Additive Manufacturing of Metals: Electron Beam Melting (EBM) I
Sponsored by: MS&T Organization
Program Organizers: Ian D. Harris, EWI; Ulf Ackelid, Arcam AB; Ola Harrysson, North Carolina State University; Sudarsanam Babu, The Ohio State University; Brent Stucker, University of Louisville
Tuesday 8:00 AM
October 18, 2011
Room: D130
Location: Greater Columbus Convention Center
Session Chair: Ulf Ackelid, Arcam AB
8:00 AM
Additive Layer Manufacture of Titanium Components – From Lab to Production: Iain Todd1; 1University of Sheffield
Additive Layer Manufacture of complex components has gained much attention as a potential replacement for casting and forging. In order to do so both the manufacturing technology and our knowledge of the science underpinning it has had to mature rapidly. Many of the obvious obstacles to adoption have been overcome but some, often surprising ones, remain. In this talk the path from the university lab to pre-production that has been followed at Sheffield will be discussed in the context of both the metallurgical and process science and the technological advances needed to achieve this. Finally the remaining major hurdles will be described and discussed and possible future directions proposed.
8:40 AM
Characterization and Comparison of Electron Beam Melting (EBM) Produced Ti-6Al-4V Parts Using Two Different Powder Fractions: Joakim Karlsson1; Sanna Fager Franzen2; Anders Snis2; Erik Unosson3; Håkan Engqvist3; Jukka Lausmaa1; 1SP Technical Research Institute of Sweden; 2Arcam AB; 3Uppsala University
Utilization of medical implants in health care is increasing. Additive manufacturing techniques are attractive for producing implants customized for individual patients. Electron Beam Melting (EBM) offers rapid manufacturing of materials with unique properties, but is limited with respect to dimensional resolution and production of small components. One important parameter affecting the resolution is the powder fraction of the raw material. In this work the effect of powder size on EBM produced Ti-6Al-4V parts was investigated, using two different powder fractions. The materials were characterized with respect to surface properties, chemical composition, microstructure, and mechanical properties, using TOF-SIMS, XPS, ICP, SEM, optical microscopy, profilometry, indentation hardness, and tensile testing. The powder fraction mainly influenced surface morphology, while chemical and mechanical properties were less affected. We present an analysis of the correlation between the two powder sizes and individual material properties.
9:00 AM
Characterization of Ti6Al4V 3D Auxetic Structures Fabricated via the Electron Beam Melting Process: Li Yang1; Ola Harrysson1; Harvey West1; Denis Cormier2; 1North Carolina State University; 2Rochester Institute of Technology
Auxetic structures have attracted many researchers due to their superior properties and promising potentials in various applications. Up until this point most of the research regarding auxetic structures has been theoretical due to the difficulty of actually fabricating and validating the structures. In the current study, a periodic 3D orthotropic re-entrant honeycomb structure was designed and fabricated from Ti6Al4V via the Electron Beam Melting (EBM) process. The compressive as well as bending properties of the structure were evaluated via physical tests and compared to the theoretical model and the finite element analysis (FEA) model. After taking the fabrication defects into account, the results showed good agreement between the theory and the experiments, and therefore justified the feasibility of structural design for auxetic structures.
9:20 AM Break
9:40 AM Cancelled
Design and Customization of a Golf Club Using Electron Beam Melting: Phillip Ray1; Gilbert Chahine1; Radovan Kovacevic1; Pauline Smith2; 1Southern Methodist University RCAM; 2Army Research Laboratory
The current work portrays a new concept of designing and manufacturing golf club heads by means of Electron Beam Melting(EBM). In light of the advancement of Additive Manufacturing (AM) technologies and the consequent widespread applications in the aerospace, automotive, and biomedical industries, the current work discusses a new application in sports technologies, i.e. the golf industry. Due to the short lead time and high customization capabilities with low tooling cost that AM provides, an improved golf club head can be designed and manufactured in a time and cost effective manner, which provides better compliance to singularities found in different players' technique and swing patterns. In addition by employing Functionally Graded Porosity (FGP), different physical and mechanical properties of the golf club can be tailored to meet specific conditions while providing optimal performance.
10:00 AM
TiAl Manufacturing Using an Arcam A2 Electron Beam Melting System: Francisco Medina1; Jennifer Hernandez1; Larry Murr1; Ryan Wicker1; 1UTEP
The Electron Beam Melting (EBM) additive manufacturing process builds complex parts out of metal powders within a high vacuum environment. The electron beam controls the particle bed temperature enabling stress-free part manufacturing. Significant melt temperatures can also be achieved so that high temperature metal alloy systems such as TiAl, Inconel 625, Inconel 718 and other nickel-base super alloys can be processed. This study describes the process for manufacturing TiAl parts using the EBM system. Initially, several powder analyses were performed, including particle microstructure, size distribution, packing density and flowability. These studies ensured the powder was capable of being processed in the EBM machine. Preliminary build parameter boundaries were then determined by performing smoke and sintering tests with varying parameters including focus offset, beam speed and current. Simple geometries were built for microstructural evaluation and mechanical property determination.
10:20 AM
Thermal, Residual Stress and Process Control Simulation of Additive Manufacturing Processes
: Anil Chaudhary1; Matt Keller1; 1Applied Optimization, Inc.
This paper presents the solution methods and simulation results for the automated prediction of thermal and residual stress distributions in the additive manufacturing of complex, 3-D deposit geometry components. It models the interaction of the laser/electron-beam with the additive material, its effect on the substrate, and the change in the thermal and stress boundary conditions by taking into account of the additive geometry as the deposition progresses. All calculations, geometry generation, thermo-mechanics and material history transfer execute automatically as per the input specification by the user. The software emulates the action of on-line process control, which uses the melt pool and temperature for controlling the laser/electron-beam power and velocity. The simulation outputs a schedule of laser/electron-beam power that will produce a consistent melt pool throughout the deposit. Results will be presented for various thermal, residual stress and process control solutions.
10:40 AM
Digital Manufacturing of Gamma-TiAl by Electron Beam Melting: John Porter1; John Wooten2; Ola Harrysson3; Kyle Knowlson3; 1University of California Santa Barbara; 2CalRAM Inc.; 3North Carolina State University
Gamma-TiAl is a critical and very attractive material for use in high temperature applications because of its mechanical characteristics; however, it is difficult and expensive to fabricate by traditional manufacturing processes. A collaborative program was conducted to investigate the ability to fabricate near-net shaped gamma-TiAl by electron beam melting (EBM) manufacturing. A team, led by UCI, developed the EBM process parameters for TiAl and fabricated test pieces for evaluation. Microstructural and chemical analyses were performed on the test pieces to characterize the material and compare it to traditionally fabricated gamma-TiAl. Heat treatment experiments were performed and the resulting microstructure analyzed. Finally, geometrical shapes were produced and, using these processing parameters, prototype rotating parts were fabricated. This paper will review this work and show examples of the parts produced. Recommendations for follow on work will be shared.
11:00 AM
Metallic Part Fabrication Using Selective Inhibition Sintering (SIS): Berok Khoshnevis1; Mahdi Yoozbashizadeh1; Trudi Dunlap; Yong Chen1; 1USC
The purpose of this research is to investigate the fundamentals of the Selective Inhibition Sintering (SIS) process for the fabrication of metallic parts. A SIS-Metal process has been developed based on the microscopic mechanical inhibition principle. In this process metal salt solution is printed in the selected areas of each metal powder layer; the salt re-crystallizes when water evaporates; salt crystals decompose and grow rapidly prior to sintering; during the sintering process the constituents of decomposed salt particles spread between metal powder particles and prevent the fusing of these particles together; consequently, the sintering process in the affected regions is inhibited. Research result on the inhibition mechanism and process control of the SIS process will be presented. Experimental results are also presented to demonstrate the process capability in fabricating metal parts. The process has numerous advantages including low cost, minimal shrinkage and deformation effects, and independence from polymeric binders.
11:20 AM
Microstructure and Mechanical Properties Evolution of Biomedical Co-Cr-Mo Alloys Produced by EBM Method during Novel Heat Treatment.: Shingo Kurosu1; Hiroaki Matsumoto1; Yunping Li1; Yuichiro Koizumi1; Akihiko Chiba1; 1Tohoku University
The microstructures and mechanical properties of Co-29Cr-6Mo alloy with C and N additions, produced by additive manufacturing using electron beam melting (EBM) method, were studied using X-ray diffraction, electron back scatter diffraction, transmission electron microscope, Vickers hardness tests, and tensile tests, focusing on the influences on the build direction and the various heat treatments after build. It is found that the microstructures for the as built specimens were changed from columnar to eqiaxed grain structure with average grain size of approximately 10-20μm due to the heat treatment employing the reverse transformation from a lamellar (hcp + Cr2N) phase to an fcc. Our results will contribute to the development of biomedical Ni-free Co–Cr–Mo–N-C alloys, produced by EBM method, with refined grain size and good mechanical properties, without requiring any hot workings.
11:40 AM Panel Discussion
12:00 PM Cancelled
An Experimentally Validated Constitutive Model for EBM Gamma-TiAl: Lorenzo Valdevit1; Scott Godfrey1; John Porter2; John Wooten3; 1University of California, Irvine; 2University of California, Santa Barbara; 3CalRAM Inc.
Disruptive insertion of EBM Gamma-TiAl in the aerospace and other DoD-relevant fields ultimately requires the development of a physics-based model enabling confident prediction of mechanical properties from the build parameters. This is a complex multi-physics challenge, requiring integration of analytical, numerical and experimental techniques at the interface of thermal science, materials science and mechanics. As a preliminary step in this direction, we present an experimentally validated constitutive model for EBM Gamma-TiAl, which accurately captures the anisotropy in elastic and plastic behavior inherent in the EBM process, while relying on semi-empirical build parameters / mechanical properties relationships, calibrated on coupon-level experiments. The goal is the delivery of a reliable and fast Finite Elements-based approach to predict stiffness, strength and failure of EBM-built Gamma-TiAl structures of potentially complex geometry (akin to the DARPA DMACE challenge). The accuracy of the model in predicting deformation and failure of complex structures is verified experimentally.