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
  • C22C21/14—Alloys based on aluminium with copper as the next major constituent with silicon
• • 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 relates to laminated products aluminum-copper-lithium alloys, more particularly, such products, their manufacturing processes and use, intended in particular for aeronautical and aerospace construction.
• Aluminum alloy rolled products are being developed to produce fuselage elements for the aerospace industry and the aerospace industry in particular.
• U.S. Patent 5,032,359 discloses a broad family of aluminum-copper-lithium alloys in which the addition of magnesium and silver, particularly between 0.3 and 0.5 percent by weight, increases the mechanical strength. .
• US Pat. No. 7,438,772 describes alloys comprising, in percentage by weight, Cu: 3-5, Mg: 0.5-2, Li: 0.01-0.9 and discourages the use of higher lithium contents due to degradation of the compromise between toughness and mechanical strength. US Pat. No.
• 7,229,509 describes an alloy comprising (% 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, 0.4 max Zr or other grain refining agents such as Cr, Ti, Hf, Se, V.
• US patent application 2009/142222 A1 discloses alloys comprising (in% by weight), 3.4 to 4.2% Cu, 0.9 to 1.4% Li, 0.3 to 0.7% of Ag, 0.1 to 0.6% Mg, 0.2 to 0.8% Zn, 0.1 to 0.6% Mn and 0.01 to 0.6% of at least one element. for the control of the granular structure. This application also describes a process for manufacturing spun products.
• US patent application 201 1/0247730 discloses alloys comprising (in% by weight), 2.75 to 5.0% Cu, 0.1 to 1.1% Li, 0.3 to 2.0% Ag, 0.2. at 0.8% Mg, 0.50 to 1.5% Zn, up to 1.0% Mn, with a Cu / Mg ratio of between 6.1 and 17, this alloy being insensitive to wrought.
• the patent application CN101967588 describes alloys of composition (in% by weight) Cu 2.8 - 4.0; Li 0.8 - 1.9; Mn 0.2-0.6; Zn 0.20 - 0.80, Zr 0.04-0.20, Mg 0.20-0.80, Ag 0.1-0.7, Si ⁇ 0.10, Fe ⁇ 0.10, Ti ⁇ 0.12, it teaches the combined addition of zirconium and manganese.
• the characteristics required for aluminum sheets intended for fuselage applications are described, for example, in patent EP 1 891 247. It is desirable in particular that the sheet has a high yield strength (to withstand buckling) as well as a high plane stress toughness, characterized in particular by a high value of high tensile stress intensity factor (Ka PP ) and a long curve R.
• Ka PP high tensile stress intensity factor
• Patent EP 1 966 402 describes an alloy comprising 2.1 to 2.8% by weight of Cu,
• the alloy being substantially free of zirconium, particularly suitable for obtaining recrystallized thin sheets.
• the fuselage sheets can be loaded in several directions and isotropic thin sheets having high properties and balanced in mechanical strength in the directions L and TL and tenacity for the directions L-T and T-L are much sought after.
• thin sheets obtained with certain alloys having high properties at certain thicknesses for example 4 mm, may in certain cases have lower or anisotropic properties at another thickness, for example 2.5 mm. It is often not advantageous industrially to use different alloys for different thicknesses and an alloy to achieve high and isotropic properties regardless of the thickness would be particularly advantageous.
• the object of the invention is a sheet having a thickness of 0.5 to 9 mm of granular structure essentially recrystallized from an aluminum-based alloy comprising 2.8 to 3.2% by weight of Cu,
• said sheet being obtained by a process comprising casting, homogenization, hot rolling and optionally cold rolling, dissolving, quenching and tempering.
• Another subject of the invention is the process for manufacturing a sheet according to the invention with a thickness of 0.5 to 9 mm in aluminum-based alloy in which, successively a) a liquid metal bath comprising
• said plate is homogenized at a temperature between 480 ° C and 535 ° C;
• an income is made comprising heating at a temperature between 130 and 170 ° C and preferably between 150 and 160 ° C for 5 to 100 hours and preferably
• Yet another object of the invention is the use of a sheet according to the invention in an aircraft fuselage panel.
• Figure 1 - R curves obtained in the direction L-T on sheets of thickness 4 to 5 mm for specimens of width 760 mm.
• Figure 2 - R curves obtained in the direction L-T on sheets of thickness 1, 5 to 2.5 mm for specimens of width 760 mm.
• the static mechanical characteristics in tension are determined by a tensile test according to standard NF EN ISO 6892-1, the sampling and the direction of the test being defined by the standard EN 485-1.
• the term "substantially uncrystallized granular structure” refers to a granular structure such that the degree of recrystallization at 1 ⁇ 2-thickness is less than 30% and preferably less than 10%, and a substantially recrystallized granular structure is called a structure. granular such that the recrystallization rate at 1 ⁇ 2 thickness is greater than 70% and preferably greater than 90%.
• the recrystallization rate is defined as the surface fraction on a metallographic section occupied by recrystallized grains.
• the grain sizes are measured according to ASTM El 12.
• a curve giving the effective stress intensity factor as a function of the effective crack extension, known as the R curve, is determined according to ASTM E 561.
• the critical stress intensity factor Kc in others the intensity factor which makes the crack unstable, is calculated from the curve R.
• the stress intensity factor Kco is also calculated by assigning the initial crack length at the beginning of the monotonic load, to the critical load . These two values are calculated for a specimen of the required form.
• Ka PP represents the Kco factor corresponding to the specimen that was used to perform the R curve test.
• Keff represents the Kc factor corresponding to the specimen that was used to perform the R curve test.
• effective stress intensity factor for effective crack extension Aaeff of 60 mm is W / 3 for M (T) type specimens, where W is the specimen width as defined in ASTM E561.
• EN 12258 Unless otherwise specified, the definitions of EN 12258 apply.
• the copper content of the products according to the invention is between 2.8 and 3.2% by weight. In an advantageous embodiment of the invention, the copper content is between 2.9 and 3.1% by weight.
• the lithium content of the products according to the invention is between 0.5 and 0.8% by weight and preferably between 0.55% and 0.75% by weight.
• the lithium content is at least 0.6% by weight. In one embodiment of the invention, the lithium content is between 0.64% and 0.73% by weight.
• the addition of lithium may contribute to the increase in strength and toughness, a too high or too low content does not provide a high value of toughness and / or a sufficient yield strength.
• the magnesium content of the products according to the invention is between 0.2 and 0.7% by weight, preferably between 0.3 and 0.5% by weight and preferably between 0.35 and 0.45% by weight. in weight.
• the manganese content is between 0.2 and 0.6% by weight and preferably between 0.25 and 0.35% by weight. In one embodiment of the invention, the manganese content is at most 0.45% by weight.
• the addition of manganese in the claimed amount allows control of the granular structure while avoiding the adverse effect on the toughness that would generate too high a content.
• the silver content is between 0.1 and 0.3% by weight. In an advantageous embodiment of the invention, the silver content is between 0.15 and 0.28% by weight.
• the titanium content is between 0.01 and 0.15% by weight.
• the titanium content is at least 0.02% by weight and preferably at least 0.03% by weight.
• the titanium content is at most 0.1% by weight and preferably at most 0.05% by weight. The addition of titanium helps to control the granular structure, especially during casting.
• the iron and silicon contents are each at most 0.1% by weight. In an advantageous embodiment of the invention, the iron and silicon contents are at most 0.08% and preferably at most 0.04% by weight. A controlled and limited iron and silicon content contributes to the improvement of the compromise between mechanical resistance and damage tolerance.
• the zinc content is less than 0.2% by weight and preferably less than 0.1% by weight. The zinc content is advantageously less than 0.04% by weight.
• the unavoidable impurities are maintained at a content of less than or equal to 0.05% by weight each and 0.15% by weight in total.
• the zirconium content is less than or equal to 0.05% by weight preferably less than or equal to 0.04% by weight and preferably less than or equal to 0.03% by weight.
• the method of manufacturing the sheets according to the invention comprises steps of production, casting, rolling, dissolution, quenching, controlled pulling and tempering.
• a bath of liquid metal is produced so as to obtain an aluminum alloy of composition according to the invention.
• the bath of liquid metal is then cast into a form of rolling plate.
• the rolling plate is then homogenized at a temperature between 480 ° C and 535 ° and preferably between 490 ° C and 530 ° C and preferably between 500 ° C and 520 ° C.
• the homogenization time is preferably between 5 and 60 hours.
• a homogenization temperature that is too low or the absence of homogenization does not make it possible to achieve improved and isotropic properties compared to those of the known products, in particular in terms of mechanical strength in the L and TL directions and toughness for the LT and TL directions over the entire thickness range.
• the rolling plate After homogenization, the rolling plate is generally cooled to room temperature before being preheated to be hot deformed. Preheating aims to achieve a temperature preferably between 400 and 500 ° C for deformation by hot rolling.
• the hot rolling and optionally cold rolling is performed so as to obtain a sheet thickness of 0.5 to 9 mm.
• a temperature greater than 400 ° C. is maintained up to a thickness of 20 mm and preferably a temperature greater than 450 ° C. up to a thickness of 20 mm.
• Intermediate heat treatments during rolling and / or after rolling can be carried out in some cases. However, preferably, the process does not include intermediate heat treatment during rolling and / or after rolling.
• the sheet thus obtained is then put into solution by heat treatment between 450 and 535 ° C., preferably between 490 ° C. and 530 ° C. and preferably between 500 ° C and 520 ° C, preferably for 5 min to 2 hours, and then quenched.
• the dissolution time is at most 1 hour in order to minimize the surface oxidation.
• the sheet then undergoes cold deformation by controlled traction with a permanent deformation of 0.5 to 5% and preferably of 1 to 3%.
• Known steps such as rolling, flattening, deflashing, straightening and shaping may optionally be carried out after dissolution and quenching and before or after the controlled pull, however the total cold deformation after dissolution and quenching. must remain less than 15% and preferably less than 10%.
• High cold deformation after dissolution and quenching cause the appearance of many shear bands passing through several grains, these shear bands being undesirable.
• the quenched sheet may be subjected to a step of wrinkling or planing, before or after the controlled pull.
• flashing / planing means a cold deformation step without permanent deformation or with a permanent deformation less than or equal to 1%, to improve the flatness.
• An income is achieved comprising heating at a temperature between 130 and 170 ° C and preferably between 150 and 160 ° C for 5 to 100 hours and preferably 10 to 40 hours.
• the final metallurgical state is a T8 state.
• a short heat treatment is performed after controlled pulling and before tempering so as to improve the formability of the sheets.
• the sheets can thus be shaped by a process such as drawing-forming before being returned.
• the granular structure of the sheets according to the invention is essentially recrystallized.
• the combination of the composition according to the invention and transformation parameters makes it possible to control the anisotropy index of the recrystallized grains.
• the sheets according to the invention are such that the grain anisotropy index measured at mid-thickness according to ASTM standard El 12 by the intercepts method in the L / TC plane is less than 20, preferably less than 15 and, preferably, less than 10.
• the grain anisotropy index measured at mid-thickness according to ASTM standard El 12 by the intercepts method in the L / TC plane is less than or equal to 8, preferably less than or equal to 6 and preferably less than or equal to 4.
• the sheets according to the invention have advantageous properties irrespective of the thickness of the products.
• the resistance to corrosion, in particular to intergranular corrosion, to corroding corrosion as well as stress corrosion, of the sheets according to the invention is high.
• the sheet of the invention can be used without plating.
• sheets according to the invention in an aircraft fuselage panel is advantageous.
• the sheets according to the invention are also advantageous in aerospace applications such as the manufacture of rockets.
• the plates were homogenized for 12 hours at 505 ° C.
• the plates were hot-rolled to obtain sheets having a thickness of between 4.2 and 6.3 mm. Some sheets have then cold-rolled to a thickness of between 1.5 and 2.5 mm.
• the details of the sheets obtained and the income conditions are given in Table 2.
• the granular structure of the samples was characterized from microscopic observation of cross sections after anodic oxidation under polarized light.
• the granular structure of the plates was essentially non-recrystallized for all the sheets except for the plates D # 2 E # 2 F # 1, F # 2, G # 1 and G # 2 for which the granular structure was essentially recrystallized.
• the grain size was determined in the mid-thickness L / TC plane according to the ASTM El 12 standard by the intercepts method from the microscopic observation of the cross-sections after anodic oxidation under polarized light.
• the anisotropy index is the ratio of grain size measured in the L direction divided by the grain size measured in the TC direction. The results are shown in Table 3.
• the samples were mechanically tested to determine their static mechanical properties as well as their toughness.
• the mechanical characteristics were measured in full thickness.
• Table 5 summarizes the results of the tenacity tests on CCT test specimens of width 760 mm for these samples. Table 5 results of the R curves for CCT test pieces of width 760 mm.
• Figures 1 and 2 illustrate the remarkable toughness of Examples F and G according to the invention in particular in the direction L-T.
• Examples F and G demonstrate that it is possible to obtain thin sheets according to the invention which have improved and isotropic properties compared to those obtained from the other examples A to E, and in particular with respect to Example C and over a wide range of typical thickness of said thin sheets.

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)
• Metal Rolling (AREA)
• Heat Treatment Of Steel (AREA)
• Powder Metallurgy (AREA)
• Conductive Materials (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=52423759

Family Applications (1)

Country Status (8)

Families Citing this family (9)

Family Cites Families (17)

• 2014
  • 2014-10-03 FR FR1402237A patent/FR3026747B1/fr active Active
• 2015
  • 2015-10-01 CN CN201580053855.3A patent/CN106795595A/zh active Pending
  • 2015-10-01 US US15/515,891 patent/US11174535B2/en active Active
  • 2015-10-01 EP EP15784082.8A patent/EP3201372B1/de active Active
  • 2015-10-01 BR BR112017006071-0A patent/BR112017006071B1/pt active IP Right Grant
  • 2015-10-01 JP JP2017518117A patent/JP6692803B2/ja active Active
  • 2015-10-01 CA CA2961712A patent/CA2961712C/fr active Active
  • 2015-10-01 WO PCT/FR2015/052634 patent/WO2016051099A1/fr not_active Ceased

Also Published As

Similar Documents

Legal Events