Synopsis:

Scientists have harnessed the power of neutrons to delve into the additive manufacturing process at an atomic level, enabling the measurement of evolving strain in materials and tracking atomic responses to stress. This breakthrough, involving the OpeN-AM platform and Spallation Neutron Source at ORNL, provides invaluable insights into material behavior during manufacturing, offering the potential to tailor residual stress in components for enhanced strength, reduced weight, and complex shapes, benefiting various industries, including automotive, aerospace, and clean energy.

Article:

In a remarkable scientific advancement, researchers have leveraged the unique capabilities of neutrons to peer into the intricacies of additive manufacturing at an atomic level. This pioneering work has enabled the measurement of strain in materials as it evolves and the tracking of atomic movements in response to stress.

Lead scientist Alex Plotkowski, a materials scientist at ORNL's Materials Science and Technology Division, emphasized the widespread implications of this breakthrough: "The automotive, aerospace, clean energy, and tool-and-die industries, any industry that needs complex and high-performance parts, could use additive manufacturing." Their findings were reported in Nature Communications.

The innovation behind this development is the OpeN-AM platform, a 3D printing system that can gauge evolving residual stress during manufacturing. This platform is used in conjunction with the VULCAN beamline at ORNL's Spallation Neutron Source (SNS), a Department of Energy Office of Science user facility. When combined with infrared imaging and computer modeling, this setup offers unprecedented insights into material behavior during the manufacturing process.

In this specific study, low-temperature transformation (LTT) steel was used as the material of interest. The researchers physically measured how atoms responded to stress, whether caused by temperature or load, employing the OpeN-AM platform. Residual stresses, those that persist even after the stress-inducing factor is removed, can deform materials or lead to premature failure. Managing these stresses is a crucial challenge in manufacturing components with desired properties and performance.

What makes this development even more remarkable is the potential it offers to manufacturers. They can now customize residual stress in their components, enhancing their strength, making them lighter, and allowing for more intricate designs. This technology can be applied to a wide range of manufacturing needs.

The experiment, which spanned two years, resulted in the development of a system that can measure strain in materials as they evolve, providing critical insights into how stresses are distributed. The implications of this achievement are significant, as it enhances the understanding of material behavior during the manufacturing process.

Furthermore, the scientists behind this achievement received a 2023 R&D 100 Award for their work. The recognition from R&D World magazine highlights the importance of this innovation, and the winners will be honored at an award ceremony in San Diego on November 16.

The research involved the use of a custom wire-arc additive manufacturing platform, conducting operando neutron diffraction on LTT metal at SNS. By processing the steel and collecting data at various stages during manufacturing and subsequent cooling to room temperature, the researchers were able to combine diffraction data with infrared imaging for verification. The platform was designed and built at the Manufacturing Demonstration Facility (MDF), a DOE Advanced Materials and Manufacturing Technologies Office user consortium.

The SNS operates a linear particle accelerator that generates neutron beams for atomic-scale material analysis. The research tool developed by the scientists allows them to observe the inner workings of materials in real-time as they are being produced.

The experiment focused on LTT steel, which undergoes a phase transformation as it cools. During this transformation, atoms rearrange, taking up different space and altering the material's behavior. Observing these transformations during processing provides critical insights into their understanding and manipulation.

"We want to understand what these stresses are, explain how they got there, and figure out how to control them," Plotkowski stated. The results of this study offer a new path to designing desirable residual stress states and property distributions in additive manufacturing components.

The significance of this research extends beyond the laboratory, as it invites scientists from around the world to ORNL to conduct similar experiments on metals intended for use in manufacturing.

This pioneering research was funded by ORNL's Laboratory Directed Research and Development program, which supports high-risk research and development with the potential for high value in national programs.

In addition to Alex Plotkowski, the co-authors of this work include ORNL's Chris Fancher, James Haley, Ke An, Rangasayee Kannan, Thomas Feldhausen, Yousub Lee, Dunji Yu, and Joshua Vaughan, as well as University of Tennessee-ORNL Governor's Chair Suresh Babu and former ORNL researchers Kyle Saleeby, Guru Madireddy, and C. Leach.

This research aligns with UT-Battelle's management of ORNL for the DOE's Office of Science, the leading supporter of fundamental research in the physical sciences in the United States, addressing pressing challenges of our time.

Conclusion:

A groundbreaking endeavor has enabled the examination of additive manufacturing at the atomic level using neutrons. The OpeN-AM platform, in conjunction with ORNL's Spallation Neutron Source, allows the measurement of evolving strain in materials and tracking atomic responses to stress during the manufacturing process. The findings hold tremendous promise for tailoring residual stress in components, enhancing their strength, reducing weight, and enabling intricate designs. This innovation has the potential to benefit various industries, including automotive, aerospace, and clean energy, by offering unprecedented insights into material behavior during manufacturing.

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