Correction of Surface Aberration in Strain Scanning Method with Analyzer
Takahisa SHOBU, Junichiro MIZUKI, Kenji SUZUKI, Yoshiaki AKINIWA and Keisuke Tanaka
Abstract:When a gauge volume sank below a specimen surface, the diffraction angle shifts. Thus, it is required to correct the surface aberration. For the annealed specimen of S45C, the shift in the diffraction angle was investigated using a strain scanning method with Ge (111) analyzer. This phenomenon was caused by the difference in the centroid between the geometric and the instrumental gauge volumes. This difference is explained by the following factors; 1) the change in the gauge volume by the divergence of the analyzer, 2) the X-ray penetration depth, 3) the gap of the centre line between the double receiving slits due to mis-setting the analyzer. As a result, the correcting method considered into these factors was proposed. For the shot-peened specimens of S45C, the diffraction angles were measured and corrected by our method. The distribution of the residual stress agreed with that obtained by the removal method. Key Words:Residual stress, Hard synchrotron X-ray, X-ray stress measurement, Strain scanning method