焼なまし材と調質材の疲労寿命のばらつき特性
1992 年 41 巻 469 号 p. 1499-1505
詳細
1992 年 41 巻 469 号 p. 1499-1505
In order to investigate the physical basis of scatter in fatigue life, rotating bending fatigue tests of smooth specimens were carried out using two steels with different microstructures. 16 or 18 specimens were fatigued at each stress range, and the initiation and propagation behaviors of a crack which led to the fracture were examined for all the specimens. The fatigue data exhibited a large scatter in fatigue life Nf at a stress near the fatigue limit. The scatter in Nf is controlled by the behavior of a microcrack, namely it is controlled by the scatter in N0.3 for an annealed steel and N0.1 for a heat-treated steel, where N0.3 and N0.1 are the number of cycles to attain a crack length of 0.3 and 0.1mm, respectively. On the other hand, after the crack became 0.3 or 0.1mm, the propagation life exhibited small scatter, and its scatter was hardly affected by the stress range. To estimate the scatter characteristics quantitatively, the statistical treatment of fatigue data was performed by assuming a Weibull distribution.
