Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
  • B22D11/0622—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars formed by two casting wheels
• • 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 present invention relates to a manufacturing process by casting continuous between cylinders of a thin sheet of suitable aluminum alloy for the production of components for beverage or use boxes food.
• said sheets In order to be suitable for these mechanical operations as well as for stresses resulting from the manipulations and pressures exerted on the inside of boxes with certain foods such as drinks carbonated, said sheets must have both a suitability for suitable deformation and a sufficient elastic limit.
• German document DE 3247698 (Alusuisse) teaches a method of manufacture of a strip intended for the manufacture of box covers aluminum alloy from a continuous casting machine characterized in that an alloy containing by weight 0.15 to 0.50% of Si is poured, 0.3 to 0.8% Fe, 0.05 to 0.25% Cu, 0.5 to 1% Mn, 2.5 to 3.5% Mg and up to 0.20% of Ti between two cooled casting rolls constituting a casting gap of 5 to 10 mm and that the resulting strip is cold rolled to a final thickness of 0.4 to 0.2 mm.
• the document JP 04276047 (Sky Aluminum) describes a process for obtaining hard sheets of aluminum alloy for the production of covers of boxes, method comprising a thin strip casting to a thickness less than 15 mm, with a cooling rate greater than 50 ° C / sec; the sheet obtained is submitted immediately or after rolling cold to a first intermediate annealing, to cold rolling with a reduction rate from 30 to 85%, at the second intermediate annealing and finally in the final cold rolling with a reduction rate higher than 30%, this the latter can be followed by a final annealing.
• the alloy has the following composition: Mg: 1.2 to 3%, Cu: 0.05 to 0.5%, Mn: 0.5 to 2%, Fe: 0.1 to 0.7%, Si: 0.1 to 0.5% , the balance being Al.
• a 6 mm thick sheet was obtained according to this process. having an elastic limit, at 45 ° relative to the direction of rolling, from 305 to 310 N / mm2.
• Document EP 99739 describes a process for obtaining a strip of Al alloy suitable for drawing and drawing, for example for obtaining boxes. It includes continuous strip casting thickness less than 2.54 cm, preferably between 6 and 12 mm, heating to 510-620 °, followed by cold rolling with reduction at least 25% thick, annealed, second cold rolled with a thickness reduction of at least 10%, a heating of recrystallization and final cold rolling.
• Strips 12.1 mm thick and of different compositions were obtained and treated according to the method described; the final products obtained have the following characteristics (tab. XIX) Elastic limit from 280 to 294 MPa Breaking load from 291 to 308 MPa Elongation 2.2 to 2.5%
• the breaking strength obtained is 272 MPa, the elastic limit of 245 MPa and the elongation of 4.1%.
• the object of the invention is, with at least equal properties, to reduce the rolling rate and eliminating the intermediate annealing steps when cold rolling, which simplifies the process and makes it more economic.
• the invention consists of a method of manufacturing a sheet of aluminum alloy intended for the housing which has for composition by weight: Mg between 1 and 4%, Mn between O and 1.6%, balance Al with its unavoidable impurities and optionally additions of Cu and / or Cr.
• said sheet is obtained by casting said alloy in the liquid state between two cylinders in the form of a strip having a thickness at most equal to 4 mm, followed by at least one heat treatment at a temperature between 400 and 580 ° C so that the sheet is at least partially recrystallized, from cold rolling up to a final thickness of less than 0.3 mm and optionally of a coating operation.
• the subject of the invention is a process first characterized by the casting a strip between two cylinders at a lower thickness or equal to 4 mm so that to reach the thickness of a cover of box to manufacture, the rolling rate is less than 95%; this avoids the recourse to intermediate annealing between the rolling passes, which is the case as soon as the thickness is greater than 4 mm, as has been seen upper.
• casting between cylinders is meant a continuous casting of strips in which the liquid metal is introduced, using a nozzle refractory, between two cooled cylinders, between which it solidifies.
• This invention is made possible by the use of the ranges of specific concentrations, cited above, of the various elements of the alloy constituting the sheet; it provides properties improved, in particular increased mechanical characteristics.
• pouring at a thickness of less than 4 mm is favorable with regard to the quality of the tape, in particular as regards the segregations which are much reduced if not absent hence a improved formability and obtaining productivity in the vicinity of its optimum.
• Another characteristic of the invention is the obtaining of a structure partially recrystallized (for example greater than about 50%) or completely, after heat treatment between 400 and 580 ° C of the strip after casting. This recrystallization of the metal is necessary to obtaining excellent formability of the alloy.
• This operation can be carried out discontinuously on the wound strip or in the process either on the strip leaving continuously from the casting machine, or on a strip previously wound after casting.
• the duration of the heat treatment and the temperature depend on the rate of temperature rise.
• the heating rate is generally between 20 and 200 ° C / h.
• the heating rate is at least 3000 ° C / h.
• the parade treatment also offers particular advantages for alloys containing less than about 0.75% of Mn. Indeed, it leads to a recrystallization with fine and isotropic grains of dimensions less than 40 micrometers while the batch annealing gives grains of dimensions between 200 and 50 micrometers; this has the effect of improving the formability of the sheet.
• the parade treatment is preferably obtained by heating in a induction oven or in a hot air circulating oven but, all other means of processing the parade of a strip can be envisaged.
• the strip After heat treatment, the strip is cold rolled to the final thickness and the sheet obtained can be covered with a plastic material intended to protect it from the environment. It can be, for example, a varnishing on both sides with a varnish which is then dried by heating at a temperature between 200 and 280 ° C.
• This magnesium is preferably combined with manganese in proportion by weight up to 1.6%.
• a content higher than the maximum value prevents proper recrystallization during annealing and causes the appearance of large grains harmful to mechanical properties.
• magnesium and manganese satisfying the condition: (3 Mn% + 2 Mg%) greater than or equal to 6% and less than or equal to 9%, so to obtain the best compromise between mechanical strength and formability.
• the magnesium content is less than 3.2% but, the best results are obtained for an Mg content of less than 2.8%; indeed, this reduces the risks of segregation during casting, associated with high Mg contents.
• Mn makes it possible to limit the content of Mg and therefore to decrease the risk of segregation; it is advantageously greater than 0.4% about.
• the addition of a small amount of copper less than or equal to 0.4% and preferably less than 0.2% and / or the addition of chromium up to about 0.2% makes it possible to improve the mechanical strength of the alloy.
• the content of these elements is limited because in too large a quantity they limit the ductility of the metal and therefore its formability.
• silicon and iron these are mainly impurities whose presence is a function of the quality of the aluminum used.
• the silicon is less than 0.3% or better than 0.2% and the iron at 0.5% or better at 0.3%.
• the silicon leads after casting or after heat treatment by maturation to the formation of intermetallic precipitates of Mg2Si which limit the formability of the alloy.
• iron it gives rise to the formation of eutectic precipitates during casting and therefore of segregations which are also harmful to ductility.
• alloys A, B and C Three types of alloys A, B and C have been used, their composition by weight: Alloy Mg% Mn% Fe% Yes% Cu% AT 3.20 0.40 0.20 0.05 0.20 B 2.50 0.75 0.20 0.05 0.20 VS 1.5 1.4 0.19 0.05 0.20
• the annealed strip is then subjected to 6 rolling passes without annealing intermediate to bring it in the form of a thick sheet final of 270 micrometers.
• Said sheet is then degreased, subjected to a chemical treatment conversion to be then varnished on both sides.
• the characteristics necessary to obtain covers suitable are a yield strength greater than 320 MPa, an index Ericksen greater than 4 and a delamination of the varnish less than 0.6 mm, it can be seen that the objectives are achieved by the process according to the invention, in particular in the case where a treatment is carried out type II or III thermal.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Organic Chemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Crystallography & Structural Chemistry (AREA)
• Thermal Sciences (AREA)
• Physics & Mathematics (AREA)
• Metal Rolling (AREA)
• Laminated Bodies (AREA)
• Table Devices Or Equipment (AREA)
• Details Of Rigid Or Semi-Rigid Containers (AREA)
• Shaping Metal By Deep-Drawing, Or The Like (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Heat Treatment Of Sheet Steel (AREA)

Applications Claiming Priority (5)

Publications (2)

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Family Applications (1)

Country Status (12)

Families Citing this family (14)

Family Cites Families (11)

• 1993
  • 1993-09-29 FR FR9311814A patent/FR2707669B1/fr not_active Expired - Lifetime
• 1994
  • 1994-07-07 IL IL110237A patent/IL110237A/en not_active IP Right Cessation
  • 1994-07-11 ES ES94922899T patent/ES2131696T3/es not_active Expired - Lifetime
  • 1994-07-11 CA CA002144757A patent/CA2144757C/fr not_active Expired - Fee Related
  • 1994-07-11 US US08/397,067 patent/US5616190A/en not_active Expired - Fee Related
  • 1994-07-11 JP JP50437295A patent/JP3689106B2/ja not_active Expired - Fee Related
  • 1994-07-11 EP EP94922899A patent/EP0660882B1/fr not_active Expired - Lifetime
  • 1994-07-11 CN CN94190606A patent/CN1043580C/zh not_active Expired - Lifetime
  • 1994-07-11 WO PCT/FR1994/000861 patent/WO1995002708A1/fr active IP Right Grant
  • 1994-07-11 DE DE69418581T patent/DE69418581T2/de not_active Expired - Fee Related
  • 1994-07-11 BR BR9405520-3A patent/BR9405520A/pt not_active IP Right Cessation
  • 1994-08-03 SA SA94150111A patent/SA94150111B1/ar unknown

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