Aluminum-copper-lithium alloy product for a lower wing skin element with improved properties

Patent metadata

Field	Value
Publication number	US-2016368589-A1
Application number	US-201415100768-A
Country	US
Kind code	A1
Filing date	Dec 2, 2014
Priority date	Dec 5, 2013
Publication date	Dec 22, 2016
Grant date	—

Abstract

The invention relates to a method for manufacturing a laminated or forged material, the thickness of which is 14 to 100 mm. The materials according to the invention are particularly suitable for manufacturing airplane underwing elements.

First claim

1 . Method of manufacturing a rolled or forged product in which:
(a) a slab of alloy is cast, of composition, as a percentage by weight, Cu: 1.8-2.6 Li: 1.3-1.8 Mg: 0.1-0.5 Mn: 0.1-0.5 and Zr<0.05 or Mn<0.05 and Zr 0.10-0.16 Ag: 0-0.5 Zn<0.20 Ti: 0.01-0.15 Fe: <0.1 Si: ≦0.1 other elements <0.05 each and <0.15 total, the remainder aluminum with a density less than 2.670 g/cm3, (b) said slab is homogenized at 480 to 540° C. for 5 to 60 hours, (c) said slab is hot worked by rolling and/or forging, the hot working conditions being such when the manganese content is 0.1 to 0.5% by weight and the zirconium content is less than 0.05% by weight the final hot working temperature is at least 400° C. or when the manganese content is less than 0.05% by weight and the zirconium content is between 0.10 and 0.16% by weight the final hot working temperature is at the most 400° C. to obtain a rolled and/or forged product having a thickness of between 14 and 100 mm, (d) said product is solution-heat treated at 490 to 530° C. for 15 minutes to 8 hours, (e) quench said product with water, (f) said product undergoes controlled stretching with a permanent deformation of 1 to 6%, (g) said product is artificially aged by heat treatment at 120 to 170° C. for 5 minutes to 100 hours.

2 . Method according to claim 1 in which the copper content of said alloy ranges between 1.9 and 2.3% by weight.

3 . Method according to claim 1 in which the lithium content of said alloy ranges between 1.4 and 1.6% by weight.

4 . Method according to claim 1 in which the magnesium content of said alloy ranges between 0.1 and 0.4% by weight.

5 . Method according to claim 1 in which the manganese content of said alloy is less than 0.04% by weight and in which the zirconium content of said alloy ranges between 0.11 and 0.15% by weight.

6 . Method according to claim 1 in which the silver content of said alloy ranges between 0.05 and 0.25% by weight.

7 . Method according to claim 1 in which the zinc content of said alloy is less than 0.05% by weight, the silicon content of said alloy is less than 0.08% by weight and the iron content of said alloy is less than 0.08% by weight.

8 . Method according to claim 1 wherein aging is such that the equivalent time t(eq) at 155° C. is between 20 and 40 hours and optionally between 25 and 35 hours, equivalent time t(eq) at 155° C. being defined by the formula:

t


(
eq
)

=

∫

exp


(

-
11400

/
T

)




t

exp


(

-
11400

/

T
ref

)

where T (in Kelvin) is the instantaneous treatment temperature, which changes with time t (in hours), and Tref is a reference temperature set at 428 K. t(eq) is expressed in hours.

9 . Rolled and/or forged product having a thickness of between 14 and 100 mm, obtainable by the method according to claim 1 , wherein at mid-thickness the volume fraction of grains having a brass texture is between 25 and 40% and the texture index is between 12 and 18.

10 . Rolled and/or forged product obtainable by the method according to claim 1 whose thickness is between 20 mm and 50 mm and whose tensile yield strength at mid-thickness TYS (L) is at least 390 MPa, the fracture toughness KappL-T (W=406 mm) is at least 105 MPa√m even after aging for 3,000 hours at 85° C. and the number of cycles in condition 6.5 MPa√m<ΔK<16.6 MPa√m at least 250,000 for a fatigue test performed according to ASTM E647 on CCT type specimens of width W=160 mm taken in direction L-T at ¼ thickness.

11 . A product according to claim 9 as a structural element in aircraft construction, and preferably optionally as an aircraft lower wing skin element.

Assignees

• Constellium Issoire

Inventors

• Bayona-Carrillo Nicolas

Classifications

• B21B3/00

  Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences {; Rolling of aluminium, copper, zinc or other non-ferrous metals}(altering special metallurgical properties of alloys, other than structure consolidation or mechanical properties resulting therefrom C21D, C22F) · CPC title

• C22F1/057

  of alloys with copper as the next major constituent · CPC title

• C22C21/00

  Alloys based on aluminium · CPC title

• C22C21/14 Primary

  with silicon · CPC title

• B21J1/003

  Selecting material · CPC title