Balancing High-Temperature Strength and Ductility in INCONEL® 718 Superalloy

This paper investigates how temperature influences the balance between strength and ductility in the nickel-based superalloy INCONEL® 718. Using mechanical-property data from the Special Metals technical bulletin and NASA Contractor Report NASA-CR-268 (1965), empirical models are developed to describe how yield strength and elongation degrade at elevated temperatures. These trends are visualised through analytical plots to identify an optimal temperature range between 900 K and 970 K, where both properties remain stable. The analysis links macroscopic mechanical behaviour to microstructural phenomena such as γ′′ coarsening and δ-phase boundary formation, demonstrating how controlled heat treatment preserves mechanical integrity in aerospace components.