A quantum-mechanically informed continuum model of hydrogen embrittlement

Thermo-mechanical treatment effects on stress relaxation and hydrogen embrittlement of cold-drawn eutectoid steels

“…Fractographic observations of the fracture surfaces showed that, in all the cases, failure proceeded through the growth of a fissure on a slanting orientation to the wire axis and nucleated at the wire surface, in keeping with previously published results for similar materials [25]. There is no unanimously accepted microscopic mechanism of hydrogen assisted metal failure; however, at a macroscopic level, it is assumed that a critical couple of tensile stress and hydrogen concentration must occur at a finite size material zone for failure initiation or propagation [39], with the critical concentration decreasing if the stress is increased. According to this, a crack is initiated or its growth is promoted when the concentration of hydrogen at a pre-existing stressed defect exceeds some critical value.…”

Effect of atomic scale plasticity on hydrogen diffusion in iron: Quantum mechanically informed and on-the-fly kinetic Monte Carlo simulations

“…Some progress can be made by incorporating information from more accurate calculations (quantum mechanical/atomistic) at smaller length scales in continuum models. As noted previously, recent work by Carter, Ortiz, and coworkers 31,33,34 along these lines has provided a basis for addressing crack propagation by hydrogen-enhanced decohesion. Although that work used a cohesive law from quantum mechanical calculations, crack tip plasticity and stress-assisted diffusion were still treated at a phenomenological level.…”

“…This implies that segregation of hydrogen to crack tips (within the so-called "cohesive zone" region ahead of a crack), or to other internal interfaces within the material, will lead to cleavage along fracture planes or decohesion of interfaces at lower levels of load. Indeed, this model for reduced cohesive strength with increasing hydrogen coverage, with proper upscaling to continuum scales via renormalization, 32,33 was used in the work of Serebrinsky et al 34 and shown to produce plausible results for intermittent crack propagation in embrittled steels. Similar models, albeit with a phenomenological law for degradation of cohesive strength, have also been proposed.…”

Modeling, Simulation and Experimental Studies of Distortions, Residual Stresses and Hydrogen Diffusion During Laser Welding of As-Rolled Steels

“…In fact, a source term must be added to the right side of the equation, which was firstly developed by MCNABB and FOSTER, (McNabb & Foster, 1963), and later by ORIANI assuming 'local equilibrium', (Oriani, 1970). Thus, the following equations hold for diffusion of hydrogen under the presence of local stress fields (c << 1) , (Serebrinsky et al, 2004):…”