Fatigue of materials - Influence of microstructure and processing effect of overaging on fatigue crack propagation of 2024 T3 aluminum alloy

The effect of controlled overaging on fatigue crack propagation (Stage II) in 2024-T3 aluminum alloy was experimentally investigated. Overaging was performed by subjecting the material from initial T3 state to appropriate aging conditions. Fatigue crack growth experiments were conducted to assess the influence of artificial aging on fatigue crack growth resistance. The experimental results showed that overaging enhances the fatigue crack propagation behavior at intermediate Δ? values compared to the T3 state and fatigue crack growth resistance was found to increase with the magnitude of overaging temperature. The reduction of fatigue crack growth rate in the overaged alloy compared to T3 material was associated with crack closure phenomena caused by cyclic plasticity and modification of strain hardening characteristics at the crack path