Predictive Modelling of  Hydrogen Assisted Fracture

Hydrogen embrittlement is arguably one of the biggest threats to the integrity of our engineering infrastructure. Hydrogen is ubiquitous and causes catastrophic failures in metallic components. The ductility and fracture resistance are drastically reduced in the presence of hydrogen and these effects increase with material strength. High strength steels exhibit hydrogen assisted cracking in otherwise benign environments (e.g., due to humidity) and a significant fracture toughness reduction with hydrogen concentration (by up to 90%!). Decades of metallurgical progress are effectively compromised by the effect of hydrogen and a problem that was mostly bounded to aggressive environments, e.g. oil and gas extraction, is now pervasive in numerous applications, from bridges to cars.
The speaker and his collaborators have been engaged in the development of models capable of predicting hydrogen assisted cracking as a function of the environment, the material and the loading conditions. To solve this longstanding challenge, research efforts were focused on four fronts: (1) the mechanisms of hydrogen embrittlement, (2) the plastic response at the small scales involved in crack tip deformation, (3) the characterization of hydrogen transport and the electrochemistry-diffusion interface, and (4) the development of robust numerical methods for crack propagation. The combination of these efforts into a mechanism-based framework for hydrogen embrittlement led to an unprecedented level of agreement with experimental measurements. The promising results achieved over a wide range of scenarios have attracted the interest of industrial partners and technical standards organizations, paving the way to extending the success of Virtual Testing to hydrogen-sensitive applications.

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