2XXX alloy kneadable products with optimized corrosion resistance and methods for their manufacture

Description

TECHNICAL FIELD

[0001] The present invention relates to a wrought product in 2XXX alloy having improved stress corrosion cracking properties and a thermo-mechanical treatment process for wrought products in 2XXX series aluminum alloys intended to improve their resistance to stress corrosion cracking while maintaining an excellent compromise between yield strength, ductility, and damage tolerance, in particular toughness. EARLIER ART

[0002] Aeronautical applications generally require a very specific set of properties. High mechanical strength alloys are generally desired, but depending on the intended use, other properties such as high tensile strength or ductility, as well as good corrosion resistance, are usually required, in particular, stress corrosion cracking resistance.

[0003] The stress corrosion cracking resistance of Alloy 2000 is evaluated by alternating immersion-immersion testing according to ASTM G47-98 (2019). Products larger than 30 mm are generally tested in tensile strength according to ASTM G49-85 (2019). Depending on the chosen device, the test is performed under constant strain or constant load. The choice depends on the intended application and selection criteria. As stated in ASTM G49-85 (2019), tensile stress corrosion cracking tests under constant load are more stringent than tensile stress corrosion cracking tests under constant strain. Therefore, the maximum allowable stress defined by a tensile stress corrosion cracking test under constant load is generally less than or equal to that determined by a tensile stress corrosion cracking test under constant strain.This difference is related to the fact that under constant deformation, particularly when a crack appears, there is a relaxation of stresses. The product is then subjected to a lower load than the initial load, making the test less severe. The article by N. Magaji et al., "Comparison of test methods used to analyze the stress corrosion cracking of differently tempered 7xxx alloys" - Materials and Corrosion 2019 - Vol. 70 - pp 1192-1204, can also be cited.

[0004] The 2000 series alloys are known from prior art. In this text, the term 2000 or 2xxx can be used interchangeably to refer to aluminum alloys in which Cu is the major element.

[0005] WO2004 / 106566 discloses an aluminium alloy having improved strength and ductility, comprising Cu 3.5 to 5.8 wt%, Mg 0.1 to 1.8 wt%, Mn 0.1 - 0.8 wt%, Ag 0.2 - 0.8 wt%, Ti 0.02 - 0.12 wt% and optionally one or more selected from the group consisting of Cr 0.1 - 0.8 wt%, Hf 0.1 - 1.0 wt%, Sc 0.03 - 0.6 wt%, and V 0.05 - 0.15 wt%, remaining aluminium, and wherein the alloy is substantially free of zirconium.

[0006] WO2020 / 123096 discloses a 2XXX alloy, with a titanium content between 0.08 and 0.20 wt%, which exhibits an excellent compromise of at least two characteristics, such as mechanical strength, toughness, elongation, and corrosion resistance. This application discloses stress corrosion testing carried out under constant deformation.

[0007] The standard practice for the final thermo-mechanical treatment of these alloys after hot rolling includes solution heating, the fastest possible quenching, cold straining of at least 2% and tempering with a single isothermal step.

[0008] The inventors found that products according to WO2004 / 106566 did not achieve a service life of more than 10 days after tensile stress corrosion testing under constant load at 200 MPa when these products were obtained according to the standard practice of thermo-mechanical processing.

[0009] FR2435535 discloses a heat treatment process for wrought aluminum alloy products of the 2000 series containing (by weight) 3.5 to 5% copper, 0.2 to 0.1% magnesium, and 0.25 to 1.2% silicon with a Si / Mg ratio greater than 0.8, characterized in that the tempering process comprises at least two stages: a primary tempering at a temperature above 225°C and below 285°C for a duration of between 6 seconds and 60 minutes, and a secondary tempering at a temperature between 120°C and 175°C for a duration of between 4 and 192 hours. FR2435535 differs from the invention in that it applies to products with a silicon content greater than 0.25% by weight and in that the first tempering stage is carried out at a temperature above 225°C.

[0010] US 3,305,410 discloses a two-step tempering heat treatment for aluminum alloys to improve corrosion resistance. This tempering is referred to as "high-low" tempering. The first step is carried out at a high temperature, typically between 190°C and 218°C, to initiate homogeneous precipitation and minimize precipitation at grain boundaries. The second step is carried out at a lower temperature, typically between 135°C and 163°C, to complete the precipitation. According to the invention, it is important that the hardening precipitation does not change significantly during the second step. This is achieved by selecting the tempering conditions according to the invention.

[0011] The invention relates to a thermo-mechanical treatment process applied to 2XXX alloys with the following composition by weight %: Cu 3.5 - 5.8; Mg 0.2 - 1.5; Mn ≤ 0.9; Fe ≤ 0.15; Si ≤ 0.15; Zr ≤ 0.25; Ag ≤ 0.8; Zn ≤ 0.8; Ti 0.02-0.15, with unavoidable impurities ≤ 0.05 each and ≤ 0.15 in total; and remaining aluminum. This process improves resistance to stress corrosion cracking while achieving an excellent compromise between yield strength, ductility, and damage tolerance, particularly toughness. Specifically, the process improves resistance to tensile stress corrosion cracking under constant load. DESCRIPTION OF THE INVENTION

[0012] The invention is described in the attached set of claims.

[0013] The invention relates to a thermo-mechanical treatment process for wrought aluminum alloy products of the 2000 series comprising, in weight %, Cu 3.5 - 5.8; Mg 0.2 - 1.5; Mn ≤ 0.9; Fe ≤ 0.15; Si ≤ 0.15; Zr ≤ 0.25; Ag ≤ 0.8; Zn ≤ 0.8; Ti 0.02-0.15, unavoidable impurities ≤ 0.05 each and ≤ 0.15 in total; remainder aluminum. This thermo-mechanical treatment comprises solution heating, quenching, work hardening, and tempering. The tempering is characterized in that it comprises at least two sequences: a first sequence whose temperature, expressed in °C, is described by a function T 1° C < ( t ) depending on time t, such that the maximum temperature reached T 1 max< is between 130°C and 180°C and the holding time t1 at a temperature between 130°C and 180°C is such that the equivalent time t 1 eq 160 ° is between 10 and 80 hours, equivalent duration t 1 eq 160 ° calculatedat a temperature of 160°C according to the formula t 1 eq 160 ° C = ∫ dt . exp − 136000 8 , 314 . 1 T 1 ° C t + 273 − 1 160 + 273 and a second sequence whose temperature, expressed in °C, is described by a function T 2 °C< (t) dependent on time t whose temperature is such that T 2 °C< ( t ) is less than T 1 max< and whose holding time t2, expressed in hours at a temperature between 100°C and 130°C, is such that the equivalent duration t 2 eq 160 ° calculated at a temperature of 160°C according to the formula t 2 eq 160 ° C = ∫ dt . exp − 136000 8 , 314 . 1 T 2 ° C t + 273 − 1 160 + 273 is between 0.3% and 15% of the equivalent duration t 1 eq 160 ° calculated for the first sequence.

[0014] In a preferred embodiment, the temperature T 2 °C< ( t ) of the second sequence is less than 130°C.

[0015] In a preferred embodiment, the holding time t2 of the second sequence, between 105°C and 130°C, preferably between 105°C and 125°C or between 110°C and 130°C, or between 110°C and 125°C, corresponds to an equivalent duration t 2 eq 160 ° between 0.3% and 15% of the equivalent duration t 1 eq 160 ° calculated for the first sequence.

[0016] Preferably, the equivalent duration t 2 eq 160 ° is greater than or equal to 0.4% of the equivalent duration t 1 eq 160 ° calculated for the first sequence, preferably the equivalent duration t 2 eq 160 ° is greater than or equal to 0.5%, 1%, 2%, or 3% of the equivalent duration t 1 eq 160 ° calculated at 160°C.

[0017] In a preferred embodiment, the equivalent duration t 2 eq 160 ° is less than or equal to 10% of the equivalent duration t 1 eq 160 ° calculated For the first sequence, the equivalent duration is even more preferred. t 2 eq 160 ° is less than or equal to 5%, or 3.5%.

[0018] Preferably, the first sequence comprises a single isothermal bearing. Preferably, the wrought product is a thin sheet, a thick sheet, a profile, or a forging. In a preferred embodiment, the wrought product is a thick sheet, a profile, or a forging with a thickness greater than or equal to 30 mm, preferably 50 mm, and even more preferably greater than or equal to 90 mm.

[0019] In a preferred embodiment, the wrought product is a thick sheet that has undergone a high-energy hydroforming shaping step prior to tempering, preferably explosion hydroforming.

[0020] The wrought product of the 2000 series aluminum alloy is preferably selected from the designations AA2139, AA2039, AA2040, AA2124, AA2024, AA2027, AA2022, AA2042. Preferably, the process is applied to a wrought product of the 2000 series aluminum alloy comprising, in % by weight, Cu 3.9 - 5.2; Mg 0.2 - 0.9; Mn 0.1 - 0.6; Fe ≤ 0.15; Si ≤ 0.15; Zr ≤ 0.15; Ag ≤ 0.6; Zn ≤ 0.8; Ti 0.02-0.15, unavoidable impurities ≤ 0.05 each and ≤ 0.15 in total; remainder aluminum. Preferably, the process is applied to a wrought product of 2000 series aluminum alloy comprising, in % by weight, Cu 4.5 - 5.0; Mg 0.40 - 0.90; Mn 0.20 - 0.50; Fe ≤ 0.15; Si ≤ 0.15; Zr ≤ 0.05; Ag 0.10 0.50; Zn ≤ 0.5; Ti 0.02-0.15, unavoidable impurities ≤ 0.05 each and ≤ 0.15 in total; remainder aluminium.

[0021] In an unclaimed embodiment, the value of the area of ​​the dissolution peak, after the second sequence, measured by DSC, with the dissolution peak between approximately 200°C and 300°C, is substantially equal to the value of the area of ​​the dissolution peak measured after the first sequence, by substantially equal means a difference less than or equal to 5%, advantageously less than or equal to 2%.

[0022] The invention also relates to a wrought product of 2000 series aluminum alloy with a thickness greater than or equal to 30 mm comprising in % by weight, Cu 3.5 - 5.8; Mg 0.2 - 1.5; Mn ≤ 0.9; Fe ≤ 0.15; Si ≤ 0.15; Zr ≤ 0.25; Ag ≤ 0.8; Zn ≤ 0.8; Ti 0.02-0.05, unavoidable impurities ≤ 0.05 each and ≤ 0.15 in total; remainder aluminum; capable of being obtained by the thermo-mechanical treatment process according to the invention. This product is characterized in that the average stress corrosion cracking life at a stress less than or equal to 200 MPa applied in the short transverse direction TC is greater than 10 days for three specimens per case, the tests being carried out according to the conditions of ASTM G47-98 (2019) using a tensile device under constant load according to ASTM G49-85 (2019).

[0023] Preferably, the wrought product of the 2000 series aluminum alloy with a thickness greater than or equal to 30 mm is such that the lifetime of all specimens tested in the short cross direction TC at a stress less than or equal to 200 MPa under the conditions of ASTM G47-98 (2019) using a tensile device under constant load according to ASTM G49-85 (2019) is greater than or equal to 10 days.

[0024] Preferably, the wrought product in 2000 series aluminum alloy with a thickness greater than or equal to 30 mm has a yield strength in the long transverse direction TL greater than or equal to 400 MPa.

[0025] In an unclaimed embodiment, the wrought product of the 2000 series aluminium alloy with a thickness greater than or equal to 30 mm comprises, in % by weight, Cu 3.9 - 5.2; Mg 0.2 - 0.9; Mn 0.1 - 0.6; Fe ≤ 0.15; Si ≤ 0.15; Zr ≤ 0.15; Ag ≤ 0.6; Zn ≤ 0.8; Ti 0.02-0.15, unavoidable impurities ≤ 0.05 each and ≤ 0.15 in total; remainder aluminium.

[0026] In an unclaimed embodiment, the wrought product of the 2000 series aluminium alloy with a thickness greater than or equal to 30 mm comprises, in % by weight, Cu 4.5 - 5.0; Mg 0.40 - 0.90; Mn 0.20 - 0.50; Fe ≤ 0.15; Si ≤ 0.15; Zr ≤ 0.05; Ag 0.10 - 0.50; Zn ≤ 0.5; Ti 0.02-0.15, unavoidable impurities ≤ 0.05 each and ≤ 0.15 in total; remainder aluminium.

[0027] Advantageously, the product according to the invention or obtained according to the process of the invention is used for aeronautical applications of integral structures such as fuselage, rib or spar elements. FIGURES

[0028] [ Fig. 1 ] There Figure 1 is a schematic representation of the revenue from an embodiment of the invention where the two sequences are carried out successively without going through a step at room temperature. Fig. 2 ] There Figure 2 shows a schematic representation of the revenue from an embodiment of the invention where the two sequences are carried out successively, passing through a stage at room temperature. Fig. 3 ] There Figure 3 shows a schematic representation of the revenue from one embodiment of the invention where the first sequence is a single step. Fig. 4 ] There Figure 4shows the thermograms obtained after differential scanning calorimetry (DSC) measurement on samples A13 and A14 from Example 6. Fig. 5 ] There Figure 5 illustrates the determination of the value of the dissolution peak area after DSC measurement. DETAILED DESCRIPTION OF THE INVENTION

[0029] Unless otherwise stated, all indications concerning the chemical composition of alloys are expressed as a percentage by weight based on the total weight of the alloy. The expression 1.4 Cu means that the copper content expressed as a percentage by weight is multiplied by 1.4. The designation of alloys is in accordance with the regulations of The Aluminium Association, which are known to those skilled in the art. Density depends on the composition and is determined by calculation rather than by a method of measurement by weight. The 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".

[0030] Unless otherwise stated, the definitions of metallurgical states given in the European standard EN 515 (1993) apply.

[0031] Unless otherwise stated, the static mechanical characteristics, in other words the tensile strength Rm, the conventional yield strength at 0.2% elongation Rp0.2 (“yield strength”) and the elongation at break A%, are determined by a tensile test according to standard EN 10002-1, the sampling and direction of the test being defined by standard EN 485-1.

[0032] Unless otherwise specified, the stress intensity factor (KQ) is determined according to ASTM E 399. ASTM E 399 provides the criteria for determining whether KQ is a valid value of K1C. For a given specimen geometry, KQ values ​​obtained for different materials are comparable provided that the yield strengths of the materials are of the same order of magnitude.

[0033] Stress corrosion cracking tests were performed according to ASTM G47-98 (2019) and ASTM G49-85 (2019) in the short cross-section (TC) direction for specimens centered at mid-thickness. Unless otherwise specified, stress corrosion cracking tests were performed using tensile test specimens. Typically, tensile test specimens are cylindrical with a diameter of 3.17 ±0.01 mm. However, flat specimens may also be used. These specimens were tested at a specified stress using a device that provided a constant load, as recommended by ASTM G49-85 (2019). At least three specimens were tested per case.

[0034] Unless otherwise specified, the terms used for aluminum and aluminum alloy products are defined by standard NF EN 12258-1. In particular, unless otherwise specified, a thin sheet is defined as a rolled product with a rectangular cross-section and a uniform thickness between 0.20 mm and 6 mm. A thick sheet is defined as a rolled product with a thickness greater than 6 mm.

[0035] A wrought product resistant to short-transverse stress corrosion cracking (STCC) means that the product exhibits no failure before 10 days of testing at a stress of 200 MPa applied in the short-transverse direction, using a device ensuring a constant load according to the recommendations of ASTM G49-85 (2019). The product according to the invention is resistant to short-transverse stress corrosion cracking. In a preferred mode, the product exhibits a mean lifetime and standard deviation such that the difference between the mean lifetime and the standard deviation is greater than 10 days.

[0036] Unless otherwise specified, tempering is a heat treatment designed to modify the properties of a product by precipitating intermetallic phases from a supersaturated solution. According to current best practices, it may consist of one or more stages. A "stage" is understood to be a heating phase, an isothermal holding phase, or a cooling phase. The heating and / or cooling phases may be linear and defined by a heating or cooling rate.

[0037] According to the invention, a "sequence" consists of one or more steps. A sequence can be defined by a temperature-time curve. T °C< (t) .

[0038] For a step or sequence, it is possible to calculate a holding time equivalent to a reference temperature T ref.

[0039] According to the invention, the tempering temperatures mentioned in the application are preferably with an accuracy of + / - 5°C, even more preferably + / - 3°C.

[0040] The duration of maintenance of a sequence defined by T °C< ( t ) during a time interval between t' and t" is equivalent to a duration t eq T ref of a sequence carried out at a reference temperature T ref. t eq T ref is defined by the formula: t eq T ref = ∫ t ′ t " dt . exp − Q R ⋅ 1 T ° C t + 273 − 1 T ref + 273 Or T °C< ( t ) is the instantaneous temperature in °C of a sequence that evolves with time t (in hours), and Tref is the reference temperature. t eq T ref is expressed in hours. The constant Q corresponds to the activation energy for diffusion. According to the invention, the constant Q is taken to be 136,000 J / mol, which corresponds to the activation energy of copper (Cu) diffusion in aluminum. The ideal gas constant R is equal to 8.314 J / K / mol.

[0041] The wrought product of the 2000 series aluminium alloy comprises in % by weight Cu 3.5 - 5.8; Mg 0.2 - 1.5; Mn ≤0.9; Fe ≤ 0.15; Si ≤ 0.15; Zr ≤ 0.25; Ag ≤ 0.8; Zn ≤ 0.8; Ti 0.02-0.15, unavoidable impurities ≤ 0.05 each and ≤ 0.15 in total; remainder aluminium.

[0042] The copper content is at least 3.5% by weight, preferably at least 3.9% by weight, advantageously at least 4.1%, and even more preferably at least 4.4% by weight to obtain sufficient yield strength. The copper content is at most 5.8% by weight, preferably at most 5.2%, advantageously at most 5.0% by weight. In one embodiment, the wrought product has a copper content between 3.9% and 5.2% by weight, advantageously between 4.5% and 5.0% by weight. Too low a copper content results in insufficient mechanical strength and yield strength. Too high a copper content results in insufficient toughness.

[0043] The magnesium content is at least 0.2% by weight, preferably at least 0.20% by weight, and advantageously at least 0.40% by weight. The magnesium content is at most 1.5% by weight, preferably at most 0.9%, and even more preferably 0.90% by weight. In one embodiment, the wrought product has a magnesium content between 0.2% and 0.9% by weight, and advantageously between 0.40% and 0.90% by weight. Too low a magnesium content results in insufficient mechanical strength and yield strength. Too high a magnesium content results in insufficient toughness.

[0044] The manganese content is preferably at least 0.05% by weight, more preferably at least 0.1%, and even more preferably at least 0.20% by weight. The manganese content is at most 0.9% by weight, preferably at most 0.6% by weight, and even more preferably at most 0.50% by weight. In one embodiment, the manganese content is between 0.1% and 0.6% by weight, preferably between 0.20% and 0.50% by weight. The addition of manganese helps control the growth of recrystallized grains, thereby increasing the mechanical strength of the product and its yield strength, but too high a content leads to a decrease in toughness.

[0045] The zinc content is at most 0.25% by weight, preferably at most 0.15% by weight, and even more preferably at most 0.05% by weight. In one embodiment, the zinc content is less than or equal to 0.04% by weight, advantageously the zinc content is less than or equal to 0.01% by weight. The inventors have found that a zinc content of less than or equal to 0.05% by weight improves the formability of the product. In another preferred embodiment, the zinc content is between 0.05% and 0.15% by weight.

[0046] The Ag content is at most 0.8% by weight, preferably at most 0.6%. In a preferred embodiment, the Ag content is between 0.10 and 0.50% by weight.

[0047] The Zn content is at most 0.8% by weight. In one embodiment, the Zn content is less than 0.5%, advantageously less than 0.25%.

[0048] The titanium content is between 0.02% and 0.05% by weight. Titanium helps control the casting microstructure, particularly by refining the grain size.

[0049] The other elements each contain at most 0.05% by weight and 0.15% by weight in total. These are unavoidable impurities; the rest is aluminum.

[0050] Advantageously, the wrought aluminum alloy product of the 2000 series is chosen from the designations AA2139, AA2039, AA2040, AA2124, AA2024, AA2027, AA2022, AA2042.

[0051] The wrought product made of aluminum alloy in the 2000 series is advantageously a thin sheet, a thick sheet, a profile, or a forging. In a preferred embodiment, the wrought product is a thick sheet of at least 30 mm, preferably 50 mm or more, and even more preferably 90 mm or more.

[0052] The wrought product in aluminum alloy of the 2000 series is obtained by a standard manufacturing process. A rough form is cast from a bath of liquid metal with the composition in % by weight Cu 3.5 - 5.8; Mg 0.2 - 1.5; Mn ≤0.9; Fe ≤ 0.15; Si ≤ 0.15; Zr ≤ 0.25; Ag ≤ 0.8; Zn ≤ 0.8; Ti 0.02-0.05, unavoidable impurities ≤ 0.05 each and ≤ 0.15 in total; remainder aluminum.

[0053] The raw form is advantageously a plate or a billet. The raw form is then homogenized and hot-formed to obtain a wrought product of aluminum alloy from the 2000 series. Advantageously, the homogenization is carried out at a temperature between 490°C and 530°C for a duration of 10 to 50 hours. Advantageously, in the case of a plate, the plate is homogenized and then hot-rolled to obtain a wrought product of aluminum alloy from the 2000 series. Advantageously, the wrought product of aluminum alloy from the 2000 series is a sheet with a thickness greater than or equal to 30 mm, preferably greater than or equal to 50 mm, and even more preferably greater than or equal to 90 mm. Advantageously, the wrought product in aluminum alloy of the 2000 series is a sheet with a thickness less than or equal to 180 mm, preferably less than or equal to 150 mm.

[0054] The wrought aluminum alloy product of the 2000 series, comprising (by weight percentages): Cu 3.5–5.8; Mg 0.2–1.5; Mn ≤ 0.9; Fe ≤ 0.15; Si ≤ 0.15; Zr ≤ 0.25; Ag ≤ 0.8; Zn ≤ 0.8; Ti 0.02–0.05, with unavoidable impurities ≤ 0.05 each and ≤ 0.15 in total; the remaining aluminum undergoes a thermomechanical treatment consisting of solution heating, quenching, work hardening, and tempering. Advantageously, the wrought product undergoes solution heating at a temperature between 490°C and 530°C for a duration of 5 to 20 hours. Advantageously, the tempering is carried out by immersing the product in solution in water at room temperature, classically around 22°C (+ / - 10°C) or by spraying the product.

[0055] Work hardening is then carried out. Advantageously, this work hardening is performed cold. It can be carried out by tension or compression. Advantageously, the permanent strain rate is between 1 and 9%, preferably between 3 and 5%.

[0056] Optionally, an additional forming step can be performed before tempering. This forming step can be carried out by a high-energy hydroforming process. Preferably, this process is performed on thick sheet metal, typically 30 mm or more thick, preferably 50 mm or more thick, and even more preferably 90 mm or more thick. This process can be an explosive hydroforming process. This type of process is described in the publication "Applications and capabilities of explosive forming" by DJ Mynor et al., Journal of Materials Processing Technology 125-126 (2002), pp. 1-25.

[0057] According to the invention, the wrought product undergoes a tempering process comprising at least two sequences. Preferably, the wrought product undergoes a tempering process comprising two sequences.

[0058] According to the request, when a temperature range is mentioned as "between 130°C and 180°C", this means that the temperature limits are inclusive. Therefore, when it is mentioned "between 130°C and 180°C", it should be understood to mean "from 130°C to 180°C". First sequence

[0059] The first sequence aims to obtain the final mechanical properties of the product. In particular, the first sequence is designed to achieve the best compromise between toughness and yield strength. According to the invention, the first sequence consists of one or more heating, and / or isothermal holding, and / or cooling stages. The temperature evolution during the first sequence can be described by a function T 1 °C< ( t ) depending on time t. During the first sequence, the temperature reaches a maximum temperature T 1 max< between 130°C and 180°C. Preferably the maximum temperature T 1 max< is reached during an isothermal plateau. The duration of the first sequence is such that the duration of maintenance at a temperature between 130°C and 180°C is equivalent to a duration equivalent t 1 eq 160 ° C between 10 and 80 hours, equivalent duration t 1 eq 160 ° C calculated at the reference temperature of 160°C according to the formula t 1 eq 160 ° C = ∫ dt . exp − 136000 8 , 314 ⋅ 1 T 1 ° C t + 273 − 1 160 + 273

[0060] The function is integrated over the time period during which the temperature, expressed in °C, is between 130°C and 180°C. That is, the function is integrated over the time period corresponding to the first time the temperature exceeds 130°C during ascent, and the first time it exceeds 130°C during descent. If the time period is discontinuous, the function must be integrated over each of the time periods during which the temperature is between 130°C and 180°C.

[0061] Preferably, the duration of maintenance at a temperature between 130°C and 180°C during the first sequence is equivalent to a duration t 1 eq 160 ° C of at least 15h, 20h, 24h, or 30h to obtain sufficient mechanical strength. Indeed, if the equivalent duration is too short, it is not possible to reach a sufficient yield strength, typically a yield strength of at least 400 MPa in the TL (Transverse Long) direction. Preferably, the holding time at a temperature between 130°C and 180°C during the first sequence is such that the equivalent duration t 1 eq 160 ° C is less than 70 hours, advantageously less than 60 hours, or 50 hours, or 40 hours in order to obtain sufficient ductility and toughness. Indeed, if the equivalent duration is too long, ductility and toughness decrease.

[0062] The first sequence may be preceded by a maturation step at room temperature. The duration of the maturation step may vary from a few minutes to a few hours or a few days. Preferably, the maturation time is between 10 minutes and 10 hours, preferably no more than 4 hours.

[0063] In a preferred embodiment of the invention, the first sequence is a single bearing (cf. Figure 3 A single-stage sequence is defined as a sequence comprising a single isothermal stage. Typically, a first single-stage sequence includes a temperature ramp-up stage, an isothermal holding stage between 130°C and 180°C, and a cooling stage. Second sequence

[0064] The second sequence aims to improve resistance to corrosion under stress.

[0065] According to the invention, the second sequence induces a negligible change in mechanical properties such as yield strength, tensile strength, or toughness. The yield strength, tensile strength, or toughness changes by less than 10% between the end of the first sequence and the end of the second sequence, advantageously by less than 5%, and even more advantageously by less than 3% or 2%. Preferably, the yield strength changes by less than 3%, preferably by less than 2%. Preferably, the toughness changes by less than 3%, preferably by less than 2%.

[0066] The inventors found that the second sequence does not significantly alter the amount of precipitate formed at the end of the first sequence.

[0067] Differential Scanning Calorimetry (DSC) is a thermal analysis technique. It measures the differences in heat exchange between a sample being analyzed and a reference (in this case, alumina). This DSC technique is based on the fact that during a physical transformation, such as a phase transition, a certain amount of heat is exchanged with the sample to maintain it at the same temperature as the reference. The direction of this heat exchange between the sample and the equipment depends on whether the transition process is endothermic or exothermic. For example, if a product contains precipitates, these precipitates may dissolve within a specific temperature range when heated. The product will then absorb more heat to increase its temperature at the same rate as the reference.The dissolution of precipitates is an endothermic phase transition because it absorbs heat. Similarly, the sample can undergo exothermic processes, such as precipitation, when it transfers heat to the system.

[0068] By measuring the difference in heat flow between the sample and the reference, a differential scanning calorimeter can measure the amount of heat absorbed or released during a transition.

[0069] Using this technique, it is possible to estimate the quantity of dissolved phases from the thermogram by calculating the area of ​​the endothermic peak or dissolution peak, expressed in J / g. This dissolution peak according to the invention is between approximately 200°C and 300°C. By "approximately 200°C and 300°C," it is meant that the dissolution peak can extend within a range of + / - 50°C relative to the 200°C-300°C range.

[0070] The inventors observed that the area of ​​the dissolution peak varies by less than 5% between the two sequences. Indeed, they found that the area of ​​the dissolution peak after the second sequence, measured by DSC (dissolution peak temperature between approximately 200°C and 300°C), is substantially equal to the area of ​​the dissolution peak measured after the first sequence. By substantially equal, they mean a difference of less than or equal to 5%, advantageously less than or equal to 2%.

[0071] According to the invention, the second sequence consists of one or more heating, and / or isothermal maintenance and / or cooling stages.

[0072] The temperature evolution during the second sequence can be described by a time-dependent function T 2 °C< ( t The second sequence is carried out at a temperature T2 lower than the maximum temperature T 1 max<of the first sequence. That is to say, during the second sequence, the function T 2 °C< (t) is below the maximum temperature T 1 max< Preferably the second sequence is carried out at a temperature T2 below 130°C, even more preferably below 125°C.

[0073] The second sequence is characterized by a holding time t2 at a temperature between 100°C and 130°C. This holding time t2 at a temperature between 100°C and 130°C can be defined by an equivalent duration t 2 eq 160 ° calculated at a temperature of 160°C according to the formula t 2 eq 160 ° C = ∫ dt . exp − 136000 8 , 314 . 1 T 2 ° C t + 273 − 1 160 + 273

[0074] The temperature T 2 °C< (t) is expressed in °C.

[0075] The function is integrated within the time frame where the product is maintained between 100°C and 130°C after the first sequence. According to the invention, the equivalent duration t 2 eq 160 ° The calculated duration is less than or equal to 15% of the equivalent duration. t 1 eq 160 ° calculated for the first sequence. Preferably, the second sequence is characterized by a holding time t2 at a temperature between 105°C and 130°C, or between 105°C and 125°C, or between 110°C and 130°C, or between 110°C and 125°C, such that the equivalent duration t 2 eq 160 ° calculated at 160°C is less than or equal to 15% of the equivalent duration t 1 eq 160 ° calculated at 160°C for the first sequence.

[0076] Prolonged maintenance at a temperature below 100°C, preferably below 105°C, even more preferably 110°C, does not improve corrosion resistance in the short transverse direction.

[0077] The equivalent duration t 2 eq 160 ° calculated at a temperature of 160°C, corresponding to the duration of maintenance t2 at a temperature between 100°C and 130°C, or between 105°C and 130°C, or between 105°C and 125°C, or between 110°C and 130°C, or between 110°C and 125°C is less than or equal to 15% of the equivalent duration t 1 eq 160 ° calculated for the first sequence.

[0078] Preferably, the equivalent duration t 2 eq 160 ° corresponding to the duration of maintenance t2 at a temperature between 100°C and 130°C or between 105°C and 130°C, or between 105°C and 125°C, or between 110°C and 130°C, or between 110°C and 125°C is less than or equal to 10%, 5%, or 3.5% of the equivalent duration t 1 eq 160 ° calculated at 160°C for the first sequence.

[0079] The inventors observed that stress corrosion cracking of the wrought product is improved if the second sequence is such that a sufficient duration between 100°C and 130°C is maintained. The equivalent duration t 2 eq 160 ° calculated at 160°C is greater than or equal to 0.3%. An equivalent duration t 2 eq 160 ° A concentration below 0.3% is insufficient to desensitize the product to stress corrosion cracking. Even more preferably, the equivalent duration t 2 eq 160 ° is greater than or equal to 0.4%, 0.5%, 1%, 2% or 3% of the equivalent duration t 1 eq 160 ° calculated at 160°C for the first sequence.

[0080] In one embodiment of the invention, the first and second sequences are performed successively without passing through ambient temperature between them. In this case, the start of the second sequence occurs when the temperature T 1 °C< ( t ) is less than 130°C as shown in the Fig. 1 .

[0081] In another embodiment of the invention, the first and second sequences are performed successively with a period of holding at room temperature between them. In this case, the start of the second sequence occurs when the temperature T 1 °C< (t) is less than 130°C as shown in the Fig. 2 The holding time t2 is equal to the sum of the holding times of the sequences within the temperature range of 100°C to 130°C. The wrought product obtained according to the invention is suitable for aeronautical applications, particularly for components made of integral structures. An integral structure is defined as a monolithic structure consisting of a skin and a stiffener in a single piece. The wrought product obtained according to the invention is advantageously used for integral structures, such as fuselage, rib, or spar elements.

[0082] The inventors observed that the thermo-mechanical treatment according to the invention provides improved resistance to stress corrosion cracking. In a preferred embodiment, the thermo-mechanical treatment is particularly advantageous for wrought products with a thickness greater than or equal to 30 mm, preferably greater than or equal to 50 mm or 90 mm, such as thick sheet metal, profiles, or forged products for which resistance to stress corrosion cracking in the short transverse direction (TC) is required.A wrought product of the 2000 series aluminium alloy with a thickness greater than or equal to 30 mm comprising in % by weight, Cu 3.5 - 5.8; Mg 0.2- 1.5; Mn ≤ 0.9; Fe ≤ 0.15; Si ≤ 0.15; Zr ≤ 0.25; Ag ≤ 0.8; Zn ≤ 0.8; Ti 0.02-0.05, unavoidable impurities ≤ 0.05 each and ≤ 0.15 in total; remainder aluminium; capable of being obtained by the thermo-mechanical treatment process according to the invention allows obtaining an average stress corrosion cracking life at a stress less than or equal to 200 MPa imposed in the short transverse direction TC greater than 10 days. The tests are performed according to the conditions of ASTM G47-98 (2019) using a tensile device under constant load according to ASTM G49-85 (2019).In particular, in a preferred embodiment, the difference between the average service life and the standard deviation measured during the test is greater than 10 days, with the tests performed according to the conditions of ASTM G47-98 (2019) using a tensile device under constant load according to ASTM G49-85 (2019). This product exhibits a long transverse yield strength (TL) greater than or equal to 400 MPa.

[0083] The product according to the invention is used for aeronautical applications of integral structures such as fuselage, rib or spar elements. EXAMPLES Example 1

[0084] An AA2139 alloy, the composition of which is given in Table 1, was hot-rolled to a final thickness of 120 mm after homogenization at a temperature between 490°C and 530°C for 10 to 50 hours. The sheet was then solution-cured at 490°C to 530°C for 5 to 20 hours, followed by quenching and controlled tensile stress relieving to achieve a permanent deformation of 2 to 4%. The sheet was then stress-corrosion tested after various tempering processes as indicated in Table 2.

[0085] The equivalent times, as defined according to the invention, are calculated taking into account the isothermal plateaus and the temperature rise and fall phases.

[0086] Revenues consisting of only one sequence are carried out with a heating rate of 40°C / h up to 150°C, then at 20°C / h up to 160°C. The cooling rate is 30°C / h.

[0087] Revenues involving two phases are carried out with the same heating and cooling rates. The two phases are performed consecutively without a period of holding at room temperature. [Table 1] If Fe Cu Mn Mg Ti Ag Zr Alloy A 0.04 0.08 4.8 0.3 0.5 0.05 0.33 <0.05 [Table 2] Reference Income Time equivalent to 160°C (h) Ratio of 2nd sequence to 1st sequence (%) 1st sequence 2nd sequence A5 160°C 36h 36.76 0.02 0.05 A6 160°C for 36 hours + 120°C for 20 hours 36.76 0.45 1.22 A7 160°C 48h 48.76 0.02 0.04 A8 160°C for 48 hours + 120°C for 20 hours 48.76 0.45 0.92

[0088] Stress corrosion cracking (SCC) tests were performed in the short transverse direction of the sheet according to the conditions of ASTM G47-98 (2019) using tensile specimens under an applied stress of 200 MPa. The specimens were subjected to immersion-emergence cycles in a 3.5% NaCl saline solution according to the conditions of ASTM G44-99 (2013). The tests were performed under constant load according to the recommendations of ASTM G49-85 (2019). The 3.17 mm diameter tensile specimens were taken from mid-thickness of the sheet. The results are presented in Table 3.

[0089] The sheets were tested to determine their static mechanical properties and toughness. The yield strength Rp0.2, tensile strength Rm, and elongation at break A, in the TL direction, are presented in Table 4. Tensile test specimens were taken from half their thickness, and the toughness test specimens used were CT20W40 (thickness B = 20 mm, width W = 40 mm according to ASTM E399) taken from one-quarter their thickness. In addition to the Kq value obtained according to ASTM E399, the Kapp value is used as a test result. This is the stress intensity factor obtained for the tested specimen using the maximum load recorded during the test as the load, and the initial crack length after fatigue pre-cracking as the crack length; this is the same length used for the calculation of Kq. [Table 3] Ref. Income Constraint Duration Minimum Average Standard deviation sigma mean-1*sigma (MPa) (Days) (Days) (Days) (Days) (Days) A5 160°C 36h 200 7 7 7 1 6 200 7 200 8 A6 160°C for 36 hours + 120°C for 20 hours Invention 200 23 16 23 7 16 200 16 200 30 A7 160°C 48h 200 14 9 18 11 7 200 30 200 9 A8 160°C for 48 hours + 120°C for 20 hours Invention 200 30 14 25 9 15 200 30 200 14

[0090] The products tested according to inventions A6 and A8 exhibit a longer average lifespan than products obtained after single-stage heating. None of the tested specimens has a lifespan of less than 10 days. The products tested according to inventions A6 and A8 have an average lifespan and a standard deviation such that the difference between the mean and the standard deviation is greater than 10 days. [Table 4] Ref Income R0.2 (MPa) Rm (MPa) A (%) Kapp (MPa. √m) Kq (MPa. √m) TL - T / 2 TL SL TL SL A5 160°C 36h 400 445 9,2 37 33 36 33 A6 160°C for 36 hours + 120°C for 20 hours Invention 402 449 9,1 37 37 A7 160°C 48h 401 447 8,9 37 33 37 33 A8 160°C for 48 hours + 120°C for 20 hours Invention 408 451 8 37 37 Example 2

[0091] The same sheet as in Example 1 was tested under other tempering conditions as indicated in Table 5. Stress corrosion tests were carried out under the same conditions as in Example 1. The results are shown in Table 6. [Table 5] Reference Income Time equivalent to 160°C (h) Ratio of 2nd sequence to 1st sequence (%) 1st sequence 2nd sequence A11 160°C for 36 hours + 93°C for 100 hours 36.76 0.02 0.05 A12 160°C for 36 hours + 120°C for 5 hours 36.76 0.13 0.35 [Table 6] Ref. Income Constraint Duration Minimum Average Standard deviation sigma average-1 sigma (MPa) (Days) (Days) (Days) (Days) (Days) A11 160°C for 36 hours + 93°C for 100 hours 200 8 8 9 2 7 200 12 200 8 A12 160°C for 36 hours + 120°C for 5 hours Invention 200 28 15 25 9 16 200 32 200 15

[0092] The product tested according to invention A12 has a significantly longer average lifespan than product A11 obtained after a tempering process comprising two sequences, but whose holding time t2 at a temperature between 100°C and 130°C is equivalent to a similar duration. t 2 eq 160 ° less than 0.3% of the equivalent time duration t 1 eq 160 ° calculated for the first sequence. None of the test specimens tested for reference A12 have a shelf life of less than 10 days. The product tested according to invention A12 has a mean shelf life and a standard deviation such that the difference between the mean and the standard deviation is greater than 10 days. Example 3

[0093] This example is according to claim of process 1 but the product is not part of the subject matter of the invention according to claim of product 12.

[0094] An AA2139 alloy, the composition of which is given in Table 7, was hot-rolled to a final thickness of 120 mm after homogenization at temperatures between 490°C and 530°C for 10 to 50 hours. The sheet was then solution-cured at temperatures between 490°C and 530°C for 5 to 20 hours, followed by quenching and stress relieving under controlled tensile stress to achieve a permanent deformation of 2 to 4%. The sheet was then stress-corrosion tested after various tempering processes as indicated in Tables 8 and 9. [Table 7] If Fe Cu Mn Mg Ti Ag Zr Alloy B 0.05 0.09 4.9 0.3 0.5 0.09 0.32 <0.05

[0095] Stress corrosion tests were carried out under the same conditions as in example 1. [Table 8] Reference Income Time equivalent to 160°C (h) Ratio of 2nd sequence to 1st sequence (%) 1st sequence 2nd sequence B5 160°C 36h 36.76 0.02 0.05 B6 160°C for 36 hours + 120°C for 20 hours 36.76 0.45 1.22 [Table 9] Ref. Income Constraint Duration Minimum Average Standard deviation sigma average-1 sigma (MPa) (Days) (Days) (Days) (Days) (Days) B5 160°C 36h 200 3 3 3 0 3 200 3 200 3 B6 160°C for 36 hours + 120°C for 20 hours invention 200 >30 NR 16 >21 200 16 200 16

[0096] The two-sequence income according to the invention leads to a significantly improved resistance to stress corrosion cracking. Example 4

[0097] Stress corrosion cracking tests were performed on an AA2139 steel plate identical to Example 1, which had undergone a single-step tempering process of 36 hours at 160°C. The plate was tested in the short transverse direction under constant load at 200 MPa of applied stress and under constant strain at 276 MPa of applied stress. The results are shown in Table 10. [Table 10] Ref. Income Constraint Duration Minimum Average Standard deviation average-1 sigma (MPa) (Days) (Days) (Days) (Days) (Days) A5 160°C 36h Constant load 200 7 7 7 1 6 200 7 200 8 Constant deformation 276 13 12 12 1 11 276 12 276 12

[0098] It is observed that tests under constant deformation result in a longer average lifespan than those obtained under constant load, despite a higher applied stress. This example confirms that tests under constant deformation are less demanding than those performed under constant load. Example 5

[0099] The same sheet metal shown in Example 1 was tested for stress corrosion cracking under marine conditions. The tests consisted of placing tensile test specimens in a marine atmosphere under a constant load of 200 MPa. This corresponds to the same stress conditions as those used in Example 1 and complies with the requirements of ASTM G49-85 (2019).

[0100] The resistance to stress corrosion under marine exposure of the sheet metal was tested for two tempering conditions, identical to those presented in example 1, and corresponding to single-step tempering 36h at 160°C and tempering according to the invention 36h at 160°C + 20h at 120°C.

[0101] The results are presented in Table 11. [Table 11] Ref. Income Constraint Duration (MPa) (Days) A5 160°C 36h 200 25 200 17 200 67 A6 160°C for 36 hours + 120°C for 20 hours invention 200 >540 200 >540 200 >540

[0102] The sheet metal that has undergone tempering according to the invention exhibits improved resistance to stress corrosion cracking in a marine atmosphere. After 18 months of exposure (approximately 540 days), none of the test specimens broke. Example 6

[0103] Stress corrosion tests were performed on a sheet of AA2139 steel identical to Example 1, which had undergone single-stage and two-stage tempering according to the invention. The single-stage tempering process consists of a single sequence and is carried out with a heating rate of 40°C / h up to 150°C, then 20°C / h up to 168°C. The cooling rate is 30°C / h. The tempering process according to the invention, which consists of two sequences, underwent the same heating and cooling rates for the first sequence as the single-stage tempering process. The second sequence is carried out immediately after the first sequence without passing through ambient temperature. After the second sequence is completed, the sheet is cooled at 30°C / h. [Table 12] Reference Income Time equivalent to 160°C (h) Ratio of 2nd sequence to 1st sequence (%) 1st sequence 2nd sequence A13 168°C 6pm 37.43 0.02 0.05 A14 168°C 18h + 120°C 5h 37.43 0.13 0.35

[0104] The products were tested in the short transverse direction under a constant load of 200 MPa of applied stress. The results are illustrated in Table 13. [Table 13] Ref. Income Constraint Duration Minimum Average Standard deviation sigma average-1 sigma (MPa) (Days) (Days) (Days) (Days) (Days) A13 168°C 6pm 200 4 1 3 2 1 200 5 200 1 A14 168°C 18h + 120°C 5h Invention 200 11 11 20 10 10 200 19 200 30

[0105] Differential scanning calorimetry (DSC) measurements were performed on both products A13 and A14. figure 4 represents the thermograms obtained. We observe that the two thermograms are similar.

[0106] We observe ( figure 4In both cases, a dissolution peak (10, 10') is located between 200°C and 300°C. The precipitates present dissolve during heating, which is accompanied by a decrease in the measured enthalpy. The amount of precipitate present at the time of heating is estimated by integrating the area of ​​the peak located below the baseline of the curve. The baseline represents the evolution of enthalpy with temperature if the sample underwent no physical transformation. This baseline can be obtained using the baseline of the reference sample, which undergoes no physical transformation in the temperature range considered. It can also be estimated by extrapolating the measured curve (see Figure 5 ). In the case of the example, a dissolution peak area of ​​4.98 J / g is measured for sample A13 and a dissolution peak area of ​​4.90 J / g for sample A14. The difference between the two is 1.6%.

[0107] The amount of precipitate formed during tempering is similar for both heat treatments considered. However, an improvement in corrosion resistance is clearly observed for sample A14, which underwent tempering according to the invention.

Claims

1. A method for thermomechanical treatment of wrought products made of a 2000 series aluminum alloy comprising, in % by weight, Cu 3.5 - 5.8; Mg 0.2 - 1.5; Mn ≤ 0.9; Fe ≤ 0.15; Si ≤ 0.15; Zr ≤ 0.25; Ag ≤ 0.8; Zn ≤ 0.8; Ti 0.02-0.15 unavoidable impurities ≤ 0.05 each and ≤ 0.15 total; remainder aluminum, which thermomechanical treatment comprises placing in solution, quenching, work hardening, and tempering characterized in that the tempering comprises at least two sequences, a first sequence whose temperature expressed in °C is described by a function T1°C (t) dependent on the time t, such that the reached maximum temperature T1max is comprised between 130°C and 180°C and the hold time t1 at a temperature comprised between 130°C and 180°C is such that the equivalent duration t 1 eq 160 ° is comprised between 10h and 80h, which equivalent duration t 1 eq 160 ° is calculated at a temperature of 160°C according to the formula t 1 eq 160 ° C = ∫ dt . exp − 136000 8 , 314 ⋅ 1 T 1 ° C t + 273 − 1 160 + 273 and a second sequence whose temperature expressed in °C is described by a function T2°C (t). dependent on the time t whose temperature is such that T2°C(t) < T1max and whose hold time t2 at a temperature comprised between 100°C and 130°C is such that the equivalent duration t 2 eq 160 ° calculated at a temperature of 160°C according to the formula t 2 eq 160 ° C = ∫ dt . exp − 136000 8 , 314 ⋅ 1 T 2 ° C t + 273 − 1 160 + 273 is comprised between 0.3% and 15% of the equivalent duration t 1 eq 160 ° calculated for the first sequence.

2. The thermomechanical treatment method according to claim 1, where the temperature of the second sequence T2°C (t) is lower than 130°C.

3. The thermomechanical treatment method according to claim 1 or 2, characterized in that the hold time t2 of the second sequence comprised between 105°C and 130°C corresponds to an equivalent duration t 2 eq 160 ° comprised between 0.3% and 15% of the equivalent duration t 1 eq 160 ° calculated for the first sequence.

4. The thermomechanical treatment method according to any one of claims 1 to 3, characterized in that the equivalent duration t 2 eq 160 ° is longer than or equal to 0.5%, preferably longer than or equal to 1%; of the equivalent duration t 1 eq 160 ° calculated for the first sequence.

5. The thermomechanical treatment method according to any one of claims 1 to 4, characterized in that the equivalent duration t 2 eq 160 ° is shorter than or equal to 10%, preferably shorter than or equal to 5%, of the equivalent duration t 1 eq 160 ° calculated for the first sequence.

6. The thermomechanical treatment method according to any one of claims 1 to 5, characterized in that the first sequence comprises a single isothermal step level.

7. The thermomechanical treatment method according to any one of claims 1 to 6, characterized in that the wrought product is a thin sheet metal or a thick sheet metal or a profile or a forged part.

8. The thermomechanical treatment method according to any one of claims 1 to 7, characterized in that the wrought product is a thick sheet metal having undergone a forming step by high-energy hydroforming before tempering.

9. The thermomechanical treatment method according to any one of claims 1 to 8, characterized in that the wrought product made of a 2000 series aluminum alloy is selected from among AA2139, AA2039, AA2040, AA2124, AA2024, AA2027, AA2022, AA2042.

10. The thermomechanical treatment method according to any one of claims 1 to 8, characterized in that the wrought product made of a 2000 series aluminum alloy comprises, in % by weight, Cu 3.9 - 5.2; Mg 0.2 - 0.9; Mn 0.1 - 0.6; Fe ≤ 0.15; Si ≤ 0.15; Zr ≤ 0.15; Ag ≤ 0.6; Zn ≤ 0.8; Ti 0.02-0.15 unavoidable impurities ≤ 0.05 each and ≤ 0.15 total; remainder aluminum.

11. The thermomechanical treatment method according to any one of claims 1 to 8, characterized in that the wrought product made of a 2000 series aluminum alloy comprises, in % by weight, Cu 4.5 - 5.0; Mg 0.40 - 0.90; Mn 0.20 - 0.50; Fe ≤ 0.15; Si ≤ 0.15; Zr ≤ 0.05; Ag 0.10 - 0.50; Zn ≤ 0.5; Ti 0.02 - 0.15 unavoidable impurities ≤ 0.05 each and ≤ 0.15 total; remainder aluminum.

12. A wrought product made of a 2000 series aluminum alloy with a thickness larger than or equal to 30 mm comprising, in % by weight, Cu 3.5 - 5.8; Mg 0.2 - 1.5; Mn ≤ 0.9; Fe ≤ 0.15; Si ≤ 0.15; Zr ≤ 0.25; Ag ≤ 0.8; Zn ≤ 0.8; Ti 0.02 - 0.05 unavoidable impurities ≤0.05 each and ≤0.15 total; remainder aluminum; obtainable by the thermomechanical treatment method according to one of claims 1 to 8, characterized in that the average service life under corrosion at a stress lower than or equal to 200 MPa applied in the short transverse direction TC is longer than 10 days for three specimens per case, the tests being carried out according to the conditions of ASTM G47 - 98 (2019) using a tensioning device under constant load according to ASTM G49 - 85 (2019) and wherein the lifespan of all the specimens is longer than or equal to 10 days.

13. The wrought product made of a 2000 series aluminum alloy with a thickness larger than or equal to 30 mm, according to claim 12, the yield strength of which in the long transverse direction TL is higher than or equal to 400 MPa.

14. A use of a wrought product according to one of claims 12 to 13 or obtained according to one of claims 1 to 11 for aeronautical applications of integral structures such as fuselage, rib or spar elements.