Microfractographic characteristics and fracture toughness of 7000 and 2000 series aluminium alloys: proposal of a static fracture model

Abstract

The results of SEM examinations performed on fracture surfaces of CT test pieces used for determining the toughness index K_IC of five high strength aluminium alloys of 7000 and 2000 series, were correlated with the fracture toughness data obtained on such alloys. A relation was formulated, in a form suggested by fracture mechanics, which links the average width of the stretched zone of the five alloys with their K_IC values. Moreover, a static fracture model was proposed, which reasonably explains the micromechanisms underlaying the formation of the cliff, that is the sharp discontinuity (step) joining the stretched zone to the overload fracture region.