Influence of asymmetric hot rolling on through-thickness microstructure gradient of Fe-20Mn-4Al-0.3C non-magnetic steel

Through-thickness microstructure gradient as a function of asymmetric hot rolling (ASHR) process parameters was investigated for a high manganese non-magnetic steel. Shear strain distribution was calculated using a two-dimensional finite element method. According to the simulation results, the surface layer of ASHR plate undergoes the highest total shear deformation which leads to the formation of a fine-grained surface layer under conditions of large rolling reduction and relatively high temperature. In the central layer is still the partially recrystallized microstructure. With velocity ratio increasing, the depth of fine-grained surface layer approaches 1/4 plate thickness, while the recrystallization proportion for the central layer is also enhanced due to the reinforced extra shear deformation. By appropriate parameter optimization, the austenitic grain size is finally refined to ~5 µm for the surface layer and ~9 µm for the center, such that the tensile property is improved.