The evolution of H from the stainless steel was studied by using a real-time dynamic technique under ultra-high vacuum conditions. The H diffusivity was found to be described by the expression:

D (m2/s) = 7.01 x 10-7 exp[-48.0/RT]

over the entire temperature range which was studied. This suggested that H evolution was not appreciably affected by the changing surface composition.

R.A.Outlaw, D.T.Peterson: Metallurgical Transactions A, 1983, 14[9], 1869-74