Additive Manufacturing of Refractory Metallic Materials: On-Demand Oral Presentations
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Additive Manufacturing Committee, TMS: Refractory Metals & Materials Committee
Program Organizers: Antonio Ramirez, Ohio State University; Jeffrey Sowards, NASA Marshall Space Flight Center; Isabella Van Rooyen, Pacific Northwest National Laboratory; Omar Mireles, Los Alamos National Laboratory; Eric Lass, University of Tennessee-Knoxville; Faramarz Zarandi, RTX Corporation; Edward Herderick, NSL Analytical; Matthew Osborne, Global Advanced Metals

Monday 8:00 AM
March 14, 2022
Room: Additive Technologies
Location: On-Demand Room


Thermal-chemical-fluid Flow of Dissimilar Species Mixing between Titanium and Refractory Metals: Junji Shinjo1; Chinnapat Panwisawas2; 1Shimane University; 2University of Leicester
    Refractory metals are used for aerospace, nuclear and biomedical applications due to the temperature-resistant and bio-compatible nature. However, chemical species mixing is one of the issues in additive manufacturing (AM) of refractory metals. In this study, mixing characteristics are investigated for Ti and refractory metals (Zr, Nb, Mo, Hf, Ta, W) using direct energy deposition in which several processing parameters are investigated. It is revealed that the convective effect in the melt pool has a significant impact on mixing, where the local viscosity is important in determining the flowability. Higher-temperature molten metal has a smaller viscosity and thus mixing is better. The local temperature control is complicated due to the interaction between convection, vapourisation and heat transfer with temperature-dependent thermophysical properties. Here, several simulation cases are presented to indicate that digital materials design based on high-fidelity thermal-chemical-fluid flow simulation is a powerful tool in predicting the dynamic behavior in AM.

Case Studies on Additive Manufacturing of Refractory Materials: Jeongwoo Lee1; Yung Shin1; 1Purdue University
    This talk covers the case studies on additive manufacturing of highly refractive materials. The first case study is to demonstrate the laser cladding of tungsten on ODS steel for plasma-facing applications. Due to the high melting point of Tungsten, melting of the material requires large energy from the laser. With the substrate materials working as binder, about 88 w% of tungsten was achieved. Successive laser heating/melting was applied to each layer deposited to improve bonding. The second case investigates the cladding of Mo on an H13 tool steel substrate by the blown-powder laser additive manufacturing process to improve its wear and corrosion resistance. To alleviate crack and low concentration due to the large mismatch in thermal properties between Mo and H13, layers were built by functionally graded mixtures of Mo and H13 tool steel powders. A high Mo concentration of 76.7 wt% was achieved.

Electron Beam Melting Additive Manufacturing of Pure Molybdenum: Patxi Fernandez-Zelai1; Christopher Ledford1; Quinn Campbell1; Andrés Márquez Rossy1; Donovan Leonard1; Michael Kirka1; 1Oak Ridge National Laboratory
    Electron beam melting (EBM) additive manufacturing (AM) is an attractive technology for printing refractory metals. A great deal of the existing molybdenum research is focused on laser based processing with relatively little EBM work. In this presentation we share recent work on EBM processing of full-dense, defect-free, molybdenum. We observed analomous microstructures consisting of sharp {001}, {111}, and mixed {001} & {111} crystallographic fibers in the build direction. The preference for these build direction fibers is dependent on the imposed surface energy density and which is likely due to changes in the weld pool morphology. Detailed microscopy demonstrates that columnar grains consist of much finer equiaxed subgrains suggesting large process induced stresses which drives plastic deformation. Furthermore, the resulting build direction fiber may be controlled, and exploited, towards fabricating components with meso-scale composite microstructures which may be used for optimizing engineering properties.

Fabrication of Pure Tungsten Using Electron Beam Powder Bed Fusion: Christopher Ledford1; Patxi Fernandez-Zelaia2; Andres Marquez Rossy2; Julio Ortega Rojas2; Quinn Campbell2; Michael Kirka2; Yutai Kato2; 1Oak Ridge National Laboratory; 2Oak Ridge National Labratory
    Refractory materials are well suited to benefit from additive manufacturing due to existing limitations in processing these materials via conventional means. Nonetheless, obtaining high density and defect free material is a nontrivial task which requires high processing temperatures along with clean inert environments. Here we present our work on the processing of pure Tungsten using electron beam powder bed fusion to produce fully dense, crack-free material. In addition, we investigate the resulting process-sensitive microstructures and corresponding property relationships.