Hot-stage microscopy and tensile test of Haynes® 282® superalloy

Investigating the high-temperature microstructure development and failure mechanisms of superalloys is critical for designing their fabrication routes and defining their application temperatures and load limits. In this study, we synchronized various thermomechanical cycles with the high-temperature microstructural development and failure mechanisms of Haynes® 282® alloy using hot-stage scanning electron microscopy and in-situ tensile testing. In addition to micrographs, video recordings were acquired to provide unique insight into the material behavior at temperatures up to 920℃. The formation of grain boundary carbide films was monitored, and the increase in their thickness was quantified at an identical location after different aging durations at 920℃. Results showed that a pre-strain of 3.5 % at room temperature increased the ultimate tensile strength and elongation during hot tensile testing at 920℃ compared to a sample with no pre-strain. Across the thermomechanical conditions studied, the failure sequence consistently progressed as follows: void formation at triple grain boundaries, grain boundary sliding, carbide-matrix separation, fracture of blocky carbides, transgranular crack propagation, and crack formation in twin boundaries. Void formation adjacent to precipitates and the presence of intersecting slip lines at the crack front within grains were also observed. We demonstrated that combining in-situ hot tensile testing with high-resolution microscopy enables a deeper understanding of microstructure evolution and failure mechanisms of superalloys compared to ex-situ characterization after thermal exposure and/or failure. Future studies should integrate in-situ and ex-situ electron backscattered diffraction to establish a direct correlation between the deformation and failure mechanisms with crystallographic characteristics. • Hot-stage microscopy with in-situ tensile test was performed on Haynes 282. • Carbide formation and γ' coarsening were observed at 920 ℃. • Different materials’ failure mechanisms were observed during testing. • The method showed high potential for studying deformation and rupture.