Aluminum alloy product having good combinations of mechanical and corrosion resistance properties and formability and process for producing such product

摘要

An improved high strength aluminum alloy product having good combinations of strength, toughness, corrosion resistance and the ability to be subjected in sheet or strip form to roll forming or shaping operations to produce elongate stringer or other aerospace structural reinforcing members. The alloy consists essentially of about 7.6 to 8.4% zinc, about 1.8 to 2.2% magnesium, about 2 to 2.6% copper and at least one element selected from zirconium, vanadium and hafnium present in a total amount not exceeding about 0.5%, preferably about 0.05 to 0.25% zirconium, the balance aluminum and incidental elements and impurities. The improved strip is preferably produced by homogenizing, hot rolling and thermally treating or annealing at about 750° to 850° F. , preferably around 800° F., followed by cold rolling to a reduction in thickness of between about 20 and 50 or 60%, preferably in the neighborhood of about 25 to 35% which, in turn, is followed by a two- stage thermal annealing treatment including heating, preferably within about 650° to about 700° F. followed by controlled cooling or ramping down to one or more temperatures within preferably around 425. degree. to 475° F. The sheet or strip so produced can be taper rolled to vary the thickness along the length of the strip which, following such taper rolling, if employed, is preferably solution heat treated and quenched, straightened, roll shaped in a plurality of roll shaping operations to produce a structural shape cross section which is then artificially aged to develop the desired properties for the aerospace application.