Additive Manufacturing: Building the Pathway towards Process and Material Qualification: Novel Material Systems
Sponsored by: TMS Extraction and Processing Division, TMS Materials Processing and Manufacturing Division, TMS Structural Materials Division, TMS: Mechanical Behavior of Materials Committee, TMS: Powder Materials Committee, TMS: Process Technology and Modeling Committee, TMS: Additive Manufacturing Bridge Committee
Program Organizers: John Carpenter, Los Alamos National Laboratory; David Bourell, University of Texas - Austin; Allison Beese, Pennsylvania State University; James Sears, GE Global Research Center; Reginald Hamilton, Pennsylvania State University; Rajiv Mishra, University of North Texas; Edward Herderick, GE Corporate

Monday 8:30 AM
February 27, 2017
Room: 8
Location: San Diego Convention Ctr

Session Chair: Amanda Wu, Lawrence Livermore National Laboratory; Michael Kirka, Oak Ridge National Laboratory

8:30 AM  
Structure / Property (Constitutive and Dynamic Strength / Damage) Characterization of Additively Manufactured (AM) Tantalum Produced Using Different AM Build Methods: George Gray1; Veronica Livescu1; Cameron Knapp1; Carl Trujillo1; Roberta Beal1; David Jones1; 1Los Alamos National Laboratory
    Certification requirements generally involve meeting engineering and physics requirements tied to the functional requirements of the engineering component and finally process and product qualification. In this presentation, the results of a study quantifying the constitutive behavior of Tantalum (Ta) fabricated using Optomec, EOS, and Sciaky additive-manufacturing (AM) platforms is presented. The microstructure of the AM-Ta is detailed for each of the AM processes. The mechanical behavior of the three AM build methods was characterized using compression testing as a function of strain rate. The dynamic damage evolution and failure response of the AM-Ta materials, as well as wrought Ta, was probed using flyer-plate impact driven spallation experiments. The damage evolution as a function of AM fabrication method was characterized using optical metallography and electron-back-scatter diffraction (EBSD).

8:50 AM  
Microstructures of Nickel-base Superalloy IN100 Fabricated through Scanning Laser Epitaxy: Amrita Basak1; Ranadip Acharya1; Suman Das1; 1Georgia Institute of Technology
    Nickel-base superalloys are extensively used to produce gas turbine hot-section components as they offer improved creep strength and higher fatigue resistance compared to other alloys due to the presence of precipitate-strengthening phases in the normally face-centered cubic (FCC) structure of the solidified nickel. In this work, the microstructures of the SLE deposited IN100 were investigated using optical imaging, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and x-ray diffraction (XRD). SEM investigations showed the presence of fine /γ′ phases, eutectics, and carbides in the deposit region. EDS analysis showed the carbides to be Ti-rich. XRD investigation revealed the presence of mixed phases in the deposit region. XRD was also used to analyze the residual stresses in the deposit region the deposit region showed a similar order of residual stresses compared to the substrate region. This work is sponsored by the Office of Naval Research through grant N00014-14-1-0658.

9:10 AM  
Development of Titanium Alloys Optimized for Additive Manufacturing Employing Laser Deposition of Powders: Brian Welk1; Hamish Fraser1; 1The Ohio State University
    Samples produced using laser deposition of metallic powders often exhibit distributions of porosity, coarse columnar microstructures, and possess significant residual stresses. This presentation describes research aimed at eliminating (or at least significantly reducing) porosity, and modifying microstructure, for example, producing equiaxed microstructures using variations in alloy composition. In this way, alloys are being produced that respond to the processing technique, rather than using conventional compositions which, in the processed condition, contain defects and unattractive microstructures. The factors that influence the choice of alloying elements to be used in these new alloys include those elements that result in a change in solidification mode, those that have been used as inoculants in cast alloys, and those that will reduce the surface tension of liquid titanium alloys. The results of these experiments will be described, which will include not only materials characterization but also mechanical property determination.

9:30 AM  
Understanding the Influence of Powder Bed Fusion Processing on the Shape Memory Alloy, Uranium-6 wt. Pct. Niobium: Amanda Wu1; Donald Brown2; Bjorn Clausen2; John Elmer1; 1Lawrence Livermore National Laboratory; 2Los Alamos National Laboratory
    Uranium-niobium alloys require specific melting and forging processes to achieve reasonable homogeneity of the alloying elements. The challenges and expenses associated with these materials processes, coupled with reprocessing of scrap from subtractive machining, have driven investigations into alternative manufacturing methods capable of producing geometrically complex parts from this uncommon material. Laser powder bed fusion can produce net-shape, fine-featured, complex architectures with high material efficiency. Materials specific challenges toward process qualification include the potential introduction of non-metallic impurities (through powder passivation or from the shielding gas atmosphere, e.g.), residual stresses resulting from thermal cycling under constraint, and process-specific weld microstructures; all of which impact on material performance. Here, we discuss the effect of post-processing heat treatments on material homogenization, impurity distribution, microstructural evolution and resultant mechanical performance, emphasizing the effects of thermal processing on structural behavior during compression loading and heating experiments via in situ neutron diffraction.

9:50 AM  
Influence of Powder Characteristics on the Defects and Oxidation of High Purity Tungsten Produced via Selective Laser Melting (SLM): Amanda Field1; Luke Carter1; Nicholas Adkins1; Mike Gorley2; Moataz Attallah1; 1University of Birmingham; 2UKAEA
    Tungsten is a candidate material for nuclear fusion applications given the high operating temperatures (2000 oC) required. Conventionally, only solid-state forming techniques have been possible. Selective Laser Melting (SLM) offers a potential processing route for the net-shape formation of the material, allowing greater flexibility in alloying and component geometries. Powder characterisation, to determine size, composition and impurity levels, was carried out on two powders with spherical and faceted morphology. Each powder was then processed via SLM on a 400 W Concept Laser M2 system to produce samples with varying laser scan speeds. The samples were then analysed to determine the prevalence of defects and to investigate the effect of powder characteristics on the oxygen pick-up of samples during processing. Further work will analyse these effects in other refractory metals and alloys.

10:10 AM Break

10:30 AM  
Processing, Microstructure, and Tensile Behavior of MarM-247 Fabricated by Electron Beam Melting: Michael Kirka1; Yousub Lee1; Alfred Okello1; Christopher Romanoski2; Kinga Unocic1; Michael Massey3; Suresh Babu3; Ryan Dehoff1; 1Oak Ridge National Laboratory; 2Vanderbilt University; 3University of Tennessee
    High gamma prime containing nickel base (Ni-base) superalloys represent a defining class of materials that have the ability to operate in high-temperature, high-stress, and corrosive environments while maintaining creep, fatigue, and fracture resistance. These unique properties are attributable to the highly engineered alloy compositions and associated precipitate strengthened microstructure. However, it is these attributes that make it difficult to utilize additive manufacturing techniques to fabricate components of increased complexity over that of traditionally manufactured components due to the crack proneness of the alloys. This study will focus on the processing challenges associated with the fabrication of the Ni-base superalloy MarM-247 in a defect free manner in the electron beam melting powder bed process. Specifically to be discussed are the effects of processing parameters upon defect formation, principally cracking, the microstructure of the as-fabricated material, as well as preliminary findings on the tensile behavior of the as-fabricated material.

10:50 AM  
Additive Manufacturing of Polymer-derived Ceramics: Zak Eckel1; Scott Biesboer1; Kenneth Cante1; John Martin1; Brennan Yahata1; Jacob Hundley1; Tobias Schaedler1; 1HRL Laboratories, LLC
    The extremely high melting point of many ceramics adds challenges to additive manufacturing as compared with metals and polymers. We report preceramic monomers that are cured with ultraviolet light in a stereolithography 3D printer or through a patterned mask, forming 3D polymer structures that can have complex shape and cellular architecture. These polymer structures can be pyrolyzed to a ceramic with uniform shrinkage and virtually no porosity. Fibers and fillers can be integrated to increase toughness and reduce shrinkage on pyrolysis. Silicon oxycarbide microlattice and honeycomb cellular materials fabricated with this approach exhibit higher strength than ceramic foams of similar density. Good oxidation performance at high temperatures is observed. Additive manufacturing of such materials is of interest for propulsion components, thermal protection systems, porous burners, microelectromechanical systems, and electronic device packaging.

11:10 AM  
A Comparison of Mechanical Properties of Additively Manufacturing and Conventionally Manufactured Components: Joy Forsmark1; 1Ford Motor Company
    Mechanical properties were determined from different locations in an engine sealing component manufactured using both conventional high pressure die casting of an Al A380 alloy and a powder bed laser (PBF) sintering process of an AlSi10Mg alloy system. The additively manufactured components were built in three different orientations. This paper will explore the differences in mechanical behavior for the excised samples tested and compare the microstructure and fracture surfaces for samples tested in similar locations in each of the components.

11:30 AM  
Additive Manufacturing of Alloy 718 by Powder Bed Fusion Methods: John Porter1; Brian Hayes1; Kenneth Davis2; Holly Garich3; Francesco Simonetti4; 1UES Inc; 2CalRAM; 3Faraday Technology, Inc.; 4University of Cincinnati
    A comparison study was undertaken to select a Powder Bed Fusion Additive Manufacturing approach for a specific part using Alloy 718. The two approaches were Electron Beam Melting and Selective Laser Melting. Post build treatments included hot isostatic pressing for pore elimination, heat treatment, and the electrochemical surface finishing of internal surfaces. The evaluation involved a comparison of shape accuracy, surface finish, microstructure, and mechanical properties. The electrochemical surface finishing of internal surfaces was performed using the FARADAYIC® process, that enables surface finish control on surfaces inaccessible to machining. Surfaces and microstructure were characterized by light and scanning electron microscopy. 3D microstructural anisotropy and open porosity were measured using scanning acoustic microscopy and a RoboMet-3D™ serial sectioning instrument. Mechanical testing was performed on subscale samples built as tensile-test blanks and on coupons excised from the manufactured parts. The attributes of the two powder bed fusion approaches were then assessed.