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Authors:

Mathieu Vandecasteele (Ghent University, Belgium) Samuel Searle (KULeuven, Belgium) Domenico Iuso (University of Antwerp, Belgium) Mohsen Nourazar (Ghent University, Belgium) Ayyoub Ahar (Flanders Make, Belgium) Milad Hamidi Nasab (KULeuven, Belgium) Bey Vrancken (KULeuven, Belgium) Brian Booth (Ghent University, Belgium)

Abstract:

Porosity and deformation defects remain critical challenges to consistent, high-quality production of metallic parts using powder bed fusion (PBF). Existing state-of-the-art monitoring systems typically lack the speed required for real-time adjustments and often target only single defect types. To address these limitations, we present a high-speed, multi-modal in-situ monitoring system operating at up to 20 kHz. The system integrates dynamic region-of-interest cameras in both the visible and short-wave infrared ranges with a GPU-optimized, machine learning-based image processing pipeline. By incorporating local print context, the system accurately identifies porosity and deformation defects, enabling rapid corrective actions. Validation on 316L stainless steel samples, deliberately engineered to exhibit these defects, demonstrates Pearson correlation coefficients of 0.9493 for porosity prediction and normalized mean absolute errors of 17% for deformation detection. The results show promise for the system to be effectively used for high-speed, intra-layer closed-loop control, significantly improving the PBF process.

DOI:

https://doi.org/10.59499/EP256766760

Authors:

Oliver Schenk (RWTH Aachen University, Germany), Yuanbin Deng (RWTH Aachen University, Germany), Christoph Broeckmann (RWTH Aachen University, Germany)

Abstract:

A digital twin offers the potential of understanding and improving production processes by using numerical models. Although multiple approaches of digital twins were reported, most of them only focus on the macroscale. However, the microstructural evolution is often crucial for the application of products. For instance, the pore morphology which determines the final mechanical properties is highly affected by the compaction and sintering steps in the PM process chain. In this work, a digital twin was developed to model the compaction and sintering of water-atomized Astaloy 85Mo on a mesoscale. Scanning electron microscopy images of green body microstructures were used to train a generative adversarial network to predict the microstructure dependent on the powder particle size. The evolution of these artificial microstructures during sintering due to surface diffusion was subsequently simulated with the level-set-method. The obtained sintering kinetic agrees well with that calculated by analytical equations of sinter neck growth.

DOI:

https://doi.org/10.59499/WP225371655

Authors:

Lucia De Bortoli (University of Trento, Italy), Sasan Amirabdollahian (University of Trento, Italy), Stefano Rappo (Lincotek Medical, Italy), Matteo Perini (ProM facility, Trentino Sviluppo, Italy), Alberto Fabrizi (University of Padova, Italy), Alberto Molinari (University of Trento, Italy)

Abstract:

In the production of Co alloy | Ti alloy bimetallic components by Laser Directed Energy Deposition (L-DED), one critical issue is the microstructure of the metallurgical bonding layer produced by the melting of the substrate. This layer has a complex microstructure resulting from the mixing of the two alloys in liquid state and solidification. To investigate such a microstructure, specimens with a different content of the two alloys were produced by SPS and melted by laser, with the working parameters typical of the L-DED process. The solidified microstructure is quite complex. The SEM-EDXS and EBDS analyses show the partitioning of Ti, Co and the alloying elements in different compounds and phases depending on the relative amount of the two alloys. The tendency to cracking shows a dependence on the microstructure.

DOI:

https://doi.org/10.59499/WP225371926

Authors:

Samuel Lister (1), Simon Graham (1), James Pepper (1), Craig Simpson (1), Nigel Adams (1), Martin Jackson (1)

1- Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Building, Mappin St., Sheffield S1 3JD, UK

Abstract:

Field Assisted Sintering Technology (FAST) is a powder consolidation technique which is growing in popularity due its short, single-step processing cycles. However, as the process matures, more focus is being placed on the production of larger cylindrical samples (both axially and radially). For the process to be economical in production, there is also a drive towards multi-part processing via serial stacking/parallel processing. In both cases, there is the potential for substantial thermal gradients within the sample/stack which could negatively impact part properties. In this work the effect of the thermal gradient (axial and radial), in a stack of eight 120 mm diameter Ti-6Al-4V plates processed in series, has been studied experimentally via microstructural assessment and Vickers hardness measurements. Results were compared with the thermal profile simulated using COMSOL multi-physics modelling software. The successful production of a tall 85 mm height x 120 mm diameter sample is also demonstrated.

DOI:

https://doi.org/10.59499/EP235756151

Authors:

A.V. Shulga

National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 31 Kashirskoe Sh., Moscow 115409, Russian Federation

Abstract:

Rapidly quenched REP-powders produced by melt atomization, evidently, are characterized by the same effect of quenching rate on structure features as in traditional solid state quenching. However, the critical cooling rate, determined in the TTT diagram for melt phase transformation: crystallization is much higher than its value for suppressing austenite transformation in carbon steels. Important features of rapidly quenched powders - high dispersity of dendrites and formation of fine grain struc-ture - determine the precipitation of carbides. Direct nuclear methods of activation autoradiography on carbon, track autoradiography on boron, metallography, SEM, EDX, etc were used for investiga-tion. The structure features including the lattice parameter of a solid solution of rapidly quenched REP powders, HIP PM compacts, products of austenitic stainless steels and their traditional coun-terparts were revealed and analyzed taking into account the role of carbon and boron, precipitation of carbides, borides and effect of non-equilibrium states of investigated materials.

DOI:

https://doi.org/10.59499/EP235762945

Authors:

Andrey Shulga (National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Russia)

Abstract:

A multiscale study of boron, carbon behavior and the microstructure of PM HIP compact from high temperature Ni-based superalloy produced using PREP-powder under tensile testing at high temperature was performed. This study of boron and carbon behavior related to the microstructure of the necking and fracture zones, was carried out by direct methods track autoradiography on boron using the nuclear reaction 10B(n, a)7Li and activation autoradiography on carbon using the nuclear reaction 12C(d, n)13N, metallography, SEM, EDX, OIM methods. The formation of a mesocrack was revealed as the localization of plastic deformation before fracture, followed by a significant migration of boron and, to a lesser extent, carbon, precipitation of boride and carbide phases in the loop of maximum shear stresses for the mesocrack and in shear bands. It is important, that Intensive boron migration begins in the diffuse neck. The results revealed are explained by dynamic strain aging

DOI:

https://doi.org/10.59499/WP225367097

Authors:

Carl-Magnus Lancelot (1), Andreas Markström (1), Amer Malik (1), Quang Minh Do (1), Johan Jeppsson (1)

1- Thermo-Calc Software AB, Råsundavägen 18A, 16967 Solna, Sweden

Abstract:

Thermo-Calc has spent the last few years developing new models to predict thermophysical material properties to incorporate with CALPHAD-based materials descriptions. This foundation is currently used to extract CALPHAD-based materials data for use in dedicated Finite Element simulation codes, which usually treat material properties in a highly simplified manner. This development has laid the foundation for a completely integrated simulation tool, using the CALPHAD-based descriptions of phase equilibria and physical properties, to simulate the Additive Manufacturing process. The Additive Manufacturing module in the Thermo-Calc software was released this summer, and it gives a unique possibility to address the problem of solidification during AM, where we obtain a unified treatment of both process parameters and chemistry-dependent thermophysical properties when solving the multiphysics problem of a moving heat source that melts and solidifies metal powder. Examples are shown of the AM module applied to different material classes.

DOI:

https://doi.org/10.59499/EP235762579

Authors:

Aaron Berger (1), Ulf Ziesing (1), Santiago Benito (1), Sebastian Weber (1)

1- Chair of Materials Technology, Institute for Materials, Ruhr-University Bochum, Universitätsstrasse 150, 44801 Bochum, Germany

Abstract:

PBF-LB/M is the most suitable process for the additive manufacturing with metallic powders when it comes to complex parts with geometrical accuracy. Nevertheless, some unknown variables are present in the process. Especially the thermal conductivity adds a high degree of uncertainty due to the significant influence of the heat flux from the part to the powder bed on the resulting properties of the part. A lack of experimental data addressing the thermophysical properties of powder and a deep understanding of the influences amplifies this problem. This work presents the thermophysical properties of different steel powders commonly used in the PBF-LB/M process using a newly developed powder container. In a quantitative comparative analysis with the corresponding solid materials, it could be shown that chemical composition and microstructure play a subordinate role in the resulting heat conductivity. Instead, the powder size distribution could be identified as the main parameter determining the emerging behavior.

DOI:

https://doi.org/10.59499/EP235764023

Authors:

E. Rahimi (1), R. Birley (1), C. Fennell (1)

1- Materials Processing Institute, UK

Abstract:

The reuse of metal powder is an essential step to make the powder bed fusion (PBF) process cost-effective; therefore, understanding the capability of virgin powder is of high importance. Not all the powder is used to make parts in a PBF process. A significant proportion of the un-used powder is collected during de-powdering of the final part. This proportion and a small proportion in the waste chamber can be sieved for reuse. In this research, powder samples were reused until their flowability was below the acceptable level for re-coating. Before every process, morphology, size and flowability were evaluated using the index that was developed in the previous research presented at WorldPM2022 [1]. The index was modified based on the alloy type and reusability aspects and it has been proposed to predict the maximum reusability of virgin powder on the condition that acceptable flowability, morphological distributions and mechanical properties are maintained.

DOI:

https://doi.org/10.59499/EP235764680

Authors:

Emir Poskovic (Politecnico di Torino, Italy), Marta Ceroni (Politecnico di Torino, Italy), Fausto Franchini (Politecnico di Torino, Italy), Luca Ferraris (Politecnico di Torino, Italy), Marco Actis Grande (Politecnico di Torino, Italy)

Abstract:

Soft Magnetic Composites (SMC) comprise magnetic grains held together by an insulating layer. The widespread diffusion in the market for such materials, conventionally employed in electrical machines, is currently held back by limitations associated with material properties and processing constraints. These drawbacks are mostly related to the insulating layer employed. This contribution aims at overcoming such limitations by means of a novel surface approach. The proposed surface modification allows to coat of each particle with a nanostructured layer providing electrical insulation while also conferring additional features such as improved mechanical properties and withstanding higher treatment temperatures. In addition, the use of the proposed technology makes the layer feasible with a wide range of materials. The layer materials can be organic, inorganic or a combination of both. SMCs encompassing the developed innovative multi-functional layers have been prepared and characterized by means of surface morphology, magnetic and mechanical properties.

DOI:

https://doi.org/10.59499/WP225371894

Authors:

Felix Radtke (1), Markus Mirz (2), Klaus Dollmeier (3), Simone Herzog (1,2), Christoph Broeckmann (1,2)

1- Institute of Applied Powder Metallurgy and Ceramics (IAPK), Aachen, Germany

2- Institute for Materials Engineering in Mechanical Engineering, Aachen, Germany

3- Georgsmarienhütte Holding GmbH, Georgsmarienhütte, Germany

Abstract:

Austenitic high nitrogen steels (HNS) are the material of choice in the aerospace, medical, and electronics industry due to their unique combination of high strength, ductility and corrosion resistance. The standard manufacturing route of HNS parts comprises of pressure electroslag remelting and machining by turning or milling. In this study, the Powder Bed Fusion – Laser Beam Metal (PBF-LB/M) process was developed for the austenitic HNS grade X13CrMnMoN18-14-3. Analysis of key factors, such as porosity and manganese content, led to an optimized process window. Solution annealing ensured a fully austenitic transformation of an unintended duplex structure on cost of the fine as-built microstructure. Metallurgical analysis allowed the discussion of the effects of nitrogen content and microstructure on strength, hardness and toughness. The study achieved the desired material properties and contributes to the development of improved materials for the PBF-LB/M process.

DOI:

https://doi.org/10.59499/EP246278588

Authors:

Volker Piotter (1), Alexander Klein (1), Klaus Plewa (1), Heinz Walter (1)

1- Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM-WK), Eggenstein-Leopoldshafen, Germany

Abstract:

Although key words like digital twin, digitalization, big data etc. are dominating our ideas for the future world of manufacturing there is still the demand for particular determination of real material parameters. Simulation of Powder Injection Moulding (PIM) makes no exception, however, due to the high degree of particle filling even marginal changes of the initial values may lead to thorough differences of the results. It could be demonstrated that accidently irrelevant improvements in pvt-data determination resulted in significantly higher accurate predictions. The influence of Bagley-correction as usually applied for polymer material characterization does not lead to better simulation reliability in case of highly filled PIM feedstocks.

DOI:

https://doi.org/10.59499/EP246281624