TY - CONF A1 - Griesche, Axel A1 - Mente, Tobias A1 - Falahat, Ala'A . M. Al A1 - Tengattini, Alessandro A1 - Dal Pont, Stefano A1 - Kardjilov, Nikolay T1 - Crystallographic phase transformations and corresponding temperature distributions during gtaw of supermartensitic stainless steel visualized by nbei N2 - We investigated the phase transformations during butt-welding of supermartensitic steel plates with help of Neutron-Bragg-Edge Imaging (NBEI). Gas tungsten arc welding (GTAW) was used with a motorized torch allowing for automated weldments. The austenitization in the heat affected zone (HAZ) could be clearly visualized at λ = 0.39 nm, a wavelength smaller than the Bragg edge wavelengths of both austenite and martensite. The re-transformation into the martensitic phase during cooling was clearly detected. However, we observed an unexpected additional change in transmission at λ = 0.44 nm, a wavelength larger than the wavelength of the Bragg edges of both the martensitic and austenitic phases. We attribute this change to the Deybe-Waller-Factor that describes the temperature dependence of coherent scattering at a crystal lattice. The observed two-dimensional attenuation map corresponds well with a temperature distribution modelling by software macros in ANSYS [3]. Here, the absolute temperature values could be achieved by calibrating the modelled attenuation with help of a thermocouple placed at the steel plate. This allows in return for a direct two-dimensional temperature reading based on the Debye-Waller-relation between neutron attenuation and sample temperature. T2 - WCNR-12 CY - Idaho Falls, Id, USA DA - 02.06.2024 KW - Neutron KW - Radiography KW - Welding PY - 2024 AN - OPUS4-60242 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Engelking, Lorenz A1 - Shabdali, Gundappa Ashwit A1 - Wandtke, Karsten A1 - Kromm, Arne A1 - Kannengießer, Thomas A1 - Schröpfer, Dirk A1 - Scharf-Wildenhain, R. A1 - Hälsig, A. A1 - Hensel, J. T1 - Residual Stress Analysis on a DED-Arc High-strength Steel Component Using the Contour Method N2 - This poster compares the results of the residual stress determination of DED-Arc open hollow cuboid specimens via XRD with the contour method. The results are in very good agreement. T2 - ECRS11 CY - Prague, Czech Republic DA - 03.06.2024 KW - DED-Arc KW - Residual stress KW - Contour method PY - 2024 AN - OPUS4-60221 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 - Hübner, Martin A1 - Dittmann, Florian A1 - Kromm, Arne A1 - Varfolomeev, Igor A1 - Kannengießer, Thomas T1 - Einfluss der Nahtgeometrie auf den Eigenspannungsabbau unter Verwendung von Low Transformation Temperature (LTT) – Schweißzusätzen N2 - Low Transformation Temperature (LTT)-Schweißzusätze stellen einen innovativen Ansatz zur Erhöhung der Ermüdungsfestigkeit geschweißter Konstruktionen dar. LTT-Schweißzusätze zeichnen sich durch eine martensitische Phasenumwandlung nahe der Raumtemperatur aus, welche Druckeigenspannungen in der Schweißnaht und der Wärmeeinflusszone (WEZ) generieren. Dieser Vortrag fokussiert sich auf die gezielte Einbringung zusätzlicher LTT-Lagen an ermüdungskritischen Stellen von konventionell geschweißten Verbindungen. Dies ermöglicht eine ökonomische Anwendung, ohne dass die Schweißnahtintegrität zu stark beeinflusst wird. Die Auswirkungen zusätzlicher LTT-Lagen wurden anhand geschweißter Längssteifen aus hochfestem Stahl hinsichtlich der chemischen Zusammensetzung und der Eigenspannungen untersucht. Unter Variation der Schweißgeschwindigkeit und Abstand zur konventionellen Naht konnten 3 unterschiedliche Nahtausführungen des Chrom-Nickellegierten LTT-Zusatzes bewertet werden. Die chemische Zusammensetzung wurde mittels OES-Analysen untersucht. Dabei stellte heraus, dass die Aufmischung in allen Varianten sehr ähnlich war trotz teils unterschiedlicher LTT-Volumina. Härtebestimmungen ergaben in allen 3 Varianten eine ähnliche Härte. Daraus lässt sich annehmen, dass die Martensitstarttemperatur bei allen Nahtvarianten ähnlich ist. Röntgenografische Eigenspannungsmessungen belegen, dass die Eigenspannungen am versa-genskritischen Nahtübergang bei Einsatz von LTT-Schweißzusätzen deutlich abgesenkt werden. Während die konventionelle Schweißnaht Zugeigenspannungen von ca. 350 MPa aufweist, können an den LTT-Nähten teilweise Druckeigenspannungen von bis zu -150 MPa nachgewiesen werden. Je höher der Abstand zur konventionellen Naht und je größer das eingebrachte LTT-Volumen ist, umso stärker sind die Eigenspannungsreduzierungen am Nahtübergang. Da in allen 3 Varianten eine ähnliche Martensitstarttemperatur angenommen werden kann, ist somit die Geometrische Komponente der LTT-Zusatzlage ein entscheidender Faktor für die Eigenspannungsreduzierung. T2 - AWT FA 13 CY - Wolfsburg, Germany DA - 19.03.2024 KW - Chemische Zusammensetzung, KW - LTT KW - Nahtgeometrie KW - Eigenspannungen PY - 2024 AN - OPUS4-60135 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Reichel, Levin A1 - Schroepfer, Dirk A1 - Kannengiesser, Thomas A1 - Kromm, Arne T1 - Effiziente Reparaturkonzepte mittels geregelter MSG Hochleistungsprozesse bei der Fertigung hochfester Dickblechverbindungen für Offshore Windenergieanlagen P1629 N2 - Der Bau von Gründungs- und Turmstrukturen für Windkraftanlagen erfordert den Einsatz moderner, nachhaltiger und ressourcenschonender hochfester Feinkornbaustähle. Durch den Schweißprozess verursachte Schweißnahtfehler sind nicht akzeptabel. Um diese zu beheben, ist das lokale thermische Fugenhobeln mit anschließendem Reparaturschweißen ein gängiges und wirtschaftliches Verfahren. Die hohe Schrumpfbehinderung um die ausgefugte Nut durch das umgebende Gefüge kann zu Rissbildung führen, wenn sich konstruktiv bedingte Spannungen und Eigenspannungen aus der Reparaturschweißung überlagern. Diese Gefahr wird durch die Verschlechterung der Mikrostruktur und der mechanischen Eigenschaften hochfester Stähle während des Schweißreparaturprozesses noch verstärkt. T2 - Bachelor-, Master-, Doktoranden-Kolloquium CY - Magdeburg, Germany DA - 16.05.2024 KW - Reparaturschweißen KW - Thermisches Ausfugen KW - Offshore KW - Sprühlichtbogen PY - 2024 AN - OPUS4-60050 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rhode, Michael A1 - Mente, Tobias A1 - Kannengiesser, Thomas T1 - Parameters and challenges for reliable hydrogen determination in welded joints by carrier gas hot extraction JF - The Paton Welding Journal N2 - For the hydrogen-based energy economy of tomorrow, the construction of the necessary infrastructure will play a central role. Most materials used to date, such as welded steels, can be prone to hydrogen embrittlement under certain conditions. This includes the classic delayed cold cracking during welding as well as degradation phenomena during service of components in hydrogen-containing environment. For the evaluation of any hydrogen effect, for example, on the mechanical properties of a welded metallic material, the hydrogen content must be precisely determined. In the case of weld seams, the carrier gas hot extraction (CGHE) according to ISO 3690 is meanwhile state-of-the-art. CGHE is based on accelerated hydrogen degassing due to the thermal activation of hydrogen at elevated temperatures. In addition to the quantification of hydrogen, thermal desorption analysis (TDA) with varying heating rates can be used to determine and evaluate the hydrogen trapping at microstructural defects in the material. For both techniques, experimental and metrological influences must be considered, which have a major effect on the result. For example, ISO 3690 suggests different sample geometries and minimum extraction times for CGHE. This study summarizes the results and experiences of numerous investigations at the Federal Institute for Materials Research and Testing (BAM) with different sample temperatures and geometries (ISO 3690 type B and cylindrical TDA samples) regarding the influence of the sample surface (polished/welded), measurement accuracy depending on the sample volume and the insufficient monitoring of the effect of PI control on the extraction temperature. A deviating extraction temperature from the target temperature can significantly falsify the measurement results. Based on the results, methods are shown which allow the desired extraction temperature to be reached quickly without physically interfering with the measuring equipment. This serves to significantly improve the reliability of the hydrogen measurement through increased signal stability and accelerated hydrogen desorption. In general, an independent temperature measurement with dummy samples is recommended for the heating procedure of choice to exclude possible undesired temperature influences before the measurement. The methods described can be transferred directly to industrial applications KW - Welding KW - Hydrogen measurement KW - ISO 3690 KW - Carrier gas hot extraction PY - 2024 DO - https://doi.org/10.37434/tpwj2024.04.01 SN - 0957-798X VL - 4 SP - 3 EP - 10 PB - International Association Welding AN - OPUS4-60071 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröpfer, Dirk A1 - Witte, Julien A1 - Kromm, Arne A1 - Kannengießer, Thomas T1 - Stresses in repair welding of high-strength steels—part 2: heat control and stress optimization JF - Welding in the World N2 - In welding of high-strength steels, e.g. for foundations and erection structures of wind energy plants, unacceptable defects can occasionally be found in the weld area, which should be removed by thermal gouging and subsequent re-welding. High shrinkage restraint of repair welds may lead to crack formation and component failure, predominantly in interaction with degraded microstructures and mechanical properties due to repair cycles. This study aims for elaboration of recommendations for repair concepts appropriate to the stresses and materials involved to avoid cold cracking, damage and expensive reworking. In part 1 [1] of this study, systematic investigations of influences of shrinkage restraint on residual stresses and cold cracking risk during repair welding of two high-strength steels S500MLO for offshore application and S960QL for mobile crane structures were focussed. In this part 2, the microstructure, particularly hardness, and residual stresses due to gouging and influences of heat control parameters in repair welding are analysed. A clear reduction in residual stress after gouging can be observed, especially for the specimens with restrained transverse shrinkage. Gouging to a depth of approx. 2/3 of the seam height does not lead to a complete relaxation of the observed reaction forces. Particularly for the higher strength steel S960QL, there are pronounced areas influenced by the gouging process in which a degradation of the microstructure and properties should be assumed. Overall, the repair welds show a significant increase in the width of the weld and HAZ compared to the original weld, especially in the case of S960QL/G89. The repair welds show higher welding-induced stresses than the original welds, especially in the areas of the HAZ and the base metal close to the weld seam. This behaviour can be attributed overall to increased restraint conditions due to the remaining root weld or shorter gouge grooves. In good agreement with earlier investigations, the residual stresses transverse to the weld can be significantly reduced by upwardly limited working or interpass temperatures, and the reaction stresses resulting from high restraint conditions can be effectively counteracted. The influence of the heat input on the stress formation is low compared to the interpass temperature for both test materials. KW - Repair-welding KW - Wind Energy KW - High-strength steels KW - Cold cracking KW - Residual stresses KW - Offshore steels PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-600259 DO - https://doi.org/10.1007/s40194-024-01731-7 SN - 0043-2288 SP - 1 EP - 15 PB - Springer Nature AN - OPUS4-60025 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rhode, Michael A1 - Richter, Tim A1 - Erxleben, Kjell A1 - Schröpfer, Dirk A1 - Witt, Julia A1 - Özcan-Sandikcioglu, Özlem A1 - Kannengießer, Thomas T1 - Processing and application properties of multiple principal element alloys (MPEA) N2 - The presentation gives an overview of BAM's activities on processing influences and application properties of MPEAs in the form of joined and machined high and medium entropy alloys (CoCrFeMnNi and CoCrNi). In the case of welding, the focus is on defect-free welded joints with sufficient mechanical properties. In the case of machining, the focus is on the possible influence on the surface quality of the materials through adequate milling parameters. In addition, the hydrogen absorption and diffusion properties as well as the electrochemical corrosion behavior are fundamentally examined. T2 - FAU-Department Werkstoffwissenschaften, Seminar: Aktuelle Probleme der Werkstoffwissenschaften CY - Erlangen, Germany DA - 25.04.2024 KW - Welding KW - Application properties KW - Machining KW - High-entropy alloy KW - Hydrogen PY - 2024 AN - OPUS4-59975 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 - Innovationstag 2024 CY - Düsseldorf, Germany DA - 10.04.2024 KW - Legierungsmodifikation KW - Ultraschallunterstütztes Fräsen KW - Additive Fertigung KW - Oberflächenintegrität PY - 2024 AN - OPUS4-59958 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kromm, Arne T1 - Spannungen beim Schweißen von Bauteilen N2 - Der Vortrag gibt einen Überblick über das Phänomen der Schweißeigenspannungen. Es wird auf die Bedeutung und Entstehungsursachen eingegangen. Mit besonderem Fokus auf die Eigenspannungen beim Schweißen von Komponenten werden Messmöglichkeiten und Anwendungsbeispiele vorgestellt. T2 - Jahresmitgliederversammlung DVS Bezirksverbandes Berlin CY - Berlin, Germany DA - 24.04.2024 KW - Eigenspannungen PY - 2024 AN - OPUS4-59944 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -