The migration of H was measured by using a gas permeation technique. Plastic deformation of the ferritic stainless steel was found to decrease the H diffusion markedly and to increase the solubility slightly,

0% deformation (>170C):     D (cm2/s) = 6.40 x 10-5 exp[-7.0(kJ/mol)/RT]

0% deformation (<170C):     D (cm2/s) = 8.45 x 10-2 exp[-33.7(kJ/mol)/RT]

25% deformation:     D (cm2/s) = 1.71 x 10-2 exp[-36.7(kJ/mol)/RT]

50% deformation:     D (cm2/s) = 2.34 x 10-2 exp[-37.2(kJ/mol)/RT]

75% deformation:     D (cm2/s) = 9.03 x 10-2 exp[-45.5(kJ/mol)/RT]

The behavior of the steels was explained in terms of trapping and phase transformations. Uniformly deformed material was studied with the aim of eventually simulating the state of the material at the tip of a H-embrittlement crack. Observed differences in the crack propagation behaviors of the alloys could be rationalized in terms of H transport and solubility in the deformed state.

T.P.Perng, M.Johnson, C.J.Altstetter: Acta Metallurgica, 1989, 37[12], 3393-7