Newly Developed X-Ray Stress Analyzer by Using a PSPC

It is expected that the application of PSPC for X-ray stress analysis will realize high speed versatile measurement which is beyond the capacity of any conventional apparatus. But at present stage, the total time for the X-ray stress measurement is not improved so much, even if a PSPC detector is installed on a conventional goniometer. This is mainly due to the fact that the PSPC system is too sensitive to mis-setting for a consentional goniometer to obtain a diffraction profile with sufficient accuracy. In order to overcome this difficulty, the authors have developed a new goniometer without a fan-shaped X-ray tube guide. The features of the system are summarized as follows. (1) The movement of an X-ray tube is achieved by a X-Y-ψ table, each axis of which can be controlled independently. (2) The distance between a goniometer and specimen can be measured by means of a displacement tranceducer using lazer beam. For the purpose of determining a method for measuring the peak shift of diffraction profile obtained through PSPC, a series of Monte Carlo simulation has been performed. It was made clear that we can evaluate stress whose standard diviation is less than 20MPa, if the data is sampled at the condition that the S/N ratio is larger than 9. The X-ray stress constant obtained through bending tests on annealed and 2.5% strained low carbon steel plates was about -300MPa/deg.