Full Description
This document describes the test method for determining residual stresses in polycrystalline materialsby the synchrotron X-ray diffraction method. The method can be applied to both homogeneous andinhomogeneous materials including those containing distinct phases.
Information on how to carry out residual stress measurements by the synchrotron X-ray diffractiontechnique is provided as:
— the selection of appropriate diffracting lattice planes on which measurements should be made fordifferent 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,
— the selection of the stress-free reference (sample) facilitating the residual strain calculation, and
— the methods available for deriving residual stresses from the measured strain data.
Procedures are presented for calibrating synchrotron X-ray diffraction instruments, enabling:
— accurately positioning and aligning test pieces;
— precisely defining the volume of material sampled for the individual measurements;and also for:
— making measurements;
— carrying out procedures for analysing the results;
— determining their uncertainties.
The principles of the synchrotron X-ray diffraction technique are described and put into perspective with EN 15305:2008 and EN ISO 21432:2020, which are used to measure stresses in the bulk of a specimen.