Al—Mg—Zn wrought alloy product and method of its manufacture
View Patent ↗An aluminum alloy wrought product including, in wt. %, Mg 3.0 to 7.0, Zn 0.6 to 2.8, Mn 0 to 1.0, Cu 0 to 2.0, Sc 0 to 0.6, at least one element selected from the group of Zr 0.04 to 0.4, Cr 0.04 to 0.4, Hf 0.04 to 0.4 and Ti 0.01 to 0.3; Fe maximum 0.3, Si maximum 0.3, inevitable impurities, and balance aluminum. The range for the Zn-content in wt. % is a function of the Mg-content according to: lower-limit of the Zn-range: [Zn]=0.34[Mg]−0.4, and upper-limit of the Zn-range: [Zn]=0.34[Mg]+0.4.
1. Method of manufacturing aluminum wrought product comprising the steps of:
a. casting stock of an ingot of an Al—Mg alloy having a chemical composition comprising, in wt. %,
Mg
3.0 to 7.0
Zn
0.6 to 2.8
Mn
0 to 1.0
Cu
0 to 2.0
Sc
0 to 0.5,
at least one element selected from the group consisting of:
Zr
0.04 to 0.4
Cr
0.04 to 0.4
Hf
0.04 to 0.4 and
Ti
0.01 to 0.3,
Fe
max. 0.3
Si
max. 0.3,
inevitable impurities, balance aluminium, and whereby the range for the Zn-content is a function of the Mg-content according to:
lower-limit of the Zn-range: [Zn]=0.34[Mg]−0.4, and
upper-limit of the Zn-range: [Zn]=0.34[Mg]+0.4, and
wherein the aluminium alloy product is substantially Li free;
b. preheating and/or homogenising the cast stock;
c. hot working the stock by one or more methods selected from the group consisting of rolling, extrusion, and forging;
d. annealing of the hot worked stock, wherein the annealing treatment is carried out at a temperature in a range of 350° C. to 475° C., followed by rapid cooling;
e. cold working the annealed and cooled stock;
f. stretching the cold worked stock in a range of 0.5 to 10%;
h. heat treating of the stock to achieve a desired temper.
2. Method according to claim 1 , wherein during step d.) the heat treatment is carried out for an annealing time of up to 2 hours.
3. Method according to claim 1 during step d.) the heat treatment is carried out for an annealing time up to 5 hours.
4. Method according to claim 1 , wherein the product has an unrecrystallised microstructure.
5. Method according to claim 1 , wherein the product is a structural member of an aircraft.
6. Method according to claim 1 , wherein the product is armour plate.
7. Method according to claim 1 , wherein the product is moulding plate.
8. Method according to claim 1 , wherein the aluminum alloy product has a Mg-content in a range of 3.0 to 5.0%.
9. Method according to claim 1 , wherein the aluminum alloy product has a Mg-content in a range of 4.0 to 5.0%.
10. Method according to claim 1 , wherein the aluminum alloy product has a Mg-content in a range of 4.2% to 4.9%.
11. Method according to claim 1 , wherein the aluminum alloy product has a Sc addition combined with an addition of Zr in a range of 0.04 to 0.4%.
12. Method according to claim 1 , wherein the aluminium alloy product has a Sc addition combined with an addition of Zr in a range of 0.06 to 0.15%.
13. Method according to claim 1 , wherein the aluminium alloy has a Cu-content in a range of 0 to 0.1%.
14. Method according to claim 1 , wherein the aluminium alloy has a Cu-content in a range of 0 to 0.05%.
15. Method according to claim 1 , wherein the aluminium alloy has a Cu-content is in a range of 0.1 to 1.5%.
16. Method according to claim 1 , wherein the aluminium alloy has a MnO-content of <0.1%.
17. Method according to claim 1 , wherein the aluminium alloy has a MnO-content of <0.05%.
18. Method according to claim 1 , wherein the aluminium alloy has a composition consisting of, in wt. %:
Mg
4.0 to 5.0
Zn
0.96 to 2.1
Mn
<0.1
Cu
0 to 2.0
Sc
0 to 0.05
Zr
0.04 to 0.4
optionally one or more element selected from the group consisting of:
Cr
0.04 to 0.4
Hf
0.04 to 0.4 and
Ti
0.01 to 0.3,
Fe
max. 0.15
Si
max. 0.15,
balance inevitable impurities each <0.05, total <0.25, balance aluminium, and whereby the range for the Zn-content is a function of the Mg-content according to:
lower-limit of the Zn-range: [Zn]=0.34[Mg]−0.4, and
upper-limit of the Zn-range: [Zn]=0.34[Mg]+0.4.
19. Method according to claim 1 , wherein the aluminium alloy product has a composition consisting of, in wt. %:
Mg
4.0 to 5.0
Zn
0.96 to 2.1
Mn
0.1 to 1.0
Cu
0 to 2.0
Sc
0.05 to 0.05
Zr
0.04 to 0.4
optionally one or more element selected from the group consisting of:
Cr
0.04 to 0.4
Hf
0.04 to 0.4 and
Ti
0.01 to 0.3,
Fe
max. 0.15
Si
max. 0.15,
balance inevitable impurities each <0.05, total <0.25, balance aluminium, and whereby the range for the Zn-content is a function of the Mg-content according to:
lower-limit of the Zn-range: [Zn]=0.34[Mg]−0.4, and
upper-limit of the Zn-range: [Zn]=0.34[Mg]+0.4.
20. Method according to claim 1 , wherein the annealing of step d.) forms Al 3 Sc dispersoids.
21. Method according to claim 20 , wherein Zr is present and the Zr stabilizes the Al 3 Sc dispersoids.
22. Method according to claim 1 , wherein the aluminium alloy has a composition consisting of, in wt. %:
Mg
3.0 to 7.0
Zn
0.6 to 2.8
Mn
0 to 0.1
Cu
0 to 2.0
at least one element selected from the group consisting of:
Zr
0.04 to 0.4
Cr
0.04 to 0.4
Hf
0.04 to 0.4 and
Ti
0.01 to 0.3,
Fe
max. 0.3
Si
max. 0.3,
inevitable impurities, balance aluminium, and whereby the range for the Zn-content is a function of the Mg-content according to:
lower-limit of the Zn-range: [Zn]=0.34[Mg]−0.4, and
upper-limit of the Zn-range: [Zn]=0.34[Mg]+0.4.
23. Method according to claim 1 , wherein 30% or less of grains of the alloy in final condition are non-recrystallized.
24. Method according to claim 1 , wherein 15% or less of grains of the alloy in final condition are non-recrystallized.
25. Method according to claim 1 , wherein the heat treating of the stock to achieve the desired temper comprises a heat treatment carried out at a temperature in a range of about 100° C. to 210° C. in one or more heat treatment steps.
26. Method according to claim 25 , wherein the heat treating of the stock to achieve the desired temper comprises a first heat treatment carried out at a temperature in a range of about 105° C. to 135° C., for at least 30 minutes.
27. Method according to claim 26 , wherein the heat treating of the stock to achieve the desired temper further comprises a second heat treatment following the first heat treatment, the second heat treatment carried out at a temperature in a range of 135° C. to 210° C. for at least 4 hours.
28. Method according to claim 1 , wherein the heat treating of the stock to achieve the desired temper further comprises a third heat treatment following the second heat treatment, the third heat treatment at a temperature of about 105° C. to 145° C. for up to about 30 hours.
29. Method according to claim 1 , wherein the rapid cooling is performed by one of spray quenching or immersion quenching in water.
30. Method according to claim 1 , wherein the cold working comprises two or more sequential cold working operations, further comprising applying one or more intermediate annealing treatments to the stock between said cold working operations, wherein the intermediate annealed stock is rapidly cooled from the intermediate annealing temperature at least after the intermediate annealing prior to the last cold working operation.
31. Method according to claim 30 , wherein the cold working comprises cold rolling the stock and stretching the stock, wherein the cold rolled stock is stretched 0.5 to 10%, wherein following the cold rolling the cold rolled stock is intermediate annealed, and then the intermediate annealed stock is rapidly cooled from the intermediate annealing temperature, and then the intermediate annealed rapidly cooled stock undergoes said stretching.
32. Method according to claim 22 , wherein the cold working comprises cold rolling the stock and stretching the stock,
wherein the cold rolled stock is stretched 0.5 to 10%, wherein following the cold rolling the cold rolled stock is intermediate annealed, and then the intermediate annealed stock is rapidly cooled from the intermediate annealing temperature, and then the intermediate annealed rapidly cooled stock undergoes said stretching,
wherein the heat treating of the stock to achieve the desired temper comprises a first heat treatment carried out at a temperature in a range of about 105° C. to 135° C., for at least 30 minutes,
wherein the heat treating of the stock to achieve the desired temper further comprises a second heat treatment following the first heat treatment, the second heat treatment carried out at a temperature in a range of 135° C. to 210° C. for at least 4 hours.
33. Method according to claim 1 , wherein the aluminium alloy Cu-content is in a range of 0.2 to 1.2 wt. %.