Experimental investigation on low cycle fatigue and creep–fatigue interaction of DZ125 in different dwell time at elevated temperatures

The low cycle fatigue (LCF) and creep–fatigue tests have been conducted with directionally solidified nickel-based superalloy DZ125 at 850 and 980 °C to study the creep–fatigue interaction behavior of alloy with different dwell time. On the average, the life of creep–fatigue tests are about 70% less than the life of LCF tests under the same strain range at 850 °C. The life of creep–fatigue decreases as dwell time increases, but the life of this alloy was almost unchanged when dwell time exceeds a critical value at 850 °C. Scanning electron microscope (SEM) analyses of the fracture revealed that the fracture modes were influenced by different way of loading. In case of LCF, the primary fracture mode was transgranular, while in case of creep–fatigue, the primary fracture mode was mixed with transgranular and intergranular. There were also obvious different morphologies of surface crack between LCF and creep–fatigue.

Research highlights▶ This paper has researched creep–fatigue interaction of directionally solidified superalloy DZ125 with different dwell time at high temperature combined with micro-mechanism by experiment. ▶ The results indicated that the life of creep–fatigue decreases as dwell time increases, but the life of this alloy was almost unchanged when dwell time exceeds a critical value at 850 °C.