Revealing the Dynamic Recrystallization Mechanism and Hot Workability of Fe–0.15C–10Mn Medium‐Mn Steel through Grain Size Distribution and 3D Processing Maps

An in‐depth understanding of thermal deformation of medium‐Mn steels (MMnSs) is crucial for the forming fabrication of key automotive components. In this work, the Fe–0.15C–10Mn MMnSs are compressed under conditions of 900–1150 °C/0.001–10 s −1 . Two‐stage models, dynamic recovery (DRV) and dynamic recrystallization (DRX), are constructed and proved to be accurately predictive with a correlation coefficient ( R ) of 0.997% and average absolute relative error (AARE) of 2.67%. Based on the analysis of microstructure evolution, the discontinuous DRX occured at a specific deformation condition of 900 °C–10 s −1 , while the continuous DRX generated at other deformed conditions. The discontinuous DRX grains only distributed along pre‐existing grain boundaries, showing a necklace‐like grain structure with multiple small zigzag protrusions at the boundary. While continuous DRX grains with low dislocation density distributed both along and inside the pre‐existing grain boundaries. The developed 3D processing map identified high strain rate (0.1–10 s −1 ) as instability domains, in which heterogeneous microstructure are observed. Consequently, optimum hot working domain is determined to be 975–1150 °C/0.001–0.05 s −1 . Complete DRX and subsequent growth of small DRXed grains result in a homogeneous microstructure, contributing to the optimal processing zone with η > 0.29.