Hydrogen Permeation and Diffusion on Artificially Aged 2¼Cr-1Mo Steel

The influence of microstructure degradation of an artificially aged 2¼Cr-1Mo steel on hydrogen permeability and diffusivity, was studied using hydrogen gas permeation tests. Samples were submitted to aging treatments at 600 °C for 2000 h, under inert and hydrogen atmosphere. Carbide precipitation, morphology and coarsening were characterized by means of SEM, TEM and synchrotron source XRD. In as-received condition, the steel exhibits a fully bainitic microstructure with fine precipitates distributed on matrix and grain boundaries. It was verified that the presence of hydrogen during aging alters the stability of carbides and their volumetric fraction. The evolution of the microstructure heat...