Proceedings

Authors:

Alexander Holzer (TU Wien, Austria) Simon Pfeifenberger (TU Wien, Austria) Atul Anand (TU Wien, Austria) Christian Gierl-Mayer (TU Wien, Austria)

Abstract:

Sinter-based additive processes, such as lithography-based metal manufacturing, enable properties and design possibilities that cannot be manufactured any other way. The final properties and geometrical precision of indirect additive manufacturing techniques are strongly affected by the quality of the debinding procedure. Therefore, several aspects - temperature, atmosphere and pre-treatments like heat treatment or solvent debinding - play an important role. In this work, the main influences and consequences of the debinding procedure are shown. Results show that the key factor is the thickness of the sample. Therefore, the temperature and dwelling time is adjusted to allow the diffusion processes. In general, synthetic air allows better removal of carbon. The process window for the optimum treatment is narrowed by the stability before sintering. Those consequent possible errors, like deformation, fragility and too high carbon content can be avoided and allow a higher performance of the component in the end.

DOI:

https://doi.org/10.59499/EP256763871

Authors:

Recalcati S. (1), Denis G. (2), Mortensen A. (2), Fais A. (1)

1- EPoS Technologies SA, ZI du Vivier 22, 1690 Villaz-St-Pierre (Switzerland)

2- Laboratory of Mechanical Metallurgy (LMM), Ecole Polytechnique Fédérale de Lausanne (EPFL), MX-D 141, Station 12, CH-1015 Lausanne (Switzerland)

Abstract:

This work investigates the in-situ formation of TiC in titanium blended with carbon during Electro-Sinter-Forging (ESF) at different levels of Specific Energy Input kJ·g-1. When sintering powder mixtures of CP-Ti in compositions between 0.5 to 1%-wt graphite, carbon atoms diffuse and react with titanium to precipitate acicular or dendritic TiC in a near-fully to fully dense material. The shape of these precipitates evolves with increasing levels of energy from being finely dispersed sharp lamellae to a dendritic-like network. Understanding this behavior opens new possibilities to design novel reinforced Electro-Sinter-Forged titanium alloys or composites by precisely controlling the precipitated TiC shape and arrangement with a goal to optimize structural or functional properties of the material.

DOI:

https://doi.org/10.59499/EP235764195

Authors:

Peter Lindecke (amsight GmbH, Germany) Daniel Rommel (Colibrium Additive, a GE Aerospace company, Germany)

Abstract:

This study investigates powder management and associated mechanical properties in the additive manufacturing (AM) of aluminum using Laser Powder Bed Fusion (L-PBF). The focus is on the development of a novel, holistic data management system for digital capture and analysis of the complete powder lifecycle. For the first time, the system enables comprehensive documentation of all quality-relevant powder parameters such as particle size distribution, chemical composition, and flow behavior in conjunction with process data and resulting component properties. In a long-term study, the aging behavior of aluminum powder was systematically investigated over multiple reuse cycles. The results demonstrate that optimized powder reconditioning can be achieved while simultaneously ensuring component quality. The developed data management system thus forms the foundation for cost-efficient and sustainable powder utilization in the L-PBF process while meeting regulatory requirements.

DOI:

https://doi.org/10.59499/EP256767166

Authors:

Yuanbin Deng (1), Anke Kaletsch (1), Christoph Broeckmann (1)

1- Institute for Materials Applications in Mechanical Engineering (IWM) at RWTH Aachen University, Augustinerbach 4, 52062 Aachen, Germany

Abstract:

Binder jetting is ideally suited to produce individual components, as it offers the possibility to directly achieve highly complex geometries. To assure the direct production of net-shape components with optimized process parameters, numerical models across scales were developed in this study to model and simulate each manufacturing step on the entire process chain. Using discrete element and finite element methods, the powder spreading process and the subsequent sintering process were simulated. By considering the influences of the density distribution on green bodies, the gravity, and the friction between the sintering substrate and the sintering parts, the sintering shrinkage and the final geometry could be precisely predicted. The results from simulation were validated with experimental data from both manufacturing steps. With the help of the inverse optimisation, the geometry of the green parts was optimised iteratively, which allows the net-shape components with the desired geometries being manufactured despite sintering distortion.

DOI:

https://doi.org/10.59499/EP235765361

Authors:

Shuigen Huang (KU Leuven, Belgium), Eric Wong (KU Leuven, Belgium), Jun Qian (KU Leuven, Belgium), Jozef Vleugels (KU Leuven, Belgium)

Abstract:

Direct Ink Writing (DIW), also known as robocasting, is a paste extrusion-based layer-by-layer additive manufacturing technique suitable for manufacturing complex geometry green compacts. In this study, NbC-Ni matrix cermets with either a porous scaffold structure or a pore-free rectangular bar geometry were prepared using a combination of DIW and sintering. The water based feedstock ink contained 40 vol% cermet powder mixture and 25 wt% pluronic F-127 hydrogel. The ink was rheologically characterized and printed using a DIW device. Thermogravimetric analysis (TGA) of the paste was performed to define the thermal debinding cycle. After debinding, the printed parts were sintered for 90 min at 1420 °C in vacuum. The microstructure and room temperature hardness of the printed parts were investigated and compared with cermets obtained by conventional press and sinter powder metallurgy.

DOI:

https://doi.org/10.59499/WP225368559

Authors:

Iain Berment-Parr (The Manufacturing Technology Centre Ltd., United Kingdom), Owen Larkin (The Manufacturing Technology Centre Ltd., United Kingdom), Kieran Bullivant (The Manufacturing Technology Centre Ltd., United Kingdom), Simon J Graham (The University of Sheffield, United Kingdom), Ahmad El-Kharouf (The University of Birmingham, United Kingdom)

Abstract:

Net shape powder consolidation is often perceived to be a slow and costly manufacturing method, unsuitable for high throughput batch production of intricate components. This work seeks to challenge that perception by introducing the use of dissolvable space holding inserts that impart an impression into densifying powders. When used under appropriate conditions, these enable simple cylindrical HIP canisters and FAST dies to be used to process complex geometry components and porous structures. Feasibility trials have evaluated the use of water soluble table salt (NaCl) in various forms, combining it with sustainable titanium powders obtained through low energy processing. High integrity titanium samples have been densified, and then extracted by dissolving the salt in water. Fabrication of an innovative hydrogen electrolyser bipolar plate has showcased the industrial potential of this manufacturing method. An embodied carbon analysis has also highlighted significant circular economy advantages compared to traditional energy intensive titanium supply chains.

DOI:

https://doi.org/10.59499/WP225367167

Authors:

Elias Ganthaler (Free University of Bozen, Italy), Hoomaan MoradiMaryamnegari (Free University of Bozen, Italy)

Abstract:

The manufacturing process of sintered components requires the compaction of metal powder in a rigid die, performed for example by a hydraulic powder press. This paper presents a novel, fully coupled model combining a physical hydraulic system model and a Finite-Element-based (FE-based) compaction model to simulate a full press cycle of a powder compaction press. The first model calculates the piston's position by modelling the hydraulic circuit including the valves, hoses, and double-acting cylinders as well as the low-level controller. The piston positions are then passed as input to an FE-based software that implements an adapted multi-surface constitutive model for granular media. This allows to investigate the influence of different trajectories and controllers. In contrast to literature, the fully coupled model allows the simulation of the whole press-cycle instead of the compaction phase alone.

DOI:

https://doi.org/10.59499/WP225371405

Authors:

Yusuke Hirayama (National Institute of Advanced Industrial Science and Technology, Japan) Keigo Kobayashi (Mitsubishi Materials Corporation, Japan) Yuji Shigeta (National Institute of Advanced Industrial Science and Technology, Japan) Zheng Liu (National Institute of Advanced Industrial Science and Technology, Japan) Kenta Takagi (National Institute of Advanced Industrial Science and Technology, Japan) Jun Kato (Mitsubishi Materials Corporation, Japan) Kazuki Okada (Mitsubishi Materials Corporation, Japan)

Abstract:

We found that an alloy containing a minimal amount of rare earth elements in aluminum significantly improves the sinterability of aluminum in a pressureless state. In this presentation, we dynamically observed the sintering process and evaluated in detail how the sintering progressed. Liquid phase sintering is achieved by the liquid phase that is produced when a minimal amount of rare earth element dissolves in aluminum below the melting point of aluminum.

DOI:

https://doi.org/10.59499/EP256768153

Authors:

Vladimir Ivannikov (Helmholtz-Zentrum Hereon, Germany), Fritz Thomsen (Flensburg University of Applied Sciences, Germany), Regine Willumeit-Römer (Helmholtz-Zentrum Hereon, Germany)

Abstract:

A novel discrete element method based approach for modeling of the early stage solid state sintering of metallic powders is proposed. It couples the mass transport driven evolution of geometry of individual contact pairs of spherical particles and their mechanical interaction in a 2-step staggered numerical scheme. At a given time, for each pair of contacting particles a system of mass transport equations is solved to update the parameters describing its local geometry. The changes in the distances between the centers of the particles are converted into the corresponding sintering forces. These are then applied as external loads to a DEM discretization of a compound. The developed approach was used to simulate sintering of packings with several thousands of particles. The numerically predicted neck growth and shrinkage rates agree well with the experimental data obtained for titanium powders for different sintering temperatures.

DOI:

https://doi.org/10.59499/WP225368028

Authors:

Agathe Deborde (IRT M2P, France), Aurélie Franceschini (IRT M2P, France), Stéphane Hans (Aubert&Duval, France)

Abstract:

Powder metallurgy is used in various industries such as aerospace, medical, defence, etc. For high cleanliness materials, metal powders can be produced using the EIGA process (Electrode Induction melting Gas Atomization). The EIGA process involves the crucible-free melting of an ingot followed by atomization using high-pressure argon. A full-scale EIGA is installed at MetaFensch|IRT M2P for R&D purposes (alloy development, numerical simulation, upscaling, etc.).Process parameters such as electrode size and gas parameters have a predominant influence on powder size and yields. On the other hand, chemical composition of the alloy and the associated thermophysical properties have a significant impact on the atomization process, and therefore on the quality of the powders. To better understand the effect of the composition, several alloys were selected (Ti64, titanium aluminide, nickel-based alloys, etc.) and atomized using the EIGA process. The properties of the powders, especially particle size distribution and morphology, are compared.

DOI:

https://doi.org/10.59499/WP225372000

Authors:

Tomi Lindroos (VTT, Finland), Timo Kinos (VTT, Finland), Kimmo Kaunisto (VTT, Finland), Tuomas Riipinen (VTT, Finland), Sini Metsä-Kortelainen (VTT, Finland), Aino Manninen (VTT, Finland), Jenni Pippuri-Mäkeläinen (VTT, Finland)

Abstract:

Electrification of the world has significantly increased the demand for novel high performance electromechanical components. Powder Metallurgy and especially Additive Manufacturing are seen as enablers to produce components based on novel soft magnetic materials with performance and designs unattainable with conventional manufacturing. Fe-Si-X soft magnetic materials were studied by focusing to tailor material to Laser Powder Bed Fusion (L-PBF) processing. Effect of different alloying elements on magnetic, electrical and mechanical properties were studied based on simulations and experiments. The focus was paid on increasing the understanding of segregation occurring at high cooling rates and how it could be utilized in controlling electrical resistivity and consequently the mitigation of eddy current losses. Gas atomized powder corresponding the most promising alloy composition was produced and further, test components were manufactured by L-PBF accompanied by appropriate heat treatments. The results of resistivity and magnetic measurements are promising when compared against conventional Fe-Si alloy.

DOI:

https://doi.org/10.59499/WP225371873

Authors:

Nompumelelo Nkosi (1,2), Natasha Sacks (1,2)

1- Department of Industrial Engineering, Stellenbosch University, Stellenbosch, South Africa

2- DSI-NRF Centre of Excellence in Strong Materials, South Africa

Abstract:

In this study the effect of build direction on the tensile properties of a Ti6Al4V alloy produced by selective laser melting was investigated. Initial cubes were printed using three different scanning patterns, namely island, meander and bi-directional alternating and rotated at 67⁰, to determine the optimum pattern producing the highest density and hardness. From the initial results all three patterns produced similar densities of >99%, while the meander pattern had the highest average hardness. Tensile test samples were printed in the vertical and horizontal directions in terms of the gauge length respectively, using the three scanning patterns and the ultimate tensile strength, % elongation and Young’s modulus was determined. The microstructure of the samples was studied using scanning electron microscopy, x-ray diffraction and computerized tomography. The tensile samples printed in the horizontal direction generally had better strength properties.

DOI:

https://doi.org/10.59499/EP235734146