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Monday Sessions
2:45 p.m. - 4:00 p.m.

 

PowderMet          AMPM          Special Interest

PowderMet Abstracts

 

PM-2-1   Compaction and Forming I

049 - Filling Density and Geometrical Precision of Ring-Shaped Parts - Effect of the Filling Strategy
Alberto Molinari, University of Trento

The influence of sintering on dimensional and geometrical precision has been widely investigated in previous works, both on ring-shaped parts and on industrial products. Results clearly correlated the dimensional precision to the anisotropic dimensional change on sintering. Geometrical precision is also affected by sintering process, but markedly depends on the result of compaction process. The origin of geometric errors has been generally attributed to inhomogeneous filling density distribution, but it has never been analyzed systematically.  In this study, a commercial Fe-Mo powder mix was used for compacting ring-shaped samples at different height to thickness ratios (H/T). Focusing on the filling strategy, different values for filling shoe speed, suction speed, and number of shakes of the filling shoe were considered. The influence of both geometry and filling strategy on filling density has been derived, and the results have been related to the geometric errors at the green and sintered state. 

227 - Influence of Surface Modification of Powdered Metals on Fabrication of Electrical Laminate Contacts
Nathan Scott Banner, Penn State University DuBois

Previous testing was completed on copper silver graphite electrical laminates. Prior to adding a silver coated copper interlayer; silver diffused into copper faster than graphite, which caused graphite accumulation at the interface creating weak bonding to occur. Upon the addition of a silver coated copper interlayer, counter diffusion occurs between the silver graphite and the silver coated copper interlayer which eliminates graphite accumulation at the interface. Using the scanning electron microscope, it was shown a very small amount of graphite diffused into the interface. Building upon our previous results, we would like to extend the use of this laminate method to other PM materials that are used for electrical contacts namely copper-tungsten and silver-tungsten systems. Laminates using the modified copper powders will be fabricated and the impact of surface modification on mechanical, electrical and wear resistant properties will be assessed. Interlaminar shear strength and electrical performance will be analyzed.

097 - Development of Air-Induced Defects within Powder Compaction
Joseph Wright, FAPMI, Drexel University

Defects can occur in a variety of forms during powder compaction. Failure of the particles to form bonds can develop cracks throughout the bulk. Entrapped air in the form of a bubble is one form of defect. Through the use of finite element analysis, the entrapped air can be implemented in a number of approaches to achieve a final compact that closely approximates real-world production. Though literature suggests a higher air pressure at the center of the tablet, our results show that bubbles more often form near to the surface, indicating an additional factor influencing their development. Although the primary focus of our work is in pharmaceutical materials due to the high production throughput, the findings can be applied to traditional powder metallurgy processes such as die compaction and powder rolling.


PM-2-2   Ferrous Powder Premixing Technology

112 - Enhanced Properties of Iron-Based PM Parts via High-Speed Mixing of Powders
Devin Carns, Penn State University DuBois

The effects of high-speed mixing of iron powders compared to traditional tumbler mixed powders was done to show improvements with the flow properties, mechanical properties (TRS and microhardness) of sintered parts, and other characteristics such as apparent density and porosity. High-speed mixing has shown improvements in almost all characteristics of F-008, FC-0208, and FD-0205 suggesting that using a high-speed mix increases the quality of a product compared to that of a tumbler mixed product. High speed mixing was done at 19,000 rpm for 30 seconds. The powders were compacted to two densities, 6.3 g/cm3 and 6.8 g/cm3 and sintered at 2075 °F in a 90%N2 + 10%H2 atmosphere. Results show that parts made from high-speed mixed powders exhibit higher microhardness and TRS strength compared to parts made from conventional mixed powders. This is attributed to ‘geometrical hardening’ due to particle fragmentation and local deformation at contact areas between particles. This ultimately improves diffusion during sintering. The results of this study suggest that high-speed mixing of powders can be used to improve the properties of typical powder metallurgy parts.

116 - Effects of High-Speed Mixing on the Properties of Sintered F-0008 and FN-0208 PM Parts
Cole Bressler, Penn State University DuBois

Two variants of iron-based powders, F-0008 and FN-0208 were used to study the effects of high-speed mixing on the physical and mechanical properties of sintered parts. The results were compared to traditional tumbler-mixed powders. The high-speed mixed powders showed reduction in the particle sizes and improvements in properties such as flow rate, apparent density, porosity, and TRS strength. The parts were compacted to two densities, 6.3 g/cm3 and 6.8 g/cm3 and sintered at 2075 °F in a 90%N2 + 10%H2 atmosphere, to allow comparison of the two variants at low and medium densities. Interestingly, high-speed mixed FN-0208 showed appreciable increase in the microhardness and TRS strength compared to conventional mixed parts. On the other hand, high-speed and conventional mixed F-0008 parts had fairly comparable properties. This suggests that the increase in the strength of high-speed mixed FN-0208 is due to co-deformation between nickel and iron powders during high-speed mixing. This results to particle fragmentation and local deformation which enhances diffusion and improves mechanical properties.

075 - The Master Alloy Concept- Flexible Precision of PM Steel
Stefan Geroldinger, Technische Universität Wien

The challenges of the future necessitate development of new materials with properties that are precisely tailored to their requirements. Alloying elements are expensive, so they should be used as efficiently as possible. Others, as Ni, should be avoided due to safety reasons. The new UHWPA atomizing technique allow the production of fine master alloy powders with low oxygen content at low cost.  In the present study, properties of PM steel grades alloyed with Cr, Si, C and / or Mn containing master alloys are compared with conventional PM steels regarding dimensional stability, hardness, hardenability, impact energy, Young’s modulus, flexural strength and microstructure.


PM-2-3   Management Issues

001 - Update on the World Market for Metal Powders & Steels
Benedikt Blitz, SMR Premium GmbH

The speech will focus on the production of Metal Powders and Powder Metallurgy Steels and especially its associated production technologies like HIP, MIM and AM. As they are and will become key future core technologies for a number of demanding products and thus for the usage in different associated industries. The presentation will also highlight the actual supply and demand situation of metal powders and the manufactured powder metallurgy steels, will introduce leading manufacturers of both powders and steels, and summarizes installed capacity and new capacity that are on the way as well as new players that enter this high value industry. The presentation will also highlight the recent developments in the world of Forged Special Steels and remelted steels (nickel alloys, stainless steel, alloy tool steel and alloy steel) as well as will give an overview about end-user demand and structures of these special steels and also summarize the actual status of installations on a global scale.

162 - Rational Choice and Organizational Theory Applied to MIM Cost Estimations
Matthew Bulger, ATPM Consulting

A review of Metal Injection Molding costing techniques, common estimation mistakes and oversights when costing MIM components

163 - Comparison of Binder-Jet and MIM
Animesh Bose, FAPMI, Desktop Metal

Binder-jet is currently established as the additive manufacturing (AM) process suitable for the mass production of complex shaped metal components without the use of any tooling.  The process has a number of similarities to the relatively mature process of Metal Injection Molding (MIM) along with some major differences.  This presentation will compare and contrast the two processes and also discuss the advantages and limitations.

 

AMPM Abstracts

 

AM-2-1   Binder Jet Materials II: Iron Based

111 - Binder Jet Additive Manufacturing of Nickel-Free Stainless Steel for Wearables
Austin Ward, The ExOne Company

Nickel-free stainless steels are attractive materials for wearable products because they are corrosion resistant, durable, and they don’t expose the wearer to nickel, which causes allergic reactions in ~18% of the population. Nickel-free stainless steels are often fabricated in net shapes using metal injection molding; however, this process relies on costly tooling, motivating the exploration of additive manufacturing as means to densify the powder. In this work, we first identify the optimal process parameters for binder jet additive manufacturing of austenitic, nickel-free stainless steel. Next, we investigate sintering, HIPing, and subsequent heat treatments to densify the green bodies while simultaneously controlling the nitrogen content to ensure that austenite remains stabilized. Ultimately, we demonstrate that binder jet printing is a viable process for creating fully dense, net-shaped components from nickel-free stainless steels by building functional wearables. 

069 - Heat Treatment Optimization and Resulting Properties of Metal Binder Jetted AISI 4140
Mats Persson, Digital Metal AB

Metal binder jetting is taking large strives toward industrialization and structural steel components in industries e.g. automotive is a growth area. DfAM enables novel and optimized part solutions. Inherent advantages in design freedom and short lead time to functional prototypes and production parts need to be matched by mechanical properties in line with conventionally processed material. 

AISI 4140 is a low alloyed steel with good through hardenability which is typically deployed in quenched and tempered state. In this paper process parameters of metal binder jetting are outlined along with as sintered physical properties. Post processing including normalizing and quench and tempering have been investigated and resulting mechanical properties are reported along with generated dynamic behaviour.  

MBJ being a sintered based technology with many similarities to MIM, thus properties in line with related standards are expected. Results are compared with normative and typical expected performance from standards. 

114 - Microstructure and Mechanical Properties of FSLA Steel Produced By The Binder Jet Process
Thomas Murphy, FAPMI, Hoeganaes Corporation

An alloy, called FSLA (free-sintering low-alloy), was designed and implemented for use with binder jet printing.  This work focuses on various heat treatments that can be utilized with the alloy to produce a range of properties for various applications. . The microstructure of the alloy can be varied post-sintering, by heat treatment, to give a wide range of mechanical properties that are suitable for automotive components. The alloy constituents are formulated, so that upon cooling from the sintering temperature, the transformation products allow the alloy to reach the required mechanical properties. The hardenability of the alloy is such that ultimate tensile strengths in excess of 1000 MPa can be obtained by inter-critically annealing the material and air cooling.  Various heat treatments and their corresponding mechanical properties will be reviewed.


AM-2-2   Metal AM Processes II

226 - Additive Manufacturing of Aluminum Alloy by Metal Fused Filament Fabrication (MF3)
Luke Malone, University of Louisville

This research studies metal-fused filament fabrication (MF3) for manufacturing aluminum alloy parts. An aluminum alloy powder-based feedstock with a polymer-binder system will be extruded via capillary rheometry to form a filament. The filament will be used to print green parts that are involved in a two-step debinding process combining solvent and thermal extraction of the polymer binder, then sintered in a partial vacuum. Resulting grain structure, sintered density, and mechanical properties will be characterized and compared to metal injection molded (MIM) specimens. The main objective is to gain an understanding of the MF3 process characteristics and the ensuing material properties and microstructure through carefully designed experiments and computer simulations, therefore creating additive manufactured components from a common lightweight metal. The overarching goal is to enable rapid, predictable, reproducible, low cost, and accurate production of metal parts with 3D features, thereby significantly expanding the current additive manufacturing capability.

085 -How Maturation of Computer and Laser Technologies Enabled the Development of Laser Powder Bed Fusion
James Sears, Amaero Additive Manufacturing

Laser Powder Bed Fusion (LPBF) is a result of significant advances in Computer and Laser Technologies over the last 60 years. The rise of computer technology from the large computing systems (taking up rooms) of the 50’s to the hand-held systems of today has been remarkable. Lasers where also invented during the same time frame and have had similar size reductions. Early lasers where electrically inefficient <3% and required significant cooling where today most lasers (less than 400 watts) can be air cooled and have plug wall efficiencies approaching 50%. A short history of lasers will be provided. A critical review of the LPBF technology will be provided with an analysis of its current limitations and issues that need to be addressed. The significant events that made Additive Manufacturing possible, including Laser Powder Bed Fusion (LPBF), will be reviewed.

007 - Understanding Processing Parameters Strategy to Simulate the Thermal Models of Electron Beam Melting
Emrecan Soylemez, Istanbul Technical University

Electron Beam Melting (EBM) is one of the challenging additive manufacturing processes for thermal modelling due to varying unknown process parameters. Understanding how the primary process parameters, such as scan speed and scan power, are controlled by beam control functions during manufacturing is essential for accurate thermal modelling of the process. In this study, we investigate the four control functions, namely current compensation function, speed function, thickness function, and turning point function. To evaluate the performance of these functions, several multi-layer experiments including different speed function values, scan vector lengths, thicknesses, etc., were designed to determine scan speed and scan power during the process. Additionally, single bead experiments were performed to obtain melt pool geometry data. Finally, it is demonstrated how the process variables affect the building strategy. These results will help to build up part-scale thermal models to accurately simulate the temperature distribution on the parts.


AM-2-3   Titanium

218 - Effect of Post-Processing on the Microstructure and Mechanical Performance of Laser Powder Bed Fusion Hydride-Dehydride Ti-6Al-4V Alloy
Mohammadreza Asherloo, Illinois Institute of Technology

Hydride-dehydride Ti-6Al-4V with non-spherical morphology and size of 50-120 μm is laser powder bed fusion (LPBF) processed to 99.8% density; remnant pores are eliminated by hot isostatic pressing (HIP). Process optimization was conducted on power-velocity-hatch spacing parameters with an increased build rate ratio of two. Microstructural observations indicate formation of columnar β grains with acicular α/α′ phases in as-built condition, while the HIPed specimens show partial decomposition of α′ to α+β inside the prior β grains. The as-built condition showed hardness 370 HV0.3, yield strength (YS) 1220 MPa, and ultimate tensile strength (UTS) 1310 MPa; after HIP treatment, the values were hardness 337 HV0.3, YS 1070 MPa, and UTS 1125 MPa. The average roughness of the as-built/HIPed samples was Ra=25.9 μm, but this decreased to Ra=1.7 μm after mechanical grinding. Fatigue testing under with R=-1 showed that the HIPed-ground condition increased the life by 10 times over the as-built condition.

169 - Current Research in Binder Jet Printing of Titanium Powders
Nathan Jump, University of Utah

Binder Jet (BJT)printing has recently emerged as a feasible manufacturing method for small to large scale parts, but at the current moment, the full capabilities of this technology are restricted by the materials available. Titanium is one of the most desirable materials used in manufacturing due to its low density, high strength, high elongation %, and corrosion resistance, yet at this time the material cannot successfully be utilized within the BJ system. This discontinuity exists due to titanium having a high affinity for both carbon and oxygen impurities. These impurities, which are abundant within the polymeric binders utilized in the BJT system, can significantly reduce the highly desired mechanical properties of titanium. Current research is being conducted to produce Ti64 parts on the BJ system, with relatively low carbon and oxygen contents. The oxygen and carbon pickups from each step are investigated.

117 - High Temperature Mechanical Properties of Gamma-TiAl Fabricated via Electron Beam Melting Additive Manufacturing
Patxi Fernandez-Zelaia, Oak Ridge National Laboratory

Titanium aluminides offer excellent high temperature specific strength however have been traditionally challenging to manufacturing. Recent advances in additive manufacturing (AM) have enabled successful processing of this material system via electron beam melting (EBM). However, limited work is available in the existing literature focusing on high temperature creep behavior of additively manufacturing TiAl. In this work we present recent results on the time-dependent behavior of EBM AM TiAl in both the as-fabricated and heat treated states. The structure-property relationships are discussed as well as implications of the results on applications for elevated temperature service conditions.

Special Interest Program Abstracts

 

SIP-2-1   Vehicle Electrification: Material Properties

513 - A Comparison of Soft Magnetic Composites to Laminated Steel
Phillip McDonald, Horizon Technology

In an effort to understand the potential benefits and market opportunities for soft magnetic composites (SMCs), a study was under taken that compared commercially available SMC materials with lamination steel assemblies. In this study, the lamination assemblies were prepared via the three most common methods: welding, stacking and gluing of the individual lamination sheets. The comparative SMC samples were compacted, de-lubed and then given a final cure as per recommended procedures. Testing was done on an automated magnetic Hysteresis graph under both DC and AC conditions. Key characteristics measured were DC permeability, core loss at various induction levels and different frequencies. The results showed that the relative performance of SMC components to their laminated counterparts is dependent upon the geometry and fabrication methods for the lamination assembly. This presentation will highlight the relative performance and potential opportunities for SMC materials.

507 - Iron-Based Powder Solutions for Soft Magnetic Composite Applications
Bruce Lindsley, Hoeganaes Corporation

 

508 - Designing SMC Components with Mechanical Strength in Mind
Fabrice Bernier, National Research Council Canada

 

 

 

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