Session: 03-08 Metals: New Processing Methods

Paper Number: 93984

93984 - From Photopolymerization of Metal Suspension to Practical and Economical Additive Manufacturing of Haynes 214 Alloy for High Temperature Applications 

Recent development in metal additive manufacturing (AM) has enabled the processing of superalloys to produce highly complex and intricately tailored components for high temperature applications such as engine turbine blades, nuclear reactors, turbochargers, and heat exchangers. Notably, nickel-based superalloys have become a topic of special interest due to their excellent mechanical properties, high corrosion, oxidation and wear resistance at elevated temperature. At Michigan State University (MSU), Haynes 214, a nickel-based superalloy, is being explored as a possible solution for high temperature super critical CO₂ heat exchanger applications due to its excellent capacity to sustain mechanical strength and structural integrity at high temperatures, as well as the ability to form highly protective oxide layers of Al₂O₃ and Cr₂O₃ in corrosive environments.

This paper presents the processing of Haynes 214 using our scalable and expeditious additive manufacturing (SEAM) process, a new metal AM technology developed at MSU. The mixture consisted of Haynes 214 powder and liquid UV curable polymer was selectively photopolymerized on a modified powder bed system in a layer-by-layer fashion. The printed three-dimensional green objects were then subjected to appropriate thermal treatments for binder removal and high temperature sintering to attain final metallic parts with relative density of above 99.5%. The SEAM process demonstrated its capability of fabricating fully dense metal parts with homogeneous microstructure and free of residual stress, significant advantages over other beam-based metal AM processes. Additionally, with its simplicity in design and affordable printing system, as well as scaling feasibility, SEAM process has great potentials in reducing manufacturing time and cost, making it a suitable and attractive manufacturing method for applications with high temperature superalloys. Moreover, with the unique ability to join multiple green parts together by co-sintering, the SEAM process can provide an elegant solution for applications that require creating enclosed channels and internal features within a part. SEAM process was successfully employed to produce the prototype heat exchanger assembly with internal fins structures and heat flow channels by co-sintering two separate green heat changer plates together.

An overview of the SEAM process working principles and its detailed printing procedures from the formation of metal powder-photopolymer mixture to the optimal curing strategy and printing parameters are provided. Also, the thermal decomposition behavior of the selected binder to obtain a clean and complete binder removal from the green parts as well as supersolidus sintering behavior including density evolution and part contiguity, which was employed to develop a 2-step sintering strategy, are characterized. Finally, a Haynes 214 heat exchanger assembly with relative density above 99.5% and no geometrical distortion is demonstrated. The economic benefits of utilizing the SEAM process over other metal AM technologies in processing superalloys for high temperature applications are briefly discussed in the end.

Presenting Author: Haseung Chung Michigan State University

Presenting Author Biography: Haseung Chung received a B.S. and M.S. in mechanical engineering from Seoul National University, Korea in 1998 and 2000, respectively. He received a Ph.D. from the University of Michigan-Ann Arbor, MI, USA in 2005. Dr. Chung is currently an Assistant Professor in the Department of Mechanical Engineering at Michigan State University.

Authors: