Determination of Alignment Errors in Classical XRD Residual Stress Methods

Abstract

A new method will be discussed for the determination and correction of alignment errors. It will be shown that for both commonly employed sin 2 psi techniques, omega-stress and psi-stress, the two relevant alignment errors (incident beam misalignment and specimen displacement) can be described with one formalism. The method is independent of the material investigated and the diffraction angle used for the residual stress analysis. Any stress-free reference sample will be suitable for the determination of the alignment errors. So, after applying the method proposed the diffractometer is useable for the whole 2theta range and for different sample materials. The remaining alignment errors as obtained with the method can be used for a software correction. Hence, re-alignment of the hardware is not necessary.