Localization of plastic deformation during high strain rate torsion testing of rolled homogeneous armour

A recently developed technique which allows a study of the localization of plastic flow during high-speed torsion testing is briefly described. High-s peed photographs showing successive stages in the deformation of three roll ed homogeneous armour (RHA) steel specimens are presented. Three stages are identified corresponding to uniform shear, localized shear and the propaga tion of ductile failure. The results are analysed to estimate the condition s under which localization and subsequent ductile fracture are initiated. T he results are compared with a previous study on a soft iron.