Influence of Thermal Conditions on the Fatigue Performance of AA2024-T4 Alloy: A Comprehensive Investigation

Aluminum alloys AA2024-T4 are used in the manufacture of aircraft structures and essential parts of transportation. During the operation of these parts for long periods, at high temperatures, and under the influence of constant or variable loads. This work focused on studying the temperature holding time (THT) effects on the mechanical and fatigue performance of AA2024-T4. Three (THT), 10 min, 20min, and 30 min effects on both mechanical and fatigue properties are discussed. The applied temperature was 150C°. The UTS, YS, E, and HB decreased when (THT) increased, except that ductility increased. The reduction in mechanical properties was recorded to be 18.64%, 14.28%, 9.58% and 14.52% compared to the (RT) results without (THT), respectively. Also, increasing the (THT) leads to reducing the fatigue life for both constant and variable loading. For continuous amplitude loading, the fatigue strength at 107 cycles was reduced from 86.24 MPa at 150 °C with 30 min. (THT). Also, the fatigue life at variable loading (180-250-200 MPa) was recorded to be 42800 cycles at RT without (THT). Moreover, at (200-180-250 MPa), the fatigue life reduced from 28133 cycles to 12533 cycles for the same condition above. Therefore, it was concluded that increasing the temperature by 30 minutes (THT) leads to a decrease in fatigue life when using constant and variable loading. The experimental results of fatigue life were compared with the Miner rule to estimate fatigue life at variable loads, and it was remarked that the Miner rule is not suitable for estimating fatigue life for this purpose.