Font Size: 

This study examines the influence of increased dislocation velocity due to hydrogen on the steady-state behavior of a crack propagating under quasi-static conditions in elastic-plastic, matched, over-matched, and under-matched weld materials. Finite element analy-ses in a small-scale yield setting with plane strain conditions resolve the near-tip fields under the remotely applied IKT− displacement fields. The constitutive model incorpo-rates hydrogen induced dilation and softening effects on the inelastic behavior of the duc-tile material representative of a pressure vessel steel. Near the crack tip, the hydrogen concentration, triaxiality, and plastic strain depend on the remote loading, the extent of material softening, and the initial concentration of hydrogen in the weld and base metal. A simple measure of damage along the uncracked ligament predicts higher values of duc-tile void growth in the presence of hydrogen and implies lower resistance to crack ad-vancement.