Low cyclic fatigue fracture of a single crystal superalloy

Single crystal base superalloy are being used in advanced gas turbines because their mechanical properties are superior to those of polycrystalline superalloys. Low cycle fatigue (LCF) has significant effect on the life of a component of a machine and it is an important limiting factor for design life of components. Investigation of LCF behavior of single crystal superalloys is essentially required. LCF behavior of a single crystal superalloy DD has been investigated. Variation of stress amplitude with number of cycles for samples fatigue tested with a strain of 0.66% in fully reversed (R--1) total strain control mode at 850 deg. C has been compared with that at ambient temperature. Fractured surfaces have been examined in the scanning electron microscope. In the present paper, experimental results are presented and discussed. (author)