Crack Growth Studies in a welded Ni-base superalloy

Paper in proceeding, 2017

It is well known that the introduction of sustained tensile loads during high-temperature fatigue (dwell-fatigue) significantly increases the crack propagation rates in many superalloys. One such superalloy is the Ni-Fe based Alloy 718, which is a high-strength corrosion resistant alloy used in gas turbines and jet engines. As the problem is typically more pronounced in fine-grained materials, the main body of existing literature is devoted to the characterization of sheets or forgings of Alloy 718. However, as welded components are being used in increasingly demanding applications, there is a need to understand the behavior. The present study is focused on the interaction of the propagating crack with the complex microstructure in Alloy 718 weld metal during cyclic and dwell-fatigue loading at 550 °C and 650 °C.