A Predictive Framework for Informing Hot Isostatic Pressing of Additively Manufactured Niobium: Connecting Process, Microstructure, and Strength

Abstract Hot isostatic pressing (HIP) is a critical post-processing step to ensure the reliability and performance of additively manufactured (AM) niobium (Nb) components for demanding aerospace and high-temperature applications. However, optimizing HIP cycles to maximize strength without relying on extensive and costly physical trials presents a significant industrial challenge. This work adapts a predictive phase-field modeling framework that directly correlates HIP process parameters of temperature and pressure to the final microstructure and mechanical strength of AM Nb, serving as a powerful tool for virtual process design. The simulation results provide quantitative guidance for manufacturing process design. The model demonstrates that applied pressure is a key lever for suppressing grain growth at high temperatures, thereby enhancing component strength. For instance, at a processing temperature of 1373 K, increasing the HIP pressure from 1 MPa to 100 MPa is predicted to boost the final yield strength by 5.70%. At a slightly lower temperature of 1273 K, the same pressure increase yields a significant 7.57% strength improvement. This critical link between processing, microstructure, and performance is established by coupling the predicted final grain size with the well-established Hall–Petch relation. This work enables manufacturers to reduce reliance on trial-and-error experimentation, accelerate the development of tailored heat treatment schedules, and reduce uncertainty in the final performance of critical components. The model establishes a foundation that can be extended to predict the behavior of more complex Nb-based alloys (e.g., C-103, Nb-1Zr), further enhancing its utility in the aerospace and advanced materials industries.