Hydrogen transport and trapping in EUROFER'97

The gas evolution permeation technique has been used to investigate the interaction of hydrogen with the reduced activation ferritic-martensitic steel EUROFER'97. The measurements were performed over the temperature range of 376-724 K with hydrogen driving pressures ranging from 5 × 10⁴ to 1.5 × 10⁵ Pa. The resultant diffusive transport parameters are: a diffusivity of D (m² s^-1) = 4.57 × 10^-7exp(-22.3(kJ mol^-1)/RT), a permeability of φ{symbol} (mol m^-1 Pa^-1/2 s^-1) = 1.03 × 10^-8exp(-37.4(kJ mol^-1)/RT) and a Sieverts' constant of K_s (mol m^-3 Pa^-1/2) = 2.25 × 10^-2exp(-15.1(kJ mol^-1)/RT). The resultant trapping parameters are: a trap density of N_t = 1.3 × 10²⁵ m^-3 and trapping energy of E_t = 43.2 kJ mol^-1. The possible sources of trapping are analysed and the most probable current mechanism in EUROFER'97 postulated. All the hydrogen transport parameters obtained for EUROFER'97 are compared to the available data corresponding to several steels of the same kind.