Methods for obtaining the strain-free lattice parameter when using diffraction to determine residual stress

• Published in: Journal of applied crystallography 2007-10, Vol.40 (5), p.891-904
• Main Authors: Withers, P. J., Preuss, M., Steuwer, A., Pang, J. W. L.
• Format: Article
• Language: English
• Subjects: Crystallography; Diffraction; Measurement techniques; neutron diffraction; Research methodology; residual stress; strain-free lattice spacing; Stress; synchrotron X-rays; Uncertainty
• ISSN: 1600-5767; 0021-8898; 1600-5767
• DOI: 10.1107/S0021889807030269

The determination of residual stress by diffraction depends on the correct measurement of the strain‐free lattice spacing , or alternatively the enforcement of some assumption about the state of strain or stress within the body. It often represents the largest uncertainty in residual stress measurements since there are many ways in which the strain‐free lattice spacing can vary in ways that are unrelated to stress. Since reducing this uncertainty is critical to improving the reliability of stress measurements, this aspect needs to be addressed, but it is often inadequately considered by experimenters. Many different practical strategies for the determining of or dref have been developed, some well known, others less so. These are brought together here and are critically reviewed. In practice, the best method will vary depending on the particular application under consideration. Consequently, situations for which each method are appropriate are identified with reference to practical examples.