Additive Manufacturing of Large-scale Metallic Components: Novel Applications and Alloys
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Additive Manufacturing Committee
Program Organizers: Sneha Prabha Narra, Carnegie Mellon University; Sougata Roy, University of North Dakota; Andrzej Nycz, Oak Ridge National Laboratory; Yousub Lee, Oak Ridge National Laboratory; Chantal Sudbrack, National Energy Technology Laboratory; Albert To, University of Pittsburgh

Tuesday 2:30 PM
March 1, 2022
Room: 263A
Location: Anaheim Convention Center

Session Chair: Joel Andersson, University West; Badri Narayanan, Lincoln Electric Company

2:30 PM  Invited
Large Metal Structures with Wire Arc Additive Manufacturing- Case Studies with Invar Tooling and AM718 Structural Parts: Badri Narayanan1; Ben Schaeffer1; Brad Barnhart1; Andrzej Nycz2; Sougata Roy3; Hannah Sims4; Thodla Ramgopal5; 1Lincoln Electric Company; 2Oakridge National Labs; 3University of North Dakota; 4Case Western Reserve University; 5DNV
     Building large metal structures requires fundamental understanding of traditional welding metallurgy principles in conjunction with optimizing deposition paths using end effectors. This work showcases the capabilities of fabricating large structures deposited with a robotic wire arc additive system that leverages advances in programmatic path planning, feedstock design, and metal delivery process optimization. The ability to programmatically control metal delivery in a controlled fashion to minimize macro defects and achieve near net shaping will be illustrated with Invar aerospace layup tooling. The effect of printing and post weld heat treatment parameters was studied to characterize the magnitude and anisotropy of its coefficient of thermal expansion (CTE). The effect of process variables and post deposition heat treatments on the mechanical performance and resistance to environmental assisted cracking (EAC) on AM 718 will also be presented. The EAC results on additively built parts will be compared to wrought 718 subjected to similar conditions.

3:10 PM  
Rapid Low-temperature Bend-forming of Hierarchical Reticulated Structures: Zachary Cordero1; Harsh Bhundiya1; Fabien Royer1; 1Massachusetts Institute of Technology
    We present a low-power, low-temperature deformation processing technique, termed Bend-Forming, that uses CNC wire bending and snap-fit joints to form net-shaped trusses from spooled wire feedstock. The technique is used to fabricate exemplar structures - an isogrid column, a tetrahedral column, and a doubly curved surface - which together highlight the versatility of the process and suggest its use for in-space manufacturing (ISM). Further, by attaching tape spring stiffeners to each strut of exemplar columns fabricated with Bend-Forming, we demonstrate increased load-carrying and buckling capabilities. A trade study comparing Bend-Forming to other ISM methods such as 3D printing, laser beam welding, and electron beam welding is conducted, and preliminary analyses of its unique challenges are presented. Together these results suggest hierarchical trusses fabricated with Bend-Forming can satisfy strength and stiffness requirements for potential applications as a solar sail frame and as a doubly curved support structure for ELF RF antennas.

3:30 PM  
An Investigation on the Capabilities of Laser Directed Energy Deposition Additive Manufacturing Process in Building Challenging Materials and Geometries: Meysam Akbari1; Ji-Cheng Zhao1; 1University of Maryland
    Laser directed energy deposition (L-DED) is an important category of metal additive manufacturing (AM) technologies that offers unique advantages such as printing large-scale parts, adding surface coatings at a fast speed, and fabricating functionally-graded materials and multi-material components. However, printing certain geometries such as overhang structures has been a challenge with this technology. An L-DED system that uses a co-axial conical powder-feeding nozzle was employed in this study to explore its capabilities in building challenging structures using nickel-based superalloys. Some practical solutions were developed to expand the flexibility of the L-DED technology in building complex shapes.

3:50 PM Break

4:10 PM  
Assessment of Hybrid Additive Manufacturing Concept for Production of Parts for Space Applications: Simon Malej1; Matjaž Godec1; Matej Balazic2; Črtomir Donik1; Alexander Walzl3; Tom Lienert4; Laurent Pambaguian5; 1Institute of Metals and Technology; 2Balmar d.o.o.; 3DISTECH – Disruptive Technologies GmbH; 4Optomec, Inc; 5European Space Research and Technology Centre
    Hybrid additive manufacturing concept (HAMC) represents production of parts by combining PBF (powder bed fusion) and LENS (laser energy net-shaping) processes. PBF process is used for production of subparts with a high structural complexity, while LENS is used for joining of PBF subparts and to build additional large semi complex structures on top of PBF subparts. HAMC method could enable production of parts where benefits of both technologies, increased complexity combined with a high build rate, can be used in one product. However, to see the properties of HAMC parts for production of high performance parts, demonstrators have to be build and tested. The work presents mechanical testing of parts produced by HAMC approach. The samples were tested with different methods to establish different correlation like porosity-mechanical properties. The results showed that building strategy and process related defects had huge impact on the mechanical properties of HAMC parts.

4:30 PM  
A Comparative Study between the Laser Metal Deposition and Selective Laser Melting of AlxCoCrFeNi MPEA: Praveen Sreeramagiri1; Husam Alrehaili2; Xin Wu2; Ganesh Balasubramanian1; 1Lehigh University; 2Wayne State University
    Additive manufacturing is a versatile manufacturing technique that can expedite the exploration of new alloys. Various processes like powder bed fusion (PBF), laser metal deposition (LMD), etc., within additive manufacturing, have unearthed a point of debate regarding the quality of the samples and the fabricability of the materials synthesized by these techniques. We attempt to compare the fabricability, quality and mechanical properties of AlxCoCrFeNi synthesized by PBF and LMD. The equiatomic composition processed using PBF revealed interlayer cracks, due to superior hardness resulting in high residual stresses. The high residual stresses are presumed to result from high cooling rates (~10^6 K/s) during processing. In contrast, samples processed with LMD revealed crack-free ~100% dense deposits, due to relatively low cooling rates (~10^4 K/s). In addition, we report the effect of varying Al content on the fabricability and microstructural evolution of samples processed by PBF and LMD.

4:50 PM  
Wire Arc Additive Manufacturing of Nano-treated High Strength Aluminum Alloys: Yitian Chi1; Maximilian Liese1; Xiaochun Li1; 1University of California Los Angeles
    Light metal has gained tremendous industry interest in fuel economy by applying light metal to reduce the weight of constructions and vehicles. With high-strength aluminum alloys as deposition material, additive manufacturing achieves significant weight saving with only minor compromise in strength. However, despite the superior strength-to-weight ratios of these high-strength aluminum alloys, they are usually non-printable due to hot cracking susceptibility. In this work, Wire Arc Additive Manufacturing (WAAM) was used to print nanoparticle enhanced high strength aluminum components. The resulting parts were crack-free with exceptional grain morphology and superior mechanical properties. Despite repeated heating cycles during the WAAM process, the incorporated nanoparticles are able to control the grains to remain stable and uniform throughout layers. This study demonstrates the great potentials when WAAM combines with Nanotech Metallurgy.