抄録
The fatigue strength of cyclic hardening materials under constant mean stress condition increase when the maximum stress becomes larger than the yield stress and cannot be estimated accurately based on the fatigue limit / strength estimation method proposed previously (e.g. Modified Goodman's curve). In this paper, the fatigue tests of SUS316NG and SM400 steels as cyclic hardening materials are carried out under constant mean stress condition and the relationships between fatigue strength and failure life are obtained. From the test results, it is shown that the difference between modified Goodman's estimation and fatigue test result changes linearly with the increase of maximum stress. Then, the approximate equation for the relationship between the difference and maximum stress is derived. By using the approximate equation for evaluating the difference and the results of modified Goodman's estimation, it is shown that the fatigue strength of cyclic hardening material under constant mean stress condition can be estimated with practically sufficient accuracy.
