Multi-field modelling of hydride forming metals Part II : application to fracture

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Multi-field modelling of hydride forming metals Part II : application to fracture

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Publication Article, peer reviewed scientific
Title Multi-field modelling of hydride forming metals Part II : application to fracture
Author(s) Jernkvist, Lars Olof
Date 2014
English abstract
In Part I of the present article, we formulated a continuum-based computational model for stress- and temperature-directed diffusion of hydrogen in metals that form brittle binary hydrides, such as Zr and Ti alloys. Among the space–time dependent parameters calculated by the model are the volume fraction and the mean orientation of hydride precipitates. These parameters are of importance for quantifying the embrittlement of hydrided materials. In this second part of the work, we use measured data for the strength and toughness of hydrided Zr alloys to correlate the local fracture properties of the two-phase (metal + hydride) material to the aforementioned parameters. The local fracture properties are used as space–time dependent input to a cohesive zone type submodel for fracture, which is fully integrated with the hydrogen transport model from Part I. The complete model is validated against fracture tests on hydrogen-charged Zr–2.5%Nb, a material used in nuclear reactor pressure tubes. More precisely, we study local embrittlement and crack initiation at a blunt and moderately stressed notch, resulting from gradual accumulation of hydrides at the notch during temperature cycling. We also simulate tests on crack initiation and growth by delayed hydride cracking, a subcritical crack growth mechanism with a complex temperature dependence. From the results of the simulations, we conclude that the model reproduces many observed features related to initiation and propagation of hydride induced cracks in the Zr–2.5%Nb material. In particular, it has the capacity to reproduce effects of the material’s temperature history on the fracture behaviour, which is important for many practical applications.
DOI http://dx.doi.org/10.1016/j.commatsci.2013.11.035 (link to publisher's fulltext)
Publisher Elsevier
Host/Issue Computational Materials Science;
Volume 85
ISSN 0927-0256
Pages 383-401
Language eng (iso)
Subject(s) Hydrogen
Hydride
Diffusion
Embrittlement
Fracture
Phase transformation
Zirconium
Titanium
Technology
Research Subject Categories::TECHNOLOGY
Handle http://hdl.handle.net/2043/17150 (link to this page)

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