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Applied Sciences
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Model of Laser Welding
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Model of Laser Welding

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Optics and Lasers".

Deadline for manuscript submissions: closed (15 February 2020) | Viewed by 12045

Special Issue Editor

Prof. Dr. Jean-Pierre Bergmann

E-Mail Website
Guest Editor
Department of Production Technology, Technische Universitaet Ilmenau, 98693 Ilmenau, Germany
Interests: laser welding; joining; US-welding; friction-stir welding; digitalization
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The development of new high intensity laser sources with lower wavelengths presents new challenges and phenomena for the welding pool and key hole, especially for steel and aluminum. High intensity IR lasers show high spatter formation at high speed before the pre-humping regime, while green lasers show different behaviors during the transition from heat conduction to key-hole welding. This Special Issue focuses on models resulting from experimental investigation as well as modeling and simulation approaches that can aid in the understanding of melt flow conditions around the key hole and can be used to evaluate key hole dynamics. In addition, papers correlating spatter formation with the manipulation of the melt pool and key hole dynamics are welcome.

Prof. Dr. Jean-Pierre Bergmann
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • key hole dynamics
  • spatter formation
  • green laser
  • humping
  • pressure in key hole
  • melt pool dynamics

Published Papers (3 papers)

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Research

9 pages, 2675 KiB  
Article
High-Speed X-Ray Investigation of Pore Formation during Full Penetration Laser Beam Welding of AA6016 Aluminum Sheets Contaminated with Lubricants
by Christian Hagenlocher, Jannik Lind, Rudolf Weber and Thomas Graf
Appl. Sci. 2020, 10(6), 2077; https://doi.org/10.3390/app10062077 - 19 Mar 2020
Cited by 9 | Viewed by 2646
Abstract
The presence of lubricants on the surface of sheets favors the formation of pores in laser welded seams. This formation process was investigated by means of high-speed X-ray imaging of the full penetration laser beam welding process of two AA6016 aluminum sheets in [...] Read more.
The presence of lubricants on the surface of sheets favors the formation of pores in laser welded seams. This formation process was investigated by means of high-speed X-ray imaging of the full penetration laser beam welding process of two AA6016 aluminum sheets in overlap configuration. The measurement of the growth velocity of the bubbles indicated their sudden growth once they started to form. Further analysis of the X-ray images identified the point of origin of the pores: a few millimeters behind the capillary between the two aluminum sheets. The study shows that the lubricant does not affect the stability of the capillary, which evidences that the formation of these pores is not caused by the fluctuations of the capillary. These results explain for the first time why pore formation cannot be avoided by process strategies, which stabilize the capillary, when welding uncleaned sheets. Full article
(This article belongs to the Special Issue Model of Laser Welding)
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19 pages, 8664 KiB  
Article
Effect of Local Gas Flow in Full Penetration Laser Beam Welding with High Welding Speeds
by Leander Schmidt, Klaus Schricker, Jean Pierre Bergmann and Christina Junger
Appl. Sci. 2020, 10(5), 1867; https://doi.org/10.3390/app10051867 - 09 Mar 2020
Cited by 20 | Viewed by 4543
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Model of Laser Welding)
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22 pages, 3642 KiB  
Article
Depth Dependence and Keyhole Stability at Threshold, for Different Laser Welding Regimes
by Remy Fabbro
Appl. Sci. 2020, 10(4), 1487; https://doi.org/10.3390/app10041487 - 21 Feb 2020
Cited by 33 | Viewed by 4453
Abstract
Depending of the laser operating parameters, several characteristic regimes of laser welding can be observed. At low welding speeds, the aspect ratio of the keyhole can be rather large with a rather vertical cylindrical shape, whereas at high welding speeds, low aspect ratios [...] Read more.
Depending of the laser operating parameters, several characteristic regimes of laser welding can be observed. At low welding speeds, the aspect ratio of the keyhole can be rather large with a rather vertical cylindrical shape, whereas at high welding speeds, low aspect ratios result, where only the keyhole front is mainly irradiated. For these different regimes, the dependence of the keyhole (KH) depth or the keyhole threshold, as a function of the operating parameters and material properties, is derived and their resulting scaling laws are surprisingly very similar. This approach allows us to analyze the keyhole behavior for these welding regimes, around their keyhole generation thresholds. Specific experiments confirm the occurrence and the behavior of these unstable keyholes for these conditions. Furthermore, recent experimental results can be analyzed using these approaches. Finally, this analysis allows us to define the aspect ratio range for the occurrence of this unstable behavior and to highlight the importance of laser absorptivity for this mechanism. Consequently, the use of a short wavelength laser for the reduction of these keyhole stability issues and the corresponding improvement of weld seam quality is emphasized. Full article
(This article belongs to the Special Issue Model of Laser Welding)
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