High toughness plate alloy for aerospace applications

• US 20020079027A1
• Filed: 02/07/2002
• Published: 06/27/2002
• Est. Priority Date: 12/12/1997
• Status: Active Grant

• Current Assignee: Howmet Aerospace, Inc.
• Original Assignee: Dhruba J. Chakrabarti, Gary H. Bray, John Liu, Robert W. Westerlund, Terrence N. Thom
• Inventors: Westerlund, Robert W., Liu, John, Chakrabarti, Dhruba J., Bray, Gary H., Thom, Terrence N.
• Granted Patent: US 6,576,071 B2
• Time in Patent Office: Days
• US Class Current: 148/439
• CPC Class Codes: C22C 21/12 with copper as the next major constituent
• CPC Class Codes: C22C 21/16 with magnesium
• CPC Class Codes: C22F 1/057 of alloys with copper as the next major constituent

Abstract

The present invention is directed to highly controlled alloy composition relationship of a high purity Al—Mg—Cu alloy within the 2000 series aluminum alloys as defined by the Aluminum Association, wherein significant improvements are revealed in fracture toughness through plane strain, fracture toughness through plane stress, fatigue life, and fatigue crack growth resistance.

Claims

1. A 2000 series aluminum product alloy consisting essentially of in weight percent about 3.60 to 4.25 copper, about 1.00 to 1.60 magnesium, about 0.30 to 0.80 manganese, no greater than about 0.05 silicon, no greater than about 0.07 iron, no greater than about 0.06 titanium, no greater than about 0.002 beryllium, the remainder aluminum and incidental elements and impurities, wherein a T_max heat treatment is below the lowest incipient melting temperature for a given 2000 series alloy composition and the Cu_target is determined by the expression:

Cu_target=Cu_eff+0.74(Mn−

0.2)+2.28(Fe−

0.005)

wherein said alloy improves by a minimum of 5% compared to the average values of standard 2324-T39 alloy shown in FIG. 1 for the same properties selected from the group consisting of the plane strain fracture toughness, K_Ic, the plane stress fracture toughness, K_app, the stress intensity factor range, Δ

K, at a fatigue crack growth rate of 10μ

-inch/cycle wherein R=0.1 and RH is greater than 90%, and combinations thereof.

3. The 2000 series aluminum alloy of claim 1 wherein the Cu_target composition is about 3.85 to about 4.05 weight percent and the Mg_target is about 1.25 to about 1.45 weight percent.

4. The 2000 series aluminum alloy of claim 1 wherein said minimum improves by 5.5%.

5. The 2000 series aluminum alloy of claim 1 wherein said minimum improves by 6%.

6. The 2000 series aluminum alloy of claim 1 wherein said minimum improves by 6.5%.

7. The 2000 series aluminum alloy of claim 1 wherein said minimum improves by 7%.

8. The 2000 series aluminum alloy of claim 1 wherein said minimum improves by 7.5%.

9. The 2000 series aluminum alloy of claim 1 wherein said alloy is a structural component in an aerospace product.

10. The 2000 series aluminum alloy of claim 1 wherein said alloy is a part of a lower wing.

18. The 2000 series aluminum alloy of claim 1 wherein said alloy is a part of a lower wing.

21. The 2000 series aluminum alloy of claim 1 wherein said alloy is in a T-39 temper.

22. The 2000 series aluminum alloy of claim 1 wherein said alloy is in a T-351 temper.

23. The 2000 series aluminum alloy of claim 1 wherein said K_Ic improves by a minimum of 1.9 in.

24. The 2000 series aluminum alloy of claim 1 wherein said K_app improves by a minimum of 4.9 ksi{square root}in.

25. The 2000 series aluminum alloy of claim 1 wherein said Δ

K at a fatigue crack growth rate of 10μ

-inch/cycle improves by a minimum of 0.65 ksi{square root}in with R equal to 0.1 and RH greater than 90%.

26. The 2000 series aluminum alloy of claim 1 wherein said K_Ic improves by a minimum of 2.0 ksi{square root}in.

27. The 2000 series aluminum alloy of claim 1 wherein said K_app improves by a minimum of 5.4 ksi{square root}in.

28. The 2000 series aluminum alloy of claim 1 where in said Δ

K at a fatigue crack growth rate of 10μ

-inch/cycle improves by a minimum of 0.71 ksi{square root}in with R equal to 0.1 and RH greater than 90%.

29. The 2000 series aluminum alloy of claim 1 wherein said K_Ic improves by a minimum of 2.2 ksi{square root}in.

30. The 2000 series aluminum alloy of claim 1 wherein said K_app improves by a minimum of 5.9 ksi{square root}in.

31. The 2000 series aluminum alloy of claim 1 wherein said Δ

K at a fatigue crack growth rate of 10μ

-inch/cycle improves by a minimum of 0.80 ksi{square root}in n with R equal to 0.1 and RH greater than 90%.

32. The 2000 series aluminum alloy of claim 1 wherein said K_Ic improves by a minimum of 2.4 ksi{square root}in.

33. The 2000 series aluminum alloy of claim 1 wherein said K_app improves by a minimum of 6.4 ksi{square root}in.

34. The 2000 series aluminum alloy of claim 1 wherein said Δ

K at a fatigue crack growth rate of 10μ

-inch/cycle improves by a minimum of 0.85 ksi{square root}in with R equal to 0.1 and RH greater than 90%.

35. The 2000 series aluminum alloy of claim 1 wherein said K_Ic improves by a minimum of 2.6 ksi{square root}in.

36. The 2000 series aluminum alloy of claim 1 wherein said K_app improves by a minimum of 6.9 ksi{square root}in.

37. The 2000 series aluminum alloy of claim 1 where in said Δ

K at a fatigue crack growth rate of 10μ

-inch/cycle improves by a minimum of 0.90 ksi{square root}in with R equal to 0.1 and RH greater than 90%.

38. The 2000 series aluminum alloy of claim 1 wherein said K_Ic improves by a minimum of 2.8 ksi{square root}in.

39. The 2000 series aluminum alloy of claim 1 wherein said K_app improves by a minimum of 7.4 ksi{square root}in.

40. The 2000 series aluminum alloy of claim 1 wherein said Δ

K at a fatigue crack growth rate of 10μ

-inch/cycle improves by a minimum 1.00 ksi{square root}in with R equal to 0.1 and RH greater than 90%.

2. A 2000 series aluminum product alloy consisting essentially of a composition within the box of W, X, Y, and Z as defined in FIG. 5, wherein T_max for each composition corner point is W=925°

F., X=933°

F., Y=917°

F., and Z=909°

F., wherein Cu_target is defined by the following equation;

Cu_target=Cu_eff+0.74(Mn−

0.2)+2.28(Fe−

0.005).

11. The 2000 series aluminum alloy of claim 2 wherein said alloy improves by a minimum of 5% compared to the average values of standard 2324-T39 alloy shown in FIG. 1 for the same properties selected from the group consisting of the plane strain fracture toughness, K_Ic, the plane stress fracture toughness, K_app, the stress intensity factor range, Δ

K, at a fatigue crack growth rate of 10μ

-inch/cycle wherein R=0.1 and RH is greater than 90%, and combinations thereof.

12. The 2000 series aluminum alloy of claim 2 wherein said alloy improves by a minimum of 5.5% compared to the average values of standard 2324-T39 alloy shown in FIG. 1 for the same properties selected from the group consisting of the plane strain fracture toughness, K_Ic, the plane stress fracture toughness, K_app, the stress intensity factor range, Δ

K, at a fatigue crack growth rate of 10μ

-inch/cycle wherein R=0.1 and RH is greater than 90%, and combinations thereof.

13. The 2000 series aluminum alloy of claim 2 wherein said alloy improves by a minimum of 6% compared to the average values of standard 2324-T39 alloy shown in FIG. 1 for the same properties selected from the group consisting of the plane strain fracture toughness, K_Ic, the plane stress fracture toughness, K_app, the stress intensity factor range, Δ

K, at a fatigue crack growth rate of 10μ

-inch/cycle wherein R=0.1 and RH is greater than 90%, and combinations thereof.

14. The 2000 series aluminum alloy of claim 2 wherein said alloy improves by a minimum of 6.5% compared to the average values of standard 2324-T39 alloy shown in FIG. 1 for the same properties selected from the group consisting of the plane strain fracture toughness, K_Ic, the plane stress fracture toughness, K_app, the stress intensity factor range, Δ

K, at a fatigue crack growth rate of 10μ

-inch/cycle wherein R=0.1 and RH is greater than 90%, and combinations thereof.

15. The 2000 series aluminum alloy of claim 2 wherein said alloy improves by a minimum of 7% compared to the average values of standard 2324-T39 alloy shown in FIG. 1 for the same properties selected from the group consisting of the plane strain fracture toughness, K_Ic, the plane stress fracture toughness, K_app, the stress intensity factor range, Δ

K, at a fatigue crack growth rate of 10μ

-inch/cycle wherein R=0.1 and RH is greater than 90%, and combinations thereof.

16. The 2000 series aluminum alloy of claim 2 wherein said alloy improves by a minimum of 7.5% compared to the average values of standard 2324-T39 alloy shown in FIG. 1 for the same properties selected from the group consisting of the plane strain fracture toughness, K_Ic, the plane stress fracture toughness, K_app, the stress intensity factor range, Δ

K, at a fatigue crack growth rate of 10μ

-inch/cycle wherein R=0.1 and RH is greater than 90%, and combinations thereof

17. The 2000 series aluminum alloy of claim 2 wherein said alloy is a structural component in an aerospace product.

19. The 2000 series aluminum alloy of claim 2 wherein said T_max increases from about 1, 2, 3, 4, or 5°

F. when silicon is less than about 0.04 weight percent.

20. The 2000 series aluminum alloy of claim 2 wherein said T_max increases from about 1, 2, 3, 4, or 5°

F. when silicon is less than about 0.03 weight percent.