The permeation rate of H through two α-Fe specimens was measured by using a low-pressure steady-state technique under conditions such that diffusion was the rate-controlling process for permeation. The permeation rate in these samples could be described by:

P (mol/s cm torr½) = 5.55 x 10-9 exp[-8095/RT]

for H pressures of 21 to 766torr and temperatures of 342 to 619K. These permeation data were combined with known solubility data to give an expression for H diffusivity in α-Fe:

D (cm2/s) = 1.01 x 10-3 exp[-1595/RT]

R.F.Miller, J.B.Hudson, G.S.Ansell: Metallurgical Transactions A, 1975, 6[1], 117-22