In situ Untersuchung der Phasenverteilung und der Schmelzbaderstarrung von Duplexstählen mittels laserinduzierter Plasmaspektroskopie (LIBS)
Metallurgical, Thermal and Thermomechanical Treatment of Materials
Final Report Abstract
The subject of the research project was the investigation of the possibilities for improving the available weld metal prediction tools for TIG welding of duplex stainless steels. For this purpose, investigations of the solidification of the weld pool and the subsequent solid phase transformations were carried out using in situ measurements of the chemical composition. The measurement method used was laser-induced plasma spectroscopy (LIPS) or laser-induced breakdown spectroscopy (LIBS). The measured variable was the spatially and temporally resolved chemical composition to determine the phase composition or distribution of ferrite and austenite during welding and solidification. In addition, the measured phase ratio changes were correlated with the respective mechanical properties of the weld seams. Many applications in industry require a material-to-material joining process of DSS. When these steels are welded, certain alloying elements can burn off and condense on colder surface areas. This loss of chemical elements can lead to changes in the structure. Using LIBS, the distribution of chemical elements on the surface of the weld seam could be measured in situ for the first time. The results were compared with those of conventional measurement methods such as energy dispersive X-ray analysis (EDX) and X-ray fluorescence analysis (XRF). LIBS line scans could be validated with EDX line scans, and the concentration curves of the chemical elements showed a comparable curve. The LIBS mappings carried out could be validated using XRF mappings and showed a high degree of agreement in the concentration distributions of the most important alloying elements. Alloying elements evaporated from the TIG welding process could also be detected using LIBS. It was also shown that LIBS measurements can also be carried out without interference during TIG welding with and without DSS filler material. Quantitative chemical compositions can be determined in situ and a correlation between the microstructure and the chemical compositions determined in situ could also be determined. High concentrations of austenite-stabilizing elements such as Cu, Ni and Mn reduce the ferrite number (FN) in the weld metal. In contrast, high concentrations of ferrite-stabilizing elements such as Nb, C and Si increase the FN in the weld metal. It is planned to address this topic in a further research project with the focus on expanding and remodeling the WRC1992 prediction diagram using in situ LIBS measurements.
Publications
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In situ investigation of chemical composition during TIG welding in duplex stainless steels using Laser-Induced Breakdown Spectroscopy (LIBS). Forces in Mechanics, 6, 100063.
Quackatz, Lukas; Griesche, Axel & Kannengiesser, Thomas
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Spatially resolved EDS, XRF and LIBS measurements of the chemical composition of duplex stainless steel welds: A comparison of methods. Spectrochimica Acta Part B: Atomic Spectroscopy, 193, 106439.
Quackatz, Lukas; Griesche, Axel & Kannengiesser, Thomas
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In situ Messung der chemischen Konzentration in der Schmelze während des WIG-Schweißens von Duplexstählen. Tagungsband 5. Niedersächsisches Symposium Materialtechnik, 2023
Quackatz L., A. Griesche, T. Kannengiesser, K. Treutler, T. Gehling, A. Eissel & V. Wessling
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Rapid solidification during welding of duplex stainless steels – in situ measurement of the chemical concentration by Laser-Induced Breakdown Spectroscopy (LIBS). IOP Conference Series: Materials Science and Engineering, 1274(1), 012018.
Quackatz, L.; Griesche, A. & Kannengiesser, T.
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Assessing ferrite content in duplex stainless weld metal: WRC ‘92 predictions vs. practical measurements. Welding in the World, 69(1), 31-45.
Quackatz, Lukas; Westin, Elin Marianne; Griesche, Axel; Kromm, Arne; Kannengiesser, Thomas; Treutler, Kai; Wesling, Volker & Wessman, Sten
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In situ chemical analysis of duplex stainless steel weld by laser induced breakdown spectroscopy. Spectrochimica Acta Part B: Atomic Spectroscopy, 214, 106899.
Quackatz, Lukas; Gornushkin, Igor; Griesche, Axel; Kannengiesser, Thomas; Treutler, Kai & Wesling, Volker
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In situ measurement of hydrogen concentration in steel using laser-induced breakdown spectroscopy (LIBS). Welding in the World, 68(4), 915-923.
Quackatz, L.; Griesche, A.; Nietzke, J. & Kannengiesser, T.
