ALUMINUM MAGNESIUM LITHIUM ALLOY WITH IMPROVED FRACTURE TOUGHNESS

1 . A wrought product comprising an aluminum alloy of a composition, as a percentage by weight,

Mg: 4.0-5.0

Li: 1.0-1.6

Zr: 0.05-0.15

Ti: 0.01-0.15

Fe: 0.02-0.2

Si: 0.02-0.2

Mn: ≦0.5

Cr ≦0.5

Ag: ≦0.5

Cu ≦0.5

Zn ≦0.5

Sc <0.01

other elements <0.05, each

remainder aluminum;

2 . A wrought product according to claim 1 , comprising at least one element selected from the group consisting of Mn and Cr with the following contents if chosen, as a percentage by weight

Mn: 0.05-0.5

Cr: 0.05-0.3, and

an element not chosen from among Mn and Cr having a content less than 0.05% by weight.

3 . The wrought product according to claim 1 , comprising at least one element selected from the group consisting of Cu and Ag with the following contents if chosen, as a percentage by weight

Cu: 0.05-0.3

Ag: 0.05-0.3, and

an element not chosen from among Cu and Ag having a content less than 0.05% by weight.

4 . The wrought product according to claim 1 ,wherein the Li content is, as a percentage by weight

Li: 1.1-1.5.and optionally Li: 1.2-1.4.

5 . The wrought product according to claim 1 , wherein the Mg content is, as a percentage by weight

Mg: 4.4-4.7.

6 . The wrought product according to claim 1 , comprising a maximum Be content of 5 ppm and/or a maximum Na content of 10 ppm and/or a maximum Ca content of 20 ppm.

7 . The wrought product according to claim 1 , comprising a Zn content less than 0.2% by weight and optionally less than 0.05% by weight.

8 . The wrought product according to claim 1 , wherein said Fe content and/or said Si content are, as a percentage by weight

Fe: 0.04-0.15

Si: 0.04-0.15.

9 . The wrought product according to claim 1 , wherein said product has been worked and the working is carried out by rolling.

10 . The wrought product according to claim 9 , comprising a thickness ranging from 0.5 to 15 mm, at mid-thickness having at least one static mechanical strength property among properties (i) to (iii) and at least one damage tolerance property among properties (iv) to (vi)

(i) a tensile yield stress R p0.2 (L)≧280 MPa and optionally R p0.2 (L)≧310 MPa,

(ii) a tensile yield stress R p0.2 (LT)≧260 MPa and optionally R p0.2 (LT)≧290 MPa,

(iii) a tensile yield stress R p0.2 (45°)≧200 MPa and optionally R p0.2 (45°)≧240 MPa,

(iv) a fracture toughness for test-specimens of width W=760 mm K app (L-T)≧90 MPa√m for a thickness less than 3 mm and K app (L-T)≧110 MPa√m for a thickness of at least 3 mm,

(v) a fracture toughness for test-specimens of width W=760 mm K app (T-L)≧100 MPa√m for a thickness less than 3 mm and K app (T-L)≧120 MPa√m for a thickness of at least 3 mm,

(vi) a crack extension of the last valid point of R curve for test-specimens of width W=760 mm Δa eff(max) (T-L)≧80 mm for a thickness of less than 3 mm and Δa eff(max) (T-L)≧110 mm for a thickness of at least 3 mm.

11 . The manufacturing process for a wrought product according to claim 1 , comprising:

preparing a molten metal bath in order to obtain an aluminum alloy,

casting said alloy in a rough shape to form a cast product,

optionally homogenizing of the cast product,

hot and optionally cold working said product,

optionally heat treating the product at a temperature ranging from 300 to 420° C. in at least one step,

solution heat-treating the product so worked, and quenching,

optionally cold working the product that has been solution heat treated and quenched,

conducting artificial aging at a temperature of not more than 150° C.

12 . The process according to claim 11 , wherein said quenching is carried out in air.

13 . The product according to claim 1 , capable of being used to produce an aircraft structural element, optionally a fuselage skin, a fuselage framework, a stringer or a rib.

14 . The process of claim 11 , which is conducted in the order given.

15 . The process of claim 11 , wherein working is conducted by rolling.