The precipitates and H permeation behavior were studied in ultra-low C steel for enameling. During the preparation of samples, two annealing processes (730C, 5h; 870C, 360s) were adopted after cold-rolling. It was found that the samples contained a large number of fine Ti(C,N) and coarse Ti4C2S2 precipitates. The mean phase particle sizes of Ti(C,N) and Ti4C2S2 precipitates in the sample annealed at 730C for 5h were, respectively, larger and smaller than those in the sample annealed at 870C for 360s. The total volume fraction of precipitates in the former was larger than that in the later. The presence of Ti(C,N) and Ti4C2S2 precipitates, acting as irreversible traps for H atoms, influenced H diffusivity. The activation energies for H diffusion in both samples were measured as 44.3 and 42.6kJ/mol, respectively.

Precipitates and Hydrogen Permeation Behavior in Ultra-Low Carbon Steel. X.Yuan: Materials Science and Engineering A, 2007, 452-453, 116-20