Effect of prolonged heating at 130°C on fatigue crack propagation of 2024 Al alloy in three orientations

An Al–Cu alloy 2024 received in T3 condition (cold worked after solutionizing and natural aging) was heated at 130°C for 100 and 1000 h. Fatigue crack growth tests were carried out before and after heating with center cracked tension specimens machined in L–T, T–L and 60° orientations. Fracture surfaces were studied by means of scanning electron microscopy. It was found that the fatigue crack growth rate depends on the test direction in T3 condition. The orientation effect seemed to be lost after prolonged heating at 130°C.