Papers by Keyword: Stress Determination

Abstract: The presence of residual stresses in thermal oxide layers has been recognized for a long time. In the present work, the mechanical fields for chromia oxide are determined either by XRD or Raman spectroscopy. In addition, the microstructure of the chromia films is investigated ant its influence on the evolution of the stress release processes is analyzed.

Abstract: At the HARWI II beamline at the GKSS outstation at DESY a new experiment for position sensitive diffractometry and tomography called DITO was built and commissioned this year. Due to the available high energy synchrotron radiation with photon energies up to 100 keV it is possible to investigate the bulk of metallic samples of a few mm thickness with both methods. The diffractometry detector allows the investigation of the phase composition as well as phase sensitive determination of residual stresses with a spatial resolution of 6 μm while the tomography detector can either measure a whole tomogram in high resolution mode with a spatial resolution of 2 μm within 3 to 4 hours or in high speed mode recording a whole tomogram within 15 seconds with a spatial resolution of 40 μm.

Abstract: The non-destructive and phase selective determination of residual stresses caused by material processing (such as welding) in polycrystalline samples is usually performed by diffraction methods. In order to obtain information about stress fields at high spatial resolution with conventional methods, for example with micro beam techniques, the sample needs to be scanned in a very time consuming manner. A much faster method is the simultaneous investigation of a larger area using position sensitive diffractometry. This method was used for the analysis of the residual stress distribution in laser beam welded thin (2 mm and 3 mm) magnesium sheets.