Abstract: In this paper, the experiment of a series of plain strain mixed mode ductile fractureis carried out in two kinds of ductile materials (quenChed aluminum alloy LY12-CZ and annealedaluminum alloy LY12-M). The microscopic characteristic behavior of deformation and the initiationof blunted crack tip is investigated by using SEM near the area ahead of the blunted crack tip inthe middle thickness profile at the critical range of crack initiation. The adaptability of ductilefracture parameter--void growth ratio is...