Ziehen
oder Kaltwalzen des gekühlten SHT-Werkstoffs; und
h. Aushärten, vorzugsweise Warmaushärten, des gekühlten und optional gereckte oder
komprimierten oder anders kaltbearbeiteten SHT-Werkstoffs, um einen gewünschten Zustand
zu erreichen.
14. Verfahren nach Anspruch 13, wobei die Homogenisierung bei einer Temperatur in einem
Bereich von 475°C bis 535°C durchgeführt wird.
15. Verfahren nach Anspruch 13 oder 14, wobei die Warmbearbeitung durch Walzen erfolgt,
und die Warmbearbeitungs-Eingangstemperatur bei einer Temperatur im Bereich von 440°C
bis 490°C liegt.
16. Verfahren nach einem der Ansprüche 13 bis 15, wobei das Lösungsglühen bei einer Temperatur
in einem Bereich von 480°C bis 525°C durchgeführt wird.
17. Verfahren nach einem der Ansprüche 13 bis 16, wobei das Recken in einem Bereich von
0,5% bis 6%, und vorzugsweise in einem Bereich von 0,5% bis 4% durchgeführt wird.
18. Verfahren nach einem der Ansprüche 13 bis 17, wobei das Produkt auf einen unterhärteten
T8-Zustand ausgehärtet wurde.
19. Verfahren nach einem der Ansprüche 13 bis 18, wobei das Knetprodukt in ein Plattenprodukt
gewalzt wird, das eine Dicke von mindestens 12,0 mm, und vorzugsweise mindestens 75
mm hat.
1. Produit corroyé en alliage d'aluminium pour des éléments structurels ayant une composition
chimique constituée de, en pourcentage en poids :
Cu |
3,2 à 4,4 |
Li |
0,8 à 1,4 |
Mg |
0,20 à 0,90 |
Mn |
0,10 à 0,8 |
Zn |
0,20 à 0,80, |
un ou plusieurs éléments sélectionnés parmi le groupe constitué de :
Zr |
0,05 à 0,25, |
Cr |
0,05 à 0,30, |
Ti |
0,01 à 0,25, |
Sc |
0,05 à 0,4, |
Hf |
0,05 à 0,4, |
Ag |
< 0,05 |
Fe |
< 0,15 |
Si |
< 0,15, |
des impuretés inévitables et le reste étant de l'aluminium.
2. Produit corroyé en alliage d'aluminium selon la revendication 1, dans lequel la teneur
en Cu est dans une plage de 3,6 % à 4,4 %, de préférence dans une plage de 3,75 %
à 4,20 %.
3. Produit corroyé en alliage d'aluminium selon la revendication 1 ou 2, dans lequel
la teneur en Li est dans une plage de 0,90 % à 1,4 %, et de préférence dans une plage
de 1,0 % à 1,30 %.
4. Produit corroyé en alliage d'aluminium selon l'une quelconque des revendications 1
à 3, dans lequel le produit contient du Zr dans une plage de 0,05 % à 0,15 %.
5. Produit corroyé en alliage d'aluminium selon l'une quelconque des revendications 1
à 4, dans lequel la teneur en Zn est au maximum 0,70 %, de préférence au maximum 0,65
%.
6. Produit corroyé en alliage d'aluminium selon l'une quelconque des revendications 1
à 5, dans lequel la teneur en Ag est inférieure à 0,02 % et, de façon plus préférée,
le produit en alliage est sensiblement dépourvu de Ag.
7. Produit corroyé en alliage d'aluminium selon l'une quelconque des revendications 1
à 6, dans lequel le produit contient du Mn dans une plage de 0,20 % à 0,6 %, et de
préférence de 0,20 % à 0,55 %.
8. Produit corroyé en alliage d'aluminium selon l'une quelconque des revendications 1
à 7, dans lequel le produit contient du Mg dans une plage de 0,20 % à 0,8 %, et de
préférence de 0,20 % à 0,65 %, et de manière plus préférée de 0,35 % à 0,65 %.
9. Produit corroyé en alliage d'aluminium selon l'une quelconque des revendications 1
à 8, dans lequel le produit est sous la forme d'un produit laminé, extrudé ou forgé.
10. Produit corroyé en alliage d'aluminium selon la revendication 9, dans lequel le produit
corroyé est sous la forme d'un produit extrudé.
11. Produit corroyé en alliage d'aluminium selon l'une quelconque des revendications 1
à 9, dans lequel le produit corroyé est sous la forme d'un produit en plaque ayant
une épaisseur de 12,0 mm à 175 mm, et de préférence au moins 75 mm.
12. Produit corroyé en alliage d'aluminium selon l'une quelconque des revendications 1
à 11, dans lequel le produit est dans une condition de vieillissement T8, et de préférence
dans une condition T84.
13. Procédé de fabrication d'un produit corroyé en alliage d'aluminium selon l'une quelconque
des revendications 1 à 12, comprenant les étapes comprenant à :
a) couler en bloc un lingot d'un alliage AlCuLi selon l'une quelconque des revendications
1 à 8,
b) préchauffer et/ou homogénéiser le bloc coulé ;
c) œuvrer à chaud le bloc par un ou plusieurs procédés sélectionnés parmi le groupe
comprenant le laminage, l'extrusion et le forgeage ;
d) en option œuvrer à froid le bloc œuvré à chaud ;
e) effectuer un traitement en solution à chaud (SHT) du bloc œuvré à chaud et/ou en
option œuvré à froid, le traitement SHT étant mis en œuvre à une température et pendant
un temps suffisant pour mettre en solution solide les constituants solubles dans l'alliage
d'aluminium ;
f) refroidir le bloc traité par SHT ;
g) en option étirer ou comprimer le bloc SHT refroidi, ou œuvrer à froid d'une autre
manière le bloc SHT refroidi pour libérer les contraintes, par exemple en planifiant
ou en étirant ou en laminant à froid le bloc SHT refroidi ; et
h) faire vieillir, de préférence par un vieillissement artificiel, le bloc SHT refroidi
et en option étiré ou comprimé ou œuvré à froid d'une autre manière pour atteindre
une températion désirée.
14. Procédé selon la revendication 13, dans lequel l'homogénéisation est effectuée à une
température dans une plage de 475° C à 535° C.
15. Procédé selon la revendication 13 ou 14, dans lequel le travail à chaud est effectué
par laminage et la température d'entrée du travail à chaud est à une température dans
la plage de 440° C à 490° C.
16. Procédé selon l'une quelconque des revendications 13 à 15, dans lequel le traitement
à chaud en solution est effectué à une température dans une plage de 480° C à 525°
C.
17. Procédé selon l'une quelconque des revendications 13 à 16, dans lequel l'étirage est
effectué dans une plage de 0,5 % à 6 %, et de préférence dans une plage de 0,5 % à
4 %.
18. Procédé selon l'une quelconque des revendications 13 à 17, dans lequel le produit
a été vieilli jusqu'à une condition de vieillissement T8.
19. Procédé selon l'une quelconque des revendications 13 à 18, dans lequel le produit
corroyé est laminé pour donner un produit en plaque ayant une épaisseur d'au moins
12,0 mm, et de préférence d'au moins 75 mm.