Hot Deformation and Dynamic Recrystallization of 18%Mn Twinning‐Induced Plasticity Steels

The deformation behavior of 18%Mn twinning‐induced plasticity (TWIP) steels with 0.4%C or 0.6%C is studied by means of isothermal compression tests in the temperature range of 973–1373 K at the strain rates of 10⁻³–10⁻¹ s⁻¹. The hot working is accompanied by the development of discontinuous dynamic recrystallization (DRX), which is commonly advanced by an increase in deformation temperature and/or a decrease in strain rate. A decrease in the carbon content promotes the DRX development, though the flow stresses scarcely depend on the carbon content. The change in the DRX kinetics results in the specific distributions of the grain orientation spread (GOS) among the DRX grains, depending on deformation conditions. The maximal fraction of grains with small GOS below 1° corresponding to rapid DRX development is observed at certain temperature/strain rate, although the DRX fraction increases with a decrease in temperature‐compensated strain rate and can be related to the fraction of grains with GOS below 4°. The texture of DRX grains is also determined by the orientations of grains with GOS below 4°. The grain boundary mobility for the DRX grain growth is characterized by an activation energy close to that for grain boundary diffusion.