On the Accuracy and the Method of Data Treatment for X-Ray Stress Measurement of 18Cr-8Ni Austenitic Stainless Steel

Abstract

The X-ray stress measurements were carried out on 18Cr-8Ni austenitic stainless steel specimens with different half-value breadths by the fixed ψ₀ and ψ₀ oscillation methods with CrKβ γ(311) diffraction. The peak position of the diffraction profile was determined by several methods, such as the half-value breadth method, the parabola fitting method and the center of gravity method by a computer and the accuracy of stress measurement was examined. The results obtained were as follows:
(1) It is not desirable to determine the peak position of diffraction profile by the center of gravity method, from a viewpoint of the accuracy of the computation.
(2) When the data of X-ray stress measurements obtained by the fixed ψ₀ and ψ₀ oscillation method were treated by using the half-value breadth or the parabola fitting method with corrections for background and an absorption factor, the error was as small as that of the graphic half-value breadth method.
(3) The corrected value of the absorption factor obtained from the normal distribution curves instead of the diffraction profies was not necessarily the same with the experimental value.