This specification covers an aluminum alloy in the form of die forgings not over 4 inches (102 mm) in nominal thickness at time of heat treatment , hand forgings with as-forged thickness not exceeding 8 inches (203 mm) and the cross-sectional area not greater than 256 square inches (1652 cm²), forged or rolled rings 3.5 inches (89 mm) and under in nominal thickness at time of heat treatment and having an OD-to-wall thickness ratio of 10:1 or greater, and stock of any size for forgings and rings (see 8.6).