Mechanical Properties, Fracture Toughness, Fatigue, Environmental Fatigue Crack Growth Rates and Corrosion Characteristics of High-Toughness Aluminum Alloy Forgings, Sheet and Plate

Abstract : The mechanical properties, including toughness and fatigue, fatigue crack growth rates and corrosion characteristics have been determined for a total of 56 lots of 7049-T73 and 7175-T736 forgings, 7475-T61 and T761 sheet, and 2124-T851 plate. Supplemental data for bare and Alclad 7475 sheet and 2124- T851 plate are also presented. Tables of computed design mechanical properties and typical stress-strain and compressive tangent modulus curves were prepared. The rates of fatigue crack propagation of these products generally do not vary significantly with specimen orientation. Humid and salt fog environments increased the rate of fatigue crack propagation for most specimens. Propagation is slower in 2124-T851 plate than for 2024-T851 plate but rates for sheet alloys 7475-T61, 7475-T761 and Alclad 7475-T61 are essentially equivalent as are rates for 7175-T736 and 7075-T7352 hand forgings. The 7175-T736 forgings, 7475-T761 sheet and 2124-T851 plate have a high resistance to exfoliation while the 7049- T73 forging an the 7475-T61 sheet show some susceptibility to exfoliation. All of the materials are resistant to stress corrosion exfoliation. All of the materials are resistant to stress corrosion cracking when stressed in the longitudinal and long-transverse grain direction. The resistance to SCC in the short-transverse direction of all the materials is representative of the respective alloys and tempers.