Quasi-in-situ observations of crack propagation and microstructure evolution of high manganese austenitic steel at −196 °C

Abstract

The crack propagation behaviors and microstructure characteristics in the high manganese austenitic steel were comprehensively investigated by quasi-in-situ observations at −196 °C. The steel exhibits a superior fracture toughness at −196 °C than at room temperature. It is found that a severe plastic deformation is necessary for a crack initiation. Although the main crack propagates along the {111} planes due to the plastic strain localization caused by an extensive planar slip, the steel still possesses a superior crack propagation resistance, which is attributed to the activations of multiple twinning and slipping systems, which provide two positive effects on blocking a crack propagation: (1) the plastic deformation further enhanced by multiple twinning and slipping systems as well as (2) a tortuous crack propagation path caused by numerous twin boundaries. Besides, the pronounced deflections at grain boundaries also have a large contribution to block a crack propagation.