scholarly journals Local Shielding Gas Supply in Remote Laser Beam Welding

2021 ◽  
Vol 5 (4) ◽  
pp. 139
Author(s):  
Klaus Schricker ◽  
Andreas Baumann ◽  
Jean Pierre Bergmann
Keyword(s):  
Laser Beam ◽  
High Speed ◽  
Flow Direction ◽  
Laser Beam Welding ◽  
Inert Gas ◽  
Deep Penetration ◽  
Geometrical Parameters ◽  
Shielding Gas ◽  
Remote Welding ◽  
Gas Supply

The use of shielding gases in laser beam welding is of particular interest for materials interacting with ambient oxygen, e.g., copper, titanium or high-alloy steels. These materials are often processed by remote laser beam welding where short welds (e.g., up to 40 mm seam length) are commonly used. Such setups prevent gas nozzles from being carried along on the optics due to the scanner application and a small area needs to be served locally with inert gas. The article provides systematic investigations into the interaction of laser beam processes and parameters of inert gas supply based on a modular flat jet nozzle. Based on the characterization of the developed nozzle by means of high-speed Schlieren imaging and constant temperature anemometry, investigations with heat conduction welding and deep penetration welding were performed. Bead-on-plate welds were carried out on stainless steel AISI 304 for this purpose using a disc laser and a remote welding system. Argon was used as shielding gas. The interaction between Reynolds number, geometrical parameters and welding/flow direction was considered. The findings were proved by transferring the results to a complex weld seam geometry (C-shape).

Laser beam welding quality monitoring system based in high-speed (10 kHz) uncooled MWIR imaging sensors

2015 ◽  
Author(s):  
Rodrigo Linares ◽  
German Vergara ◽  
Raúl Gutiérrez ◽  
Carlos Fernández ◽  
Víctor Villamayor ◽  
...  
Keyword(s):  
Laser Beam ◽  
Monitoring System ◽  
High Speed ◽  
Laser Beam Welding ◽  
Quality Monitoring ◽  
Welding Quality ◽  
Imaging Sensors

scholarly journals Characterization of Temperature Fields in Laser Beam Welded Hollow-Cylindrical Cold Crack Samples from High Strength Steel 100Cr6

2021 ◽  
Author(s):  
Eric Wasilewski ◽  
Nikolay Doynov ◽  
Ralf Ossenbrink ◽  
Vesselin Michailov
Keyword(s):  
Laser Beam ◽  
High Strength Steel ◽  
Unit Length ◽  
Laser Beam Welding ◽  
High Strength ◽  
Temperature Fields ◽  
Deep Penetration ◽  
Heating Rates ◽  
Hydrogen Distribution ◽  
Cooling Rates

Abstract This work presents a comparative study of thermal conditions that occur during laser beam welding of high strength steel 100Cr6 that often leads to a loss of technological strength and may conditionally produce cold cracks. The results from both experiments and thermal-metallurgical FE-simulations indicate that the type of heat coupling changes significantly when welding with different process parameters, e.g., in the transition between conduction and deep penetration welding. Further, the simulations show that as a result of the high welding speeds and reduced energy per unit length, extremely high heating rates of up to 2x104 K s-1 (set A) resp. 4x105 K s-1 (set B) occur in the material. Both welds thus concern a range of values for which conventional Time-Temperature-Austenitization (TTA) diagrams are not currently defined, so that the material models can only be calibrated using general assumptions. This noted change in energy per unit length and welding speeds causes significantly steep temperature gradients with a slope of approximately 5x103 K mm-1 and strong drops in the heating and cooling rates, particularly in the heat affected zone near the weld metal. This means that even short distances along the length present a staggering difference in relation to the temperature peaks. The temperature cycles also show very different cooling rates for the respective parameter sets, although in both cases they are well below a cooling time t8/5 of one second, so that the phase transformation always leads to the formation of martensite. The results from this study are intended to be used for further detailed experimental and numerical investigation of microstructure, hydrogen distribution, and stress-strain development at different restrain conditions.

scholarly journals Influence of oscillating magnetic field on the keyhole stability in deep penetration laser beam welding

2021 ◽  
Vol 135 ◽  
pp. 106715
Author(s):  
Ömer Üstündağ ◽  
Nasim Bakir ◽  
Andrey Gumenyuk ◽  
Michael Rethmeier
Keyword(s):  
Magnetic Field ◽  
Laser Beam ◽  
Laser Beam Welding ◽  
Deep Penetration ◽  
Oscillating Magnetic Field

Processing of Keyhole Depth Measurement Data during Laser Beam Micro Welding

2020 ◽  
Vol 234 (5) ◽  
pp. 722-731
Author(s):  
Sören Hollatz ◽  
Marc Hummel ◽  
Lea Jaklen ◽  
Wiktor Lipnicki ◽  
Alexander Olowinsky ◽  
...  
Keyword(s):  
Laser Beam ◽  
Data Processing ◽  
Laser Beam Welding ◽  
Measurement Data ◽  
Welding Process ◽  
Deep Penetration ◽  
Limited Information ◽  
Depth Measurement ◽  
Interferometric Measurement ◽  
Weld Depth

Analysing the quality of weld seams is still a challenging task. An optical inspection of the surface is giving limited information about the shape and depth of the weld seam. An application for laser beam welding with high demands regarding the weld depth consistency is the electrical contacting of battery cells. The batteries themselves have a limited terminal or case thickness that must not be penetrated during the welding process to avoid leakage or damage to the cell. That leads to a minimum weld depth to ensure the electrical functionality, and a maximum weld depth indicated by the case thickness. In such applications, a destructive analysis is not suitable which leads to the demand for a non-destructive measurement during the process. Using a coaxial, interferometric measurement setup, the keyhole depth during the deep penetration welding is measureable. For a keyhole with a depth of a couple of millimetres, such a system is commercially available. In micro scale, however, these systems are facing several challenges such as scanning systems, small spot diameters of a few tens of micrometres and narrow keyholes. This study contains an investigation of an interferometric measurement of the keyhole depth and the suitability for laser micro welding. Therefore, the data processing of the achieved measurements is investigated, and the results are compared with the depth measurement of metallographic analysed samples. Stainless steel is used to investigate the behaviour and the stability of developed data processing strategy and the resulting depth values.

A study of the shielding gas influence on the laser beam welding of AA5083 aluminium alloys by in-process spectroscopic investigation

2006 ◽  
Vol 44 (10) ◽  
pp. 1039-1051 ◽  
Author(s):  
Teresa Sibillano ◽  
Antonio Ancona ◽  
Vincenzo Berardi ◽  
Emanuela Schingaro ◽  
Giuseppe Basile ◽  
...  
Keyword(s):  
Laser Beam ◽  
Spectroscopic Investigation ◽  
Aluminium Alloys ◽  
Laser Beam Welding ◽  
Shielding Gas

Laser-Arc Hybrid Welding Process of Galvanized Steel Sheets

2008 ◽  
Vol 580-582 ◽  
pp. 355-358 ◽  
Author(s):  
Souta Matsusaka ◽  
Toshiro Uezono ◽  
Takuya Tsumura ◽  
Manabu Tanaka ◽  
Takehiro Watanabe
Keyword(s):  
Laser Beam ◽  
Welding Speed ◽  
High Speed ◽  
Incidence Angle ◽  
Welding Process ◽  
Galvanized Steel ◽  
Mag Welding ◽  
Hybrid Process ◽  
Deep Penetration ◽  
Steel Sheets

Galvanized steel sheets with a lap joint were welded by a laser-arc hybrid process. The hybrid system consisted of 2kW LD or YAG laser oscillator and frequency-modulated DC pulsed MAG welding machine. In this experiment, the arc traveled on the specimens, following the laser beam with the interval of 2 mm. The results showed that the hybrid process had some advantages, such as deep penetration depth, high welding speed and high gap-tolerance, in comparison with the conventional MAG welding. Observations from a high-speed digital video-camera suggested that the zinc and iron vapors induced by laser beam irradiation stabilized the arc plasma. Effects of the incidence angle between a welding head and a specimen on the weld bead formations were also discussed. As a result, the welding speed of 2.0 m/min was achieved at 1.0 mm of gap length condition when the incidence angle was 50 degree.

scholarly journals The bulging effect and its relevance in high power laser beam welding

2021 ◽  
Vol 1135 (1) ◽  
pp. 012003
Author(s):  
Antoni Artinov ◽  
Xiangmeng Meng ◽  
Nasim Bakir ◽  
Ömer Üstündağ ◽  
Marcel Bachmann ◽  
...  
Keyword(s):  
Laser Beam ◽  
Penetration Depth ◽  
Weld Pool ◽  
High Power ◽  
High Speed ◽  
Laser Beam Welding ◽  
Hot Cracking ◽  
Alloying Elements ◽  
High Power Laser ◽  
Power Laser

Abstract The present work deals with the recently confirmed widening of the weld pool interface, known as a bulging effect, and its relevance in high power laser beam welding. A combined experimental and numerical approach is utilized to study the influence of the bulge on the hot cracking formation and the transport of alloying elements in the molten pool. A technique using a quartz glass, a direct-diode laser illumination, a high-speed camera, and an infrared camera is applied to visualize the weld pool geometry in the longitudinal section. The study examines the relevance of the bulging effect on both, partial and complete penetration, as well as for different sheet thicknesses ranging from 8 mm to 25 mm. The numerical analysis shows that the formation of a bulge region is highly dependent on the penetration depth and occurs more frequently during partial penetration above 6 mm and complete penetration above 8 mm penetration depth, respectively. The location of the bulge correlates strongly with the cracking location. The obtained experimental and numerical results reveal that the bulging effect increases the hot cracking susceptibility and limits the transfer of alloying elements from the top of the weld pool to the weld root.

scholarly journals Numerical Study on the Influence of the Plasma Properties on the Keyhole Geometry in Laser Beam Welding

2022 ◽  
Vol 9 ◽  
Author(s):  
Donato Coviello ◽  
Antonio D’Angola ◽  
Donato Sorgente
Keyword(s):  
Laser Beam ◽  
Numerical Study ◽  
Laser Beam Welding ◽  
Welding Process ◽  
Beam Power ◽  
Deep Penetration ◽  
Multiple Reflections ◽  
Absorption Mechanism ◽  
Plasma Properties ◽  
Workpiece Surface

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.

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