PowderMet          AMPM          Special Interest          TNT Presentations

039 - Making Clean Steels Directly from Iron Ore via a Novel Powder Metallurgy Process
Amir Meysami, University of Utah

The iron and steel industry accounts for around 7% of global greenhouse gas emissions and 11% of global carbon dioxide emissions. The Hydrogen Reduction and Melt-less Steelmaking (HRMLES) process, currently being developed at the University of Utah with support from the US DOE/ARPA-E, is a novel powder metallurgy pathway designed to achieve ultra-low life cycle emissions for steel production. The foundation of this innovation is the direct reduction and alloying from concentrated iron ore to produce steel products without the need for melting, thereby avoiding traditional iron and steelmaking methods. This study explores the hydrogen reduction step in the HRMLES process. The reduction kinetics of beneficiated ore powder with hydrogen for making iron powder were investigated and reported. The gas-solid reduction behavior was studied with thermogravimetric experiments to track the kinetics behavior and dominant mechanism of reaction at temperature range of 600 ˚C to 1000 ˚C. Results indicated that the dominate reduction mechanism shifts between low and high temperatures. Additionally, using weight loss percentage versus time, the conversion function of reduction process, i.e., reduction fraction of ore to iron powder, was calculated. Also, the activation energy reduction was determined. Characterization results of the initial iron powder produced was also reported.

035 - Pore Elimination from Liquid Metal Droplets for Manufacturing Pore-Free Powders for Additive Manufacturing
Ali Nabaa, University of Wisconsin-Madison

Gas atomization (GA) is a widely adopted method for metal powder production, involving the atomization of molten metal using pressurized gases. Despite its prevalence in additive manufacturing (AM), GA-produced powders often contain pores that can transfer to the as-built parts to deteriorate part quality. Here, we report an approach to achieve pore-free gas-atomized metal powders by inducing a reversed thermal gradient through rapid heating. The resultant thermocapillary force drives the pores out of the molten metal droplets. We demonstrate the feasibility of utilizing rapid heating to eliminate pores from droplets of different metal alloys, using high-fidelity simulation. Furthermore, we derive an analytical model to estimate the critical thermal gradient needed for pore-free powder production.

008 - Reduced Ceramic Inclusions PGA Systems of Aerospace Nickel-Based Alloys
Michael Jacques, Retech Systems LLC

High temperature nickel alloys used in aerospace applications are very sensitive to interstitial, elemental, low density and high density inclusions. One recent know case of ceramic inclusions have had a major impact and cost to engine manufactures to look for alternative methods from the traditional manufacturing of powder production. Retech has developed the Plasma Arc Melting (PAM) gas atomization processes (PGA) to produce ceramic free melting and atomization of nickel powders and substantially reduce these risks. To understand the material quality produced using this technology, we have looked at the feedstock quality from multiple suppliers and then examined these materials when produced through Retech’s PGA equipment located in Buffalo, NY. Again, the focus on testing and reporting of the material “cleanliness” is characterized. This project will increase engine OEM’s knowledge and potential benefits of using the PAM / PGA process to significantly reduce the inclusion risks and ultimately enhance the quality and production capacity of the supply chain for high-purity metal powders.

002 - Going Beyond the Basics in Reducing Costs When Machining PM Components with PCBN Cutting Tools
Brett Young, Shape-Master Tool Co.

Regardless of whether you are new to using PCBN tools for machining powdered metal parts or a seasoned professional, there is always room for improvement relative to reducing total machining costs. Improvement can come in the form of reducing tool cost per unit (CPU) by switching to more cost effect tool geometries or tool types to lower the cost per cutting edge. Tool CPU can also be reduced by utilizing a wider range of PCBN grades to optimize tool performance based on differences in the PM alloy, hardness and machining application process. There are also methods to utilize each cutting edge more extensively to significantly reduce tool cost. Productivity increases can be targeted by increasing the amount of PCBN on the tool to reduce the number of passes required to remove the necessary stock and by using form tools to create part features in shorter machining cycles. Increased feed rates always result in improved productivity and in many cases also increase tool life and should be employed where workpiece surface finish allows.

084 - Enhancing the Machining Consistency of PM Components—A Look at a New Machining Additive
Bruce Lindsley, Hoeganaes Corporation

Powder Metallurgy part machinability is an inherently challenging yet critical process. While net shape in nature, PM parts show significant differences when being machined in comparison to wrought products. Porosity and thermal differences along with non-homogenous microstructures are just some of the reasons why PM machining is often characterized as difficult. Machinability enhancers like MnS have been the backbone of the industry response to these challenges but proves to cause secondary issues when processing; namely enhanced corrosion. As such, in this paper and in response to these issues a new additive with a focus on the drilling operation has been studied.

024 - Machining of Martensitic PM Steels and the Techniques to Improve
Bo Hu, North American Höganäs Co.

Martensitic PM steels are manufactured by either heat-treatment after conventional sintering or sinter-hardening to produce components requiring high mechanical performance such as high hardness and high strength. Despite the near-net shape feature of PM components, machining is often required to achieve desired dimensional tolerances and/or surface finish. Martensitic PM steels are generally difficult to machine due to their high matrix hardness. The high matrix hardness results in low productivity and high tooling costs for any required machining operations. This paper examines the machining of a heat-treated component made with a common prealloyed steel, FL-4405HT, and techniques to improve the machining response. The effect of heat-treating conditions on machinability was also investigated.

102 - Residual Stress Characterization Within Layer Thickness of Ti-6Al-4V Manufactured by Laser Powder Bed Fusion Using Hole-Drilling and Digital Image Correlation
Navid Esfahani, Georgia Institute of Technology

Residual stress is a critical factor influencing the mechanical performance and structural integrity of additively manufactured components. This study investigates the residual stress distribution within the layer thickness of Ti-6Al-4V (Ti64) samples produced by laser powder bed fusion (LPBF). A novel combination of the hole-drilling method and digital image correlation (DIC) is employed for accurate and non-destructive residual stress measurement at microstructural scales. The experimental workflow includes systematic drilling of sub-layer thicknesses and strain mapping through high-resolution DIC to capture stress variations across layers. By correlating these measurements with LPBF processing parameters, the study aims to enhance the understanding of stress formation mechanisms and their influence on material performance. Results provide valuable insights into optimizing LPBF process parameters to mitigate residual stresses, improving the reliability and functionality of Ti64 components for critical applications.

104 - Physical, Mechanical, and Electrical Properties of Copper Fabricated via Sinter-Based Material Extrusion (MEX) 3D Printing
Pavan Ajjarapu, Oak Ridge National Laboratory

This work uses a sintered based material extrusion additive manufacturing (MEX-AM) process to fabricate high-density copper parts via extrusion-based 3D printing technology. In the current work, copper powder-filled polymeric feedstocks and filaments with 58 vol.% and 61 vol.% solids loading were prepared and characterized for physical, thermal, and rheological properties. Subsequently, the filaments were 3D printed into tensile and tablet geometries via a benchtop MX-AM machine. An L9 Taguchi design of experiments was performed by varying print temperature, print speed, and layer height for three levels to identify optimal process conditions to obtain the highest green density and minimum surface roughness perpendicular and parallel to the build direction. Copper green parts were further sintered and characterized to understand the final part's physical, mechanical and electrical properties. Microstructure evolution with varying sintering conditions was also studied to identify its influence on final part properties. This study aims to provide a holistic understanding of the structure-property-processing relationship in copper parts fabricated via sintered based MEX 3D Printing.

103 - Synergistic Effects of Hot Isostatic Pressing and Hirtisation on Additively Manufactured 316L Stainless Steel
Swathi Manchili, Research Institutes of Sweden

Additive manufacturing (AM) offers unparalleled design freedom for complex 316L stainless steel components, but as-built AM parts often suffer from suboptimal surface finish, porosity, residual stresses, and anisotropy, limiting their performance in demanding applications. Post-processing techniques are crucial to overcome these limitations. This study investigates the synergistic effects of combining Hot Isostatic Pressing (HIP) and Hirtisation, a surface modification technique, on the properties of AM 316L stainless steel. HIP enhances density, reduces porosity, and improves mechanical strength, while Hirtisation tailors surface properties like roughness, hardness, and corrosion resistance. This study explores the combined influence of these techniques on microstructure, mechanical properties, and surface characteristics. The findings contribute to optimizing post-processing strategies for powder bed fusion-laser beam manufactured 316L, enabling wider adoption in demanding applications by achieving superior material performance. Further research will investigate the influence of processing parameters on the final material characteristics to refine

082 - Copper and Copper Alloy Powders for Metal Additive Manufacturing
John L. Johnson, FAPMI, Novamet/Ultra Fine Specialty Products

Copper and copper alloy powders are evaluated for their suitability for metal additive manufacturing by binder jetting technology (BJT), material extrusion (MEX), and laser-beam powder bed fusion (PBF-LB). The packing density, flowability, sphericity, internal porosity, and binder absorption time of gas-atomized copper-based powders with different particle sizes are compared. The effects of oxygen and other impurity contents on the sintering behavior and conductivity of pure copper and C18150 are investigated. The effects of powder characteristics on the mechanical properties of PBF-LB C96400 are investigated.

070 - Properties and Applications on Iron Powder Made by Gas Atomization
Kalathur Narasimhan, FAPMI, P2P Technologies

Applications and properties of iron powder made by inert gas atomization are reviewed. Iron powders are used in many different applications such as: soft magnetics; catalysts; water remediation; ink and toner carriers; coatings such as magnetic paints; welding; food grade iron for iron fortification; additives to dyes and stains. The gas atomization of pure iron is sometimes difficult due to the reaction of the iron with the refractories used in the introduction of the molten metal to the atomizing jet. The current process overcomes this limitation and the gas atomized iron powders in this study are reviewed in comparison to electrolytic iron in terms of particle size, shape, grain size and porosity levels. Applications of the iron, particularly, in terms of magnetic properties and use in 3D printing are also reviewed.

061 - Progress in Gas Atomization Reaction Synthesis-Based Consolidation of Oxide Dispersion Strengthened Ferritic Steels: Heat Treatment Effects on Microstructure and Properties
Iver Eric Anderson, FAPMI, Ames National Laboratory

To replace mechanical alloying that expends days of milling and suffers from contamination, and inhomogeneity, oxide dispersion strengthened (ODS) ferritic steels, e.g., “14YWT,” were made with powders from gas atomization reaction synthesis (GARS). These Fe-Cr-Y-W-Ti alloys are atomized with Ar+O2 mixed gas to produce Cr-enriched surface oxide on the resulting powders. TEM analysis of GARS powders revealed that the surface oxide layer characteristics are controlled by oxygen concentration and size-dependent droplet cooling during rapid solidification. Consolidation by vacuum hot pressing (VHP) at different temperatures (750-900C) produced variations in Cr-oxide, intermetallic compound (e.g., Y2Fe17), and oxide dispersoids in the compacts. Recently, VHP and hot cross-rolling at 800C of GARS powders (dia.<20µm) enriched in Y with Zr partially substituted for Ti were characterized as-rolled and heat-treated. Hardness, tensile strength, and microstructure results are reported for 2h heat treatments at elevated temperatures (800-1,200C).

075 - Aspects of Critical Minerals and Sustainability: Overview
Ian Donaldson, FAPMI, GKN Sinter Metals

The automotive industry has been facing disruption as it transforms to clean energy to address the environmental impacts that are leading to global climate change. In the transition to clean energy, critical minerals bring new challenges. For example, a typical electric car requires six times the mineral inputs of a conventional car. Batteries, EV motors and electrical networks associated with clean energy will require an enormous amount of minerals such as nickel, copper and aluminum with copper being a foundation for all technologies related to electricity. This shift to clean energy with the fast-growing demand for these non-renewable minerals makes sustainability efforts more challenging. Sustainability, which can be defined as the ability to meet existing needs without impeding future generations from meeting their needs, has become an emphasis as industries strive to improve the environmental performance of their organizations. This presentation delves into these issues and how they impact the powder metals industry.

046 - Aspects of Critical Minerals and Sustainability: Impact on the Powder Metallurgy Industry
Ian Donaldson, FAPMI, GKN Sinter Metals

The automotive industry has been facing disruption as it transforms to clean energy to address the environmental impacts that are leading to global climate change. In the transition to clean energy, critical minerals bring new challenges. For example, a typical electric car requires six times the mineral inputs of a conventional car. Batteries, EV motors and electrical networks associated with clean energy will require an enormous amount of minerals such as nickel, copper and aluminum with copper being a foundation for all technologies related to electricity. This shift to clean energy with the fast-growing demand for these non-renewable minerals makes sustainability efforts more challenging. Sustainability, which can be defined as the ability to meet existing needs without impeding future generations from meeting their needs, has become an emphasis as industries strive to improve the environmental performance of their organizations. This presentation delves into these issues and how they impact the powder metals industry.