An electrochemical permeation method was used to measure the diffusivity of H in 3N5-purity material at temperatures of between 10 and 80C. It was found that the data for 0.5M H2SO4 electrolyte solution represented the highest diffusivity.

Studies on the Diffusivity of Hydrogen in Pure Iron. C.W.Su, J.K.Wu: Journal of Materials Science Letters, 1988, 7[8], 849-50