The diffusivity was measured by using an electrochemical permeation method. The diffusivity in annealed specimens, at temperatures between 311 and 332K and using a charging current of 50A/m2, was described by the expression:

D (m2/s) = 4.41 x 10-7 exp[-53.51(kJ/mol)/RT]

Cold-rolled specimens exhibited a higher diffusivity,

D (m2/s) = 4.51 x 10-7 exp[-49.92(kJ/mol)/RT]

and this was attributed to the presence of cold-worked α' martensite.

The Electrochemical Determination of Diffusivity and Solubility of Hydrogen in an Austenitic Type 304 Steel. Y.Sakamoto, H.Katayama: Journal of the Japan Institute of Metals, 1982, 46[8], 805-14