Coupling Diffusion And Mechanics Modeling For Hydrogen Embrittlement (HE) | 66472
ISSN: 2169-0022
Journal of Material Sciences & Engineering
Open Access
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This work deals with modeling HE mechanisms in high strength steels. The aim is to elucidate two failure mechanisms in the
presence of hydrogen: Hydrogen induced local plasticity (HELP) and hydrogen induced decohesion (HID). The HELP theory
suggests that hydrogen, in contrast to the usual understanding of embrittlement, enhances the dislocation mobility and promotes
slip localization, resulting in localized plastic failure. Furthermore, hydrogen reduces the bonding energy between atoms leading
to decohesion. The HID mechanism might explain the brittle intergranular fracture surface observed in high strength steels.
Experimental evidence of the occurrence of HELP versus HID or, more probably, their synergetic effect, is still an unresolved issue.
Hydrogen atoms can accumulate, either within the matrix or at interfaces (i.e., between particles and the surrounding matrix, or
grain boundaries) affecting the mechanical response of the material. We construct a finite element model in order to simulate the
mechanical behavior of the matrix and interface coupled with hydrogen transport. We also include simple kinetic models of the
flux of atoms into (and out of) an interface. We combine this understanding with micromechanical models of the interaction of
dislocations with particles and with empirical models of the effect of hydrogen on interface decohesion and plastic deformation to
provide a set of coupled constitutive equations for hydrogen transport and mechanical behavior. With this modeling framework, we
aim to identify and explore the conditions under which HELP or HID or both mechanisms are activated. In particular, we model
the failure of high strength steels which contain a distribution of nano-scale particles. We simulate the response in hydrogen and
hydrogen-free environments and identify the conditions under which hydrogen can lead to: (1) a quasi-brittle macroscopic response
through localization of plastic deformation facilitated by decohesion at the particle/matrix interface or (2) a brittle intergranular
fracture process.
Biography
Olga Barrera is a Senior Research Associate at the University of Oxford. Her expertise is in the field of computational mechanics and computational material modeling. Her research focuses on solving a range of coupled diffusion mechanics problems focused on understanding the failure process of a number of material systems. She also has experience in applying the wide range of skills developed in the fields of materials modeling and computational solid mechanics to solve exciting and important problems in parallel disciplines such as biomechanics.