A study of the impact deformation and fracture behaviour of austenitic manganese steel

This study uses the split-Hopkinson pressure bar to investigate the impact deformation and fracture behaviour of austenitic manganese steel at strain rates ranging from 2.0 × 10³ s^-1 to 8.0 × 10 ³ s^-1 at room temperature. The experimental results indicate that strain rate exerts a significant influence on the mechanical properties of austenitic manganese steel. With an increasing strain rate, the impact flow stress, work hardening rate, and strain rate sensitivity increase, while the activation volume decreases. The variations of strain rate sensitivity and activation volume are closely related to the work hardening stress. The results of this study show that the observed flow behaviour is described accurately by the Zerilli-Armstrong constitutive law. Fractographic analysis reveals that the specimen fracture is dominated by the formation of an adiabatic shear band formation. Furthermore, dimple characteristics and cleavage facets are observed on the fracture surface, indicating a relatively ductile fracture mode. The cleavage fracture is found to be associated with the increasing strain rate, which gives rise to a loss of deformability.