The relative susceptibility of ferrous alloys to hydrogen embrittlement determined by effective electrolytic hydrogen pressure measurement

Electrochemical hydrogen charging experiments with AISI 1018 and 410 steels showed that when these steels were cathodically charged under experimentally identical conditions, both the hydrogen uptake and transport characteristics and the effective hydrogen pressures developed at the charged surfaces were different. These results show that the typical hydrogen embrittlement test which uses cathodic charging at selected cathodic current densities to determine the relative susceptibility of different materials to hydrogen embrittlement is not valid because such differentiation can only be made when the materials are subjected to the same effective hydrogen pressure. The results also show that a calibration curve of effective hydrogen pressure versus cathodic charging current density must be made for each material in order to determine the proper current density to use in a cathodic charging experiment.