Investigating the effects of sub-surface microstructure within crystal plasticity

Safe operation is vital in the nuclear industry. This is achieved through codes and standards that incorporate overly conservative assumptions. Reducing these over-conservative assumptions, whilst maintaining confidence in the results, could lead to increased plant lifetime and so increased production of low carbon energy. Material models, such as crystal plasticity finite element (CPFE) methods, may improve the predictions of codes and standards because they account for microstructural effects directly. For industry to adopt CPFE as a material modelling method, it must be sufficiently validated. One area that is difficult to validate is the effect of sub-surface microstructure on mechanical response due to the complexity associated with acquiring it. This study explores the impact of sub-surface microstructure on CPFE modelling, primarily focusing on deformation. Electron backscatter diffraction (EBSD) is combined with serial sectioning using a focused ion beam to collect a 3D representation of the microstructure below the surface. The microstructure collected is implemented into a CPFE model and compared with a simulation that does not consider the sub-surface microstructure. The intragranular elastic strain and local orientation changes are compared to experimental data. Difference between results is seen, with the inclusion of sub-surface microstructure leading to closer agreement with EBSD data.