Al-Cu-Mg ALLOY SUITABLE FOR AEROSPACE APPLICATION

Abstract

An aluminium alloy wrought product having high strength and high fracture toughness and high resistance to intergranular corrosion. The alloy including in weight %: Cu 4.1-5.5%; Mg 0.30-1.6%; Mn 0.15-0.8%; Ti 0.03-0.4%; Cr 0.05-0.4%; Ag<0.7%; Zr<0.2%; Fe<0.20%, preferably <0.15%, more preferably <0.1%; Si<0.20%, preferably <0.15%, more preferably <0.1%; and the balance being aluminium and other impurities or incidental elements each <0.05%, total <0.15%.

Description

FIELD OF INVENTION

The invention relates to an aluminium wrought alloy, in particular an Al—Cu—Mg type alloy (or AA2000 series aluminium alloy as designated by the Aluminium Association). More specifically, the present invention relates to an aluminium alloy product having high strength, high fracture toughness exhibiting low crack propagation and high resistance to intergranular corrosion. Products made from the aluminium alloy according to the invention are very suitable for aerospace applications but not limited thereto. The alloy can be processed to various product forms such as sheet, thin plate or an extruded product, a forged product, or a welded product. The aluminium alloy product can be uncoated or coated or plated with another aluminium alloy in order to improve desired properties even further.

BACKGROUND OF THE INVENTION

Designers and manufacturers in particular in the aerospace industry are constantly trying to improve fuel efficiency, product performance and constantly trying to reduce manufacturing, maintenance and service costs. One way of achieving these goals is by improving the relevant properties of the used aluminium alloys so that a structure made from a particular alloy can be designed more effectively or will have a better overall performance. By improving the relevant material properties for a particular application, also the service costs can be significantly reduced by longer inspection intervals of the structure such as an aeroplane.

The main application of AA2000 series aluminium alloys in aeroplanes is as fuselage or skin plate, for which purpose typically AA2024 in the T351 temper is used or as lower wing plate for which purpose typically AA2024 in the T351 temper and AA2324 in the T39 temper is used. For these applications high tensile strength and high toughness are required. It is known that these properties of a AA2000 series aluminium alloy can be improved by higher levels of alloying elements such as Cu, Mg and Ag.

However, by increasing the concentration of the mentioned alloying elements, the resistance to corrosion, in particular also to intergranular corrosion is decreased to levels which could limit the applicability of the alloy.

Intergranular corrosion of an aluminium alloy not only affects the integrity of the structure for which it is used, in which may corroded grain boundaries may act as a nucleus for cracks which propagate under the influence of the alternating load during operation of the structure. Therefore, the occurrence of intergranular corrosion sets limits to the use of aluminium alloys of the AA2000 series with high levels of the mentioned alloying elements.

The most commonly used aluminium alloys form the AA2000 series for aerospace application are AA2024, AA2024HDT (“High Damage Tolerant”) and AA2324.

For newly designed aeroplanes, there is a wish for even better properties of the aluminium alloys than the known alloys have in order to design aeroplanes which are more manufacturing and operationally cost effective. Accordingly, a need exists for an aluminium alloy capable of achieving an improved balance of properties of the aluminium alloy in the relevant form.

SUMMARY OF THE INVENTION

The present invention is directed to a AA2000 series aluminium alloy having the capability of achieving a balance of properties in any relevant product made of the alloy that is better than the balance of properties of the variety of commercially available aluminium alloys of the AA2000 series, nowadays used for such a product or of AA2000 series aluminium alloys disclosed so far.

One object of the present invention is to provide an aluminium alloy wrought product, in particular suitable for aerospace application within the AA2000 series alloys having an improved balance of high strength and fracture toughness and high resistance to intergranular corrosion.

Another object of the present invention is to provide an aluminium alloy wrought product as referred to above which shows a high resistance to exfoliation corrosion and stress corrosion cracking.

A further object of the present invention is to provide an aluminium alloy wrought product as referred to above which is tolerant to the usual variation in process parameters during its manufacturing process.

Yet another object of the present invention is to provide an aluminium alloy wrought product as referred to above which is weldable and suitable for use in welded constructions.

Yet another object of the present invention is to provide an aluminium wrought product as referred to above in a form which is suitable for use in an aerospace structure.

A further object of the present invention is to provide a method of manufacturing an aluminium alloy wrought product as mentioned hereinabove.

One or more of the objects and other objects and advantages are obtained with an aluminium alloy wrought product having high strength and high fracture toughness and high resistance to intergranular corrosion, the aluminium alloy comprising in weight %:

Cu 4.1-5.5%
Mg 0.30-1.6%
Mn 0.15-0.8%
Ti 0.03-0.4%
Cr 0.05-0.4%
Ag <0.7%
Zr <0.2%
Fe <0.20%, preferably <0.15%, more preferably <0.1%
Si <0.20%, preferably <0.15%, more preferably <0.1%,

and the balance being aluminium and other impurities or incidental elements each <0.05%, total <0.15%.

Unless stated otherwise herein all percentages are by weight percent (wt. %).

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 shows a Cr—Ti diagram setting out the Cr—Ti range for the invention together with narrower preferred ranges.

FIGS. 2 a, 2b show micrographs of a cross section of a sample of an alloy according to the invention in T3 temper and of a comparative alloy after corrosion testing.

FIGS. 3 a, 3b show micrographs of a cross section of sample of an alloy according to the invention in T6 temper and of a comparative alloy after corrosion testing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides an aluminium alloy wrought product having high strength and high fracture toughness and high resistance to intergranular corrosion, the aluminium alloy comprising in weight %:

Cu 4.1-5.5%
Mg 0.30-1.6%
Mn 0.15-0.8%
Ti 0.03-0.4%
Cr 0.05-0.4%
Ag <0.7%
Zr <0.2%
Fe <0.20%, preferably <0.15%, more preferably <0.1%
Si <0.20%, preferably <0.15% more preferably <0.1%,

and the balance being aluminium and other impurities or incidental elements each <0.05%, total <0.15%.

Unless stated otherwise herein all percentages are by weight percent (wt. %).

It was found that the composition of the aluminium alloy according to our invention leads to an alloy product having a high resistance to intergranular corrosion while maintaining a higher strength and higher toughness as compared to the conventional AA2024 alloy, The alloy product of the invention also exhibits a high resistance to exfoliation corrosion and stress corrosion cracking.

Good results are also obtained in a preferred embodiment of the invention wherein 0.03%<Ti<0.3%, preferably 0.05%<Ti<0.2%. According to this embodiment good properties can also be achieved with a lower concentration of Ti.

Another embodiment has the range wherein 0.05%<Cr<0.3%, preferably 0.05%<Cr<0.15%. In this embodiment in particular good intergranular corrosion properties are maintained while at the same time the alloy product is less quench sensitive.

A further embodiment has the range wherein 0.1%<Ti+Cr<0.4%. It has been found that within the given range Ti and Cr can be substituted by each other while maintaining good resistance against intergranular corrosion and good mechanical properties.

Preferably 0.1%<Ti+Cr<0.3%. In this embodiment of the invention, still good properties are achieved with reduced addition of the alloying elements Ti and Cr.

In a preferred embodiment the Cu level is selected in the range wherein 4.4%<Cu<5.5%, more preferably 4.7%<Cu<5.3%.

In a further preferred embodiment the Mg level is selected in the range wherein 0.3%<Mg<1.2%, more preferably 0.4%<Mg<0.75%.

Iron can be present in the range of up to 0.20% and preferably is kept to a maximum of 0.15%, more preferably to a maximum of 0.1%. A typical preferred iron level would be in the range of 0.03% to 0.08%.

Silicon can be present in a range of up to 0.20% and preferably is kept to a maximum of 0.15%, more preferably to a maximum of 0.1%. A typical preferred silicon level would be as low as possible and would typically be for practical reasons in a range of 0.02% to 0.07%.

Zirconium can be present in the alloy product according to the invention in an amount of up to 0.20%. A suitable Zr level is a range of 0.04% to 0.15%. A more preferred upper limit for the Zr level is 0.13%, and even more preferably not more than 0.11%.

Manganese can be added alone or in combination with other dispersoid formers. A preferred maximum for the Mn level is 0.80% and a preferred minimum level is 0.15%. A preferred range for the Mn level is in the range of wherein 0.2%<Mn<0.5%.

In the prior art, it has been proposed to add Ag to an AA2000 alloy to improve the resistance against intergranular corrosion. However, there are drawbacks associated with the addition of Ag. One drawback is that Ag is an expensive element and its addition raises the price of the alloy. A second drawback is that also in relation to the price of Ag, any scrap of the alloy should be carefully handled and recycled to reclaim the Ag.

Therefore, in another preferred embodiment of the aluminium alloy product according to the invention, the alloy is free of Ag. In practical terms this would mean that Ag is present at the level of an impurity or incidental element, so at a level of <0.05%. More preferably the alloy is substantially free of Ag. With “substantially free” is meant that no purposeful addition of Ag 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 aluminium alloy product.

In a preferred embodiment of the aluminium alloy product according to the invention, the alloy has a composition consisting of, in wt. %:

Cu 4.1-5.5%
Mg 0.30-1.6%
Mn 0.15-0.8%
Ti 0.03-0.4%
Cr 0.05-0.4%
Zr <0.2%
Fe <0.15%, preferably <0.1%
Si <0.15%, preferably <0.1%,

and the balance being aluminium and other impurities or incidental elements each <0.05%, total <0.15%, and is substantially free of Ag.

More preferred narrower ranges for the various alloying elements are set out in this specification and claims.

Preferably, the aluminium alloy product according to the invention is in the T3x, T6x or T8x temper. Dependent on the intended field of application of the alloy the appropriate temper is selected to give the alloy product desired properties. Temper designations are according to the Aluminium Association.

Because of the improved resistance to intergranular corrosion, at high strength and fatigue levels, the product is preferably provided in the form of a sheet, plate, forging or extrusion for use in an aerospace structure.

The aluminium alloy product according to the invention shows an excellent balance of properties for application as plate over a wide variety of thickness, preferably in the form of a plate having a thickness in the range of 0.7 to 80 mm. In the plate thickness range of 0.6 to 1.5 mm the aluminium alloy product is also of particular interest as automotive body sheet.

In the thickness range of up to 40 mm the properties of the aluminium alloy product will be excellent for fuselage sheet and preferably the thickness is up to 25 mm.

In the thickness range of 20 to 80 mm, the properties are excellent for wing plates, e.g. lower wing plate, when tensile strength and fatigue properties are of great importance. In this thickness range, the aluminium alloy products can also be used for stringers or to form an integral wing panel and stringer for use in an aircraft wing structure.

The aluminium alloy product according to the invention can also be used as tooling plate or mould plate, e.g. for moulds for manufacturing formed plastic products for example via die-casting or injection moulding. In this application higher Fe and Si levels up to 0.4% for each of these elements are acceptable.

The invention is also embodied in a method for the manufacture of an aluminium alloy product having high strength and high fracture toughness and a high resistance to intergranular corrosion comprising the steps of:

a. casting an ingot having a composition according to the invention;

b. homogenising and/or pre-heating the ingot after casting;

c. hot working the ingot into a pre-worked product by one of more methods selected from the group consisting of rolling, extruding and forging;

d. optional reheating the pre-worked product and either

e. hot working and/or cold working to a desired work piece form;

f. solution heat treating said formed work piece at a temperature and time sufficient to place into solid solutions substantially all soluble constituents in the alloy;

g. quenching the solution heat treated work piece by one of spray quenching or immersion quenching in water or other quenching media;

h. optionally stretching or compressing of the quenched work piece;

i. naturally or artificially ageing the quenched and optional stretched or compressed work piece to achieve a desired temper.

The method according to the invention yields aluminium alloy product having excellent resistance to intergranular corrosion and having high strength and excellent fatigue properties.

The alloy products of the present invention are conventionally prepared by melting and alloying an aluminium alloy product and may be direct chill (“D.C.”) cast into ingots or other suitable casting techniques. Homogenisation treatment is typically carried out in one or more steps, each step having a temperature preferably in the range of 460° C. to 535° C. The pre-heat temperature involves heating the ingot to the hot working temperature which is typically in a temperature range of 400° C. to 480° C. Working the alloy product can be done by one or more methods selected from the group consisting of rolling, extruding and forging. For the present alloy product hot rolling is preferred. Solution heat treatment is typically carried out in the same temperature range as used for homogenisation although somewhat shorter soaking times can be selected.

In an embodiment of the method according to the invention, artificial ageing preferably comprises an ageing step at a temperature in the range of 135° C. to 210° C., preferably for 5 to 20 hours.

In another embodiment of the invention the natural ageing preferably comprises a step of ageing at room temperature during 1 to 10 days.

Preferably, the aluminium alloy product is aged to a temper selected from the group comprising T3, T351, T39, T6, T651, and T87.

In one embodiment the aluminium alloy product is processed to fuselage sheet, preferably to fuselage sheet having a thickness of less then 30 mm.

In another embodiment the aluminium alloy product is processed to lower wing plate.

In a further embodiment the aluminium alloy product is processed to upper wing plate.

In still a further embodiment the aluminium alloy product is processed to an extruded product.

In yet a further embodiment the aluminium alloy product is processed to a forged product.

In yet another embodiment the aluminium alloy product is processed to a thin plate having a thickness in the range of 15 to 40 mm.

In still another embodiment the aluminium alloy product is processed to a thick plate having a thickness up to 300 mm.

EXAMPLES

In the following, the invention will be further illustrated with reference to the drawings and the results of laboratory testing.

FIG. 1 shows a Cr—Ti diagram setting out the Cr—Ti range for the invention together with narrower preferred ranges.

FIG. 1 shows schematically the ranges for the Cr and Ti content for the alloy according to the invention. The broadest range is identified by a rectangular box with angular points A, B, C, D.

FIG. 1 also shows schematically a preferred range of a balanced content of both Cr and Ti. The broadest range thereof is identified by a quadrangular box with angular points E, F, G, H.

The point P indicates the Cr and Ti content of a sample of an alloy according to the invention which was used for testing (also referred to as alloy 3 in the following examples).

The letter Q indicates the Cr and Ti content of two comparative alloys, also used for testing and also referred to as alloys 1 and 2. Alloys 1 and 2 fall outside the invention.

Alloy 2 has, with the exception of the Cr and Ti content, the same chemical composition as Alloy 3 according to the invention. Alloy 1 has a chemical composition typical for a conventional AA2024 alloy.

On a laboratory scale, three ingots were cast and processed to a plate to prove the principle of the current invention. The alloy compositions of the three alloys are listed in Table 1.

TABLE 1
Composition of the alloys (wt. %), balance
aluminium and inevitable impurities
Alloy	Cu	Mg	Mn	Ti	Zr	Zn	Fe	Si	Cr
1	4.5	1.5	0.6	0.03	<0.01	0.03	<0.06	<0.04	—
(Ref.
AA2024)
2	5.1	0.58	0.30	0.03	0.14	0.08	<0.06	<0.04	—
3	5.1	0.58	0.30	0.1	<0.01	0.08	<0.06	<0.04	0.15
(Inv.
Alloy)

The alloys listed in Table 1 were processed as follows:

• • Casting an ingot,
  • For Alloy 1: homogenising the ingot at a heating rate of 30° C./h to 465° C., soaking at that temperature for 2 hours followed by further heating at a rate of 15° C./h to 495° C. and soaking at that temperature for 24 hours followed by air cooling to room temperature.
  • For Alloys 2 and 3; homogenising the ingot at a heating rate of 30° C./h to 525° C., soaking at that temperature for 24 hours, followed by air cooling to room temperature.
  • Pre-heating to 420° C.
  • Hot rolling from 80 mm to 8 mm.
  • Cold rolling from 8 mm to 2 mm to a cold rolled plate.
  • Solution heat treating of the cold rolled plate
    • For alloy 1 at 495° C. for 30 min.
    • For alloys 2 and 3 at 525° C. for 30 min.
  • Quenching the cold rolled plate by either direct water quenching or quenching in water after holding 10 sec. in still air.
  • Storing the cold rolled plate for 4 hours at room temperature.
  • Stretching and ageing the cold rolled plate by either:
    • Stretching and natural ageing for 5 days at room temperature to T3x tempers (viz. T3, T351, and T39); or
    • Stretching and artificial ageing for 12 hours at 175° C. to T6x and T8x tempers (viz. T6, T651, T87).

Samples taken from the cold rolled plates processed as described above, were subjected to an intergranular corrosion test according to ASTM G110.

The results of the corrosion test are shown in Tables 2, 3, 4 and 5.

In the tables (i) indicates only pitting corrosion and no intergranular corrosion was observed, (ii) indicates pitting corrosion with slight intergranular corrosion at the bottom of the pit was observed, and (iii) indicates that local intergranular corrosion was observed.

TABLE 2
Maximum corrosion depth and type of the alloys in T3x temper
	Alloy	T3	T351	T39
	1 (Ref. AA2024)	151 (i)	172 (iii)	118 (ii)
	2	186 (i)	319 (iii)	127 (ii)
	3	60 (i)	121 (i)	71 (i)

Table 2 shows that a balanced addition of Cr and Ti according to an embodiment of the invention gives rise to outstanding intergranular corrosion free properties in the T3x tempers with a markedly lower pit depth compared with the other alloys.

TABLE 3
Maximum corrosion depth and type of the alloys in the T3x temper
with a quench delay of 10 seconds after solution heat treatment
	Alloy	T3	T351	T39
	1 (Ref. AA2024)	188 (ii)	181 (iii)	257 (iii)
	2	151 (i)	137 (ii)	311 (iii)
	3	101 (i)	90 (i)	56 (i)

This table shows that also after a quench delay of up to 10 s the outstanding corrosion properties are maintained with the alloy according to the invention.

TABLE 4
Maximum corrosion depth and type of the alloys
in the T6x temper and T8x temper
	Alloy	T6	T651	T87
	1 (Ref. AA2024)	220 (iii)	203 (iii)	151 (iii)
	2	263 (iii)	223 (iii)	188 (iii)
	3	159 (ii)	124 (ii)	99 (ii)

As can be seen from this table, improved corrosion properties are achieved by the balanced addition of Cr and Ti. Only pitting with a very slight intergranular corrosion at the bottom of the pit was found.

TABLE 5
Maximum corrosion depth and type of the alloys in
the T6x and T8x temper with a quench delay
of 10 sec. after solution heat treatment
	Alloy	T6	T651	T87
	1 (Ref. AA2024)	216 (iii)	257 (iii)	235 (iii)
	2	218 (iii)	276 (iii)	165 (iii)
	3	175 (ii)	180 (ii)	147 (ii)

For long quench delays of up to 10 sec. the intergranular corrosion resistance decreases slightly, but the performance is still notably superior to the performance of the comparative alloys, with or without quench delay.

The results of the corrosion test are also shown in FIGS. 2a, 2b, 3a and 3b.

FIGS. 2 a, 2b show micrographs of a cross section of a sample of an alloy according to the invention in T3 temper and of a comparative alloy after corrosion testing.

In particular, FIG. 2a shows a micrograph of a cross section of a sample of comparative alloy 1 (Ref. AA2024) in T3 temper after corrosion testing. The micrograph clearly shows pitting corrosion and intergranular corrosion to a depth of more than 150 μm.

FIG. 2 b shows a micrograph of a cross section of a sample of an alloy according to the invention (alloy 3) also in T3 temper after corrosion testing. The samples show only slight pitting, with a maximum depth of 60 μm and no intergranular corrosion.

FIGS. 3 a, 3b show micrographs of a cross section of sample of an alloy according to the invention in T6 temper and of a comparative alloy after corrosion testing.

In particular, FIG. 3a shows a micrograph of a cross section of a sample of a comparative alloy 1 (Ref. AA2024) in T6 temper after corrosion testing. The micrograph clearly shows local intergranular corrosion, extending to a depth of about 220 μm.

FIG. 3 b shows a micrograph of a cross section of a sample of an alloy according to the invention (alloy 3) also in T6 temper after corrosion testing. The sample exhibits pitting with only slight intergranular corrosion to a depth of less than 160 μm.

In both tempers, T3 and T6, the corrosion performance of the alloy according to the invention is considerably better than the corrosion performance of the comparative alloy Ref. AA2024.

Mechanical properties of the alloys, cast and processed as described above, were also measured and the results have been collected in Tables 6 and 7.

TABLE 6
Tensile properties (L direction) of the alloys in T3 temper
		Rp	Rm	A
	Alloy	(MPa)	(MPa)	(%)
	1 (Ref. AA2024)	344	465	17.7
	2	328	441	21.7
	3	334	466	22.6

From Table 6 it can be seen that in the T3 temper, comparable mechanical properties can be achieved with an alloy according to the invention as for reference alloys 1 (Ref. AA2024) and 2.

TABLE 7
Fracture toughness (L-T direction) of the alloys in T3 temper
		UPE
	Alloy	(kJm−2)	TS/Rp
	1 (Ref. AA2024)	276	1.68
	2	518	1.98
	3	410	2.00

From Table 7 it can be seen that significantly higher toughness is maintained with an alloy of the present invention as compared to comparative alloy AA2024.

Although the present invention has been described with reference to some specific examples, one skilled in the art shall certainly be able to achieve many other embodiments within the spirit and scope of the invention. Thus, the invention is not limited by the above-listed embodiments, but rather is defined by the claims appended hereto.

Claims

1. An aluminium alloy wrought product having high strength and high fracture toughness and high resistance to intergranular corrosion, said aluminium alloy wrought product made of an alloy comprising in weight %:

2. The aluminium alloy product according to claim 1, wherein Fe<0.15%.

3. The aluminium alloy product according to claim 1, wherein Fe<0.1%.

4. The aluminium alloy product according to claim 1, wherein Si<0.15%.

5. The aluminium alloy product according to claim 1, wherein Si<0.1%.

6. The aluminium alloy product according to claim 1, wherein 0.03%<Ti<0.3%.

7. The aluminium alloy product according to claim 1, wherein 0.05%<Ti<0.2%.

8. The aluminium alloy product according to claim 1, wherein 0.05%<Cr<0.3%.

9. The aluminium alloy product according to claim 1, wherein 0.05%<Cr<0.15%.

10. The aluminium alloy product according to claim 1, wherein 0.1%<Ti+Cr<0.4%.

11. The aluminium alloy product according to claim 1, wherein 0.1%<Ti+Cr<0.3%.

12. The aluminium alloy product according to claim 1, wherein 4.4%<Cu<5.5%.

13. The aluminium alloy product according to claim 1, wherein 4.7%<Cu<5.3%.

14. The aluminium alloy product according to claim 1, wherein 0.3%<Mg<1.2%.

15. The aluminium alloy product according to claim 1, wherein 0.4%<Mg<0.75%.

16. The aluminium alloy product according to claim 1, wherein 0.2%<Mn<0.5%.

17. The aluminium alloy product according to claim 1, wherein Ag is present at the level of an impurity or incidental element.

18. The aluminium alloy product according to claim 17, which is substantially free of Ag.

19. The aluminium alloy product according to claim 1, wherein the product is in the T3x, T6x or T8x temper.

20. The aluminium alloy product according to claim 1, wherein the product is in the form of a sheet, plate, forging or extrusion for use in an aerospace structure.

21. The aluminium alloy product according to claim 1, wherein the product is in the form of a plate having a thickness in the range of 0.7 to 80 mm.

22. A method for the manufacture of an aluminium alloy product having high strength and high fracture toughness and a high resistance to intergranular corrosion comprising the steps of: a. casting an ingot having a composition of the alloy according to claim 1;b. homogenising and/or pre-heating the ingot after casting; c. hot working the ingot into a pre-worked product by one of more methods selected from the group consisting of rolling, extruding and forging; d. optionally reheating the pre-worked product and either e. hot working and/or cold working to a desired work piece form; f. solution heat treating said formed work piece at a temperature and time sufficient to place into solid solutions substantially all soluble constituents in the alloy; g. quenching the solution heat treated work piece by one of spray quenching or immersion quenching in water or other quenching media; h. optionally stretching or compressing of the quenched work piece; i. naturally or artificially ageing the quenched and optional stretched or compressed work piece to achieve a desired temper.

23. The method of manufacturing according to claim 22, wherein the aluminium alloy product is aged to a temper selected from the group comprising T3, T351, T39, T6, T651 and T87.

24. The method of manufacturing according to claim 22, wherein the aluminium alloy product is processed to fuselage sheet.

25. The method of manufacturing according to claim 22, wherein the aluminium alloy product is processed to fuselage sheet having a thickness of less then 30 mm.

26. The method of manufacturing according to claim 22, wherein the aluminium alloy product is processed to lower wing plate.

27. The method of manufacturing according to claim 22, wherein the aluminium alloy product is processed to upper wing plate.

28. The method of manufacturing according to claim 22, wherein the aluminium alloy product is processed to an extruded product.

29. The method of manufacturing according to claim 22, wherein the aluminium alloy product is processed to a forged product.

30. The method of manufacturing according to claim 22, wherein the aluminium alloy product is processed to a thin plate having a thickness in the range of 15 to 40 mm.

31. The method of manufacturing according to claim 22, wherein the aluminium alloy product is processed to a thick plate having a thickness of at most 300 mm.

32. The method of manufacturing according to claim 22, comprising said reheating the pre-worked product.

33. The method of manufacturing according to claim 22, comprising said hot working and/or cold working to the desired work piece form.