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
• • 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

Definitions

• the invention generally relates to wrought products of aluminum-copper-lithium alloys, and more particularly to such products in the form of profiles intended to produce stiffeners in aeronautical construction. State of the art
• Aluminum alloys containing lithium are very interesting in this respect, since lithium can reduce the density of aluminum by 3% and increase the modulus of elasticity by 6% for each weight percent of lithium added.
• their performance must reach that of commonly used alloys, in particular in terms of a compromise between the static mechanical strength properties (elastic limit, breaking strength) and the properties of damage tolerance ( toughness, resistance to the propagation of fatigue cracks), these properties being in general antinomic.
• These alloys must also have sufficient corrosion resistance, be able to be shaped according to the usual methods and have low residual stresses so that they can be machined integrally.
• Several Al-Cu-Li alloys are known for which an addition of silver is made.
• No. 5,032,359 discloses a broad family of aluminum-copper-lithium alloys in which the addition of magnesium and silver, in particular between 0.3 and 0.5 percent by weight, makes it possible to increase the mechanical strength. These alloys are often known under the trade name "Weldalite TM".
• US Patent 5,198,045 discloses a family of Weldalite TM alloys comprising (in% by weight) (2,4-3,5) Cu, (1,35-1,8) Li, (0,25-0,65) Mg, (0.25-0.65) Ag, (0.08-0.25) Zr.
• the wrought products made with these alloys combine a density of less than 2.64 g / cm 3 and a compromise between strength and toughness of interest.
• US Pat. No. 7,229,509 describes a family of Weldalite TM alloys comprising (in% by weight) (2.5-5.5) Cu, (0.1-2.5) Li, (0.2-1.0). Mg, (0.2-0.8) Ag, (0.2-0.8) Mn, (up to 0.4) Zr or other elements such as Cr, Ti, Hf, Se and V. Examples presented have a compromise between mechanical strength and improved toughness but their density is greater than 2.7 g / cm 3 .
• Patent application WO2007 / 080267 discloses a Zirconium-free Weldalite TM alloy for fuselage plates comprising (in% by weight) (2.1 -2.8) Cu, (1, 1-1, 7) Li, (0.2-0.6) Mg, (0.1-0.8) Ag, (0.2-0.6) Mn.
• AA2196 alloy comprising (in% by weight) (2.5-3.3) Cu, (1, 4-2.1) Li, (0.25-0.8) Mg, is also known. , 25-0.6) Ag, (0.04-0.18) Zr and at most 0.35 Mn.
• a first subject of the invention is an aluminum-based alloy product comprising, in% by weight,
• Li 1.6-2.3; preferably 1.7-2.2;
• Mg 0.3-0.9; preferentially 0.5-0.7;
• Mn 0.2 - 0.6; preferably 0.3-0.6;
• V 0.01-0.3, preferably 0.02-0.1;
• a second object the invention is an aluminum alloy product comprising, in% by weight,
• Li 1.6-2.3; preferably 1.7-2.2;
• Mg 0.3-0.9; preferentially 0.5-0.7;
• Mn 0.2 - 0.6; preferably 0.3-0.6;
• V 0.01-0.3, preferably 0.02-0.1;
• Another subject of the invention is a process for manufacturing a raw aluminum alloy casting product according to the invention comprising the steps of:
• the casting is carried out without the addition of grain refining or by adding an affine comprising (i) Ti and (ii) B or C and such that the B content from the refining agent is less than 20 ppm preferably less than 10 ppm and, more preferably still, less than 5 ppm and that of C less than 3 ppm, preferably less than 2 ppm and, more preferably still, less than 1 ppm and / or
• the casting is carried out for a raw casting form of thickness E (mm) or diameter D (mm) greater than 150 mm at a casting speed v (in mm min) greater than:
• Yet another object of the invention is a method of manufacturing a wrought product comprising pouring a raw form according to the process of the invention and steps of rolling or extrusion and / or forging, dissolving, quenching, stress relieving and optionally tempering.
• Yet another object of the invention is a structural element incorporating at least one product obtained by the process for manufacturing a wrought product according to the invention or made from an alloy product according to the invention.
• FIG. 1 represents the size of the casting grains ( ⁇ ) of the AlCuLiMgMnZr alloys of Example 1 placed in the Zr diagram (% by weight) as a function of Li (% by weight).
• FIG. 2 represents the size of the casting grains ( ⁇ ) of the AlCuLiMgMnZr alloys of Example 1 placed in the Zr diagram (% by weight) as a function of Li (% by weight).
• Figure 3 shows the shape of the profiles W of Example 2 ("shape" means the cross section of said profile).
• FIG. 4 represents the shape of the Z profiles of example 2 ("shape" is understood to mean the cross section of said profile).
• FIG. 5 represents the size of the casting grains ( ⁇ ) of the AlCuLiMgMnZr alloys of Example 3 placed in the Zr diagram (% by weight) as a function of Li (% by weight).
• FIG. 6 represents the size of the casting grains ( ⁇ ) of the AlCuLiMgMnZr alloys of Example 3 placed in the Zr diagram (% by weight) as a function of Li (% by weight).
• alloys are in accordance with the regulations of The Aluminum Association, known to those skilled in the art.
• the density depends on the composition and is determined by calculation rather than by a method of measuring weight.
• 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 the metallurgical states are given in the European standard EN 5 15 (2009).
• the static mechanical characteristics in other words the tensile strength R m , the conventional yield stress at 0.2% elongation R p o, 2 ("yield strength") and elongation at break A, are determined by a tensile test according to EN 10002-1 (2001), the sampling and the direction of the test being defined by EN 485-1 (2016).
• the stress intensity factor (KQ) is determined according to ASTM E 399 (2012). Thus, the proportion of test pieces defined in paragraph 7.2.1 of this standard is always verified, as is the general procedure defined in paragraph 8.
• ASTM E 399 (2012) gives criteria 9.1 .3 and 9.1 .4 determine if KQ is a valid Kic value. Thus, a Kic value is always a KQ value, the reciprocal being not true.
• the criteria of ASTM E399 (2012) 9.1 .3 and 9.1.4 are not always verified, however for a given specimen geometry, the KQ values presented are still comparable. between them, the specimen geometry making it possible to obtain a valid value of Kic not being always accessible taking into account the constraints related to the dimensions of the sheets or profiles.
• the thickness of the profiles is defined according to 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 can be considered as the thickness of the elementary rectangle.
• a "structural element” or “structural element” of a mechanical construction is called 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 calculation of structure is usually prescribed or realized.
• These are typically elements whose failure is likely to endanger the safety of said construction, its users, its users or others.
• these structural elements include the elements that make up the fuselage (such as fuselage skin (fuselage skin in English), stiffeners or stringers, bulkheads, fuselage (circumferential frames), wings (such as wing skin), stiffeners (stiffeners), ribs (ribs) and spars) and empennage including horizontal stabilizers and vertical stabilizers horizontal or vertical stabilizers, as well as floor beams, seat tracks and doors.
• fuselage such as fuselage skin (fuselage skin in English
• stiffeners or stringers such as fuselage skin
• bulkheads fuselage (circumferential frames)
• wings such as wing skin
• stiffeners stiffeners (stiffeners), ribs (ribs) and spars
• empennage including horizontal stabilizers and vertical stabilizers horizontal or vertical stabilizers, as well as floor beams, seat tracks and doors.
• the present inventors have found that, surprisingly, for certain AlCuLiMgMnZr alloys of particularly low density containing less than 0.1% by weight of silver and a joint addition of copper, lithium, magnesium and manganese, the specific choice of a The particular content of zirconium, a function of the lithium content, makes it possible to very significantly improve the robustness of the manufacturing process while maintaining a satisfactory compromise between the mechanical strength and the damage tolerance for the product.
• robustness of the manufacturing process is meant here generating little scrap related in particular to problems of hot slots and allowing the use of a large amount of recycled alloy.
• the aluminum alloy product according to the invention comprises, as a percentage by weight,
• Li 1.6-2.3; preferably 1.7-2.2;
• Mg 0.3-0.9; preferentially 0.5-0.7;
• Mn 0.2 - 0.6; preferably 0.3-0.6;
• V 0.01 - 0.3; preferably 0.02-0.1;
• the copper content of the alloy according to the invention for which both the compromise of properties and the improvement of the feasibility of the process are obtained is 2.4 to 3.2% by weight.
• the copper content is 2.5 to 3.0% by weight and preferably 2.6 to 2.9% by weight.
• the copper content is 2.4 to 2.6% by weight.
• the lithium content of the alloy according to the invention is such that it makes it possible to obtain a product having a particularly advantageous density, especially a density of less than 2.63 g / cm 3 , more particularly less than 2.62 g. / cm 3 and, more particularly, less than or equal to 2.61 g / cm 3 .
• the lithium content of the alloy is thus greater than 1.6% by weight, preferably greater than 1.7% by weight and, more preferably still, greater than 1.9% by weight.
• Such a lithium content induces a very high sensitivity to oxidation, hydrogenation and hot cracking, giving rise to difficulties in casting the alloy and, consequently, requires very specific manufacturing processes.
• the application WO2015 / 086921 describes in particular the fact that, since lithium is particularly oxidizable, the casting of aluminum-copper-lithium alloys generates more fatigue crack initiation sites than for 2XXX lithium-free alloys. In order to remedy this problem, it has been proposed to carry out the casting under specific conditions, in particular conditions such that the hydrogen and oxygen contents are kept particularly low and that the casting is of semi-vertical type using a particular distributor. . However, for the particularly high lithium contents referred to herein, it is further generally found that problems with hot cracking or cracking at the core of the raw form during casting.
• the problem of hot cracking can be remedied by sharpening the alloy during casting. It is known that the risk of hot cracking is even higher than the casting grain is coarser. A reduction in grain size and a change in grain shape can be achieved by adding large amounts of grain refining agent during casting.
• Typical grain refining agents are A13% Ti0.15% C, All% Ti0.15% C, A13% Til% B and A15% Til% B in the form of yarn generally added online. The addition of these agents induces the dispersion of fine particles of boride or carbide in the liquid metal which will serve as nucleation sites of the grains during solidification.
• grain refining agents comprising titanium as well as that of alloy remakes containing titanium also rapidly induces, as and when the alloy production cycles, an increase in the content of the alloy. total titanium alloy, which degrades the damage tolerance properties of the wrought product and thus limits the possible contribution of recycled metal in the load.
• an AlCuLiMgMnZr alloy according to the invention having particular Li and Zr contents, made it possible to improve the robustness of the manufacturing process and to limit or even to suppress the intake of refining agent grain.
• the lithium content of the alloy according to the invention is thus greater than 1, 6% by weight, preferably greater than 1.7% by weight and, more preferably still, greater than 1, 9% by weight.
• the Li content of the alloy is from 1.7 to 2.3% by weight or still 2.0 to 2.2% by weight.
• the high lithium content in particular exacerbates the sensitivity to oxidation of the liquid metal bath, promotes the problems of core cracking during casting which requires reducing the casting speed.
• the zirconium content is from 0.12 to 0.18% by weight; preferably from 0.13 to 0.16% by weight; and more preferably from 0.14 to 0.15% by weight.
• the precisely selected alloy composition according to the invention allows the formation of cubic crystal phases Al 3 Zr and Ab (Zr, Li) which are structurally similar to the metastable phase AbLi which is known to precipitate by demixing the solid solution during an income after dissolution and quenching but which is not expected to form from the liquid, the known stable form being the tetragonal variety.
• the formation of such phases through the composition of the specifically selected alloy could be at the origin of grain nucleation sites during the solidification of the raw form of casting thus allowing the formation of an extremely fine granular structure in the presence a conventional amount of grain refining agent or to limit, possibly eliminate, the supply of grain refining agent during casting.
• the present inventors have thus demonstrated a particular compromise between the zirconium and lithium contents such that it makes it possible to obtain both a compromise of satisfactory properties for the wrought product and to significantly improve the robustness of the manufacturing process.
• said alloy product AlCuLiMgMnZr, in particular the casting step of this process.
• the zirconium content of the alloy according to the invention is advantageously such that Zr> -0.06 * Li + 0.242, preferentially such that Zr> -0.06 * Li + 0.2575.
• the Li and Zr contents of the alloy according to the invention are such that Zr * Li> 0.235, preferably Zr * Li> 0.242, more preferably Zr * Li> 0.275.
• the magnesium content is 0.3 to 0.9% by weight and, preferably, 0.5 to 0.7% by weight. Magnesium, in the particular alloy composition of the present invention, helps to promote the achievement of a fine tint.
• the manganese content is from 0.2 to 0.6% by weight, preferably from 0.3 to 0.6% by weight and, more preferably, from 0.4 to 0.5% by weight.
• manganese makes it possible to reach a compromise of satisfactory properties for the wrought product.
• the silver content is less than 0.15% by weight, preferably less than 0.1% by weight and more preferably less than 0.05% by weight.
• the present inventors have found that the advantageous compromise between known mechanical strength and damage tolerance for alloys typically containing about 0.3% by weight of silver can be obtained for alloys containing essentially no silver with selection. of composition performed.
• the zinc content is less than 1.0% by weight, preferably less than 0.9% by weight. According to a first particular embodiment, the zinc content is between 0.1 and 0.5% by weight and preferably between 0.2 and 0.4% by weight. According to a second particular embodiment, the zinc content is less than 0.05% by weight.
• the alloy also contains at least one element that can contribute to controlling the grain size selected from Ti, Cr, Se, Hf and V, the amount of the element, if selected, being from 0.01 to 0 , 15% by weight, preferably 0.01 to 0.05% for Ti, from 0.01 to 0.15% by weight, preferably 0.02 to 0.1% by weight for Se, from 0.01 to 0 , 3% by weight and preferably from 0.02 to 0.1% by weight for Cr and V and from 0.01 to 0.5% by weight for Hf.
• titanium is chosen in the above-mentioned contents and even more advantageously in a content ranging from 0.01 to 0.03% by weight.
• the unavoidable impurities include iron and silicon, these impurities have a total content of less than 0.20% by weight and preferably less than 0.08% by weight and 0.06% by weight respectively for iron and aluminum. silicon; the other elements are impurities which preferably have a content of less than 0.05% by weight each and 0.15% by weight in total.
• the method of manufacturing the raw casting products according to the invention comprises steps of preparation, casting and solidification of the raw form. These steps are followed, for the production of the wrought products according to the invention, rolling or extrusion steps and / or forging, dissolution, quenching, stress relief and optionally returned.
• a liquid metal bath is produced, a raw form is cast from said liquid metal bath, and the raw form is solidified into a billet, a rolling plate, or the like. a forging draft.
• the casting step is carried out without the addition of grain refining or by adding an affine comprising (i) Ti and (ii) boron, B, or carbon, C, and such that:
• the content of B originating from the refining agent is less than 45 ppm, preferably less than 20 ppm, preferably less than 10 ppm and, more preferably still, less than 5 ppm,
• the C content is less than 6 ppm, preferably less than 3 ppm, preferably less than 2 ppm and, more preferably still, less than 1 ppm.
• a liquid metal bath is produced, a raw form is cast from said liquid metal bath and the raw form is solidified into a billet, a rolling plate or a forging draft.
• the casting is carried out, for a casting form of thickness or diameter D greater than 150 mm at a casting speed v (in mm / min) greater than:
• the grain size of the AlCuLiMgMnZr alloy according to the invention in the raw casting state, obtained by one of the processes according to the invention is less than 1 ⁇ , preferably less than or equal to 105 ⁇ . and, more preferably still less than 100 ⁇ for raw shapes of casting thickness or diameter greater than 150 mm, preferably greater than 250 mm and preferably still greater than 300 mm.
• the grain size of the AlCuLiMgMnZr alloy according to the invention in the raw state of casting, obtained by one of the methods according to the invention is less than or equal to 95 ⁇ , preferably less than 90 ⁇ for rough casting shapes with a diameter greater than 150. mm, preferably greater than 250 mm and preferably still greater than 300 mm.
• the pouring size was measured from samples taken at mid-radius (R / 2) billets, using the intercepts method, in accordance with ASTM El 12.
• the invention makes it possible to produce wrought products, that is to say, spun, rolled and / or forged products.
• the process for manufacturing the wrought products according to the invention comprises the rolling, extrusion and / or forging, solution-setting, quenching, stress-relieving and optionally return steps in one or more stages.
• the wrought products according to the invention are spun products.
• the process for manufacturing the spun product according to the invention comprises the steps:
• an object of the invention is a structural element incorporating at least one product according to the invention or a product manufactured from a method according to the invention.
• the use of a structural element incorporating at least one product according to the invention or manufactured from such a product is advantageous, in particular for aeronautical construction.
• the products according to the invention are particularly advantageous for the production of structural elements such as fuselage or wing stiffeners, floor beams and seat rails.
• Table 1 Composition in% by weight and density of AlCuLiMgMnZr alloys
• alloy billets AA2196 (alloy 2 and 5), the composition of which is given in Table 3 below, were homogenized for 8 hours at 500 ° C. and then 24h at 527 ° C. (alloy 2) or 8 hours at 520 ° C. ° C (alloy 5). Alloy billets 76 of Example 1 were homogenized 10 h at 534 ° C.
• the billets were then heated to 450 ° C. +/- 40 ° C. and then hot-spun to obtain profiles W according to FIG. 3 for alloy 2 and Z according to FIG. 4 for alloys 5 and 76.
• the profiles thus obtained were dissolved at 524 ° C., quenched and triturated with a permanent elongation of between 2 and 5%.
• the income was made for 48 hours at 152 ° C.
• Table 3 Composition in% by weight and density of alloy AA2196 5 0.03 0.04 2.90 0.31 0.40 0.01 0.03 0.1 1.67 0.38 2.64
• Samples taken at the end of the profile were tested to determine their static mechanical properties as well as their toughness (Kq).
• the location of the samples is shown in dashed lines in FIGS. 3 and 4.
• the reverts used for the measurement of the static properties were of diameter 10 mm and taken in such a way that the direction of the axis of the specimen corresponds to the direction of the sample. spinning (L direction).
• the composition of the liquid metal is that of solidified alloys, the subsequent solidification being carried out without the conventional addition of refining so as to highlight the contribution intrinsic of the composition of the alloy to the law of germination.
• the grain sizes obtained are different from those obtained in vertical casting in the presence of refining, but the possibility of self-inoculation of the alloy in a certain range of composition can be demonstrated by this test which makes it possible to specify the position of the boundary of the domain of interest in the Zr vs Li plane.
• the cooling rate is 3.5K.sup.- 1 .
• the pin which has the shape of a cone section height 65mm and whose circular bases have respective radii of 25mm and 65mm, is demolded and cut along its axis.
• the grain measurement is made 38 mm from the small face.
• the upper part of the pin thus cut was polished then underwent anodic oxidation before being observed under polarized light.
• the grain size was measured on this upper part thus prepared by an intercept method according to the ASTM El 12 standard.
• Table 5 Composition in% by weight and density of AlCuLiMgMnZr alloy used

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Continuous Casting (AREA)
• Extrusion Of Metal (AREA)
• Conductive Materials (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=59325429

Family Applications (1)

Country Status (7)

Families Citing this family (2)

Family Cites Families (18)

• 2017
  • 2017-04-10 FR FR1753135A patent/FR3065012B1/fr active Active
• 2018
  • 2018-04-09 EP EP18724942.0A patent/EP3610048B1/de active Active
  • 2018-04-09 BR BR112019021001A patent/BR112019021001A2/pt not_active Application Discontinuation
  • 2018-04-09 US US16/603,703 patent/US11667997B2/en active Active
  • 2018-04-09 CA CA3058096A patent/CA3058096A1/fr active Pending
  • 2018-04-09 CN CN201880024418.2A patent/CN110546288A/zh active Pending
  • 2018-04-09 WO PCT/FR2018/050887 patent/WO2018189472A1/fr unknown
• 2023
  • 2023-03-23 US US18/188,685 patent/US20230227954A1/en active Pending

Also Published As

Similar Documents

Legal Events