Abstract
The characteristics of fracture surface of flake graphite cast iron were investigated by means of fractography in order to obtain informations needed for failure analysis. From the view point of the difference in fracture mechanism between fatigue and static bending, it was clarified that the both fracture could be distinguished by measuring the percentage of pearlite fracture surface.
The results obtained are summarized as follows:
(1) The fracture surface of fatigue and static bending consisted of graphite fracture, intergranular fracture and transgranular fracture of pearlite block. There was no difference in graphite fracture surface between fatigue and static bending.
(2) The intergranular fracture of pearlite block comprised the lamellar parts by fatigue and dimple pattern by static bending. Most parts of the static fracture surface of pearlite block showed a dimple-like pattern. Quasi-cleavage fracture surface was observed at both of the above fracture surfaces.
(3) The percentage of pearlite fracture surface by fatigue was 34-41% and that by static bending was 11-14%.
(4) It was confirmed that the statical fracture took a shorter path among graphites than the fatigue fracture did. This means that the former has smaller percentage of pearlite fracture surface than the latter.
