The ratchetting and retained austenite transformation of medium‐manganese transformation‐induced plasticity steel during asymmetrical cyclic stressing

Abstract The uniaxial ratchetting behavior and cyclic softening/hardening characteristics of Fe‐0.4C‐7Mn‐3.2Al steel are revealed by cyclic loading experiments. Electron backscattered diffraction (EBSD) and X‐ray diffraction (XRD) analyses have been carried out for assessing retained austenite (RA) transformation during cyclic deformation. Fe‐0.4C‐7Mn‐3.2Al steel exhibits a gradual transition from cyclic stabilization to slight cyclic hardening with increasing strain amplitude. RA transformation is one of the reasons for cyclic hardening. The ratchetting of Fe‐0.4C‐7Mn‐3.2Al steel shows two different characteristics under asymmetrical cyclic stressing. When the stress amplitude is below a certain value, the ratchetting is similar to that of typical cyclic stabilized materials in three stages of deceleration, stabilization and acceleration. However, when the stress amplitude reaches a certain level, the ratchetting evolution accelerates from the beginning to the fracture. The results show that the interaction between transformation‐induced plasticity and ratchetting strain can lead to accelerated accumulation of plastic strain.