Other Standards for Neutron Diffraction Residual Stress Analysis

The NQL was built upon previous standardisation projects. The Versailles Agreement on Advanced Materials and Standards – Technical Working Area 20 (VAMAS TWA20) is among the first efforts to establish neutron diffraction as a non-destructive residual stress measurement technique. The project was created in 1996 with specific objectives of: i) establishing residual stress measurements by neutron diffraction; ii) inter-laboratory comparison to establish reproducibility, and iii) to draft a measurement standard. A number of ‘Round Robin’ investigations of residual stress were performed, involving 19 laboratories around the world. The report concluded that a very satisfactory agreement among the participating neutron diffraction facilities was obtained for neutron diffraction residual stress analysis.  The link to the report can be found here [TODO: link to vamas shrinkfit-plug report].

The ISO 21432:2019(en) Non-destructive testing – Standard test method for determining residual stresses by neutron diffraction represents the “good practice” guide of how to perform neutron diffraction residual stress analysis. The document provides the summary of the method, basic terminologies, and general guidance on how to perform the measurement, data analysis, and reporting the measurement results. The link to the document can be found here.

Advancing from the two previous standardisation projects, which were focused on establishing the technique and creating the standard of the measurement, the NQL take the next step of providing practical guidance on how to ‘certify’ the instrument setup to meet the critical requirements for residual stress analysis.