ASTM E 1426 - 98 (Reapproved 2003) Standard Test Method for Determining the Effective Elastic Parameter for X-Ray Diffraction Measurements of Residual Stress

American Society for Testing and Materials (ASTM). Current edition approved April 10, 2003. Published July 2003. Originally approved in 1991. Last previous edition approved in 1998 as E 1426 – 98. 4 p. This test method covers a procedure for experimentally determining the effective elastic parameter, Eeff, for the evaluation of residual and applied stresses by X-ray diffraction techniques. The effective elastic parameter relates macroscopic stress to the strain measured in a particular crystallographic direction in polycrystalline samples. Eeff should not be confused with E, the modulus of elasticity. Rather, it is nominally equivalent to E/(1 + v) for the particular crystallographic direction, where v is Poisson’s ratio. The effective elastic parameter is influenced by elastic anisotropy and preferred orientation of the sample material.