Microstructural Influence on Mechanical Properties of a Lightweight Ultrahigh Strength Fe-18Mn-10Al-0.9C-5Ni (wt%) Steel

This study evaluates the role of thermomechanical processing and heat treatment on the microstructure and mechanical properties of a hot rolled, annealed, and aged Fe-18Mn-10Al-0.9C-5Ni (wt%) steel. The steel exhibited rapid age hardening kinetics when aged in the temperature range of 500-600 degrees C for up to 50 h, which has been shown in other work to be the result of B2 ordering in the ferrite and kappa-carbide precipitation within the austenite matrix. The ultimate tensile strength increased from 1120 MPa in the annealed condition to 1230 MPa after 2 h of aging at 570 degrees C. Charpy V-notch toughness was evaluated at -40 degrees C in sub-sized specimens with a maximum in the annealed and quenched condition of 28.5 J in the L-T orientation.