External reference samples for residual stress analysis by X-ray diffraction

摘要

The GFAC (French Association for residual stress analysis) decided in 2007 to work on external reference samples for residual stress analysis by X-ray diffraction as defined in the XPA 09-285 and EN 15305-2009 standards.Seven materials are studied: ferritic steel, martensitic steel, aluminium alloy, titanium alloy, 2 types of Nickel-Chromium alloy and tungsten thin layers deposited on silicon wafers.The purpose of this external round robin campaign is threefold: (ⅰ) to give possibilities for each laboratory involved in the campaign test to obtain external reference samples for each material tested, (ⅱ) to validate a common procedure for qualification of external samples and (ⅲ) to commercialise validated external reference samples through the GFAC association.A common approach of X-Ray diffraction parameters, samples geometry and standard procedure has been chosen and adopted by each laboratory involved in these tests.No indication in terms of residual stress calculation method is given;the choice of the method (centroid, middle point, maximum of peak, fitting...) is the choice of the laboratory according to their X-ray diffraction setups, softwares and experience.Once all samples are analysed, values given by each laboratory are compared and analysed.