Pittsburgh’s Swanson School of Engineering recently received an award from the Office of Naval Research (ONR) to design, develop and optimize new metallic alloy compositions for additive manufacturing (AM) that are resistant to the effects of Naval/maritime environment.
The research is led by Wei Xiong, PhD, assistant professor in the Swanson School’s Department of Mechanical Engineering and Materials Science, with team members Esta Abelev, PhD and Susheng Tan, PhD.
As the Navy has seen a surge in interest and experimentation with additive manufacturing (AM), we caught up with Dr. Wei Xiong to learn more about this exciting research opportunity in an exclusive AMazing® Q&A conversation.
AMazing®: Professor Xiong, congratulations on the recent award by the The Office of Naval Research (ONR) Additive Manufacturing Alloys for Naval Environments (AMANE). Industry experts surmise that in order for additive manufacturing to reach its full potential, advances in materials as well as design and process technology will be needed. How broad is the current portfolio of printable steel materials for the Naval/maritime environment?
Dr. Wei Xiong: Thanks! This is an exciting project for us. At the moment, the AM community has focused on stainless 316 and some maraging steels for additive manufacturing. So far, the current portfolio of printable steel materials for the Navy/maritime environment is limited. We intend to fill the gap by developing new high strength steel powders.
AMazing®: Traditionally, the Navy has relied upon high strength low alloy (HSLA) steels for naval construction. Does microalloying with post processing optimization represent the best option in terms of cost toward developing new steel prototypes with improved processability, part quality and performance for use in direct metal laser sintering?
Dr. Wei Xiong: In our research, we plan to achieve acceptable mechanical properties in the “as-built” 3D printed condition. From there, we will apply post-processing that should strengthen the material properties to a higher level. We will use HSLA alloys as a reference for the new steel designs. Microalloying is the key to achieve these design goals, and we are adopting the most advanced computational methods to optimize the alloying effects in steel powder design.
AMazing®: What challenges to you anticipate in the development of new material prototypes for direct metal laser sintering?
Dr. Wei Xiong: As a research project, we plan to experiment with a lot of steel powders. It is an expensive process. Since we have a limited budget and a short time period to conduct our research, we need to develop good models, perform rigorous experiments and calibrate our model-predictions accordingly, using as few iterations as possible.
AMazing®: As we understand one objective of the project is to approach the research using Integrated Computational Materials Engineering (ICME) tools.What potential benefits does an ICME approach offer over more traditional approaches with regard to the preparation and testing of new materials?
Dr. Wei Xiong: The method is called CALPHAD-based ICME (CALPHAD: Calculation of Phase Diagrams, ICME: Integrated Computational Materials Engineering). This is a design method using different physical metallurgy design models based on multicomponent alloy thermodynamics and diffusion kinetics, which allow us to understand the process-microstructure-property relations according to different combinations of processing parameters and alloy compositions.
I have to emphasize that we are not performing pure computational design for this project, instead, we will use both simulation and experiments to achieve the best design. Experimentation is the essential part for us to calibrate and verify our model-prediction. The traditional methods usually have the limitation on design space regarding the choices of the composition and processing parameters. Therefore, more trial-and-error will be applied to optimize these combinations of alloy composition and processing parameters, which is not cost-effective and more often limited in quality of optimization.
AMazing®: Would you please share with us some of other research projects being conducted at the Physical Metallurgy and Materials Design Laboratory (PMMD) at University of Pittsburgh?
Dr. Wei Xiong: Sure. Besides the support by ONR, we are involved in two additional NASA funded projects. One is the NASA (The National Aeronautics and Space Administration) Early Stage Innovations (ESI) research project. We are working with my colleague Dr. Albert To and ANSYS Inc. to develop a laser process-structure model on additive manufacturing of Inconel 718.
We have another STTR project just funded by NASA to further extend the laser process-structure model to a more generic process-structure-property modeling, including post-process simulation. We are collaborating with QuesTek Innovations LLC. In the past few years, Pitt has invested in advanced manufacturing research that has helped me establish the PMMD lab. Therefore, we also have some internal funds from Pitt to develop new alloys, which includes high entropy alloys, light-weight alloys and superalloys. Bridging engineering applications and fundamental science is the primary goal of the PMMD lab. We intend to design new alloys for engineering applications and new design models, and in the process, contribute to the fundamentals of materials science.
This concludes our interview. Dr. Xiong, thank you very much for your participation. We are very grateful for the opportunity to learn about the recent award and ongoing activities involving additive manufacturing at Swanson School of Engineering, University of Pittsburgh.
To read about the award from the Office of Naval Research, press here.
About Dr. Wei Xiong
Dr. Wei Xiong is an assistant professor in Materials Science at University of Pittsburgh directing the Physical Metallurgy and Materials Design Laboratory. He received his PhD degree from KTH Royal Institute of Technology in Sweden and the Doctor of Engineering degree from Central South University in China.
In 2012, he moved from Sweden to the US after his PhD research program. He stayed one year at the University of Wisconsin – Madison (2012-2013) before joining Northwestern University as a research associate for alloy design research (2013-2016). Dr. Xiong works in materials design and process optimization, which covers a wide range of inorganic materials, and focuses on phase equilibria and phase transformations using both experiments and modeling.
Dr. Wei Xiong has more than 40 publications related to physical metallurgy, including 7 invited book chapters. Dr. Wei Xiong serves on the ASM International Alloy Phase Diagrams Committee, TMS Alloy Phases Committee, TMS High Temperature Alloys Committee, TMS Additive Manufacturing Committee, and TMS Young Professionals Committee. He is the TMS ICME (Integrated Computational Materials Engineering) education sub-committee chair. He has received several academic awards, which include: Best Paper Awards of the CALPHAD journal in 2012 and 2013, and TMS FMD Young Leader Professional Development Award 2015. Dr. Xiong serves as an associate editor of journal: Science and Technology of Advanced Materials.
About Swanson School of Engineering, University of Pittsburgh
The University of Pittsburgh’s Swanson School of Engineering is one of the oldest engineering programs in the United States and is consistently ranked among the top 50 engineering programs nationally. The Swanson School has excelled in basic and applied research during the past decade and is on the forefront of 21st century technology including sustainability, energy systems, bioengineering, micro- and nanosystems, computational modeling, and advanced materials development.
Approximately 120 faculty members serve more than 4,000 undergraduate and graduate students and Ph.D. candidates in six departments, including Bioengineering, Chemical and Petroleum Engineering, Civil and Environmental Engineering, Electrical and Computer Engineering, Industrial Engineering and Mechanical Engineering and Materials Science.
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