Fatigue of aluminium alloy 2024-T351 in humid and dry air

Reversed bending fatigue tests conducted on specimens of aluminium alloy 2024-T351 in dry and humid air at stress levels of 248, 276, 290, 317 and 359 MPa showed that at low stress amplitude humid air reduces the fatigue life by as much as 21%. Mirco-hardness tests showed that the reduction in fatigue life is primarily attributed to localized hydrogen-induced overageing. SEM analysis and microhardness data were combined with past studies to propose a mechanism for environmentally induced fatigue in aluminium alloy 2024-T351 over a wide range of stress levels.