2000 Series alloys with enhanced damage tolerance performance for aerospace applications
View Patent ↗The invention provides a 2000 series aluminum alloy having enhanced damage tolerance, the alloy consisting essentially of about 3.0-4.0 wt % copper; about 0.4-1.1 wt % magnesium; up to about 0.8 wt % silver; up to about 1.0 wt % Zn; up to about 0.25 wt % Zr; up to about 0.9 wt % Mn; up to about 0.5 wt % Fe; and up to about 0.5 wt % Si, the balance substantially aluminum, incidental impurities and elements, said copper and magnesium present in a ratio of about 3.6-5 parts copper to about 1 part magnesium. The alloy is suitable for use in wrought or cast products including those used in aerospace applications, particularly sheet or plate structural members, extrusions and forgings, and provides an improved combination of strength and damage tolerance.
1. A 2xxx series alloy product having an effective combination of strength, toughness and corrosion resistance, an alloy consisting essentially of,
Cu: about 3.0 to about 4.0 wt. %,
Mg: about0.4to about 1.1 wt. %,
Mn about 0.20 to about 0.9 wt %,
combined weight percent of Fe and Si less than about 0.25 wt. %,
Ag about 0.3 wt. % to about 0.8 wt. %
Zn up to about 0.40 wt. %,
and up to about 0.1 wt. % of a grain refiner, the remainder aluminum and incidental elements and impurities, wherein the combined weight percent of Ag and Zn is at least about 0.3 wt.% and the Cu and the Mg are present in a ratio of about 3.6-4.5 parts Cu to about 1 part Mg.
2. The alloy product of claim 1 , wherein the combined weight percent of Ag and Zn is at least about 0.4 wt. % and said ratio is about 4.0-4.5 parts Cu to 1.0 part Mg.
3. The alloy product of claim 1 , wherein the weight percent Ag is from 0.30 to 0.50.
4. The alloy product of claim 1 , further comprising a recrystallization inhibitor selected from the group consisting of Zr, Cr, Sc, Hf and Er.
5. The alloy product of claim 1 , wherein said recrystallization inhibitor is up to about 0.18 wt % of Zr.
6. The alloy product of claim 1 , wherein said grain refiner is a ceramic compound.
7. The alloy product of claim 1 , wherein said grain refiner is titanium or a titanium compound.
8. The alloy product of claim 1 , wherein said grain refiner is Ti, TiB 2 or TiC.
9. The alloy product of claim 1 , wherein the weight percent of Ag is at least 0.4 wt. %.
10. The alloy product of claim 1 , wherein the product is cold worked and artificially aged.
11. The alloy product of claim 1 , wherein the product is aged to an under-aged strength.
12. The alloy product of claim 1 , wherein the product is aged to peak strength.
13. The alloy product of claim 1 , wherein the product is aged to over-aged strength.
14. An aluminum alloy suitable for use as a sheet product in fuselage applications including skin, panels, and stringers, or for use in wing applications including lower wing skins, stringers, and panels, and in thick components such as spars and ribs, an alloy consisting essentially of,
copper from about 3.0 to about 4.0 wt. %,
magnesium from about 0.4 to about 1.1 wt. %,
manganese from about 0.2 to 0.4 wt. %,
silver from about 0.2 to 0.8 wt. %,
zinc from about 0.01 to 0.40 wt. %,
up to about 0.20 wt. % of a recrystallization inhibitor,
up to 0.10 wt % of a grain refiner selected from the group consisting essentially of Ti, TiB 2 , and TiC,
combined weight percent of Fe and Si less than about 0.25 wt. %,
the remainder aluminum and incidental elements and impurities,
wherein said Cu and Mg are present in a ratio of about 3.6-4.5 parts Cu to about 1 part Mg and
wherein said alloy product has one or more mechanical properties or combinations of mechanical properties selected from the group consisting of
1) toughness as measured by the Kahn tear test using ASTM B871 of at least about 40% higher than AA2524 similarly tested and having about the same UTS and TYS;
2) toughness as measured by the Kahn tear test using ASTM B871 of at least about 20% higher than AA2524 similarly tested and at least about a 10% increase in UTS and TYS relative to AA2524;
3) an average high load transfer joint fatigue life at least about 60% greater than 2X24HDT in terms of average fatigue life (in cycles); and
4) a change in corrosion property type from intergranular to pitting as measured by ASTM G110.
15. The alloy product of claim 14 , wherein the combined amount of Zn plus Ag is at least 0.3 wt. %.
16. The alloy product of claim 15 , wherein the combined amount of Zn plus Ag is from about 0.3 wt. % to about 0.6 wt. %.
17. The alloy product of claim 14 , wherein the combined weight percent of Ag and Zn is between about 0.3 and 1.2 wt. %.
18. The alloy product of claim 14 , wherein the product is cold worked and artificially aged.
19. The alloy product of claim 14 , wherein the product is aged to an under-aged strength.
20. The alloy product of claim 14 , wherein the product is aged to peak strength.
21. The alloy product of claim 14 , wherein the product is aged to over-aged strength.
22. The alloy product of claim 14 , wherein the product is stretched or cold compressed to at least 2 wt. %.
23. The alloy product of claim 14 , wherein the product is stretched or cold compressed at least 0.50%.
24. The alloy product of claim 14 , further comprising a recrystallization inhibitor selected from the group consisting of Zr, Cr, Sc, Hf and Er.