CORROSION RESISTANT ALUMINUM ALLOYS HAVING HIGH AMOUNTS OF MAGNESIUM AND METHODS OF MAKING THE SAME

1 . A method comprising:

(a) continuously casting an Al—Mg alloy comprising from about 6 wt. % to about 10 wt. % Mg;

(b) hot rolling the Al—Mg alloy to a thickness of less than 6.35 mm;

(c) annealing the Al—Mg alloy via a furnace, wherein the annealing step comprises:

(i) heating the Al—Mg alloy at elevated temperature and for a time sufficient to achieve an O temper; and

(ii) cooling the Al—Mg alloy, wherein, after the cooling step, the Al—Mg alloy comprises a plurality of grains, and wherein the Al—Mg alloy is substantially free of a continuous film of β-phase at the grain boundaries after the Al—Mg alloy has been age sensitized.

2 . The method of claim 1 , wherein after the cooling step (c)(ii), the Al—Mg alloy is free of a continuous film of β-phase.

3 . The method of claim 1 , wherein the heating step (c)(i) comprises:

heating the Al—Mg alloy to a temperature T 1 , wherein T 1 is from about 365° C. to about 500° C., for a period of at least about 2 hours.

4 . The method of claim 3 , wherein the cooling step (c)(ii) comprises:

first cooling the Al—Mg alloy from the temperature T 1 to a temperature T 2 , wherein the temperature T 2 is at least about 25° C. less than the temperature T 1 , and wherein the rate of cooling from temperature T 1 to temperature T 2 is not greater than about 100° C. per hour; and

second cooling the Al—Mg alloy from the temperature T 2 to a temperature T 3 , wherein T 3 is at least about 100° C. less than temperature T 2 .

5 . The method of claim 4 , wherein the cooling rate of the first cooling step is in the range of from about 30° C./hour to about 60° C./hour.

6 . The method of claim 1 , wherein the continuously casting comprises strip casting.

7 . The method of claim 6 , wherein the cooling rate of the second cooling step is at least about 100° C./hour.