ALUMINUM-COPPER-LITHIUM ALLOY PRODUCT FOR INNER SIDE ELEMENT WITH IMPROVED PROPERTIES

Abstract

The invention relates to a new product made of lithium copper aluminum alloy and methods for producing the same. The product is a rolled product with a final thickness of 15 mm to 50 mm, with a composition in % by weight Cu: 2.3 – 2.7; Li: 1.3 – 1.7; Mg: 0.2 – 0.5; Mn: 0.2 – 0.5; Ag: 0 – 0.1; Zn: < 0.20; Ti: 0.01 – 0.15; Zr < 0.07; Fe: ≤ 0.1; Si: ≤ 0.1; other elements ≤ 0.05 each and ≤ 0.15 in total, remainder aluminum and such that the sum of the volume fractions of the Cube texture components {001} <100> , Goss {011} <100> and CG26.5 {021} <100> at mid-thickness is less than or equal to 7.5%. It can be produced by hot rolling such that the thickness reduction of each of the last two passes is less than or equal to 10 mm, and where the final hot rolling temperature is between 400°C and 440°C. Abstract figure: Figure 2

Description

Title of the invention: ALUMINUM-COPPER-LITHIUM ALLOY PRODUCT FOR INNER SIDE ELEMENT WITH IMPROVED PROPERTIES Technical field

[0001] The present invention relates to aluminum alloy products and, more particularly, to such products, their methods of manufacture and use, in particular in the aerospace industry and preferably for wing intrados applications. Previous art

[0002] Rioja et al. in "The role of crystallographic texture on the performance of fiat rolled aluminum products for aerospace applications" - Light metals 2008 shows that alloy 2x24 or 2199 see their resistance to fatigue crack propagation under spectrum decrease as the elastic limit increases.

[0003] Prasad et al. in Aluminum-Lithium alloys - processing properties and applications - Elsevier edition 2014 in chapter 11 pp 341-375 mentions that fatigue improvement of lithium alloys is achieved by solid solution hardening and coalescence of delta prime precipitates. It is also possible to improve fatigue by thermal and thermomechanical treatments involving tempering (also known as artificial aging) and pre-tensioning or cold deformation before tempering.

[0004] EP3077559 discloses a method of manufacturing a rolled or forged material of which the thickness is 14 to 100 mm for wing intrados applications. Said material consists of an aluminum alloy composed, in % by weight, of: 1.8-2.6 Cu; 1.3-1.8 Li; 0.1-0.5 Mg; 0.1-0.5 Mn; Zr < 0.05, 0-0.5 Ag; Zn < 0.20; 0.01-0.15 Ti; Fe < 0.1; Si < 0.1; other elements < 0.05 each and < 0.15 in total, remainder aluminum whose density is less than 2.670 g / cm3. Said method comprises: homogenization; hot rolling under conditions such that the final temperature is at least 400°C, solution heating preferably by heat treatment between 490 and 530°C for 15 min to 8 h, then quenching typically with water. The sheet then undergoes controlled traction of 1 to 6%, then undergoes tempering at a temperature between 120 and 170°C for 5 to 100 h.

[0005] There is a need to improve the fatigue spectrum of such products while maintaining their tensile mechanical properties and toughness. Disclosure of the invention

[0006] An object of the invention relates to a manufacturing method improving the resistance in fatigue under spectrum of a rolled product in aluminum copper lithium with thickness ranging from 15 mm to 50 mm.

[0007] The manufacturing process comprises the following steps: (a) an aluminum alloy plate of composition, in % by weight, Cu: 2.3 - 2.7 is cast Li: 1.3-1.7 Mg: 0.2 - 0.5 Mn: 0.2 - 0.5 Ag: 0 - 0.1, preferably <0.05 Zn: < 0.20, preferably <0.05 Ti: 0.01-0.15 Zr <0.07, preferably <0.05 Fe: < 0.1 If: < 0.1 other elements < 0.05 each and < 0.15 in total, remainder aluminum, (b) The said cast plate is homogenized at a temperature of 480°C to 540°C for 5 to 60 hours. (c) Optionally, said homogenized plate is preheated from 420°C to 520°C, (d) said homogenized plate is hot rolled, optionally reheated, to obtain a rolled product having a final thickness of from 15 mm to 50 mm. The hot rolling is carried out in N successive passes such that the reduction in thickness of each of the last two passes is less than or equal to 10 mm. Preferably, the reduction in thickness of each of the last two passes is at least 1 mm, preferably at least 3 mm. Preferably, the average reduction in thickness of the last three passes is less than or equal to 10 mm. The final hot rolling temperature is between 400°C and 440°C. Preferably the hot rolling inlet temperature is between 420°C and 520°C, preferably between 450°C and 480°C. (e) said rolled product is put into solution, preferably by heat treatment at 490°C to 530°C for 15 min to 8 h, (f) quenching said solution-treated rolled product with water, (g) said solution-treated and hardened rolled product is pulled in a controlled manner with a permanent deformation of 2 to 5%, (h) said rolled product thus solution-treated, quenched and stretched is tempered by heating from 120 to 170°C for 5 to 100 hours.

[0008] Another subject of the invention relates to a rolled product made of lithium copper aluminum with a thickness of between 15 mm and 50 mm having a composition, in % by weight, Cu: 2.3 - 2.7 Li: 1.3 - 1.7 Mg: 0.2 - 0.5 Mn: 0.2 - 0.5 Ag: 0-0.1, Zn: < 0.20, Ti: 0.01-0.15 Zr <0.07, Fe: <0.1 Si: <0.1 other elements < 0.05 each and < 0.15 in total, remainder aluminum. The said product is characterized by a sum of the volume fractions of the texture components Cube {001} <100> , Goss {011} <100> and CG26.5 {021} <100> at mid-thickness less than or equal to 7.5%, preferably less than or equal to 7%.

[0009] Such a product can be obtained by the process according to the invention.

[0010] Preferably, the Zr content is less than or equal to 0.05% by weight, preferably less than or equal to 0.04% by weight. Preferably, the Ag content is less than or equal to 0.05% by weight. Preferably, the Zn content is less than or equal to 0.05% by weight.

[0011] Preferably, said rolled product has a moderately recrystallized granular structure at mid-thickness. Moderately recrystallized structure means a granular structure having a surface fraction of recrystallized grains between 20% and 50%. Figures

[0012] [Fig.l] [Fig.l] represents a table showing the different hot rolling passes corresponding to example 1.

[0013] [Fig.2] [Fig.2] represents the evolution of the number of flights measured in fatigue under spectrum as a function of the volume fraction of cube, Goss, CG26.5 orientations according to example 1. Detailed description of the invention

[0014] Unless otherwise stated, all statements of the chemical composition of alloys are expressed as a percentage by weight based on the total weight of the alloy. Designation of alloys is in accordance with the regulations of The Aluminium Association, known to those skilled in the art. Density depends on the composition and is determined by calculation rather than by a weight measurement method. Values ​​are calculated in accordance with the procedure of The Aluminium Association, which is described on pages 2-12 and 2-13 of "Aluminum Standards and Data". Definitions of the metallurgical states are given in the European standard EN 515.

[0015] Unless otherwise stated, the static mechanical characteristics, in other words the breaking strength Rm, the tensile yield strength Rpoj2 and the elongation at break A%, are determined by a tensile test according to the standard EN 10002-1 or NF EN ISO 6892-1. The location at which the parts are taken and their direction are defined by the standard EN 485-1. Unless otherwise stated, the definitions of the standard EN 12258 apply. The R curve is determined according to the standard ASTM 561-22. From the R curve, the critical stress intensity factor KC is calculated, i.e. the intensity factor which causes the instability of the crack. The stress intensity factor KCO is also calculated by assigning the initial crack length at the start of monotonic loading to the critical load. These two values ​​are calculated for a specimen of the desired shape.Kapp denotes the KCO corresponding to the test piece used to carry out the R curve test.

[0016] The products according to the invention are capable of being obtained by a process comprising the steps of casting, homogenization, hot rolling, solution treatment, quenching, controlled traction and tempering. The inventors have found that by modifying the hot rolling conditions, it is possible to improve the number of fatigue flights under spectrum.

[0017] An aluminum alloy plate according to the invention is cast.

[0018] The copper content of the alloy according to the invention is from 2.3% to 2.7%. Preferably the copper content is at least 2.4% or 2.5%, preferably at least 2.45% or even more preferably at least 2.50%. The maximum copper content is 2.6% or preferably 2.60 or 2.55% by weight.

[0019] The lithium content is from 1.3 to 1.7% by weight. Advantageously, the lithium content is at least 1.35% and preferably 1.40% by weight. Preferably, the lithium content is at most 1.65% or preferably 1.60% by weight.

[0020] The silver content is from 0 to 0.1% by weight. In one embodiment of the invention, the silver content is from 0.01 to 0.1% by weight. In another embodiment of the invention, which has the advantage of minimizing the density, the silver content is at most 0.05% by weight.

[0021] The magnesium content is from 0.2 to 0.5% by weight. Preferably the magnesium content is at most 0.4% by weight. In an advantageous embodiment of the invention the magnesium content is at least 0.20% by weight.

[0022] The manganese content is from 0.2 to 0.5%, preferably from 0.20 to 0.50%. Preferably, the manganese content is at least 0.25%, or even more preferably at least 0.30%. Preferably, the manganese content is at most 0.45%, or even more preferably at most 0.40%.

[0023] The zirconium content is less than 0.07% by weight. Preferably, the zirconium content zirconium is less than or equal to 0.05% by weight, even more preferably less than or equal to 0.04% by weight. Preferably the zirconium content is at least 0.01%.

[0024] The alloy also contains from 0.01 to 0.15% by weight of Ti and preferably from 0.02 to 0.10% by weight in particular to control the grain size during casting.

[0025] The zinc content is less than 0.20% by weight. Preferably the zinc content is less than or equal to 0.05% by weight, or even 0.04% by weight.

[0026] It is preferable to limit the content of unavoidable impurities in the alloy so as to achieve the most favorable damage tolerance properties. Unavoidable impurities include iron and silicon, these elements having a content of less than or equal to 0.1% by weight each, or even 0.08% by weight each. Preferably, the content of iron and silicon is less than or equal to 0.06% by weight each. The other elements considered as impurities have a content of less than or equal to 0.05% by weight each and 0.15% by weight in total. The remainder corresponds to aluminum.

[0027] The plate is cast by conventional casting techniques such as semi-continuous casting. The plate has a substantially parallelepiped shape. The plate preferably has a thickness of 300 mm or more, for example 400 mm, 500 mm or 600 mm or any other intermediate values. After casting, the plate is generally scalped to eliminate segregation zones near the surface while maintaining a substantially parallelepiped shape.

[0028] The cast plate is then homogenized. The homogenization treatment is carried out at a temperature of 480°C to 540°C for 5 to 60 hours. Preferably, the homogenization temperature is 495°C to 515°C.

[0029] After homogenization, the plate is generally cooled to room temperature before being preheated to a temperature of 420°C to 520°C for hot deformation by rolling. The preheating aims to reach an initial deformation temperature preferably between 420 and 520°C and preferably of the order of 450°C to 480°C allowing the deformation of the plate. However, it is also possible to roll the homogenized plate directly without prior preheating if it is not cooled and has a sufficient temperature, preferably between 420 and 520°C and preferably of the order of 450°C to 480°C.

[0030] Hot deformation is carried out by hot rolling so as to obtain a sheet with a final thickness th of between 15 mm and 50 mm. Preferably, the final thickness is at least 20 mm or 25 mm.

[0031] The hot rolling conditions are chosen such that the final hot deformation temperature is between 400°C and 440°C, preferably between 405°C and 435°C. To achieve this hot rolling exit temperature, The skilled person has various technical solutions at his disposal. Examples include the use of heating and / or cooling boxes to achieve an outlet temperature of at least 400°C. Heated rolling cylinders can also be used.

[0032] Hot rolling is carried out according to an N-pass rolling scheme where N is the number of passes. The number of passes N is preferably between 10 and 40 passes, preferably between 20 and 30 passes.

[0033] The inventors have found that it is possible to improve the fatigue strength under spectrum by adapting the rolling scheme so that the final thickness th is obtained by hot rolling in N passes and the thickness reduction of the last two passes is each less than or equal to 10 mm. Preferably, the thickness reduction of the last two passes is each less than or equal to 9 mm. Preferably, the thickness reduction of the last two passes is at least 1 mm, preferably at least 3 mm, even more preferably at least 5 mm.

[0034] The difference in thickness of the sheet between two consecutive rolling passes is called thickness reduction.

[0035] Preferably, the average thickness reduction of the last three passes is less than or equal to 10 mm, preferably less than or equal to 9 mm. Preferably, the average thickness reduction of the last three passes is at least 5 mm, preferably at least 6 mm.

[0036] The inventors found that by maintaining an exit hot rolling temperature of 400°C to 440°C and a rolling pattern such that the thickness reduction of the last two passes is each less than or equal to 10 mm, it was possible to obtain an improvement in the fatigue life under spectrum. The inventors attribute this behavior to the fact that such manufacturing parameters combined with the selected alloy composition make it possible to minimize the texture components parallel to the direction <100> on the final product. According to the invention, a texture component parallel to the direction <100> includes Cube texture {001} <100> , the Goss texture {011} <100> and the texture CG26.5 {021} <100> .

[0037] The sheet thus rolled is then solution-treated, preferably by heat treatment at 490 to 530°C for 15 min to 8 h, then quenched in water, typically water at room temperature, preferably below 40°C.

[0038] The product then undergoes a controlled traction of 2 to 5% and preferably at least 3%, typically around 4%.

[0039] An aging is then carried out at a temperature of 120 to 170°C for 5 to 100 hours, preferably 130 to 160°C for 30 to 90 hours.

[0040] Preferably the tempering is such that the equivalent time t_eq at 155°C is comprised of 30 to 60 hours. Preferably, the equivalent time t_eq at 155 °C is at least 32h, 34h, 36h. It may be interesting to aim for equivalent times t_eq at 155 °C of 30 to 40 hours in order to improve the elongation in the TL direction and the machinability of the product. In another preferred embodiment, the equivalent time t_eq at 155 °C is 45 to 55 hours in order to improve the thermal stability of the product.

[0041] The equivalent time t_eq at 155 °C is defined by the formula:

[0042] Jexp(-11400 / T) dt where T (in Kelvin) is the instantaneous temperature of ?-eCl ~ exp(-11400 / Tref) treatment, which evolves with time t (in hours), and Tref is a reference temperature fixed at 428 K (155°C). t_eq is expressed in hours. The constant Q / R = 11400 K is derived from the activation energy for Li diffusion, Q = 95000 J / mol. The formula giving t_eq takes into account the heating and cooling phases.

[0043] The preferred metallurgical states for the sheets are the T8 states, more particularly T84 or T86.

[0044] The rolled product thus obtained exhibits very good fatigue resistance under the spectrum in the LT direction. The inventors attribute this excellent behavior to the microstructure of the product, in particular its texture. Without being bound by any theory, the inventors believe that this better fatigue behavior under the spectrum can be attributed to the volume fraction of the texture components Cube {001} <100> , Goss {011} <100> and CG26.5 {021} <100> at mid-thickness. The inventors discovered that a product having a sum of volume fractions of the Cube texture components {001} <100> , Goss {011} <100> and CG26.5 {021} <100> less than or equal to 7.5%, preferably less than or equal to 7%, allows for improved fatigue resistance under spectrum. The volume fractions of the Cube {001} components <100> , Goss {011} <100> andCG26.5 {021} <100> are measured at mid-thickness.

[0045] The inventors believe that minimizing texture components having a direction <100> parallel to the rolling direction is favorable for increasing fatigue resistance under spectrum. Indeed, these texture components correspond to grains having potentially 8 activatable sliding systems (8 sliding systems with very similar Schmidt factors) when they are stressed in the rolling direction. The inventors believe that cracks propagate less easily and / or less quickly when the microstructure of the product has fewer grains oriented according to this type of texture.

[0046] Texture quantification can be done from global measurements by X-ray diffraction or from local measurements by electron backscatter diffraction (EBSD) in a scanning electron microscope (SEM). We can then access, via the calculation of the distribution function of the crystal orientations (FDOC), to the volume fractions of the different components present in the texture.

[0047] The FDOC can be calculated by the spherical harmonics method from the measured pole figures (preferably at least 4 pole figures). The size of the samples is adapted to the grain size of the material. Preferably, if an RX measurement is used, the size of the samples is chosen so as to be able to analyze at least 3000 grains, preferably 5000. If the EBSD technique is used, the size of the samples is chosen so as to be able to analyze at least a hundred grains, preferably at least 200 grains.

[0048] It is possible to simplify the information contained in the FDOC. This is commonly done in the art to describe selected aspects of the distribution of orientations in the material. An example of this practice is the calculation of the volume fraction of crystallites that have a specific orientation. To do this, reference orientations are defined as well as an angle of maximum misorientation around these orientations. The FDOC is then integrated into the domain thus defined, which makes it possible to deduce the relative volume of orientations contained in this domain compared to the total volume. The present inventors have used a tolerance of 15° around the Cube {001} orientations <100> , Goss {011} <100> andCG26.5 {021} <100> in order to describe the texture obtained.

[0049] The rolled product according to the invention has a final thickness th of between 15 mm and 50 mm, preferably the final thickness is at least 20 mm or 25 mm.

[0050] The rolled product according to the invention is a lithium copper aluminum alloy with a composition in % by weight Cu: 2.3 - 2.7; Li: 1.3-1.7; Mg: 0.2 - 0.5; Mn: 0.2 - 0.5; Ag: 0 - 0.1; Zn: < 0.20; Ti: 0.01 - 0.15; Zr <0.07; Fe: < 0.1; Si: < 0.1; other elements < 0.05 each and < 0.15 in total, remainder aluminum. Preferably, the Zr content is less than or equal to 0.05% by weight, preferably less than or equal to 0.04% by weight. Preferably, the Ag content is less than or equal to 0.05% by weight. Preferably, the Zn content is less than or equal to 0.05% by weight.

[0051] Preferably, the product has a moderately recrystallized granular structure at mid-thickness. Moderately recrystallized granular structure means a granular structure which has a surface fraction of recrystallized grains between 20% and 50%.

[0052] The measurement of recrystallized surface fraction can be measured by EBSD. According to the invention, a grain is considered recrystallized if it has a misorientation of at least 11° with the neighboring grain and the orientations within said grain (also called GOS for Grain Orientation Spread) have an extent of less than 3°. Examples

[0053] Example 1

[0054] Six compositions were cast in plate form (Table 1). All alloys have a composition according to the invention.

[0055] [Table 1] - Chemical composition (% by weight) Ref. 0.05 2.49 0.35 0.33 0.03 0.02 1.51 0.03 E 0.03 0.04 2.48 0.36 0.35 0.04 0.02 5 1.51 0.03 F 0.03 0.04 2.48 0.36 0.35 0.04 0.02 5 1.51 0.03 G 0.03 0.05 2.52 0.36 0.33 0.03 0.01 5 1.52 0.03

[0056] All the plates were homogenized for 12 hours at 508°C, then reheated to 492°C before hot rolling (HRL). The plates were hot rolled to a thickness of 23 mm to 35 mm. Table 2 shows the main hot rolling parameters. [Fig.l] shows the details of the rolling passes carried out. Plates B, C, D are reference plates. In particular, plate C is a reference plate already mentioned in patent EP3077559 (reference 3A in EP3077559). Plates E, F, G were hot rolled according to the invention. The thickness reduction of the last two passes (passes Nl and N) is less than 10 mm and the rolling exit temperature is between 400°C and 440°C. The average thickness reduction of the last three passes is less than 10 mm.

[0057] [Table 2] - Hot rolling conditions Ref. Initial thickness before LAC (mm) Final thickness after LAC (mm) Number of passes Total s LAC LAC Start (°C) LAC End (°C) Pass N-2 (mm) Pass Nl (mm) Pass N (mm) Average of the last 3 passes (mm) B Ref 366 23 24 430 340 16 14 8 13 C Ref 364 35 20 444 410 3 13 11 9 D Ref 366 32 34 422 353 8 9 8 9 E Inv 367 25 30 429 417 10 9 6 8 F Inv 366 25 27 455 407 9 7 5 7 G Inv 366 25 25 459 416 11 9 6 9

[0058] At the end of hot rolling (LAC), the sheets were solution-treated, then quenched, then stretched and then tempered for 80 hours at 140°C according to the conditions indicated in Table 3.

[0059] [Table 3] - Transformation conditions Reference Solution setting (duration - T°C) Traction (%) B 45' 497°C 4.2% C 45' 497°C 3.8% D 51'497°C 4.2% E 57' 497°C 4.0% F 57' 497°C 4.0% G 35' 497°C 3.8%

[0060] The static mechanical characteristics of the sheets were measured in the L and TL directions as well as the toughness on specimens of width 406 mm and thickness B = 6.35 mm, in the LT direction. Each of the sheets was also tested in fatigue under spectrum in the LT direction. The fatigue under spectrum is representative of the intrados conditions of a commercial aircraft according to the specification of an aircraft manufacturer on CCT type specimens, thickness 12 mm, length 700 mm and width 200 mm having a notch of 30 mm. The fatigue under spectrum characterization specimens were taken at mid-thickness of the sheet. The fatigue under spectrum results were obtained after pre-cracking by fatigue until the crack reaches 40 mm. The result obtained is the number of flights measured between 50 mm and 130 mm of crack propagation. The results are presented in Table 4.

[0061] [Table 4] - Mechanical properties Ref. Fatigue under spectrum Rm Rp0.2 E% Rm Rp0.2 E% Kapp number of flights (MPa) (MPa) (%) (MPa) (MPa) (%) (MPa-V m) LT LLL TL TL TL LT B Ref 6146 413 373 14.8 427 364 11.2 110 C Ref 6922 459 411 10.9 454 394 10.5 117 D Ref 6479 477 432 10.7 462 405 10.4 118 E Inv 7493 446 393 12.2 455 387 11.2 117 F Inv 7362 440 386 13.9 451 382 11.4 117 G Inv 7747 437 384 12.3 446 380 11.0 115

[0062] The sheets produced according to the invention E, F, G make it possible to achieve a higher number of fatigue flights under spectrum than the reference sheets. It is possible to increase the number of fatigue flights under spectrum by at least 6%, 8% or even 12% if we refer to the best of the reference cases (sheet C).

[0063] A texture measurement by EBSD was carried out on each of the sheets at mid-thickness in order to determine the texture and the recrystallized fraction of the tested sheets. The present inventors used a tolerance of 15° for each of the orientations considered. The volume fraction in % of the orientations, brass, copper and S, as well as the cube, Goss, CG 26.5 orientations for each of the sheets is given in Table 5.

[0064] [Table 5] - Results of texture measurements (volume fraction in %) Ref. Copper C {112} <111> Brass L {110} <112> S {123} <634> Sum C + L+S Cube {001} <100 Goss {011} <100> CG26.5 {021} <100> Sum Cube + Goss + CG26.5 % % % % % % % B Ref 1.6 6.9 7.9 16.4 4.1 4.0 4.2 12.3 C Ref 6.3 31.6 32.0 69.9 3.7 1.8 2.5 8.1 D Ref 5.1 21.0 25.5 51.5 3.3 2.0 2.8 8.1 E Inv 3.8 21.6 23.3 48.7 3.5 1.2 2.1 6.7 F Inv 3.8 22.0 22.8 48.5 3.4 1.7 2.3 7.4 G Inv 3.9 21.6 23.3 48.7 3.7 1.5 1.8 7.0

[0065] A correlation is observed between the number of fatigue flights under spectrum and the sum of the volume fractions of the Cube texture components {001} <100> , Goss {011} <100> and CG26.5 {021} <100> at mid-thickness ([Fig.2]). The inventors found that the improvement in fatigue under spectrum was inversely correlated with the value of the sum of the texture components Cube {001} <100> , Goss {011} <100> and CG26.5 {021} <100> at mid-thickness. The inventors discovered that a product having a sum of the volume fractions of the texture components Cube {001} <100> , Goss {011} <100> and CG26.5 {021} <100> at mid-thickness less than 7.5% improves fatigue resistance under the spectrum by at least 6%.

[0066] The sheets according to the invention were further characterized in such a way as to measure the recrystallized surface fraction at mid-thickness (Table 6). This measurement of recrystallized surface fraction was measured by EBSD. A grain is considered to be recrystallized if it has a misorientation of at least 11° with the neighboring grain and the orientation of said grain has an extent of less than 3°, also called Grain Orientation Spread (GOS).

[0067] [Table 6] - Result of recrystallized surface fraction at mid-thickness Ref. Recrystallized surface fraction t / 2 E Inv 31% F Inv 29% G Inv 39%

Claims

Claims

1. A method of manufacturing a rolled product of lithium copper aluminum alloy wherein: (a) an aluminum alloy plate of composition, in % by weight, is cast, Cu: 2.3 - 2.7 Li: 1.3-1.7 Mg: 0.2 - 0.5 Mn: 0.2 - 0.5 Ag: 0 - 0.1, preferably <0.05 Zn: < 0.20, preferably <0.05 Ti: 0.01-0.15 Zr <0.07, preferably <0.05 Fe: <0.1 If: < 0.1 other elements < 0.05 each and < 0.15 in total, aluminium remains, (b) said cast plate is homogenized at a temperature of 480°C to 540°C for 5 to 60 hours, (c) Optionally, said homogenized plate is preheated from 420°C to 520°C, (d) hot rolling said homogenized plate to obtain a rolled product having a final thickness of 15 mm to 50 mm, (e) solution heating said rolled product, preferably by heat treatment at 490°C to 530°C for 15 min to 8 h, (f) quenching said solution-treated rolled product with water, (g) said solution-treated and hardened rolled product is pulled in a controlled manner with a permanent deformation of 2 to 5%, (h) said rolled product thus solution-treated, quenched and stretched is tempered by heating from 120 to 170°C for 5 to 100 hours, characterized in that hot rolling is carried out in N successive passes such that the reduction in thickness of each of the last two passes is less than or equal to 10 mm, and where the final hot rolling temperature is between 400°C and 440°C.

2. A manufacturing method according to claim 1 such that the reduction in thickness of each of the last two passes is at least 1 mm, preferably at least 3 mm.

3. Manufacturing method according to claim 1 or 2 such that the average thickness reduction of the last three passes is less than or equal to 10 mm.

4. Manufacturing method according to any one of claims 1 to 3 such that the hot rolling inlet temperature is from 420°C to 520°C, preferably from 450°C to 480°C.

5. Rolled product with a final thickness of 15 mm to 50 mm made of lithium copper aluminum alloy having a composition, in % by weight, Cu: 2.3 - 2.7 Li: 1.3-1.7 Mg: 0.2 - 0.5 Mn: 0.2 - 0.5 Ag: 0-0.1 Zn: < 0.20 Ti: 0.01-0.15 Zr <0.07 Fe: <0.1 Si: <0.1 other elements < 0.05 each and < 0.15 in total, remains aluminum, characterized in that the sum of the volume fractions of the Cube texture components {001} <100> , Goss {011} <100> andCG26.5 {021} <100> at mid-thickness is less than or equal to 7.5%, preferably less than or equal to 7%.

6. Rolled product according to claim 5 characterized in that the Zr content is less than or equal to 0.05% by weight, preferably less than or equal to 0.04% by weight.

7. Rolled product according to claim 5 or 6 characterized in that the Ag content is less than or equal to 0.05% by weight.

8. Rolled product according to any one of claims 5 to 7 characterized in that the Zn content is less than or equal to 0.05% by weight.

9. Rolled product according to any one of claims 5 to 8 characterized in that at mid-thickness the granular structure of said product is moderately recrystallized, the granular structure has a surface fraction of recrystallized grains between 20% and 50%.