Applications of Neutron Diffraction in Residual Stress Analysis

The principle of residual stress measurement using neutron diffraction is based on Bragg’s Law. Through accurate characterization of the crystal plane spacing within the gauge volume, information about the material’s micro lattice deformation can be obtained, thus the deep internal elastic strain of the crystalline material can be measured non-destructively. Usually the measurement value is related to the location of the measurement, temperature and external loading, which is then used for the evaluation of structural integrity and deformation of the actual component. Based on the authors’ previous research experiences, this paper briefly introduces the basic principles of neutron diffraction and subsequently focuses on its applications in residual stress analysis in a number of typical case studies, including rolling to reduce residual stress and distortion in friction stir welds, UOE linepipe seam welds, pipe girth welds, large engineering component, near surface residual stress analysis, residual stresses at cruising altitude temperature, stress response of a welding material during in-situ heat treatment, and quantitative analysis of internal stress during thermal ageing and creep.