Classifications

• • 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
• • 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
• • 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
  • 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

Definitions

• the invention relates to an aluminum-based alloy, preferably of the system Al-Li-Mg, which contains lithium, magnesium, zinc, zirconium and manganese and is in the field of metallurgy of alloys used as a material for constructions in aerospace engineering, in shipbuilding and mechanical engineering of terrestrial means of transport, including welded constructions.
• the alloy according to the international patent application WO No. 92/03583 has the following chemical composition in percentage by mass: aluminum Base lithium 0.5 - 3.0 magnesium 0.5-10.0 zinc 0.1 - 5.0 silver 0.1 - 2.0
• the alloy may contain up to 1.0% zirconium.
• This alloy has a strength of 476 - 497 MPa, a yield strength of 368 - 455 MPa, a relative elongation of 7 - 9% and a density of 2.46 - 2.63 g / cm 3 .
• the alloy is recommended as a structural material for aerospace products.
• the disadvantages of this alloy are as follows:
• the alloy is alloyed with silver, which increases product costs - from semi-finished products to finished products.
• High zinc content alloys and added copper have reduced corrosion resistance, while in fusion welding they show an increased tendency to form defects and significant softening.
• a comparable alloy for the entire field of application is from the U.S. Patent No. 4,636,357 known.
• This alloy has the following chemical composition in percent by mass: aluminum Base lithium 2.0 - 3.0 magnesium 0.5 - 4.0 zinc 2.0 - 5.0 copper 0 - 2.0 zirconium 0 - 0.2 manganese 0 - 0.5 nickel 0 - 0.5 chrome 0 - 0.4
• This alloy has a sufficiently high strength level 440 - 550 MPa and a yield strength of 350 - 410 MPa.
• the disadvantages of this alloy are the low level of relative elongation of the alloy (1.0-7.0%) and the low fracture toughness, insufficient corrosion resistance and limited strength of welded joints compared to the strength of the base material.
• the object of the present invention is to achieve an increase in the ductility of the alloy in the heat-treated state while maintaining high strength and ensuring high corrosion resistance and good weldability, with sufficiently high fracture toughness and thermal stability values after heating at 85 ° C should be guaranteed in the course of 1000 h.
• a method for improving the fracture toughness of an aluminum-lithium alloy is out US 4840682 and US 5076859 known.
• WO 96/18752 A1 describes a method of heat treating an aluminum-lithium alloy.
• an alloy of the system AI-li-Mg having the following chemical composition in percent by mass: lithium 1.5 - 1.9 magnesium 4.1 - 6.0 zinc 0.1 - 1.5 zirconium 0.05 - 0.3 manganese 0.01-0.8 hydrogen 0.9x10 -5 -4.5x10 -5 and at least one element selected from the following group: beryllium 0.001-0.2 yttrium 0.01 - 0.5 scandium 0.01 - 0.3 aluminum rest
• the hydrogen content causes a reduction in the longitudinal shrinkage during solidification to form solid finely divided particles of lithium hydride and avoids the formation of porosity in the material.
• the magnesium content ensures the necessary level of strength properties and weldability. When the magnesium content falls below 4.1%, it will reduce the strength and grow the tendency of the alloy to hot cracking during both casting and welding. Increasing the magnesium content of the alloy above 6.0% reduces machinability in casting, hot and cold rolling, and plasticity characteristics of finished semi-finished products and articles thereof.
• the necessary level of mechanical and corrosion properties and sufficient fracture toughness and weldability, compliance with the lithium content is essential.
• the lithium content was lowered below 1.5%, the density of the alloy increased, the level of the strength properties and the modulus of elasticity decreased, and when the lithium content exceeded 1.9%, workability by cold working, weldability, plasticity characteristics and fracture toughness deteriorated.
• Zirconium in the amount of 0.05-0.3% is a modifier in the casting of ingots and, together with the manganese (in the amount of 0.01-0.8%), ensures structural solidification in the semi-finished products as a result of the formation a polygonal or fine-grained structure.
• the formation of a homogeneous fine-grained microstructure in semifinished products made of the alloy according to the invention causes an increase in deformability during cold rolling.
• the invention relates to a method for the heat treatment of aluminum-based alloys, preferably of the system Al-Li-Mg.
• the object of such a heat treatment process is to increase the ductility of the alloy while maintaining its high strength and at the same time to achieve high values of corrosion resistance and fracture toughness, but in particular the Preservation of these properties upon exposure of the material to increased temperature over a long period of time.
• this method does not ensure the stability of the properties of lithium-containing aluminum alloys after low temperature heating at 85 ° C over 1000 hours, which simulates solar heating during long-term operation of aircraft. After heating to 85 ° C for 1000 h, the relative elongation and fracture toughness of lithium-containing alloys treated by this method are reduced by 25-30%.
• this invention can also be carried out in such a way that cooling takes place at a cooling rate of 2 to 8 ° C. per hour for 10 to 30 hours.
• inventive alloys having the feature of claim 1 have particularly advantageous properties in the sense of the task, if they were treated by the aforementioned method.
• the first stage of artificial aging takes place at a temperature of 80-90 ° C over 3 - 12 h and a second stage at 110 - 185 ° C over 10 - 48 h.
• a second stage of artificial aging can be carried out at a temperature of 110 to 125 ° C and a duration of 5 to 12 hours, these method parameters are preferably applied when the third aging stage is carried out according to claim 3.
• billets of 70 mm diameter were cast.
• the metal was melted in the resistance furnace.
• After homogenization (500 ° C, 10 h) strips were pressed from the billets with a cross section of 15 x 65 mm.
• the ingots were heated to a temperature of 380-450 ° C before being pressed.
• Rolled blocks from the strips were heated to 360 - 420 ° C and hot rolled to 4 mm thick sheets, which then up to 2.2 mm Thickness have been cold rolled.
• the cold-rolled sheets were quenched from a temperature of 400-500 ° C in water or air, with a degree of deformation up to 2%, and subjected to the heat treatments listed in Tab.
• Alloys Nos. 3-10 are materials according to the invention Process for heat treatment of the investigated alloys Alloy no.
• Heat treatment no. Heat treatment method 3, 5, 9 3 80 ° C, 4 h + 185 ° C, 10 h + 110 ° C, 8 h 8.10 4 90 ° C, 3 h + 110 ° C, 48 h + 90 ° C, 14 h 4, 7 5 85 ° C, 5 h + 145 ° C, 25 h + 110 ° C, 10 h 6 6 85 ° C, 12 h + 120 ° C, 12 h + 90 ° C, 12 h Properties of the investigated alloys Alloy no Heat treatment no.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Crystallography & Structural Chemistry (AREA)
• Thermal Sciences (AREA)
• Physics & Mathematics (AREA)
• Heat Treatment Of Articles (AREA)
• Battery Electrode And Active Subsutance (AREA)
• Powder Metallurgy (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Metal Rolling (AREA)
• Heat Treatment Of Steel (AREA)
• Heat Treatments In General, Especially Conveying And Cooling (AREA)

Applications Claiming Priority (5)

Publications (2)

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ID=26653936

Family Applications (1)

Country Status (11)

Families Citing this family (17)

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• 1998
  • 1998-09-21 CN CN98809322A patent/CN1084799C/zh not_active Expired - Lifetime
  • 1998-09-21 ES ES98952615.7T patent/ES2445745T3/es not_active Expired - Lifetime
  • 1998-09-21 AU AU10250/99A patent/AU759402B2/en not_active Expired
  • 1998-09-21 BR BRPI9812377-7A patent/BR9812377B1/pt not_active IP Right Cessation
  • 1998-09-21 JP JP2000512995A patent/JP4185247B2/ja not_active Expired - Fee Related
  • 1998-09-21 EP EP98952615.7A patent/EP1017867B1/de not_active Expired - Lifetime
  • 1998-09-21 WO PCT/EP1998/006010 patent/WO1999015708A1/de active IP Right Grant
  • 1998-09-21 US US09/509,181 patent/US6395111B1/en not_active Expired - Lifetime
  • 1998-09-21 KR KR1020007003017A patent/KR100540234B1/ko not_active IP Right Cessation
  • 1998-09-21 CA CA002303595A patent/CA2303595C/en not_active Expired - Lifetime
  • 1998-09-21 UA UA2000042301A patent/UA66367C2/uk unknown
• 2001
  • 2001-11-26 US US09/994,273 patent/US6461566B2/en not_active Expired - Lifetime

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