Mass spectrometry was used to study the permeation of H through membranes of fully-annealed and slightly cold-worked material which was in contact with distilled H2O or dilute acidic buffer solutions. At temperatures ranging from 10 to 100C, the permeation and diffusivity could be described by:

P (/s) = 7.2 x 10-2 exp[-13.0(kcal/g-atom)/RT]

D (cm2/s) = 2.2 x 10-3 exp[-3.1(kcal/g-atom)/RT]

In the case of fully-annealed or slightly cold-worked material, the H could diffuse into the Fe only when the Fe contacted the H2O directly. Abrasion, or H ions in a dilute acidic buffer solution, did not affect the H diffusion coefficient but increased the H concentration at the Fe surface which contacted the H2O or buffer solution.

Diffusion of Hydrogen in Iron. J.Y.Choi: Metallurgical Transactions, 1970, 1[4], 911-9