C2024-20712 Can Electrochemical Charging Replace Hydrogen Gas Charging During Hydrogen Embrittlement Testing?

Roy Johnsen, Erik Koren, Bård Nyhus, Catalina Hagen, Anette Hagen, Antonio Alvaro - This paper presents the output from a study with the aim to correlate hydrogen gas charging and electrochemical charging for a X65 pipeline steel. The hydrogen uptake and diffusivity were evaluated via the permeation technique by employing both hydrogen gas charging and electrochemical charging. The dependency of effective diffusion coefficient, Deff, on the charging conditions was investigated. Sub-surface hydrogen concentration, C0R, was then employed to determine a relationship between effective hydrogen fugacity fH2eq and overvoltage η. In parallel, a permeation cell consisting of two membranes with thickness 6 mm welded together with a narrow gap in between was built. This unit was exposed to equal cathodic polarization conditions as the electrochemical permeation cell. The equilibrium pressure in the gap was measured and compared to the calculated hydrogen pressure from the gas permeation te