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
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium
  • C22C21/02—Alloys based on aluminium with silicon 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
• • 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

• This invention concerns thin strips or foils less than 200 ⁇ m thick and preferably less than 50 ⁇ m thick, made of an aluminium alloy with iron and with silicon, with substantially low manganese content, and a process of manufacturing such strips or foils. These strips may be obtained by semi-continuous casting of conventional plates or by continuous casting, for example by twin-belt casting or twin-roll casting.
• Alloys with a very low manganese content are frequently used for thin foil, for example such as the 8111 alloy with the following composition (% by weight) registered with the Aluminum Association:
• Manganese is normally added to increase the mechanical strength, for example as in the 8006 alloy for which the composition (% by weight) registered with the Aluminum Association is as follows:
• the mechanical properties can also be improved by adding a small quantity of manganese in alloys in the 8000 series containing iron.
• Patent application WO 02/64848 (Alcan International) describes the fabrication of thin strips made of AlFeSi alloy containing from 1.2% to 1.7% Fe and 0.35% to 0.8% of Si, by continuous casting. A high mechanical strength is obtained by adding 0.07% to 0.20% of manganese to the alloy. This addition of manganese is recognised as being necessary to obtain a small grain size after final annealing.
• manganese appears to be an element capable of improving the mechanical properties of 8000 alloys.
• manganese in solid solution or in the form of fine precipitates can block or delay recrystallisation during final annealing. Therefore, the precipitation of phases containing manganese needs to be controlled precisely during each step in the procedure, which is often difficult. Any drift in the transformation procedure has non-negligible consequences on the effectiveness of the final annealing. Therefore, it would be very useful to develop an alloy that does not contain any manganese, but that does have high mechanical properties.
• U.S. Pat. No. 5,503,689 (Reynolds Metals) describes a process for manufacturing a thin strip made of an alloy containing 0.30% to 1.1% Si and 0.40% to 1.0% Fe, less than 0.25% Cu and less than 0.1% Mn, by continuous casting and cold rolling without intermediate annealing.
• the preferred contents of iron and silicon are between 0.6% and 0.75%.
• U.S. Pat. No. 5,725,695 (Reynolds Metals) describes a procedure for the same composition, with intermediate annealing between 400° C. and 440° C. (750° F.-825° F.) and a final recrystallisation annealing at 288° C. (550° F.).
• the ratio of the Si and Fe contents is greater than or equal to 1.
• the maximum ultimate tensile strength obtained is 90 MPa (13.13 ksi)
• the maximum yield stress is 39.1 MPa (5.68 ksi)
• the elongation is 11.37% for thicknesses of 46 ⁇ m (0.00185°).
• the intermediate annealing control usually requires a high temperature heat treatment (at above 400° C.) so as to obtain recrystallisation.
• Patent application WO 99/23269 (Nippon Light Metal and Alcan International) describes a process applicable to AlFeSi alloys containing 0.2% to 1% of Si and 0.3% to 1.2% of Fe, with a Si/Fe ratio of between 0.4 and 1.2, in which intermediate annealing is done in two steps, the first between 350° C. and 450° C., and the second between 200° C. and 330° C. The purpose of this process is to reduce surface defects in the foil. Mechanical properties are not mentioned.
• the purpose of the invention is to obtain thin strips or foils made of an AlFeSi alloy with no added manganese, with a high mechanical strength while maintaining good formability, with the most economic industrial manufacturing procedure possible.
• the subject matter of the invention is a thin foil between 6 ⁇ m and 200 ⁇ m thick, and preferably between 6 ⁇ m and 50 ⁇ m thick, of an alloy with the following composition (% by weight):
• Si 1.0-1.5; Fe: 1.0-1.5; Cu ⁇ 0.2; Mn ⁇ 0.1; other elements ⁇ 0.05 each and ⁇ 0.15 total, remainder Al, preferably with the condition Si/Fe ⁇ 0.95, with an ultimate tensile strength in the annealed temper R m >10 MPa for thicknesses >9 ⁇ m and >100 MPa for thicknesses between 6 ⁇ m and 9 ⁇ m.
• the yield stress R 0.2 of the thin foil is preferably >70 MPa.
• the ultimate elongation is greater than the following values, as a function of the thickness of the foil: Thickness ( ⁇ m) A (%) greater than and preferably than 6-9 3 4 9-15 5 7 15-25 10 15 25-50 18 25 50-200 20 25
• the silicon content of the alloy is preferably between 1.1% and 1.3% and its iron content is between 1.0% and 1.2%.
• Another subject matter of the invention is a manufacturing process for thin strips thinner than 200 ⁇ m made of an Al—Fe—Si alloy with composition (% by weight):
• the thin strips or foils according to the invention are made from 8000 AlSiFe alloys with almost no manganese, typically less than 0.1%. Iron and silicon contents are significantly higher than 8011 and 8111 alloys that are the most frequently used manganese-free AlSiFe alloys for thin foil.
• One preferred composition range is an alloy containing 1.1% to 1.3% of silicon and 1.0% to 1.2% of iron.
• Alloys according to the invention preferably have a composition such that the Si/Fe ratio of silicon and iron contents is ⁇ 0.95.
• Their mechanical strength in the annealed temper (O temper) is exceptional for alloys with this composition, with an ultimate tensile strength R m >110 MPa or even 115 MPa for thicknesses >9 ⁇ m, and >100 MPa for thicknesses from 6 ⁇ m to 9 ⁇ m, and a conventional yield stress at 0.2%, R 0.2 >70 MPa.
• This high mechanical strength is not obtained at the expense of formability, since elongations are at least as high as for 8011 and 8111 alloys, and bursting pressures are higher.
• Hot rolled strips, or as-cast strips obtained by continuous twin-roll casting may be homogenised at low temperature (between 450° C. and 500° C.) to reduce the central segregation that may reduce formability to the final thickness.
• This low temperature heat treatment is sufficient to resorb any central segregations in these manganese-free alloys.
• the strips are then cold rolled, either down to the final thickness or to an intermediate thickness between 0.5 mm and 5 mm, at which an intermediate annealing is performed.
• this intermediate annealing can be done at a relatively low temperature between 250° C. and 350° C., and preferably between 280° C. and 340° C., for longer than 2 hours.
• this temperature range is described in the literature, particularly in patent application WO 02/064848 mentioned above, it is below the normal range that remains above 400° C.
• Final annealing is done at a temperature between 200° C. and 370° C. for between 1 h and 72 h. Annealing durations depend on the degreasing quality of the foil. A fine grain structure is obtained after annealing, with an average grain size measured by image analysis with a scanning electron microscope equal to less than 3 ⁇ m.
• the combination of low temperature homogenisation or no homogenisation at all with an intermediate annealing at low temperature or no intermediate annealing at all, is economically advantageous but also helps to obtain a fine grain size.
• the grain size is about 30% lower than is possible with heat treatments at a higher temperature, consequently increasing the mechanical properties R 0.2 and R m which for small thicknesses are related to the number of grain joints. This gain is not achieved at the detriment of elongation, since the increase in the number of grains in the thickness also limits the risk of local damage in one or two single grains in the thickness of the foil.
• Thin foils according to the invention are particularly suitable for applications requiring good mechanical strength and high formability, for example such as fabrication of multi-layer composites, particularly for lids for packaging of fresh products, overcaps or aluminium wrapping.
• the strips were cold rolled to a thickness of 2 mm and an intermediate annealing was then carried out on them for 5 hours at 320° C.
• the strips were then cold rolled in several passes to the final thickness of 38 ⁇ m.
• a final annealing was then carried out on them for 40 hours at 270° C.
• the ultimate strength of the alloy A strip is much higher than 110 MPa, and the yield stress is higher than 70 MPa.
• the bursting pressure and the elongation are also higher, such that this alloy is both stronger and more formable.
• a 6.1 mm thick strip made of alloy A described in example 1 was made by continuous twin-roll casting. The strip was then cold rolled to a thickness of 2 mm. A normal intermediate annealing for an alloy of this type was then carried out on part of the strip, for 5 hours at 500° C. An intermediate annealing was carried out on the other part of the strip, for 5 hours at 320° C. according to the invention. The two parts of the strip were then cold rolled in several passes to the final thickness of 10.5 ⁇ m. A final annealing was then carried out on them for 40 hours at 270° C.
• the average grain size measured by image analysis with an SEM is 3.6 ⁇ m for annealing at 470° C., and 2.3 ⁇ m for annealing at 320° C. Therefore the increase in mechanical properties for low temperature annealing is related to the reduction in grain size obtained after final annealing.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Materials Engineering (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Crystallography & Structural Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Continuous Casting (AREA)
• Laminated Bodies (AREA)
• Heat Treatment Of Sheet Steel (AREA)
• Closures For Containers (AREA)
• Wrappers (AREA)
• Catalysts (AREA)
• Metal Rolling (AREA)
• Containers Having Bodies Formed In One Piece (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=33560962

Family Applications (1)

Country Status (21)

Cited By (7)

Families Citing this family (3)

Citations (2)

Family Cites Families (8)

• 2003
  • 2003-07-21 FR FR0308864A patent/FR2857981A1/fr active Pending
• 2004
  • 2004-06-23 AR ARP040102197A patent/AR044882A1/es not_active Application Discontinuation
  • 2004-07-19 DK DK04767726T patent/DK1644545T3/da active
  • 2004-07-19 UA UAA200601770A patent/UA80778C2/uk unknown
  • 2004-07-19 JP JP2006520859A patent/JP4989221B2/ja not_active Expired - Lifetime
  • 2004-07-19 WO PCT/FR2004/001902 patent/WO2005010222A2/fr active IP Right Grant
  • 2004-07-19 EA EA200600276A patent/EA009227B1/ru not_active IP Right Cessation
  • 2004-07-19 ES ES04767726T patent/ES2281831T3/es not_active Expired - Lifetime
  • 2004-07-19 ZA ZA200600425A patent/ZA200600425B/en unknown
  • 2004-07-19 DE DE602004005045T patent/DE602004005045T2/de not_active Expired - Lifetime
  • 2004-07-19 BR BRPI0412775-7A patent/BRPI0412775A/pt not_active IP Right Cessation
  • 2004-07-19 AT AT04767726T patent/ATE355392T1/de not_active IP Right Cessation
  • 2004-07-19 US US10/565,219 patent/US20060213590A1/en not_active Abandoned
  • 2004-07-19 PL PL04767726T patent/PL1644545T3/pl unknown
  • 2004-07-19 AU AU2004259877A patent/AU2004259877A1/en not_active Abandoned
  • 2004-07-19 CA CA002532585A patent/CA2532585A1/fr not_active Abandoned
  • 2004-07-19 CN CNB2004800210038A patent/CN100445405C/zh not_active Expired - Fee Related
  • 2004-07-19 EP EP04767726A patent/EP1644545B1/fr not_active Expired - Lifetime
  • 2004-07-19 PT PT04767726T patent/PT1644545E/pt unknown
  • 2004-08-11 SA SA04250245A patent/SA04250245B1/ar unknown
• 2006
  • 2006-01-31 NO NO20060508A patent/NO338970B1/no unknown

Patent Citations (2)

Also Published As

Similar Documents

Legal Events