Form This specification covers an aluminum alloy in the form of sheet and plate from 0.010 to 0.499 inch (0.25 to 12.67 mm)@ inclusive@ in thickness (see 8.4). Application This product has been used typically for structural components@ including machine tapered parts@ 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.