Mechanisms of Fatigue Endurance in Alloy 617M at Different Temperatures (300-1023 K)

The present study aims at understanding the mechanisms of fatigue endurance through high-cycle fatigue (HCF) behavior of Alloy 617M at varying temperatures, ranging from 300 to 1023 K. Dynamic strain aging (DSA) was a key feature observed in this alloy at high temperatures (853-973 K), which also affects the cyclic life as well as the endurance limit. Furthermore, in situ precipitation of Cr(23)C(6)and gamma ' phase (Ni-3(Al,Ti)) at 973 K during the course of HCF cycling is found to impart a beneficial effect on the HCF life of the alloy. AtT > 973 K, effect of creep damage was found to be prominent, resulting in a deteriorating effect on HCF life. The role of DSA, precipitation and creep on the fatigue damage is assessed through in-depth microstructural characterization of the tested specimens, which is further utilized to develop a damage map across the temperatures 300-1023 K.