Microstructural stages of Intermetallic fracture during sheared deformation of AA6082 sheet

Abstract

Abstract Detailed high-resolution quantitative microstructural investigations were performed on AA6082(T6) sheets. The progressive deformations of a shear band formation were studied to understand the fracture mechanism in blanking process. The fracture characteristics of the alloys can be dictated by the intermetallic particles. Damage evolution of this alloy is quantitatively characterized as a function of strain. Intermetallic particles trigger the fracture in the blanking process. 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 the crack nucleus for matrix cracking and coalescences. Particle fracture increases with increase in imposed strain. For initial deformation stages, fragmentation of particles is taking place without significant void growth. But with subsequent deformation stages, fragmentation process has been enhanced with multi-fragmentation and re-fracturing of previously broken particles. Most probably, larger particles nucleate voids at much lower strains than smaller particles, and void growth takes place more rapidly at larger particles and they are the major contributors in the initiation of fracture throughout the deformation process. Crack has initiated in the shear band preferably from the punch side (punch side is sharper than the die side) and the cracks are found almost parallel to the loading axis.