High-speed blanking of AA5754 and 22MnB5: In-situ optical insights into localized shear deformation and elastic rebound effects

High-speed blanking (HSB) offers considerable potential for producing high-quality cut surfaces by controlling the formation of adiabatic shear bands (ASBs). The enclosed geometry of conventional tooling prevents direct observation of dynamic localization processes. This study utilizes a novel, optically accessible tool design that enables in-situ, high-speed imaging combined with digital image correlation (DIC) to investigate local shear deformation during HSB. The tooling is numerically validated by comparison with a conventional closed setup and used during HSB at different impact energy levels with two sheet materials: the aluminum alloy AA5754 and the press-hardened martensitic steel 22MnB5. We document distinct material-dependent localization mechanisms during HSB. AA5754 exhibits gradual shear localization closely coupled to punch kinematics, with shear deformation distributed over a comparatively wide zone and estimated peak shear rates in the range of 4.6–6.1·10 4 s -1 . In contrast, 22MnB5 shows delayed but distinct localization, with a pronounced elastic rebound effect of the tool, which significantly amplifies plastic instability. During unloading, local velocities exceed nominal striker speeds by a factor of about three. Post-mortem microstructural investigations confirm the formation of narrow ASBs with widths of only a few micrometers. By combining local velocities from DIC with microstructure-based measurements of the deformation zone, we estimate instantaneous shear rates within ASBs up to ~3.6·10 6 s -1 during the final stages of plastic instability. Our methodology provides time-resolved insights into the kinematics of localized shear deformation. The findings contribute to the understanding of ASB formation during HSB and can support the targeted design of advanced blanking tools.