Abstract
The double-repeated rotating bending fatigue tests of 18-8 austenitic steel were carried out at room temperature, 400°C, 500°C and 600°C.
The main conclusions arrived at are as follows.
(1) Remarkable surface temperature rise is measured during the fatigue tests of solution-treated 18-8 austenitic steel. Its behavior has the same tendency as that of the deflection of the specimens during the fatigue tests.
(2) Generally, cumulative cycle ratio Σ(n/N) is larger than one when the secondary stress level σ2 is higher than the primary stress level σ1. However, the effect of stress sequence on Σ(n/N) is not observed at 600°C, nor is it observed at any temperature when the cycle ratio of the primary stress level n1/N1 is 0.25.
(3) The relation between Σ(n/N) and the surface temperature and deflection during the double-repeated fatigue tests are as follows. When σ1<σ2, the surface temperature and deflection under the secondary stress level σ2 are smaller than those under the constant stress σ2 of the same level. When σ1>σ2, the former is larger than the latter. When the stress sequence have not an effect on Σ(n/N), the former is much the same as the latter.
