HYDROGEN PERMEATION AND DIFFUSION IN IRON-BASE SUPERALLOYS

In this work, the hydrogen permeation and diffusion in three iron-base superalloys, JBK-75, Incoloy903 and GH35A, were investigated. A gaseous permeation technique was employed to measure the hydrogen permeabilities and diffusivities of specimens with different heat treatments for a given alloy over the temperature range of 210-430-degrees-C. The effects of strengthening phase gamma' on the hydrogen permeation and diffusion in the alloys were examined. The results showed that the dependences of the hydrogen permeabilities and diffusivities in various alloys on the temperature obeyed Arrhenius relationship over the test temperature range and that the hydrogen permeation behavior in these alloys was essentially independent of their heat-treated conditions, i.e. which was not significantly affected by gamma' precipitates in the alloys. The hydrogen permeation parameters of the iron-base superalloys were approximately consistent with those of the austenitic stainless steels. The hydrogen transport in these alloys with fc.c. structure was generally controlled only by the lattice diffusion of hydrogen.