EFFECTS OF THE AGING CONDITION AND IMPACT VELOCITY ON THE TENSILE DUCTILITY OF Al-Cu AND Al-Ag ALLOYS.

Abstract

Static and impact tension tests were carried out in order to investigate the effects of the aging condition and deformation speed on the elongation percentage and reduction of area in Al-4. 0% Cu and Al-12. 6% Ag alloys which were aged at various stages. With increasing impact velocity, the ductility generally increases in a well-known manner, and the dimples formed on the fracture surface are enlarged in mean size. 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. 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.