The ductility of nickel sheet subjected to in situ cathodic hydrogen charging has been investigated over a range of multiaxial stress states including uniaxial, plane-strain, and equibiaxial tension. The data show that the extent of ductility loss due to the presence of hydrogen increases as the stress state tends from uniaxial to equibiaxial tension. In all instances, the hydrogen embrittlement is characterized by intergranular fracture with failure occurring due to microcrack formation, microcrack link-up, and macrocrack growth. The increased susceptibility of nickel to intergranular hydrogen embrittlement with increasing biaxiality of stress state is shown to be a consequence of an enhanced rate of the link-up of strain-induced intergranular microcracks.
Rbum&Nous
avons ttudie la ductilitt de feuilles de nickel soumises a une charge d'hydrogene cathodique in situ pour une gamme de contraintes multiaxiales comprenant les tractions uniaxiale, plane et tquibiaxiale. Nos resultats montrent que le perte de ductilite due a la presence d'hydrogene augmente lorsque l'ttat de la contrainte passe de la traction uniaxiale a la traction tquibiaxiale. Dans tous les cas, la fragilisation par l'hydrogtne est caracttriste par la rupture intergranulaire qui se produit par suite de