Both surface unequal thickness removal-both surface x-ray diffraction method for residual stress measurement in a plate

As the exact theory of measuring the residual stress distribution in a plate by x-ray stress measuring method, there are surface irradiation method and back surface irradiation method of Doi-Sato, and one surface removal-both surface irradiation method and both surface equal thickness removal-both surface irradiation method of the authors. In this paper, the theoretical equations for the measurement of residual stress distribution by both surface irradiation method are proposed for the case of removing thin layers of unequal thickness successively from both surfaces. The theoretical equations for the above mentioned conventional methods can be derived as the special cases of these theoretical equations. As an example of the application of this theory, a heat-treated saw material (SKS 51) was used, and the residual stress distribution was measured. The theory of measurement and the example of application are reported. The features of this theory are that differential terms are not included in the equations, and the calculation errors become very small. If the thickness of removal from both surfaces is different, the calculation errors can be eliminated by applying this theory. (Kako, I.)