Abstract:Due to the gradually prominent impact of fracture characteristics and serrated yielding in the application of nickel-based superalloys, the hot tensile properties of Inconel 718 superalloy were studied, including fracture behavior, mechanical properties, and plastic behavior. The experiments adopted three heat treatment regimes and two tensile directions. Results show that various heat treatments make grain sizes different. The larger-sized grains make the vertical surface uneven, which also decrease the number of grain boundaries and carbides, restricting the occurrence of dimples and ultimately reducing the material plasticity. The reduced grain boundaries can decrease dislocations, increase the demand for thermal activation energy, and transform the serration mode of serrated yielding. In addition, various heat treatments also make precipitates different. Carbides can promote the formation of dimples. The needle-shaped δ phase precipitates at grain boundaries and twin boundaries, and slightly inclines towards the rolling direction. Therefore, its pinning effect is outstanding along the transverse direction, which can affect the dimple aggregation and the dislocation movement, ultimately exhibiting anisotropy in fracture characteristics, mechanical properties, and serrated yielding.