Classifications

• • 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
  • C22C21/12—Alloys based on aluminium with copper as the next major constituent
  • C22C21/16—Alloys based on aluminium with copper as the next major constituent with magnesium
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64C—AEROPLANES; HELICOPTERS
  • B64C1/00—Fuselages; Constructional features common to fuselages, wings, stabilising surfaces or the like
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C1/00—Making non-ferrous alloys
  • C22C1/02—Making non-ferrous alloys by melting
• • 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
  • C22C21/12—Alloys based on aluminium with copper as the next major constituent
  • C22C21/18—Alloys based on aluminium with copper as the next major constituent with zinc
• • 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
  • C22F1/057—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 copper as the next major constituent
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64C—AEROPLANES; HELICOPTERS
  • B64C1/00—Fuselages; Constructional features common to fuselages, wings, stabilising surfaces or the like
  • B64C2001/0054—Fuselage structures substantially made from particular materials
  • B64C2001/0081—Fuselage structures substantially made from particular materials from metallic materials

Definitions

• the invention relates to thin sheets of 2XXX alloys, more particularly, of such products, their methods of manufacture and use, intended in particular for aeronautical and aerospace construction.
• Alloys AA2024 or AA2524 in metallurgical state T3 are alloys commonly used for the manufacture of fuselage sheets.
• Application EP1 170394 A1 describes such alloys for the production of thin sheets for the aeronautical industry. These sheets are described to exhibit increased resistance to crack propagation. However, their mechanical strength / toughness compromise is not as efficient as other alloys such as the AA2139 alloy.
• the AA2139 alloy described in particular by US Pat. No. 7,229,508, is indeed an alloy which is quite efficient in terms of properties for the fuselage sheets but has a relatively high density compared to the previous solutions.
• the invention relates to a thin sheet of aluminum-based alloy essentially recrystallized and of thickness between 0.25 and 12 mm comprising, in% by weight,
• the thin sheet has a Cu content of between 3.4 and 3.8% by weight.
• the Mg content is between 0.55 and 0.75% by weight
• the Mn content is between 0.2 and 0.5% by weight, preferably between 0.25 and 0.45% by weight.
• the Zr content is between 0.01 and 0.04% by weight or less than 0.01% by weight.
• the thin sheet is such that:
• the Ag content is between 0.01 and 0.25% by weight and the Zn content is less than 0.1% by weight or
• the Ag content is less than 0.2% by weight, preferably 0.05 and 0.2% by weight and the Zn content is between 0.2 or 0.4% by weight or - the Ag content is less than 0.1% by weight and the Zn content is less than 0.1% by weight, preferably the Ag content is between 0.02 and 0.1% by weight and the Zn content is less than 0 0.05% by weight, more preferably still, the Ag content is between 0.05 and 0.1% by weight and the Zn content is less than 0.05% by weight.
• the report Cu / Mg is between 4.5 and 6.5, preferably this ratio is such that 5 ⁇ Cu / Mg ⁇
• the thin sheet has, in state T8, at least two of the following properties, preferably at least three, even more preferably all of the following properties:
• tempering of the fractionated sheet by heating at a temperature between 130 and 180 ° C for a period of 10 to 100 h.
• the income from the fractionated sheet is produced by heating to a temperature between 155 and 165 ° C for a period of 28 to 60 hours.
• the invention also relates to the use of a sheet as described above or manufactured according to the method detailed above as a fuselage sheet or sheet for the development of hybrid aluminum-composite laminate parts also known by the acronym FML (Fiber Metal Laminate) for wing or fuselage applications in the aeronautical industry.
• FML Fiber Metal Laminate
• FIG. 1 illustrates the compromise between toughness (propagation energy UPE in the direction TL in J / mm 2 ) - mechanical resistance (conventional elastic limit at 0.2% elongation R p o, 2 directions TL in MPa) of different sheets of Example 1.
• FIG. 2 illustrates the compromise between toughness (propagation energy UPE in the direction TL in J / mm 2 ) - mechanical resistance (conventional elastic limit at 0.2% elongation R p o, 2 directions TL in MPa) of different sheets of Example 3.
• the static mechanical characteristics in tension in other words the tensile strength R m , the conventional elastic limit at 0.2% elongation R p o, 2, and the elongation at rupture A, are determined by a tensile test according to standard ISO 6892-1: 2009, the sampling and the direction of the test being defined by standard IS06361-1: 2011.
• the cracking speed (da / dN) is determined according to standard ASTM E 647-15.
• the test described in this standard makes it possible to determine a curve da / dN-DK where DK is the variation of the intensity factor of applied stress and da / dN is the speed of advance of crack.
• the toughness was evaluated by the unit propagation energy (Unit Propagation Energy, UPE, also called “Kahn tenacity”) of a tear resistance test according to standard ASTM B871-01 (2013) in the direction TL. It is expressed in J / mm z .
• the granular structure of the samples is characterized in the LxTC plane at mid-thickness, t / 2 and is evaluated quantitatively after a metallographic attack of anodic oxidation type and under polarized light.
• the term “essentially recrystallized” is used when the granular structure has a predominant proportion of recrystallized grains, typically when more than 80%, preferably more than 90% and more preferably still more than 95% of the grains are recrystallized.
• the recrystallized grains are isotropic and have a ratio aspect, that is to say a ratio between the average length and the average thickness less than or equal to 6, preferably less than or equal to 5 and preferably less than or equal to 4
• a low grain ratio aspect in the LxTC plan makes it possible in particular to improve the toughness of the products.
• a selected class of aluminum alloy containing specific and critical quantities of copper, magnesium, manganese in particular makes it possible to prepare thin sheets having an improved compromise of properties in particular compared to thin sheets of alloy 2524 to state T3.
• the invention relates to a thin sheet of aluminum alloy.
• thin sheet is meant here a rolled product with a thickness of between 0.25 and 12 mm, preferably between 0.3 and 8 mm, more preferably still between 0.5 and 5 mm.
• the aluminum-based alloy from which the thin sheet is made comprises, in% by weight, Cu 3.4 - 4.0; Mg 0.5 - 0.8; Mn 0.1 - 0.7; Fe ⁇ 0.15; If ⁇ 0.15; Zr ⁇ 0.04; Ag ⁇ 0.65; Zn ⁇ 0.5; unavoidable impurities ⁇ 0.05 each and ⁇ 0.15 in total; remains aluminum.
• the Cu content of the alloy is between 3.4 and 4.0% by weight, preferably between 3.4 and 3.8% by weight. Such a copper content makes it possible in particular to obtain an alloy having good mechanical strength. However, increasing the copper content in the alloy comes at the expense of density.
• the Mg content is between 0.5 and 0.8% by weight, preferably between 0.55 and 0.75% by weight and, more preferably still, between 0.6 and 0.7% by weight.
• the addition of Mg in the alloy is favorable for obtaining products having good mechanical characteristics and low density. However, beyond 0.8% by weight, magnesium is likely to degrade toughness.
• the Cu / Mg ratio is advantageously between 4.25 and 8, preferably between 4.5 and 6.5, more preferably still this ratio is such that 5 ⁇ Cu / Mg ⁇ 6.
• the ratio Cu / Mg is such that 5 ⁇ Cu / Mg ⁇ 5.5, preferably 5 ⁇ Cu / Mg ⁇ 5.3.
• the Cu / Mg ratio is such that 5.5 ⁇ Cu / Mg ⁇ 6, preferably 5.7 ⁇ Cu / Mg ⁇ 5.9.
• a Cu / Mg ratio greater than 8 is not favorable for the density of the sheet.
• a Cu / Mg ratio of less than 4.25 can lead to the production of a product that does not have sufficient toughness for some of the targeted applications.
• the Mn content of the alloy is between 0.1 and 0.7% by weight, preferably between 0.2 and 0.5% by weight, and more preferably still, between 0.25 and 0.45% by weight. weight.
• Mn is a refining element of the grain.
• a content of Mn greater than 0.7% by weight can be detrimental for the speed of cracking of the sheets (da / dN).
• the Zr content is less than or equal to 0.04% by weight, preferably less than or equal to 0.03% by weight. According to an advantageous embodiment, making it possible in particular to obtain an excellent compromise between Kahn toughness and elastic limit R P o, 2 , the Zr content is between 0.01 and 0.04% by weight. According to another embodiment, the Zr content is less than 0.01% by weight.
• the present inventors prefer in particular the alloy sheets comprising little Zr in order to be able to more easily recycle the sheets and the chips or scrap from machining resulting from the manufacturing processes of such sheets or from the aeronautical industries.
• the content of Zr selected makes it possible to maintain a granular structure which is essentially recrystallized whatever the method of manufacturing the sheet used.
• the Ag content is less than or equal to 0.65% by weight, preferably less than 0.5% by weight and more preferably less than 0.4% by weight.
• the Zn content is less than or equal to 0.5% by weight.
• the Ag content is between 0.01 and 0.25% by weight and the Zn content is less than 0.1% by weight.
• the sheets according to such an embodiment have in particular an excellent tenacity compromise (in particular Kahn tenacity) - R PO , 2 .
• the propagation energy UPE (TL) of such sheets is advantageously greater than 0.32 J / mm 2 and preferably greater than 0.4 J / mm 2 while the limit with elasticity R p o, 2 (TL) is greater than 350 MPa.
• such sheets also have a breaking strength R m (TL) greater than 400 MPa.
• the Ag content is less than 0.2% by weight, preferably between 0.1 and 0.2% by weight, and the Zn content is between 0.2 or 0.4% by weight. weight.
• the sheets according to such an embodiment have, in addition in particular a good compromise between toughness (in particular Kahn toughness) and R p o, 2 (TL), high mechanical properties both in the L direction and in the TL direction.
• such sheets have an elastic limit R p o, 2 (L) greater than 360 MPa and preferably greater than 395 MPa and a higher tensile strength R m (L) greater than 400 MPa and preferably greater 435 MPa as well as a yield strength R p o, 2 (TL) greater than 340 MPa and preferably greater than 365 MPa and preferably greater than 375 MPa and a higher breaking strength R m (TL) at 390 MPa and preferably greater than 405 MPa and more preferably greater than 425 MPa.
• such sheets have a Kahn tenacity such that the propagation energy UPE (TL) of such sheets is greater than 0.25 J / mm 2 and preferably greater than 0.3 J / mm 2 .
• UPE (TL) > -0.00175 R p o, 2 (TL ) + 0.96.
• the Ag content is less than 0.1% by weight and the Zn content is less than 0.1% by weight, preferably the Ag content is between 0.02 and 0, 1% by weight and the Zn content is less than 0.05% by weight, more preferably still, the Ag content is between 0.05 and 0.1% by weight and the Zn content is less than 0, 05% by weight.
• Such sheets have the advantage of a compromise in properties greater than that of 2524 T3 alloy sheets while presenting an economic advantage.
• the inventors have found that the content of Zn in the selected alloy influences the corrosion resistance. For example, a Zn content of about 0.3% by weight is beneficial for corrosion resistance while a content of 0.6% or more decreases the corrosion resistance.
• the elastic limit (R p0.2 ) / toughness (UPE) compromise can be improved in the presence of Zn but degrades for a content of 0.6% by weight and more.
• the Ag content is less than 0.01% by weight and the Zn content is less than 0.01% by weight.
• Iron and silicon generally affect the toughness properties.
• the contents of Fe and Si should preferably be at most 0.15% by weight each, preferably less than 0.10% by weight each.
• the thin sheets of aluminum-based alloy are manufactured using a process successively comprising the steps of preparing a bath of liquid metal comprising the alloying elements detailed above, of casting, homogenization, hot rolling and, optionally, cold, dissolution and quenching, controlled traction and tempering.
• the casting of a plate from the bath of liquid metal is carried out by semi-continuous casting with direct cooling.
• the plate is homogenized, preferably at a temperature between 480 and 560 ° C, more preferably still between 520 and 540 ° C, for a period of 4 to 20 hours, advantageously 10 to 14 hours.
• the homogenized plate is then hot rolled and, optionally, cold rolled into a sheet having a final thickness of between 0.25 and 12 mm.
• the plates are advantageously heated to a temperature of 420 to 480 ° C, preferably 440 to 460 ° C for 10 to 20 hours.
• the sheets are dissolved, for example at a temperature between 490 and 560 ° C, preferably 520 and 540 ° C for 20 min to 2 hours, preferably 30 minutes to 1 hour, then quenched.
• the homogenized sheets are subjected to a controlled traction with a permanent deformation of 0.5 to 6%, preferably from 3 to 6%.
• a controlled traction with a permanent deformation of 0.5 to 6%, preferably from 3 to 6%.
• Such cold work hardening rates can also be obtained by cold rolling, planing, forging or a combination of these methods and controlled traction.
• Controlled traction with a selected permanent deformation makes it possible in particular to increase the mechanical properties of the sheets according to the invention.
• the sheets are finally subjected to artificial aging or returned to a temperature between 130 and 180 ° C for a period of 10 to 100 h.
• the income of the towed sheet is produced by heating at a temperature between 155 and 165 ° C for a period of 28 to 60 hours.
• the income of the sheet fractionated is produced by heating at a temperature between 170 and 190 ° C for a period of 10 to 20 hours.
• the sheets according to the invention have, in state T8, that is to say after the tempering, at least two of the following properties, preferably at least three of the following properties, more preferably still all of the following properties:
• the sheets according to the invention have, in the T8 state, a compromise in toughness / mechanical strength, in particular a compromise in propagation energy UPE (TL) in J / mm 2 / conventional elastic limit at 0.2% of elongation R p o, 2 (TL) in MPa greater than that of alloy AA2524 in state T3.
• the high mechanical characteristics of the alloys according to the invention make it possible to manufacture thin sheets which are particularly suitable for the aeronautical industry, in particular for use as fuselage sheets or sheets for the production of hybrid aluminum-composite laminate parts also known as the acronym LML (Liber Metal Laminate) for wing or fuselage applications in the aeronautical industry.
• the sheet of the invention generally does not cause any particular problem during the subsequent operations performed on the sheet in the T8 state.
• the corrosion resistance of the sheet according to the invention is typically high.
• sheets of 2XXX alloy have been prepared.
• Table 1 Composition in% by weight of the plates and corresponding density
• the plates were homogenized for 12 hours at 530 ° C. They were preheated 12 to 18 hours at 450 ° C before being hot rolled and then cold rolled to obtain thin sheets with a thickness of 3 mm.
• the sheets were dissolved for 45 minutes at 530 ° C. and then fractionated with a controlled deformation of 2 to 4%. They have been subjected to artificial aging, the conditions of which are detailed in Table 2 below.
• the sheets D to K all presented an essentially recrystallized structure (recrystallization rate at T / 2 greater than 90%).
• the aspect ratio in the L / TC plane was determined for Examples A, B and C and was 9.3, 2.7 and 4.7, respectively.
• FIG. 1 illustrates the compromise between toughness (propagation energy UPE in the direction TL in J / mm2) and mechanical resistance (conventional elastic limit at 0.2% elongation R P o, 2 directions TL in MP a) of different sheets.
• the fatigue crack advance rates measured according to ASTM E 647-15 are provided in Table 4 for the T-L direction. All the sheets are in the T8 state (income conditions: 14 hours at 175 ° C) with the exception of sheet C which is in the T3 state.
• the tempering conditions are given in Table 5.
• the sheets were tested to determine their static mechanical properties.
• the elastic limit R P o, 2, the breaking strength R ffi and the elongation at break A, in the L direction and the TL direction, are presented in the
• sheets of 2XXX alloy have been prepared on an industrial scale.
• the plates were homogenized for 20 hours at 525 ° C. They were preheated 12 to 18 hours at 460 ° C before being hot rolled to obtain thin sheets with a thickness of 4 mm.
• the sheets were placed in solution for 30 minutes at 510 ° C. and then pulled with a controlled deformation of 2 to 4%. They were subjected to an artificial aging of 14 hours at 175 ° C.
• the sheets L to O all presented an essentially recrystallized structure (recrystallization rate at T / 2 greater than 90%).
• the grain sizes were measured at mid-thickness on L / TC cuts according to the ASTM El 12 standard. The results are presented in Table 7.
• the sheets were tested to determine their static mechanical properties.
• the elastic limit R P o, 2 , the breaking strength R m and the elongation at break A, in the direction L and the direction TL, are presented in Table 8.
• the toughness was evaluated by the so-called Kahn test method according to standard ASTM B871-01 (2013), the results are given in Table 9 and in Figure 2.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Aviation & Aerospace Engineering (AREA)
• Metal Rolling (AREA)
• Laminated Bodies (AREA)
• Heat Treatment Of Sheet Steel (AREA)

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• 2018
  • 2018-10-10 FR FR1871158A patent/FR3087206B1/fr active Active
• 2019
  • 2019-10-07 BR BR112021006605A patent/BR112021006605A2/pt unknown
  • 2019-10-07 CA CA3115014A patent/CA3115014A1/fr active Pending
  • 2019-10-07 EP EP19816820.5A patent/EP3864184A1/fr active Pending
  • 2019-10-07 WO PCT/FR2019/052373 patent/WO2020074818A1/fr unknown
  • 2019-10-07 CN CN201980065873.1A patent/CN112805397A/zh active Pending
  • 2019-10-07 US US17/284,373 patent/US20210388470A1/en active Pending

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