STRESS-ANALYSIS BY X-RAY-DIFFRACTION - ME ASUREMENT AND EVALUATION PROCEDURES AND THEIR CONTRIBUTION TO THE RESULTS

The quality of measured results depends not only on the definite accur acy but also on the expression of the uncertainty of measure ment. Fur thermore such a statement is recommended for an accredited laboratory. In the present paper the uncertainty of measurement in residual stres s analysis by means of x-ray diffraction is investigated for different samples, different evaluation methods and different data acquisition strategies. The uncertainties calculated by the computer turned out to have hardly no validity. The peak evaluation method which yields the smallest uncertainty was determined. The real uncertainty depends on t he given problem, on the data acquisition time and on the peak evaluat ion method. The selection of the different measurement options (number of psi-angles, step width, number of single measurements, etc.) is of secondary importance.