Low-spatter high speed welding by use of local shielding gas flows

Schmidt, Leander; Hickethier, Steen; Schricker, Klaus; Bergmann, Jean Pierre

doi:10.1117/12.2507024

Cited by 8 publications

(8 citation statements)

References 7 publications

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“…Figure 1b shows a visualized flow pattern of helium, whereby the gas was used exemplary for illustration reasons due the high difference in density. Otherwise, the experiments were carried out using argon, to ensure comparable test conditions to preliminary investigations [29,30]. Further details in schlieren imaging are given in [31].…”

Section: Methodsmentioning

confidence: 99%

“…In this way, the system could be positioned with an accuracy of 0.05 mm and a reproducibility of 0.02 mm. Based on the findings of preliminary investigations [29,30], the nozzle was set to a trailing flow orientation with an angle of incidence of α = 48, while these settings resulted in the maximum reduction of loss of mass. This should ensure a direct interaction of the gas flow and the keyhole rear wall.…”

Section: Methodsmentioning

confidence: 99%

“…A study about the influence of a local gas flow at welding speeds above 5 m/min has not been sufficiently investigated so far. Based on the latest investigations on partial penetration welding [29,30], this publication focusses on the influence of local gas flows on full penetration welding of high-alloy steel AISI304 (1.4301, X5CrNi18-10) at welding speeds from 8 m/min to 16 m/min. For this purpose, a novel experimental setup was developed, in order to characterize the effect of the gas flow on the stability of the keyhole and melt pool dynamics.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Local Gas Flow in Full Penetration Laser Beam Welding with High Welding Speeds

et al. 2020

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Spatter formation is a major issue in deep penetration welding with solid-state lasers at high welding speeds above 8 m/min. In order to limit spatter formation, the use of local gas flows represents a technically feasible solution. By using the gas flow, the pressure balance inside the keyhole, and therefore the keyhole stability, is affected. Existing investigations demonstrate a reduction in spatter and pore formation for partial penetration welding up to a welding speed of 5 m/min. However, the effect of the gas flow is not yet clarified for full penetration welding at welding speeds above 8 m/min. By using a precisely adjustable shielding gas supply, the effect of a local gas flow of argon was characterized by welding stainless steel AISI304 (1.4301/X5CrNi18-10). The influence of the gas flow on the melt pool dynamics and spatter formation was recorded by means of high-speed videography and subsequently analyzed by image processing. Schlieren videography was used to visualize the forming flow flied. By the use of the gas, a change in melt pool dynamics and gas flow conditions was observed, correlating to a reduction in loss of mass up to 70%. Based on the investigations, a model of the acting effect mechanism was given.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of Local Gas Flow in Full Penetration Laser Beam Welding with High Welding Speeds

et al. 2020

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“…Recent investigations obtained a loss of mass reduction of up to 91% with an argon gas flow under low flow rates (≤4.8 L/min) [32]. In addition, the geometry of the keyhole was affected for partial [33] and full penetration welding [34] and for the welding of lap joints [35]. The influence of the gas flow on the pressure balance in the keyhole was estimated in [33] combining investigations in [36,37].…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the geometry of the keyhole was affected for partial [33] and full penetration welding [34] and for the welding of lap joints [35]. The influence of the gas flow on the pressure balance in the keyhole was estimated in [33] combining investigations in [36,37]. Also, in [38] the gas flow was mentioned as a mechanism to stabilize the keyhole and to reduce spatter formation.…”

Section: Introductionmentioning

confidence: 99%

Interaction between Local Shielding Gas Supply and Laser Spot Size on Spatter Formation in Laser Beam Welding of AISI 304

Diegel,

Mattulat,

Schricker

et al. 2023

Applied Sciences

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Background. Spatter formation at melt pool swellings at the keyhole rear wall is a major issue for laser deep penetration welding at speeds beyond 8 m/min. A gas nozzle directed towards the keyhole, that supplies shielding gas locally, is advantageous in reducing spatter formation due to its simple utilization. However, the relationship between local gas flow, laser spot size, and the resulting effects on spatter formation at high welding speeds up to 16 m/min are not yet fully understood. Methods. The high-alloy steel AISI 304 (1.4301/X5CrNi18-10) was welded with laser spot sizes of 300 μm and 600 μm while using a specially designed gas nozzle directed to the keyhole. Constant welding depth was ensured by Optical Coherence Tomography (OCT). Spatter formation was evaluated by precision weighing of samples. Subsequent processing of high-speed images was used to evaluate spatter quantity, size, and velocity. The keyhole oscillation was determined by Fast Fourier Transform (FFT) analysis. Tracking the formation of melt pool swellings at the keyhole rear wall provided information on the upward melt flow velocity. Results. The local gas flow enabled a significant reduction in the number of spatters and loss of mass for both laser spot sizes and indicated an effect on surface tension by shielding the processing zone from the ambient atmosphere. The laser spot size affected the upward melt flow velocity and spatter velocity.

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Effect of partial and global shielding on surface-driven phenomena in keyhole mode laser beam welding

Schmidt,

Schricker,

Diegel

et al. 2023

Weld World

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Partial shielding by means of local gas supply has proven to be very effective in reducing spatter. Besides the effect of gas-induced dynamic pressure, the shielding of oxygen is also highly relevant for melt pool dynamics and spatter formation due to the growth of oxides and the influence on surface tension. Therefore, this paper addresses the effect of local supplied argon on oxide growth and seam topography during keyhole mode laser beam welding of high-alloy steel AISI 304. To determine the shielding quality, the results are compared to laser beam welding in a global argon atmosphere. The topography of the upper weld seams was analyzed by scanning electron microscopy (SEM). An X-ray microanalysis (EDX) in line scan modus was performed to determine and to locate the elements which are covering the specimen surface. The chemical state of the found elements was quantified by X-ray photoelectron spectroscopy (XPS). In a last step, high-speed synchrotron X-ray imaging was performed to separate the effect of the gas-induced pressure and the gas-induced shielding on keyhole geometry. The results show that a local supply of argon contributes to a significant difference in oxide growth, affecting melt pool convection and weld seam geometry. It was further shown that the effect of gas flows at low flow rates is primarily because of oxygen shielding, as no significant difference in keyhole geometry was found by high-speed synchrotron X-ray imaging.

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Low-spatter high speed welding by use of local shielding gas flows

Cited by 8 publications

References 7 publications

Effect of Local Gas Flow in Full Penetration Laser Beam Welding with High Welding Speeds

Effect of Local Gas Flow in Full Penetration Laser Beam Welding with High Welding Speeds

Interaction between Local Shielding Gas Supply and Laser Spot Size on Spatter Formation in Laser Beam Welding of AISI 304

Effect of partial and global shielding on surface-driven phenomena in keyhole mode laser beam welding

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