Investigation of Low Cycle Fatigue at Elevated Temperatures : Dependence of Behavior of Fatigue Cracks on the Conditions of Temperature and Plastic Strain Range

In order to investigate how mechanical and temperature conditions influence low cycle fatigue fracture, it is necessary to give attention to the process of fatigue fracture. The behaviour of fatigue cracks was observed in order to clarify the process of fatigue fracture. Fatigue tests were carried out using a AISI 321 stainless steel by a push-pull testing machine. According to the present experimental results, it is clarified that when fatigue tests are carried out under the same plastic strain range but different temperature conditions, the similar state of cracks are observed, provided the same ratio of number of repeated cycles to the number of cycles to fracture is given. Thus, it is concluded that the process of the low cycle fatigue fracture are influenced mainly by the plastic strain range, and that the rate of fatigue fracture depends on temperature.