Ultra-high Strength Inconel 718 Alloy Produced by a Novel Heat Treatment

In order to ameliorate microstructure and optimize properties of Inconel 718 alloy, a novel heat treatment method combining high-temperature ultra-short annealing at 980 degrees C for 1 min with subsequent double aging was proposed. The results showed that ultra-short annealing generated partially recrystallized microstructure and recrystallized nuclei were formed even in deformed grains, which was confirmed by KAM maps. Therefore, high-temperature ultra-short annealing overcame recrystallization barrier, and the subsequent recrystallization process could be completed during aging treatment with relatively low temperature, resulting in the uniformly refined microstructure (similar to 3.59 mu m). The 980-1min-aged sample exhibited outstanding tensile properties. The room temperature ultimate strength and total elongation were 1600 MPa and 19%, respectively. The corresponding values of high- temperature (650 degrees C) tensile tests were similar to 1350 MPa and similar to 26%. Consequently, ultra-short annealing can be a promising route to enhance the properties of Inconel 718 alloy.