Cyclic Behavior of Nickel-Based Superalloy 617 M at Elevated Temperature

Cyclic behavior of Alloy 617 M in forged condition at several strain amplitudes ranging from ± 0.25 to ± 0.8% was studied at test temperatures from 200 to 750 °C. Axial strain control tests were performed at strain ratio R = − 1. Cyclic stress response (CSR) curve was plotted for each testing condition. CSR showed initial cyclic hardening followed by saturation and sudden stress drop due to macroscopic crack generation for lower temperatures (200 °C), whereas continuous cyclic hardening followed by stress drop was observed at higher temperatures (> 200 °C). Higher hardening rate for ± 0.25% strain amplitude was observed especially at highest temperature. Dynamic strain aging phenomenon was distinctly observed at test temperatures above 650 °C. Upward shift of stress response with increasing strain amplitude was observed. Fractography study showed fine striation distributed over large area for ± 0.25% strain amplitude and extensive cracking for higher strain amplitudes; ± 0.6% and ± 0.8%. Strain life and Coffin–Manson plots were obtained.