Additive Manufacturing: Materials, Alloy Development, Microstructure and Properties: Additive Manufacturing of Metallic Materials (Cu, Co, Mo, and Ni)
Program Organizers: Prashanth Konda Gokuldoss, Tallinn University of Technology; Zhi Wang, South China University of Technology; Jurgen Eckert, Erich Schmid Institute of Materials Science; Filippo Berto, Norwegian University of Science and Technology
Monday 8:00 AM
November 2, 2020
Room: Virtual Meeting Room 3
Location: MS&T Virtual
Session Chair: Narges Moghaddam, The University of Texas at Arlington
8:00 AM Invited
Metal Powder Recyclability within Binder Jet Additive Manufacturing Process: Saereh Mirzababaei1; Brian K. Paul1; Somayeh Pasebani1; 1Oregon State University
This work determines the level of 316L stainless steel powder recyclability within binder jetting process. Results of powder characterization demonstrate a 22% increase in the number of coarse particles (≥30μm) with an 18.2% reduction in the number of fine particles (≤10μm) after recycling 316L stainless steel powder sixteen times. Few elongated and irregular-shaped particles were found after recycling, possibly due to particle agglomeration and handling and sieving of powder. A negligible increase in oxygen content by 0.0359%±0.001 was detected in the recycled powder. Density of the sintered part produced using recycled powder was 1.5% lower than the part produced using new powder due to changes in particle size distribution and the flowability of the powder caused by changes in morphology. Final built parts, using new and recycled powder, showed similar hardness (155±2.71 HV and 165±8.6 HV) and yield strength (206±16 MPa and 192±10 MPa), respectively.
8:20 AM
Multi-objective Optimization of Binder Jetting Process Parameters for the Co-Cr-Mo Alloy: Ahmet Koca1; Baris Kirim1; Recep Onler2; Emrecan Soylemez1; 1Department of Mechanical Engineering, Istanbul Technical University; 2Department of Mechanical Engineering, Gebze Technical University
Binder jetting additive manufacturing enables manufacturing complex geometries for a variety of materials. Identifying favorable binder jetting process parameters is the key to obtain an acceptable final product quality in terms of density, geometric capabilities, surface roughness, mechanical properties and geometric retention during sintering. In this study, a design of experiment for Co-Cr-Mo alloy based on Taguchi’s orthogonal array is employed to characterize the effects of several binder jetting parameters (i.e., binder amount, roller speed, curing time) and post-printing parameters (i.e., debinding temperature and time; sintering temperature, atmosphere and time) on final part density, shape retention and final chemical composition. A two-step optimization approach is used to identify ideal process parameters. First, Taguchi’s method is used to identify the optimal combination of process parameters to obtain favorable density and hardness, and then a genetic algorithm based multi-objective optimization approach is used to find optimal printing and sintering conditions.
8:40 AM
Reparation of Co-based Parts Using Additive Manufacturing Technologies: Wilfried Pacquentin1; Jérome Varlet1; Hicham Maskrot1; Gilles Rolland2; Pierre Wident1; 1CEA; 2EDF – R&D, Département Matériaux et Mécanique des Composants, Site des Renardières, F-77818 Moret sur Loing
Direct Laser Deposition (DLD) is a versatile, cost-effective and time-saving tool to repair worn out or damaged parts compatible with a vast panel of metals and complex geometries. In-situ repairing of a component part of a large scale structure may save the complexity of disassembling the host structure using a robot arm to convey the laser beam and the metal powder carrying gas feed. Process parameters include laser beam and powder jet characteristics as well as raster scan strategies and part preparation protocol. The search for the adequate parameter set is at the heart of R&D. We successfully repaired cobalt-based hardfacing coatings in spite of their sensitivity to crack formation induced by extensive thermal cycling. Samples were made using DLD including induction heating, and characterized by non-destructive testing, microstructural examinations and mechanical tests. The quality criteria (dense deposition, minimum porosity and absence of crack) are met.
9:00 AM
Process and Characterization of 3D-printed Copper: Tawfiq Shamsudeen1; Schuyler Mann1; Leo Santala1; David Betolatti1; Louis Pate1; Jose Alarcon1; Michael Bianco1; Ping-Chuan Wang1; 1SUNY New Paltz
Additive manufacturing (AM) of metal structures is emerging as a potentially revolutionary technique, offering many research opportunities to investigate fundamental materials science and limitations. A project of fabricating copper structures using regular consumer-grade 3D printers is currently ongoing at SUNY New Paltz, adopting injection molding techniques with filament consisting of 90% copper powder and 10% polylactic acid (PLA) as a binder. Subsequent heat treatments are conducted to (1) remove PLA from the green state (debinding), and (2) densify the loosely packed copper particles for mechanical strength (sintering). In the first section of the paper, the considerations and challenges throughout the project will be identified along with the feasibility demonstration. Secondly, the design and implementation of a heat treatment system to achieve proper densification will be presented. Lastly, results of the microstructure characterizations will be summarized to illustrate the processing-structure-property relationship of copper specimens using AM techniques.
9:20 AM
Sintering and Alloying Kinetics of Particle-Based Ink Extruded Nickel-Based Scaffolds: Safa Khodabakhsh1; Ashley Paz y Puente1; 1University of Cincinnati
Additive manufacturing of Ni based superalloys, well known for their application in jet turbines, is being investigated because of its potential, but is somewhat limited currently due to a variety of reasons, including poor sintering, internal porosity, and cracking from residual stresses. A combined particle-based ink extrusion and gas-phase alloying approach could overcome some of the aforementioned issues and be used to produce Ni-based scaffolds, with high surface area and low density. In this work, Ni-Cr structures are 3D printed and subsequently gas-phase alloyed with Al via pack cementation. Upon homogenization, Kirkendall pores form internal to the printed struts and can coalesce into interconnected channels, further lowering the density and increasing the surface area of these scaffolds. Furthermore, a reverse pack cementation step, can be used to tailor Al content, which along with a homogenization and aging treatment, results in the desired gamma/gamma prime microstructure, essential for Ni-based superalloys.
9:40 AM
A New Sintering Process for Binder-Jet Printed 625 Alloy: Chuyuan Zheng1; Pierangeli Rodriguez de Vecchis1; Markus Chmielus1; Ian Nettleship1; 1University of Pittsburgh
For non-beam based additive manufacturing (AM) technologies, such as binder-jet 3D printing (BJ3DP), the issue of remnant porosity can drastically limit the mechanical properties of printed metal parts. Previous work by our group has demonstrated that supersolidus liquid phase sintering (SLPS) facilitates the particle rearrangement required to remove large printing defects before final stage sintering. However, prolonged SLPS resulted in chemical segregation at the grain boundaries and rapid grain growth. In this work a novel sintering process is being developed to activate particle rearrangement but avoid chemical segregation in the sintered part. The effect of the sintering process on microstructure evolution will be presented using quantitative results from 2D (by optical microscopy and SEM) and 3D (by X-ray computed tomography) microstructure measurements.
10:00 AM
Co-design of Parts and Processing for Thin-walled Structures Produced via Laser Powder Bed Fusion: Nicholas Lamprinakos1; Anthony Rollett1; 1Carnegie Mellon University
A key advantage of additive manufacturing (AM) is that it allows the production of parts with complicated geometries, but co-design of the parts and the processing is essential. For example, the fabrication of heat exchangers requires the use of complex thin-wall structures to improve heat exchange efficiency. Although AM allows such complicated shapes to be built, oftentimes the processing parameters must be adjusted based on the geometry because geometry has a large impact on thermal gradients during the building process. In this work, the processing parameters for the laser powder bed fusion (LPBF) process were varied to determine the optimal parameters for producing thin-walled parts that could be used in a heat exchanger. The novel superalloy MHA3300 was used for this study because its printability and excellent creep properties at high temperatures make it attractive for this application.