Damage tolerant aluminum alloy product and method of its manufacture

• US 20010023721A1
• Filed: 05/01/2001
• Published: 09/27/2001
• Est. Priority Date: 12/22/1998
• Status: Abandoned Application

• Current Assignee: Alfred Johann Peter Haszler, Alfred Ludwig Heinz
• Original Assignee: Alfred Johann Peter Haszler, Alfred Ludwig Heinz
• Inventors: Heinz, Alfred Ludwig, Haszler, Alfred Johann Peter
• Application Number:
  US09/845,181
• Publication Number:
  US 20010023721A1
• Time in Patent Office: Days
• US Class Current: 148/439
• CPC Class Codes: B32B 15/016 all layers being formed of aluminium or aluminium alloys
• CPC Class Codes: C22C 21/16 with magnesium
• CPC Class Codes: C22F 1/057 of alloys with copper as the next major constituent
• CPC Class Codes: Y10T 428/12764 Next to Al-base component

Abstract

The invention relates to a product comprising an aluminum base alloy consisting of (in weight %): Cu 3.8 - 4.9, Mg 1.2 - 1.8, Mn 0.1 - 0.9, Fe max. 0.12, Si max. 0.10, Ti max. 0.15, Zn max. 0.20, Cr max. 0.10, impurities each max. 0.05, total max. 0.15, balance aluminum. The product having a minimum L-0.2% yield strength of 300 MPa or more, a minimum LT-0.2% yield strength of 270 MPa, a minimum T-L fracture toughness K_C(ao) of 100 MPa.{square root}m or more for a 700 mm wide CCT-panel, and has in both L/ST- and LT/ST-sections an average grain size of at least 6 according to ASTM E-112. Further the invention relates to a method for the manufacturing of such a product.

Claims

1. A damage tolerant alloy product comprising an aluminum base alloy consisting essentially of (in weight %):

Cu3.8-4.9Mg1.2-1.8Mn0.1-0.9Femax. 0.12Simax. 0.10Timax. 0.15Znmax. 0.20Crmax. 0.10impuritieseachmax. 0.05totalmax. 0.15

balance aluminum,

said product having a minimum L-0.2% yield strength of 300 MPa or more, a minimum LT-0.2% yield strength of 270 MPa, a minimum T-L fracture toughness K_C(ao) of 100 MPa.{square root}m or more for a 700 mm wide CCT-panel, and having in both L/ST- and LT/ST-sections an average grain size of at least 6 according to ASTM E-112.

2. The product in accordance with

claim 1

, wherein the Cu content is in a range of 3.8 to 4.7%.

3. The product in accordance with

claim 1

, wherein the Cu content is in a range of 3.9 to 4.6%.

4. The product in accordance with

claim 1

, wherein the Mg content is in a range of 1.2 to 1.7%.

5. The product in accordance with

claim 1

, wherein the Mn content is in a range of 0.1 to 0.8%.

6. The product in accordance with

claim 1

, wherein the product has minimum longitudinal (L)-0.2% yield strength of 360 MPa or more, the minimum 0.2% yield strength in the TL-direction (transverse direction) is 300 MPa.

7. The product in accordance with

claim 1

, wherein the product has minimum transverse (TL)-tensile strength of 440 MPa or more and a minimum longitudinal (L)-tensile strength of 475 MPa or more.

8. The product in accordance with

claim 1

, wherein the product has minimum L-T fracture toughness K_C(ao) of 105 MPa.{square root}m for 700 mm wide CCT-panels.

9. The product in accordance with

claim 1

, wherein the minimum T-L fracture toughness K_C(ao) is 170 MPa.{square root}m or more for 2000 mm wide CCT-panels.

10. The product in accordance with

claim 1

, wherein the minimum T-L fracture toughness K_C(ao) is 175 MPa.{square root}m or more for 2000 mm wide CCT-panels.

11. The product in accordance with

claim 1

, wherein the grain aspect ratio in both L/ST- and LT/ST-sections is 1:

4 or less.

12. The product in accordance with

claim 1

, wherein the grain aspect ratio in both L/ST- and LT/ST-sections is 1:

3 or less.

13. The product in accordance with

claim 1

, wherein the grain aspect ratio in both L/ST- and LT/ST-sections is 1:

2 or less.

14. The product in accordance with

claim 1

, wherein the product is a sheet product.

15. The product in accordance with any one of

claim 1

, wherein the product is a plate product.

16. A composite comprising the product in accordance with

claim 1

, and a cladding on the product, the cladding comprising a higher purity aluminum alloy than said product.

17. A composite comprising the product in accordance with

claim 1

, and a cladding on the product, the cladding comprising a member of the group consisting of:

(i) an alloy of the Aluminum Association AA1000 series;

(ii) an alloy of the Aluminum Association AA6000 series; and

(iii) an alloy of the Aluminum Association AA7000 series.

28. An aircraft skin comprising a sheet or plate of the damage tolerant alloy product of

claim 1

.

18. A method for manufacturing a damage tolerant alloy product, comprising the steps of:

(a) casting an ingot or a slab comprising an aluminum alloy consisting of (in wt. %);

Cu3.8-4.9Mg1.2-1.8Mn0.1-0.9Femax. 0.12Simax. 0.10Timax. 0.15Znmax. 0.20Crmax. 0.10impuritieseach max. 0.05total max. 0.15

balance aluminum;

(b) hot rolling the ingot to form an intermediate product;

(c) cold rolling the intermediate product to form a rolled product in both the length and in the width direction with a total cold deformation of more than 60%;

(d) solution heat treating the intermediate product after cold rolling in at least one direction;

(e) cooling the solution heat treated intermediate product; and

(f) ageing the cooled intermediate product;

said damage tolerant product having a minimum L-0.2% yield strength of 300 MPa or more, a minimum LT-0.2% yield strength of 270 MPa, a minimum T-L fracture toughness K_C(ao) of 100 MPa.{square root}m or more for a 700 mm wide CCT-panel, and having in both L/ST- and LT/ST-sections an average grain size of at least 6 according to ASTM E-112.

19. The method in accordance with

claim 18

, wherein during step (b) the ingot is hot rolled in both the length and in the width direction.

20. The method in accordance with

claim 18

, wherein during step (c) the intermediate product is first cold rolled in the one direction with a total cold deformation in the range of 20 to 55% and then further cold rolled in the other direction to a rolled product with a total cold deformation of 60% or more.

21. The method in accordance with

claim 20

, wherein the process step (c) comprises the sequential steps of:

(c-i) first cold rolling the intermediate product in one direction with a total cold deformation in the range of 20 to 55%;

(c-ii) solution heat treating the intermediate product after cold rolling;

(c-iii) tempering the solution heat treated intermediate product to a T3 or a T351-temper;

(c-iv) soft annealing the tempered intermediate product; and

(c-v) cold rolling of the soft annealed intermediate product in at least another direction to a final gauge thickness with a total cold deformation of more than 60%.

22. The method in accordance with

claim 21

, wherein during process step (c-v) the soft annealed intermediate product is being cold rolled in both the length and in the width direction.

23. The method in accordance with

claim 21

, wherein the hot rolling of the ingot to the intermediate product occurs after homogenization at a temperature of 400 to 505°

C.

24. The method in accordance with

claim 21

, wherein solution heat treating of the intermediate product after cold rolling in at least one direction occurs at a temperature of 460 to 505°

C. for 5 to 120 minutes.

25. The method in accordance with

claim 21

, wherein the solution heat treated intermediate product is cooled to a temperature of 175°

C. or lower.

26. The method in accordance with

claim 21

, wherein soft annealing of the cooled intermediate product occurs at a temperature of 300 to 430°

C. for 0.5 to 12 hours.

27. The method in accordance with

claim 21

, wherein between cold rolling passes, the intermediate product is inter-annealed at a temperature of 300 to 430°

C. for 0.5 to 12 hours.

29. An aircraft skin comprising a sheet or plate of the damage tolerant alloy product made by the method of

claim 18

.

30. A damage tolerant alloy product comprising an aluminum base alloy consisting of (in weight %):

Cu3.8-4.9Mg1.2-1.8Mn0.1-0.9Femax. 0.12Simax. 0.10Timax. 0.15Znmax. 0.20Crmax. 0.10impuritieseach max. 0.05total max. 0.15

balance aluminum,

said product having a minimum L-0.2% yield strength of 300 MPa or more, a minimum LT-0.2% yield strength of 270 MPa, a minimum T-L fracture toughness K_C(ao) of 100 MPa.{square root}m or more for a 700 mm wide CCT-panel, and having in both L/ST- and LT/ST-sections an average grain size of at least 6 according to ASTM E-112.