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
  • C22C21/02—Alloys based on aluminium with silicon as the next major constituent
  • C22C21/04—Modified aluminium-silicon alloys
• • 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
  • C22F1/043—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 silicon as the next major constituent

Definitions

• the invention relates to the field of sheets of medium and high strength aluminum alloys used in mechanical, aeronautical and space construction and in armaments.
• alloys 2000 and 7000 have a much better temperature resistance than that of most alloys 2000 and 7000, and at least equivalent to that of alloys in these series specially studied for their temperature resistance, such as alloys 2019 and 2618.
• Al-Si alloys are used very widely for the manufacture of molded parts. However, in this form, they have far lower mechanical strength, fatigue and toughness properties than the wrought and transformed alloys 2000 and 7000 used in structural parts. In rare cases, they can be used in laminated form, in particular for covering plated sheets intended for the manufacture of brazed heat exchangers. Alloys 4343, 4104, 4045 and 4047 are thus used, for example, the properties sought in this case being essentially a low melting temperature and good wettability.
• Al-Si alloys can also be spun in the form of bars or profiles which, due to their good resistance to wear and temperature, are used in mechanical parts such as connecting rods, brake master cylinders, drive shafts , bearings and various components of motors and compressors.
• One of the alloys used for this purpose is 4032.
• French patent FR 2291284 describes the manufacture of sheets of AlSi alloy containing 4 to 15% of Si by continuous casting between two cooled cylinders. This casting method is intended to increase the elongation at break, and therefore the formability. They are not high-strength sheets usable in structural applications, since the sheets are simply annealed and the elastic limits exemplified do not exceed not 220 MPa.
• Mn ⁇ 0.5% and / or Cr ⁇ 0.5%
• the silicon content is preferably between 6.5 and 8%, corresponding to that of the AS7G alloy.
• Another object of the invention is the use of medium or thick sheets of this alloy for the undersides of aircraft wings, of thin sheets for the coating of aircraft fuselages, of sheets for the manufacture of cryogenic tanks. rockets, floors and skips of industrial vehicles and hulls or supersructures of boats.
• the sheets according to the invention have silicon contents generally corresponding to the fields of alloys AS7G and AS9G according to French standard NF A 57-702 or the designations A 357 and A 359 of the Aluminum Association.
• Magnesium should not exceed 1% to avoid the formation of insoluble intermetallic compound Mg2Si. Copper must be limited to 0.8% to avoid the formation of insoluble phases Mg2Si and Q (AlMgSiCu). This content also makes it possible to limit the sensitivity to intercrystalline corrosion.
• Iron is also limited to 0.3%, and preferably 0.08%, as it is in 7000 alloys for heavy plate, when good toughness and / or good elongation.
• the presence of titanium is linked to the refining of the titanium plates, identical to that used for current medium and high strength alloys. As is usually the case with quality molding alloys, it is necessary to modify the alloy to avoid the formation of primary silicon and to obtain a finely dispersed fibered eutectic structure. For this operation, strontium is preferable to sodium which could cause hot fragility during processing.
• the sheets according to the invention can be obtained by vertical casting of plates, hot rolling up to 6 mm, optionally cold rolling in the case of thin sheets, dissolving between 545 and 555 ° C, quenching with cold water, maturation at room temperature and / or tempering between 6 and 24 h at a temperature between 150 and 195 ° C.
• Hot rolling can be preceded by homogenization between 530 and 550 ° C for a duration of less than 20 h, short enough to avoid a globalization of the fibrous eutectic and a marked coalescence of the manganese and / or chromium, when the alloy contains it.
• the alloy is weldable by conventional TIG or MIG processes, continuous or pulsed, depending on whether it is a thin or thick sheet, and its density is always lower than that of traditional 2000 and 7000 alloys.
• Example 1 homogenized sheet Plates of 380 x 120 mm section of alloy with the following composition (by weight) were produced by vertical casting: Si: 6.77% Mg: 0.59% Cu: 0.24%
• the alloy was homogenized at 550 ° C for 8 hours, after a temperature rise of 4 hours, reheated for 2 hours at 500 ° C, then hot rolled up to 20 mm thick on a reversible rolling mill. Cut sheets were placed in solution for 2 hours at 550 ° C, soaked in water and subjected to an income of 8 hours at 175 ° C, ie a state T651 according to the designations of the Aluminum Association.
• the alloy has a density of 2,678 and a modulus of elasticity E of 74,100 MPa, or a specific module of 27,670 MPa, was measured on the sheet by the hysteresis loop method in tension. 2.770, 72,500 MPa and 26,175 MPa respectively for a sheet of the same thickness in 2024 alloy in the T351 state, an increase of 5.7% in the specific module. This increase is more than 9% higher compared to alloy 2219 for welded construction.

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• 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)
• Laminated Bodies (AREA)
• Continuous Casting (AREA)
• Soft Magnetic Materials (AREA)
• Coating With Molten Metal (AREA)
• Pressure Welding/Diffusion-Bonding (AREA)
• Physical Vapour Deposition (AREA)

Applications Claiming Priority (3)

Publications (2)

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• 1994
  • 1994-06-13 FR FR9407405A patent/FR2721041B1/fr not_active Expired - Fee Related
• 1995
  • 1995-05-29 JP JP8501711A patent/JPH09501988A/ja active Pending
  • 1995-05-29 DE DE69504802T patent/DE69504802T2/de not_active Revoked
  • 1995-05-29 CA CA002168946A patent/CA2168946A1/fr not_active Abandoned
  • 1995-05-29 WO PCT/FR1995/000693 patent/WO1995034691A1/fr not_active Application Discontinuation
  • 1995-05-29 EP EP95920993A patent/EP0717784B1/de not_active Revoked
  • 1995-05-29 AT AT95920993T patent/ATE171222T1/de not_active IP Right Cessation
  • 1995-05-29 US US08/537,864 patent/US5837070A/en not_active Expired - Fee Related

Non-Patent Citations (1)

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