Additive manufacturing enables design and production of structural metallic components with complex geometries. Recent work has shown that, in addition to complex geometries, site-specific microstructures can be achieved through careful control of processing condition at every layer. The interactions between boundary conditions imposed by component geometry, wide variations of thermal signatures are brought about by mode of energy delivery, and composition of the alloys. These phenomena are studied using computer modeling, in-situ monitoring and ex-situ characterization tools. The results from the above clearly show that the additive manufacturing is nothing but multipass micro-welding with complex boundary conditions and published theories and tools relevant to Integrated Computational Weld Models are quite relevant. This talk will review case studies and associated fundamental challenges in extending these methodologies to wide range of structural metals and alloys. First study focused on control of crystallographic texture, during electron/laser beam powder melting, by controlling thermal gradient (G) and liquid-solid interface velocity (R). The sensitivity of columnar to equiaxed transitions in solidification maps was related to uncertainty of parameters used in the interface response function theories, as well as spatial and temporal variations in G and R. Second study focused on using melting experiments and post-process heat treatment as an alloy evaluation methodology. Microstructures in the melt regions of model aluminum and nickel alloys confirmed the feasibility of selecting wide range of solidification microstructures through spatial variations of G and R along the 3D melt pool surface, as well as stability of eutectic structures during post-process heat treatments. Extension of the above approach to solid-state additive manufacturing will also be introduced.
Dr. Sudarsanam Suresh Babu holds the UT/ORNL governor’s chair in advanced manufacturing at the University of Tennessee, Knoxville and serves in the Department of Mechanical, Aerospace and Biomedical engineering. Suresh has a joint professorship with the Department of materials science and Engineering (MSE). As a Governor's Chair, Suresh has a joint appointment within Manufacturing Sciences Division and in the Advanced Manufacturing Program at Oak Ridge National Laboratory (ORNL). Suresh leads basic and applied research in a wide range of additive and other advanced manufacturing processes including product design implications in collaboration with faculty and students at UT as well as with researchers at the Manufacturing Demonstration Facility (MDF) at ORNL. He has published more than 250 journal papers.
Suresh obtained his bachelor’s degree in metallurgical engineering from PSG College of Technology, Coimbatore, INDIA, and his master’s degree in industrial welding metallurgy-materials joining from Indian Institute of Technology, Madras. He obtained his PhD in materials science and metallurgy from University of Cambridge, UK in 1992. He also worked as a research associate in the prestigious Institute for Materials Research, Sendai, Japan before joining ORNL in 1993. From 1993 to 1997, he held joint researcher position with ORNL, University of Tennessee and The Penn State University. From 1997 to 2005, he worked as an R&D staff at ORNL. From 2005 to 2007, Suresh held a senior level technology leader position in engineering and materials at Edison Welding Institute, Columbus, Ohio. From 2007 to 2013, he was a faculty in the welding engineering program and Department of Materials Science and Engineering at the Ohio State University, Columbus, Ohio. Suresh was the director of NSF I/UCRC center for integrative materials joining science for energy applications in collaboration with Colorado School of Mines, Lehigh University and University of Wisconsin from 2010 to 2013. In 2019, Suresh was also appointed as Director of Bredesen Center for Interdisciplinary Research and Education for Energy- and Data- Science and Engineering. In 2020, Suresh was appointed to the National Science Board by the President of the United States of America for a six-year term.