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
• • 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

Definitions

• the invention relates to thin strips, with a typical thickness between 30 and 150 ⁇ m, made of an aluminium-iron alloy, suitable for pressing, intended especially for packaging, and more particularly for the preparation of thin food trays and plates for the distribution of foodstuffs and the fast food industry.
• the Al—Fe alloys of the 8000 series are widely used for the production of thin sheets or strips intended for packaging. They may be produced, either in the traditional manner of casting a plate, hot rolling, then cold rolling, with intermediate annealing of the plate one or more times and most often a final annealing, either by means of continuous casting between two rolls, for example, and cold rolling, and the plate may be annealed once or more times.
• U.S. Pat. No. 5,380,379 from Alcoa Aluminio de Nordeste relates to the production, by means of continuous casting between rolls, of very thin sheets made of alloys containing 1.35 to 1.6% of iron, 0.3 to 0.6% of manganese, 0.1 to 0.4% of copper and less than 0.2% of silicon.
• the silicon content is limited by the onset of intermetallic phases of the AlFeSi or AlMnSi type, while the presence of copper is required to give the product sufficient mechanical strength.
• Patent application WO 98/52707 by the applicant describes a process for producing aluminium alloy strips containing (by weight) at least one of the elements Fe (between 0.15 to 1.5%) or Mn (between 0.35 to 1.9%) with Fe+Mn ⁇ 2.5%, and which may contain Si ( ⁇ 0.8%), Mg ( ⁇ 0.2%), Cu ( ⁇ 0.2%), obtained by continuous casting between cooled and reinforced rolls with a thickness between 1 and 5 mm, following by a cold rolling.
• the strips obtained in this manner have at the same time a yield strength that is higher than that of the strips produced in the conventional manner and good formability.
• the aim of the invention is to improve the tradeoff between mechanical strength, formability and the isotropy of the mechanical properties in comparison with this reference alloy.
• the subject of the invention is aluminium alloy strips with a thickness between 30 and 150 ⁇ m, made of an alloy of composition (% by weight):
• Si ⁇ 0.4; Fe: 1.5-1.9; Mn: 0.04-0.15; other elements: ⁇ 0.05 of each and 0.15 in total, with the remainder consisting of aluminium.
• the subject of the invention is also a process for producing alloy strips with this composition by continuous casting between rolls of a strip with a thickness between 2 and 10 mm, with the possible homogenization of this strip at a temperature setting between 420 and 550° C., cold rolling of this strip until the final thickness is achieved, and possibly an intermediate annealing for 1 to 4 hours at a temperature setting between 300 and 350° C., and a final annealing at a temperature setting between 200 and 430° C. for a period of at least 30 hours.
• Another object of the invention is to use these strips for plates and trays for prepared foodstuffs.
• the alloy used for sheets and strips according to the invention is characterized by an iron content between 1.5 and 1.9%, which is higher than that which is customarily used for the alloy 8021B intended for the production of plates and trays.
• the advantage of a higher iron content resides in the improvement in mechanical strength; this effect is even more marked when the strips are produced by continuous casting between rolls.
• the iron content must remain below 1.9% to avoid approaching the eutectic AlFe content, which would cause coarse-grained primary AlFe phases to appear.
• the other characteristic is a manganese content between 0.04 and 0.15%.
• This addition has a favourable effect on the mechanical strength, while maintaining a high level of elongation, the tradeoff between these properties, which are usually antagonistic, clearly being improved with strips produced by means of continuous casting. If the manganese content is greater than 0.15%, the manganese clearly plays more of an anti-recrystallizing role, which may adversely affect the efficiency of the final annealing required to obtain good isotropy of the mechanical characteristics.
• the production of sheets and strips according to the invention is preferably done by the continuous casting of a strip with a thickness of 2 to 10 mm between two cooled and reinforced rolls (“twin-roll casting”).
• the cast strip may be homogenized, especially in the case where elongation is favoured over mechanical strength. This homogenization must be carried out at a temperature that is not too high, between 420 and 550° C., in order to prevent too great a degradation of the mechanical strength. If the requirements regarding elongation are less binding, homogenization is not essential.
• the strip is then cold rolled with the necessary number of passes until the final thickness between 30 and 150 ⁇ m is reached.
• the said cold rolling may be done with or without intermediate annealing. If intermediate annealing is necessary, it must be relatively short, of the order of 1 to 4 hours, and carried out at a temperature setting that is not too high, typically between 300 and 350° C., to avoid enlargement of the grain. But it is possible, when very high elongation values are not desired, to avoid both homogenization and intermediate annealing, which makes the production process particularly simple.
• the rolled strip is then annealed at a temperature between 200 and 400° C. for a period of at least 30 hours, in such a manner that a recrystallized structure is obtained.
• This annealing may be carried out at one or more temperature settings, such as a first setting between 200 and 300° C., and a second setting between 300 and 400° C.
• the strip may subsequently be cut into sheets if necessary.

Landscapes

• 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 Sheet Steel (AREA)
• Laminated Bodies (AREA)
• Cookers (AREA)
• Continuous Casting (AREA)
• Table Devices Or Equipment (AREA)
• Soft Magnetic Materials (AREA)
• Clamps And Clips (AREA)
• Containers Having Bodies Formed In One Piece (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=27636231

Family Applications (1)

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Cited By (4)

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Citations (2)

Family Cites Families (2)

• 2002
  • 2002-02-15 FR FR0201959A patent/FR2836154B1/fr not_active Expired - Fee Related
• 2003
  • 2003-02-12 CA CA002475700A patent/CA2475700A1/fr not_active Abandoned
  • 2003-02-12 RU RU2004127592/02A patent/RU2004127592A/ru not_active Application Discontinuation
  • 2003-02-12 AT AT03739530T patent/ATE392489T1/de not_active IP Right Cessation
  • 2003-02-12 EP EP03739530A patent/EP1483422B1/fr not_active Expired - Lifetime
  • 2003-02-12 AU AU2003226882A patent/AU2003226882A1/en not_active Abandoned
  • 2003-02-12 BR BR0307633-4A patent/BR0307633A/pt not_active Application Discontinuation
  • 2003-02-12 WO PCT/FR2003/000452 patent/WO2003069003A2/fr active IP Right Grant
  • 2003-02-12 DE DE60320387T patent/DE60320387T2/de not_active Expired - Lifetime
  • 2003-02-12 US US10/502,809 patent/US20050207934A1/en not_active Abandoned
• 2004
  • 2004-08-13 NO NO20043388A patent/NO20043388L/no not_active Application Discontinuation

Patent Citations (2)

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