Results of Interlaboratory X-Ray Stress Measurements

The data from five residual stress round robins run by the X-Ray Fatigue Division of the SAE Fatigue Design and Evaluation Committee have been studied. Many factors affecting precision have been isolated during 16 years of testing. Some of these relate to the sample?material hardness and geometry- while others, such as alignment, are instrumental or procedural. Laboratories using proper techniques can achieve an interlaboratory standard deviation of 2.5 ksi on a stressed, hardened steel cylinder.