レール鋼の繰返し打撃による塑性変形挙動

概要

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Repeated impact blows given by a passing train to the joints cause plastic flow on a rail head, sometimes resulting in its fatigue fracture. To cope with this phenomenon, the End-Hardened rail (EH rail) has come to be widely used. Though the effectiveness of this kind of rail has been confirmed by field test, the characteristics of plastic flow by cyclic impact blow have not been clarified yet. In this study, cyclic impact blow test and low cycle fatigue test have been performed using 0.75%C steels with different hardness and structure. The results are summarized as follows : 1) The deformation caused by cyclic impact blow in the pearlite structure is larger than in the tempered martensite one. In the case of tempered martensite structure, there occurs a cyclic softening at an early stage of the deformation in cyclic impact blow test. On the contrary, there occurs only hardening in the case of pearlite structure. 2) Dislocation structures in cyclic impact blow test change remarkably with the distance from the impact surface. Further, fatigue behavior in cyclic impact blow test can be estimated almost from the result of low cycle test.
社団法人日本鉄鋼協会の論文
1988-09-01