MANUFACTURING METHOD OF MAKING ALUMINUM ALLOY SEMI-FINISHED PRODUCT WITH IMPROVED MICROPOROSITY

• US 20120237395A1
• Filed: 02/16/2012
• Published: 09/20/2012
• Est. Priority Date: 02/18/2011
• Status: Active Grant

• Current Assignee: Issoire Constellium
• Original Assignee: Alcan Rehnalu, Constellium France
• Inventors: JARRY, Philippe
• Granted Patent: US 9,670,567 B2
• Time in Patent Office: Days
• US Class Current: 420/528
• CPC Class Codes: B22D 1/00 Treatment of fused masses in the ladle or the supply runners before casting for continuous casting B22D11/10; metallurgical processing, e.g. refining of iron or other metal C21, C22, C25C
• CPC Class Codes: C22B 21/06 refining electrolytic refining C25C; C22B21/0046, C22B21/0061 take precedence
• CPC Class Codes: C22B 9/026 by acoustic waves, e.g. supersonic waves
• CPC Class Codes: C22C 21/00 Alloys based on aluminium
• CPC Class Codes: C22F 1/04 of aluminium or alloys based thereon
• CPC Class Codes: Y02P 10/20 Recycling

Abstract

The invention relates to a manufacturing method for making an unwrought semi-finished product having at mid thickness a density of micropores of size greater than 90 μm less than 50% and preferably less than 20% of the density of micropores of size greater than 90 μm obtained by a method according to prior art. The method according to the invention comprises in particular an ultrasound treatment step for the molten metal bath in a furnace and/or a vessel using an immersed device comprising at least one ultrasound transmitter. The semi-finished products obtained according to the method of the invention are particularly advantageous for manufacturing by rolling sheets designed for the aircraft industry to produce spars, ribs, upper and lower wing skins and for manufacturing by extrusion sections designed for the aircraft industry to produce stiffeners.

Claims

1. A manufacturing method for an unwrought aluminum alloy semi-finished product optionally comprising a rolling slab and/or an extrusion billet, said method comprising:

(i) preparing a molten metal bath of an alloy having a composition comprising, percentage by weight;

Zn;

0-12

Cu;

0-6

Mg;

0-6

Li;

0-3

Ag;

0-1

Si<

0.5

Fe<

0.5

optionally at least one of Cr, Zr, Mn, Hf, Ti, Sc, V, B, with a content<

0.5, remainder aluminum,

(ii) treating with ultrasound said molten metal bath in a furnace and/or a vessel using an immersed device comprising at least one ultrasound transmitter,

(iii) transferring said molten metal bath so treated to a solidification device,

(iv) vertical direct chill semi-continuous casting said treated molten metal bath.

2. Method according to claim 1 wherein said treating with ultrasound is carried out with a total ultrasound power P for a length of time t such that the energy P×

t is at least equal to a minimum energy per mass unit E_min of 1 kJ/kg, the minimum duration of treatment of the mass unit being called t_min=E_min/P.

3. Method according to claim 2 in which P is at least equal to 400 W and/or t is at least equal to 60 s.

4. Method according to claim 2, wherein said treating with ultrasound is carried out during casting in a vessel dimensioned so that an average residence time of a mass unit is at least equal to t_min.

5. Method according to claim 1, wherein said treating with ultrasound is carried out in a furnace stirred by electromagnetic means which optionally comprises an induction furnace.

6. Method according to claim 1, wherein said molten metal bath is at a temperature at least equal to 690°

C. during the treating with ultrasound.

7. Method according to claim 1, wherein a duration elapsing between an end of said treating with ultrasound of the liquid metal bath and an introduction of said liquid metal bath in the solidification device is at least a few minutes and optionally comprises at least three minutes.

8. Method according to claim 1, wherein said molten metal bath is an alloy having a Mg content of at least 0.1% by weight and/or a Li content of at least 0.1% by weight.

9. Method according to claim 1, wherein there is no degassing in said method and the hydrogen content of said molten metal bath during solidification is least 0.15 ml/100 g.

10. Method according to claim 1, wherein said alloy is selected from the group consisting of AA2014, AA2017, AA2024, AA2024A, AA2027, AA2139, AA2050, AA2195, AA2196, AA2296, AA2098, AA2198, AA2099, AA2199, AA2214, AA2219, AA2524, AA5019, AA5052, AA5083, AA5086, AA5154, AA5182, AA5186, AA5383, AA5754, AA5911 AA7010, AA7020, AA7040, AA7140, AA7050, AA7055, AA7056, AA7075, AA7449, AA7450, AA7475, AA7081, AA7085, AA7910, and AA7975.

11. Method according to claim 1, wherein a semi-finished product obtained by said method has at mid thickness, a density of micropores of a size greater than 90 μ

m, that is less than 50% of a density of micropores of a size greater than 90 μ

m obtained by a method that is identical to said method but does not includes said treating by ultrasound.

14. A method of claim 9, wherein said hydrogen content is at least 0.25 ml/100 g.

15. A method of claim 9, wherein said hydrogen content is at least 0.30 ml/100 g.

16. A method of claim 11, wherein a semi-finished product obtained by said method has at mid thickness, a density of micropores of a size greater than 90 μ

m, that is less than 20% of a density of micropores of a size greater than 90 μ

m obtained by a method that is identical said method but does not include said treating by ultrasound.

12. Facility for vertical direct chill semi-continuous casting, said facility comprising:

at least one furnace for melting metal and/or keeping metal at a given temperature and/or operations for preparing molten metal and adjusting the composition of said metal, at least one vessel designed to perform a treatment to remove impurities that are dissolved and/or are in suspension in molten metal, a device for solidifying molten metal by vertical direct chill semi-continuous casting, said device for solidifying comprising at least one ingot mould, a bottom block, a device to move downwardly, at least one device for procuring molten metal and a cooling system, wherein said furnace, said vessel and said device for solidifying being connected to each other by troughs in which molten metal can be transported, wherein said facility further comprises at least one immersed device comprising at least one ultrasound transmitter positioned in a furnace and/or a vessel.

13. Facility according to claim 12, wherein said device comprising an ultrasound transmitter is positioned in an induction furnace.

17. A method for manufacturing an unwrought aluminum alloy semi-finished product comprising conducting an ultrasound treatment in a furnace and/or a vessel upstream of casting said semi-finished product, wherein said ultrasound treatment decreases dimensions of micropores in solidified metal of said alloy and hydrogen content and grain structure are not modified.

18. A method of claim 17, wherein no degassing is present.

19. A method of claim 17, wherein said alloy comprises

Zn:

0-12

Cu;

0-6

Mg;

0-6

Li;

0-3

Ag;

0-1

Si<

0.5

Fe<

0.5

optionally at least one of Cr, Zr, Mn, Hf, Ti, Sc, V, B, with a content<

0.5, remainder aluminum.

20. A semi-finished product obtained by a method of claim 17 that has at mid thickness, a density of micropores of a size greater than 90 μ

m, that is less than 50% of a density of micropores of a size greater than 90 μ

m obtained by a method that is identical to said method but does not include conducting an ultrasound treatment upstream of casting.

21. The product of claim 20, wherein in a homogenized state has a hydrogen content greater than 0.15 ml/100 g.

22. The product of claim 20, wherein said alloy comprises at least 0.1% Mg and/or 0.1% Li.

23. An aircraft part comprising a product of claim 20.