Al-Zn-Mg-Cu系合金のじん性に及ぼす中間加工熱処理の影響

抄録

RI-ITMT method was applied to improve the toughness of Al-Zn-Mg-Cu alloys. This method is applicable most effectively to the Zr bearing Al-Zn-Mg-Cu alloys, but insufficiently to the Cr bearing alloys. Reduction of impurities Fe and Si is not so effective for toughening the alloys. The size of recrystallized grains in the alloys to which RI-ITMT method has been applied is extremely finer than that of the alloys to which a conventional method has been applied. A relationship lies between transgranular dimple fractured surface ratio and toughness, where transgranular dimple fractured surface expands with toughness. The ratio of this fracture surface type increases with fine transgranular precipitates, because they prevent the formation of rough slip bands in the grain.