Austenitic high manganese and aluminum steels have exceptional combinations of high strength and toughness with excellent wear resistance. Adding aluminum in levels from 6 to 8.8 wt% reduces the density by 10-15 % compared with quenched and tempered Cr and Mo steels but also decreases strain hardening and abrasive wear resistance. Wear resistance may be improved by a low-cost heat treatment in a nitrogen atmosphere to produce a hard layer of surface AlN. In the current study, the effect of aluminum and silicon content on the kinetics of nitriding process was evaluated for a Fe- 30 %Mn-(6-9 %) Al-(1-1.6 %)Si-0.9 %C steel in the temperature range of 900-1100°C (1652-2012°F). Results show that up to a 550-lm-thick surface layer ofAlN plates can be produced, depending on the time and temperature. Increasing the amount of silicon from 1.1 to 1.6 % Si had no statistical effect on the diffusion of nitrogen in the temperature range of 900-1100°C (1652-2012°F). Increasing the amount of aluminum from 6 to 8.8 % Al decreased the diffusivity of nitrogen and increased the calculated activation energy from 64 to 79 kJ/mol. The lower than expected values of the activation energy for the diffusion of nitrogen in austenite is suggested to be the result of the development of high-diffusivity pathways at the interface between the AlN and the austenite matrix.