Study on evaluation of internal stresses using area detector

An area detector technique has to be applied to the strain scanning method for the coarse grains. A new rotating slit system was designed for a 2-dimensional (2D) detector strain scanning method. The rotating slit system focuses the 2D detector on the center of the goniometer, and the gauge volume is made by the rotating slit system. The stress measurements were examined by the rotating slit and 2D detector. The measured diffraction spots shifted for the 2D strain scanning. The magnitude of the shift of the diffraction spot was very large as compared with the shift due to the strain. This phenomenon was caused by interaction between the gauge volume and the coarse grain. That is a coarse grain effect. To overcome the coarse grain effect, we propose a diffraction spot trace method (DSTM), which is constructed by the rotating slit and the PILATUS detector. The bending stress distribution of the coarse grain aluminum alloy was measured by DSTM. The agreement between the measured stress and the applied stress is very good. (author)