高分解能4Dイメージングによる球状黒鉛鋳鉄の疲労挙動解析

抄録

  Recently, observation of iron materials at high spatial resolutions close to theoretical values, which has been difficult with conventional synchrotron X-ray tomography, is being realized by high resolution 4D imaging. In the present study, the applicability to 4D imaging (i. e. consecutive capturing of 3D images) was investigated, and the method was experimentally applied for investigating the fatigue crack propagation behavior of spheroidal graphite cast iron. The shape and spatial distribution of graphite nodules and 3D morphologies, opening displacement and crack growth rate of cracks were measured together with crack-tip strain mapping. Significantly complex shapes of graphite nodules and cracks were observed.

  The fatigue crack was found to propagate while absorbing graphite nodules successively. Its growth behavior is affected strongly by stress shielding/anti-shielding effects. The strain distribution around the crack-tip appears to be discontinuous and heterogeneous. The physical mechanisms of three-dimensionally complex crack propagation behaviors are discussed on the basis of these images and quantitative information.