The migration of H was measured in the high-strength super-alloys at temperatures ranging from 150 to 500C, and applied H pressures of 1 to 3atm. In the case of Inconel-718, the results depended to some extent upon the heat-treatment which was given to the alloy. For this material, in the solution-treated condition, the results were described by:

P (cm2/s atm½) = 8.09 x 10-3 exp[-13.33(kcal/mol)/RT]

D (cm2/s) = 1.07 x 10-2 exp[-11.90(kcal/mol)/RT]

For Incoloy-903, the results were described by:

P (cm2/s atm½) = 9.50 x 10-3 exp[-13.71(kcal/mol)/RT]

D (cm2/s) = 2.46 x 10-2 exp[-12.59(kcal/mol)/RT]

Hydrogen Permeation and Diffusion in Inconel 718 and Incoloy 903. W.M.Robertson: Metallurgical Transactions A, 1977, 8[11], 1709-12