Amorphous and nanocrystalline phases were detected on the top of the nitrided layer by TEM. The DOS of IGC was analyzed in detail by DL-EPR measurement. Erosion-wear resistance of the sample nitrided at 673 K for 6 h was doubly enhanced. The enhancement of the surface microhardness (673 K-36 h) reached up to ∼ 6 times.