Measurement of local plastic strain distribution of stainless steel by electron backscatter diffraction

Current phenomenological knowledge and understanding of mechanisms are reviewed for radiation embrittlement of reactor pressure vessel low alloy steels and irradiation assisted stress corrosion cracking of core internals of stainless steels. Accumulated test data of irradiated materials in light water reactors and microscopic analyses by using state-of-the-art techniques such as a three-dimensional atom probe and electron backscatter diffraction have significantly increased knowledge about microstructural features. Characteristics of solute clusters and deformation microstructures and their contributions to macroscopic material property changes have been clarified to a large extent, which provide keys to understand in the degradation mechanisms. However, there are still fundamental research issues that merit study for long-term operation of reactors that requires reliable quantitative prediction of radiation-induced degradation of component materials in low-dose rate high-dose conditions.

https://www.tandfonline.com/doi/pdf/10.1080/00223131.2013.772448

Current understanding of radiation-induced degradation in light water reactor structural materials

Assessment of local deformation using EBSD: quantification of accuracy of measurement and definition of local gradient.

Assessment of plastic heterogeneity in grain interaction models using crystal plasticity finite element method

Assessment of local deformation using EBSD: Quantification of local damage at grain boundaries

Three-dimensional local stress analysis on grain boundaries in polycrystalline material

A gold (Au) micro-interconnection, which connects through-hole electrodes in a three-dimensional chip-stacking LSI, is composed of several tens of grains. If the size of the interconnection becomes small in comparison with the grain, the anisotropic property of grains influences mechanical reliability. In this study, the stress distribution in the Au micro-interconnection is investigated by finite element method (FEM) analysis. The crystallographic structure of the Au micro-interconnection is obtained by a three-dimensional simulation based on a nucleation and growth model. The FEM analysis shows that the stress is concentrated on the region near the micro- interconnection/substrate interface edge and that a stress singularity exists there. The stress distribution of the micro-interconnection varies because of microscopic factors, which are due to the shape and crystallographic orientation of grains. Statistical evaluations of plural analytical models show that the stress variation approximates a normal distribution.

Yoshihiro Kawamura

Papers

Three-dimensional local stress analysis on grain boundaries in polycrystalline material

Analysis of Stress Distribution in Au Micro-Interconnection by Polycrystalline Models