Form This specification covers an aluminum alloy in the form of die forgings up to 4 inches@ incl (102 mm@ incl) in thickness@ and hand forgings up to 6 inches@ incl (152 mm@ incl) in thickness (see 8.6). Application These forgings have been used typically for parts requiring a combination of good strength and resistance to stresscorrosion cracking@ and where good stability is required during machining@ but usage is not limited to such applications.