| In this study, microstructural influence on the anisotropic fatigue properties of Al-Li 8090 alloy has been investigated in relation to the intrinsic and extrinsic nature. For all three(L-T, T-S and S-T) orientations fatigue resistance of δ` microstructure was higher than that of S`+δ` microstructure, mainly due to the higher levels of crack closure in δ` microstructure. In the early stage of crack growth, fatigue resistance of -T and T-S specimens was considerably higher than that of S-T specimen. lntergranular delamination susceptible to occur in the S-T specimen was found to be responsible for the highest crack growth rate. However, overall fatigue properties of T-S specimen were estimated to be poor due to the frequent catastrophic fracture occurring in the direction of vertical intergranular boundaries. Fatigue resistance of S-T specimen was not largely affected by the introduction of S` phase in the δ` microstructure. |
|
