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AssigneePechiney Rhenalu
InventorsJean-Luc Hoffmann, Marcel Cortes
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The invention concerns a method for making aluminium alloy strips containing (by weight) at least 0.15 to 1.5% Fe and/or 0.35 to 1.9% Mn, with Fe+Mn<2.5% and optionally Si<0.8%, Mg<0.2%, Cu<0.2%, Cr<0.2%, Zn<0.2%, and other elements each <0.1% and <0.3 % in all, by continuous casting between two cylinders cooled and shrinked to a thickness ranging between 1 and 5 mm, the force applied to the cylinders during casting, expressed in tonnes per meter of strip width, being less than 300+2000/e, e being the cast strip thickness in mm. The invention also concerns strips in alloy of the same composition, twin-roll cast between 1 and 5 mm thick and having a product R0.2 (MPa)×A (%) greater than 2500, and preferably than 3000.
Method for producing aluminium alloy strips containing(by weight) at least one of elements Fe (from 0.15 to 1.5%) or Mn (from 0.35 to 1.9%) with:
Method for producing aluminium alloy strips containing (by weight) at least one of elements Fe (from 0.15 to 1.5%) or Mn (from 0.35 to 1.9%) with Fe+Mn<2.5%, and optionally Si<0.8%, Mg <0.2%, Cu <0.2%, Cr<0.2%, Zn<0.2%, other elements <0.1% each and 0.3% in all, by continuous twin-roll casting between cooled shrinked cylinders, characterised in that the heat exchange between the metal and the cylinder shells during casting is slowed down such that the temperature of the cylinder shells is higher than 80° C., preferably than 130° C.
Aluminium alloy strip containing (by weight) at least one of elements Fe (from 0.15 to 1.5%) or Mn (from 0.35 to 1.9%) with Fe+Mn<2.5% and optionally containing Si (<0.8%), Mg (<0.2%), Cu (<0.2%) or Zn (<0.2%), other elements <0.1% each and 0.3% in all, continuous cast to a thickness of between 1 and 5 mm, having at the as-cast state a product R0.2 (in MPa)×A (%) greater than 2500.
15 Strip in Al-Mn alloy according to any of claims 5 to 14 with Fe+Mn>1.4% having, after enamelling and/or PTFE anti-adhesive coating treatment, a yield strength of more than 80 MPa, preferably more than 100 MPa.
Dependencies are inferred from the claim text.
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Alloys based on aluminium
Parts, details or accessories of cooking-vessels: selection of specific materials, e.g. heavy bottoms with copper inlay or with insulating inlay
Into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars: formed by two casting wheels
Alloys
Term end not estimated
The invention concerns a method for making aluminium alloy strips with low magnesium and copper content, especially AlFeSi and AlMn alloys, by continuous thin gauge twin-roll casting (<5 mm). It also relates to strips of said alloys cast by thin gauge twin-roll casting, and optionally cold rolled, having high mechanical resistance, good formability and good anisotropy.
To obtain high mechanical resistance with aluminium alloys not requiring subsequent structural hardening, recourse is generally made to the addition of magnesium, as for the alloys of the 5000 series as per the Aluminium Association nomenclature. Aside from the fact that the casting of these alloys, in particular their continuous casting, is fairly demanding, there are applications for which the presence of magnesium in substantial quantities is unacceptable. This is the case for example with sheets intended for enamelled cooking utensils, in which magnesium has an adverse affect on the adherence of the enamel layer, or for strips intended for manufacturing heat exchanger blades brazed with a fluoride flux, since the magnesium diffuses on the surface and reacts with the flux. On this account, for these applications use is made of the AlFeSi alloys in the 1000 series, AlMn alloys in the 3000 series or AlSiFe alloys in the 4000 series whose mechanical resistance is distinctly lower. The article by M. DELEUZE and D. MARCHIVE on the new wrought alloys “Les nouveaux alliages de corroyage 4006 et 4007” Revue de l'Aluminium, June 1980, pp. 289-292, clearly demonstrates the demands of the cooking utensil market placed upon aluminium alloy strip manufacturers.
These alloy strips are usually produced by vertical semi-continuous casting of plates, hot rolling, cold rolling and soft annealing. After enamelling, involving annealing at a temperature in the region of 550° C., or after PFTE coating submitted to polymerization at around 450° C., the sheets of 4006 and 4007 alloys have a yield strength R0.2 of between 55 and 80 MPa.
On a continuous twin-roll 3CM casting machine made by Pechiney Aluminium Engineering, 5 alloys were cast whose chemical composition (by weight %) is given in table I: 1 TABLE I Alloy Mn Fe Si Mg 8006 0.44 1.29 0.15 0.028 3003 1.1 0.40 0.10 — 1050 — 0.20 0.14 0.002 8011 — 0.75 0.70 — 1200 — 0.55 0.20 —
In each case, measurements were taken of cast thickness, separating force per metre of strip width, compared with the limit value of 300-2000/e, and the mechanical characteristics of the as-cast strip tensile strength Rm (in MPa), yield strength at 0.2% R0.2 (in MPa), elongation A (%) and earing ration (%) according to standard NF-EN 1669 with a drawing ratio of 1.92. The results are grouped together in table II: 2 TABLE II e Force 300 + Rm R0.2 A R0.2 × Earing Alloy mm t/m 2000/e MPa MPa % A ratio 8006 3.1 867 945 166 118 25 2950 2.8 3003 3.0 900 967 158 114 23 2622 4.4 1050 3.5 720 871 106 81 39 3159 4.0 8011 3.9 1018 813 156 112 23 2576 9.0 1200 3.0 1100 967 121 93 32 2976 8.9 3003 3.5 1400 871 181 141 17 2297 8.0
It is found that, in the first 3 cases, both an elongation of more than 20% and a product R0.2×A of more than 2500 is obtained, together with an earing ratio of less than 7. On the other hand, for the 3 last cases in which the force is too high, the earing ratio is quite substantial which renders the strip unfit for stamping.