Hydrogen transport in stainless steels

Hydrogen Diffusion and Permeation through Duplex Membrane of Cu–Ni and Cu–Fe

“…In this case the permeation rate is given by (19) where S and V are the pumping speed (1501/s) and the volume on the down stream side (2.8 1), respectively. Because of a very small vacuum time constant, 2.8/150(=0.02) s-1, the second term in the eq.…”

“…(Cu-Ni phase diagram shows the complete solid solution (20)) From the fact that the permeability is much higher in Ni than in Cu, while the diffusivity is a little smaller in the former than in the latter, it is expected that the permeability of Ni might be reduced by alloying of Cu with Ni, without appreciable change in the diffusivity. It is not Monel (19), which has the nominal composition of 65% Ni, 33% Cu and 2% Fe and shows the similar level of permeability to Ni (see Fig. 7).…”

10.2172/918137

“…The relative solubility then provides a indirect indication of the accuracy of the diffusion determination. If we neglect the studies that result in low solubility [15,34,35] and only consider the studies where the solubility determinations cluster at the highest values [29,32,36], the hydrogen diffusivity relationships are in good accord with one another. The relationship of Louthan and Derrick [27], Table 1 and marked by circles in Figure 5, appears to represent a good average of diffusivity for austenitic stainless steels.…”

“…The average relationship of Sun et al was also generated from six alloys in several conditions (solutionized, annealed and cold-worked) [29] and is marked with triangles in Figure 4. The other lines represent permeability determined for type 316 stainless steels from a number of studies [15,16,[32][33][34][35][36].…”

“…The relationships from these studies [15,34,35] are plotted as dotted lines in Figures 5 and 6. High diffusivity implies low solubility ( K = Φ D), and since diffusivity and permeability are similar in magnitude over a wide range of temperature, small differences in diffusivity appear as large relative differences in solubility, Figure 6.…”