PowderMet          AMPM          Special Interest          Carbide Forum

520 - Leveraging Powder Metallurgy Sustainability: From Theory to Practice
Kyle Unger, North American Höganäs Co.

The powder metallurgy (PM) industry can fulfill increasing sustainability demands by integrating practical initiatives within business practices. Consumers and original equipment manufacturers (OEM) are expecting their suppliers to produce circular and low CO₂ emission materials. Previous research has concluded that PM is intrinsically more sustainable than competing technologies due to its lower energy intensity and increased material utilization. Life Cycle Analysis (LCA) will be used to demonstrate how PM can meet the expectations from consumers and OEMs for reduced CO₂ emissions. Sustainability actions that can be taken by manufacturers to meet lower emission guidelines and show compliance will also be discussed. 

521 - The Significance of Sustainability for the Powder Metal Industry
Ian Donaldson, FAPMI,GKN Sinter Metals

There is an evolving landscape of sustainability that requires the Powder Metallurgy (PM) industry to make critical assessments of their strategies to address it.  This sustainable movement is driven by a combination of factors including increased energy risks, climate change impact, emerging regulations, a fast-growing demand for non-renewable minerals, and a growing consumer desire for greener products.  Industries globally are required to deal with their ecological impact and place heightened focus on improving their sustainability performance.  Highlights of the motivations for building a sustainable organization plus the importance of tactics such as integration of data and the role of digitalization on the path to a more sustainable future are discussed.

522 - Sustainable Production of High-Performance Metal Powders for Additive Manufacturing
John L.L. Meyer, 6K Additive

Additive manufacturing (AM) is recognized as a green production technology, with significant gains in material utilization, lower buy-to-fly ratios, and reduced generation of scrap (that in cases would otherwise be destined for landfill). Atomization processes (commonly used to produce metal AM feedstock) have a strong track record in quality and economy of scale but have historically been burdened by low yields which have left room for improvement in terms of environmental impact. A third-party study was conducted by Foresight Management to quantify the environmental impact associated with the production of AM powder comparing 6K Additive’s UniMelt process vs. atomization. The results from this study showed 6K Additive’s microwave plasma powder production process utilizing sustainable metal feedstocks resulted in 91% less energy and 92% less carbon emissions (global warming potential) for a nickel alloy and 74% less energy and 78% less carbon emissions for a titanium alloy.

079 - Production of ODS-Ferritic Alloys Using Gas Atomized Reaction Synthesis (GARS) Powders and Conventional PM Methods for Long-Life Reactor Fuel Assembly Ducts
Jordan Tiarks, Ames National Laboratory

Development of methods to produce (pyrochlore) oxide-dispersion strengthened (ODS) ferritic alloys using conventional powder metallurgy (PM) techniques can provide a cost-effective method of enabling adoption of these high-performance alloys for use in extreme environments (e.g., high temperature, irradiation). A two-step process drives the formation of nanoscale oxide precipitates through a high-temperature thermally-activated oxidation exchange reaction after consolidation. Precursor powder feedstocks based on a modified “14YWT” alloy, 82.4Fe-14.0Cr-0.20Y-3.0W-0.4Ti (wt.%), were produced via gas atomization reaction synthesis (GARS). This powder was then consolidated to full density using vacuum hot pressing (VHP) at a temperature chosen to promote densification and partial sintering and followed by hot rolling to sheets. Final annealing was chosen to drive the formation of nano-pyrochlores and achieve full strength. This presentation will focus on work-to-date in GARS powder production, consolidation via VHP, and development of hot-rolling and annealing. Work funded by USDOE-NE through Ames Lab contract DE-AC02-07CH11358.

095 - Investigation of Novel Pour Tube Geometries Using 3D Printed Geometries for Close-Coupled Gas Atomization
Trevor Riedemann, Ames National Laboratory

In close-coupled gas atomization, the geometry of the pour tube extension affects the performance of the gas die. Each unique pour tube geometry has unique aspiration pressure curves that promote or deter lick-back. The geometry also facilitates closed-wake or open-wake gas flow across die manifold pressures. Recently, the proliferation of 3D printers has lowered the cost and timelines required to test novel geometries in gas-only flow and water-test atomization. This work evaluates a matrix of geometries including straight wall, isentropic plug nozzle, and hemispherical pour tube ends for aspiration. Down selected geometries will undergo water atomization testing. This work is funded by the U.S. Department of Energy through Ames National Laboratory contract DE-AC02-07CH11358.

123 - Minimum N2 Purity Required to Sinter Iron, Steel, Low Alloy Steel, and Stainless-Steel Parts
Harb Nayar, TAT Technologies

Since the introduction of N2-H2 atmospheres as a replacement of Endo gas 45 years ago, the standard guideline has been the N2 used should be of high purity i.e. 99.999+% pure i.e. O2 less than 10 ppm.

Lately, the question being asked in the PM industry is: Do we really require O2 to be less than 10 ppm in the N2 portion of the N2-H2 atmosphere for sintering? How much more O2 in N2 can be used without affecting the properties of the sintered parts as compared to the high purity N2? This paper answers these two questions by sintering “green” PM parts made from a variety of commonly used compositions in the industry. The sintering at 2050F will be carried using the 6-zone belt furnace at TAT Technologies. The study will cover 5 different levels of O2 from 10 ppm to 500 ppm in N2 blended with high purity H2 before introduction into the furnace. The actual PM parts for the study used will be acquired from local PM parts makers. Parts will cover the following powder families: Fe, Fe-C, Fe-CU-C, low alloy steels and Stainless steel. Sintered parts will be evaluated by the parts suppliers for appearance, hardness, Carbon loss and selected tensile strength etc. Some microstructures will be included. Atmosphere composition in HH section will be recorded for H2, O2 and Dew point under both before and during sintering for all five N2 purity levels.

007 - The Effect of Nanocrystalline Ni-Ti-B on the Structural, Mechanical, and Corrosion Aspects of Aluminum 6061
Arun K. Chattopadhyay, Uniformity Labs

The impact of introducing nanocrystalline Ni-Ti-B into Aluminum 6061 composites was examined by structural, morphological, corrosion, and mechanical properties. The phases, microstructure, and distribution of Ni-Ti-B were studied by XRD, SEM, and EDAX. Alloy's mechanical strength was assessed by hardness, compressive strength, and wear properties. Electrochemical impedance spectroscopy and potentiodynamic polarization tests were carried out to assess the corrosion resistance of the alloy. Experimental findings indicate that increasing the proportion of nanocrystalline Ni-Ti-B had a positive impact on the overall homogeneity of the composite structure. However, localized agglomeration of nanocrystalline Ni-Ti-B particles and the formation of porous regions were also observed. These observations suggest that achieving a perfectly uniform distribution of the reinforcement material may pose certain challenges.

088 - A Wire Arc-Directed Energy Deposition-Based Method for High-Throughput Alloy Design for Fusion Additive Manufacturing
Saket Thapliyal

The need for designing alloys specifically for fusion-based additive manufacturing (F-BAM) processes becomes underlined by the fact that certain alloys that are processable with conventional processing routes exhibit deteriorated processability with F-BAM. While the data driven and machine learning approaches to alloy and microstructure design are on the rise, an accurate control of the processability, microstructure, and component properties requires accurately capturing the overall process physics, including process thermokinetics. Even though multiscale computational frameworks can be attractive for capturing process physics, the validation of such computational frameworks for F-BAM microstructures still requires experimental methods that can represent F-BAM process thermokinetics and the effect thereof on the alloy microstructure and properties. To this end, we report a wire arc-directed energy deposition (WA-DED)-based high-throughput experimental approach for microstructure and alloy design for F-BAM. Examples that establish the significance of such high-throughput experimental method for validating the CALPHAD-trained machine learning models are also discussed. Furthermore, considerations in alloy design for F-BAM using such high-throughput approach are highlighted with examples. Overall, findings will facilitate integration of F-BAM-based high throughput alloying approaches with computational alloy design and enable microstructure control with F-BAM.

074 - AI-Based Feedstock Compositional Design
Patxi Fernandez-Zelaia

Feedstock compositional variability can have significant impact on the material's process response. In many cases precise control of minor alloying elements is impossible or extremely cost prohibitive. Hence, there is a need to develop methods for identifying robust alloy compositions for specific applications. Modern machine learning and AI-based generative models are extremely expressive and excel in operating on various data modalities e.g. images, text, tabular data, etc. In this work we demonstrate the use of AI-generative models, trained using computational thermodynamics data, for alloy design tasks. We specifically focus on a UNS N07718 binder jetting example where we target a composition that is robust against variability in C and B content. Our method identifies a range of compositions that ensure good sintering behavior yet still fall within the bounds of currently existing specifications. Results indicate the proposed method is effective and potentially a useful tool for quality assurance and compositional design tasks.

023 - Porous Sinter-Based Metal AM Structures for Medical and Filter Applications
Christian Staudigel, Headmade Materials GmbH

The sinter-based metal additive manufacturing (AM) process is known for reliable serial production in metal AM with high part quality. In this presentation, the speaker will share of this new sinter-based metal AM process combines standard PM metal powders with its proprietary binder system to form a powdery feedstock that can be processed into green parts on standard plastic laser sintering systems. The subsequent debinding and sintering step is again PM industry standard and the part characteristics are fully comparable to MIM in terms of density and strength. But it can also be used to produce porous parts up to 50 vol% porosity. Even gradient porosity and parts with dense and porous sections are possible. The influence of feedstock, laser sintering parameters and sintering parameters on porosity and the potential in filter applications and medical industry will be shown in this study.

010 - Optimization of Multilaser Laser Powder Bed Fusion in High Carbon Steels Using Advanced Finite Element Simulations
Juan Martínez Alvarez, ArcelorMittal

Using an advanced proprietary finite element method code, our teams have delved deep into the science of laser pathways. The objective has been clear: to achieve a holistic and uniform heat distribution while drastically reducing any harmful thermal gradients.
One of the most notable triumphs of our novel methodology is its capacity to efficiently handle high carbon steels. Our method sidesteps the high temperature buildplate preheating entirely, providing a more streamlined and agnostic process to the machine.
Every design input in our system is subjected to a detailed thermal evaluation. This iterative process ensures that the laser sequencing is constantly refined and optimized. Central to this optimization is a bespoke function that we have developed, aimed expressly at mitigating areas of excessive heat concentration, ensuring the uniformity of the process. Dilatometry experiments have determined the level of heat and cooling rate of our target function. These benchmarks not only provide invaluable data but also act as pivotal reference points, guiding our thermal simulations and ensuring their accuracy.
To quantify and showcase the tangible benefits of our approach, we have undertaken comparative studies. By analyzing the microstructure at both, macro and micro level between the optimized and classic approach. The results proved that could be an approach to produce tool steels where solidification issues are common in LB-PBF parts.

143 - Pulsatile Gas Atomization Theory and Process Revisited: A Visual, Computational and Empirical Examination
Jason Ting, Elementum3D

The pulsatile atomization phenomenon in close-coupled liquid metal gas atomization is revisited to recognize how spray atomization of aqueous liquid for fuel combustion, in aerospace engineering, can be applied to gas atomization of molten metal for metal powder production for the metal MIM, PM and AM industry. 

​The relationships between the liquid metal flow rates, the aspiration pressure (gas only condition) at the melt orifice, and the atomization operating pressures of the atomizer will be revisited and explained, as this is  crucial to the production of fine metal powder.  These parameters are frequently interdependent, therefore the critical controls of these gas atomization variables require one to understand the fundamental of gas dynamics phenomenon.  A phenomenological two-phase fluid dynamic model coined “pulsatile atomization” is presented and discussed to elucidate the above relationships.  The investigation of these atomization variables was originally performed on an industrial melt atomizer system, but subsequently verified by other researchers and powder producers. This atomization model is reviewed, with CFD modeling, and High-Speed Cinematography to show the relationship between gas-only aspiration pressure and the melt atomization process.

404 - Grade Design of Cemented Carbide, Tungsten Carbide with Binders; and the Effect of Minor Additive Additions
Robert Scott, H. C. Starck Tungsten LLC

Cemented carbides are one of the most widespread powder metallurgy products, containing hard Tungsten Carbide (WC) in a ductile metal binder. The main applications include metalworking, mining, wear components in ground engaging tools, and oil and gas drilling. The most widely used binder is Cobalt (Co), and in some cases Nickel (Ni) or combination of Ni and Co. This tutorial will give a brief summary of the production process of WC, from the ores and scrap materials to Tungsten metal and finally, carburization. WC grades can be designed with the desired combination of properties by choosing the grain size, binder content, and additives. The importance of additives such as NbC, TaC, VC, and Cr3C2 and their influence on the properties will be described. The physical-chemical properties tested on the powder and sintered parts and their effects on the final properties of the cemented carbide will be discussed.

405 - Alternative WC Binder Materials
Johannes Pöschke, IKTS - Dresden

Cobalt is, since the invention of cemented carbide, the binder metal of choice for use in WC based tools. Within the last years several reasons like the cmr (carcinogenic, mutagenic or toxic to reproduction) and crm (critical raw material) classification as well as the use of cobalt in lithium ion battery have resulted in the search of alternative more safe and potentially cheaper metal binders. Within this contribution an introduction to the needed properties and functions of metal binders in WC based cemented carbides are presented and a general overview about possible alternatives to cobalt is given. Next to commercially available grades based on nickel, iron-nickel or nickel-chrom, novel binder metals like high entropy or intermetallic alloys are discussed and their properties as binders in cemented carbides compared to cobalt.

406 - Corrosion Resistant Carbide Grades
Madison Rase, Hyperion Materials & Technologies

The combination of a hard metal phase and a binder phase in cemented tungsten carbide results in a complex corrosion mechanism. The hard metal phase is susceptible to corrosion in alkaline conditions while the binder phase is susceptible in acidic conditions, so it is not practical to apply a single solution wherever corrosion is a concern. Additionally, many of the levers available for impacting corrosion resistance, including grain size, binder content, magnetic saturation, and additives, also impact the final hardness, strength, and toughness of the material. As a result, the working environment needs to be considered alongside points of performance when selecting a grade for a given application. This session will review the methods available for improving corrosion resistance and their suitability for different working conditions, impacts to other physical properties that should be considered, and best practices for grade selection.