Creep-fatigue life prediction using simple high-temperature low-cycle fatigue testing machines

Abstract

Several criteria have been proposed for the fracture caused by creep-fatigue interaction and many studies are still being made to verify the validity of these criteria. Most of the studies, however, are based on data obtained by short-time tests. A simple high-temperature low-cycle fatigue testing machine for long-time creep-fatigue tests has been developed and experiments on two kinds of Cr-Mo-V steel forgings and 304 stainless steel plate carried out. The experimental results indicate: (1) the data obtained by long-hold time tests deviate considerably from the linear damage fraction rule; (2) creep-rupture ductility seems to be one of the important factors affecting creep-fatigue life after long times; and (3) in the case of materials whose creep-rupture ductility shows a marked variation with time, Manson's ∆ε_cp—∆N_cp diagram may not become a single line.