The distribution of chromium and carbon atoms in 9% and 11% Cr martensitic steels, quenched and then submitted to different annealing treatments, has been investigated by means of X-ray diffraction (XRD) analysis, microhardness tests, internal friction (IF) and dynamic modulus ( M d) measurements. Results are analyzed on the basis of the concentrations of carbon atoms remaining in solution after the various stages of carbide precipitation.