Al-Zn-Mg-Cu ALLOY WITH IMPROVED DAMAGE TOLERANCE-STRENGTH COMBINATION PROPERTIES
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 7.9
Mg
1.92 to 2.1
Cu
1.43 to 1.80
Zr
0.04 to 0.15
Ti
<0.05
Fe
<about 0.08
Si
<about 0.07
Mn
at most 0.19,
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 is in a range of 1.92 to 1.95.
3 . Aluminium alloy product according to claim 1 , wherein
Mg is in a range of 1.92 to 1.95
Cu is in a range of 1.43 to 1.75.
4 . Aluminium alloy product according to claim 1 , wherein the Zn-content is in a range of 7.2 to 7.7%.
5 . Aluminium alloy product according to claim 1 , wherein the Zn-content is in a range of 7.2 to 7.43%.
6 . Aluminium alloy product according to claim 1 , wherein the Zr-content is at least 0.06% to 0.15.
7 . Aluminium alloy product according claim 1 , wherein
the Zr-content is in a range of 0.04 to 0.13%.
8 . Aluminium alloy product according to claim 1 , wherein
the Zr-content is in a range of 0.04 to 0.11%.
9 . Aluminium alloy product according claim 1 , wherein the Zr-content is in a range of about 0.06 to 0.15%.
10 . Aluminium alloy product according claim 1 , wherein the Zr-content is in a range of about 0.06 to 0.01%.
11 . Aluminium alloy product according to claim 1 , wherein the Mn-content is in a range <0.11%.
12 . Aluminium alloy product according to claim 1 , wherein the Mn-content is in a range of at most 0.02%.
13 . Aluminium alloy product according to claim 1 , wherein the Mn-content is in a range of at most 0.01%.
14 . Aluminium alloy product according to claim 1 , wherein the alloy product is substantially free from Mn.
15 . Aluminium alloy product according to claim 1 , wherein the alloy consists essentially of, in weight percent:
Zn
7.2 to 7.7
Mg
1.90 to 1.97
Cu
1.43 to 1.80
Zr
0.04 to 0.15
Mn
at most 0.19
Si
<0.07
Fe
<0.08
Ti
<0.05,
impurities each <0.05, total <0.15, and balance aluminium.
16 . Aluminium alloy product according to claim 1 , wherein the alloy consists essentially of, in weight percent:
Zn
7.2 to 7.7
Mg
1.90 to 1.97
Cu
1.43 to 1.52
Zr
0.04 to 0.15
Mn
at most 0.19
Si
<0.07
Fe
<0.08
Ti
<0.05,
impurities each <0.05, total <0.15, and balance aluminium.
17 . Aluminium alloy product according to claim 1 , wherein the product has an EXCO corrosion resistance of “EB” or better.
18 . Aluminium alloy product according to claim 1 , wherein the product has an EXCO corrosion resistance of “EA” or better.
19 . Aluminium alloy product according to claim 1 , wherein the product is in the form of a sheet, plate, forging or extrusion.
20 . 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.
21 . 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.
22 . 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.
23 . Aluminium alloy product according to claim 1 , wherein the product has a thickness of less than 1.5 inch.
24 . Aluminium alloy product according to claim 35 , wherein the product has a thickness of less than 1.0 inch.
25 . Aluminium alloy product according to claim 1 , wherein the product has a thickness of more than 2.5 inch.
26 . Aluminium alloy product according to claim 37 , wherein the product has a thickness in the range of 2.5 to 11 inch.
27 . 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.
28 . 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.
29 . Aluminium alloy product according to claim 1 , wherein the product is in the form of a sheet or plate.
30 . Aluminium alloy product according to claim 1 , wherein the product is in the form of a forging or extrusion.
31 . Aluminium alloy product according to claim 30 , wherein the product has a thickness of more than 2.5 inch.
32 . 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.
33 . 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.
34 . 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.
35 . Aluminium alloy product according to claim 34 , which plate product has an elongation in the ST-testing direction of 5% or more.
36 . Aluminium alloy product according to claim 34 , which plate product has an elongation in the ST-testing direction of 5.5% or more.
37 . 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.
38 . 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.
39 . 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.
40 . Method according to claim 39 , 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.
41 . Method according to claim 39 , wherein during processing step h.) the alloy product has been stretched in a range at most 8%.
42 . Method according to claim 39 , wherein during processing step b) the ingot has been homogenized at a temperature in the range of 460 to 490° C.
43 . Method according to claim 39 , wherein the alloy product has been processed to fuselage sheet.
44 . Method according to claim 43 , wherein the alloy product has been processed to fuselage sheet having a thickness of less than 1.5 inch.
45 . Method according to claim 39 , wherein the alloy product has been processed to lower wing plate.
46 . Method according to claim 39 , wherein the alloy products has been processed to upper wing plate.
47 . Method according to claim 39 , wherein the alloy product has been processed to an extruded product.
48 . Method according to claim 39 , wherein the alloy product has been processed to a forged product.
49 . Method according to claim 39 , wherein the alloy product has been processed to a thin plate having a thickness in the range of 0.7 to 3 inch.
50 . Method according to claim 39 , wherein the alloy product has been processed to a thick plate having a thickness at most 11 inch.
51 . 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 16 ;
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.
52 . Method according to claim 51 , 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.
53 - 123 . (canceled)