初析フェライトを含む層状パーライト鋼のぜい性破壊挙動に及ぼす前ひずみの影響について

概要

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The effect of prestrain on the transition behaviour of fracture in a lamellar pearlite steel containing free ferrites has been investigated by means of low temperature tensile tests. The results obtained are summarized as follows: (1) The types of initiation of microcracks can be divided into the following classes according to the temperature range. Below T_C, almost all of micro-cracks occur at the boundary of pearlite colonies (type A) and micro-cracks in the free ferrite(type B) are observed barely. Between T_C and T_B, only those of type A are observed. Both type A and type C, which represents micro-cracks grown into the pearlite colony from a boundary of pearlite colony and a free ferrite, are observed near T_B in the range between T_B and T_D・In the vicinity of T_D, transgranular micro-cracks in the pearlite colony (type D) are observed in addition to those of types A and C. (2) The non-ductile transition temperature rises with increasing prestrain. (3) When prestrained, the peak of the fracture stress-temperature curve near the ductile transition temperature becomes very weak. The fracture stress of the prestrained specimens is lower than that of the non-strained.
社団法人日本材料学会の論文
1979-11-15