Effect of stress triaxiality on fracture behavior of 2091 aluminum alloys

Abstract

The toughness of Al-Li system alloy increases in general with lowering temperature. The mechanism of the toughness increase at low temperature has not been, however, clearly defined yet. In this study, the relationship between formation of laminated cracks and stress triaxiality are investigated on 2091 Al-Li system alloys. The number of laminated cracks increases with rising stress triaxiality. The dynamic fracture toughness value J_d increases at 77 K and exhibits greater value at a thickness, B, of 1mm. The increasing ratio at 77 K in fracture toughness of specimens with laminated cracks is much greater than that of specimens without laminated cracks. The laminated cracks will lead to the stress relaxation at the main crack tip increase the fracture toughness.