Materials Performance Centre Modeling Directions

Crystal Plasticity Modeling Prediction of intergranular strains and mechanical properties Relevant to stress corrosion cracking in stainless steels and Ni-base alloys Good expertise in Manchester, validated by X- ray and neutron diffraction Need parallelization to allow larger microstructures and studies of permutations in reasonable timescales

Grain Aggregate Modeling Prediction of intergranular stresses and strains Relevant to stress corrosion, and intergranular damage mechanisms Expertise developing in Manchester, using 3D microstructure data and diffraction-based validation Need to validate modeling approaches and address issues due to large model size.

Damage Modeling Prediction of microstructure effects on damage development Relevant to stress corrosion cracking, for example Development of current work on crystal aggregates, derived from tomography Work done so far in partnership with other institutes Need to develop further in Manchester

Image-Based Modeling Dimensional Change of Graphite Models constructed from tomography data, with crystal anisotropy deduced from pore orientations Model validation against in- situ tomography of thermal dimensional change Aim to predict irradiation induced dimensional change Currently limited by model size

Image Based Modeling Issues How large a volume do you need to model? What resolution mesh do you need? As resolution of XMT systems improves, data sets and mesh sizes expand Research Needs – Development of visualisation methodologies – Development of serial mesh generation – Any size mesh (so far up to 320 GB data set) – Development of parallelised FE code – Development of XFEM Example: fibre composite Model Stress Development

Grain Boundary Modeling Prediction of Diffusion and Segregation Relevant to stress corrosion and sensitisation kinetics Requires molecular dynamics methods Currently little expertise in Manchester in this area, but development of capability is needed to support other work Work being done with collaborators

Flow Assisted Corrosion Oxide Water H 2 H 2 Steel Fe 2+ Fe 2+ Fe 2+ Fe 2+ C0C0 C bulk CsCs Iron oxidation to give Fe(II) or magnetite Fe 3 O 4 at the internal metal-oxide interface Diffusion of soluble species (Fe 2+ and H 2 ) across the porous Oxide layer Dissolution and reduction of magnetite into solution Removal of the soluble iron species (and hydrogen), transported into the bulk of the flowing solution

Other Areas Multiscale modeling – Integration of microstructural models with fracture propagation models Coupled modeling – Development of crack tip chemistry – Influence of residual stress on crack tip deformation