鋳鉄の黒鉛組織とクレージング性との関連について

抄録

  The author has studied the crazing characteristics of gray cast iron in terms of the thermal stress fatigue. As it is well known that the destruction of cast iron is closely related to graphite structure, it was considered that the formation of crazing also depends on the graphite structure of cast iron.
  Thus, this study was undertaken to find out the effects of graphite on the crazing characteristics of the material. For this purpose, several materials with different graphite conditions (content, shape and structure of graphite) were examined. The results are summarized as follows:
  (1) With respect to the content of graphite in the material, the crazing was broad, deep, long and straight in the material with no-graphite, but narrow, shallow, short and like the pattern on a tortoise-shell in the material containing graphite with a good resistance to crazing compared to the material with no-graphiite.
  (2) Of the materials containing graphite, that containing flake graphite showed good resistance to crazing compared to that containing nodular graphite.
  (3) On the relation between the flake graphite structure and crazing characteristics of gray cast iron, it was observed that the resistance to crazing improved with increasing graphite area in cross-sectional area, length of flake graphite, number of flake graphite and magnitude of notch-effect due to flake graphite, while it became worse with increasing average distance of the flake graphites.
  (4) It has become clear by this study that there is a close relation between the graphite condition and crazing characteristics of cast iron.