Microstructural Evolution Study of Fe–Mn–Al–C Steels Through Variable Thermomechanical Treatments

The microstructural evolution of the two austenitic alloys Fe–20Mn–3Al–0.7C wt pct and Fe–20Mn–6Al–0.7C wt pct when different thermal and thermomechanical treatments are performed has been studied. To this end, a generic industrial die of 100 ton capacity and a Gleeble 3800 simulator were selected to perform the thermomechanical treatments. A solubilization treatment was carried out at 1100 °C for 4 days for the two alloys in as cast state. In addition, the specimens deformed with the industrial die underwent a solubilization treatment at 1100 °C for 4 hours. Microstructural characterizations were performed by X-ray diffraction, transmission Mössbauer spectrometry, and electron backscatter diffraction. The results showed both the formation of different austenites rich and poor in solute atoms, as well as different microstructures, as a function of the treatments performed, which affected the resulting dynamically recrystallized microstructures. Notably, it was observed that it is possible to explain and relate the evolution of the microstructure to the hyperfine parameters resulting from fitting the Mössbauer spectra. In particular, the relationship between the degree of dynamic recrystallization and the evolution of an ordered austenitic structure is discussed.