French round-robin test of X-ray stress determination on a shot-peened steel

A round-robin test of X-ray residual stress determination was performed by the Groupement Francais d'Analyse des Contraintes and involved 16 laborator ies. The standard deviation of the measurements was about 36 MPa, but a pos ttreatment of the raw data with the same software reduced the dispersion to 19 MPa. Analysis of the uncertainty sources (goniometer alignment, operato r. counting statistics, nonlinearity of the material, etc.) revealed that t he main sources come from the data treatment and the operator.