Monday
Keynote Presentation: A Holistic Approach to Low-Cost Titanium
Z.Z. Fang, University of Utah
USA
The high cost of titanium has challenged the Ti industry and is a major focus of the research community globally for several decades. Although the powder metallurgy (PM) of Ti has shown promise to be a low-cost approach, it has not gained significant market acceptance because the performance-to-cost ratios of PM Ti cannot compete with that of the wrought alloys. In order to compete, the cost of Ti and Ti alloy powders must be drastically reduced and the mechanical properties of sintering Ti alloys must be drastically improved. This presentation introduces both a low-cost powder production process and a sintering technology that can produce Ti-6Al-4V with wrought-like microstructure and mechanical properties. The strong affinity of titanium to oxygen makes the conventional Ti metal production by either the Kroll or the Hunter process energy-intensive and costly. A new approach is designed to prepare high-purity Ti metal powder from commercial purified TiO2. Pure TiO2 is subjected to Mg reduction, followed by a de-oxygenation process using Mg. Both the Mg reduction and the deoxygenation processes are carried out in a hydrogen atmosphere. It has been shown that hydrogen can destabilize the Ti-O system and enable Mg to reduce the oxygen content in Ti to very low levels. This is a fundamental breakthrough that makes the direction production of Ti metal and alloy from TiO2 by magnesium reduction possible. This talk will present an elaborate design of the hydrogen assisted Mg reduction process (HAMR) and the results that demonstrate the HAMR process can produce low oxygen Ti metal powder with oxygen content as low as a few hundred ppm. HAMR process can be used to produce both low oxygen CP-Ti and Ti alloy powders.
The second part of this presentation introduces a new approach for sintering Ti alloy powders. A hydrogen sintering and phase transformation process are designed to produce Ti-6Al-4V alloy with wrought-like microstructure and mechanical properties via simple press-&-sintering and heat treatment. Titanium powder is typically sintered in a high vacuum to achieve high density and low oxygen. Sintered materials usually have coarse grain size and lamellar structure in the case of sintered Ti-6Al-4V alloys. In this work, a novel process is designed to take advantage of both the higher sintered density for using TiH2 as raw material and the phase transformation induced by hydrogen that produces fine grain sizes. The process can produce near-fully dense (>99%Ti-6Al-4V) Ti materials with very fine grain size (~<1.0µm) in an as-sintered state. The refined microstructure has advantages over the coarse lamellar structure of conventional sintered Ti materials from the standpoint of mechanical properties. The as-sintered Ti-6Al-4V can also be heat treated to obtain wrought-like equi-axial globular or bi-modal microstructure and mechanical properties. This presents a new opportunity for low-cost manufacturing of PM Ti materials with both static and fatigue mechanical properties equivalent to that of wrought Ti materials. This presentation will show the results of microstructure and mechanical properties of as-sintered, heat-treated, and those with an additional pore closing treatment. The results demonstrate that PM Ti-6Al-4V can be made to have equivalent mechanical properties, including fatigue strength, to that of wrought Ti.
Keynote Presentation: Where did AM Come from and Why is It Such a Good Fit for PM Titanium?
J. Sears, AMAERO Additive Manufacturing
USA
Over the last 50 years there have been many developments in the techniques used to fabricate components using Titanium Alloy powders. The reasons for using PM Ti for part fabrication has been well established, i.e., the associated reduction in fabrication costs. A major impediment to a wider acceptance for the use of PM Ti has been the high cost of powder. Now, with the recent focus on Additive Manufacturing, the interest in using PM Ti has increased and more producers are becoming online. A brief history of where Additive Manufacturing came from will be presented along with past and present developments of titanium powder production.
Keynote Presentation: Titanium a Bow on Powder to Production: Ti 6Al 4V Case Studies
A. Andreaco, GE Additive
Canada
Additive manufacturing (AM) is incredibly desirable for not only low volume, high mix applications to support customers like the Department of Defense (DoD), but also for serialized production in highly regulated fields such as aerospace and medical devices. Across these scenarios, Ti 6Al 4V is one of the most common alloys requested to support such applications. GE Additive has active partnerships across both electron beam powder bed fusion (EB-PBF) and laser powder bed fusion (L-PBF) modalities working to characterize Ti 6Al 4V for producing qualified hardware. This talk will summarize approaches that can enable rapid qualification, including consideration of aspects such as material characterization and powder reuse.
Evaluation of Nitinol Produced via Multiple PM Forming Routes
P. Sheffield, Praxis Technology
USA
The processing of Nitinol for study of its shape memory properties has been studied and reported in detail. Some processing routes such as Additive Manufacturing & Metal Injection Molding are difficult to produce consistent shape memory properties due to the sensitivity of material composition and typical thin-section, wire geometries of components. However, AM & MIM processing are potential routes to produce components that take advantage of the super elastic properties of Nitinol. This paper reviews the physical and mechanical properties focused on super elasticity of Nitinol produced via DLMS & Binder Jet Additive Manufacturing, as well as through Metal Injection Molding. The paper will examine the composition, density, modulus, microstructure, and tensile properties of the produced specimens.
Scaling Sinter Based 3D Printing Technologies for Titanium and Its Alloys
M. Scharvogel, Element22 GmbH
Germany
The relatively new sinter-based (sb) 3DP technologies can allow manufacturing precision Titanium components with excellent material properties and good surface finish in an economic fashion, when following certain rules. The manufacturing technologies are interesting for prototypes through production quantities and used in many different industry segments. Certain sb3DP technologies are tailored towards small integrate parts, while other allow manufacturing large parts in economic fashion. There are technologies that allow printing components with different materials or varying properties by other means. In traditional Metal Injection Molding the shape of the components is defined by the molding tool. In 3D Printing, some techniques use a similar approach where the shape is defined by some kind of secondary mold that is often created be printing, while some techniques created the desired shape without a mold. But, there are also several in between technologies that allow 3D Printing of different types of molding tools.
Another large difference between the technologies currently available, is that some use lose powder while others have the powder bound with binders, so there is no lose powder with the related potential hazard.
The key to success is to understand what technologies exist, to understand the advantages and challenges are related to them and being to apply them. In some application it might be even best to combine different methods.
These new sinter based 3DP technologies allow true innovation and creating geometries, structures and applications that have not been possible before. A general overview will describe compare the different technologies with its advantages and challenges.
Titanium Powder Production from HDH Reprocessing of Titanium Scrap
B. Pratt, Powdermet Inc.
USA
Typical titanium components utilize only 30% of the initial ingot in the final part while the other 70% ends as titanium scrap that must be recycled. To understand the magnitude of the produced waste: the major aerospace companies in the U.S. each produce 5-10 million kilograms of titanium scrap every year. To reduce titanium waste, required embodied energy, carbon dioxide emissions, and cost, Powdermet Inc has successfully developed their Hydride-Dehydride (HDH) process to recycle scrap titanium for secondary use. The HDH process produces ultra-low oxygen, small (diameter of particles) powder for titanium wire production and near-net shape component production as well as MMC’s with enhanced and tailored properties along with the ability to modify, adjust, and correct alloy chemistry. Our process maintains Titanium grade 4 and below, and through our powder metallurgy processing maintain >90% of ASM reported properties. Additionally, the enhanced HDH titanium reprocessing enables the use of these reclaimed titanium powders in new markets with revised formulations tailored to desired properties.
HDH Ti-6Al-4V Alloy for Laser Powder Bed Fusion
M. Paliwal, Kymera International
USA
Ti-6Al-4V is one of the most commonly used titanium alloys due to its excellent mechanical properties and its corrosion resistance. This makes it a great candidate for Aerospace and biomedical applications. In Laser Powder Bed Fusion (LPBF) Ti64 is most commonly utilized in its Gas Atomized (GA) form as this yields good processability and mechanical properties. The high cost of GA Ti64 material is a significant cost driver in the AM process. Ti64 HDH (Hydrogenation-Dehydrogenation) is a melt free powder production process that produces a lower-cost form of titanium powder using traceable recycled feedstock. Compared to its spherical GA counterpart, HDH powder is angular in shape and larger in particle size. These attributes can hinder the LPBF processing of these powders and negatively impact the mechanical properties of the final part. However, this study shows that process parameters can be developed for this particular material, along with standardized Hot Isostatic Pressing and Annealing, which results in mechanical properties similar to that achievable with GA powder while reducing cost. In this study LPBF Ti64 HDH samples were fabricated, heat-treated, and HIP-ed in three different variants. They were then machined and tensile tested in accordance with ASTM E8 standard. Each variant was then analyzed for density, microstructure, and chemical composition.
Titanium Powder for AM and MIM made by Titanium Sponge Manufacturer
M. Tomita, OSAKA Titanium Technologies Co., Ltd.
Japan
We have the world's second largest production capacity for titanium sponge and have been maintaining a stable supply of titanium sponge to customers in Europe, U.S. and Japan, mainly in the medical and aerospace industries over our 70-year history since our foundation. Our high-quality products are highly regarded particularly in applications that require high reliability. We have been involved in the production of spherical titanium powder for almost 30 years including their development and have applied the system of stable supply and quality assurance we have developed in the production of titanium sponge to CP titanium and titanium alloy powder for AM.
In this report, we introduce titanium and titanium alloy powder that we have developed and manufactured from the viewpoint of stable supply and high quality. We will also present some cost-efficient titanium alloy powder that takes advantage of the strengths as a titanium sponge powder manufacturer.
From Requirements to Qualified Parts – Selecting the Right Titanium Powder for AM
J-F Carrier, Tekna
Canada
Additive Manufacturing is a relatively young technology that is finally reaching its plateau of productivity. In order to meet the promises of the technology and benefit from its capabilities, one must be aware of the good practises and industry standards that have been adopted by experienced members of the AM community. With regards to titanium feedstock, this presentation aims at educating AM newcomers on leading practices for successful qualifications programs. Topics such as technical definitions, management approaches, selection criteria, quality system evaluation and general operations management are covered.
Bound Metal Deposition of Ti-6Al-4V Alloy
A. Bose, Desktop Metal, Inc.
USA
Additive manufacturing (AM) often referred to as 3D Printing has had a major impact on the manufacturing sector. The ability to make parts without any tooling enables creation of new designs faster with a lower cost and design freedom that was not possible earlier. Elimination of the need for machining is especially critical for materials that are hard to machine, such as titanium alloys. The AM processes typically results in lower material waste, which is another advantage for high-cost materials like titanium and its alloys, and provides manufacturers with a shorter time-to-market. Material extrusion is an AM process that is based on the process of fused filament fabrication that was developed initially for polymer-based materials. Bound Metal Deposition (BMD) is a process within the material extrusion category that has its roots in fused filament fabrication (FFF) and metal injection molding (MIM) and is capable of fabricating complex shaped parts from metals and alloys. An advantage of the BMD process is that the part production does not require handling of loose powder as the powder is bound by polymeric material. This paper will detail the BMD processing of a Ti-6Al-4V alloy including the development of its microstructure and properties.
Effect of Hot Isostatic Pressing on the Performance of Heat Treated Ti-6Al-4V Alloys Manufactured via Laser Powder Bed Fusion
P. Davies, Sandvik Additive Manufacturing
Sweden
Given the increased development of additive manufacturing technologies, which allows the production of complex-shaped advanced parts, a special attention is necessary towards reducing processing defects and achieving fully dense and homogenous materials. In this work, the assessment of Ti-6Al-4V powders is thoroughly carried out, followed by production of parts by multi-beam laser powder bed fusion (LPBF) and post-processing treatments, including hot isostatic pressing (HIP) with a focus on reducing porosity. Fundamental knowledge is built through the analysis of the resultant powder and microstructures in order to predict mechanical properties. Room temperature tensile strength, impact toughness and high-cycle fatigue properties are reviewed, assisted by a microscopy study to detect any microstructural damage, which can drastically reduce mechanical performance and lead to the propagation of cracks under dynamic loading. The presence of such defects and their influence on the performance of heat-treated and HIPed parts are also discussed to evaluate building parameters and bespoke heat treatments to achieve superior properties. A comparison is made between the effect of these stages on LPBF and traditionally cast and HIPed Ti-6Al-4V alloys for aerospace and medical applications.
Examination of Cold Rolling and Annealing Processes for Ti-6Al-4V and Ti-5Al-2.5Fe Roll Compacted Strips
S. Clemens, Dalhousie University
Canada
Direct powder rolling (DPR) is a powder metallurgy process which uses a rolling force to compact powders into continuous sheets or strips. The strips produced are porous and are sintered to increase the bond between particles. Cold rolling is then implemented to increase density and reduce thickness of the strips, and annealing processes are used to further reduce porosity and control the mechanical properties. Sheets of Titanium and Ti-alloys produced via DPR methods presented in the available literature have not yet shown adequate mechanical properties necessary for commercial use. The advancement of the DPR is highly desirable with the availability of low-cost powder feedstock; this would allow for a widespread use of Titanium as a light metal in the Canadian aerospace and automotive industries, facilitating weight reduction, lower fuel economy, and ultimately a reduction in greenhouse gases. CP-Ti grade 3 sponge powder was blended with a 60Al:40V master alloy or elemental aluminum and iron powders to create mixtures of Ti-6Al-4V and Ti-5Al-2.5Fe respectively. These powders were then roll compacted to form strips. Previous work has examined various sintering conditions and cold rolling paths; densities greater than 99.5% have been achieved. The current work seeks to optimize the cold rolling path and will be evaluated by mechanical and microstructural properties in addition to density.
Alternative Manufacturing Process for Titanium Braze Alloy
C.G. McCracken, Oerlikon Metco Inc.
Canada
Titanium braze alloys are often used in the manufacture of composite honeycomb structures and heat exchangers made from titanium alloys, offering lightweight composite structures with increased strength and stiffness. This paper will focus on the most commonly used titanium braze alloy, BTi-1, (Ti-15Ni-15Cu) with a melting range of 900-950°C and manufactured using an atomizing process. This paper presents a totally new BTi-1 powder manufacturing process which incorporates titanium’s unique ability to undergo a reversible hydride-dehydride (HDH) process. This new HDH BTi-1 braze alloy powder has been successfully trialed to join titanium substrates and this paper also describes the unique HDH BTi-1 braze powder manufacturing process and compares braze powders and brazing joints against a conventionally produced atomized BTi-1 powder.
Evaluation of AM Process Productivity and Resulting Properties of Titanium Ti-6Al-4V
K. Kakko, EOS
Finland
Higher build rates in Laser Powder Bed Fusion (LBPF) are desirable, as faster processing and shorter part building times can effectively reduce the cost-per-part. The aim of the present study was to compare the productivity and properties of EOS Ti-6Al-4V produced with different LBPF build rates and with different post-processing routes. The microstructures and mechanical properties of the parts produced with different build rates were analyzed using microscopy, mechanical testing and results compared to wrought reference material. The results indicate that the productivity of the processes can be increased by using, e.g., higher layer thicknesses, but this increased productivity can come at a cost of deteriorating some of the material properties. It is therefore fundamental to understand the correlation of productivity, material properties and application requirements, to maximize the productivity of this manufacturing process.
A Study on the Sintering of Fine Titanium Powders
R. Pelletier, National Research Council
Canada
It has been an objective for many years to produce near net shape metal injection molding (MIM) components with density and mechanical properties close to those obtained with wrought titanium and titanium alloys. Recent developments enabled the production of MIM parts with high density while maintaining the fine microstructures leading to good mechanical properties to the sintered materials. It is, however, still unclear how the MIM conditions are providing the high densities obtained. Indeed, it was observed that these fine powders don’t reach such high density when loose sintered at the same temperature. It appears that the MIM route creates favorable conditions that promote densification. This paper investigated potential sources responsible for the improved densification when using the MIM process. The main hypotheses investigated were the higher initial relative density of the MIM parts, the capillary forces generated by the slowly vanishing liquid residual binder that improves the initial contact between individual particles prior to sintering, and the presence of binder decomposition products that could contribute to activate sintering.
Investigation of the Effect of Build Volume on Reusability of Ti-6Al-4V Plasma Atomized Powder L-PBF Process
M. Habibnejad-Korayem, AP&C, A GE Additive Company
Canada
Additive manufacturing continues to grow as an effective method of producing high quality and complex parts. With this growth, attention is now shifting to improved efficiency of the process and its materials. A popular material in the aerospace and biomedical additive field is Ti-6Al-4V. The particularly high production costs of this material make this an even more important area of study. Powder reuse represents a logical method to reduce these costs but presents several key issues. Reused powders often see increased oxygen levels, crack formations within powders, formation of agglomerates and changes to the overall particle size distribution and powder flowability. This study aims to investigate the effect of build volume on the properties of reused powder over 8-9 cycles. Both the characteristics of the powder itself as well as that of produced parts were investigated and include part surface roughness, porosity, microstructure, texture as well as powder morphology and flowability. A combination of multiple characterization methods including novel approaches such as the FT4 powder rheometer allow for the results of this study to be comprehensive. The powders used in this investigation had an initial size distribution of 15-45 μm and were printed with a Laser Powder Bed Fusion (L-PBF) printer. The characterization of parts and powders were completed after each cycle and were taken with a build volume of both 10% and 20%. The reuse strategy implemented was the single batch strategy which utilizes a single batch of powders without blending with virgin powder throughout the cycles. This study aims to track the evolution of part properties as well as powder properties as the powder passes through many reuse cycles. With these results, the goal is to provide insight as to how to track powder degradation as well as provide insight for consumers as to the quality of parts produced from reused powders.
Landing Gear Components by Additive Manufacturing, the Story from Powder to Printing
C.P. Eonta, MolyWorks
USA
This presentation will discuss production of additive manufacturing grade powders and landing gear components for aerospace applications. Research and development includes landing gear material coupons and full-scale parts. Printed coupon data will be presented such as: low and high cycle fatigue. The process under development conforms to material specifications required for airworthiness certification and compliance with Title 14 Code of Federal Regulations, which includes: derived mechanical properties. Adoption of production process will be discussed and how consistent production of landing gear component material which conforms to material specifications required for airworthiness certification and compliance with Title 14 Code of Federal Regulations is being developed.