Strain Hardening During Hot Compression Through Planar Dislocation and Twin-Like Structure in a Low-Density High-Mn Steel

In this work, we study the flow hardening behavior and microstructural evolution in a low-density Fe-21Mn-0.1C-2.0Al-2.5Si (wt.%) transformation-twinning-induced plasticity steel during hot compression. The substructures were examined by transmission electron microscopy and electron backscatter diffraction methods. The alloy exhibits a combination of strain hardening (at low and medium true compression strains, <0.2) followed by a strain softening at 800 °C. We explain the flow hardening behavior in terms of substructure refinement due to planar dislocation, as well as twin-like structure. The transmission electron microscopy results suggest that short-range ordering triggers slip planarity after straining to 0.05 at 800 °C. Twin-like structure with misorientation angle higher than 20° is formed during further plastic deformation.