Modelling the effect of hydrogen on ductile tearing resistance of steels

Abstract

The effect of hydrogen on the mechanical behaviour of steels is twofold: it affects the local yield strength and it accelerates material damage. On the other hand, the diffusion behaviour is influenced by the hydrostatic stress, the plastic deformation and the strain rate. This requires a coupled model of deformation, damage, hydrogen sorption and diffusion. The deformation behaviour is described by von Mises plasticity with isotropic hardening, and crack extension is simulated by a cohesive zone model. The local hydrogen concentration, which is obtained from the sorption and diffusion analysis, causes a reduction in the yield strength and the cohesive strength. Crack extension in a C(T) specimen of a ferritic steel under hydrogen charging is simulated by fully coupled finite element analyses of hydrogen kinetics and mechanical behaviour. The simulation results are compared with test results.

A coupled diffusion and cohesive zone modelling approach for numerically assessing hydrogen embrittlement of steel structures

“…Given that the model takes neither the kinetics of trapping/detrapping nor the transport of hydrogen to the surface into account, all approaches may be argued for. From Figure 14 scription of the model can be found in [14,68].…”

A review of cohesive zone modelling as an approach for numerically assessing hydrogen embrittlement of steel structures

“…A thorough description of the model can be found in [14,54]. By including both local hydrogen softening and hydrogen induced lowering of the local cohesive strength, the model describes an attempt in the direction of including both the HEDE and the HELP degradation mechanisms and their interactions.…”

“…Brocks and co-workers [14,54] have developed a model of hydrogen-induced cracking, which, in addition to the coupled interactions of hydrogen diffusion and reduced cohesive strength, also includes the effect of surface kinetics on hydrogen absorption and hydrogen-induced softening of the local yield strength (HELP mechanism). A thorough description of the model can be found in [14,54].…”

“…Brocks and co-workers [14,54] have developed a model of hydrogen-induced cracking, which, in addition to the coupled interactions of hydrogen diffusion and reduced cohesive strength, also includes the effect of surface kinetics on hydrogen absorption and hydrogen-induced softening of the local yield strength (HELP mechanism). A thorough description of the model can be found in [14,54]. By including both local hydrogen softening and hydrogen-induced lowering of the local cohesive strength, the model describes an attempt in the direction of including both the HEDE and the HELP degradation mechanisms and their interactions.…”

Editorial

“…Andrieux and Sun develop and validate damage models from the behaviour of deep drawn TRIP steel [4], while Helm examines the thermo-mechanical representation of stored energy during plastic deformation [5]. Molecular dynamics simulation of the lubrication phenomena in ultrathin solid gold films is the subject of the contribution from Pastewka et al [6] and Falkenberg et al model the effect of hydrogen on the ductile tearing resistance of steels [7]. Completing the selection of papers dedicated to Hermann Riedel, Svoboda and Maier derive a model for the formation of precipitate-free zones [8].…”