Abstract: The tested wire specimens of Fe-Nb alloys were carbonized with 0.5wt%C in a hydrogen-benzene mixed gasflow at a temperature lower than A1 point. The metallograph observation on the quenched specimens showed that the structure of the carbonzied surface layer with a thickness about 40μm is martensite, whereas that inside the layer is α-Fe phase. The internal frictions of both the quenched specimens at room temperatures and the quenched-deformed specimens at the room-medium temperatures were measured by NHI-12 vacuum Keˆ-pentulum. It was found that there is an 1 × 10^-2 high peak near 45°C in the quenched specimens, while in the quenched-deformed specimens, a higher peak (h = 1.7-2.0 × 10^-2) by 45-60°C takes place with two small peaks, i.e., -300°C and -235°C peaks. It is considered that under the experimental conditions including the strongly macrostrutural stress, they are separately the diffusion peak of carbon atoms in body-centered tetragonal (bct) lattice, the SKK peak in the desolution process of metastable carbide in martensite and the SKK peak of the α-Fe deformed phase.