Fracture behaviour of 2195-T8 aluminium alloy plates

In this paper, the determination of the fracture toughness of a thin Al-Cu-Li 2195-T8 alloy plate faces to the problems of insufficient thickness constraint and pop-ins coupled with local unstable crack growth. Since crack initiation occurs by crack tip blunting followed by ductile tearing, J(1c) is an advisable alternative to K(1c). The microstructural interpretation of J(1c) values indicates that they depend mainly on the inclusion distribution of the alloy, and that the local interparticle spacing along inclusion rows aligned in the rolling direction is the initiation toughness controlling parameter, irrespective of the crack orientation plane. On the other hand, crack growth toughness, expressed by the tearing modulus T, shows a crack orientation dependence, because the interparticle spacing along inclusion rows determines the T values in TL samples, whereas the spacing between inclusion rows determines the T values in LT samples.