Influence of Homogenization on Phase Transformations during Isothermal Aging of Inconel 718 Superalloys Fabricated by Additive Manufacturing and Suction Casting

The attainment of the desired strength Inconel 718 superalloy heavily relies on isothermal aging process, which plays a critical role in achieving anticipated hardening effect. Surprisingly, there remains dearth dedicated studies investigating influence homogenization phase transformations during leaving gap knowledge required to guide design post-heat treatment strategies. Addressing this gap, our work investigates impact time at 730 °C alloys produced via additive manufacturing (AM) and suction casting (SC) methods. Intriguingly, we observe contrasting behaviors particle size γ″ γ′ aged samples, depending alloy processing method. Specifically, AM alloys, extended leads an increase γ′, whereas opposite trend is observed SC alloys. Furthermore, despite undergoing same heat treatment, exhibit smaller sizes but higher precipitate number densities compared resulting superior hardness. Notably, pronounced grain refinement evident 1 h homogenized samples under 1180 °C, warranting further investigations into underlying mechanisms. This study elucidates crucial attaining microstructure following subsequent processes. Moreover, it offers novel insights for developing strategies superalloys.