DANSK DSF/FPRCEN/TS 18094 PDF

The work provides advice on how to determine reliable estimates of residual stresses from the strain data and on how to estimate the uncertainty in the results. The work item will describe the test method for determining residual stresses in polycrystalline materials by synchrotron diffraction method. It is applicable to both homogeneous and inhomogeneous materials including those containing distinct phases. The principles of the synchrotron diffraction technique is described and put into perspective with the EN15305 standard on Non-destructive Testing – Test Method for Residual Stress analysis by X-ray Diffraction (test method for the determination of macroscopic residual or applied stresses non-destructively by X-ray diffraction analysis in the near-surface region of a polycrystalline specimen or component) and the ISO 21432 standard on Non-destructive testing – Standard test method for determining residual stresses by neutron diffraction. Information on how to carry out residual stress measurement by synchrotron diffraction technique is provided as: • the selection of appropriate diffracting lattice planes on which measurements should be made for different categories of materials, • the specimen directions in which the measurements should be performed, • the volume of material examined in relation to the material grain size and the envisaged stress state, and • the selection of the stress-free reference sample to be able to make the residual stress calculation. Procedures will be described for calibrating synchrotron diffraction instruments and for accurately positioning and aligning test pieces and for precisely defining the volume of material sampled for the individual measurements. Procedures for making measurements will be presented together with those for analysing the results and for determining their uncertainties based on statistics.