Thermal Fatigue Combined with Static Mean Stress and Reversed Mechanical Stress

Abstract

In the present paper is discussed the relative comparison of the strength of AISI 347 stainless steel in thermal fatigue combined with the mean stress and the reversed mechanical stress with its strength in simple thermal fatigue, low cycle fatigue and static creep.
The analysis is compared with experimental results.
Conclusions obtained are as follows:
(1) The fracture life of AISI 347 stainless steel in thermal fatigue under the reversed mechanical stress can be predicted from the test results in low cycle fatigue at equivalent steady temperature. In the case of tensile stressing at upper temperature side, however, the fatigue life coincides with test result of low cycle fatigue at that temperature.
(2) The strength of the material in thermal fatigue combined stress, the reversed mechanical stress and the mean stress has been discussed analytically and experimentally. The lifetime is predicted from the low cycle fatigue data at equivalent steady temperature and the creep rupture data.
(3) The deformation of the specimen under stress cycling combined with the thermal stress, the reversed mechanical stress and the mean stress is larger than what is shown in the result of analysis on the time consumption hypothesis. In this case, it is necessary to consider the effect of stress history during one cycle.