Gradient structure produces superior dynamic shear properties

We report that gradient-structured twinning-induced plasticity steels have much superior dynamic shear properties over homogeneous nanostructured (NS) counterparts. The gradient structure was found to delay the nucleation of adiabatic shear bands (ASBs) at the NS surface layers and to reduce the propagation speed of ASB by an order of magnitude as compared with homogeneous NS materials. The conventional maximum stress criterion on ASB initiation for homogeneous materials is found not valid for gradient structure. These findings may provide insights for designing impact-tolerant gradient structures with excellent dynamic properties. [GRAPHICS] IMPACT STATEMENT Gradient structures were found to produce superior dynamic shear properties that are not accessible to their homogeneous counterparts due to the suppression of nucleation and propagation of adiabatic shear bands.