Relationship between the microstructure and properties of thermomechanically processed Fe？17Mn and Fe？17Mn？3Al steels

Two austenitic Mn steels (Fe？17Mn and Fe？17Mn？3Al (wt%, so as the follows)) were subjected to thermomechanical processing (TMP) consisting of forging followed by solutionization and hot rolling. The rolled samples were annealed at 650 and 800°C to relieve the internal stress and to induce recrystallization. The application of TMP and heat treatment to the Fe？17Mn/Fe？17Mn？3Al steels refined the austenite grain size from 169 μm in the as-solutionized state to 9–13 μm, resulting in a substantial increase in hardness from HV 213 to HV 410 for the Fe？17Mn steel and from HV 210 to HV 387 for the Fe？17Mn？3Al steel. The elastic modulus values, as evaluated by the nanoindentation technique, increased from (175 ± 11) to (220 ± 12) GPa and from (163 ± 15) to (205 ± 13) GPa for the Fe？17Mn and Fe？17Mn？3Al steels, respectively. The impact energy of the thermomechanically processed austenitic Mn steels was lower than that of the steels in their as-solutionized state. The addition of Al to the Fe？17Mn steel decreased the hardness and elastic modulus but increased the impact energy.