CAREER: Understanding Dynamic Recrystallization Mechanisms in Hybrid In-situ Rolled Additive Manufacturing

This Faculty Early Career Development (CAREER) project aims to generate new knowledge necessary for establishing a novel, hybrid in-situ rolled additive manufacturing (HI-RAM) process. Fusion-based metal additive manufacturing employs a high-energy heat source to fabricate three-dimensional (3D) metal and metal-based parts through a layer-by-layer process. Despite the high density, additive parts have inherent limitations in mechanical properties such as anisotropy and low ductility, which will significantly hinder their use in critical structural applications. To address these limitations, this project will perform fundamental research to enable a transformative manufacturing process—HI-RAM. This new process incorporates an in-situ thermomechanical hot rolling process in the additive manufacturing process, in which a micro-roller trails the heat source and rolls the deposited metal bead. The high-performance structural parts fabricated by HI-RAM could increase the adoption of 3D printed metal parts by many industries, and thus HI-RAM could significantly enhance U.S. manufacturing leadership. This project will build partnerships with colleges, high schools, local manufacturers, and manufacturing organizations to deliver professional training related to HI-RAM, aimed at motivating and preparing a high-quality manufacturing workforce. The project involves multiple disciplines, including advanced manufacturing, materials science, structural mechanics, and applied mathematics, and also expects to broaden the participation of women and underrepresented minorities and strengthen education in STEM. The HI-RAM technology could drastically improve the mechanical properties of additive metals by eliminating anisotropy, improving ductility, and increasing strength, through the mechanism of recrystallization-induced texture elimination and grain refinement. A new 3D multi-physics simulation platform will be established to study the dynamic recrystallization mechanisms, which will be the first model to accurately and efficiently capture the thermal-mechanical-metallurgical relationship in deformation-enhanced 3D printing. The project will address gaps in knowledge about the relationships between dynamic recrystallization and additive manufacturing’s non-equilibrium features and in-situ plastic deformation. It will explore strategies to obtain homogeneous recrystallization in the as-printed textured microstructure, using rolling parameters, roller profiles, and the cyclic and accumulative process conditions. Additionally, this project will investigate the critical multi-physics phenomena to guarantee process performance, such as laser–material interaction, solidification, crystal plasticity, and recrystallization. While this research focuses on the promising in-situ hot rolling and laser-directed energy deposition process, the research outcomes and manufacturing methodology will inform different metal additive manufacturing processes and microscopic forming processes. This project is jointly funded by the Advanced Manufacturing Program and the Established Program to Stimulate Competitive Research (EPSCoR). This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.