Euro PM2024 Proceedings

Authors:

Michael Norda (1), Jan Henrik Lübbe (1), Prof. Dr. Frank Petzoldt (1), Prof. Dr. Ralf M. Gläbe (2)

1- Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM, Wiener Straße 12, 28359 Bremen, Germany

2- HSB Hochschule Bremen - City University of Applied Sciences, Neustadtswall 30, 28199 Bremen, Germany

Abstract:

The metal binder jetting (MBJ) process is a powder bed-based Additive Manufacturing (AM) process, which is attracting growing interest. In this process, a liquid binder deposited by a print head bonds the powder particles to create so-called green parts. For a reliable metal binder jetting process, the metal powder must have a high quality. The morphology and particle size distribution have a major influence on the flowability and sinterability of the material. In this work, the aging process is observed particularly regarding the slightly disappearing fine fraction during the process. A practical method is presented to reliably detect the ageing process of the powder. In addition, a method is developed to stop or curb ageing to support constant printing conditions. The experiments are conducted using 17-4PH stainless steel. Several properties of powders and parts are analysed such as particle size distribution, green part density, powder bed density and dimensional tolerances.

DOI:

https://doi.org/10.59499/EP246246174

Authors:

Ella Staufer (1,2), Christian Edtmaier (1), Elisabeth Ballok (1), Jelena Horky (2), Thomas Klein (3), Duyao Zhang (4), Mark Easton (4), Martin Schmitz-Niederau (5)

1- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Austria

2- RHP-Technology GmbH, Austria

3- LKR Light Metals Technologies Ranshofen, Austrian Institute of Technology, Austria

4- Centre for Additive Manufacturing, School of Engineering, RMIT University, Australia

5- Voestalpine Böhler Welding Germany GmbH, Germany

Abstract:

The growing demand for titanium alloys, particularly in the aerospace industry, arises from their remarkable strength-to-weight ratio. However, the commonly used Ti-6Al-4V (Ti64) alloy exhibits columnar grain growth after additive manufacturing, such as powder bed fusion or direct energy deposition, resulting in anisotropic mechanical properties. To overcome this, Ti-Cu-based alloys are introduced for equiaxed grain growth, but their mechanical properties fell short of Ti64. Ternary and quaternary alloying elements (Fe and Cr) are incorporated to enhance mechanical properties. Firstly, several alloys (Ti-6.5Cu-xCr-yFe) produced via powder hot-extrusion exhibit promising microstructure under light microscopy and SEM. Hardness and tensile strength are improved, even exceeding the tensile strength of Ti64. The most promising ones underwent the blown-powder Plasma Metal Deposition process for in-situ alloying, revealing fine microstructures, equiaxed grains, and increased tensile strength. These findings highlight their potential for aerospace applications, presenting isotropic mechanical properties and dense samples.

DOI:

https://doi.org/10.59499/EP246278391

Authors:

Srinivasan Suresh (1), Gillham Joe (1), Marshall M. Jessica (1)

1- University of Warwick, Coventry, United Kingdom

Abstract:

First wall (FW) materials for future fusion reactors have tungsten (W) and ferritic/martensitic steel (FMS) as prime materials. The significant difference in thermo-physical properties of W-FMS joints, specifically, high ductile-brittle transition temperature (DBTT) in W making it brittle at low temperatures and embrittlement due to recrystallization. Cemented tungsten carbide (cWC)-reactive sintered boride (RSB) composites are considered as promising candidate to develop reliable joining technology albeit cWC-RSB to steel joint is challenging. Brazing is a prospective technology; brazing experiments were conducted using Cu-based and FeCr-based interlayers/foils with low-activation elements and high Z-materials. This study compares the effect of brazing compositions, temperature and holding time. The microstructures, mechanical properties, and the strength of brazed joints were investigated using SEM, EDS and EBSD analysis with microhardness and fracture toughness. The results show that cWC-RSB to steel successfully joined by brazing, achieved like W-steel joints and boron in cWC-RSB suppresses the thermo-physical property mismatch.

DOI:

https://doi.org/10.59499/EP246283792

Authors:

Melanie Stenzel (1), Bahar Fayyazi (1), Shaumik Lenka (2), Nicholas Sim (2), Thomas Wagstaff (2), Yuji Ishino (2), Pimin Zhang (2), Yining He (2)

1- TANIOBIS GmbH, Goslar, Germany

2- Alloyed, Yarnton, United Kingdom

Abstract:

Many applications among aerospace, defense and energy generation require materials being capable to perform in high temperature environments. Nb-base alloys are becoming particularly interesting if the temperatures exceed ~1050°C as they are outperforming even the most advanced Ni- and Co-base alloys. Notably, conventional production methods for Nb-base alloys are challenging, especially if parts with complex shapes are to be manufactured. The use of powder-based processes e.g. AM or HIP, opens up new opportunities to economically produce complex-shaped parts. However, for these processes the application of suitable high-quality powders is mandatory. In this context, the production of Nb-base alloys as powder feedstock using the electrode induction-melting gas atomization (EIGA) is reported. Powders and additively manufactured parts were investigated by X-ray diffraction, scanning electron microscopy, mechanical tests, and electro-thermal mechanical testing (ETMT). The mechanical performance, i.e., strength of parts processed by laser beam powder bed fusion (PBF-LB) clearly outperforms that of conventionally manufactured parts.

DOI:

https://doi.org/10.59499/EP246278262

Authors:

Markus Weinmann (1), Melanie Stenzel (1), Jan Johannsen (2), Christian Lauhoff (3), Thomas Niendorf (3)

1- TANIOBIS GmbH, Goslar, Germany

2- Fraunhofer Research Institution for Additive Manufacturing Technologies IAPT, Hamburg, Germany

3- University of Kassel, Institute of Materials Engineering, Kassel, Germany

Abstract:

The development of spherical Ti/Nb/Ta alloy powders with compositions Ti-xNb-6Ta (x = 20, 27, 35 wt%) by electrode induction melting gas atomization (EIGA) and their processing by laser beam powder bed fusion (PBF-LB/M) are reported. Microstructure investigations by X-ray diffraction and scanning electron microscopy including energy dispersive X-ray spectroscopy and electron backscatter diffraction reveal a significant impact of the composition on the structural properties, i.e., phase evolution and texture, and the possibility for a direct microstructure design. Ti-rich alloys preferably solidify in the orthorhombic α’’-phase, whereas in Nb/Ta-rich alloys the body-centered cubic (bcc) β-phase is observed. The alloys possess a very broad processing window and can be printed to full density over a wide range of printing parameters. Additively manufactured Ti-27Nb-6Ta shows a unique behavior, since strength and elongation at failure strongly depend on the printing parameters applied. The underlying microstructural mechanisms, i.e., the influence of the laser energy on texture effects and phase formation, are discussed.

DOI:

https://doi.org/10.59499/EP246268362

Authors:

Maheswaran Vattur Sundaram (1), Fredrik Vinnerborg (1)

1- Höganäs AB, Sweden

Abstract:

Astaloy® CrS is a Cr pre-alloyed water-atomised powder containing 0.85wt.%Cr and 0.15wt.%Mo, developed as a sustainable alternative to Fe-Cu-C PM steels. For applications demanding higher performance, secondary operations such as heat treatments(HT) are necessary. Carburising is one HT process to improve surface hardness, wear resistance, and fatigue strength, leading to superior performance. For Fe-Cu-C materials, gas carburising(GC) is conventionally used, but for Cr pre-alloyed materials, low-pressure carburising(LPC) is preferred since it prevents oxidation. This investigation assesses the processing capabilities and the material requirements for successful heat treatment of CrS. To achieve this, LPC and GC were performed on both CrS and Fe-Cu-C samples with densities ranging from 7.1 to 7.4 g/cm3, sintered at 1120°C. The results indicated a higher static and fatigue performance after GC for CrS than the Fe-Cu-C. LPC provides better control of case depth for varying densities but requires a material with better hardenability for gas quenching.

DOI:

https://doi.org/10.59499/EP246278537

Authors:

Annalisa Fortini (1), Ottavia Vezzani (1), Michele Gragnanini (1), Gian Luca Garagnani (1), Mattia Merlin (1)

1- University of Ferrara, Department of Engineering, Italy

Abstract:

Powder metallurgy (PM) steels containing diffusion-bonded Ni are characterized by microstructural inhomogeneities related to the lack of Ni diffusion during sintering. As a result of sinter-hardening treatment a martensitic microstructure with Ni-rich austenite areas is obtained. Aiming at homogenizing the Ni distribution by diffusion, in the present study two different post-sintering treatments were performed, consisting in a vacuum quenching at 900 °C for 1 h and 3 h, respectively, followed by inert gas cooling. Microstructural evolution was investigated through hardness tests, optical and scanning electron microscopy, coupled with image analysis techniques. The mechanical properties of sinter-hardened and heat-treated samples were evaluated through Charpy impact, tensile and pin-on-disk tribological tests. The main effect on material properties was given by austenite content reduction and the resulting formation of Ni-rich martensite.

DOI:

https://doi.org/10.59499/EP246281385

Authors:

Eshwara Nidadavolu (1), Martin Wolff (1), Thomas Ebel (1), Regine Willumeit-Römer (1)

1- Institute of Metallic Biomaterials, Helmholtz-Zentrum Hereon, Germany

Abstract:

Liquid phase sintered biodegradable Mg-0.6Ca alloy generally exhibits an isotropic microstructure with homogenously restricted grain size of 30 µm, even after long sintering durations of 60 h at 625 °C. Such sintered microstructures reveal the presence of numerous impurity oxide particles at the grain boundaries, which are evident also on the initial gas atomized powder surfaces. However, after a mechanical powder sieving treatment for 20 min, the surface SiO2 concentration dropped from initially 220 ppm to 85 ppm, resulting in heterogeneous grain coarsening after sintering for 18 h at 625°C. For the use of Mg-Ca materials as biodegradable implants, reproducibility of in vitro degradation results is a prerequisite, for which a homogenous grain structure is desired. However, the lowered oxide-pinning effect at certain grain boundaries created heterogeneous grain coarsening and this indicates the necessity for the careful handling of fine powders to ensure repeatability in degradation and mechanical properties.

DOI:

https://doi.org/10.59499/EP246281669

Authors:

G. Gaillard (1), M. Soulier (1), C. Flament (1), P. Faucherand (1), V. Bonnefoy (1), V. Chastand (2), C. Marchand-Maillet (2), G. Bonnefont (3)

1-Université Grenoble Alpes, CEA, LITEN, France

2-Dassault Aviation Argonay, France

3-AddUp SAS, France

Abstract:

Powder characteristics in a laser powder bed fusion (LPBF) process have a major impact on the quality of the parts produced [1] [2]. An in-depth study was done to assess the effect of powder properties on LPBF-densified materials, focusing on two alloys (titanium and aluminum). Both powders were processed in a wide range of conditions in order to determine their induced effects: batch variability at specification thresholds, powder after multiple reuses and storage-aged powder. For each configuration, the powders and the LPBF-densified materials were subjected to physical, chemical, microstructural and mechanical analyses. The study of the effects of powder characteristics led to define recommendations for the management of supply, reuse and storage so as to optimize production costs while maintaining an acceptable quality level.

DOI:

https://doi.org/10.59499/EP246277018

Authors:

Marie Luise Scheck (1), Rui Joao Santos Batista (3), Simone Herzog (2), Anke Kaletsch (1,2), Constantin Häfner (3,4), Christoph Broeckmann (1,2)

1- Institute for Applied Powder Metallurgy and Ceramics (IAPK) at RWTH Aachen e.V., Germany

2- Institute for Materials Applications in Mechanical Engineering, RWTH Aachen University, Germany

3- Fraunhofer Institute for Laser Technology ILT, Germany

4- Laser Technology LLT, RWTH Aachen University, Germany

Abstract:

Processing carbide-rich tool steels with laser-based powder bed fusion is challenging as cracks occur frequently. Substrate plate preheating is commonly applied to improve the processability as the temperature gradients are lowered and stresses reduced. The modified temperature gradients alter the microstructure formation of the alloy. In this study, a carbide-rich tool steel was processed at RT, 500°C and 800°C substrate plate preheating which lead to different precipitated carbide and retained austenite contents. The high substrate plate heating of 800°C significantly reduced cracking of the alloy and a fully martensitic microstructure was obtained. In the samples built at RT or 500°C, the lower diffusion hinders carbide precipitation and thus leads to austenite stabilization. These specimens show cracks despite their higher retained austenite contents. Here, the retained austenite has a high hardness, and therefore it is assumed that it is distorted, brittle and thus cannot prevent crack growth within the specimens.

DOI:

https://doi.org/10.59499/EP246281362

Authors:

Santiago Cano Cano (1), Johannes Bosters (1), Clemens Sperling (1), Denise Mödder (1), Johannes Stögerer (1), György Harakály (1)

1- Incus GmbH, Austria

Abstract:

Lithography-based Metal Manufacturing (LMM) is an additive manufacturing (AM) technology that delivers components with high feature resolution and surface quality. By utilizing common Metal Injection Molding grade powders (d90 <25 µm) in the process, a surface roughness of Ra < 2 µm can be achieved, with stable geometric features down to 100 µm. Although these as-printed component parameters surpass those of other metal AM technologies, some applications demand lower surface roughness. To enhance part quality, one approach is the introduction metal powders with smaller size distribution. This not only improves the surface roughness, but also augment the sintering process by facilitating better powder packing. In pursuit of this objective, steel alloys of 316L and 17-4PH with varying size distribution have been analysed, with a specific focus on their processability in the LMM technology and their effectiveness in raising the quality of the components.

DOI:

https://doi.org/10.59499/EP246281371

Authors:

Farnoosh Forouzan (1,2), Heike Henrich (1), Milad Zohrevand (3), Dimitris Chasoglou (1)

1- Höganäs AB, Sweden

2- Luleå university of technology, Sweden

3- Tampere university, Finland

Abstract:

In this study, the effect of high-power ultrasonic treatment (UST) in comparison with common thermal tempering of Astaloy® CrS (0.85%Cr-0.15%Mo)-0.8%C pressed and sintered samples after quenching is investigated. Results from microhardness, EBSD, and XRD show a promising level of tempering in the samples just after 4 minutes of UST by decreasing the strain level in the specimen and dislocation annihilation, while the thermal annealing at 200° C for 1 hr resulted in more softening and lower hardness level. The results of this study confirm that the Ultrasonic treatment is an effective rapid and easy method with much lower energy consumption that can be good enough to stress relief the component after quenching and substitute the traditional tempering based on the application.

DOI:

https://doi.org/10.59499/EP246269731