厚肉球状黒鉛鋳鉄のX線CTによる3次元黒鉛組織観察

抄録

  The morphologies of various abnormal graphite can be observed in heavy-section spheroidal graphite cast iron, which are not found in thin-section spheroidal graphite cast iron. For example, chunky graphite that crystallizes as the eutectic solidification time becomes longer is a typical abnormal graphite structure, and it is known to reduce the fatigue strength, tensile strength, and elongation in spheroidal graphite cast iron. Papers on anomalous graphite have been reported, in many cases observing two-dimensional cross-sections with an optical microscope, but few reports have focused on the overall three-dimensional structure. In this study, heavy-section graphite cast iron with different wall thicknesses is imaged by high-resolution X-ray CT, and the three-dimensional structure of graphite is observed to clarify the characteristic structural differences and formation process of chunky graphite, etc. As for the volume fractions of graphite structures, when the eutectic solidification time increases, the graphite nodule size becomes coarse. In addition, when the graphite nodule size increases from 60μm to 67μm or more, the shape of the graphite becomes more complex.