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

该学院早期职业发展（CAREER）项目旨在产生建立新型混合原位轧制增材制造（HI-RAM）工艺所需的新知识。基于熔融的金属增材制造采用高能热源通过逐层工艺制造三维（3D）金属和金属基部件。尽管密度高，但增材部件在机械性能方面具有固有的局限性，例如各向异性和低延展性，这将显著阻碍它们在关键结构应用中的使用。为了解决这些限制，本项目将进行基础研究，以实现变革性的制造工艺-HI-RAM。这种新工艺在增材制造工艺中采用了原位热机械热轧工艺，其中微型辊跟踪热源并滚动沉积的金属珠。HI-RAM制造的高性能结构部件可以增加许多行业对3D打印金属部件的采用，因此HI-RAM可以显着提高美国制造业的领导地位。该项目将与大学、高中、当地制造商和制造组织建立伙伴关系，提供与HI-RAM相关的专业培训，旨在激励和培养高素质的制造业劳动力。该项目涉及多个学科，包括先进制造、材料科学、结构力学和应用数学，并有望扩大妇女和代表性不足的少数民族的参与，加强STEM教育。HI-RAM技术可以通过消除各向异性、改善延展性和增加强度，通过再结晶诱导的织构消除和晶粒细化的机制来显著改善添加剂金属的机械性能。将建立一个新的3D多物理仿真平台来研究动态再结晶机制，这将是第一个准确有效地捕捉变形增强3D打印中热-机械-冶金关系的模型。该项目将解决动态再结晶和增材制造的非平衡特征与原位塑性变形之间关系的知识空白。它将探索策略，以获得均匀的再结晶在打印织构组织，使用轧制参数，轧辊轮廓，以及循环和累积的过程条件。此外，该项目将研究关键的多物理现象，以保证工艺性能，如激光-材料相互作用，固化，晶体塑性和再结晶。虽然这项研究的重点是有前途的原位热轧和激光定向能量沉积工艺，但研究成果和制造方法将为不同的金属增材制造工艺和微观成形工艺提供信息。该项目由先进制造计划和激励竞争研究的既定计划（EPSCoR）共同资助。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.