Morphology of multiscale defect structures and plastic strain localization during impact perforation of A6061 alloy targets

Mechanisms of plastic strain localization (PSL) and fracture localization (FL) during dynamic (impact) loading accompanied by “plug” formation are related to structural transitions in the ensemble of defects. A characteristic feature of these transitions in the A6061 alloy is the multiscale character of the resulting structures. It is established that two bands featuring multiscale invariance can exist, namely, the PSL and FL bands, the lengths of which depend on the impact velocity. The length of a deformed layer, in which strain is localized, has a clear tendency of growing toward the free surface of the target. The passage from the PSL to FL band is characterized by a sharp increase in the Hurst exponent.