Introduction: Low density, age-hardenable austenitic steels in the FeMnAlC system show promising combinations of high strength and ductility for structural applications. The combined high strength, and relatively low density (6.5-7 g/cm³), makes these alloys a potential replacement for traditional quenched and tempered steels with the added potential for significant light-weighting. These FeMnAlC steels are 10-15% less dense than conventional steels. The density reduction in FeMnAlC is primarily due to the elevated concentrations of Al in the range of 5-10 wt. pct. Alloying with aluminum is effective in both expanding the austenite lattice with a larger radius atom, as well as replacing the higher atomic weight Fe atoms in the unit cell. It has been shown in many systems that increased concentrations of Al is will stabilize δ-ferrite [1-4], a high temperature body centered cubic phase, requiring large additions of Mn to produce fully austenitic microstructures after solution treatment above 950 °C [4-7].
Authors: Krista R. Limmer, Daniel M. Field, Bryan A. Cheeseman, and Ryan A. Howell
Keywords: low density steel, plate steel, solution treatment