The permeability and diffusivity of H in the stainless steels were measured by using a gaseous permeation technique at between 200 and 430C. The results indicated that the permeability and diffusivity obeyed Arrhenius relationships:

21-6-9:     D (m2/s) = 2.49 x 10-7 exp[-51.15(kJ/mol)/RT]

21-9-9:     D (m2/s) = 6.33 x 10-7 exp[-54.99(kJ/mol)/RT]

21-6-9:     P (molH2/msMPa½) = 2.52 x 10-4 exp[-61.29(kJ/mol)/RT]

21-9-9:     P (molH2/msMPa½) = 2.83 x 10-4 exp[-62.29(kJ/mol)/RT]

and were not affected by cold-working or heat-treatment. The values were affected by the alloy composition.

X.Sun, J.Xu, Y.Li: Materials Science and Engineering, 1989, A114, 179-87