Due to the gradually prominent impact of fracture characteristics and serrated yielding in the application of nickel-based superalloys, this paper explores the hot tensile properties of Inconel 718 superalloy, including fracture behavior, mechanical properties, and plastic behavior. The experiments adopted three heat treatments and two tensile directions. Results show that various heat treatments make grain sizes different. The major-sized grains make the vertical surface uneven. They also decrease the number of grain boundaries and carbides, limiting the occurrence of dimples and ultimately reducing the material plasticity. The decreased 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 provide occurrence occasions for dimples. The needle-shaped δ phase precipitates at grain and twin boundaries and slightly inclines towards the rolling direction. Therefore, its pinning effect is outstanding along the transverse direction. It can affect the dimple aggregation and the dislocation movement, ultimately exhibiting anisotropy in fracture characteristics, mechanical properties, and serrated yielding.