Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-57269 Zeitschriftenartikel Wandtke, Karsten; Schröpfer, Dirk; Scharf-Wildenhain, R.; Hälsig, A.; Kannengießer, Thomas; Kromm, Arne; Hensel, J. Influence of the WAAM process and design aspects on residual stresses in high-strength structural steels Wire arc additive manufacturing (WAAM) enables the efficient production of weight-optimized modern engineering structures. Further increases in efficiency can be achieved by using high-strength structural steels. Commercial welding consumables for WAAM are already available on the market. Lack of knowledge and guidelines regarding welding residual stress and component safety during production and operation leads to severely limited use for industry applications. The sensitive microstructure of high-strength steels carries a high risk of cold cracking; therefore, residual stresses play a crucial role. For this reason, the influences of the material, the WAAM process, and the design on the formation of residual stresses and the risk of cold cracking are being investigated. The material used has a yield strength of over 800 MPa. This strength is adjusted via solid solution strengthening and a martensitic phase transformation. The volume expansion associated with martensite formation has a significant influence on the residual stresses. The focus of the present investigation is on the additive welding parameters and component design on their influence on hardness and residual stresses, which are analyzed by means of X-ray diffraction (XRD). Reference specimens (hollow cuboids) are welded fully automated with a systematic variation of heat control and design. Welding parameters and AM geometry are correlated with the resulting microstructure, hardness, and residual stress state. Increased heat input leads to lower tensile residual stresses which causes unfavorable microstructure and mechanical properties. The component design affects heat dissipation conditions and the intensity of restraint during welding and has a significant influence on the residual stress. Berlin Springer 2023 Welding in the World 67 4 987 996 urn:nbn:de:kobv:b43-572698 10.1007/s40194-023-01503-9 https://creativecommons.org/licenses/by/4.0/deed.de 2023-04-05 OPUS4-53604 Zeitschriftenartikel Sprengel, Maximilian; Ulbricht, Alexander; Evans, Alexander; Kromm, Arne; Sommer, Konstantin; Werner, Tiago; Kelleher, J.; Bruno, Giovanni; Kannengießer, Thomas Towards the optimization of post-laser powder bed fusion stress-relieve treatments of stainless steel 316L This study reports on the stress relaxation potential of stress-relieving heat treatments for laser powder bed fused 316L. The residual stress is monitored non-destructively using neutron diffraction before and after the heat treatment. Moreover, the evolution of the microstructure is analysed using scanning electron microscopy. The results show, that a strong relaxation of the residual stress is obtained when applying a heat treatment temperature at 900°C. However, the loss of the cellular substructure needs to be considered when applying this heat treatment strategy. Boston Springer 2021 Metallurgical and materials transactions A 52 12 5342 5356 urn:nbn:de:kobv:b43-536045 10.1007/s11661-021-06472-6 https://creativecommons.org/licenses/by/4.0/deed.de 2021-10-25 OPUS4-50036 Posterpräsentation Kannengießer, Thomas Issues and challenges in component welding of high strength fine-grained structural steels When assessing the performance of welded components residual stresses are vital. The possibilities of transferring the real boundary conditions of welding, which influence the residual stress, into the laboratory are highlighted in this contribution. The potentials of a test system specially developed for this purpose are demonstrated. The component design induces global process-, geometry- and material-dependent stresses, which can be simulated and quantified in the system. In addition, the resulting local residual stress distribution can be exactly determined with high spatial resolution with the aid of X-ray diffraction. Examples are presented of how the conditions to be found during production are simulated in the laboratory. 2019 AJP 2019 Ponta Delgada, Azores (Portugal) 24.10.2019 25.10.2019 2019-12-16 OPUS4-49770 Beitrag zu einem Tagungsband Kromm, Arne; Kannengießer, Thomas Online-Observation of Martensite Formation by combined use of Synchrotron Diffraction and Dilatometry Welding residual stress engineering by means of an adjusted martensite phase transformation would be highly attractive as detrimental tensile residual stresses may be prevented already during welding without time and cost intensive post processing. The present study shows a synchrotron diffraction analysis of a martensitic steel subjected to thermo-mechanical load cycles. Experiments were conducted regarding the microstructural strain response during the austenite to martensite transformation. The strains are a function of the temperature and the specific loads applied during cooling. The relation between the transformation plasticity of the material, the amount of martensite formed and the arising strains can thus be assessed. The lattice plane specific strains were compared to experimental findings from (macro) dilatation tests. It is shown that the microscopic material behavior differs remarkably from the one observed on the macroscopic scale, what leads to characteristic residual stresses in the material. Osaka, Japan SEIEI Printing Co., Ltd Joining and Welding Research Institute 2019 Proceedings of Visual-JW 2019 & WSE 2019 Visual-JW 2019 & WSE 2019 The 5th International Symposium on Visualization in Joining & Welding Science through Advanced Measurements and Simulation & The 8th International Conference of Welding Science and Engineering Osaka, Japan 21.11.2019 22.11.2019 83 84 2019-12-02 OPUS4-49773 Beitrag zu einem Tagungsband Kannengießer, Thomas; Kromm, Arne; Lausch, Thomas; Schroepfer, Dirk; Hannemann, Andreas In-situ Observation of Stress Evolution and Cracking during High Strength Steel Welding Residual stresses are crucial when assessing the performance of welded components. The present work deals with the possibilities of transferring the real-life boundary conditions of welding, which influence the residual stress, into the laboratory. The possibilities of a test system with a load capacity of 2 MN specifically developed for online monitoring of stress formation and cracking are shown. Due to the structural design, global process, geometry and material-dependent stresses are induced, which can be quantified in-situ during welding and post weld heat treatment. Examples are presented how the conditions to be found during production are simulated in the laboratory. It is shown how welding residual stresses in high-strength steels are affected by the heat control. Elevated working temperatures significantly increase the tensile residual stresses in the heat affected zone (HAZ). The effect of mechanical stresses resulting from welding on stress relief cracking is demonstrated by the example of a creep resistant steel. Reheat cracks were monitored online during post weld heat treatment. Osaka, Japan SEIEI Printing Co., Ltd Joining and Welding Research Institute 2019 Proceedings of Visual-JW 2019 & WSE 2019 Visual-JW 2019 & WSE 2019 The 5th International Symposium on Visualization in Joining & Welding Science through Advanced Measurements and Simulation & The 8th International Conference of Welding Science and Engineering Osaka, Japan 21.11.2019 22.11.2019 83 84 2019-12-05 OPUS4-49763 Vortrag Kannengießer, Thomas In-situ Observation of Stress Evolution during High Strength Steel Welding Residual stresses are crucial when assessing the performance of welded components. The present work deals with the possibilities of transferring the real-life boundary conditions of welding, which influence the residual stress, into the laboratory. The possibilities of a test system with a load capacity of 2 MN specifically developed for online monitoring of stress formation and cracking are shown. Due to the structural design, global process, geometry and material-dependent stresses are induced, which can be quantified in-situ during welding and post weld heat treatment. Examples are presented how the conditions to be found during production are simulated in the laboratory. It is shown how welding residual stresses in high-strength steels are affected by the heat control. Elevated working temperatures significantly increase the tensile residual stresses in the heat affected zone (HAZ). The effect of mechanical stresses resulting from welding on stress relief cracking is demonstrated by the example of a creep resistant steel. Reheat cracks were monitored online during post weld heat treatment. 2019 Visual-JW 2019 & WSE 2019 The 5th International Symposium on Visualization in Joining & Welding Science through Advanced Measurements and Simulation & The 8th International Conference of Welding Science and Engineering Osaka, Japan 21.11.2019 22.11.2019 2019-11-27 OPUS4-46662 Zeitschriftenartikel Kromm, Arne; Lausch, Thomas; Schröpfer, Dirk; Dixneit, Jonny; Hannemann, Andreas; Kannengießer, Thomas Neu, Richard W.; Totten, George E. From the field to the lab: Real scale assessment of stresses in welded components Residual stresses are crucial when assessing the performance of welded components. The present work deals with the possibilities of transferring the real-life boundary conditions of welding, which influence the residual stress, into the laboratory. The possibilities of a test system specifically developed for this purpose with a maximum capacity of 2 MN are shown. Due to the structural design, global process, geometry and material-dependent stresses are induced, which can be simulated and quantified within the system. Additionally, X-ray diffraction can be applied to determine the resulting local residual stress distribution precisely with high spatial resolution. Two examples are presented how the conditions to be found during production are simulated in the laboratory. It is shown how welding residual stresses in high-strength steels are affected by the heat control. It was possible to clarify why elevated working temperatures significantly increase the bending stresses in the welded joint and therefore the tensile residual stresses in the heat affected zone (HAZ). The effect of a heat treatment applied under mechanical stress resulting from welding is demonstrated by the example of a creep resistant steel. Reheat cracking is significantly increased in this case compared to small scale laboratory based tests. West Conchohocken ASTM International 2018 Materials Performance & Characterization 7 4 574 593 10.1520/MPC20170111 2018-11-20 OPUS4-46605 Beitrag zu einem Tagungsband Schröpfer, Dirk; Kromm, Arne; Hannemann, Andreas; Kannengießer, Thomas Seefeldt, Marc In-situ determination of critical welding stresses during assembly of thick-walled components made of high-strength steel The performance and safety of welded high-strength low-alloyed steel (HSLA) components are substantially affected by the stresses occurring during and after welding fabrication, especially if welding shrinkage and distortion are severely restrained. The surrounding structure of the whole component affects loads in the far-field superimposing with welding stresses in the near-field of the weld. In this study a unique testing facility was used to restrain shrinkage and bending while analyse multiaxial far-field loads (max. 2 MN) during assembly of thick-walled component. A novel approach for the assessment of the in-situ-measured far-field data in combination with the actual weld geometry was elaborated. For the first time, analyses of the global bending moments of restrained welds based on the neutral axis of the actual weld load bearing section were achieved. Hence, far-field measurements offered the possibility to determine critical near-field stresses of the weld crosssections for the entire joining process. This work presents the approach for far-to-near field in-situ determination of stresses in detail for the 2-MN-testing system based on an extensive experimental work on HSLA steel welds, which demonstrates sources and consequences of these high local welding stresses. Thus, it was clarified, why the first weld beads are crucial regarding welding stresses and cold cracking, which is well known, but has never been measured so far. Accompanying analyses using X-ray diffraction (XRD) after welding show effects on local residual stress distributions. These analyses indicated viable prospects for stress reduction during assembly of thick-walled HSLA steel components. Millersville, PA, USA Materials Research Forum LLC 2018 Residual stresses 2018, ECRS-10 6 978-1-9452-9188-3 European Conference on Residual Stresses 2018 - ECRS-10 Leuven, Belgium 11.09.2018 14.09.2018 191 196 urn:nbn:de:kobv:b43-466053 10.21741/9781945291890-30 https://creativecommons.org/licenses/by/4.0/deed.de 2018-11-16 OPUS4-41806 Zeitschriftenartikel Vollert, J.; Dixneit, Jonny; Kromm, Arne; Buslaps, Th.; Kannengießer, Thomas In situ EDXRD study of MAG-welding using LTT weld filler materials under structural restraint Welding using low transformation temperature (LTT) filler materials is an innovative approach to mitigate detrimental welding residual stresses without cost-intensive post weldtreatments. Due to the local Generation of compressive residual stresses in the weld line by means of a delayed martensite transformation a significant enhancement of the cold cracking resistance of highly stressed welded components can be expected. For the effective usage of These materials a deeper understanding of the microstructural evolution inside the weld material is necessary to determine the complex processes that cause the residual stress formation during welding. Solid-state phase transformation kinetics and the evolution of strain in LTT weld filler materials are monitored in-situ at the instrument ID15A at the ESRF in Grenoble, France. The transferability to real components is implemented by using a realistic MAG welding process under consideration of structural restraint. During welding of multilayer joints, the phase Transformation and phase specific strain evolution of each individual layer is investigated in transmission geometry by means of energy-dispersive X-ray diffraction EDXRD using high energy synchrotron Radiation with a counting rate of 2.5 Hz. The measurement results of a 10% Cr / 10% Ni LTT weld filler are compared to data monitored for the conventional weld filler material G89. The in-situ data clearly indicate a strong effect on the local strain evolution and the formation of compressive strain. This results from the restraint volume expansion during the postponed austenite to martensite transformation of the LTT weld filler, which counteracts the thermal shrinkage. In contrast, for the conventional weld filler material the thermal contraction strains lead to tensile residual strain during welding. Furthermore, the results of in-situ observation during welding Show that the transformation kinetic is dependent on the welding sequence. Switzerland Trans Tech Publications 2017 Materials Science Forum 905 107 113 10.4028/www.scientific.net/MSF.905.107 2017-09-01 OPUS4-37892 Zeitschriftenartikel Dixneit, Jonny; Kromm, Arne; Hannemann, Andreas; Friedersdorf, Peter; Kannengießer, Thomas; Gibmeier, J. In-situ load analysis in multi-run welding using LTT filler materials Modifying the level of mostly detrimental welding residual stresses already during the welding process would be highly attractive as time- and cost-consuming post processing may be prevented. The nature of stress buildup during welding-associated cooling is highly affected by phase transformations. Up to now, it is not clear in which way this is applicable to real component welding exhibiting high shrinkage restraint and complex heat input. In this study, two different low transformation temperature (LTT) alloys have been investigated concerning the stress development in restrained multi-run butt welding in order to evaluate the potential of stress reduction. Pulsed gas metal arc welding (P-GMAW) welding was executed on a testing facility designed to simulate real lifelike restraint conditions of component weldments. The effect of reducedMS-temperatures and the heat control on the globally acting stresses was monitored by in-situ measurement of the reaction forces during welding fabrication. Additional local residual stress measurements allowed analyzing global as well as local loading of the welded construction. Although phase transformation has a significant influence on unloading the joint during each weld pass, the reaction stress upon cooling to room temperature seems to be determined mainly by the heat input. On the surface, low longitudinal residual stresses were observed in case of LTT whereas transverse residual stresses are less affected. Heidelberg Springer 2016 Welding in the World - The International Jounral of Materials Joining 60 69th IIW Annual Assembly and International Conference Melbourne, Australia 10.07.2016 15.07.2016 6 1159 1168 10.1007/s40194-016-0373-1 2016-10-24