Phenomenological and Physically Based Modeling of Flow Stress and Strengthening Mechanism of Inconel 718

Nickel‐based alloys are widely used in high‐temperature applications due to their excellent mechanical strength and oxidation resistance. However, properties such as high‐temperature strength and pronounced work‐hardening make them difficult to machine. In this study, the mechanical behavior and strengthening mechanisms of conventionally heat‐treated Inconel 718 alloy are investigated. Microstructural characterization is performed to identify and analyze the composition, morphology, and distribution of precipitates. Uniaxial compression tests are conducted at temperatures ranging from 20 to 1000C and strain rates from 0.002 to 20 . A phenomenological constitutive model based on the Johnson‐Cook formulation is developed to better describe thermal softening and temperature‐dependent strain rate sensitivity. The model is validated against experimental flow stress data, reducing yield strength deviations at 850C and strain rate of 0.002 from 88% to 13% and from 321% to 7% at 1000C. In addition, a physically based MatCalc model is used to simulate precipitation kinetics, yield strength, and flow stress. Overall, this study introduces an integrated experimental‐computational framework that combines microstructural characterization with a physically based model and an improved flow stress model, enabling a more accurate and comprehensive understanding of the deformation and strengthening mechanisms of Inconel 718 under extreme thermomechanical conditions.