Low-Temperature and Corrosion Fatigue Crack-Growth Resistance of D16ATNV and V95T1 Aluminum Alloys after Long-Term Operation

The cyclic crack resistance of D16ATNV (2024-T3 type) and V95T1 (7075-T6 type) degraded aluminum alloys is investigated. The specimens are cut out from different zones of the wing skin of an AN-12 aircraft after 40 yr of its operation along (L-specimens) and across (T-specimens) the direction of rolling of skin sheets. The tests were carried in air at temperatures of 20 and - 60A degrees C and in a corrosive medium (3.5% NaCl solution). It is shown that the effects of low temperature and corrosive medium on the fatigue threshold Delta K (th) and cyclic fracture toughness Delta K (fc) for D16ATNV alloy are qualitatively similar to the effects observed for D16 and V95 aluminum alloys in the as-received state. At the same time, the indicated effects are absolutely different for V95T1 alloy.