International Organization for Standardization (ISO)
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ISO/TTA 3:2001
Scope
This Technology Trends Assessment specifies a test method for determining residual
stresses in polycrystalline materials by neutron diffraction. It may be applied to
homogeneous and inhomogeneous materials and to test pieces containing distinct
phases.
The principles of the neutron diffraction technique are outlined. Advice is provided
on the crystalline planes on which measurements should be made for different
categories of materials. Guidance is provided about the directions in which the
measurements should be obtained and of the volume of material which should be
examined, in relation to material grain size and the stress state envisaged, when
making measurements.
Procedures are described for accurately positioning and aligning test pieces in a
neutron beam and for precisely defining the volume of material that is sampled when
individual measurements are being made.
The precautions needed for calibrating the neutron diffraction facilities are described.
Techniques for obtaining a stress-free reference are presented.
The methods of determining individual elastic strains by neutron diffraction are
described in detail. Procedures for analysing the results and for determining their
statistical relevance are presented. Advice is provided on how to determine reliable
estimates of residual (or applied) stress from the strain data and of how to estimate the
uncertainty in the results.
ISO/TTA 3:2001 history
2001ISO/TTA 3:2001 Polycrystalline materials - Determination of residual stresses by neutron diffraction