H effects in Al-Mg, Al-Zn-Mg alloys and in Al: experiments, continuum and atomistic modeling

Döme Tanguy (1)

1 ILM - Institut Lumière Matière [Villeurbanne]

Stress corrosion cracking of pure Al5%Mg is studied. It is shown by slow strain rate tests, constant force and cyclic traction-traction tests in a simulated confined medium that alpha ligaments (precipitate free) can be embrittled by hydrogen. Surface crack initiation in aged, annealed, 5083, after reversible H pre-charging, is modeled by a combination of digital image correlation and polycrystalline aggregate finite element simulation. It is shown, at the scale of the grain, that cracking occurs by a "decohesion" in between hard grains embedded in a deformation band. Cohesive zone modeling is used to quantify the possible impact of H weakened beta precipitates on the global cohesion of a grain facet. It is shown that alpha embrittlement dominates. Finally, some basic aspects of hydrogen interactions with defects in Al are discussed, from atomic scale simulations: the stability of vacancy-hydrogen clusters, their mobility, hydrogen trapping, intergranular H and vacancy segregation and their impact on cohesion.

Mots clés: aluminum alloys; hydrogen embrittlement; grain boundary cohesion

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Döme Tanguy. H effects in Al-Mg, Al-Zn-Mg alloys and in Al: experiments, continuum and atomistic modeling. Corrosion, 2016, 72 (2), pp.297-313. ⟨10.5006/1854⟩. ⟨hal-02988108⟩