LAUSR

The thermal deformation behavior and microstructure evolution of medium Mn steel (0.15C–7Mn) are investigated by the two‐hit compression tests. The results reveal that different static softening dynamics are the functions of deformation temperature, interval time, and strain rate. The short static softening plateaus are exhibited in the static softening curves during post‐deformation holding at 950 °C and 0.1, 1 s−1. Based on the electron backscatter diffraction (EBSD) analysis, the progresses of static recovery (SRV) and static recrystallization (SRX) are enhanced by the increment of deformation temperature. The frequencies of medium angle boundaries (MAGBs) and high angle boundaries (HAGBs) increase gradually with an increased interval time at 1000 °C and 0.1 s−1, which suggests that both SRV and SRX contribute to static softening, but the predominant softening mechanism is SRV. In addition, the influence of temperature, interval time, and strain rate on the distribution and average magnitude of grain size is investigated. The deformation temperature and strain rate have a significant influence not only on average grain dimension, but also on the distribution of grain size. Interval time has great influence on average grain size, but has slight effect on distribution of grain size.