Significance and Use 6.1 This test method provides standard procedures for experimentally determining the XEC for use in the measurement of residual and applied stresses using x-ray diffraction techniques. It also provides a standard means of reporting the precision of the XEC. 6.2 This test method is applicable to any crystalline material that exhibits a linear relationship between stress and strain in the elastic range, that is, only applicable to elastic loading. 6.3 This test method should be used whenever residual stresses are to be evaluated by x-ray diffraction techniques and the XEC of the material are unknown.Scope 1.1 This test method covers a procedure for experimentally determining the x-ray elastic constants (XEC) for the evaluation of residual and applied stresses by x-ray diffraction techniques. The XEC relate macroscopic stress to the strain measured in a particular crystallographic direction in polycrystalline samples. The XEC are a function of the elastic modulus, Poisson’s ratio of the material and the hkl plane selected for the measurement. There are two XEC that are referred to as 1/2 S2hkl and S1 hkl. 1.2 This test method is applicable to all x-ray diffraction instruments intended for measurements of macroscopic residual stress that use measurements of the positions of the diffraction peaks in the high back-reflection region to determine changes in lattice spacing. 1.3 This test method is applicable to all x-ray diffraction techniques for residual stress measurement, including single, double, and multiple exposure techniques. 1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
