Individual Papers

Authors:

Carlos Belei (1), Zuzana Kovacova (1), Johannes Bieg (2), Erich Neubauer (1)

1-RHP-Technology GmbH, Technologie- und Forschungszentrum, Austria

2-ESA - European Space Research and Technology Centre (ESTEC), The Netherlands

Abstract:

This study investigated the hot pressing of three distinct high entropy alloy (HEA) powder compositions, namely CrMo0.5NbTa0.5TiZr (named HEA-01), AlCrMoNbTi (HEA-02) and AlCrFeNiTi (HEA-03). The experimental design focused on varying temperature and dwell time, while pressure remained constant. Density was adopted as a response, which was assessed through both quantitative (using Archimedes density test with theoretical densities as a reference) and qualitative analysis (via microstructural examination). Subsequent hardness testing was also performed. It was observed that for HEA-01 and 03, fully dense parts were achieved in conditions where reactions between the constituents occurred, which resulted in material loss via “squeezing” phenomenon (i.e., when excess material is expelled from the die during pressing). HEA-02 achieved densities above 99% without major squeezing or melting being reported. In any case, the observed microstructure was considered heterogeneous. Depending on processing conditions, HEA-01 and HEA-02 reached hardness values of 341 ± 25 and 429 ± 37 HV10, respectively, while HEA-03 was measured at 525 ± 25 HV10.

DOI:

https://doi.org/10.59499/EP246281334

Authors:

Faraz Deirmina (1), Lorenzo Quarzago (2), Eleonora Bettini (1), Matthew Ritche (3), Daniel Butcher (3), Shahin Mehraban (3), Nicholas Lavery (3), Massimo Pellizzari (2)

1- Powder R&D Group, Sandvik Additive Manufacturing, Sweden

2- University of Trento, Dept. of Industrial Engineering, Italy

3- Swansea University, MACH1 Laboratories, Dept. of Mechanical Engineering, United Kingdom

Abstract:

Hot work tool steels with medium C contents are known to be difficult to process by laser powder bed fusion (L-PBF). Cold and, to a lesser extent, hot cracking occurs in these alloys. Cold cracks are attributed to the low ductility and large residual stresses due to the complex thermal profiles. These can be avoided by platform preheating, which may introduce additional costs and side-effects on microstructure and properties. Therefore, the market trend is to develop new steel grades with improved 3D-printabilty. In this work, a prototype alloy with a leaner C content is proposed. To compensate for the negative effect of reduced C, computational thermodynamics was used to define chemistries with an optimized balance of carbide forming elements, and Si. The prototype tool steel shows enhanced L-PBF processability, and properties meeting and/or exceeding those of wrought AISI H13 in terms of hot strength, tempering and thermal fatigue resistance.

DOI:

https://doi.org/10.59499/EP235765264

Authors:

Montero-Sistiaga Maria (1), Osinga Timo (1), Haagsma Ralph (1), Bottazzi Olmo (2), Esveldt Vincent (2), Bautmans Ludo (3), Hamer Wouter (4), de Smit Marc (1)

1- NLR- Royal Netherlands Aerospace Centre, Marknesse, Netherlands

2- Mokveld Valves B.V., Gouda, Netherlands

3- Oerlikon Metco AM powders, Sint Truiden, Belgium

4- Shell Global Solutions International B.V., Amsterdam, Netherlands

Abstract:

Extensive research is currently done on microstructure and mechanical property characterisation of metal additive manufacturing technologies. However, there remains a limited focus on the combination of these technologies. This study addresses this gap by combining laser powder bed fusion (LPBF) and directed energy deposition (DED) technologies to produce a check valve. The interior of a valve requires high corrosion resistance which can be obtained using In718, while the exterior benefits from more cost effective material, in this case 316L. From the consolidation side, LPBF allows the production of small complex features and DED offers a higher production rate and the possibility of tailoring compositions and mechanical properties. The interface quality and microstructure of different multi-material combinations were studied in this work. Tensile properties were investigated of hybrid multi-material parts to select the best combination. In addition, the production route for producing a multi-material check valve combining LPBF and DED was developed.

DOI:

https://doi.org/10.59499/EP246281394

Authors:

Farshad Khorasani (1), Aydin Selte (2), Yu Cao (1)

1- Chalmers University of Technology, Sweden

2- Uddeholm AB, Sweden

Abstract:

Hybrid tool steels, designed to meet diverse specifications, offer superior fatigue life, toughness, and abrasion resistance. However, this may pose significant challenges in traditional manufacturing. The current study explores the use of Hot Isostatic Pressing (HIP) to bond a high-wear-resistant cold work tool steel powder (Vanadis 8 SuperClean) with a tough hot work tool steel bar (Orvar 2 Microdenodized). The effectiveness of HIP in creating hybrid tool steels is assessed. The impact on the microstructure and mechanical property in terms of hardness in the bonding zone has been examined by employing various analytical methods and simulations. The results confirm a strong bond achieved through HIP, with promising initial outcomes.

DOI:

https://doi.org/10.59499/EP246278227

Authors:

Wolfgang Limberg (Helmholtz-Zentrum Hereon, Germany) Vasil M. Garamus (Helmholtz-Zentrum Hereon, Germany) Eshwara Nidadavolu (Helmholtz-Zentrum Hereon, Germany) Thomas Ebel (Helmholtz-Zentrum Hereon, Germany) Berit Zeller-Plumhoff (Helmholtz-Zentrum Hereon, Germany)

Abstract:

Partly degradable implants consisting of a titanium and a magnesium part allow for novel therapies in medical treatment of bone fractures. In this study, as test specimens MIM-produced titanium tensile test specimens were coated around the gauge length with magnesium MIM feedstock via injection moulding. The magnesium coating was then removed by two different ways: At some specimens mechanically by cutting and grinding and at the other specimens chemically by degradation in 0.9 wt.% NaCl solution.The tensile test properties of the permanent titanium component before and after the removing of the temporary magnesium part were evaluated at room temperature. Hydrogen loading of the titanium parts after chemical degradation was observed. This increase of Hydrogen content of more than 2000 µg|g led to massive embrittlement. Plastic elongation decreased from over 12% to below the detection limit and tensile strength decreased from more than 800 down to 500 MPa.

DOI:

https://doi.org/10.59499/EP256764931

Authors:

Naiara Azurmendi (TECNALIA, Spain) Iñigo Agote (TECNALIA, Spain) Xabier Gómez (TECNALIA, Spain) Irati Zurutuza (TECNALIA, Spain) Cristina Fernandes (PALBIT S.A., Portugal) Daniel Figueiredo (PALBIT S.A., Portugal) Bruno Guimarães (PALBIT S.A., Portugal)

Abstract:

Additive manufacturing of hard metals is gaining attention for its ability to create complex parts and innovative designs. Binder Jetting (BJ) is particularly promising due to its low cost, fast production, and ability to produce stress- and crack-free parts with isotropic properties. The correct binder selection plays a significant role in determining both the green part properties and, especially, the depowdering performance. This study investigates the influence of two different binders (AQUAFUSE and CLEANFUSE-commercial designations) on the properties of hard metal parts manufactured by BJ using commercially available WC-12%Co powder (WOKA 3111FC). The green part properties (green density, green strength), as well as sintered part properties (density, shrinkage, and microstructure), obtained using each binder type, were evaluated and compared. The results suggest that binder selection is a critical factor in optimizing the performance of BJ-manufactured hard metal parts and highlight the potential of CLEANFUSE for applications requiring higher mechanical integrity.

DOI:

https://doi.org/10.59499/EP256767731

Authors:

Lucia Garcia de la Cruz (Universidad Carlos III de Madrid, Spain) Gabriel Caballero (Universidad Carlos III de Madrid, Spain) José Manuel Torralba (Universidad Carlos III de Madrid; IMDEA Materials Institute, Spain) Robin Kromer (I2M, Université de Bordeaux, Arts et Métiers, CNRS, France) Mónica Campos (Universidad Carlos III de Madrid, Spain)

Abstract:

Powder selection to manufacture metallic materials via Material Extrusion Additive Manufacture (MEX) highly affects the ability to process the designed parts, where criteria such as availability or price, are considered. However, powder properties have a major impact in the stages of MEX. In this study, two 316L stainless steel powders with different granulometry were selected (d50 of 12 and 33 mm with Sw of 3.14 and 5.95 respectively), to assess the influence of particle size and PSD on feedstock performance in g-MEX. Feedstock with 55 (vol.)% solid loading was prepared and characterized through rheological oscillatory testing to analyze the effect of temperature and frequency in its fluid-like behavior. The two feedstocks were then evaluated in terms of extrudability, investigating the ability to extrude continuously and the particle size distribution in the strand. Additionally, debinding and sintering were carried out to evaluate the effect of granulometry on the final part.

DOI:

https://doi.org/10.59499/EP256768017

Authors:

Lucas Vogel (1,2) ; Qaiser Ali Khan (2) ; Martina Zimmermann (3,4) ; Carlo Burkhardt (1)

1- Institut für strategische Technologie- und Edelmetalle, Hochschule Pforzheim, Tiefenbronner Str. 65, 75175 Pforzheim, Germany

2- Metshape GmbH, Tiefenbronner Str. 59, 75175 Pforzheim, Germany

3- Fraunhofer-Institut für Werkstoff- und Strahltechnik IWS Dresden, Winterbergstr. 28, 01277 Dresden, Germany

4- Institut für Werkstoffwissenschaft, Technische Universität Dresden, Helmholtzstraße 7, 01069 Dresden, Germany

Abstract:

The need for additive manufactured parts with high dimensional accuracy and high surface quality leads to innovation in sinter-based AM. A promising approach is the emerging lithography-based metal manufacturing (LMM) which combines powder metallurgy and stereolithography. As this is a novel technology, this study aims to investigate the printing parameters: degree of powder filling of the feedstock, layer thickness, coating speed, coating mode and size of the material roll, with the help of a DoE. After the previously published investigation of green part characteristics, the samples are debound and sintered. These parts are analysed with focus on geometrical accuracy and densification. The DoE enables analysis of correlations between printing parameters and densification behaviour. Therefore, it improves the understanding of the technology and enables further optimization.

DOI:

https://doi.org/10.59499/EP235762089

Authors:

Lucas Vogel (University Pforzheim, Germany), Martina Zimmermann (Technical University Dresden, Germany)

Abstract:

Lithography-based metal manufacturing (LMM) is an emerging technology for the 3D production of metal parts with high dimensional accuracy and outstanding surface quality. To reliably reproduce these properties, a better understanding of parameter characteristics correlation is necessary. One of the most important characteristics of the printed part is the green density and its distribution within the building volume. This study investigates the printing parameters degree of powder filling of the feedstock, layer thickness, coating speed, coating mode and size of the material roll, with the help of a DoE. The green parts are getting characterised by dimensions, weight and density using the principle of Archimedes. Also, the strength of the green part is investigated. As the densification during sintering works as a magnifying glass for imperfections and differences in green density of the green parts, all samples get sintered and analysed on their density and shrinkage afterwards.

DOI:

https://doi.org/10.59499/WP225367139

Authors:

Naiqi Shang (1), Thomas Dahmen (1), Thomas Lundin Christiansen (1), Venkata Karthik Nadimpalli (1)

1- Department of Civil and Mechanical Engineering, Technical University of Denmark, Denmark

Abstract:

Low green strength of binder-jetted parts can lead to potential damage during depowdering and thus complicates green part handling. Understanding and optimizing green strength is therefore essential for the overall control and repeatability of the process. This study systematically investigates the effect of different saturation levels, layer thicknesses and part orientation on the mechanical properties, via compression testing, of binder-jetted cylindrical green parts. The results indicate excellent suitability of the spray-formed powder as binder jetting feedstock due to the uniform spherical particle morphology and high flowability. Mechanical testing indicated that higher binder saturation levels and loading direction perpendicular to the build direction are found to improve the compressive green strength, whereas the layer thickness only has a minor influence. The maximum compressive green strength was achieved as 7.67 MPa on average under the condition of 120% saturation and 90 µm layer thickness. Injection Molding requirements.

DOI:

https://doi.org/10.59499/EP235764032

Authors:

Thalita Queiroz e Silva (1), Meysam Mashhadikarimi (1), Pâmala Samara Vieira (1), Anderson Costa Marques (1), Gabriel Dos Santos Vasconcelos (1), Lucas Marques Dos Santos (2)

1-Materials Science and Engineering Postgraduate Program, Federal University of Rio Grande do Norte, Brazil.

2-School of Science and Technology, Federal University of Rio Grande do Norte, Brazil.

Abstract:

Composites formed by a copper matrix, reinforced by a ceramic and refractory material, stand out due to their relevance in electrical conductor applications. In this context, this study investigated the hardening of copper powder with the addition of different concentrations of tungsten carbide (5, 10, 15 and 20% by weight) prepared by high-energy milling (HEM) for 1, 2, 5, 10 and 20 hours. The powders were characterized by SEM, XRD and Vickers microhardness. The results showed that the milling method was efficient for obtaining Cu-WC composites, with strong bonds between the phases. The diffractograms showed characteristic copper and tungsten carbide peaks, with no secondary phases. The Vickers microhardness value is directly related to the amount of WC and the milling time; consequently, the 20% WC composite powder milled for 20 hours had a microhardness of 251 HV, exceeding the values of the other powders.

DOI:

https://doi.org/10.59499/EP246281184

Authors:

Hanna Nilsson Åhman (1,2), Pelle Mellin (1), Francesco D’Elia (2), Cecilia Persson (2)

1- Swerim AB, Sweden

2- Div. of Biomedical engineering, Dept. of Materials Science and Engineering, Uppsala University, Sweden

Abstract:

Powder bed fusion – laser beam (PBF-LB) of Mg alloys has great potential, both for producing patient specific implants and lightweight structures. However, the relationship among PBF-LB parameters, microstructure, and resulting material properties is poorly understood. As a first step towards a better understanding, the effect of various process conditions on the melt pool geometry and the microstructure formed is herein investigated. From the results it can be concluded that a lower scanning speed or a higher power result in deeper melt pools and more dendritic grains due to a warmer process. Similarly, thinner wall thickness also resulted in dendritic grains. A change in laser scanning line rotation between each layer showed that the grains tend to grow within the melt pool, rather than across several layers as seen for other alloys. These results show the importance of the parameters studied, and future work should investigate the resulting material properties.

DOI:

https://doi.org/10.59499/EP235762947