A REEXAMINATION OF THE TRAPPING OF HYDROGEN IN IRON AND STEEL

The apparent hydrogen diffusivity data for pretreated pure iron and st eel membranes have been analysed for hydrogen-trapping effects. Modifi ed equations, valid for the appropriate boundary conditions of chargin g, have been derived to compute the trap density from the apparent dif fusivity. In general, the traps are saturable in nature. The dependenc e of diffusivity of hydrogen in iron and steel on the charging current density or overvoltage indicates trapping of hydrogen at dislocations and grain/interfacial boundaries.