Form: This specification covers an aluminium alloy on the form of rolled or forged rings. Application: Primarily for structural applications requiring material with moderate strength and excellent resistance to stress-corrosion cracking and where good stability is required during machining. Alloy is further characterized by excellent fusion weldability. Classification: The rings covered by this specification are classified by type of mechanical stress relief as follows: Type 1 - Stress relieved by stretching (6061-T651) Type 2 - Stress relieved by compression (6061-T652) Either type may be supplied@ unless a specific type is ordered.