@misc{IsrarBuhlBambach, author = {Israr, Rameez and Buhl, Johannes and Bambach, Markus}, title = {A study on power-controlled wire-arc additive manufacturing using a data-driven surrogate model}, series = {The International Journal of Advanced Manufacturing Technology}, volume = {177}, journal = {The International Journal of Advanced Manufacturing Technology}, number = {7-8}, issn = {1433-3015}, doi = {10.1007/s00170-021-07358-y}, pages = {2133 -- 2147}, abstract = {Wire-arc additive manufacturing (WAAM) provides an alternative for the production of various metal products needed in medium to large batch sizes due to its high deposition rates. However, the cyclic heat input in WAAM may cause local overheating. To avoid adverse effects on the performance of the part, interlayer dwelling and active cooling are used, but these measures increase the process time. Alternatively, the temperature during the WAAM process could be controlled by optimizing the welding power. The present work aims at introducing and implementing a novel temperature management approach by adjusting the weld-bead cross-section along with the welding power to reduce the heat accumulation in the WAAM process. The temperature evolution during welding of weld beads of different cross-sections is investigated and a database of the relation between optimal welding power for beads of various sizes and different pre-heating temperatures was established. The numerical results are validated experimentally with a block-shaped geometry. The results show that by the proposed method, the test shape made was welded with lower energy consumption and process time as compared to conventional constant-power WAAM. The proposed approach efficiently manages the thermal input and reduces the need for pausing the process. Hence, the defects related to heat accumulation might be reduced, and the process efficiency increased.}, language = {en} } @misc{NguyenBuhlIsraretal., author = {Nguyen, Lam and Buhl, Johannes and Israr, Rameez and Bambach, Markus}, title = {Analysis and compensation of shrinkage and distortion in wire-arc additive manufacturing of thin-walled curved hollow sections}, series = {Additive Manufacturing}, volume = {Vol. 47}, journal = {Additive Manufacturing}, issn = {2214-8604}, doi = {10.1016/j.addma.2021.102365}, language = {en} } @misc{SzczepańskiBambachJenschetal., author = {Szczepański, Łukasz and Bambach, Markus and Jensch, Felix and Ambroziak, Andrzej and Kurzynowski, Tomasz}, title = {Structural investigations of Fe-Zr-Si-Cu metallic glass with low glass-forming ability produced in laser powder bed fusion technology}, series = {Materials \& Design}, volume = {Vol. 210}, journal = {Materials \& Design}, issn = {0264-1275}, doi = {https://doi.org/10.1016/j.matdes.2021.110112}, pages = {7}, language = {en} } @misc{DeillonJenschPalmetal., author = {Deillon, L{\´e}a and Jensch, Felix and Palm, Frank and Bambach, Markus}, title = {A new high strength Al-Mg-Sc alloy for laser powder bed fusion with calcium addition to effectively prevent magnesium evaporation}, series = {Journal of materials processing technology}, volume = {Vol. 300}, journal = {Journal of materials processing technology}, issn = {1873-4774}, doi = {10.1016/j.jmatprotec.2021.117416}, pages = {10}, language = {en} } @misc{PetrikSydowBambach, author = {Petrik, Jan and Sydow, Benjamin and Bambach, Markus}, title = {Beyond parabolic weld bead models: AI-based 3D reconstruction of weld beads under transient conditions in wire-arc additive manufacturing}, series = {Journal of Materials Processing Technology}, volume = {302 (2022)}, journal = {Journal of Materials Processing Technology}, doi = {10.1016/j.jmatprotec.2021.117457}, pages = {16}, language = {en} } @misc{MaqboolMaassBuhletal., author = {Maqbool, Fawad and Maaß, Fabian and Buhl, Johannes and Hahn, Marlon and Hajavifard, Ramin and Walther, Frank and Tekkaya, A. Erman and Bambach, Markus}, title = {Targeted residual stress generation in single and two point incremental sheet forming (ISF)}, series = {Archive of Applied Mechanics}, volume = {91}, journal = {Archive of Applied Mechanics}, number = {8}, issn = {1432-0681}, doi = {10.1007/s00419-021-01935-z}, pages = {3465 -- 3487}, language = {en} } @misc{AfzalHajavifardBuhletal., author = {Afzal, Muhammad Junaid and Hajavifard, Ramin and Buhl, Johannes and Walther, Frank and Bambach, Markus}, title = {Influence of process parameters on the residual stress state and properties in disc springs made by incremental sheet forming (ISF)}, series = {Forschung im Ingenieurwesen}, volume = {85}, journal = {Forschung im Ingenieurwesen}, number = {3}, issn = {1434-0860}, doi = {10.1007/s10010-021-00491-w}, pages = {783 -- 793}, language = {en} } @misc{BambachHertyImran, author = {Bambach, Markus and Herty, Michael and Imran, Muhammad}, title = {Feedback stabilization of forming processes}, series = {arXiv}, journal = {arXiv}, language = {en} } @misc{AbasAlkahtaniKhalidetal., author = {Abas, Muhammad and Alkahtani, Mohammed and Khalid, Qazi Salman and Hussain, Ghulam and Abidi, Mustufa Haider and Buhl, Johannes}, title = {Parametric Study and Optimization of End-Milling Operation of AISI 1522H Steel Using Definitive Screening Design and Multi-Criteria Decision-Making Approach}, series = {Materials}, volume = {15}, journal = {Materials}, number = {12}, issn = {1996-1944}, doi = {10.3390/ma15124086}, language = {en} } @misc{BesongBuhlBambach, author = {Besong, Lemopi Isidore and Buhl, Johannes and Bambach, Markus}, title = {Increasing formability in hole-flanging through the use of punch rotation based on temperature and strain rate dependent forming limit curves}, series = {International Journal of Material Forming}, volume = {15}, journal = {International Journal of Material Forming}, number = {3}, issn = {1960-6214}, doi = {10.1007/s12289-022-01684-6}, pages = {1 -- 21}, language = {en} } @misc{BambachGersterHertyetal., author = {Bambach, Markus and Gerster, Stephan and Herty, Michael and Imran, Muhammad}, title = {Feedback control for random, linear hyperbolic balance laws}, series = {International Journal for Uncertainty Quantification}, volume = {12}, journal = {International Journal for Uncertainty Quantification}, number = {2}, issn = {2152-5099}, doi = {10.1615/Int.J.UncertaintyQuantification.2021037183}, pages = {81 -- 104}, language = {en} } @misc{IsrarBuhlHaerteletal., author = {Israr, Rameez and Buhl, Johannes and H{\"a}rtel, Sebastian and Bambach, Markus}, title = {Reinforcement of Tooling Using Residual Stresses Generated by Cladding by Arc Welding}, series = {Metals}, volume = {12}, journal = {Metals}, number = {6}, issn = {2075-4701}, doi = {10.3390/met12060984}, pages = {30}, abstract = {Cladding is typically used to protect components from wear and corrosion while also improving the aesthetic value and reliability of the substrate. The cladding process induces significant residual stresses due to the temperature difference between the substrate and the clad layer. However, these residual stresses could be effectively utilized by modifying processes and geometrical parameters. This paper introduces a novel methodology for using the weld-cladding process as a cost-effective alternative to various existing reinforcement techniques. The numerical analyses are performed to maximize the reinforcement of a cylindrical tool. The investigation of how the weld cladding develops compressive stresses on the specimen in response to a change in the weld beads and the welding sequence is presented. For the benchmark shape, experimental verification of the numerical model is performed. The influence of the distance between the weld beads and the effect of the tool diameter is numerically investigated. Furthermore, the variation in compressive stresses due to temperature fluctuations during the extrusion process has been evaluated. The results showed that adequate compressive stresses are generated on the welded parts through the cladding process after cooling. More compressive stresses are induced in the tool as the cross-section of the weld bead is increased. Furthermore, keeping a gap between the adjacent beads improves tool reinforcement. Hence, the targeted reinforcement of the substrate can be achieved by optimizing the welding sequence and process parameters.}, language = {en} } @misc{SydowJhanjiHaelsigetal., author = {Sydow, Benjamin and Jhanji, Avantika and H{\"a}lsig, Andr{\´e} and Buhl, Johannes and H{\"a}rtel, Sebastian}, title = {The Benefit of the Process Combination of Wire Arc Additive Manufacturing (WAAM) and Forming—A Numerical and Experimental Study}, series = {Metals}, volume = {12}, journal = {Metals}, number = {6}, issn = {2075-4701}, doi = {10.3390/met12060988}, pages = {13}, language = {en} } @misc{EmdadiBolzBuhletal., author = {Emdadi, Aliakbar and Bolz, Sebastian and Buhl, Johannes and Weiß, Sabine and Bambach, Markus}, title = {Laser Powder Bed Fusion Additive Manufacturing of Fe3Al-1.5Ta Iron Aluminide with Strengthening Laves Phase}, series = {Metals}, volume = {12}, journal = {Metals}, number = {6}, issn = {2075-4701}, doi = {10.3390/met12060997}, language = {en} } @misc{ErtugrulHaelsigHenseletal., author = {Ertugrul, G{\"o}khan and H{\"a}lsig, Andre and Hensel, Jonas and Buhl, Johannes and H{\"a}rtel, Sebastian}, title = {Efficient Multi-Material and High Deposition Coating including Additive Manufacturing by Tandem Plasma Transferred Arc Welding for Functionally Graded Structures}, series = {Metals}, volume = {12}, journal = {Metals}, number = {8}, issn = {2075-4701}, doi = {10.3390/met12081336}, pages = {1 -- 17}, language = {en} } @misc{OmairAlkahtaniAyazetal., author = {Omair, Muhammad and Alkahtani, Mohammed and Ayaz, Kashif and Hussain, Ghulam and Buhl, Johannes}, title = {Supply Chain Modelling of the Automobile Multi-Stage Production Considering Circular Economy by Waste Management Using Recycling and Reworking Operations}, series = {Sustainability}, volume = {14}, journal = {Sustainability}, number = {22}, issn = {2071-1050}, doi = {10.3390/su142215428}, abstract = {The supply chain management plays a crucial role in delivering products from a supplier, through the manufacturer, distributors, and retailers to the targeted customers. The lifecycle of the products can be ended at any stage due to imperfect quality or waste, which are typically not managed well for a good price. This product's life can be extended and increased with the use of the circular economy for the value addition processes which turn the waste into byproducts, which can be sold with maximum profit. The automobile industry is associated with various other small industries and is very significant for the economy at the local, national, and international levels. However, the industry also requires sustainable development in its supply chain management, gained by introducing the circular economy concept to manage and reduce the generated waste. The consumption of carbon fiber-reinforced composites (CFRCs) in the manufacturing of numerous automotive parts has acquired immense attention this decade, but the process also generates imperfect products (waste). The proposed model is based on a mathematical formulation to manage imperfect production by reworking and recycling, where the former is required to re-add value to the proportion of the rejected parts, and the latter is to recycle the remaining scrap into useful products by using a circular economy. The outsourcing operation is also added to provide an optimal level of inventory and lot sizing for minimizing the total cost of the supply chain management. Data from the automobile part industry are tested to provide the practical implications of the proposed SCM mathematical model. Sensitivity analysis is performed to understand the significance level of the individual parameters affecting the objective function, i.e., the total cost of the SCM. The results show a meaningful insight for the managers to obtain the benefits of the circular economy in multi-stage automobile part production for sustainable and resilient supply chain management.}, language = {en} } @misc{HussainAlkahtaniAlsultanetal., author = {Hussain, Ghulam and Alkahtani, Mohammed and Alsultan, Marwan and Buhl, Johannes and Gupta, Munish Kumar}, title = {Chip formation, cutting temperature and forces measurements in hard turning of Gcr15 under the influence of PcBN chamfering parameters}, series = {Measurement}, volume = {Vol. 204}, journal = {Measurement}, issn = {1873-412X}, doi = {10.1016/j.measurement.2022.112130}, language = {en} } @misc{HirtlerUensalBuhletal., author = {Hirtler, Markus and {\"U}nsal, Ismail and Buhl, Johannes and Bambach, Markus}, title = {Investigation of quench hardening behavior of directed energy deposited 22MnB5 steel for local reinforcement of hot stamping parts}, series = {CIRP Journal of Manufacturing Science and Technology}, volume = {Vol. 39}, journal = {CIRP Journal of Manufacturing Science and Technology}, issn = {1878-0016}, doi = {10.1016/j.cirpj.2022.08.003}, pages = {223 -- 231}, language = {en} } @misc{BesongBuhlHaerteletal., author = {Besong, Lemopi Isidore and Buhl, Johannes and H{\"a}rtel, Sebastian and Bambach, Markus}, title = {Increasing the Forming Limits in Hole Flanging of Dual-Phase (DP) 1000 Steel Using Punch Rotation}, series = {Key Engineering Materials}, volume = {Vol. 926}, journal = {Key Engineering Materials}, issn = {1662-9795}, doi = {10.4028/p-06y8un}, pages = {717 -- 723}, language = {en} } @misc{AfzalBuhl, author = {Afzal, Muhammad Junaid and Buhl, Johannes}, title = {Numerical Study to Promote the Residual Stresses Development during ISF Process with Improvement in Two Point Incremental Die Forming}, series = {Key Engineering Materials}, volume = {Vol. 926}, journal = {Key Engineering Materials}, issn = {1662-9795}, pages = {752 -- 759}, language = {en} } @misc{ImranDeillonSizovaetal., author = {Imran, Muhammad and Deillon, L{\´e}a and Sizova, Irina and Neirinck, Bram and Bambach, Markus}, title = {Process optimization and study of the co-sintering behaviour of Cu-Ni multi-material 3D structures fabricated by spark plasma sintering (SPS)}, series = {Materials \& Design}, volume = {Vol. 223}, journal = {Materials \& Design}, issn = {0264-1275}, doi = {10.1016/j.matdes.2022.111210}, language = {en} } @misc{FischerGruegerWoll, author = {Fischer, Tim Sebastian and Gr{\"u}ger, Lennart and Woll, Ralf}, title = {Additive Manufacturing: A Step-by-Step Guide}, series = {Industry 4.0 Science}, journal = {Industry 4.0 Science}, number = {1}, issn = {2942-6162}, doi = {10.30844/I4SE.23.1.80}, pages = {80 -- 88}, abstract = {New technologies have enabled additive manufacturing to construct components layer by layer using 3D model data. Machinery requirements for this are minimal, entailing only a welding device for energy input and a guiding machine to shape the component. Though there are clear benefits to the process, such as the cost-effective technology and high deposition rates, the complex interactions involved must receive due consideration.}, language = {en} } @misc{GruegerFischerWolletal., author = {Gr{\"u}ger, Lennart and Fischer, Tim Sebastian and Woll, Ralf and Buhl, Johannes}, title = {Absicherung von Risiken beim Prozess des Wire Arc Additive Manufacturing}, series = {Industry 4.0 Science}, volume = {2024}, journal = {Industry 4.0 Science}, number = {1}, issn = {2942-6154}, doi = {10.30844/I4SD.24.1.63}, pages = {63 -- 69}, language = {de} } @misc{GruegerFischerWolletal., author = {Gr{\"u}ger, Lennart and Fischer, Tim Sebastian and Woll, Ralf and Buhl, Johannes}, title = {Safeguarding Against Risks in the Wire Arc Additive Manufacturing Process}, series = {Industry 4.0 Science}, volume = {2024}, journal = {Industry 4.0 Science}, number = {1}, issn = {2942-6170}, doi = {10.30844/I4SE.24.1.63}, pages = {63 -- 69}, abstract = {In this article, the potential risks in wire arc additive manufacturing are analyzed using failure mode and effects analysis. To achieve this, 186 possible causes of risk were analyzed and the five most critical risks were discussed in detail. Four significant risk factors were identified in the construction process. The fifth risk relates to the shielding gas flow. This is only one influencing factor among the welding parameters, which have strong interactions with each other. Therefore, their relationships should be analyzed on the basis of numerous tests.}, language = {en} } @misc{GruegerJenschDittrichetal., author = {Gr{\"u}ger, Lennart and Jensch, Felix and Dittrich, Fabian and H{\"a}rtel, Sebastian}, title = {On the creation of a material bond between L-PBF-manufactured AZ91 and Ti-6Al-4V components in the context of medical applications}, series = {Materials}, volume = {17}, journal = {Materials}, number = {18}, publisher = {MDPI AG}, issn = {1996-1944}, doi = {10.3390/ma17184667}, abstract = {Within the scope of these investigations, the feasibility of a material bond between Ti-6Al-4V and the magnesium alloy AZ91 is analyzed. Ti-6Al-4V is frequently used for implants due to its biocompatibility, corrosion resistance, and specific strength. However, depending on the surface quality, the attachment behavior of the bone to the implant varies. Magnesium implants promote the regeneration of bone tissue and biodegrade as the bone tissue heals. Combining the properties of both materials in one implant enables a reduced implant volume and increased stability. For this reason, this study aims to demonstrate the feasibility of creating a material bond between the materials Ti-6Al-4V and AZ91. For this purpose, Ti-6Al-4V truncated cones and AZ91 sleeves were produced using the additive manufacturing process of laser powder bed fusion (L-PBF). The as-built sleeves were then pressed onto machined truncated cones. Since zinc serves as a lubricant and has good diffusion properties with the materials used as a result of heat treatment, a comparison was made between zinc-coated and the as-built Ti-6Al-4V samples. This showed that a bond was created after hot isostatic pressing and that the push-out force could be increased by more than 4.5 times. Consequently, a proof of feasibility was demonstrated, and a high potential for applications in medical technology was shown.}, language = {en} } @misc{GruegerHaertelSahin, author = {Gr{\"u}ger, Lennart and H{\"a}rtel, Sebastian and Sahin, Emre}, title = {Simulierte Produktionsumgebung heute - Evaluation der numerischen Prozesssimulation des selektiven Laserschmelzens}, series = {Industry 4.0 Science}, volume = {2024}, journal = {Industry 4.0 Science}, number = {4}, publisher = {GITO mbH Verlag}, issn = {2942-6154}, doi = {10.30844/I4SD.24.4.70}, pages = {70 -- 77}, language = {de} } @misc{BambachUensalSviridovetal., author = {Bambach, Markus and {\"U}nsal, Ismail and Sviridov, Alexander and Hama-Saleh, Rebar and Weisheit, Andreas}, title = {Hybrid manufacturing of sheet metals and functionalizing for joining applications via hole flanging}, series = {Production Engineering}, volume = {15}, journal = {Production Engineering}, number = {2}, issn = {0944-6524}, doi = {10.1007/s11740-020-01016-0}, pages = {223 -- 233}, language = {en} } @misc{SchmidtJenschHaertel, author = {Schmidt, Alexander and Jensch, Felix and H{\"a}rtel, Sebastian}, title = {Multi-material additive manufacturing-functionally graded materials by means of laser remelting during laser powder bed fusion}, series = {Frontiers of Mechanical Engineering}, volume = {18}, journal = {Frontiers of Mechanical Engineering}, number = {4}, issn = {2095-0233}, doi = {10.1007/s11465-023-0765-z}, pages = {1 -- 11}, abstract = {Many processes may be used for manufacturing functionally graded materials. Among them, additive manufacturing seems to be predestined due to near-net shape manufacturing of complex geometries combined with the possibility of applying different materials in one component. By adjusting the powder composition of the starting material layer by layer, a macroscopic and step-like gradient can be achieved. To further improve the step-like gradient, an enhancement of the in-situ mixing degree, which is limited according to the state of the art, is necessary. In this paper, a novel technique for an enhancement of the in-situ material mixing degree in the melt pool by applying laser remelting (LR) is described. The effect of layer-wise LR on the formation of the interface was investigated using pure copper and low-alloy steel in a laser powder bed fusion process. Subsequent cross-sectional selective electron microscopic analyses were carried out. By applying LR, the mixing degree was enhanced, and the reaction zone thickness between the materials was increased. Moreover, an additional copper and iron-based phase was formed in the interface, resulting in a smoother gradient of the chemical composition than the case without LR. The Marangoni convection flow and thermal diffusion are the driving forces for the observed effect.}, language = {en} } @misc{AlimovSviridovSydowetal., author = {Alimov, Artem and Sviridov, Alexander and Sydow, Benjamin and Jensch, Felix and H{\"a}rtel, Sebastian}, title = {Additive Manufacturing of Hot-Forming Dies Using Laser Powder Bed Fusion and Wire Arc Direct Energy Deposition Technologies}, series = {Metals}, volume = {13}, journal = {Metals}, number = {11}, issn = {2075-4701}, doi = {10.3390/met13111842}, abstract = {Additive technologies are now widely used for the production of complex precise parts and have high potential for the production of forming dies. In this work, hot-forming dies optimized for additive manufacturing were developed and produced with wire arc direct energy deposition (WA-DED) and laser powder bed fusion (L-PBF) technologies. The concept of lightweight hot-forming dies with a 2D-lattice structure was developed, which reduced the weight of each die by 56\%, from 14.2 kg to 6.1 kg, in production using L-PBF. Maraging/precipitation-hardened steel 17-4PH was used as an alternative to traditional hot-working steels with slightly lower mechanical properties and a much higher processability in the additive manufacturing process. The workability of the manufactured dies was confirmed by forging tests on an industrial screw press.}, language = {en} } @misc{HussainHassanWeietal., author = {Hussain, G. and Hassan, Malik and Wei, Hongyu and Buhl, Johannes and Xiao, Maohua and Iqbal, Asif and Qayyum, Hamza and Riaz, Asim Ahmed and Muhammad, Riaz and Ostrikov, Kostya}, title = {Advances on Incremental forming of composite materials}, series = {Alexandria Engineering Journal}, volume = {Vol. 79}, journal = {Alexandria Engineering Journal}, issn = {1110-0168}, doi = {10.1016/j.aej.2023.07.045}, pages = {308 -- 336}, language = {en} } @misc{HartRawungHornBuhletal., author = {Hart-Rawung, Thawin and Horn, Alexander and Buhl, Johannes and Bambach, Markus and Merklein, Marion}, title = {A unified model for isothermal and non-isothermal phase transformation in hot stamping of 22MnB5 steel}, series = {Journal of Materials Processing Technology}, volume = {313}, journal = {Journal of Materials Processing Technology}, issn = {1873-4774}, doi = {10.1016/j.jmatprotec.2023.117856}, language = {en} } @misc{SzyndlerHaertelBambach, author = {Szyndler, Joanna and H{\"a}rtel, Sebastian and Bambach, Markus}, title = {Machine learning of the dynamics of strain hardening based on contact transformations}, series = {Journal of Intelligent Manufacturing}, volume = {2025}, journal = {Journal of Intelligent Manufacturing}, publisher = {Springer}, doi = {10.1007/s10845-025-02577-6}, pages = {22}, abstract = {Dislocation density-based models offer a physically grounded approach to modeling strain hardening in metal forming. Since these models are typically defined by Ordinary Differential Equations (ODEs), their accuracy is constrained by both, the model formulation and the parameter identification process. Machine Learning (ML) provides an alternative by allowing models to be constructed directly from experimental data, bypassing the accuracy limitations of explicitly defined models. However, applying ML to ODEs introduces the need for novel training techniques. This work presents a new approach for developing neural ODE models for flow curve description, utilizing a contact transformation to simplify the problem of learning an ODE into a learning a multivariate function.}, language = {en} } @misc{KaarsDittrichMayretal., author = {Kaars, Jonny and Dittrich, Fabian and Mayr, Peter and Hensel, Jonas}, title = {Welding of 42SiCr treated by quenching and partitioning : mechanical properties of the HAZ and preheating proposal}, series = {Welding in the world : the international journal of materials joining}, journal = {Welding in the world : the international journal of materials joining}, publisher = {Springer}, address = {Berlin}, doi = {10.1007/s40194-025-02032-3}, pages = {1 -- 13}, abstract = {A 42SiCr experimental steel was heat-treated by the quenching and partitioning (Q\&P) heat treatment to achieve a combination of high strength and ductility. The associated microstructure is characterized in literature by finely distributed martensite laths with a small volume fraction of retained austenite embedded. The goal of this work is to provide a comprehensive characterization of the mechanical properties of all subzones in the heat-affected zone (HAZ) of welded 42SiCr-Q\&P steel. Dedicated microspecimens were subjected to a specifically selected thermal cycle in a dilatometer and characterized by mechanical testing and microstructural assessment. One specimen series is dedicated to the assessment of the mechanical properties of the material after welding; another four specimen series represent some carefully selected strategies to mitigate adverse effects of welding. Tensile testing revealed a decrease in yield strength in the HAZ by up to 35\%. The ductility of the material showed inverse behavior. Material in the supercritical zone shows > 2000 MPa of ultimate strength, but at the same time is very brittle. The most remarkable result showed that the embrittlement in the supercritical zone can be successfully mitigated by holding the material at temperatures in the range of 200-250 °C for 5 min upon cooling, resulting in a yield strength of around 1400 MPa along with a ductility of > 10\%, restoring the desired property combination. This very promising observation suggests fusion welding of 42SiCr-Q\&P might be possible by means of preheating, maintaining the superior mechanical properties of Q\&P in the weld.}, language = {en} } @misc{ErtugrulEmdadiJedynaketal., author = {Ertugrul, G{\"o}khan and Emdadi, Aliakbar and Jedynak, Angelika and Weiß, Sabine and H{\"a}rtel, Sebastian}, title = {Hot forming behavior of tungsten carbide reinforced Ni-based superalloy 625 additively manufactured by laser directed energy deposition}, series = {Additive manufacturing letters}, volume = {13}, journal = {Additive manufacturing letters}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2772-3690}, doi = {10.1016/j.addlet.2025.100267}, pages = {1 -- 12}, abstract = {The demands of high-performance industries such as aerospace, automotive, tool manufacturing, oil, and gas industries are driving the innovation in high-performance materials and their production methods. This study explores the impact of hybrid manufacturing, specifically the effect of the addition of tungsten carbide (WC/W2C) via Laser-Directed Energy Deposition (L-DED), on the hot workability, hardness, and microstructure of nickel-based superalloy Inconel 625 (IN625). IN625 is known for its high temperature and high corrosion resistance, and tungsten carbide for its high wear resistance and grain refinement effect. The integration of WC/W2C particles into the IN625 matrix, in addition to the use of the hybrid approach of additive manufacturing followed by a hot-forming process, significantly influences the microstructure and mechanical behavior of the material. Thus, while incorporation of the WC/W2C can strengthen the material and extend the mechanical limitations, its full impact, including any potential usages, should be thoroughly evaluated for the intended application of the materials. To understand the effect of WC/W2C, additive manufacturing of IN625 both with and without WC/W2C and isothermal hot compression was carried out. The objective is to analyze the differences in microstructure and properties between L-DED manufactured IN625, and WC-reinforced IN625, and their hot-forming behavior, focusing on the effects of WC addition and post-deformation on microstructure and mechanical properties. This work represents the first investigation into the effect of WC/W2C hard particles on the hot-forming process of additively manufactured Ni-based metal matrix composites.}, language = {en} } @misc{ErtugrulEmdadiHaertel, author = {Ertugrul, G{\"o}khan and Emdadi, Aliakbar and H{\"a}rtel, Sebastian}, title = {Powder production and additive manufacturing of iron aluminide alloys using plasma ultrasonic atomization and laser-directed energy deposition}, series = {Additive manufacturing letters}, volume = {14}, journal = {Additive manufacturing letters}, editor = {MacDonald, Eric W.}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {2772-3690}, doi = {10.1016/j.addlet.2025.100313}, pages = {1 -- 9}, abstract = {With a combination of desirable properties such as low density, high specific yield strength, low material cost, and excellent oxidation and corrosion resistance, iron aluminide (Fe-Al) has shown considerable potential to be an alternative to high-alloy chromium steels, and in some cases even nickel-based superalloys, in high-temperature applications. Due to these features, it is especially suitable for the aerospace and automotive industries. Recent advancements indicate an increasing interest in Fe-Al within the additive manufacturing industry, particularly in directed energy deposition (DED) processes. Despite this progress, processing of Fe-Al materials using the laser directed energy deposition (L-DED) has not been sufficiently investigated. In this study, Fe-Al powder material was produced from a commercial Al rod encased in a commercial low alloy-steel tube by a plasma-based ultrasonic atomization eliminating the need to cast an alloy ingot in advance. Subsequently, the produced powder was used in a l-DED process to fabricate an additively manufactured sample. The sample was investigated in terms of mechanical property, microstructure, chemical composition, and phase structure by scanning electron microscope (SEM) / energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), electron backscatter diffraction (EBSD) and microhardness analyses.}, language = {en} } @misc{EmdadiBolzJenschetal., author = {Emdadi, Aliakbar and Bolz, Sebastian and Jensch, Felix and Tovar, Michael and Weiß, Sabine}, title = {On the hot deformation of a Fe-Al-Ta iron aluminide prepared via laser powder bed fusion}, series = {Crystals}, volume = {13}, journal = {Crystals}, number = {4}, publisher = {MDPI}, address = {Basel}, issn = {2073-4352}, doi = {10.3390/cryst13040627}, pages = {1 -- 12}, abstract = {In the present work, a combined process of laser powder bed fusion (LPBF) and hot working in terms of microstructure refinement was investigated for Fe-25Al-1.5Ta alloy samples. Uniaxial compression tests were carried out parallel and perpendicular to the building direction (BD) at 1000 °C, where BCC A2-phase was stable, at a strain rate of 0.0013 s-1. The true stress-true strain curves indicated a broad flow stress peak followed by a slight decrease, which is typical for dynamic recrystallization (DRX) of conventional BCC metals such as ferritic iron. A negligible dependence in the flow stress behavior on the compression direction was observed. DRX initiated at a stress of 18.7 MPa for the sample compressed parallel to the BD, corresponding to a true strain of 0.011, and at 18.1 MPa for the samples compressed normal to the BD, which corresponded to a true strain of 0.010. The microstructural investigations by electron backscatter diffraction (EBSD) showed that the relatively coarse and elongated grains of the as-LPBF builds were significantly refined after hot working. The microstructure of the compressed samples mainly consisted deformed grains. These were fragmented by sub-grains bounded by low-angle boundaries independent of the compression axis, indicating the occurrence of dynamic recovery (DRV) during hot working. In addition, a few equiaxed, small grains were observed in the pre-existing grain boundaries, which formed due to DRX. Most pores in the as-LPBF builds were closed after hot compression, particularly in the central region of the deformed specimens where the compressive stress state is dominant. In summary, hot compression reveals a practical thermomechanical post-processing treatment for Fe-Al-Ta iron aluminides built by LPBF. The hot working refines the epitaxially elongated microstructure of the as-LPBF builds by DRV/DRX and reduces the porosity.}, language = {en} } @misc{ErtugrulHaelsigRimpletal., author = {Ertugrul, G{\"o}khan and H{\"a}lsig, Andre and Rimpl, Robert and Hensel, Jonas and H{\"a}rtel, Sebastian}, title = {Artificial neural network based calibration of Goldak heat source parameters in tandem plasma transferred arc process using finite element analysis}, series = {The international journal of advanced manufacturing technology}, volume = {139}, journal = {The international journal of advanced manufacturing technology}, publisher = {Springer Nature}, address = {London}, issn = {0268-3768}, doi = {10.1007/s00170-025-15843-x}, pages = {2349 -- 2363}, abstract = {The paper proposes a novel approach for determining multiple heat source parameters to achieve the necessary accuracy in the numerical prediction for a parallel tandem plasma transferred arc process. An artificial neural network (ANN) approach as a supervised learning-based artificial intelligence (AI) was used to model the complex relationship between heat distribution and tandem/dual heat source parameters based on finite element analysis (FEA). This study presents the first ANN-assisted numerical simulation for multiple heat source optimization of the tandem plasma transferred arc process. The model demonstrated high accuracy in predicting and calibrating the tandem heat source parameters, based on systematic simulation trials of the tandem plasma transferred arc welding. The results of the tandem heat source determined by ANN-assisted FEA were verified using experimental data on melt pool size and substrate distortion. This verification considered metrics such as penetration width, penetration depth, melt pool length, melt pool half-width, and the absolute distortion (measured as the difference between minimum and maximum displacement), with relative errors of 7.0\%, 7.6\%, 0.4\%, 1.9\%, and 9.7\%, respectively.}, language = {en} } @misc{EmdadiYangSzyndleretal., author = {Emdadi, Aliakbar and Yang, Yitong and Szyndler, Joanna and Jensch, Felix and Ertugrul, G{\"o}khan and Tovar, Michael and H{\"a}rtel, Sebastian and Weiß, Sabine}, title = {Highly printable Fe₃Al intermetallic alloy}, series = {Metals : open access journal}, volume = {16}, journal = {Metals : open access journal}, number = {5}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/met16010005}, pages = {1 -- 15}, abstract = {Intermetallic Fe₃Al-based alloys reinforced with Laves-phase precipitates are emerging as potential replacements for conventional high-alloy steels and possibly polycrystalline Ni-based superalloys in structural applications up to 700 °C. Their impressive mechanical properties, however, are offset by limited fabricability and poor machinability due to their severe brittleness. High tool wear during finish-machining, which is still required for components such as turbine blades, remains a key barrier to their broader adoption. In contrast to conventional manufacturing routes, additive manufacturing offers a viable solution by enabling near-net-shape manufacturing of difficult-to-machine iron aluminides. In the present study, laser powder bed fusion was used to produce an Fe-25Al-1.5Ta intermetallic containing strengthening Laves-phase precipitates, and the porosity, microstructure and phase composition were characterized as a function of the process parameters. The results showed that preheating the build plate to 650 °C effectively suppressed delamination and macrocrack formation, even though noticeable cracking still occurred at the high scan speed of 1000 mm/s. X-ray tomography revealed that samples fabricated with a lower scan speed (500 mm/s) and a higher layer thickness (0.1 mm) contained larger, irregularly shaped pores, whereas specimens printed at the same volumetric energy density (40 J/mm3) but with different parameter sets exhibited smaller fractions of predominantly spherical pores. All samples contained mostly elongated grains that were either oriented close to <001> relative to the build direction or largely texture-free. X-ray diffraction confirmed the presence of Fe₃Al and C14-type (Fe, Al)₂Ta Laves phase in all samples. Hardness values fell within a narrow range (378-398 HV10), with only a slight reduction in the specimen exhibiting higher porosity.}, language = {en} } @misc{JenschSviridovDubininetal., author = {Jensch, Felix and Sviridov, Alexander and Dubinin, Sergej and Karabulut, Fatih and Weiß, Sabine and H{\"a}rtel, Sebastian}, title = {Parameter optimization for low-porosity Ti-6Al-4V parts produced using accelerated PBF-LB process}, series = {Progress in additive manufacturing}, journal = {Progress in additive manufacturing}, publisher = {Springer}, address = {Cham}, issn = {2363-9520}, doi = {10.1007/s40964-025-01510-w}, pages = {1 -- 17}, abstract = {In this study, the influence of various process parameters on the porosity of Ti-6Al-4V parts fabricated via Powder Bed Fusion - Laser Based (PBF-LB) is investigated. Three different layer thicknesses (30 μm, 60 μm, and 120 μm) were analyzed to define process windows enabling a build-rate acceleration while keeping the porosity below 0.1\%. Through iterative parameter refinement, the effects of laser power, scan speed and hatch distance were examined in terms of linear energy density (LED), energy transmission density (ETD) and volumetric energy density (VED), and their influence on the formation of process-related defects such as pores. Correlations between these energy metrics and pore formation types (keyhole vs. lack-of-fusion) are discussed. The results demonstrate that process acceleration by a factor of more than 3 is possible while maintaining high quality of the components in terms of internal porosity. In addition, an accelerated method for manufacturing components using the PBF-LB process is presented, in which components are manufactured at very high build-rates but with increased porosity and then brought to the target porosity of 0.1\% using the HIP process. This has made it possible to accelerate the build-rate in PBF-LB production by a further 32\%. Accounting for the additional time required for HIP, the HIP route is faster than using the accelerated, which achieves the target porosity in as-built condition, for parts larger than 1421 cm3.}, language = {en} }