Additive Manufacturing for Energy Applications IV: On-Demand Oral Presentations
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 8:00 AM
March 14, 2022
Room: Additive Technologies
Location: On-Demand Room

Process-aware Design Optimization Methods for Metal Additive Manufacturing: Albert To1; Praveen Vulimiri1; 1University of Pittsburgh
    This talk will discuss recent advances in process-aware design optimization methods for metal additive manufacturing (AM) techniques including laser powder bed fusion (L-PBF), binder jetting, and wire-arc additive manufacturing (WAAM). These methods have been developed for designing support structures, build orientation, scanning path, and deformation compensation. The key novelty in these methods lies in the formulation of the modified inherent strain model which enables fast and accurate prediction of part-scale residual stress and deformation resulting from laser processing. The new model accounts for the interlayer effect on the redistribution of the inherent strains during AM processing. The proposed model reduces simulation time significantly, thus making it practical to perform process-aware topology optimization. Through both simulations and experiments, the design optimization methods developed are shown to not only reduce residual stress and deformation, but also prevent cracking and build failure in various test cases.

3D Ink-extrusion Printing of Thermoelectric Materials onto Heat Exchangers: Alexander Proschel1; Donna Guillen1; Dennis Tucker1; David Dunand2; 1Idaho National Laboratory; 2Northwestern University
    Thermoelectric materials can convert rejected heat into electrical energy, thus augmenting the utility of heat exchangers. However, conventionally manufactured thermoelectric devices are restricted by geometric and manufacturing limitations. The development of ink-based additive manufacturing (AM) techniques could overcome these restrictions and expand the potential applications of thermoelectric generation. This talk will describe a 3D ink-extrusion technique developed for printing half-Heusler thermoelectric materials using a low-cost 3D printer. This approach suspends metallic powder precursors in a viscous polymer solution to print continuous struts forming microlattice structures. A subsequent heat treatment step vaporizes the remaining polymer and binder while simultaneously densifying the powders. Afterwards, the printed part is infiltrated with a liquid metal precursor to form the desired thermoelectric phase. This AM approach offers the potential to print thermoelectric materials directly onto heat exchangers improving efficiency, cost and performance.

Advanced Manufacturing for the Development of Advanced In-pile Sensors and Instrumentation: Kiyo Fujimoto1; Michael McMurtrey1; Troy Unruh1; Tommy Holschuh1; Lance Hone1; Patrick Moo1; Dave Estrada2; 1Idaho National Laboratory; 2Boise State University
    Idaho National Laboratory and Boise State University have recently established capabilities to incorporate advanced manufacturing (AM) methods to accelerate, modernize and enhance functionality of nuclear sensors and instrumentation to achieve the goal of enhancing the safety and efficiency of nuclear reactors. A significant thrust of this work is the development of nuclear relevant feedstock compatible with direct-write processes for the development, fabrication and testing of AM sensors for peak temperature detection and neutron flux monitoring. Incorporating AM techniques provides instrumentation solutions for space-limited applications while also providing an opportunity to significantly expand the design possibilities of the devices. Recent work includes testing and evaluation of the performance reliability of AM melt wire materials and AM neutron dosimeter foils with a comparison to their classically fabricated counterparts. These recent efforts demonstrate the significant potential for incorporating AM techniques in the development of unique, compact and novel in-pile sensors and instrumentation.

Effects of Processing Conditions on Microstructure of Metals Produced via Laser Powder Bed Fusion – A Case Study on Pure Nickel: Qingyang Lu1; Xiaogang Wang1; Tan-Phuc Le1; Jude Emil Fronda1; Karl Davidson1; Matteo Seita1; 1Nanyang Technological University
    We explore the laser powder bed fusion (LPBF) of pure nickel and use it as a case study to investigate the influence of laser beam diameter and shielding gas flow speed on the density, surface roughness and crystallographic texture of printed parts. As we increased the laser beam diameter from 45 m to 180 m, the density and surface roughness of the parts improved. The crystallographic texture of the samples printed with serpentine strategy transits from <111> to <100> along the scanning direction when printed with slow and fast shielding gas speeds respectively. Our work provides insights to suitable processing conditions for LPBF of metals. Furthermore, as nickel is a pure element, our study can be used as a baseline for researchers working on simulations related to microstructure of pure metals produced via LPBF.

Implications of Zr Additions for High-temperature Performance of Additively Manufactured Aluminum Alloys: Richard Michi1; Kevin Sisco2; Sumit Bahl1; Ying Yang1; Jonathan Poplawsky1; Lawrence Allard1; Ryan Dehoff1; Alex Plotkowski1; Amit Shyam1; 1Oak Ridge National Laboratory; 2University of Tennessee, Knoxville
    Additions of Zr are regularly employed in AM Al alloys to reduce hot tearing through nucleation of equiaxed grains. Additionally, precipitation of L12-Al3Zr nanoprecipitates provides strengthening upon heat treatment. Several AM Al alloys have recently shown promise for use in the 250–400 C temperature range where traditional Al alloys lose their strength, so it is of particular interest to understand the implications of Zr additions for high-temperature performance of AM Al alloys. In this talk, we compare the high-temperature mechanical behavior, including creep, of Zr-free and Zr-bearing AM Al-Ce-Ni-Mn and Al-Ce-Ni-Mn-Zr alloys. Phase selection and microstructural changes on multiple length scales, from micron-scale grains to nanometer-scale L12-Al3Zr precipitates are evaluated and correlated to the high-temperature performance, with discussion of insights for AM high-temperature alloy design. APT was conducted at ORNL’s CNMS, which is a U.S. DOE Office of Science user facility.

In-situ Powder-directed Energy Process Control for Additively Manufactured Multi-layer, Functionally Graded Components: Calvin Downey1; Luis Nunez1; Isabella van Rooyen2; Indrajit Charit3; Michael Maughan3; Edward Herderick4; 1Idaho National Laboratory; 2Pacific Northwest National Laboratory; 3University of Idaho; 4Ohio State University
    Harsh environments require advanced materials possessing high-temperature mechanical strength, corrosion resistance, and irradiation resistance. Claddings offer improvements over existing structural materials with protective layers over a bulk component. Additive manufacturing (AM) presents novel blown-powder directed energy deposition (DED) fabrication technologies, including laser-engineered-net-shaping (LENS) and Trumpf hybrid industrial machines. Process control in DED, such as laser heat input and in-situ material composition, make this method unique for overcoming issues such as layer delamination and brittle-phase nucleation. This study investigates DED-fabricated multi-layer bi-metals and compositionally functionally graded materials (FGMs) for 316L stainless steel, Inconel, and Cobalt-based alloys. Multi-layer clad builds are analyzed with x-ray diffraction to allow compositional phase control at the interlayer. Various combinations of FGMs are fabricated to 5–20% grades per layer. Electron microscopy, energy dispersive x-ray spectroscopy, and microhardness tests determine microstructure and preliminary mechanical behavior.

Process Maps Using Fluid Dynamics Models in Single-laser Tracks for Additive Manufacturing: Adrian Sabau1; Narendran Raghavan2; Lang Yuan3; John Turner1; Vipul Gupta4; 1Oak Ridge National Laboratory; 2Los Alamos National Laboratory; 3University of South Carolina; 4GE Research
    In order to obtain the processing envelope of the laser fusion process, a wide range for laser power and laser scan speed were investigated. Microstructure variation was assessed via a columnar-to-equiaxed transition (CET) model during rapid solidification. EBSD micrographs from single-tracks laser fusion experiments were used identify the number of nucleation sites per unit volume, which is one of the most important parameters in Hunt’s CET model. Single-tracks laser fusion (STLF) were simulated using a heat-transfer-solidification-only (HTS) model and its extension with fluid dynamics (HTS_FD) model using Truchas parallel open-source code. In order to cover the entire power-speed processing space, six power levels (50 to 300 W), and six laser speeds (0.1 to 1 m/s), were selected for conducting multi-physics STLF process simulations. Numerical simulation results for the HTS_FD indicated that the fluid flow effects must be considered when developing the process map for laser fusion process.

Surface Roughness of Metal Additive-manufactured Single-track Clads: Luis Nuez1; Calvin Downey1; Isabella van Rooyen2; Indrajit Charit3; Michael Maughan3; 1Idaho National Laboratory; 2Pacific Northwest National Laboratory; 3University of Idaho
    Additive manufacturing (AM) of metal components has advanced in terms of Technology Readiness Level, thanks to the development of process-structure-property (PSP) maps and refined processing methods. Directed energy deposition technologies such as laser engineered net shaping (LENS) and wire arc AM (WAAM) have shown great promise for components in high-temperature environments such as those seen in the energy and aerospace industries. The surface roughness of AM parts is a significant process-induced defect that can affect part quality, as well as thermal and hydraulic performance—especially important in components such as printed circuit heat exchangers. This parametric study of surface roughness looks at the fabrication of 316L stainless steel and Inconel 718 single-track clads using LENS and WAAM. Surface roughness is measured using laser-optical advanced microscopy, and the initial experimental results for the arithmetic mean surface roughness and PSP maps are presented.

Data-driven Modeling for Microstructure-property Relationships of 17-4 Stainless Steel: Michael Porro1; Bin Zhang1; Akanksha Parmar1; Yung Shin1; 1Purdue University
    The high upfront cost of determining the resultant mechanical properties of metal parts built by additive manufacturing significantly hinders widespread adoption in the industry. The objective of this study is to establish a procedure to reduce this cost by using data-driven modeling to predict the mechanical properties of AM-built 17-4 PH stainless steel parts. A data-driven model can provide a quicker way of predicting mechanical properties based on given microstructure information. To build a data-driven model the widely available but scattered data in literature are collected and utilized, and additional tensile specimens were built by binderjet and laser powderbed fusion processes, and resultant microstructure and mechanical properties were experimentally measured. The collected data from the literature and experiments were used to build data-driven models of structure-property relationships. The established data-driven models exhibited good prediction capabilities for yield strength, ductility and ultimate tensile strength for a number of validation cases.

Elevated Temperature Deformation Behavior of Al-Cu-Ce(-Zr) Alloys Produced by Laser Powder Bed Fusion Process: Sumit Bahl1; Richard Michi1; Kevin Sisco1; Donovan Leonard1; Lawrence Allard1; Jonathan Poplawsky1; Ryan Dehoff1; Amit Shyam1; Alex Plotkowski1; 1Oak Ridge National Laboratory
    Al-9Cu-6Ce and Al-9Cu-6Ce-1Zr (wt%) alloys were designed and produced with laser powder bed fusion additive manufacturing (AM) for high-temperature applications in 250 – 400 C temperature range. During AM, the thermal history varies from one location to another inside a melt pool which can result in heterogeneous microstructures. We will describe microstructural heterogeneities present at different length scales and their impact on monotonic tensile deformation in AM Al-Cu-Ce and Al-Cu-Ce-Zr alloys. The results show that the heat-affected zones underneath the melt pool boundaries are potential failure zones in the heterogeneous microstructure particularly under the condition of low strain-rate sensitivity. The addition of Zr enables age-hardening in Al alloys through the formation of nanoscale Al3Zr precipitates. The deformation behavior of the Al-Cu-Ce-Zr alloy in the presence of Al3Zr precipitates will also be discussed with implications for future alloy design.