2相混合組織鋼の延性,破壊機構と組織因子との関わり

抄録

Fracture behavior of the steels with a ferrite-martensite and a ferrite-pearlite microstructure has been investigated with special attention to the relationship among ductility, fracture mechanisms and microstructures. A well known dependency of fracture ductility (ε_f) on the volume fraction of second phase (V_fs) found originally by Edelson was confirmed for each microstructure, but a marked difference in such a dependency was observed between those microstructures when the different fracture mechanisms are involved, indicating that a single relationship between ε_f and Vf_s appears only for the two phase microstructure in which the fracture mechanism is identical. A new concept of the fracture ductility surface has been proposed to explain the microstructural effects in fracture ductility of the two phase alloys. Using this concept, and interpretation was given to the scatter of the fracture ductility of present materials and to the dependency of ε_f on the morphology of microstructure and on the hardness ratio between the constituents in two phase microstructure.