Hydrogen transport and trapping in EUROFER’97

Abstract

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 × 10 4 to 1.5 × 10 5 Pa. The resultant diffusive transport parameters are: a diffusivity of D (m 2 s −1) = 4.57 × 10 −7exp(−22.3(kJ mol −1)/ RT), a permeability of ϕ (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 × 10 25 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.