General Poster Session: Additive Technologies
Program Organizers: TMS Administration
Monday 5:30 PM
February 24, 2020
Room: Sails Pavilion
Location: San Diego Convention Ctr
A-157: Effect of Process Parameters on Plasma Transferred Arc Additive Manufactured 17-4PH Using the Taguchi Method: Sandy Ibrahim1; Jose Mercado Rojas1; Tonya Wolfe2; Hani Henein1; Ahmed Qureshi1; 1University of Alberta; 2Innotech Alberta
Plasma transferred arc additive manufacturing (PTA-AM) is a newly developed AM process proposed for the manufacturing of large industrial parts that can be used in applications for the resource sector. 17-4PH stainless steel is a common material used in numerous industries due to its good corrosion resistance, ease of fabrication and an UTS of about 1400 MPa at peak age hardening. The PTA-AM system has numerous process parameters such as shield, center and powder gas pressures and flowrates, current, voltage, angle of powder nozzle deposition relative to the welding direction and speed of an automated table connected to the PTA-AM system. A G-code for the automated table was developed for each desired printed AM shape. The different combinations of the above parameters can result in numerous, very different mechanical properties and microstructures of the AM samples as well as geometrical uniformity. A full factorial of experiments to print an optimized (minimum porosity and at least comparable hardness and UTS relative to other manufacturing processes) 17-4PH stainless AM part is not feasible within a reasonable timeframe. Thus, a Taguchi design of experiments (DOEs) was designed to identify the most influential parameters on the final mechanical properties and microstructure. This poster will present the results from Taguchi’s DOEs and their relationship to the built PTA-AM of 17-4PH stainless steel samples.
A-158: Effect of Scanning Strategy and Energy Density on Mechanical and Microstructural Properties of 316L Stainless Steel Processed via Selective Laser Melting: Taban Larimian; Manigandan Kannan1; Dariusz Grzesiak2; Bandar Almangour3; Tushar Borkar4; 1the University of Akron; 2West Pomeranian University of Technology; 3Saudi Arabia Basic Industries Corporation; 4Cleveland State University
Selective laser melting (SLM) is an additive manufacturing (AM) process that uses the energy of a laser beam in order to selectively melt the metallic powder that have been spread on a substrate. Processing parameters (e.g. laser power, scanning strategy, etc.) are essential factors that contribute to the mechanical and microstructural properties of SLM-fabricated parts. In this work 16 SLM-fabricated blocks (made of 316L stainless steel) that were built under different processing parameters were investigated. Effect of energy density (70, 100 and 150 (J/mm3)), scanning strategy (alternate hatches, single pass of laser beam, alternate hatches, multiple passes of laser beam and cross hatches, single pass of laser beam) and scanning speed (6 different speeds) on mechanical properties such as microhardness, ultimate tensile strength, yield strength, elongation and relative density was studied. Furthermore, effect of said parameters on microstructure of the samples was studied by scanning electron microscopy (SEM) analysis.
A-159: Effects of Bi in Rapid Solidification of a Hypoeutectic Al-Si Alloy: José Marcelino Dias1; Abdoul-Aziz Bogno2; Jose Spinelli3; Amauri Garcia4; Hani Henein2; 1University of Campinas and University of Alberta; 2University of Alberta; 3Federal University of São Carlos; 4University of Campinas
In recent years, Al-Si-Bi alloys have drawn a lot of interest due to their self-lubricating property and wear resistance in bearing applications. This study reports on the investigation of the solidification path of an Al-Si-Bi alloy in the Al-rich corner under different thermal histories. Different but complementary analytical tools were used to investigate the effect of Bi on the microstructure and mechanical properties of Al-8wt.%Si-2.5wt.%Bi solidified under varying cooling rates and undercoolings. The solidification trials were done using Impulse Atomization and Differential Scanning Calorimetry. The results were compared with a previously characterized binary hypo-eutectic Al-Si alloy, solidified under the similar conditions. The ternary alloy is found to exhibit two different Si morphologies (i.e. flaky, and fibrous), which were directly related to the solidification path of the ternary alloy and are compared to those obtained from the binary alloy. Finally, Bi addition is found to increase the undercooling and the eutectic cooling rate of the ternary alloy compared to those of the binary one, leading to increased hardness.
A-160: Effects of Photoinitiators on Biomechanical Properties of Gelatin Methacrylate Hydrogels and Cell Viability in 3D Bioprinting: Heqi Xu1; Jazzmin Casillas1; Changxue Xu1; 1Texas Tech University
In 3D bioprinting, the bioink is precisely deposited on the substrate to build 3D cellular constructs based on a layer-by-layer mechanism. Photocrosslinkable polymers such as gelatin methacrylate (GelMA) have been widely utilized in various 3D bioprinting applications. When the GelMA is used for 3D bioprinting, the photoinitiator is required for its crosslinking. Two types of photoinitiator are commonly used: Irgacure 2959 and lithium phenyl-,2,4,6-trimethylbenzoylphosphinate (LAP). This study compares effects of these two photoinitiators on the biomechanical properties of GelMA hydrogels and cell viability in 3D bioprinting process. The biomechanical properties include swelling, degradation, and stress-strain relationship. This study also compares the effects of these two photoinitiators on the cell viability during and after 3D bioprinting process. Specifically, during the 3D bioprinting process the effects of the photoinitiator concentration and printing time are investigated, and after the 3D bioprinting process the effects of the printing time and incubation time are investigated.
A-161: Microstructure and Mechanical Properties of 410 Stainless Steel via Metal Big Area Additive Manufacturing: Sougata Roy1; Benjamin Shassere2; Jake Yoder3; Andrzej Nycz1; Mark Noakes1; Niyanth Sridharan1; 1Oak Ridge National Laboratory; 2MS Technology, Inc.; 3Virginia Tech
Metal Big Area Additive Manufacturing (mBAAM) is a novel wire-arc additive manufacturing method that uses a close loop deposition control approach developed at the Oak Ridge National Laboratory. The mBAAM process was used to fabricate thin walled builds using ER410 welding wire. The uni-axial tensile and CVN tests conducted on the ‘as printed’ samples showed significant scatter among the samples sectioned parallel, perpendicular and at 45° angle to the build direction. Microstructural study confirmed formation of d (delta) ferrite as the driving factor behind such sporadic results. In addition to processing, strategies to improve and homogenize the mechanical properties via post processing heat treatments were also explored. Normalizing at 1050°C for 1 hr. resulted dissolution of delta ferrite into the microstructure which led to significantly uniform tensile and Charpy test results. Increasing tempering temperature above 450°C resulted significant reduction on surface hardness but tempering above 550°C showed compelling increase in toughness.
A-162: Microstructure and Mechanical Properties of Ti-6Al-4V Additively Manufactured with Electron Beam Freeform Fabrication: Samuel Present1; Karen Taminger2; Kevin Hemker1; 1Johns Hopkins University; 2NASA Langley Research Center
Electron beam freeform fabrication (EBF3) is a wire-fed directed energy deposition additive manufacturing process that emphasizes a high deposition rate in order to manufacture large parts. EBF3 offers the capability to additively manufacture large-scale structural components in remote space environments. Despite its promise, the relationships between processing parameters, microstructure, and mechanical properties of material produced by EBF3 are not well understood. This work was undertaken to characterize the microstructure of as-deposited Ti-6Al-4V as well as its mechanical properties with respect to anisotropy and inhomogeneity. The microstructure was characterized using a variety of techniques, including electron microscopy and electron backscatter diffraction. Nanoindentation was performed to elucidate the effects of microstructural inhomogeneities. On the bulk-scale, the mechanical properties were characterized using tensile tests, shear tests, and 3-D DIC strain mapping.
A-163: Properties and Microstructure of Additive Manufactured Carbon Steel: Shifeng Liu1; 1Xi’an University of Architecture and Technology
Three types of carbon steel (316L, 45 steel and GCr15 according to Chinese standard) with different contents of carbon were selected as raw materials for additive manufacture. Selective laser melting (SLM) and electron-beam melting (EBM) were employed to fabricate samples. Microstructure and properties of the samples prepared by different process techniques were investigated and compared. The influence of carbon content on the formability of carbon steel during additive manufacturing was studied. The results show that 45 steel (C:0.42~0.50 wt.%) fabricated by EBM presents the highest tensile stress, while SLMed GCr15 (C:0.95~1.05 wt.%) exhibits the best tribological performance due to its high microhardness. It is noticed that samples manufactured by EBM has less residual stress than those via SLM for the benefit of preheating process during EBM process. The formability of the carbon steel show close relation with its carbon content during SLM et EBM.