1. Characterization of sensitivity to FPH under H2 pressure

1.1 Specific features of gas loading

In order to characterize the FPH sensitivity of a metal in the presence of H ₂ pressure, it is necessary to use appropriate equipment guaranteeing the quality of the results obtained. Indeed, the latter can be significantly impacted by the following points (figure 1 ):

• metal surface finish. Greater roughness results in greater sensitivity of the material to FPH. An oxide layer can also reduce the penetration of hydrogen into the material and reduce or mask the sensitivity of the material, leading to erroneous data;

• ...