Form This specification covers an aluminum alloy in the form of plate 1.500 inches (38.10 mm) to 6.000 inches (152.40 mm) in nominal thickness (see 8.4). Applications This plate has been used typically for parts requiring a high level of mechanical properties up to 300 ??(149 ??@ but usage is not limited to such applications. Certain design and fabrication procedures may cause plate to become susceptible to stress-corrosion cracking; ARP823 recommends practices to minimize such conditions.