Effect of anodization and loading on fatigue life of 2618-T851 aluminum alloy.

Anodizing process is largely performed on aluminum alloys to enhance corrosion and wear resistances. However, this process can significantly reduce the fatigue resistance of aluminum alloys depending on the alloy and the process parameters. This paper deals with the influence of anodizing process on fatigue resistance of the aeronautical aluminum alloy 2618-T851. The anodic film has been characterized after each step using scanning electron microscopy (SEM). This analysis showed that the anodic layer was crazed just after impregnation operation with micro-cracks extending from the surface up to half the anodic layer. Simultaneously, uniaxial fatigue tests under tension or torsion loadings have been conducted in order to evaluate the effect of each process step in relation with loading nature. The results showed that the anodizing step has a detrimental effect on fatigue life of 2618 alloy when specimens are subjected to tensile loading. However, anodizing process has no effect on fatigue life under torsion loading. Fractographic observations have been conducted in order to get an insight on the mechanisms involved in each case. [ABSTRACT FROM AUTHOR]