TY - CONF A1 - Quackatz, Lukas T1 - Analyzing the impact of individual alloying elements on weld microstructure: In situ chemical composition measurement during TIG welding of Duplex Stainless Steels microstructure N2 - Various industrial applications require the joining of DSS components. Tungsten Inert Gas (TIG) welding is particularly well-suited for this purpose due to the ability to achieve highly reproducible automated welds. However, during solidification of the weld pool, critical phase ratios of ferrite (α) and austenite (γ) may occur, leading to solidification cracking, increased corrosion susceptibility, lower ductility and critical strength values. Hence, in order to achieve the desired material characteristics, it is crucial to accurately predict the α/γ phase ratio within the weld. Conventionally, the WRC-1992 diagram is employed for this purpose. In our study, we used Laser-Induced Breakdown Spectroscopy (LIBS) to track alterations in the chemical composition of the weld metal on the surface throughout the welding process. One significant benefit of this method is its capability to provide precise and real-time measurements of chemical compositions during welding, both temporally and spatially. In previous investigations, we could develop routines to quantify the measurement of chemical compositions within the weld metal and the Heat-Affected Zone (HAZ). The conducted research focuses on examining the alterations in chemical concentrations of specific alloying elements, namely Cu and Mn as γ-forming elements, and Nb and Cr as α-forming elements, during welding. These changes are measured in real-time using Laser-Induced Breakdown Spectroscopy (LIBS). To achieve this, both the ferrite number, determined through magnetic-inductive techniques, and the weld microstructure are analyzed. Through image-analytical methods, a correlation is established between the microstructure and the LIBS data obtained. T2 - AJP 2023 CY - Braga, Portugal DA - 19.10.2023 KW - LIBS KW - In situ measurement KW - Duplex stainless steel KW - TIG welding PY - 2023 AN - OPUS4-58657 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Quackatz, Lukas T1 - Rapid solidification during welding of duplex stainless steels – in situ measurement of the chemical Concentration by Laser-Induced Breakdown Spectroscopy (LIBS) N2 - Duplex stainless steels (DSS) are frequently used, especially in applications requiring high strength combined with high corrosion resistance in aggressive media. Examples include power plant components and maritime structures. During welding of these steels, local variations in chemical composition can occur. This results in ferritization of the material and negatively affects the mechanical properties of the components. In this work, tungsten inert gas (TIG) welding experiments were performed with DSS. Chemical composition analysis was realized in situ by using Laser Induced Breakdown Spectroscopy (LIBS). The aim of the work is to quantitatively measure the chemical composition in the weld seam of various DSS and to identify possible influences of welding parameters on the microstructure of the material. The chemical concentrations of the main alloying elements Cr, Ni, Mn on the surface of the sample during the welding process and the cooling process were measured. Mn and Ni are austenite stabilizers and their content increases during welding by using certain high alloyed filler material. Spectra were recorded every 1.3 s at a spacing of approximately 2 mm. During the cooling process the location of the measurement was not changed. The LIBS method is proofed to be suitable for the quantitative representation of the chemical compositions during the welding process. T2 - 6th International Conference on Advances in Solidification Processes CY - Le Bischenberg, France DA - 20.06.2022 KW - LIBS KW - In situ measurement KW - Duplex stainless steel KW - TIG welding PY - 2022 AN - OPUS4-55116 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Quackatz, Lukas T1 - First measurements of chemical composition changes during cooling of duplex stainless steel during TIG welding using laser-induced breakdown spectroscopy (LIBS) N2 - Duplex stainless steels (DSS) are frequently used, especially in applications requiring high strength combined with high corrosion resistance in aggressive media. Examples include power plant components and maritime structures. During welding of these steels, local variations in chemical composition can occur. This results in ferritization of the material and negatively affects the mechanical properties of the components. In this work, tungsten inert gas (TIG) welding experiments were performed with DSS. Chemical composition analysis was realized in situ by using Laser Induced Breakdown Spectroscopy (LIBS). The aim of the work is to quantitatively measure the chemical composition in the weld seam of various DSS and to identify possible influences of welding parameters on the microstructure of the material. The chemical concentrations of the main alloying elements Cr, Ni, Mn on the surface of the sample during the welding process and the cooling process were measured. Mn and Ni are austenite stabilizers and their content increases during welding by using certain high alloyed filler material. Spectra were recorded every 1.3 s at a spacing of approximately 2 mm. During the cooling process the location of the measurement was not changed. The LIBS method is proofed to be suitable for the quantitative representation of the chemical compositions during the welding process. T2 - MSE 2022 CY - Darmstadt, Germany DA - 27.09.2022 KW - LIBS KW - In situ measurement KW - Duplex stainless steel KW - TIG welding PY - 2022 AN - OPUS4-55922 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Quackatz, Lukas A1 - Griesche, Axel A1 - Kannengießer, Thomas A1 - Treutler, K. A1 - Gehling, T. A1 - Eissel, A. A1 - Wesling, V. T1 - In situ Messung der chemischen Konzentration in der Schmelze während des WIG-Schweißens von Duplexstählen N2 - Duplexstähle besitzen ein zweiphasiges Gefüge und werden aufgrund ihrer verbesserten Schweißeignung gegenüber den Vollausteniten häufig im Anlagen- bzw. Apparatebau eingesetzt. Aufgrund der hohen Abkühlgeschwindigkeit und dem Abbrand von Legierungselementen kommt es zu einer Ferritisierung des Schweißguts und damit zu einer Degradation der mechanischen Eigenschaften. Zur Vorhersage des Phasenverhältnisses im Schweißgut wird das WRC1992-Diagramm genutzt. Dieses Diagramm zeigt einige Ungenauigkeiten und benötigt zur genaueren Vorhersage der Phasenverhältnisse eine Überarbeitung. Um den Einfluss einzelner Elemente auf das Schweißnahtmikrogefüge besser zu verstehen, wurden drahtförmige Schweißzusatzwerkstoffe mit dem Ferrit-Bildner Nb und dem Austenit-Bildner Cu beschichtet und für Schweißungen verwendet. Die Messmethode der Laser-induzierten Plasmaspektroskopie (LIBS) bietet hier eine gute Möglichkeit der in situ Überwachung der chemischen Konzentrationen, während des WIG-Schweißens von Duplexstählen. Die LIBS-Messergebnisse, konnten mit der Ferritnummer und der Schweißnahtmikrostruktur korreliert werden. T2 - Symposium Materialtechnik der TU Clausthal CY - Clausthal-Zellerfeld, Germany DA - 23.02.2023 KW - LIBS KW - In situ measurement KW - WRC 1992 diagram KW - Dduplex stainless steel KW - TIG welding PY - 2023 VL - 12 SP - 612 EP - 627 PB - Shaker CY - Aachen AN - OPUS4-57991 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Quackatz, Lukas T1 - Analyse der chemischen Konzentrationen während des WIG-Schweißens von Duplexstählen mittels Laser induzierter Plasmaspektroskopie (LIPS) N2 - Die Kombination aus hoher Korrosionsbeständigkeit und guten mechanischen Eigenschaften von Duplexstählen (DSS) ist auf ihre chemische Zusammensetzung und das ausgewogene Phasenverhältnis von Ferrit (α) und Austenit (γ) zurückzuführen. Viele industrielle Anwendungen erfordern eine stoffschlüssige Verbindung von DSS. Das Wolfram-Inertgas-Schweißen (WIG) ist relativ einfach zu handhaben, benötigt nur wenig Platz und ermöglicht ein automatisiertes Schweißen, mit sehr hoher Reproduzierbarkeit und ist daher hervorragend zum Schweißen von DSS. Während der Erstarrung dieser Dualphasenstähle kann es zu kritischen Phasenverhältnissen von α und γ kommen, was zu Erstarrungsrissen, Korrosionsanfälligkeit, geringerer Duktilität und kritischen Festigkeitswerten führt. Um die gewünschten Werkstoffeigenschaften zu erhalten, muss daher die α/γ-Verteilung zuverlässig vorhergesagt werden. Dies geschieht in der Regel mit Hilfe des WRC1992-Diagramms. Die Vorhersagegenauigkeit des Ferritgehalts in diesem Diagramm ist jedoch meist nicht genau genug und muss daher optimiert werden. Daher ist es notwendig, selbst kleinste Veränderungen in der chemischen Zusammensetzung des Schweißguts idealerweise während des Schweißens zu überwachen. Dies wird in diesen Experimenten mit Hilfe der laser-induzierten Plasmaspektroskopie (LIBS) durchgeführt. Ein großer Vorteil dieser Technik ist die hochgenaue zeit- und ortsaufgelöste Messung der chemischen Zusammensetzung während des Schweißens. In vorherigen Arbeiten wurde bereits die chemische Zusammensetzung im Schweißgut und der WEZ quantifiziert. In der präsentierten Untersuchung wird der Einfluss einzelner Elemente, wie Nb und Cu, auf das resultierende Schweißmikrogefüge untersucht. T2 - BMDK der Universität Magdeburg CY - Magdeburg, Germany DA - 05.07.2023 KW - LIBS KW - In situ measurement KW - WRC 1992 diagram KW - TIG welding KW - Duplex stainless steels PY - 2023 AN - OPUS4-57873 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Quackatz, Lukas T1 - Measurement of hydrogen concentration in steel using Laser-induced Breakdown spectroscopy (LIBS) N2 - Currently, the ISO 3690 standard requires a thermal activation of the diffusible hydrogen in weld metal for the subsequent ex situ concentration measurement by TDS. Laser-induced breakdown spectroscopy (LIBS) would offer a time and spatially resolved, almost non-destructive, measurement of hydrogen at surfaces. We could already show that this analysis technique allows for highly accurate in situ measurements of chemical compositions of e.g. Mn, Cr and Ni during welding e.g. in the melt pool, the weld metal or the heat affected zone. For quantitative LIBS measurements of hydrogen in steel, certified reference materials with different hydrogen concentrations were used for calibration. There is a significant problem in welding steels: A critical combination of diffusible hydrogen, hardness microstructure and weld residual stresses can cause cold cracks to form in the weld microstructure. We investigated hydrogen in steels, which was loaded either electrochemically or with high-pressure hydrogen gas. Subsequently, various experiments were conducted to verify the feasibility of hydrogen measurements with LIBS. For example, depth profiles of hydrogen distribution could be obtained. Furthermore, samples were water jet cut and a line scan was made over the cross section to obtain a spatially resolved representation of the hydrogen. Total hydrogen concentrations were determined using carrier gas hot extraction. Our results show that LIBS is a promising technique for time and spatially resolved measurement of hydrogen in steels. T2 - IIW Annual Assembly 2023 CY - Singapore DA - 16.07.2023 KW - LIBS KW - Hydrogen measurement KW - Welding KW - Stainless steel PY - 2023 AN - OPUS4-57989 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Quackatz, Lukas T1 - In situ Messung chemischer Konzentrationen im Schmelzbad von Duplexstählen während des WIG-Schweißens N2 - Die Kombination aus hoher Korrosionsbeständigkeit und guten mechanischen Eigenschaften von Duplexstählen (DSS) ist auf ihre chemische Zusammensetzung und das ausgewogene Phasenverhältnis von Ferrit (α) und Austenit (γ) zurückzuführen. Viele industrielle Anwendungen erfordern eine stoffschlüssige Verbindung von DSS. Das Wolfram-Inertgas-Schweißen (WIG) ist relativ einfach zu handhaben, benötigt nur wenig Platz und ermöglicht ein automatisiertes Schweißen, mit sehr hoher Reproduzierbarkeit und ist daher hervorragend zum Schweißen von DSS. Während der Erstarrung dieser Dualphasenstähle kann es zu kritischen Phasenverhältnissen von α und γ kommen, was zu Erstarrungsrissen, Korrosionsanfälligkeit, geringerer Duktilität und kritischen Festigkeitswerten führt. Um die gewünschten Werkstoffeigenschaften zu erhalten, muss daher die α/γ-Verteilung zuverlässig vorhergesagt werden. Dies geschieht in der Regel mit Hilfe des WRC1992-Diagramms. Die Vorhersagegenauigkeit des Ferritgehalts in diesem Diagramm ist jedoch meist nicht genau genug und muss daher optimiert werden. Daher ist es notwendig, selbst kleinste Veränderungen in der chemischen Zusammensetzung des Schweißguts idealerweise während des Schweißens zu überwachen. Dies wird in diesen Experimenten mit Hilfe der laser-induzierten Plasmaspektroskopie (LIBS) durchgeführt. Ein großer Vorteil dieser Technik ist die hochgenaue zeit- und ortsaufgelöste Messung der chemischen Zusammensetzung während des Schweißens. In vorherigen Arbeiten wurde bereits die chemische Zusammensetzung im Schweißgut und der WEZ quantifiziert. In der präsentierten Untersuchung wird der Einfluss einzelner Elemente, wie Nb und Cu, auf das resultierende Schweißmikrogefüge untersucht. T2 - BMDK der Universität Magdeburg CY - Magdeburg, Germany DA - 08.11.2023 KW - LIBS KW - In situ measurement KW - Duplex stainless steel KW - TIG welding KW - Calibration free PY - 2023 AN - OPUS4-58777 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Quackatz, Lukas A1 - Griesche, Axel A1 - Nietzke, Jonathan A1 - Kannengießer, Thomas T1 - In situ measurement of hydrogen concentration in steel using laser‑induced breakdown spectroscopy (LIBS) N2 - The ISO 3690 standard “Determination of hydrogen content in arc weld metal” requires a thermal activation of the diffusible hydrogen in a piece of weld metal for the subsequent ex situ concentration measurement by carrier gas hot extraction CGHE or thermal desorption spectroscopy (TCD). Laser-induced breakdown spectroscopy (LIBS) offers a time and spatially resolved, almost non-destructive, in situ measurement of hydrogen at surfaces without sample preparation. We measured hydrogen in steels, which were charged either electrochemically or by high-pressure hydrogen gas, and compared the results. Further, the feasibility of quantitative hydrogen line scan measurements with LIBS was demonstrated by measuring hydrogen at water jet cut surfaces. The hydrogen concentrations measured with the help of LIBS were compared with CGHE measurements. It was observed that hydrogen can be reliably measured with LIBS for concentrations larger than 2 wt.-ppm. The maximum hydrogen concentration achieved using electrochemical charging was 85.1 ppm. The results show that LIBS is a promising technique for time- and spatially resolved measurements of hydrogen in steels. T2 - IIW Annual Assembly 2023 CY - Singapore KW - LIBS KW - Hydrogen measurement KW - Welding KW - Stainless steel KW - Diffusible hydrogen PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-593664 DO - https://doi.org/10.1007/s40194-023-01677-2 SP - 1 EP - 9 PB - Springer AN - OPUS4-59366 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Quackatz, Lukas A1 - Gornushkin, Igor B. A1 - Griesche, Axel A1 - Kannengießer, Thomas A1 - Treutler, Kai A1 - Wesling, Volker T1 - In situ chemical analysis of duplex stainless steel weld by laser induced breakdown spectroscopy N2 - The high corrosion resistance and good mechanical properties of duplex stainless steel (DSS) are due to its special chemical composition, which is a balanced phase ratio of ferrite (α) and austenite (γ). Many industrial applications require the integration of DSS components. For this, Gas tungsten arc welding (GTAW) is an excellent choice, as it allows an automated operation with high reproducibility. However, when the weld pool solidifies, critical ratios of α- and γ- phases can occur, which lead to solidification cracking, increased susceptibility to corrosion, and a decrease in ductility and critical strength. Previous studies have shown that these defects can be caused by the accumulation of manganese and chromium in the heat affected zone (HAZ), requiring ongoing monitoring of this accumulation. A suitable method for such monitoring is laser-induced breakdown spectroscopy (LIBS), which can be used in two operating modes: calibration using standard reference samples and calibration-free. Unlike conventional quantitative LIBS measurements, which require reference samples to generate a calibration curve, calibration-free LIBS (CF-LIBS) allows chemical compositions to be determined solely from the emission spectrum of the plasma. Numerous publications show that CF-LIBS is a fast and efficient analytical method for the quantitative analysis of metal samples. In this work, CF-LIBS is applied to spectra obtained during GTAW DSS welding and the result is compared with those obtained by PLS analysis. A good correlation was found between both types of analysis, demonstrating the suitability of the CF-LIBS method for this application. The CF-LIBS method has a significant advantage over conventional LIBS due to the rapid in situ measurement of concentrations of major alloying elements without calibration procedure. This, combined with fast feedback and appropriate adjustment of welding parameters, helps prevent welding defects. KW - Duplex stainless steels KW - In situ measurement KW - LIBS KW - GMAW PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-597940 DO - https://doi.org/10.1016/j.sab.2024.106899 SN - 0584-8547 VL - 214 SP - 1 EP - 7 PB - Elsevier B.V. AN - OPUS4-59794 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Quackatz, Lukas A1 - Westin, Elin Marianne A1 - Griesche, Axel A1 - Kromm, Arne A1 - Kannengießer, Thomas A1 - Treutler, Kai A1 - Wesling, Volker A1 - Wessman, Sten T1 - Assessing ferrite content in duplex stainless weld metal: WRC ‘92 predictions vs. practical measurements N2 - AbstractThe weldability of stainless steels is largely controlled by the chemical composition, and alloys with ferritic or ferritic-austenitic solidification show the highest resistance to hot cracking. As the resulting phase balance also affects the final properties, it may be beneficial to both foresee and measure the weld metal ferrite content. The WRC ‘92 constitution diagram is currently the most accurate prediction tool available, but it does not take the cooling rate into consideration and the precision may be less accurate for stainless steels with high ferrite numbers (FNs). This study aims to assess the reliability of the WRC ‘92 diagram for weld metals with FN  50. The chemical composition was altered through gas tungsten arc welding (GTAW) of UNS S32205 with ER347 filler wire that had been coated using physical vapor deposition (PVD) with either niobium (Nb), copper (Cu), nickel (Ni), manganese (Mn), carbon (C), or silicon (Si). The actual ferrite content was evaluated using image analysis, FeriteScope and X-ray diffraction (XRD). While predictions from the WRC ‘92 diagram were deemed acceptable for Ni, Si, and Mn, notable deviations were observed for Nb, Cu, and C. The FeriteScope exhibited a consistent trend with image analysis, albeit with slightly higher FN values, wider scatter, and the conversion factor from FN to vol% is open for discussion. The lowest accuracy and largest spread were obtained using non-contact XRD, rendering it unsuitable for ferrite measurements of welds. These findings underscore the need for improved prediction tools and appropriate measurement methods for assessing ferrite content in duplex weld metals. KW - Duplex stainless steel KW - Welding KW - Phase balance KW - Microscopy KW - Microstructure PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-618777 DO - https://doi.org/10.1007/s40194-024-01878-3 SN - 1878-6669 VL - 69 IS - 1 SP - 31 EP - 45 PB - Springer CY - Berlin AN - OPUS4-61877 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Quackatz, Lukas A1 - Westin, Elin Marianne A1 - Griesche, Axel A1 - Kromm, Arne A1 - Kannengießer, Thomas A1 - Treutler, Kai A1 - Wesling, Volker A1 - Wessman, Sten T1 - Assessing ferrite content in duplex stainless weld metal: WRC ‘92 predictions vs. practical measurements N2 - AbstractThe weldability of stainless steels is largely controlled by the chemical composition, and alloys with ferritic or ferritic-austenitic solidification show the highest resistance to hot cracking. As the resulting phase balance also affects the final properties, it may be beneficial to both foresee and measure the weld metal ferrite content. The WRC ‘92 constitution diagram is currently the most accurate prediction tool available, but it does not take the cooling rate into consideration and the precision may be less accurate for stainless steels with high ferrite numbers (FNs). This study aims to assess the reliability of the WRC ‘92 diagram for weld metals with FN  50. The chemical composition was altered through gas tungsten arc welding (GTAW) of UNS S32205 with ER347 filler wire that had been coated using physical vapor deposition (PVD) with either niobium (Nb), copper (Cu), nickel (Ni), manganese (Mn), carbon (C), or silicon (Si). The actual ferrite content was evaluated using image analysis, FeriteScope and X-ray diffraction (XRD). While predictions from the WRC ‘92 diagram were deemed acceptable for Ni, Si, and Mn, notable deviations were observed for Nb, Cu, and C. The FeriteScope exhibited a consistent trend with image analysis, albeit with slightly higher FN values, wider scatter, and the conversion factor from FN to vol% is open for discussion. The lowest accuracy and largest spread were obtained using non-contact XRD, rendering it unsuitable for ferrite measurements of welds. These findings underscore the need for improved prediction tools and appropriate measurement methods for assessing ferrite content in duplex weld metals. KW - Duplex stainless steel KW - Phase fraction prediction KW - WRC diagram PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-623682 DO - https://doi.org/10.1007/s40194-024-01878-3 VL - 69 SP - 31 EP - 45 PB - Springer Science and Business Media LLC AN - OPUS4-62368 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -