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

Definitions

• the present invention relates to a process for manufacturing sheets of hypoeutectic aluminum-iron alloys, intended more particularly for the production of light dishes, flexible pipes, plugs and for all applications requiring said sheet of mechanical characteristics which favor stamping. , folding and stiffness.
• hypoeutectic aluminum-iron alloys are understood here to mean those which contain less than 1.7% of iron.
• Such alloys are known in particular from French patent FR no. 1,438,096 which protects a product suitable for the production of metal sheets with a thickness of less than 76 ⁇ m, characterized in that it contains from 0.6 to 1.2 % iron, the rest being aluminum.
• Such a sheet is obtained by conventional semi-continuous casting followed by cold rolling and has interesting mechanical characteristics, namely a tensile breaking strength of the order of 80 MPa and an elongation of 7%.
• the Applicant has directed its research towards alloys with a composition which is quite far from eutectic and contains at most 1.3% iron.
• Those skilled in the art know that, under these conditions, solidification begins with the appearance of so-called primary aluminum crystals in the form of dentrites and ends with an eutectic deposit composed of intermetallics of At n Fe which separates the grains from each other. This leads to a heterogeneous structure quite different from the homogeneous structure obtained in the case of a eutectic composition.
• hypoeutectic Al ,, Fe has a significantly better elongation characteristic than that of conventional alloys 1100 and 5005. This property means that, as the patent teaches: »the alloy adapts better to thin sheet manufacturing operations and return the superior product obtained for packaging applications, for which better mechanical strength would be ineffective if it were accompanied by a significant loss of elongation.
• the metal hardens or better hardens, that is to say that it gradually loses all capacity for plastic elongation while acquiring greater strength. It can then be heated to a temperature in the region of 400 ° C. and thus carry out a so-called recrystallization annealing, an operation during which the mechanical characteristics change considerably and are oriented towards a reduction in the breaking load and an increase in elongation. Admittedly, this significantly improves the elongation, but more often than not, the resistance has become insufficient.
• the metal bath is treated with a refiner, it is poured semi-continuously in an ingot mold or continuously between cylinders, it is cold rolled and annealed between 380 ° C and 430 ° C, this process being characterized in that the refiner is added in such a quantity that it generates a pouring structure in which the grains have a maximum dimension less than 100 ⁇ m and the spacing between dendrite arms is between 8 and 30 ⁇ m and in that the rolling takes place according to a thickness reduction rate of between 98 and 99.8%.
• the method according to the invention consists in implementing the conventional steps in metallurgy of refining the alloy in the liquid state, of casting, of rolling, of final annealing. It can be noted, however, that the process applies indifferently to a product cast in semi- continuous by means of ingot molds or type 3C cylinder casting machines, provided that the refining and work hardening parameters are adapted to the type of casting so as to lead to the same final structure.
• the process is first characterized by the addition of a refiner in quantity such that it generates a casting structure in which the grains have a maximum dimension of less than 100 ⁇ m.
• a refiner in quantity such that it generates a casting structure in which the grains have a maximum dimension of less than 100 ⁇ m.
• grains with dimensions close to 200 ⁇ m are obtained by casting.
• experience has shown that with such a size, the alloy behaves too heterogeneously during rolling and that shear bands are created favorable to the development of a total recrystallization, which goes to the 'against obtaining a semi-recrystallized structure.
• This refining can be obtained by means of any agent generally used in aluminum metallurgy and, in particular, products based on boron and titanium such as, for example, AT5B.
• alloy compositions moving as far as possible from the eutectic zone but nevertheless retaining sufficient iron to benefit from the particular properties of this element and, in particular, from its action as an agent for blocking recrystallization.
• a content of between 1.1 and 1.3% of iron is preferred.
• the alloy is avoided from being poured into a cylinder machine of the HUNTER type because the solidification speed is too high and leads to dendrites which are too fine less than 5 ⁇ m.
• the 3C machine proves to be particularly advantageous in the process of the invention because it gives rise to the formation of dendrites which are still sufficiently large so that zones with and without eutectic can be clearly distinguished on the structure.
• the method is also characterized in that the cold rolling, applied directly to the casting structure, is carried out according to a thickness reduction rate of between 98 and 99.8%.
• the process also includes an annealing between 380 and 430 ° C. after rolling at a temperature rise rate and of a duration such that the desired semi-recrystallized structure is developed and which is then composed of recrystallized grains of diameter less than 30 ⁇ m and generally between 5 and 15 ⁇ m, isolated in a restored matrix with sub-grains of 1 to 2 ⁇ m.
• the semi-recrystallized structure thus obtained seems essentially due to a dispersion in the distribution of the distances between the intermetallic particles allowing both recrystallization when this distance is large and blocking of recrystallization when this distance is small.
• the small volume occupied by the recrystallized grains seems essential because it brings to the alloy a notable improvement in ductility while the structure of the sub-grains still allows a high elastic limit to be retained.
• alloy sheet an advantageous compromise between its characteristics, which is particularly favorable for subsequent processing operations such as stamping for example.
• the invention also relates to the alloy sheet obtained by the process having a thickness of between 50 and 250 ⁇ m, a composition such as: characterized by a structure in which 10 to 30% of the volume is in the recrystallized state in the form of grains greater than 5 ⁇ m and less than 30 ⁇ m, and the rest is in the restored state so as to obtain an advantageous compromise between the tensile strength and elongation, and for the first mechanical characteristic being between 120 and 140 MPa, and for the second, above 17%.
• a composition such as: characterized by a structure in which 10 to 30% of the volume is in the recrystallized state in the form of grains greater than 5 ⁇ m and less than 30 ⁇ m, and the rest is in the restored state so as to obtain an advantageous compromise between the tensile strength and elongation, and for the first mechanical characteristic being between 120 and 140 MPa, and for the second, above 17%.
• the invention can be illustrated by means of the following examples which give the results of mechanical characteristics obtained with sheets of 100 ⁇ m thickness, produced according to the claimed process.
• An alloy of composition was refined using an AT5B mother alloy at a rate of 3 kg per tonne of alloy, then continuously cast using a bottomless ingot mold in the form of a plate whose section has the dimensions 38 x 7 cm with a speed of 8 cm / minute.
• the structure of the cast product was composed of primary aluminum grains having a maximum dimension less than 150 ⁇ m separated from each other by eutectic zones of AI n Fe.
• the plate was cold rolled at a thickness reduction rate of 99.8% so as to give a sheet 100 ⁇ m thick which was annealed at 420 ° C for 30 hours.
• the final structure of this sheet had 30% of its volume in the recrystallized state and its mechanical characteristics were as follows: understood of values particularly in the preparation of dishes obtained by stamping.
• An alloy of composition was refined using an ATSB master alloy at a rate of 2 kg per tonne of alloy, then continuously cast using a type 3C cooled cylinder machine in the form of a thick sheet 0.8 cm with a speed of 100 cm / minute.
• the structure of the cast product included primary aluminum grains of dimensions between 30 and 80 ⁇ m separated from each other by eutectic zones of Al n Fe.
• the sheet was cold rolled at a thickness reduction rate of 99% so as to form a sheet of thickness 80 ⁇ m which was annealed at 400 ° C for 30 hours.
• the sheet had a final structure recrystallized at 20% and its mechanical characteristics were as follows: characteristics which made it possible to use this sheet for the preparation of deep-drawn dishes, with a practically zero rate of reject.
• the present invention finds its application in the aluminum industry whenever it is desired to obtain sheets with a thickness of between 50 and 150 ⁇ m having a couple of optimum values with regard to the tensile breaking load. and elongation.

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• Chemical & Material Sciences (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Metal Rolling (AREA)
• Coating With Molten Metal (AREA)
• Soft Magnetic Materials (AREA)
• Analysing Materials By The Use Of Radiation (AREA)
• Continuous Casting (AREA)
• Powder Metallurgy (AREA)
• Coloring Foods And Improving Nutritive Qualities (AREA)
• Manufacture Of Alloys Or Alloy Compounds (AREA)
• Forging (AREA)
• Laminated Bodies (AREA)
• Manufacturing Cores, Coils, And Magnets (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

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• 1981
  • 1981-04-13 FR FR8107844A patent/FR2503738A1/fr active Granted
• 1982
  • 1982-04-06 NO NO821164A patent/NO156572C/no unknown
  • 1982-04-07 DK DK159682A patent/DK159682A/da not_active IP Right Cessation
  • 1982-04-08 EP EP82420049A patent/EP0064468B1/fr not_active Expired
  • 1982-04-08 AT AT82420049T patent/ATE10116T1/de not_active IP Right Cessation
  • 1982-04-08 DE DE8282420049T patent/DE3261110D1/de not_active Expired
  • 1982-04-08 ES ES511308A patent/ES511308A0/es active Granted
  • 1982-04-09 TR TR21267A patent/TR21267A/xx unknown
  • 1982-04-09 GR GR67860A patent/GR69198B/el unknown

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