Al-Zn-Mg-Cu alloy with improved damage tolerance-strength combination properties
View Patent ↗An Al—Zn—Mg—Cu alloy with improved damage tolerance-strength combination properties. The present invention relates to an aluminium alloy product comprising or consisting essentially of, in weight %, about 6.5 to 9.5 zinc (Zn), about 1.2 to 2.2% magnesium (Mg), about 1.0 to 1.9% copper (Cu), preferable (0.9Mg−0.6)≦Cu≦(0.9Mg+0.05), about 0 to 0.5% zirconium (Zr), about 0 to 0.7% scandium (Sc), about 0 to 0.4% chromium (Cr), about 0 to 0.3% hafnium (Hf), about 0 to 0.4% titanium (Ti), about 0 to 0.8% manganese (Mn), the balance being aluminium (Al) and other incidental elements. The invention relates also to a method of manufacturing such as alloy.
1. An aluminium alloy product with high strength and fracture toughness and a good corrosion resistance, said alloy consisting of, in weight %:
Zn
7.2
to 7.43
Mg
1.92
to 2.1
Cu
1.43
to 1.80
Zr
about 0.06
to 0.1
Fe
<about 0.08
Si
<about 0.07
Mn
0.05
to 0.11
and other impurities or incidental elements each <0.05, total <0.15, and the balance being aluminium.
2. Aluminium alloy product according to claim 1 , wherein
Mg
1.92 to 1.95.
3. Aluminium alloy product according to claim 1 , wherein
Mg
1.92 to 1.95
Cu
1.43 to 1.75.
4. An aluminium aluminium alloy product according to claim 1 ,said alloy consisting of, in weight %:
Zn
7.2
to 7.43
Mg
1.92
to 2.1
Cu
1.43
to 1.75
Zr
about 0.06
to 0.10
Fe
<0.08
Si
<0.07
Mn
0.05
to 0.11
Ti
<0.05,
and other impurities or incidental elements each <0.05, total <0.15, and the balance being aluminium.
5. Aluminium alloy product according to claim 1 , wherein the product has an EXCO corrosion resistance of “EB” or better.
6. Aluminium alloy product according to claim 1 , wherein the product has an EXCO corrosion resistance of “EA” or better.
7. Aluminium alloy product according to claim 1 , wherein the product is in the form of a sheet, plate, forging or extrusion.
8. Aluminium alloy product according to claim 1 , wherein the product is in the form of a sheet, plate, forging or extrusion as part of an aircraft structural part.
9. Aluminium alloy product according to claim 1 , wherein the product is fuselage sheet, upper wing plate, lower wing plate, thick plate for machined parts, forging or thin sheet for stringers.
10. Aluminium alloy product according to claim 1 , wherein the product has a thickness in the range of 0.7 to 3 inch at its thickest cross sectional point.
11. Aluminium alloy product according to claim 1 , wherein the product has a thickness of less than 1 .5 inch.
12. Aluminium alloy product according to claim 11 , wherein the product has a thickness of less than 1.0 inch.
13. Aluminium alloy product according to claim 1 , wherein the product has a thickness of more than 2.5 inch.
14. Aluminium alloy product according to claim 13 , wherein the product has a thickness in the range of 2.5 to 11 inch.
15. Aluminium alloy product according to claim 1 , which in an extrusion having a thickness in the range of at most 10 mm at its thickest cross sectional point.
16. Aluminium alloy product according to claim 1 , which is an extrusion having a thickness in the range of 2 to 6 inch at its thickest cross sectional point.
17. Aluminium alloy product according to claim 1 , wherein the Mn-content is in the range of 0.09 to 0.11.
18. Aluminium alloy product according to claim 1 , wherein the product is in the form of a sheet or plate.
19. Aluminium alloy product according to claim 1 , wherein the product is in the form of a forging or extrusion.
20. Aluminium alloy product according to claim 19 , wherein the product has a thickness of less than 1.0 inch.
21. Aluminium alloy product according to claim 19 , wherein the product has a thickness of more than 2.5 inch.
22. Aluminium alloy product according to claim 21 , wherein the product has a thickness in the range of 2.5 to 11 inch.
23. Aluminium alloy product according to claim 19 , wherein the product is in the form of a forging or extrusion as part of an aircraft structural part.
24. Aluminium alloy product according to claim 3 , wherein the product is fuselage sheet, upper wing plate, lower wing plate, thick plate for machined parts, forging or thin sheet for stringers.
25. Aluminium alloy product according to claim 3 , which in an extrusion having a thickness in the range of at most 10 mm at its thickest cross sectional point.
26. Aluminium alloy product according to claim 3 , which is an extrusion having a thickness in the range of 2 to 6 inch at its thickest cross sectional point.
27. Aluminium alloy product according to claim 3 , wherein the product has an EXCO corrosion resistance of “EB” or better.
28. Aluminium alloy product according to claim 3 , wherein the product has an EXCO corrosion resistance of “EA” or better.
29. Aluminium alloy product according to claim 1 , which is a plate product having a thickness of 2.5 inch or more and exhibiting increased elongation in the ST-testing direction compared to its AA7050 counterpart.
30. Aluminium alloy product according to claim 29 , which plate product has an elongation in the ST-testing direction of 5% or more.
31. Aluminium alloy product according to claim 29 , which plate product has an elongation in the ST-testing direction of 5.5% or more.
32. Aluminium alloy product according to claim 1 , which is a plate product having a thickness of 2.5 inch or more and exhibiting a fracture toughness Kapp improvement of at least 20% compared to its AA7050 aluminium alloy counterpart in the L-T testing direction at ambient room temperature and when measured at S/4 according to ASTM E561 using 16-inch centre cracked panels.
33. Aluminium alloy product according to claim 1 , which is a plate product having a thickness of 2.5 inch or more and exhibiting a fracture toughness Kapp improvement of at least 20% compared to its AA7050 aluminium alloy counterpart in the L-T testing direction at ambient room temperature and when measured at S/4 according to ASTM E561 using 16-inch centre cracked panels.
34. An aluminium alloy structural component for a commercial jet aircraft, said structural component made from an aluminium alloy product according to claim 1 .
35. An aluminium alloy structural component for a commercial jet aircraft, said structural component made from an aluminium alloy product according to claim 3 .
36. Method of producing a high-strength, high-toughness AA7xxx-series alloy product having a good corrosion resistance, comprising the processing steps of:
a.) casting an ingot having a composition according to claim 1 ;
b.) homogenising and/or pre-heating the ingot after casting;
c.) hot working the ingot into a pre-worked product by one or more methods selected from the group consisting of: rolling, extruding and forging;
d.) optionally reheating the pre-worked product and either,
e.) hot working and/or cold working to a desired workpiece form;
f.) solution heat treating said formed workpiece at a temperature and time sufficient to place into solid solution essentially all soluble constituents in the alloy;
g.) quenching the solution heat treated workpiece by one of spray quenching or immersion quenching in water or other quenching media;
h.) optionally stretching or compressing of the quenched workpiece;
i.) artificially ageing the quenched and optionally stretched or compressed workpiece to achieve a desired temper.
37. Method according to claim 36 , wherein during processing step i.) the alloy product is artificially aged to a temper selected from the group consisting of T6, T74, T76, T751, T7451, T7651, T77 and T79.
38. Method according to claim 36 , wherein during processing step h.) the alloy product has been stretched in a range at most 8%.
39. Method according to claim 36 , wherein during processing step b.) the ingot has been homogenised at a temperature in the range of 460 to 490° C.
40. Method according to claim 36 , wherein the alloy product has been processed to fuselage sheet.
41. Method according to claim 40 , wherein the alloy product has been processed to fuselage sheet having a thickness of less than 1 .5 inch.
42. Method according to claim 36 , wherein the alloy product has been processed to lower wing plate.
43. Method according to claim 36 , wherein the alloy product has been processed to upper wing plate.
44. Method according to claim 36 , wherein the alloy product has been processed to an extruded product.
45. Method according to claim 36 , wherein the alloy product has been processed to a forged product.
46. Method according to claim 36 , wherein the alloy product has been processed to a thin plate having a thickness in the range of 0.7 to 3 inch.
47. Method according to claim 36 , wherein the alloy product has been processed to a thick plate having a thickness at most 11 inch.
48. Method of producing a high-strength, high-toughness AA7xxx-series alloy product having a good corrosion resistance, comprising the processing steps of:
a.) casting an ingot having a composition according to claim 33 ,
b.) homogenising and/or pre-heating the ingot after casting;
c.) hot working the ingot into a pre-worked product by one or more methods selected from the group consisting of: rolling, extruding and forging;
d.) optionally reheating the pre-worked product and either,
e.) hot working and/or cold working to a desired workpiece form;
f.) solution heat treating said formed workpiece at a temperature and time sufficient to place into solid solution essentially all soluble constituents in the alloy;
g.) quenching the solution heat treated workpiece by one of spray quenching or immersion quenching in water or other quenching media;
h.) optionally stretching or compressing of the quenched workpiece;
i.) artificially ageing the quenched and optionally stretched or compressed workpiece to achieve a desired temper.
49. Method according to claim 48 , wherein during processing step i.) the alloy product is artificially aged to a temper selected from the group consisting of T6, T74, T76, T751, T7451, T7651, T77 and T79.
50. Method according to claim 48 , wherein during processing step h.) the alloy product has been stretched in a range to at most 8%.
51. Method according to claim 48 , wherein during processing step b.) the ingot has been homogenised at a temperature in the range of 460 to 490° C.
52. Method according to claim 48 , wherein the alloy product has been processed to fuselage sheet.
53. Method according to claim 48 , wherein the alloy product has been processed to fuselage sheet having a thickness of less than 1.5 inch.
54. Method according to claim 48 , wherein the alloy product has been processed to lower wing plate.
55. Method according to claim 48 , wherein the alloy product has been processed to upper wing plate.
56. Method according to claim 48 , wherein the alloy product has been processed to an extruded product.
57. Method according to claim 48 , wherein the alloy product has been processed to a forged product.
58. Method according to claim 48 , wherein the alloy product has been processed to a thin plate having a thickness in the range of 0.7 to 3 inch.
59. Method according to claim 48 , wherein the alloy product has been processed to a thick plate having a thickness of at most 11 inches.