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Abstract

The present invention provides an aluminum alloy structural plate excelling in strength and corrosion resistance, in particular, resistance to stress corrosion cracking, and a method of manufacturing the aluminum alloy plate. This aluminum alloy structural plate includes 4.8-7% Zn, 1-3% Mg, 1-2.5% Cu, and 0.05-0.25% Zr, with the remaining portion consisting of Al and impurities, wherein the aluminum alloy structural plate has a structure in which grain boundaries with a ratio of misorientations of 3-10.degree. is 25% or more at the plate surface. The aluminum alloy structural plate is manufactured by: homogenizing an ingot of an aluminum alloy having the above composition; hot rolling the ingot; repeatedly rolling the hot-rolled product at 400-150.degree. C. so that the degree of rolling is 70% or more to produce a plate with a specific thickness, or repeatedly rolling the hot-rolled product at a material temperature of 400-150.degree. C. in a state in which rolls for hot rolling are heated at 40.degree. C. or more so that the degree of rolling is 70% or more to produce a plate material with a specific thickness; subjecting the plate material to a solution heat treatment at 450-500.degree. C. for five minutes or more; and cooling the resulting plate material at a cooling rate of 10.degree. C. or more.

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First Claim