Influence of shock prestraining on the formation of shear localization in 304 stainless steel

Adiabatic shear localization was studied in both annealed (as-received) and shock-prestrained 304 stainless steels (304 SS). A forced shear technique was used to probe the evolution of shear localization under high-strain-rate loading using a compression split-Hopkinson pressure bar (SHPB) and hat-shaped specimens. The shearing responses of the shock-prestrained steel at high strain rate indicate that they exhibit a higher initial yield strength but a lower work-hardening rates than those observed in the annealed steel. The shock-prestrained specimens, having achieved an unstable condition at a smaller plastic displacement and a lower flow stress, were seen to exhibit distinct sharp-edged bands. Corresponding comparisons between the mechanical responses and the deformed microstructures demonstrate that loading-path dependency exerts a strong influence on shear-band formation. The shock-prestrained 304 SS displayed a higher incidence of deformation twins, slip bands, and dislocation debris prior to the shear tests; this substructure suppressed further dislocation storage (work hardening) and thereby facilitated the propensity for shear localization.