ES2323902T3 - ALUMINUM-COPPER-LITHIUM HIGH TENACITY PLATE FOR AIRPLANE FUSELAGE - Google Patents

Abstract

An aluminum alloy contains (by wt.%): (A) 2.1 to 2.8 of copper; (B) 1.1 to 1.7 of lithium; (C) 0.1 to 0.8 of silver; (D) 0.2 to 0.6 of magnesium; (E) 0.2 to 0.6 of manganese; (F) a quantity of iron and silicon = to 0.1; (G) inevitable impurities of = 0.05 each and 0.15 in total; (H) the alloy is essential exempt of zirconium, this being less than 0.04. Independent claims are also included for: (1) a rolled, extruded or forged product of this alloy; (2) the fabrication of a sheet of this alloy; (3) the rolled sheet thus obtained; (4) an aircraft fuselage panel incorporating the sheet; (5) a structural element for aeronautical construction.

Description

Sheet metal aluminum-copper-lithium high tenacity for airplane fuselage.

Field of the invention

The present invention generally relates to aluminum alloy products and more particularly to such products, their manufacturing procedures and of use, in particular in the aerospace industry.

State of the art

A continuous research effort is made  to develop materials that can reduce weight and increase the efficiency of high aircraft structures benefits. Aluminum-lithium alloys (AlLi) they are very interesting about it because lithium can reduce the 3% aluminum density and increase the modulus of elasticity 6% per weight percent of added lithium. But nevertheless AlLi alloys are not yet used intensively in the aerospace industry due to alloy defects developed until today, such as thermal stability inadequate, a great anisotropy and an inadequate tenacity for example.

The history of alloy development AlLi is described for example in the chapter "Alloys aluminum-lithium ": from the work" Aluminum and Aluminum Alloys ", (ASM Specialty Handbook, 1994). The first aluminum-lithium alloys (Al-Zn-Cu-Li) is introduced in Germany in the 20s, then it introduced AA2020 alloy (Al-Cu-Li-Mn-Cd) in the late 50s and then, in the mid 60s, it introduced 1420 alloy (Al-Mg-Li) in the Soviet Union. The only industrial applications of the AA2020 alloy were the wings and horizontal stabilizers of RA5C aircraft Vigilant. The classic composition of the AA2020 alloy was (in weight percentage): Cu: 4.5, Li: 1.2, Mn: 0.5, Cd: 0.2. Between the Reasons why this alloy has limited applications, it You can underline its low tenacity. Apart from the specific function of the Cd, one of the reasons why it has properties Limited was attributed to the use of Mn in this alloy. In 1982 E.A. Starke stated (in "Metallurgical Transactions A.", Vol. 13A, p.2267): "The largest dispersoids rich in Mn they can also be harmful to ductility because they cause porosities. "This idea of a disastrous effect of Mn was widely recognized by the specialist. For example, in 1991, Blackenship declared (in "Proceedings of the Sixth International Aluminum-Lithium Conference ", Garmisch-Partenkirchen, p.190), "The dispersoids rich in manganese create porosities and thus favor the process of fracture. "It was suggested that zirconium be used instead of manganese as a granular structure control agent. At same document Blackenship declares: "Zirconium is an element of quality for the control of the granular structure in the Al-Li-X alloys ".

They continued to develop AlLi alloys in the 80s which led to the introduction of alloys AA8090, AA2090 and AA2091. All these alloys They contained zirconium instead of manganese.

In the early 90s a new range of AlLi alloys containing silver, known by the name "Weldalite®". These alloys used to contain less Li and presented better thermal stability. US Patent No. 5 032 359 (Pickens, Martin Marietta) describes alloys that contain between 2.0 and 9.8% by weight of an element of alloy comprising Cu, Mg and mixtures thereof, between 0.01 and 2.0% by weight of Ag, 0.2 and 4.1% by weight of Li and 0.05 and 1.0 percent by weight of a grain refining additive selected from Zr, Cr, Mn, Ti, B, Hf, V, TiB2 and mixtures of these. Note that in fact the list of refining additives proposed by Pickens mix elements used for refining foundry grain (such as TiB_ {2}) and elements used for the control of grain structure during operations of transformation, such as zirconium. Although Pickens indicate that "although we must concentrate here on the use Zirconium for grain refining, tuners can be used conventional grain such as Cr, Mn, Ti, B, el Hf, V, TiB_ {2} and mixtures thereof ", clearly appears at from the history of the development of AlLi alloys that there is a prejudice for the specialist regarding the use of any element other than Zr for the control of granular structure This is how Zr is used in all examples described by Pickens. Similarly, in a developed alloy more recently (AA2050, see also WO2004 / 106570), it find the use of zirconium for grain refining, where the addition of manganese allows to improve the toughness.

WO2004 / 106570 A1 discloses the alloy, in weight percentage: Cu: 2.5-5.5%, Li: 0.1-2.5%, Mg: 0.2-1%, Ag: 0.2-0.8%, Mn: 0.2-0.8%, Zr: up to  0.3%, Al remainder and inevitable impurities.

You can also mention the AA2297 alloy containing lithium, copper and manganese, optionally magnesium but not silver, and for which zirconium is also used for the grain refining. US 5 234 662 discloses a preferred composition of 1.6% by weight of Li, 3% by weight of Cu, 0.3% by weight of Mn and 0.12% by weight of Zr.

AA2050 and AA2297 alloys were proposed mainly for thick plates, of a thickness greater than 0.5 inch (12.7 mm).

Another range of AlLi alloys containing Zn are described in US Patent No. 4,961,792 and US Patent No. 5,066 342 for example, and it was developed in the early 1990s. The metallurgy of these alloys cannot be compared with the metallurgy of "Weldalite®" alloys because the addition of a significant amount of zinc, and in particular the combination of zinc and magnesium, completely modifies the properties of the alloy, for example in terms of mechanical strength and corrosion resistance

With a view to using AlLi alloys for fuselage applications, the alloys have to offer equal performance, even better performance in terms of mechanical strength, damage tolerance, than currently used alloys that do not contain Li. In particular, resistance to crack propagation is an important issue in the context of these applications and this explains why alloys recognized for their high tolerance to damage such as AA2524 and AA2056 are traditionally used. Among the other desirable properties, weldability and corrosion resistance can be stressed. Due to the increasing tendency of reduction of expensive mechanical fixing operations in the aerospace industry, weldable alloys such as AA6013, AA6056 or AA6156 are introduced for the fuselage panels. High corrosion resistance is also desirable to replace plated products with cheaper bare products. Among the problems related to known AlLi alloys, the anisotropy of the elasticity limit was mentioned above, which in turn determines the anisotropy of the other mechanical properties. The low elasticity limit in the intermediate test directions, such as at 45 ° with respect to the rolling direction, is the most obvious manifestation of the
anisotropy

As regards the properties of the damage tolerance, the R curve test is a means widely recognized to characterize the properties of tenacity. The R curve represents the evolution of the Critical effective voltage intensity for the propagation of crack according to the extent of effective crack under a increasing monotonous tension. Allows load determination Critical for an unstable break for any configuration adapted to fissured aircraft structures. The values of voltage intensity factor and crack extension are effective values as defined in ASTM E561. He classical analysis, which is usually used, of the tests performed in panels that have a central crack, it provides a factor of apparent breaking voltage intensity (K_ {app}). This value does not necessarily vary significantly according to the length of the R curve. However the length of the R curve, to know the maximum crack extension of the curve, is a parameter important in itself for the fuselage design, particularly for panels comprising fixed reinforcements.

There is a need for alloy High strength Al-Cu-Li mechanical, that does not present any anisotropy, with a high toughness and in particular a high crack extension before a unstable rupture, high corrosion resistance, a small density (i.e. less than about 2.70 g / cm3), for aeronautical applications and in particular sheet metal applications of fuselage.

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Object of the invention

A first object of the invention is an alloy Aluminum based comprising between 2.1 and 2.8% by weight of Cu, 1.1 and 1.7% by weight of Li, 0.1 and 0.8% by weight of Ag, 0.2 and 0.6% by weight of Mg, 0.2 and 0.6% by weight of Mn, a amount of Fe and Si less than or equal to 0.1% by weight each, Al balance and unavoidable impurities in a lower proportion or equal to 0.05% by weight each and 0.15% by weight in total, the alloy being substantially free of zirconium, which means that the proportion of zirconium is less than 0.04% in weight.

Another object of the invention is a process. of manufacturing an aluminum alloy sheet that presents high strength and toughness, in which:

(a) A plate is cast which comprises between a 2.1 and 2.8% by weight of Cu, 1.1 and 1.7% by weight of Li, a 0.1 and 0.8% by weight of Ag, 0.2 and 0.6% by weight of Mg, 0.2 and 0.6% by weight of Mn, a lower amount of Fe and Si or equal to 0.1% by weight each, balance Al and inevitable impurities in a proportion less than or equal to 0.05% by weight each and 0.15% by weight in total, the alloy being substantially free of zirconium, which means that the Zirconium ratio is less than 0.04% by weight,

(b) the corresponding plate is homogenized between 480 and 520ºC for 5 to 60 hours,

(c) hot rolled and optionally in  cold the corresponding plate on a sheet, with a temperature initial rolling of 450 to 490 ° C,

(d) the corresponding sheet is dissolved between 480 and 520 ° C for 15 minutes to 4 hours,

(e) the corresponding plate is tempered,

(f) the corresponding sheet with a permanent deformation of between 1 and 5%,

(g) a tempering of the corresponding  sheet by heating between 140 and 170ºC for 5 to 80 hours.

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Another object of the invention is a product laminated, extruded or forged comprising an alloy according to the invention.

Another object of the invention is an element of structure intended for aeronautical construction comprising a product according to the invention.

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Description of the figures

Figures 1 to 5 refer to certain aspects  of the invention described herein. These are illustrative and of No limiting ways.

Figure 1: R curve in the direction T-L (CCT760 test tube)

Figure 2: R curve in the direction L-T (CCT760 test tube)

Figure 3: Evolution of the speed of cracking in the T-L direction when the amplitude of the voltage intensity factor.

Figure 4: Evolution of the speed of cracking in the L-T direction when the amplitude of the voltage intensity factor.

Figure 5: Relative evolution of R_ {p0.2} according the orientation with respect to the rolling direction.

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Description of the invention a) Definitions

Unless otherwise indicated all indications that refer to the chemical composition of Alloys are expressed as a weight percentage based on weight total alloy. The designation of the alloys is made in accordance with known The Aluminum Association regulations by the specialist The definitions of metallurgical states are indicated in European standard EN 515.

Unless otherwise indicated the characteristics static mechanics, in other words breaking resistance last R_ {m}, the tensile yield limit R_ {p0,2} and The elongation at break A is determined by a test of traction according to EN 10002-1, defining the place where the pieces are removed and their meaning through the norm EN 485-1

Cracking speed (using the test  da / dN - ΔK) is determined according to ASTM E 647.

A curve is determined that provides the effective voltage intensity factor according to the effective crack extension, known as the R curve, according to ASTM E 561. The critical voltage intensity factor K_ {c}, in other terms The intensity factor that causes the crack to be unstable is calculated from the R curve. The voltage intensity factor K_ {co} is also calculated by attributing the initial crack length at the beginning of the load to the critical load monotonous Both values are calculated for a specimen as required. K_ {app} represents the K_ {co} factor that corresponds to the test tube used to perform the R curve test. K_ {eff} represents the K_ {c} factor that corresponds to the test tube used to perform the R curve test. Δ_ {eff (max)} represents the crack extension of the last point of the R curve, valid according to ASTM E561. The last point is obtained when the sudden rupture of the specimen occurs, possibly when the tension in the uncracked ligament on average exceeds the limit of elasticity of the material. Unless otherwise indicated, the crack size at the end of the fatigue pre-curing stage is W / 3 for type M (T) specimens, where W is the width of the specimen as defined in the standard
ASTM E561.

Note that the width of the specimen used in a tenacity test may have an influence substantial on the R curve measured in the test. Being the plates fuselage large panels, the toughness results obtained in sufficiently wide samples, such as samples that have a width greater than or equal to 400 mm, they are the only ones considered significant for the evaluation of tenacity. By this reason is that only CCT760 test samples were used, which had a width of 760 mm, for the evaluation of the tenacity. The initial crack length is 2ao = 253 mm.

Here it is called "structure element" or "structural element" of a mechanical construction one piece mechanics whose failures are likely to jeopardize the security of the corresponding construction, of its users or of others.

For an airplane these structure elements they include in particular the elements that make up the fuselage (such as fuselage skin) fuselage reinforcements or stringers, partitions watertight (bulkheads), circular fuselages (circumferential frames), wings (such as wing skin), reinforcements (stringers or stiffeners), ribs (ribs) and spars, as well as floor profiles (floor beams), the seat tracks and the doors.

When talking about "sheet metal" it is done reference here to a rolled product not exceeding 12.7 mm or 0.5 inch thick

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b) Detailed description of the invention

Advantageously the alloy aluminum-copper-lithium-silver-magnesium-manganese  according to an embodiment of the invention it has the following composition:

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TABLE 1 Alloy composition ranges according to the invention (% by weight, the rest being Al)

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the alloy being substantially free of zirconium. When talking about "noticeably exempt from zirconium "it must be understood that the proportion of zirconium has if it is less than 0.04% by weight, preferably less than a 0.03% by weight, and even more preferably less than 0.01% in weight.

Unexpectedly the inventors discovered  that the small proportion of zirconium allowed to improve the toughness of the alloys Al-Cu-Li-Ag-Mg-Mn; in particular the length of the curve R increases so significant. The use of manganese instead of zirconium for controlling the granular structure has different advantages additional such as obtaining a structure recrystallized and with isotropic properties for a thickness located between 0.8 and 12.7 mm or between 1/32 and 1/2 inch.

Iron and silicon usually damage the tenacity properties. The amount of iron has to be limited at 0.1% by weight (preferably 0.05% by weight) and the amount of silicon has to be limited to 0.1% by weight (preferably 0.05% by weight). The inevitable impurities they must be limited to 0.05% by weight each and to 0.15% in total weight If the alloy does not comprise another element of In addition, the rest consists of aluminum.

The inventors discovered that if the proportion  Copper is greater than 2.8%, or 2.6%, or even 2.5% by weight, in certain cases the toughness properties may decrease quickly while, if the proportion of copper is less than 2.1%, or 2.2%, or even 2.3% by weight, the resistance Mechanical is too small.

As regards the proportion of lithium, a proportion of lithium greater than 1.7%, or 1.6%, even at 1.5% by weight causes thermal stability problems. A proportion of lithium less than 1.1%, or 1.2%, even at a 1.3% by weight causes inadequate mechanical resistance and lower gain in terms of density.

The inventors discovered that if the proportion  of silver is less than 0.1%, or 0.2% by weight, the Mechanical resistance obtained does not meet the desired properties. However the proportion of silver has to be kept below 0.8%, or 0.6%, or even 0.4% by weight as a large amount of silver increases the density of the alloy and so Same cost.

The alloy according to the invention can be used to manufacture extruded, forged or laminated products. Advantageously the alloy according to the invention is used for make plates.

The products according to the invention have a Very high toughness. The inventors suspect that perhaps the absence of zirconium in the products according to the invention may be related to the results of tenacity. Zr and Mn, what both can be used to control the granular structure, They have a very different behavior. During solidification, Zr being a peritectic element, it is usually enriched in the center of the grain and impoverish in the limits of the grain, while Mn, which is an eutectic element that has a distribution coefficient of  approximately one, is distributed much more homogeneously. The different behavior of Zr and Mn during solidification could be related to the different effect observed in tenacity terms Obtaining a structure recrystallized, favored here by the absence of zirconium, perhaps  it can also have an intrinsic beneficial effect on the tenacity. Advantageously the recrystallization index of the Products according to the invention is greater than 80%.

The inventors discovered that the temperature homogenization had to be preferably between 480 and 520 ° C for 5 to 60 hours, and more preferably between 490 and 510 ° C for 8 to 20 hours. During the invention the inventors observed that in certain cases homogenization temperatures higher than 520ºC they tended to reduce the results of tenacity. The inventors think that there is a relationship between the technical effect of homogenization conditions and the behavior during solidification described more above.

For production of plates temperature  Initial hot rolling is preferably 450 to 490 ° C. Hot rolling is preferably performed as for obtain a thickness between 4 and 12.7 mm. So optional, for a thickness of approximately 4 mm or less, you can add a cold rolling stage if necessary. In case of sheet metal fabrication, the sheet obtained has a thickness between 0.8 and 12.7 mm, and the invention is more advantageous for sheets 1.6 to 9 mm thick and even more advantageous for sheets  2 to 7 mm thick. The product according to the invention dissolves then, preferably by heat treatment between 480 and 520 ° C for 15 min. at 4 h, and it is tempered with water at temperature ambient.

The product is then subjected to traction controlled between 1 and 5% and preferably between 2 and 4% If the traction is greater than 5% the mechanical properties they may not be sufficiently improved and may be encounter industrial difficulties such as an application expensive, which would increase the cost of the product. A tempered at a temperature between 140 and 170 ° C for 5 at 80 h and more preferably between 140 and 155 ° C for 20 to 80 h. The lowest dissolution temperatures in this range are usually favor high tenacity. In an embodiment of the present invention comprising a welding step of the product, the tempering stage is divided into two stages: one stage prior tempering, prior to a welding operation, and a Final heat treatment of a welded structural element.

The characteristics of the sheets obtained with the present invention comprise at least one of the following features:

- the tensile yield limit R_ {p0.2} in the L direction is preferably at least 390 MPa or even 400 MPa,

- the breaking strength R_ {m} in the direction L is preferably at least 410 MPa or even of 420 MPa,

- the tensile yield limit R_ {p0,2} at 45º with respect to the direction of the laminate is therefore less equal to the tensile yield limit R_ {p0,2} in the L-T sense.

- the difference between the elasticity limit in tensile R_ {p0,2} at 45º with respect to the direction of the laminate and the tensile yield limit R_ {p0,2} in the TL direction defined by (R_ {p0,2} (TL) - R_ {p0,2} (45º)) / Rp_ {0,2} (TL), is between + 5% and -5% and preferably between + 3% and -3%.

- the tenacity properties they use CCT760 specimens (with 2ao = 253 mm) are such that:

- K_ {app} in the T-L address it is preferably at least 100 MPa? and preferably at least 120 MPa?;

- K_ {app} in the L-T address it is at least 150 MPa \ surdm and preferably at least minus 160 MPa \ surdm;

- K_ {eff} in the direction T-L it is at least 120 MPa \ surdm and preferably at least minus 150 MPa \ surdm;

- K_ {eff} in the L-T direction it is at least 160 MPa \ surdm and preferably at least minus 220 MPa \ surdm;

- \ Deltaa_ {eff (max)}, the extension of crack of the last valid point of the R curve in the direction T-L, is preferably at least 60 mm and preferably at least 80 mm;

- \ Deltaa_ {eff (max)}, from the R curve in the L-T direction, preferably at least 60 mm and preferably at least 80 mm.

The terms "high strength", "high toughness "," large extent of crack before a fracture unstable "," small anisotropy "such as are used here they refer to products offered by the above properties.

Advantageously the recrystallization index of The plates according to the invention is greater than 80%.

Advantageously the conformation of the products according to the invention can be carried out by stretched-shaped ("stretch-forming"), deep drawing, pressing, stretch forming, profile rolling or folding, these techniques being known by the specialist. At assembly of structural parts, if desired can be used all known and possible riveting, gluing and welding adapted to aluminum alloys. The products according the invention can be fixed to reinforcements or frames, by rivet, glued or welded for example. The inventors discovered that in If welding is chosen, it may be preferable to use low temperature welding techniques, which help ensure that the thermally affected area is as limited as possible. For this purpose laser welding and welding by friction-mixing often provide results particularly satisfying.

If desirable products according to invention, before or after shaping, can be submitted advantageously to a temper to provide properties improved static mechanics. Advantageously this tempering too It can be done in an assembled structural element. The products according to the invention are preferably used for manufacture of structural elements for construction aeronautics. A structural element, formed by a sheet according to the invention and reinforcements or frames, being preferably constituted said reinforcements or frames by extruded profiles, can use in particular for the manufacture of fuselage aeronautical or any other use in which you present them Properties could be advantageous. In an advantageous embodiment of the invention, a fuselage panel comprising at least one sheet according to the invention.

The inventors discovered that the products of  the invention offered a particularly favorable compromise between static mechanical properties, high toughness and density. For known low density products, the sheet metal high tensile strength and with an important limit of elasticity usually have a low tenacity. For the plates of the invention the properties of high tenacity and in particular the very long R curve favor industrial application to parts of aircraft fuselage. In certain advantageous embodiments of the invention the density of the products is less than about 2.69 g / cm3 and preferably less than about 2.66 g / cm3.

The products of the invention do not usually induce no particular problem during subsequent operations of surface treatment classically used in construction aeronautics, in particular for mechanical or chemical polishing, or treatments aimed at improving the adherence of polymer coatings.

Corrosion resistance is usually high intergranular of the products of the invention; as an example, by subjecting the metal to a corrosion test, they usually only bites detected In a preferred embodiment, You can make a sheet of the invention, without it being placed in one or the other side, with a low-charged aluminum alloy of Alloy elements

These aspects, as well as others, of this invention are explained in more detail with the aid of the following illustrative and non-limiting example.

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Example

The example of the invention bears the reference C. Examples B and D are presented by way of comparison. He Example A is a reference AA2098 alloy. Table 2 shows provide the chemical compositions of the different Alloys tested.

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TABLE 2 Chemical composition (% by weight)

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Table 3 shows the volumetric mass of the different alloys tested. Between the different materials tested samples B to D present the mass smaller volume.

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TABLE 3 Volumetric mass of alloys subjected to proof

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Table 4 shows the procedures. Used to manufacture the different samples.

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TABLE 4 Conditions of the consecutive stages of transformation

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The granular structure of the samples is characterized from the microscopic observation of the cross sections after anodic oxidation, under polarized light or after a chromic attack. An index of recrystallization The recrystallization index is defined as the fraction of surface occupied by recrystallized grains. For the  samples B, C and D the recrystallization index was 100%. For samples A # 1 and A # 2 the recrystallization index was less than 20%.

The samples were mechanically subjected to test in order to determine its mechanical properties static as well as its resistance to the propagation of cracks. Table 5 gives the limit of elasticity in traction, ultimate strength and break elongation.

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TABLE 5 Mechanical properties of samples

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The static mechanical properties of samples according to the invention are comparable to those of an alloy 2XXX range damage-tolerant and less than those of high strength alloys such as 7475 or 2098 (A). The strength of comparison alloy B is lower than that of the alloy according to the invention (C), which perhaps is related to the absence of silver in the alloy of comparison B. The inventors consider the proportion of copper and the lower zirconium ratio of the sample according to the invention explain the lowest resistance compared to the 2098 alloy (sample A).

The anisotropy of sample C according to invention is very low as illustrated in figure 5 that represents the normalized evolution of the elastic limit of agreement with the orientation. Thus the limit of elasticity in traction at 45º It is slightly higher than the tensile strength limit in the TL sense; thereby the difference between these values, defined by (R_ {p0.2} (TL) - R_ {p0.2} (45º)) / R_ {p0.2} (TL), is of -0.3%. In comparison, this difference is 13.2% for the Reference sample A # 2 (AA2098).

In addition, sample C according to the invention has high tenacity properties

The R curves are supplied in Figures 1 and 2  of samples A # l, B and C, respectively for the addresses T-L and L-T. Figure 1 shows clearly that the crack extension of the last valid point of the R (\ Deltaa_ {eff (max)}) curve is much larger for sample C of the invention that for the reference sample To the. This parameter is at least as critical as the values. K_ {app} because, as explained in the art description above, the length of the R curve is an important parameter for The fuselage design. Figure 2 shows the same trend but  the difference is smaller because the address L-T gives intrinsically better results. He Table 6 compiles the results of the tenacity tests.

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TABLE 6 Results of the trials of tenacity

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Table 7 shows the results. from the R curve. The crack extension of the last point Valid of curve R is higher for sample C of the invention than for sample A # l of reference. The inventors consider that several reasons can be proposed to explain these results. Unexpectedly the absence of Zr can contribute mostly, directly or indirectly, to the results in tenacity terms

TABLE 7 Summary data of the R curve

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Figures 3 and 4 show the evolution of the cracking speed respectively in orientation T-L and L-T, when the amplitude varies of the voltage intensity factor. The width of the sample was 400 mm (test tube CCT 400) and R = 0.1. None observed most important difference between samples A, B and C. The cracking rate of sample C is of the same order of magnitude than typically obtained for alloys AA6156 and AA2056.

The intergranular corrosion resistance of Samples A # l, B and C were tested according to ASTM G110. No corrosion was detected for all samples intergranular Thus for the sample according to the invention the Intergranular corrosion resistance was high.

Other specialists will appear more clearly advantages, features and modifications. Therefore, the invention in its broadest aspects is not limited to details specific or to the representative devices shown and describe here. So you can make different modifications without going beyond the scope of the general inventive concept as defined in the appended claims.

Claims (12)

1. Aluminum based alloy comprising between 2.1 and 2.8% by weight of Cu, 1.1 and 1.7% by weight of Li, 0.1 and 0.8% by weight of Ag, 0.2 and 0.6% by weight of Mg, 0.2 and 0.6% by weight of Mn, a lower amount of Fe and Si or equal to 0.1% by weight each, balance Al and inevitable impurities in a proportion less than or equal to 0.05% by weight each and 0.15% by weight in total, the alloy being substantially free of zirconium, which means that the Zirconium ratio is less than 0.04% by weight. 2. Aluminum alloy according to claim 1, comprising between 2.2 and 2.6% by weight of Cu, 1.2 and a 1.6% by weight of Li, 0.2 and 0.6% by weight of Ag, 0.3 and a 0.5% by weight of Mg, 0.2 and 0.5% by weight of Mn. 3. Aluminum alloy according to claim 1, which comprises between 2.3 and 2.5% by weight of Cu, 1.3 and a 1.5% by weight of Li, 0.2 and 0.4% by weight of Ag, 0.3 and a 0.4% by weight of Mg, 0.3 and 0.4% by weight of Mn. 4. Aluminum alloy according to any one of claims 1 to 3 wherein the proportion of zirconium is less than 0.03% by weight and preferably less than 0.01% in weigh. 5. rolled, extruded or forged product that comprises an alloy according to any one of the claims 1 to 4 6. Product according to claim 5 whose Recrystallization rate is greater than 80%. 7. Laminated product according to claim 5 or  claim 6 whose thickness does not exceed 12.7 mm. 8. Procedure for manufacturing a sheet of aluminum alloy that has high strength and toughness, in the one who: (a) a plate is cast comprising a 2.1 and 2.8% by weight of Cu, 1.1 and 1.7% by weight of Li, a 0.1 and 0.8% by weight of Ag, 0.2 and 0.6% by weight of Mg, 0.2 and 0.6% by weight of Mn, a lower amount of Fe and Si or equal to 0.1% by weight each, balance Al and inevitable impurities in a proportion less than or equal to 0.05% by weight each and 0.15% by weight in total, the alloy being substantially free of zirconium, which means that the Zirconium ratio is less than 0.04% by weight, (b) the corresponding plate is homogenized between 480 and 520ºC for 5 to 60 hours, (c) hot rolled and optionally in  cold the corresponding plate on a sheet, with a temperature initial rolling of 450 to 490 ° C, (d) the corresponding sheet is dissolved between 480 and 520 ° C for 15 minutes to 4 hours, (e) the corresponding plate is tempered, (f) the corresponding sheet with a permanent deformation of between 1 and 5%, (g) a tempering of the corresponding  sheet by heating between 140 and 170ºC for 5 to 80 hours. 9. Product according to claim 8 wherein the thickness of the sheets obtained is between 0.8 mm and 12.7 mm and preferably between 1.6 mm and 9 mm. 10. Sheet metal obtainable by method of claim 8 or claim 9, which understands (a) a limit of elasticity R0.2 in the sense L of at least 390 MPa and preferably of at least 400 MPa, and / or (b) a difference between the limit of tensile elasticity R_ {p0,2} at 45º with respect to the direction of the laminate and the tensile yield limit R_ {p0,2} in the TL direction, defined by (R_ {p0,2} (TL) - R_ {p0,2} (45º)) / R_ {p0,2} (TL), between + 5% and -5% and preferably between + 3% and -3%, and / or (c) a flat tension tenacity K_ {app}, measured on specimens of type CCT760 (2ao = 253 mm) of at least 100 MPa \ surdm and preferably at least 120 MPa \ surdm, in the T-L sense, and / or (d) and a crack extension of the last point valid of the R \ Deltaa_ {eff (max)} curve in the direction T-L of at least 60 mm and preferably of at least 80 mm 11. Aircraft fuselage panel comprising at least one sheet according to claim 10. 12. Structure element intended for a aeronautical construction comprising at least one product according to claim 6, 7 or 10.