Round‐robin test for X‐ray stress analysis standards: Optimization for discrepancy reduction

Abstract

The aim of this paper is to shed some light on the discrepancy origins of a round‐robin test for X‐ray stress analysis in order to improve the specimen quality and to establish new guidelines for the coming works on set‐up certification. After a global overview of the return measurements and certificates, an original analysis method is proposed with a detailed study of the raw results emphasizing the most relevant uncertainties. It is shown that the standardization of stress calculus parameters widely reduces the inter‐laboratory discrepancy. A comparative analysis of the experimental patterns with some of the most common peak localization techniques also shows the importance of providing this information together with the stress values calculated even with quasi‐ideal cases such as shot‐peened aluminium alloy specimens. In this way, the value distributions can be easily fitted with a simple statistical law which allows the mean stress value to be considered as more representative.