@article{64678, abstract = {{One of the major topics in the modern automotive industry is reducing emissions and increasing the mileage range. To tackle this challenge, on the one hand, modifying the powertrain system is a possibility, and on the other hand, lightweight design offers various possibilities. Multi-Material Design (MMD) involves designing car bodies that combine different materials that require joining. Given the variety of materials, mechanical joining processes are preferred. Especially the current development of the Giga/Mega-casting process concerning aluminium casting and the subsequent mechanical joining illustrates the challenges of this material group. In car production, aluminium castings are mainly made from aluminium-silicon (AlSi) alloys. Ultimately, the alloy system's insufficient ductility leads to crack initiation during mechanical joining. Cast parts are therefore often used in areas of the car body that are exposed to high-pressure loads. For example, self-piercing riveting (SPR) is used due to its high load-bearing capacity. In this study, improved joinability is demonstrated by influencing the microstructure through tailored solidification rates and a developed heat-treatment chain strategy adapted for hypoeutectic AlSi systems. Data on microstructure, mechanical, and joining properties are used to develop a solidification-joining correlation for the SPR process across a range of Si contents and solidification rates. The purpose is to develop the ability to produce suitable aluminium castings with sufficient joinability, thereby improving versatility.}}, author = {{Neuser, Moritz and Kaimann, Pia Katharina and Stratmann, Ina and Bobbert, Mathias and Klöckner, Johann Moritz Benedikt and Mann, Moritz and Hoyer, Kay-Peter and Meschut, Gerson and Schaper, Mirko}}, journal = {{Journal of Manufacturing Processes}}, keywords = {{Mechanical joining, Aluminium, Self-piercing riveting, Casting, Microstructure, Joinability AlSi-alloys}}, publisher = {{Elsevier}}, title = {{{Solidification-joinability correlation of hypoeutectic aluminium casting alloys for self-piercing riveting (SPR)}}}, doi = {{https://doi.org/10.1016/j.jmapro.2026.02.040}}, volume = {{164}}, year = {{2026}}, } @article{65506, abstract = {{ Purpose The adoption of laser powder bed fusion (LPBF) as an additive manufacturing technique has been slow in the oil and gas (O&G) industry because of the uncertainty regarding material performance and the lack of suitable materials. The high investment and time required for LPBF development also discourage adoption. This study aims to address these concerns by developing a parameter set for a relevant material using a systematic approach to optimize the density of the printed parts with reduced experimental effort. Design/methodology/approach First, an industry-relevant Ni-based superalloy, UNS N09946, was gas-atomized to produce a powder. The powder was fully characterized to ensure successful printing. Next, a processing parameter set tailored for achieving full density was developed for UNS N09946 using a Design of Experiments (DoE) approach based on the volumetric energy density equation. Findings A model was created using Response Surface Methodology that relates laser power, scan speed and hatch distance to efficiently identify successful parameter combinations, thus reducing the number of specimens necessary for the successful manufacturing of UNS N09946 using LPBF. A part density of 99.9% was achieved using this method. Originality/value This study applies an existing experimental design method to a never-before-printed material. The reduced experimental effort through this method and lessons learned from the gas atomization process can be directly applied to other materials in and outside the O&G industry to further the adoption of LPBF as a serious manufacturing technology. }}, author = {{Wooldridge, Madison and Holzweissig, Martin and Hoyer, Kay-Peter and Schaper, Mirko}}, issn = {{1355-2546}}, journal = {{Rapid Prototyping Journal}}, pages = {{1--15}}, publisher = {{Emerald}}, title = {{{Response surface methodology for parameter development of alloy UNS N09946 processed with laser powder bed fusion}}}, doi = {{10.1108/rpj-01-2025-0039}}, year = {{2026}}, } @article{65823, abstract = {{ABSTRACT Additive manufacturing by laser powder bed fusion enables complex AlSi10Mg components but produces a heterogeneous microstructure prone to localized corrosion. In this study, hydrophobic polydimethylsiloxane (PDMS) ultrathin films, with and without an SiO ₓ interlayer attached by chemical vapor deposition (CVD), were applied for corrosion mitigation. Surface modifications were characterized by X‐ray photoelectron spectroscopy (XPS), polarization modulation–infrared reflection–absorption spectroscopy (PM‐IRRAS) and water contact angle (WCA) measurements. Electrochemical behavior was evaluated by electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), and chronoamperometry by a droplet‐cell approach. Atmospheric corrosion processes simulating marine corrosion were monitored by optical microscopy. Spectroscopic analyses confirm successful PDMS attachment. Electrochemical measurements reveal reduced corrosion current densities by one magnitude, suppressed pitting activity, and anodic shifts of the pitting potential. The SiO ₓ ‐CVD + PDMS bilayer exhibits the highest resistance to atmospheric corrosion. }}, author = {{Prüßner, Tim and Hoyer, Kay-Peter and Buitkamp, Nadine and Grundmeier, Guido}}, issn = {{0947-5117}}, journal = {{Materials and Corrosion}}, publisher = {{Wiley}}, title = {{{Atmospheric Corrosion Protection of LPBF Manufactured AlSi10Mg by Combining SiO x ‐CVD and PDMS Grafting}}}, doi = {{10.1002/maco.70163}}, year = {{2026}}, } @article{66791, abstract = {{Abstract Roller shells of twin-roll-caster (TRC) are subjected to wear and tear due to their usage in harsh casting and forming conditions. Therefore, their durability is significantly shortened by the need to refinish the surface to reinstate suitable surface parameters for rolling and casting thin aluminium or other metal strips. To extend the lifetime of the rollers, a solution to repair the surface has to be found. Due to the constraints in the TRC process, most surface repair processes are not suitable, too complex (multistage heat treatment) or too expensive. Hence, high velocity oxygen fuel (HVOF) is a viable solution for applying a repair surface onto worn-down rollers, as this process is well-known and understood, already established in the industry, and potentially possible to integrate into the TRC process environment without disassembling the roller from the machine.}}, author = {{Lauth, Martin and Hoyer, Kay-Peter and Voswinkel, Dietrich and Gräfen, Winfried and Schaper, Mirko}}, issn = {{2194-1831}}, journal = {{HTM Journal of Heat Treatment and Materials}}, number = {{4}}, pages = {{166--178}}, publisher = {{Walter de Gruyter GmbH}}, title = {{{Adapting the HVOF Process for the Repair of Twin-Roll-Caster Shells}}}, doi = {{10.1515/htm-2026-0017}}, volume = {{81}}, year = {{2026}}, } @article{66790, abstract = {{Abstract Roller shells of twin-roll-caster (TRC) are subjected to wear and tear due to their usage in harsh casting and forming conditions. Therefore, their durability is significantly shortened by the need to refinish the surface to reinstate suitable surface parameters for rolling and casting thin aluminium or other metal strips. To extend the lifetime of the rollers, a solution to repair the surface has to be found. Due to the constraints in the TRC process, most surface repair processes are not suitable, too complex (multistage heat treatment) or too expensive. Hence, high velocity oxygen fuel (HVOF) is a viable solution for applying a repair surface onto worn-down rollers, as this process is well-known and understood, already established in the industry, and potentially possible to integrate into the TRC process environment without disassembling the roller from the machine.}}, author = {{Lauth, Martin and Hoyer, Kay-Peter and Voswinkel, Dietrich and Gräfen, Winfried and Schaper, Mirko}}, issn = {{2194-1831}}, journal = {{HTM Journal of Heat Treatment and Materials}}, number = {{4}}, pages = {{166--178}}, publisher = {{Walter de Gruyter GmbH}}, title = {{{Adapting the HVOF Process for the Repair of Twin-Roll-Caster Shells}}}, doi = {{10.1515/htm-2026-0017}}, volume = {{81}}, year = {{2026}}, } @article{58378, abstract = {{Abstract The contact between two partners can be determined using experimental or numerical methods. For the validation of numerical simulations, appropriate experiments and material models of the contact partners are required. Paper in combination with carbon paper can be used in experiments to detect the area of contact between contact partners. A simplified linear-elastic material model of paper for compression in the thickness direction was developed. To evaluate the material model, it was applied to an exemplary wheel-rail contact situation.}}, author = {{Stratmann, Ina and Hoyer, Kay-Peter and Schindler, Christian}}, issn = {{0742-4787}}, journal = {{Journal of Tribology}}, pages = {{1--19}}, publisher = {{ASME International}}, title = {{{Developing a simplified linear-elastic material model for carbon paper applied in the rough rail-wheel contact}}}, doi = {{10.1115/1.4067696}}, year = {{2025}}, } @inproceedings{58878, author = {{Buczek, Moritz and Duffe, Tobias and Kullmer, Gunter and Tews, Karina and Teutenberg, Dominik and Meschut, Gerson}}, booktitle = {{25. Kolloquium: Gemeinsame Forschung in der Klebtechnik}}, location = {{Köln}}, title = {{{Bruchmechanisches Schnittebenenkonzept zur lebensdauergerechten Auslegung von hyperelastischen Klebverbindungen bei multiaxialen und variablen Belastungsamplituden}}}, year = {{2025}}, } @article{59872, abstract = {{Lightweight design is a driving concept in modern automotive engineering to minimize resource consumption over a vehicle's lifecycle through multi-material design, which relies on the use of joining techniques in car body fabrication. Multi-material design and the increasing trend towards producing large structural components using the megacasting process pose considerable challenges, particularly in the mechanical joining of aluminium-silicon (AlSi) castings. These castings typically exhibit low ductility and are prone to cracking when mechanically joined. Based on the excellent castability of hypoeutectic AlSi alloys, these are applied in sand casting and die casting as well as in megacasting. With a silicon content between 7 wt% and 12 wt%, these AlSi-alloys have a plate-like silicon phase that initiates cracks during mechanical joining. To enhance the joinability of castings, the research hypothesis is that improved solidification conditions enable a significant modification in the microstructure and therefore, increase the mechanical properties. During the manufacture of the castings using the sand casting process, the solidification conditions within the structural elements are varied to modify the microstructure to obtain castings with graded microstructure. The castings are evaluated using mechanical, microstructural and joining testing methods and finally, a microstructure-joinability correlation is established.}}, author = {{Neuser, Moritz and Schlichter, Malte Christian and Hoyer, Kay-Peter and Bobbert, Mathias and Meschut, Gerson and Schaper, Mirko}}, journal = {{44th Conference of the International Deep Drawing Research Group (IDDRG 2025)}}, keywords = {{Joining, Casting, Self-pierce riveting, Aluminium casting alloy}}, location = {{Lissabon (Portugal)}}, title = {{{Mechanical joinability of microstructurally graded structural components manufactured from hypoeutectic aluminium casting alloys}}}, doi = {{10.1051/matecconf/202540801081}}, volume = {{408}}, year = {{2025}}, } @article{62166, author = {{Prüßner, Tim and Hoyer, Kay-Peter and Buitkamp, Nadine and Vieth, Pascal and Grundmeier, Guido}}, issn = {{0254-0584}}, journal = {{Materials Chemistry and Physics}}, publisher = {{Elsevier BV}}, title = {{{Surface functionalisation of additively manufactured AlSi10Mg by organophosphonic acid and PDMS grafting}}}, doi = {{10.1016/j.matchemphys.2025.131758}}, volume = {{349}}, year = {{2025}}, } @inproceedings{62725, abstract = {{Aluminium-Silizium-Legierungen (AlSi) werden insbesondere bei der gießtechnischen Herstellung von Leichtbaukomponenten für Fahrzeuge verwendet. Dieses Legierungssystem hat hervorragende Gießeigenschaften bei gleichzeitig akzeptablen mechanischen Eigenschaften. Aufgrund des hohen Silizium-(Si)-Gehaltes, wodurch die Volumenkontraktion im Phasenübergang von flüssig-fest nahezu unterbunden wird, neigen AlSi-Legierungen dazu, feinere oder gröbere Si-Platten bei unterschiedlichen Erstarrungsgeschwindigkeiten zu bilden. Um die mechanischen Eigenschaften zu verbessern, werden dem Legierungssystem in der Schmelzphase entweder Natrium (Na) oder Strontium (Sr) zugesetzt. Dies hat zur Folge, dass sich eine fein lamellare Si-Morphologie bei der Erstarrung ausbildet; dies kann ebenfalls durch hohe Erstarrungsgeschwindigkeiten erreicht werden. Ein nachfolgendes Lösungsglühen bewirkt eine Sphäroidisierung der Si-Partikel und dient der Steigerung der Duktilität. Aktuell fehlen fundierte Erkenntnisse zur Ausprägung der Si-Morphologie in Abhängigkeit der Erstarrungsgeschwindigkeit oder infolge einer Wärmebehandlung. Vor diesem Hintergrund werden in dieser Studie verschiedene Behandlungsparameter in Bezug auf das Einformverhalten der Si-Partikel mit einem bildauswertenden Verfahren evaluiert sowie unter Bezug auf verschiedene chemische Zusammensetzungen miteinander korreliert.}}, author = {{Neuser, Moritz and Cichon, Gerrit and Hoyer, Kay-Peter and Schaper, Mirko}}, booktitle = {{Bildauswertendes Verfahren zur Evaluierung der Mikrostruktur von AlSi-Systemen}}, isbn = {{978-3-88355-454-9}}, keywords = {{Bildauswertendes Verfahren, Mikrostrukturanalyse, AlSi-System, Si-Morphologie}}, location = {{Dresden}}, pages = {{454 -- 459}}, publisher = {{Deutsche Gesellschaft für Materialkunde (DGM)}}, title = {{{Bildauswertendes Verfahren zur Evaluierung der Mikrostruktur von AlSi-Systemen}}}, volume = {{43}}, year = {{2025}}, } @article{63072, abstract = {{Titanium alloys are widely employed for biomedical implants due to their high strength, biocompatibility, and corrosion resistance, yet their lack of intrinsic antibacterial activity remains a major limitation. Incorporating copper, an antibacterial and β-stabilising element, offers a promising strategy to enhance implant performance. This study investigates Ti-6Al-7Nb modified with 1–9 wt.% Cu via in situ alloying during metal-based laser powder bed fusion (PBF-LB/M), with the aim of assessing processability, microstructural evolution, and mechanical properties. Highly dense samples (>99.9%) were produced across all Cu levels, though chemical homogeneity strongly depended on processing parameters. Increasing Cu content promoted β-phase stabilisation, Ti2Cu precipitation, and pronounced grain refinement. Hardness and yield strength increased nearly linearly with Cu addition, while ductility decreased sharply at ≥5 wt.% Cu due to intermetallic formation, hot cracking, and brittle fracture. These results illustrate both the opportunities and constraints of rapid alloy screening via PBF-LB/M. Overall, moderate Cu additions of 1–3 wt.% provide the most favourable balance between mechanical performance, manufacturability, and potential antibacterial functionality. These findings provide a clear guideline for the design of Cu-functionalised titanium implants and demonstrate the efficiency of in situ alloy screening for accelerated materials development.}}, author = {{Steinmeier, Paul and Hoyer, Kay-Peter and Lopes Dias, Nelson Filipe and Zielke, Reiner and Tillmann, Wolfgang and Schaper, Mirko}}, issn = {{2073-4352}}, journal = {{Crystals}}, keywords = {{Biomaterial, In Situ Alloying, Titanium, Additive Manufacturing}}, number = {{12}}, publisher = {{MDPI AG}}, title = {{{In Situ Alloying of Ti-6Al-7Nb with Copper Using Laser Powder Bed Fusion}}}, doi = {{10.3390/cryst15121053}}, volume = {{15}}, year = {{2025}}, } @techreport{63209, abstract = {{Die DFG-Projekte AddFeRo-PM (406108415) und AddFeRo-SR (465089065) untersuchten die Potenziale des LB-PBF/M-Verfahrens zur Herstellung von Rotoren für unterschiedliche elektrische Maschinen. Im interdisziplinären Ansatz wurden Materialentwicklung und mechanische sowie elektromagnetische Optimierung verbunden. Im Projekt „AddFeRo-PM“ wurde der Rotor einer permanentmagneterregten Synchron- maschine (PMSM) untersucht. FeSi erwies sich als geeignete Legierung, konnte aber wegen Spannungsrissen nur bis zu 3 % Siliziumanteil (kurz: FeSi3) verarbeitet werden. Mechanische und elektromagnetische Untersuchungen ermöglichten eine 3D-Optimierung der Rotorgeometrie und -struktur. Der Demonstrator wurde additiv gefertigt und zeigt Leicht-baupotenziale sowie reduzierte Drehmomentwelligkeit. Im Folgeprojekt „AddFeRo-SR“ kam eine Hochtemperatur-Bauraumheizung (HTBH) zum Einsatz, die FeSi mit 6,5 % Siliziumanteil verarbeitbar machte, welches bessere elektro- magnetische Eigenschaften bietet. Sie wurde bei einer Synchron-Reluktanzmaschine (SynRM) getestet. Eine hybride Rotorfertigung erwies sich jedoch aufgrund von HTBH-Einschränkungen als ungeeignet, weshalb eine einteilige Fertigung mit FeSi3 umgesetzt wurde. Experimente bestätigten vergleichbare Betriebsergebnisse zur konventionellen Fertigung bei reduzierter Rotormasse. Zusätzlich wurde eine Methodik entwickelt, um additive Verfahren als Ergänzung zur konventionellen Fertigung zu integrieren. Beide Projekte zeigen das Potenzial additiver Fertigung für Leichtbau und Wirkungsgradsteigerung im Elektromaschinenbau und bieten wertvolle Grundlagen für industrielle Anwendungen.}}, author = {{Haase, Michael and Behrendt, Marius and Hengsbach, Florian and Kunnathully Sathees Kumar, Vinay and Magerkohl, Sebastian and Magyar, Balázs and Ponick, Bernd and Schaper, Mirko and Zimmer, Detmar}}, keywords = {{Additive Fertigung, Elektromotor, Leichtbau, Synchronmotor, DFG}}, publisher = {{Technische Informationsbibliothek}}, title = {{{Additive Fertigung im Elektromaschinenbau: Erforschung von Potentialen der additiven Fertigung in Rotoren permanentmagneterregter Synchronmaschinen}}}, doi = {{10.34657/26753}}, year = {{2025}}, } @article{58133, author = {{Pramanik, Sudipta and Mileaege, Dennis and Andreiev, Anatolii and Hoyer, Kay-Peter and Schaper, Mirko}}, issn = {{1059-9495}}, journal = {{Journal of Materials Engineering and Performance}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Effect of Compression Rate and Pore Size Distribution on the Compression Behavior of Additively Manufactured Bio-inspired Fe3Si Microporous Material}}}, doi = {{10.1007/s11665-024-10618-z}}, year = {{2025}}, } @inbook{58950, author = {{Braun, Marcel Patrick Klaus and Grydin, Olexandr and Hoyer, Kay-Peter and Schaper, Mirko}}, booktitle = {{The Minerals, Metals & Materials Series}}, isbn = {{9783031810602}}, issn = {{2367-1181}}, location = {{LAs Vegas, USA}}, publisher = {{Springer Nature Switzerland}}, title = {{{Precipitation Hardening in the Magnesium–Zinc–Calcium Alloy System}}}, doi = {{10.1007/978-3-031-81061-9_12}}, year = {{2025}}, } @inproceedings{59154, abstract = {{Abstract. Lightweight design is one of the central topics of the automotive industry since reducing mass can save emissions over the entire life cycle of a component. Nowadays, vehicle structures usually consist of a multi-material design, which poses the additional challenge of joining these different materials. Mechanical joining is the most common way of joining different types of materials. Cast aluminium alloys of the AlSi system have a low ductility, which causes cracks during the mechanical joining process in the joint. One research approach is to achieve a fine microstructure by influencing the solidification rate since this results in increased mechanical properties, specifically the elongation at fracture and yield strength. A very fine microstructure can be achieved by utilizing Twin-roll casting (TRC) which is a continuous casting process in which high solidification rates of more than 100 K/s occur. In this study, the hypoeutectic cast aluminium alloy AlSi9 is processed in the TRC process using copper rollers. The cast strips are investigated regarding the microstructure-property correlation. A variation of the roller materials and cooling conditions allows for an increase in the solidification rate, whereby a defined, fine microstructure can be achieved, which enhances the mechanical properties of the hypoeutectic aluminium casting alloys.}}, author = {{Neuser, Moritz and Hoyer, Kay-Peter and Schaper, Mirko}}, booktitle = {{Materials Research Proceedings}}, issn = {{2474-395X}}, publisher = {{Materials Research Forum LLC}}, title = {{{Processing of the hypoeutectic AlSi9 alloy with twin-roll casting by using copper shells}}}, doi = {{10.21741/9781644903551-26}}, volume = {{52}}, year = {{2025}}, } @inproceedings{59155, abstract = {{Abstract. Twin-Roll-Casting (TRC) is an energy- and cost-efficient process to produce near-net-shape aluminum strips. Due to the high affinity of molten aluminum to steel surfaces, those rollers show signs of wear throughout the rolling campaign. This leads to the necessity of restoring the worn surfaces to suitable parameters. The easiest way is to grind the surface till all superficial defects are omitted. However, the thickness of the roller is not endless, therefore the rollers must be replaced after a certain amount of surface reconditioning. This ultimately leads to the non-usability of the roller. This research shows a route to recondition the surface including the possibility of renewing worn-down surfaces with an energy- and cost-efficient high-velocity oxygen fuel (HVOF) treatment with subsequent grinding to the desired initial surface parameters.}}, author = {{Lauth, Martin and Hoyer, Kay-Peter and Schaper, Mirko and Gräfen, Winfried}}, booktitle = {{Materials Research Proceedings}}, issn = {{2474-395X}}, publisher = {{Materials Research Forum LLC}}, title = {{{Cost-effective repair solution for twin-roll-caster rollers}}}, doi = {{10.21741/9781644903551-5}}, volume = {{52}}, year = {{2025}}, } @article{60851, author = {{Ghosh, Koustav and Milaege, Dennis and Steinmeier, Paul and Schaper, Mirko and Hoyer, Kay-Peter and Pramanik, Sudipta}}, issn = {{1059-9495}}, journal = {{Journal of Materials Engineering and Performance}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Effect of Strain Rate on the Deformation Behavior and Energy Absorption Characteristics of LPBF-Processed Ti2448 Microarchitectured Lattice Structures}}}, doi = {{10.1007/s11665-025-11669-6}}, year = {{2025}}, } @inproceedings{65172, abstract = {{Abstract. The process of joining is used in numerous sectors of the manufacturing industry, where constructions composed of individual components or metal sheets are combined to form complex structures. A straightforward and pervasive approach for joining materials of disparate natures and coated surfaces is clinching. During the clinching process, plastic deformation, residual stresses and damage are introduced into the joint. Due to time-varying service loads cracks can initiate and propagate in the vicinity of the joint which limits the lifetime of the clinched structure. In order to prevent those damage cases, it is crucial to perform fracture mechanical evaluation of cracks in the joint region. Therefore, this publication deals with the question of how plastic deformation, residual stresses and damage need to be considered for the assessment of a crack. For this purpose, simple substitute models are employed to illustrate the principles based on the clinching application example.}}, author = {{Weiß, Deborah and Duffe, Tobias and Joy, Tintu David and Kullmer, Gunter}}, booktitle = {{Materials Research Proceedings}}, issn = {{2474-395X}}, publisher = {{Materials Research Forum LLC}}, title = {{{Consideration of residual stresses and damage in the fracture mechanical investigation of mechanically joined structures}}}, doi = {{10.21741/9781644903551-28}}, volume = {{52}}, year = {{2025}}, } @misc{63764, author = {{Weiß, Deborah and Krome, Sven and Duffe, Tobias and Kullmer, Gunter and Ostwald, Richard}}, publisher = {{LibreCat University}}, title = {{{Experimentelle Ermittlung von Rissablenkungswinkeln bei außerphasiger Mixed-Mode-Belastung mittels einer neuartigen Probengeometrie}}}, doi = {{https://doi.org/10.48447/BR-2025-490}}, year = {{2025}}, } @misc{65221, author = {{Kullmer, Gunter and Weiß, Deborah and Duffe, Tobias and Schramm, Britta and Ostwald, Richard}}, publisher = {{LibreCat University}}, title = {{{BESCHREIBUNG DES R- UND DES TEMPERATUREINFLUSSES SOWIE DES EINLAUFVERHALTENS BEI EXPERIMENTELL BESTIMMTEN RISSFORTSCHRITTSKURVEN MIT DEM EXPONENTIALANSATZ}}}, doi = {{https://doi.org/10.48447/BR-2025-492}}, year = {{2025}}, }