H induced C-Cr associate redistribution in MANET steel

Internal friction (IF) and dynamic modulus (M ) measurements have been performed on samples of MANET steel (10.5% Cr, 0.17% d 4 C) to study the interaction of H with C–Cr clusters. Samples of MANET steel as-quenched and annealed for 7.2310 s at 973 K have n been permeated by flowing H at 873 K. The IF curves have been analysed using the linear approach proposed by Sarrak, Tomilin, Golovin and Suvorova and fitted as the sum of seven Snoek-type peaks corresponding to a different number n of Cr atoms (0#n#6) at 21 the corners of the octahedron around the C atom. The comparison between Q spectra of samples before and after H permeation shows that a redistribution of C–Cr clusters takes place. In particular, H appears to preferentially interact with C of the C–Cr clusters with a n n higher number of Cr atoms