The permeation data for this 2.25Cr-1wt%Mo steel could be described by the expression:

P (cm2/cm s Pa½) = 0.00037 exp[-54.5(kJ/mol)/RT]

while the H diffusivity could be described by:

D (cm2/s) = 0.00032 exp[-9.2(kJ/mol)/RT]

T.P.Perng, C.J.Altstetter: Metallurgical Transactions A, 1986, 17[11], 2086-90