Multiple recrystallization mechanisms of adiabatic shear bands: Observations via electromagnetic force-induced wide-range transition zones

Abstract

Over the past decades, the formation mechanisms of adiabatic shear bands under dynamic loading have attracted wide coverage from researchers. This study introduces a novel approach focusing on the transition zones at ASB edge rather than their fully recrystallized center to advance current understanding. These regions can be regarded as transitional stages within the unaccomplished dynamic recrystallization process, thereby demonstrating the accurate evolution. Using electromagnetic riveting processing of commercial 2A10 Al-Cu alloy, we generated ASB (>130 μm) with distinguishable edge regions exceeding 10 μm in width. Through microstructure characterization under focused ion beam and kinetic analysis, the direct microscopic evidence of rotational dynamic recrystallization and additional recrystallization mechanisms activated alongside rotational dynamic recrystallization were discovered. The results demonstrate the sequential mechanisms: rotational dynamic recrystallization initiates firstly during deformation, producing ultrafine grains at ASB centers; discontinuous dynamic recrystallization subsequently emerges with localized temperature elevation; continuous dynamic recrystallization requires a longer duration than the deformation process itself, classified as incomplete recrystallization.