Al-Zn-Mg-Cu alloys and products with improved ratio of static mechanical characteristics to damage tolerance

1. An Al—Zn—Mg—Cu alloy product with a thickness of up to 60 mm, said alloy consisting of (in mass percentage):

a) Zn 9.0-9.5 Cu 1.32-1.67 Mg 1.6-about 1.96 Zr 0.03-0.15 Fe+Si<0.25,

b) Ti from 0.02-0.15%, and

c) aluminum remainder and inevitable impurities, and wherein

Mg/Cu<1.7 and

(7.7−0.4 Zn)>(Cu+Mg)>(6.4−0.4 Zn), wherein the elastic limit of said product is R p0.2 (L)>661 MPa and wherein the product comprises a breaking elongation A%(L)>10%.

2. A laminated, extruded or forged product comprising an alloy product as claimed in claim 1 .

3. A civilian aircraft comprising an alloy product as claimed in claim 1 .

4. A semi-finished product having a width between 0.5 m and 4m, a thickness from 10 mm to 60 mm and a length of between 6 m and more than 20 m comprising an alloy product as claimed in claim 1 .

5. An alloy product as claimed in claim 1 , wherein K app measured in the Long-Transverse direction according to ASTM E561 at half thickness on a specimen with the width W=406 mm is equal or greater than 70 MPa√m.

6. An alloy product as claimed in claim 1 , wherein K app measured in the Long-Transverse direction according to ASTM E561 at half thickness on a specimen with the width W=406 mm is equal or greater than 75 MPa√m.

7. An alloy product as claimed in claim 1 , with the proviso that Mg is not less than or equal to Cu.

8. An alloy product as claimed in claim 1 , with the proviso that Mg is not less than or equal to Cu+0.1.

9. An alloy product as claimed in claim 1 , with the proviso that Mg is not less than or equal to Cu+0.2.

10. An alloy product as claimed in claim 1 , with the proviso that Mg is not less than or equal to Cu+0.3.

11. A structural element suitable for aeronautical construction, incorporating at least one Al—Zn—Mg—Cu alloy product having a thickness of up to 60 mm which is laminated and/or extruded, said alloy consisting of (in mass percentage):

a) Zn 9.0-9.5 Cu 1.32-1.67 Mg 1.6-about 1.96 Zr 0.03-0.15 Fe+Si<0.25,

b) Ti from 0.02-0.15%, and

c) aluminum remainder and inevitable impurities, and wherein Mg/Cu<1.7,

(7.7−0.4 Zn)>(Cu+Mg)>(6.4−0.4 Zn), and

wherein the elastic limit of said product is Rpo 2 (L)>661 MPa and wherein the product comprises a breaking elongation A%(L)>10%.

12. A laminated, extruded or forged product comprising a structural element as claimed in claim 11 .

13. A structural element as claimed in claim 11 , wherein K 1C (L-T)>23 Mpa√m.

14. A civilian aircraft comprising a structural element as claimed in claim 11 .

15. A semi-finished product having a width between 0.5 m and 4m, a thickness from 10 mm to 60 mm and a length of between 6 m and more than 20 m comprising a structural element as claimed in claim 11 .

16. A structural element as claimed in claim 11 , wherein K app measured in the Long-Transverse direction according to ASTM E561 at half thickness on a specimen with the width W=406 mm is equal or greater than 70 MPa√m.

17. A structural element as claimed in claim 11 , wherein K app measured in the Long-Transverse direction according to ASTM E561 at half thickness on a specimen with the width W=406 mm is equal or greater than 75 MPa√m.

18. A structural element as claimed in claim 11 , wherein Mg>Cu.

19. A structural element as claimed in claim 11 , with the proviso that Mg is not less than or equal to Cu.

20. A structural element as claimed in claim 11 , with the proviso that Mg is not less than or equal to Cu+0.1.

21. A structural element as claimed in claim 11 , with the proviso that Mg is not less than or equal to Cu+0.2.

22. A structural element as claimed in claim 11 , with the proviso that Mg is not less than or equal to Cu+0.3.

23. An alloy product as claimed in claim 1 , wherein K 1C (L-T)>23 Mpa√m.

24. An alloy product as claimed in claim 23 , wherein K 1C (L-T)>25 Mpa√m.

25. An alloy product as claimed in claim 24 , wherein K 1C (L-T) is at least 29 Mpa√m.

26. A wing unit caisson having an extrados manufactured from an Al—Zn—Mg—Cu alloy sheet having a thickness of up to 60 mm, wherein said sheet consists of an alloy of (in mass percentage):

a) Zn 9.0-9.5 Cu 1.32-1.67 Mg 1.6-about 1.96 Zr 0.03-0.15 Fe+Si<0.25,

b) Ti from 0.02-0.15%, and

c) aluminum remainder and inevitable impurities, and wherein said sheet satisfies the following conditions

Mg/Cu<1.7; and

(7.7−0.4 Zn)>(Cu+Mg)>(6.4−0.4 Zn), wherein the elastic limit of said extrados is RpO.2(L)>661 MPa and wherein the extrados comprises a breaking elongation A%(L)>10%.

27. A wing unit caisson as claimed in claim 26 , wherein said sheet is used in metallurgic state T6 or T651.

28. A wing unit caisson as claimed in claim 26 , wherein said sheet is used in metallurgic state T7.

29. A wing unit caisson comprising at least one stiffener of a product having a thickness of up to 60 mm extruded in Al—Zn—Mg—Cu alloy, wherein said extruded product consists of (in mass percentage):

a ) Zn 9.0-9.5 Cu 1.32-1.67 Mg 1.6-about 1.96 Zr 0.03-0.15 Fe+Si<0.25

b) Ti from 0.02-0.15%, and

c) aluminum remainder and inevitable impurities, and wherein said stiffener satisfies the conditions

Mg/Cu<1.7

(7.7−0.4 Zn)>(Cu+Mg)>(6.4−0.4 Zn), wherein the elastic limit of said extruded product is Rp0.2(L)>661 MPa and wherein the extruded product comprises a breaking elongation A%(L)>10%.

30. A wing unit caisson as claimed in claim 29 , wherein said extruded product is used in metallurgic state T6 or T651.

31. A wing unit caisson as claimed in claim 29 , wherein said extruded product is used in metallurgic state T7.

32. An Al—Zn—Mg—Cu extruded alloy product having a thickness of up to 60 mm, consisting of (in mass percentage):

a) Zn 9.0-9.5 Cu 1.32-1.67 Mg 1.6-about 1.96 Zr 0.03-0.15Fe+Si<0.25,

b) Ti from 0.02-0.15%, and

c) aluminum remainder and inevitable impurities, and wherein

Mg/Cu<1.7,

(7.7−0.4 Zn)>(Cu+Mg)>(6.4−0.4 Zn)

and with the proviso that Mg is not less than or equal to Cu+0.1, the elastic limit of said product is Rp 0.2 (L)>661 MPa and

the extruded product comprises a breaking elongation A%(L)>10%,

said extruded product comprises a foot, an intermediate section and a top section, and

K 1C (L-T) for the top section is at least 37 MPa√m.

33. An Al—Zn—Mg—Cu extruded alloy product having a thickness of up to 60 mm, consisting of (in mass percentage):

a) Zn 9.0-9.5 Cu 1.32-1.67 Mg 1.6-about 1.96 Zr 0.03-0.15 Fe+Si<0.25,

b) Ti from 0.02-0.15%, and

c) aluminum remainder and inevitable impurities, and wherein

Mg/Cu<1.7,

(7.7−0.4 Zn)>(Cu+Mg)>(6.4−0.4 Zn),

the magnesium and copper content

thereof is selected such that Mg is not less than or equal to Cu and

Mg+Cu is not less than or equal to 3.3,

the elastic limit of said product Rp 0.2 (L) >661 MPa

the extruded product comprises a breaking elongation A%(L)>10%,

said extruded product comprises a foot, an intermediate section and a top section, and

K 1C (L-T) for the top section is at least 37 MPa√m.

34. An Al—Zn—Mg—Cu extruded alloy product having a thickness of up to 60 mm, consisting of (in mass percentage):

a) Zn 9.0-9.5 Cu 1.32-1.67 Mg 1.6-about 1.96 Zr 0.03-0.15 Fe+Si<0.25,

b) Ti from 0.02-0.15%, and

c) aluminum remainder and inevitable impurities, and wherein

Mg/Cu<1.7,

(7.7-0.4 Zn)>(Cu+Mg)>(6.4-0.4 Zn),

the magnesium and copper content thereof is selected such that Mg is not less than or equal to Cu+0.3, and Mg+Cu is not less than 3.5,

the elastic limit of said product is Rp 0.2 (L)>661 MPa,

the extruded product comprises a breaking elongation A%(L)>10%,

said extruded product comprises a foot, an intermediate section and a top section, and

K 1C (L-T) for the top section is at least 37 MPa√m.

35. An Al—Zn—Mg—Cu extruded alloy product with a thickness of up to 60 mm, said alloy consisting of (in mass percentage):

a) Zn: about 9.43 Cu: about 1.32-1.67 Mg: 1.6-about 1.96 Zr 0.03-0.15 Fe+Si<0.25,

b) Ti from 0.02-0.15%, and

c) aluminum remainder and inevitable impurities, wherein

the elastic limit of said product is R p02 (L)>661 MPa,

the product comprises a breaking elongation A%(L)>10%,

said extruded product comprise a foot, an intermediate section and a top section, and

K 1C (L-T) for the top section is at least 37 MPa√m.