Form This specification covers an aluminum alloy in the form of extruded bars@ rods@ and profiles (shapes) from 0.375 to 1.300 inches (9.53 to 33.02 mm) in diameter or thickness@ produced with cross sectional area of 22.5 in2 (145 cm2) maximum@ and a circumscribing circle diameter (circle size) of 17.4 inches (44.2 cm) maximum. See 8.3 for definition of circumscribing circle size. Application These extrusions have been used typically for machined parts requiring high strength with high toughness@ but usage is not limited to such applications. Certain processing procedures may cause this product to become susceptible to stress-corrosion cracking; ARP823 recommends practices to minimize such conditions.