A novel approach for estimating hydrogen uptake and diffusion coefficient

Hydrogen diffusional parameters in metallic alloys were evaluated for API 5L-grade X65 steel by introducing a simplified approach using a single-compartment electrochemical cell. The experimental hydrogen flow from electrochemically pre-charged specimens is interpolated through a numerical approach, with a simulated target curve derived for a specific geometry. The diffusion coefficient and concentration of diffusible hydrogen were estimated after hydrogen charging in alkaline solutions at different levels of cathodic polarisation. The results show constant and reproducible values of diffusivity despite the level of polarisation, and the concentration of diffusible hydrogen increases with cathodic overpotential, depending on the composition of the solution.