セパレーションを発生する鋼板の疲労亀裂伝播速度について

抄録

Our previous paper made it clear that the fatigue strength was influenced by the angle between progressing direction of fatigue crack and ferrite-pearlite layer and the fatigue life tend to increase with the separation index. Furthermore, this paper deals with the fatigue crack propagation on the specimen with surface notch and the specimen with through thickness notch at room and sub-zero temperature, and shows the anisotropic effect of thickness direction in the TMCP steel plate with tendency to occur the separation. The results obtained are summarized as follows; (1) In the case of surface fatigue crack, the rate of fatigue crack propagation has a tendency to decrease with the separation index (2) The propagation of surface fatigue crack is obstructed by micro-separations in TMCP steel plate with tendency to occur the separation. (3) The effect of the separation on the rate of fatigue crack propagation in the direction of plate width is not recognized.