Euro PM2024 Proceedings

Authors:

Louise Rosenblad (1), Per-Lennart Larsson (1), Henrik Larsson (2), Hjalmar Staf (1,3)

1- Department of Engineering Mechanics, KTH Royal Institute of Technology, Sweden

2- Department of Materials Science and Engineering, KTH Royal Institute of Technology, Sweden

3- Sandvik Coromant AB, Sweden

Abstract:

During sintering, a green body of powder particles is heated to high temperatures, fusing the particles together. In cemented carbide production, the sintering process generally results in substantial densification of the material. By using a dilatometer, shrinkage during the sintering process can be measured. For a green body of lower density, early particle rearrangement has been observed. This is investigated here using different initial densities using the same powder, leading to a suggested addition to the constitutive model. The environment in the dilatometer and the sintering furnace differs, especially with respect to heating and temperature during holding. This effect can be minimized by creating robustness in the model, making it independent of the heating cycle. Here, this is done by optimizing the constitutive parameters towards four heating cycles for a specific powder.

DOI:

https://doi.org/10.59499/EP246275377

Authors:

Daniel Figueiredo (1,2), B. Guimarães (1,3), Tiago E.F. Silva (4), Cristina M. Fernandes (1), J. Paulo Davim (2)

1- R&D Department, Palbit S.A., Aveiro, Portugal

2- Department of Mechanical Engineering, University of Aveiro, Portugal.

3- Center for MicroElectroMechanical Systems, University of Minho, Guimarães, Portugal

4- INEGI, University of Porto, Porto, Portugal

Abstract:

Machining in ductile mode is usually applied for finishing precision parts of hard materials, such as cemented carbide parts, medical ceramic components or glass material applications. Thus, the study of ductile mode cutting of brittle materials has been attracting more and more efforts. The possibility of applying predominant plastic-flow cutting (ductile mode), using ultra-precision machines, in hard/brittle materials has been previously linked to the careful selection of operational conditions, regarding the brittle-to-ductile threshold. This threshold, also known as the critical depth of cut, relates with material specific properties (i.e., elastic modulus, material hardness and fracture toughness) as is widely employed in grinding processes control. In the present work, micro-milling of WC-15wt.%Co sintered samples was performed with diamond coated end mills, confirming the influence of a ductile-to-brittle threshold on the cutting regime. Critical scale effects and structure-related behaviour were also confirmed. A positive impact on machined surface quality was observed when ductile mode was applied. Scanning electron microscopy was used to evaluate the microstructure features after different machining conditions.

DOI:

https://doi.org/10.59499/EP246281747

Authors:

Tuomas Jokiaho (1), Atte Antikainen (1), Juha Lagerbom (1), Tomi Lindroos (1), Elina Huttunen-Saarivirta (1)

1- VTT Technical Research Centre of Finland Ltd., Finland

Abstract:

Nitrogen-alloyed austenitic nickel-free stainless steels (ANFSS) are known for their good corrosion resistance and mechanical properties, and stable non-magnetic nature. As long as the nitrogen content remains within certain limits, increasing the nitrogen content generally improves all the said properties. However, if the nitrogen content is increased up to a too high level, ductile-to-brittle transition may take place. The optimal nitrogen level is determined by other alloying elements that can have a role in stabilizing the austenite and increasing nitrogen solubility in the melt during manufacturing. In this research, we investigate how to control the nitrogen content of nominally Fe-16Mn-14Cr-0.27C-0.35N steel during direct energy deposition processing using the mixtures of powders representing the nominal composition and subjected to a nitriding treatment. An emphasis is placed on the corrosion and mechanical properties of the resulting alloy, which we aim to explain by the analyses of material chemical composition and microstructure.

DOI:

https://doi.org/10.59499/EP246281583

Authors:

Pavel Ctibor (1), Libor Straka (2)

1-The Czech Academy of Sciences, Institute of Plasma Physics

2-Czech Technical University, Faculty of Electrical Engineering

Abstract:

Commercial powders made of two copper oxides were compacted with spark plasma sintering (SPS). Their dielectric properties were studied in a broad range of frequencies and temperatures. Various relaxation phenomena were documented. DC resistivity was measured as well. Microstructure and phase composition were studied, and phase purity was shown for CuO, whereas Cu2O was more sensitive to carbon contamination during the SPS processing. Influence of the sintering temperature on microstructure and electrical properties was described for both materials.

DOI:

https://doi.org/10.59499/EP246276957

Authors:

Thomas Hutsch (1), Sebastian Riecker (1), Marvin Uhlig (2), James Siegenthaler (2), Matthias Mühle (2), Thomas Studnitzky (1), Johannes Trapp (1), Thomas Weißgärber (1, 3)

1- Fraunhofer IFAM Dresden, Dresden, Germany

2- Fraunhofer USA, Michigan, USA

3- TU Dresden, Dresden, Germany

Abstract:

Many requirements and applications in various industrial sectors demand high-quality finishes on parts. These finishes, whether due to tolerances or surface quality, are often challenging to achieve through additive manufacturing technologies, necessitating additional post-processing. This study aims to investigate the effect of specific surface treatments on parts produced through Sintering Based Additive Manufacturing (SBAM), such as Fused Filament Fabrication (FFF). With the premise of employing affordable post-processing methods that can potentially maintain competitive prices for the parts, the study analyzes the post-processing techniques of shot blasting and vibratory polishing on parts with different geometries. Additionally, the study examines the effect of surface treatments on part walls manufactured at various angles. The results obtained demonstrate significant improvements in surface roughness, although there is potential for them to modify the geometry and round the edges of the parts.

DOI:

https://doi.org/10.59499/EP246283253

Authors:

Alexandre Mégret (1), Loïc Prince (1), Véronique Vitry (1), Fabienne Delaunois (1)

1- Metallurgy Unit, Faculty of Engineering, University of Mons, Belgium

Abstract:

Recycling end-of-life tungsten carbide tools is important to encounter the issues linked to critical raw materials (CRM). Indeed, cobalt and tungsten have been listed as critical by the European Commission since 2011. Previous studies have characterized a recycled powder in terms of densification, microstructure, and mechanical properties, leading to interesting properties compared to conventional powders. The study of corrosion and tribological properties was not characterized although they are essential to understand the interactions between the cemented carbide tool and other materials. In this study, parts made from recycled tungsten carbide powder containing 7.5 wt.% cobalt have been sintered to evaluate their corrosion properties (open-circuit potential, polarizations…) and their tribological properties (friction coefficient, wear mechanisms…).

DOI:

https://doi.org/10.59499/EP246278304

Authors:

Mariana Pinto (1), Juliana Almeida (1), Alexandre Bastos (1), Joaquim Sacramento (2), Filipe Oliveira (1), Luís Filipe Malheiros (3), Pedro Pereira (2)

1- Department of Materials and Ceramic Engineering, CICECO, Aveiro, Portugal

2- DURIT, Metalurgia Portuguesa do Tungsténio, Lda., Portugal

3- INEGI, Department of Metallurgical and Materials Engineering, University of Porto, Portugal

Abstract:

The unfavourable corrosion behaviour of some hardmetal compositions is a main drawback for many applications. In wear parts operating in acidic media, cobalt (Co) is usually partially or totally substituted by nickel (Ni) and chromium (Cr) to increase the corrosion resistance. In hardmetals for metal forming tools, where high-volume fractions of binder are needed, the use of alternative binders, namely alloys of CoNiCr, is practically unexplored. Studying the corrosion and wear behaviour of hardmetals with high contents of these compositions is increasingly necessary for those applications. The degradation of mechanical properties induced by corrosion and wear damage that can decrease the service time of forming tools is an additional motivation for this research. This work studies the influence of binder composition in the performance of hardmetals with high binder contents in different tribological and corrosive environments, assessing the effects of partially replacing Co with simultaneous additions of Ni and Cr.

DOI:

https://doi.org/10.59499/EP246285835

Authors:

Masari F. (1), Pär Olsson (2), Peter Szakálos (2), Torralba JM (1,3), Campos M. (1)

1- Universidad Carlos III De Madrid, Leganes Madrid, Spain

2- KTH Royal Institute of Technology, Stockholm, Sweden

3- IMDEA Materials Institute, Getafe Madrid, Spain

Abstract:

The use of molten lead as a heat exchange fluid poses important critical issues, both in terms of corrosion resistance and creep resistance, due to the temperatures and structural stresses reached during operation. The objective of this work has been the investigation of the corrosion resistance and mechanical properties of new experimental compositions of alumina-forming stainless-steel candidates for these applications. The exposures to stagnant liquid lead were carried out for 500 and 1,000 hours, at temperatures of 550 and 650 °C, with controlled amounts of oxygen dissolved in the liquid lead. In comparison with the AISI 316L and T91 both tested as reference materials, the studied alloys showed highly promising corrosion behavior and mechanical properties. According to these results, the proposed steels are appropriate for components that will operate in liquid lead at elevated temperatures without corrosion, while maintaining good mechanical properties.

DOI:

https://doi.org/10.59499/EP246282505

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:

E. Frutos (1), D. Cuenca-Fernandez (1), N. Encinas (1), J. Cornide (1)

1-Surface Engineering and Nanostructured Materials Research Group, Faculty of Chemical Sciences, Complutense University of Madrid, Spain

Abstract:

Strengthened high entropy alloys (HEAs), represent a new paradigm for simultaneously achieving high strength and ductility, thereby circumventing this well-known trade-off in conventional and single-phase HEAs alloys. However, dynamic strengthening mechanisms and phase-boundary interactions during external loading remain unclear for these multiphase systems. The large fraction of phase boundary significantly impacts plastic flow in these systems. In this study, the microstructure, based on a mixture of ordered FCC/BCC ((L12, L21)/B2) phases and s phase, and small-scale mechanical behaviour has been evaluated for Fe7Cr7-xNi4+xTiMo (x=0, & 2) high entropy alloys obtained from of mechanically alloyed powders by spark plasma sintering (SPS). The use of nano and macro-indentation tests has allowed us to characterize the values of hardness and fracture toughness shown by the different (L12, L21)/(B2,s)ratios presented by high-entropy Fe-rich alloys.

DOI:

https://doi.org/10.59499/EP246280981

Authors:

Frederik Tischel (1), Vasily Ploshikhin (1)

1- University of Bremen, Airbus Endowed Chair for Integrative Simulation and Engineering of Materials and Processes, Germany

Abstract:

Sinter-based Additive Manufacturing (SBAM) methods, such as Metal Binder Jetting, bridge the high productivity rate of series production and freedom of design in additive manufacturing. However, SBAM requires a subsequent sintering process to achieve the desired material properties, resulting in distortion due to anisotropic shrinkage and creep distortion. Numerical simulation can be used to predict and compensate for this distortion. The numerical approach requires the determination of sintering strain and viscosity. These material parameters depend on many factors such as density, grain size, and temperature. Therefore, many experiments are necessary to specify all dependen-cies. In this study sintering strain and viscosity are determined as process-related, time-dependent mate-rial parameters directly from sinter dilatometer experiments of binder-jetted Ti-6Al-4V samples under different loads. The process-related material parameters vastly reduce the experimental effort. Fur-ther, the calculated sinter distortion is more accurate than the results using material parameters determined by complex material models.

DOI:

https://doi.org/10.59499/EP246278578

Authors:

Motheo Sepako (1), Thuli Mkhaliphi (1), Deborah Blaine (2)

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

2- Department of Mechanical & Mechatronic Engineering, Stellenbosch University, South Africa

Abstract:

The study investigates the influence of Laser Powder Bed Fusion (LPBF) processing parameters on the production of AISI420 stainless steel (420SS). The research aims to determine the effect of energy density, a function of laser power, scan speed, layer height and hatching spacing on the density, porosity, microstructure, and mechanical properties of the as-built 420SS. The findings reveal that as built samples with a relative density exceeding 99% utilized volumetric energy density values ranging from 79.4 to 136.6 J/mm³ and laser power above 150 W. Samples featured porosity levels below 0.01%, characterized by isolated small spherical pores with diameters < 30 μm. The microstructure displayed retained austenite phases, with additional presence of martensite phases at the melt pool boundary, attributed to the rapid cooling associated with the LPBF process. The microhardness of the as-built samples exceeded 540 HV, surpassing that reported for cast 420SS.

DOI:

https://doi.org/10.59499/EP246281798