RAPID HIGH TEMPERATURE AGING OF AL-ZN-MG-CU ALLOYS

摘要

Abstract of the DisclosureA method of thermally treating an article composed ofan alloy consisting essentially of aluminum, 4 to 8% zinc, 1.5to 3.5% magnesium, 1 to 2.5% copper, and at least one elementselected from the group consisting of 0.05 to 0.3% chromium, 0.1to 0.5% manganese, and 0.05 to 0.3% zirconium, which methodincludes solution heat treating the article and subsequently sub-jecting the article to a time and temperature effective for increas-ing the resistance to corrosion of the alloy over its resistancein the T6 condition, the time and temperature being from 10 secondsto 10 minutes and from 350 to 520°F, or else 435 to 520°F, respec-tively. An alloy consisting essentially of aluminum, 4 to 8% zinc,1.5 to 3.5% magnesium, 1 to 2.5% copper, and at least one elementselected from the group consisting of 0.05 to 0.3% chromium, 0.1to 0.5% manganese and 0.05 to 0.3% zirconium, having a corrosionresistance increased over that of its T6 condition, with a solutionpotential lying in the range minus 825 to minus 935 millivolts, ayield strength lying in the range 46 to 72 ksi, a dislocation den-sity above that exhibited by aluminum alloy 7075 in the T73 condi-tion, denuded grain boundary regions, and grain boundary precipitate.