Additive Manufacturing for Energy Applications IV: Mechanical Properties and Performance Testing
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Additive Manufacturing Committee, TMS: Nuclear Materials Committee
Program Organizers: Isabella Van Rooyen, Pacific Northwest National Laboratory; Indrajit Charit, University of Idaho; Subhashish Meher, Idaho National Laboratory; Kumar Sridharan, University of Wisconsin-Madison; Xiaoyuan Lou, Purdue University; Michael Kirka, Oak Ridge National Laboratory

Monday 8:30 AM
February 28, 2022
Room: 261B
Location: Anaheim Convention Center

Session Chair: Indrajit Charit, University of Idaho

8:30 AM  Invited
Additive Manufacturing Topology Optimization and Materials Testing at Westinghouse: William Cleary1; Thomas Pomorski2; 1Westinghouse Electric; 2Penn United Technologies
     Additive manufacturing (AM) is an enabling technology for novel designs and complex shapes that cannot be produced using traditional manufacturing methods. For many nuclear applications, AM could help streamline manufacturing and the supply chain, and reduce production costs while achieving higher performance through improved heat transfer, thermal hydraulic (T/H) performance, material life and accident tolerance. These benefits would improve reliability and operating margins. To realize the benefits of AM, topology optimization and materials development are required. Topology optimization with the use of AM reduces the amount of material required as well as providing improved ergonomic, performance, and safety benefits. It also reduces the time required to print components as well as reducing secondary finishing times and costs.Several examples of additive manufacturing topology optimization along with mechanical testing for various laser powder bed fusion materials, parameters, and geometries, to improve performance and capabilities, are presented.

9:00 AM  
Topological Optimization of CoCrMo Lattice Structures Fabricated by Laser Powder Bed Fusion: Bandar AlMangour1; So-Yeon Park2; Kyu-Sik Kim2; Dariusz Grzesiak3; Kee-Ahn Lee2; 1King Fahd University of Petroleum and Minerals; 2Inha University; 3West Pomeranian University of Technology
    This study involves the fabrication of triply periodic minimal surface sheet lattices by laser powder bed fusion using CoCrMo alloy powder. The tensile properties and deformation behavior of the materials were evaluated by increasing the unit cell size (1, 2.5, and 5 mm) for each topology. The results of the tensile tests showed that the yield strengths and Young’s moduli of all topologies decreased and that their elongations increased with decreasing unit cell size. We compared the mechanical properties of the Neovius and IWP lattices, which had the same unit cell size, and found that the former exhibited higher yield strength, tensile strength, and elongation. Further, the tensile deformation behavior of the specimens was analyzed by applying the Gibson–Ashby analytic model. The Neovius lattice accommodated more uniform deformations in a greater number of cell layers.

9:20 AM  
Mechanical and Corrosion Properties of Friction Surfaced 304L Stainless Steel for Crack Repair: Hemant Agiwal1; Hwasung Yeom1; Kenneth Ross2; Kumar Sridharan1; Frank Pfefferkorn1; 1University of Wisconsin Madison; 2Pacific Northwest National Laboratory
    Friction surfacing has been evaluated for repairing chloride-induced stress corrosion cracks (CISCC) in stainless steel canisters for used nuclear fuel dry cask storage systems (DCSS). 304L austenitic stainless-steel rod was deposited over a substrate of the same material using a CNC machine tool using two different consumable rod diameters, 3/8” and 1/2” on clean and oxidized substrates. Friction surfacing on simulated through-cracks followed by helium leak testing demonstrated the feasibility of gas-tight repair. Closing of cracks at the interface between substrate and deposit was identified after microstructural analyses. Mechanical characteristics of these deposits using microhardness, bending, tensile, and adhesion testing methods were evaluated. Fractography and microstructure characterization was performed and a fine grain structure was observed in the deposited material. Corrosion performance of friction surfaced deposits were tested under ferric chloride solution for 72 hours, and bench-marked against the performance of a sensitized 304L uncoated plate tested under similar conditions.

9:40 AM  
Evaluation of Tensile Strength and Microstructure of 304L Stainless Steel Repaired via Additive Friction Stir Deposition: Harish Rao1; Malcom Williams1; Christopher Williamson1; Noah Zahm1; Paul Allison1; Brian Jordon1; Luke Brewer1; Vijay Vasudevan1; 1University of Alabama
    In this research, we study the feasibility of using additive friction stir deposition (AFSD) as a suitable technology for repairing cracks in 304L stainless steel canisters. Multiple layers of 304L materials were deposited on a 304L plate. Tensile specimens were extracted from the deposited component in longitudinal and build direction to evaluate tensile strength and to characterize microstructure evolution. The AFSD component were dense and exhibited a highly refined grain structure as compared to the feedstock. Continuous bonding at the interfacial layers were observed with no evidence of cracks or porosity. The present study indicates AFSD technology can be implemented for effective repair of 304L stainless steel canisters.

10:00 AM Break

10:20 AM  
Oxide Dispersion Strengthened Stainless Steel by Reactive Additive Manufacturing: Houshang Yin1; Jingfan Yang1; Bingqiang Wei2; Mukesh Bachhav3; Jian Wang2; Xiaoyuan Lou1; 1Auburn University; 2University of Nebraska–Lincoln; 3Idaho National Laboratory
    Oxide dispersion strengthened (ODS) stainless steel was synthesized via in-situ reaction during laser powder bed fusion (LPBF). Under the as-built condition, the material showed fine equiaxed grains and high-density nanoscale oxides in the size of 10-30 nm. Oxides were amorphous in nature with complex compositions. After heat treatment at high temperature, the additive-manufactured ODS stainless steel demonstrated excellent thermal stability. Grain growth and oxide coarsening were not observed. Oxides transformed to crystalline. ~33% increase in hardness was observed in the heat-treated sample as compared to the as-built one. Transmission electron microscope (TEM) and atom probe tomography (APT) were both utilized to understand the underlying strengthening mechanism and reaction kinetics.