Three-dimensional investigation of steady state fatigue crack closure via high-resolution synchrotron X-ray microtomography

摘要

Fatigue crack closure investigation by surface analysis techniques can not provide enough information in the interior of metals. High resolution X-ray microtomography provides a valuable opportunity to investigate crack closure happened between the specimen's free surface and the interior region. The purpose of the present research is to investigate fatigue crack closure behavior and their mechanisms by detailed three-dimensional characterization. In situ microtomographic observation of fatigue crack propagation in Al-Mg-Si series aluminum alloy was performed at SPring-8 (JASRI). Radiographs were recorded during 180 deg rotation of the specimen when the crack grew to a suitable size. The tomographic scans were obtained for different crack extension. The radiographs were then reconstructed to obtain high-resolution three-dimensional image by the convolution back-projection algorithm.