TY - CONF A1 - Wandtke, Karsten A1 - Schröpfer, Dirk A1 - Kannengießer, Thomas A1 - Kromm, Arne A1 - Scharf-Wildenhain, R. A1 - Hälsig, A. A1 - Hensel, J. T1 - Einfluss trennender Fertigungsschritte auf die Eigenspannungen in additiv gefertigten Bauteilen aus hochfestem Stahl N2 - Additive Fertigungsverfahren wie das Wire Arc Additive Manufacturing (WAAM) ermöglichen die effiziente Fertigung von gewichtsoptimierten endkonturnahen Strukturen in modernen Stahlkonstruktionen. Ihre Effizienz kann weiter durch die Verwendung von hochfesten Stählen gesteigert werden. Dies erlaubt eine signifikante Einsparung von Kosten, Zeit und Ressourcen. Entsprechende Schweißzusatzwerkstoffe für Lichtbogenschweißverfahren sind kommerziell verfügbar. Fehlende Richtlinien und fehlende quantitative Kenntnisse über die schweißtechnische Beanspruchung während der Fertigung und im Betrieb limitieren den industriellen Einsatz stark. Daher werden in einem aktuellen Vorhaben (IGF-Nr. 21162 BG) der BAM und TU Chemnitz die wesentlichen Einflüsse und komplexen Interaktionen durch Werkstoff, Fertigungsprozess, Konstruktion und trennende Fertigungsschritte auf den Beanspruchungszustand untersucht. Der vorliegende Beitrag fokussiert hierfür die Auswirkungen trennender Fertigungsschritte auf Verzug und Eigenspannungen definierter WAAM-Prüfkörper. Die Eigenspannungsanalyse erfolgt mittels Röntgenbeugung. Die große Anzahl an Ergebnissen von zuvor untersuchten Referenzproben, die mit einem speziellen WAAM-Massivdraht (Streckgrenze >820 MPa) bei unterschiedlicher Wärmeführung und Geometrie vollautomatisiert geschweißt wurden, lässt eine Korrelation der Messdaten zu. Hierzu erfolgt die Analyse des Ausgangszustandes und abschließend des Zustandes nach trennender Bearbeitung, welche begleitend mittels digitaler Bildkorrelation hinsichtlich des Verzuges untersucht wurden. So ist zu beobachten, dass die Geometrie deutlichen Einfluss auf Relaxation und Umlagerung der Eigenspannungen hat und damit die Risssicherheit positiv beeinflussen kann. T2 - Werkstofftechnisches Kolloquium 2023 Chemnitz CY - Chemnitz, Germany DA - 29.03.2023 KW - Additive Fertigung KW - Hochfester Stahl KW - Eigenspannungen PY - 2023 AN - OPUS4-57690 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wandtke, Karsten A1 - Schröpfer, Dirk A1 - Kromm, Arne A1 - Kannengießer, Thomas A1 - Scharf-Wildenhain, R. A1 - Hälsig, A. A1 - Hensel, J. T1 - Consideration of manufacturing-related stresses and cold crack avoidance in high-strength steels WAAM components N2 - High-strength steels offer great potential in weight-optimised modern steel structures. Additive manufacturing processes, such as Wire Arc Additive Manufacturing (WAAM), enable near-net-shape manufacturing of complex structures and more efficient manufacturing, offering significant savings in costs, time, and resources. Suitable filler materials for WAAM are already commercially available. However, the lack of knowledge or technical guidelines regarding welding residual stresses during manufacturing and operation in connection with cold cracking risk limit their industrial application significantly. In a project of BAM and TU Chemnitz, the influences and complex interactions of material, manufacturing process, design and processing steps on residual stress evolution are investigated. By developing process recommendations and a special cold cracking test, economic manufacturing, and stress-appropriate design of high-strength steel WAAM components are main objectives. The present study focuses on determining the influence of heat control (interpass temperature, heat input, cooling time) and the design aspects of the components on the hardness and residual stresses, which are analysed by X-ray diffraction. Defined reference specimens, i.e., hollow cuboids, are automatically welded with a special WAAM solid wire. The influences of wall length, wall thickness and wall height on the residual stresses are analysed. Geometric properties can be selectively adjusted by wire feed and welding speed but cannot be varied arbitrarily. This was addressed by adapted build-up strategies. The results indicate a significant influence of the heat control and the wall height on the residual stresses. The interpass temperature, wall thickness and wall length are not significant. These analyses allow recommendations for standards and manufacturing guidelines, enabling a safe and economic manufacturing of high-strength steel components. T2 - European Steel Technology and Application Days CY - Düsseldorf, Germany DA - 14.06.2023 KW - DED-arc KW - Additive manufacturing KW - Heat control KW - High-strength filler metals KW - Residual stress PY - 2023 AN - OPUS4-57691 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kromm, Arne A1 - Wandtke, Karsten A1 - Schröpfer, Dirk A1 - Kannengießer, Thomas A1 - Scharf-Wildenhain, R. A1 - Hälsig, A. A1 - Hensel, J. T1 - Eigenspannungen in mittels DED-Arc gefertigten Bauteilen aus hochfestem Stahl N2 - Der Vortrag gibt einen Überblick über die mittels XRD und Neutronenbeugung ermittelten Eigenspannungen in additiv gefertigten Bauteilen. Zusätzlich wird der Einfluss der Prozessparameter auf die Härte betrachtet. T2 - Frühjahrssitzung des Fachausschusses 13 Eigenspannungen der AWT CY - Berlin, Germany DA - 28.03.2023 KW - Eigenspannungen KW - DED-arc KW - Hochfester Stahl KW - Neutronenbeugung PY - 2023 AN - OPUS4-57289 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schroepfer, Dirk A1 - Rhode, Michael A1 - Erxleben, Kjell A1 - Richter, Tim T1 - Local mechanical properties of TIG dissimilar metal welded CoCrFeMnNi high-entropy alloy to austenitic steel AISI 304 N2 - Multiple principal element alloys (MPEA) encompass the well-known high entropy alloys (HEAs). MPEA/HEA represent a new class of materials consisting of at least three alloying elements, each containing 5 to 35 at.-%. This alloying concept thus differs fundamentally from conventional materials such as steel or nickel alloys. For this purpose, the alloying elements are specifically selected, and the microstructures are adjusted in a single-phase and, in some cases, multi-phase manner. In particular, conflicting goals, such as the trade-off between strength and ductility in conventional steels, are overcome. In the last 20 years, however, the focus has been on material synthesis. With the increase in available material quantities, the focus is now on pro-cessing issues such as joining and welding processes. The weldability of MPEA has received very little atten-tion so far. Experience with dissimilar metal welds (DMWs) is completely lacking but is essential for the appli-cation of these materials in combination with conventional materials. The present study presents, comprehen-sive experimental results on the weldability of MPEA-DMWs. For that purpose, a Co20Cr20Fe20Mn20Ni20 HEA in cold-rolled and heat-treated condition was joined by means of tungsten inert gas welding (TIG) with the austenitic Cr-Ni steel AISI 304. The DMWs resulted in interesting mechanical properties. They were obtained by instrumented tensile tests as well as the local deformation in the weld area by using digital image correlation (DIC) technique. A significant softening in the heat-affected zone (HAZ) of the MPEAs as well as a slightly reduced tensile strength with a significant decrease of the elongation at fracture were found. The experiments provided proof in principle of the weldability of the MPEAs for DMWs with conventional materials that ensure a corresponding capability for mechanical loading. This allows further considerations on the application of these innovative materials. T2 - IIW Annual Assembly, Meeting of Commission C-II CY - Singapore DA - 18.07.2023 KW - High-entropy alloy KW - Welding KW - Microstructure KW - Mechanical properties KW - Dissimilar metal weld PY - 2023 AN - OPUS4-57978 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Reichel, Levin A1 - Schroepfer, Dirk A1 - Kannengiesser, Thomas A1 - Kromm, Arne A1 - Becker, Amadeus T1 - Residual stress formation during repeated gouging and repair welding cycles of high-strength steels N2 - The construction of foundation and erection structures for wind power plants requires the use of modern, sustainable and resource-efficient high-strength fine-grained structural steels. Weld defects due to the welding process are unacceptable. To overcome this issue, local thermal gouging followed by re-welding is a common and cost-effective method. The high shrinkage restraint of the gouge by the surrounding structure can cause crack initiation when design and re-weld induced residual stresses are superimposed. This risk is intensified by the progressive degradation of the microstructure and mechanical properties of high-strength steels during the weld repair process. This investigation focuses on high-strength steels S500MLO for offshore applications and S960QL for mobile crane applications. The reduction and development of residual stresses caused by local thermal gouging and re-welding was investigated. Digital Image Correlated (DIC) stress-strain analysis was performed during preheating, welding and cooling. The results of the global DIC analysis and local longitudinal and transverse residual stresses of the weld determined by X-ray diffraction were found to be in good agreement. Furthermore, different stress levels were identified during gouging and welding. Repeated repair cycles led to an increase of longitudinal and transverse residual stresses in the weld metal as well as a hardness increase in the heat affected zone. T2 - European Conference on Residual Stresses - ECRS11 CY - Prague, Czech Republic DA - 03.06.2024 KW - Repair welding KW - Gouging KW - Residual stress KW - Repair cycles KW - High-strength steels PY - 2024 AN - OPUS4-60215 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kromm, Arne A1 - Wandtke, Karsten A1 - Engelking, Lorenz A1 - Schröpfer, Dirk A1 - Kannengießer, Thomas A1 - Scharf-Wildenhain, R. A1 - Hälsig, A. A1 - Hensel, J. T1 - Case Studies 2 – RS in DED-arc AM Components N2 - The presentation shows examples of resdiual stresses to be found typically in DED-arc additively manufactured high strength steel components. T2 - European Conference on Residual Stresses 11 - Tutorial 1: Residual stresses in additive manufacturing CY - Prague, Czech Republic DA - 03.06.2024 KW - Residual stress KW - DED-arc KW - High strength steel PY - 2024 AN - OPUS4-60285 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kromm, Arne A1 - Wandtke, Karsten A1 - Shabdali, Gundappa Ashwit A1 - Schröpfer, Dirk A1 - Kannengießer, Thomas A1 - Scharf-Wildenhain, R. A1 - Hälsig, A. A1 - Hensel, J. T1 - Comparison and capabilities of different Methods N2 - X-ray and Neutron diffraction as well as the contour method were used to determine residual stresses in a additively manufactured sample. The results are compared. Capabilites and limitations are shown. T2 - European Conference on Residual Stresses 11 - Tutorial 1: Residual stresses in additive manufacturing CY - Prague, Czech Republic DA - 03.06.2024 KW - Residual stress KW - X-ray diffraction KW - Neutron diffraction KW - Contour method PY - 2024 AN - OPUS4-60286 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Engelking, Lorenz A1 - Schröpfer, Dirk A1 - Kannengießer, Thomas A1 - Eissel, A. A1 - Treutler, K. A1 - Wesling, V. T1 - Herstellung beanspruchungsgerechter Oberflächen durch Kombination innovativer additiver und abtragender Fertigungsschritte an hochbelasteten Komponenten N2 - Die additive Fertigung mittels Schweißverfahren bietet große ökonomische Vorteile für eine ressourceneffiziente Bauteilherstellung. Offene Fragen bezüglich Homogenität, Anisotropie der Schweißgefüge und den damit verbundenen Bauteileigenschaften stehen einer wirtschaftlichen Verarbeitung oftmals im Wege. Finale Bauteilgeometrie und Oberflächengüte erfordern meist komplementäre subtraktive Fertigungsschritte. Werkstoffe für hochbelastbare Komponenten sind oftmals schwer spanbar. In einem Vorhaben der BAM und des ISAF wurde untersucht, wie die Modifikation der AM-Schweißzusätze und das ultraschallunterstützte Fräsen (US) die Zerspanungssituation verbessern. Der vorliegende Artikel stellt wesentliche Zusammenhänge zwischen Legierung, Gefüge und Zerspanung zweier schwer spanbarer Hochleistungslegierungen (FeNi und CoCr) dar. Großes Potenzial zeigte neben dem US die Modifikation mit Zr und Hf bei Zulegierung in das Schweißgut mittels Beschichtung von Massivdrähten bzw. Herstellung von Fülldrähten. T2 - Bachelor-, Master-, Doktoranden-Kolloquium (BMDK) CY - Magdeburg, Germany DA - 19.06.2024 KW - Legierungsmodifikation KW - Ultraschallunterstütztes Fräsen KW - Additive Fertigung KW - Oberflächenintegrität PY - 2024 AN - OPUS4-60429 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -