Study of the hydrogen diffusion and segregation into FeCMo martensitic HSLA steel using electrochemical permeation test

摘要

Diffusion and trapping mechanisms are studied in order to improve Hydrogen embrittlement (HE) resistance of high yield strength steels. Investigations were carried on Fe-C-Mo model steel with a quenched and tempered martensitic microstructure. Hydrogen diffusion was studied by using the electrochemical permeation technique. The influence of the charging current densities in 1 M H_2SO_4 at ambient temperature shows a relation between the apparent diffusion coefficient D_(app) and the apparent subsurface concentration of hydrogen C_(0app). Two domains can be separated and are mainly associated with a competition between two distinct processes: hydrogen trapping and hydrogen diffusion. These results are correlated to the quantities of reversible and irreversible traps into the membrane Moreover, the experimental results revealed that the apparent diffusion coefficient increases and the total amount of trapped hydrogen decreases with temperature. The activation energy of the diffusion process (0.26 eV) and the trapping process (0.58 eV) are supposed to be, respectively, affiliated with lattice diffusion and with trapping on incidental dislocations and/or on martensitic lath interfaces due