The Influence of High-Temperature Helium and the Amount of Revert Material on the Material Properties of Inconel 738

Nickel-based alloys are considered promising materials for primary circuits of high-temperature gas reactors (HTGRs), specifically turbines. The helium (He) coolant in the gas-turbine-based HTGRs is expected to reach temperatures up 900 °C; therefore, selected should adequately perform over a long service life at such an environment. A manufacturing method production reactor components precision casting, where content revert (recyclate) material alloy differs and can influence behavior. In our study, Inconel 738 was manufactured by casting 50% 100% tested HTGR conditions examine on material’s properties. Tensile specimens were exposed °C 1000 h containing specified amount gaseous impurities. Scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), combination X-ray diffraction (XRD) nano-, microhardness methods, used characterization after performing tensile tests room temperature. presence three types layers observed: thin layer formed aluminum chromium oxides surface; non-uniform surface Ti3O5 inner (Al,Cr)2O3; fine-grained Cr-enriched phase (approx. 10–20 µm below surface), which act as protective layer. Mechanical properties both decreased exposure but did not show significant difference result material. increase nano-hardness line profiles throughout specimen’s cross-section observed locally precipitates grain boundaries. After exposure, Rp0.2 values 20% 17.7%, Rm 12.3% 20.8% samples 50 content, respectively. Furthermore, decrease (HV0.1) detected 4.98% longitude 5.80% 3.85% 7.86% It be concluded that have similar corrosion resistance conditions. presented results complement knowledge about degradation environment advanced gas-cooled reactors.