European standardization activities on residual stress analysis by neutron diffraction

A main objective of a recently completed European research project, RESTAND - residual stress standard using neutron diffraction, was to develop industrial confidence in the application of the neutron-diffraction technique for residual stress measurement and its principal deliverable was a relevant draft code of practice. In fact this draft standard was jointly developed within RESTAND and VAMAS TWA 20 - an international pre-normative research activity. As no such standard is yet available, on the basis of this draft standard document the European Standards Committee on Non-Destructive Testing (CEN TC/138) has established a new ad hoc Work Group (AHG7). The objective of this group is the development of a European pre-standard on a 'test method for measurement of residual stress by neutron diffraction'. The document contains the proposed protocol for making the measurements. It includes the scope of the method, an outline of the technique, the calibration and measurement procedures recommended, and details of how the strain data should be analysed to calculate stresses and establish the reliability of the results obtained. (orig.)