Abstract
The influences of small vibratory stresses and the loading axis against grain flow directions on the initiation behavior of stress corrosion cracking (SCC) were investigated in high-strength aluminum alloys sensitive to active path corrosion type SCC. Irrespective of loading direction, the strength of dynamic SCC under a sustained load with small superimposed vibratory stresses (≧59MPa) was considerably lower than that of static SCC under a sustained load, σscc. The static SCC resistance in the TT orientation, where the loading axis is normal to the rolling direction, was superior to that in the LL orientation, where the loading axis is parallel to the rolling direction. Under dynamic loading, on the contrary, the strength in the LL orientation was higher than that in the TT orientation. Static SCC cracks under a sustained load were initiated at grain boundaries, whereas dynamic SCC cracks were initiated at grain boundaries, hydrogen-induced {111} plain cleavages, and transgranular sites associated with corrosion fatigue.
