Application of Image Plate to X-Ray Stress Measurement of Surface Thin Layer

Abstract

In this study, the authors made an experiment to observe the residual stress state in the surface of the engineered parts (for example, shot-peened steel) by X-ray stress measurement. An evaluation method was proposed for the stress gradient from the information on the X-ray Debye ring obtained with an area detector. The method utilized the fact that the X-ray penetration depth is a function of the central angle of the Debye ring α. It varies due to a section of Debye ring. It also depends on the incidence angle of X-rays and the wavelength used. Mean stress over the whole penetration depths of X-rays, which is defined as the Laplace stress, was measured by the cosα method[1, 2] by using this characteristic, and the real space stress[3-5] gradient was evaluated.