Modelling of the Hydrogen Diffusion in Martensitic Steel in contact w ith H 2 SO 4 Media

Hydrogen Embrittlement (HE) is one of the mechanisms responsible for premature failure of structures (petroleum industries, pipe- lines, water conduit…). In the context of environmental sustainability, it is compelling to improve or conceive new processes and/or new materials capable of reducing fracture induced by HE. The purpose of this article is to analyze the influence of the oxide layer on the permeability of hydrogen. This investigation was carried on as a correlative effort with experimental tests completed on a steel with a quenched and tempered martensitic microstructure within acid media (H 2SO4). I n this project finite element modeling using Comsol Multiphysics software is needed to get abounding data concerning the apparent diffusion coefficient. Hydrogen concentration, variation of the thickness and the diffusion coefficient of the oxide layer may affect the apparent diffusion coefficient. Phenomenological laws have been derived to approach true diffusion coefficient and average hydrogen concentration as a function of apparent diffusion coefficient and hydrogen concentration at the entry side of the sample.