EP3201371B1 - Method of fabrication of a wrought product of an alloy of aluminium- magnesium-lithium, wrougt product and use of the product - Google Patents

Method of fabrication of a wrought product of an alloy of aluminium- magnesium-lithium, wrougt product and use of the product Download PDF

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EP3201371B1
EP3201371B1 EP15785160.1A EP15785160A EP3201371B1 EP 3201371 B1 EP3201371 B1 EP 3201371B1 EP 15785160 A EP15785160 A EP 15785160A EP 3201371 B1 EP3201371 B1 EP 3201371B1
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product
mpa
alloy
process according
weight
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German (de)
French (fr)
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EP3201371A1 (en
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Gaëlle POUGET
Bernard Bes
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Constellium Issoire SAS
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Constellium Issoire SAS
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Priority claimed from FR1402186A external-priority patent/FR3026411B1/en
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
    • C22F1/047—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with magnesium as the next major constituent
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C22C21/06—Alloys based on aluminium with magnesium as the next major constituent
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C22C21/06—Alloys based on aluminium with magnesium as the next major constituent
    • C22C21/08—Alloys based on aluminium with magnesium as the next major constituent with silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/002—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working by rapid cooling or quenching; cooling agents used therefor

Definitions

  • the invention relates to a process for manufacturing a wrought aluminum-magnesium-lithium alloy product, more particularly to a process for manufacturing such a product exhibiting an improved compromise in properties, in particular an improved compromise between tensile yield strength. and toughness of said products.
  • the subject of the invention is also a product capable of being obtained by said manufacturing process and its use, said product being intended in particular for aeronautical and aerospace construction.
  • Wrought aluminum alloy products are developed to produce high strength parts intended in particular for the aeronautical industry and the aerospace industry.
  • Aluminum alloys containing lithium are of great interest in this regard, as lithium can reduce the density of aluminum by 3% and increase the modulus of elasticity by 6% for each weight percent lithium added.
  • aluminum alloys simultaneously containing magnesium and lithium make it possible to achieve particularly low densities and have therefore been extensively studied.
  • the patent GB 1,172,736 teaches an alloy containing, in weight percent, 4-7% Mg, 1.5 - 2.6% Li, 0.2 - 1% Mn and / or 0.05 - 0.3% Zr, remains aluminum. This alloy is useful for producing products with high mechanical strength, good corrosion resistance, low density and high modulus of elasticity. Said products are obtained by a process comprising optional quenching followed by tempering. By way of example, the products resulting from the process according to GB 1,172,736 present a tensile strength ranging from about 440 MPa to about 490 MPa, a tensile yield strength ranging from about 270 MPa to about 340 MPa and an elongation at break of the order of 5-8%.
  • This document also discloses a process for obtaining said alloy comprising the steps: a) casting an ingot of the composition described above, b) removing the residual stresses from said ingot by heat treatment, c) homogenizing by heating and maintaining temperature then cooling the ingot, d) hot rolling said ingot to its final thickness, e) dissolving and then quenching the product thus rolled, f) pulling the product and g) tempering said product by heating and maintaining temperature .
  • the patent US 5,431,876 teaches a group of ternary alloys of lithium aluminum and magnesium or copper, including at least one additive such as zirconium, chromium and / or manganese.
  • the alloy is prepared according to methods known to those skilled in the art comprising, by way of example, an extrusion, a solution, a quenching, a traction of the product of 2 to 7% then an annealing.
  • the patent US 6,551,424 describes a process for manufacturing aluminum-magnesium-lithium alloy rolled products of composition (in% by weight) Mg: 3.0 - 6.0; Li: 0.4 - 3.0; Zn up to 2.0; Mn up to 1.0; Ag up to 0.5; Fe up to 0.3; Si up to 0.3; Cu up to 0.3; 0.02 - 0.5 of a member selected from the group consisting of Sc, Hf, Ti, V, Nd, Zr, Cr, Y, Be, said process including cold rolling lengthwise and in the direction of the width.
  • the patent US 6,461,566 describes an alloy of composition (in% by weight) Li: 1.5 - 1.9; Mg: 4.1 - 6.0; Zn 0.1 - 1.5; Zr 0.05 - 0.3; Mn 0.01 - 0.8; H 0.9 x 10 -5 -4.5 x 10 -5 and at least one element selected from the group Be 0.001 - 0.2; Y 0.001 - 0.5 and Sc 0.01 - 0.3.
  • the patent application WO 2012/16072 describes a wrought aluminum alloy product of composition in% by weight, Mg: 4.0 - 5.0; Li: 1.0 - 1.6; Zr: 0.05 - 0.15; Ti: 0.01 - 0.15; Fe: 0.02 - 0.2; Si: 0.02 - 0.2; Mn: ⁇ 0.5; Cr ⁇ 0.5; Ag: ⁇ 0.5; Cu ⁇ 0.5; Zn ⁇ 0.5; Sc ⁇ 0.01; other elements ⁇ 0.05; remains aluminum.
  • Said product is in particular obtained according to a manufacturing process comprising in particular successively the casting of the alloy in raw form, its hot and optionally cold deformation, the solution and then the quenching of the product thus deformed, optionally the cold deformation.
  • the metallurgical state obtained for the rolled products is advantageously a T6 or T6X or T8 or T8X state and for the extruded products advantageously a T5 or T5X state in the case of quenching on a press or a T6 or T6X or T8 or T8X state.
  • FR 1 519 021 A discloses an alloy, which contains 4-7% Mg, 1.5-2.6% Li, 0.05-0.3% Zr, 0.2-1.0 Mn, the remainder being aluminum.
  • SU 1 367 517 A1 discloses an aluminum base alloy.
  • EP 0 273 600 A2 discloses an aluminum alloy containing 1.0-2.8 Li%, 2.5-7.0% Mg and ⁇ 1% at least one of the additive elements including Zr.
  • CHEN ZG ET AL "The effect of small additions of silver on aging behavior of Al-Mg-Li alloys", ALUMUMUM ALLOYS: THEIR PHYSICAL AND MECHANICAL PROPERTIES, PAPERS PRESENTED AT THE INTERNATIONAL CONFERENCE, 4TH, ATLANTA, SEPT.
  • Wrought aluminum-magnesium-lithium alloy products have a low density and are therefore particularly advantageous in the extremely demanding field of aeronautics.
  • their performance must be significantly improved compared to that of existing products, in particular their performance in terms of compromise between the properties of static mechanical resistance (in particular tensile yield strength and compression, tensile strength) and damage tolerance properties (toughness, fatigue crack propagation resistance), these properties being generally contradictory.
  • These alloys must also have sufficient corrosion resistance, be able to be shaped according to the usual methods and have low residual stresses so as to be able to be machined without substantial distortion during said machining.
  • Another subject of the invention is a wrought product capable of being obtained according to the method of the invention as well as the use of said wrought product to produce an aircraft structural element.
  • alloys are expressed as a percentage by weight based on the total weight of the alloy.
  • expression 1.4 Cu means that the copper content expressed in% by weight is multiplied by 1.4.
  • the designation of the alloys is made in accordance with the regulations of The Aluminum Association, known to those skilled in the art. Density depends on composition and is determined by calculation rather than by a weight measurement method. The values are calculated in accordance with the procedure of The Aluminum Association, which is described on pages 2-12 and 2-13 of “Aluminum Standards and Data” . The definitions of metallurgical states are given in European standard EN 515.
  • the static mechanical properties in tension are determined by a tensile test according to standard NF EN ISO 6892-1, the sampling and direction of the test being defined by standard EN 485-1.
  • the increased stress on the product during the K1c toughness test according to ASTM E399 may be indicative of the product's propensity to delamination.
  • delamination is meant here (“crack delamination” and / or “crack divider” in English) a cracking in planes orthogonal to the front of the main crack. The orientation of these planes corresponds to that of the grain boundaries not recrystallized after deformation by wrought.
  • a low delamination is the sign of less fragility of the planes concerned and minimizes the risks of deviation of crack towards the longitudinal direction during propagation in fatigue or under monotonic stress.
  • structural element or “structural element” of a mechanical construction a mechanical part for which the static and / or dynamic mechanical properties are particularly important for the performance of the structure and for which a structural calculation is usually prescribed or performed. These are typically elements the failure of which is likely to endanger the safety of said construction, its users, its users or others.
  • these structural elements include in particular the elements that make up the fuselage (such as the fuselage skin), the stiffeners or runners of the fuselage (stringers), the watertight bulkheads, the frames of the fuselage (circumferential frames), the wings (such as the upper or lower wing skin), the stiffeners (stringers or stiffeners), the ribs, the spars (spars), the floor (floor beams) and seat tracks (seat tracks)) and the tail unit composed in particular of horizontal and vertical stabilizers (horizontal or vertical stabilizers), as well as the doors.
  • the process for manufacturing the products according to the invention comprises the successive stages of producing a bath of liquid metal so as to obtain an Al-Mg-Li alloy of particular composition, the casting of said alloy in crude form, optionally the homogenization of said raw form thus cast, hot deformation of said raw form to obtain a hot-deformed product, separate solution of the product thus hot-deformed, quenching of said hot-deformed product, optionally dressing / leveling of the deformed and tempered product, the tempering of said deformed and tempered product and the cold deformation of the tempered product in a controlled manner to obtain a permanent cold deformation of 1 to 10%, preferably 2 to 6%, more preferably still of 3 at 5% and more preferably still from 4 to 5%.
  • the manufacturing process therefore consists first of all in the casting of a crude form of Al-Mg-Li alloy of composition, in% by weight: Mg: 4.0 - 5.0; Li: 1.0 -1.8; Zr: 0.05 - 0.15; Mn: ⁇ 0.6; Ag: ⁇ 0.5; Fe: ⁇ 0.1; Ti: ⁇ 0.15; Si: ⁇ 0.05; other elements ⁇ 0.05 each and ⁇ 0.15 in combination; remains aluminum.
  • a bath of liquid metal is therefore produced and then cast in raw form, typically a rolling plate, a spinning billet or a forge blank.
  • the Al-Mg-Li alloy has an Mn content, in% by weight, of 0.2 to 0.6%, preferably from 0.35 to 0.5%, more preferably of 0.35 to 0.45% and more preferably still from 0.35 to 0.40%.
  • the alloy products as described above and having the advantageous Mn content exhibit in particular improved static mechanical properties as well as a low propensity for delamination.
  • the raw aluminum alloy form has a silver content of less than or equal to 0.25% by weight, more preferably a silver content of 0.05% to 0.1% by weight.
  • This element contributes in particular to the static mechanical properties.
  • the raw aluminum alloy form has a total Ag and Cu content of less than 0.15% by weight, preferably less than or equal to 0.12%. The control of the maximum content of these two elements in combination makes it possible in particular to improve the resistance to intergranular corrosion of the wrought product.
  • the crude form has a zinc content, in% by weight, of less than 0.04%, preferably less than or equal to 0.03%.
  • a zinc content in% by weight, of less than 0.04%, preferably less than or equal to 0.03%.
  • Such limitation of zinc content in the particular alloy described above has given excellent results in terms of density and corrosion resistance of the alloy.
  • the raw aluminum alloy form has an Fe content, in% by weight, less than 0.08%, preferably less than or equal to 0.07%, more preferably still less than or equal to 0.06%.
  • the present inventors believe that a minimum content of Fe, as well as possibly that of Si, can contribute to improving the mechanical properties and in particular the fatigue properties of the alloy. Excellent results have in particular been obtained for an Fe content of 0.02 to 0.06% by weight and / or an Si content of 0.02 to 0.05% by weight.
  • the lithium content of the products according to the invention is between 1.0 and 1.8% by weight.
  • the raw aluminum alloy form has a Li content, in% by weight, less than 1.6%, preferably less than or equal to 1.5%, more preferably less than or equal to 1 , 4%.
  • a minimum lithium content of 1.1% by weight and preferably 1.2% by weight is advantageous.
  • the present inventors have observed that a limited lithium content, in the presence of certain addition elements, makes it possible to very significantly improve the toughness, which largely compensates for the slight increase in density and the decrease in static mechanical properties.
  • the raw aluminum alloy form has a Zr content, in% by weight, of 0.10 to 0.15%.
  • the inventors have in fact observed that such a Zr content makes it possible to obtain an alloy having a favorable fiber structure for improved static mechanical properties.
  • the raw aluminum alloy form has an Mg content, in% by weight, of 4.5 to 4.9%. Excellent results have been obtained for alloys according to this embodiment, in particular as regards the static mechanical properties.
  • the Cr content of the products according to the invention is less than 0.05% by weight, preferably less than 0.01% by weight.
  • Such a limited Cr content in combination with the other elements of the alloy according to the invention makes it possible in particular to limit the formation of primary phases during casting.
  • the Ti content of the products according to the invention is less than 0.15% by weight, preferably between 0.01 and 0.05% by weight.
  • the Ti content is limited in the particular alloy of the present invention, in particular to prevent the formation of primary phases during casting.
  • the manufacturing process optionally comprises a step of homogenizing the raw form so as to reach a temperature between 450 ° C and 550 ° C and, preferably, between 480 ° C and 520 ° C for a period of between 5 and 60 hours.
  • the homogenization treatment can be carried out in one or more stages.
  • the hot deformation is carried out directly following a simple reheating without carrying out homogenization.
  • the raw shape is then hot deformed, typically by extrusion, rolling and / or forging, to obtain a deformed product.
  • This hot deformation is carried out from preferably at an inlet temperature above 400 ° C and, advantageously, from 420 ° C to 450 ° C.
  • the hot deformation is a deformation by extrusion of the raw form.
  • the hot and optionally cold deformed product is optionally subjected to separate solution at a temperature of 360 ° C to 460 ° C, preferably 380 ° C to 420 ° C, for 15 minutes to 8 hours.
  • the hot-deformed product is dissolved and then quenched.
  • the quenching is carried out with water and / or air. It is advantageous to carry out the quenching in air because the intergranular corrosion properties are improved.
  • a press or quenching on extrusion heat
  • it is advantageous to carry out the quenching on a press (or quenching on extrusion heat), preferably quenching on an air press, such quenching making it possible in particular to improve the static mechanical properties.
  • it can also be quenching on a water press. In the case of quenching on a press, the product is dissolved over extrusion heat.
  • the hot-deformed and tempered product may optionally be subjected to a dressing or leveling step depending on whether it is a section or a sheet.
  • dressing or leveling is understood here to mean a cold deformation step without permanent deformation or with a permanent deformation of less than 1%.
  • the hot-deformed, quenched and optionally dressed / planed product then undergoes a tempering step.
  • the tempering is carried out by heating, in one or more stages, at a temperature below 150 ° C, preferably at a temperature of 70 ° C to 140 ° C, for 5 to 100 hours.
  • the hot-deformed product thus tempered is cold-deformed in a controlled manner to obtain a permanent cold deformation of 1 to 10%, preferably 2 to 6%, more preferably still from 3 to 5% and, more preferably still. from 4 to 5%.
  • the permanent cold deformation is 2 to 4%.
  • the cold deformation can in particular be carried out by traction, compression and / or rolling.
  • the cold deformation is carried out by traction.
  • the metallurgical state obtained for the wrought products corresponds in particular to a T9 state according to standard EN515.
  • the process for manufacturing a wrought product does not include any cold deformation step inducing a permanent deformation of at least 1% between the hot deformation step or, if this step is present, solution and the income stage.
  • composition chosen in particular the content of Mg, Li and Mn if the latter is present, and the processing parameters, in particular the order of the steps of the manufacturing process, advantageously makes it possible to obtain wrought products. having a very particular improved property compromise, in particular the compromise between mechanical strength and damage tolerance, while exhibiting low density and good corrosion performance.
  • the wrought products according to the invention are preferably extruded products such as profiles, rolled products such as sheets or thick sheets and / or forged products.
  • a subject of the invention is also wrought products capable of being obtained according to the method described above, advantageously such products cold-deformed with a permanent cold-deformation of greater than 4%. Indeed, such products have quite new and particular characteristics.
  • the wrought products that can be obtained by the process according to the invention have, for a thickness of between 0.5 and 15 mm, at mid-thickness at least two mechanical strength properties static selected from properties (i) to (iii) and at least one damage tolerance property selected from properties (iv) to (v).
  • the products spun according to the invention exhibit particularly advantageous characteristics.
  • the spun products have a thickness of between 0.5mm and 15mm, but according to the disclosure of products with a thickness greater than 15mm, up to 50mm or even 100mm or more can also have advantageous properties.
  • the thickness of extruded products is defined according to standard EN 2066: 2001: the cross section is divided into elementary rectangles of dimensions A and B; A being always the largest dimension of the elementary rectangle and B being able to be considered as the thickness of the elementary rectangle. The sole is the elementary rectangle with the largest dimension A.
  • the wrought products according to the invention are advantageously used to produce structural elements of an aircraft, in particular of airplanes.
  • Preferred aircraft structural elements are in particular a fuselage skin, a fuselage frame, a stiffener or a fuselage stringer or else a wing skin, a wing stiffener, a rib or a spar.
  • Alloys A and B both have a composition suitable for carrying out the process according to the invention.
  • the density of alloys A and B calculated in accordance with the procedure of The Aluminum Association described on pages 2-12 and 2-13 of “Aluminum Standards and Data” , is 2.55.
  • Table 1 Composition in% by weight and density of Al-Mg-Li alloys used Alloy Ag Li Yes Fe Cu Ti Mn Mg Zn Zr Na (ppm) Ca (ppm) Density AT 0.10 1.39 0.04 0.05 0.01 0.03 0.14 4.56 0.03 0.12 8 22 2.55 B 0.11 1.39 0.03 0.06 0.01 0.03 0.41 4.57 0.03 0.11 8 15 2.55
  • the mechanical properties, in particular the maximum stress tolerable by the product or tensile strength, Rm, and the elastic limit Rp0.2 (stress value for a plastic deformation of 0.2%) of the products in the T9 are globally significantly higher than those of products in T8 or T6 states. Furthermore, the mechanical properties, in particular Rp0.2, increase with the increase in controlled traction (T6 ⁇ T8-3% ⁇ T8-5% ⁇ T9-3% ⁇ T9-5%).
  • An Mn content of the Al-Mg-Li alloy of about 0.4% by weight significantly improves the mechanical strength (Rp0.2 and Rm), in particular in the L direction, of the alloy relative to that of an alloy having an Mn content of about 0.14% by weight (alloy A).
  • the yield strength (stress value for a plastic deformation of 0.2%, Rp0.2) of the products in the T9 state is significantly higher than those of the products in the T8 or T6 states. Moreover, Rp0.2 increases with the increase in the controlled tensile stress (T6 ⁇ T8-3% ⁇ T8-5% ⁇ T9-3% ⁇ T9-5%).
  • alloy B An Mn content of the Al-Mg-Li alloy of about 0.4% by weight significantly improves the mechanical strength of the alloy (Rp0.2 and Rm) compared to that of a alloy having an Mn content of about 0.14% by weight (alloy A).
  • the products according to the invention exhibit satisfactory toughness whatever the Mn content of the alloy.
  • the figure 2 illustrates the yield strength, Rp0.2, of the products of this example as a function of the toughness, K Q (all values of K Q are invalid due to the criterion P max / P Q ⁇ 1.10).
  • the figure 3 illustrates the yield strength, Rp0.2, of the products of this example as a function of the stress intensity factor corresponding to the maximum stress, K max .
  • T9 products present an excellent compromise between their static properties, in particular Rp0.2, and their toughness, K Q , or their stress intensity factor corresponding to the maximum force, K max .
  • Alloy B products have lower delamination than Alloy A products.

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Description

Domaine de l'inventionField of the invention

L'invention concerne un procédé de fabrication d'un produit corroyé en alliage aluminium-magnésium-lithium, plus particulièrement un procédé de fabrication d'un tel produit présentant un compromis de propriétés amélioré, notamment un compromis amélioré entre limite d'élasticité en traction et ténacité desdits produits. L'invention a également pour objet un produit susceptible d'être obtenu par ledit procédé de fabrication et son utilisation, ledit produit étant destiné en particulier à la construction aéronautique et aérospatiale.The invention relates to a process for manufacturing a wrought aluminum-magnesium-lithium alloy product, more particularly to a process for manufacturing such a product exhibiting an improved compromise in properties, in particular an improved compromise between tensile yield strength. and toughness of said products. The subject of the invention is also a product capable of being obtained by said manufacturing process and its use, said product being intended in particular for aeronautical and aerospace construction.

Etat de la techniqueState of the art

Des produits corroyés en alliage d'aluminium sont développés pour produire des pièces de haute résistance destinées notamment à l'industrie aéronautique et à l'industrie aérospatiale.Wrought aluminum alloy products are developed to produce high strength parts intended in particular for the aeronautical industry and the aerospace industry.

Les alliages d'aluminium contenant du lithium sont très intéressants à cet égard, car le lithium peut réduire la densité de l'aluminium de 3 % et augmenter le module d'élasticité de 6 % pour chaque pourcent en poids de lithium ajouté. En particulier, les alliages d'aluminium contenant simultanément du magnésium et du lithium permettent d'atteindre des densités particulièrement faibles et ont donc été extensivement étudiés.Aluminum alloys containing lithium are of great interest in this regard, as lithium can reduce the density of aluminum by 3% and increase the modulus of elasticity by 6% for each weight percent lithium added. In particular, aluminum alloys simultaneously containing magnesium and lithium make it possible to achieve particularly low densities and have therefore been extensively studied.

Le brevet GB 1,172,736 enseigne un alliage contenant, en pourcentage en poids, 4 à 7 % de Mg, 1,5 - 2,6 % de Li, 0,2 - 1 % de Mn et/ou 0,05 - 0,3 % de Zr, reste aluminium. Cet alliage est utile pour l'élaboration de produits présentant une résistance mécanique élevée, une bonne résistance à la corrosion, une faible densité et un module d'élasticité élevé. Lesdits produits sont obtenus par un procédé comprenant une trempe optionnelle puis d'un revenu. A titre d'exemple, les produits issus du procédé selon GB 1,172,736 présentent une résistance à la rupture allant d'environ 440 MPa à environ 490 MPa, une limite d'élasticité en traction allant d'environ 270MPa à environ 340 MPa et un allongement à la rupture de l'ordre de 5-8%.The patent GB 1,172,736 teaches an alloy containing, in weight percent, 4-7% Mg, 1.5 - 2.6% Li, 0.2 - 1% Mn and / or 0.05 - 0.3% Zr, remains aluminum. This alloy is useful for producing products with high mechanical strength, good corrosion resistance, low density and high modulus of elasticity. Said products are obtained by a process comprising optional quenching followed by tempering. By way of example, the products resulting from the process according to GB 1,172,736 present a tensile strength ranging from about 440 MPa to about 490 MPa, a tensile yield strength ranging from about 270 MPa to about 340 MPa and an elongation at break of the order of 5-8%.

La demande internationale WO 92/03583 décrit un alliage utile pour les structures aéronautiques ayant une faible densité et de formule générale MgaLibZncAgdAlbal, dans lequel a est compris entre 0,5 et 10%, b est compris entre 0,5 et 3%, c est compris entre 0,1 et 5%, d est compris entre 0,1 et 2% et bal indique que le reste est de l'aluminium. Ce document divulgue également un procédé d'obtention dudit alliage comprenant les étapes : a) couler d'un lingot de composition ci-avant décrite, b) retirer les contraintes résiduelles dudit lingot par traitement thermique, c) homogénéiser par chauffage et maintien en température puis refroidir le lingot, d) laminer à chaud ledit lingot jusqu'à son épaisseur finale, e) mettre en solution puis tremper le produit ainsi laminé, f) tractionner le produit et g) réaliser un revenu dudit produit par chauffage et maintien en température.International demand WO 92/03583 describes an alloy useful for aeronautical structures having a low density and of general formula Mg a Li b Zn c Ag d Alb al , in which a is between 0.5 and 10%, b is between 0.5 and 3% , c is between 0.1 and 5%, d is between 0.1 and 2% and bal indicates that the remainder is aluminum. This document also discloses a process for obtaining said alloy comprising the steps: a) casting an ingot of the composition described above, b) removing the residual stresses from said ingot by heat treatment, c) homogenizing by heating and maintaining temperature then cooling the ingot, d) hot rolling said ingot to its final thickness, e) dissolving and then quenching the product thus rolled, f) pulling the product and g) tempering said product by heating and maintaining temperature .

Le brevet US 5,431,876 enseigne un groupe d'alliages ternaire d'aluminium lithium et magnésium ou cuivre, incluant au moins un additif tel que le zirconium, le chrome et/ou le manganèse. L'alliage est préparé selon des procédés connus de l'homme du métier comprenant, à titre d'exemple, une extrusion, une mise en solution, une trempe, une traction du produit de 2 à 7 % puis un revenu.The patent US 5,431,876 teaches a group of ternary alloys of lithium aluminum and magnesium or copper, including at least one additive such as zirconium, chromium and / or manganese. The alloy is prepared according to methods known to those skilled in the art comprising, by way of example, an extrusion, a solution, a quenching, a traction of the product of 2 to 7% then an annealing.

Le brevet US 6,551,424 décrit un procédé de fabrication de produits laminés en alliage aluminium-magnésium-lithium de composition (en % en poids) Mg : 3,0 - 6,0 ; Li : 0,4 - 3,0 ; Zn jusqu'à 2,0 ; Mn jusqu'à 1,0 ; Ag jusqu'à 0,5 ; Fe jusqu'à 0,3 ; Si jusqu'à 0,3 ; Cu jusqu'à 0,3 ; 0,02 - 0,5 d'un élément sélectionné dans le groupe consistant en Sc, Hf, Ti, V, Nd, Zr, Cr, Y, Be, ledit procédé incluant un laminage à froid dans le sens de la longueur et dans le sens de la largeur.The patent US 6,551,424 describes a process for manufacturing aluminum-magnesium-lithium alloy rolled products of composition (in% by weight) Mg: 3.0 - 6.0; Li: 0.4 - 3.0; Zn up to 2.0; Mn up to 1.0; Ag up to 0.5; Fe up to 0.3; Si up to 0.3; Cu up to 0.3; 0.02 - 0.5 of a member selected from the group consisting of Sc, Hf, Ti, V, Nd, Zr, Cr, Y, Be, said process including cold rolling lengthwise and in the direction of the width.

Le brevet US 6,461,566 décrit un alliage de composition (en % en poids) Li : 1,5 - 1,9 ; Mg : 4,1 - 6,0 ; Zn 0,1 - 1,5 ; Zr 0,05 - 0,3 ; Mn 0,01 - 0,8 ; H 0,9 x 10-5-4,5 x 10-5 et au moins un élément sélectionné dans le groupe Be 0,001 - 0,2 ; Y 0,001 - 0,5 et Sc 0,01 - 0,3.The patent US 6,461,566 describes an alloy of composition (in% by weight) Li: 1.5 - 1.9; Mg: 4.1 - 6.0; Zn 0.1 - 1.5; Zr 0.05 - 0.3; Mn 0.01 - 0.8; H 0.9 x 10 -5 -4.5 x 10 -5 and at least one element selected from the group Be 0.001 - 0.2; Y 0.001 - 0.5 and Sc 0.01 - 0.3.

La demande de brevet WO 2012/16072 décrit un produit corroyé en alliage d'aluminium de composition en % en poids, Mg : 4,0 - 5,0 ; Li : 1,0 - 1,6 ; Zr : 0,05 - 0,15 ; Ti : 0,01 - 0,15 ; Fe : 0,02 - 0,2 ; Si : 0,02 - 0,2 ; Mn : ≤ 0,5 ; Cr≤ 0,5 ; Ag : ≤ 0,5 ; Cu≤ 0,5 ; Zn≤0,5 ; Sc < 0,01 ; autres éléments < 0,05 ; reste aluminium. Ledit produit est en particulier obtenu selon un procédé de fabrication comprenant notamment successivement la coulée de l'alliage sous forme brute, sa déformation à chaud et optionnellement à froid, la mise en solution puis la trempe du produit ainsi déformé, optionnellement la déformation à froid du produit ainsi mis en solution et trempé et enfin le revenu du produit corroyé à une température inférieure à 150°C. L'état métallurgique obtenu pour les produits laminés est avantageusement un état T6 ou T6X ou T8 ou T8X et pour les produits filés avantageusement un état T5 ou T5X dans le cas de la trempe sur presse ou un état T6 ou T6X ou T8 ou T8X.The patent application WO 2012/16072 describes a wrought aluminum alloy product of composition in% by weight, Mg: 4.0 - 5.0; Li: 1.0 - 1.6; Zr: 0.05 - 0.15; Ti: 0.01 - 0.15; Fe: 0.02 - 0.2; Si: 0.02 - 0.2; Mn: ≤ 0.5; Cr≤ 0.5; Ag: ≤ 0.5; Cu≤ 0.5; Zn≤0.5; Sc <0.01; other elements <0.05; remains aluminum. Said product is in particular obtained according to a manufacturing process comprising in particular successively the casting of the alloy in raw form, its hot and optionally cold deformation, the solution and then the quenching of the product thus deformed, optionally the cold deformation. of the product thus dissolved and quenched and finally the tempering of the wrought product at a temperature below 150 ° C. The metallurgical state obtained for the rolled products is advantageously a T6 or T6X or T8 or T8X state and for the extruded products advantageously a T5 or T5X state in the case of quenching on a press or a T6 or T6X or T8 or T8X state.

FR 1 519 021 A divulgue un alliage, qui contient 4-7% Mg, 1.5-2.6% Li, 0.05-0.3% Zr, 0.2-1.0 Mn, le reste étant de l'aluminium. SU 1 367 517 A1 divulgue un alliage en base d'aluminium. EP 0 273 600 A2 divulgue un alliage d'aluminium contenant 1.0-2.8 Li%, 2.5-7.0% Mg et <1 % au moins un des éléments additifs incluant Zr. CHEN Z G ET AL: "The effect of small additions of silver on aging behavior of Al-Mg-Li alloys", ALUMIUM ALLOYS: THEIR PHYSICAL AND MECHANICAL PROPERTIES, PAPERS PRESENTED AT THE INTERNATIONAL CONFERENCE, 4TH, ATLANTA, SEPT. 11-16, 1994, vol. 2,11 septembre 1994 (1994-09-11), pages 177-182 , divulgue des alliages d'aluminium, qui contiennent 1.63 Li%, 5.05 % Mg , 0.26 Ag, 0.13 Zr et 1.56 Li%, 5.0% Mg, 0.52 Ag, 0.13 Zr. FRIDLYANDER I N: "Aluminum alloys containing lithium and magnésium", METALLOVEDENIE I TERMICHESKAYA OBRABOTKA METALLOV (RU), no. 9,1 janvier 2003 (2003-01-01), pages 13-16 (ISSN: 0026-0819 ) divulgue un alliage 1420. FRIDLYANDER I N ET AL: "Soviet aluminum-lithium alloys of aerospace application",ALUMINIUM-LITHIUM: PAPERS PRESENTED AT THE SIXTH INTERNATIONAL ALUMINIUM-LITHIUM CONFERENCE, 1991, GARMISCH-PARTENKIRCHEN (FRG), vol. 1, 1 janvier 1992 (1992-01-01), pages 35-42 , divulgue un alliage 1420. FR 1 519 021 A discloses an alloy, which contains 4-7% Mg, 1.5-2.6% Li, 0.05-0.3% Zr, 0.2-1.0 Mn, the remainder being aluminum. SU 1 367 517 A1 discloses an aluminum base alloy. EP 0 273 600 A2 discloses an aluminum alloy containing 1.0-2.8 Li%, 2.5-7.0% Mg and <1% at least one of the additive elements including Zr. CHEN ZG ET AL: "The effect of small additions of silver on aging behavior of Al-Mg-Li alloys", ALUMUM ALLOYS: THEIR PHYSICAL AND MECHANICAL PROPERTIES, PAPERS PRESENTED AT THE INTERNATIONAL CONFERENCE, 4TH, ATLANTA, SEPT. 11-16, 1994, vol. September 2.11, 1994 (1994-09-11), pages 177-182 , discloses aluminum alloys, which contain 1.63 Li%, 5.05% Mg, 0.26 Ag, 0.13 Zr and 1.56 Li%, 5.0% Mg, 0.52 Ag, 0.13 Zr. FRIDLYANDER IN: "Aluminum alloys containing lithium and magnesium", METALLOVEDENIE I TERMICHESKAYA OBRABOTKA METALLOV (RU), no. January 9.1, 2003 (2003-01-01), pages 13-16 (ISSN: 0026-0819 ) discloses a 1420 alloy. FRIDLYANDER IN ET AL: "Soviet aluminum-lithium alloys of aerospace application", ALUMINUM-LITHIUM: PAPERS PRESENTED AT THE SIXTH INTERNATIONAL ALUMINUM-LITHIUM CONFERENCE, 1991, GARMISCH-PARTENKIRCHEN (FRG), vol. 1, January 1, 1992 (1992-01-01), pages 35-42 , discloses an alloy 1420.

Les produits corroyés en alliage aluminium-magnésium-lithium présentent une faible densité et sont donc particulièrement intéressants dans le domaine extrêmement exigeant de l'aéronautique. Pour que de nouveaux produits soient sélectionnés dans un tel domaine, leur performance doit être significativement améliorée par rapport à celle des produits existants, en particulier leur performance en terme de compromis entre les propriétés de résistance mécanique statique (notamment limite d'élasticité en traction et en compression, résistance à la rupture) et les propriétés de tolérance aux dommages (ténacité, résistance à la propagation des fissures en fatigue), ces propriétés étant en général antinomiques.Wrought aluminum-magnesium-lithium alloy products have a low density and are therefore particularly advantageous in the extremely demanding field of aeronautics. For new products to be selected in such a field, their performance must be significantly improved compared to that of existing products, in particular their performance in terms of compromise between the properties of static mechanical resistance (in particular tensile yield strength and compression, tensile strength) and damage tolerance properties (toughness, fatigue crack propagation resistance), these properties being generally contradictory.

Ces alliages doivent également présenter une résistance à la corrosion suffisante, pouvoir être mis en forme selon les procédés habituels et présenter de faibles contraintes résiduelles de façon à pouvoir être usinés sans distorsion substantielle lors dudit usinage.These alloys must also have sufficient corrosion resistance, be able to be shaped according to the usual methods and have low residual stresses so as to be able to be machined without substantial distortion during said machining.

Il existe donc un besoin pour des produits corroyés en alliage aluminium-magnésium-lithium présentant une faible densité ainsi que des propriétés améliorées par rapport à celles des produits connus, en particulier en termes de compromis entre les propriétés de résistance mécanique statique et les propriétés de tolérance aux dommages. Concernant les propriétés de tolérance aux dommages, les produits corroyés doivent en particulier présenter une ténacité élevée ainsi qu'une faible propension au délaminage. De tels produits doivent de plus pouvoir être obtenus selon un procédé de fabrication fiable, économique et facilement adaptable à une ligne de fabrication conventionnelle.There is therefore a need for wrought aluminum-magnesium-lithium alloy products exhibiting a low density as well as improved properties compared to those of known products, in particular in terms of compromise between the properties of static mechanical strength and damage tolerance properties. Regarding the damage tolerance properties, wrought products must in particular exhibit high toughness as well as low delamination propensity. Such products must also be able to be obtained according to a reliable, economical manufacturing process that is easily adaptable to a conventional manufacturing line.

Objet de l'inventionObject of the invention

L'invention est définie par les revendications. Un premier objet de l'invention est un procédé de fabrication d'un produit corroyé à l'état T9 selon la norme EN515 comprenant les étapes successives:

  1. (a) on coule une forme brute en alliage d'aluminium de composition, en % en poids : Mg : 4,0 - 5,0 ; Li : 1,0 -1,8 ; Zr : 0,05 - 0,15; Mn : ≤ 0,6 ; Ag : ≤ 0,5; Fe : ≤ 0,1 ; Ti : < 0,15 ; Si : ≤ 0,05 ; autres éléments ≤ 0,05 chacun et ≤ 0,15 en association ; reste aluminium ;
  2. (b) optionnellement, on homogénéise ladite forme brute;
  3. (c) on déforme à chaud ladite forme brute pour obtenir un produit déformé à chaud;
  4. (d) on met en solution ledit produit déformé à chaud à une température de 360°C à 460°C, préférentiellement 380-420°C, pendant 15 minutes à 8 heures ;
  5. (e) on trempe ledit produit déformé à chaud ;
  6. (f) optionnellement, on effectue un dressage ou un planage dudit produit déformé et trempé ;
  7. (g) on réalise un revenu dudit produit déformé et trempé ;
  8. (h) on déforme à froid de façon contrôlée le produit déformé à chaud ainsi revenu pour obtenir une déformation permanente à froid de 1 à 10 %, de préférence de 2 à 6%, plus préférentiellement encore de 3 à 5% et, plus préférentiellement encore de 4 à 5% afin d'obtenir un produit corroyé à l'état T9 selon la norme EN515.
The invention is defined by the claims. A first object of the invention is a method of manufacturing a product wrought in the T9 state according to standard EN515 comprising the successive steps:
  1. (a) casting a crude form of aluminum alloy of composition, in% by weight: Mg: 4.0 - 5.0; Li: 1.0 -1.8; Zr: 0.05 - 0.15; Mn: ≤ 0.6; Ag: ≤ 0.5; Fe: ≤ 0.1; Ti: <0.15; Si: ≤ 0.05; other elements ≤ 0.05 each and ≤ 0.15 in combination; remains aluminum;
  2. (b) optionally, said raw form is homogenized;
  3. (c) said raw form is hot deformed to obtain a hot deformed product;
  4. (d) said hot-deformed product is dissolved at a temperature of 360 ° C to 460 ° C, preferably 380-420 ° C, for 15 minutes to 8 hours;
  5. (e) said hot deformed product is quenched;
  6. (f) optionally, a dressing or leveling of said deformed and tempered product is carried out;
  7. (g) tempering said deformed and quenched product;
  8. (h) the hot-deformed product thus tempered is cold-deformed in a controlled manner to obtain a permanent cold deformation of 1 to 10%, preferably 2 to 6%, more preferably still from 3 to 5% and, more preferably another 4 to 5% in order to obtain a product wrought in the T9 state according to standard EN515.

L'invention a encore pour objets, un produit corroyé susceptible d'être obtenu selon le procédé de l'invention ainsi que l'utilisation dudit produit corroyé pour réaliser un élément de structure d'aéronefs.Another subject of the invention is a wrought product capable of being obtained according to the method of the invention as well as the use of said wrought product to produce an aircraft structural element.

Description des figuresDescription of figures

  • Figure 1 : Profilé pour cadre de fuselage de l'exemple 1 Figure 1 : Profile for fuselage frame of example 1
  • Figure 2 : Limite d'élasticité, Rp0,2, en fonction de la ténacité, KQ* pour une barre plate de 10 mm d'épaisseur (* toutes les valeurs de KQ sont invalides en raison du critère Pmax / PQ ≤ 1,10 de la norme ASTM E399 ) Figure 2 : Yield strength, Rp0.2, as a function of toughness, K Q * for a flat bar 10 mm thick (* all values of K Q are invalid due to the criterion P max / P Q ≤ 1 , 10 of ASTM E399)
  • Figure 3 : Limite d'élasticité, Rp0,2, en fonction du facteur d'intensité de contrainte correspondant à la force maximale, Kmax (évaluée selon la norme ASTM E399) pour une barre plate de 10 mm d'épaisseur Figure 3 : Yield strength, Rp0.2, as a function of the stress intensity factor corresponding to the maximum force, K max (evaluated according to standard ASTM E399) for a flat bar 10 mm thick
Description de l'inventionDescription of the invention

Sauf mention contraire, toutes les indications concernant la composition chimique des alliages sont exprimées comme un pourcentage en poids basé sur le poids total de l'alliage. A titre d'exemple, l'expression 1,4 Cu signifie que la teneur en cuivre exprimée en % en poids est multipliée par 1,4. La désignation des alliages se fait en conformité avec les règlements de The Aluminium Association, connus de l'homme du métier. La densité dépend de la composition et est déterminée par calcul plutôt que par une méthode de mesure de poids. Les valeurs sont calculées en conformité avec la procédure de The Aluminium Association, qui est décrite pages 2-12 et 2-13 de « Aluminum Standards and Data » . Les définitions des états métallurgiques sont indiquées dans la norme européenne EN 515.Unless otherwise indicated, all indications concerning the chemical composition of alloys are expressed as a percentage by weight based on the total weight of the alloy. By way of example, the expression 1.4 Cu means that the copper content expressed in% by weight is multiplied by 1.4. The designation of the alloys is made in accordance with the regulations of The Aluminum Association, known to those skilled in the art. Density depends on composition and is determined by calculation rather than by a weight measurement method. The values are calculated in accordance with the procedure of The Aluminum Association, which is described on pages 2-12 and 2-13 of “Aluminum Standards and Data” . The definitions of metallurgical states are given in European standard EN 515.

Les caractéristiques mécaniques statiques en traction, en d'autres termes la résistance à la rupture Rm, la limite d'élasticité conventionnelle à 0,2% d'allongement Rp0,2, et l'allongement à la rupture A%, sont déterminés par un essai de traction selon la norme NF EN ISO 6892-1, le prélèvement et le sens de l'essai étant définis par la norme EN 485-1. La ténacité est déterminée par essai de ténacité Klc selon la norme ASTM E399. Une courbe donnant le facteur d'intensité de contrainte effectif en fonction de l'extension de fissure effective est déterminée selon la norme ASTM E399. Les essais ont été réalisés avec une éprouvette CT8 (B = 8mm, W = 16 mm). Dans le cas de valeurs de KQ invalides selon la norme ASTM E399, en particulier par rapport au critère Pmax/PQ ≤ 1,10, les résultats ont été aussi présentés en Kmax (facteur d'intensité de contrainte correspondant à la force maximale Pmax).The static mechanical properties in tension, in other words the tensile strength R m , the conventional yield strength at 0.2% elongation R p0.2, and the elongation at break A%, are determined by a tensile test according to standard NF EN ISO 6892-1, the sampling and direction of the test being defined by standard EN 485-1. The toughness is determined by the Klc toughness test according to the ASTM E399 standard. A curve giving the effective stress intensity factor as a function of the effective crack extension is determined according to ASTM E399. The tests were carried out with a CT8 specimen (B = 8mm, W = 16mm). In the case of invalid values of K Q according to the standard ASTM E399, in particular compared to the criterion P max / P Q ≤ 1.10, the results were also presented in K max (stress intensity factor corresponding to the maximum force P max ).

L'augmentation des contraintes sur le produit lors de l'essai de ténacité K1c selon la norme ASTM E399 peut être révélatrice de la propension du produit au délaminage. On entend ici par « délaminage » (« crack delamination » et/ou « crack divider » en anglais) une fissuration dans des plans orthogonaux au front de la fissure principale. L'orientation de ces plans correspond à celle des joints de grains non recristallisés après déformation par corroyage. Un faible délaminage est le signe d'une moindre fragilité des plans concernés et minimise les risques de déviation de fissure vers la direction longitudinale lors d'une propagation en fatigue ou sous sollicitation monotone.The increased stress on the product during the K1c toughness test according to ASTM E399 may be indicative of the product's propensity to delamination. By “delamination” is meant here (“crack delamination” and / or “crack divider” in English) a cracking in planes orthogonal to the front of the main crack. The orientation of these planes corresponds to that of the grain boundaries not recrystallized after deformation by wrought. A low delamination is the sign of less fragility of the planes concerned and minimizes the risks of deviation of crack towards the longitudinal direction during propagation in fatigue or under monotonic stress.

Sauf mention contraire, les définitions de la norme EN 12258 s'appliquent.Unless stated otherwise, the definitions of standard EN 12258 apply.

Par ailleurs, on appelle ici « élément de structure » ou « élément structural » d'une construction mécanique une pièce mécanique pour laquelle les propriétés mécaniques statiques et/ou dynamiques sont particulièrement importantes pour la performance de la structure et pour laquelle un calcul de structure est habituellement prescrit ou réalisé. Il s'agit typiquement d'éléments dont la défaillance est susceptible de mettre en danger la sécurité de ladite construction, de ses utilisateurs, de ses usagers ou d'autrui. Pour un avion, ces éléments de structure comprennent notamment les éléments qui composent le fuselage (tels que la peau de fuselage, (fuselage skin en anglais), les raidisseurs ou lisses de fuselage (stringers), les cloisons étanches (bulkheads), les cadres de fuselage (circumferential frames), les ailes (tels que la peau de voilure extrados ou intrados (upper or lower wing skin), les raidisseurs (stringers ou stiffeners), les nervures (ribs), les longerons (spars), les profilés de plancher (floor beams) et les rails de sièges (seat tracks)) et l'empennage composé notamment de stabilisateurs horizontaux et verticaux (horizontal or vertical stabilisers), ainsi que les portes.Furthermore, here we call “structural element” or “structural element” of a mechanical construction a mechanical part for which the static and / or dynamic mechanical properties are particularly important for the performance of the structure and for which a structural calculation is usually prescribed or performed. These are typically elements the failure of which is likely to endanger the safety of said construction, its users, its users or others. For an airplane, these structural elements include in particular the elements that make up the fuselage (such as the fuselage skin), the stiffeners or runners of the fuselage (stringers), the watertight bulkheads, the frames of the fuselage (circumferential frames), the wings (such as the upper or lower wing skin), the stiffeners (stringers or stiffeners), the ribs, the spars (spars), the floor (floor beams) and seat tracks (seat tracks)) and the tail unit composed in particular of horizontal and vertical stabilizers (horizontal or vertical stabilizers), as well as the doors.

Le procédé de fabrication des produits selon l'invention comprend les étapes successives d'élaboration d'un bain de métal liquide de façon à obtenir un alliage Al-Mg-Li de composition particulière, la coulée dudit alliage sous forme brute, optionnellement l'homogénéisation de ladite forme brute ainsi coulée, la déformation à chaud de ladite de forme brute pour obtenir un produit déformé à chaud, la mise en solution séparée du produit ainsi déformé à chaud, la trempe dudit produit déformé à chaud, optionnellement le dressage/planage du produit déformé et trempé, le revenu dudit produit déformé et trempé et la déformation à froid de façon contrôlée du produit revenu pour obtenir une déformation permanente à froid de 1 à 10 %, de préférence de 2 à 6%, plus préférentiellement encore de 3 à 5% et plus préférentiellement encore de 4 à 5%.The process for manufacturing the products according to the invention comprises the successive stages of producing a bath of liquid metal so as to obtain an Al-Mg-Li alloy of particular composition, the casting of said alloy in crude form, optionally the homogenization of said raw form thus cast, hot deformation of said raw form to obtain a hot-deformed product, separate solution of the product thus hot-deformed, quenching of said hot-deformed product, optionally dressing / leveling of the deformed and tempered product, the tempering of said deformed and tempered product and the cold deformation of the tempered product in a controlled manner to obtain a permanent cold deformation of 1 to 10%, preferably 2 to 6%, more preferably still of 3 at 5% and more preferably still from 4 to 5%.

Le procédé de fabrication consiste donc tout d'abord à la coulée d'une forme brute en alliage Al-Mg-Li de composition, en % en poids : Mg : 4,0 - 5,0 ; Li : 1,0 -1,8 ; Zr : 0,05 - 0,15; Mn : ≤ 0,6 ; Ag : ≤ 0,5; Fe : ≤ 0,1 ; Ti : < 0,15 ; Si : ≤ 0,05 ; autres éléments ≤ 0,05 chacun et ≤ 0,15 en association ; reste aluminium. Un bain de métal liquide est donc réalisé puis coulé sous forme brute, typiquement une plaque de laminage, une billette de filage ou une ébauche de forge.The manufacturing process therefore consists first of all in the casting of a crude form of Al-Mg-Li alloy of composition, in% by weight: Mg: 4.0 - 5.0; Li: 1.0 -1.8; Zr: 0.05 - 0.15; Mn: ≤ 0.6; Ag: ≤ 0.5; Fe: ≤ 0.1; Ti: <0.15; Si: ≤ 0.05; other elements ≤ 0.05 each and ≤ 0.15 in combination; remains aluminum. A bath of liquid metal is therefore produced and then cast in raw form, typically a rolling plate, a spinning billet or a forge blank.

Selon un mode de réalisation avantageux, l'alliage Al-Mg-Li présente une teneur en Mn, en % en poids, de 0,2 à 0,6%, préférentiellement de 0,35 à 0,5%, plus préférentiellement de 0,35 à 0,45% et plus préférentiellement encore de 0,35 à 0,40%.According to an advantageous embodiment, the Al-Mg-Li alloy has an Mn content, in% by weight, of 0.2 to 0.6%, preferably from 0.35 to 0.5%, more preferably of 0.35 to 0.45% and more preferably still from 0.35 to 0.40%.

Les produits en alliage tel que décrit précédemment et ayant la teneur en Mn avantageuse présentent en particulier des propriétés mécaniques statiques améliorées ainsi qu'une faible propension au délaminage.The alloy products as described above and having the advantageous Mn content exhibit in particular improved static mechanical properties as well as a low propensity for delamination.

Selon un mode de réalisation avantageux, la forme brute en alliage d'aluminium présente une teneur en argent inférieure ou égale à 0,25 % en poids, plus préférentiellement une teneur en argent de 0,05 % à 0,1 % en poids. Cet élément contribue notamment aux propriétés mécaniques statiques. De plus, selon un mode de réalisation encore plus avantageux, la forme brute en alliage d'aluminium présente une teneur totale en Ag et Cu inférieure à 0,15 % en poids, préférentiellement inférieure ou égale à 0,12%. Le contrôle de la teneur maximale en ces deux éléments en association permet en particulier d'améliorer la résistance à la corrosion intergranulaire du produit corroyé.According to an advantageous embodiment, the raw aluminum alloy form has a silver content of less than or equal to 0.25% by weight, more preferably a silver content of 0.05% to 0.1% by weight. This element contributes in particular to the static mechanical properties. In addition, according to an even more advantageous embodiment, the raw aluminum alloy form has a total Ag and Cu content of less than 0.15% by weight, preferably less than or equal to 0.12%. The control of the maximum content of these two elements in combination makes it possible in particular to improve the resistance to intergranular corrosion of the wrought product.

Selon un mode de réalisation particulier, la forme brute présente une teneur en zinc, en % en poids, inférieure à 0,04%, préférentiellement inférieure ou égale à 0,03%. Une telle limitation de teneur en zinc dans l'alliage particulier décrit précédemment a donné d'excellents résultats en termes de densité et de résistance à la corrosion de l'alliage.According to a particular embodiment, the crude form has a zinc content, in% by weight, of less than 0.04%, preferably less than or equal to 0.03%. Such limitation of zinc content in the particular alloy described above has given excellent results in terms of density and corrosion resistance of the alloy.

Selon un autre mode de réalisation compatible avec les modes précédents, la forme brute en alliage d'aluminium présente une teneur en Fe, en % en poids, inférieure à 0,08%, préférentiellement inférieure ou égale à 0,07%, plus préférentiellement encore inférieure ou égale à 0,06%. Les présents inventeurs pensent qu'une teneur minimum en Fe, ainsi qu'éventuellement celle de Si, peut contribuer à améliorer les propriétés mécaniques et notamment les propriétés en fatigue de l'alliage. D'excellents résultats ont en particulier été obtenus pour une teneur en Fe de 0,02 à 0,06 % en poids et/ ou une teneur en Si de 0,02 à 0,05% en poids.According to another embodiment compatible with the preceding embodiments, the raw aluminum alloy form has an Fe content, in% by weight, less than 0.08%, preferably less than or equal to 0.07%, more preferably still less than or equal to 0.06%. The present inventors believe that a minimum content of Fe, as well as possibly that of Si, can contribute to improving the mechanical properties and in particular the fatigue properties of the alloy. Excellent results have in particular been obtained for an Fe content of 0.02 to 0.06% by weight and / or an Si content of 0.02 to 0.05% by weight.

La teneur en lithium des produits selon l'invention est comprise entre 1,0 et 1,8 % en poids. Selon un mode de réalisation avantageux, la forme brute en alliage d'aluminium présente une teneur en Li, en % en poids, inférieure à 1,6%, préférentiellement inférieure ou égale à 1,5%, préférentiellement encore inférieure ou égale à 1,4%. Une teneur minimale en lithium de 1,1 % en poids et de préférence de 1,2 % en poids est avantageuse. Les présents inventeurs ont constaté qu'une teneur en lithium limitée, en présence de certains éléments d'addition, permet d'améliorer très significativement la ténacité, ce qui compense largement la légère augmentation de densité et la diminution des propriétés mécaniques statiques.The lithium content of the products according to the invention is between 1.0 and 1.8% by weight. According to an advantageous embodiment, the raw aluminum alloy form has a Li content, in% by weight, less than 1.6%, preferably less than or equal to 1.5%, more preferably less than or equal to 1 , 4%. A minimum lithium content of 1.1% by weight and preferably 1.2% by weight is advantageous. The present inventors have observed that a limited lithium content, in the presence of certain addition elements, makes it possible to very significantly improve the toughness, which largely compensates for the slight increase in density and the decrease in static mechanical properties.

Selon un mode de réalisation préféré, la forme brute en alliage d'aluminium présente une teneur en Zr, en % en poids, de 0,10 à 0,15%. Les inventeurs ont en effet constaté qu'une telle teneur en Zr permet d'obtenir un alliage présentant une structure fibrée favorable pour des propriétés mécaniques statiques améliorées.According to a preferred embodiment, the raw aluminum alloy form has a Zr content, in% by weight, of 0.10 to 0.15%. The inventors have in fact observed that such a Zr content makes it possible to obtain an alloy having a favorable fiber structure for improved static mechanical properties.

Selon un mode de réalisation avantageux, la forme brute en alliage d'aluminium présente une teneur en Mg, en % en poids, de 4,5 à 4,9%. D'excellents résultats ont été obtenus pour des alliages selon ce mode de réalisation notamment pour ce qui concerne les propriétés mécaniques statiques.According to an advantageous embodiment, the raw aluminum alloy form has an Mg content, in% by weight, of 4.5 to 4.9%. Excellent results have been obtained for alloys according to this embodiment, in particular as regards the static mechanical properties.

Selon un mode de réalisation avantageux, la teneur en Cr des produits selon l'invention est inférieure à 0,05% en poids, préférentiellement inférieure à 0,01% en poids. Une telle teneur limitée en Cr en association avec les autres éléments de l'alliage selon l'invention permet notamment de limiter la formation de phases primaires lors de la coulée.According to an advantageous embodiment, the Cr content of the products according to the invention is less than 0.05% by weight, preferably less than 0.01% by weight. Such a limited Cr content in combination with the other elements of the alloy according to the invention makes it possible in particular to limit the formation of primary phases during casting.

La teneur en Ti des produits selon l'invention est inférieure à 0,15% en poids, préférentiellement comprise entre 0,01 et 0,05% en poids. La teneur en Ti est limitée dans l'alliage particulier de la présente invention notamment pour éviter la formation de phases primaires lors de la coulée. D'autre part, il peut être avantageux de contrôler la teneur en Ti pour maîtriser la structure granulaire et notamment la taille de grain lors de la coulée de l'alliage.The Ti content of the products according to the invention is less than 0.15% by weight, preferably between 0.01 and 0.05% by weight. The Ti content is limited in the particular alloy of the present invention, in particular to prevent the formation of primary phases during casting. On the other hand, it may be advantageous to control the Ti content in order to control the granular structure and in particular the grain size during the casting of the alloy.

Certains éléments peuvent être néfastes pour les alliages Al-Mg-Li tels que précédemment décrits, en particulier pour des raisons de transformation de l'alliage telles que la toxicité et/ou les casses lors de la déformation. Il est donc préférable de limiter ces éléments à un niveau très faible, i.e. inférieur à 0,05 % en poids ou même moins. Dans un mode de réalisation avantageux, les produits selon l'invention ont une teneur maximale de 10 ppm de Na, préférentiellement de 8 ppm de Na, et/ou une teneur maximale de 20 ppm de Ca. Selon un mode de réalisation particulièrement avantageux, la forme brute en alliage d'aluminium est substantiellement exempte de Sc, Be, Y, plus préférentiellement ladite forme brute comprend moins de 0,01% en poids de ces éléments pris en combinaison. Selon un mode de réalisation particulièrement avantageux, la forme brute en alliage d'aluminium présente une composition, en % en poids :

  • Mg : 4,0 - 5,0, préférentiellement 4,5 - 4,9;
  • Li : 1,1 -1,6, préférentiellement 1,2 - 1,5 ;
  • Zr : 0,05 - 0,15, préférentiellement 0,10 - 0,15 ;
  • Ti : < 0,15, préférentiellement 0,01-0,05 ;
  • Fe : 0,02 - 0,1, préférentiellement 0,02 - 0,06 ;
  • Si : 0,02 - 0,05 ;
  • Mn : ≤ 0,6, préférentiellement 0,2 - 0,6, plus préférentiellement encore 0,35 - 0,5 ;
  • Cr : < 0,05, préférentiellement < 0,01 ;
  • Ag : ≤ 0,5 ; préférentiellement ≤ 0,25 ; plus préférentiellement encore ≤ 0,1 ;
  • Sc : <0,01 ;
  • autres éléments ≤ 0,05 chacun et ≤ 0,15 en association ;
  • reste aluminium. D'excellents résultats ont été obtenus avec un alliage présentant une telle composition.
Certain elements can be harmful for Al-Mg-Li alloys as described above, in particular for reasons of transformation of the alloy such as toxicity and / or breakage during deformation. It is therefore preferable to limit these elements to a very low level, ie less than 0.05% by weight or even less. In an advantageous embodiment, the products according to the invention have a maximum content of 10 ppm of Na, preferably 8 ppm of Na, and / or a maximum content of 20 ppm of Ca. According to a particularly advantageous embodiment, the raw form of aluminum alloy is substantially free of Sc, Be, Y, more preferably said raw form comprises less than 0.01% by weight of these elements taken in combination. According to a particularly advantageous embodiment, the raw aluminum alloy form has a composition, in% by weight:
  • Mg: 4.0 - 5.0, preferably 4.5 - 4.9;
  • Li: 1.1 -1.6, preferably 1.2 - 1.5;
  • Zr: 0.05 - 0.15, preferably 0.10 - 0.15;
  • Ti: <0.15, preferably 0.01-0.05;
  • Fe: 0.02 - 0.1, preferably 0.02 - 0.06;
  • Si: 0.02 - 0.05;
  • Mn: ≤ 0.6, preferably 0.2 - 0.6, more preferably still 0.35 - 0.5;
  • Cr: <0.05, preferably <0.01;
  • Ag: ≤ 0.5; preferably ≤ 0.25; more preferably still ≤ 0.1;
  • Sc: <0.01;
  • other elements ≤ 0.05 each and ≤ 0.15 in combination;
  • remains aluminum. Excellent results have been obtained with an alloy exhibiting such a composition.

Suite à l'étape de coulée de la forme brute, le procédé de fabrication comprend optionnellement une étape d'homogénéisation de la forme brute de façon à atteindre une température comprise entre 450 °C et 550 °C et, de préférence, entre 480°C et 520 °C pendant une durée comprise entre 5 et 60 heures. Le traitement d'homogénéisation peut être réalisé en un ou plusieurs paliers. Selon un mode de réalisation préféré de l'invention, on procède directement à la déformation à chaud à la suite d'un simple réchauffage sans effectuer d'homogénéisation.Following the step of casting the raw form, the manufacturing process optionally comprises a step of homogenizing the raw form so as to reach a temperature between 450 ° C and 550 ° C and, preferably, between 480 ° C and 520 ° C for a period of between 5 and 60 hours. The homogenization treatment can be carried out in one or more stages. According to a preferred embodiment of the invention, the hot deformation is carried out directly following a simple reheating without carrying out homogenization.

La forme brute est ensuite déformée à chaud, typiquement par filage, laminage et/ou forgeage, pour obtenir un produit déformé. Cette déformation à chaud est effectuée de préférence à une température d'entrée supérieure à 400 °C et, de manière avantageuse, de 420°C à 450°C. Selon un mode de réalisation avantageux, la déformation à chaud est une déformation par filage de la forme brute.The raw shape is then hot deformed, typically by extrusion, rolling and / or forging, to obtain a deformed product. This hot deformation is carried out from preferably at an inlet temperature above 400 ° C and, advantageously, from 420 ° C to 450 ° C. According to an advantageous embodiment, the hot deformation is a deformation by extrusion of the raw form.

Dans le cas de la fabrication de tôles par laminage, il peut être nécessaire de réaliser une étape de laminage à froid (qui constitue alors première étape optionnelle de déformation à froid) pour les produits dont l'épaisseur est inférieure à 3 mm. Il peut s'avérer utile de réaliser un ou plusieurs traitements thermiques intermédiaires, typiquement réalisés à une température comprise entre 300 et 420 °C, avant ou au cours du laminage à froid.In the case of the manufacture of sheets by rolling, it may be necessary to carry out a cold rolling step (which then constitutes the first optional cold deformation step) for products whose thickness is less than 3 mm. It may prove useful to carry out one or more intermediate heat treatments, typically carried out at a temperature between 300 and 420 ° C., before or during cold rolling.

Le produit déformé à chaud et, optionnellement, à froid est optionnellement soumis à une mise en solution séparée à une température de 360°C à 460°C, préférentiellement de 380°C à 420°C, pendant 15 minutes à 8 heures.The hot and optionally cold deformed product is optionally subjected to separate solution at a temperature of 360 ° C to 460 ° C, preferably 380 ° C to 420 ° C, for 15 minutes to 8 hours.

Le produit déformé à chaud est mis en solution est ensuite trempé. La trempe est effectuée à l'eau et/ou à l'air. Il est avantageux de réaliser la trempe à l'air car les propriétés de corrosion intergranulaire sont améliorées. Dans le cas d'un produit filé, il est avantageux de réaliser la trempe sur presse (ou trempe sur chaleur de filage), préférentiellement une trempe sur presse à l'air, une telle trempe permettant en particulier d'améliorer les propriétés mécaniques statiques. Selon un autre mode de réalisation, il peut également s'agir d'une trempe sur presse à l'eau. Dans le cas de la trempe sur presse, le produit est mis en solution sur chaleur de filage.The hot-deformed product is dissolved and then quenched. The quenching is carried out with water and / or air. It is advantageous to carry out the quenching in air because the intergranular corrosion properties are improved. In the case of a spun product, it is advantageous to carry out the quenching on a press (or quenching on extrusion heat), preferably quenching on an air press, such quenching making it possible in particular to improve the static mechanical properties. . According to another embodiment, it can also be quenching on a water press. In the case of quenching on a press, the product is dissolved over extrusion heat.

Le produit déformé à chaud et trempé peut éventuellement être soumis à une étape de dressage ou de planage selon qu'il s'agit d'un profilé ou d'une tôle. On entend ici par « dressage/planage » une étape de déformation à froid sans déformation permanente ou avec une déformation permanente inférieure à 1%.The hot-deformed and tempered product may optionally be subjected to a dressing or leveling step depending on whether it is a section or a sheet. The term “dressing / leveling” is understood here to mean a cold deformation step without permanent deformation or with a permanent deformation of less than 1%.

Le produit déformé à chaud, trempé et, optionnellement dressé/plané, subit ensuite une étape de revenu. Avantageusement, le revenu est réalisé par chauffage, en un ou plusieurs paliers, à une température inférieure à 150 °C, de préférence à une température de 70 °C à 140 °C, pendant 5 à 100 heures.The hot-deformed, quenched and optionally dressed / planed product then undergoes a tempering step. Advantageously, the tempering is carried out by heating, in one or more stages, at a temperature below 150 ° C, preferably at a temperature of 70 ° C to 140 ° C, for 5 to 100 hours.

Finalement, le produit déformé à chaud ainsi revenu est déformé à froid de façon contrôlée pour obtenir une déformation permanente à froid de 1 à 10 %, de préférence de 2 à 6%, plus préférentiellement encore de 3 à 5% et, plus préférentiellement encore de 4 à 5%. Selon un mode de réalisation avantageux, la déformation permanente à froid est de 2 à 4%. La déformation à froid peut en particulier être réalisée par traction, compression et/ou laminage. Selon un mode de réalisation préféré, la déformation à froid est réalisée par traction. De façon tout à fait inattendue, il a été mis en évidence que, lorsqu'elle est réalisée après l'étape de revenu, la déformation à froid de façon contrôlée d'un produit corroyé de composition telle que décrite précédemment permet d'obtenir un excellent compromis entre les propriétés mécaniques statiques et celles de tolérance aux dommages, en particulier de ténacité. L'état métallurgique obtenu pour les produits corroyé correspond notamment un état T9 selon la norme EN515. Selon un mode de réalisation avantageux, le procédé de fabrication d'un produit corroyé ne comprend aucune étape de déformation à froid induisant une déformation permanente d'au moins 1% entre l'étape de déformation à chaud ou, si cette étape est présente, de mise en solution et l'étape de revenu.Finally, the hot-deformed product thus tempered is cold-deformed in a controlled manner to obtain a permanent cold deformation of 1 to 10%, preferably 2 to 6%, more preferably still from 3 to 5% and, more preferably still. from 4 to 5%. According to an advantageous embodiment, the permanent cold deformation is 2 to 4%. The cold deformation can in particular be carried out by traction, compression and / or rolling. According to a preferred embodiment, the cold deformation is carried out by traction. Completely unexpectedly, it has been demonstrated that, when it is carried out after the tempering step, the cold deformation in a controlled manner of a wrought product of composition as described above makes it possible to obtain a excellent compromise between static mechanical properties and those of tolerance to damage, in particular toughness. The metallurgical state obtained for the wrought products corresponds in particular to a T9 state according to standard EN515. According to an advantageous embodiment, the process for manufacturing a wrought product does not include any cold deformation step inducing a permanent deformation of at least 1% between the hot deformation step or, if this step is present, solution and the income stage.

La combinaison de la composition choisie, en particulier de la teneur en Mg, Li et Mn si ce dernier est présent, et des paramètres de transformation, en particulier l'ordre des étapes du procédé de fabrication, permet avantageusement d'obtenir des produits corroyés ayant un compromis de propriétés amélioré tout à fait particulier, en particulier le compromis entre la résistance mécanique et la tolérance aux dommages, tout en présentant une faible densité et une bonne performance en corrosion.The combination of the composition chosen, in particular the content of Mg, Li and Mn if the latter is present, and the processing parameters, in particular the order of the steps of the manufacturing process, advantageously makes it possible to obtain wrought products. having a very particular improved property compromise, in particular the compromise between mechanical strength and damage tolerance, while exhibiting low density and good corrosion performance.

Les produits corroyés selon l'invention sont préférentiellement des produits filés tels que des profilés, des produits laminés tels que des tôles ou des tôles épaisses et/ou des produits forgés.The wrought products according to the invention are preferably extruded products such as profiles, rolled products such as sheets or thick sheets and / or forged products.

L'invention a également pour objet des produits corroyés susceptibles d'être obtenus selon le procédé précédemment décrit, avantageusement de tels produits déformé à froid avec une déformation permanente à froid supérieure à 4%. En effet, de tels produits présentent des caractéristiques tout à fait nouvelles et particulières.A subject of the invention is also wrought products capable of being obtained according to the method described above, advantageously such products cold-deformed with a permanent cold-deformation of greater than 4%. Indeed, such products have quite new and particular characteristics.

Les produits corroyés susceptibles d'être obtenus par le procédé selon la divulgation, avantageusement lesdits porduits avec une déformation permanente à froid supérieure à 4%, ont, en particulier à mi-épaisseur, pour une épaisseur comprise entre 0,5 et 15 mm, au moins une propriété de résistance mécanique statique choisie parmi les propriétés (i) à (iii) et au moins une propriété de tolérance aux dommages choisie parmi les propriétés (iv) à (v) :

  1. (i) une résistance à la rupture Rm (L) ≥ 440 MPa, préférentiellement Rm (L) ≥ 445 MPa, plus préférentiellement Rm (L) ≥ 450 MPa et, plus préférentiellement encore Rm (L) ≥ 465 MPa;
  2. (ii) une limite d'élasticité en traction Rp0,2 (L) ≥ 360 MPa, préférentiellement Rp0,2 (L) ≥ 380 MPa, plus préférentiellement Rp0,2 (L) ≥ 390 MPa et, plus préférentiellement encore, Rp0,2 (L) ≥ 400 MPa;
  3. (iii) une limite d'élasticité en traction Rp0,2 (TL) ≥ 330 MPa et préférentiellement Rp0,2 (TL) ≥ 340 MPa et, plus préférentiellement encore, Rp0,2 (TL) ≥ 370 MPa;
  4. (iv) une ténacité, mesurée selon la norme ASTM E399 avec des éprouvettes CT8 de largeur W = 16 mm et d'épaisseur = 8mm, KQ (L-T) ≥ 20 MPa√m, de préférence KQ (L-T) ≥ 22 MPa√m ;
  5. (v) un facteur d'intensité de contrainte correspondant à la force maximale Pmax, mesurée selon la norme ASTM E399 avec des éprouvettes CT8 de largeur W = 16 mm et d'épaisseur = 8mm, Kmax (L-T) ≥ 20 MPa√m, de préférence Kmax (L-T) ≥ 25 MPa√m.
The wrought products capable of being obtained by the process according to the disclosure, advantageously said products with a permanent cold set of greater than 4%, have, in particular at mid-thickness, for a thickness of between 0.5 and 15 mm, at least one static mechanical strength property chosen from properties (i) to (iii) and at least one damage tolerance property chosen from properties (iv) to (v):
  1. (i) a tensile strength Rm (L) ≥ 440 MPa, preferably Rm (L) ≥ 445 MPa, more preferably Rm (L) ≥ 450 MPa and, more preferably still Rm (L) ≥ 465 MPa;
  2. (ii) a tensile yield strength Rp0.2 (L) ≥ 360 MPa, preferably Rp0.2 (L) ≥ 380 MPa, more preferably Rp0.2 (L) ≥ 390 MPa and, more preferably still, Rp0, 2 (L) ≥ 400 MPa;
  3. (iii) a tensile yield strength Rp0.2 (TL) ≥ 330 MPa and preferably Rp0.2 (TL) ≥ 340 MPa and, more preferably still, Rp0.2 (TL) ≥ 370 MPa;
  4. (iv) toughness, measured according to standard ASTM E399 with CT8 specimens of width W = 16 mm and thickness = 8mm, K Q (LT) ≥ 20 MPa√m, preferably K Q (LT) ≥ 22 MPa √m;
  5. (v) a stress intensity factor corresponding to the maximum force Pmax, measured according to standard ASTM E399 with test pieces CT8 of width W = 16 mm and thickness = 8mm, Kma x (LT) ≥ 20 MPa√m , preferably K max (LT) ≥ 25 MPa√m.

Selon un mode de réalisation préféré de la divulgation, les produits corroyés susceptibles d'être obtenus par le procédé selon l'invention ont, pour une épaisseur comprise entre 0,5 et 15 mm, à mi-épaisseur au moins deux propriétés de résistance mécanique statique choisies parmi les propriétés (i) à (iii) et au moins une propriété de tolérance aux dommages choisies parmi les propriétés (iv) à (v).According to a preferred embodiment of the disclosure, the wrought products that can be obtained by the process according to the invention have, for a thickness of between 0.5 and 15 mm, at mid-thickness at least two mechanical strength properties static selected from properties (i) to (iii) and at least one damage tolerance property selected from properties (iv) to (v).

Les produits corroyés selon l'invention présentent en outre une moindre propension au délaminage, ce dernier étant évalué sur les surfaces de rupture d'éprouvettes Klc suivant la norme ASTME399 (éprouvette CT8, B = 8mm, W = 16 mm).The wrought products according to the invention also exhibit a lower propensity for delamination, the latter being evaluated on the fracture surfaces of Klc test pieces according to the ASTME399 standard (test piece CT8, B = 8mm, W = 16 mm).

Les produits filés selon l'invention présentent des caractéristiques particulièrement avantageuses. Les produits filés ont une épaisseur comprise entre 0,5 mm et 15 mm, mais selon la divulgation des produits d'épaisseur supérieure à 15 mm, jusque 50 mm ou même 100 mm ou plus peuvent avoir également des propriétés avantageuses. L'épaisseur des produits filés est définie selon la norme EN 2066 : 2001 : la section transversale est divisée en rectangles élémentaires de dimensions A et B ; A étant toujours la plus grande dimension du rectangle élémentaire et B pouvant être considéré comme l'épaisseur du rectangle élémentaire. La semelle est le rectangle élémentaire présentant la plus grande dimension A.The products spun according to the invention exhibit particularly advantageous characteristics. The spun products have a thickness of between 0.5mm and 15mm, but according to the disclosure of products with a thickness greater than 15mm, up to 50mm or even 100mm or more can also have advantageous properties. The thickness of extruded products is defined according to standard EN 2066: 2001: the cross section is divided into elementary rectangles of dimensions A and B; A being always the largest dimension of the elementary rectangle and B being able to be considered as the thickness of the elementary rectangle. The sole is the elementary rectangle with the largest dimension A.

Les produits corroyés selon l'invention sont avantageusement utilisés pour réaliser des éléments de structure d'aéronef, notamment d'avions. Des éléments de structure d'aéronef préférés sont notamment une peau de fuselage, un cadre de fuselage, un raidisseur ou une lisse de fuselage ou encore une peau de voilure, un raidisseur de voilure, une nervure ou un longeron. Ces aspects, ainsi que d'autres de l'invention sont expliqués plus en détails à l'aide des exemples illustratifs et non limitatifs suivants.The wrought products according to the invention are advantageously used to produce structural elements of an aircraft, in particular of airplanes. Preferred aircraft structural elements are in particular a fuselage skin, a fuselage frame, a stiffener or a fuselage stringer or else a wing skin, a wing stiffener, a rib or a spar. These and other aspects of the invention are explained in more detail with the aid of the following illustrative and non-limiting examples.

ExemplesExamples Exemple 1Example 1

Plusieurs formes brutes en alliage Al-Mg-Li dont la composition est donnée dans le tableau 1 ont été coulées. Les alliages A et B ont tous deux une composition apte à la mise en œuvre du procédé selon l'invention. La densité des alliages A et B, calculée en conformité avec la procédure de The Aluminium Association décrite en pages 2-12 et 2-13 de « Aluminum Standards and Data » , est de 2,55. Tableau 1 - Composition en % en poids et densité des alliages Al-Mg-Li utilisés Alliage Ag Li Si Fe Cu Ti Mn Mg Zn Zr Na (ppm) Ca (ppm) Densité A 0,10 1,39 0,04 0,05 0,01 0,03 0,14 4,56 0,03 0,12 8 22 2,55 B 0,11 1,39 0,03 0,06 0,01 0,03 0,41 4,57 0,03 0,11 8 15 2,55 Several crude forms of Al-Mg-Li alloy, the composition of which is given in Table 1, were cast. Alloys A and B both have a composition suitable for carrying out the process according to the invention. The density of alloys A and B, calculated in accordance with the procedure of The Aluminum Association described on pages 2-12 and 2-13 of “Aluminum Standards and Data” , is 2.55. Table 1 - Composition in% by weight and density of Al-Mg-Li alloys used Alloy Ag Li Yes Fe Cu Ti Mn Mg Zn Zr Na (ppm) Ca (ppm) Density AT 0.10 1.39 0.04 0.05 0.01 0.03 0.14 4.56 0.03 0.12 8 22 2.55 B 0.11 1.39 0.03 0.06 0.01 0.03 0.41 4.57 0.03 0.11 8 15 2.55

Des billettes de 358 mm de diamètre ont été réalisées dans les formes brutes. Elles ont été réchauffées à 430-440°C puis déformées à chaud par filage sur une presse sous forme d'un profilé pour cadre de fuselage tel que représenté à la figure 1. Les produits ainsi filés ont été trempés à l'air (trempe sur presse). Ils ont ensuite subi :

  • pour les produits à l'état final T6 : un revenu bi-palier effectué pendant 30h à 120°C suivi de 10h à 100°C ;
  • pour les produits à l'état final T8 : une traction contrôlée avec déformation permanente de 3 ou 5% (respectivement T8-3% et T8-5%) puis un revenu bi-palier effectué pendant 30h à 120°C suivi de 10h à 100°C;
  • pour les produits à l'état final T9 : un revenu bi-palier effectué pendant 30h à 120°C suivi de 10h à 100°C puis une traction contrôlée avec déformation permanente de 3 ou 5% (respectivement T9-3% et T9-5%).
Billet 358 mm in diameter were produced in the rough shapes. They were heated to 430-440 ° C then hot deformed by extrusion on a press in the form of a profile for a fuselage frame as shown in figure 1 . The products thus spun were air quenched (press quenching). They then underwent:
  • for products in the final state T6: a two-stage tempering carried out for 30 hours at 120 ° C followed by 10 hours at 100 ° C;
  • for products in the final state T8: controlled traction with permanent deformation of 3 or 5% (respectively T8-3% and T8-5%) then a two-stage tempering carried out for 30 hours at 120 ° C followed by 10 hours at 100 ° C;
  • for the products in the final state T9: a two-stage tempering carried out for 30h at 120 ° C followed by 10h at 100 ° C then a controlled traction with permanent deformation of 3 or 5% (respectively T9-3% and T9- 5%).

Des échantillons ont été testés pour déterminer leurs propriétés mécaniques statiques (limite d'élasticité Rp0,2 en MPa, résistance à la rupture Rm en MPa, et allongement A en % ).Samples were tested to determine their static mechanical properties (yield strength R p0.2 in MPa, tensile strength R m in MPa, and elongation A in%).

Les résultats obtenus sont donnés dans les tableaux 2 (sens L) et 3 (sens TL) ci-dessous. Ces résultats sont les moyennes de 4 mesures effectuées sur des échantillons pleine épaisseur prélevés sur 4 positions sur le cadre de fuselage (postions référencées a, b, c et d sur la figure 1) pour le sens L et de 2 mesures effectuées sur des échantillons pleine épaisseur prélevés sur 1 position unique, référencée c sur la figure 1, pour le sens TL. Tableau 2 - Propriétés mécaniques des produits obtenus (sens L) Alliage Propriété mécanique T6 T8 (3%) T8 (5%) T9 (3%) T9 (5%) A Rm (MPa) 427 447 449 449 460 Rp0,2 (MPa) 298 330 346 382 409 A (%) 12 11 10 9 9 B Rm (MPa) 441 453 459 460 468 Rp0,2 (MPa) 321 340 354 398 418 A (%) 11 10 9 8 7 Tableau 3 - Propriétés mécaniques des produits obtenus (sens TL) Alliage Propriété mécanique T6 T8 (3%) T8 (5%) T9 (3%) T9 (5%) A Rm (MPa) 441 441 439 441 454 Rp0,2 (MPa) 308 308 302 335 371 A (%) 14 14 13 11 9 B Rm (MPa) 444 456 459 456 467 Rp0,2 (MPa) 298 309 333 328 347 A (%) 15 14 14 10 11 The results obtained are given in Tables 2 (direction L) and 3 (direction TL) below. These results are the averages of 4 measurements taken on full thickness samples taken from 4 positions on the fuselage frame (positions referenced a, b, c and d on the figure 1 ) for the L direction and of 2 measurements carried out on full thickness samples taken from 1 single position, referenced c on the figure 1 , for the TL direction. Table 2 - Mechanical properties of the products obtained (direction L) Alloy Mechanical property T6 T8 (3%) T8 (5%) T9 (3%) T9 (5%) AT Rm (MPa) 427 447 449 449 460 Rp0.2 (MPa) 298 330 346 382 409 AT (%) 12 11 10 9 9 B Rm (MPa) 441 453 459 460 468 Rp0.2 (MPa) 321 340 354 398 418 AT (%) 11 10 9 8 7 Alloy Mechanical property T6 T8 (3%) T8 (5%) T9 (3%) T9 (5%) AT Rm (MPa) 441 441 439 441 454 Rp0.2 (MPa) 308 308 302 335 371 AT (%) 14 14 13 11 9 B Rm (MPa) 444 456 459 456 467 Rp0.2 (MPa) 298 309 333 328 347 AT (%) 15 14 14 10 11

Les propriétés mécaniques, en particulier la contrainte maximale supportable par le produit ou résistance à la rupture, Rm, et la limite d'élasticité Rp0,2 (valeur de contrainte pour une déformation plastique de 0,2%) des produits à l'état T9 sont globalement significativement plus hautes que celles des produits aux états T8 ou T6. Par ailleurs, les propriétés mécaniques, en particulier Rp0,2, augmentent avec l'augmentation de la traction contrôlée (T6 < T8-3% < T8-5% < T9-3% < T9-5%).The mechanical properties, in particular the maximum stress tolerable by the product or tensile strength, Rm, and the elastic limit Rp0.2 (stress value for a plastic deformation of 0.2%) of the products in the T9 are globally significantly higher than those of products in T8 or T6 states. Furthermore, the mechanical properties, in particular Rp0.2, increase with the increase in controlled traction (T6 <T8-3% <T8-5% <T9-3% <T9-5%).

Une teneur en Mn de l'alliage Al-Mg-Li d'environ 0,4 % en poids (alliage B) permet d'améliorer significativement la résistance mécanique (Rp0,2 et Rm), en particulier dans le sens L, de l'alliage par rapport à celle d'un alliage présentant une teneur en Mn d'environ 0,14 % en poids (alliage A).An Mn content of the Al-Mg-Li alloy of about 0.4% by weight (alloy B) significantly improves the mechanical strength (Rp0.2 and Rm), in particular in the L direction, of the alloy relative to that of an alloy having an Mn content of about 0.14% by weight (alloy A).

Exemple 2Example 2

Plusieurs formes brutes en alliage Al-Mg-Li dont la composition est donnée dans le tableau 1 de l'exemple précédent ont été coulées. Les alliages A et B ont tous deux une composition apte à la mise en œuvre du procédé selon l'invention.Several crude forms of Al-Mg-Li alloy, the composition of which is given in Table 1 of the preceding example, were cast. Alloys A and B both have a composition suitable for carrying out the process according to the invention.

Des billettes de 358 mm de diamètre ont été réalisées dans les formes brutes. Elles ont été réchauffées à 430-440°C puis déformées à chaud par filage sur une presse sous forme d'une barre plate (100 mm x 10 mm). Les produits ainsi filés ont été trempés à l'air (trempe sur presse). Ils ont ensuite subit :

  • pour les produits à l'état final T6 : un revenu bi-palier effectué pendant 30h à 120°C suivi de 10h à 100°C ;
  • pour les produits à l'état final T8 : une traction contrôlée avec déformation permanente de 3 ou 5% (respectivement T8-3% et T8-5%) puis un revenu bi-palier effectué pendant 30h à 120°C suivi de 10h à 100°C;
  • pour les produits à l'état final T9 : un revenu bi-palier effectué pendant 30h à 120°C suivi de 10h à 100°C puis une traction contrôlée avec déformation permanente de 3 ou 5% (respectivement T9-3% et T9-5%).
Billet 358 mm in diameter were produced in the rough shapes. They were reheated to 430-440 ° C then hot deformed by extrusion on a press in the form of a flat bar (100 mm × 10 mm). The products thus spun were air quenched (press quenching). They then suffered:
  • for products in the final state T6: a two-stage tempering carried out for 30 hours at 120 ° C followed by 10 hours at 100 ° C;
  • for products in the final state T8: controlled traction with permanent deformation of 3 or 5% (respectively T8-3% and T8-5%) then a two-stage tempering carried out for 30 hours at 120 ° C followed by 10 hours at 100 ° C;
  • for the products in the final state T9: a two-stage tempering carried out for 30h at 120 ° C followed by 10h at 100 ° C then a controlled traction with permanent deformation of 3 or 5% (respectively T9-3% and T9- 5%).

Des échantillons cylindriques de 4 mm de diamètre ont été testés pour déterminer leurs propriétés mécaniques statiques (limite d'élasticité, Rp0,2, en MPa ; résistance à la rupture, Rm, en MPa et allongement, A, en % ).Cylindrical samples of 4 mm in diameter were tested to determine their static mechanical properties (yield strength, R p0.2, in MPa; tensile strength, Rm, in MPa and elongation, A, in%).

Les résultats obtenus sont donnés dans les tableaux 4 (sens L) et 5 (sens TL) ci-dessous. Tableau 4 - Propriétés mécaniques des produits obtenus (sens L). Alliage Propriété mécanique T6 T8 (3%) T8 (5%) T9 (3%) T9 (5%) A Rm (MPa) 421 439 441 444 453 Rp0,2 (MPa) 286 319 330 381 398 A (%) 13 11 11 9 10 B Rm (MPa) 439 453 456 451 462 Rp0,2 (MPa) 309 337 352 383 424 A (%) 11 10 8 9 6 Tableau 5 - Propriétés mécaniques des produits obtenus (sens TL). Alliage Propriété mécanique T6 T8 (3%) T8 (5%) T9 (3%) T9 (5%) A Rm (MPa) 400 428 417 430 438 Rp0,2 (MPa) 267 300 303 334 345 A (%) 16 17 15 14 14 B Rm (MPa) 423 437 447 448 449 Rp0,2 (MPa) 290 315 323 339 371 A (%) 16 16 16 14 12 The results obtained are given in Tables 4 (direction L) and 5 (direction TL) below. Table 4 - Mechanical properties of the products obtained (direction L). Alloy Mechanical property T6 T8 (3%) T8 (5%) T9 (3%) T9 (5%) AT Rm (MPa) 421 439 441 444 453 Rp0.2 (MPa) 286 319 330 381 398 AT (%) 13 11 11 9 10 B Rm (MPa) 439 453 456 451 462 Rp0.2 (MPa) 309 337 352 383 424 AT (%) 11 10 8 9 6 Alloy Mechanical property T6 T8 (3%) T8 (5%) T9 (3%) T9 (5%) AT Rm (MPa) 400 428 417 430 438 Rp0.2 (MPa) 267 300 303 334 345 AT (%) 16 17 15 14 14 B Rm (MPa) 423 437 447 448 449 Rp0.2 (MPa) 290 315 323 339 371 AT (%) 16 16 16 14 12

La limite d'élasticité (valeur de contrainte pour une déformation plastique de 0,2%, Rp0,2) des produits à l'état T9 est significativement plus haute que celles des produits aux états T8 ou T6. Par ailleurs, Rp0,2 augmente avec l'augmentation de la contrainte de la traction contrôlée (T6 < T8-3% < T8-5% < T9-3% < T9-5%).The yield strength (stress value for a plastic deformation of 0.2%, Rp0.2) of the products in the T9 state is significantly higher than those of the products in the T8 or T6 states. Moreover, Rp0.2 increases with the increase in the controlled tensile stress (T6 <T8-3% <T8-5% <T9-3% <T9-5%).

Une teneur en Mn de l'alliage Al-Mg-Li d'environ 0,4 % en poids (alliage B) permet d'améliorer significativement la résistance mécanique de alliage (Rp0,2 et Rm) par rapport à celle d'un alliage présentant une teneur en Mn d'environ 0,14 % en poids (alliage A).An Mn content of the Al-Mg-Li alloy of about 0.4% by weight (alloy B) significantly improves the mechanical strength of the alloy (Rp0.2 and Rm) compared to that of a alloy having an Mn content of about 0.14% by weight (alloy A).

La ténacité des produits a été caractérisée par l'essai de Klc suivant la norme ASTM E399. Les essais ont été effectués avec une éprouvette CT8 (B = 8mm, W = 16 mm) prélevée à mi-épaisseur. Les valeurs de KQ ont toujours été invalides selon la norme ASTM E399, en particulier par rapport au critère Pmax/PQ ≤ 1,10. Pour cela, les résultats sont présentés en Kmax (facteur d'intensité de contrainte correspondant à la force maximale Pmax). Les résultats sont reportés dans les tableaux 6 et 7 et illustrés aux figures 2 et 3 (éprouvettes L-T et T-L respectivement). Ces résultats sont les moyennes d'au moins deux 2 valeurs. Tableau 6 - Résultats des essais de ténacité sur éprouvettes L-T (Kmax et KQ en MPa√m) Alliage Ténactité T8 (3%) T8 (5%) T9 (3%) T9 (5%) A Kmax L-T 32,2 33,6 32,5 25,9 KQ L-T 24,6 26,3 25,2 22,3 B Kmax L-T 30,0 32,2 25,9 - KQ L-T 24,6 26,2 22,0 - Tableau 7 - Résultats des essais de ténacité sur éprouvettes T-L (Kmax et KQ en MPa√m) Alliage Ténactité T8 (3%) T8 (5%) T9 (3%) T9 (5%) A Kmax T-L 30,8 29,5 29,9 - KQ T-L 25,4 25,0 24,7 - B Kmax T-L 28,5 28,2 25,2 - KQ T-L 24,2 24,3 22,4 - The toughness of the products was characterized by the Klc test according to the ASTM E399 standard. The tests were carried out with a CT8 specimen (B = 8mm, W = 16mm) taken at mid-thickness. The values of K Q have always been invalid according to the standard ASTM E399, in particular compared to the criterion P max / P Q ≤ 1.10. For this, the results are presented in K max (stress intensity factor corresponding to the maximum force P max ). The results are reported in Tables 6 and 7 and illustrated in figures 2 and 3 (LT and TL specimens respectively). These results are the means of at least two 2 values. Table 6 - Results of toughness tests on LT specimens (K <sub> max </sub> and K <sub> Q </sub> in MPa√m) Alloy Tenacity T8 (3%) T8 (5%) T9 (3%) T9 (5%) AT K max LT 32.2 33.6 32.5 25.9 K Q LT 24.6 26.3 25.2 22.3 B K max LT 30.0 32.2 25.9 - K Q LT 24.6 26.2 22.0 - Alloy Tenacity T8 (3%) T8 (5%) T9 (3%) T9 (5%) AT K max TL 30.8 29.5 29.9 - K Q TL 25.4 25.0 24.7 - B K max TL 28.5 28.2 25.2 - K Q TL 24.2 24.3 22.4 -

Les produits selon l'invention présentent une ténacité satisfaisante quelle que soit la teneur en Mn de l'alliage.The products according to the invention exhibit satisfactory toughness whatever the Mn content of the alloy.

La figure 2 illustre la limite d'élasticité, Rp0,2, des produits du présent exemple en fonction de la ténacité, KQ (toutes les valeurs de KQ sont invalides en raison du critère Pmax / PQ ≤ 1,10 ). La figure 3 illustre la limite d'élasticité, Rp0,2, des produits du présent exemple en fonction du facteur d'intensité de contrainte correspondant à la contrainte maximale, Kmax.The figure 2 illustrates the yield strength, Rp0.2, of the products of this example as a function of the toughness, K Q (all values of K Q are invalid due to the criterion P max / P Q ≤ 1.10). The figure 3 illustrates the yield strength, Rp0.2, of the products of this example as a function of the stress intensity factor corresponding to the maximum stress, K max .

Les produits en T9 présentent un excellent compromis entre leurs propriétés statiques, en particulier Rp0,2, et leur ténacité, KQ, ou leur facteur d'intensité de contrainte correspondant à la force maximale, Kmax.T9 products present an excellent compromise between their static properties, in particular Rp0.2, and their toughness, K Q , or their stress intensity factor corresponding to the maximum force, K max .

Le délaminage a été quantifié de façon semi-quantitative sur les surfaces de rupture des éprouvettes Klc précédemment décrites selon un score de 0 à 2 : score 0 = absence de délaminage visible, score 1 = faible délaminage, score 2 = délaminage marqué (plusieurs feuillets/fissures secondaires dans le sens L visibles). Les tableaux 8 et 9 récapitulent les scores attribués aux différentes éprouvettes (éprouvettes L-T et T-L respectivement). Tableau 8 - Evaluation du délaminage sur éprouvettes L-T (scores) Alliage T8 (3%) T8 (5%) T9 (3%) T9 (5%) A 1 2 2 1 B 0 1 0 - Tableau 9 - Evaluation du délaminage sur éprouvettes T- L (scores) Alliage T8 (3%) T8 (5%) T9 (3%) T9 (5%) A 0 1 1 - B 0 0 0 - The delamination was quantified semi-quantitatively on the fracture surfaces of the Klc specimens previously described according to a score of 0 to 2: score 0 = absence of visible delamination, score 1 = weak delamination, score 2 = marked delamination (several sheets / secondary cracks in the L direction visible). Tables 8 and 9 summarize the scores assigned to the different test pieces (LT and TL test pieces respectively). Table 8 - Evaluation of delamination on LT specimens (scores) Alloy T8 (3%) T8 (5%) T9 (3%) T9 (5%) AT 1 2 2 1 B 0 1 0 - Alloy T8 (3%) T8 (5%) T9 (3%) T9 (5%) AT 0 1 1 - B 0 0 0 -

Les produits en alliage B présentent un délaminage plus faible que les produits en alliage A.Alloy B products have lower delamination than Alloy A products.

Claims (12)

  1. Process for manufacturing a wrought product in the T9 temper as per the standard EN515 comprising the successive steps:
    (a) casting an unwrought product made of aluminium alloy of composition, as a % by weight: Mg: 4.0 - 5.0; Li: 1.0 - 1.8; Zr: 0.05 - 0.15; Mn: 0.6; Ag: ≤ 0.5; Fe: ≤ 0.1; Ti: < 0.15; Si: ≤ 0.05; other elements ≤ 0.05 each and ≤ 0.15 in association; the remainder aluminium;
    (b) optionally, homogenising said unwrought product;
    (c) hot working said unwrought product to obtain a hot-worked product;
    (d) subjecting said hot-worked product to a solution heat treatment at a temperature of 360°C to 460°C, preferentially 380-420°C, for 15 minutes to 8 hours;
    (e) quenching said hot-worked product;
    (f) optionally, straightening or flattening said worked and quenched product;
    (g) aging said worked and quenched product;
    (h) cold working the worked product thus aged in a controlled manner to obtain a tensile cold permanent set from 1 to 10%, preferably from 2 to 6%, even more preferably from 3 to 5% in order to obtain a wrought product in the T9 temper as per the standard EN515.
  2. Process according to claim 1 wherein the hot working of step (c) is a deformation by extruding the unwrought product.
  3. Process according to claim 1 or 2 wherein the hot working of step (c) is carried out at an initial temperature greater than 400°C, preferably from 420°C to 450°C.
  4. Process according to any one of claims 1 to 3 wherein the quenching of step (e) is a press quenching.
  5. Process according to any one of claims 1 to 4 wherein the quenching of step (e) is performed in air.
  6. Process according to any one of claims 1 to 5 wherein the aging of the hot-worked and quenched product of step (g) is carried out by heating, in one or more stages, at a temperature less than 150°C, preferably at a temperature from 70°C to 140°C, for 5 to 100 hours.
  7. Process according to claim 1 wherein said unwrought product made of aluminium alloy has an Mn content, as a % by weight, from 0.2 to 0.6, preferably from 0.35 to 0.5.
  8. Process according to claim 1 wherein said unwrought product made of aluminium alloy has a Zn content, as a % by weight, less than 0.04%, preferably less than or equal to 0.03%.
  9. Process according to claim 1 wherein said unwrought product made of aluminium alloy has an Fe content, as a % by weight, less than 0.08%, preferably less than or equal to 0.07%, more preferably less than or equal to 0.06%.
  10. Process according to claim 1 wherein said unwrought product made of aluminium alloy has an Li content, as a % by weight, less than 1.6%, preferably less than or equal to 1.5%, more preferably less than or equal to 1.4%.
  11. Wrought product that can be obtained according to any one of the processes of claims 1 to 10 having at mid-thickness, for a thickness between 0.5 and 15 mm, the thickness of the extruded products being defined as per the standard EN 2066:2001, at least one static mechanical strength property from properties (i) to (ii) and at least one damage tolerance property from properties (iii) to (iv):
    (i) a tensile yield strength Rp0.2 in the L direction ≥ 360 MPa and preferably Rp0.2 in the L direction ≥ 380 MPa and, more preferably, Rp0.2 in the direction L ≥ 400 MPa;
    (ii) a tensile yield strength in the TL direction ≥ 330 MPa and preferably Rp0.2 in the TL direction ≥ 340 MPa and, more preferably, Rp0.2 in the TL direction ≥ 370 MPa;
    (iii) a toughness, measured as per the standard ASTM E399 with CT8 test specimens of width W= 16 mm and of thickness = 8 mm, KQ in the T-L direction ≥ 20 MPa√m, preferably KQ in the L-T direction ≥ 22 MPa√m;
    (iv) a stress intensity factor corresponding to the maximum force Pmax, measured as per the standard ASTM E399 with CT8 test specimens of width W = 16 mm and of thickness = 8 mm, Kmax in the T-L direction ≥ 20 MPa√m, preferably Kmax in the L-T direction ≥ 25 MPa√m.
  12. Use of a wrought product according to claim 11, for producing an aircraft structural element, preferably a fuselage skin, a fuselage frame, a fuselage stiffener or stringer, or a wing skin, a wing stiffener, a rib or a spar.
EP15785160.1A 2014-09-29 2015-09-29 Method of fabrication of a wrought product of an alloy of aluminium- magnesium-lithium, wrougt product and use of the product Active EP3201371B1 (en)

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FR1402187A FR3026410B1 (en) 2014-09-29 2014-09-29 CORROYE PRODUCT ALLOY ALUMINUM MAGNESIUM LITHIUM
FR1402186A FR3026411B1 (en) 2014-09-29 2014-09-29 METHOD FOR MANUFACTURING LITHIUM MAGNESIUM ALUMINUM ALLOY PRODUCTS
PCT/FR2015/052581 WO2016051061A1 (en) 2014-09-29 2015-09-29 Method for manufacturing products made of magnesium-lithium-aluminum alloy

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