Late News Poster Session: Additive Technologies
Program Organizers: TMS Administration

Tuesday 5:30 PM
March 1, 2022
Room: Exhibit Hall C
Location: Anaheim Convention Center

J-9: Influence of Process Parameters on Defect Formation for AA 6061 via Laser Powder Bed Fusion Additive Manufacturing: Sivaji Karna¹; Lang Yuan¹; Andrew Gross¹; Tianyu Zhang¹; Rimah Al-Aridi¹; Faith Buchanan¹; Timothy Krentz²; Dale Hitchcock²; ¹University of South Carolina; ²Savannah River National Laboratory
    AA 6061 is one of the most commonly used aluminum alloys in aerospace and automotive applications. However, applications of additively manufactured AA 6061 via the laser powder bed fusion (LPBF) process are limited, owing to the formation of extensive pores and cracks during the rapid solidification. In this study, bead-on-plate experiments, informed by numerical simulations based on Rosenthal solutions, covering a wide range of cooling rates, were performed to understand the melt pool behavior, including size and stability. Process parameters were then selected to print cubic samples. Samples are characterized using microscopy techniques. Samples with a relative density higher than 99.5 % were achieved with high power, high scan speed, and relatively low energy density. Cracks were observed in all samples, and the influence of the process parameters on crack initiation, size, and distribution was analyzed. Lastly, methods to mitigate crack formation, such as heated bed are discussed.

J-49: Data-driven Quality Control of Laser Directed Energy Deposition (DED): Michael Juhasz¹; Melanie Lang¹; Jeff Riemann¹; ¹FormAlloy Technologies, Inc.
    Defects are a leading cause for rejection of additively manufactured parts. Typically, defect measurements are gathered post-production with little to no remedy in the case where defects are found. In-situ monitoring of Additive Manufacturing (AM) produced parts was employed to collect real-time data during a Directed Energy Deposition (DED) build. The in-situ signatures were linked to post-build defects using Machine Learning (ML)-based, layer classification. A threshold was applied to detect porosity sizes and quantities that render individual layers as acceptable or unacceptable. We demonstrate these ML techniques for the purpose of defect monitoring are shown to be highly effective at classifying acceptable/unacceptable layers real-time during build process.

J-51: Laser Metal Deposition (LMD) and High-speed Laser Cladding – Perspectives for Brake Discs: Eliana Fu¹; Sabrina Vogt¹; Marco Goebel¹; ¹Trumpf
     Laser Metal Deposition (LMD), also known as Direct Energy Deposition (DED) is an often-used technology for high quality repairs, wear and corrosion protection as well as modifications on existing parts. With build-up rates of up to 500 cmł/min this technology can be used for fast, near net shape build-ups for e.g. applying optimized structural reinforcements to increase functionality or resistance to high local stress loads. A new variant of the well-known LMD process is the High-Speed Laser Cladding, enabling very high feed rates between 100-500 m/min and locally adjusted layer thicknesses between 50-300 ľm per layer.For automotive industry, LMD and High-Speed Laser Cladding are already being investigated for a broad range of applications. In the poster, we will highlight use cases from R&D and future production, in particular focusing on the coating of brake discs using High-Speed Laser Cladding.

J-52: Towards a Magnetic Field Induced Strain in Additive Manufactured NiMnGa Shape Memory Alloys: Robert Chulist¹; Anna Wójcik¹; Maciej Kowalczyk²; Łukasz Żrodowski²; Norbert Schell³; Rafał Wróblewski²; Wojciech Maziarz¹; ¹IMMS PAS; ²Warsaw University of Technology; ³Helmholtz-Zentrum Geesthacht
    Selective laser melting (SLM) process was used to manufacture NiMnGa-based polycrystalline samples. The initial powders were firstly prepared by ball milling process producing a fine particle size of about 20 ľm. Depending on the composition and printing parameters three distinct types of martensite crystal structures, namely simple tetragonal, and two monoclinic modulated i.e. 10M and 14M were obtained. The localized heating/cooling conditions produce a layered microstructure with a strong fiber <100> texture along the growth direction. The crystal structure and crystallographic texture drastically change when laser oscillation mode is chosen. The results are discussed with respect to crystallographic texture, printing mode, heat treating process, and the resulting magnetic field-induced strain. The financial support by National Centre for Research and Development of Poland is acknowledged for funding (TECHMATSTRATEG 2/410941/4/NCBR/ 2019).

J-53: Uncovering the Deformation Pathways of an AM Ti Alloy with Engineered Duplex Microstructure: Jenniffer Bustillos¹; Atieh Moridi¹; ¹Cornell University
    In this work we aim to uncover the deformation mechanisms and defect evolution characteristics in a recently engineered L-PBF Ti-6Al-4V duplex microstructure. The engineered microstructure benefits from the unique synergy of the α-lath’s strength and plasticity of globular α-grains, significantly improving the tensile ductility (εf=20ą1%) as compared to conventionally hot isostatically pressed AM parts, wrought, cast, forged, annealed, aged, and solution-treated counterparts. We uncover the complex interplay between phases (α, β) and microstructural characteristics (laths, globules) responsible for the extended plasticity and retained strength (UTS=1.06ą0.02GPa) in the recently developed duplex AM Ti-6Al-4V under tensile loading. Using an adaptive domain misorientation analysis approach of conventional electron backscattered diffraction (EBSD) data, we resolve the heterogenous distribution of strains in the duplex microstructure in the form of complex dislocation cells, and sub-grains enabling an added pathway of deformation via their ease of rotation.