Microstructural stages of intermetallic fracture during sheared deformation of AA6082 sheet

Abstract

The progressive deformations of a shear band formation were studied to understand the fracture mechanism of AA6082(T6) sheets. The fracture characteristics of the alloys can be dictated by the intermetallic particles. Damage evolution of the alloy is quantitatively characterized as a function of strain. Larger, elongated, and favorably oriented particles fracture first (with initial deformation), and with progressive deformation (blanking), smaller and rounded particles start breaking. These broken particles become a crack nucleus for matrix cracking and coalescences. In the initial deformation stages, fragmentation of particles takes place without significant void growth. However, with subsequent deformation stages, the fragmentation process has been enhanced with multi-fragmentation and re-fracturing of previously broken particles. Larger particles nucleate voids at much lower strains with void growth. Crack has initiated in the shear band, preferably from the punch side (the punch side is sharper than the die side), and cracks are found almost parallel to the loading axis.