2021 年 59 巻 2 号 p. 52-60
There is a good correlation between the S-N curve and crack growth law in carbon steel. Also, the fatigue limit of that can be evaluated from the param-eters of hardness and crack initiation conditions. The crack initiation behavior is related to the distribution of microstructures and the sizes of inclu-sions. Therefore, when the fatigue limit and life of carbon steel are predicted, it is better to consider the initial crack length and crack growth behavior. In this study, one such case was investigated by push-pull with constant stress amplitude by using 0.45% carbon steel. The initial crack lengths were varied with the specimen used and testing conditions. The prediction method of the S-N curve from a corrected crack growth law in such case was pro-posed. Also, a method of prediction of fatigue limit and life from the point of safety was discussed in this study.