Wear Behavior Dominated by Strain Partitioning Between Retained Austenite and α-Fe in Bainitic Steel

The strains in α-Fe (bainite) and retained austenite (RA) exhibit an apparent discrepancy during deformation, namely strain partitioning, which can determine the tensile behavior of bainitic steels. Due to the involvement of plastic deformation and strain accumulation in the wear process, the strain partitioning phenomenon must be considered in the study of wear mechanisms. The impact wear tests results indicated that the wear behavior was strongly affected by strain partitioning between α-Fe and RA, and the initial hardness and work-hardening rate were not the main factors determining the wear resistance. The strain partitioning is closely related to the RA morphology tailored by isothermal processes, which was proved by in situ tensile test. The strain discrepancy between the continuous thin-film RA and α-Fe was shown to be less significant. A smaller strain discrepancy alleviated stress concentration and minimized the occurrence of cracks and material spalling during wear. The strain discrepancy between blocky RA and α-Fe was shown to be greater. The high-strain in blocky RA promoted the strain-induced transformation (SIT) effect and increased the work-hardening rate; however, it led to strain concentration on the worn surface and accelerated surface spalling.