ジコウ コウカ AL 12MASS% ZN ゴウキン ノ ヒロウ キョウド ニ オヨボス フクゲン ショリ ノ エイキョウ

Effect of reversion treatment on the fatigue strength of age hardened Al-12mass% Zn alloy was studied by measurements of Vickers micro-hardness and number of cycles to failure under repeated tensile loading. The results obtained are summarized as follows. 1) Rate of reversion was faster in the surface layer than in the interior when the age hardened specimen annealed at 353K. That is, soft surface layer was formed, again. 2) In this case, the presence of soft surface layer strengthens fatigue resistance of the age hardened Al-12mass%Zn alloy