PowderMet AMPM Special Interest
PM-9-1 Novel Processing Technologies
101 - Spherical Ti-6Al-4V Alloy Powder Made by the Direct Reduction and Alloying (DRA) Process
MD Emran Hossain, University of Utah
Spherical Ti-6Al-4V alloy powder is one of the most demanding feed materials for additive manufacturing to produce near-net-shaped products. Atomization is today's most used technique to produce Ti-6Al-4V spherical powder, but high production cost drives the emergence of low-cost processes. Some new methods have been developed to produce spherical Ti-6Al-4V alloy powder; however, no process has been claimed to make it directly from raw oxides. This research demonstrates a novel pathway to make spherical Ti-6Al-4V alloy powder directly from basic oxides by hydrogen-assisted magnesiothermic reduction (HAMR). Raw metal oxides are mixed uniformly and reduced to form fine Ti-6Al-4V alloy powder, which is then granulated-sintered and deoxygenated (GSD) to produce the spherical powder. The process is called the direct reduction and alloying (DRA) process. Spherical Ti-6Al-4V alloy powders produced by this process have low interstitial impurities, controlled particle size distribution, uniform and homogeneous composition, and excellent flowability.
160 - Oxygen Concentration Tailoring for 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 necessary “mechano-chemical” mixing, 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 and understand the solidification rates, electromagnetic levitation (EML) experimentation is being developed to examine the effects of gas mixtures on a “macro-sized” droplet to characterize and predict 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.
086 - Accelerating TTM of High-Performance Metal Parts: From Prototyping to Manufacturing on One AM Platform
Dror Danai, XJET 3D
When it comes to producing high-performance metal parts of relatively small dimensions, manufacturers today can choose among various traditional and additive manufacturing (AM) technologies. While traditional technologies (e.g., CNC machining, metal injection molding (MIM), and investment casting) provide high quality and competitive costs in large runs, they typically require costly and lengthy product development processes. While varying metal AM technologies (e.g., metal binder jetting (MBJ) and direct metal laser sintering (DMLS)) each has their advantages/disadvantages, most [or: they] involve powder-based processes that raise safety and other operational challenges. One relatively new metal manufacturing technology – metal material jetting – today delivers an automated production process that enables cost-effective prototyping and manufacturing using the same metal AM system. As a result, the time to market (TTM) of performance parts can be accelerated rapidly. In this presentation, representatives of XJet and Azoth, a metal service bureau, will highlight the experience of a [or: the] metal service provider in using XJet’s AM system (and underlying material jetting technology) from prototyping to production.
PM-9-2 PM Product Applications II
185 - Process Experience with High Permeability Soft Magnetic Composites
Neal Kraus, Hoeganaes Corporation
Soft magnetic composites (SMCs) materials provide a significant opportunity for the PM industry in electric motor applications. Newer grades with higher permeability have been introduced to the market and proper processing is critical to maximize performance. A batch furnace capable of different thermal profiles and atmospheres including steam has been used to explore different parameter sets to shed light on critical curing variables. Examples of proper and problematic curing will be shared along with magnetic property impacts.
010 - NdFeB Magnets in Traction Motors
Kalathur Narasimhan, FAPMI, P2P Technologies
The demand for Neo magnets in traction motors and Windmills spurred a great interest in domestic production. National security issues are a factor as well. China with vast amount of rare earth ores has been a dominant player for the past two decades that resulted in the rest of the world to shut down their magnet plants. There is an attempt to restart production of rare earths in Mountain Pass, California which opens a opportunity for parts makers to get in to making magnets.
Several methods are used to reduce cost of raw materials cost in magnets in the traction motors .Grain boundary engineering offers excellent promise also Light rare earths like Ce, La are more abundant. However saturation induction is lower in Ce and La but high enough, so substitutions are possible. Pr and Nd occur together and often called as didymium and can be used as lower cost substitute. Efforts to replace Nd with these substitutes have been in progress for some time. This presentation will cover the progress made thus far.
047 - History of the Gerotor Design and Manufacturing
Glenn Mann, Nichols Portland LLC
History of the gerotor design and manufacturing from the W. H. Nichols aspect, with its beginnings starting in the 1920’s. The “generated rotor” know as the gerotor design which recognized as one of the most popular power elements for hydraulic pumps and motors. Starting from Myron Hill’s “Book of Kinematics of Gerotors” and working with Harte Nichols to develop a special profile grinder for the inner rotor gerotor set in the 1920’s cutting chips from billet for low volume to the high-volume powder metal manufacturing. The gerotor provides an excellent combination of compact size and low manufacturing cost compared to other gear designs (spur, crescent, etc.). This paper is written to provide an overview of the gerotor design and its impact to the industrial and automotive sectors.
AM-9-1 Laser Powder Bed Fusion of Stainless Steels
037 - Consequences of Powder Reuse on Microstructure Evolution during Laser Powder Bed Fusion of 316L Stainless Steel
Madelyn Madrigal Camacho, Colorado School of Mines
Successive reuse processes lead to changes in powder morphology, chemical composition, and microstructure in the recovered powder. In the case of 316L stainless steel, literature reports successful powder reuse within 12-30 consecutive cycles, however, a detailed understanding of the effect of powder degradation on the final part quality is unexplored. Therefore, the primary goal of this study is to enable the rapid degradation of the powder feedstock under conditions which can be transferable to manufacturing processes. With this approach, the effects of the thermally dynamic powder-laser interactions and the instrument process parameters on reused powder characteristics can be explored. The results provide insight to the consequences of the melt pool behavior with the instabilities of the altered powder, solidification modes, microstructure, evolution of spatter and porosity in the as-built components. These observations point to important considerations to design a standard method for reusing powder in powder bed fusion processes.
003 - Microstructural Control of a Multi-Phase PH Steel Printed with Laser Powder Bed Fusion
Brandon Fields, University of California, Irvine
The microstructure and properties have been observed to vary substantially in different locations of laser powder bed fusion parts. This variation is due to local changes in cooling rates and thermal gradient direction when varying the part geometry. Understanding and controlling this phenomenon is crucial towards optimizing the properties of a printed part. This microstructural control can be utilized when applied to a material which has differing phases with distinct advantageous properties (such as strong & brittle versus weak & ductile), that can be tuned locally to optimize the overall part. We demonstrate this understanding and control in a dual phase 17-4 precipitation hardened steel, quantify the differences in mechanical properties between the microstructures, and determine the ability and scale of microstructural control. Control of local and bulk properties by tuning the microstructure are observed.
054 - 3D Multi-Material Laser Powder Bed Fusion of 420 Stainless Steel-Cu Parts for Plastic Injection Mold Inserts
Ângela Cunha, University of Minho
Plastic injection molding is one of the fastest-growing industries in the world. However, although it presents numerous advantages, the costs associated with the mold and machine are high and, therefore, this process is only profitable for mass production. Moreover, the reduction in the cycle time, more specifically the cooling time, has been a never-ending challenge since it has a direct influence on the production costs. In this sense, this study is focused on the production of 420 stainless steel-copper solutions by 3D multi-material laser powder bed fusion. This novel material’s design concept allows combining the high mechanical resistance of the steel alloy and high thermal conductivity of the copper. The processing parameters and strategies, and the transition between dissimilar materials are one of the most challenging and important aspects both from mechanical and metallurgical point of view. The obtained results show that this approach is effective to produce inserts in 420 stainless steel-copper capable of improve in-service conditions of a plastic injection mold, enhancing mold performance and life.
AM-9-2 AM of Copper Components
133 - Physical, Mechanical, and Electrical Properties of Copper Fabricated via Sinter-Based Material Extrusion (MEX) 3D Printing
Kameswara Ajjarapu, University of Lousiville
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.
026 - Development of C18150 as a Structural Copper Alloy for Binder Jet Manufacturing
Kyle Myers, ExOne
C18150 is a copper alloy containing chromium and zirconium as the primary alloying elements. The alloy can be heat treated by a precipitation hardening mechanism, which also increases the conductivity of the material compared to the solutionized condition. The alloy’s combination of strength, hardness, and conductivity make it an attractive selection in thermal transfer applications where the stresses may be too high for unalloyed copper. This work examines the results of binder jet printing three different C18150 powders. The powders were characterized to understand their particle size distribution, morphology, and rheological characteristics. Debind and sintering profiles were optimized for each powder to achieve high sintered density. Sintered parts printed from each powder were subsequently subjected to heat treatment and were characterized with respect to residual interstitials, microstructure, conductivity, and mechanical properties.
182 - Electrical Properties of AM Copper
Nicholas Murphy, Kymera International
Investment in additive manufacturing (AM) has led to great interest in copper powder as a material that could be used for 3D printing. Previous research has shown that both traditional press-and-sinter copper powder parts and additively manufactured copper parts can achieve excellent electrical conductivity, among other properties. In this paper, we explore more fully the electrical properties of copper AM parts as compared to press-and-sinter copper parts.
197 - Opening the Door to PM
Robert Swenson, TriTech Titanium Parts
The binderjet printing process is gaining interest for many PM applications. There is not any startup cost to look at a new part. Parts can be designed and printed to fit any application. The binderjet process can produce very complex shapes like lattice structures and internal passageways. In these cases the binderjet process will be the best and lowest cost method of production, as unique products are being produced that cannot be otherwise achieved (except for PBF which is more expensive). Another path is to use the binderjet process to prototype parts that can eventually become high volume. When volumes get great enough there is a cost advantage to switch to metal injection molding. The economic factors include part cost for each technology, tooling cost for metal injection molding, and the transition point for switching from printing to molding. Often the base case for the part is to be machined, and maybe from a different material like stainless steel or aluminum. The presentation will look at two examples of development and the benefits of each technology.
081 - Utilisation of Wide Particle Size Distributions of Plasma Atomized Ti-6AL-4V Powders for Laser Powder Bed Fusion: Effect of Powder Properties on the Tensile Properties and Surface Roughness of Produced Parts
Mahdi HabibnejadKorayem, GE Additive
Laser powder bed fusion (LPBF)is an additive manufacturing process that utilizes a laser to fuse powders in a bed and typically utilizes fine powders with a narrow particle size distribution. Powder properties such as morphology, mean size and particle size distribution affect the flow properties of the powder, which in turn have strong effects on the performance of the final part. Previous work surrounding metal powders used in additive manufacturing focuses on the relationships between powder particle size distribution and flow properties. However, relationships between powder particle size distribution (PSD) and mean size to mechanical properties such as yield strength, tensile strength, dimensional accuracy, and surface roughness have not been explored. This work measured the flow properties of Ti-6Al-4V powders with varying size distributions and compared them to their mechanical performance and surface characteristics of LPBF printed test coupons. Despite differences in powder size distribution, mean size and flowability, the mechanical properties of each test coupon are comparable. The fracture surface and microstructure of each produced sample was nearly identical regardless of PSD. Results are promising in that they demonstrate that wider PSD powders can generate coupons with comparable yield strength, tensile strength, hardness, and dimensional accuracy to the benchmark powder. The main downside of utilizing wider PSDs is that the surface roughness of the samples increases, though this increase is marginal when comparing to other manufacturing methods.
077 - Investigation on the Influence of Powder Oxygen Homogeneity on the Processability and Properties of the L-PBF Processed Ti-6Al-4V
Javier Arreguin, AP&C, a GE Additive Company
Current powder specifications for additive manufacturing assume homogenous chemical composition of powder feedstock to ensure the final properties of printed components. In the case of Ti-6Al-4V composition, one of the main elements influencing the final properties of printed components, and that is evolving as powder is recycled, is the oxygen content, which can be distributed at either the interstitial free positions or surface. Such variations allow the differentiations between grade 23 and 5. In general, the main criterion to select among the above material grades is the fact that higher oxygen content of the grade 5 enhance the strength and the lower oxygen content of the grade 23 results in superior ductility. The mixture of the above grades to control the average chemical composition could minimize the disposal of powder after recycling thus maximizing the usage of the powder and lowering the overall cost. Some may expect that such mixtures could bring inconsistency and heterogeneity in the localized oxygen distribution and thus the mechanical properties. This paper is to present the experimental data to clarify the uncertainties introduced to the L-PBF processability by comparing an uniform chemical composition with a mixed one, both meeting the grade 23 nominal chemical composition, and comment on the final mechanical and physical properties of L-PBF printed components particularly the resulted microstructure and fatigue properties.
AM-9-4 Powder Quality and Testing
097 - Assessing the Reusability of a High-Strength Aluminum Alloy Feedstock in Laser Powder Bed Fusion
José Muñiz, Equispheres Inc.
In metal powder bed fusion the reusability (and stability) of the feedstock has significant impact on process cost and print consistency. Any variation in powder properties over the multiple build cycles can impact the stability of the process and perhaps necessitate changes to the build parameters, an undesired outcome. Aluminum powders have a reputation for variability that can result in a lack of process reliability, and lack of stability over time. This degradation is affected by overall feedstock quality but also by the impact of the process itself. In this study the long-term stability of different particle size distributions is assessed with the aim of assembling a statistically significant dataset. The powder feedstocks are the same composition and similar overall quality, but differ in terms of specific surface area. This allows us to isolate the influence of particle size distribution on the long-term powder stability and performance in-process.
130 - Detecting Particulate Contaminants in Metal Powders Using X-Ray Fluorescence
Timothy Glose, Malvern Panalytical
Contamination of metal powders used for additive manufacturing provide a real risk to product quality and safety. That’s because the presence of contaminant particles with different melting characteristics or mechanical properties than the bulk powder can lead to localized stress points in the printed part. This could lead to premature or catastrophic failure and is especially important in risk adverse sectors such as aerospace, medical, and oil and gas. Contamination can originate at various stages in the value chain, including powder production, powder handling, and powder recycling at the AM facility. Identifying contamination can be difficult though as you are often dealing with ppm levels of contamination, and in the case of cross-contamination with other AM powders they can look visibly similar. In this talk we show the potential of X-ray fluorescence as a tool for identifying inorganic and metallic contaminants in metal powders down to ppm level with specific emphasis on Tungsten contamination in Titanium alloy.
194 - Automated, Reliable, and Comprehensive Universal Powder Testing to Improve Processing Efficiency and Aid Quality Control
Nicholas Monroe, Micromeritics Instrument Corporation
Additive manufacturing (AM) is a highly efficient manufacturing technique involving ‘printing’ intricate components to a tight specification by gradually building up powder layers which are then selectively fused together. Controlling the performance of the powders is critical for process efficiency and end-product quality. Variability in feedstock can lead to quality issues such as non-uniform layering, low tensile strength, and poor surface finish. Powder characterization has a vital role to play in supporting this process, as testing techniques that can reliably measure properties that correlate directly with AM performance are essential. Identifying which powder properties lead to uniform, repeatable performance of powder allows new formulations to be optimized and helps reduce the occurrence of final products that are out of specification. Existing techniques such as Angle of Repose testing, Flow through a Funnel, and Bulk Density measurements are often too insensitive to accurately quantify subtle differences between powders with different processing performance. During this presentation, the audience will be shown a universal powder tester that provides automated, reliable, and comprehensive measurements of powder flow characteristics. This information can be correlated with process experience to improve processing efficiency and aid quality control.
Special Interest Program Abstracts