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Authors:

Karin Frisk (Innomat AB, Sweden)

Abstract:

Computational alloy design based on the CALPHAD approach involves physically based models and therefore successfully predicts properties of complex multicomponent metallic materials. When remelting metal powder by laser the effect of rapid solidification on microstructures often requires adjustments of composition, as compared to those of conventionally produced material, to reach adequate properties and avoid cracks. Searching for new compositions outside the common ranges of alloying elements, can benefit from using design criteria and data analysis. The design criteria can for example be hardenability, solidification ranges, corrosion resistance, precipitation hardening. The calculations provide the dataset to be analysed. A few examples of what is possible for Fe- and Al-based alloys, are given. The models, but also the background data, used for the calculations is critical, and this will be illustrated and discussed.

DOI:

https://doi.org/10.59499/WP225372044

Authors:

Felix-Christian Reissner (Fraunhofer Institute for Structural Durability and System Reliability LBF, Germany), Etienne Haberlick (Fraunhofer Institute for Structural Durability and System Reliability LBF, Germany), Karl Burkamp (RWTH Aachen University, Germany)

Abstract:

This paper describes a data-driven methodology to derive reliable S-N curves for PM components that take the hardness, the highly stressed volume, the stress ratio and the density into account. The methodology aims for a fatigue assessment approach applicable for all PM steels. For this, a large database with approximately 800 S-N curves, 20.000 S-N experiments and a broad spectrum of different geometries, materials, loading conditions, sinter conditions etc. is set up. The methodology is based mainly of known analytical functions, such as the Bal’shin equation and the Haigh diagram. The parameters for the fatigue assessment are obtained by optimization of the used analytical functions. As a result, the model leads to a highly reliable fatigue assessment of PM components.

DOI:

https://doi.org/10.59499/WP225371463

Authors:

G. Poehle (1), P. Quadbeck (2), S. Riecker (1), C. Kukla (3), V. Momeni (4), S. Schuschnigg (4)

1- Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM, Dresden, Germany

2- Offenburg University of Applied Sciences, Offenburg, Germany

3- Montanuniversitaet Leoben, Industrial Liaison Department, Leoben, Austria

4- Montanuniversitaet Leoben, Department of Polymer Engineering and Science, Institute of Polymer Processing, Leoben, Austria

Abstract:

Fused Filament Fabrication (FFF) is a widespread additive manufacturing technology, mostly in the field of printable polymers. The use of filaments filled with metal particles for the manufacture of metallic parts by FFF presents specific challenges regarding debinding and sintering. For aluminium and its alloys, the sintering temperature range overlaps with the temperature range of thermal decomposition of many commonly used “backbone” polymers, which provide stability to the green parts. Moreover, the high oxygen affinity of aluminium necessitates the use of special sintering regimes and alloying strategies. Therefore, it is challenging to achieve both low porosity and low levels of oxygen and carbon impurities at the same time. Feedstocks compatible with the special requirements of aluminium alloys were developed. We present results on the investigation of debinding/sintering regimes by Fourier Transform Infrared spectroscopy (FTIR) based In-Situ Process Gas Analysis and discuss optimized thermal treatment strategies for Al-based FFF.

DOI:

https://doi.org/10.59499/EP235764658

Authors:

M. A. Lagos (1); N. Azurmendi(1); A. Lores (1); I. Leizaola (1); I. Agote (1)

1- TECNALIA, Basque Research and Technology Alliance (BRTA), Mikeletegi Pasealekua 2, 20009 Donostia-San Sebastián, Spain

Abstract:

Binder Jetting is capable of cost-effectively producing complex metal and ceramic components without the need for support structures. However, printed parts typically contain porosity due to the use of coarse powders and a loosely packed powder bed. For some materials, it is difficult to achieve full density without infiltration of a secondary lower melting point material.

This work presents the post-densification of binder jetting parts by a pressure assisted sintering process, Spark Plasma Sintering. Sacrificial powder was used in other to maintain the complex geometry. Copper pieces were successfully densified using different starting conditions. However, densification of the pieces was not isotropic, and thus some design considerations are explained in order to obtain the right geometry. Additionally, considerations about the possible scalability and industrial application of this approach are also presented.

DOI:

https://doi.org/10.59499/EP235753924

Authors:

Jazmina Navarrete Cuadrado (CEIT-BRTA, Spain), Tomas Soria Biurrun (CEIT-BRTA, Spain), Steven Moseley (Hilti Corporation, Liechtenstein), Nerea Gonzalez Polvorosa (Hilti Corporation, Liechtenstein), Jose M. Tarragó (Hilti Corporation, Liechtenstein), Jose M. Sanchez-Moreno (CEIT-BRTA, Spain)

Abstract:

Tungsten borides are potential candidates for the fabrication of tool materials. Among them, tungsten tetraboride is attracting increasing attention due to its very high hardness (» 47 GPa), good electrical conductivity and abrasion and corrosion resistance. Nevertheless, the technologies needed to obtain WB4 based usable tools are still to be developed. In this work, full densification of WB4 based hard materials has been achieved by applying glass encapsulated HIP cycles to powders mixtures with different W|B ratios and Ta additions. Contrary to that reported by other authors, it has been confirmed that Ta addition enhance the transformation of tungsten tetraboride (WB4) into tungsten diboride (WB2). Processing parameters have been tailored for retaining the hard WB4 hexagonal phase after sintering reaching hardness values over 26 GPa (HV5). Interaction between WB4 and different metals has been investigated in order to find suitable binder phases for producing tougher WB4-metal cermets.

DOI:

https://doi.org/10.59499/WP225371740

Authors:

Alexandru Sorea (1), Peter Valler (1), Peter Kjeldsteen (1), Phillip Hjelmeborn Kaae (2)

1- Sintex a/s, Hobro, Denmark

2- Grundfos China Holding Co.Ltd., Suzhou, China

Abstract:

Metal powder extrusion (MPE) of AISI 904L super austenitic stainless steel makes it possible to produce complex structures with a higher corrosion resistance compared to austenitic stainless steels such as AISI 304L and AISI 316L. The initial sintering trials resulted in a porous part with low corrosion resistance. As AISI 904L is a steel with austenitic phase through the entire sintering window, densification during sintering was inhibited which resulted in the reduced corrosion resistance due to open porosities. This paper will show how to enhance densification in order to improve the corrosion resistance closer to the expected level comparable to cast and rolled material but with the shaping possibilities of MPE.

DOI:

https://doi.org/10.59499/EP246278527

Authors:

Herbert Danninger (TU Wien, Austria) Milad Hojati (TU Wien, Austria) Stefan Geroldinger (TU Wien, Austria) Raquel de Oro Calderon (TU Wien, Austria) Christian Gierl-Mayer (TU Wien, Austria) Robert Hellein (Miba Sinter Austria GmbH, Austria)

Abstract:

In ferrous powder metallurgy, replacing the common alloy elements Ni and Cu by less critical ones such as Cr, Mn and Si is both technically and economically attractive. Combining the masteralloy route with prealloying offers compositional flexibility and rapid homogenization during sintering as well as sinter hardening capability. However, the oxygen affinity of the alloy elements has to be considered. In the present study it is shown that combining starting powders prealloyed with Cr-Mo or Mo with Mn-Si masteralloys results in internal gettering, i.e. oxygen transfer from the base powder to the masteralloy, which shifts deoxidation to higher temperatures. However, the masteralloy thus promotes deoxidation of the base powder particles and consequently enhances interparticle strength even when sintering at moderate temperatures, with just slight loss of alloying effect. This shows that not only the total oxygen content but also the oxygen distribution is of relevance for the mechanical properties.

DOI:

https://doi.org/10.59499/EP256679196

Authors:

Javier Hidalgo (UCLM, Spain), Juan Alfonso Naranjo (UCLM, Spain), Juan Jimenez (UCLM, Spain), Gemma Herranz (UCLM, Spain)

Abstract:

Advents in additive technologies have enabled the production of tailormade prostheses for medical applications. This achievement is limited by the yet scarce available commercial materials. This work explores the use of fused filament fabrication for the production of a bone prosthesis of biocompatible CoCrMo alloy. One of the biggest challenges was the design of a highly loaded feedstock capable be turned into a coiling filament adapted to the FFF requirements. A suitable filament was successfully created and printing conditions optimized. A thorough study was carried out to determine debinding and sintering conditions, with particular focus on the dimensional precision, microstructure analysis and hardness test. Finally, the filament was tested for the processing of an acetabular shell for a hip prosthesis with dense|porous zones.

DOI:

https://doi.org/10.59499/WP225372298

Authors:

O. Utku Uçak (1), Marco Zago (1), Bruno Vicenzi (2), Mark James Dougan (3), Markus Schneider (4), Preben Hedegard Pedersen (5), Juergen Voglhuber (6), Ilaria Cristofolini (1)

1- University of Trento - Trento, Italy

2- EPMA, Chantilly - France

3- AMES Barcelona Sintering S.A., Barcelona – Spain

4- GKN Sintermetals GmbH, Radevormwald - Germany

5- Sintex a/s, Hobro - Denmark

6- Miba Sinter Austria GmbH, Vorchdorf - Austria

Abstract:

Design for Sintering 2 is an EPMA Club Project aimed at improving the previously developed design procedure accounting for anisotropic dimensional changes on sintering. Goal of the project is both enlarging the reference database through the fruitful cooperation of the industrial partners and investigating in depth the mechanisms responsible for anisotropic dimensional changes. This work is focused on the second part of the project, aimed at studying the influence of compaction parameters. Axi-symmetric parts characterized by different materials and geometrical parameters were produced at different green densities with different compaction strategies. Focusing the attention on the anisotropy in the compaction plane, dimensional changes were measured and evaluated, also relating them to the attainable dimensional tolerances. The influence of compaction strategy was analyzed in depth, and for the different materials and geometries the more robust process conditions for dimensional precision were highlighted.

DOI:

https://doi.org/10.59499/EP235765189

Authors:

Karim Asami (Technical University Hamburg, Germany), Dirk Herzog (Technical University Hamburg, Germany), Clarissa Klemp (Technical University Hamburg, Germany), Leon Geyer (Technical University Hamburg, Germany), Claus Emmelmann (Technical University Hamburg, Germany)

Abstract:

Filament-based material extrusion (MEX|M) presents a rapid and inexpensive alternative to e.g. metal injection molding, particularly for prototype production. The filament consists of metal powder in a plastic matrix and is melted and applied layer by layer until a so-called green body is created. These green parts are subsequently debinded and sintered at high temperatures to form a dense metal component. It is crucial to identify the material-specific and process-specific limits in order to be able to manufacture true to size. This paper therefore develops design guidelines for the MEX|M process for green part manufacturing for the widely used austenitic stainless steel AISI 316L (1.4404). Basic geometrical features such as walls, boreholes and overhangs are studied and influencing factors on the dimensional accuracy are assessed. Based on the results, recommendations for part design are presented.

DOI:

https://doi.org/10.59499/WP225371760

Authors:

Masari Facundo (1), Hernández Pascual Rebeca (2), Hernández Mayoral M. Mercedes (2), Torralba José Manuel (2,3), Campos Mónica (2)

1- Universidad Carlos III de Madrid, Leganés Madrid, Spain

2- Centre for Energy, Environmental and Technological Research (CIEMAT), Madrid, Spain

3- IMDEA Materials Institute, Getafe Madrid, Spain

Abstract:

Increasing the operating pressure and temperature of power plants is one method to increase their efficiency and hence lower CO2 emissions. The materials employed define the maximum operating parameters of a plant, ergo, it is crucial to develop new materials to raise its working conditions. Currently, alumina-forming austenitic steels), alloys vulnerable to stress corrosion cracking and irradiation swelling, are one of the materials used for temperatures about 750°C. A novel type of material is proposed, alumina-forming ferritic-martensitic steels, which have superior corrosion and swelling resistance. Advanced fabrication techniques like field-assisted sintering and selective laser melting are explored to achieve different microstructures, starting from pre-alloyed atomized powders. These microstructures were studied with SEM and EBSD, while their mechanical behaviour was observed at room temperature. Finally, corrosion tests were conducted at temperatures of 800°C for 500 hours.

DOI:

https://doi.org/10.59499/EP235765533

Authors:

Patrícia Freitas Rodrigues (University of Coimbra, Portugal) Patrícia Freitas Rodrigues (University of Coimbra, Portugal) Gonçalo Abrantes (University of Coimbra, Portugal) Bernardo Alves (University of Coimbra, Portugal) Ricardo Coelho (University of Coimbra, Portugal) Daniel Gatões (University of Coimbra, Portugal) Luís Cacho (University of Coimbra, Portugal) Andersan Paula (IME- Instituto Militar de Engenharia, Brazil) Rodolfo Batalha (ISQ - instituto de soldadura e qualidade, Portugal) João Paulo Dias (IPN - Instituto Pedro Nunes, Portugal) Sofia Ramos (University of Coimbra, Portugal) Maria Teresa Vieira (University of Coimbra, Portugal)

Abstract:

The increasing demand for advanced materials that combine mechanical strength, corrosion resistance, thermal stability, and weight reduction has driven significant progress in the development of high-performance shape memory alloys (SMAs). These materials represent a category of metallic systems with the capacity to outperform traditional superalloys in demanding environments, such as those encountered in space. This study introduces the (Ti6Al4V)50Ni36Co14 alloy (non-equiatomic low-density alloy) designed for advanced structural applications. This alloy presents a density of approximately 5.2 g|cm³, positioning it as significantly lighter than conventional NiTi-based SMAs and other low-density high-performance alloys. Beyond its reduced weight, the (Ti6Al4V)50Ni36Co14 alloy demonstrates good mechanical and functional properties. Merging these attributes with the geometric freedom given by processing via additive manufacturing, this alloy stands as strong a candidate for applications in critical environments. This work explores the printability of the (Ti6Al4V)50Ni36Co14 alloy, opening pathways for further advancements in powder metallurgy and manufacturing technologies.

DOI:

https://doi.org/10.59499/EP256767869