| The high mobility of hydrogen is due to the relative small size compared to the atomic size of transition metals. However the presence of defect (dislocations, voids, grain boundaries), can hinder hydrogen transport as they are potential trapping sites. The main objective is to study the hydrogen diffusivity and permeability in steels, it is possible to perform an electrochemical hydrogen permeation process in a thin film (foil or sheet) as a function of certain variables such as prior cold work, thickness, polarization charging current, grain size, electrolyte medium, type of promoter, and concentration. Devanathan and Stachurski (DS) cell is adapted to the study of hydrogen cathodic charging and permeation behavior.; Cold work in Armco-Fe sample (cold rolled condition) increases the dislocation density with these sites acting as irreversible trapping sites as reflected in the reduction of diffusivity and permeability parameters. Same behavior was observed for grain boundary. In both cases the trap binding energy obtained was 20.81 KJ/mol and 15.29KJ/mol for Armco-Fe respectively.; Based on desorption test conducted on prior hydrogen charged materials at room temperature, it appears that the solubility of hydrogen in AF1410 steel is about three times approximately higher than in Armco-Fe. (Abstract shortened by UMI.)... |
