Planar-Biaxial Thermo-mechanical Fatigue Behavior of Nickel-Base Superalloy Inconel 718 Under Proportional Loading

Abstract

The planar-biaxial thermo-mechanical fatigue behavior of nickel-base superalloy Inconel 718 was studied for selected proportional loading conditions, in particular biaxial strain ratios of 1.0, 0.6, and − 1.0. The cyclic temperature loading with minimum and maximum temperatures of 400 °C and 630 °C and a duration of 250 seconds was either In-Phase or Out-of-Phase to the mechanical axes. Besides the multiaxial tests, uniaxial thermo-mechanical fatigue tests were conducted In-Phase and Out-of-Phase with the same temperature cycle and cycle duration. The performed thermo-mechanical fatigue tests were analyzed regarding the deformation and lifetime behavior and compared with high-temperature isothermal low-cycle fatigue tests from a previous work of the authors. On the side of the lifetime description, a strain- and a stress-based approach were presented. For the planar-biaxial tests, the crack initiation mechanism and crack paths were shown.

Full-field analysis of damage under complex thermomechanical loading

“…Thus, simultaneous measurement of temperature by IRT and local displacement by DIC will help in improving these aspects. As compared to the state-of-the-art where most of authors have tried to decrease temperature gradient in biaxial TMF facilities [32,56], the present study takes advantage of these gradients.…”