Additive Manufacturing of Metals: Microstructure, Properties and Alloy Development: Additive Manufacturing of Miscellaneous Non-ferrous Alloys
Program Organizers: Prashanth Konda Gokuldoss, Tallinn University of Technology; Ulf Ackelid, Freemelt AB; Andrzej Wojcieszynski, ATI Specialty Materials; Sudarsanam Babu, University of Tennessee, Knoxville; Ola Harrysson, North Carolina State University

Wednesday 8:00 AM
October 2, 2019
Room: B115
Location: Oregon Convention Center

Session Chair: Prashanth Konda Gokuldoss, Tallinn University of Technology

8:00 AM  Invited
Additive Manufacturing of Implantable Biomaterials: Processing Challenges, Biocompatibility Assessment and Clinical Translation: Bikramjit Basu1; 1Indian Institute of Science
     Biomaterials science and biomedical engineering have sustained as one among frontier and growing areas of research and innovation within the engineering science community in the world;considering the number of scientific discoveries and their societal impact. Significant attempts were largely directed to re-create functional musculoskeletal systems with considerable potential to treat various types of human diseases.I will present multiscale measurements and analysis to quantitatively understand the process physics of 3D inkjet powder printing.I will present some of our recent results to demonstrate the efficacy of the 3D powder printing to fabricate Ti6Al4V, Calcium Phosphate and magnesium phosphate-based bioceramic scaffolds.A major emphasis will be placed on the binder formulation,post-processing treatment,and micro-computed tomography of interconnected porous architecture together with strength reliability.One of the most recent clinical translational attempts to treat decompressive craniectomy using 3D powder printed patient-specific cranial prosthesis will be presented.This presentation will also mention the speaker’s thoughts on translational research programs.

8:30 AM  
Milling of Ti-64Al-4V for In Space Manufacturing of 3D-Printed Metal Structures: Curtis Hill1; 1NASA, Marshall Space Flight Center
     NASA is developing materials and processes for the in space manufacturing of many items for the International Space Station (ISS) and future exploration platforms. These new manufacturing processes will require the further development of current metal sintering and 3D printing processes to achieve high-performance metal parts with the power and space constraints of the ISS. The current sintering process for Ti-64Al-4V requires a sintering temperature of 1,300C, which places severe power demands on the ISS. Since the best commercially-available Ti-64Al-4V powder is in the 15-30m particle size, our study investigates the impact of reducing the particle size upon sintering temperature and also the final sintered density of the metal parts.A novel approach to micro-milling the Ti-64Al-4V is presented for this research. This new milling technique will have broad application to other areas that require particle size reduction of hard metallic materials, such as Nuclear Thermal Propulsion and other NASA technologies.

8:50 AM  Cancelled
Additive Manufacturing of Pure Magnesium: Densification Behavior, Microstructural Evolution, and Mechanical Properties: Bandar AlMangour; Abdulaziz AlHazaa1; Dariusz Grzesiak2; Ahmad Sorour3; 1Department of Physics & Astronomy, College of Science, King Saud University; 2Department of Mechanical Engineering and Mechatronics, West Pomeranian University of Technology, Szczecin; 3Center of Research Excellence in Corrosion, Research Institute, King Fahd University of Petroleum and Minerals
    Mg-based materials are known for their low density as well as high biocompatibility, which makes them suitable for lightweight structural and biomedical applications. This study investigates the densification behavior, microstructural evolution, and mechanical properties of pure Mg processed by selective laser melting(SLM)under various processing parameters. The challenges associated with the SLM-processability of Mg were addressed. Parts with a relative density of up to 97.26% were obtained by optimizing the energy density of the laser beam, combined with hot-isostatic pressing. Fine cellular dendrites were formed, which coarsened as the applied energy density increased. Improved hardness were observed, and were mainly attributed to the higher degree of densification as well as grain-boundary strengthening. The oxidation tests suggest that the degradation rate is relatively slow, owing to the fine grain size.

9:10 AM  
Effect of Processing Conditions on Mechanical Properties of Copper Fabricated Using Electron Beam Powder Bed Fusion: Prithwish Tarafder1; Christopher Ledford1; Timothy Horn1; Magnus Ahlfors2; Joel Alfano3; Harvey West1; Christopher Rock1; 1North Carolina State University; 2Quintus Technologies; 3Siemens
    Powder bed additive manufacturing of copper promises interesting applications due to design flexibility of the process, and superior mechanical and physical properties of the material. However, micro-structural and mechanical characterization is required to qualify copper as AM material. Aiming at validating the mechanical properties, this research, at its initial stage, examined uniaxial quasi-static tensile behavior of Electron Beam Melting printed copper in as-printed, hot isostatic pressed, and annealed condition to interpret effects of process history, powder feedstock oxygen content, and build orientation. Preliminary results indicate positive correlation between second phase oxides and tensile strength, while build orientation shows significant impact on grain morphology and overall properties. The research now aims at conducting load controlled uniaxial fatigue test on printed samples with aforementioned treatment conditions at different temperature levels to replicate application scenarios; wherein similar process related factors will be analyzed based on their effects on fracture mechanism during fatigue testing.

9:30 AM  
Development of Parameters and Comparison of Mechanical and Microstructural Properties of Tungsten Nickel Iron (W-Ni-Fe) with Parts Fabricated from Laser Powder Bed Fusion (PBF): Michael Brand1; Colt Montgomery1; Robin Pacheco1; Joel Montalvo1; Jessica Lopez1; Adam Wachtor1; John Carpenter1; 1Los Alamos National Laboratory
    Tungsten Nickel Iron (W-Ni-Fe) samples were fabricated using an EOS M290 powder bed fusion (PBF) instrument. Powder for this research had an average size of 30m and a range of 15-44m. Laser parameters were developed on the EOS M290 using single beads and density cubes to achieve a fully dense sample. With these parameters, the single beads and the density cubes were viewed using a scanning electron microscope (SEM) to verify whether the tungsten is melting and determine if the samples are fully dense. SEM was used to look at the microstructural differences based on each of the parameters used for each sample. ASTM E8 micro tensile bars were fabricated to determine the tensile properties and ductility of the samples. Comparisons were made to samples produced by wrought process to the PBF samples.

9:50 AM  
Effect of Heat Treatments on Compressive Properties of Lattice-structured AlSi10Mg Alloy Fabricated by Selective Laser Melting: Asuka Suzuki1; Keito Sekizawa1; Mulin Liu1; Takafumi Wada1; Naoki Takata1; Makoto Kobashi1; 1Nagoya University
    Lattice-structured aluminum alloys fabricated by additive manufacturing processes are ones of the promising materials for shock energy absorbers. Also, mechanical properties of aluminum alloys fabricated by selective laser melting change largely with heat treatments. In the present study, we investigated effect of heat treatments on compressive properties of a lattice-structured AlSi10Mg alloy with a BCC type unit cell fabricated by the selective laser melting. The as-fabricated lattice specimen shear fractured at an angle of 45 from the compressive axis. Heat treatments at 300C for 2 h or 530C for 6 h enabled the lattice specimens to deform until densified. However, the nominal stress dropped in the plateau region due to the formation of shear bands, which occurred more frequently in the 530C/6 h heat-treated lattice specimen than in the 300C/2 h heat-treated lattice specimen. These results will be discussed based on the fractography, X-ray computed tomography and finite element analysis.

10:10 AM Break

10:30 AM  
Effect of Sample Dimensions on Microstructure of Selectively Laser Melted AlSi10Mg Alloy: Naoki Takata1; Hirohisa Kodaira1; Asuka Suzuki1; Makoto Kobashi1; 1Nagoya University
    In order to reveal the effect of sample dimensions on microstructure of the AlSi10Mg alloy fabricated by selective laser melting (SLM) combined with a powder bed technique, plate-shaped AlSi10Mg alloy samples with various widths (ranging from approximately 10 mm to 0.3 mm) were built in this study. All SLM-fabricated samples exhibited characteristic microstructural morphologies consisting of melt pools with columnar α-Al grains surrounded by fine eutectic Si particles. Their sample dimension had a slight effect on the texture and average grain size of the α-Al matrix. However, the formation of fine Si precipitates was observed more often within the columnar α-Al grains in the smaller-sized samples, which could be a dominant contributor to the observed softening of the sample by reducing the sample dimension. The observed softening will be discussed in terms of varied cooling rates due to low thermal conductivity of alloy powders.

10:50 AM  
Fatigue Life of Additively Manufactured AlSi10Mg Produced by Powder Bed Fusion: Daniel Urban1; Kevin Chasse1; Marc Heffes1; Walter Myers1; Edward Martin1; Noe Rodriguez1; 1Northrop Grumman Systems Corporation
    Aerospace and defense applications may experience millions of stress cycles in random vibration conditions, thus accurately predicting fatigue performance of additively manufactured (AM) components is of practical importance. In this investigation, high cycle fatigue (HCF) and fracture behavior of AlSi10Mg samples produced via laser powder bed fusion (LPBF) have been studied. The fatigue life effects of build layer thickness, heat treatment, surface finish, and stress concentration factors (Kt) have been analyzed. Surface finish and near-surface porosity have previously been shown to have a large effect on fatigue life of LPBF materials. The data developed herein provide important information for structural design of fatigue-critical applications, illustrate the important effects of certain processing parameters, and relate behavior to select load conditions. Microstructure and fractography results corroborate some of the HCF and fatigue crack growth rate results, particularly as a function of layer thickness and heat treatment condition.