PowderMet          AMPM          Special Interest

138 - Development of Advanced Lubricants for New PM Applications
Kylan McQuaig, Hoeganaes Corporation

As the powder metallurgy (PM) industry continues to evolve, the need for highly-effective, clean-burning, environmentally-friendly lubricants becomes more evident.  PM parts are becoming more complex and require higher strength with less weight, necessitating a push for components with higher green and sintered density.  While many lubricants have been developed over the years, newer advanced lubricants have been conceived that are both more lubricious and cleaner burning than their previous counterparts, opening the compaction operating window.  Superior lubricants can be used at lower additions to achieve higher density without the need for heated tooling into a tight temperature range.  They can also allow for easier de-lubrication during sintering, which lessens their environmental impact, results in cleaner parts, and improves magnetic performance when used in soft magnetic applications.

047 - Understanding the Mechanical Properties of PM Steels Through Quantitative Metallography and Fractography with the Aid of Artificial Intelligence
Simon Gelinas, Université Laval

The microstructures of powder metallurgy steel components, especially those made from premixes, are known to be complex due to the presence of a diversity of stable and metastable phases, as well as pores. Similarly, this microstructure heterogeneity also characterizes the fracture surface of these specimens where an entanglement of different fracture modes can be observed. In addition, the presence of certain phases in certain volume fractions or located in critical areas such as grain boundaries can act as preferred path for crack initiation, propagation, and fracture. In this work, Deep Learning algorithms were trained and used as tools to deal with the tedious and complex task of segmenting a large number of highly inhomogeneous micrographs and fractographs where individual elements are not easily discernable. The quantitative values derived from the segmented microstructure and fracture surfaces allowed to establish correlations between the proportion of specific phases and variations of mechanical properties as well as changes in the preponderance of certain modes of failure. 

030 - Tooth Root Bending Fatigue Strength of Sintered Small Module Spur Gears
Alberto Molinari, FAPMI, University of Trento

The tooth root bending fatigue strength of small module spur gears was investigated. Gears were produced with low alloyed powder mixes with different carbon contents and density. Gears were either through hardened or carburised. Fatigue strength increases with green density, while the effect of the carbon content depends on the chemical composition of the base powder. The results were interpreted with the Murakami approach and the effect of the hardness and of the microstructural characteristics of the steels was discussed.

152 - Strategies for Melt System Design for Use with Reactive and High Temperature Materials
David Byrd, Ames Laboratory

Close-Coupled Gas Atomization (CCGA) is an excellent method for producing metal powders for both production and research applications. A push for rapid development of innovative and advanced alloys for use with Additive Manufacturing (AM) has pushed for developing strategies to overcome the challenge of how to melt and contain these alloys that contain reactive element additions and/or require high melting temperatures. In this work, various ceramic melt system designs were evaluated for compatibility with advanced materials with respect to chemical and thermal requirements up to 1,800 °C, useful in a CCGA atomization system. Specially made components using a Plasma Arc Spraying (PAS) process were combined with traditional ceramic melt system components to provide a robust containment for these alloys. These melt systems have proven able to contain and deliver these alloys to the atomization die with the necessary superheat to atomize. Support from USDOE-EERE-AMO through Ames Laboratory under contract no. DE-AC02-07CH11358.

143 - Production Scale Plasma Atomizer for Reactive and Refractory Metal Alloys
Aamir Abid, Retech Systems LLC

A barrier to broader adoption of refractory and reactive metal powders (like Titanium and its alloys) is centered on the combination of the net cost of production for specified powders and the availability of suitable capacity to address the demand. Additionally, though firms are producing similar powders using a range of technologies, not all available powders are compatible with current additive manufacturing systems nor have all the potential alloys been available in powder form to be applied to any particular application. With that in mind, Retech has undertaken a focused effort to develop an atomization system that would provide a larger production capacity of a range of metal and alloy powders utilizing Plasma Arc Melting (PAM) in combination with gas atomization. Plasma melting allows for the introduction of a broad range of feed materials including revert without incurring the additional cost of processing feed to wire or bar forms. With this flexibility of feed materials, recycling high-value materials become an economically viable option. The powders produced on the Plasma Atomizer are spherical with minimal satelliting and low internal porosity. Powder Particle Size Distribution (PSD), morphology, and chemistry will be presented in this study and these results will be compared to the current state-of-the-art commercial atomized powder technologies. 

060 - Further Developments in Close-Coupled Transferred Arc Plasma-Wire Atomization
Joseph Tunick Strauss, FAPMI, HJE Company, Inc.

Prior work by the authors with the close-coupled transferred arc plasma-wire atomization process indicated that it was mostly competitive with non-transferred arc plasma-arc atomization with respect to specific energy consumption. However, there was room for improvement on the gas/metal mass ratio in order to match that of the non-transferred arc plasma technology.  This paper will outline the methods used to identify areas where the process hardware could be modified for improved efficiency. The performance in terms of specific energy usage, gas/metal mass ratio, and powder yields will be reported.

219 - Development of Oxygen Additions for Design of Gas Atomization Reaction Synthesis Processing of Oxide Dispersion Strengthened Alloys
Emma Cockburn, Iowa State University

Mechanical alloying (MA) has been a focus in developing processing methods for oxide dispersion strengthened (ODS) alloys for ultrahigh temperature and/or high-flux radiation tolerant applications, such as nuclear power. MA, while capable of providing “mechano-chemical” mixing of yttria and alloy (Fe- or Ni-based) powders, is time-consuming and may introduce contamination and inhomogeneities. Gas atomization reaction synthesis (GARS) for producing powders for ODS alloy processing provides a cleaner feedstock of powders with Cr-enriched surface oxides and Y-containing intermetallics, creating oxide dispersoids during laser-powder bed fusion additive manufacturing and solid-state friction/stir consolidation by indirect extrusion fabrication. To design the atomization gas composition for GARS process, electromagnetic levitation (EML) experimentation is being developed to examine the effects of gas mixtures on a “macro-sized” droplet to characterize surface oxides and oxide dispersoid generation. EML results will be compared to computational models and atomization results. Funded by USDOE-ARPA-e program through Ames Lab contract no. DE-AC02-07CH11358.

023 - Investigation of the Ceramic-Metal Interface of Modified Powder Metallurgy Steel
Craig Stringer, Atlas Pressed Metals

Powder metallurgy is a capable metal forming technology that can economically produce complex geometries from a wide variety of metal alloys. Inherent to traditional powder metallurgy manufacturing, however, is internal porosity that influences bulk properties such as strength and apparent hardness which typically results in the powder metallurgy alloy measuring to a lower value than its wrought counterpart.  Previous investigations have looked at various techniques to infiltrate the internal porosity with metallic alloys or other nonmetallic material to improve the overall bulk properties with varying success.  In this paper, several ceramic based constituents are incorporated into the powder metallurgy metal matrix forming a composite structure with multifaceted ceramic-metal interface features.  Evaluations of the ceramic-metal interface is presented along with measurement of apparent hardness, composite strength, wear resistance and corrosion resistance.

027 - Development of Ultrafine Electrolytic Iron Powders with High Dendriticity
Ivan Lorenzon, Pometon SpA

The role of iron powders  is very important in a lot of applications because of  peculiar  chemical-physical properties of this essential metal for the industry. The morphology of these particles confer some limitation in terms of compressibility and compatibilization of iron powder within  the matrix (metallic, organics) or with the added micro-charges. To improve both compressibility and interaction with other materials, a new family of  iron powders are being developed which provide purity and granulometries similar to those of iron from carbonyl iron but with completely different morphology and suitable for applications involving the use of a large amount of fillers (metallic or inorganic). The morphology of these innovative powders is used to create an iron structure / skeleton that retains the highest  amount of other elements. Such elements would not  bind together with only the cold compaction, with final result of fragile mechanical components  presenting also difficulty  to the  handling  before sintering or consolidation (compaction) process.  This study, aimed at developing dendritic iron powder with high degree of complexity of the dendrites, find a particular interest in applications  like brake pads for the automotive sector, diamant tools, electrodes for batteries, food and more. A multi-year R&D program in collaboration with producers and high-profile R&D centres, gives fundamental guidelines to facilitate the process of new formulations providing a systematic set of data,  related to the most typical chemical, physical and mechanical characteristics of this innovative powder.

076 - Metal Binder Jetting of Superalloy Impeller for Turbocharger Application
Mattia Forgiarini, Azoth

Metal Binder Jetting (MBJ) is a promising Additive Manufacturing (AM) technique as it can be used to form complex geometries out of almost any type of powder without the use of heat input at high production rates and low manufacturing cost.  In this work MBJ printing is explored as a fabrication process for an impeller composed of a Ni-base superalloy for a turbocharger application.  Conventional wrought and machining methods used to manufacture impellers to-date offer good mechanical properties for end-application performance however the high material “buy-to-fly” ratio has drawn interest to explore AM approaches. Fusion-based AM technologies, such as laser and electron beam powder bed fusion, are limited with deposition rates and are challenged to print high gamma prime/gamma double prime strengthened Ni-base alloys due to their poor weldability. For these reasons, the development of 3D printing and post-processing approaches using fusionless MBJ for Mar M 247 was investigated.  Conventional post-process Hot Isostatic Pressing (HIP) and heat treatment was applied to establish baseline microstructural and mechanical property data along with the evaluation of an over-speed impeller spin test. Results were then leveraged to establish process-structural-property relationships for further optimization of the microstructure through post-process combined HIP and heat treatment to maximize part performance. 

133 - Comparison of Nitinol Fabricated via DMLS and Binder Jet Printing
Joseph Grohowski, Praxis Technology

Nickel-titanium materials are of interest not only for their shape memory properties but also because of their super-elastic behavior. Powder based forming routes offers exciting possibilities for more versatile and economical forming of super-elastic nickel-titanium alloys. Additive manufacturing offers the further advantage of the rapid prototyping or manufacturing these articles. Nitinol articles formed by DMLS and binder jet are compared on the basis of microstructure and mechanical properties.

140 - HDH Ti-6Al-4V Alloy for Laser Powder Bed Fusion
Edel Arrieta, University of Texas, El Paso

Ti-6Al-4V is one of the most commonly used titanium alloys due to its excellent mechanical properties and its corrosion resistance. This makes it a great candidate for aerospace and biomedical applications. In Laser Powder Bed Fusion (LPBF) Ti64 is most commonly utilized in its Gas Atomized (GA) form as this yields good processability and mechanical properties. The high cost of GA Ti64 material is a significant cost driver in the AM process. Ti64 HDH (Hydrogenation-Dehydrogenation) is a melt free powder production process that produces a lower-cost form of titanium powder using traceable recycled feedstock. Compared to its spherical GA counterpart, HDH powder is angular in shape and larger in particle size. These attributes can hinder the LPBF processing of these powders and negatively impact the mechanical properties of the final part. However, this study shows that process parameters can be developed for this particular material, along with standardized Hot Isostatic Pressing and Annealing, which results in mechanical properties similar to that achievable with GA powder while reducing cost. In this study LPBF Ti64 HDH samples were fabricated, heat-treated, and HIP-ed in three different variants. They were then machined and tensile tested in accordance with ASTM E8 standard. Each variant was then analyzed for density, microstructure, and chemical composition.

077 - Fabrication of High Temperature Parts Composed of Titanium-Zirconium-Molybdenum Alloy (TZM) Using Powder Bed Fusion (PBF)
Michael Brand, Los Alamos National Laboratory

High temperature structural materials are in great demand for power, chemical and nuclear industries which can perform beyond 1000oC as super alloys usually fail.  Mo based TZM (Titanium-Zirconium-Molybdenum) alloy is capable of retaining strength up to 1500°C with excellent corrosion compatibility against molten alkali metals.  Currently this alloy is considered an important candidate material for high temperature compact nuclear and fusion reactors.  Due to the reactive nature of Mo and having a high melting point manufacturing this alloy by conventional process in unsuitable.  Complex shapes using complex materials can be fabricated by using the Powder Bed Fusion (PBF) process.  Using PBF, ideal parameters for TZM alloy will be developed.  Tensile bars and small replica reactor parts will be fabricated.  Mechanical properties obtained from parts fabricated by the conventional process will be compared to the mechanical properties of the additive manufactured parts.

037 - Effect of Building Orientation and Specimen Position on the Properties Ti-6Al-4V Alloys Manufactured via L-PBF
Paul Davies, Sandvik Additive Manufacturing

The Ti-6Al-4V alloy is of great importance for the medical, aerospace and automotive industries due to its biocompatibility, corrosion resistance and high specific strength. As the production of complex-shaped materials via additive manufacturing technologies develop rapidly, a special attention is given towards understanding the effect of the microstructure evolution on the mechanical properties of Ti-6Al-4 parts. In this work, the assessment of atomized powders is thoroughly carried out, followed by manufacturing via laser powder bed fusion (L-PBF) and post-processing heat treatments, including hot isostatic pressing (HIP). Fundamental knowledge is built through the analysis of the resultant microstructure and mechanical properties. Room temperature tensile strength and impact toughness properties are reviewed. The presence of defects and their influence on the performance of heat-treated and HIPed parts, as well as the influence of processing parameters and specimen orientation are also discussed to evaluate building parameters and optimized heat treatments to achieve superior properties.

072 - Contributions of Post-Processing and HIP to the Fatigue Properties of Ti-6Al-4V from Laser Powder Bed Fusion
Richard Schleusener, University of Washington

The surface texture resulting from Laser Powder Bed Fusion (LPBF) additive manufacturing (AM) is detrimental to the fatigue properties of metal components. Hence, surface treatment and complementary post-processing methods are presently sought for improvements. Here, fatigue specimens of Grade 5 Ti-6Al-4V were produced by LPBF, stress relieved and then subjected to chemical polishing, centrifugal barrel polishing, machining, and dry polishing; selected groups were subjected to hot isostatic pressing (HIP) prior to the surface treatment. Results showed that internal pores exposed by machining or other aspects of material removal substantially decreased the fatigue life and its consistency across specimens. Although machining did not produce the lowest surface roughness, it provided the largest improvement in fatigue life. Interestingly, while the HIP treatment decreased the internal porosity significantly and promoted an improvement in the fatigue performance in general, the results were not consistent across all the surface treatment methods.

232 - Recent Developments in Binder Jetting of Ti-6Al-4V
Tim Daugherty, ExOne

Binder jet additive manufacturing (BJAM) of Ti-6Al-4V allows for the manufacture of complex geometries in large volumes.  Production of Ti-6Al-4V by binder jet additive manufacturing (BJAM) has been elusive in part because of the difficulty in balancing density, microstructure, and chemistry, all of which are critical to both mechanical property outcomes and material specifications. In this work, the current state of the art for BJAM of Ti64 will be discussed including specific examples of sintered microstucture, density, chemistry, and material properties printed using an ExOne InnoventX modified with a controlled atmosphere. Lastly a case study will be presented showcasing the ability to improve Ti64 dimensional control using Desktop Metal’s Live Sinter Software.

073 - Powder Production of Grade Ti-6Al-4V for Laser Powder Bed Fusion: Contribution to Metal Quality and Properties
Richard Schleusener, University of Washington

As metal Laser Powder Bed Fusion (LPBF) additive manufacturing nears industrialization, powder feedstock economics is of greater importance.  Here, powders of Grade 5 Ti-6Al-4V produced by gas atomization (GA) and plasma atomization (PA) were acquired from different sources and used to produce metal with consistent design and process parameters. The metal quality was evaluated in terms of the microstructure, porosity, and mechanical properties after stress relief, and after a HIP treatment. In the stress-relieved condition, the metal produced with the GA powder exhibited lower yield and ultimate tensile strength (approx. 10%) with respect to that produced with PA powder. The metal produced with GA powder exhibited anisotropy, with lowest ductility for horizontal specimens built parallel to the build plate. Application of the HIP treatment improved properties of the GA metal to near equivalent to that of the PA metal, which provides a strategy for lowering cost.   

165 - Current State of SMC Technology and Electrification Trends in the Auto Industry
Bruce Lindsley, Hoeganaes Corporation

Electrification in the automotive industry has the potential to be a major disruption to the conventional powder metallurgy (PM) component industry. While the transition from the internal combustion engine to battery electric vehicles would eliminate many traditional PM applications in the engine and transmissions, numerous opportunities exist using PM soft magnetic composite (SMC) technology. This SIP will provide an update on the current state of SMC technology and electrification trends, SMC material properties, transmission evolution, E-motors and design and alternative approaches to SMC manufacturing.

166 - Trends & Standards Committee Update
Roland Warzel III, North American Höganäs Co.

Electrification in the automotive industry has the potential to be a major disruption to the conventional powder metallurgy (PM) component industry. While the transition from the internal combustion engine to battery electric vehicles would eliminate many traditional PM applications in the engine and transmissions, numerous opportunities exist using PM soft magnetic composite (SMC) technology. This SIP will provide an update on the current state of SMC technology and electrification trends, SMC material properties, transmission evolution, E-motors and design and alternative approaches to SMC manufacturing.

167 - SMC and E-Motor Case Studies
Chantal Labrecque, Rio Tinto Metal Powders

Electrification in the automotive industry has the potential to be a major disruption to the conventional powder metallurgy (PM) component industry. While the transition from the internal combustion engine to battery electric vehicles would eliminate many traditional PM applications in the engine and transmissions, numerous opportunities exist using PM soft magnetic composite (SMC) technology. This SIP will provide an update on the current state of SMC technology and electrification trends, SMC material properties, transmission evolution, E-motors and design and alternative approaches to SMC manufacturing.