Abstract
In this paper, ductile fracture loci formulated in the space of the effective plastic strain to fracture and the stress triaxiality for a cast aluminum alloy A356 and a low pressure die cast aluminum alloy were obtained using a combined experimental-numerical approach. A total of 12 tests were conducted including 6 tensile tests on notched and unnotched round bars and 6 biaxial loading tests on flat butterfly specimens in each material. Corresponding finite element analysis was performed to determine the evolution of stress and strain states. It was found that the material ductility strongly depends on the stress triaxiality for both present cast alloys. In addition, the material ductility of A356 was larger than that of low pressure die cast alloy. Meanwhile, the fractographic study reveals that many small voids nucleated uniformly in A356 although the low pressure die cast alloy showed the randomly distributed large voids at the high stress triaxiality. The smooth shear fracture surface was obtained in A356 while both many voids and small shear fracture surfaces were observed in the low pressure die cast alloy.
