The fatigue strength of low temperature age-hardened Al-2mass%Cu alloy

Abstract

Fatigue strength of an age hardened and reversion annealed Al-2mass%Cu alloy was examined by a repeated tension fatigue test. The fatigue strength of the specimen fully aged around room temperature after quenching from 823 K did not depend on whether the soft surface layer was present or not, but the specimen aged after quenching from 723 K, which had a thicker soft surface layer, showed higher strength than the specimen without soft surface layer. Fatigue strength of the specimen of which the soft surface was removed, however, was independent of quenching temperature. Reversion annealing for 600 s at 323 K after aging, which made the soft surface layer thicker, increased the fatigue strength. It is concluded from these results that the formation of the soft surface layer in the present alloy can increase fatigue strength in repeated tensile test, as in the case of the Al-Zn alloy.