Effects of the Microstructure on the Hydrogen Diffusivity in Ni-Based Superalloy 718
In some applications involving aggressive environments, common in oil and gas industries, superalloys 718 may suffer hydrogen embrittlement, resulting in degradation of mechanical properties. The aim of this work is to study the interaction of hydrogen with different microstructures in a 1 mm thick plate, annealed and age hardened superalloy 718. In this way, the effects of hydrogen interaction on microstructure were studied via thermal programmed desorption (TPD), tensile tests and scanning electron microscopy (SEM). Samples were studied in as-received, artificially aged and overaged conditions. Hydrogenated samples submitted to tensile tests presented ductility loss when compared to hydrogen free samples, showing the hydrogen embrittlement sensitivity of this alloy. The influence of phase precipitation on hydrogen diffusivity, as a result of aging treatment, was also discussed in this work.
Andreas Öchsner, Graeme E. Murch, Ali Shokuhfar and João M.P.Q. Delgado
T.S.A. Rosa et al., "Effects of the Microstructure on the Hydrogen Diffusivity in Ni-Based Superalloy 718", Defect and Diffusion Forum, Vols. 297-301, pp. 733-738, 2010