AT502313B1 - METHOD FOR PRODUCING A HIGH-DAMAGE TOLERANT ALUMINUM ALLOY - Google Patents

Description

& t £ S! iÄ hi5 AT502 313B1 2009-09-15

Description [0001] The present invention discloses a method of producing a high damage tolerant rolled aluminum alloy having good toughness and fatigue crack growth resistance while maintaining good levels of strength, and an aluminum alloy sheet or plate product having such high toughness and fatigue crack growth resistance. Furthermore, the invention relates to the use of an alloy product obtained by the method of this invention.

It is known in the art heat treatable aluminum alloys in a number of applications where relatively high strength is involved, such as aircraft fuselages. Vehicle parts and other applications to use. The aluminum alloys AA2024, AA2324 and AA2524 are well known heat treatable aluminum alloys that have useful strength and toughness properties with T3, T39 and T351 coatings. In addition, the aluminum alloys AA6013 and AA6058 are well-known heat treatable aluminum alloys which have useful strength and toughness properties as well as good fatigue crack growth resistance at both T4 and T6 temper.

It is known that the T4 temper relates to a solution annealed and quenched state that has naturally aged to a substantially stable level of properties, while T6 grades relate to a firmer state made by artificial aging.

Several other AA2000 and AA6000 series alloys are generally unsuitable for the construction of commercial aircraft requiring different sets of characteristics for different types of structures. Depending on the design criteria for a given aircraft component, even small improvements in toughness and crack growth resistance, particularly for high AK values, can result in weight savings that will result in fuel savings over the life of the aircraft and / or a greater level of safety. In particular, the outer hull or lower wing skin is required to have properties such as good resistance to crack propagation, either in the form of fracture toughness or fatigue crack growth resistance. A rolled alloy product, used either as a sheet or as a panel with improved damage tolerance characteristics, improves passenger safety, reduces the weight of the aircraft, and results in a longer flying range, lower costs, and less frequent maintenance intervals.

[0005] US 5,213,639 discloses a method of making an AA2000 series aluminum alloy with an aluminum base alloy which is hot rolled, heated and hot rolled again, thereby achieving good combinations of strength along with high fracture toughness and a low fatigue crack growth rate. It is disclosed to apply an intermediate annealing treatment after hot rolling the cast ingot at a temperature of between 479 ° C and 524 ° C and hot rolling the interannealed alloy again. Such an alloy is reported to have a 5% improvement over the conventional AA2024 series alloys in T-L fracture toughness and improved fatigue crack growth resistance at certain AK levels.

It has been reported that the known AA6056 alloy is susceptible to grain boundary corrosion in the T6 temper condition. To overcome this problem, US 5,858,134 provides a process for the production of rolled or extruded products having a defined chemical composition, which brings the products into an over-aged temper, resulting in time-consuming and time-consuming processing by the manufacturer of air and water Space components required. Here it is reported that to achieve the improved grain boundary corrosion resistance of essential 1/13

oiteüsdiisd '' patenuimt AT502 313 B1 2009-09-15

Importance of the process is that the Mg / Si ratio in the alloy is less than one.

US-4. 589,932 discloses an aluminum wrought alloy product, for example, for automotive and aerospace constructions, the alloy subsequently being registered under the AA designation 6013. Such an aluminum alloy was solution heat treated at a temperature in the range of 449 ° C to 582 ° C, which approaches the solidus temperature of the alloy.

EP-A-1143027 discloses a method for producing an AA6000 series Al-Mg-Si alloy having a defined chemical composition, wherein the products are subjected to artificial aging to improve the alloy and enhance the characteristics Damage tolerance (" HDT ") similar to those of the AA2024 series, which are preferably used for aviation applications but are not weldable. The aging process is optimized using a respective function of the composition.

EP-1170394-A2 discloses an aluminum alloy sheet product having improved fatigue crack growth resistance with an anisotropic microstructure defined by grains having an average aspect ratio of greater than about 4. Such an alloy has an improvement in compressive strength properties achieved by respective sheet products as compared to conventional AA2524 sheet products. Throughout the highly anisotropic grain structure, fatigue crack growth resistance could be improved.

WO-97/22724 discloses a method and apparatus for producing an aluminum alloy sheet product, typically for automotive use, with improved yield strength by continuously and rapidly heating the hot rolled and cold rolled sheet, which has been solution annealed and quenched, to a preaging temperature before the step of continuous winding. After rapid heating, the sheet is cooled in ribbon form at ambient temperature, with rapid heating and ambient temperature cooling improving the paint bake response of the aluminum alloy sheet. It is disclosed that it is preferred to quickly heat the wound sheet to between 65 ° C and 121 ° C and to choose a cooling rate at ambient temperature which is preferred to be between 1.1 ° C / hr and 3.3 ° C / h.

From WO / 1996/029440 a method according to the preamble of claim 1 is known. In this case, a very rapid cooling takes place after the solution annealing at a rate of about 540 ° C / sec from the temperature range between 400 and 290 ° C to a temperature of less than 180 ° C. Good material properties were expected from such a rapid cooling, for example, by high-pressure cooling water.

In addition, a method for the production of automotive parts is known (WO98 / 37251), in which the rolled product after the solution heat treatment in the range between 480 ° C and 580 ° C to about 55 ° C to 85 ° C also with a cooled to very high cooling rate of more than 10 ° C / sec and then wound in the range between 55 ° C and 85 ° C, before the subsequent slow cooling to room temperature with a cooling rate of in particular less than 2 ° C / h.

It is an object of the present invention to provide a method of producing an aluminum alloy product having improved toughness and fatigue crack growth resistance. At the same time, the strength levels of conventional AA2000, AA5000, AA6000 or AA7000 series alloys should be maintained. In particular, it is the object of the present invention to provide an improved method for producing high damage tolerant ("HDT") aluminum alloys having balanced fatigue crack propagation, toughness, corrosion resistance and strength properties. The HDT properties should preferably be better than those of conventionally made AA6013-T6, 6056-T6 alloys, and preferably better than AA2024-T3 alloys. *** " or AA2524-T3 alloys.

In particular, there is a general requirement for AA6000 series rolled aluminum alloys, preferably in the range of AA6013 and AA6056 series aluminum alloys, for use in aerospace applications where the fatigue crack growth rate ("FCGR") is not greater than a defined one Should be maximum. For example, an FCGR meeting the requirements of Series 2024 high damage tolerant alloy products has an FCGR below 0, 001 mm / cycles at Ak = 2QMPa ^ m and 0, 01 mm / cycles at Ak = 40MPaVm.

Another object of the present invention is to provide a rolled aluminum alloy product for use in engineering structural parts in the aircraft industry, and an aircraft skin material or vehicle component made from such alloy.

The invention is characterized in claim 1 and in subclaims further embodiments of the invention are claimed.

In the invention, emphasis is placed on a controlled cooling cycle for cooling after leaving the hot rolling mill to a temperature of 150 ° C or less. It is advisable to wrap the hot rolled product during cooling.

For cooling during the controlled cooling cycle corresponding to T (t) = δΟ-ίδΟ-ΪΕχιτ ^ "1, the use of a value α in the range of - 0, 09 ± 0, 05 (h'1), in particular from - 0, 09 ± 0, 03 (h'1).

It has been found that below the temperature of 150 ° C, the cooling rate is no longer relevant to achieving one or more of the advantages found in this invention.

While prior art techniques teach one skilled in the art to cast a billet and hot roll to achieve a sheet or sheet product wherein the billet is optionally preheated or homogenized prior to hot rolling, the hot rolled product has fairly lost its elevated temperature fast, which jeopardized the performance of the product. It has been found that by maintaining the hot-rolled product at an elevated temperature for a predetermined period of time to undergo a controlled cooling cycle, the damage tolerance properties such as toughness and crack growth resistance of such a rolled product of the present invention can be improved.

Typical hot rolling mill outlet temperatures are in a practical industrial scale in a range of 350 to 500 ° C and depend on the alloy, for example, the exit temperature for a AAöxxx at the higher end of this range of about 420 to 500 ° C, whereas for AA2xxx and AA7xxx series alloys, this would be at the lower end of this range of about 350 to 425 ° C.

[0022] E in further cold rolling the cooled hot rolled product in band ring form is optional. The cold rolling may be straight or oblique rolls. Further steps of intermediate annealing before, during or after cold rolling are also optional.

Further, it is possible to wind the hot-rolled product to obtain a wound shape while performing a controlled cooling until the product is cooled to room temperature. Then it is possible to cut the band ring in blooms, which are then further cold rolled. The material produced by this inventive processing sequence showed a better balance of properties than those hot rolled products cut into billets during or after hot rolling without winding (standard sheet follower sequence) or those wound after cold rolling (standard sheet sequence).

A second alternative for subjecting the hot rolled product to a controlled cooling cycle is the step of continuously moving the alloy through an oven after a period of 3 to 10 minutes hot rolling, wherein the furnace may be arranged to apply heat and / or cold to the alloy as it advances to its cold rolling station or winding station, thereby to conform to the controlled cooling cycle.

In a further alternative, the rolled product is first hot rolled to a desired level and then cooled to room temperature using conventional cooling. Thereafter, the cooled hot rolled product is reheated to a hot mill exit temperature and is then cooled to below 150 ° C, taking into account the controlled cooling cycle of the invention. Thereafter, further processing takes place.

Depending on whether sheets or plates are produced, the hot-rolled product is either fed into the oven after hot rolling or wound after hot rolling, the further processing is done on band rings (sheet sequence). When the product is cut into sheet plates during or after hot rolling, further processing is done on sheet metal plates produced thereby.

The furnace may preferably be arranged to hold different amounts of heat in the vicinity of the hot rolling station and other amounts of heat at a greater distance from the hot rolling station depending on the cooling rate, thickness and other dimensions of the hot rolled product containing the Hot rolling station leaves, applies.

When the hot rolled product is subjected to the controlled cooling cycle by winding, it is possible to wind the alloy in a respective furnace after hot rolling, and then the furnace can also be arranged to apply heat to control the cooling cycle.

In one embodiment, the hot rolled product has a dimension in a range of up to 12 mm when leaving the hot rolling mill at the hot rolling mill exit temperature, and preferably in a range of 1 to 10 mm, the range being 4 to 8 mm Strongest is to be preferred.

Further, when the rolled product is subjected to a cold rolling process, it is preferable that the total cold rolling reduction be in a range of 40 to 70% in order to further optimize the mechanical properties. The final gauge of the rolled alloy product is preferably in a range of about 2 to 7 mm.

The process of the present invention may further comprise one or more of the following steps: d) solution annealing the hot rolled product after it has undergone the controlled cooling cycle or the cold rolled product at a temperature and time sufficient to place soluble components in the alloy in solid solution; E) quenching the solution heat treated alloy product by one of spray quenching or immersion quenching in water or other quenching media; F) optionally stretching or pressing the quenched alloy product or otherwise cold working to relax, such as straightening sheet metal products; G) optionally aging the quenched and optionally stretched or pressed alloy product to achieve a desired temper, depending on the alloy chemistry, but the T3, T351, T6, T4, T74 T76, T751, T7451, T7651, T77 temper , T79 includes.

Further, it is possible to anneal and / or reheat a hot-rolled block after a first hot rolling operation, and then roll the product again to a hot-rolling size, followed by a hot rolling Cooling after the cooling cycle of the invention followed. It is further possible to anneal the hot rolled product before and / or during cold rolling. These techniques, which are known in the art, can be advantageously used in a method according to the present invention.

The average cooling rate using the controlled cooling cycle of the invention is in the range of 12 to 20 ° C / hour.

In one embodiment of the present invention, the casting block for the processing sequence of the process disclosed herein comprises the following composition (in weight%): Si 0.6 to 1.3, Cu 0.04 to 1, 1, Mn 0.1 to 0.9, Mg 0.4 to 1.3, Fe 0.01 to 0.3, Zr < 0.25, Zn < 0.6, Ti < 0.15, V < 0.25, Hf < 0.25, other elements, in particular impurities, each less than 0.05 and less than 0.20 total, balance aluminum, alloys in the composition range of AA6013 or AA6056 being more preferable.

Another embodiment of the present invention uses a block comprising the following composition (in weight%): Cu 3.8 to 5.2, Mg 0.2 to 1.6, Cr < 0.25, Zr < 0.25 and preferably 0.06 to 0.18, Mn £ 0.50 and Mn: > 0 and preferably > 0.15, Fe 0.15, Si 0.15 and Μη-containing dispersoids and non-essential elements and impurities each less than 0.05 and less than 0.15 in total and the remainder substantially and wherein the Mn-containing dispersoids preferably at least partially replaced by Zr-containing dispersoids.

According to another embodiment of the present invention, the method uses a block substantially comprising the following composition (in weight%): Zn 5, 0 to 9.5, Cu 1.0 to 3.0, Mg 1.0 to 3.0, Mn < 0.35, Zr < 0.25, and preferably 0.06 to 0.16, Cr < 0.25, Fe < 0.25, Si < 0.25, Sc < 0.35, Ti < 0.10, Hf and / or V < 0.25, other elements, typically impurities, each less than 0.05 and less than 0.15 in total, balance aluminum. Typical examples are alloys in the range of AA7040, AA7050 and AA7x75.

According to another aspect of the present invention, there is disclosed an aluminum alloy sheet or panel product having high toughness and fatigue crack growth resistance, which is made from an alloy product prepared by a method as described above and hereinafter has been described in more detail was prepared. In particular, the present invention is best suited for producing a rolled alloy sheet product which is a structural element of an aircraft or a motor vehicle. Such a rolled alloy sheet product could be used, for example, as a fuselage skin of an aircraft or a vehicle component.

The foregoing and other features and advantages of the method and alloy products of the present invention will become readily apparent from the following detailed description of preferred embodiments and the following figures, in which Figure 1 is a typical aluminum alloy cooling curve after hot rolling using the method of this invention has been cooled. 5/13 iKte-isscfistiiö pälemaat AT502 313B1 2009-09-15

EXAMPLES EXAMPLE 1 In a first embodiment of the present invention, two conventional alloys (AA6013 and AA6056) were cast and made into a sheet product. Two processing variants were used here: Sequence 1. A normal processing sequence was used by pouring blocks of conventional laboratory grade AA6013 and AA60156 alloy compositions. Blocks of 80 x 80 x 100 mm were cut, homogenized, preheated and hot rolled to 4, 5 mm sheet. After hot rolling, the hot rolled products were conventionally cooled to ambient temperature by allowing the sheet to cool to room temperature in ambient air, fed to the cold rolling station, cold rolled to 2 mm and heat treated at 550 ° C for 20 minutes, then quenched and heated at 190 for 4 hours ° C aged on a T6 temper.

Sequence 2. Blocks of conventional AA6013 and AA6056 alloy compositions were cast at the laboratory level and cut to a size of 80 x 80 x 100 mm. These blocks were homogenized, preheated and hot rolled to 4.5 mm sheet. An industrial scale simulation of hot rolling was incorporated by giving the hot rolled product a temperature history similar to that exhibited by a large production strip ring. The other processing steps were kept similar to work sequence 1. After cold rolling, the cold rolled product was heat treated at 550 ° C for 20 minutes, quenched, and then aged for 4 hours at 190 ° C on a T6 temper. The results are given in Table 1.

Table 1. Overview of strength (Rp, Rm) using small Euronorm, notch toughness (TS / Rp), grain boundary corrosion (IGC) in depth, and type of 6013 and 6056 alloy compositions, which are ordered by work sequence 1 and work sequence 2r described above, were processed at two different hot rolling exit temperature settings.

No. Alloy Table Heat Roll Outlet Temperature rc) Rp (MPa) Rm (MPa) TS / Rp IGC Depth (pm) IGC Type 1 6013 2 490 354 390 1.75 101 P (i ) 2 1 490 344 381 1.72 118 I 3 2 450 345 385 1.73 97 I 4 1 450 337 377 1.63 108 I 5 6056 2 490 347 386 1.85 112 I 6 1 490 349 388 1.79 177 l + 7 2 450 328 372 1.75 103 P (i) 8 1 450 331 375 1.70 143 I

From Table 1 it can be seen that the rolled products showed better notch toughness at higher hot rolling temperatures while maintaining good levels of yield strength and specific tensile strength. Furthermore, there is an improvement in grain boundary corrosion so that further fatigue crack growth resistance tests were performed (Table 2).

Table 2. Overview of Fatigue Crack Growth Stability (FCGR) for the Example 6/13

ästeifcsasri® AT502 313B1 2009-09-15 games no. 1,2 and 5, 6 from Table 1 (higher hot rolling temperatures) at two different ΔΚ levels.

Alloying Operation Heat roll outlet tempera- ture (° C) FCGR ΔΚ = 30 MPaVm FCGR ΔΚ = 40 MPaVm 6013 2 490 1, 83E-03 5, 26E-03 1 490 I, 84E-03 8, 88E-03 6056 2 490 I, 62E-03 3, 32E-03 1 490 1, 66E-03 4, 89E-03 [0050] While the fatigue crack growth resistance of the inventive products is comparable to the fatigue crack growth resistance of a product obtained by the standard processing sequence Almost identical to lower AK values, fatigue crack growth resistance is improved at higher AK values.

According to another preferred embodiment of the present invention, a low-copper high-damage tolerant AA6000 series alloy composition was prepared in a large scale production experiment. The composition is given in Table 3.

Table 3. Composition of high damage tolerant sheet metal product series AA6000 in wt -%, balance aluminum and unavoidable impurities.

Si Fe Cu Mg Mn Zn 1, 14 0, 18 0, 32 0, 70 0.71 0, 08 The alloy was made into a sheet metal product having a hot rolling amount of 4.5 mm. The following three processing variants were then applied: Work sequence 1 A standard processing sequence. (No winding step after hot rolling).

Sequence 2. The inventive processing sequence with winding after hot rolling and hot rolling and cold rolling in the same direction.

Sequence 3. The inventive sequence with winding after hot rolling and hot rolling and cold rolling in different directions (oblique rolls).

All three aforementioned processing variants were applied according to the following general processing sequence: a. Direct chill casting of blocks of an alloy composition according to Table 3.

B. Homogenizing the cast blocks.

C. Preheat the homogenized blocks for 6 hours at 510 ° C and then hot-roll the preheated blocks, with the result that the exit temperature is approximately 450 ° C at a level of 4.5 mm.

D1. No winding (= work sequence 1).

D2. Winding, cooling and cutting into metal sheets (= sequence 2).

D3. Winding, cooling and cutting to metal sheets (= sequence 3).

E1. Cold rolling to a final dimension of 2 mm (sequence 1).

E2. Cold rolling in the same direction as in the hot rolling to a final dimension of 2 mm (sequence 2).

E3. Cold rolling in a different direction as during hot rolling (oblique rolling) on 7/13 tarssÄiies patemt AT502 313B1 2009-09-15 a final dimension of 2 mm (sequence 3).

F. Heat treated for 2 hours at 550 ° C.

G. Stretching the cold-rolled product by 1, 5 to 2, 5%.

H. Aging for 4 hours at 190 ° C to a T6 temper condition.

Table 4. Overview of strength (Rp, Rm) using small Euronorm, notched toughness (TS / Rp) and grain boundary corrosion (IGC) of a finished product with an alloy according to Table 3 and using three processing sequences 1, 2 and 3 , as described above.

Work sequence Rp (MPa) Rm (MPa) Rp (MPa) Rm (MPa) TS / Rp IGC Depth (pm) L-direction LT direction TL- direction- 1 334 345 322 344 1.51 62 2 329 344 321 341 1.60 43 3 333 344 326 347 1.58 49 While the levels of strength could be maintained, the rolled products made according to Processing Sequences 2 and 3 showed better notch toughness and better grain boundary corrosion behavior. Consequently, fatigue crack growth resistance was also measured and reported in Tables 5 and 6.

Table 5. Fatigue crack growth resistance in mm / cycle for 5 different AK values for the products made according to processing sequences 1, 2 and 3 as described above. ΔΚ (MPaVm) Work sequence 1 Operating sequence 2 Operating sequence 3 10 1.52E-04 1.71E-04 1.78E-04 20 1.43E-03 8, 58E-04 1.26E-03 30 6, 14E-03 3, 38E-03 5, 17E-03 40 1,70E-02 9, 54E-03 - 50 3, 73E-02 1,85E-02 -

Table 6. Values of Table 5 with respect to the standard (sequence 1). __ ΔΚ (MPaVm) Work sequence 1 Work sequence 2 Work sequence 3 10 100% 113% 117% 20 100% 60% 88% 30 100% 55% 84% 40 100% 56% - 50 100% 50% - [0073] The above indicated Examples show that the damage tolerance properties of sheet metal or sheet products can be improved using the inventive method and that the fatigue crack growth resistance can be improved in particular for higher AK values. 8.13

oiteüsäisd'is patenuimt AT502 313 B1 2009-09-15 EXAMPLE 2.

Fig. 1 shows a typical continuous cooling curve for an aluminum AA7050 alloy as it is cooled from a hot rolling mill exit temperature of 440 ° C to a temperature below 150 ° C, the metal sheet having a dimension of 4.5 mm and immediately leaving of the hot rolling mill according to an embodiment of the method of this invention. The width of the band ring was 1.4 meters. The temperatures of the band ring as a function of time are also shown in Table 7 for the warmest point of a band ring (which is the center and is displayed as HotSpt in Figure 1) and the coldest point (which is the edge of a band ring and as ColdSpt in Figure 1) 1 is displayed). Table 7 also provides the temperatures for a ribbon ring 2.8 meters wide.

In the cooling curve shown in Fig. 1, the α is about -0, 084 (h1).

When a sheet having a gauge of about 4.0 to 4.5 mm was allowed to cool down to below 150 ° C from the hot rolling mill discharge temperature using conventional cooling practice, namely, to cool the sheet after leaving the hot rolling mill without winding operation or the like In normal standing air, the α was typically in the range of -0.5 to -2 (h'1) and caused such a sheet to cool down to a temperature within a period of less than 3 hours from the hot mill exit temperature cooled from 150 ° C or less.

The controlled cooling cycle follows the equation set forth above and in the claims and the average cooldown of the wound product form from 440 to 150 ° C is in the range of 12 to 20 ° C / hour.

Table 7. Banding temperatures as a function of time when cooled according to the invention for an AA7050 alloy with a degree of winding of 4.5 mm.

Time (hours) Band Ring Width 1.4 meters Band Ring Width 2.8 meters Coldest Point (° C) Warmest Point (° C) Coldest Point (° C) Warmest Point (° C) 0 431 440 431 440 2 344 372 349 385 6 249 266 262 287 10 187 199 204 222 12 165 175 182 197 14 146 150 163 176 16 130 137 148 159 18 117 123 134 144 9/13

Claims (13)

A method of making high damage tolerant structural parts of an aircraft or spacecraft of aluminum alloy rolled products having high toughness and improved fatigue growth resistance, comprising the steps of: a) casting a block with a composition comprising; selected from the group consisting of AA2000, AA6000 and AA7000 series alloys; b) homogenizing and / or preheating the block after casting; c) hot rolling the billet into a hot rolled product, optionally cold rolling the hot rolled product into a cold rolled product, characterized in that the rolled product after hot rolling from the hot rolling exit temperature texit is between 350 ° C and 500 ° C to 150 ° C or lower in one controlled cooling cycle corresponding to T (t) = δΟ-ίδΟ-ΪΕχι ^ β 1, where T (t) is the temperature (° C) as a function of time (h), e is the Euler number (= 2, 71828), t is the time (h), and α is selected from the range of -0.09 ± 0.05 (h'1), and that the hot rolled product is wound and / or continuously passed through an oven during the controlled cooling cycle becomes. 2. The method according to claim 1, characterized in that α is selected from the range of -0.09 ± 0.03 (h'1). 3. The method according to claim 1 or 2, characterized in that the hot rolling is carried out to a thickness of the product of 12 mm or less. 4. The method according to claim 3, characterized in that the hot rolling is carried out to a thickness of the product in a range between 1 and 10 mm and preferably in a range between 4 and 8 mm. 5. A process according to any one of the preceding claims, characterized by one or more of the following process steps: d) solution annealing the hot rolled product after it has undergone the controlled cooling cycle or the cold rolled product; e) quenching the solution heat treated alloy product; f) optional stretching or pressing of the quenched alloy product; g) optionally aging the quenched and optionally stretched or pressed alloy product to achieve a desired temper. A method according to any one of the preceding claims, characterized in that the average cooling rate in the controlled cooling cycle is selected from the range of 12 to 20 ° C / hour. 7. The method according to any one of the preceding claims, characterized in that the casting of a block having the following composition (in wt. -%) is carried out: Si 0.6 to 1.3 Cu 0.04 to 1.1 Mn 0.1 to 0.9 Mg 0.4 to 1.3 Fe 0.01 to 0.3 Zr &lt; 0.25 Cr &lt; 0.25 10/13 & t £ S! »Cilsl5Chi $ AT502 313B1 2009-09-15 Zn &lt; 0.6 Ti &lt; 0.15 V &lt; 0.25 Hf &lt; 0.25, other elements less than 0, 05 and less than 0.20 in total, balance aluminum. 8. The method according to any one of claims 1 to 6, characterized in that the casting of a block is carried out with an alloy in the composition range of AA6013 or AA6056. 9. The method according to any one of claims 1 to 6, characterized in that the casting of a block for the following composition (in wt. -%) takes place: Cu 3.8 to 5.2 Mg 0.2 to 1.6 Cr &lt; 0.25 Zr &lt; 0.25 and preferably 0.06 to 0.18 Mn &lt; 0.50 and Mn: &gt; 0 and preferably> 0.15 Fe <0.15 Si &lt; 0.15, other elements each less than 0.05 and less than 0.15 in total, balance aluminum. 10. The method according to any one of claims 1 to 6, characterized in that the casting of a block having the following composition (in wt. -%) takes place: Zn 5.0 to 9.5 Cu 1.0 to 3.0 Mg 1, 0 to 3.0 Mn &lt; 0.35 Zr &lt; 0.25 and preferably 0.06 to 0.16 Cr &lt; 0.25 Fe &lt; 0.25 Si &lt; 0.25 Sc &lt; 0.35 Ti <0.10 Hf and / or V &lt; 0.25 other elements each less than 0.05 and less than 0.15 in total, balance aluminum. 11. The method according to any one of claims 1 to 6, characterized in that the casting 11/13 of a block comprises an alloy of the composition range selected from the group of AA7040, AA7050 and AA7x75. 12. The method according to any one of the preceding claims, characterized in that the rolled alloy product is rolled to a final dimension in the range of 2 mm to 7 mm. 13. Use of an aluminum alloy sheet produced according to one of the preceding claims for a fuselage skin of an aircraft. For this 1 sheet drawings