PowderMet          AMPM          Special Interest

017 - Evaluation of Tungsten Heavy Alloy Magnetic Properties with Respect to Their Composition for Balancing Weights
Rafael Cury, Plansee Tungsten Alloys

Tungsten heavy alloys are regularly used as a dense material on any application requiring balancing weights. From watch industry to aerospace, some of these alloys must show the ability to function without being affected by magnetic field. Iron and Cobalt are commonly used as an alloying element, along with Ni which is the main alloying element. Those 3 alloying metals are widely known as material which can be affected by such fields. Yet, depending on the concentration and the temperature, the properties might vary. Indeed, it is thus possible to have alloys used at room temperature containing certain amount of iron or cobalt without showing ferromagnetism. 

The use of WHA for balacing weights is widely known. The presence of Fe is always questioned and some customers prefer to have W Ni Cu alloys instead. Those alloys can be quite adapted to their application but other options are also available as W Ni Fe or W Ni Co with both Fe and Co in low content in certain temperature ranges. 

012 - Co-Free Cemented Carbides for Percussion Drilling
Markus Fürst, Vienna University of Technology

Since their discovery exactly one hundred years ago, WC-Co cemented carbides (hardmetals) have been well-established composite materials extensively used in multiple fields of industry such as cutting applications, drilling, mining, and milling, due to the combination of high hardness and toughness. In recent years the partial or complete substitution of Co as the metallic binder has been a central topic of hardmetal research for economical, legal, ethical, and health-related reasons. The presented work focuses on the complete substitution of Co as the binder element in WC hardmetals used in percussive drilling applications. Other suitable metallic elements in Ni-based binders have been used to strengthen the binder via the well-known principles of solid solution strengthening and precipitation hardening. After successfully establishing suitable candidates by comparing the microstructure, HV and KIc with Co-containing reference materials from industrial partners, wear tests such as the ASTM B611 test were conducted to simulate the high stress abrasion conditions in percussive drilling. The results show that alloys of other transition group metals can compete with Co when used as the binder matrix in hardmetals and upon further optimisation may very well be viable candidates for Co replacement.

115 - Optimizing the Sintering Process of High-Performance Carbides
Mathias Mallman, Graphit Kropfmühl GmbH

The demand for carbide tools and components with highest quality, as well as the constantly rising costs for energy and raw materials, make optimization of the sintering process of high-performance carbides indispensable. The coating of the carrier plates with graphite- and ceramic-dispersions plays a decisive role, ensuring separation between component and plate as well as optimized grain growth.  Graphit Kropfmühl GmbH (GK), a manufacturer of graphite-containing dispersions, has been providing high-performance results in Europe for this sintering application with its Grap Aqua series. Due to its own mines located in Europe, Africa and Asia, GK has direct access to various raw materials, with the right one being selected depending on process requirements. Customized dispersions, characterized by a low level of impurities and/or already containing various ceramic components, have been targeted to improve the sintering processes and product quality. The range of coating performances in the carbide sintering application is presented, including a case study from GK’s experience in Europe using its graphite-based dispersions.

068 - Production Experience with Advanced Lubricants for Improved Compaction Performance
Kylan McQuaig, Hoeganaes Corporation

Demands on powder metallurgy (PM) lubricants are intense and complicated due to the wide range of PM processes utilized.  Necessary lubricant properties include ability to mix uniformly at scale, good powder flow and fill in powder premixes, excellent ejection of compacted parts, and clean burn-off behavior during sintering.  Many of the advanced lubricants used in previous generations of PM parts have now been rendered obsolete due to the inclusion of metallic stearates and other unwanted raw materials in their formulation.  Today’s advanced lubricants, such as AncorLube LV, are far more clean-burning and environmentally friendly, resulting in parts with full lubricant removal and a desired surface finish.  This lubricant has now been used in a production setting for an extended period with positive results.  The benefits of this lubricant, the improvements observed, and potential opportunities of using advanced lubricants in varying part geometries throughout the PM process are explored.

112 - Formulation and Performance of Novel Lubricants for High-Density Powder Metallurgy Applications
Mihai Faroga, Stackpole International

This paper investigates the development of high-density lubricants for powder metallurgy applications and their impact on the compressibility, strength, and ejection ability of compacted components. The authors develop a mathematical model to predict the quantity of lubricant required to reach a target density of 7.2 g/cc and 7.3 g/cc, as well as the compaction pressure requirement while maintaining excellent ejection and green strength. The study examines multiple factors that affect the formulation of high-density materials, including the compressibility of the base material, and the type and percentage of lubricants. The performance of the two iron-based powders created, Powder A (FC-0205, 7.3 g/cc) and Powder B (FC-0205, 7.2 g/cc), is quantitatively compared at different densities regarding ejection, green strength, and compressibility. The target total volume is set at 99% (± 0.5%) to achieve the designated densities and ideal compaction environment. The results demonstrate that Powder B consistently presents higher green strength and lower slide ejection, which is expected due to its higher 3.1 GS lubricant content and compressibility curve. On the other hand, Powder A displays more ideal compressibility and peak ejection at its designated density, demonstrating the effectiveness of this predictive model. The study provides valuable insights into optimizing the manufacturing process of high-quality, efficient, and cost-effective components.

039 - Machining Responses of PM Stainless Steel Components Manufactured under Different Sintering Conditions
Bo Hu, North American Höganäs Co.

Powder metallurgy (PM) stainless steels offer exceptional corrosion resistance, but present a very different machinability behavior compared to common carbon and low alloyed PM steels. Since they contain a high alloy content with no carbon addition, stainless steels consist of either an austenitic or ferritic microstructure after sintering. Such types of metallurgical matrixes are soft and form long chips during machining. In addition, work-hardening occurs on the machined surface due to the high alloyed matrix. Generally, the stainless steel (SS) components are preferred to be sintered at high temperature in a vacuum or 100% reducing atmosphere to achieve high sintered density, prevent oxidation and limit metallurgical defects. When they are sintered in a nitrogen-containing atmosphere, nitride formation with chromium occurs in the matrix resulting in a different behavior in machining. In this study, the machining response of a PM 316 stainless steel are evaluated after being sintered at conventional and high temperatures in atmospheres containing different percentages of nitrogen. At the same time, methods to improve the machinability are investigated to provide machining solutions for the related stainless steels.

148 - Correlating Surface Roughness to Processing Parameters through Machine Learning Techniques
Srujana Rao Yarasi, Carnegie Mellon University

Additively manufactured surfaces have an inherent roughness which may be undesirable. In some applications, it can result in fatigue crack initiation sites while in others it serves to increase surface area. There are multiple factors that affect surface roughness, including powder size and processing parameters. The measurement of surface roughness is a data rich problem that can benefit from characterization with machine learning techniques. AM rough surface characterization and subsequently, the relationships connecting the processing parameters to roughness are explored in this study. Build orientation is seen to affect the surface roughness and a Convolutional Neural Network (CNN) is used to distinguish between the differently oriented surfaces. The ability to control surface roughness using process parameters reduces the need for post-processing and furthers our understanding of its impact on mechanical properties

946 - Establishing powder processing temperatures of gas atomized reaction synthesis (GARS) powder to induce precipitation of nano-oxides (NO)
Iver Eric Anderson, FAPMI    Ames National Laboratory

Using the GARS technique to produce an oxide dispersion strengthen (ODS) precursor powder offers a novel approach to oxide dispersoid strengthened (ODS) ferritic steels by replacing old ball milling techniques. A kinetically stable oxygen storage phase, chromia, enables NOs that are composed of Y-Ti pyrochlore oxides to be precipitated during consolidation. The consolidation and working temperatures must remain below the dissolution temperature of chromia in BCC iron. The heat treatment for the precipitation of NOs also must be established. Preliminary in situ X-ray diffraction (XRD) results for (surrogate) 410 water-atomized stainless-steel powder showed chromia dissolution at ~880 C. DSC experiments on gas atomized reaction synthesis (GARS) ODS-precursor powder confirmed chromia dissolution and showed NO precipitation at ~1150 C. However, the limited resolution of laboratory scale XRD necessitated synchrotron level intensities to resolve low volume fractions of chromia and Y-Ti pyrochlore. Supported by USDOE-NE-NEUP-NEET through Ames Lab contract DE-AC02-07CH11358.

142 - Recent Results on a High Strength Al-Mn-Sc Alloy Fabricated by Laser Powder Bed Fusion (LPBF).
James Sears, Amaero Additive Manufacturing

Over the last few years there have been reports of a high-strength, high-temperature Al-Mn-Sc Zr alloy printable in standard Laser Powder Bed Fusion (LPBF) systems with properties exceeding those of conventional 7xxx series alloys. It should be noted that this data was generated using lab scale processing with Zr levels of 0.4 to 0.7 wt. %. This data showed ultimate strength levels exceeding 550 MPa with 12 % elongation in the aged condition and thermal stability at 250 °C of over 3000 hrs. What was not discussed in these papers was the limitation of commercially producing this alloy with elevated Zr levels.

In developing this as a commercial alloy, the need to consider alloying limitations of the casting and atomization processes. To this end, an Al-Mn-Sc alloy with much less Zr was processed to aid to the casting and atomization processes. Two lots of the low Zr alloy were produced by DC casting by an industrial producer. Both lots were converted into powder by a commercial powder producer. The property results from this material after consolidation using LPBF were 475 MPa tensile strength with 13 % elongation. These results show a considerable reduction in tensile strength compared to the previous university work but still represent an improvement for a high strength direct aged printable aluminum alloy. Results from the literature with the elevated Zr will be compared with those from the current work.

178 - High Strength Aluminum Alloys by Additive Manufacturing
Juha Kotila, EOS Finland

High strength aluminum alloys have become very attractive on metal AM. The traditional, wrought high strength aluminum 2000-, 6000- and 7000-series alloys have unique combination of light weight and high strength. Especially in heat treated conditions. But Additive Manufacturing of identical aluminum alloys in high quality without mixed, costly additives has proven to be challenging.  This paper presents properties of 2139-series aluminum intended for AM applications requiring high mechanical properties in room temperature and especially elevated operation temperatures typically experienced in electric and combustion engine applications found in aviation, transportation, racing and space industries. Comparison of properties to wrought high strength aluminum alloys as well as other type AM aluminum grades will be made against the Al 2139 AM parts build using EOS M290 metal AM printer, Al 2139 AM process and suitable heat treatment for optimum performance. Paper will focus on performance of Al 2139 AM parts in long term operating conditions experienced in engine applications. 

098 - An Aluminum Powder Feedstock Designed for High-Throughput Additive Manufacturing Processes
Martin Conlon, Equispheres, Inc.

As metal powder bed fusion moves to scale and challenge traditional manufacturing processes, it imposes new requirements on the metal powder feedstock. This paper presents a comprehensive characterization of a new, novel aluminum alloy feedstock that is designed for the next generation of high throughput laser powder bed fusion machines. We discuss how powder characteristics such as specific surface area, sphericity, and surface condition impact key powder behaviours such as flowability, packing density, and moisture sorption—and how those behaviours influence the stable processing window. Density results and mechanical data are presented.

137 - Directed Energy Deposition (DED) of 6061 Reactive Additive Manufacturing (RAM) Alloy Designed for Additive Manufacturing (AM)  
Chloe Johnson, Elementum 3D

High strength aluminum alloys, such as 6061, 2024, and 7075 are commonly used in traditional manufacturing, but are generally considered unprintable due to solidification cracking in AM processes. In these alloys, a large solidification range leads to hot tearing in the final stages of solidification. Reactive additive manufacturing (RAM) technology enables use of micron-scale reactive particles in the powder feedstock that react in the melt to form nano-scale nucleation sites and produce a fine-grained and crack-free microstructures. This technology has been applied to produce a laser powder bed fusion (LPBF) printable 6061 based alloy, A6061-RAM2, that is heat treatable with properties like that of the wrought product. More recently, this material has been investigated for directed energy deposition (DED) applications, achieving similar performance to LPBF processed A6061-RAM2. Powder characteristics, microstructure, and mechanical properties for DED produced parts using this inoculated 6061 alloy were investigated. This study shows the applicability of high strength aluminum RAM alloys beyond LPBF into large scale AM processes, specifically DED.

121 - Processing High-Strength Aluminum Alloys Using Direct Metal Deposition (DMD®)
Rachael Mancuso, DM3D Technology, LLC

Manufacturing high-strength Aluminum with laser based additive manufacturing is a challenge due to its high reflectivity and tendency towards cracking. However, the combination of light weight and high strength makes these alloys very attractive for various applications in space, aerospace industries. Recent advances in the technology and material synthesis has made AM of such alloys possible. Direct Metal Deposition (DMD) is a type of DED (Directed Energy Deposition) technology utilizing high power laser as heat source and metal powder as feedstock. Recent work on high strength alloys using DMD technology has shown promises to manufacture larger parts using these materials. 
 
This presentation will give a brief overview of the DMD technology highlighting the benefits of the process with a focus on different Al-alloys, such as 2xxx series, cast aluminum series, and Scalmaloy. Furthermore, we will discuss their DMD deposited microstructures and properties. Some sample parts will also be shown as a case study. At the end, we will discuss some potential applications for the space, aerospace, and other industries. 

158 - Varestraint Weldability Testing of Iron Based Super Alloys Built with Blown Powder Directed Energy Deposition Additive Manufacturing
William Evans, NASA Marshall Space Flight Center

In this investigation varestraint weldability testing was conducted on two iron based super alloys used by NASA for rocket engine applications. The purpose of varestraint weldability testing is to compare the susceptibility of a certain alloy to hot cracking during welding operations. The alloys investigated were JBK-75 and NASA HR-1 which are both based on the Fe-Cr-Ni family of alloy. The goal of this study is to compare weldability properties between wrought and LP-DED material and to form a comparison between the two Fe based super alloys. Both metals are designed for their high strength and their hydrogen environment resistance. Three forms of each alloy were investigated during this study: Conventional wrought plate and LP-DED printed plates. Each set of material underwent transverse varestraint weldability testing and spot varestraint weldability testing. During this study the team recorded images of the crack evolution for each sample and measured and recorded total crack length, maximum crack distance, and the overall number of cracks in each sample. The team noted that there were distinct differences in total crack susceptibility between the different alloys and between the alloy forms. A trend was also noted with cracking susceptibility increasing with an increase in parent material grain size. 

091 - Multimodal Powder: A Key to Achieving Superior Properties in Binder Jetting of 17-4 PH Alloy
Sam Imanieh, Uniformity Labs, Inc

In recent years, binder jetting technology (BJT) has gained popularity as an additive manufacturing (AM) technology in various production sectors, including tooling, biomedical, energy, and defense. This technique differs from other powder bed-based AM methods. In BJT, parts build by binding powder feedstock while using post-print furnace cycles to densify the parts instead of using an energy source to melt & fuse during printing. As a result, binder jetting produces parts of relatively lower densities as it depends on a sintering process to densify, which can have a negative impact on part tolerances and mechanical properties. To address this issue, our study explored the use of multimodal powder with novel particle size distributions to increase part density and mechanical strength and the quality of printed material. This study utilized UniJet™ 17-4PH multimodal powder in the Production System P-1™binder jet printer from Desktop Metal. The green parts had a density of 5.05 ±0.03 g/cc and showed a TRS strength of 18±1 Mpa. The sintered density was 7.74±0.02 g/cc. The as-sintered and H900 heat-treated bars complied with MIM - MPIF 35 min. To test the green strength and flowability of the powder, which aids in the depowdering process, we printed a highly complex geometry with thin and inter-channel connections. This was afunctional part meant to be applied as a bone implant and compatible with a specific 3D scan of a bone structure.

036 - Microstructure and Mechanical Properties of 316L Stainless Steel Micro Additive Manufactured Components
Michael Pires, Lehigh University

Over the previous two decades, microfabrication technologies have been developed due to the high demand for micro-sized components. Current additive manufacturing (AM) processes have already made adequate progress in producing small-scale components, but the fabrication of micro-sized components may introduce compromised results. A comparative study between additive (standard-AM) and micro-additive manufactured (micro-AM) 316L stainless steel components was conducted to examine the respective resulting microstructures and mechanical performance. Components were produced via selective laser melting (SLM), binder jetting (BJ), and digital light processing (DLP). Microstructural characterization was performed with optical (LOM) and scanning electron (SEM) microscopy techniques. X-ray diffraction (XRD), X-ray energy dispersive spectroscopy (XEDS), and electron backscatter diffraction (EBSD) were performed to identify and quantitatively measure microstructural phases, grain size, and texture. Uniaxial tensile and microhardness testing was performed at scale for all 316L stainless steel components. Surface roughness was measured to evaluate its contribution to mechanical properties at scale.

180 - Effects of Hot Isostatic Pressing on Microstructure and Mechanical Properties of Vacuum-Sintered Gas Atomized Fine 316L Stainless Steel Fabricated via Binder Jetting
Mohammad Jamalkhani, Illinois Institute of Technology

316L stainless steel (SS) has been received attention as a compatible feedstock in binder jetting. However, characteristic remnant pores in the structure of the as-sintered parts decrease mechanical properties. To optimize the sintering profile providing both densities of >99% and dimensional accuracy, the effect of hot isostatic pressing (HIP) on the microstructure and mechanical properties of the binder jetted fine 316L SS powder was investigated. Sintering temperatures ranging between 1,340-1,430 ℃ and HIP cycles with four combinations of pressure and temperature were selected. After the HIP process, a relative bulk density of 99.43% was achieved at 1,370 ℃ reaching a maximum of 99.76% at 1,430 ℃. Grain coarsening was seen as the sintering temperature increased reaching its peak of 207.41±5.39 μm at 1,400 ℃; however, a slight change in the grain size was detected at 1,430 ℃ due to a noticeable amount of delta-ferrite at the grain boundaries.

519 - The Effects of Element Size and Type on Relative Stress Gradient and Support Factor for Predicting PM Fatigue Life with FKM Guideline
George Coppens, Amsted Automotive

Reports from within the powder metal (PM) community indicate the Forschungskuratorium Maschinenbau (FKM) guideline shows promise for predicting PM fatigue life. The power of the method comes from the ability to increase the local material fatigue strength by a value known as the support factor which is dependent on relative stress gradient. The relative stress gradient calculation includes stress at the surface, stress below the surface, and the distance between those stress values which can all be influenced by finite element size and type. This paper will use finite element analysis (FEA) to study multiple notch geometries when meshed with second order hexahedral and tetrahedral elements of varied sizes. The stress at the notch will be extracted as a function of depth, and the relative stress gradient at different depths will be calculated. The relative stress gradients will be used to calculate support factors to determine sensitivity to element size and type. The results can be used to make informed meshing decisions when creating FEA models.

514 - Soft Magnetic Composite Properties Selection for Design of Advanced Electric Motors
Fabrice Bernier, National Research Council Canada

Due to their unique characteristics, soft magnetic composites (SMC) are attracting interest for the design of novel high performance electric motors. Indeed, SMC exhibit low losses at high frequencies and can allow for new 3D magnetic flux designs that are not feasible with traditional laminated steels. However, SMC typically have lower mechanical properties. In order to take advantage of the enhanced design possibilities while avoiding issues related to SMC shortcomings, powerful electro-magnetic simulation software can be used to optimize envisioned motor topologies. In that context, diverse mechanical, thermal, electrical and magnetic material properties are required as inputs to assess the different motor performance characteristics such as efficiency map, power density and mechanical stability. Losses profile and thermal characteristics are also important for the motor thermal management including establishing the motor cooling strategy. To meet the simulation requirements, traditionally measured and readily available SMC properties are often insufficient. This presentation will discuss SMC properties that are mandatory to include in advanced motor design and simulations and the required tests that need to be performed to obtain them. This will be highlighted through examples where stringent motor requirements in terms of efficiency are leading to SMC characterization and properties selection shifting from a simple magnetic consideration to more a complex compromise between magnetic characteristics, material resistivity, high RPM losses and tensile mechanical requirements.  

515 - Boosting the Strength and Electrical Conductivity of Pure Aluminum and Aluminum Alloys
Pete Imbrogno, MPP

It is common knowledge that using pure copper as the material of choice in applications requiring adequate strength and great electrical conductivity (EC) is preferable. However, the overwhelming increase in the cost and availability of copper is becoming a major concern. As the move towards electrification throughout the world is occurring, so is a parallel move to make aluminum (Al) and Al alloys suitable to function as a replacement for copper, in these types of applications. To make this goal a reality, exploration into enhancements in the strength and (EC) of pure Al and Al alloys is necessary. This study compiles the strength and (EC) for existing Al powdered metal (PM) materials, to better understand what existing data to target future research. Also highlighted in this publication are reviews of completed research projects by industry professionals and academia, noting both shortcomings and successes.