X-ray Investigation of Stress Measurement : On the Method of Measurement, the Effect of Radiation Area and Resolving Power

Concerned with the stress measurement by X-ray, several basic problems remain to be further investigated, for example, the correlation of the stress value obtained by X-ray method to that obtained by mechanical means. In the present paper, the practical signiflcance of applying sin2ψ method to stress measuring is emphasized and the influence of radiation area on the stress value by using both the film and the geiger counter methods for plate specimens of 0.07% and 0.55% carbon steel is discussed. (1) Stress measured by the film method is sufficiently exact under the test conditions employed by the authors. Measured stresses were in fairly good agreement with the mechanically induced ones. (2) In the case of the counter method applied to cold-worked or heat-treated specimens of carbon steels, it is found that the value of cosec θψ for the oblique incidence of 45°has the trend to deviate from the theoretical one owing to the absorption of X-ray by materials, causing asymmetricity of diffracted profiles. This tendency becomes more conspicuous as the radiation area is increased.