Significance and Use

This test method provides standard procedures for experimentally determining the effective elastic parameter for X-ray diffraction measurement of residual and applied stresses. It also provides a standard means of reporting the precision of the parameter.

This test method is applicable to any crystalline material which exhibits a linear relationship between stress and strain in the elastic range.

This test method should be used whenever residual stresses are to be evaluated by an X-ray diffraction technique and the effective elastic parameter of the material is unknown.

1. Scope

1.1 This test method covers a procedure for experimentally determining the effective elastic parameter, E _eff , 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. E _eff should not be confused with E , the modulus of elasticity. Rather, it is nominally equivalent to E /(1 + ? ) for the particular crystallographic direction, where ? is Poisson's ratio. The effective elastic parameter is influenced by elastic anisotropy and preferred orientation of the sample material.

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 inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that 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 and health practices and determine the applicability of regulatory limitations prior to use.

2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

ASTM Standards

E4 Practices for Force Verification of Testing Machines

E6 Terminology Relating to Methods of Mechanical Testing

E7 Terminology Relating to Metallography

E1237 Guide for Installing Bonded Resistance Strain Gages

Keywords

elastic parameter; residual stress; x-ray diffraction; Crystal lattice structure; Effective elastic parameter (E eff ); Macroscopic analysis; Polycrystalline materials; Residual stress; Stress--metallic materials; X-ray diffraction analysis;

ICS Code

ICS Number Code 71.040.50 (Physicochemical methods of analysis)

DOI: 10.1520/E1426-98R09E01

ASTM International is a member of CrossRef.

ASTM E1426