Hydrogen-enhanced localized plasticity is an acceptable mechanism for hydrogen embrittlement which is based upon experimental observations and theoretical computations. The underlying principle in the hydrogen-enhanced localized plasticity theory is that the presence of hydrogen causes the localization of the slip bands which results in the decrease of the fracture strength. In a sample under plane-strain tensile stress, plastic instability could lead to either the concentration of plastic flow in a narrow neck or bifurcation from homogeneous deformation into a mode of an exclusively localized narrow band of intense shear. Recently, it was demonstrated that the presence of hydrogen could indeed induce shear banding bifurcation at macroscopic strains. By using a steady-state equilibrium equation for hydrogen diffusion analysis, the effect of hydrogen on the bifurcation of a homogeneous deformation in a plane-strain tension specimen into a necking or a shear localization mode of deformation has already been studied. In the present research, using a transient hydrogen diffusion analysis and introducing a new constitutive equation accompanied by considering the reduction in the local flow stress upon hydrogen dissolution into the lattice, the effect of hydrogen on shear localization was investigated. In addition, progress was made in that, the changes in the distribution of the total and trapping hydrogen concentrations through the loading time and particularly during the development of the necking event were determined.

A Coupled Elastoplastic-Transient Hydrogen Diffusion Analysis to Simulate the Onset of Necking in Tension by using the Finite Element Method. R.Miresmaeili, M.Ogino, T.Nakagawa, H.Kanayama: International Journal of Hydrogen Energy, 2010, 35[3], 1506-14