Abstract This paper showcases how a holistic approach to digitalisation enables data-driven welding applications, exemplarily for a gas metal arc welding (GMAW) laboratory. The workflow integrates advanced process monitoring, synchronised multi-sensor data acquisition and tools for data analytics. A welding domain-specific data exchange format weldx is presented that unifies and aggregates the data sets acquired during process monitoring with final component quality metrics, supporting reuse, traceability, and reproducibility. Two case studies illustrate the approach. First, GMAW parameters are adaptively adjusted according to local seam geometry to compensate joint-preparation deviations from nominal values typical for large-scale steel fabrication. Second, the seamless data aggregation along the welding production chain enables an automatic life-cycle assessment (LCA), quantifying the environmental impacts of additive manufacturing with DED Arc/M and attributing the dominant contributors to the carbon footprint. Collectively, the results indicate that a fully integrated experimental set-up together with standardised data structures and scalable analytics can couple monitoring, control, and sustainability, thereby realising the potential of digitalisation for high-quality and environmentally informed welding production.

Tandem gas metal arc welding (T-GMAW) utilizes simultaneous deposition from two wires to enhance the productivity for joining thick sections. Current knowledge on the actual energy consumption vis-à-vis filler wire deposition rate in T-GMAW is limited. We present here a detailed investigation on multi-pass single V-groove T-GMAW of a 30 mm thick structural steel plate with real-time monitoring of current, voltage and metal transfer modes for both filler wires. A novel electrical deposition efficiency (EDE) metric is realized using measured current and voltage transients to correlate electrical energy usage with the deposition rate. For a constant wire feed rate, the short-circuiting metal transfer mode resulted in much lesser energy input and 50% higher EDE in comparison to the pulsed mode of metal transfer.

A novel, event-driven approach to controlling the weaving motion in swing arc narrow gap GMAW is presented in this study. The control method is based on independently detecting the arc attachment event at each sidewall of the narrow groove to adjust the weaving motion in real time. Previous arc sensing approaches for swing arc principles are based on evaluating and comparing arc sensor readings collected during the dwell periods at each sidewall. Not only does this require the torch to be positioned at the groove centre and the arc motion to be symmetric, but previous methods have also been shown to rely on complex parametrization of control parameters. The newly presented approach is based on the real-time monitoring of the welding current progression during the approach of the arc towards the sidewall of the groove independently on each side. As soon as the arc attachment at the sidewall is detected based on a characteristic rise in the current signal, the weaving motion is stopped. For reference experiments in a 21-mm wide groove, the weaving angle amplitude is controlled and limited to 50° on both sides individually, resulting in stable process conditions and uniform sidewall fusion. It is further shown that the newly developed control method can successfully be applied to groove widths of 18 mm and 24 mm without reconfiguration of the control parameters, highlighting the flexibility of the approach.

Wire arc directed energy deposition (DED-Arc) is an emerging metal additive manufacturing process to build near-net shaped metallic parts in a layer-by-layer with minimal material wastage. Automated in situ monitoring and fast-responsive analyses of process signatures and deposit profiles during DED-Arc are in ever demand to print dimensionally consistent parts and reduce post-deposition machining. A comprehensive experimental investigation is presented here involving real-time synchronous measurement of arc current, voltage, and the deposit profile using a novel multi-sensor monitoring framework integrated with the DED-Arc set-up. The recorded current–voltage transients are used to estimate the time-averaged arc power, and energy input in real time for an insight of the influence of wire feed rate and printing travel speed on the deposit characteristics. A unique attempt is made to represent the geometric profiles of the single-track deposits in a generalized mathematical form corresponding to a segmented ellipse, which has exhibited the minimum root-mean-square error of 0.03 mm. The dimensional inconsistency of multi-track deposits is evaluated quantitatively in terms of waviness using build profile monitoring and automated estimation, which is found to increase with an increase in step-over ratio and energy input. For the multi-track mild steel deposits, the suitable range of step-over ratio for the minimum surface waviness is observed to lie between 0.6 and 0.65. Collectively, the proposed framework of synchronized process monitoring and real-time analysis provides a pathway to achieve dimensionally consistent and defect-free parts, and highlights the potential for closed-loop control systems for a wider industrial application of DED-Arc.

Despite the advances in hardware and software techniques, standard numerical methods fail in providing real-time simulations, especially for complex processes such as additive manufacturing applications. A real-time simulation enables process control through the combination of process monitoring and automated feedback, which increases the flexibility and quality of a process. Typically, before producing a whole additive manufacturing structure, a simplified experiment in the form of a bead-on-plate experiment is performed to get a first insight into the process and to set parameters suitably. In this work, a reduced order model for the transient thermal problem of the bead-on-plate weld simulation is developed, allowing an efficient model calibration and control of the process. The proposed approach applies the proper generalized decomposition (PGD) method, a popular model order reduction technique, to decrease the computational effort of each model evaluation required multiple times in parameter estimation, control, and optimization. The welding torch is modeled by a moving heat source, which leads to difficulties separating space and time, a key ingredient in PGD simulations. A novel approach for separating space and time is applied and extended to 3D problems allowing the derivation of an efficient separated representation of the temperature. The results are verified against a standard finite element model showing excellent agreement. The reduced order model is also leveraged in a Bayesian model parameter estimation setup, speeding up calibrations and ultimately leading to an optimized real-time simulation approach for welding experiment using synthetic as well as real measurement data.

The high amount of resource consumption of fusion welding processes offers the potential to reduce their environmental impact. While the driving forces are known from a qualitative perspective, the quantitative assessment of the crucial parameters is not a trivial task. Therefore, herein, a welding‐specific methodology to utilize life cycle assessment as a tool for evaluating the environmental impact of fusion welding processes is presented. In this context, two welding processes, resistance spot welding and laser beam welding, are analyzed for two different use cases. These comprise the welding of shear test specimens and a cap profile made of electrogalvanized sheets of DC 05 + ZE (1.0312) as representative of an automotive application. For both welding processes, the main influences on the resulting environmental impact categories are evaluated and compared. The requirements for ecological efficient welding processes are discussed and implemented.

The increasing adoption of Open Science principles has been a prevalent topic in the welding science community over the last years. Providing access to welding knowledge in the form of complex and complete datasets in addition to peer-reviewed publications can be identified as an important step to promote knowledge exchange and cooperation. There exist previous efforts on building data models specifically for fusion welding applications; however, a common agreed upon implementation that is used by the community is still lacking. One proven approach in other domains has been the use of an openly accessible and agreed upon file and data format used for archiving and sharing domain knowledge in the form of experimental data. Going into a similar direction, the welding community faces particular practical, technical, and also ideological challenges that are discussed in this paper. Collaboratively building upon previous work with modern tools and platforms, the authors motivate, propose, and outline the use of a common file format specifically tailored to the needs of the welding research community as a complement to other already established Open Science practices. Successfully establishing a culture of openly accessible research data has the potential to significantly stimulate progress in welding research.

Der Einsatz von Aluminiumlegierungen als Konstruktionswerkstoff hat in den letzten Jahren stetig zugenommen. Insbesondere hoherfeste Aluminiumlegierungen, wie die Vertreter der 6000’er Aluminiumgruppe, rucken Aufgrund ihres hervorragenden Festigkeits- / Gewichtsverhaltnisses immer mehr in den Fokus. Vertreter dieser Aluminiumklasse, die als Hauptlegierungselemente Magnesium und Silizium beinhalten, weisen neben der bei allen Aluminiumlegierungen prasenten Affinitat zur Porenbildung zusatzlich eine ausgepragte Heisrissanfalligkeit auf. Die additive Verarbeitung von Al-Mg-Si-Legierungen mittels MSG Verfahren gestaltet sich daher herausfordernd. Neben der Schweiseignung ist die geometrische Gestalt der Schweisraupe fur die additive Fertigung von entscheidender Bedeutung. Spurbreite und Spurhohe sind masgebliche Grosen, die bei der Pfadgenerierung im Hinblick auf Endkonturnahe und der Vermeidung von Unganzen, Poren und Bildefehlern zu beachten sind. Dieser Beitrag zeigt am Beispiel des Wire Arc Additive Manufacturing von Al-Mg-Si-Legierungen einen Ansatz, mit dem es moglich ist, zeit- und kostenintensive vollfaktorielle Parameterstudien zum Erhalt von Spurgeometrie und Schweisqualitat durch dynamische Parameterstudien zu ersetzen.

Wire arc additive manufacturing enables the production of near-net shape large-volume metallic components leveraging an established industrial base of welding and cladding technology and adapting it for layer-wise material deposition. However, the complex relationship between the process parameters and resulting mechanical properties of the components still remains challenging. In case of high-strength Al-Mg-Si aluminum alloys, no commercial filler wires are yet available due the high susceptibility of solidification cracking as well as the necessary efforts to obtain acceptable mechanical properties. To address this need, we evaluated a novel filler wire based on AlMg0.7Si doped with a Ti5B1 master alloy to foster fine equiaxed grains within the deposited metal. The correlation between the process parameters and component quality was examined by analyzing the size and distribution of pores as well as the grain morphology. Furthermore, we evaluated the influence of different post-weld heat treatment strategies to achieve mechanical properties corresponding to the reference wrought material. We demonstrated that fine equiaxed grains in the weld metal reduced the susceptibility of solidification cracking significantly. The novel AlMg0.7Si-TiB (S Al 6063-TiB) filler wire facilitated wire arc additive manufacturing of high-strength aluminum components with mechanical properties that were almost as superior as the corresponding wrought base material.

Darstellung der aktuellen Situation sowie des Potenzials von Forschungsdatenmanagement und OpenScience in der Schweistechnik.

The development within the offshore wind sector towards more powerful turbines combined with increasing water depth for new wind parks is challenging both the designer as well as the manufacturer of bottom fixed support structures. Besides XL-monopiles, the market developed an innovative and economic jacket support structure which is based on automatically manufactured tubular joints combined with standardized pipes. Besides the improvements for a serial manufacturing process the automatically welded tubular joints show a great potential in terms of fatigue resistance e.g. due to a smooth weld geometry without sharp notches. However, these benefits are not considered yet within the fatigue design process of automatically manufactured jacket substructures according to current standards due to the lack of suitable S-N curves. Therefore, 32 axial fatigue tests on single and double-sided automatically welded tubular X-joints have been performed to determine a new hot spot stress related S-N curve. Based on these constant amplitude fatigue tests a new S-N curve equal to a FAT 126 curve was computed which implicitly includes the benefits of the automatically welding procedure.

Kleinere und mittlere Unternehmen agieren heutzutage in einem globalen Umfeld, wodurch diese zu Elementen einer komplexen Wertschopfungskette werden. Der zunehmende Anstieg der Preise fur industriell essenzielle Ressour-cen, wie Primarenergie und Rohstoffe, sowie sich ausweitende klimapolitische Restriktion fuhren zur Notwendigkeit, die Wettbewerbsfahigkeit durch innovative und okoeffiziente Fertigungsprozesse langfristig zu sichern. Rahmenbe-dingungen zu schaffen, welche die Positionierung nachhaltiger Produkte und Prozesse innerhalb globaler Wert-schopfungsketten ermoglicht, ist daher ein wesentliches Ziel der deutschen Industriepolitik [1, 2]. Im Rahmen dieses Beitrages werden aktuelle Forschungsarbeiten zur Bewertung der Umweltwirkungen der schweis-technischen Fertigungskette anhand ausgewahlter Schmelzschweisverfahren unter Berucksichtigung vor- sowie nachgelagerter Fertigungsschritte dargestellt. Das hierzu notwendige Element zur Analyse der Fertigungsprozesse ist die Okobilanzierung - eine weit verbreitete und standardisierte Methode zur Abschatzung der Umweltwirkungen eines Produktes oder Prozesses. Hierbei stellt die Sachbilanzierung, d.h. die Ermittlung samtlicher relevanter Ener-gie- und Ressourcenverbrauche wahrend der schweistechnischen Fertigung, aufgrund des hohen Dokumentations-aufwandes sowie Ableitung assoziierter Wirkkategorien das groste Hindernis fur eine Etablierung und Akzeptanz der Okobilanzierung in der Praxis dar. Gleichwohl wird seitens Unternehmen, welche als Zulieferer von OEM’s agieren, die Dokumentation des fertigungsspezifischen CO2-Verbrauches gefordert. Ein weiterer Aspekt der Arbeiten beinhaltet folglich Methoden zur automatisierten Erfassung von schweistechnischen Produktionsdaten sowie deren Nachverfolgbarkeit aufzuzeigen. Anhand unterschiedlicher Schweisverfahren werden die aus den Produktionsdaten abgeleiteten Energie- und Ressourcenverbrauche automatisiert in den relevanten Umweltwirkungen uberfuhrt. Die analysierten Schweisprozesse umfassen dabei ein breites fur kmU relevantes Spektrum. Durch die softwareseitige Bereitstellung der aufgestellten Umweltprofile ist der Anwender in der Lage, Schweisprozesse unter okologischen Aspekten zu bewerten und die effizienteste Variante zu identifizieren.

ABSTRACTTo increase the competitiveness of jacket substructures compared to monopiles a changeover from an individual towards a serial jacket production based on automated manufactured tubular joints combined with standardized pipes has to be achieved. Therefore, this paper addresses fatigue tests of automatically welded tubular X‐joints focusing on the location of the technical fatigue crack. The detected location of the technical crack is compared to numerical investigations predicting the most fatigue prone notch considering the structural stress approach as well as the notch stress approach. Besides, the welding process of the automated manufactured tubular X‐joints is presented.

Abstract Resistance spot welding (RSW) is widely used in the automotive industry as the main joining method. Generally, an automotive body contains around 2000 to 5000 spot welds. Therefore, it is of decisive importance to characterize the mechanical properties of these areas for the further optimization and improvement of an automotive body structure. The present paper aims to introduce a novel method to investigate the mechanical properties and microstructure of the resistance spot weldment of DP1000 sheet steel. In this method, the microstructure of RSW of two sheets was reproduced on one sheet and on a bigger area by changing of the welding parameters, e. g. welding current, welding time, electrode force and type. Then, tensile tests in combination with digital image correlation (DIC) measurement were performed on the notched tensile specimens to determine the mechanical properties of the weld metal. The notch must be made on the welded tensile specimen to force the fracture and elongation on the weld metal, enabling the characterization of its properties. Additionally, the parameters of a nonlinear isotropic material model can be obtained and verified by the simulation of the tensile specimens. The parameters obtained show that the strength of DP1000 steel and the velocity of dislocations for reaching the maximum value of strain hardening, are significantly increased after RSW. The effect of sample geometry and microstructural inhomogeneity of the welded joint on the constitutive property of the weld metal are presented and discussed.

To increase the competitiveness of jacket substructures compared to monopiles a changeover from an individual towards a serial jacket production based on automated manufactured tubular joints combined with standardized pipes has to be achieved. Therefore, this paper addresses fatigue tests of automatically welded tubular X-joints focusing on the location of the technical fatigue crack. For this X-joint, the detected location of the technical crack is then compared to numerical investigations predicting the most fatigue prone notch considering the structural stress approach as well as the notch stress approach. Additionally, the fatigue prone hot spot according to both approaches is compared for a typical offshore jacket double-K-joint to emphasize the significance of the presented outcomes for the existing offshore structures. Besides, the welding process of the automatically manufactured tubular X-joints is presented.

Das MSG-Engspaltschweisen eignet sich auf Grund der I-Nahtvorbereitung besonders fur das wirtschaftliche Fugen bei hohen Blechdicken uber 100 mm und bietet daruber hinaus zusatzliche technologische Vorteile. Fur die automatisierte Anwendung des Verfahrens unter Produktionsbedingungen muss dabei die Prozesssicherheit auch fur mitunter grose Variationen der Spaltbreite entlang der Schweisnaht gesichert bleiben. In erster Linie betrifft dies bei mechanischer Auslenkung der Drahtelektrode die Adaption der Pendelbewegung auf die jeweilige Spaltbreite um eine ausreichende Flankenanbindung zu garantieren. Fur die Online-Regelung der Pendelbewegung mittels Lichtbogensensorik wurde eine Methode implementiert die die notwendigen Pendelwinkel an jeder Nahtflanke unabhangig ermittelt und daruber hinaus Fehlstellungen des Brenners sowie Veranderungen des Kontaktrohrabstandes und der Prozessparameter eigenstandig kompensiert. Eine Fullgradregelung auf Grundlage optischer Erfassung und Auswertung der Schweisnahtgeometrie wurde zusatzlich eingesetzt um bei veranderlichen Nahtquerschnittsflachen einen vorgegebenen, gleichbleibenden Lagenaufbau zu erzielen.

AbstractDie Entwicklung in der Offshore‐Windenergie hin zu größeren, leistungsstärkeren Anlagentypen sowie die zeitgleich zunehmenden Wassertiefen der projektierten Windparks stellt u. a. Designer und Fertiger der Gründungsstrukturen der Windenergieanlagen vor wachsende Herausforderungen. Neben dem Gründungskonzept mittels XL‐Monopiles rückt auch die Jacketgründung wegen der Kombination aus dem vergleichsweise geringen Materialverbrauch bei gleichzeitig hoher Steifigkeit in den Fokus. Der Fertigungsaufwand der Jackets ist verglichen mit Monopiles groß, kann jedoch durch die Kombination aus Standardrohren mit automatisiert gefertigten Jacketknoten reduziert werden. Vor diesem Hintergrund befasst sich dieser Beitrag mit der Prozesskette der automatisierten Fertigung von Hohlprofilknoten inklusive der Digitalisierung relevanter Fertigungsparameter sowie der optischen Erfassung der Schweißnahtgeometrie durch einen Linienlaser. Des Weiteren wird eine Methodik zur Analyse der gescannten Schweißnahtgeometrie anhand von drei Referenzstellen eines X‐Knotens vorgestellt, mit der sowohl die Kerbradien als auch die Nahtanstiegswinkel bestimmt werden können. Abschließend werden die Geometrieparameter beim Ermüdungsnachweis nach dem Kerbspannungskonzept berücksichtigt und ihr Einfluss durch einen Vergleich mit dem Strukturspannungskonzept auf Basis äquivalenter Spannungskonzentrationsfaktoren quantifiziert.

In diesem Vortrag werden aktuellen Forschungsarbeiten bezuglich der Digitalisierung der schweistechnischen Fertigungskette dargestellt. Anwendungsbeispiel ist das automatisierte Schweisen von Hohlprofilknoten, welche fur die Fertigung von Jacket-Grundungsstrukturen fur Offshore Windenergieanlagen eingesetzt werden. Besonderer Fokus liegt hierbei auf der Datenubergabe an nachgelagerter Prozessschritte bzw. externe Forschungspartner. Die Ruckverfolgbarkeit des Fertigungsprozesses ermoglicht die zeitliche und raumliche Zuordnung von Prozessparametern (elektrische Signale) zu geometrischen Eigenschaften der Schweisnaht (Kerbgeometrie) bis hin zur numerisch berechneten Lebensdauer.

This study examines the relationship between the magnetic mesostructure with the microstructure of low carbon steel tungsten inert gas welds. Optical microscopy revealed variation in the microstructure of the parent material, in the heat affected and fusion zones, correlating with distinctive changes in the local magnetic stray fields measured with high spatial resolution giant magneto resistance sensors. In the vicinity of the heat affected zone high residual stresses were found using neutron diffraction. Notably, the gradients of von Mises stress and triaxial magnetic stray field modulus follow the same tendency transverse to the weld. In contrast, micro-X-ray fluorescence characterization indicated that local changes in element composition had no independent effect on magnetic stray fields.

An approach to develop an arc sensor for gap width estimation during automated NG-GMAW with a weaving electrode motion is introduced by combining arc sensor readings with optical measurements of the groove shape to allow precise analyses of the process. The two test specimen welded for this study were designed to feature a variable groove geometry in order to maximize efficiency of the conducted experimental efforts, resulting in 1696 individual weaving cycle records with associated arc sensor measurements, process parameters and groove shape information. Gap width was varied from 18 mm to 25 mm and wire feed rates in the range of 9 m/min to 13 m/min were used in the course of this study. Artificial neural networks were applied as a modelling tool to derive an arc sensor for estimation of gap width suitable for online process control that can adapt to changes in process parameters as well as changes in the weaving motion of the electrode. Wire feed rate, weaving current, sidewall dwell currents and angles were defined as inputs to calculate the gap width. The evaluation of the proposed arc sensor model shows very good estimation capabilities for parameters sufficiently covered during the experiments.