Form This specification covers an aluminum alloy in the form of sheet and plate from .008 to 2.000 inches@ incl (0.20 to 50.80 mm@ incl) in thickness@ supplied in the annealed (O) condition (see 8.4). Application These products have been used typically for formed structural parts which will be subsequently heat treated@ but usage is not limited to such applications. Certain design and processing procedures may cause these products to become susceptible to stress-corrosion cracking after heat treatment; ARP823 recommends practices to minimize such conditions.