Permeability, solubility and diffusivity of hydrogen in alloy 718

The permeability, solubility, and diffusion of hydrogen in alloy 718 were examined through both, experimental results and data from existing literature. There is a notable difference between hydrogen solubilities calculated from concentration measurements and those derived from permeation measurements. Consequently, based on a synthesis of experimental and literature data, the following coefficients for hydrogen are proposed: K0=186 mol/(m3 * MPa0.5) and HS=8140 J/mol for solubility, P0=1.68 * 10-4 mol/(m3 * MPa0,5) and HP=57974 J/mol for permeability as well as D0=9.01 * 10-7 m2/s and HD=49834 J/mol for diffusivity. It is shown that these coefficients can largely be applied independently of the heat treatment of alloy 718.