scholarly journals Hybrid laser-arc welding of laser- and plasma-cut 20-mm-thick structural steels

Ömer Üstündağ ◽  
Nasim Bakir ◽  
Sergej Gook ◽  
Andrey Gumenyuk ◽  
Michael Rethmeier

AbstractIt is already known that the laser beam welding (LBW) or hybrid laser-arc welding (HLAW) processes are sensitive to manufacturing tolerances such as gaps and misalignment of the edges, especially at welding of thick-walled steels due to its narrow beam diameter. Therefore, the joining parts preferably have to be milled. The study deals with the influence of the edge quality, the gap and the misalignment of edges on the weld seam quality of hybrid laser-arc welded 20-mm-thick structural steel plates which were prepared by laser and plasma cutting. Single-pass welds were conducted in butt joint configuration. An AC magnet was used as a contactless backing. It was positioned under the workpiece during the welding process to prevent sagging. The profile of the edges and the gap between the workpieces were measured before welding by a profile scanner or a digital camera, respectively. With a laser beam power of just 13.7 kW, the single-pass welds could be performed. A gap bridgeability up to 1 mm at laser-cut and 2 mm at plasma-cut samples could be reached respectively. Furthermore, a misalignment of the edges up to 2 mm could be welded in a single pass. The new findings may eliminate the need for cost and time-consuming preparation of the edges.

2022 ◽  
Vol 101 (1) ◽  
pp. 15-26

The application of hybrid laser-arc welding (HLAW) for joining closed circumferential welds is a challenge due to the high risk of forming a defective overlap area with a shrinkage void or solidification cracks in the material thickness. A series of HLAW experiments were performed to understand the development of a faulty overlap area when closing the circumferential weld. Welding trials on flat specimens and pipe segments were supported by numerical analyses in which the thermomechanical behavior of the welds in the overlap area was investigated. Different process control strategies were tested, including variations in defocusing levels and the overlap length. The newly developed HLAW head, including laser optics with a motor-driven collimation system, made it possible to defocus the laser beam during welding without disturbing the stability of the welding process. High-level defocusing of the laser beam of more than 40 mm relative to the specimen surface with a resulting beam diameter of > 2.9 mm, and in combination with a short overlap length of 15 mm, was promising with respect to the formation of a desired cup-shaped weld profile that is resistant to solidification cracks.

2022 ◽  
Rafael Gomes Nunes Silva ◽  
Max Baranenko Rodrigues ◽  
Milton Pereira ◽  
Koen Faes

Abstract Welding processes are present in all sectors of the industry, highlighting the manufacturing industry of thick plates and pipelines. In these applications, welding processes have a major influence on costs, schedules, risk analysis and project feasibility. Conventional arc welding processes, such as the gas metal arc welding (GMAW) process, have limitations when applied to high thickness joints due to their maximum achievable penetration depth. On the other hand, the laser beam welding (LBW) welding process, despite reaching high penetration depths, has several limitations mainly regarding the geometric tolerance of the joint. In this regard, the hybrid laser-arc welding (HLAW) process emerges as a promising bonding process, combining the advantages of the GMAW and LBW processes into a single melting pool. Despite the many operational and metallurgical advantages, the HLAW process presents a high complexity due to the high number of parameters involved and the interaction between the laser beam and the electric arc. The present work discusses the challenges involved in the parametrization of the HLAW process applied to the joining of thick plates and pipes, and empirically evaluated a comparison between the HLAW and GMAW processes, showing a reduction of operating time of approximately 40 times, and a reduction of consumption of shielding gas and filler material of approximately 20 times, evidencing the technical and financial contribution of the hybrid process.

D Wallerstein ◽  
E Vaamonde ◽  
A Prada ◽  
EA Torres ◽  
SL Urtiga Filho ◽  

Hybrid Laser-Arc Welding (HLAW) is a relatively new joining technique that combines advantages from both laser beam welding and arc welding. The interaction between laser beam and arc welding provides advantageous synergic effects, especially for thick joints. On the other hand, this interaction brings extra complexity to HLAW, limiting its acceptance in industry. Therefore, it is still necessary to elucidate some features of HLAW, such as the influence of parameters and consumables on the characteristics of the resulting joints. In the present study, the effects of welding gases (Ar + CO2 in different proportions) and filler metals (solid and flux-cored wires) on thick S355 structural steel joints are assessed. The best welds in terms of geometric characteristics, microstructures, and mechanical behavior were fabricated with high CO2 content welding gases and flux-cored welding wires. The use of flux-cored wires promoted higher penetration, lower hardness, and formation of acicular ferrite, avoiding the formation of martensite encountered in joints welded with solid wires. Moreover, the application of flux-cored wires could lead to cost savings in future applications, by reducing the laser power required to produce sound joints.

2022 ◽  
Vol 9 ◽  
Donato Coviello ◽  
Antonio D’Angola ◽  
Donato Sorgente

Keyhole laser welding is the benchmark for deep-penetration joining processes. It needs high incident laser beam power densities at the workpiece surface to take place. The gaseous phase plays a fundamental role to keep the deep and narrow keyhole cavity open during the process. The plasma created in this process is a mixture of ionized metal vapors and the environmental gas and it develops inside the keyhole (keyhole plasma) and above the workpiece surface (plasma plume). The presence of plasma implicates absorption, scattering, and refraction of laser beam rays. These phenomena alter the power density of the laser beam irradiating the workpiece surface and thus affect the resulting welding process. In this work, a mathematical and numerical model has been developed to calculate the keyhole shape taking into account the plasma absorption effects. The model considers the keyhole walls as the liquid-vapor interface and computes the keyhole geometry applying a local energy balance at this interface. In addition, the model takes into account the multiple reflections effects inside the cavity through an iterative ray-tracing technique, and calculates the absorption mechanism due to inverse Bremsstrahlung for each ray along its segmented path inside the keyhole. Results show the effect of plasma properties on the keyhole shape and depth.

2021 ◽  
pp. 131384
Morteza Taheri ◽  
Amirreza Kazemi ◽  
P. Gurusamy ◽  
Arash Rasoulpouraghdam ◽  
V. Mohanavel ◽  

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