Abstract
The authors have applied micro computed tomography (μCT) with synchrotron radiation of SPring-8 to imaging of fatigue cracks in cast aluminum alloy AC4CH. Theoretical evaluation showed that the edge of a sample apart from an X-ray detector was enhanced in the radiographic image due to the refraction of X-rays. The edge enhancement was confirmed with 28keV monochromatic X-ray under the arrangement where the detector was set behind the sample by 800mm. The enhancement also appeared on the tomographic image reconstructed by FBP (filtered back projection) algorithm. The fatigue cracks were clearly observed in both reconstructed images of laser-peened and unpeened samples. The crack image of the unpeened sample was evidently larger than that of the laser-peened sample, which implies that laser peening retarded the fatigue crack propagation.
