A new perspective on the mechanical behavior of Inconel 617 at elevated temperatures for small modular reactors

This study investigates the temperature-dependent mechanical properties of Inconel 617, a nickel-based superalloy, for small modular reactor applications. The formation of the sigma phase, driven by high chromium content during prolonged high-temperature exposure, significantly impacts the alloy's strength, creep resistance, stress rupture life, and ductility. The transition temperature for sigma phase formation is predicted to be approximately $1064{}^{\circ }\text{C}$, with an uncertainty range between $700{}^{\circ }\text{C}$ and $1250{}^{\circ }\text{C}$, confirmed through an uncertainty analysis of elemental composition. Chromium is identified as the primary element influencing sigma phase stability. Additionally, hot tearing susceptibility during solidification is assessed, revealing that a carbon content of 0.08 wt% minimizes the cracking susceptibility coefficient to 0.425, reducing the risk of solidification cracking. These findings offer critical insights for optimizing the composition and processing conditions of Inconel 617 in laser-directed energy deposition additive manufacturing.