Aluminum-zinc-magnesium-copper alloy wrought product

1 . A method of producing an aluminum alloy flat rolled product having: improved strength and fracture toughness, the method comprising the steps of:

(a) providing a molten body of an aluminum base alloy comprised of 1.95 to 2.5 wt. % Cu, 1.95 to 2.5 wt. % Mg, 8.2 to 10 wt. % Zn, 0.05 to 0.25 wt. % Zr, max. 0.15 wt. % Si, max. 0.15 wt. % Fe, max. 0.1 wt. % Mn, the remainder aluminum and incidental elements and impurities;

(b) casting said molten body of said aluminum base alloy to provide an ingot, said molten aluminum base alloy being cast at a rate in the range of 1 to 6 inches per minute;

(c) homogenizing said ingot by heating in a first temperature range of 840 to 860° F. followed by heating in a second temperature range of 860° to 880° F., the second homogenization temperature being greater than the first temperature to provide a homogenized ingot having a uniform distribution of η precipitate and zirconium containing dispersoids;

(d) rolling said homogenized ingot to provide a flat rolled product, said rolling being carried out in a temperature range of 600° to 850° F.;

(e) solution heat treating said flat rolled product; and

(f) artificial aging said flat rolled product to provide a product having improved strength and fracture toughness.

2 . The method in accordance with claim 1 wherein the alloy contains 1.95 to 2.3 wt. % Cu.

3 . The method in accordance with claim 1 wherein the alloy contains 1.95 to 2.3 wt. % Mg.

4 . The method in accordance with claim 1 wherein the alloy contains 0.05 to 0.2 wt. % Cr.

5 . The method in accordance with claim 1 wherein the alloy contains 8.45 to 9.4 wt. % Zn.

6 . The method in accordance with claim 1 wherein the alloy contains 0.01 to 0.1 wt. % Sc.

7 . The method in accordance with claim 1 wherein the alloy contains 0.01 to 0.2 wt. % Ti.

8 . The method in accordance with claim 1 including heating in said first temperature range for 6 to 18 hours.

9 . The method in accordance with claim 1 including heating in said second temperature range for 4 to 36 hours.

10 . The method in accordance with claim 1 including rapidly quenching said flat rolled product.

11 . The method in accordance with claim 1 wherein said solution heat treating is carried out in a temperature range of 875° to 885° F. for 5 to 120 minutes.

12 . The method in accordance with claim 1 wherein said artificial aging is carried out by aging in a temperature range of 175° to 300° F. for 3 to 30 hours followed by aging at 280° to 360° F. for 3 to 24 hours.

13 . The method in accordance with claim 1 wherein said artificial aging is carried out by aging in a temperature range of 210° to 280° F. for 4 to 24 hours followed by aging at 320° to 400° F. for 30 minutes to 14 hours.

14 . The method in accordance with claim 1 wherein said artificial aging is carried out by aging in a temperature range of 150° to 325° F. for 2 to 30 hours followed by aging at 300° to 500° F. for 5 minutes to 3 hours followed by aging at 175° to 325° F. for 2 to 30 hours.

15 . The method in accordance with claim 1 wherein said artificial aging is a three-step process wherein said first and third steps improve strength and a second step improves corrosion resistance.

16 . The method in accordance with claim 1 wherein said artificial aging includes aging: (i) at a low temperature above room temperature to precipitation harden said extrusion; (ii) at temperatures to improve corrosion resistance properties of said extrusion; and (iii) at lower temperatures above room temperature to precipitation harden said extrusion.

17 . The method in accordance with claim 1 wherein the flat rolled product has a fracture toughness at least 5% greater than a similar product fabricated from 7075 alloy.

18 . The method in accordance with claim 1 wherein the flat rolled product has a fracture toughness at least 8% greater than a similar product fabricated from 7075 alloy.

19 . The method in accordance with claim 1 wherein the flat rolled product is a plate product having thickness in the range of 2 to 12 inches.

20 . A method of producing an aluminum alloy flat rolled product having improved strength and fracture toughness, the method comprising the steps of:

(a) providing a molten body of an aluminum base alloy comprised of 1.95 to 2.3 wt. % Cu, 1.95 to 2.3 wt. % Mg, 8.2 to 9.4 wt. % Zn, 0.05 to 0.2 wt. % Cr, 0.05 to 0.15 wt. % Zr, max. 0.15 wt. % Si, max. 0.15 wt. % Fe, max. 0.1 wt. % Mn, the remainder aluminum and incidental elements and impurities;

(b) casting said molten body of said aluminum base alloy to provide an ingot, said molten aluminum base alloy being cast at a rate in the range of 1 to 6 inches per minute;

(c) homogenizing said ingot by heating in a first temperature range of 840° to 860° F. for 6 to 24 hours followed by heating in a second temperature range of 860° to 880° F. for 4 to 36 hours wherein the second homogenization temperature is greater than the first temperature to provide a homogenized body having a uniform distribution of η precipitate and zirconium and chromium containing dispersoids;

(d) rolling said homogenized ingot to provide a plate product, said rolling being carried out in a temperature range of 600° to 850° F.;

(e) rapidly quenching said plate product;

(f) solution heat treating said plate product; and

(g) artificial aging said product to provide a product having improved strength and fracture toughness.

21 . The method in accordance with claim 20 wherein the alloy contains 0.01 to 0.1 wt. % Sc.

22 . The method in accordance with claim 20 wherein the alloy contains 0.01 to 0.2 wt. % Ti.

23 . The method in accordance with claim 20 wherein said solution heat treating is carried out in a temperature range of 875° to 885° F. for 5 to 120 minutes.

24 . The method in accordance with claim 20 wherein said artificial aging is carried out by aging in a temperature range of 175° to 300° F. for 3 to 30 hours followed by aging at 280° to 360° F. for 3 to 24 hours.

25 . The method in accordance with claim 20 wherein said artificial aging is carried out by aging in a temperature range of 245° to 255° F. for 6 to 24 hours followed by aging at 360° to 390° F. for 5 to 120 minutes.

26 . The method in accordance with claim 20 wherein said artificial aging is a three-step process wherein said first and third steps improve strength and a second step improves corrosion resistance.

27 . The method in accordance with claim 20 wherein said artificial aging includes aging: (i) at a low temperature above room temperature to precipitation harden said extrusion; (ii) at temperatures to improve corrosion resistance properties of said extrusion; and (iii) at lower temperatures above room temperature to precipitation harden said extrusion.

28 . The method in accordance with claim 20 wherein the plate product has a fracture toughness at least 5% greater than a similar plate product fabricated from 7075 alloy.

29 . The method in accordance with claim 20 wherein said artificial aging is carried out by aging in a temperature range of 150° to 325° F. for 2 to 30 hours followed by aging at 300° to 500° F. for 5 minutes to 3 hours followed by aging at 175° to 325° F. for 2 to 30 hours.

30 . A method of producing an aluminum alloy plate product having improved strength and fracture toughness, the method comprising the steps of:

(a) providing a molten body of an aluminum base alloy comprised of 1.95 to 2.5 wt. % Cu, 1.95 to 2.5 wt. % Mg, 8.2 to 10 wt. % Zn, 0.05 to 0.25 wt. % Zr, max. 0.15 wt. % Si, max. 0.15 wt. % Fe, max. 0.1 wt. % Mn, the remainder aluminum and incidental elements and impurities;

(b) casting said molten body of said aluminum base alloy to provide an ingot, said molten aluminum base alloy being cast at a rate in the range of 1 to 4 inches per minute;

(c) homogenizing said ingot by heating in a first temperature range of 840 to 860° F. followed by heating in a second temperature range of 860° to 880° F., the second homogenization temperature being greater than the first temperature to provide a homogenized ingot having a uniform distribution of η precipitate;

(d) rolling said homogenized ingot to provide a plate product, said rolling being carried out in a temperature range of 600° to 850° F. to provide said plate product in a substantially non-recrystallized condition;

(e) rapidly quenching said plate product;

(f) solution heat treating said plate product; and

(g) artificial aging said product to provide a product having improved strength and fracture toughness.

31 . The method in accordance with claim 30 wherein the alloy contains 0.05 to 0.2 wt. % Cr.

32 . The method in accordance with claim 30 wherein the alloy contains 0.01 to 0.2 wt. % Ti.

33 . The method in accordance with claim 30 wherein the alloy contains 0.01 to 0.2 wt. % Sc.

34 . The method in accordance with claim 30 wherein said solution heat treating is carried out in a temperature range of 875° to 885° F. for 5 to 120 minutes.

35 . The method in accordance with claim 30 wherein said artificial aging is carried out by aging in a temperature range of 175° to 300° F. for 3 to 30 hours followed by aging at 280° to 360° F. for 3 to 24 hours.

36 . The method in accordance with claim 30 wherein said artificial aging is carried out by aging in a temperature range of 210° to 280° F. for 4 to 24 hours followed by aging at 300° to 400° F. for 1 to 14 hours.

37 . The method in accordance with claim 30 wherein said artificial aging includes aging: (i) at a low temperature above room temperature to precipitation harden said extrusion; (ii) at temperatures to improve corrosion resistance properties of said extrusion; and (iii) at lower temperatures above room temperature to precipitation harden said extrusion.

38 . The method in accordance with claim 30 wherein said artificial aging is carried out by aging in a temperature range of 150° to 325° F. for 2 to 30 hours followed by aging at 300° to 500° F. for 5 minutes to 3 hours followed by aging at 175° to 325° F. for 2 to 30 hours.

39 . An improved aluminum base alloy plate product consisting essentially of 1.95 to 2.5 wt. % Cu, 1.95 to 2.5 wt. % Mg, 8.2 to 10 wt. % Zn, 0.05 to 0.25 wt. % Zr, max. 0.15 wt. % Si, max. 0.15 wt. % Fe, max. 0.1 wt. % Mn, the remainder aluminum and incidental elements and impurities, said plate product having a fracture toughness of 5% or greater and a yield strength of 8% or greater than a similarly sized 7075 product.

40 . The alloy product in accordance with claim 39 wherein the alloy contains 1.95 to 2.3 wt. % Cu.

41 . The alloy product in accordance with claim 39 wherein the alloy contains 1.9 to 2.3 wt. % Mg.

42 . The alloy product in accordance with claim 39 wherein the alloy contains 0.05 to 0.2 wt. % Cr.

43 . The alloy product in accordance with claim 39 wherein the alloy contains 8.45 to 9.4 wt. % Zn.

44 . The alloy product in accordance with claim 39 wherein the alloy contains 0.01 to 0.2 wt. % Sc.

45 . The alloy product in accordance with claim 39 wherein the alloy contains 0.01 to 0.2 wt. % Ti.

46 . The alloy product in accordance with claim 39 wherein said product is a wing spar.

47 . The alloy product in accordance with claim 39 wherein sand product is a wing rib.

48 . The alloy product in accordance with claim 39 wherein said product is an aircraft stringer.

49 . The alloy product in accordance with claim 39 wherein said product is an aircraft floor beam.

50 . The alloy product in accordance with claim 39 wherein said product is an aircraft fuselage beam.