Influence of the C content on the permeation of hydrogen in Fe alloys with low contents of C. (December 2016) - Peñalva, I.
Highlights: The gas permeation technique was used to study the influence of the C content in the permeation of hydrogen. Six Fe alloys with controlled chemical alloying elements and microstructure were analyzed and values of the permeability (ϕ) were experimentally measured. An increase of the permeability due to the presence of low content of C (tens of ppm in weight) was experimentally measured. A negligible effect on the permeability due to the presence C (∼800 ppm of in weight) was experimentally measured. The effects caused by the presence of P and Cr together with C were also studied, showing a negligible influence in the permeability of H due to the addition of low contents of C in presence of P and Cr. Abstract: In this work, the permeability of hydrogen through samples of six Fe alloys was experimentally analyzed. The main objective of this work was to determine the influence of the C content of the alloy in the permeability of hydrogen. Three of the samples, pure Fe, FeP and Fe10%Cr, contained negligible quantities of C, whereas the other three, FeC, FePC, and Fe10%CrC, had the same metallurgical composition as their corresponding pair, with the only difference in the carbon content. The gas evolution permeation technique was used to measure the hydrogen transport parameter of permeability in these alloys. The experimental measurements were carried out with temperatures ranging from 423 K to 823 K and for high purity hydrogen loading pressures ranging from 1.0 × 10 3 Pa to 1.5 × 10 5 Pa. The experimental permeation results were analyzed using a non-linear least square fitting. The final resulting values of the permeability were paired off in order to determine the effect of the C content: pure Fe versus FeC, FeP versus FePC and Fe10%Cr versus Fe10%CrC. According to the results, the influence of the metallurgical composition of C in Fe alloys on the permeability of hydrogen is discussed together with the synergistic effects caused by the presence of P and Cr.