Effects of Al content on microstructure and properties of high Mn austentic steels in Fe-Mn-Al-C systemIEHK
Fe-Mn-Al-C steels possess outstanding mechanical properties based on an excellent combination of strength and ductility. The mechanical properties merged with the density reduction due to increased aluminum contents have drawn much attention to the automotive industry. Aluminum has a strong impact on the stacking fault energy and forms different types of precipitates including the intermetallic kappa-, B2- and D03- phase. Therefore, aluminum has a strong effect on the strain hardening behavior and mechanical properties, including an undesirable reduction of the elastic modulus by solute aluminum.
In this work, the impact of aluminum additions on the evolution of the microstructure and mechanical properties during austenite recrystallization and precipitation annealing processes are investigated. Light optical microscopy (LOM), synchrotron X-ray diffraction (SYXRD), atom probe tomography (APT), small angular neutron scattering (SANS) and transmission electron microscopy (TEM) are employed to study the microstructure with an emphasis on the kappa phase. The annealing conditions will be optimized with respect to achieve an ideal combination of strength, ductility and elastic modulus.