Effect of aging and overhanging on fatigue behavior of 2024-T3 and 7075-T6 aluminum alloys

The object of this study was to investigate the low temperature long time aging effect of 2024-T3 and 7075-T6 on the fatigue life of the CT-114 tutor aircraft.; The alloys were artificially reaged. Mechanical properties of yield strength and ductility, material properties of hardness and electrical conductivity were measured and related to the changes in fracture toughness and microstructure as altered by the various aging conditions.; Major changes in the material and mechanical properties behavior of 7075-T6 took place at the reaging condition of 175{dollar}spcirc{dollar}C for 38 hours. Similar changes in 2024-T3 alloy took place at the reaging condition of 175{dollar}spcirc{dollar}C for 150 hours.; Both 2024-T3 and 7075-T6 have complex fatigue life behaviors. Initially the fatigue life of each alloy increases to peakaged condition and thereafter decreases continuously. However, highly overaged 2024-T3 alloy provides an overall improved fatigue life. When compared to their original material, both alloys provide better fatigue life at least up to 300 accumulated fours of operations at 175{dollar}spcirc{dollar}C.