TY - JOUR A1 - Delgado Arroyo, Diego A1 - Richter, Tim A1 - Schröpfer, Dirk A1 - Boerner, Andreas A1 - Rhode, Michael A1 - Lindner, T. A1 - Preuß, B. A1 - Lampke, T. T1 - Influence of Milling Conditions on AlxCoCrFeNiMoy Multi-Principal-Element Alloys N2 - Multi-Principal-Element or High-Entropy Alloys (MPEAs/HEAs) have gained increasing interest in the past two decades largely due to their outstanding properties such as superior mechanical strength and corrosion resistance. However, research studies on their processability are still scarce. This work assesses the effect of different machining conditions on the machinability of these novel alloys, with the objective of advancing the introduction of MPEA systems into industrial applications. The present study focuses on the experimental analysis of finish-milling conditions and their effects on the milling process and resulting surface finish of CoCrFeNi, Al0.3CoCrFeNi and Al0.3CoCrFeNiMo0.2 alloys fabricated via Spark Plasma Sintering. Ball-nose-end milling experiments have been carried out various milling parameters such as cutting speed, feed per cutting edge, and ultrasonic assistance. In situ measurements of cutting forces and temperature on the tool edge were performed during the experiments, and surface finish and tool wear were analyzed afterwards. The results exhibited decreasing cutting forces by means of low feed per cutting edge and reduced process temperatures at low cutting speed, with the use of ultrasonic-assisted milling. It was shown that the machinability of these modern alloys through conventional, as well as modern machining methods such as ultrasonic-assisted milling, is viable, and common theories in machining can be transferred to these novel MPEAs. KW - Multi-principal element alloys KW - Finish milling KW - Spark plasma sintering KW - Ultrasonic-assisted milling KW - Microstructure characterization PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-572990 DO - https://doi.org/10.3390/coatings13030662 VL - 13 IS - 3 SP - 1 EP - 18 PB - MDPI (Multidisciplinary Digital Publishing Institute) CY - Basel (CH) AN - OPUS4-57299 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Buzolin, R.H. A1 - Richter, Tim A1 - Pixner, F. A1 - Rhode, Michael A1 - Schröpfer, Dirk A1 - Enzinger, N. T1 - Microstructure and texture characterisation of friction stir welded CoCrNi and CoCrFeMnNi multi-principle element alloys N2 - This work investigates the microstructure formed in friction stir welds of FCC alloys, focused on two multiprincipal alloys: a CoCrFeMnNi high-entropy alloy (HEA) and a CoCrNi medium-entropy alloy (MEA). A commercial stainless steel AISI 304 is used for comparison. The largest nugget was formed in the MEA, while the smallest was formed in the HEA. Grain refinement occurs in the stirred zone in all welds. Discontinuous dynamic recrystallisation is the predominant restoration mechanism during friction stir welding of the three investigated alloys. A sharp decrement in the Σ3 boundary fraction occurs in the stirred zone of the AISI 304 and HEA welds, while comparable values with the base metal are found for the MEA weld. The peak in the maximum index of crystallographic texture is observed on the advancing side of the stirred zone of the AISI 304 weld. A strong <001> θ-fibre texture is formed in the advancing side of the nugget in the AISI 304 from a well-established {123} <634> S-type texture in the base metal. Multiple crystallographic texture components without specific fibres are identified in most regions of the welds, indicating the complex shear path history during friction stir welding. KW - Microstructure KW - Multiple principal element alloy KW - Friction stir welding KW - Electron backscattered diffraction KW - Crystallographic texture PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-572987 DO - https://doi.org/10.1016/j.mtcomm.2023.105870 VL - 35 SP - 1 EP - 14 PB - Elsevier Ltd. CY - Amsterdam (NL) AN - OPUS4-57298 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Richter, Tim A1 - Diese, Marcel A1 - Rhode, Michael A1 - Schröpfer, Dirk T1 - Characterization of cracking phenomena in TIG welds of high and medium entropy alloy N2 - Multi-element systems with defined entropy (HEA - High Entropy Alloy or MEA - Medium Entropy Alloy) are rather new material concepts that are becoming increasingly important in materials research and development. Some HEA systems show significantly improved properties or combinations of properties, e.g., the overcome of the trade-off between high strength and ductility. Thus, the synthesis, the resulting microstructures, and properties of HEA have been primarily investigated so far. In addition, processing is crucial to achieve a transfer of potential HEA/MEA materials to real applications, e.g. highly stressed components. Since fusion welding is the most important joining process for metals, it is of vital importance to investigate the weldability of these materials. However, this has rarely been the subject of research up to date. For that reason, in this work the weldability depending on the surface preparation of a CoCrFeMnNi-HEA and a CoCrNi-MEA for TIG welding is investigated. The fusion welding of longer plates is described here for the first time for the CoCrNi alloy. The welds of both materials showed distinct formation of cracks in the heat affected zone (HAZ). Optical and scanning electron microscopy analysis clearly confirmed an intergranular fracture topography. But based on the results, the crack mechanism cannot be conclusively clarified as either a liquid metal embrittlement (LME) or hot cracking like liquid film separation occurred. T2 - 2nd International Conference on Advanced Joining Processes CY - Online meeting DA - 21.10.2021 KW - High Entropy Alloy KW - TIG welding KW - Cracking PY - 2021 AN - OPUS4-53607 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schröpfer, Dirk T1 - Formation of multi-axial welding stresses due to material behaviour during fabrication of high-strength steel components N2 - Today an expanding application of high-strength steels in modern welded constructions can be observed. The economical use of these steel grades largely depends on the strength and reliability of the weldments. Therefore the special microstructure and mechanical properties of these grades have to be taken into account by keener working ranges regarding the welding parameters. However, performance and safety of welded components are strongly affected by the stresses occurring during and after welding fabrication locally in the weld seam and globally in the whole component, especially if the shrinkage and distortion due to welding are restrained. Some extensive studies describe the optimization of the welding stresses and the metallurgical effects regarding an adapted welding heat control. In particular lower working temperatures revealed to be effective to significantly reduce the local and global welding induced residual stresses of the completed weld. However, decreased interpass temperatures cause concurrently higher stresses during welding fabrication. This work shows some strategies to reduce these in-process stresses. With help of multi-axial welding stress analyses in component-related weld tests using a special 2-MN-testing facility differences in stress build-up are described in detail for root welds, filler layers and subsequent cooling to ambient temperature. T2 - IIW Intermediate Meeting, C-II-A CY - Trollhättan, Sweden DA - 06.03.2017 KW - Residual stresses KW - GMA Welding KW - High-strength steels KW - Process parameters KW - Restraint PY - 2017 AN - OPUS4-41066 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Scharf-Wildenhain, R. A1 - Hälsig, A. A1 - Hensel, J. A1 - Wandtke, Karsten A1 - Schröpfer, Dirk A1 - Kromm, Arne A1 - Kannengießer, Thomas T1 - Einfluss von Wärmeführung und Bauteildesign auf die Eigenschaften und fertigungsbedingten Beanspruchungen additiv geschweißter hochfester Feinkornbaustähle N2 - Hochfeste Feinkornbaustähle verfügen über großes Potenzial für gewichtsoptimierte, effiziente Strukturen in vielen modernen Stahlkonstruktion. Weitere Effizienzsteigerungen können durch additives Fertigen sowie bionische Bauweisen erreicht werden. Hochfeste Zusatzwerkstoffe für additives MSG-Schweißen (engl.: Wire Arc Additive Manufacturing, WAAM) sind bereits von den Schweißzusatzherstellern lieferbar. Eine breite industrielle Anwendung insbesondere für KMU ist aufgrund fehlender quantitativer Erkenntnisse und Richtlinien bezüglich schweißbedingter Beanspruchungen und Bauteilsicherheit während der Herstellung und des Betriebs derzeit stark limitiert. In einem gemeinsamen Forschungsprojekt (FOSTA-P1380/IGF21162BG) der BAM und der TU Chemnitz werden daher die mit Eigenspannungsausbildung und der Gefahr einer Kaltrissbildung verbundenen prozess- und werkstoffbedingten sowie konstruktiven Einflüsse beim WAAM hochfester Stähle untersucht. Der vorliegende Beitrag fokussiert die Analyse der Auswirkungen von Schweißwärmeführung und Design der WAAM-Bauteile auf die Abkühlbedingungen, Gefüge, mechanisch-technologischen Eigenschaften und Eigenspannungen. Hierfür werden geometrisch definierte Probenkörper (Hohlquader) vollautomatisiert mit einem speziellen, hochfesten WAAM-Massivdraht (Streckgrenze >790 MPa) geschweißt. Die Wärmeführung und Probenabmessungen werden innerhalb eines statistischen Versuchsplans variiert. Die Schweißwärmeführung wird dabei so eingestellt, dass die t8/5-Abkühlzeiten im empfohlenen Verarbeitungsbereich (ca. 5 s bis 20 s) sichergestellt sind. Hierzu ließen sich über zusätzliche thermo-physikalische Umformsimulationen mittels Dilatometer die komplexen Wärmezyklen abbilden und die resultierende Zugfestigkeit des Schweißgutes bestimmen. Das WAAM-Schweißen komplexer Geometrien mit variierenden Schweißwärmeführungen und geometrischen Verhältnissen bzw. Wanddicken bedingt neben den Auswirkungen auf die Abkühlbedingungen, Abkühlzeiten und Gefüge deutliche Einflüsse auf die konstruktiven Steifigkeitsverhältnisse beim Schweißen. Es zeigen sich anhand der Schweißexperimente signifikante Auswirkungen durch Probenskalierung und Wärmeeinbringung auf die resultierenden lokalen Eigenspannungen. Die Folge können ungünstige Bauteileigenschaften und risskritische Zugeigenspannungen sein. T2 - DVS Congress 2022 CY - Koblenz, Germany DA - 19.09.2022 KW - MAG-Schweißen KW - Additive Fertigung KW - Eigenspannungen KW - Hochfester Stahl KW - Kaltrisssicherheit KW - Wärmeführung KW - Windenergie PY - 2022 SN - 978-3-96144-189-1 VL - 382 SP - 737 EP - 745 PB - DVS Media GmbH CY - Düsseldorf AN - OPUS4-56719 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröpfer, Dirk A1 - Kromm, Arne A1 - Kannengießer, Thomas T1 - Load analyses of welded high-strength steel structures using image correlation and diffraction techniques N2 - In an increasing number of modern steel applications, high-strength structural steel grades are demanded to meet specifications regarding a high load-bearing capacity and a low operating weight. Lightweight design rules enhance the safety requirements, especially for welded joints. Besides a higher cracking risk for high-strength steel welds, the formation of tensile residual stresses might lead to fracture due to overloading or premature failure if not adequately considered. In this study, a stress-strain analysis was conducted at component-related structures from S960QL using digital image correlation while preheating, welding and cooling adjacent to the weld seam. X-ray diffraction analysis of the local residual stresses in the weld seam showed a good comparability with global analyses using either a DIC system or a special testing facility, which allowed in situ measurements of welding loads. By analysing two different seam geometries, it could be shown that lower multi-axial stresses arise if a narrower weld groove is used. Comparative analyses revealed a direct correlation of the local residual stresses in the weld with transverse shrinkage restraint, whereas the residual stress level in the HAZ is significantly affected by the bending restraint of the weld construction and the occurring bending stresses, respectively. KW - Process parameters KW - Residual stresses KW - Restraint KW - GMAwelding KW - High-strength steels PY - 2018 DO - https://doi.org/10.1007/s40194-018-0566-x SN - 0043-2288 SN - 1878-6669 VL - 62 IS - 3 SP - 459 EP - 469 PB - Springer CY - Berlin, Heidelberg AN - OPUS4-44270 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Eissel, A. A1 - Engelking, Lorenz A1 - Treutler, K. A1 - Schröpfer, Dirk A1 - Wesling, V. A1 - Kannengießer, Thomas ED - da Silva, L. F. M. ED - Martins, P. A. F. ED - Reisgen, U. T1 - Nickel-Iron-Alloy Modification to Enhance Additively Welded Microstructure for Subsequent Milling N2 - The aerospace industry uses nickel–iron alloys, e.g., FeNi36, to create moulding tools for composite materials, since these alloys have a low coefficient of thermal expansion. Nickel–iron alloys are hard-to-cut materials. The moulding tools are large in size and involve complex structures, making them cost-intensive and difficult to manufacture. Thus, the focus is set on additive manufacturing, which can additionally enable the repair of components in order to eliminate local defects. However, the process usually results in a heterogeneous microstructure and anisotropic mechanical properties. As there is a high demand for a precise and exact fit of the precision moulds and the surface quality, the welded components must be subsequently machined. Additionally, inhomogeneous microstructure may lead to unstable cutting forces and conditions. Consequently, a modification of the microstructure morphology is achieved through specific alloy modifications in order to stabilise and improve the subsequent machining process. Therefore, titanium and zirconium are chosen as modification elements with a maximum 1% weight percent and are added to nickel–iron alloy powder. The elements are alloyed, and build-up welded by plasma-transferred-arcwelding. The resulting microstructure morphology of the welded wall structure and the machining properties are then determined. It can be shown that titanium has a significant effect on the structural morphology of the welded layers, as well as on the machining. KW - Alloy modification KW - Alloy 36 KW - Plasma-transferred arc welding KW - Ultrasonic-assisted milling KW - Surface integrity PY - 2022 SN - 978-3-030-95463-5 DO - https://doi.org/10.1007/978-3-030-95463-5_6 SP - 85 EP - 99 PB - Springer CY - Cham AN - OPUS4-55484 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schröpfer, Dirk T1 - Formation of multi-axial welding stresses due to material behaviour during fabrication of high-strength steel components N2 - Today an expanding application of high-strength steels in modern welded constructions can be observed. The economical use of these steel grades largely depends on the strength and reliability of the weldments. Therefore the special microstructure and mechanical properties of these grades have to be taken into account by keener working ranges regarding the welding parameters. However, performance and safety of welded components are strongly affected by the stresses occurring during and after welding fabrication locally in the weld seam and globally in the whole component, especially if the shrinkage and distortion due to welding are restrained. Some extensive studies describe the optimization of the welding stresses and the metallurgical effects regarding an adapted welding heat control. In particular lower working temperatures revealed to be effective to significantly reduce the local and global welding induced residual stresses of the completed weld. However, decreased interpass temperatures cause concurrently higher stresses during welding fabrication. This work shows some strategies to reduce these in-process stresses. With help of multi-axial welding stress analyses in component-related weld tests using a special 2-MN-testing facility differences in stress build-up are described in detail for root welds, filler layers and subsequent cooling to ambient temperature. T2 - IIW Annual Assembly 2017 CY - Shanghai, China DA - 25.06.2017 KW - Residual stresses KW - GMA Welding KW - Restraint KW - High-strength steels KW - Process parameters PY - 2017 AN - OPUS4-41075 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schröpfer, Dirk T1 - Residual stress formation in DED-arc manufactured high strength steel components N2 - Additive manufacturing (AM) processes enable the efficient production of advanced constructions. New developments in topology optimization are leading to weight-optimized designs of increasing complexity. Direct energy deposition processes (DED) such as wire and arc-based additive manufacturing are an important method of additive manufacturing. The wire filler metals enable a wide range of materials, while the arc process provides a high deposition rate compared to laser and powder-based processes. Combined with the use of high-strength steels, the thickness of walls or components can be significantly reduced in the context of lightweight construction, which results in significant savings in energy, costs, time and resources. Suitable high-strength steel filler metals are commercially available for DED-arc AM processes. However, guidelines and quantitative knowledge about welding stresses and cold cracking issues during component production and service are lacking. This limits the industrial application considerably. In a joint project of BAM and Chemnitz University of Technology, the main influences and complex interactions of material, production process, design and processing steps on the residual stress level are investigated. The aim is to develop processing recommendations and a cold cracking test for economical processing and stress-related design of high-strength steels with DED-arc. This study focuses on residual stress analysis by neutron diffraction (ND) and X-ray diffraction (XRD) on defined test specimens. The ND analysis were performed at the Paul Scherrer Institute- Villigen, Switzerland (PSI) and the XRD analysis at BAM. The study shows a quantitative and qualitative comparison of the residual stress magnitudes and distribution between the component bulk (ND) and surface (XRD) analyses. The ND analysis reveals that in DED-arc AM walls the residual stresses dominate in the direction of welding and are negligibly small in each case transverse to the direction of welding. The topology of the analyzed residual stresses shows almost identical residual stress maps compared to XRD. In addition, the residual stresses are significantly influenced by the solid phase transformation of the material due to low cooling times and less post heat treatment cycles of following AM layers in the area of the top layer. T2 - IIW Intermediate Meeting C-II/CIX CY - Munich, Germany DA - 06.03.2023 KW - Additive manufacturing KW - High strength steel KW - Residual stress PY - 2023 AN - OPUS4-59307 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schröpfer, Dirk T1 - Projektvorstellung FOSTA P1311: Beanspruchungsgerechte Reparatur von Schweiß-verbindungen bei der Fertigung von Bauteilen aushochfesten Feinkornbaustählen N2 - Bei der Montage von Stahlkonstruktionen kommt es trotz anforderungsgerechter schweißtechnischer Fertigung vereinzelt zur Detektion von unzulässigen Unregelmäßigkeiten im Schweißbereich. Die Verarbeitungsregelwerke empfehlen das lokale thermische Ausfugen betroffener Bereiche und erneutes Schweißen, geben aber aufgrund fehlender wissenschaftlich fundierter Untersuchungen kaum Informationen zu adäquaten Reparaturkonzepten. Dies betrifft insbesondere die Berücksichtigung und Optimierung resultierender schweißbedingter Beanspruchungen durch hohe Schrumpfbehinderungen der Ausfugenuten sowie der Gefügedegradation angrenzender Bereiche durch das Ausfugen und erneute Schweißen. Gerade bei hochfesten Stahlgüten ergeben sich dadurch häufig reduzierte mechanische Eigenschaften und zusätzliche schweißbedingte Beanspruchungen sowie erneut auftretende Nahtdefekte. Deshalb sind für das Forschungsvorhaben systematische bauteilrelevante Untersuchungen der schweißbedingten Beanspruchungen und Gefügeveränderungen reparierter Schweißnähte in Abhängigkeit von der Schrumpfbehinderung und Wärmeführung beim Schweißen und Ausfugen sowie von der Reparaturzyklenanzahl geplant, mit dem Ziel Empfehlungen für beanspruchungs- und werkstoffgerechte Reparaturkonzepte abzuleiten. Hierfür sind gerade Analysen an hochfesten Stahlgüten S500 für den Offshore-Bereich und S960QL für den Mobilkranbau interessant, die zur Errichtung und Fertigung hocheffizienter Konstruktionen wie Windenergieanlagen notwendig sind. Die Erkenntnisse bieten eine Grundlage für entsprechende Normen und Regelwerke. Damit können letztlich Schäden und zumeist teure Nacharbeiten verhindert und eine verbesserte Ausnutzung des hohen Festigkeitspotentials hochfester Stähle erreicht werden. Gerade auch KMU können mit Blick auf die Kosten für Fertigung, Schweißarbeit und Material von den Erkenntnissen beim Einsatz hochfester Stähle, die für eine effiziente Realisierung der Energiewende in Deutschland notwendig sind, profitieren T2 - NA 092-00-05 GA (DVS AG Q 4/Q 4.1) CY - Hamm, Germany DA - 04.03.2020 KW - Reparatur KW - Eigenspannungen KW - Schweißen KW - Wärmeführung KW - Hochfester Feinkornbaustahl KW - Gefügedegradation PY - 2020 AN - OPUS4-51584 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Scharf-Wildenhain, R. A1 - Hälsig, A. A1 - Hensel, J. A1 - Wandtke, Karsten A1 - Schröpfer, Dirk A1 - Kannengießer, Thomas T1 - Heat control and design‑related effects on the properties and welding stresses in WAAM components of high‑strength structural steels N2 - Commercial high-strength fller metals for wire arc additive manufacturing (WAAM) are already available. However, widespread industrial use is currently limited due to a lack of quantitative knowledge and guidelines regarding welding stresses and component safety during manufacture and operation for WAAM structures. In a joint research project, the process- and material-related as well as design infuences associated with residual stress formation and the risk of cold cracking are being investigated. For this purpose, reference specimens are welded fully automated with defned dimensions and systematic variation of heat control using a special, high-strength WAAM fller metal (yield strength>790 MPa). Heat control is varied by means of heat input (200–650 kJ/m) and interlayer temperature (100–300 °C). The ∆t8/5 cooling times correspond with the recommendations of fller metal producers (approx. 5–20 s). For this purpose, additional thermo-physical forming simulations using a dilatometer allowed the complex heat cycles to be reproduced and the resulting ultimate tensile strength of the weld metal to be determined. Welding parameters and AM geometry are correlated with the resulting microstructure, hardness, and residual stress state. High heat input leads to a lower tensile stress in the component and may cause unfavorable microstructure and mechanical properties. However, a sufciently low interlayer temperature is likely to be suitable for obtaining adequate properties at a reduced tensile stress level when welding with high heat input. The component design afects heat dissipation conditions and the intensity of restraint during welding and has a signifcant infuence on the residual stress. These complex interactions are analyzed within this investigation. The aim is to provide easily applicable processing recommendations and standard specifcations for an economical, appropriate, and crack-safe WAAM of high-strength steels. KW - GMA welding KW - Additive manufacturing KW - Residual stresses KW - High-strength steel KW - Cold cracking safety KW - Heat control KW - Wind energy PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-567397 DO - https://doi.org/10.1007/s40194-022-01450-x SN - 1878-6669 VL - 2022 SP - 1 EP - 11 PB - Springer CY - Berlin AN - OPUS4-56739 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eissel, A. A1 - Engelking, Lorenz A1 - Gustus, R. A1 - Treutler, K. A1 - Wesling, V. A1 - Schröpfer, Dirk A1 - Kannengießer, Thomas T1 - Alloy modification for additive manufactured Ni alloy components—part I: effect on microstructure and hardness of Invar alloy N2 - Alloy 36 (1.3912), also known as “Invar,” is an alloy with 36% nickel. The alloy has a remarkably low thermal expansion coefficient in certain temperature ranges. This peculiarity is called the invar effect, which was discovered in 1896 by the Swiss physicist Charles Édouard Guillaume. Therefore, it is used in applications in which dimensional stability is critical, such as molding tools for composite materials in aerospace, automotive applications, or liquified natural gas (LNG) cargo tanks. Moreover, increasingly complex structures and the optimization of resource efficiency also require additive manufacturing steps for the production or repair of components. Additively manufactured components have a heterogeneous microstructure and anisotropic mechanical properties. In addition, the manufactured components require subsequent machining surface finishing, like finish milling, to achieve their final contour. Nickel iron alloys are difficult to machine. Additionally, inhomogeneous microstructure may lead to unstable cutting forces and conditions. In part I of this investigation, the initial alloy 36 is modified with the elements Ti, Zr, and Hf up to a maximum of 0.33 wt.-%. The influence of the modification elements on the microstructure as well as on the hardness of the AM components is examined. Furthermore, one modification is applied to metal arc welding process and investigated. Part II focuses on the effect of the alloy modifications on machinability as well as on the surface integrity of plasma-transferred-arc-welded (PTA) and finish milled invar components. T2 - 75th IIW Annual Assembly CY - Tokyo, Japan DA - 17.07.2022 KW - Alloy modification KW - Alloy 36 KW - Plasma-transferred arc welding PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-571777 DO - https://doi.org/10.1007/s40194-023-01510-w SN - 0043-2288 SP - 1 EP - 9 PB - Springer CY - Heidelberg AN - OPUS4-57177 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Engelking, Lorenz A1 - Eissel, A. A1 - Schröpfer, Dirk A1 - Treutler, K. A1 - Kannengießer, Thomas A1 - Wesling, V. T1 - Optimisation of surface residual stresses using ultrasonic‑assisted milling for wire‑arc additive manufactured Ni alloy components N2 - Nickel alloys are cost intensive materials and generally classified as difficult-to-cut material. However, machining of these materials is needed especially in case of alloy 36 (1.3912), which is commonly used in mould construction for the production of fibre-reinforced composites. With regard to repair, modification and manufacturing of such components, additive manufacturing offers significant economic advantages. Nevertheless, subsequent machining steps are needed to achieve the final component contour and defined surface conditions. Dependent on the material and machining process conditions, detrimental tensile residual stresses may be the result on the machined surface, having negative impact on the component performance and safety. In this investigation, machining experiments were carried out on wire arc additive manufactured components made of alloy 36, varying the cutting speed and the feed rate. In addition, the conventional milling process (CM) was compared with a modern, hybrid machining process, the ultrasonic-assisted milling (US). The cutting forces and the surface-near residual stresses were analysed using X-ray diffraction. A significant improvement of the machinability as well as the surface integrity by using the ultrasonic assistance was observed, especially at low cutting speeds. The CM induced mainly tensile residual stresses, the US mainly compressive residual stresses. KW - Surface integrity KW - Ultrasonic-assisted milling KW - Additive manufacturing KW - Ni alloy KW - Alloy 36 PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-575246 DO - https://doi.org/10.1007/s00170-023-11326-z SN - 1433-3015 VL - 126 IS - 9 SP - 4191 EP - 4198 PB - Springer Nature AN - OPUS4-57524 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -