Additive Manufacturing of Refractory Metallic Materials: Additive Manufacturing of Refractory Alloys and Pure Refractory Elements
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 8:30 AM
February 28, 2022
Room: 262C
Location: Anaheim Convention Center
Session Chair: Antonio Ramirez, The Ohio State University; Jeffrey Sowards , Nasa - MSFC; Isabella Van Rooyen, Pacific Northwest National Laboratory
8:30 AM Introductory Comments
8:35 AM Invited
Refractory Metals – Some Historical Observations: Jeffrey Wadsworth; 1
In 1980 exciting programs underway in refractory metals required new metallurgical insights. The Trident Missile was an exemplar; the Post Boost Control System operated for a few minutes at a temperature of 1650oC and used Mo, Ta, Nb (Cb), and W alloys and high temperature coatings. I will describe some of the issues that arose in that mission, including the room temperature fracture of Mo fasteners upon refurbishment. This led to a study on the role of oxygen in embrittlement of Mo alloys. The advent of techniques such as in-situ Auger Spectroscopy fracture were key in understanding the true origins of failure, but so were fundamental thermodynamics. I will also touch upon decisions that had been made regarding Nb alloys. The political role of key decision makers in influencing technical options will be described. The relevance to Additive Manufacturing of refractory metals and alloys will be emphasized.
9:10 AM
Additive Manufacture of Refractory Metals for Aerospace Applications: Omar Mireles1; Jeffrey Sowards1; 1NASA Marshall Space Flight Center
High temperature refractory metals are required for a number of high temperature propulsion, power, and thermal protection applications. Refractory metals can be expensive, difficult to manufacture, tend to have high buy-to-fly ratios, and few vendors. Refractory metal additive manufacture (AM) is in development and like traditional AM alloys requires substantial post-processing to include powder heat treatment, surface finish enhancement, inspection, and machining before placed in service. The combination of limited feedstock sources, high temperature processing, oxygen sensitivity, fracture prone nature, and need for elevated temperature mechanical testing limit the number of qualified facilities capable of post-processing AM refractory materials, which add to cost and schedule constraints. However, properly implemented refractory metal AM can overcome existing manufacture limitations by greatly increasing design flexibility, new material options, reduced price, decreased lead-time, and leverage the ever growing AM commercial supply base.
9:30 AM
Refractory Development Framework Using Computational Modeling: Nathan Daubenmier1; Antonio Ramirez1; Fredrick Michael2; Jeffrey Sowards2; Omar Mireles2; 1The Ohio State University; 2NASA
The high melting temperature of refractory alloys is beneficial for specialized flight applications including Nuclear Thermal Propulsion, green propulsion, and hypersonic flight. Refractory elements such as tungsten and molybdenum, however, often compromise material strength and microstructure due to post solidification cracking and low strength. The high cost of acquisition and production of refractory alloys makes a widescale study of substitutional and interstitial elemental additions difficult. Computational modeling methods including calculation of phase diagrams (CALPHAD) provide cost and time effective options for analyzing wide compositional ranges to determine the effect of alloying methods for target material properties. A comprehensive analysis of a refractory system investigated grain growth, grain pinning, strength, DBTT, and other thermodynamic results to allow for down selection of alloying elements for ideal post-solidification material properties. This procedure is suggested as a framework for refractory alloy development to improve the starting point of physical production and testing of alloys.
9:50 AM Break
10:10 AM
Laser Powder-bed-fusion of Pure Tungsten for Fusion Energy Applications: Alberico Talignani1; Shiqi Zheng1; Philip DePond2; Maria Strantza2; Jianchao Ye2; Y. Morris Wang1; 1University of California, Los Angeles; 2Lawrence Livermore National Laboratory
Tungsten is the material-of-choice for plasma facing components in fusion reactors. Additive manufacturing (AM) tungsten offers abundant design freedom and reduces cost. Due to its intrinsic brittleness, caused by a ductile-to-brittle transition temperature above room temperature (500-700K) and impurities, tungsten is prone to cracking during manufacturing. This presentation reports the progresses of our effort to AM tungsten via laser powder-bed-fusion (L-PBF). Achieving crack-free L-PBF tungsten samples has not been possible in the literature. Understanding crack formation and propagation, and how to suppress them during L-PBF is thus crucial. Single track experiments with a broad range of laser conditions have been explored to obtain optimized processing conditions. The results from both continuous wave and pulsed wave lasers will be presented. We further report the successful fabrications of near fully dense W samples and discuss the strategies that aim to resolve the challenging issues of cracking in L-PBF tungsten.
10:30 AM
LPBF Printing of Nb for the Production of 3D Resonance Cavities: Antonio Ramirez1; Ricardo Namur2; Graham Clark1; David Doll3; Michael Sumption1; 1Ohio State University; 2Univ. Estadual de Ponta Grossa; 3Hypertechresearch
We undertook to use LPBF 3-D printing of pure Niobium to produce 3-D resonators. The use of 3D printing enabled quick prototyping, design flexibility, and scalability, both in terms of size and in terms of multiple unit arrays. An LPBF Mlab system by Concept Laser was used to print a cavity design for 6 GHz with a high q-factor. Printing parameters, build plate, supports, and part orientation were optimized, with 100 W at 1200 mm/s, providing the best part density. The cavities were successfully produced along with witness samples for metallurgical analysis. Electrolytic polishing of the printed parts was explored and all results on printing, characterization, and polishing will be presented.