| Abstract Scope |
This study investigates the correlation between microstructural features inherent to the alloy processing and the oxidation behavior of Alloy 625, and its subsequent impact on fatigue performance. Prior studies on the oxidation behavior of additively manufactured (AM) chromia-forming Ni-based alloys have shown enhanced degradation compared to their conventionally processed counterparts (i.e., faster oxidation kinetics, porous oxide scales, and deeper and higher fraction of intergranular oxidation), which can potentially affect fatigue performance. Our results, consistent with existing literature, reveal similar trends after isothermal oxidation of AM Alloy 625 samples at 800 and 950 °C. The high cycle fatigue tests of oxidized samples revealed a shorter lifespan for AM samples compared to wrought due to earlier crack initiation. A proposed mechanism for crack initiation shows the synergetic correlation of the intergranular oxidation with associated voids, buckling, and deeper depletion region. |