Hydrogen embrittlement I. Analysis of hydrogen-enhanced localized plasticity: Effect of hydrogen on the velocity of screw dislocations inα-Fe

Discrete dislocation plasticity HELPs understand hydrogen effects in bcc materials

“…Using a line tension model, Itakura et al (2013) studied hydrogen effect on screw dislocation mobility in α-Fe using first-principles calculation and revealed a general trend that hydrogen enhances screw mobility by promoting nucleation of kink pairs at a low concentration and decreases the mobility by impeding migration of kink pairs at a high concentration. Based on this work and by performing kinetic Monte Carlo (kMC) simulations, Katzarov et al (2017) were able to simulate the motion of individual 1/2[111] screw dislocations over long timescales. They provided the first quantitative description of hydrogen effects on screw mobility as a function of bulk hydrogen concentration, temperature and applied stress in α-Fe.…”

“…In this paper, we present three dimensional discrete dislocation plasticity (DDP) simulations incorporating hydrogen in a finite volume with dislocation mobility parameters typical for bcc metals and a physical bulk hydrogen concentration. In addition to hydrogen elastic shielding, hydrogen increased dislocation mobility is also incorporated following the quantitative description introduced by Katzarov et al (2017). The simulations were performed using an in-house Matlab based GPU accelerated DDP code; which is a modified version of DDLab developed at LLNL by Arsenlis et al (2007).…”

“…The influence of hydrogen on dislocation mobility can be directly captured by atomistic simulations. Katzarov et al (2017) calibrated the effect of hydrogen on the mobility of pure screw dislocations in α-Fe, using kMC based on first principle calculations (Itakura et al, 2013). A quantitative relationship between dislocation mobility and bulk hydrogen concentration were extracted under different temperatures and applied stresses.…”

“…A quantitative relationship between dislocation mobility and bulk hydrogen concentration were extracted under different temperatures and applied stresses. This work concerns the ambient temperature case, and the corresponding curves is reproduced with permission from Katzarov et al (2017) in Fig. 2(a).…”

Hydrogen embrittlement II. Analysis of hydrogen-enhanced decohesion across (111) planes in α -Fe

“…These are hydrogen-enhanced localized plasticity (HELP), which is the subject of the first in this series of two papers [1], and hydrogen-enhanced decohesion (HEDE), which is the subject of this paper. Decohesion associates hydrogen embrittlement with a decrease in the atomic bond strength due to hydrogen segregation at a grain boundary or other interface.…”