Berlin 2015 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 9: Hydrogen in metals II: Multiscale simulations

MM 9.5: Vortrag

Montag, 16. März 2015, 13:00–13:15, TC 006

Multiscale modelling of hydrogen embrittlement in metals — •Pratheek Shanthraj, Haiming Zhang, Gerard Leyson, Franz Roters, Tilmann Hickel, Dierk Raabe, and Jörg Neugebauer — Max Planck Institut für Eisenforschung, Düsseldorf, Germany

A multiscale phase field damage model is developed and coupled to a finite-strain thermo-mechanical framework to investigate the evolution of damage in metals under hydrogen-loaded conditions. The evolution of damage is based on the nucleation and growth of voids driven by the conservative transport and coagulation of hydrogen-stabilized superabundant vacancies, as well as the propagation of cracks driven by the competition between stored elastic energy at the crack tip and the hydrogen-dependent material decohesion energy. The dynamics of the hydrogen-decorated-vacancy concentration field and the damage microstructure is expressed in the form of a coupled Cahn-Hilliard and Allen-Cahn system of equations, respectively, and the physically based model parameters, such as decohesion and vacancy formation energies under hydrogen-loaded conditions, are obtained from ab-initio calculations, thus rendering the approach a multiscale modeling framework. As a case study, a polycrystalline aggregate, whose elasto-plastic mechanical response is governed by a local crystal plasticity model, is deformed under a range of hydrogen-loaded conditions to investigate the role of grain boundaries in the damage evolution process as a potential source and sink for vacancies as well as a site for interface decohesion.