Abstract
The effect of temperature and environment (air, humidity and 3.5 wt% NaCl salt spray) on cyclic fatigue life and fracture mechanism on 2524 aluminum alloy was investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and fatiguae property testing. The results showed that temperature has a detrimental influence on cyclic fatigue life. The cyclic fatigue strength n=106 at elevated temperature (100%°C) decreased by 30 MPa compared to that at cryogenic temperature (-55°C). Moreover, temperature also remarkably affected the feature of dislocation, second-phase particles and grain boundary. The fracture surface at cryogenic temperature showed crystallographic morphology. The dominant deformation process at ambient and elevated temperature was a combination of predominantly transgranular and local intercrystalline fracture mechanism. The fractographic features revealed the fatigue crack growth behavior of the alloy in three environments, more brittle striations were observed in humidity air and salt spray. The increased crack growth rate was attributed to a combination of hydrogen embrittlement and anodic dissolution at the tip of crack.
