Effects of the Aging Condition and Impact Velocity on the Tensile Ductility of Al-Cu and Al-Ag Alloys

Static and Impact tension tests have been carried out in order to investigate the effects of the aging condition and the deformation speed on the elongation per cent and reduction of area of Al-4.0%Cu and Al-12.6%Ag alloys which aged in the various stages. The results obtained are as follows: (1) With increasing impact velocity, the ductility generally increases in a well-known manner and the dimples formed on the fracture surface is enlarged in mean size. (2) As-quenched specimens and those in the incipient stages of aging have a small amount of precipitates which are the source of void formation. Accordingly, the ductility of these alloys was often decreased by impact tension owing to slipping-off fracture or grain boundary brittle fracture. (3) Grain boundary ductile fracture takes place in the static tension of fully aged or over-aged alloys by linking voids formed around grain boundary precipitates. In the impact tension, however, transgranular fracture occurs with the resulting excellent reduction in area.