Measurement of internal strain in materials using high energy synchrotron radiation white x-rays

This paper presents a basic research on a measurement of strain in the bulk of materials by using high energy white X-rays from a synchrotron radiation source of SPring-8. WEL-TEN780E (JIS G3128 SHY685) whose grain size was 13 μm was used as a specimen shaped into G type. The specimen was loaded with bending. The white X-ray beam, which has a height of 50 μm and width of 300 μm, was incident in the specimen with the Bragg angle θ of 5degree. Bending strain at the surface of specimen was measured by a strain gauge. The strain in the loading direction of the specimen was obtained directly from a rate of change of peak energy of transmitted X-rays through the thickness. As a result, the internal strain of SHY685 of 5 mm thickness could be evaluated using white X-rays which range of energy from 60 keV to 150 keV. It is suitable for the measurement with sufficient accuracy to include more than or equal to 5000 grains of crystal in the gauge volume. The measurement error of strain could be decreased by using the diffracted X-rays with high energy. Furthermore, the measurement with a high degree of accuracy was accomplished using α-Fe321 diffraction in this material. The results showed that the high energy white X-ray is effective for internal strain measurements. (author)