Hydrogen uptake and diffusivity in steel armor wires with different chemical composition, carbide distribution, grain size, and degree of deformation

In this study, six flexible pipe steel armor wires used in oil and gas transportation are characterized, their hydrogen diffusion coefficients uptakes measured using an electrochemical permeation technique. The have ferritic–pearlitic microstructures with round, lamellar, or partially lamellar carbides the shape orientation of grains indicate that were plastically deformed to different degrees. It was assumed transported through ferrite, so presence cementite leads longer paths which quantified a tortuosity factor. After compensating for tortuosity, normalized steady-state flux shows tendency increase as grain size decreases. effective decrease ferrite–cementite interface area, suggesting trapping on interfaces. uptake diffusible lowest least materials about twice high more materials.